02 bsssig signalling protocols ppt v1
DESCRIPTION
sigTRANSCRIPT
CTXX 2900 /1.0 en 1 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Welcome to
BSSSIGBase Station SubBase Station Sub--system system SignallingSignalling CourseCourse
Trainer’s Slides
CTXX 2900 /1.0 en 2 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
BSSSIGBSSSIG -- Course ContentsCourse Contents• GSM Network Review• BSS Signalling on A, Abis & Air Interface• Signalling Examples - Sign. Flow in MOC, MTC, LUP & HO• Use of Nethawk• Useful BSC/MSC Commands• Successful Call Cases• Failing Call Cases/Troubleshooting
CTXX 2900 /1.0 en 3 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SignallingSignalling is...is......all kinds of information exchange that enables speech or data connections between two or more subscribers. It can be on betweennetwork and subscribers or between different network elements.
Its main tasks in general are:- call control (establishment, supervision & maintenance, release)- control of servicesMobile specific additional tasks are:- subscriber administration- mobility management
• Signalling information is made of sets of standardized messages.• The GSM network uses pre-existent protocols developed for modern telecommunication networks, i.e. CCS7.• The CCS7 used in PSTN networks was redefined in order to fulfill the signalling requirements of mobile networks.
CTXX 2900 /1.0 en 4 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SignallingSignalling in the BSSin the BSS
DX 200
MSCTC
HLROMC
BSC
DX 200
BTS
BTS
BTS
MS
NSS
CCS7
LAPDLAPDm
BSS
NMS NSS
CTXX 2900 /1.0 en 5 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
OSI OSI ReferenceReference ModelModel
application
host A
transmission medium
Communication hardware/software
application
host B
Communication hardware/software
OSI Stack
1 Physical Layer
2 Data Link Layer
3 Network Layer
4 Transport Layer
5 Session Layer
6 Presentation Layer
7 Application Layer
Protocol peer-to-peer
communication
User Part
QoS
Network delivery service (network type dependent)
CTXX 2900 /1.0 en 6 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
GSM GSM SignallingSignalling LayersLayers• The Physical Layer (L1)
Air interface - data transmission at 270.833 kbits/sA/Abis interface - data transmission at 2,048 kbits/s (2Mbps) Data to signals convertion according to the physical medium
• The Link Layer (L2)Air interface – GSM-specific LAPDm protocolAbis interface – LAPD protocolA interface – MTP (CCS7) protocolSegmentation, Error detection/correction, Retransmission
• The Network Layer (L3)Air interface – RR / DTAPAbis interface – BTSM A interface – BSSMAP Channel allocation, transport function, mobility and transaction handling
<< In BSS, << In BSS, applicationsapplications are are often referred as often referred as GSM_L3, GSM_L3, but it is notbut it is not OSI_L3 >>OSI_L3 >>
CTXX 2900 /1.0 en 7 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SignallingSignalling Protocols in GSMProtocols in GSM
CMCMB
SSAP
BSSAP
DTAP
CMCM
SCCPSCCP
MTPMTP
SMS
SS
CC
MMMM
BSSMAPBSSMAP
A Interface (G.703)A Interface (G.703)
BSSMAPBSSMAP
SCCPSCCP
MTPMTP
RRRR
BTSMBTSM
LAPDLAPD
RR’RR’
BTSMBTSM
LAPDLAPD LAPDmLAPDm
Abis Interface (G.703)Abis Interface (G.703) Air InterfaceAir Interface
SMS
SS
CC
MMMM
RRRR
MSC BSC BTS MS
LAPDmLAPDm
GSML3
GSML3
04.08 *
04.80
04.11
04.08
04.08 04.0808.08
08.58
08.56 04.06
08.54 04.04
08.06
08.04
08. 04* ETSI specifications
CTXX 2900 /1.0 en 8 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Module ContentsModule Contents• Introduction to BSS Signalling• CCS7
- MTP- SCCP
• LapD-LapDm
• BTSM• RR• BSSAP
- BSSMAP- DTAP
CTXX 2900 /1.0 en 9 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
CCS7CCS7
CTXX 2900 /1.0 en 10 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Where is CCS7 on A interface?Where is CCS7 on A interface?T S 1 2 3 4 5 6 7 8
0 S Y N C H1 T C H2 T C H3 T C H4 T C H5 T C H6 T C H7 T C H8 T C H9 T C H
1 0 T C H1 1 T C H1 2 T C H1 3 T C H1 4 T C H1 5 T C H1 6 C C S 71 7 T C H1 8 T C H1 9 T C H2 0 T C H2 1 T C H2 2 T C H2 3 T C H2 4 T C H2 5 T C H2 6 T C H2 7 T C H2 8 T C H2 9 T C H3 0 T C H3 1 T C H
•Traffic channels' baud rate is 64 kbit/s
•TCH are located in TS's 1-15 17-31
•TS 16 can be used for CCS7 signalling
CTXX 2900 /1.0 en 11 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
…….and on Ater interface?.and on Ater interface?
