lte overview

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LTE – EPC Overview

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1 © Nokia Siemens Networks RA41201EN20GLA0

LTE RPESSLTE – EPC Overview

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Nokia Siemens Networks Academy

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Module Objectives

After completing this module, the participant should be able to:

• List the LTE/SAE main requirements

• Underline the LTE/SAE key features

• Review the 3GPP specification work concerning LTE/SAE.

• Describe the LTE Network Architecture

• List the key functionalities of the evolved NB

• Understand the protocol stack implemented on EUTRAN interfaces

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Module Contents

• LTE Requirements

• LTE Key Features

• LTE Standardization

• LTE Architecture

• Evolved NB functionalities

• EUTRAN Interfaces

• LTE Summary

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Module Contents







• LTE Summary

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The way to the Long-Term Evolution (LTE): a 3GPP driven initiative

• LTE is 3GPP system for the years 2010 to 2020 & beyond.

• It shall especially compete with WiMAX 802.16e/m

• It must keep the support for high & highest mobility users

like in GSM/UMTS networks

• The architectural changes are big compared to UMTS

• LTE commercial launch has started early 2010.

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What are the LTE challenges?

• Best price, transparent flat rate

• Full Internet

• Click-bang responsiveness

• reduce cost per bit

• provide high data rate

• provide low latency

The Users’ expectation… ..leads to the operator’s challenges

Price per Mbyte has to be reduced to remain profitable

User experience will have an impact on ARPU

LTE: lower cost per bit and improved end user experience

UMTS HSPA I-HSPA LTE

Cost per MByte

HSPA LTE HSPA LTE

Throughput Latency

Fact

or 1

0

Factor 2-3

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LTE = Long Term Evolution

• Peak data rates of 303 Mbps / 75 Mbps

• Low latency 10-20 msEnhanced consumer experience

• Scalable bandwidth of 1.4 – 20 MHz

Easy to introduce on any frequency band

• OFDM technology

• Flat, scalable IP based architecture

Decreased cost / GB

• Next step for GSM/WCDMA/HSPA and CDMA

A true global roaming technology

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Schedule for 3GPP releases

• Next step for GSM/WCDMA/HSPA and cdma2000

A true global roaming technology

year

3GPP Rel. 99/43GPP Rel. 99/4 Rel. 5Rel. 5 Rel. 6Rel. 6 Rel. 7Rel. 7

2007200520032000 2008

HSDPAIMS

HSUPAMBMS

WLAN IW

HSPA+LTE Studies

Specification:

2009

• LTE have been developed by the same standardization organization. The target has been simple multimode implementation and backwards compatibility.

• HSPA and LTE have in common:

– Sampling rate using the same clocking frequency

– Same kind of Turbo coding

• The harmonization of these parameters is important as sampling and Turbo decoding are typically done on hardware due to high processing requirements.

• WiMAX and LTE do not have such harmonization.

Rel. 8Rel. 8

LTE & EPC

Rel. 9Rel. 9

LTE-Astudies

LTE-A: LTE-Advanced

Rel. 10Rel. 10

LTE-AUMTS/

WCDMA

2011

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Comparison of Throughput and Latency (1/2)

HSPA R6

Max. peak data rate

Mb

ps

Evolved HSPA (Rel. 7/8, 2x2 MIMO)

LTE 2x20 MHz (2x2 MIMO)

LTE 2x20 MHz (4x4 MIMO)

Downlink

Uplink

350

300

250

200

150

100

50

0HSPAevo

(Rel8)

LTE

* Server near RAN

Latency (Rountrip delay)*

DSL (~20-50 ms, depending on operator)

0 20 40 60 80 100 120 140 160 180 200

GSM/EDGE

HSPARel6

min max

ms

Enhanced consumer experience:- drives subscriber uptake

- allow for new applications

- provide additional revenue streams

• Peak data rates of 303 Mbps / 75 Mbps

• Low latency 10-20 ms

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Scalable bandwidth

• Scalable bandwidth of 1.4 – 20 MHz

Easy to introduce on any frequency band: Frequency Refarming(Cost efficient deployment on lower frequency bands supported)

Scalable Bandwidth

Urban

2006 2008 2010 2012 2014 2016 2018 2020

Rural

2006 2008 2010 2012 2014 2016 2018 2020

or

2.6 GHz

2.1 GHz

2.6 GHz

2.1 GHz

LTE

UMTS

UMTS

LTE

900 MHz

900 MHz GSM

or

GSM UMTS

LTE

LTE

LTE

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0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

