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Structure of Combined BCCH

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Um Interface and Radio Channelswww.huawei.com

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Contents1. Overview 2. Processing of Voice Signal 3. Radio Channel

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page2

Radio InterfaceAnother MSC BTS BSCMSPSTN ISDN

A-bis

A

MSC/VLR

HLR/AUCMS

UmCopyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

OMC

SMC

Page3

Hierarchical Structure of Um InterfaceCommunication management (CM) Network application layer (L3) Mobility and security management (MM) Radio resources management (RR)

Data link layer (L2)

Integrated management

RACH

BCCH

AGCH/PCH

SDCCH

SACCH

TCH

FACCH

Physical link layer (L1)

TCH0 TCH1 TCH2

SACCH

TCH23 IDL

Multiframe

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page4

Radio Access TechnologyTime FDMA Time TDMA

Frequency

Frequency

Time CDMA Code

Frequency

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page5

Radio Access TechnologyTime FDMA Time TDMA

Frequency

Frequency

Time CDMA Code

FrequencyCopyright 2006 Huawei Technologies Co., Ltd. All rights reserved. Page6

Contents1. Overview 2. Processing of Voice Signal 3. Radio Channel

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page7

Voice Signal Processing

20ms Voice A/D 8KHz 13bit Segme ntation 22.8kbit/s Speech coding 13kbit/s Channel coding

33.8kbit/s Interleaving Encryption Burst formatting Modulation Transmission

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page8

Speech Coding

The coding mode is called Regular Pulse Excited-Long Term Prediction (RPE-LTP).

It works as follow: 8KHZ of sampling is performed first, then divided into frames with 20ms; every frame has 4 subframes; the duration of every sub-frame is 5ms; and the pure bit rate is 13kbit/s.

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page9

Channel Coding+3 50bit Block coder Excited coder 456bit *2+4

132bit

78bit

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page10

InterleavingB1 2 3 4 5 6 7 8 ... ... 452 453 454 455 456

First interleaving:

B0 1 9 .

B1 2 10 . . . 450

B2 3 11 . . . 451

B3 4 12 . . . 452

B4 5 13 . . . 453

B5 6 14 . . . 454

B6 7 15 . . . 455

B7 8 16 . . . 456

....

. . 449

....

Second interleaving:

{A4,B0}

{A5,B1}

{A6,B2}

{A7,B3}

{B4,C0}

{B5,C1}

{B6,C2}

{B7,C3}

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page11

InterleavingB1 2 3 4 5 6 7 8 ... ... 452 453 454 455 456

First interleaving:

B0 1 9 .

B1 2 10 . . . 450

B2 3 11 . . . 451

B3 4 12 . . . 452

B4 5 13 . . . 453

B5 6 14 . . . 454

B6 7 15 . . . 455

B7 8 16 . . . 456

....

. . 449

....

Second interleaving:

{A4,B0}

{A5,B1}

{A6,B2}

{A7,B3}

{B4,C0}

{B5,C1}

{B6,C2}

{B7,C3}

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page12

Voice Burst

3

57

1

26

1

57

3

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page13

Timing Advance (TA)The mobile phone should send the signal in advance!!

TATransmission delay t

Transmission delay t

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page14

Timing Advance (TA)The mobile phone should send the signal in advance!!

TATransmission delay t Transmission delay t

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page15

Frequency HoppingFrequency f0 f1 f2 f3 f4 Frame

Time

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page16

Frequency HoppingFrequency

f0 f1 f2 f3 f4 Frame Time

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page17

DTX

DTX: Discontinuous TransmissionShut off the transmission at voice intervals; Only transmit SID frames The transcoder at the RX terminal produces comfortable noise.

VAD: Voice Activity DetectionImplemented by the transcoder.

Prolong battery life and reduce interference

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page18

DTX

DTX: Discontinuous TransmissionShut off the transmission at voice intervals; Only transmit SID frames The transcoder at the RX terminal produces comfortable noise.

VAD: Voice Activity DetectionImplemented by the transcoder.

Prolong battery life and reduce interference

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page19

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 adjudicatorSignal level

BCCH Carrier is not involved in power control.

Target level value: e.g. -85 dm

Time

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page20

Contents1. Overview 2. Processing of Voice Signal 3. Radio Channel

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page21

Frame and ChannelFrequency

200kHz

BP Slit 15/26msCopyright 2006 Huawei Technologies Co., Ltd. All rights reserved. Page22

Time

Logical Channel Type

GSM900 and DCS1800 have the same logical channel categoryLogical channel

Common channel (CCH)

Dedicated channel (DCH)

Broadcast control channel (BCH)

Common control channel (CCCH)

Control channel

Voice channel (TCH)

FCCH

SCH

BCCH PCH (system information)

AGCH

RACH

SDCCH

FACCH

TCH/F

TCH/H

SACCH

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page23

Downlink Logical ChannelFCCH SCH BCCH CCCH PCH AGCH

Common Channel

BCCH

SDCCH

Dedicated Channel

DCCH

SACCH FACCH

TCH

TCH/F TCH/H

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page24

Downlink Logical ChannelFCCH SCH BCCH CCCH PCH AGCH

Common Channel

BCCH

SDCCH

Dedicated Channel

DCCH

SACCH FACCH

TCH

TCH/F TCH/H

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page25

Uplink Logical ChannelCommon channel

RACH

CCCH

SDCCH SACCH FACCH TCH/F TCH/H

DCCH

Dedicated channel

TCH

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page26

Uplink Logical ChannelCommon channel

RACH

CCCH

SDCCH SACCH FACCH TCH/F TCH/H

DCCH

Dedicated channel

TCH

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page27

Use of Logical Channelsoff stateSearch for frequency correction burst Search for synchronization sequence Read system information

FCCH SCH BCCH PCH RACH AGCH SDCCH SDCCH TCH FACCH

idle mode

Listen paging message Send access burst Wait for signaling channel allocation

dedicated mode

Call setup Assign traffic channel Conversation Call release

idle mode

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page28

Burst Access burst (AB): Used in MS initial accessTail bit Data 41 synchronous bits 36 encrypted bits Tail bit Guard interval

8bit

3bit

68.25bit

Frequency correction burst (FB): Used in frequency synchronization between MS and BTSTail bit Data Tail bit Guard interval

3bit

142bit

3bit

8.25bit

Synchronous burst (SB): Used in timing synchronization between MS and BTSTail bit Data 39 encrypted bits 64 synchronous bits Data 39 encrypted bits Tail bit Guard interval

3bit

3bit 8.25bit

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page29

Burst Normal burst (NB): Used to carry the information of the traffic channel and the control channel except for RACHTail bit Data 57 encrypted bits Training sequence Data 57 encrypted bits Tail bit Guard interval

3bit

1 26bit 1Frame stealing flag

3bit

8.25bit

Dummy burst (DB): Used in transmission of filling frames by BTS at timeslots when there is no information deliveredTail bit Tail bit 142 modulation bits Guard interval

3bit

3bit

8.25bit

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page30

Physical Combination of Logical Channel26-frame multi-frameTCH/F+SACCH/F (full-rate TCH) TCH/H+SACCH/H (half-rate TCH)

51-frames multi-frameFCCH+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)

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

Page31

Structure of Main