GSM Radio Interface ISSUE2.20

7/27/2019 GSM Radio Interface ISSUE2.20

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www.huawei.com

Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

Um Interface andRadio Channels


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Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page1

Contents

1. Overview

2. Processing of Voice Signal

3. Radio Channel


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Radio Interface

Another MSC

HLR/AUC

SMC

PSTN

ISDN

OMC

MS

Um

MS

A-bis

BSC

A

BTS

MSC/VLR


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Communication management (CM)

Radio resources management (RR)

Mobility and security management

(MM)

Integrated management

TCH0 TCH1 TCH2SACCHTCH23 IDL

Multiframe

Physical link layer (L1)

Data link layer (L2)

Network application layer (L3)

Hierarchical Structure of Um Interface

RACH BCCH AGCH/PCH SDCCH SACCH TCH FACCH

CC, SS, SMS

Use LAPDm Protocol


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Radio Access Technology

Power

Power

Power

FDMA

TDMA

CDMA

TimeFDMA

Frequency

TDMATime

Frequency

CDMA

Frequency

Time

Code


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Contents

1. Overview


3. Radio Channel


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Voice Signal Processing

(A/D)

20 ms

22.8kbit/s

13kbit/s8KHz,13bi

t

33.8kbit/s

Segmentation Speech coding Channel coding

Interleaving Encryption) Burst formatting Modulation

Transmission

Voice


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Analog-Digital Conversion


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Speech Coding

The Enhance Full Rate coding mode is called CELP(Code Excited LinearPredictive Coding)

The Full Rate coding mode is called RPE-LTP(Regular Pulse Excited-Long

Term Prediction).

The Half Rate coding mode is called VCELP(Vector-Sum Excited Linear

Prediction)

13kbit/s260 bits(FR)

112 bits(HR)

244 bits(EFR) 12.2kbit/s

5.6kbit/s

(A/D)

20 ms

8KHz,13bi

t

Segmentation Speech coding

Voice


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Channel Coding

13kbit/s260 bits(FR)

112 bits(HR)

244 bits(EFR) 12.2kbit/s

5.6kbit/s

(A/D)

20 ms

8KHz,13bit

Segmentation Speech coding

Voice

Channel coding

22.8kbit/s456bits(FR/EFR)

228bits(HR) 11.4kbit/s

BlockCoder

1:2

Convolutional

Coder


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1 2 3 4 5 6 7 8 ... ... 452 453 454 455 456

B

8

16.

.

.

456

2

10.

.

.

450

6

14.

.

.

454

1

9.

.

.

449

4

12.

.

.

452

7

15.

.

.

455

3

11.

.

.

451

5

13.

.

.

453

.... ....

B0 B1 B2 B3 B4 B5 B6 B7

{A4,B0} {A5,B1} {A6,B2} {A7,B3} {B4,C0} {B5,C1} {B6,C2} {B7,C3}

First interleaving:

Second interleaving:

Interleaving


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Voice Burst

Tailbit

Tailbit

Guard

periodData

Data Training sequence

57 encrypted bits3

bits8.25 bits26 bits1

3

bits57 encrypted bits 1

(A/D)

20 ms

22.8kbit/s

13kbit/

s8KHz,13bit

33.8kbit/

s

Segmentation Speech coding Channel coding

Interleaving Encryption) Burst formatting Modulation

Transmission

Voice


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Voice Signal Processing

33.8 kbit/s

22.8 kbit/s13 kbit/s

8 kHz

13 bits

Transmitting partReceiving part

Speaker

ReceiverDemodulator

AdaptiveEqualizationDe-ciphering

De-interleavingChannel decodingSpeech decodingD/A-conversion

TransmitterModulator

Burst formattingCiphering

InterleavingChannel codingSpeech codingSegmentation

A/D-conversionMicrophone

13 kbit/s

Transmitting part

Receiving part

TransmitterModulator

Burst formattingCiphering

InterleavingChannel codingD/D-conversion8 kHz8 bits64 kbit/s PCM

ReceiverDemodulator

AdaptiveEqualizationDe-ciphering

De-interleavingChannel Decoding

GSM NetworkMobile equipment


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Transmission delay t

Transmission delay t

TA

The mobile phone should

send the signal in advance!!