HSPA R6 HSPA R6 +UE

equalizer

HSPA R7 WiMAX LTE R8

bp

s/H

z/c

ell

DownlinkUplink

Increased Spectral Efficiency

• All cases assume 2-antenna terminal reception

• HSPA R7, WiMAX and LTE assume 2-antenna BTS transmission (2x2 MIMO)

ITU contribution from WiMAX Forum shows

DL 1.3 & UL 0.8 bps/Hz/cell

Reference:

- HSPA R6 and LTE R8 from 3GPP R1-071960

- HSPA R6 equalizer from 3GPP R1-063335

- HSPA R7 and WiMAX from NSN/Nokia simulations

• OFDMA technology increases Spectral efficiency

LTE efficiency is 3 x HSPA R6 in downlinkHSPA R7 and WiMAX have Similar Spectral Efficiency

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Reduced Network Complexity

• Flat, scalable IP based architecture

Flat Architecture: 2 nodes architectureIP based Interfaces

Access Core Control

Evolved Node B Gateway

IMS HLR/HSS

Flat, IP based architecture

Internet

MME

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LTE/SAE Requirements Summary

1. Simplify the RAN:- Reduce the number of different types of RAN nodes, and their complexity.

- Minimize the number of RAN interface types.

2. Increase throughput: Peak data rates of UL/DL 50/100 Mbps

3. Reduce latency (prerequisite for CS replacement).

4. Improve spectrum efficiency: Capacity 2-4 x higher than with Release 6 HSPA

5. Frequency flexibility & bandwidth scalability: Frequency Refarming

6. Migrate to a PS only domain in the core network: CSFB for initial phase

7. Provide efficient support for a variety of different services. Traditional CS services will be supported via VoIP, etc: EPS bearers for IMS based Voice

8. Minimise the presence of single points of failure in the network above the eNBs S1-Flex interface

9. Support for inter-working with existing 3G system & non-3GPP specified systems.

10. Operation in FDD & TDD modes

11. Improved terminal power efficiency

A more detailed list of the requirements and objectives for LTE can be found in TR 25.913.

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Module Contents







• LTE Summary

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LTE/SAE Key Features

EPS ( Evolved Packet System ) /SAE ( System Architecture Evolution ) /

LTE ( Long Term Evolution )

EPC ( Evolved Packet Core )EPC ( Evolved Packet Core )EUTRAN( Evolved UTRAN )

EUTRAN( Evolved UTRAN )

IP NetworkIP Network



OFDMA/SC-FDMA

MIMO ( beam-forming/spatial multiplexing)

HARQ

Scalable bandwidth(1.4, 3, 5, 10, .. 20 MHz)

Evolved Node B / No RNC

UL/DL resourcescheduling

IP Transport Layer

QoS Aware

Self Configuration

PS Domain only, No CS Domain

IP Transport Layer

QoS Aware

3GPP (GTP) or IETF (MIPv6)

Prepared for Non-3GPP Access

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LTE/SAE Key Features – EUTRAN (1/2)

Evolved NodeB• No RNC is provided anymore• The evolved Node Bs take over all radio management functionality.• This will make radio management faster & hopefully the network architecture

simpler

IP transport layer• E-UTRAN exclusively uses IP as transport layer

UL/DL resource scheduling• In UMTS physical resources are either shared or dedicated• Evolved Node B handles all physical resource via a scheduler and assigns

them dynamically to users & channels• This provides greater flexibility than the older system

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LTE/SAE Key Features – EUTRAN (2/2)

QoS awareness• The scheduler must handle & distinguish different QoS classes• Otherwise RT services would not be possible via EUTRAN• The system provides the possibility for differentiated services

Self configuration• Currently under investigation• Possibility to let Evolved Node Bs configure themselves• It will not completely substitute the manual configuration & optimization

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LTE/SAE Key Features – EPC (Evolved Packet Core)

Packet Switched Domain only• no CS domain is provided• if CS applications are required, they must be implemented via IP• only one mobility management for the UE in LTE.

3GPP (GTP) or IETF (MIPv6) option• The EPC can be based either on 3GPP GTP protocols (similar to PS domain in

UMTS/GPRS) or on IETF Mobile IPv6 (MIPv6)

Non-3GPP access• The EPC will be prepared also to be used by non-3GPP access networks (e.g.

