5.oep100330 lte cell_planning_issue1.10

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LTE Cell Planning

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LTE Cell Planning


The general process includes information collection, pre-planning, detailed planning,

and cell planning. In the cell planning, main concerns are frequency planning, TA

planning, PCI planning, and PRACH planning.

LTE Cell Planning


LTE Cell Planning


There are several new frequency band options for LTE, some of which are available now or

should be within the next few years. These include the 700MHz, AWS (Advanced Wireless

Services) and 2.6GHz bands, as well as the re-use of existing GSM 900MHz and 1800MHz

bands. In addition, due to poor harmonization, there are other spectrum bands available,

including: 850MHz, 1500MHz, 1700MHz and 1900MHz.

LTE Cell Planning


LTE Cell Planning


Application scenario: Adapt to situations with integrated operator frequency resources

and consecutive frequency bands. If the frequency point bandwidth is wide (>=10MHz), it

can be used as the initial network construction mode of the urban or densely-populated

urban areas. Basically satisfy the phase one capacity requirements. Use relatively narrow

frequency point bandwidth (<=10MHz) to implement wide coverage of suburban and rural

areas; thus reducing the initial network construction cost.

LTE Cell Planning


Application scenario:

Adapt to situations that the operator frequency resources are rich or frequency

bands dispersed and bandwidth is narrow.

The system capacity is dependent on the bandwidth of single frequency point. If

the bandwidth of frequency point is wide (>=5MHz), it can be used on initial

network construction of dense or common urban. If the bandwidth of frequency

point is narrow (<5MHz), it can be used on coverage of suburban and rural areas.

LTE Cell Planning


ICIC is a technology that mitigates inter-cell interference together with the scheduling and

power control technologies. ICIC is applied at the Medium Access Control (MAC) layer.

ICIC restricts highly interfering CEUs within the orthogonal bands at the edge of cells or

schedules the CEUs in neighboring cells at different points of time. In this way, ICIC

mitigates inter-cell interference, increases the CEU throughput, and improves the system

coverage. This document provides the details on ICIC.

LTE Cell Planning


LTE Cell Planning


TA: Similar to the location area and routing area in 2G/3G networks, the tracking area

(TA) is used for paging. TA planning aims to reduce location update signaling caused

by location changes in the LTE system.

TA list : A list of TAIs that identify the tracking areas that the UE can enter without

performing a tracking area updating procedure. The TAIs in a TAI list assigned by an

MME to a UE pertain to the same MME area. In LTE system, if an UE changes the

TAs in the TAI list, TA update won’t be triggered.

LTE Cell Planning


In the Los Angles, there are several independent density area that connected by the main

road (like island) . The UE may go across the different area through this road.

LTE Cell Planning


LTE Cell Planning


In this scenario, users are average distributed in each area

LTE Cell Planning


LTE Cell Planning


A TA coverage should be proper setting according to the capability of EPC

When the suburban area and urban area are covered discontinuously, an independent TA

is used for the suburban area.

LTE Cell Planning


LTE Cell Planning


PCI: Physical Cell ID, is used to generate scrambling code to identify the different cell

LTE Cell Planning


Differences between a scrambling code and a PCI: The scrambling code ranges from

0 to 511 whereas the PCI ranges from 0 to 503. In addition, the protocols do not have

specific requirements for scrambling code planning. Therefore, only the reuse

distance needs to be ensured in scrambling code planning. For PCI planning,

however, 3GPP protocols require that the value of PCI/3 should be 0, 1, or 2 in each

eNB.

LTE Cell Planning


PCI: Physical Cell ID, is used to generate scrambling code to identify the different cell

LTE Cell Planning


LTE Cell Planning


A CP is a copy of the end of an OFDM symbol to the start position of the symbol. Each CP

generates a guard interval between two OFDM symbols.

LTE Cell Planning


The symbol energy that can be captured by the OFDM receiver depends on the CP length:

If the CP is longer than the multipath delay of an OFDM symbol, the OFDM

receiver can capture all energy of the symbol.

If the CP is shorter than the multipath delay of an OFDM symbol, the OFDM

receiver can capture only some energy of the symbol.

LTE Cell Planning


LTE Cell Planning


The random access procedure is used in various scenarios, including initial access,

handover, or re-establishment. Like other 3GPP systems the random access procedure

provides a method for contention and non-contention based access. The PRACH (Physical

Random Access Channel) includes RA (Random Access) preambles generated from ZC

(Zadoff-Chu) sequences.

There are five preamble formats defined which four of them are for FDD

LTE Cell Planning


Other preamble formats then Format 0 and Format 4 (TDD) are available only with the

LOFD-001009 Extended Cell Access Radius feature.

LTE Cell Planning


c = speed of light (300000km/h)

LTE Cell Planning


LTE Cell Planning


* in fact, with the lowest configuration, where we assume maximum cell radius of 790m

we assign only one value per cell. Further explanation on following slides.

LTE Cell Planning


PRACH configuration is defined by the following parameters

Root sequence, setting in the eNodeB

Ncs: Automatically setting based on the cell radius configuration

PRACHfrequency offset: Scheduled by eNodeB

High speed flag: Indicate whether the cell is for high speed

All the parameters all carried by Sib2

LTE Cell Planning


LTE Cell Planning


Calculations:

LTE Cell Planning


ZeroCorrZone Ncs Preamble

Format T_GT (ms)

Max Delay

Spread [ms]

Max Cell Radius

(according to T_GT) [km]

Max Cell Radius

(according to Ncs) [km]

0 839 3 715.625 16.666 107.344 117.214

1 13 0 96.875 5.208 14.531 0.792

2 15 0 96.875 5.208 14.531 1.078

3 18 0 96.875 5.208 14.531 1.507

4 22 0 96.875 5.208 14.531 2.079

5 26 0 96.875 5.208 14.531 2.651

6 32 0 96.875 5.208 14.531 3.510

7 38 0 96.875 5.208 14.531 4.368

8 46 0 96.875 5.208 14.531 5.512

9 59 0 96.875 5.208 14.531 7.371

10 76 0 96.875 5.208 14.531 9.803

11 93 0 96.875 5.208 14.531 12.234

12 119 2 196.875 5.208 29.531 15.953

13 167 2 196.875 5.208 29.531 22.818

14 279 1 515.625 16.666 77.344 37.119

15 419 1 515.625 16.666 77.344 57.143

LTE Cell Planning


Here is an another example for the root sequence planning, suppose the cell radius is

10km

The Ncs value is determined by the cell radius. If the cell radius is 9.8 km, the

Ncs value is 76

The value of 839/76 is rounded down to 11, that is, each index can generate

11 preamble sequences. In this case, six root sequence indexes are required

to generate 64 preamble sequences.

The number of available root sequence indexes is 139 (0, 6, 12…828)

The available root sequence indexes are assigned to cells. The assignment

principles are similar to those for PCIs.

LTE Cell Planning


LTE Cell Planning


Meaning: Indicates the ratio of UL subframes to DL subframes in a TDD cell. For details,

see 3GPP TS 36.211.

GUI Value Range: SA0(SA0), SA1(SA1), SA2(SA2), SA3(SA3), SA4(SA4), SA5(SA5),

SA6(SA6)

Unit: None

Actual Value Range: SA0, SA1, SA2, SA3, SA4, SA5, SA6

LTE Cell Planning


LTE Cell Planning


5.oep100330 lte cell_planning_issue1.10

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