CCS7CCS7CCS7
•The traffic channels and signalling channels coming from three (four) different PCMs from the MSC are reallocated in the transcoder
•Traffic channels (16 Kbits/s) form each PCM (30) go to 8 consecutive time slots
•Signalling channels (64 Kbits/s) are allocated in the last time slots of the frame
•One LAPD channel is allocated in TS 1, sub TS 1-2 for communication between TC and BSC
CTXX 2900 /1.0 en 12 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
CCommon ommon CChannel hannel SignallingSignalling nn°°77 –– CCS7CCS7
1 Physical layer
2 Data link layer
3 Network layer
4 Transport layer
5 Session layer
6 Presentation layer
7 Application layer
MTP (levels 1-3)
User Part (level 4)
OSI Reference ModelCCITT Common
Channel SignallingNo 7
CTXX 2900 /1.0 en 13 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTPMTP
CTXX 2900 /1.0 en 14 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
CCS7CCS7--MTPMTP• MTP is the message transfer part. It is responsible for transferring of
signalling messages from one element to another within the samesignalling network. It consists of three sub layers.
SignallingData Link
Network Management
MessageHandling
Signalling Link
LAYER 1
LAYER 2
LAYER 3
CTXX 2900 /1.0 en 15 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
CCS7 CCS7 -- MTPMTPThe three levels of the MTP are:• Level 1 - Signalling Data Link Level
... to access the physical medium (Signalling Link)• Level 2 - Signalling Link Level
... to provide reliable transfer of signalling messages (Signalling Link Set)Creates signalling units:MSU - Message Signalling UnitLSSU - Line Status Signalling UnitFISU - Fill-In Signal Unit
CTXX 2900 /1.0 en 16 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTP Layer 2 Frame FormatsMTP Layer 2 Frame Formats
F CK SIF SIO LI F I B
FSN B I B
BSN F
LI F I B
FSN B I B
BSN F
LI F I B
FSN B I B
BSN F
F CK
F CK
SF
First bit transmitted
First bit transmitted
8 16 8n, n>2 8 2 6 1 7 1 7 8
8 16 8 or 16 2 6 1 7 1 7 8
8 16 2 6 1 7 1 7 8
CK Check Bits SF Status Field F Flag SIF Signalling Information Field LI Length Indicator SIO Service Information Octet FSN Forward Sequence Number BIB Backward Indicator Bits BSN Backward Sequence Number FIB Forward Indicator Bits
(a) Basic format of a message signal unit ( MSU) , Length Indicator (LI) >2
(b) Format of a link status signal unit ( LSSU) , Length Indicator (LI) =1or 2
(c) Format of a fill-in signal unit ( FISU) Length Indicator (LI) =0
MSU
LSSU
FISU
CTXX 2900 /1.0 en 17 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTP Layer 2 Frame (MSU)MTP Layer 2 Frame (MSU)
CK Check BitsF FlagLI Length IndicatorFSN Forward Sequence Number BSN Backward Sequence Number
SIF Signalling Information FieldSIO Service Information OctetBIB Backward Indicator BitsFIB Forward Indicator Bits
F CK SIF SIO LI
F
I
B
FSN
B
I
B
BSN F
First bit
transmitted
8 16 8n, n>2 8 2 6 1 7 1 7 8
CTXX 2900 /1.0 en 18 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Bit StuffingBit Stuffing
• “0111 1110” is the flag to start and end the Signalling Message• Can not be repeated inside the message• The solution is Bit Stuffing.• One the message is created, MTP layer 2 looks for 5 consecutive
“1”• If they are found, one extra “0” is inserted• This extra “0” is removed at the Reception end, before error
check.
CTXX 2900 /1.0 en 19 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTP Message Sequencing ExerciseMTP Message Sequencing Exercise
FIB
FSNBIB
BSN
FIB
FSNBIB
BSN
FIB
FSNBIB
BSN
Exchange A Exchange B
ERROR
Retransmission
FIB
FSNBIB
BSNPositive Ack.
Negative Ack.
1 101 1 120
100 0 121 1
0 101 1 121
101 0 122 1
BIB(B)=FIB(A)BIB(B)=last BIB(B)ERROR
FIB(A)= last FIB(A)RETRANSMISSION
FIB
FSNBIB
BSN
100 1 120 1
?
