OMF000001 Um Interface and Radio Channels ISSUE1.4

OMF000001 Um interface and radio channels ISSUE1.4

OMF000001 Um interface and radio channels ISSUE1.4

Wireless Training Department

ContentsContents

Overview

Processing of voice signal

Radio channel

Radio InterfaceRadio Interface

Another MSC

HLR/AUC/LR

SMC

PSTN ISDN

OMC

MS

Um interface

MS

Um

Um

A-bisinterface

BSCMSC/VLR

A interface

MAP interface

BTS

MSC

Communication management (CM)Communication management (CM)

Radio resources management (RR)Radio resources management (RR)

Mobility and security management (MM)

Mobility and security management (MM)

Integrated managementIntegrated management

TCH0 TCH1 TCH2 SACCH TCH23 IDLTCH0 TCH1 TCH2 SACCH TCH23 IDL

MultiframePhysical link layer (L1)

Data link layer (L2)

Network application layer (L3)

Hierarchical Structure of Um InterfaceHierarchical Structure of Um Interface

RACH BCCH AGCH/PCH SDCCH SACCH TCH FACCH

Radio Access TechnologyRadio Access Technology

TimeFDMA

Frequency

TDMATime

Frequency

CDMA

Frequency

Time

Code

ContentsContents

Overview

Processing of voice signal

Radio channel

Voice A/DA/D8KHz13bit Speech

codingSpeech coding

SegmentationSegmentation

20ms13kbit/s

Channel codingChannel coding

InterleavingInterleaving Burst formattingBurst formattingEncryptionEncryption

22.8kbit/s

ModulationModulation33.8kbit/s

Transmission

Voice Signal ProcessingVoice Signal Processing

Speech CodingSpeech Coding

z 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 sub-frames; the duration of every sub-frame is

5ms; and the pure bit rate is 13kbit/s.

Block coderBlock coder

Excited coder

Excited coder

50bit

+3 *2+4

132bit

78bit

456bit

Channel CodingChannel Coding

1 2 3 4 5 6 7 8 ... ... 452 453 454 455 4561 2 3 4 5 6 7 8 ... ... 452 453 454 455 456

B

816...

456

816...

456

210...

450

210...

450

614...

454

614...

454

19...

449

19...

449

412...

452

412...

452

715...

455

715...

455

311...

451

311...

451

513...

453

513...

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

First interleaving:

Second interleaving:

InterleavingInterleaving

InterleavingInterleaving

1 2 3 4 5 6 7 8 ... ... 452 453 454 455 4561 2 3 4 5 6 7 8 ... ... 452 453 454 455 456

B

816...

456

816...

456

210...

450

210...

450

614...

454

614...

454

19...

449

19...

449

412...

452

412...

452

715...

455

715...

455

311...

451

311...

451

513...

453

513...

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

First interleaving:

Second interleaving:

33 5757 11 2626 11 5757 33

Voice BurstVoice Burst

Transmission delay t


TA

The mobile phone shouldsend the signal in advance!!

Timing Advance (TA)Timing Advance (TA)

Timing Advance (TA)Timing Advance (TA)



TA

The mobile phone shouldsend the signal in advance!!

Frequency HoppingFrequency Hopping

Frequency

f 0

Frame

f 1

f 2

f 3

f 4

Time

Prolong battery life and reduce interference

DTXDTX

z DTX: Discontinuous Transmission

Shut off the transmission at voice intervals;

Only transmit SID frames

The transcoder at the RX terminal produces comfortable noise.

z VAD: Voice Activity Detection

Implemented by the transcoder.

DTXDTX

z DTX: Discontinuous Transmission

Shut off the transmission at voice intervals;

Only transmit SID frames

The transcoder at the RX terminal produces comfortable noise.

z VAD: Voice Activity Detection

Implemented by the transcoder.

Prolong battery life and reduce interference

Power ControlPower Control

z Prolong battery life

z Reduce network interference

z Include both uplink power control and downlink power control

z Level and quality are taken into account

z BSC is the final adjudicator

BCCH Carrier is not involved in power control.

