gsm interfaces protocols
TRANSCRIPT
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GSM Interfaces and ProtocolsGSM Interfaces and Protocols
Telecommunications
MSc in Software Development
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IntroductionIntroduction
Communication between the several logical and
physical entities of a GSM PLMN is based on
specified interfaces and associated protocols
Interfaces of radio access part
Radio Interface Um-Interface
BTS-BSC interface Abis-Interface
BSC-MSC interface A-Interface
NSS interfaces
B, C, D, E, F Interfaces
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GSM InterfacesGSM Interfaces
MS
BTS
BSC MSCBTS
BTS
BTS
BTS
BTS
BSCUm
PSTN/ISDN
AAbis
MSC
Gateway
MSC
VLR
VLR
HLR
AUC
EIR
B
E
C
D
F
SMS
Centre
OMC
Radio Subsystem
Base Station Subsystem
(BSS)
Operation Subsystem (OSS)
Network & Switching Subsystem (NSS)
SIM
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GSM ProtocolsGSM Protocols
Radio
LAP-Dm
64 kb/s G.703
LAP-D
MTP 1
MTP 2
MTP 3
SCCP
MTP 1
MTP 2
MTP 3
SCCP
MTP 1
MTP 2
MTP 3
SCCP
MTP 1
MTP 2
MTP 3
SCCP
MTP 1
MTP 2
MTP 3
RIL3 - RR
RIL3 - MM
RIL3 - CM
RSM BSSMAP MAP/E, MAP/G
Distribution Protocol TCAP
MAP/D MAP/C
TUP,
ISUP
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI Layers
MS BTS BSC
Relay
MSC/VLR
Anchor
MSC/VLR HLR/AuCGMSC
SMS Gateway
PSTN/
ISDN
Um Abis A B, E, G C D
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GSM Radio InterfaceGSM Radio Interface
Combination of FDM and TDM
Uplink and downlink have each 25MHz of total
spectrum available
Spectrum divided into 124 carrier frequencies
Carrier spacing is 200kHz
8 time slots per carrier
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MultiplexingMultiplexing
Frequency Slot 0 Slot 1 Slot 2 Slot 7ch 1ch 2ch 3.
.
.
.
.
ch 124
Time1 Frame = 8 timeslotsFrame duration = 4.615 ms
timeslot duration = 0.577 ms
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TDMA Frame StructureTDMA Frame Structure
Each TDMA frame divided into 8 time slots
TDMA frames are grouped into two types of
multiframes
26-frame multiframe for traffic channels
51-frame multiframe for control channels
Multiframes are multiplexed into single superframe
of 6.12sec duration
2048 multiframes are combined into hyperframe
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Channel TypesChannel Types
Physical Channels
defined by carrier frequency/TDMA time slot combination
Logical Channels
two types of logical channels
Traffic Channels (TCH)
Control Channels (CCH)
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Traffic ChannelsTraffic Channels
Traffic channels carry user information
speech
data, FAX
Two types of TCH
full rate channel with 22.8kbps gross bit rate
half rate channel with 11.4kbps gross bit rate
TCH are multiplexed into 26-frame multiframe
structure
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2626--frameframe MultiframeMultiframe
26-frame multiframe
T1 T2 T3 T4 T5 T10
T11
A T12
T21
T22
T23
I
Tn: time frame number n for traffic data.
A: slow associated control channel.
I: idle frame.
