Download - Lte Coverage and Capacitry Dimensioning
Long Term Evolution (LTE) Access NetworkCoverage and Capacity Dimensioning
This thesis submitted in partial fulfillment of the requirementsfor thedegree of high diploma in wireless telecommunicationsystem.
Submitted by
● Amr Abdel-Magid Kassab
● Amr Mahmoud Morsy
● Mohammed Mahmoud Mohammed Saad
● Mohamed Mahmoud Mohamed Tantawy
● Mohamed Morsy Mohamed
● Hanaa Abdelmoety Kamel
● Walaa Abd-Elhamid Elawam
Supervised By
Dr.Hamed Abdel Fatah El Shenawy
Cairo 2013
Ministry of Higher Education
National Telecommunication Institute
Electronics and Communications Department
Acknowledgements
First of all, we are grateful to ALLAHALMIGHTY, the most merciful,the most beneficent, who gave us strength, guidance and abilities tocomplete this thesis in a successful manner.
We are thankful to our parents and our teachers that guided us throughoutour career path especially in building up our base in education andenhance our knowledge.
We are indebted to our supervisor Dr. Hamed Abd El Fattah ElShenawyfor his supervision and his co-operation and support really helped uscompleting our project.
Abstract
Long Term Evolution (LTE) is set of enhancement to the currentcellular system in use. LTE is designed to have scalable channelbandwidth up to 20MHz, with low latency and packet optimized radioaccess technology. The peak data rate of LTE is 100 Mbps in downlinkand 50 Mbps in the uplink.
LTE support both FDD and TDD duplexing.
LTE with OFDM technology in the down link, which provideshigher spectral efficiency and more robustness against multipath fading
LTE with SC-FDMA in the uplink LTE
LTE with different MIMO configurations
Dimensioning is initial phase of network planning. It provides estimateof the network elements count as well as the capacity of those elements.The purpose of our project to estimate the required number ofeNodeBs needed to support users with certain traffic load with adesired level of quality of service (QOS) and cover the area ofinterest.
This estimate fulfills coverage requirements and verified for capacityrequirements .
Coverage dimensioning occurs via radio link budget (RLB), maximumallowable propagation path loss (MAPL) is obtained. MAPL is convertedinto cell radius by using appropriate propagation models. The radius ofthe cell is used to calculate the number of sites required to cover the areaof interest. The cell size and the site count are obtained.
Capacity planning deals with the ability of the network to provideservices to certain numbers of users with a desired level of quality ofservice (QOS).
Capacity based site count is compared with coverage based site count.The greater one is selected as the final site count.
Project objectives
Overview of LTE system architecture and specifications Dimensioning of LTE Network Coverage dimensioning via radio link budget and propagation
models Capacity dimensioning Numerical results using Visual Studio and basic language Conclusions and suggestions for future work.
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List of Contents
Item Page
1.0 Chapter One: Overview of LTE 1-1
1.1 Introduction 1-2
2.2 IMT-Advanced 1-2
1.3 LTE specifications 1-4
LTE Architecture 1-15
2.0 Chapter Two: LTE network dimensioning 2-1
2.1 Introduction 2-2
2.2 LTE network dimensioning 2-2
2.3 LTE network dimensioning inputs 2-6
2.4 Coverage planning inputs 2-7
2.5 Capacity planning inputs 2-8
2.6 LTE network dimensioning outputs 2-8
2.7 Comparison among dimensioning, planning, optimization 2-9
3.0 Chapter Three: Coverage dimensioning 3-1
3.1 Introduction 3-2
3.2 Concepts and Terminology 3-4
3.3 Link Budget Definition 3-5
3.4 Why we use Link Budget? 3-6
3.5 What are the types of Link Budget? 3-6
3.6 Up Link Budget (Up Link coverage) 3-7
3.7 Up Link Budget entries 3-7
3.8 Morphologies Classifications 3-28
3.9 Down Link Budget(Down Link coverage) 3-29
3.10 Down Link limited Link Budget 3-35
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3.11 propagation models 3-37
3.12 Classifications of propagation models 3-39
3.13 Ericsson variant COST 231 Okomara-Hata wave propagation
model
3-42
4.0 Chapter Four: Capacity dimensioning 4-1
4.1 Introduction 4-2
4.2 Uplink capacity 4-3
4.3 Downlink capacity 4-6
4.4 Application or service distribution model 4-13
5.0 Chapter Five: numerical results 5-1
5.1 Uplink budget 5-3
5.2 Effects on cell Radius (R) 5-17
5.3 Downlink capacity 5-21
6.0 Chapter Six: conclusion and suggestions for future work 6-1
6.1 Conclusion 6-2
6.2 Suggestions for future work 6-3
iii
List of figures
Items PageFigure(1-1) Overview of IMT advanced 1-2
Figure(1-2) Resource element and resource block 1-14
Figure(1-3) LTE architecture 1-15
Figure(1-4) Evolved Packet System 1-15
Figure(2-1) LTE network planning process 2-2
Figure(2-2) Dimensioning basic steps 2-3
Figure(2-3) LTE network dimensioning inputs 2-6
Figure(2-4) LTE coverage planning 2-7
Figure(2-5) LTE dimensioning outputs 2-9
Figure(2-6) LTE optimization process stages 2-10
Figure(2-7) LTE optimization process 2-11
Figure(2-8) LTE optimization process 2-16
Figure(3-1) LTE Dimensioning Process 3-4
Figure(3-2) Resource Block Definition in Frequency
Domain.
3-11
Figure(3-3) Downlink and Uplink User Scheduling in Time
and Frequency Domain.
3-12
Figure (4.1) channel bandwidth partitioning 4-22
Figure (4-2) subscriber class deployment model 4-29
Figure(5-1) flowchart of effective isotropic radiated power 5-3
Figure(5-2) Effective Isotropic Radiated Power 5-3
Figure(5-3) flowchart of sensitivity of eNodeB 5-5
Figure(5-4) Sensitivity of Enhanced nodeB 5-5
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Figure(5-5) flowchart of Interference Margin 5-7
Figure(5-6) flowchart of Log Normal Fading Margin 5-7
Figure(5-7) flowchart of total margins 5-8
Figure(5-8) Total margin 5-8
Figure(5-9) flowchart of total gains 5-10
Figure(5-10) flowchart of total losses 5-10
Figure(5-11) total gains and total losses 5-11
Figure(5-12) flowchart of maximum allowable path loss 5-12
Figure(5-13) Max. allowable path loss 5-13
Figure(5-14) flowchart of cell radius using Ericson variant
Okumara -Hata
5-14
Figure(5-15) flowchart of site count 5-15
Figure(5-16) cell radius and Site Count 5-15
Figure(5-17) the effect of cell Loading Factor (Q) on the cell
Radius (R) Omni
5-17
Figure(5-18) the effect of cell Loading Factor (Q) on the cell
Radius (R) 3 sector
5-18
Figure(5-19) the effect of morphology on the cell Radius (R)
omni
5-19
Figure(5-20) the effect of morphology on the cell Radius (R) 3
sector
5-20
Figure(5-21) downlink capacity 5-21
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List of tables
Item Page
Table(1-1) Improvement in downlink spectral efficiency going
from 2G to 4G System
1-7
Table (1-2) Targets for average spectrum efficiency 1-8
Table (3-1) Bandwidths and number of physical resource
blocks
3-16
Table(3-2) Channel models specifications 1 3-18
Table (3-3) Channel models specifications 2 3-18
Table(3-4) Channel propagation conditions 3-19
Table(3-5) Maximum Doppler frequency for each channel
model
3-19
Table(3-6) Semi –empirical parameters for uplink 3-21
Table(3-7) Examples of F for varying tilt 3-23
Table(3-8) Lognormal fading margins for varying standard
deviation of log normal fading
3-24
Table(3-9) Values of penetration loss on different morphology
classes
3-26
Table(3-10) Summarizes the features of different morphologies 3-28,
3-29
Table(3-11) Examples of Fc at cell edge for varying tilt 3-33
Table(3-12) Semi –empirical parameters for downlink 3-33
Table(3-14) Fixed attenuation A in Ericsson variant COST 231
Okumara Hata propagation models
3-43
Table(4-1) SINR values corresponding to each modulation
coding scheme (MCS)
4-4
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Table(4-2) semi- empirical parameters for up link 4-5
Table(4-3) Semi- empirical parameters for downlink 4-11
Table (4.5) applications or services distribution model 4-14
Table (4.6) mobile service flows and QoS parameters 4-19
Table (4.7) subscriber class distribution model 4-28
Table (4.8) subscriber class traffic model 4-30
Table (5-1) Default values of User Equipment Effective
Isotropic Radiated Power(EIRP)
5-4
Table(5-2) Default values of Enhanced NodeB sensitivity 5-6
Table(5-3) Default values of total margin 5-9
Table(5-4) Default values of total Gain and losses 5-12
Table(5-5) Default values of Maximum allowable path loss
(MAPL)
5-14
Table(5-6) values of Cell Radius and Site count with
difference Base stations heights
5-16
Table(5-7) The effect of cell Loading Factor (Q) on the cell
Radius (R) Omni
5-17
Table(5-8) The effect of cell Loading Factor (Q) on the cell
Radius (R) 3 sector
5-18
Table(5-9) the effect of morphology on the cell Radius (R)
omni
5-19
Table(5-10) the effect of morphology on the cell Radius (R) 3
sector
5-20
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List of Acronyms and Abbreviations
16QAM: 16 point quadrature amplitude modulation
3GPP: Third Generation Partnership
٦٤QAM: 64 point quadrature amplitude modulation
3G: third generation
4G: fourth generation
AACK: Acknowledgement
AGC: Automatic Gain Control
AP: Access Point
ARQ: Automatic Repeater Request
AUC: Authentication center
A/D: Analog to digital
ADSL: Assymetric Digital Subscriber Line
AMPS: Advanced Mobile Phone Services
AWGN: Additive White Gaussian Noise
BBCH: Broadcast Channel
BPSK: Binary Phase Shift Keying
BSC: Base Station Controller
BTS: Base Transceiver Station
BW: Bandwidth
BER: Bit Error Rate
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CCDMA: Code Division Multiple Access
CW: Continuous Wave
CPL: Car Penetration Loss
COST: Community Collaborative studies in the areas of science and
technology
DDL: Downlink
DSL: Digital Subscriber Line
D/A: Digital to analog
DU: Dense Urban
EEDGE: Enhanced Data Rate for GSM Evolution
EIR: Equipment Identity Register
EIRP: Effective Isotropic Radiated Power
eNodeB: Enhanced NodeB (enhanced base station)
EPA: extended pedestrian
ETU: extended terrestrial
EVA: extended vehicular
EPC: Evolved Packet Core
EPS: Evoved Packet System
FFDD: Frequency Division Duplex
FDMA: Frequency Division Multiple Access
FTT: Fast Fourier Transform
FM: Frequency Modulation
FWLL: Fixed Wireless Local Loop
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FFM: Fast Fading Margin
GGGSN: Gateway GPRS Serving Node
GMSC: Gateway Mobile Switching Center
GMSK: Gaussian Minimum Shift Keying
GSM: Global System for Mobile
GPRS: General Packet Radio Service
GUI: Graphical User Interface
HHARQ: Hybrid Automatic Repeater Request
HLR: Home Location Register
HSCSD: High Speed Circuit Switched Data
HSDPA: High Speed Downlink Packet Access
HSS: Home Subscriber Server
HSUPA: High Speed Uplink Packet Access
IIMS: IP Multimedia Subsystem
IM: Interference Margin
IP: Internet Protocol
KKPI: Key Performance Indicator
LLTE: Long Term Evolution
MMBMS: Multimedia broadcast multicast services
MB-SFN: Multicast/broadcast-single frequency network
x
MIMO: Multi Input Multi Output
MME: Mobile Mobility Management Entity
MRC: Maximal ratio combining
MS: mobile Station
MSC: Mobile Switching Center
MAPL: Maximum Allowable Path Loss
OOFDM: Orthogonal Frequency Division Multiplexing
OMC: Operation and Maintenance Center
PPAPR: Peak -to-average power ratio
PCRF: Policy and Charging Rules Function
PDCCH: Physical downlink control channel
PDN: Public Data Network
PLMN: Public land Mobile Network
PRB: Physical Resource Block
PSK: Phase Shift Keying
PSTN: Public Switched Telephone Network
P-GW: PDN Gateway
PUCCH: Physical Uplink Control Channel
PDCCH: Physical Downlink Control Channel
QQAM: Quadrature Amplitude Modulation
QPSK: Quadrature phase shift Keying
QOS: Quality Of Service
xi
RRFPA: Radio Frequency Power Amplifier
RNC: Radio Network Controller
RLB: Radio Link Budget
SSC-FDMA: Single Carrier-Frequency Division Multiple Access
SGSN: Serving GPRS Support Node
SIM: Subscriber Identity Module
SINR: Signal Interference -to-noise ratio
S-GW: Serving Gateway
SRVCC: Single Radio Voice Call Continuity
SMS: Short Message Service
SU: Sub Urban
TTDD: Time Division Duplexing
TDMA: Time Division Multiple Access
TMA: Tower Mounted Amplifier
UUE: User Equipment
UL: Uplink
UMTS: Universal Mobile Telecommunication system
UTRAN: UMTS Terrestrial Radio Access Network
VVLR: Visitor Location Register
VOIP: Voice over IP
xii
W
WCDMA: Wideband Code Division Multiple Access
WIMAX: Worldwide Interoperability for Microwave Access
Chapter One
Overview of Long Term Evolution (LTE)
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 2
Chapter one
Overview of Long Term Evolution (LTE)
1.1. Introduction
LTE is designed to meet users need for high speed data and media
transport as well as high-capacity voice support .The LTE PHY employs
some advanced Technologies that are new to mobile applications these
include OFDMA -SC-FDMA –MIMO. The LTE PHY uses OFDMA in
downlink and SC-FDMA on up link.
Figure (1-1) Overview of IMT Advanced
1.2. IMT-Advanced
International Mobile Telecommunications Advanced (IMT-
Advanced) is requirements issued by the ITU-R of the International
Telecommunication Union (ITU) in 2008 for what is marketed as 4G
mobile phone and Internet access service.
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 3
1.2.1 IMT ADVANCED Requirements
Specific requirements of the IMT-Advanced report included:
1- Based on an all-Internet Protocol (IP) packet switched network
2- Interoperability with existing wireless standards
3- A nominal data rate of 100 Mbit/s while the client physically
moves at high speeds relative to the station,50 Mbit /s in the uplink
and 1 Gbit/s while client and station are in relatively fixed
positions.
4- Dynamically share and use the network resources to support more
simultaneous users per cell.
5- Scalable channel bandwidth 1.4 MHz, 3 MHz, 5 MHz, 15 MHz
and 20 MHz optionally up to 40
6- Peak link spectral efficiency of 15 bit/s/Hz in the downlink, and
6.25bit/s/Hz in the uplink (meaning that 1 Gbit/s in the downlink
should be possible over less than 67 MHz bandwidth)
7- System spectral efficiency of up to 3 bit/s/Hz/cell in the downlink
and 2.25 bit/s/Hz/cell for indoor usage
8- Seamless connectivity and global roaming across multiple
networks with smooth handovers
9- Ability to offer high quality of service for multimedia support
10- support antenna configurations
a- Downlink 4×2, 2×2, 1×2, 1×1
b- Uplink 1×2, 1×1
11- coverage
a- full performance up to 5 km
b-slight degradation 5 km-30 km
c-operation up to 100 km should not be precluded by standard
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 4
12- mobility
a- optimized for low speed less than 15 km per hour
b-high performance at speeds up to 120 km per hour
c-maintain link at speeds up to 350 km per hour
13- LTE support efficient broadcast mode performance :multicast and
broadcast
14- broadcast spectral efficiency 1bit /sec/Hz
15- LTE support paired and unpaired frequency band
16- It support FDD and TDD, half duplex TDD
17- Support adaptive modulation technique: High level and low level
modulation
18- Support scalable FFT size
19- It support turbo code
20- It support low complexity low cost terminal
21- Support VOIP 60 session /Hz/cell
22- Support of cell sizes from tens of meters of radius (femto and Pico
cells) up to over 100 km radius microcells
23- Simplified architecture: The network side of EUTRAN is
composed only by the enodeBs.
24- Low data transfer latencies (sub-5ms latency for small IP packets
in optimal conditions), lower latencies for handover and connection
setup time.
1.3 LTE specifications1.3.1 Peak Rates and Peak Spectral Efficiency
For Data rate many services with lower data rates such as voice
services are important and still occupy a large part of a mobile network’s
overall capacity, but it is the higher data rate services that drive the design
Chapter 1: Overview of Long Term Evolution (LTE)
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of the radio interface. The ever increasing demand for higher data
rates for web browsing, streaming and file transfer pushes the peak
data rates for mobile systems from kbit/s for 2G, to Mbit/s for 3G and
getting close to Gbit/s for 4G (Erik Dahlman, Stefan Parkvall, and Johan
Sköld, 2011). For marketing purposes, the first parameter by which
different radio access technologies are usually compared is the peak per-
user data rate which can be achieved. This peak data rate generally scales
according to the amount of spectrum used, and, for MIMO systems,
according to the minimum of the number of transmit and receive
antennas.
The peak data rate can be defined as the maximum throughput per user
assuming the whole bandwidth being allocated to a single user with the
highest modulation and coding scheme and the maximum number of
antennas supported. Typical radio interface overhead (control channels,
pilot signals, guard intervals, etc.) is estimated and taken into account for
a given operating point. For TDD systems, the peak data rate is generally
calculated for the downlink and uplink periods separately. This makes it
possible to obtain a single value independent of the uplink/downlink ratio
and a fair system comparison that is agnostic of the duplex mode. The
maximum spectral efficiency is then obtained simply by dividing the peak
rate by the used spectrum allocation.
The target peak data rates for downlink and uplink in LTE Release 8
were set at 100 Mbps and 50 Mbps respectively within a 20 MHz
bandwidth, 7 corresponding to respective peak spectral efficiencies of 5
and 2.5 bps/Hz. The underlying assumption here is that the terminal has
two receive antennas and one transmit antenna. The number of antennas
used at the base station is more easily upgradeable by the network
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 6
operator, and the first version of the LTE specifications was
therefore designed to support downlink MIMO operation with up to four
transmit and receive antennas.
When comparing the capabilities of different radio communication
technologies, great emphasis is often placed on the peak data rate
capabilities. While this is one indicator of how technologically advanced
a system is and can be obtained by simple calculations, it may not be a
key differentiator in the usage scenarios for a mobile communication
system in practical deployment. Moreover, it is relatively easy to design a
system that can provide very high peak data rates for users close to the
base station, where interference from other cells is low and techniques
such as MIMO can be used to their greatest extent. It is much more
challenging to provide high data rates with good coverage and mobility,
but it is exactly these latter aspects which contribute most strongly to user
satisfaction.
In typical deployments, individual users are located at varying
distances from the base stations, the propagation conditions for radio
signals to individual users are rarely ideal, and the available resources
must be shared between many users. Consequently, although the claimed
peak data rates of a system are genuinely achievable in the right
conditions, it is rare for a single user to be able to experience the peak
data rates for a sustained period, and the envisaged applications do not
usually require this level of performance. A differentiator of the LTE
system design compared to some other systems has been the recognition
of these „typical deployment constraints‟ from the beginning. During the
design process, emphasis was therefore placed not only on providing a
competitive peak data rate for use when conditions allow, but also
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 7
importantly on system level performance, which was evaluated during
several performance verification steps.
System-level evaluations are based on simulations of multicell
configurations where data transmission from/to a population of mobiles is
considered in a typical deployment scenario. The sections below describe
the main metrics used as requirements for system level performance. In
order to make these metrics meaningful, parameters such as the
deployment scenario, traffic models, channel models and system
configuration need to be defined (Stefanie Sesia, Issam Toufik and
Matthew Baker, 2011).
Table (1-1): Improvement in downlink spectral efficiency going from 2G
to 4G System
1.3.2 Spectrum efficiency
In this section, the target for peak spectrum efficiency, the average
spectrum efficiency, and cell edge spectrum efficiency are defined. The
target for average spectrum efficiency and the cell edge user throughput
efficiency should be given a higher priority than the target for peak
spectrum efficiency and VoIP capacity. The target for average spectrum
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 8
efficiency and the cell edge spectrum efficiency should be achieved
simultaneously.
The peak spectrum efficiency is the highest data rate normalized by
overall cell bandwidth assuming error-free conditions, when all available
radio resources for the corresponding link direction are assigned to a
single UE. The system target to support downlink peak spectrum
efficiency of 30 bps/Hz and uplink peak spectrum efficiency of 15
bps/Hz. Assumption of antenna configuration is (8x8) or less for DL and(
4x4) or less for UL Average spectrum efficiency is defined as the
aggregate throughput of all users (the number of correctly received bits
over a certain period of time) normalized by the overall cell bandwidth
divided by the number of cells. The average spectrum efficiency is
measured in b/s/Hz/cell. Advanced E-UTRA should target the average
spectrum efficiency to be as high as possible, given a reasonable system
complexity. The expectation at the end of the study item is that the values
of all the targets (of the different configurations) will be made available,
but currently the evaluation for the blanked out boxes in the table below,
are a lower priority. Advanced E-UTRA should target the average
spectrum efficiencies in different environments in Table (2-2).
Table (1-2): Targets for average spectrum efficiency
Chapter 1: Overview of Long Term Evolution (LTE)
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1.3.3 Cell edge user throughput
The cell edge user throughput is defined as the 5% point of CDF of
the user throughput normalized with the overall cell bandwidth.
Advanced E-UTRA should target the cell edge user throughput to be as
high as possible, given a reasonable system complexity.
A more homogeneous distribution of the user experience over the
coverage area is highly desirable and therefore a special focus should be
put on improving the cell edge performance.
The expectation at the end of the study item is that the values of all the
targets (of the different configurations) will be made available, but
currently the evaluation for the blanked out boxes in the table below, are
a lower priority. Advanced E- UTRA should target the cell edge user
throughput below in different environments
1.3.4 Voice Capacity (VOIP)
VoIP services convert your voice into a digital signal that
travels over the Internet. If you are calling a regular phone number, the
signal is converted to a regular telephone signal before it reaches the
destination. VoIP can allow you to make a call directly from a computer,
a special VoIP phone, or a traditional phone connected to a special
adapter. In addition, wireless "hot spots" in locations such as airports,
parks, and cafes allow you to connect to the Internet and may enable you
to use VoIP service wirelessly.
Some VoIP providers offer their services for free, normally only for
calls to other subscribers to the service. Your VoIP provider may permit
you to select an area code different from the area in which you live. It
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 10
also means that people who call you may incur long distance charges
depending on their area code and service.
Some VoIP providers charge for a long distance call to a number outside
your calling area, similar to existing, traditional wire line telephone
service. Other VoIP providers permit you to call anywhere at a flat rate
for a fixed number of minutes.
Depending upon your service, you might be limited only to other
subscribers to the service, or you may be able to call anyone who has a
telephone number - including local, long distance, mobile, and
international numbers. If you are calling someone who has a regular
analog phone, that person does not need any special equipment to talk to
you. Some VoIP services may allow you to speak with more than one
person at a time. Some VoIP services offer features and services that are
not available with a traditional phone, or are available but only for an
additional fee. You may also be able to avoid paying for both a
broadband connection and a traditional telephone line. If you're
considering replacing your traditional telephone service with VoIP, there
are some possible differences. Some VoIP services don't work during
power outages and the service provider may not offer backup power. Not
all VoIP services connect directly to emergency services through 9-1-1.
For additional information VoIP providers may or may not offer directory
assistance/white page listings.
1.3.5 Mobility
The system shall support mobility across the cellular network for
various mobile speeds up to 350km/h (or perhaps even up to 500km/h
depending on the frequency band). System performance shall be
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 11
enhanced for 0 to 10km/h and preferably enhanced but at least no worse
than E-UTRAand E-UTRAN for higher speeds.
1.3.6 Control Plane and User Plane Latency
Control plane deals with signaling and control functions, while
user plane deals with actual user data transmission. C-Plane latency is
measured as the time required for the UE (User Equipment) to transit
from idle state to active state. In idle state, the UE does not have an
Reconnection.
Once the RRC is setup, the UE transitions to connected state and then to
the active state when it enters the dedicated mode. U-Plane latency is
defined as one way state when it enters the dedicated mode. U-Plane
latency is defined as one-way transmit time between a packet being
available at the IP layer in the UE/E-UTRAN (Evolved UMTS Terrestrial
Radio Access Network) edge node and the availability of this packet at
the IP layer in the EUTRAN/ UE node.
U-Plane latency is relevant for the performance of many applications.
This tutorial presents in detail the delay budgets of C-Plane and U-Plane
procedures that add to overall latency in state transition and packet
transmission. Latency calculations are made for both FDD and TDD
modes of operation. Technical details of C-Plane and U-Plane latency
.This tutorial is organized as follows: Requirements and assumptions in
Section This tutorial presents in detail the delay budgets of C- Plane and
U-Plane procedures that add to overall latency in state transition and
packet transmission. Latency calculations are made for both FDD and
TDD modes of operation. Technical details of C-Plane and U-Plane
latency are cited in This tutorial is organized as follows: Requirements
Chapter 1: Overview of Long Term Evolution (LTE)
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and assumptions in Section II, C- Plane latency analysis in Section III and
U-Plane latency analysis in Section IV. The conclusions are summarized
in Section V. All the values indicated in the tables are in mill seconds
(ms). The method of calculating these latencies is illustrated in the
appendix.
Low latency where5 ms user plane latency for small IP packets (user
equipment to radio access network [RAN] edge) .100 ms camped to
active. 50 ms dormant to active.