Time

Signal level

Target level value:e.g. -85 dm

ContentsContents

Overview

Processing process of voice channel

Radio channel

Frequency

200kHz

BP

15/26ms Slit

Time

Frame and ChannelFrame and Channel

0 1 2 3 2044 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

TB3

TB3

GP8.25 TB: Tail bit

TB3

TB3

GP8.25

GP: Guard periodTB3

TB3

GP8.25

TB3

TB3 GP 68.25

58 information bits 26 training sequences 58 information bits

Constant bit 142

Information bit 39 Extended training sequence 64Information 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

FrameFrame

FrameFrame

0 1 2 3 2044 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

TB3

TB3

GP8.25 TB: Tail bit

TB3

TB3

GP8.25

GP: Guard periodTB3

TB3

GP8.25

TB3

TB3 GP 68.25

58 information bits 26 training sequences 58 information bits

Constant bit 142

Information bit 39 Extended training sequence 64Information 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

8bit 41 synchronous bits36 encrypted

bits 3bit 68.25bit

Tail bit Tail bit Guard intervalData

Access burst (AB): Used in MS initial access

Guard interval

3bit 142bit 3bit 8.25bit

Tail bit Tail bitData

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

3bit 39 encrypted bits

39 encrypted bits 3bit 8.25bit

Tail bit Tail bit Guard intervalDataData

64 synchronous bits

Synchronous burst (SB): Used in timing synchronization between MS and BTS

BurstBurst

3bit 142 modulation bits 3bit 8.25bit

Tail bit Tail bit Guard interval

Dummy burst (DB): Used in transmission of filling frames by BTS at timeslots when there is no information delivered

BurstBurst

3bit 57 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

Broadcast control channel (BCCH) Control channel

Common control channel (CCCH)

Voice channel(TCH)

FCH SCH BCCH(system information)

TCH/FAGCH RACH SDCCH FACCH

SACCH

TCH/H

TCH/9.6FTCH/ 4.8F, HTCH/ 2.4F, H

PCH

Common channel (CCH)

Dedicated channel (DCH)

Logical channel

Logical Channel TypeLogical Channel Type

z GSM900 and DCS1800 have the same logical channel

category

FCCHSCHBCCH

PCHAGCH

BCCH

CCCH

CommonChannel

SDCCHSACCHFACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated Channel

Downlink Logical ChannelDownlink Logical Channel

Downlink Logical ChannelDownlink Logical Channel

FCCHSCHBCCH

PCHAGCH

BCCH

CCCH

CommonChannel

SDCCHSACCHFACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated Channel

RACH CCCH

Common channel

SDCCH

SACCHFACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated channel

Uplink Logical ChannelUplink Logical Channel

Uplink Logical ChannelUplink Logical Channel

RACH CCCH

Common channel

SDCCH

SACCHFACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated channel

Use of Logical ChannelsUse of Logical Channels

Search for frequency correction burst

Search for synchronization sequence

Read system information

Listen paging message

Send access burst

Wait for signaling channel allocation

Call setup

Assign traffic channel

Conversation

Call release

FCCHSCHBCCH

PCHRACHAGCH

SDCCHSDCCHTCHFACCH

idle mode

off state

dedicatedmode

idle mode

26-frame multiframeTCH/F+FACCH/F+SACCH/TF (full-rate TCH)

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

51-frames multiframeFCCH+SCH+BCCH+CCCH (main BCCH)

FCCH+SCH+BCCH+CCCH+SDCCH/4+SACCH/C4 (combined

BCCH)

BCCH+CCCH (extended BCCH)

SDCCH/8+SACCH/C8 (main SDCCH)

Physical Combination of Logical ChannelPhysical Combination of Logical Channel

Structure of Logical Channel Combination Frame-Main BCCH

Structure of Logical Channel Combination Frame-Main BCCH

5046-4942-45414020-3916-1912-1511106-92-510Frame

Number

ICX4CX4SFCX4CX4SFCX4BX4SFChannel

Grpup5Group3,4 (same as Group2)

