Edge 4

EDGE

Channel Coding for EGPRS

Convolutional Codes

Bits outBits in

Systematic rate ½ code with constraint length 7

Bits outBits in

Non-systematic rate ½ code with constraint length 7

•EDGE convolutional code is rate 1/3, non-systematic code with constraint length 7

•Efficient decoder algorithms exist, - Viterby decoder

Punctured Convolutional Codes

1 0 0 1 1 1 0 0 1 0 1 1 0

1 0 0 1 1 1 0 0 1 0 1 1 0

1 0 1 1 0 0 1 0 1 0

-1.2 -0.5 -1.5 -2.0 +1.0 +1.3 +0.3 +1.3 -1.2 +2.2

0.0 0.0 0.0-1.2 -0.5 -1.5 -2.0 +1.0 +1.3 +0.3 +1.3 -1.2 +2.2

From conv.Encoder

Apply puncturing

Transmitted

Received &Demodulated

Depunc-tured

1 0 0 1 1 1 0 0 1 0 1 1 0

EGPRS: Modulation and Coding SchemesScheme Modu-

lationMax. rate

kbpsData

Code rateHeader

code rateFamily

MCS-9 59,2 1,0 A

MCS-8 54,4 0,92 A

MCS-7 44,8 0,76

0,36

B

MCS-6 29,6 / 27,2 0,49 A

MCS-5

8PSK

22,4 0,370,33

B

MCS-4 16,8 1,0 C

MCS-3 14,8 / 13,6 0,80 A

MCS-2 11,2 0,66 B

MCS-1

GMSK

8,4 0,53

0,53

C

Header Data

RLC block

4 bursts

CRC

f1 f2 f3 f4 freq

f1f2f3f4

Frequency Hopping

1MCS-5code rate

0,37

CRCcheckOK

CRCcheckOK

CRCcheckOK

GPRS / EGPRS Block Structure

Header Data CRC

- 2

Header Data CRC

- 3

GPRS / EGPRS Block Structure

Header Data

RLC block

4 bursts

CRC

f1 f2 f3 f4 freq

f1f2f3f4

Frequency Hopping

1

Header Data CRC

- 2

Header Data CRC

- 3MCS-9code rate

1,0

Two RLC Blocks per Radio Block

Header Data

RLC block

CRCMCS-1

:MCS-6

HeaderData

Data

CRC

CRC

Two RLC blocks with one HeaderMCS-7:

MCS-9

EGPRS Link Quality Control (LQC)• Combined Link Adaption (LA) and

Incremental Redundancy (IR) scheme

• Link Adaption: Modulation and coding selected based on link quality measurements MCS-1 to MCS-9

• Incremental Redundancy: Robustness increased for every retransmission through joint decoding

Uplink TBF

Downlink TBF

Link Adaption Principle

Measure DL performance

Report DL per-formance to BSS

DL measurementsChoose MCS for DL

Measure UL performance

Choose MCS for UL

Give UL command to MS

Use UL MCS according to command

UL MCS Command

8-PSK Block Error Rate

C/I dB

10 0

10 -1

10 -2

10 -3

0 5 10 15 20 3025

BLER

TU50 - FH - 8PSK - 900 MHz

MCS-5

MCS-6

MCS-7

MCS-8

MCS-9

EGPRS throughput for different MCSs

Th

rou

ghp

ut

= R

x (

1 -

BL

ER

) k

b/s

C/I dB 0 5 10 15 20 25 30 4035

60

50

30

10

0

40

20

MCS-1

MCS-5

MCS-9

MCS-7

MCS-3

Optimal LA

Channel Quality behaviour

f1 f2 f3 f4 freq

f1f2f3f4

Frequency Hopping

Carrier/Interference ratio

Multipath propagation

Time dispersion

Velocity

120 km/h

Burst 1

BEP est 1

Burst 2

BEP est 2

Burst 3

BEP est 3

Burst 4

BEP est 4

RadioBlock

Link Quality Control MeasurementsBit Error Probability (BEP) estimated on burst level

Variation co-efficient of BEP

C/I, multipath propagation, time dispersion, velocity

Velocity, frequency hopp.