Scalable bandwidth where the 4G channel offers four times more
bandwidth than current 3G systems and is scalable. So, while 20 MHz
channels may not be available everywhere, 4G systems will offer channel
sizes down to 5 MHz, in increments of 1.5 MHz.
1.3.7 Spectrum Allocation and Duplex Modes
Transmission techniques exist
Simplex
One party transmits data and the other party receives data.No
simultaneous transmission is possible, the communication is one-way and
only one frequency (channel) is used.
Half Duplex
Each party can receive and transmit data, but not at the same time. The
communication is two-way and only one frequency (channel) is used.
Full Duplex
Each party can transmit and receive data simultaneously.
Chapter 1: Overview of Long Term Evolution (LTE)
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The communication is two-way and two frequencies.
Full duplex main methods used are
Time Division Duplexing (TDD)
The communication is done using one frequency, but the time for
transmitting and receiving is different. This method emulates full duplex
communication using a half-duplex link.
Frequency Division Duplexing (FDD)
The communication is done using two frequencies and the transmitting
and receiving of data is simultaneous.
The advantages of TDD are typically observed in situations uplink and
downlink data transmissions are not symmetrical. Transmitting and
receiving is done using one frequency, the channel estimations for beam
forming (and other smart antenna techniques) apply for both the uplink
and the downlink.
A typical disadvantage of TDD is the need to use guard periods between
the downlink and uplink transmissions. The advantages of FDD are
typically observed in situations where the uplink and downlink data
transmissions are symmetrical (which is not usually the case when using
wireless phones). More importantly, when using FDD, the interference
between neighboring Radio Base Stations (RBSs) is lower than when
using TDD. Also, the spectral efficiency (which is a function of how well
a given spectrum is used by certain access technology) of FDD is greater
than TDD.
Chapter 1: Overview of Long Term Evolution (LTE)
1 - 14
Frequency band from 2600MHz to 2.6 GHz. Channel bandwidth up to 20
MHz Channel bandwidth on-demand (1.4 MHz, 3MHz, 5MHz,
10MHz, 15MHz, 20MHz). Charging / volume
1.3.8 Resource element and resource block
A resource element is the smallest unit in the physical layer and
occupies one OFDM or SC-FDMA symbol in the time domain and
one subcarrier in the frequency domain as shown in figure (2-1) .
Aresource block (RB) is the smallest unit that can be scheduled for
transmission. An RB physically occupies 0.5 ms (1 slot) in the time
domain and 180 KHz in the frequency domain .the number of
subcarriers per RB and the number of symbols per RB vary as a
function of the cyclic prefix length and subcarrier spacing.
Figure (1-2): Resource element and resource block
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1 - 15
1.4 LTE architecture
Figure (1-3) LTE architecture
The combination of the EPC and the evolved RAN ( E-UTRAN) is the
evolved packet system (EPS).
Figure (1-4) Evolved Packet System
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1 - 15
1.4 LTE architecture
Figure (1-3) LTE architecture
The combination of the EPC and the evolved RAN ( E-UTRAN) is the
evolved packet system (EPS).
Figure (1-4) Evolved Packet System
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1 - 15
1.4 LTE architecture
Figure (1-3) LTE architecture
The combination of the EPC and the evolved RAN ( E-UTRAN) is the
evolved packet system (EPS).
Figure (1-4) Evolved Packet System
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1.4.1 Access network
E-UTRAN
Consists only of enodeBs on the network side. The enodeB performs
tasks similar to those performed by the nodeBs and RNC (radio network
controller) together in UTRAN. The aim of this simplification is to
reduce the latency of all radio interface operations.
The eNBs are interconnected with each other by means of the X2
interface. The eNBs are connected by the S1 interface to the EPC
(Evolved Packet Core). The eNB connects to the MME (Mobility
Management Entity) by means of the S1-MME interface and to the
Serving Gateway (S-GW) by means of the S1-U interface. The S1
interface supports a many-to-many relation between MMEs / Serving
gateways and eNBs.
eNodeB
eNB interfaces with the UE and hosts the Physical (PHY), Medium
Access Control (MAC), Radio Link Control (RLC), and Packet Data
Control Protocol (PDCP) layers. It also hosts Radio Resource Control
(RRC) functionality corresponding to the control plane. It performs many
functions including radio resource management, admission control,
scheduling, enforcement of negotiated UL QoS, cell information
broadcast, ciphering/deciphering of user and control plane data, and
compression/decompression of DL/UL user plane packet headers.
Functions of eNodeB
Transmission & Reception
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Modulation & Demodulation
Radio resources allocation
Error Detection and Correction
Connectivity to the EPC
Header Compression & packet encryption
Scheduling and transmission of broadcast information
1.4.2 CORE NETWORK ( EPC )
The main logical nodes of the EPC are:
Mobility Management Entity (MME)
PDN Gateway (P-GW)
Policy and Charging Rules Function (PCRF)
Serving Gateway (S-GW).
Home Subscriber Server (HSS)
1- MME
Mobility Management Entity is the control node that processes the
signaling between the UE and the CN. Manages and stores UE context
(for idle state: UE/user identities, UE mobility state, user security
parameters). It generates temporary identities and allocates them to UEs.
Security Procedures (by interacting with the HSS).
Idle mode UE Tracking Area update & Paging
Handling QoS
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Choosing the SGW for a UE at the initial attach and at time of
intra-LTE handover involving Core Network node relocation.
2-P-GW
The PDN GW provides connectivity to the UE to external packet
data networks by being the point of exit and entry of traffic for the UE
The Packet data network gateway is responsible for:
IP address allocation for the UE
Charging (according to rules from the PCRF )
Filtering of downlink user IP packets into the different QoS based
bearers
mobility anchor for interworking with non-3GPP technologies such
as CDMA2000 and WiMAX networks
3-PCRF
The Policy and Charging Rules Function is responsible for :
Real time Determination of policy & charging rules
QoS handling.
4-S-GW
The SGW routes and forwards user data packets, while also acting
as the mobility anchor for the user plane during inter-eNB handovers and
as the anchor for mobility between LTE and other 3GPP technologies
(terminating S4 interface and relaying the traffic between 2G/3G systems
and PDN GW).
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The serving gateway is responsible for:
Routes and forwards user data packets
Mobility anchor for intra E-UTRAN mobility (when the UE
moves between eNodeBs)
Mobility anchor with 2G/GSM and 3G/UMTS mobility.
5-HSS
Users subscription data
Information about the PDNs to which the user can connect
The identity of the MME to which the user is currently
attached or registered
Authentication information
Chapter TwoLTE network dimensioning
Chapter 2: LTE network dimensioning
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Chapter TwoLTE network dimensioning
2.1 Introduction
Dimensioning is a part of the whole planning process, which alsoincludes detailed planning and optimization of the wireless cellularnetwork as shown in figure: (2-1)
Figure: (2-1) LTE network planning process
2.2 LTE network dimensioning
It is the initial phase of network planning. It provides the firstestimate of the network element count as well as the capacity of thoseelements. The purpose of dimensioning is to estimate the requirednumber of eNodeBs needed to support a specified traffic load in an area.The aim of this whole exercise is to provide a method to design thewireless cellular network such that it meets the requirements set forth bythe customer. This process can be modified to fit the needs of anywireless cellular network. This is a very important process in networkdeployment. Wireless cellular network dimensioning is directly related tothe quality and effectiveness of the network. And can deeply affect itsdevelopment. Wireless cellular network dimensioning follows basic stepsshown in figure:
Coverage planning and siteselection and acquisition
Requirements andstrategy for
coverage, capacityand quality Capacity requirement
Parameter planning
Performanceanalysis in terms ofquality, efficiency
and availability
Dimensioning OptimizationPlanning
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Figure (2-2): Dimensioning basic steps
2.2.1 Data and Traffic analysis
This is the first step in LTE dimensioning. It involves gathering ofrequired inputs and their analysis to prepare them for use in LTEdimensioning process.
Operator data and requirements are analysed to determine the bestsystem configuration. Wireless cellular dimensioning requires somefundamental data elements. These parameters include subscriberpopulation, traffic distribution, geographical area to be covered,frequency band, allocated bandwidth, and coverage and capacityrequirements. Propagation models according to the area and frequencyband should be selected and modified if need. This is necessary forcoverage estimation.
System specific parameters like, transmit power of the antennas, theirgains, estimate of system losses, type of antenna system used etc., mustbe known prior to the start of wireless cellular network dimensioning.Each wireless network has its own set of parameters.
Traffic analysis gives an estimate of the traffic to be carried by thesystem. Different types of traffic that will be carried by the network aremodulated. Traffic types may include voice calls, VOIP, PS or CS traffic.Overheads carried by each type of traffic are calculated and included inthe model. Time and amount of traffic is also forecasted to evaluate theperformance of the network and to determine whether the network canfulfil the requirements set forth.
Dimensioning steps
Data/TrafficAnalysis
Coverageestimation
CapacityEvaluation
TransportDimensioning
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2.2.2 Coverage estimation
It is used to determine the coverage area of each eNodeB. Coverageestimation calculates the area where eNodeB can be heard by the users(receivers). It gives the maximum area that can be covered by eNodeB.But it is not necessary that an acceptable connection (e.g a voice call)between eNodeB and receiver can be established in coverage area.However eNodeB can be detected by the receiver in coverage area.
Coverage analysis fundamentally remains the most critical step in thedesign of LTE network as with 3G systems. RLB (Radio Link Budget) isat the heart of coverage planning which allows the testing of path lossmodel and the required peak data rates against the target coverage levels.
The result is the effective cell range to work out the coverage-limitedsite count. This requires the selection of appropriate propagation model tocalculate path loss.
LTE RLB with the knowledge of cell size estimates and of the area tobe covered is an estimate of the total number of sites is found. Thisestimate is based on coverage requirements and needs to be verified forthe capacity requirements.
Coverage planning includes radio link budget and coverage analysisRLB comprises of all the gains and losses in the path of the signal fromtransmitter to receiver. This includes transmitter and receiver gains aswell as losses and the effect of the wireless medium between them. Freespace propagation loss, fast fading and slow fading in taken into account.Additionally, parameters that are particular to some systems are alsoconsidered. Frequency hopping and antenna diversity margins are twoexamples.
2.2.3 Capacity evaluation
Capacity planning deals with the ability of the network to provideservices to the users with a desired level of quality. After the sitecoverage area is calculated using coverage estimation, capacity relatesissues are analyzed. This involves selection of site and systemconfiguration, e.g. channels used channel elements and sectors.
These elements are different for each system. Configuration is selectedsuch that it fulfils the traffic requirements. In some wireless cellularsystems, coverage and capacity are interrelated, e.g. in WCDMA.
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In this case, data pertaining to user distribution and forecast ofsubscriber’s growth is of almost importance.
Dimensioning team must consider these values as the have directimpact on coverage and capacity, Capacity evaluation gives an estimateof the number of sites required to carry the anticipated traffic over thecoverage area.
Once the number of sites according to the traffic forecast isdetermined, the interfaces of the network are dimensioned. Number ofinterfaces can vary from a few in some systems to many in others. Theobjective of this step is to perform the allocation of traffic in such a waythat no bottle neck is created in the wireless network. All the quality ofservice requirements are to be met and cost has to be minimized. Goodinterface dimensioning is very important for smooth performance of thenetwork.
With a rough estimate of the cell size and site count, verification ofcoverage analysis is carried out for the required capacity. It is verifiedwhether with the given site density, the system can carry the specifiedload or new sites have to be added. In LTE, the main indicator of capacityis SINR distribution in the cell.
This distribution is obtained by carrying out system levels simulations.SINR distribution can be directly mapped into system capacity (datarate). LTE cell capacity is impacted by several factors, for example,packet scheduler implementation, supported MCSs, antennaconfigurations and interference level. Therefore, many sets of simulationresults are required for comprehensive analysis. Capacity based site countis then compared with coverage result and greater of the two numbers isselected as the final site count, as already mentioned in the previoussection.
2.2.4 Transport Dimensioning
Transport dimensioning deals with the dimensioning of interfacesbetween different network elements. In LTE, S1 (between eNodeB and aGW) and X2 (between two eNodeBs) are the two interfaces to bedimensioned. These interfaces were still in the process of beingstandardized at the time of this work. Therefore, transport dimensioningis not included in this thesis work.
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An initial sketch of LTE network is obtained by following the abovementioned steps of dimensioning exercise. This initial assessment formsthe basis of detailed planning phase. In this thesis, main emphasis is onsteps two to four.
First step is unnecessary because the data for the test cases is takenfrom WIMAX scenario, allowing its by pass. Coverage and capacityplanning is dealt in detail and resulting site count is calculated to give anestimate of the dimensioned LTE network. Dimensioning of LTE willdepend on the operator strategy and business case. The physical side ofthe task means to find the best possible solution of the network whichmeets operator requirements and expectations. In detail and resulting sitecount is calculated to give an estimate if the dimensioned LTE network.
Dimensioning of LTE will depend on the operator strategy andbusiness case. The physical side of the task means to find the bestpossible solution of the network which meets operator requirements andexpectative.
2.3 LTE network dimensioning inputs
LTE dimensioning inputs used in the development of methods andmodels for LTE dimensioning. LTE dimension inputs can be broadlydivided into three categories; quality, coverage and capacity relatedinputs. LTE network dimensioning has three main processes shown infigure (2-3).
Figure (2-3): LTE network dimensioning inputs
2.3.1 Quality inputs
Dimensioning inputs
Coverage planning inputsQuality inputs Capacity planning inputs
Chapter 2: LTE network dimensioning
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Quality inputs include average cell throughput and blocking probability.These parameters are the customer requirements to provide a certain levelof service to its users. These inputs directly translate into Qos parameters.Besides cell edge coverage probability is used in the dimensioning tool todetermine the cell radius and thus the site count.
Three methods are employed to determine the cell edge. These includeuser defined maximum throughput at the cell edge, maximum coveragewith respect to lowest MCS (giving the minimum possible site count) andpredefined cell radius. With a predefined cell radius, parameters can bevaried to check the data rate achieved at this cell size. This option givesthe flexibility to optimize transmitted power and determining a suitabledata rate corresponding to this power.
2.4 Coverage planning inputs
Required coverage probability plays a vital role in determination of callradius. Even a minor change in coverage probability causes a largevariation in cell radius as shown in figure (2-4)
Figure (2-4): LTE coverage planning
LTE dimensioning inputs for coverage planning exercise are similarto the corresponding inputs for 3G UMTS networks.
Radio link budget (RLB) is of central importance to coverageplanning in LTE.
Radio Link budget(RLB)
MAPL
Propagation model
Cell size
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RLB inputs include transmitter and receiver antenna systems, numberof antennas used, conventional system gains and losses, cell loading andpropagation models. LTE can operate in both the conventional frequencybands of 900 and 1800 MHz as well as extended band of 2600 MHz.Models for all the three possible frequency bands are incorporated in thiswork. Additionally, channel types (pedestrian, Vehicular) andgeographical information is needed to start the coverage dimensioningexercise. Geographical input information consists of area typeinformation (Urban, Rural, etc.) and size of each area type to be covered.Furthermore, required coverage probability plays a vital role indetermination of cell radius. Even a minor change in coverage probabilitycauses a large variation in cell radius.
2.5 Capacity planning inputs
Capacity planning inputs provides the requirements, to be met by LTEnetwork dimensioning exercise. Capacity planning inputs gives thenumber of subscribers in the system, their demanded services andsubscriber usage level. Available spectrum and channel bandwidth usedby the LTE system are also very important for LTE capacity planning.
Traffic analysis and data rate to support available services (Speech,Data) are used to determine the number of subscribers supported by asingle cell and eventually the cell radius based on capacity evaluation.
LTE system level simulation results and LTE link level simulationresults are used to carry out capacity planning exercise along with otherinputs. These results are obtained from Nokia's internal sources.Subscriber growth forecast is used in this work to predict the growth andcost of the network in years to come. This is a marketing specific inputtargeting the feasibility of the network over a longer period of time.Forecast data will be provided by the LTE operators.
2.6 LTE network dimensioning outputs
Outputs or targets of LTE dimensioning process have already beendiscussed indirectly in the previous section. Outputs of the dimensioningphase are used to estimate the feasibility and cost of the network. Theseoutputs are further used in detailed network planning. Dimensioning LTEnetwork can help out LTE core network team to plan a suitable networkdesign and to determine the number of backhaul links required in thestarting phase of the network as shown in figure (2-5)
Cell size is the main output of LTE dimensioning exercise.
Chapter 2: LTE network dimensioning
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Two values of cell radius are obtained, one from coverage evaluationand second from capacity evaluation. The larger of the number is takenas the final output. Cell radius is then used to determine the number ofsites. Assuming a hexagonal cell shape, number of sites can be calculatedby using simple geometry. This procedure is explained capacities ofeNBs are obtained from capacity evaluation, along with the number ofsubscribers supported by each cell. Interface dimensioning is the last stepin LTE access network dimensioning, which is out of scope of this thesiswork. The reason is that LTE interfaces (S1 and S2) were still undergoingstandardization.
Figure (3-5): LTE dimensioning outputs
2.7 Comparison among dimensioning, planning and optimization.
Dimensioning is the initial phase of network planning. It provides thefirst estimate of the network element count as well as the capacity ofthese elements. The purpose of dimensioning is t estimate the requirednumber of the radio base stations needed to support a specified trafficload in an area.
The radio network planning process is designed to maximize thenetworks coverage, whilst at the same time providing the desiredcapacity. In order to achieve this, there are number of stages that are
DimensioningOutputs
Population statistics
Number of subscribes
Area to be covered by thenetwork
Subscriber geographical spread
Cell throughput
Final site-count
Chapter 2: LTE network dimensioning
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typically performed, these include: Initial Planning, Detailed Planningand Optimization.
Optimization is probably the most important stage when planning anLTE network. Typically it can be split into pre-launch optimization.There are however a number of different areas that may be optimized,these include.
Figure (2-6) optimization stages of LTE
2.7.1 Planning of LTE
The radio network planning process is designed to maximize thenetworks coverage, whilst at the same time providing the desiredcapacity. In order to achieve this, there are a number of stages that aretypically performed, these include:
Nominal or preliminary planning Detailed planning Optimization
Chapter 2: LTE network dimensioning
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typically performed, these include: Initial Planning, Detailed Planningand Optimization.
Optimization is probably the most important stage when planning anLTE network. Typically it can be split into pre-launch optimization.There are however a number of different areas that may be optimized,these include.
Figure (2-6) optimization stages of LTE
2.7.1 Planning of LTE
The radio network planning process is designed to maximize thenetworks coverage, whilst at the same time providing the desiredcapacity. In order to achieve this, there are a number of stages that aretypically performed, these include:
Nominal or preliminary planning Detailed planning Optimization
Chapter 2: LTE network dimensioning
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typically performed, these include: Initial Planning, Detailed Planningand Optimization.
Optimization is probably the most important stage when planning anLTE network. Typically it can be split into pre-launch optimization.There are however a number of different areas that may be optimized,these include.
Figure (2-6) optimization stages of LTE
2.7.1 Planning of LTE
The radio network planning process is designed to maximize thenetworks coverage, whilst at the same time providing the desiredcapacity. In order to achieve this, there are a number of stages that aretypically performed, these include:
Nominal or preliminary planning Detailed planning Optimization
Chapter 2: LTE network dimensioning
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Figure (2.7) the cellular network planning processes
2.7.1.1 Nominal or preliminary cell planning
A nominal or preliminary cell plan can be produced from thedata compiled from coverage and traffic analysis. The nominal cell plainsa graphical representation of the network and looks like a cell pattern on amap. During nominal cell planning, do not care about the position of thesites taking only in consideration the separation distance between sites.
To simplify the network planning, hexagonal shaped cells are adoptedalthough they are artificial or fictitious and do not exist in real world butit have become a widely promoted symbols for cellular structured system.Nominal cell plans are the first cell plans and forms the basis for furtherplanning.
In reality, each company has a planning tool which is a work stationequipped with a software package based on link budget calculations andusing certain propagation model to determine the cell radius and theresults are displayed on the map using different colors. An up to datedigital three dimensional map with high resolutions for the area where thenetwork is to be planned is used to import the actual environment datathat include the terrain fluctuations (height information), clutterdistribution, dense degree of the area of interest. The area of interest is
Chapter 2: LTE network dimensioning
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divided into different sub regions according to different environmentdefinitions. Each sub region has its own characteristics. The classificationis based on the dense of buildings and their heights in the sub region.
Each sub region is classified into one of the four categories: denseurban (DU), urban (UR), suburban (SU) and rural (RU).The planning tooldetermines the classification of each sub region. It is possible to importdata from site survey files. Data can also be imported from fieldmeasurements files to tune the propagation model as will be explained inthe following subsections.
The area where the network is to be planned to be covered withcellular structured system is used. Two study cases are investigated:
Coverage oriented environment represent suburbanand rural environments.
Capacity oriented environment represent dense urbanand urban environments.
Using the software program developed by us the maximum allowablepath loss (MAPL) is calculated using reverse link budget and forwardlink budget and the link balance was made and the least value was takenas an input to the propagation model. Thus, the cell radius was calculatedusing coverage criterion. The classification of sub regions according totheir building density and heights is determined by us during site surveyby observing the area features, landmarks and terrain in each sub region.
2.7.2 Detailed planning
2.7.2.1 Site surveysOnce the nominal cell planning has been completed, site surveys
can be performed for all the proposed site locations by the site surveyteam. The site survey includes: site search, candidate sites are chosen, thesite survey team check the validity of each location of the sites, contactwith the site owner, site location lease agreement, get permission of thenew sites, and carry out the construction of the civil works, towererection, transmission and interconnection between the network entities.Finally site acquisition.
The following items must be checked for each site:
The space for the equipment including: antennas, cable runs andpower facilities. The exact site locations (with some shifts)are fed back tothe network planning team to modify the network planning by shifting the
Chapter 2: LTE network dimensioning
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locations of the sites such that no dead zones were introduced and overlapbetween sites were reduced as much as possible.
2.7.2.2 Field measurementsThe purpose of the field measurements is to correct the propagation
model to reflect the propagation status of wireless signal in theenvironment of the area of interest, thus making the model more practicalmeet the coverage requirement.
To conduct field tests, the following steps have to be followed:You have to choose the frequency of the measurement. If there is
interference on the frequency point to be used, choose a frequency pointwithout interference. The transmission characteristics are almost the samewhen frequency difference is 10 MHz or so.
Field measurements site choice: You have to choose the fieldmeasurements site. The field measurements site should not be too muchhigher than the surrounding buildings and 10 meters are suitable. Toobtain as much data as possible for correcting various clutters, two orthree field measurements sites with similar surrounding clutters(building heights, site height, and so on) can be chosen to carry out fieldmeasurements and data from several sites can be synthesized to executethe correction of the various clutters.
Choose pertinent parameters of the field measurements site i.e. useomnidirectional antenna, choose proper transmission power, noobstruction surrounding the field measurements site, and clean thefrequency point.
The tools for field measurements includes: transmitter or CWtransmitter, scanner or field strength meter and GPS handset.
Before field measurements, you have to span antennas,install transmitter, and adjust output power and frequency point to propervalues and transmitting signal.
After field measurements, the field measurements data is put into aform acceptable for the planning tool load the field measurements fileinto the planning tool and correct the model.
2.7.2.3 System design (or final cell plan)The actual and the exact site locations are used to produce the final cell
planning which is used for network installations, provided that no deadzones and overlap between sites is small as possible 2.5 System diagnosisThe test team via the driving test and using test mobile system which is atesting tool. The testing tool includes mobile test units (MTUs) in carsand fixed test units geographically distributed. The testing tool consists ofa MS with special software, a portable personal computer (PC) and a
Chapter 2: LTE network dimensioning
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global positioning system (GPS) receiver and mobile traffic recording(MTR) and cell traffic recording (CTR). The MS is used in active andidle mode. The PC is used for presentation, control and measurementdata storage. The GPS receiver provides the exact position of themeasurement site by utilizing satellites. When the satellite signals areshadowed, the GPS system switches to dead reckoning. Dead reckoningconsists of a speed sensor and a gyro. This provides the position ifsatellite signals are lost temporarily. The measurement data can beimported to the planning tool and can be displayed on a map to comparethe measured handoffs with the predicted cell boundaries for example tocheck the network performance, to evaluate the customer complaints, toverify that the final cell planning was implemented successfully.
2.7.2.4 System tuningAfter installation of the network, it is continuously monitored to
determine how well it meets the coverage and capacity requirement usingthe measured data, parameters are changed. Other measurements can betaken if necessary.
The parameters to be changed are such as eNodeB transmitted power,eNodeB antenna height, antenna down tilting angle, antenna type (gain,horizontal HPBW, and so on). Change handoff parameters, change, addor decrease channels.
2.7.2.5 System growthCell planning is an ongoing process. If the network needs to be
expanded to extend coverage due to increase in traffic of because orchange in the environment Starting with a new capacity or traffic andcoverage or power analysis.
2.7.2.6 eNodeB site choiceWhen choosing eNodeB site, the following rules should be obeyed:
1) Antenna height should be higher to some degree than thesurroundings.
2) Ensure that there is no obvious obstruction insurrounding environments.
3) Ensure that there is no obstruction surrounding the position ofsetting the global positioning (GPS) antenna.
4) Meet coverage goal requirement concerning the effectivecoverage of the eNodeB.
5) Predict traffic distribution in the coverage area and set theeNodeB sites on the places of real traffic need.
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6) Utilize existent sites such as telecom Egypt centrals in case ofrural communication network and use other communicationresources as possible such as towers, buildings.
7) Guarantee necessary space separation concerning theinterference from other systems.
8) Avoid strong wireless transmitter, radar or other seriousinterference.
