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Wireless Test World 2009

Wireless Test World 2009 Agilent, Your Partner in AdvancingNew Wireless Communications

Page 1Page 1Page 1

Concepts of LTE-Advanced

© Copyright 2009 Agilent Technologies, Inc.

Wireless Test World 2009 Page 2Page 2

Agenda


Who Put the “G” in 3G and 4GLTE and LTE-Advanced timelineLTE and IMT-Advanced Performance GoalsSystem Architecture EvolutionHow to meet these goals

• Multiple antenna techniques– MIMO– Beam Forming– Coordinated Multi-Point (CoMP)

• Fractional Frequency Reuse• Relays• Femtocells• Clustered DFT-S-OFDM Uplink


IS-136TDMA PDCGSMIS-95A

cdma

Wireless evolution 1990 - 2010

2G

Incr

easi

ng e

ffici

ency

, ban

dwid

th a

nd d

ata

rate

s

2.5G

3G

3.5G

3.9G

4G

HSCSD iModeGPRSIS-95Bcdma

LTE-Advanced Rel-9/10

802.16m

E-GPRSEDGEcdma2000 W-CDMA

FDDW-CDMA

TDDTD-SCDMALCR-TDD

HSUPAFDD & TDD

1xEV-DORelease B

1xEV-DORelease A

1xEV-DORelease 0

HSDPAFDD & TDD

Edge Evolution HSPA+

802.11g

802.11a

802.11b

802.16dFixed

WiMAXTM

802.11n

802.11h

WiBRO

Page 3

LTERel-8

802.16eMobile

WiMAXTMUMB



ITU – the source of the “G” in Wireless

International Mobile Telephony

International Telecommunications Union

ITU-Radio Working Party 8F (now 5D)

IMT-2000 “3G” IMT-Advanced “4G”

All “IMT” technologies have access to designated IMT spectrum

Page 4Concepts of LTE-Advanced


IMT Spectrum

3300 3400 3500 3600 3700 3800 3900 4000 4100 4200 4300 4400 4500 4600 4700 4800 4900 5000

1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900

20252110 2170 26901710

100 500 600 700 800 900 1000200 300 400

5150 470 890915925960

806450 790698

New for IMT in some countries ofRegions 1 & 3

NewRegion 2

NewGlobal

ExistingIMTidentified

IMT bands can be used by all IMT-2000 and IMT-Advanced technologies



Agenda



• Fractional Frequency Reuse• Relays• Femtocells


Wireless Test World 2009 Page 7

2005 2006 2007 2008 2009 2010

First GCF UE certification

Rel-7 Feasibility study

Rel-8 Test development

2011 2012

Rel-8 Specification development

GCF Test validation

First Trial Networks

FirstCommercial

NetworksFurther

Commercial Networks

LSTI Proof of Concept

LSTI IODT

LSTI IOT

LSTI Friendly Customer Trials

LTE timeline

LSTI = LTE/SAE Trial Initiative GCF = Global Certification ForumConcepts of LTE-Advanced


LTE-Advanced timeline


Wireless Test World 2009 Page 9

3GPP UMTS standards evolution (RAN)

1999

2010

Release Functional Freeze

Main feature of Release

Rel-99 March 2000 UMTS 3.84 Mcps (W-CDMA FDD & TDD)

Rel-4 March 2001 1.28 Mcps TDD (aka TD-SCDMA)

Rel-5 June 2002 HSDPA

Rel-6 March 2005 HSUPA (E-DCH)

Rel-7 Dec 2007 HSPA+ (64QAM DL, MIMO, 16QAM UL). LTE & SAE Feasibility Study

Rel-8 Dec 2008 LTE Work item – OFDMA air interface

SAE Work item, New IP core network

Edge Evolution, more HSPA+

Rel-9 Dec 2009? UMTS and LTE minor changes, LTE-Advanced feasibility study

Rel-10 TBD LTE-Advanced (4G) work item



Agenda






IMT-2000 3G requirement

Major focus on data transmission

• 2048 kbps for stationary user

• 384 kbps for low mobility

• 144 kbps for high mobility

No requirements on spectral efficiency

Specs were per user, not per any channel size• Led to 3x cdma2000 to meet the rate spec



IMT-Advanced requirements – 4G

• A high degree of commonality of functionality worldwide while retaining the flexibility to support a wide range of services and applications in a cost efficient manner;

• Compatibility of services within IMT and with fixed networks;

• Capability of interworking with other radio access systems;

• High quality mobile services;

• User equipment suitable for worldwide use;

• User-friendly applications, services and equipment;

• Worldwide roaming capability; and

• Enhanced peak data rates to support advanced services and applications (100 Mbit/s for high and 1 Gbit/s for low mobility were established as targets for research) .