LAN, WLAN, WiMAX, etc.)• This will provide true convergence of different packet radio access system

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Module Contents







• LTE Summary

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Standardisation around LTE

Next Generation Mobile Networks. Is a group of mobile operators, to provide a coherent vision for technology evolution beyond 3G for the competitive delivery of broadband wireless services.More in www.ngmn.org

Collaboration agreement established in December 1998. The collaboration agreement brings together a number of telecommunications standards bodies: ARIB, CCSA, ETSI, ATIS, TTA, and TTC.

More in www.3gpp.org

LTE/SAE Trial Initiative. Is was founded in may 2007 by a group of leading telecommunications companies.Its aim is to prove the potential and benefits that the LTE technology can offer.More in http://www.lstiforum.com/

LSTI

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From 3GPP Specs into Commercial Launch

• Historically, 1.25-1.5 years from the specs approval until backwards compatibility (ASN.1) with HSDPA and HSUPA

• Historically, 1.25-1.5 years from the backwards compatibility until commercial launch with HSDPA & HSUPA

• LTE backwards compatibility: 03/2009. First commercial launch: 12/2009

2003 2004 2005 2006 2007

1 2 3

1 2 3

1.5 years 1.5 years

1.25 years 1.25 years

1 = Specs approved

2 = Backwards compatibility

3 = 1st commercial launch

HSDPA

HSUPA

2008 2009 2010

1 2 31.25 years 0.75 years

LTE

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3GPP LTE Background (1/2)Milestones

• End 2004 3GPP workshop on UTRAN Long Term Evolution

• March 2005 Study item started

• December 2005 Multiple access selected

• March 2006 Functionality split between radio and core agreed

• September 2006 Study item closed & approval of the work items

• December 2007 1st version of all radio specs approved

• March 2008 3GPP Release 8 Stage 1 specifications were frozen

• December 2008 3GPP Release 8

2005 2006 2007 2008

Feasibility study started

Multiple access

selected

Feasibility study closed

Work item started

Work plan approved

Stage 2 approved

Stage 3 approved

Radio Specs approved

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3GPP LTE Background (2/2)Schedule

• 2009 2100 & 2100/1700 MHz frequency bands selected; Release 9

• 2010 Additional frequency bands added (700, 800 & 2600 MHz). Inter-RAT Mobility. LTE capable devices

• 2011 Network Sharing. Self-optimized networks. Part of 3GPP Release 9. Release 10 (LTE-Advanced)

2008 2009 2010 2011

Demonstrate LTE Air

Interface Performance

Operator Trials. Friendly-use networks

LTE Networks Launch:

commercial solution available

Large Scale LTE Networks.

VoIP service optimized.

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Module Contents







• LTE Summary

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Network Architecture Evolution

SAE GWGGSN

SGSN

RNC

Node B (NB)

Direct tunnel

GGSN

SGSN

I-HSPA

MME/SGSN

HSPA R7 HSPA R7 LTE R8

Node B + RNC

Functionality

Evolved Node B (eNB)

GGSN

SGSN

RNC

Node B (NB)

HSPA

HSPA R6LTE

User plane

Control Plane

• Flat architecture: single network element in user plane in radio network and core network

SAE: System Architecture Evolution

SAE GW: Serving Gateway +PDN Gateway

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Evolved Packet System (EPS) Architecture - Subsystems

• The EPS architecture goal is to optimize the system for packet data transfer.

• There are no circuit switched components. The EPS architecture is made up of:

– EPC: Evolved Packet Core, also referred as SAE

– eUTRAN: Radio Access Network, also referred as LTE

LTE or eUTRAN SAE or EPC

EPS Architecture

• EPC provides access to external packet IP networks and performs a number of CN related functions (e.g. QoS, security, mobility and terminal context management) for idle and active terminals

• eUTRAN performs all radio interface related functions

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LTE/SAE Network Elements

Main references to architecture in 3GPP specs.: TS23.401,TS23.402,TS36.300

LTE-UE

Evolved UTRAN (E-UTRAN)

MME S10

S6a

ServingGateway

S1-U

S11

PDNGateway

PDN

Evolved Packet Core (EPC)

S1-MME

PCRFS7 Rx+

SGiS5/S8

Evolved Node B(eNB)