9) Choose places with convenient traffic, reliable electricity plant,if not available use generators or solar cell panels
10) Avoid being near the flammable or explosive buildings.11) Avoid being near the industrial manufactories with
poisonous gas or smoke and dust.12) Avoid hospitals, educational buildings, military zones,
church, mosques, and entertainment areas.
2.7.2.7 Antenna configuration and cell type choiceThe choice of eNodeB antenna should concern with the followingfactors: site type, dense degree of eNodeB and relative positionsbetween them and dense degree of the area and so on. Thefollowing rules should be obeyed when choosing antennas:1) In dense urban (DU) and urban (UR) areas i.e. in capacity
oriented areas, sectorized cells or directional antennas withnarrow power beam width (HPBW) angle can be chosen andlarge gain can be chosen to reduce the other cell interference andincrease the capacity.
2) In suburban areas and rural areas with low capacity where useror population density is low i.e. In coverage oriented areas,Omni cells with omnidirectional antennas with high antennaheight can be chosen.
3) In suburban areas and rural areas, when the capacity increases,directional antennas with wide half power beam width (HPBW)angle and large gain value can be chosen to increase coverage.
4) In highways, where there is no need to cover towns along theroad, or at border area or at the coast, 2 sector configuration isthe optimal solution with two directional antennas with narrowerwidth and higher gain antennas.
5) Three sector cells is the optimum solution to meet both capacityand coverage in all morphologies.
6) Dual polarization is usually used in dense urban (DU) and urban(UR) areas and space diversity is usually used in suburban (SU)rural (RU) areas.
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2.7.3 LTE optimization
Optimization is probably the most important stage when planning LTEnetwork. Typically it can be split into pre-launch optimization andpost-launch optimization. There is however a number of different areasthat may be optimized these including:
Capacity Coverage Configuration and parameters Interference
Prelaunching optimization
It is done when the sites are on air but not available to users. It is donevia drive test to determine gaps and holes for coverage and to ensureoptimal operation for the network and to verify coverage, capacity andquality requirements.
Figure (2-8) LTE optimization process
Chapter 2: LTE network dimensioning
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2.7.3 LTE optimization
Optimization is probably the most important stage when planning LTEnetwork. Typically it can be split into pre-launch optimization andpost-launch optimization. There is however a number of different areasthat may be optimized these including:
Capacity Coverage Configuration and parameters Interference
Prelaunching optimization
It is done when the sites are on air but not available to users. It is donevia drive test to determine gaps and holes for coverage and to ensureoptimal operation for the network and to verify coverage, capacity andquality requirements.
Figure (2-8) LTE optimization process
Chapter 2: LTE network dimensioning
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2.7.3 LTE optimization
Optimization is probably the most important stage when planning LTEnetwork. Typically it can be split into pre-launch optimization andpost-launch optimization. There is however a number of different areasthat may be optimized these including:
Capacity Coverage Configuration and parameters Interference
Prelaunching optimization
It is done when the sites are on air but not available to users. It is donevia drive test to determine gaps and holes for coverage and to ensureoptimal operation for the network and to verify coverage, capacity andquality requirements.
Figure (2-8) LTE optimization process
Chapter Three
Coverage Dimensioning
Chapter 3: Coverage dimensioning
3 - 2
Chapter Three
Coverage dimensioning3.1 Introduction
The link budget calculations estimate the maximum allowed signal
Attenuation, called path loss, between the mobile and the base station
antenna. The maximum path loss allows the maximum cell range to be
estimated with a suitable propagation model, such as Okumura–Hata. The
cell range gives the number of base station sites required to cover the
target geographical area. The link budget calculation can also be used to
compare the relative coverage of the different systems.
Network dimensioning requires determination the number or cells
(number of sites) to cover a certain region and to determine the radius of
each cell and the spacing between them either using traffic or coverage
criteria. So, in this chapter we will discuss the coverage analysis using
the link budget and certain propagation model.
This chapter presents the outline and basic concepts required to
dimension coverage in the Long Term Evolution (LTE) network with
functions in the current release. The method presented in this document
consists of concepts and mathematical calculations that are elements of a
general dimensioning process.
The detailed order and flow of calculations depends on the required
output of and type of input for the specific dimensioning task. The
method provides a specific dimensioning process example. By changing
the prescribed inputs and outputs and the order of calculations, the
dimensioning process can be adapted to other methods.
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3 - 3
Input requirements for the capacity and coverage dimensioning
process consist of a bit rate at the cell edge, one for downlink and one for
uplink.
The required output is site-to-site distance and cell capacity in the
uplink and downlink. The method is developed for Frequency Division
Duplex (FDD), but can also be used for Time Division Duplex (TDD) .
Limitations
Limitations to the calculation method include the following:
Multiple Inputs Multiple Outputs (MIMO) is considered only for
the downlink for a maximum of two antennas
Outer loop power control in the uplink is not modelled
The method is adapted and developed primarily as a mobile
broadband service that can handle Voice over IP (VoIP) to a limited
extent
Quality of Service (QoS) is not handled by the method
Assumptions
Calculations for coverage and capacity are based on the following
assumptions:
All user equipment is assumed to have two receiving antennas
All resource blocks are transmitted at the same power, including
user data, as well as control channels and control signals
The coverage for control channels and control signals equals that
of user data at the same power.
Layer 1 overhead for all control channels and control signals is
included in the Signal-to-Interference-and-Noise Ratio (SINR) to
bit rate relationships.
Chapter 3: Coverage dimensioning
3 - 4
Figure (3-1) LTE Dimensioning Process
3.2 Concepts and Terminology
The following terms are used in describing capacity and coverage
dimensioning:
Average user bit rate
The bit rate achievable by a single user. When all resources in a cell
are used, the average user bit rate can be the average throughput in one
cell. It is a measure of average potential in a cell while all interfering cells
are loaded to the dimensioned level.
Cell edge
The geographical location where the path loss between eNodeB and
the antenna is at a specific maximum threshold value, as calculated using
the quality requirement imposed on the network, guaranteeing the
required quality with a probability of 95%, for example.
Cell throughput
Cell throughput is obtained in one cell when all cells are loaded to
the dimensioned level, and the resource use is equal to system load,
Chapter 3: Coverage dimensioning
3 - 4
Figure (3-1) LTE Dimensioning Process
3.2 Concepts and Terminology
The following terms are used in describing capacity and coverage
dimensioning:
Average user bit rate
The bit rate achievable by a single user. When all resources in a cell
are used, the average user bit rate can be the average throughput in one
cell. It is a measure of average potential in a cell while all interfering cells
are loaded to the dimensioned level.
Cell edge
The geographical location where the path loss between eNodeB and
the antenna is at a specific maximum threshold value, as calculated using
the quality requirement imposed on the network, guaranteeing the
required quality with a probability of 95%, for example.
Cell throughput
Cell throughput is obtained in one cell when all cells are loaded to
the dimensioned level, and the resource use is equal to system load,
Chapter 3: Coverage dimensioning
3 - 4
Figure (3-1) LTE Dimensioning Process
3.2 Concepts and Terminology
The following terms are used in describing capacity and coverage
dimensioning:
Average user bit rate
The bit rate achievable by a single user. When all resources in a cell
are used, the average user bit rate can be the average throughput in one
cell. It is a measure of average potential in a cell while all interfering cells
are loaded to the dimensioned level.
Cell edge
The geographical location where the path loss between eNodeB and
the antenna is at a specific maximum threshold value, as calculated using
the quality requirement imposed on the network, guaranteeing the
required quality with a probability of 95%, for example.
Cell throughput
Cell throughput is obtained in one cell when all cells are loaded to
the dimensioned level, and the resource use is equal to system load,
Chapter 3: Coverage dimensioning
3 - 5
interfering cells as well as interfered cells. It is the average throughput
per cell as calculated across the entire network.
Coverage (area)
The percentage of cell area that can be served according to a defined
quality requirement. With an assumed uniform subscriber density (often
assumed in a dimensioning exercise), the percentage of served area
equals the percentage of served users.
Resource block
It is the smallest unit in the physical layer and occupies one OFDM
or SC-FDMA symbol in the time domain and one subcarrier in the
frequency domain. A two-dimensional unit in the time-frequency plane,
Consisting of a group of 12 carriers, each with 15 kHz bandwidth, and
one slot of 0.5 ms.
System load
The extent of available air interface resource usage.
The system load equals the ratio of used resource blocks as an average
over the entire system.
3.3 link Budget Definition
Illustrative example: you are planning a vacation .You estimate that
you will need 1000 L.E to pay for the hotels, restaurant, food etc.. You
start your vacation and watch the money get spent at each stop. When you
get home, you pat yourself on the back for a job well done because you
still have 50 L.E left in your wallet.
We do something similar with communication links, called creating
"a link budget" The traveller is the signal and instead of money it starts
out with ”power".
Chapter 3: Coverage dimensioning
3 - 6
It spends its power (or attenuates, in engineering terminology) as it
travels wired or wireless.
So you can use a credit card along the way for extra money infusion,
the signal can get "margin" extra power infusion along the way from
intermediate amplifiers such as microwave repeaters foe telephone links
or from satellite transponders for satellite links. The designer hopes that
the signal will complete its trip with just enough power to be decoded at
the receiver with the desired signal quality.
In our example, we started our trip with 1000 LE because we wanted
a budget vacation. But what if our goal was a first-class vacation with
stays at five stars hotels, best shows and travel by A1000LE budget
would not be enough and possibly we will need instead $5000. The
quality of the trip desired determines how much money we need to take
along.
Link budget means to catalog all losses and gains between the two
ends of communication i.e. mobile station (MS) and eNodeB to yield the
maximum allowable (or available or acceptable) loss in signal strength
that can be tolerated between the transmitter and receiver. Link budget
traces power expenditures along path from transmitter to receiver to
identify or determine the maximum allowable path loss and to determine
the maximum feasible cell radius using propagation model.
Link budget is defined sometimes as the difference between
transmitter effective isotropic radiated power (EIRP) and the minimum
signal strength at the receiver i.e. the receiver sensitivity for acceptable
quality .Link budget is specified in logarithmic units (decibels) .Link
budget output is fed to propagation model to provide the greatest spatial
Chapter 3: Coverage dimensioning
3 - 7
distance between transmitter and receiver at which reliable
communication of the desired quality can still take place.
3.4 Why we use Link Budget?
link budget is necessary to determine or calculate the maximum
allowable or available, or accepted path loss (MAPL) where
communication is achieved reliably or that will provides adequate signal
strength at the cell boundary for acceptable voice quality over 90% of the
coverage area if it is flat or 75% if it is hilly .Link budget is necessary to
determine the radius of the cells, and finally to determine the locations of
cell sites as well as the spacing between them to ensure reliable and
uninterrupted communication as mobile stations (MSs) move through the
coverage area of interest.
3.5 What are the types of link budget?
Since communication in mobile cellular phone system between mobile
stations (MSs) and eNodeB is bidirectional. Thus it depends on the
quality of the both reverse link and forward link. There are two link
budgets:
Reverse link budget (up link budget) i.e. as signal is transmitted
from mobile station (MS) and received by eNodeB.
Forward link budget (down link budget) i.e. as signal is transmitted
from eNodeB and received by mobile station (MS).
The reverse link budget has to be considered in system design first then
forward link budget and finally link balance will be made. But since
coverage is usually reverse link limited, we will focus on reverse link
budget (up link budget).
Chapter 3: Coverage dimensioning
3 - 8
3.6 Up link Budget (uplink coverage)
Most mobile telephony systems are frequently limited by the
uplink, so it is useful to start link budget calculations with the uplink
coverage requirements.
The calculations are performed according to the following stages:
User equipment (UE) effective isotropic radiated or transmitted
power per physical resource block (PRB)
The uplink required bit rate per physical resource Block (PRB)
(Rrequired, PRB)
The uplink required SINR ( ) given the uplink required bit rate
physical resource Block (PRB) (Rrequired, PRB).
ENodeB receiver sensitivity (SeNodeB)
Uplink noise rise or interference margin (IM) (BIUL)
Log normal fading margin (BLNF)
Uplink link budget maximum allowable path loss (MAPLUL)
3.7 Up Link Budget Entries:
The following set of definitions is to be read in conjunction with the
appended reverse link budget (uplink budget) spread sheet.
3.7.1 Maximum mobile station (MS) transmitted power per traffic
channel:
It is the power coming out of the radio / amplifier and into the
antenna power; the power value is 23 dBm at cellular frequencies .These
values are taken from minimum performance standards for a 200
milliwatt mobile station.
Chapter 3: Coverage dimensioning
3 - 9
3.7.2 Mobile station (MS) transmitter antenna gain (dBi) :
An antenna is a device used to transmit or receive radio frequency
(RF). The radio produces an RF signal and the antenna is the transport
medium used to direct that signal onto free space for its eventual
reception by another antenna attached to a receiver. One of the most
important aspects of an antenna is the antenna gain.
Mobile station (MS) antenna gain is the measure of strength of the
amplification effect of MS antenna directed signal with respect to signal
loss. It is the output transmitted power from the mobile station, in a
particular direction, compared to that produced in any direction by a
perfect reference antenna (isotropic antenna or dipole antenna).
An antenna can create an amplification effect depending on its
construction. The amplification effect is the result of focusing the
transmission signal into a tight beam. Antenna gain works by the same
principle. Signal loss simply describes a decrease in signal strength. Gain
and loss are very important to antenna and radio performance because
they directly affect signal quality and the signal transmission and
reception capabilities. Antenna gain has a direct effect on the total power
radiated from an antenna. The value of the power transmitted into an
antenna will not leave the antenna at the same value. It will be increased
by the amount of gain of the antenna.
Antenna gain can be expressed in dBi, decibels relative to an idea
isotropic radiator or dBd, decibels relative to an idea dipole effective
area. A half –wave dipole antenna has an isotropic gain of 2.15 dBi. This
means that the dipole, in the direction of maximum radiation, is 2.15dB
more intense than that of an isotropic radiator, based on the same input
power.
Chapter 3: Coverage dimensioning
3 - 10
The value taken for MS antenna gain ranges between 0 dB this is the
gain of the mobile station (MS) antenna. At both cellular and personal
communication system (PCS) frequencies, this is a dipole whose gain can
be taken to be 2.2 dBi.
Mobile station (MS) antenna gain is defined either absolute gain or
relative gain.
The absolute gain: it is the ratio of maximum radiation intensity in
(watts) per unit solid angle to the total input power over 4 .
The relative power antenna gain
It is the power gain of the antenna concerned in certain direction to
the power gain of a reference antenna assuming the input power is the
same for each antenna. The reference antenna may be isotropic antenna or
dipole antenna. The isotropic antenna radiates equally in all directions in
all planes like point of source. It is fictions or hypothetical antenna and is
used as a reference.
3.7.3 Head /Body Losses (dB)
Head /body loss refers to the attenuation of the radio signal during
both transmission and reception as the mobile station antenna is held to
the ear of the mobile station (MS). At personal communication system
(PCS) and cellular frequencies, this attenuation is mainly due to the head
of the user while at lower frequencies (large wave lengths) the entire
human body could distort the radiation pattern of the mobile station
antenna. Head/body losses are the amount of power that is absorbed
through the head and body of the human being from MS.
Typically head /body loss values range from 2 to 5 dB (3dB).Values
to be used in the link budget are typically provided by the wireless
network operator based on field measurements or prior experience. It is
Chapter 3: Coverage dimensioning
3 - 10
The value taken for MS antenna gain ranges between 0 dB this is the
gain of the mobile station (MS) antenna. At both cellular and personal
communication system (PCS) frequencies, this is a dipole whose gain can
be taken to be 2.2 dBi.
Mobile station (MS) antenna gain is defined either absolute gain or
relative gain.
The absolute gain: it is the ratio of maximum radiation intensity in
(watts) per unit solid angle to the total input power over 4 .
The relative power antenna gain
It is the power gain of the antenna concerned in certain direction to
the power gain of a reference antenna assuming the input power is the
same for each antenna. The reference antenna may be isotropic antenna or
dipole antenna. The isotropic antenna radiates equally in all directions in
all planes like point of source. It is fictions or hypothetical antenna and is
used as a reference.
3.7.3 Head /Body Losses (dB)
Head /body loss refers to the attenuation of the radio signal during
both transmission and reception as the mobile station antenna is held to
the ear of the mobile station (MS). At personal communication system
(PCS) and cellular frequencies, this attenuation is mainly due to the head
of the user while at lower frequencies (large wave lengths) the entire
human body could distort the radiation pattern of the mobile station
antenna. Head/body losses are the amount of power that is absorbed
through the head and body of the human being from MS.
Typically head /body loss values range from 2 to 5 dB (3dB).Values
to be used in the link budget are typically provided by the wireless
network operator based on field measurements or prior experience. It is
Chapter 3: Coverage dimensioning
3 - 10
The value taken for MS antenna gain ranges between 0 dB this is the
gain of the mobile station (MS) antenna. At both cellular and personal
communication system (PCS) frequencies, this is a dipole whose gain can
be taken to be 2.2 dBi.
Mobile station (MS) antenna gain is defined either absolute gain or
relative gain.
The absolute gain: it is the ratio of maximum radiation intensity in
(watts) per unit solid angle to the total input power over 4 .
The relative power antenna gain
It is the power gain of the antenna concerned in certain direction to
the power gain of a reference antenna assuming the input power is the
same for each antenna. The reference antenna may be isotropic antenna or
dipole antenna. The isotropic antenna radiates equally in all directions in
all planes like point of source. It is fictions or hypothetical antenna and is
used as a reference.
3.7.3 Head /Body Losses (dB)
Head /body loss refers to the attenuation of the radio signal during
both transmission and reception as the mobile station antenna is held to
the ear of the mobile station (MS). At personal communication system
(PCS) and cellular frequencies, this attenuation is mainly due to the head
of the user while at lower frequencies (large wave lengths) the entire
human body could distort the radiation pattern of the mobile station
antenna. Head/body losses are the amount of power that is absorbed
through the head and body of the human being from MS.
Typically head /body loss values range from 2 to 5 dB (3dB).Values
to be used in the link budget are typically provided by the wireless
network operator based on field measurements or prior experience. It is
Chapter 3: Coverage dimensioning
3 - 11
important to obtain these values from the operator since any design loss
raises design cell count.
It worth to mention that in fixed wireless local loop (FWLL), the
head /body loss is zero while in mobile cellular mobile has a value.
3.7.4 Physical resource block:
A resource element is the smallest unit in the physical layer and
occupies one OFDM or OFDMA symbol in the time domain and one
subcarrier in the frequency domain.
A transmitted OFDMA signal can be carried by a number of parallel
subcarriers.
Each LTE subcarrier is 15 kHz. Twelve subcarriers (180 kHz) are
grouped into a resource block. Depending on the carrier bandwidth, LTE
supports a varying number of resource blocks. The downlink has an
unused central subcarrier.
The following illustration shows resource block definition:
Figure (3-2) Resource Block Definition in Frequency Domain.
A resource block is limited in both the frequency and time domains.
One resource block is 12 subcarriers during one slot (0.5 ms).
Chapter 3: Coverage dimensioning
3 - 11
important to obtain these values from the operator since any design loss
raises design cell count.
It worth to mention that in fixed wireless local loop (FWLL), the
head /body loss is zero while in mobile cellular mobile has a value.
3.7.4 Physical resource block:
A resource element is the smallest unit in the physical layer and
occupies one OFDM or OFDMA symbol in the time domain and one
subcarrier in the frequency domain.
A transmitted OFDMA signal can be carried by a number of parallel
subcarriers.
Each LTE subcarrier is 15 kHz. Twelve subcarriers (180 kHz) are
grouped into a resource block. Depending on the carrier bandwidth, LTE
supports a varying number of resource blocks. The downlink has an
unused central subcarrier.
The following illustration shows resource block definition:
Figure (3-2) Resource Block Definition in Frequency Domain.
A resource block is limited in both the frequency and time domains.
One resource block is 12 subcarriers during one slot (0.5 ms).
Chapter 3: Coverage dimensioning
3 - 11
important to obtain these values from the operator since any design loss
raises design cell count.
It worth to mention that in fixed wireless local loop (FWLL), the
head /body loss is zero while in mobile cellular mobile has a value.
3.7.4 Physical resource block:
A resource element is the smallest unit in the physical layer and
occupies one OFDM or OFDMA symbol in the time domain and one
subcarrier in the frequency domain.
A transmitted OFDMA signal can be carried by a number of parallel
subcarriers.
Each LTE subcarrier is 15 kHz. Twelve subcarriers (180 kHz) are
grouped into a resource block. Depending on the carrier bandwidth, LTE
supports a varying number of resource blocks. The downlink has an
unused central subcarrier.
The following illustration shows resource block definition:
Figure (3-2) Resource Block Definition in Frequency Domain.
A resource block is limited in both the frequency and time domains.
One resource block is 12 subcarriers during one slot (0.5 ms).
Chapter 3: Coverage dimensioning
3 - 12
In the downlink, the time-frequency plane of OFDMA structure is used to
its full potential. The scheduler can allocate resource blocks anywhere,
even non-contiguously.
A variant used in the uplink requires the scheduled bandwidth to be
contiguous and a single carrier. The method, called SC-FDMA, can be
considered a separate multiple access method.
A user is scheduled every Transmit Time Interval (TTI) of 1 ms,
indicating a minimum of two consecutive resource blocks in time at every
scheduling instance. The minimum scheduling in the frequency
dimension is the width of one resource block. The scheduler is free to
schedule users both in the frequency and time domain.
The illustration in shows user scheduling in the time and frequency
domain for downlink and uplink:
Figure (3-3) Downlink and Uplink User Scheduling in Time and
Frequency Domain.
Chapter 3: Coverage dimensioning
3 - 12
In the downlink, the time-frequency plane of OFDMA structure is used to
its full potential. The scheduler can allocate resource blocks anywhere,
even non-contiguously.
A variant used in the uplink requires the scheduled bandwidth to be
contiguous and a single carrier. The method, called SC-FDMA, can be
considered a separate multiple access method.
A user is scheduled every Transmit Time Interval (TTI) of 1 ms,
indicating a minimum of two consecutive resource blocks in time at every
scheduling instance. The minimum scheduling in the frequency
dimension is the width of one resource block. The scheduler is free to
schedule users both in the frequency and time domain.
The illustration in shows user scheduling in the time and frequency
domain for downlink and uplink:
Figure (3-3) Downlink and Uplink User Scheduling in Time and
Frequency Domain.
Chapter 3: Coverage dimensioning
3 - 12
In the downlink, the time-frequency plane of OFDMA structure is used to
its full potential. The scheduler can allocate resource blocks anywhere,
even non-contiguously.
A variant used in the uplink requires the scheduled bandwidth to be
contiguous and a single carrier. The method, called SC-FDMA, can be
considered a separate multiple access method.
A user is scheduled every Transmit Time Interval (TTI) of 1 ms,
indicating a minimum of two consecutive resource blocks in time at every
scheduling instance. The minimum scheduling in the frequency
dimension is the width of one resource block. The scheduler is free to
schedule users both in the frequency and time domain.
The illustration in shows user scheduling in the time and frequency
domain for downlink and uplink:
Figure (3-3) Downlink and Uplink User Scheduling in Time and
Frequency Domain.
Chapter 3: Coverage dimensioning
3 - 13
The bit rate requirement should be based on the service for which the
system is dimensioned, and as a compromise between conflicting needs
and trends, with the following considerations:
With a small 'PRBn the required bit rate can be satisfied with a minimum
of resources. This leaves a maximum amount of space in the time-
frequency resource plane for other users to maximize capacity.
At a large 'PRBn , the transmitted blocks are spread over a frequency
interval, with less power used per physical resource block. A lower
modulation scheme and/or a higher coding rate can be selected. The
receiver is capable of decoding the transmissions at lower SINR, to give a
higher path loss leading to an increased cell range. Additionally, the user
equipment can reduce maximum output power when using large 'PRBn
according to the 3GPP document user equipment (UE) radio transmission
and reception. The back-off allowed is not assumed to be used at cell
edge.
The impact from noise rise on the resulting coverage range when
varying 'PRBn in the dimensioning plays a comparatively minor role, unless
the noise rise is very high.
All physical resource blocks must be consecutive in the uplink.
Large 'PRBn may be less probable if the scheduler operates efficiently.
Using a few different values of for calculating the link budget can be
helpful.
3.7.5 User equipment effective isotropic radiated power (EIRP) per
physical resource Block (PRB)
All allocated resource blocks share the total user equipment output
power.
Chapter 3: Coverage dimensioning
3 - 14
Assuming that all resource blocks are allocated an equal amount of
power, the power per physical resource block (PRB )is calculated in the
following way:
Equation (3-1) represents power of user equipment per physical
resource block
Equation (3-2) represents Effective Isotropic Radiated Power of user
equipment
Where:
GUE is the user equipment transmitting antenna gain [dBi]
LHBL is the head body loss [dB ]
Gother is the gain due to using MIMO.
LHBL is head/ body loss [dB]
EIRP means effective or equivalent isotropic radiated power. This
refers to the effective isotropically radiated power from the mobile station
(MS) at the antenna connector or it is the power radiated within a given
geographical. It is the effective input power to hypothetically isotropic
antenna that achieves the maximum radiated intensity in any direction. It
is a function of the MS transmitted power and the MS transmitter antenna
gain and head/body losses.
3.7.6 eNodeB receiver thermal noise density No
This simply refers to the thermal noise floor at absolute temperature.
No is eNodeB thermal noise density and given by:
No = 10log KT
Chapter 3: Coverage dimensioning
3 - 14
Assuming that all resource blocks are allocated an equal amount of
power, the power per physical resource block (PRB )is calculated in the
following way:
Equation (3-1) represents power of user equipment per physical
resource block
Equation (3-2) represents Effective Isotropic Radiated Power of user
equipment
Where:
GUE is the user equipment transmitting antenna gain [dBi]
LHBL is the head body loss [dB ]
Gother is the gain due to using MIMO.