BIB(B)=FIB(A)FIB(B)=BIB(A)ERROR RESOLVED
CTXX 2900 /1.0 en 20 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTP Message Sequencing ExerciseMTP Message Sequencing Exercise
FIB
FSNBIB
BSN
FIB
FSNBIB
BSN
FIB
FSNBIB
BSN
Exchange A Exchange BLast Seq. # sent : 50Last Seq. # recd. : 100Last FIB/BIB : 1
ERROR
Retransmission
FIB
FSNBIB
BSNPositive Ack.
Negative Ack.
1
2
3
4
Write down the values of BSN, BIB, FSN & FIB at each stage.
CTXX 2900 /1.0 en 21 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTP Layer 2 Frame (LSSU)MTP Layer 2 Frame (LSSU)
F CK SF LIFIB
FSNBIB
BSN F
First bittransmitted
8 16 8 or 16 2 6 1 7 1 7 8
BCA
BCA000 out of alignment001 normal alignment010 emergency alignment011 out of service101 busy
SPARE
• INITIALIZATION (AFTER SWITCH ON)• ALIGNMENT (AFTER A LINK FAILURE)• FLOW CONTROL (LEVEL 2)
LSSU & FISU ARE NOT RETRANSMITTED
CTXX 2900 /1.0 en 22 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
CCS7CCS7 -- MTP ContinuedMTP Continued• Level 3 - Signalling Network Level (Signalling Route Set)
This level has 2 functions:– Message handling - routing of outgoing
messages, distribution of incoming messages (matches OSI layer 3)
– Network management - sending SignallingNetwork Test (SNT) and Signalling Network Management (SNM) messages (functions go beyond OSI layer 3).
L3 uses Signalling Point Code (SPC) to address messages to individual network elements.
L3 uses Service Information Octet (SIO) to address messages to higher level applications.
CTXX 2900 /1.0 en 23 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTP MTP LLayerayer 33
SLS OPC DPC
OPC Originating Point CodeDPC Destination Point CodeSLS Signalling Link Selection
User informationsubfield Label
DCBASubservice
field
DCBAService
indicator(SI)
Signalling Information Field ( SIF)
Service informationoctet(SIO)
First bittransmitted
4 bits 14 bits 14 bits 4bits 4
Routing label
>> Service indicator: SCCP, TUP, ISUP, DUP, SNM, SNT
>> Subservice field: NA0, NA1, INA0, INA1
>> Routing Label: a STP can modify the SLS field, not OPC and DPC.
CTXX 2900 /1.0 en 24 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MESSAGEDISCRIM.
MESSAGEDISTRIB.
MESSAGEROUTING
layer 4 layer 2layer 3
MTPL3 MTPL3 -- SSignallingignalling messagemessage handlinghandlingTHE SIGNALLING MESSAGE HANDLING FUNCTIONS ARE DIVIDED INTO :
• MESSAGE ROUTING• MESSAGE DISCRIMINATION• MESSAGE DISTRIBUTION
MSU inDPC=own SPC
DPC<>own SPC
SIO ?
MSU out
SIF
SIF
CTXX 2900 /1.0 en 25 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTP Message ExampleMTP Message ExampleConn:1 Card:1 TS:25 Subch:0 2016 19:35:50.59 MSU - BSN: 126 (7Eh) BIB: 1 FSN: 7 (07h) FIB: 1 - Signalling Network Test & Maintenance regular - network indicator : national network - data, length : 14, (0Eh) SLTM - SIGNALLING LINK TEST MESSAGE - DPC : 432 (01B0h) OPC : 12600 (3138h) - SLC : 0 (00h) - test pattern length : 8 (8h) 14 15 16 17 18 19 1A 1B Conn :1 Card:1 TS:25 Subch:0 2017 19:35:50.603 MSU - BSN: 7 (07h) BIB: 1 FSN: 127 (7Fh) FIB: 1 - Signalling Network Test & Maintenance regular - network indicator : national network - data, length : 14, (0Eh) SLTA - SIGNALLING LINK TEST ACKNOWLEDGE - DPC : 12600 (3138h) OPC : 432 (01B0h) - SLC : 0 (00h) - test pattern length : 8 (8h) 14 15 16 17 18 19 1A 1B
Conn :1 Card:1 TS:25 Subch:0 2038 19:36:07.732 MSU - BSN: 7 (07h) BIB: 1 FSN: 0 (00h) FIB: 1 - SCCP - network indicator : national network - data, length : 50, (32h)Conn:1 Card:1 TS:25 Subch:0 2039 19:36:07.741 MSU - BSN: 0 (00h) BIB: 1 FSN: 8 (08h) FIB: 1 - SCCP - network indicator : national network - data, length : 13, (0Dh)
SLTM - SIGNALLING LINK TEST MESSAGE - DPC : 432 (01B0h) OPC : 12600 (3138h) - SLC : 0 (00h) - test pattern length : 8 (8h) 14 15 16 17 18 19 1A 1B
Service Indicator :- indicates what type of service provided by the higher layer messages- eg. Sign NW testing, SCCP, TUP..