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Control ChannelsControl Channels
Control channels carry system control and
synchronisation information
Three categories are defined
Broadcast channel
Common control channel
Dedicated control channel
Almost all control channels exist in the 51-frame
multiframe structure
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5151--frameframe MultiframeMultiframe
DOWNLINK (51 time frames)
F S B B B B C C F S C C C C C C F S C C C C C C C C I
F: frequency correction channel
S: synchronisation channel
B: broadcast control channel
C: common control channel
I: idle frame
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Broadcast ChannelBroadcast Channel
Frequency Correction Channel (FCCH)
Synchronisation Channel (SCH)
Broadcast Control Channel (BCCH)
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Common Control ChannelCommon Control Channel
Paging Channel (PCH)
Random Access Channel (RACH)
Access Grant Channel (AGCH)
Cell Broadcast Channel (CBCH)
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Dedicated Control ChannelDedicated Control Channel
Stand-alone Dedicated Control Channel (SDCCH)
Slow Associated Control Channel (SACCH)
Fast Associated Control Channel (FACCH)
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Burst TypesBurst Types
Normal Burst
Frequency Correction Burst
Synchronisation Burst
Dummy Burst
Access Burst
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Burst TypesBurst Types
Start (3) Encrypted data (58) t raining (26) encrypted data (58) stop (3) Guard period (8.25)
Tail bits 57 bits data + 1 Stealing 57 bits data + 1 Stealing Tail bitsflag flag
Start(3) fixed bits (142) Stop (3) guard period (8.25)
start(3) encrypted data (39) Extended training (64) Encrypted data (39) stop (3) guard period (8.25)
extended start (8) synch. seq. (41) encrypted data (36) Stop (3) extended guard per iod (68.25)
Normal Burst
Frequency Correction Burst Burst
Synchronisation Burst
Access Burst
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Channel CombinationsChannel Combinations
CC1: TCH/F + FACCH/F + SACCH/TF
CC2: TCH/H(0,1) + FACCH/H(0,1) +
SACCH/TH(0,1)
CC3: TCH/H(0) + FACCH/H(0) + SACCH/TH(0) +
TCH/H(1)
CC4: FCCH + SCH + BCCH + CCCH
CC5: FCCH + SCH + BCCH + CCCH +
SDCCH/4(0,1,2,3) + SACCH/C4(0,1,2,3)
CC6: BCCH + CCCH CC7: SDCCH/8 + SACCH/8
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Channel Combination 2Channel Combination 2
T0 T1 T0 T1 T0 T1 T0 T1 T0 T1 T0 T1 A0 T0 T1 T0 T1 T0 T1 T0 T1 T0 T1 T0 T1 A1
T0: TCH/H(0) A0: SACCH/TH(0)
T1: TCH/H(1) A1: SACCH/TH(1) 26-frame multiframe
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Channel Combination 5Channel Combination 5
F: FCCH D0: SDCCH/4(0) A0: SACCH/C4(0) R: RACH
F: FCCH D1: SDCCH/4(1) A1: SACCH/C4(1)
F: FCCH D2: SDCCH/4(2) A2: SACCH/C4(2)
F: FCCH D3: SDCCH/4(3) A3: SACCH/C4(3) 2 x 51-frame multiframe
F S B B B B C C C C F S C C C C C C C C F S D0 D0 D0 D0
D1 D1 D1 D1 F S D2 D2 D2 D2 D3 D3 D3 D3 F S A0 A0 A0 A0 A1 A1 A1 A1 -
F S B B B B C C C C F S C C C C C C C C F S D0 D0 D0 D0
D1 D1 D1 D1 F S D2 D2 D2 D2 D3 D3 D3 D3 F S A2 A2 A2 A2 A3 A3 A3 A3 -
D3 D3 D3 D3 R R A2 A2 A2 A2 A3 A3 A3 A3 R R R R R R R R R R R R
R R R R R R R R R R R D0 D0 D0 D0 D1 D1 D1 D1 R R D2 D2 D2 D2
Uplink
Downlink
D3 D3 D3 D3 R R A0 A0 A0 A0 A1 A1 A1 A1 R R R R R R R R R R R R
R R R R R R R R R R R D0 D0 D0 D0 D1 D1 D1 D1 R R D2 D2 D2 D2
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CC based on Cell LoadCC based on Cell Load
Low capacity cell with one TRX
- TN 0: FCCH + SCH + BCCH + CCCH + SDCCH/4(0,1,2,3) + SACCH/C4(0,1,2,3)- TN1 to TN7: TCH/F + FACCH/F + SACCH/TF
Medium capacity cell with four TRX
- Once (on TN 0): FCCH + SCH + BCCH + CCCH- Twice (on TN2 and TN4): SDCCH/8 +SACCH/8- 29 times: TCH/F + FACCH/F + SACCH/TF