LHBL is head/ body loss [dB]
EIRP means effective or equivalent isotropic radiated power. This
refers to the effective isotropically radiated power from the mobile station
(MS) at the antenna connector or it is the power radiated within a given
geographical. It is the effective input power to hypothetically isotropic
antenna that achieves the maximum radiated intensity in any direction. It
is a function of the MS transmitted power and the MS transmitter antenna
gain and head/body losses.
3.7.6 eNodeB receiver thermal noise density No
This simply refers to the thermal noise floor at absolute temperature.
No is eNodeB thermal noise density and given by:
No = 10log KT
Chapter 3: Coverage dimensioning
3 - 14
Assuming that all resource blocks are allocated an equal amount of
power, the power per physical resource block (PRB )is calculated in the
following way:
Equation (3-1) represents power of user equipment per physical
resource block
Equation (3-2) represents Effective Isotropic Radiated Power of user
equipment
Where:
GUE is the user equipment transmitting antenna gain [dBi]
LHBL is the head body loss [dB ]
Gother is the gain due to using MIMO.
LHBL is head/ body loss [dB]
EIRP means effective or equivalent isotropic radiated power. This
refers to the effective isotropically radiated power from the mobile station
(MS) at the antenna connector or it is the power radiated within a given
geographical. It is the effective input power to hypothetically isotropic
antenna that achieves the maximum radiated intensity in any direction. It
is a function of the MS transmitted power and the MS transmitter antenna
gain and head/body losses.
3.7.6 eNodeB receiver thermal noise density No
This simply refers to the thermal noise floor at absolute temperature.
No is eNodeB thermal noise density and given by:
No = 10log KT
Chapter 3: Coverage dimensioning
3 - 15
Where:
K is Boltzman constant = 1.3806488 × 10-23 Watt/Hertz/Kelvin or
joule /Kelvin (J/K)
T is temperature in kelvin degree =290 degree Kelvin or degree
Celsius (K) =273+17 degree centigrade
No =10 log (1.3806488 × 10-23 *290) / 1 mW = -174 dBm/Hz
Equation (3-3) represents eNodeB receiver thermal noise density
3.7.7 eNodeB receiver noise figure (NF) (dB)
The eNodeB receiver noise figure (NF) is a measure of the signal to
noise ratio (SNR) degradation when signal enters receiver till SNRi reach
the input of demodulator by the eNodeB front end RF amplifier and filter
Noise figure is given by:
NF=10 log (SNRi / SNRo)
Equation (3-4) eNodeB receiver noise figure.
Where:
SNR: It is the input signal to noise ratio. SNRo is the output signal to
noise ratio.
3.7.8 The uplink required bit rate per physical resource Block (PRB)
(Rbrequired, PRB,UL)
Dimensioning starts by defining the quality requirement. Quality is
expressed as a certain bit rate that can be provided to one individual user
at the cell edge with a certain probability. The required bit rate follows
the service for which the system is dimensioned.
All calculations are performed per physical resource block. Table (3-1)
shows how to obtain the required bit rate per physical resource block; the
required bit rate is divided by the number of physical resource blocks 'PRBn
Chapter 3: Coverage dimensioning
3 - 16
that can be allocated to obtain that bit rate. The required bit rate per
resource block is given by:
Equation (3-5) represents the required bit rate per physical resource
block
Where:
: Required bit rate
: Physical resource block
In a real system, 'PRBn is selected by the scheduler on a 1 ms Time
Transmission Interval (TTI) level. In a dimensioning exercise, the
number 'PRBn can be selected freely, guided by experience and
understanding of the system within the constraints of total deployed
bandwidth, as shown in table (3-1).
Table (3-1) bandwidths and number of physical resource blocks (PRB)
specified in 3GPP
3.7.9 The uplink required SINR ( ) given the uplink required bit
rate Rrequired, PRB
Chapter 3: Coverage dimensioning
3 - 16
that can be allocated to obtain that bit rate. The required bit rate per
resource block is given by:
Equation (3-5) represents the required bit rate per physical resource
block
Where:
: Required bit rate
: Physical resource block
In a real system, 'PRBn is selected by the scheduler on a 1 ms Time
Transmission Interval (TTI) level. In a dimensioning exercise, the
number 'PRBn can be selected freely, guided by experience and
understanding of the system within the constraints of total deployed
bandwidth, as shown in table (3-1).
Table (3-1) bandwidths and number of physical resource blocks (PRB)
specified in 3GPP
3.7.9 The uplink required SINR ( ) given the uplink required bit
rate Rrequired, PRB
Chapter 3: Coverage dimensioning
3 - 16
that can be allocated to obtain that bit rate. The required bit rate per
resource block is given by:
Equation (3-5) represents the required bit rate per physical resource
block
Where:
: Required bit rate
: Physical resource block
In a real system, 'PRBn is selected by the scheduler on a 1 ms Time
Transmission Interval (TTI) level. In a dimensioning exercise, the
number 'PRBn can be selected freely, guided by experience and
understanding of the system within the constraints of total deployed
bandwidth, as shown in table (3-1).
Table (3-1) bandwidths and number of physical resource blocks (PRB)
specified in 3GPP
3.7.9 The uplink required SINR ( ) given the uplink required bit
rate Rrequired, PRB
Chapter 3: Coverage dimensioning
3 - 17
Similar to High Speed Packet Access (HSPA) in WCDMA, LTE
includes a variety of different transport formats with different modulation
and coding schemes. Each format has a specified bit rate. The SINR
requirement for decoding a particular transport format has been
determined by a large set of simulations. The simulation results in a set of
tables for different channel models and for different antenna
arrangements. As an approximation, the simulation results have been
fitted to a semi-empirical parameterized expression. The expression for
the dependency between Rrequired,PRB and the SINR is expressed along
with the semi-empirical constants a0, a1, a2 and a3.
Using the required bit rate Rrequired,PRB , a SINR is obtained that
represents the requirement on signal quality.
For the transport formats in LTE, given the required bit rate per resource
block, RPRB, the signal-to-interference-and-noise ratio (SINR), γ, is
determined by a set of link simulations.
The uplink cases simulated include the following:
Antenna techniques: 2-branch RX diversity
Modulation schemes: QPSK, 16-QAM
Channel models and Doppler frequency EPA 5 Hz, EVA 70
Hz, ETU 300Hz
Performance analysis of multipath propagation channels:
The multipath propagation condition consists of several parts:
A delay profile in the form of a ―tapped delay-line‖, characterized
by a number of tapes at fixed positions on a sampling grid. The
profile can be further characterized by the r.m.s delay spread and
the maximum delay spanned by the taps.
Chapter 3: Coverage dimensioning
3 - 18
A combination of channel model parameters that include the Delay
profile and Doppler spectrum that characterized by a classical
spectrum shape and a maximum Doppler frequency.
Both delay profiles and Doppler spectrum for various E-UTRA
channel models were considered. The delay profiles are selected to be
representative of low, medium and high delay spread environments. The
resulting model parameters.
Here the Excess tap delay and Relative power were analysed and the
mobile radio channels such as Extended Pedestrian A, Extended
Vehicular A, Extended typical urban Model and HSTC model
performance were compared using the Table (3-2).Model No. of channels taps Max. Delay
Extended Pedestrian A
(EPA)7 410 ns
Extended Vehicular A(EVA) 9 2510ns
Extended typical urban(ETU) 9 5000ns
Table (3-2) Channel models specifications
Table (3-3) Channel model specifications
EPA EVA
Excess tab delay(ns) Relative power
(dB)
Excess tab
delay(ns)
Relative power (dB)
0 0 0 0
30 -1 -30 -1.5
70 -2 150 -1.4
90 -3 310 -3.6
110 -8 370 -0.6
190 -17.2 710 -9.1
410 -20.8 1090 -7
Chapter 3: Coverage dimensioning
3 - 19
Extended urban and HSTC modelETU HSTC model
Excess tap delay (ns) Excess tap delay (ns) Excess tap delay (ns) Excess tap delay (ns)
0 -1 0 -1
50 -1 900 -21
120 -1 1900 -35
200 0 2200 -39
230 0 2700 -39.1
500 0 6100 -43
1600 -3 7100 -21.2
2300 -5 10100 -35
5000 -7 - -
Table (3-4) channel propagation conditions
Table (3-4) shows channel propagation conditions that are used for
the performance measurements in multi-path fading environment for low,
medium and high Doppler frequencies. In this paper, the combination of
channel models that include the Delay profile and the Doppler spectrum
are considered for the simulation [5].Model Maximum Doppler frequency
EPA 5 Hz
EVA 70 Hz
ETU 300 Hz
HSTC 1340 Hz
Table (3-5) Maximum Doppler frequency channel model
Table (4&5) shows multi-path delay profiles that are used for the
performance measurements in multi-path fading environment. The Excess
tap delay functions can be expressed in terms of Doppler spectrum as
mentioned below.
S (f) ∝1/((1-(f/fd)2)0.5
Equation (3-6) represents Doppler spectrum
Chapter 3: Coverage dimensioning
3 - 20
Where:
S (f): Doppler spectrum,
f: Frequency,
fd: It is the Doppler frequency which proportional inversely with Doppler
spectrum.
1- Extended Pedestrian A (EPA)
Extended Pedestrian A. A propagation channel model based on the
International Telecommunication Union (ITU) Pedestrian A model,
extended to a wider bandwidth of 20 MHz.
The pedestrian channel model represents a UE speed of 3 km/h. It
described by
Tau: is a vector of path delays, each specified in nano seconds.
Tau: [0 30 70 90 110 190 410]/109
PDB (Power Delayed Bus): is a vector of relative path powers, in dB
PDB = [0 -1 -2 -3 -8 -17.2 -20.8]
2- Extended Vehicular A (EVA)
• Extended Vehicular A. A propagation channel model based on the
International Telecommunication Union (ITU) Vehicular A model,
extended to a wider bandwidth of 20 MHz.
• The vehicular channel model represents UE speeds of 30, 120 km/h and
higher.
Tau= [0 30 150 310 370 710 1090 1730 2510]/ (109).
PDB= [0 -1.5 -1.4 -3.6 -0.6 -9.1 -7 -12 -16.9].
3-Extended Terrestrial Urban (ETU)
A propagation channel model based on the GSM Typical Urban model,
extended to a wider bandwidth of 20 MHz It models a scattering
environment which is considered to be typical in a urban area.
Chapter 3: Coverage dimensioning
3 - 21
Tau= [0 50 120 200 230 500 1600 2300 5000]/(10^9)
PDB=[-1 -1 -1 0 0 0 -3 -5 -7]
3.7.10 the required signal-to-interference-and-noise ratio SINR ett arg
given the required bit rate RPRB
The results, including an implementation margin, have been fitted to
a semi-empirical parameterized expression for the required signal-to-
interference-and-noise ratio SINR ett arg given the required bit rate RPRB is
written as follows:
Equation (3-7) represents the required signal-to-interference-and-noise
ratio SINR.
The semi-empirical parameters for uplink a0, a1,a2 and a3 are given in
tables (3.6)
Table (3- 6) semi-empirical parameters for uplink
3.7.11 eNodeB receiver sensitivity (SeNodeB)
eNodeB receiver sensitivity SeNodeB is the required signal power at
the system reference point when there is no interference contribution
from other user equipments. The following relation describes eNodeB
receiver sensitivity per physical resource block (PRB):
Chapter 3: Coverage dimensioning
3 - 21
Tau= [0 50 120 200 230 500 1600 2300 5000]/(10^9)
PDB=[-1 -1 -1 0 0 0 -3 -5 -7]
3.7.10 the required signal-to-interference-and-noise ratio SINR ett arg
given the required bit rate RPRB
The results, including an implementation margin, have been fitted to
a semi-empirical parameterized expression for the required signal-to-
interference-and-noise ratio SINR ett arg given the required bit rate RPRB is
written as follows:
Equation (3-7) represents the required signal-to-interference-and-noise
ratio SINR.
The semi-empirical parameters for uplink a0, a1,a2 and a3 are given in
tables (3.6)
Table (3- 6) semi-empirical parameters for uplink
3.7.11 eNodeB receiver sensitivity (SeNodeB)
eNodeB receiver sensitivity SeNodeB is the required signal power at
the system reference point when there is no interference contribution
from other user equipments. The following relation describes eNodeB
receiver sensitivity per physical resource block (PRB):
Chapter 3: Coverage dimensioning
3 - 21
Tau= [0 50 120 200 230 500 1600 2300 5000]/(10^9)
PDB=[-1 -1 -1 0 0 0 -3 -5 -7]
3.7.10 the required signal-to-interference-and-noise ratio SINR ett arg
given the required bit rate RPRB
The results, including an implementation margin, have been fitted to
a semi-empirical parameterized expression for the required signal-to-
interference-and-noise ratio SINR ett arg given the required bit rate RPRB is
written as follows:
Equation (3-7) represents the required signal-to-interference-and-noise
ratio SINR.
The semi-empirical parameters for uplink a0, a1,a2 and a3 are given in
tables (3.6)
Table (3- 6) semi-empirical parameters for uplink
3.7.11 eNodeB receiver sensitivity (SeNodeB)
eNodeB receiver sensitivity SeNodeB is the required signal power at
the system reference point when there is no interference contribution
from other user equipments. The following relation describes eNodeB
receiver sensitivity per physical resource block (PRB):
Chapter 3: Coverage dimensioning
3 - 22
Equation (3-8) represents eNodeB receiver sensitivity
Where
Nt is the thermal noise power density and is equal -174 dBm/Hz
NfeNodeB is the noise figure of the eNodeB receiver [dB]
WPRB is the bandwidth per physical resource block (PRB): 180 kHz
ULett ,arg is SINR requirement for the uplink traffic channel [dB]
ULPRBN , is the thermal noise per physical resource block in uplink is
given by:
Equation (3-9) represents the thermal noise per physical resource
block in uplink
The eNodeB receiver can be assumed to have a noise figure of 2 dB with
tower mounted amplifier (TMA) and 3 dB without.
3.7.12 Up link noise rise or interference margin (IM) BIUL :
In LTE a user does not interfere with other users in the cell since
they are separated in the frequency/time domain. The noise rise in the
uplink depends only on interference from adjacent cells. In the link
budget, an interference margin compensates for noise rise. The standard
case of closed loop power control is shown as a linear ratio. The uplink
interference margin is given by:
Equation (3-10) represents Up link noise rise or interference margin.
Where:
Chapter 3: Coverage dimensioning
3 - 22
Equation (3-8) represents eNodeB receiver sensitivity
Where
Nt is the thermal noise power density and is equal -174 dBm/Hz
NfeNodeB is the noise figure of the eNodeB receiver [dB]
WPRB is the bandwidth per physical resource block (PRB): 180 kHz
ULett ,arg is SINR requirement for the uplink traffic channel [dB]
ULPRBN , is the thermal noise per physical resource block in uplink is
given by:
Equation (3-9) represents the thermal noise per physical resource
block in uplink
The eNodeB receiver can be assumed to have a noise figure of 2 dB with
tower mounted amplifier (TMA) and 3 dB without.
3.7.12 Up link noise rise or interference margin (IM) BIUL :
In LTE a user does not interfere with other users in the cell since
they are separated in the frequency/time domain. The noise rise in the
uplink depends only on interference from adjacent cells. In the link
budget, an interference margin compensates for noise rise. The standard
case of closed loop power control is shown as a linear ratio. The uplink
interference margin is given by:
Equation (3-10) represents Up link noise rise or interference margin.
Where:
Chapter 3: Coverage dimensioning
3 - 22
Equation (3-8) represents eNodeB receiver sensitivity
Where
Nt is the thermal noise power density and is equal -174 dBm/Hz
NfeNodeB is the noise figure of the eNodeB receiver [dB]
WPRB is the bandwidth per physical resource block (PRB): 180 kHz
ULett ,arg is SINR requirement for the uplink traffic channel [dB]
ULPRBN , is the thermal noise per physical resource block in uplink is
given by:
Equation (3-9) represents the thermal noise per physical resource
block in uplink
The eNodeB receiver can be assumed to have a noise figure of 2 dB with
tower mounted amplifier (TMA) and 3 dB without.
3.7.12 Up link noise rise or interference margin (IM) BIUL :
In LTE a user does not interfere with other users in the cell since
they are separated in the frequency/time domain. The noise rise in the
uplink depends only on interference from adjacent cells. In the link
budget, an interference margin compensates for noise rise. The standard
case of closed loop power control is shown as a linear ratio. The uplink
interference margin is given by:
Equation (3-10) represents Up link noise rise or interference margin.
Where:
Chapter 3: Coverage dimensioning
3 - 23
ULett arg is the SINR target for the uplink open loop power control.
ULQ is average uplink system load.
CLF is defined as the ratio of actual capacity to pole point capacity.
Pole point capacity is defined as the capacity when all user equipment
raise their power to infinity this is a hypothetical situation which is taken
as a reference.
F is the average ratio of path gains for interfering cells to those of the
serving cell.
F is defined and investigated thoroughly for WCDMA radio network
dimensioning. Table (3.7) gives values for F at varying electric tilt with
30 meter antenna height and 3-sector sites. The values are based on
system simulations.
Table (3.7) examples of F for varying tilt
3.7.13 Log normal fading margin:
Fading is defined as the random variation (change or fluctuation) of
the received signal. There are different types of fading: large scale or
slow fading and small scale or fast fading.
Fading is described using probability density functions: large scale or
slow fading is log normal distributed while small scale or fast fading
which is Rayleigh or Rican distributed. Rayleigh distribution describes
Chapter 3: Coverage dimensioning
3 - 24
the received signal is due to only reflection and there is no line of sight
(LOS). Log normal distribution describes signal changes due to
abstraction in the path between eNodeB and mobile station (MS).
Fading margin is an extra margin is included in the link budget. The
lognormal fade margin is calculated based on the coverage objective,
which is typically specified as a target coverage probability at cell edge.
Typical numbers are 90% and 75% edge coverage probability. Achieving
90% edge coverage implies that at 90% of the locations at edge, a cell can
be initiated and kept up.
Using path loss models, one can relate area coverage probability to
edge coverage probability and hence to fade margin requirement. 95%
area coverage probability is mapped to 75% edge coverage. These values
presume a completely noise limited receiver.
The lognormal (or slow fading) margin models the required area
coverage probability. By adding this margin, a probability is secured for
setting up and maintaining a connection at a given quality.
Table (3.8) shows fading margins in dB for varying standard deviation σ
of the lognormal fading process and different coverage probabilities:
Table (3.8) log normal fading margins for varying standard deviation of
lognormal Fading
Chapter 3: Coverage dimensioning
3 - 25
Equation (3-11) represents Log normal fading margin
Where:
is the mean of log normal.
is the standard deviation of log normal.
P% is the coverage probability
The standard components are given for link analysis in the radio
interface. The standard margins for indoor, car penetration loss, body
loss, feeder loss, jumper loss, and antenna gain are the same as any
mobile network. A fading margin is required to guarantee a certain
coverage probability. MAPLUL represents the maximum allowable path
loss in uplink link budget, fed into the downlink link budget.
3.7.14 eNodeB receiver cable feeder, jumper and connector losses
Feeder cable loss
Feeder cable loss is the loss of electrical energy due to the inherent
characteristics of the feeder cable. The eNodeB receiver feeder cable is
dependent on the feeder type and length of feeder run. The receiver cable
and connector losses are nominally taken in the range of 2 dB to 4 dB.
When the cable length and diameter (and hence attenuation/feet) are
known, the actual cable losses may be substituted in the link budget along
with additional margin of 0.5 dB for connector (and duplexer) losses.
Radio equipment should be placed as close as possible to the antennas in
order to reduce the feeder cable loss.
Typically feeder cable diameters used are 7/8" and 15/8" and
corresponding attenuations are 6.15 dB/100 meters and 3.84 dB/meters.
Jumper loss "Lj"
Chapter 3: Coverage dimensioning
3 - 25
Equation (3-11) represents Log normal fading margin
Where:
is the mean of log normal.
is the standard deviation of log normal.
P% is the coverage probability
The standard components are given for link analysis in the radio
interface. The standard margins for indoor, car penetration loss, body
loss, feeder loss, jumper loss, and antenna gain are the same as any
mobile network. A fading margin is required to guarantee a certain
coverage probability. MAPLUL represents the maximum allowable path
loss in uplink link budget, fed into the downlink link budget.
3.7.14 eNodeB receiver cable feeder, jumper and connector losses
Feeder cable loss
Feeder cable loss is the loss of electrical energy due to the inherent
characteristics of the feeder cable. The eNodeB receiver feeder cable is
dependent on the feeder type and length of feeder run. The receiver cable
and connector losses are nominally taken in the range of 2 dB to 4 dB.
When the cable length and diameter (and hence attenuation/feet) are
known, the actual cable losses may be substituted in the link budget along
with additional margin of 0.5 dB for connector (and duplexer) losses.
Radio equipment should be placed as close as possible to the antennas in
order to reduce the feeder cable loss.
Typically feeder cable diameters used are 7/8" and 15/8" and
corresponding attenuations are 6.15 dB/100 meters and 3.84 dB/meters.
Jumper loss "Lj"
Chapter 3: Coverage dimensioning
3 - 25
Equation (3-11) represents Log normal fading margin
Where:
is the mean of log normal.
is the standard deviation of log normal.
P% is the coverage probability
The standard components are given for link analysis in the radio
interface. The standard margins for indoor, car penetration loss, body
loss, feeder loss, jumper loss, and antenna gain are the same as any
mobile network. A fading margin is required to guarantee a certain
coverage probability. MAPLUL represents the maximum allowable path
loss in uplink link budget, fed into the downlink link budget.
3.7.14 eNodeB receiver cable feeder, jumper and connector losses
Feeder cable loss
Feeder cable loss is the loss of electrical energy due to the inherent
characteristics of the feeder cable. The eNodeB receiver feeder cable is
dependent on the feeder type and length of feeder run. The receiver cable
and connector losses are nominally taken in the range of 2 dB to 4 dB.
When the cable length and diameter (and hence attenuation/feet) are
known, the actual cable losses may be substituted in the link budget along
with additional margin of 0.5 dB for connector (and duplexer) losses.
Radio equipment should be placed as close as possible to the antennas in
order to reduce the feeder cable loss.
Typically feeder cable diameters used are 7/8" and 15/8" and
corresponding attenuations are 6.15 dB/100 meters and 3.84 dB/meters.
Jumper loss "Lj"
Chapter 3: Coverage dimensioning
3 - 26
Jumper loss is the loss of electrical energy due to the connection of
the tower top amplifier with the antenna using jumpers. A typical value of
the jumper is 11.2 dB/100m.When the used jumper type and length is
known, the total jumper loss can be calculated.
Connector loss "Lc"
It is the loss of electrical energy because of connectors that make the
antennas tied with the top of the tower. A typical value of the connector
loss is 1 dB.
3.7.15 Building / vehicle penetration loss:
This refers to the attenuation of the signal as it passes through one or
more walls of the building in the desired coverage area. When a mobile
station (MS) is used inside the building and the eNodeB is situated
outside, there is a loss when the signal penetrates the building. It is
defined as the difference between the average signal strength outside the
buildings and the average signal strength over the ground floor of the
building. The value of penetration loss must be included when designing
link budget. Table (3.9) shows the value of penetration loss on different
morphology classesIn building dense
urban
In building
suburban
In building rural In car
20 18 12 9
Table (3-9) values of penetration loss on different morphology classes
When the MS is situated in a car without external antenna, an extra
margin has to be added to cope with the penetration loss of the car. This
extra margin is typically 9 dB.
Chapter 3: Coverage dimensioning
3 - 27
3.7.16 eNodeB receiver antenna gain (dBi)
This refers to the gain of the receiving antenna at eNobeB .While the
actual antennas used in the network may vary from site to site, a nominal,
representative value is provided in the link budget based on the frequency
of operation and sectorization.
The nominal antenna gain values for personal communication
systems (PCS) and cellular frequencies differ based on the cell Omni or
sectorized .The gain units are dBi or gain with respect to an isotropic
radiator. The value of antenna gain also can be varied depending to the
manufacturer. Typically a value of eNondeB receiver antenna gain is
typically 12 dBi for omni cell and 18 dBi for sectorized cell
3.7.17 Uplink link budget maximum allowable path loss (MAPLUL)
Finally, the uplink link budget maximum allowable path loss
(MAPLUL) Can be calculated as follows:
Equation (3-12) represents Uplink link budget maximum allowable
path loss.
Where: (MAPLUL) is the maximum allowable path loss due to
propagation in the air [dB]
BLNF is the log-normal fading margin [dB]
BIUL is the uplink interference margin [dB]
LCPL is the car penetration loss [dB]
LBPL is the building penetration loss [dB]
GeNodeB is the eNodeB receiver antenna gain [dBi]
Gother is the other gain [dBi]
Lf is eNode B feeder loss [ dB ]
Chapter 3: Coverage dimensioning
3 - 27
3.7.16 eNodeB receiver antenna gain (dBi)
This refers to the gain of the receiving antenna at eNobeB .While the
actual antennas used in the network may vary from site to site, a nominal,
representative value is provided in the link budget based on the frequency
of operation and sectorization.
The nominal antenna gain values for personal communication
systems (PCS) and cellular frequencies differ based on the cell Omni or
sectorized .The gain units are dBi or gain with respect to an isotropic
radiator. The value of antenna gain also can be varied depending to the
manufacturer. Typically a value of eNondeB receiver antenna gain is
typically 12 dBi for omni cell and 18 dBi for sectorized cell
3.7.17 Uplink link budget maximum allowable path loss (MAPLUL)
Finally, the uplink link budget maximum allowable path loss
(MAPLUL) Can be calculated as follows:
Equation (3-12) represents Uplink link budget maximum allowable
path loss.