Group2Group1Group

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

5049484713-461211109876543210Frame

Number

RRRRRRRRRRRRRRRRRRRChannel

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

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

Structure of Logical Channel Combination Frame-Combined BCCH

Structure of Logical Channel Combination Frame-Combined BCCH

5046-49

42-45

414036-39

32-35

313026-29

22-25

212016-19

12-15

11106-92-510Frame

Number

IA3

4

A2

4

SFD3

4

D2

4

SFD1

4

D0

4

SFC

4

C

4

SFC

4

B

4

SFChannel

IA1

4

A0

4

SFD3

4

D2

4

SFD1

4

D0

4

SFC

4

C

4

SFC

4

B

4

SFChannel

Grpup5Group4Group3Group2Group1Group


47-50464541-4437-4014-3610-136-9540-3Frame

Number

D24RRD14D04RRA14A04RRD04Channel

D24RRD14D04RRA34A24RRD34Channel



Structure of Logical Channel Combination Frame-Main SDCCH

Structure of Logical Channel Combination Frame-Main SDCCH

50494844-4740-4336-3932-3528-3124-2720-2316-1912-158-114-70-3Frame

Number

IIIA7

4A6

4A5

4A4

4D7

4D6

4D5

4D4

4D3

4D2

4D1

4D0

4Channel

IIIA3

4A2

4A1

4A0

4D7

4D6

4D5

4D4

4D3

4D2

4D1

4D0

4Channel


47-5043-4639-4235-3831-3427-30

23-2619-22

15-18

1413128-114-70-3Frame

Number

A44

D74

D64

D54

D44

D34

D24

D14

D04

IIIA3

4A2

4A14Channel

A04

D74

D64

D54

D44

D34

D24

D14

D04

IIIA7

4A6

4A54Channel



Structure of Logical Channel Combination Frame-TCH

Structure of Logical Channel Combination Frame-TCH

T:TCH; I:IDLE

252423222110209876543210Frame Number

ITTTTTTTTTTTTTTTTChannel

1 multi-frame (26TDMA Frames) 120ms

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 ChannelConfiguration of Common Control Channel

CCCH GroupingCCCH Grouping

z The GSM system supports various kinds of channel

combinations (GPRS not taken into account), in which the

main BCCH, extended BCCH, combined BCCH, and the

BCCH+CBCH combination contain the CCCH, i.e. all of the

four combinations support the MS access. The MS are

distributed to different CCCH groups based on this fact.

CCCH GroupingCCCH Grouping

z The GSM specifies that the CCCH can be mapped to

timeslots 0, 2, 4 and 6 but the extended BCCH combination

can only be mapped to timeslots 2, 4 and 6 because it does

not contain FCCH and SCH. Therefore, all MS synchronize

with the base station at timeslot 0 and access the network via

different CCCH.

Paging GroupPaging Group

z The GSM system supports a maximum of 99=81 paging groups. the MS can be divided into 81 sub-groups at most

from the opinion of the paging group. No matter what

combination mode is adopted, the number of blocks used for

paging in every 51 multi-frame does not exceed 9. The system

enables the 51 multi-frame to cycle again , with a quantity of

BS-PA-MFRAMS (number of frames of the same paging) of

51 multi-frames as a period.

Paging GroupPaging Group

z In GSM terms, the paging block in any 51 multiframe is called

a paging super-group. Therefore, the number of paging super-

frames in the system is the number of frames of the same

paging. The number of paging groups in each super-group is

9 or 3 number of access granted reserved blocks.

Calculation of CCCH and Paging GroupCalculation of CCCH and Paging Group

z CCCH group number of MS=[(IMSI mod 1000) mod

(BS_CC_CHANS x N)] div N

z Paging group number of MS=[(IMSI mod 1000) mod

(BS_CC_CHANS x N)] mod N

In the formula:

N = Number of paging groups x BS-PA-MFRAMS

IMSI = IMSI number of the mobile phone

mod = Modulo calculation

div = Divide exactly

QuestionsQuestions

z Whats the rate of voice coding ?

z What are the advantages of

discontinuous transmission (DTX)?

z What types of logical channels are

there?

Documents

OMF000001 Um Interface and Radio Channels ISSUE1.4