High capacity cell with 12 TRXs
- Once on TN0: FCCH + SCH + BCCH + CCCH- Once on TN2: BCCH + CCCH
- Once on TN4: BCCH + CCCH- Once on TN6: BCCH + CCCH
- 5 times: SDCCH/8 + SACCH/8- 87 times: TCH/F + FACCH/F + SACCH/TF
1. Notice that a BCCH always appears in TN 0 together with the logical channelsSCH and FCCH.
2. Additional combinations CC6 are added when traffic is expected to be heavy.
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Channel CodingChannel Coding
Block Code
Fire Code adds 40 bits redundancy, used on control
channels
Generator polynomial P(X) = (X23 + 1)(X17 + X3 + 1)
Convolutional Code
coder rates of 1/2, 1/3, 1/6, and 244/456
Interleaving
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InterleavingInterleaving
0
8
M
440
448
1
9
M
441
449
2
10
M
442
450
3
11
M
443
451
4
12
M
444
452
5
13
M
445
453
6
14
M
446
454
7
15
M
447
455
0 8 440 448
1 9 441 449
2 10 442 450
3 11 443 451
4 12 444 452
5 13 445 453
6 14 446 454
7 15 447 455
Burst N (even bit)
Burst N+1 (even bit)
Burst N+2 (even bit)
Burst N+3 (even bit)
Burst N+4 (odd bit)
Burst N+5 (odd bit)
Burst N+6 (odd bit)
Burst N+7 (odd bit)
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InterleavingInterleaving
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Coding on Logical ChannelsCoding on Logical Channels
Channel Type Bit/Block
Data+Parity+Tail
Convolutional
Coding Rate
Bit/
Block
Interleaving
depth
TCH/FS 456 8
Class I 182 + 3 + 4 1/2 (378)
Class II 78 + 0 + 0 - (78)
TCH/F9.6 4 * 60 + 0 + 4 244/456 456 19
TCH/F4.8 60 + 0 + 16 1/3 228 19
TCH/H4.8 4 * 60 + 0 + 4 244/456 456 19
TCH/F2.4 72 + 0 + 4 1/6 456 8
TCH/H2.4 72 + 0 + 4 1/3 228 19
FACCHs 184 + 40 + 4 1/2 456 8
SDCCHs, SACCHs 184 + 40 + 4 1/2 456 4
BCCH, AGCH, PCH 184 + 40 + 4 1/2 456 4
RACH 8 + 6 + 4 1/2 36 1
SCH 25 + 10 + 4 1/2 78 1
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ModulationModulation
GMSK
BT = 0.3
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Timing AdvanceTiming Advance
TS 0 TS 1 TS 2 TS 3 TS 4 TS 5
TS 5 TS 6 TS 7
TA
TS 1 TS 2
3 TSs
The actual point in time of the transmission is shifted by the
Timing Advance.
Receivi
Sending
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Signalling Application ProtocolsSignalling Application Protocols
Radio Interface Layer (RIL) Protocols
Radio Resource (RR) Management
Mobility Management (MM)
Call Management (CM)
BSS and NSS Protocols
Common Channel Signalling System #7 (CCS7)
TCAP
GSM MAP
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AAbisbis--InterfaceInterface
Interface between BTS and BSC
Non-standardised interface, manufacturers follow
certain guidelines
Based on transmission of data on a PCM 30 interface
(2.048Mb/s transmission rate partitioned into 32
channels of 64 kb/s each)
Voice compression can pack between 4 and 8 voice
channels into single PCM 30 channel.