LTE-Advanced spectral efficiency requirements

Page 13

Item Sub-category

LTE (3.9G) target

LTE-Advanced (4G) target

IMT-Advanced (4G) target

Peak Spectral Efficiency(b/s/Hz)

Downlink 16.3 (4x4 MIMO) 30 (up to 8x8 MIMO)

15 (4x4 MIMO)

Uplink 4.32(64QAM SISO)

15 (up to 4x4 MIMO)

6.75 (2x4 MIMO)

Downlink cell spectral efficiency

b/s/Hz 3km/h500m ISD

2x2 MIMO 1.69 2.4

4x2 MIMO 1.87 2.6 2.6

4x4 MIMO 2.67 3.7

Downlink cell-edge user spectral

efficiency b/s/Hz 5 percentile 10 users

500M ISD

2x2 MIMO 0.05 0.07

4x2 MIMO 0.06 0.09 0.075

4x4 MIMO 0.08 0.12

ISD is Inter Site Distance 2x to 4x efficiency of Rel 6 HSPA


Wireless Test World 2009 8th May 2008

Spectral Efficiency bits / sec / Hz

0.01

0.1

1

10

100

1980 1985 1990 1995 2000 2005 2010 2015Average efficiency Peak efficiency

AMPSGSM

GPRSEDGE

W-CDMA

HSDPA1xEV-DO

LTE802.16e

IS-95C

1xEV-DO(A)EGPRS2 1/3

W-CDMA (R99)EGPRS 4/12 (R99)

Growth in peak and average spectral efficiency

HSDPA (R7)HSDPA (R5)

LTEtarget

EGPRS 1/3 (R99)

Peak efficiency lies around this line

Average efficiency and hence capacitygrowth of deployed systems lags well behind and will level off due to inter-cell interference

But the pursuit of peak efficiency is massively driving up air interface cost &complexity



Emphasis for IMT-Advanced

Average spectral efficiency and cell-edge most important

Peak performance less important



Agenda






Logical high level architecture for SAE Evolved Packet Core with multi-RAT integration (Rel 8)

TR 23.882 Figure 4.2-1

HSS - Home subscriber server

IMS - IP multimedia subsystem

Inter AS anchor - Inter access system anchor

MME - Mobility management entity

Op. IP Serv. - Operator IP service

PCRF - Policy and charging rule control function

UPE - User plane entity

WiMAX could connect here



Agenda






LTE-Advanced solution proposals

• Simultaneous uplink transmission of control and data• Self optimizing networks

• A new more flexible uplink transmission scheme “clustered”Discrete Fourier Transform Spread OFDM

• Bandwidth aggregation – Up to 100 MHz in 20 MHz channels• Higher order MIMO and beamsteering

• 8x8 in downlink, 4x4 in uplink• Cell-edge interference co-ordination and cancellation• Co-operative MIMO - Coordinated Multipoint (CoMP)• In-channel relay• Femtocells



C/I – another way of stating the problemCarrier to Interference ratio

Page 20

Isolated CellHigh DensityIn Building



Variation due to fading and variable interference

Page 21

Most macrocell activity takes place in this

region

Variation in the frequency domain not

shown

Real life performance 2x2 MIMOα,β are correlation of antenna at cell, UE



MIMO and Beamsteering – Increase C in C/I

Page 22

Rel-8 LTE UELTE-A UE

• Multiple antennas used for MIMO can also be used for beam forming

• LTE-A can go up to 8x8

• Must be backward compatible with Rel-8 –has limited 4x4 steering

• Must have dedicated Reference Signals

• Control is a Challange

Beamsteering is defined in LTE with 4 cell antennas –it is being extended to 8 in LTE-Advanced



Cell Edge Interference Avoidance Fractional Frequency Reuse – Decrease I in C/I

Yellow – Use all frequencies

Red, Green, Blue – Use some frequencies – different for each

The cell centers are further awayfrom neighbors, get good C/I

The cell edges (red, blue, green) getinterference reduction by frequency clearance