Where: (MAPLUL) is the maximum allowable path loss due to
propagation in the air [dB]
BLNF is the log-normal fading margin [dB]
BIUL is the uplink interference margin [dB]
LCPL is the car penetration loss [dB]
LBPL is the building penetration loss [dB]
GeNodeB is the eNodeB receiver antenna gain [dBi]
Gother is the other gain [dBi]
Lf is eNode B feeder loss [ dB ]
Chapter 3: Coverage dimensioning
3 - 27
3.7.16 eNodeB receiver antenna gain (dBi)
This refers to the gain of the receiving antenna at eNobeB .While the
actual antennas used in the network may vary from site to site, a nominal,
representative value is provided in the link budget based on the frequency
of operation and sectorization.
The nominal antenna gain values for personal communication
systems (PCS) and cellular frequencies differ based on the cell Omni or
sectorized .The gain units are dBi or gain with respect to an isotropic
radiator. The value of antenna gain also can be varied depending to the
manufacturer. Typically a value of eNondeB receiver antenna gain is
typically 12 dBi for omni cell and 18 dBi for sectorized cell
3.7.17 Uplink link budget maximum allowable path loss (MAPLUL)
Finally, the uplink link budget maximum allowable path loss
(MAPLUL) Can be calculated as follows:
Equation (3-12) represents Uplink link budget maximum allowable
path loss.
Where: (MAPLUL) is the maximum allowable path loss due to
propagation in the air [dB]
BLNF is the log-normal fading margin [dB]
BIUL is the uplink interference margin [dB]
LCPL is the car penetration loss [dB]
LBPL is the building penetration loss [dB]
GeNodeB is the eNodeB receiver antenna gain [dBi]
Gother is the other gain [dBi]
Lf is eNode B feeder loss [ dB ]
Chapter 3: Coverage dimensioning
3 - 28
Lj is the Jumper loss [dB]
LC is connector loss [ dB ]
3.8 Morphologies classifications
Dense urban (DU):
Central business districts with skyscrapers or with buildings with having
10 to 20 stories and above, the building separation (S) less than 10
meters. Clutter height higher than 30 meters.
Urban (UR):
Residential , office area, hotels, hospitals etc with buildings having 5 to
10 stories and street width less than 5 meters and building separation (S)
less than 10 meters. Clutter height higher from 15 to 30 meters.
Suburban(SU):
Mix of residential and business communications with 2 to 5 stories shops
and offices. The building separation is (S) less than 20 meters. Villages or
high ways scattered with trees and houses, some obstacles near the MS
but not very congested.
Rural area:
Parks or fields with small trees with height less than 12 meters and 20%
house density of residential area of 2 stories with wide roads, The
building separation is (S) less than 20 meters. Clutter height higher than
3o meters.
Open areas:
Clutter height higher than 3 meters open areas, parks, fields, paved areas.
Morphology
class
Clutter height
(meters)
Building
separation
(meters)
Morphology definition
Dense urban H>30 S<10 Building height more than 10 stories
Chapter 3: Coverage dimensioning
3 - 29
Urban 15<H<30 S<10Building height between 5 to 10 stories and
street width <5 meters
Suburban 10<H<15 S<10 Residential or office areas of 3-4 stories
Rural H<10 S<20
Residential areas of 2 stories with wide roads,
parks or fields with small trees<12meters and
20% house density
Open H<3 S<20 Open areas, parks, fields, paved areas
Table (3-10) summarizes the features of different morphologies.
3.9 Downlink Budget
The downlink link budget is calculated for the following purposes:
• To determine the limiting link
• To determine the bit rate that can be supported in the downlink at the
uplink cell range limit.
The calculations are performed according to the following steps:
• Path loss from uplink
• Bit rate requirement
• Power per resource block
• Downlink noise rise (interference margin)
• Downlink link budget
• Receiver sensitivity, UE
• Bit rate at the cell edge
• Concluding the link budge
3.9.1 Path loss from Uplink
(MAPLUL) from the uplink link budget calculations is the starting
point of the downlink calculations and is used to obtain a downlink noise
rise estimate. At the end of the link budget calculation process, if the
downlink (MAPLUL) is less than the uplink (MAPLUL), both the uplink
Chapter 3: Coverage dimensioning
3 - 30
and downlink link budgets can be recalculated (including the noise rise)
using the new (MAPLUL).
3.9.2 Bit Rate Requirement
If the bit rate requirement is not expressed per resource block, it is
divided by (Rreq) to obtain (Rreq). As with the uplink, the bit rate
requirement is expressed per resource block in the calculations. However,
unlike the uplink, the downlink scheduler can allocate resource blocks
across the entire deployed bandwidth without requiring them to be
consecutive. It can be shown that it is always favourable to spread the
transmission across as many resource blocks as possible. Assuming this,
the number of allocated
3.9.3 The down link required bit rate (Rb required, PRB,DL ) per physical
resource block (PRB)
If the down link bit rate requirement Rb, required,DL is not expressed per
physical resource block (PRB), it is divided by nPRB to obtain
Rbrequired,PRB,DL .
As with the uplink, the bit rate requirement is expressed per physical
resource block in the calculations. However, unlike the uplink, the
downlink scheduler can allocate physical resource blocks across the
entire deployed bandwidth without requiring them to be consecutive.
It can be shown that it is always favourable to spread the transmission
across as many physical resource blocks (PRB) as possible. Assuming
this, the number of allocated physical resource blocks nPRB in the
downlink for dimensioning is set to the total number of physical resource
blocks for the deployed bandwidth.
Chapter 3: Coverage dimensioning
3 - 31
In this process, the obtained bit rate requirement per physical resource
block is not used directly to calculate power per physical resource block,
but to compare with the rate that can be obtained at the cell edge given by
the uplink link budget. Alternatively, it can be used as a starting point for
link budget calculations.
3.9.4 eNodeB radiated or transmitted power (EIRP) per physical
resource block (PRB)
The power in LTE is shared by all physical resource blocks. It is
assumed that all physical resource blocks are allocated an equal amount
of power. An individual physical resource block has no power control.
Instead, users are scheduled with high rates every millisecond. The e
Node B transmitted or radiated power per physical resource block is:
Equation (3-13) represents eNodeB transmitted power (EIRP) per
physical resource block (PRB).
Where:
Pnorm,ref : is the sum of nominal power from all radio units in the cell at
the reference point [W]. This means if MIMO is used with two radio
units of 20 W each, is equal to 40W.It is expected that 20 W, 40 W and
60 W power classes will be common. The nominal power at the reference
point can be reduced by loss in feeders.
nRB : is physical resource block.
3.9.5 Thermal noise per physical resource block in the downlink
(N PRB,DL )
N PRB,DL is the thermal noise per physical resource block in the downlink,
defined as follows:
Chapter 3: Coverage dimensioning
3 - 31
In this process, the obtained bit rate requirement per physical resource
block is not used directly to calculate power per physical resource block,
but to compare with the rate that can be obtained at the cell edge given by
the uplink link budget. Alternatively, it can be used as a starting point for
link budget calculations.
3.9.4 eNodeB radiated or transmitted power (EIRP) per physical
resource block (PRB)
The power in LTE is shared by all physical resource blocks. It is
assumed that all physical resource blocks are allocated an equal amount
of power. An individual physical resource block has no power control.
Instead, users are scheduled with high rates every millisecond. The e
Node B transmitted or radiated power per physical resource block is:
Equation (3-13) represents eNodeB transmitted power (EIRP) per
physical resource block (PRB).
Where:
Pnorm,ref : is the sum of nominal power from all radio units in the cell at
the reference point [W]. This means if MIMO is used with two radio
units of 20 W each, is equal to 40W.It is expected that 20 W, 40 W and
60 W power classes will be common. The nominal power at the reference
point can be reduced by loss in feeders.
nRB : is physical resource block.
3.9.5 Thermal noise per physical resource block in the downlink
(N PRB,DL )
N PRB,DL is the thermal noise per physical resource block in the downlink,
defined as follows:
Chapter 3: Coverage dimensioning
3 - 31
In this process, the obtained bit rate requirement per physical resource
block is not used directly to calculate power per physical resource block,
but to compare with the rate that can be obtained at the cell edge given by
the uplink link budget. Alternatively, it can be used as a starting point for
link budget calculations.
3.9.4 eNodeB radiated or transmitted power (EIRP) per physical
resource block (PRB)
The power in LTE is shared by all physical resource blocks. It is
assumed that all physical resource blocks are allocated an equal amount
of power. An individual physical resource block has no power control.
Instead, users are scheduled with high rates every millisecond. The e
Node B transmitted or radiated power per physical resource block is:
Equation (3-13) represents eNodeB transmitted power (EIRP) per
physical resource block (PRB).
Where:
Pnorm,ref : is the sum of nominal power from all radio units in the cell at
the reference point [W]. This means if MIMO is used with two radio
units of 20 W each, is equal to 40W.It is expected that 20 W, 40 W and
60 W power classes will be common. The nominal power at the reference
point can be reduced by loss in feeders.
nRB : is physical resource block.
3.9.5 Thermal noise per physical resource block in the downlink
(N PRB,DL )
N PRB,DL is the thermal noise per physical resource block in the downlink,
defined as follows:
Chapter 3: Coverage dimensioning
3 - 32
Equation (3-13) represents Thermal noise per physical resource
block in the downlink
NfUE The assumed noise figure Nf for typical user equipment (UE)
receiver is 7 dB.
3.9. 6 the down link noise rise or interference margin (IM) (BIDL)
The down link noise rise on the cell edge is needed for the link
budget and is calculated using the following expression where all
quantities linear:
Equation (3-14) represents the down link noise rise or interference
margin
Where:
DLQ : is the downlink system load.
FC : is the average ratio between the received power from other cells to
that of own cell at cell edge locations.
The load is modeled with QDL. The link budget must be true for a network
with a given load. Normally, one design input is to determine the load for
which the coverage is available.
The cell plan quality is modeled with the factor FC . FC describes the
ratio of received power from all other cells to that received from own cell
at a location near the cell edge. Table (3-11) gives values at varying
electric tilt with 30 meter antenna height, and 3-sector sites. The values
Chapter 3: Coverage dimensioning
3 - 32
Equation (3-13) represents Thermal noise per physical resource
block in the downlink
NfUE The assumed noise figure Nf for typical user equipment (UE)
receiver is 7 dB.
3.9. 6 the down link noise rise or interference margin (IM) (BIDL)
The down link noise rise on the cell edge is needed for the link
budget and is calculated using the following expression where all
quantities linear:
Equation (3-14) represents the down link noise rise or interference
margin
Where:
DLQ : is the downlink system load.
FC : is the average ratio between the received power from other cells to
that of own cell at cell edge locations.
The load is modeled with QDL. The link budget must be true for a network
with a given load. Normally, one design input is to determine the load for
which the coverage is available.
The cell plan quality is modeled with the factor FC . FC describes the
ratio of received power from all other cells to that received from own cell
at a location near the cell edge. Table (3-11) gives values at varying
electric tilt with 30 meter antenna height, and 3-sector sites. The values
Chapter 3: Coverage dimensioning
3 - 32
Equation (3-13) represents Thermal noise per physical resource
block in the downlink
NfUE The assumed noise figure Nf for typical user equipment (UE)
receiver is 7 dB.
3.9. 6 the down link noise rise or interference margin (IM) (BIDL)
The down link noise rise on the cell edge is needed for the link
budget and is calculated using the following expression where all
quantities linear:
Equation (3-14) represents the down link noise rise or interference
margin
Where:
DLQ : is the downlink system load.
FC : is the average ratio between the received power from other cells to
that of own cell at cell edge locations.
The load is modeled with QDL. The link budget must be true for a network
with a given load. Normally, one design input is to determine the load for
which the coverage is available.
The cell plan quality is modeled with the factor FC . FC describes the
ratio of received power from all other cells to that received from own cell
at a location near the cell edge. Table (3-11) gives values at varying
electric tilt with 30 meter antenna height, and 3-sector sites. The values
Chapter 3: Coverage dimensioning
3 - 33
are based on system simulations. For dimensioning other antenna heights,
see appendix (A)
Table (3-11) examples of Fc at cell edge for varying tilt
3.9.7 The calculated down link SINR on the cell edge
The downlink calculated SINR on the edge of a cell with the size
given by MAPLUL is given by the following equation:
Equation (3-15) represents down link SINR on the cell edge.
3.9.8 The down link calculated bit rate Rcalculated at cell edge
The cell edge down link SINR estimate or calculated is transformed
into a calculated bit rate per physical resource block, Rbcalculated,PRB by the
same type of semi-empirical relationship as for the uplink SINR
requirement . For the downlink, the semi-empirical constants or
parameters a0, a1,a2 and a3 are given in table (3-12) .
Chapter 3: Coverage dimensioning
3 - 33
are based on system simulations. For dimensioning other antenna heights,
see appendix (A)
Table (3-11) examples of Fc at cell edge for varying tilt
3.9.7 The calculated down link SINR on the cell edge
The downlink calculated SINR on the edge of a cell with the size
given by MAPLUL is given by the following equation:
Equation (3-15) represents down link SINR on the cell edge.
3.9.8 The down link calculated bit rate Rcalculated at cell edge
The cell edge down link SINR estimate or calculated is transformed
into a calculated bit rate per physical resource block, Rbcalculated,PRB by the
same type of semi-empirical relationship as for the uplink SINR
requirement . For the downlink, the semi-empirical constants or
parameters a0, a1,a2 and a3 are given in table (3-12) .
Chapter 3: Coverage dimensioning
3 - 33
are based on system simulations. For dimensioning other antenna heights,
see appendix (A)
Table (3-11) examples of Fc at cell edge for varying tilt
3.9.7 The calculated down link SINR on the cell edge
The downlink calculated SINR on the edge of a cell with the size
given by MAPLUL is given by the following equation:
Equation (3-15) represents down link SINR on the cell edge.
3.9.8 The down link calculated bit rate Rcalculated at cell edge
The cell edge down link SINR estimate or calculated is transformed
into a calculated bit rate per physical resource block, Rbcalculated,PRB by the
same type of semi-empirical relationship as for the uplink SINR
requirement . For the downlink, the semi-empirical constants or
parameters a0, a1,a2 and a3 are given in table (3-12) .
Chapter 3: Coverage dimensioning
3 - 34
Table (3-12) Semi-empirical parameters for down link
The downlink cases simulated include the following:
Antenna techniques: SIMO 1x2, TX diversity 2x2, Open loop
Spatial Multiplexing (OLSM) 2x2
Modulation schemes: QPSK, 16-QAM, 64-QAM
Channel models and Doppler frequency: extended pedestrian
model A (EPA) 5 Hz, extended vehicular model A (EVA) 70 Hz,
extended terrestrial urban model (ETU) 300 Hz
Number of OFDM symbols used for PDCCHs: 1
The uplink cases simulated include the following:
• Antenna techniques: 2-branch RX diversity
• Modulation schemes: QPSK, 16-QAM
• Channel models and Doppler frequency EPA 5 Hz, EVA 70
Hz, ETU 300Hz
The results, including an implementation margin, have been fitted to a
semi-empirical parameterized expression for bit rate RPRB as follows:
Equation (3-16) represents the down link calculated bit rate Rcalculated
at cell edge.
Where:
Chapter 3: Coverage dimensioning
3 - 34
Table (3-12) Semi-empirical parameters for down link
The downlink cases simulated include the following:
Antenna techniques: SIMO 1x2, TX diversity 2x2, Open loop
Spatial Multiplexing (OLSM) 2x2
Modulation schemes: QPSK, 16-QAM, 64-QAM
Channel models and Doppler frequency: extended pedestrian
model A (EPA) 5 Hz, extended vehicular model A (EVA) 70 Hz,
extended terrestrial urban model (ETU) 300 Hz
Number of OFDM symbols used for PDCCHs: 1
The uplink cases simulated include the following:
• Antenna techniques: 2-branch RX diversity
• Modulation schemes: QPSK, 16-QAM
• Channel models and Doppler frequency EPA 5 Hz, EVA 70
Hz, ETU 300Hz
The results, including an implementation margin, have been fitted to a
semi-empirical parameterized expression for bit rate RPRB as follows:
Equation (3-16) represents the down link calculated bit rate Rcalculated
at cell edge.
Where:
Chapter 3: Coverage dimensioning
3 - 34
Table (3-12) Semi-empirical parameters for down link
The downlink cases simulated include the following:
Antenna techniques: SIMO 1x2, TX diversity 2x2, Open loop
Spatial Multiplexing (OLSM) 2x2
Modulation schemes: QPSK, 16-QAM, 64-QAM
Channel models and Doppler frequency: extended pedestrian
model A (EPA) 5 Hz, extended vehicular model A (EVA) 70 Hz,
extended terrestrial urban model (ETU) 300 Hz
Number of OFDM symbols used for PDCCHs: 1
The uplink cases simulated include the following:
• Antenna techniques: 2-branch RX diversity
• Modulation schemes: QPSK, 16-QAM
• Channel models and Doppler frequency EPA 5 Hz, EVA 70
Hz, ETU 300Hz
The results, including an implementation margin, have been fitted to a
semi-empirical parameterized expression for bit rate RPRB as follows:
Equation (3-16) represents the down link calculated bit rate Rcalculated
at cell edge.
Where:
Chapter 3: Coverage dimensioning
3 - 35
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
3.9.9 Concluding link budget according to required and calculated
bit rate
The resulting or calculated bit rate is multiplied by the number of
physical resource blocks (PRB) (nPRB) to obtain the maximum calculated
bit rate (Rcalculated) expected on the cell edge. If the uplink is really the
limiting link, (Rcalculated) should be larger than the required bit rate
(Rrequired). If the resulting or calculated bit rate (Rcalculated) is lower than the
required bit rate (Rrequired), then the downlink is the limiting link
3.10 Downlink Limited Link Budget
If the resulting or calculated bit rate (Rcalculated) is lower than the
required bit rate (Rrequired), then the downlink is the limiting link. In that
case, the true maximum cell range must be determined by back tracking
the downlink link budget calculations.
The downlink link budget calculations are performed according to
the following steps:
(1) R PRB, required is transformed into a required SINR .
(2)The required SINR is used to derive user equipment (UE) sensitivity
(SUE) at the cell edge.
(3)The user equipment (UE) sensitivity (SUE) is used in the link budget,
initially with the same noise rise BIDL as before.
3.10.1 User equipment (UE) receiver sensitivity
The user equipment sensitivity SUE is given by:
Chapter 3: Coverage dimensioning
3 - 35
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
3.9.9 Concluding link budget according to required and calculated
bit rate
The resulting or calculated bit rate is multiplied by the number of
physical resource blocks (PRB) (nPRB) to obtain the maximum calculated
bit rate (Rcalculated) expected on the cell edge. If the uplink is really the
limiting link, (Rcalculated) should be larger than the required bit rate
(Rrequired). If the resulting or calculated bit rate (Rcalculated) is lower than the
required bit rate (Rrequired), then the downlink is the limiting link
3.10 Downlink Limited Link Budget
If the resulting or calculated bit rate (Rcalculated) is lower than the
required bit rate (Rrequired), then the downlink is the limiting link. In that
case, the true maximum cell range must be determined by back tracking
the downlink link budget calculations.
The downlink link budget calculations are performed according to
the following steps:
(1) R PRB, required is transformed into a required SINR .
(2)The required SINR is used to derive user equipment (UE) sensitivity
(SUE) at the cell edge.
(3)The user equipment (UE) sensitivity (SUE) is used in the link budget,
initially with the same noise rise BIDL as before.
3.10.1 User equipment (UE) receiver sensitivity
The user equipment sensitivity SUE is given by:
Chapter 3: Coverage dimensioning
3 - 35
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
3.9.9 Concluding link budget according to required and calculated
bit rate
The resulting or calculated bit rate is multiplied by the number of
physical resource blocks (PRB) (nPRB) to obtain the maximum calculated
bit rate (Rcalculated) expected on the cell edge. If the uplink is really the
limiting link, (Rcalculated) should be larger than the required bit rate
(Rrequired). If the resulting or calculated bit rate (Rcalculated) is lower than the
required bit rate (Rrequired), then the downlink is the limiting link
3.10 Downlink Limited Link Budget
If the resulting or calculated bit rate (Rcalculated) is lower than the
required bit rate (Rrequired), then the downlink is the limiting link. In that
case, the true maximum cell range must be determined by back tracking
the downlink link budget calculations.
The downlink link budget calculations are performed according to
the following steps:
(1) R PRB, required is transformed into a required SINR .
(2)The required SINR is used to derive user equipment (UE) sensitivity
(SUE) at the cell edge.
(3)The user equipment (UE) sensitivity (SUE) is used in the link budget,
initially with the same noise rise BIDL as before.
3.10.1 User equipment (UE) receiver sensitivity
The user equipment sensitivity SUE is given by:
Chapter 3: Coverage dimensioning
3 - 36
Equation (3-17) represents User equipment (UE) receiver sensitivity
3.11.2 Downlink budget maximum allowable path loss (MAPLDL)
The down link budget maximum allowable path loss (MAPLDL )is
described by the following equation:
Equation (3-18) represents Downlink budget maximum allowable path
loss.
Where:
PRBeNodeBEIRP , is the effective isotropic radiated or transmitter power
per physical resource block at the system reference point [dBm]
UES is the user equipment (UE) sensitivity [dBm]
(4)New signal attenuation for down link is derived with the following
equation:
Equation (3-19) represents signal attenuation for down link.
(5)The new down link signal attenuation L sa,max,DL is applied in to obtain
a new BIDL
(6)Equation in the above is iterated until L sa,max,DL and BIDL are constant.
(7)The new L sa,max,DL converted to MAPLDL is now used to calculate the
true cell range.
MAPLDL is used as a measure of cell size. It is converted to
geographical distance by a suitable wave propagation model.
A down link limited system means that the uplink quality exceeds the
requirement. If the bit rate on the cell edge for the uplink is needed, the
uplink budget calculations also must be back tracked:
Chapter 3: Coverage dimensioning
3 - 36
Equation (3-17) represents User equipment (UE) receiver sensitivity
3.11.2 Downlink budget maximum allowable path loss (MAPLDL)
The down link budget maximum allowable path loss (MAPLDL )is
described by the following equation:
Equation (3-18) represents Downlink budget maximum allowable path
loss.
Where:
PRBeNodeBEIRP , is the effective isotropic radiated or transmitter power
per physical resource block at the system reference point [dBm]
UES is the user equipment (UE) sensitivity [dBm]
(4)New signal attenuation for down link is derived with the following
equation:
Equation (3-19) represents signal attenuation for down link.
(5)The new down link signal attenuation L sa,max,DL is applied in to obtain
a new BIDL
(6)Equation in the above is iterated until L sa,max,DL and BIDL are constant.
(7)The new L sa,max,DL converted to MAPLDL is now used to calculate the
true cell range.
MAPLDL is used as a measure of cell size. It is converted to
geographical distance by a suitable wave propagation model.
A down link limited system means that the uplink quality exceeds the
requirement. If the bit rate on the cell edge for the uplink is needed, the
uplink budget calculations also must be back tracked:
Chapter 3: Coverage dimensioning
3 - 36
Equation (3-17) represents User equipment (UE) receiver sensitivity
3.11.2 Downlink budget maximum allowable path loss (MAPLDL)
The down link budget maximum allowable path loss (MAPLDL )is
described by the following equation:
Equation (3-18) represents Downlink budget maximum allowable path
loss.
Where:
PRBeNodeBEIRP , is the effective isotropic radiated or transmitter power
per physical resource block at the system reference point [dBm]
UES is the user equipment (UE) sensitivity [dBm]
(4)New signal attenuation for down link is derived with the following
equation:
Equation (3-19) represents signal attenuation for down link.
(5)The new down link signal attenuation L sa,max,DL is applied in to obtain
a new BIDL
(6)Equation in the above is iterated until L sa,max,DL and BIDL are constant.
(7)The new L sa,max,DL converted to MAPLDL is now used to calculate the
true cell range.
MAPLDL is used as a measure of cell size. It is converted to
geographical distance by a suitable wave propagation model.
A down link limited system means that the uplink quality exceeds the
requirement. If the bit rate on the cell edge for the uplink is needed, the
uplink budget calculations also must be back tracked:
Chapter 3: Coverage dimensioning
3 - 37
(1)L sa,max,DL from the downlink is applied in to obtain the new down link
MAPLDL and a new uplink noise rise (BIUL) is approximated with the
following expression:
Equation (3-20) represents uplink noise rise.
Where:''PRBn is the number of resource blocks allocated to the service responsible
for the interference. n’’PRB may or may not be equal to n’PRB, the number
of resource blocks allocated to the service for which the link budget is
calculated.
H is the average attenuation factor, depends on the site geometry, antenna
pattern, wave propagation exponent, and eNodeB antenna height. H is the
standard average path loss factor used in coverage and capacity
dimensioning value of 0.36 is recommended for dimensioning.
(2)the equation of the uplink budget maximum allowable path loss
(MAPLUL), is solved for the eNodeB sensitivity eNodeBS , and the downlink
DLsaL max,, is inserted.
(3)the equation of receiver sensitivity is solved for the uplink signal-to-
interference-and- noise ratio (SINR) at the cell edge . is converted to a
logarithmic value.
(4)The corresponding calculated bit rate is calcultedbR , determined.