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BSS ConfigurationsBSS Configurations
Networking between BTSs and BSCs
Multiplexing of user data
Typical network configurations
Star Configuration
Ring Configuration
Serial Configuration
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Star ConfigurationStar Configuration
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Serial ConfigurationSerial Configuration
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Ring ConfigurationRing Configuration
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MultiplexingMultiplexing -- Star ConfigurationStar Configuration
FAS/NFAS
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Not used
Not used
Partial O&M data
Not used
O&M signalling
TRX 8 signalling
TRX 2 signalling
TRX 6 signalling
TRX 5 signalling
TRX 4 signalling
TRX 3 signalling
TRX 7 signalling
TRX 1 signalling
Not used
Not used
17
18
19
20
21
22
23
24
25
26
27
28
29
3031
TRX 1
TRX 5
TRX 2
TRX 6
TRX 3
TRX 7
TRX 4
TRX 8
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MultiplexingMultiplexing -- Serial ConfigurationSerial Configuration
FAS/NFAS
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
Air 0 Air 1 Air 2 Air 3
Air 4 Air 5 Air 6 Air 7
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Not used
Partial O&M data
BTS4/TRX1 signalling
BTS3/TRX2 signalling
BTS3/TRX1 signalling
BTS2/O&M signalling
BTS2/TRX1 signalling
BTS1/TRX2 signalling
BTS4 O&M signalling
BTS3 O&M signalling
BTS2/TRX2 signalling
BTS1/O&M signalling
BTS1/TRX1 signalling
Transmission Control Information
17
18
19
20
21
22
23
24
25
26
27
28
29
3031
BTS1/TRX1
BTS3/TRX1
BTS1/TRX2
BTS3/TRX2
BTS2/TRX1
BTS4/TRX1
BTS2/TRX2
BTS4/TRX2
BTS4/TRX2 signalling
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Control Signalling on theControl Signalling on the AAbisbis--InterfaceInterface
Layer 1 uses 64kb/s D-channel on E1 line
(G.701/702) protocol
Layer 2 uses the ISDN LAPD protocol
Layer 3 divided into four parts
TRX Management (TRXM)
Common Channel Management (CCM)
Radio Link Management (RLM)
Dedicated Channel Management (DCM)
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AAbisbis--Interface Protocol StackInterface Protocol Stack
D-Channel
LAPD
TRXM
User data (CC, RR, MM)
Layer 1
Higher Layers
CCM RLM DCM
Layer 2
Layer 3
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Layer 2Layer 2 -- LAPDLAPD
GSM adopted basically ISDN layer 2 LAPD as
defined in ITU recommendations Q.920 and Q.921
Uses three frame types based on more general HDLC
Information frame group containing the I-frame
Supervisory frame group containing the RR, RNR, REJ
frames
Unnumbered frame group containing the SABME, DM,
UI, DISC, UA, FRMR, and XID frames
Two protocol options based on window length of 8
and 128 GSM uses mainly the 128 window length option
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LAPD Frame FormatLAPD Frame Format
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Layer 2 AddressingLayer 2 Addressing
LAPD uses three SAPI (0, 62, and 63) to layer 3
SAPI 0 - radio signalling (radio signalling link, RSL)
connection setup, release
SMS and supplementary services messages
SAPI 62 - O&M messages (O&M link, OML)
SAPI 63 - Layer 2 management
SAPI 62 and 63 messages have priority so that during
congestion the network can still be managed
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Layer 3 SignallingLayer 3 Signalling
Layer 3 consists of four parts
TRXM, CCM, DCM, RLM
message transmission and format depends on SAPI
SAPI = 0 for radio link signalling, carries user data from
CC, MM, RR, and also SMS and SS
SAPI = 62, 63 for OMC and layer 2 management.
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Layer 3 RSL Message FormatLayer 3 RSL Message Format
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Example Messages for RLMExample Messages for RLM
ID (Hex) Name Direction Description
01 DATA REQuest BSCBTS Transport container for transparent transfer of
BSSAP data from NSS to MS
02 DATA INDication BTSBSC Transport container for transparent transfer of BSSAP
data from MS to NSS
04 ESTablish REQuest BSCBTS Request for BTS to establish layer 2 connection on
radio interface.
05 ESTablish CONFirm BTSBSC Answer to EST_REQ. Message sent to BSC after
BTS receives an LAPDmUA frame from MS
06 ESTablish INDication BTSBSC Response from BTS on receiving an LAPDmSABM
frame from MS
07 RELease REQuest BSCBTS Request to BTS to release current layer 2 connection.
BTS sends an LAPDmDISC frame to MS.
0A UNIT DATA REQuest BSCBTS Transport frame to send messages sent in LAPDmUI
frames over radio interface
0B UNIT DATA
INDicationBTSBSC Transport frame for messages received in LAPDmUI
frames over radio interface
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Example Messages for CCM and TRXMExample Messages for CCM and TRXM
ID (Hex) Name Direction Description
11 BCCH INFOrmation BSCBTS Transport frame for SYS_INFO messages for
transmission in BCCH on time slot 0
12 CCCH LOAD
INDicationBTSBSC Informs BSC about traffic load on CCCH of radio
interface. Frequency of transmission may be adjusted
by OMC.
13 CHANnel ReQuireD BTSBSC Message sent by BTS on receipt of CHAN_REQ by
MS.
