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3 May 2007

Long Term Evolution (LTE) and System Architecture Evolution (SAE)

www.nethawk.fi

3 May 2007

Contents

> Why LTE/SAE?> LTE Overview> LTE technical objectives and architecture> LTE radio interface> RAN interfaces> SAE architechture [3GPP TS 23.401]> Functions of eNB> Functions of aGW> GTP-U tunneling> Non-3GPP access tunneling> Testing challenges with LTE> LTE standardisation status

www.nethawk.fi

3 May 2007

Why LTE/SAE?

> Packet Switched data is becoming more and more dominant> VoIP is the most efficient method to transfer voice data Need for PS optimised system> Amount of data is continuously growing Need for higher data rates at lower cost> Users demand better quality to accept new servicesHigh quality needs to be quaranteed> Alternative solution for non-3GPP technologies (WiMAX) needed

> LTE will enhance the system to satisfy these requirements.

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3 May 2007

LTE Overview

> 3GPP R8 solution for the next 10 years> Peaks rates: DL 100Mbps with OFDMA, UL 50Mbps with SC-FDMA> Latency for Control-plane < 100ms, for User-plane < 5ms > Optimised for packet switched domain, supporting VoIP> Scaleable RF bandwidth between 1.25MHz to 20MHz> 200 users per cell in active state> Supports MBMS multimedia services> Uses MIMO multiple antenna technology> Optimised for 0-15km/h mobile speed and support for up-to 120-350

km/h> No soft handover, Intra-RAT handovers with UTRAN> Simpler E-UTRAN architecture: no RNC, no CS domain, no DCH

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3 May 2007

LTE technical objectives and architecture

> User throughput [/MHz]:– Downlink: 3 to 4 times Release 6 HSDPA – Uplink: 2 to 3 times Release 6 Enhanced Uplink

> Downlink Capacity: Peak data rate of 100 Mbps in 20 MHz maximum bandwidth

> Uplink capacity: Peak data rate of 50 Mbps in 20 MHz maximum bandwidth

> Latency: Transition time less than 5 ms in ideal conditions (user plane), 100 ms control plane (fast connection setup)

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3 May 2007

> Mobility: Optimised for low speed but supporting 120 km/h– Most data users are less mobile!

> Simplified architecture: Simpler E-UTRAN architecture: no RNC, no CS domain, no DCH

> Scalable bandwidth: 1.25MHz to 20MHz: Deployment possible in GSM bands.

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3 May 2007

LTE radio interface

> New radio interface modulation: SC-FDMA UL and OFDMA DL

– Frequency division, TTI 1 ms– Scalable bandwidth 1.25-20MHz– TDD and FDD modes

• UL/DL in either in same or in another frequncy

– OFDMA has multiple orthogonal subcarries that can be shared between users

• quickly adjustable bandwith per user – SC-FDMA is technically similar to OFDMA

but is better suited for uplink from hand-held devices

• Single carrier, time space multiplexing• Tx consumes less power

From Ericsson, H. Djuphammar

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3 May 2007

LTE/SAE Keywords

> aGW Access Gateway> eNB Evolved NodeB> EPC Evolved Packet Core> E-UTRAN Evolved UTRAN> IASA Inter-Access System Anchor> LTE Long Term Evolution of UTRAN> MME Mobility Management Entity> OFDMA Ortogonal Frequency Division Multiple Access> SC-FDMA Single Carrier Frequency Division Multiple Access> SAE System Architecture Evolution> UPE User Plane Entity

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3 May 2007

eNB

aGW

S1

eNB

S8

X2

aGW

eNB

X2

RAN interfaces

>X2 interface between eNBs for handovers>Handover in 10 ms>No soft handovers >Interfaces using IP over E1/T1/ATM/Ethernet /…>Load sharing in S1>S1 divided to S1-U (to UPE) and S1-C (to CPE) >Single node failure has limited effects

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3 May 2007

> SAE architecture [3GPP TS 23.401]

GERAN

UTRAN GPRS Core

MME UPESAEGW

PCRF

Operator IP services

(including IMS, PSS, ...)

