Edge 4
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Transcript of 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
Puncturing pattern 2
Soft bits # 1 Soft bits # 2 Soft bits # 3
RLC Block
Transmission # 3
Puncturing pattern 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