Download - GSM Coding Scheme
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GSM Coding SchemeGSM Coding Scheme
MOBILE DIVISIONMOBILE DIVISION
ZTE CORPORATIONZTE CORPORATION
Oct, 2004Oct, 2004
Copyright 2003, ZTE CORPORATION
GSM Voice ServiceGSM Voice Service
GSM Packet ServiceGSM Packet Service
AgendaAgenda
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Voice service of GSMVoice service of GSM
FRFR
Full Rate Full Rate speech/channelspeech/channel
EFREFR
Enhanced Enhanced Full RateFull Rate
HRHR
Half Rate Half Rate speech/channelspeech/channel
AMRAMR
Adaptive Muti-Rate Adaptive Muti-Rate speechspeech
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Voice service flow of GSMVoice service flow of GSM
MSCBTS BSCMS
Um 22.8kbps/11.4kbps
A interface A-law 64kbps
Abis interface 16kbps/8
kVoice Code(TC)
Channel Code(CCU)
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Voice ServiceVoice Service
Sampling frequency
8KHz(0 ~ 3400Hz voice)
Speech frame: 20ms
8KHz×20ms=160
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Compare with PSTN and PHSCompare with PSTN and PHS
PSTN
PCM: 64kbps (A-law or µ-law), MOS = 4.3
PHS ( PCS )
ADPCM: 32kbps, MOS = 4.3
GSM
<16kbps. MOS<4.1
Specific codec algorithm shall be adopted.
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FR(Full Rate)FR(Full Rate)
Algorithm: RPE-LTP-LPC
Data rate after encoding: 13kbps
Quality of data after encoding: MOS = 3.8
LPC LTP RPE13kbps64kbps
FR encoding
encoding
decoding
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EFR(Enhanced Full Rate)EFR(Enhanced Full Rate)
Algorithm: ACELP
Data rate after encoding: 12.2kbps
Quality of data after encoding: MOS = 4.1
LPC LTP ACE12.2kbps64kbps
EFR encoding
encoding
decoding
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HR(Half Rate)HR(Half Rate)
LPC LTP VSE5.6kbps64kbps
HR encoding
encoding
decoding
Algorithm: VSELP
Data rate after encoding: 5.6kbps
Quality of data after encoding: MOS = 3.7
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AMR(Adaptive Multi-Rate)AMR(Adaptive Multi-Rate)
LPC LTP MR-ACEAMR64kbps
HR encoding
encoding
decoding
Algorithm: MR-ACELP
Data rate after encoding: 4.75 kbps - 12.2kbps
Quality of data after encoding: MOS = 3.7
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0 4.75 kbps 1 5.15 kbps 2 5.90 kbps 3 6.70 kbps4 7.40 kbps5 7.95 kbps 6 10.2 kbps 7 12.2 kbps (GSM EFR)
AMR(Adaptive Multi-Rate)AMR(Adaptive Multi-Rate)
1. Select proper encoding rate adaptively according to
state report of different channel.
2. Be prepared for transition from 2G to 3G.
3. Changeable data data rate is suitable for packet
transmission such as IP transmission.
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Voice decode modelVoice decode model
A(z)1 s(n)^
+
v(n)
c(n)
u(n)
g c
fixedcodebook
adaptive codebook g p
LP synthesis
post-filterings'(n)^
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Comparison of GSM voice code schemesComparison of GSM voice code schemes
encodingscheme
rate (kbps) Quality(MOS) complexitycost
/channeltransit to
3GFR 13 normal(3.8) lowest lowest No
EFR 12.2 high(4.1) high high No
HR 5.6lower(3.7), declining very
rapidly as environmentgoes bad
higher highest No
AMR 4.75~12.2
Aim at 3G. The bestquality for both networkand subscriber. MOS isbetween HR and EFR.
highest highest Yes
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Protection of voice channel encoding
Um:
FR: 22.8kbps
HR: 11.4kbps
Protect bit:
FR : 13 + 9.8 = 22.8 (kbps)
EFR : 12.2 + 10.6 = 22.8 (kbps)
HR : 5.6 + 5.8 = 11.4(kbps)
AMR : ??+??= 22.8 (kbps)
??+??= 11.4 (kbps)
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Voice Quality of HRVoice Quality of HR
Encodingscheme
Algorithmbit rate after
encoding (bps)bit rate onAbis (bps)
MOS
FR RPE-LTP-LPC 13k 16k 3.8EFR ACELP 12.2k 16k 4.1HR VSELP 5.6k 8k/16k 3.7
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Abis interface unit and TRAU shall be upgraded to support HR
HRHR
BBTTSS
BBSSCC
TTCCUU
BBSSCC
RRMMMM
OMC-R server OMC-R Client
LAN
BBSSCC
SSCCMM
BBTTSS
BBSSCC
TTCCUU
BBSSCC
TTCCUU
BBSSCC
RRMMMM
BBSSCC
RRMMMM
OMC-R server OMC-R Client
LAN
BBSSCC
SSCCMM
BBSSCC
SSCCMM
Processing of HR frame
Processing of HR configuration, PM and service flow
Uplink: 8k to 16k conversionDownlink: 16k to 8k conversion
Uplink: HR frame decoded to 64k voice channelDownlink: 64k voice channel encoded to 16k HR channel
16k HR channel16k HR channel A interface 64k voice channel
Abis interface 8k HR channelSupport HR
handset service
Processing of HR configuration, PM and related OMM
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1. Load of MP
a) Load of MP increase by about 1 % . The structure of database is more complicated and the quantity of PM counter increase.
2. RF parameters
a) Network congestion will be improved
b) No impact to the coverage
c) Quality of voice is lower
Effect of HR to the systemEffect of HR to the system
Copyright 2003, ZTE CORPORATION
GSM Voice ServiceGSM Voice Service
GSM Packet ServiceGSM Packet Service
AgendaAgenda
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GPRSGPRS
(General Packet Radio Services)(General Packet Radio Services)
Scheme Code
Rate
USF
bits
Pre-
coded
USF
bits
Radio
Block
(excl.
USF
and BCS)
BCS Tail
bits
Coded
bits
Punctured
bits
Data
Rate
(kbps)
CS-1 1/2 3 3 181 40 4 456 0 9.05
CS-2 ~2/3 3 6 268 16 4 588 132 13.4
CS-3 ~3/4 3 6 312 16 4 676 220 15.6
CS-4 1 3 12 428 16 0 456 0 21.4
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Enhanced GSM Phase II+, higher bit rate.
The max bit rate of GSM data service is 14.4kbps, and the max bit rate of EDGE can reach up to 48kbps.
EDGE is a good alternative of UMTS 3G.
EDGEEDGE
((Enhanced Data rate for GSM EvolutionEnhanced Data rate for GSM Evolution ) )
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EDGE EDGE channel encoding schemechannel encoding scheme
凿孔方案( P1-P3 )的设计要遵循一定的规则和流程,比如每个 MCS 可有多个凿孔方
Scheme ModulateMax bit rate
(kbps)code rate
rate ofhead code
Pics(20ms)
Sector
MCS-9 59. 2 1 0. 36 2 AMCS-8 59. 2 0. 92 0. 36 2 AMCS-7 44. 8 0. 76 0. 36 2 BMCS-6 29. 6 0. 49 1/3 1 AMCS-5 22. 4 0. 37 1/3 1 BMCS-4 17. 6 1 0. 51 1 CMCS-3 14. 8 0. 85 0. 51 1 AMCS-2 11. 2 0. 66 0. 51 1 BMCS-1 8. 8 0. 53 0. 51 1 C
GMSK
8PSK