3.11 propagation models
To make a design and plan of cellular mobile phone systems,
accurate propagation characteristics of the environment should be known
especially the path loss. The calculation of path loss is vital for the
Chapter 3: Coverage dimensioning
3 - 37
(1)L sa,max,DL from the downlink is applied in to obtain the new down link
MAPLDL and a new uplink noise rise (BIUL) is approximated with the
following expression:
Equation (3-20) represents uplink noise rise.
Where:''PRBn is the number of resource blocks allocated to the service responsible
for the interference. n’’PRB may or may not be equal to n’PRB, the number
of resource blocks allocated to the service for which the link budget is
calculated.
H is the average attenuation factor, depends on the site geometry, antenna
pattern, wave propagation exponent, and eNodeB antenna height. H is the
standard average path loss factor used in coverage and capacity
dimensioning value of 0.36 is recommended for dimensioning.
(2)the equation of the uplink budget maximum allowable path loss
(MAPLUL), is solved for the eNodeB sensitivity eNodeBS , and the downlink
DLsaL max,, is inserted.
(3)the equation of receiver sensitivity is solved for the uplink signal-to-
interference-and- noise ratio (SINR) at the cell edge . is converted to a
logarithmic value.
(4)The corresponding calculated bit rate is calcultedbR , determined.
3.11 propagation models
To make a design and plan of cellular mobile phone systems,
accurate propagation characteristics of the environment should be known
especially the path loss. The calculation of path loss is vital for the
Chapter 3: Coverage dimensioning
3 - 37
(1)L sa,max,DL from the downlink is applied in to obtain the new down link
MAPLDL and a new uplink noise rise (BIUL) is approximated with the
following expression:
Equation (3-20) represents uplink noise rise.
Where:''PRBn is the number of resource blocks allocated to the service responsible
for the interference. n’’PRB may or may not be equal to n’PRB, the number
of resource blocks allocated to the service for which the link budget is
calculated.
H is the average attenuation factor, depends on the site geometry, antenna
pattern, wave propagation exponent, and eNodeB antenna height. H is the
standard average path loss factor used in coverage and capacity
dimensioning value of 0.36 is recommended for dimensioning.
(2)the equation of the uplink budget maximum allowable path loss
(MAPLUL), is solved for the eNodeB sensitivity eNodeBS , and the downlink
DLsaL max,, is inserted.
(3)the equation of receiver sensitivity is solved for the uplink signal-to-
interference-and- noise ratio (SINR) at the cell edge . is converted to a
logarithmic value.
(4)The corresponding calculated bit rate is calcultedbR , determined.
3.11 propagation models
To make a design and plan of cellular mobile phone systems,
accurate propagation characteristics of the environment should be known
especially the path loss. The calculation of path loss is vital for the
Chapter 3: Coverage dimensioning
3 - 38
determination of RF cell coverage of eNodeB placement and in
optimizing it. There are many prediction models that are used to predict
path loss. Although these models differ in their methodologies, all have
the distance between the transmitter and receiver as a parameter i.e. the
path loss is heavily dependent on the distance between the transmitter and
receiver. Other effects also come into play in addition to distance. In the
following subsections, the propagation model will be defined and why it
is necessary. The different types of propagation predict models for
terrestrial wireless communication systems will be presented briefly, and
then an example of each type will be discussed in detail. The focus is
placed on the following models: free space model, Cost 231 Okumara
Hata model and Cost 231 Walfisch Ikegami model. The last two models
are the most widely used software package for cellular system design.
Definition of propagation model:
Propagation model is a model used to determine the maximum range
of the communication system which provides acceptable quality provided
that the maximum allowable or permissible or accepted path loss (MAPL)
is determined as accurately as possible via link budget. In cellular mobile
phone system propagation model is used to calculate the maximum
distance between the mobile station (MS) and the eNodeB at which
reliable communication take place with the desired quality of service. and
to determine the locations of cell site (CSs) and the spacing between the
CSs in order to ensure reliable and uninterrupted communications as the
MS moves through the required coverage area. The propagation models
are necessary and essential because the various propagation effects and
time varying, dynamic and difficult to predict. The signal traveling from
the eNodeB to the mobile station follows many different paths before
Chapter 3: Coverage dimensioning
3 - 39
arriving at the receiving antenna of the MS. Each individual path affects
the signal causing attenuation, delay and phase shift. In additional, the
motion of the mobile station (MS) nearby scatters such as trucks and
buses may cause Doppler frequency shifts in each received component.
The received signal at the mobile station (MS) is therefore a result of
direct rays, reflected rays and shadowing or any combinations of these
signals. The path loss can be obtained either by field measurements are
time consuming and expensive while the models are simple and efficient
to use.
3.12Classifications of propagation models
Propagation models can be roughly divided into three types: the
empirical, theoretical and semi-empirical models.
3.12.1Empirical propagation models
Empirical models are usually set of equations, the model parameters
are divided from extensive field measurements data. They are accurate
for environments with the same characteristics as those where
measurements were made. The input parameters for empirical models are
usually qualitative and not very specific e.g. dense urban (DU), urban
(UR), Suburban (SU) and rural (RU) areas and so on. One of the main
drawbacks of empirical models is that they cannot be used for different
environment without modifications. The output parameters are basically
range specific. Empirical models examples are Okumara model and Hata
model.
3.12.2 Theoretical propagation models
They are derived physically assuming some ideal conditions for
example over roof top diffractions model is derived using physical optics
assuming uniform heights and spacing of buildings. Theoretical models
Chapter 3: Coverage dimensioning
3 - 40
examples are Walfisch and Bertoni model, Ikegami model and free space
model.
3.12.3 Semi – empirical propagation models
The parameters of the theoretical models are empirically to fit
measurement data. Semi –empirical models examples are COST 231 –
Walfisch Ikegami model and COST 231 Okumara Hata model.
Free space model
The free space model is physical model because it describes how
signal propagates. The free-space model is based on expanding spherical
wave front as the signal radiates from a point source in space. The
electromagnetic waves in free space diminish as a function of inverse
square of the distance i.e. (1/d^2), where d is the distance between the
transmitter and receiver and in our case the distance between the mobile
station (MS) and eNodeB. It is mostly used in satellite communication
systems where the signal travels through free space.
Assume that the MS antenna and eNodeB antenna are arranged such
that their directions of maximum gain are aligned i.e. the source and load
impedances match the antenna impedances their polarization are matched
and they are separated by a distance.
Okumara model
In 1968, Okumara model is an empirical developed by Yoshihisa
Okumara based upon an extensive series of measurements of the field
strength made in and around Tokyo city by Y. Okumara in VHF and UHF
land mobile radio services at several frequencies in 100 MHz and 3 MHz.
Okumara model is a graphics- based model using numerous of curves.
Okumara model is applied for prediction of maximum allowable path loss
over macro cell, built up areas. It is also successfully applied in other
Chapter 3: Coverage dimensioning
3 - 41
urban environment (outside Japan) taking urbanization factor, terrain type
correction into account. Okumara model was limited from 1 Km to 100
Km distance.
The frequencies range from 1 m to 10 meters. Okumara model’s
drawback is the results are available in graghical form.
Okumara – Hata model
In 1980, Hata model is an empirical formula derived from
Okumara’s results. The measurements graphs results have been fitted to a
mathematical model by M.Hata.
The Okumara graphs have been approximated by Hata in a set of
formulas. The Hata model is a formula- based for Okumara model and
can be used more effectively. Okumara –Hata model is applied for
prediction of maximum allowable path loss over macro cell, buit – up,
quasi smooth areas but the equations were limited from 1 Km to 20 Km
distance. The frequencies range from 150 to 1500 MHz. The mobile
station antenna height should be between 1m to 10meters. The eNodeB
antenna height ranges 30 to 200meters. Okumara –Hata model is easily
computable.
COST 231 Okumara Hata model
The Cost 231 Okumara –Hata propagation model was and still is
widely used for coverage calculation in microcellular network planning.
In 1999, it was found by the European community collaborative studied
in the areas of science and technology (COST) that Okumara Hata model
underestimates path loss. Okumara Hata model for medium to small cities
i.e. urban area has been extended and modified to correct the situation
and to cover the frequency band from 1500 to 2000 MHz in the COST
231 project. Thus, COST 231 Okumara Hata model is considered semi
Chapter 3: Coverage dimensioning
3 - 42
empirical model after adjustment to cover the frequency band of 4G
cellular systems for urban personal communication system (PCS)
applications.
The model include terrain information qualitatively by dividing the
prediction area into a series of clutter and terrain categories namely dense
urban, suburban and rural, open, quasi open… etc environments.
Okumara Hata model with related corrections is the most common model
used in designing real systems. Okumara takes urban area as a reference
and apply correction factors for conversion to the other classifications. In
Okumara Hata model, the path loss is function of several parameters such
as frequency, frequency range, height of MS antenna, height of eNodeB
antenna, and building density. This model has been proven to be accurate
and is used by computer simulation planning tools.
For the parameters, there are only certain ranges in which the model
is valid; that hb should only be between 30m to 200m, hm should be
between 1m to 10m, d should be between 1 Km to 20Km.
3.13 Ericsson variant of COST 231 Okumura–Hata Wave
Propagation model
This section describes the wave propagation characteristics. It is not
expected that a channel wider than 5 MHz will have a significant
difference in the ability to compensate for Rayleigh fading.
The equation to calculate the cell radius R in kilometres is as follows:10R
Equation (3-21) represents cell radius
Where:
Chapter 3: Coverage dimensioning
3 - 43
A is frequency-dependent fixed attenuation value, shown in table
(3.14)
hb is base station or eNodeB antenna height [m]
hm is height of the user equipment (UE) antenna [m]
a (hm) = (1.1 log F- 0.7) hm – (1.56 log F- 0.8)
Equation (3-22) represents a function of user equipment antenna in RU,
UR, and SU
a(hm) is the Mobile station Antenna height correction factor as described
in the Hata Model for Urban Areas.
a(hm)=3.2[log(11.75hm)]2 - 4.97
Equation (3-23) represents a function of user equipment antenna in
DU areas.
Equation (3-24) represents maximum allowable pathloss as a function
of cell radius.
Table (3-13) fixed attenuation A in Ericsson variant COST 231 Okumura-
Hata propagation model
Chapter 3: Coverage dimensioning
3 - 43
A is frequency-dependent fixed attenuation value, shown in table
(3.14)
hb is base station or eNodeB antenna height [m]
hm is height of the user equipment (UE) antenna [m]
a (hm) = (1.1 log F- 0.7) hm – (1.56 log F- 0.8)
Equation (3-22) represents a function of user equipment antenna in RU,
UR, and SU
a(hm) is the Mobile station Antenna height correction factor as described
in the Hata Model for Urban Areas.
a(hm)=3.2[log(11.75hm)]2 - 4.97
Equation (3-23) represents a function of user equipment antenna in
DU areas.
Equation (3-24) represents maximum allowable pathloss as a function
of cell radius.
Table (3-13) fixed attenuation A in Ericsson variant COST 231 Okumura-
Hata propagation model
Chapter 3: Coverage dimensioning
3 - 43
A is frequency-dependent fixed attenuation value, shown in table
(3.14)
hb is base station or eNodeB antenna height [m]
hm is height of the user equipment (UE) antenna [m]
a (hm) = (1.1 log F- 0.7) hm – (1.56 log F- 0.8)
Equation (3-22) represents a function of user equipment antenna in RU,
UR, and SU
a(hm) is the Mobile station Antenna height correction factor as described
in the Hata Model for Urban Areas.
a(hm)=3.2[log(11.75hm)]2 - 4.97
Equation (3-23) represents a function of user equipment antenna in
DU areas.
Equation (3-24) represents maximum allowable pathloss as a function
of cell radius.
Table (3-13) fixed attenuation A in Ericsson variant COST 231 Okumura-
Hata propagation model
Chapter Four
Capacity Dimensioning
Chapter 4: Capacity Dimensioning
4 - 2
Chapter four
Capacity Dimensioning4.1 Introduction
Capacity dimensioning obtains input information to the phases
after radio interface dimensioning: transmission link dimensioning and
eNodeB dimensioning.
The method is specified for a certain system load. The dimensioning
method finds the maximum capacity that the target cell can sustain
momentarily, given the system load in the surrounding cells. It is
improbable that all cells in a system are fully loaded at the same time, as
observed in real networks of different technologies.
The evaluation of capacity needs the following two tasks to be
completed:
Being able to estimate the cell throughput corresponding to the settings
used to derive the cell radius
Analyzing the traffic inputs provided by the operator to derive the traffic
demand, which include the number of subscribers (U), the traffic mix
and data about the geographical spread of subscribers in the
deployment area
The target of capacity planning exercise is to get an estimate of the
site count based on the capacity requirements. Capacity requirements are
set forth by the network operators based on their predicted traffic.
Average cell throughput is needed to calculate the capacity-based site
count.
In LTE, the main indicator of capacity is SINR distribution in the
cell. In this project, for the sake of simplicity, LTE access network is
assumed to be limited in capacity by DL.
Chapter 4: Capacity Dimensioning
4 - 3
The purpose of this chapter is to describe the capacity dimensioning for
the LTE network and to explain the methods used and factors impacting
the capacity dimensioning process. This chapter includes several sections.
The first section describes the cell throughput calculations, while the
second part is about traffic demand estimation. Later sections concern
with capacity based site count evaluation.
Capacity Definition
The number of connections that the wireless channel can support without
unduly degrading the data services carried on the channel.
4.2 Uplink Capacity
4.2.1 IT is based on the following calculations:
Signal-to-Interference-and-Noise Ratio (SINR)
Cell throughput
Number of sites required
4.2.2Signal-to-interference-and-noise ratio
The operating mode with power control assumes perfect power
control (PPC) and infinite power dynamics. User equipment is received at
the signal to interference plus noise ratio (SINR) identical to the bit rate
per physical resource block (PRB) is identical to the bit rate
corresponding to the SINR and the number of allocated physical resource
blocks.
By varying the load QUL , the average user throughput does not change
However, the cell throughput and the cell range will change
The most accurate evaluation of cell capacity (throughput under certain
constraints) is given by running simulations. The best solution to derive
cell throughput is direct mapping of SINR distribution obtained from a
Chapter 4: Capacity Dimensioning
4 - 4
simulator into MCS (thus, bit rate) or directly into throughput using
appropriate link level results.
Capacity dimensioning gives an estimate of the resources needed
for supporting a specified offered traffic with a certain level of QoS (e.g.
throughput or blocking probability). Theoretical capacity of the network
is limited by the number of eNodeB’s installed in the network. Cell
capacity in LTE is impacted by several factors, which includes
interference level, packet scheduler implementation and supported
modulation and coding schemes (MCSs).
The SINR values to support each modulation coding scheme (MCS) are
derived from look-up tables that are generated from link level
simulations. As shown in table (4-1) for urban channel model and a fixed
inter-site distance of 1732m in LTE network.
Table (4-1) SINR values corresponding to each modulation coding
scheme (MCS)
Chapter 4: Capacity Dimensioning
4 - 4
simulator into MCS (thus, bit rate) or directly into throughput using
appropriate link level results.
Capacity dimensioning gives an estimate of the resources needed
for supporting a specified offered traffic with a certain level of QoS (e.g.
throughput or blocking probability). Theoretical capacity of the network
is limited by the number of eNodeB’s installed in the network. Cell
capacity in LTE is impacted by several factors, which includes
interference level, packet scheduler implementation and supported
modulation and coding schemes (MCSs).
The SINR values to support each modulation coding scheme (MCS) are
derived from look-up tables that are generated from link level
simulations. As shown in table (4-1) for urban channel model and a fixed
inter-site distance of 1732m in LTE network.
Table (4-1) SINR values corresponding to each modulation coding
scheme (MCS)
Chapter 4: Capacity Dimensioning
4 - 4
simulator into MCS (thus, bit rate) or directly into throughput using
appropriate link level results.
Capacity dimensioning gives an estimate of the resources needed
for supporting a specified offered traffic with a certain level of QoS (e.g.
throughput or blocking probability). Theoretical capacity of the network
is limited by the number of eNodeB’s installed in the network. Cell
capacity in LTE is impacted by several factors, which includes
interference level, packet scheduler implementation and supported
modulation and coding schemes (MCSs).
The SINR values to support each modulation coding scheme (MCS) are
derived from look-up tables that are generated from link level
simulations. As shown in table (4-1) for urban channel model and a fixed
inter-site distance of 1732m in LTE network.
Table (4-1) SINR values corresponding to each modulation coding
scheme (MCS)
Chapter 4: Capacity Dimensioning
4 - 5
The average signal-to-interference-and-noise ratio (SINR) yields a
bit rate. The result is the bit rate per physical resource block. The average
user bit rate is scaled proportionately with the number of Physical
resource blocks corresponding to the deployed bandwidth.
For the transport formats in LTE, the relationship between bit rate
per resource block (RRB) and Signal-to-Interference-and-Noise Ratio
(SINR), γ, is determined by a set of link simulations.
The uplink simulations include the following:
Antenna configuration: 2-branch RX diversity
Modulation schemes: QPSK, 16-QAM
Channel models: EPA 5 Hz, EVA 70 Hz, ETU 300Hz
The results, including an implementation margin, have been fitted to a
semi-empirical parameterized expression as follows:
Equation (4-1) represents the required bit rate
Where:
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
The semi-empirical parameter a0 represents the maximum obtainable bit
rate in one resource block as shown in table (4-2)
Table (4-2) semi- empirical parameters for up link
Chapter 4: Capacity Dimensioning
4 - 5
The average signal-to-interference-and-noise ratio (SINR) yields a
bit rate. The result is the bit rate per physical resource block. The average
user bit rate is scaled proportionately with the number of Physical
resource blocks corresponding to the deployed bandwidth.
For the transport formats in LTE, the relationship between bit rate
per resource block (RRB) and Signal-to-Interference-and-Noise Ratio
(SINR), γ, is determined by a set of link simulations.
The uplink simulations include the following:
Antenna configuration: 2-branch RX diversity
Modulation schemes: QPSK, 16-QAM
Channel models: EPA 5 Hz, EVA 70 Hz, ETU 300Hz
The results, including an implementation margin, have been fitted to a
semi-empirical parameterized expression as follows:
Equation (4-1) represents the required bit rate
Where:
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
The semi-empirical parameter a0 represents the maximum obtainable bit
rate in one resource block as shown in table (4-2)
Table (4-2) semi- empirical parameters for up link
Chapter 4: Capacity Dimensioning
4 - 5
The average signal-to-interference-and-noise ratio (SINR) yields a
bit rate. The result is the bit rate per physical resource block. The average
user bit rate is scaled proportionately with the number of Physical
resource blocks corresponding to the deployed bandwidth.
For the transport formats in LTE, the relationship between bit rate
per resource block (RRB) and Signal-to-Interference-and-Noise Ratio
(SINR), γ, is determined by a set of link simulations.
The uplink simulations include the following:
Antenna configuration: 2-branch RX diversity
Modulation schemes: QPSK, 16-QAM
Channel models: EPA 5 Hz, EVA 70 Hz, ETU 300Hz
The results, including an implementation margin, have been fitted to a
semi-empirical parameterized expression as follows:
Equation (4-1) represents the required bit rate
Where:
a0, a1,a2 and a3 are fitted parameters and the SINR is expressed in dB.
The semi-empirical parameter a0 represents the maximum obtainable bit
rate in one resource block as shown in table (4-2)
Table (4-2) semi- empirical parameters for up link
Chapter 4: Capacity Dimensioning
4 - 6
In the uplink, one or more resource blocks are always allocated at
each band edge to signalling for users in idle mode on the channel
Physical Uplink Control Channel (PUCCH). For this reason, the number
of physical resource blocks in uplink available for calculating capacity
are always reduced by a number value of 4 is recommended for
dimensioning.
The resulting Uplink average user bit rate per cell is:
Ravg,UL =RRB,UL (nRB - nPUCCH)
Equation (4-2) represents Uplink average user bit rate per cell
Average cell Throughput
The Uplink average cell throughput is by the following equation:
Tcell,UL = QUL Ravg,UL
Equation (4-3) represents the uplink average throughput
Where:
The nRB is different and larger than the number of resource blocks
nRB used for uplink coverage dimensioning
QUL: is the uplink system load
Ravg,UL: Average UP Link data rate
The site throughput:
Where the site capacity is a multiple of the cell throughput, which
depends on the number of cells per site (Not considering any hardware
limitation) According to cell type.
If omni cell then the site throughput is given by:
Tsite = Tcell Equation (4-4)
If 3 sector cell, then the site throughput is given by:
Tsite = 3 × Tcell Equation (4-5)
Chapter 4: Capacity Dimensioning
4 - 7
The total throughput or the overall data rate
To determine the traffic demand estimation, the total throughput
or the overall data rate is given by:
Ttotal = U × TU
Equation (4-6) represents the total throughput or the overall data
rate
Where:
U is the number of users in the network
TU is the throughput per user or peak data rate
The number of sites required
Nsite =
Equation (4-7) represents the number of sites required
4.3 Downlink Capacity
The following downlink capacity calculations are performed:
Signal-to-Interference-and-Noise Ratio (SINR)
Cell throughput
The number of sites required.
4.3.1 The maximum signal attenuation Lsa max at the cell border
The maximum allowable path loss from the uplink is used to find the
maximum sustainable bit rate per physical resource block in the
downlink. Lsa max is given by:
Lsa,Max = MAPL + BLNF – (Gue + Gothers) + LPBL + LCPL+ Lf + Lc
Equation (4-8) represents The maximum signal attenuation Lsa max
at the cell border
Chapter 4: Capacity Dimensioning
4 - 8
Where:
MAPLUL is the uplink budget maximum allowable path loss
(MAPL) from coverage calculation.
BLNF : log-normal fading margin
GUE : User equipment transmitting antenna gain [dBi]
Gothers : It is gains due to MIMO
LBPL : Building penetration loss
LCPL : Car penetration loss
LF : Feeder loss
LC : Connector loss
4.3.2 Thermal noise power density per physical resource block in
downlink
N PRB,DL = Nt + Nf + 10 Log (WPRB)
Equation (4-9) represents Thermal noise power density per physical
resource block in downlink.
Where:
Nt: It is thermal noise power density = 10 log10 KT and is equal
-174 dBm/Hz
Nf : noise figure of receiver = 7 d B
W(PRB) : bandwidth per physical resource block = 180 KHz
NPRB,DL : Down Link thermal noise per physical resource block
K : Boltzmann's constant and its value is 1.38* 10-23
T : Temperature and its value is 290 degree Kelvin
Chapter 4: Capacity Dimensioning
4 - 9
4.3.3 The eNodeB transmitted power per physical resource block
Equation (4-10) represents The eNodeB transmitted power per physical
resource block
Where:
Ptx ,eNodeB, PRB is the eNode B transmitted power per physical
resource block at the system reference point
P (norm) : is the sum of normal power from all radio units in the cell
at the reference point
The average down link noise rise or interference margins is
Equation (4-11) represents the average down link noise rise or
interference margins
Where:
• BIDL : Interference margin (IM)
• Ptx,eNodeB,PRB : is the eNodeB transmitted or radiated power per
physical resource block.
• QDL is the average downlink system load.
• Fc is interference factor.
• N PRB,DL :Noise thermal power density, down link , per PRB.
Chapter 4: Capacity Dimensioning
4 - 9
4.3.3 The eNodeB transmitted power per physical resource block
Equation (4-10) represents The eNodeB transmitted power per physical
resource block
Where:
Ptx ,eNodeB, PRB is the eNode B transmitted power per physical
resource block at the system reference point
P (norm) : is the sum of normal power from all radio units in the cell
at the reference point
The average down link noise rise or interference margins is
Equation (4-11) represents the average down link noise rise or
interference margins
Where:
• BIDL : Interference margin (IM)
• Ptx,eNodeB,PRB : is the eNodeB transmitted or radiated power per
physical resource block.
• QDL is the average downlink system load.
• Fc is interference factor.
• N PRB,DL :Noise thermal power density, down link , per PRB.
Chapter 4: Capacity Dimensioning
4 - 9
4.3.3 The eNodeB transmitted power per physical resource block
Equation (4-10) represents The eNodeB transmitted power per physical
resource block
Where:
Ptx ,eNodeB, PRB is the eNode B transmitted power per physical
resource block at the system reference point
P (norm) : is the sum of normal power from all radio units in the cell
at the reference point
The average down link noise rise or interference margins is
Equation (4-11) represents the average down link noise rise or
interference margins
Where:
• BIDL : Interference margin (IM)
• Ptx,eNodeB,PRB : is the eNodeB transmitted or radiated power per
physical resource block.
• QDL is the average downlink system load.
• Fc is interference factor.
• N PRB,DL :Noise thermal power density, down link , per PRB.
Chapter 4: Capacity Dimensioning
4 - 10
• nPRB is number of physical resource block.
• F is the cell plan quality factor. It describes the ratio of received
power from all other cells to that received from own cell at a
location near the cell edge locations.
• B(IDL) : Down Link interference Margin
4.3.4 Signal-to-Interference-and-Noise Ratio
The downlink capacity is based on the Signal-to-Interference-and-
Noise Ratio (SINR) at the average location within a cell, denoted as a
linear ratio.
The average SINR is expressed in the average noise rise. This is
similar to the interference margin, but the SINR is evaluated at an
average location instead of at the cell edge.
The resulting average downlink signal-to-interference-and-noise
ratio (SINR), is given by the following equation:
Equation (4-12) represents Signal-to-Interference-and-Noise Ratio
in downlink
Where:
• H is the average attenuation factor dependent on site geometry,
antenna pattern, wave propagation exponent,and base station
antenna height.
• H is the standard average path loss factor used in coverage and
capacity dimensioning And for dimensioning H is value of 0.36
Chapter 4: Capacity Dimensioning
4 - 10
• nPRB is number of physical resource block.