Timing Advance (TA)

TA = 0 to 63

1 bit equivalent to 3.7s

TS has 156bit

Max coverage = 35Km


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Frequency Hopping

Frequency

f 0

Frame

f 1

f 2

f 3

f 4

Time


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Prolong battery life andreduce interference

DTX

DTX: Discontinuous Transmission

Shut off the transmission at voice intervals;

Only transmit SID frames

The transcoder at the RX terminal produces comfortable noise.

VAD: Voice Activity Detection

Implemented by the transcoder.

Sub & Full

Measurement


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Power Control

Prolong battery life

Reduce network interference

Include both uplink power control and downlink power control

Level and quality are taken into account

BSC or BTS is the final adjudicator

BCCH Carrier is notinvolved in power control.

Time

Signal level

Target level value:e.g. -85 dm


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Contents

1. Overview


3. Radio Channel


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Frequency

200kHz

15/26ms

BP

Slot

Time

Frame and Channel


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32107654321

Physical Channel of Logical Channel

0

different

message

types

Logical channel

Physical Channel

Logical channel

Logical channel

Logical channel

Logical channel

TDMA FRAME

200K

577 ms


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8bit 41 synchronousbits

36 encrypted

bits3bit 68.25bit

Tail bit Tail bit Guard intervalData

Guard interval

3bit 142bit 3bit 8.25bit

Tail bit Tail bitData

3bit 39 encryptedbits

39 encrypted

bits3bit 8.25bit

Tail bit Tail bit Guard intervalDataData

Burst

64 synchronous bits

Access burst (AB): Used in MS initial access

Frequency correction burst (FB): Used in frequency synchronizationbetween MS and BTS

Synchronous burst (SB): Used in timing synchronization between

MS and BTS

63bit TA come from

here


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3bit 142 modulation bits 3bit 8.25bit

Tail bit Tail bit Guard interval

Burst

3bit57 encrypted bits

57 encrypted bits 3bit 8.25bit

Tail bit Tail bit Guard intervalDataData

26bit1 1

Training sequence

Frame stealing flag

Normal burst (NB)

Used to carry the information of the traffic channel and the control channel

except for RACH

Dummy burst (DB)

Used in transmission of filling frames by BTS at timeslots when there is noinformation delivered

Burst rate come from

=156.25/(0.577*8)


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Broadcast control channel

(BCH)Control channelCommon control channel

(CCCH)

Voice channel

(TCH)

FCCH SCH BCCH TCH/FAGCH RACH SDCCH FACCH

SACCH

TCH/HPCH

Common channel

(CCH)

Dedicated channel

(DCH)

Logical channel

Logical Channel Type

GSM900 and DCS1800 have the same logical channel category

(system information)


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FCCH

SCH

BCCH

PCH

AGCH

BCCH

CCCH

Common

Channel

SDCCH

SACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated

Channel

Downlink Logical Channel


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RACH CCCH

Common

channel

SDCCH

SACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated

channel

Uplink Logical Channel


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Use of Logical Channels

FCCH

Allocate signaling channel

Power-on Search for frequency correction burst

Search for synchronous burst

Listen to the system information

Monitor paging message

Send access burst

Set up the call

Allocate voice channel

Conversation

Release the call

Idle mode

SCH

BCCH

PCH

RACH

AGCH

SDCCH

SDCCH

TCH

FACCH

Dedicated mode

Idle mode


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26-frame multi-frame

TCH/F+FACCH/F+SACCH/F (full-rate TCH)

TCH/H+FACCH/H+SACCH/H (half-rate TCH)

51-frames multi-frame

FCCH+SCH+BCCH+CCCH (main BCCH)

FCCH+SCH+BCCH+CCCH+SDCCH/4+SACCH/4 (combined BCCH)

BCCH+CCCH (extended BCCH)

SDCCH/8+SACCH/8 (main SDCCH)

Physical Combination of Logical Channel

TS 2, 4, 6


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Structure of Main BCCH1 multi-frame (51TDMA Frames) 235.38ms Downlink

Group Group1 Group2

Group3,4

(same as

Group2)

Grpup5

Channel F S BX4 CX4 F S CX4 CX4 F S CX4 CX4 I

Frame

Number0 1 2-5 6-9 10 11 12-15 16-19 20-39 40 41 42-45 46-49 50

1 multi-frame (51TDMA Frames) 235.38ms Uplink

Channel R R R R R R R R R R R R R RR R R R R

Frame

Number0 1 2 3 4 5 6 7 8 9 10 11 12 13-46 47 48 49 50

F:FCCH; S:SCH; B:BCCH; C:CCCH; R:RACH; I:IDLE


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Structure of Combined BCCH1 multi-frame (51TDMA Frames) 235.38ms Downlink