X2

LTE-Uu

HSS

Mobility Management

Entity Policy & Charging Rule

Function

SAEGateway

eNB

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Module Contents







• LTE Summary

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Inter-cell RRM: HO, load balancing between cells

Radio Bearer Control: setup , modifications and release of Radio Resources

Connection Mgt. Control: UE State Management,MME-UE Connection

Radio Admission Control

eNode B Meas. collection and evaluation

Dynamic Resource Allocation (Scheduler)

eNB Functions

IP Header Compression/ de-compression

Access Layer Security: ciphering and integrity protection on the radio interface

MME Selection at Attach of the UE

User Data Routing to the SAE GW

Transmission of Paging Msg coming from MME

Transmission of Broadcast Info (e.g. System info,MBMS)

• Only network element defined as part of eUTRAN.

• Replaces the old Node B / RNC combination from 3G.

• Terminates the complete radio interface including physical layer.

• Provides all radio management functions

• To enable efficient inter-cell radio management for cells not attached to the same eNB, there is a inter-eNBinterface X2 specified. It will allow to coordinate inter-eNB handovers without direct involvement of EPC during this process.

Evolved Node B (eNB)

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Module Contents







• LTE Summary

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LTE Radio Interface & the X2 Interface

LTE-Uu interface• Air interface of LTE

• Based on OFDMA in DL & SC-FDMA in UL

• FDD & TDD duplex methods

• Scalable bandwidth: 1.4MHz - 20 MHz

X2 interface• Inter eNB interface

• X2AP: special signalling protocol (Application Part)

• Functionalities:

– In inter- eNB HO to facilitate Handover and provide data forwarding.

– In RRM to provide e.g. load information to neighbouring eNBs to facilitate interference management.

– Logical interface: doesn’t need direct site-to-site connection, i.e. can be routed via CN as well

(E)-RRC(E)-RRC User PDUsUser PDUs User PDUsUser PDUs

PDCPPDCP

..

RLCRLC

MACMAC

LTE-L1 (FDD/TDD-OFDMA/SC-FDMA)LTE-L1 (FDD/TDD-OFDMA/SC-FDMA)

TS 36.300

eNB

LTE-Uu

eNB

X2

User PDUsUser PDUs

GTP-UGTP-U

UDPUDP

IPIP

L1/L2L1/L2

TS 36.424

X2-UP(User Plane)X2-CP

(Control Plane)

X2-APX2-AP

SCTPSCTP

IPIP

L1/L2L1/L2TS 36.421

TS 36.422

TS 36.423

TS 36.421

TS 36.420

UDP: User Datagram Protocol ( L4 Transport Layer)

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S1-MME & S1-U Interfaces

MME

ServingGateway

S1-MME(Control Plane)

S1-U(User Plane)

NAS ProtocolsNAS Protocols

S1-APS1-AP

SCTPSCTP

IPIP

L1/L2L1/L2

User PDUsUser PDUs

GTP-UGTP-U

UDPUDP

IPIP

L1/L2L1/L2

TS 36.411

TS 36.411

TS 36.412

TS 36.413

TS 36.414

TS 36.410

eNB

S1 interface is divided into two parts:

S1-MME interface

• Control Plane interface between eNB & MME

• S1AP:S1 Application Protocol

• MME & UE will exchange NAS signaling via eNB through this interface ( i.e.

authentication, tracking area updates)

• S1 Flex: an eNB is allowed to connect to a maximum of 16 MME. (LTE2, RL20)

S1-U interface

• User plane interface between eNB & Serving Gateway.

• Pure user data interface (U=User plane)

LTE4: Multi-Operator Core Network (MO-CN): An eNB can be connected simultaneously to the different Evolved Packet Cores (EPCs) of different operators, and shared by them.

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Module Contents







• LTE Summary

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LTE: What is new?

• new radio transmission schemes:

– OFDMA in DL

– SC-FDMA in UL

– MIMO Multiple Antenna Technology

• New radio protocol architecture:

– Complexity reduction

– Focus on shared channel operation, no dedicated channels anymore

• new network architecture:

– More functionality in the base station (eNodeB)

– Focus on PS domain

– Flat architecture (2-nodes)

– All-IP

• Important for Radio Planning

– Frequency Reuse 1▪ No need for Frequency Planning

– No need to define neighbour lists in LTE

OFDMA: Orthogonal Frequency Division Multiple Access

SC-FDMA: Single Carrier Frequency Division Multiple Access

PS: Packet Switched

lte overview

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