MEAN_BEP & CV_BEP

Block n Block n+1 Block n+2

MEAN_BEP nCV_BEP n

MEAN_BEP n+1CV_BEP n+1

MEAN_BEP n+2CV_BEP n+2

Channel Quality Report

MEAN_BEP_AVCV_BEP_AV

IR Principle - GenerelData

Encoded Data

Low Rate Code - e.g. 1/3

2 st

incr

emen

t

1 sttransmission

1 st

incr

emen

t

Header

Datafield

Block Identity-robustly coded

IR in EGPRS

Convolutional Encoded Data

Rate 1/3 Convolutional code

Data

Transmission # 1

Puncturing pattern 1

Transmission # 2


Soft bits # 1 Soft bits # 2 Soft bits # 3

RLC Block

Transmission # 3


Tra

nsm

itte

rR

ecei

ver

EGPRS: Code RatesScheme Modu-

lationMax. rate

kbpsR1

Code rateR1 + R2

Code rateR1 + R2 + R3

Code rateMCS-9 59,2 1,0 0,5 0,33

MCS-8 54,4 0,92 0,46 0.31 *

MCS-7 44,8 0,76 0,38 0,25 *

MCS-6 29,6 0,49 0,24 * -

MCS-5

8PSK

22,4 0,37 0,19 * -

MCS-4 16,8 1,0 0,5 0,33

MCS-3 14,8 0,85 0,42 0,28 *

MCS-2 11,2 0,66 0,33 -

MCS-1

GMSK

8,4 0,53 0,26 * -

*) indicate that some repetition is made.

IR and LA performance k

b/s

C/I dB 0 5 10 15 20 25 30

60

50

30

10

0

40

20

MCS-9 no IR

MCS-7 no IR

MCS-6 no IR

MCS-5 no IR

MCS-1 no IR

MCS-9 IR

Principle of operation, MCS-6

36 bits 96 bits 1836 bits

USF RLC/MAC CRC FBI E Data 74 octets = 592 bit BCS TB

3 bits 32 bits 612 bits

Rate 1/3 concolutional coding

Burst 1 Burst 2 Burst 3 Burst 4

1392 bit = 348 bit / burst

36 bits 96 bitsSB=4

Puncturing

1256 bitsP1

36 bits 96 bitsSB=4 1256 bitsP2

1256 bitsP2

EGPRS Decoding processData SF

Train.seq.

57 1 26 1 57

DataSF

Datafield

Header

Decide modulation (blind detection):/2 derotation + channel estimation•3/8 derotation + channel estimation•choose best signal =

GMSK or 8-PSK modulation

/2GMSK

3/8 8-PSK

Decide header format (stealing bits)

ReadStealing

bitsDecode header:

•Read MCS and puncturing scheme for data field.•The block identity (TFI) and Uplink

State Flag (USF) is also in the header.

ReadMCS and PS

info

Decode data, possibly together with previous transmissions if IR is used.

Decodedata field•Decide modulation (blind detection)

•Decide header format (stealing bits)

•Decode header (read MCS and PS)

•Decode data, possibly together with

previous transmissions if IR is used

Multiplexing EGPRS & GPRS

GPRSEGPRS

EGPRS 8-PSK Block

EGPRS GMSK Block

GPRS Block

Control Block CS-1 coded

”Old” GPRS terminals can only decode GPRS blocks (CS-1 to CS-4), but the can read USF from EGPRS / GMSK blocks.

PCUBSC

DL

USFUSF USF

max. 360 ms

Control Blocks with information for both GPRS- and EGPRS-terminals are CS1 coded.

Radio Blocks in Downlink

Edge 4

Documents

Transcript of Edge 4