Group Group1 Group2 Group3 Group4 Grpup5

Channel F SB

4

C

4F S

C

4

C

4F S

D0

4

D1

4F S

D2

4

D3

4F S

A0

4

A1

4I

Channel F SB

4

C

4F S

C

4

C

4F S

D0

4

D1

4F S

D2

4

D3

4F S

A2

4

A3

4I

Frame

Number0 1 2-5 6-9 10 11

12-

15

16-

1920 21

22-

25

26-

2930 31

32-

35

36-

3940 41

42-

45

46-

4950


Channel D34 R R A24 A34 RR D04 D14 R R D24

Channel D04 R R A04 A14 RR D04 D14 R R D24

Frame

Number0-3 4 5 6-9 10-13 14-36 37-40 41-44 45 46 47-50

F:FCCH; S:SCH; B:BCCH; C:CCCH; D:SDCCH ;A:SACCH; R:RACH; I:IDLE


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Structure of Logical Channel

Combination Frame-Main SDCCH1 multi-frame (51TDMA Frames) 235.38ms Downlink

ChannelD0

4

D1

4

D2

4

D3

4

D4

4

D5

4

D6

4

D7

4

A0

4

A1

4

A2

4

A3

4I I I

ChannelD0

4

D1

4

D2

4

D3

4

D4

4

D5

4

D6

4

D7

4

A4

4

A5

4

A6

4

A7

4I I I

Frame

Number 0-3 4-7 8-11

12-

15

16-

19

20-

23

24-

27

28-

31

32-

35

36-

39

40-

43

44-

47 48 49 50


ChannelA5

4

A6

4

A7

4I I I

D0

4

D1

4

D2

4

D3

4

D4

4

D5

4

D6

4

D7

4

A0

4

Channel A14

A24

A34

I I I D04

D14

D24

D34

D44

D54

D64

D74

A44

Frame

Number0-3 4-7 8-11 12 13 14

15-

18

19-

22

23-

26

27-

30

31-

34

35-

38

39-

42

43-

46

47-

50

D:SDCCH; A:SACCH; I:IDLE


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Structure of Logical Channel

Combination Frame-TCH

T:TCH;A:SACCH; I:IDLE

1 multi-frame (26TDMA Frames) 120ms

Channel T T T T T T TT A T,,,T T T T T T T I

Frame

Number 0 1 2 3 4 5 611 12 1318 19 20 21 22 23 24 25

1 multi-frame (26TDMA Frames) 120ms

Channel T t T t T t Tt A T,,,t T t T t T t a

Frame

Number0 1 2 3 4 5 611 12 1318 19 20 21 22 23 24 25

Case of one full rate TCH

Case of two half rate TCHs

DTX

Frame 52nd

to 59th


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0 1 2 32044

2045 2046 2047

0 1 2 3 48 49 5047

0 1 24 25

0 1 24 25 1 49 500

0 1 4 5 762 3

TB

3

TB

3

GP

8.25TB: Tail bitTB

3TB3

GP8.25

GP: Guard periodTB3

TB3

GP8.25

TB3

TB3

GP 68.25

58 information bits26 training

sequences58 information bits

Constant bit 142

Information bit 39 Extended training sequence 64 Information bit 39

Synchronous sequence 41 Information bit 36

Normal burst (NB)

Frequency correction burst (FB)Synchronous burst (SB)

Access burst (AB)

1 hyper frame=2048 super-frames=2715648TDMA frames (3 hours, 28 minutes, 53 seconds and 760 milliseconds)

1 super-frame=1326TDMA frames (6.12 seconds)

1 multiframe=26TDMA frames (120ms) 1 multiframe=51TDMA frames (3060/13ms)

1TDMA frame=8 timeslots (120/26=4.615ms)

1 timeslot=156.25 bit duration (15/26=0.577ms)(1 bit duration: 48/13=3.68us)

BCCHCCCHSDCCH

TCHSACCH/TFACCH

Frame


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PCH RACHAGCH

Downlink CCCH Uplink CCCH

How to determine the total CCCH resources of the cell? How to

allocate AGCH and PCH reasonably?

Configuration of Common Control Channel


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Summary

In this course, we have learned:

Processing of Voice Signal

Radio Channel in Um Interface

Key Technical in Um Interface


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Documents

GSM Radio Interface ISSUE2.20