LTE Performance

Anders Furuskär and Magnus LundevallWireless Access Networks

Ericsson Research

[anders.furuskar, magnus.lundevall]@ericsson.com

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-252

Outline

About Performance EvaluationsLTE Performance Checkpoint 2

– Delay and latency– Peak data rates– User throughput and spectrum efficiency– VoIP– MBSFN

1.7 bps/Hz/cell – good or bad?– Comparison to upper bound– Supported traffic volumes

Summary

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-253

Performance Evaluations

Scenario, models and assumptions

Pe

rfo

rma

nc

e Ide

ali

ty

Ideal receiver

Practical receiver

Practical deployment

Single-cell

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-254

Control Plane Latency

3GPP control plane latency target reached!

Targets:Idle Active in 100ms

Achievement:Idle Active in 47.5ms + 2xTs1cTarget:

<100ms

Achievement:47.5 + 2xTs1c

UE eNB MME

5. RRC Connection Request

3. TA + Scheduling Grant

2. RACH Preamble

8. Connection Request

10. Connection Setup

12. RRC Connection Setup

15. RRC Connection Complete

9. Processing delay in MME

1. Delay for RACH Scheduling period

4. Processing delay in UE

3. Processing delay in eNB

7. Processing delay in eNB

11. Processing delay in eNB

14. Processing delay in UE

13. H-ARQ Retransmission

16. H-ARQ Retransmission

6. H-ARQ Retransmission

5ms

1ms

1ms

1ms

5ms*

2.5ms

0.3x5ms

4ms

Ts1c (2-15ms)

Ts1c (2-15ms)1.5ms

0.3x5ms

0.3x5ms

4ms

5ms*

3ms

*) together

15ms

Note: FDD figures, similar results for TDD

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-255

User Plane Latency

3GPP user plane latency target reached!

Targets:1-way RAN delay <5ms

Achievement:3.5 + BLER x 5 ms

UE eNB

1 ms

1 ms

HARQ RTT 5 ms

1 ms

1 ms

TTI + framealignment

1.5 ms

1.5 ms

Note: FDD figures, similar results for TDD

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-256

Peak Data Rates

3GPP peak data rate targets reached!

19,6

39,2

81,6

163,2

244,8

326,4

3,5 8,619,9

41,5

63,1

84,7

0

50

100

150

200

250

300

350

1,25 2,5 5 10 15 20Bandwidth [MHz]

Peak

Dat

a R

ates

[Mbp

s]

Downlink 4x4Uplink (64QAM)

Targets:100Mbps DL (2x2)

50Mbps UL

Achievement:326Mbps DL (4x4)

173Mbps DL (2x2)

85Mbps UL (64QAM)

56Mbps UL (16QAM)

1.6Gbps in 100MHz IMT-A capable

DL target 100Mbps

UL target 50Mbps

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-257

Data Rates in LTE Test BedAssumptions:Over-the-air10MHz4x4 MIMO64QAMR ≅ 0.7TTI=0.67ms 16SCs/RB

Achievement102Mbps (non-optimized)

Source:Markus Ringström

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-258

User throughput and Spectrum EfficiencyIntroduction

0 2 4 6 8 100

2

4

6

8

10

12

14

16

18

Sector Throughput [Mbps]

Mea

n U

ser T

hrou

ghpu

t [M

bps]

E-UTRABaselineTarget range (sim)

Downlink results in checkpoint 1 Relation to Checkpoint 1 (2006)

Revised evaluation frameworkSingle high-loaded operating point (10 UE/cell)

Increased realism (feedback delay, measurement errors, overhead)

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-259

User throughput and spectrum efficiencyDownlink

3GPP downlink targets reached!

Targets:Mean user tpt 3-4xCell-edge u tpt 2-3xSpectrum eff. 3-4xBaseline: Basic HSPA R6

Achieved spectrum eff.:LTE 2x2 1.7 bps/Hz/cellLTE 4x2 1.9 bps/Hz/cellLTE 4x4 2.7 bps/Hz/cell

UTRA Baseline E-UTRA 2x2 E-UTRA 4x2 E-UTRA 4x40

1

2

3

Spec

trum

eff.

[bps

/Hz/

cell]

Case1 (ISD=500m)

Target

UTRA Baseline E-UTRA 2x2 E-UTRA 4x2 E-UTRA 4x40

0.1

0.2

0.3

0.4

Cell-

edge

use

r tp

[bps

/Hz]

Target

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-2510

User throughput and spectrum efficiencyUplink

3GPP uplink targets reached!