Coordinated Multi-Point - CoMPCo-operative MIMO or Network MIMO

• Requires high bandwidth backhaul

Page 24

Different data from two different cell sitesCombine for one link

Requires lots of wireline network capacity



CoMP simulation by NTT DoCoMoreference: NTT DoCoMo 3GPP R1-091484

10 UE’s per cell

CoMP initiated for C/I = 3 dB, 2 cells only

6 ray typical urban fading model

Random motion

500 meter ISD, 3 cells per node B

10 MHz system bandwidth

Scheduling Algorithm is Proportional Fairness

Page 25

Source: NTT DoCoMo R1-091484



CoMP Cell-edge users and cell throughput with full data buffers

Cell-edge user throughput

Cell Throughput

Single Cell Transmission

0.672 MbpsRef

20.21 MbpsRef

CoMP with 8 RE’s

0.778 Mbps+15.8%

20.20 Mbps0%

CoMP with 12 RE’s

0.769 Mbps+14.4%

19.98 Mbps-1.1%

CoMP with 16 RE’s

0.753 Mbps+12.1%

19.29 Mbps-4.5%

Cell-edge user throughput

Cell Throughput

Single Cell Transmission

0.743 MbpsRef

20.54 MbpsRef

CoMP with 8 RE’s

0.866 Mbps+16.6%

21.13 Mbps+2.9%

CoMP with 12 RE’s

0.854 Mbps+14.9%

20.98 Mbps+2.1%

CoMP with 16 RE’s

0.840 Mbps+13.1%

20.25 Mbps-1.4%

Page 26

2 x 2 MIMO with CoMP 4 x 2 MIMO with CoMP

• Scheduler holds data rate for cell-edge users roughly constant with various channel configurations

• Impact to cell throughput is minimal• Improvement to cell-edge performance modest• Probably not worth the impact to network complexity

RE is Resource Element which is an OFDM sub-Carrier for one symbol




CoMP is more effective with light cell loading

Page 27

0

1

2

3

4

5

8 10 12 14 16 18 20 22Cell throughput (Mbps)

Cel

l-edg

e us

er th

roug

hput

(Mbp

s)

2-by-2fD = 5.55 HzOn/off traffic

Joint transmission (8 REs per RB)Joint transmission (12 REs per RB)Joint transmission (16 REs per RB)Single-cell transmission

0

1

2

3

4

5

6

8 10 12 14 16 18 20 22

Cell throughput (Mbps)C

ell-e

dge

user

thro

ughp

ut (M

bps)

4-by-2fD = 5.55 HzOn/off traffic

Joint transmission (8 REs per RB)Joint transmission (12 REs per RB)Joint transmission (16 REs per RB)Single-cell transmission

2 x 2 MIMO Configuration 4 x 2 MIMO Configurationregion of 1st sim


A drop in Cell Throughput is used a measure of data reduction. 100% ~ 20 MB/s



In-channel relayRF backhaul to improve coverage



Femtocells – Not unique to LTE-Advanced (Rel 9)

Page 29

Preserves network resources:SpectrumBackhaul



Femtocell Attributes

Page 30

Attribute Traditional Cellular FemtocellsInfrastructure cost $10,000 - 100,000 $100 - 200Infrastructure finance

Operator End User

Backhaul Expensive leased T1/E1 lines

Existing broadband internet

Planning Operator End user (no central planning)

Deployment Operator truck roll End user one touchQuality of Service Operator controlled Best EffortControl Operator via O&M Operator via InternetMobility Good/excellent Nomadic/best effortData throughput Limited Excellent



New Uplink structure in LTE-Advanced

How to define channel coding for bandwidth aggregation

How to minimize PAPR

The choice is Clustered DFT-S-OFDM

Not selected were OFDM or N×SC-FDMA



Block diagram for N×SC-FDMA

Page 32

3 parallel data paths for 3 clusters of 20 MHz each

Not used in LTE-AdvancedSource: Motorola R1-083820



Block Diagram for Clustered DFT-S-OFDM

Page 33

The Mapping Function goes to all clusters in parallelSource: Motorola R1-083820



CM comparison of proposed uplink access schemes for 16-QAM

Page 34

0

1

2

3

4

5UL Access Scheme CM Comparison - 16-QAM

Cub

ic M

etric

N=2

N=2

N=5

N=5

OFDMANxSC-FDMAClusteredDFT-S-OFDM

Source: Motorola R1-083820

Cubic Metric (CM) is similar to Peak to Average Power Ratio (PAPR) in dB

N is number of 20 MHz clusters



Conclusions

LTE-Advanced has many important features

Meeting 3 bps/Hz looks impractical

Still lots of smoke and mirrors

Peak data rates are even less meaningful than in earlier standards – How can you get below zero?

Competition for the marketplace is HSPA Plus, then LTE

Softer competition from 1xEV-DO


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