Non-3GPP IP Access

Evolved Packet Core

S11

S2

S3 S4

S7

S6

SGiS1

Gb

IuRx+

X1

eNB

X1

eNB

X2

Evolved RAN

aGW

PDNSAE GW

S5

HSS

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3 May 2007

SAE architechture [3GPP TS 23.401]TBD

eNB

TBD

eNB

aGW

S1

TBD

eNB

S8

X2

Operator IP service, including

IMS

SAE GW

S11

PDNSAE GW

S11S5

SGi

Evolved RAN

HSS PCRF

IASA

aGW = MME/UPE

aGW

S6aS7

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3 May 2007

Functions of eNB

> Terminates RRC, RLC and MAC protocols and takes care of Radio Resource Management functions

– Controls radio bearers– Controls radio admissions– Controls mobility connections– Allocates radio resources dynamically (scheduling)– Receives measurement reports from UE

> Selects MME at UE attachment> Schedules and transmits paging messages coming from MME> Schedules and transmits broadcast information coming from MME &

O&M> Decides measurement report configuration for mobility and scheduling> Does IP header compression and encryption of user data streams

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3 May 2007

Functions of aGW

> Takes care of Mobility Management Entity (MME) functions– Manages and stores UE context– Generates temporary identities and allocates them to UEs– Checks authorization– Distributes paging messages to eNBs– Takes care of security protocol– Controls idle state mobility– Control SAE bearers– Ciphers & integrity protects NAS signaling

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3 May 2007

> Takes care of User Plane Entity (UPE) functions– Terminates for idle state UEs the downlink data path and

triggers/initiates paging when downlink data arrive for the UE.– Manages and stores UE contexts, e.g. parameters of the IP bearer

service or network internal routing information. – Switches user plane for UE mobility– Terminates user plane packets for paging reasons

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3 May 2007

Functions

S1

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3 May 2007

RRC

RLC

MAC

PHY

PDCP

RRC

RLC

MAC

PHY

PDCP

NAS NAS

aGWUE eNB

S1

> LTE Control Plane

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3 May 2007

> LTE User Plane

RLC

MAC

PHY

PDCP

RLC

MAC

PHY

PDCP

aGWUE eNB

IP IP

S1

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3 May 2007

GTP-U tunneling

SAE GWUPEeNB ServerUEUE

Radio L1Radio L1

MACMAC

PDCPPDCPIPv6/v4

u

ApplicationApplication

TCP/UDP

RLCRLC

L1L1

L2L2

IP

UDPUDP

GTP-UGTP-U

L2L2

L1L1

IP

UDPUDP

GTP-UGTP-U

L2L2

L1L1

IP

UDPUDP

GTP-UGTP-U

L2L2

L1L1

IPv6/v4

TCP/UDPApplication

L1L1

L2L2

L1L1

L2L2

X1X1 S1S1 S11S11 SGiSGi

IP

UDPUDP

GTP-UGTP-U

L2L2

L1L1

IP

UDPUDP

GTP-UGTP-U

L2L2

L1L1

S5S5PDN

SAE GW

Header compression & encryption

IP

UDPUDP

GTP-UGTP-U

L2L2

L1L1Radio Radio L1L1

MACMACRLCRLCPDCPPDCP

ENCENC

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3 May 2007

Non-3GPP access tunneling

PDN

SAE GW

HA

AP ServerUEUE

L1L1

L2L2IP

L2L2

L1L1

IPv6/v4

TCP/UDPApplication

L1L1

L2L2

L1L1

L2L2

WLANWLAN S2S2 SGiSGi

L2L2

L1L1

IP

MIPIPv4/6

IPUDP

IP

MIPIPv4/6

UDP

IP

L2L2

L1L1

IP

L2L2

L1L1

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3 May 2007

Testing challenges with LTE

> How to optimize radio interface?– No radio measurement data available since no ”Iub-like” interface

> Increased complexity of eNB– need for analysis of internal traffic– need for internal debugging– need for analysis of protocol data

> How to test inter-eNB handovers?> How to test inter-system handovers?> How to test voice and video broadcast?> 10x higher throughput How to verify eNB performance?> How to test application level QoS? How to verify SLA?> How to handle network management challenges?

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3 May 2007

LTE standardisation status

> Specification work done by 3GPP TS RAN.> First 3GPP specs expected 3Q2007> First trials expected 2008> Commercial release expected 2009> NetHawk is member in 3GPP and follows closely the standardisation

work

2007 2008 2009

CommercialRelease

TrialsSpecification

First 3GPP specs expected 3Q/2007

www.nethawk.fi

3 May 2007