Targets:Mean user tpt 2-3xCell-edge u tpt 2-3xSpectrum eff. 2-3xBaseline: Basic HSPA R6

Achieved spectrum eff.:LTE 1x2 0.7 bps/Hz/cellLTE 1x4 1.1 bps/Hz/cell

UTRA Baseline E-UTRA 1x2 E-UTRA 1x40

0.5

1

1.5

Spec

trum

eff.

[bps

/Hz/

cell]

Case1 (ISD=500m)

Target

UTRA Baseline E-UTRA 1x2 E-UTRA 1x40

0.02

0.04

0.06

Cell-

edge

use

r tp

[bps

/Hz]

Target

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-2511

VoIP

123289Case3

-293Case2

241317Case1

ULDL

VoIP Capacity (users/sector/5MHz)Deployment

Scenario

Targets:Similar to UTRA CS (60-80 users/5MHz)Internal target200/5MHz

Achievement:240 users (case 1)

3GPP VoIP targets reached!

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-2512

MBSFNMulticast Broadcast Single Frequency Network

Targets:1bps/Hz

Achievement:3bps/Hz(1bps/Hz at 1700m ISD in case 1)

3GPP MBSFN targets reached!

500 1000 1500 2000 2500 3000 3500 40000

0.5

1

1.5

2

2.5

3

3.5

4

ISD [m]

MB

SFN

spe

ctru

m e

ffici

ency

[bps

/Hz]

Case1, 19 sites

Target 1bps/Hz

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-2513

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

Shannon(reuse 1,

RR)

Modulationand Coding

Cyclicprefix

Guardbands

CCHoverhead

Simulation(PF, ideal

CQI)

Simulation(PF, real

CQI)

Spec

trum

Effi

cien

cy [b

ps/H

z/se

ctor

]1.7 bps/Hz/sector – Good or Bad?’Theory’ and Simulation

-10 -5 0 5 10 15 200

20

40

60

80

100

Downlink Wideband C/(I+N) [dB]

C.D

.F. [

%]

LTE approaches theoretical limits!

R/W=2xlog2(1+SINR)

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-2514

1.7 bps/Hz/sector – Good or Bad?3GPP Case 1 (500m ISD) in a City Center Area (20,000km-2)

Sector Capacity1.7x20MHz =34Mbps

Sector Size6·(167·167·√3/2/2)= 0.0725km2

333mSubscriber DensityPop. dens. 20,000km-2

Penetration 90%Market share x30%Sub. dens: 5,400km-2

Subscribers per cell5400·0.0725 = 392

Capacity per subscriber34/392 = 87kbps(average over busy hour, << rate when active)

Assuming 30·10=300 busy hours per month:87·300·3600/8 =12GB/month

4,000 MP3s (3MB each)120,000 RAN1 Tdocs

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-2515

Summary

3GPP checkpoint passed– Peak data rates: DL 326Mbps, UL 86Mbps– Latency: CP ~50ms, UP 3.5ms, HO ~ 12ms– Throughput: DL >3 and UL >2 x UTRA baseline– VoIP: 240 users/5MHz– MBSFN: >3bps/Hz

LTE approaches theoretical limitsLTE can serve lots of traffic

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-2516

Handover Interruption Time

3GPP control plane latency target reached!

Targets:None

Achievement Contention-free:DL: 12msUL: 12msContention-based:DL: 25msUL: 18.5ms

UE SourceeNB

TargeteNB MME/UPE

HO command

HO complete

Ack

U-plane route update

(Path switch)

UL DL

(a) Interruption due to radio L1/L2 layers

(b) Interruption due to UL RRC signalling

(d) Interruption due to path switch(c) Interruption due to

DL RRC signalling

DL synchronisation+

Timing advance+

UL resource request/grant

U-plane active U-plane active

U-plane active U-plane activeForwardeddata only

Measurement report

HO request

HO request confirm

Data forwarding(background process)

......

Data forwarding may continue even after

path switch

UE SourceeNB

TargeteNB MME/UPE

HO command

HO complete

Ack

U-plane route update

(Path switch)

UL DL

(a) Interruption due to radio L1/L2 layers

(b) Interruption due to UL RRC signalling

(d) Interruption due to path switch(c) Interruption due to

DL RRC signalling

DL synchronisation+

Timing advance+

UL resource request/grant

U-plane active U-plane active

U-plane active U-plane activeForwardeddata only

Measurement report

HO request

HO request confirm

Data forwarding(background process)

......

Data forwarding may continue even after

path switch

12ms

6.5ms

6.5ms

(d) Forwarding delay at path switch exceeding (a)+(b) ~0ms

EAB-07:033455 Uen Rev A Ericsson Internal LTE Performance Checkpoint 2007-06-2517