15 PAGing CoMmanD BSCBTS Response of the BSC on receipt of a PAGING
command from MSC. Contains IMSI and/or TMSIand the paging group of called MS
16 IMMediate ASSign
CoMmanDBSCBTS Contains all information for assignment of a SDCCH
on radio interface. Transmitted in response to
receiving a correct CHAN_RQD.
19 RF RESource
INDicationBTSBSC BTS uses this message to periodically inform BSC
about quality and quantity of available resources on
radio interface. Allows BSC to refrain from assigning
channels with poor quality.
1C ERROR REPORT BTSBSC Used when error is detected by TRX and no otherresponse message exists.
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Example Messages for DCMExample Messages for DCM
ID (Hex) Name Direction Description
21 CHANnel ACTivation BSCBTS Message to reserve and activate channels on the radio
interface. Contains accurate description of requestedchannel (half/full rate, DTX on/off, channel type,
etc.)
22 CHANnel ACTivationACKnowledge
BTSBSC BTS acknowledges with this message reception ofCHAN_ACT message and activation of requested
channel.
24 CONNection FAILure BTSBSC Message is sent in case of layer 1 problems on the
radio interface
25 DEACTivate SACCH BSCBTS Requests BTS to stop transmission over the SACCH.
The DEACT_SACCH is part of the release procedure
26 ENCRyptionCoMmanD
BSCBTS Activation of ciphering on the radio interface.Message contains the algorithm A5/X to be used.
27 HANDover DETect BTSBSC HND_DET is used during handover (not for intra-
BTS and intra-BSC handover). After target cell has
received the HND_ACC message it calculates thedistance to MS (TA) and sends result in HND_DET
message to BSC. It also informs MSC about
successful handover as soon as possible to allow for
faster switching of the call.
28 MEASurement RESult BTSBSC Contains the mutual measurement result of the MS
and BTS.
2E RF CHANnel RELease BSCBTS RF_CHAN_REL message is sent to B TS after release
of layer 2 connection to request release of layer 1
connection.
2F MS POWERCONTROL
BSCBTS Message used by BSC to adjust the MS transmitterpower according to current radio conditions
30 BS POWER
CONTROLBSCBTS Message used by BSC to adjust the BTS transmitter
power according to current radio conditions
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Layer 3 O&M SignallingLayer 3 O&M Signalling
Messages depend on individual equipment
manufacturer
Management messages as well as software updates
and file transfer are included in signalling
Message transfer distinguishes between O&M
messages and HMI/MMI messages
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Layer 3 OML Message FormatLayer 3 OML Message Format
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The GSM AThe GSM A--InterfaceInterface
Interface between BSS and MSC
Standardised interface allows mixing of equipment
from different manufacturers
A-Interface at physical level consists of two parts
First part between BSS and TRAU, transmission payload
is still compressed
Second part between TRAU and MSC
A-Interface at higher layers depens on SS7 MTP and
SCCP to carry BSSAP
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Multiplexing on AMultiplexing on A--InterfaceInterface
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AA--Interface Protocol StackInterface Protocol Stack
MTP1-3
SCCP
BSSMAP
DTAP
Layer 1 -3
User data BSSAP
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AA--Interface Message RelationshipsInterface Message Relationships
M
O
B
I
L
E
S
T
A
T
I
ON
B
S
S
M
S
C
Radio
Resource
Management
(RR) BSSMAP
Call Control (CC)
Mobility Mgt. (MM)
DTAP
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Format of BSSAP MessagesFormat of BSSAP Messages
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Example BSSMAP MessagesExample BSSMAP MessagesID (Hex) Name Direction Description
01 ASSignment REQuest MSCBSC Sent from MSC to setup channel on radio interface
and A-interface. BSC selects TCH out of list of
available channels and assigns channel by means ofASS_CMD.
10 HaNDover REQuest MSCBSC If the BSC needs to be changed during handover, this
message is sent by the MSC to the new BSC.
11 HaNDover ReQuireD BSCMSC BSC uses message to request handover from MSC
(only intra-MSC and inter-MSC).
1B HaNDover DETect BSCMSC BSC reacts with this message when it receives a
HND_DET message from the BTS on the Abis-interface.
20 CleaR CoMmanD MSCBSC This message is always used to release the radio
resources to a specific MS.
30 RESET BSCMSC In case of fatal errors with serious data incon-
sistencies between MSC and BSC reset is performed.