• F is the cell plan quality factor. It describes the ratio of received
power from all other cells to that received from own cell at a
location near the cell edge locations.
• B(IDL) : Down Link interference Margin
4.3.4 Signal-to-Interference-and-Noise Ratio
The downlink capacity is based on the Signal-to-Interference-and-
Noise Ratio (SINR) at the average location within a cell, denoted as a
linear ratio.
The average SINR is expressed in the average noise rise. This is
similar to the interference margin, but the SINR is evaluated at an
average location instead of at the cell edge.
The resulting average downlink signal-to-interference-and-noise
ratio (SINR), is given by the following equation:
Equation (4-12) represents Signal-to-Interference-and-Noise Ratio
in downlink
Where:
• H is the average attenuation factor dependent on site geometry,
antenna pattern, wave propagation exponent,and base station
antenna height.
• H is the standard average path loss factor used in coverage and
capacity dimensioning And for dimensioning H is value of 0.36
Chapter 4: Capacity Dimensioning
4 - 10
• nPRB is number of physical resource block.
• F is the cell plan quality factor. It describes the ratio of received
power from all other cells to that received from own cell at a
location near the cell edge locations.
• B(IDL) : Down Link interference Margin
4.3.4 Signal-to-Interference-and-Noise Ratio
The downlink capacity is based on the Signal-to-Interference-and-
Noise Ratio (SINR) at the average location within a cell, denoted as a
linear ratio.
The average SINR is expressed in the average noise rise. This is
similar to the interference margin, but the SINR is evaluated at an
average location instead of at the cell edge.
The resulting average downlink signal-to-interference-and-noise
ratio (SINR), is given by the following equation:
Equation (4-12) represents Signal-to-Interference-and-Noise Ratio
in downlink
Where:
• H is the average attenuation factor dependent on site geometry,
antenna pattern, wave propagation exponent,and base station
antenna height.
• H is the standard average path loss factor used in coverage and
capacity dimensioning And for dimensioning H is value of 0.36
Chapter 4: Capacity Dimensioning
4 - 11
• The down link bit rate per physical resource block
• The average signal-to-interference-and-noise ratio (converted to
logarithmic)
• yields an average bit rate by way of and is the bit rate per physical
resource block,
• The bit rate per physical resource block, down link RPRB,DL Given
SINR
Equation (4-13) represents the down link bit rate per physical
resource block
For the downlink, the semi-empirical parameters are given in table (4-3)
Table (4-3) Semi- empirical parameters for downlink
4.3.5The down link cell throughput
The average down link user bit rate per cell is scaled
proportionately with the number of physical resource blocks and is given
by:
Ravg,DL = RRB,DL (nRB,DL- nPDCCH)
Chapter 4: Capacity Dimensioning
4 - 11
• The down link bit rate per physical resource block
• The average signal-to-interference-and-noise ratio (converted to
logarithmic)
• yields an average bit rate by way of and is the bit rate per physical
resource block,
• The bit rate per physical resource block, down link RPRB,DL Given
SINR
Equation (4-13) represents the down link bit rate per physical
resource block
For the downlink, the semi-empirical parameters are given in table (4-3)
Table (4-3) Semi- empirical parameters for downlink
4.3.5The down link cell throughput
The average down link user bit rate per cell is scaled
proportionately with the number of physical resource blocks and is given
by:
Ravg,DL = RRB,DL (nRB,DL- nPDCCH)
Chapter 4: Capacity Dimensioning
4 - 11
• The down link bit rate per physical resource block
• The average signal-to-interference-and-noise ratio (converted to
logarithmic)
• yields an average bit rate by way of and is the bit rate per physical
resource block,
• The bit rate per physical resource block, down link RPRB,DL Given
SINR
Equation (4-13) represents the down link bit rate per physical
resource block
For the downlink, the semi-empirical parameters are given in table (4-3)
Table (4-3) Semi- empirical parameters for downlink
4.3.5The down link cell throughput
The average down link user bit rate per cell is scaled
proportionately with the number of physical resource blocks and is given
by:
Ravg,DL = RRB,DL (nRB,DL- nPDCCH)
Chapter 4: Capacity Dimensioning
4 - 12
Equation (4-14) represents the down link cell throughput
4.3.6 The down link cell throughput is given by:
Tcell,DL = QDl × Ravg,DL
Equation (4-15) represents the down link cell throughput
Where:
• Raverage,DL is average DL data rate
• R PRB,DL is DL data rate per physical resource block.
• n'PRB is the number of physical resource block
• nPDCCH is the number of Physical DL control channels
• QDL is the average down link system load
4.3.7 The total throughput
Ttotal = U × TU Equation (4-16)
Where:
Ttotal: The total throughput
Tsite: The site throughput
4.3.8 The site throughput
Tsite = Tcell (Omni cell ) Equation (4-17)
Tsite = 3 × Tcell ( 3 sector cell ) Equation (4-18)
Where:
Tcell,DL is the DL cell throughput
The number of sites required
Nsite = Equation (4-19)
Nsite: Number of sites required
Chapter 4: Capacity Dimensioning
4 - 13
4.4 Application or service distribution model
A key element in network planning is to estimate the number of users
that each BS may support. To have an idea about the maximum number
of subscribers that a typical BS can serve the information of possible
different traffic types and their parameters are essential. But On the other
hand, mixed application packet data networks are notoriously difficult to
treat with statistical methods for the general case. The traffic engineering
for how the bandwidth is apportioned to the various active connections is
typically left to operator configuration and is not included in the standard.
In this project, different application classes are introduced and the desired
parameters and usage percentage related to each of the applications are
specified. There are five major classes’ services or applications as shown
in table (1) that are:
Multiplayer interactive gaming
VoIP and Video Conference
Streaming Media
Web browsing and instant messeging
Media Content Downloading
To fulfil the required QoS specifications of each application a number of
important parameters must be met. These parameters are: bit error rate,
jitter, latency and minimum throughput. The list above is sorted in a
decreasing delay sensitivity order. The latency sensitivity gives an
allocation priority to the suffering application.
According to the service types, the first application group can be
classified in the VBR services. Since the goal of this project is to decide
the maximum capacity of a typical base station, will we focus on the
Chapter 4: Capacity Dimensioning
4 - 14
minimum reserved data rate of each VBR service and leave the maximum
sustained data rate for more advanced scheduling procedures.
The first application class i.e. Multiplayer Interactive Gaming needs a
minimum reserved data rate of 50 kbps for each user.
The second class belongs to the CBR service type with the average
reserved data rate of 32 kbps for each user.
The Streaming Media application group can be classified into VBR
services with reserved data rate of 64 kbps.
The last two application classes can be considered as best effort (BE)
service type. The web browsing application group can be assigned the
nominal data-rate of the user while the file transfer protocol (FTP) class is
supported with the remaining capacity assigned to each Subscriber that is
available after satisfying other guaranteed service types.
Table (4.5) applications or services distribution model
However, the other important factor for capacity estimation of a typical
base station is the user demands and the trend of each user type. In the
Chapter 4: Capacity Dimensioning
4 - 15
coming sections an application distribution scenario and two important
scales to follow the market trends are presented.
4.4.1 Service Flows
In the previous sections, we have examined the various factors that
influence the overall channel bandwidth. What remains after accounting
for the per-channel and per-packet overhead is the usable channel
bandwidth. This channel size is the relevant quantity for determining the
service capacity consistent with the QoS parameters. The traffic
engineering for how the bandwidth is apportioned to the various active
connections is typically left to operator configuration.
In this section we will illustrate one way in which this could be
accomplished. We begin by reviewing the three basic service types.
In general service flows related to each application can be identified
with two major traffic rate allocation types:
(i)The Reserved Traffic Rate
It is the committed information rate for the flow of the data rate that
is unconditionally dedicated to the flow and therefore can be directly
subtracted from the available user channel size to determine the
remaining capacity.
(ii)The Sustained Traffic rate
It is the peak information rate that the system will permit. Traffic,
submitted by a subscriber station at rates bounded by the minimum and
maximum rates, is dealt with by the base station on a non-guaranteed
basis.
Chapter 4: Capacity Dimensioning
4 - 16
Based on the above traffic rate allocation methods three service
flows can be defined. These services are as follows:
4.4.2 Constant Bit Rate (CBR) Services
System can support Constant Bit Rate (CBR) by configuring
dedicated frequency-time channel grants to specific traffic flows. The
dedicated resources correspond to a constant throughput rate. CBR
service flows are suitable for applications with strict latency and
throughput constraints and that generate a steady stream of fixed size
packets such as VoIP. These service flows can be dynamically set up or
torn down in response to detection by the system of changing traffic
needs.
On the downlink, the base station directly controls the scheduling of
traffic and allocation of the frequency-time channel resources. Dedicating
a portion of the channel bandwidth for CBR flows is therefore a matter of
keeping track of the allocated resources and transporting any available
packets from appropriately classified traffic.
For the uplink the Unsolicited Grant Service (UGS) scheduling
method is used. The base station dedicates a portion of the uplink channel
bandwidth to a Subscriber Station corresponding to one or more service
flows for the duration of the flow. The base station communicates this
assignment to the Subscriber Station in the uplink channel usage maps
that are periodically broadcast out to all stations.
From a capacity standpoint, the key CBR QoS parameter is the
unvarying Maximum Sustained Traffic Rate, which is the committed
information rate for the flow. The maximum rate is unconditionally
dedicated to the flow and therefore can be directly subtracted from the
Chapter 4: Capacity Dimensioning
4 - 17
available user channel size to determine the remaining capacity. The only
overhead associated with CBR flows is the UGS grant overhead, which
increases the size of the uplink channel usage map.
Although the bandwidth is dedicated for a CBR service flow, the
base station scheduler implementation could still elect to temporarily
“borrow” the dedicated bandwidth on the downlink frame if there is no
CBR traffic to send. The scheduler must however issue uplink grants
according to the CBR service flow configuration whether or not the
subscriber station has any traffic to send (the scheduler has no way of
knowing in advance).
CBR service has a maximum reserved traffic rate. This service is
suitable for applications with strict latency and throughput constraints and
those that generate a steady stream of fixed size packets such as VoIP.
4.4.3 Variable Bit Rate (VBR) Services
For applications that have variable traffic throughput demands
systems support Variable Bit Rate (VBR) services. VBR service flows
are suitable for applications that generate fluctuating traffic loads
including compressed streaming video and VoIP with silence
suppression.
On the down link (DL), the base station directly controls the
scheduling of traffic and allocation of the frequency-time channel
resources. Dedicating a portion of the channel bandwidth is therefore a
matter of keeping track of the allocated resources and transporting any
available packets from appropriately classified traffic. The base station
Chapter 4: Capacity Dimensioning
4 - 18
performs this scheduling successively for each TDMA frame that is sent
out for example every 10 ms so that the time varying nature of the VBR
traffic can be supported in real time.
For the uplink (UL), there are several scheduling methods depending
on the QoS requirements for the service flow. For flows with strict real
time access constraints, periodic polling assures that the subscriber station
will have guaranteed channel access up to a specified Minimum Reserved
Traffic Rate. Real time Polling Service (rtPS) operates by having the
base station poll individual subscriber stations periodically for example
every frame to solicit bandwidth requests. Extended real time Polling
Service (ertPS) operates more like UGS except that the committed
maximum rate can be changed on the fly as controlled by subscriber
station signalling.
For flows with looser real time access constraints, non real time
Polling Service (nrtPS) operates like rtPS except the polls can be
directed at individual or groups of subscriber stations, and the latency of
the base station response to bandwidth requests is not guaranteed. The
subscriber stations can also use piggyback methods to request continuing
channel access.
Chapter 4: Capacity Dimensioning
4 - 19
Table (4.6) mobile service flows and QoS parameters
For capacity calculations, the two key VBR QoS parameters are the
Minimum Reserved Traffic Rate and the Maximum Sustained Traffic
Rate. For VBR, the minimum rate corresponds to the committed
information rate. Since the minimum rate is guaranteed, it can be directly
subtracted from the available user channel size to determine the
remaining capacity. The maximum rate is the peak information rate that
the system will permit. Traffic, submitted by a subscriber station at rates
bounded by the minimum and maximum rates, is dealt with by the base
station on a non-guaranteed basis. The overhead associated with VBR
service comes from the polling method except for ertPS, which basically
has the same overhead as UGS i.e. the size of the uplink channel usage
maps is increased for each active flow.
Chapter 4: Capacity Dimensioning
4 - 20
If the polls are directed at a group of subscriber stations the responses
must use a contention bandwidth request interval to respond since request
collisions can occur.
Although the bandwidth is dedicated for the Minimum Reserved
portion of the VBR service flow, the base station scheduler
implementation could still elect to temporarily “borrow” the dedicated
bandwidth on the downlink frame if there is no traffic to send. The
scheduler must however issue uplink grants for bandwidth requests
according to the VBR service flow configuration for the Minimum
Reserved QoS parameter whether or not the subscriber station has any
traffic to send (the scheduler has no way of knowing in advance).
VBR has a minimum reserved and a maximum sustained traffic
rates. These types of service flows are suitable for applications that
generate fluctuating traffic loads including compressed streaming video.
4.4.4 Best Effort (BE) Services
Best effort (BE) services are intended for service flows with the
loosest QoS requirements in terms of channel access latency and without
guaranteed bandwidth. Best effort services are appropriate for
applications such as web browsing and file transfers that can tolerate
intermittent interruptions and reduced throughput without serious
consequence.
On the downlink, the base station directly controls the scheduling of
traffic and allocation of the frequency-time channel resources. For best
effort services, the affected traffic is sent as surplus capacity that is
available after satisfying other guaranteed service types.
Chapter 4: Capacity Dimensioning
4 - 21
On the uplink, the base station should provide periodic contention
intervals in order for subscriber stations with best effort flows to submit
their bandwidth requests. The subscriber stations can also use piggyback
methods to request continuing channel access.
The overhead associated with best effort services comes from
providing the contention intervals for bandwidth requests.
BE are intended for service flows with the loosest QoS requirements
in terms of channel access latency and without guaranteed bandwidth.
Best effort services are appropriate for applications such as web browsing
and file transfers that can tolerate intermittent interruptions and reduced
throughput without serious consequence. For best effort services, the
affected traffic is sent as surplus capacity that is available after satisfying
other guaranteed service types.
Figure (1) shows a schematic the available bandwidth that is
partitioned
Based on the presented bandwidth partitioning methodology, each of
the desired applications can be assigned with the desired service flow
based on its required quality of service (QoS) parameters. As mentioned
before the realization procedure of this task is not included in the standard
and each vendor must implement it utilizing appropriate traffic
scheduling processes for time and frequency channel recourse allocations.
The scheduling is directly controlled by each Base Station.
Chapter 4: Capacity Dimensioning
4 - 22
4.4.5 Sharing Non-Guaranteed Bandwidth
In comparing best effort services against variable bit rate services an
ambiguity becomes apparent. The system must by definition not admit
more guaranteed bandwidth traffic onto the channel than it can supply.
On the other hand, VBR and BE services can both have non-guaranteed
traffic. For VBR it is the portion of traffic submitted at rates above the
Minimum Reserved rate. For BE it is all of the submitted traffic. How
should the scheduler deal with this situation in cases where there is
insufficient remaining capacity to honor all requests? Shown graphically
in figure (1), what should happen if regions C and D overlap? The answer
is not specified by the 802.16 standard but is left to vendor
implementation.
Figure (4.1) channel bandwidth partitioning
Note that the figure illustrates the case where the scheduler actually has
traffic to fill the guaranteed portion of the channel. If that were not the
case then in theory the scheduler can temporarily borrow the guaranteed
Chapter 4: Capacity Dimensioning
4 - 23
bandwidth to satisfy non-guaranteed bandwidth requests. For capacity
estimations we need to assume the worst case where the guaranteed
bandwidth is in use.
This should not come as a surprise; the base station scheduler design
is similarly not described by the standard. The authors of the standard
were trying to balance the conflicting requirements of creating a standard
while allowing freedom where possible for product differentiation and
innovation.
One simple way to deal with the issue might be to implement a
policy of fair-sharing the non-guaranteed bandwidth between VBR and
BE. That is, equally divide any remaining bandwidth up between all
requesting VBR and BE service flows. The problem with this approach is
that is does not allow service providers much control to differentiate their
services. The other problem is that, while VBR can specify a minimum
information rate, BE services under severe congestion can be starved with
throughput rates approaching zero. A better solution is to provide a
method for prioritizing access to non-guaranteed bandwidth, which can
be done by introducing the concept of service flow over-subscription.
4.4.6 Quality of service (QoS) Control modeling
Dimensioning a network needs to keep in mind the user traffic
demand and the applications it uses so that the density of Base Stations
and backbone network dimensioning can fulfill the demand. Another
important task in service provision is to support the QoS parameters of
each connection over the demanded bandwidth. In our current algorithm
we benefit two Over Subscription Ratio (OSR) and Contention Ratio
Chapter 4: Capacity Dimensioning
4 - 24
(CR) measures in order to apply quality of service (QoS) control over the
expected traffic that will be explained in this section.
4.4.7 Contention Ratio (CR)
As the customer base is growing, there must be a measure of the
simultaneity of users requesting bit rate from the Base Stations because
most users won’t demand data at the same time. In simplest terms it
means that, the absolute peak demand on shared resources rarely occurs.
This user simultaneity is defined by a parameter we call contention ratio.
On the other hand, many of the connected subscribers will demand
data whose packets can be delivered assuming some latency or jitter i.e.
less priority.
The available channel bandwidth can be allocated to the users in a
guaranteed and non-guaranteed moods based on the applications.
Generally, applying a contention ratio (CR) for the guaranteed bandwidth
is a practice that operators should approach with caution since their
customers naturally expect that their service agreements will be honored
always. In our algorithm, no Contention Ratio is applied over the
guaranteed partition of the channel bandwidth. However, in future
developments assigning a CR over reserved bandwidths that correspond
to the error or blocking probability of each application will result in a
more accurate traffic modelling. According to the algorithm proceeded in
this thesis, two contention ratios are defined for the non-guaranteed
partition of the bandwidth. Typical values for contention ratios can be
about 30 for residential users (less priority) up to 10 for business users
(higher priority and throughput).In this case, if a Residential Class and a
Business Class Subscribers have contracted a downlink BE service of the
Chapter 4: Capacity Dimensioning
4 - 25
rates 512 kbps and 1Mbps respectively, 512/30=17 kbps and
1000/10=100 kbps are the actual data-rates that must be considered in the
system total capacity calculations. This is while the data rate of the
services with guaranteed bandwidth (CBR,VBRMR) will remain
untouched. Figure (2) illustrates the distribution of two different service
classes traffic model.
4.4.8 Over Subscription Ratio (OSR)
Over-subscription ratio, sometimes called over-booking ratio, in
simplest terms means taking advantage of the fact that, for many systems,
absolute peak demand on shared resources rarely occur. Examples are
everywhere in daily life. Air lines aggressively over-subscribe their seat
capacity. Public telephone networks over-subscribe their network
switching capacity. The point of over-subscription is that system capacity
requirements can be significantly reduced if the requirement to handle
absolute worst-case scenarios is ignored. However, over-subscription
comes at a price that is related to trading hard guarantees of service for
soft statistical guarantees. Depending on the nature of shared resource
usage i.e. the traffic, and how aggressively the resource is over-
subscribed, there can be exceptional periods where there is more demand
than can be served.
The standard also includes the ability to specify a traffic priority
QoS parameter for VBR and BE service flows. This allows basic
grouping of priority between sets of service flows. However, it does not
distinguish between guaranteed and non-guaranteed VBR traffic or allow
division of priority beyond eight basic levels.
Chapter 4: Capacity Dimensioning
4 - 26
How mathematically rigorous the statistics of the guarantees are
usually depends on how much is known about the offered traffic. One
well-known example is the blocking probability associated with
traditional voice Erlang statistics. On the other hand, mixed application
packet data networks are notoriously difficult to treat with statistical
methods for the general case. Often this results in resorting to empirical
rules derived from traffic measurements of a given user population.
In the case of mobile networks, operators can choose to over-
subscribe the total network capacity in order to improve overall network
utilization and cost per line business economics. There are two basic
scenarios. An operator can choose to over-subscribe one or more service
flow’s ‘guaranteed’ bandwidth, or they might choose to over-subscribe
their non-guaranteed bandwidth.
Generally over-subscription of guaranteed bandwidth is a practice
that operators approach with caution since their customers naturally
expect that their service agreements will be honored always. But the fine
print of these agreements may also allow for hopefully rare periods when
the network will not be able to support the guaranteed performance. One
simple example could be that voice over internet protocol (VoIP) users
are guaranteed that less than 1% of their call attempts will be blocked.
This can be accomplished by using Erlang statistics to reserve an over-
subscribed block of bandwidth sufficient to support a given number of
voice lines.
Over-subscription of non-guaranteed bandwidth is of course fair
game but an operator must still balance their users’ service level
expectations against the degree of over-subscription of the network
Chapter 4: Capacity Dimensioning
4 - 27
capacity. If users are told that they can expect “up to” some peak level of
service but discover that during busy hours that they can only get one
tenth of that service they will likely be dissatisfied with their service.
Often this is handled by marketing a “typical” level of service associated
with a given level of over-subscription (related to the total number of
users) and an “up to” service rate limit.
Returning to the issue of shared non-guaranteed bandwidth between
VBR and BE service flows, one solution for prioritizing the access would
be to associate a level of over-subscription to each service flow. For VBR
flows there are two relevant independent levels of over-subscription, one
for the guaranteed Minimum Reserved portion, and a second for the non-
guaranteed portion corresponding to rates bounded by the Minimum
Reserved and the Maximum Sustained limits.
For BE flows there is just one level of over-subscription associated
with the Maximum Sustained limit. If the system allows the service flows
to be configured in this manner then the relative priority ranking of the
non-guaranteed portions of the VBR and BE service flows can be
accomplished. This in turn allows operators to calculate the total number
of lines of service that can be provisioned for a given service scenario.
The problem of allocating the aggregate system capacity to the
various service flows must take into account the QoS requirements of
those flows. Dedicated or guaranteed bandwidth must be dealt with first
and what remains is shared by non-guaranteed services.
OSR is the ratio of the total subscriber’s demand over the reference
capacity of the base station when taking into account the adaptive
Chapter 4: Capacity Dimensioning
4 - 28
modulation. The reference capacity of the base station corresponds to the
available bit rate of the lowest modulation scheme served with that BS.
Subscriber classes distribution model
Consider the two subscriber classes i.e. business and residential.
Assume that the residential class occupies 58% of the users under cover
of our base station while the business class users are confined to 42%. As
shown in table (4.3).
Subscriber class Percentage or weight%
Business subscriber class (B) 58%
Residential subscriber class (R) 42%
Table (4.7) subscriber class distribution model
The total subscriber’s demand capacity refers to the repartition of the
subscribers based on their type of service. In this case the total capacity
for OSR calculation would be:
Ctot=N× (PR×BWR+ PR×BWB) Equation (4-20)
Ctot = N × (58% x 512 + 42% x 1000)
OSR = Ctot /Cref Equation (4-21)
Where
N refers to the number of users that are connected to the base
station (BS).
OSR is a measure of QoS in cell planning. A fair trade off
between OSR and CRs of traffic model will provide us with a
good measure of QoS control. This is because of the fact that the
Chapter 4: Capacity Dimensioning
4 - 29
CRs help us to have a realistic model of the in use traffic based on
the modulation distribution of the subscribers within the coverage
area, while the OSR gives us an idea about the traffic demand that
the operator has committed.
4.4.9 Application or service Distribution and Market Trends
Therefore, studying the traffic demand of existing service providers
can give us an idea about the subscribers’ possible application
distribution while using metropolitan broadband wireless services.
As can be seen, the most significant usage belongs to HTTP web
browsing applications. While the total percentage of the point to point
(p2p) services is almost 60% of all traffic, due to applying bandwidth
limitation over point to point (p2p) in October it drops to 14%. Streaming
traffic increased from 1.24% 12.5% mainly because of submission of
mobile TV.
These values are used to model our application distribution. Table
(4.3) summarizes this model which is the final distribution that will be
taken in to consideration in our capacity calculation algorithm.
Figure (4-2) subscriber class deployment model
Chapter 4: Capacity Dimensioning
4 - 30
4.4.10 Subscribers’ traffic demand
Now that all application distribution parameters are completely
defined, the minimum bandwidth of the demanding traffic can be
calculated. The phrase minimum demand here signifies that we are only
relying on the minimum reserved data-rate required for the applications
including guaranteed bandwidth.
Subscriber class
Business subscriber class (BWB) 1Mbps
Residential subscriber class (BWR) 512 Kbps
Table (4.8) subscriber class traffic model
This fact enables us to derive the maximum supportable capacity of
a generic sector. In our algorithm, the traffic demand is categorized into 2
subscriber classes. Adding more classes is an easy task and won’t change
The relations below conduct traffic demand calculation path for
residential and business class subscribers and the Total Traffic Demand
for DL.