RESET message is used to synchronise BSC and
MSC again. The message is also used when the A-interface is originally initialised
32 OVERLOAD BSCMSC Send to MSC in order to indicate overlaod situationin BTS or whole BSS. Possible to specify type of
overload. MSC sends message to indicate processor
overload in the switch.
34 RESet CIRCuit BSCMSC RES_CIRC is used like RESET. However,
RES_CIRC only resets individual time slots on the
A-interface rather than whole trunks.
40 BLOCK BSCMSC Individual traffic channels need sometimes to beblocked for traffic.
50 RESource REQuest MSCBSC MSC requests BSC with this message to provide
updated information on the available radio resources
of a BTS.
52 PAGING MSCBSC In case of a mobile terminating call the MSC sends a
PAGING message to all BSC of a location area.
53 CIPHER MODE
CoMmanDMSCBSC This message is sent in order to start ciphering on the
radio interface.
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GSM Mobile Application PartGSM Mobile Application Part
GSM uses the Mobile Application Part (MAP), a special
application layer signalling protocol at all interfaces in the NSS
MAP uses the SS7 protocol stack for message transmission
between entities in the NSS
MAP sits on top of SS7 TCAP and uses services of TCAPs
structured dialogue for message transmission
In typical applications MAP is often integrated with TCAP
Dialogue between MAP applications starts with BEGIN and
ends with END message
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GSM MAP
MAP and TCAP within SS7MAP and TCAP within SS7
TCAP
SCCP
HLR VLR MSC EIR
Layer 4 - 6
Layer 7
Layer 3
Application Users
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TCAPTCAP
GSM TCAP uses exclusively the connectionless
service of SCCP (protocol classes 0 and 1)
Sending TCAP directly addresses the destination via
the SCCP usually using the destinations global title
(GT) address
In GSM the global title is typically an entities ISDN
number
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Generic communication via TCAPGeneric communication via TCAP
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MAP and its relationship withMAP and its relationship with TCAPsTCAPs
sublayerssublayers
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Coding of Data in TCAPCoding of Data in TCAP
TCAP can encode length indicators from one byte toseveral thousand bytes
Several parameter types are supported and encoding
uses ASN.1 and associated encoding rules
GSM uses the standard TCAP data encoding
structure of three component elements (TLV
convention)
Identifier (Type) T
Length of Value L
Contents (Value) V
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Example Coding of an IMSI in TCAPExample Coding of an IMSI in TCAP
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TCAP messages used in GSMTCAP messages used in GSM
Of the five defined TCAP messages, GSM uses only four
BEGin Opens dialog for one user (MAP) to another user; comprises
originating transaction ID.
END
Specifically ends a dialog process, which was started by BEG;
may contain an optional component part with MAP data
CONtinue
Used between BEG and END to transport data; comprises of both
originating and destination transaction ID; first CON after BEG
confirms that protocol and context are ok.
ABorT
Both TCAP and MAP may use ABT to abort process if error or
processing difficulty; reason may be provided; distinction is madebetween user and provider (U-ABORT and P-ABORT)
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Structure of TCAP messagesStructure of TCAP messages
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Structure of TCAP messagesStructure of TCAP messages
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Structured Dialog in MSCStructured Dialog in MSC--toto--MSCMSC
TransactionTransaction
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Component PortionComponent Portion
The component portion is optional, but if present,
contains user data
INVOKE Component
RETURN RESULT Component
RETURN ERROR Component
REJECT Component
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Example use ofExample use of return resultreturn resultComponentComponent
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Decoding of an END MessageDecoding of an END Message
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Decoded END MessageDecoded END Message
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MAP ServicesMAP Services
MAP used to control communication between
signalling application users such as HLR, VLR, and
MSC
MAP offers the following services
MAP-DELIMITER service
MAP-OPEN service
MAP-CLOSE service
MAP-U-ABORT service
MAP-P-ABORT service
MAP-NOTICE service
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Special MAP ServicesSpecial MAP Services
Special MAP services (local operation codes in GSM
terminology) define the actual type of data exchange
between MAP users
Examples
updateLocation
cancelLocation
registerSS
eraseSS
sendRoutingInfo
prepareHandover
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Direction of MAP ServicesDirection of MAP Services
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Interaction between MAP and TCAPInteraction between MAP and TCAP