DRresrved=P1×DR1+P2×DR2+P3×DR3 Equation (4-22)
DRreserved = 25% x 50 + 10% x 32 + 12.5% x 64
DRshared-R=P4×DR4+P5 × (BWR-(DR1+DR2+DR3) Equation (4-23)
DRshared-R = 32.5% x BWR + 20% x (BWR - (50+32+64)
DRshared-B=P4×DR4+P5 × (BWB-(DR1+DR2+DR3) Equation (4-24)
DRshared-B = 32.5% x BWB + 20% x (BWB - (50+32+64))
Traffic R = N x (%PR) x (DRreserved + (DRshared-R / CR R) Equation (4-25)
Chapter 4: Capacity Dimensioning
4 - 31
Traffic B = N x (%PB) x (DRreserved + (DRshared-B / CR B) Equation (4-26)
Traffic Total = Traffic R + Traffic B
The parameters are as follow:
DRreserved: Minimum Reserved (Guaranteed) Data-rate for CBR/VBR
Applications
DRshared-R : Shared Data-rate for Residential Class users with BE
Applications
DRshared-B: Shared Data-rate for Business Class users with BE
Applications
BWR: Residential class subscribers data-rate based on user agreement
BWB : Business class Subscribers data-rate based on user agreement
N: Total number of the users connected to the sector
%PR: Percentage of the residential class subscribers within the area
under study
CR R: Contention Ratio for residential class subscribers
%PB: Percentage of the business class subscribers within the area under
study
CRB: Contention Ratio for business class subscribers
Chapter FiveNumerical Results
Chapter 5: Numerical Results
5 - 2
Chapter FiveNumerical Results
Flow chart of Project Work
Start
Preliminary study about LTE
Problem specific study andReview of the related works
Theoretical Understanding(Input/output specification, etc)
Basic Dimensioning Tool started
Work on LTE Dimensioningand Tool
Coverage Planning (Radio Link Budget,Number of sites needed
based on Capacity)Capacity Evaluation
Review: Is thework complete?
Proceed with documentation
End
Chapter 5: Numerical Results
5 - 3
5.1 Up Link Budget
5.1.1 User Equipment effective Isotropic Radiated Power (EIRP):-
Figure (5-1) flowchart of effective isotropic radiated power
Figure (5-2) Calculation of EIRP
EIRP
Transmittedpower per PRB
Gain
-H/B losses
Chapter 5: Numerical Results
5 - 4
Inputs:-n’PRbsUE antenna GainP(UE)P(UE,PRB)Other GainsHead Body lossOutput:-EIRP(UE)Equation:-P(UE,PRB) =EIRPUE,PRB = PUE,PRB + GUE + Gothers – LHBLWhere:-n’PRBs: Number of Physical Resource BlocksPUE: user equipment output PowerP(UE,PRB): Power per Physical Resource BlocksGUE: User equipment transmitting antenna gain [dBi]LHBL : head body loss [dB]G others : It is gains due to MIMOEIRPUE,PRB: Effective Isotropic Radiated Power.
Excel Results
Coverage (UL)---- RL budget1-UE parameters
Item Unit ValuesP(UE) dBm 23P(UE) Watt 199.5262315
Channel B.W MHz 20nPRB PRBs 100
P(UE.PRB) Watt 1.995262315P(UE,PRB) dBm 33
UE Tx gain dBi 0other UE gain dBi 2L(HBL) in VOIP dB 3EIRP (UE,PRB) dBm 32
Table (5-1) EIRP
Chapter 5: Numerical Results
5 - 5
5.1.2 Enhanced NodeB Sensitivity:
-
Figure (5-3) flowchart of sensitivity of eNodeB
Figure (5-4) Sensitivity of Enhanced nodeB
Sensitivity
Thermal noise
Noise figure
Log Wprb(B.Wper PRB)
SINR
Chapter 5: Numerical Results
5 - 6
Inputs:-KTNtNflogWPRBa0a1a2a3γtarget
Output:-SeNodeBSINRN(PRB,UL)Equation:-SeNodeB= Nt + Nf + logWPRB +γtarget,UL
Where:- Nt: It is thermal noise power density Nf: noise figure of receiver Wprb : bandwidth per physical resourse block γtarget,UL: SINR requirement for uplink traffic channel
Excel Results2-BS parameter
Item Unit ValuesBoltzman constant J/K 1.38E-23
Ambient temperature K 290Thermal noise power density (Nt) dBm/Hz -174
Noise figure of eNodeB (Nf) dB 2BW per resource block [W(PRB)] MHz 0.18
a0 Kbps 536.6a1 dB 20.76a2 dB 13.28a3 Kbps 0
Bit rate [R(PRB)] Kbps 64SINR dB -2.499734217
Sensitivity of e.NoodeB dB -181.9470092
Table (5-2) Default values of Enhanced eNodeB sensitivity
Chapter 5: Numerical Results
5 - 7
5.1.3 Interference Margin (IM)
Figure (5-5) flowchart of Interference Margin
5.1.4 Log Normal Fading Margin (BLNF)
Figure (5-6) flowchart of Log Normal Fading Margin
Chapter 5: Numerical Results
5 - 7
5.1.3 Interference Margin (IM)
Figure (5-5) flowchart of Interference Margin
5.1.4 Log Normal Fading Margin (BLNF)
Figure (5-6) flowchart of Log Normal Fading Margin
Chapter 5: Numerical Results
5 - 7
5.1.3 Interference Margin (IM)
Figure (5-5) flowchart of Interference Margin
5.1.4 Log Normal Fading Margin (BLNF)
Figure (5-6) flowchart of Log Normal Fading Margin
Chapter 5: Numerical Results
5 - 8
5.1.5 Total Margins:-
Figure (5-7) flowchart of total margins
Figure (5-8) Total margin
Inputs:-SINR (Gamma)Q'8UL
Chapter 5: Numerical Results
5 - 8
5.1.5 Total Margins:-
Figure (5-7) flowchart of total margins
Figure (5-8) Total margin
Inputs:-SINR (Gamma)Q'8UL
Chapter 5: Numerical Results
5 - 8
5.1.5 Total Margins:-
Figure (5-7) flowchart of total margins
Figure (5-8) Total margin
Inputs:-SINR (Gamma)Q'8UL
Chapter 5: Numerical Results
5 - 9
Interference Factor (F)µσP%LNFBI (UL)FFMOutputs:-(IM) BIULBLNFTotal MarginsEquation:-
BIUL= , , ,BLM= norm inverse (P%,µ,σ)Total Margins= LNF+ BI(UL)+ FFMWhere:-γ target,Ul: Is the SINR target for the Uplink open loop Power ControlQUE: Is the average Uplink System loadF : It is the average ratio of Path gains for interfering cells to those of theserving cell.µ: is the mean of lognormalσ : is the standard deviation of lognormalP : is the coverage probabilityLNF: log normal fading marginsBI(UL): Interference marginFFM: fast fading margin
5-MarginsItem Unit Values
Mean of Log normal (µ) --------- 0Standard Deviation (σ) dB 3
Area of Coverage Flat Areaedge Coverage Prob. F(p) % 90
Lognormal Fading Margin [B(LNF)] dB 3.844654697Cell Loading Factor [Q(UL)] --------- 0.64
F --------- 0.7B(IUL) dB 1.26066082
Fast Fading Margin [B(FFM)] dB 2Total Margin dB
Table (5-3) Default values Total margin
Chapter 5: Numerical Results
5 - 10
5.1.6 Total Gains:-
Figure (5-9) flowchart of total gains5.1.7 Total Losses
Figure (5-10) flowchart of total losses
Connectorloss
Connectorspecifications
Connectorlength
Jumperloss
Jumperspecifications
Jumperlength
Carpenetration
loss
Head/body loss Buildingpenetration loss
Total losses
Chapter 5: Numerical Results
5 - 10
5.1.6 Total Gains:-
Figure (5-9) flowchart of total gains5.1.7 Total Losses
Figure (5-10) flowchart of total losses
Connectorloss
Connectorspecifications
Connectorlength
Jumperloss
Jumperspecifications
Jumperlength
Carpenetration
loss
Head/body loss Buildingpenetration loss
Total losses
Chapter 5: Numerical Results
5 - 10
5.1.6 Total Gains:-
Figure (5-9) flowchart of total gains5.1.7 Total Losses
Figure (5-10) flowchart of total losses
Connectorloss
Connectorspecifications
Connectorlength
Jumperloss
Jumperspecifications
Jumperlength
Carpenetration
loss
Head/body loss Buildingpenetration loss
Total losses
Chapter 5: Numerical Results
5 - 11
Figure (5-11) total gains and total lossesInputs:-G1G2BPLCPLJumper LengthJumper LossFeeder lengthFeeder lossContactor lossoutputs:-Gt: Total GainsTotal LossesEquation:-Total Gains = eNodeB antenna Gain + Other GainsTotal Losses= BPL+ CPL+ Jumper Length+ Jumper Loss+ Feederlength+ Feeder loss+ Contactor lossWhere:-G1: eNodeB antenna Gain
Chapter 5: Numerical Results
5 - 12
G2: Other gainsGt : Total GainsBPL: Building Penetration LossCPL: Car penetration loss
4-other eNodeB parameterItem Unit Values
Gain of e.NodeB dBi 18Other gain of e.NodeB dBi 4
Total Gain dBi 22Building Pentration Loss [LBPL] dBi 15
Car Penteration Loss [LCPL] dBi 9BS Feeder Specification (dB/100m) 3e.NodeB Feeder Length Meter 30
e.NodeB Feeder Loss (Lf) dB 1.05e.NodeB Jumper Specification dB/100m 2
e.NodeB Jumper Length Meter 5e.NodeB Jumper Loss (Lj) dB 0.1
e.NodeB Connector Loss (Lc) dB 1Total Loss dB 26.15
Table (5-4) Total Losses and Gain
5.1.8 Maximum Allowable Paths Loss (MAPL)
Figure (5-12) flowchart of maximum allowable path loss
MAPL
EIRP
Gain
-Losses
-margins
-Sensitivity ofeNodeB
Chapter 5: Numerical Results
5 - 13
Figure (5-13) Max. Allowable path loss in using GUI in Matlab
Inputs:-EIRP(UE,PRB)SeNodeBTotal losses (LBPL + LCPL + LeNodeB +Lj +LC )Total Gains (GeNodeB + Gother)Total margins (BLNF + BIul)Output:-MAPLUL
Equation:-MAPLUL=EIRPUL,PRB – SeNodeB – (BLNF + BIul) – (LBPL + LCPL + LeNodeB +Lj +LC ) + (GeNodeB + Gother)
Where:-BLNF: lognormal fading margin [dB]BIul: UL interference Margin [dB]LCPL: car penetration loss [dB]LBPL: Building Penetration LossGeNodeB: eNodeB Reciever antenna gainGother: is other Gain [dBi]
Chapter 5: Numerical Results
5 - 14
Lf eNodeB: is eNodeB feeder loss [dB]Lj: jumper lossLC: connector loss
Excel Results
6-Max allowable path lossItem Unit Values
MAPL dB 202.6916936
Table (5-5) Default values of Maximum allowable path loss (MAPL)
5.1.9 Cell Radius Using Ericson Variant Okumura-Hata
Figure (5-14) flowchart of cell radius using Ericson variant Okumara -Hata
Chapter 5: Numerical Results
5 - 14
Lf eNodeB: is eNodeB feeder loss [dB]Lj: jumper lossLC: connector loss
Excel Results
6-Max allowable path lossItem Unit Values
MAPL dB 202.6916936
Table (5-5) Default values of Maximum allowable path loss (MAPL)
5.1.9 Cell Radius Using Ericson Variant Okumura-Hata
Figure (5-14) flowchart of cell radius using Ericson variant Okumara -Hata
Chapter 5: Numerical Results
5 - 14
Lf eNodeB: is eNodeB feeder loss [dB]Lj: jumper lossLC: connector loss
Excel Results
6-Max allowable path lossItem Unit Values
MAPL dB 202.6916936
Table (5-5) Default values of Maximum allowable path loss (MAPL)
5.1.9 Cell Radius Using Ericson Variant Okumura-Hata
Figure (5-14) flowchart of cell radius using Ericson variant Okumara -Hata
Chapter 5: Numerical Results
5 - 15
5.1.10 Site Count
Figure (5-15) flowchart of site count
Figure (5-16) cell radius and Site Count
Inputs:-MAPLhb
Chapter 5: Numerical Results
5 - 15
5.1.10 Site Count
Figure (5-15) flowchart of site count
Figure (5-16) cell radius and Site Count
Inputs:-MAPLhb
Chapter 5: Numerical Results
5 - 15
5.1.10 Site Count
Figure (5-15) flowchart of site count
Figure (5-16) cell radius and Site Count
Inputs:-MAPLhb
Chapter 5: Numerical Results
5 - 16
hma(hm)FrequencyADeployment AreaCell RadiusCell AreaOutputs:-R in kilometersSite CountEquation:-R=10α
α=
Site Count =
Where:-Lo= A+13.82loghb+ a(hm)ϒ= 44.9 – 6.55loghbMAPL: maximum allowable paths losshb: base station or eNodeB antenna height [m]hm: height of user equipment antenna [m]a(hm): inverse relationshipis written as followsMAPL=A – 13.8loghb – a(hm) + (44.9 – 6.55log hb)log RA: frequency-dependent fixed attenuation valueSc: site count =
Table (5-6) values of Cell Radius and Site count with difference Basestations heights
Chapter 5: Numerical Results
5 - 17
5.2 Effects on cell Radius (R)In the following subsections the effect of the following parameters will beinvestigated
1- Effect of cell types, we will considered omni cell and 3 sectors cell2- Impact of different morphologies, we will considered Rural.
Suburban and Urban.3- Effect of cell loading factor4- Effect of eNodeB antenna height
5.2.1 The effect of cell Loading Factor (Q) on the cell Radius (R)Omni
Table (5-7) the effect of cell Loading Factor (Q) on the cell Radius (R)Omni
Figure (5-17) the effect of cell Loading Factor (Q) on the cell Radius (R)Omni
CLF 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9RUcell R
599.4749
592.2286
584.7593
577.0495
569.0798
560.828
552.2687
543.3728
534.1065
UR 66.50882
65.7482
64.96365
64.15327
63.31495
62.44628
61.54451
60.60648
59.62851
SU 162.179
160.2639
158.2893
156.2505
154.1423
151.9588
149.6931
147.3374
144.8827
DU 218.58 216.135
213.6123
211.0059
208.3088
205.5133
202.6104
199.5898
196.4394
Chapter 5: Numerical Results
5 - 18
We conclude that in case of omni cell as cell loading factor increase cellradius decreases for different types of morphologiesFor certain cell loading factor the cell radius increase as we go fromurban to suburban to ruralFor example for cell loading factor 50%Cell radius in urban = 63.31495 KmCell radius in suburban = 154.1423 KmCell radius for rural = 569.0798 Km
5.2.2 The effect of cell Loading Factor (Q) on the cell Radius (R) 3Sector
Table (5-8) the effect of cell Loading Factor (Q) on the cell Radius (R) 3sector
Figure (5-18) the effect of cell Loading Factor (Q) on the cell Radius (R)3 sector
h(B)/meter 10 20 30 40 50 60 70 80 90 100
RU cellR
253.1066
444.5555
636.3798
832.8866
1035.47
1244.719
1460.917
1684.21
1914.677
2152.359
UR 56.07967
90.7723
123.3535
155.2647
187.0305
218.9044
251.028
283.4883
316.3421
349.6283
SU 96.84865
161.4741
223.6102
285.4681
347.8312
411.0675
475.3765
540.8769
607.6433
675.7252
DU 215.7335
375.6464
534.7792
697.0233
863.6646
1035.261
1212.091
1394.3
1581.973
1775.158
Chapter 5: Numerical Results
5 - 19
We conclude that for 3 sector cell the same result as omni cell but moreover cell radius of 3 sector cell is larger than cell radius of omni cell onall morphologies For example for cell loading factor 50%Cell radius in urban = 92.56354 KmCell radius in suburban = 228.1687 KmCell radius for rural = 850.2738 Km
5.2.3 Effect of eNodeB antenna height on Cell Radius in omni cell
h(B)/meter 10 20 30 40 50 60 70 80 90 100
RU cellR
176.5427
304.0831
429.9145
557.4427
687.8188
821.5555
958.9149
1100.043
1245.025
1393.912
UR 39.11576
62.08971
83.33301
103.9171
124.2365
144.4842
164.7695
185.1606
205.7025
226.4265
SU 67.55226
110.4509
151.0628
191.0609
231.0496
271.3182
312.0271
353.274
395.1219
437.6136
DU 150.4748
256.9482
361.2769
466.5107
573.696
683.3069
795.5906
910.6878
1028.683
1149.629
Table (5-9) the effect of eNodeB antenna height on the cell Radius (R)omni
Figure (5-19) the effect of eNodeB antenna height on the cell
Radius (R) omin
Chapter 5: Numerical Results
5 - 20
We conclude that the cell radius of Omni cell increases as eNodeB antenna
height increase for different types of morphologies for certain eNodeB antenna
height for example h = 30 m
Cell radius in urban = 83.33301 Km
Cell radius in suburban =151.0628 Km
Cell radius in rural = 83.33301 Km
5.2.4 Effect of eNodeB antenna height types on Cell Radius in 3-
sector cell
h(B)/meter 10 20 30 40 50 60 70 80 90 100
RU cellR
253.1066
444.5555
636.3798
832.8866
1035.47
1244.719
1460.917
1684.21
1914.677
2152.359
UR 56.07967
90.7723
123.3535
155.2647
187.0305
218.9044
251.028
283.4883
316.3421
349.6283
SU 96.84865
161.4741
223.6102
285.4681
347.8312
411.0675
475.3765
540.8769
607.6433
675.7252
DU 215.7335
375.6464
534.7792
697.0233
863.6646
1035.261
1212.091
1394.3
1581.973
1775.158
Table (5-10) the effect of eNodeB antenna height on the cell Radius (R) 3sector
Figure (5-20) the effect of eNodeB antenna height on the cell Radius (R)
3 sector
Chapter 5: Numerical Results
5 - 21
For 3 sector cell the same results as omni cell but more over cell radius of
3 sector cell is larger than cell radius of omni cell
For 3 sector cell for certain eNodeB antenna height for example h = 30 m
Cell radius in urban = 123.3535 Km
Cell radius in suburban = 223.6102 Km
Cell radius in rural = 636.3798 Km
5.3 Downlink capacity
Figure (5-21) downlink capacityInputs:-MAPLLNF marginTotal GainTotal LossesP (norm,ref)N (PRB)Q (CLF)HChannel ModelOver Booking Factor
Chapter 5: Numerical Results
5 - 22
Subscriber ClassSubscriber Data rateCode rateNumber of userApplication services
Outputs:-L (sa,max,DL)P (e Node B,PRB)R(PRB,DL)Interface Margine (BIDL)SINRRavg,DLTotal Through putNumber of cell required (Nrequired)
T cell,DL
Equation:-
Nrequired = Tt/Tsite
Chapter 5: Numerical Results
5 - 23
RAVG,DL = RRB,DL (nRB,DL - nPDCCH)
Tsite = Tcell,DL × number of active users (U)
Tsite = Tcell,DL (Omni cell )
Tsite = 3 × Tcell (3 sector cell)
Ttotal = U × TU × (OBF)
Nsite =
Ctot=N× (PR×BWR+ PR×BWB)
C tot = N × (58% x 512 + 42% x 1000)
OBF = Ctot /Cref
DRresrved=P1×DR1+P2×DR2+P3×DR3
DRreserved = 25% x 50 + 10% x 32 + 12.5% x 64
DRshared-R=P4×DR4+P5 × (BWR-(DR1+DR2+DR3)
DRshared-R = 32.5% x BWR + 20% x (BWR - (50+32+64)
DRshared-B=P4×DR4+P5 × (BWB-(DR1+DR2+DR3)
DRshared-B = 32.5% x BWB + 20% x (BWB - (50+32+64))
Traffic R = N x (%PR) x (DRreserved + (DRshared-R / CR R)
Traffic B = N x (%PB) x (DRreserved + (DRshared-B / CR B)
Traffic Total = Traffic R + Traffic B = Tu × OBF
• Where:-
n'PRBs : number of physical resourse block
Chapter 5: Numerical Results
5 - 24
• RPRB,DL : Down Link data rate per physical resourse block
• (nPUCCH) : number of physical DL control channels
• QDL : The average downlink system load
• T(user) : Throughput for user
• B(IDL) : Downlink Interference margin (IM) or noise rise
• P(eNodeB,DL) : eNodeB transmitted or radiated power per physical
resourse block
• N(PRB,DL) : Down Link thermal noise per physical resourse block
• L(sa,max) : Maximum Down Link signal attenuation
• H : The average attenuation
• R(avrege,DL) : Average Downl Link data rate
• T(cell,DL) : The Downl Link data rate
• T(total) : Total Throughput
• T(site) : Throughput for site
• SINR(DL,avg) : Average Downl Link signal to interference and
noise ratio
• DRreserved: Minimum Reserved (Guaranteed) Data-rate for
CBR/VBR Applications
• DRshared-R : Shared Data-rate for Residential Class users with BE
Applications
Chapter 5: Numerical Results
5 - 25
• DRshared-B: Shared Data-rate for Business Class users with BE
Applications
• BWR: Residential class subscribers data-rate based on user
agreement
• BWB : Business class Subscribers data-rate based on user
agreement
• N: Total number of the users connected to the sector
• %PR: Percentage of the residential class subscribers within the area
under study
• CR R: Contention Ratio for residential class subscribers
• %PB: Percentage of the business class subscribers within the area
under study
• CR B: Contention Ratio for business class subscribers
Chapter SixConclusion and Suggestions for future work
Chapter 6: Conclusion and Suggestions for future work
6 - 2
Chapter sixConclusion and Suggestions for future work
6.1 Conclusions
In this project, we study LTE network coverage and capacitydimensioning.Dimensioning process is a part of planning process and provides thenetwork elements count as well as the capacity of those elements.We considered only access network dimensioning .Thus; the output of thedimensioning is the number of eNodeB that fulfil coverage and capacityrequirements.LTE coverage dimensioning is done via radio link budget (RLB) andsuitable propagation models .The output of RLB is the MAPL.Then using a suitable propagation model, the cell radius is obtained.Cell radius is used to obtain site count.LTE capacity dimensioning is obtained, given the number of subscribers,their demanded services and subscriber usage level. The cell radius basedon capacity is determined.Two values of cell radius are obtained:▪ One from coverage dimensioning▪ Second from capacity dimensioning the larger of the two numbers istaken as the final output
We get in consider the effect of the following parameters
1- Effect of cell types, we will considered omni cell and 3 sectors cell2- Impact of different morphologies, we will considered Rural.
Suburban and Urban.3- Effect of cell loading factor4- Effect of eNodeB antenna height
The effect of cell Loading Factor (Q) on the cell Radius (R) Omni cell
We conclude that in case of Omni cell as cell loading factor increase cell radiusdecreases for different types of morphologiesFor certain cell loading factor the cell radius increase as we go from urban tosuburban to ruralFor example for cell loading factor 50% cell radiuscell radius in urban = 63.31495 KmCell radius in suburban = 154.1423 KmCell radius for rural = 569.0798 Km
Chapter 6: Conclusion and Suggestions for future work
6 - 3
The effect of cell Loading Factor (Q) on the cell Radius (R) 3 Sector
We conclude that for 3 sector cell the same result as omni cell but moreover cell radius of 3 sector cell is larger than cell radius of omni cell onall morphologiesFor example for cell loading factor 50%Cell radius in urban = 92.56354 KmCell radius in suburban = 228.1687 KmCell radius for rural = 850.2738 Km
Effect of eNodeB antenna height on Cell Radius in omni cell
We conclude that the cell radius of omni cell increases as eNodeBantenna height increase for different types of morphologiesFor certain eNodeB antenna height cell radius increases as we go fromurban to suburban to rural for certain eNodeB antenna height for exampleh = 30 mCell radius in urban = 83.33301 KmCell radius in suburban =151.0628 KmCell radius in rural = 83.33301 Km
Effect of eNodeB antenna height on Cell Radius in 3 sector cell
For 3 sector cell the same results as omni cell but more over cell radius of3 sector cell is larger than cell radius of omni cellFor 3 sector cell For certain eNodeB antenna height for example h = 30 mCell radius in urban = 123.3535 KmCell radius in suburban = 223.6102 KmCell radius in rural = 636.3798 KmFinally, a dimension tool is developed.In this project, interference system based capacity dimensioning isstudied.
Chapter 6: Conclusion and Suggestions for future work
6 - 4
6.2 Suggestions for future work
In this project we considered only LTE coverage and capacitydimensioning. Data analysis, Traffic analysis and Transportdimensioning can be studied in the future.
In this project, we considered only access network, LTE corenetwork can be studied to determine core network nodes and thenumber of backhaul links required.
In this project, we considered VOIP only, other services such asweb browsing, file transfer and multimedia can be studiedindividually, then developing traffic model for user includingmixed services.
Detail LTE planning that include in addition to coverage andcapacity dimensioning: frequency planning, neighbour planningand parameter planning, finally a planning tools is developed.
In addition to introducing digital three dimensional (3D) mapwhich is imported in the planning tool as real prediction andsimulations of the RF signal level in a real traffic distribution.
Other methods for capacity dimensioning such as cell ring basedcapacity method and modulation based capacity dimensioningmethod can be studied.
In this project, we consider FDD (Frequency Division Duplex), inthe future we can use TDD (Time Division Duplex) or half duplex.
References
1) 3GPP Technical Report TR 25.813, “Radio Interface Protocol Aspects for
Evolved UTRA”, version 7.0.0
2) “Long Term Evolution (LTE): an introduction,” Ericsson White paper,
October 2007.
3) Dahlman, Parkvall, Skold and Beming, 3G Evolution: HSPA and LTE for
Mobile Broadband, Academic Press, Oxford, UK, 2007.
4) Indoor radio planning : A practical guide for GSM, UMTS, HSPA, LTE ,
Second edition ,MortenTolstup, 2011 John Willey sons.
5) Wiley-VCH Verlag GmbH, Boschstrasse 12, D-69469 Weinheim, Germany
6) Jossey-Bass, 989 Market Street, San Francisco, CA 94103-1741, USA
7) Abdul Basit Syed, Description of Models and Tool, Coverage and Capacity
Estimation of 3GPP Long Term Evolution, February, 2009
.