MTPL2
MTPL3
CTXX 2900 /1.0 en 26 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SCCPSCCP
CTXX 2900 /1.0 en 27 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Protocol Stack inProtocol Stack in GSMGSM
MTP
TUP NUPISUP
SCCP
BSSAPMAP
TCAP
CTXX 2900 /1.0 en 28 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SSignalling ignalling CConnection onnection CControl ontrol PPart art -- SCCPSCCPSCCP provides additional functions to MTP in order to transfer
both call-related and non-call-related (not possible with originalMTP) signalling messages by using connection-oriented and connectionless network services:
• Additional routing functions (OSI layer 3), i.e. SSN, Global Title.
• Logical signalling connection (OSI layer 4). MTP is able to perform only connectionless services. SCCP can provide both Connectionless and Connection-oriented network services.
• Management function (beyond OSI functionality), controlling the availability of sub-systems and broadcasting this information to other nodes in the network.
CTXX 2900 /1.0 en 29 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SCCP SCCP -- servicesservices
• In the connectionless service, all routing information required to route the data to its destination must be contained in each data packet. No logical connection is established between the end nodes.
• Connection-oriented network service is a way to rationalize the exchange of signalling information between two network service users by establishing a logical signalling connection between them. This logical connection is achieved by giving a local reference number to the signalling messages belonging together.
CTXX 2900 /1.0 en 30 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SCCPSCCP network network servicesservices (GSM 08.06)(GSM 08.06)Connection oriented messages include:
• Connection Request (CR)• Connection Confirm (CC)• Data Form (DT1)• Released (RLSD)• Release Complete (RLC)
Connectionless messages include:• Unit Data (UDT)• SCCP Management Messages (by UDT messages)
CTXX 2900 /1.0 en 31 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SLR (A) No. , DLR (B) No.
SLR (B) No. , DLR (A) No.
DLR (B) No.
SLR (B) No. , DLR (A) No.
DLR (A) No.
SLR (A) No.
SCCP CONS SCCP CONS SignallingSignalling
EXCHANGEA
EXCHANGEB
CR
CC
DT1
DT1
RLSD
RLC
SLR No. : Source Local Reference No. DLR No. : Destination Local Reference No.
CTXX 2900 /1.0 en 32 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Calling Address, Called Address
Calling Address, Called Address
Calling Address, Called Address
Calling Address,Called Address
SCCP CLNS SCCP CLNS SignallingSignalling
EXCHANGEA
EXCHANGEB
UDT
UDT
UDT
UDT
Addresses can be SPCs or Global Titles
CTXX 2900 /1.0 en 33 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SCCP SCCP -- structure of messagestructure of message (1)(1)
OPC DPC
First bit transmitted
Label 1000=NA0 0011=SCCP
F CK SIF SIO LIFIB
FSNBIB
BSN FMTP message
SCCPmessage
SLS
4bits 14 bits 14 bits
8n bits
Messagetype8 bits
09=UDT
pointersto data
user data
pointertopara-meters(called)
pointertopara-meters(calling)
pointertodata
calledpartypara-meters
callingpartypara-meters
user data
CTXX 2900 /1.0 en 34 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MTP & SCCP Message ExampleMTP & SCCP Message Example
MTPL2
SCCP
Conn:1 Card:1 TS:25 Subch:0 1944 19:34:50.832 MSU - BSN: 124 (7Ch) BIB: 1 FSN: 117 (75h) FIB: 1 - SCCP - network indicator : national network - data, length : 50, (32h) CR - CONNECTION REQUEST Routing Label - DPC : 12600 (3138h) OPC : 432 (01B0h) - SLC : 12 (0Ch) Source Local Reference - 0C8056h Protocol Class - protocol class : 2h, connection oriented Called Party Address - length 2 (02h) - no global title present - routing based on SSN and MTP routing label - subsystem is BSSAP Calling Party Address - length 4 (04h) - no global title present - routing based on SSN and MTP routing label - point code : 432 (01B0h) - subsystem is BSSAP SCCP User Data - length 27 (1Bh) End of Optional Parameters
Service Indicator : ‘SCCP’
SCCP Message : ‘CONNECTION REQUEST’
CTXX 2900 /1.0 en 35 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
LAPDLAPD
CTXX 2900 /1.0 en 36 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
LinkLink Access Access ProtocolProtocol on Don D--channelchannel --LLapapD (GSM 08.56)D (GSM 08.56)
• LAPD is the layer 2 protocol used on the Abis interface.• The are two different types of LAPD signalling links:OMUSIG:
BSC BTS• download SW, HW database;• download configuration files;• remote session to the Transmission Unit.
BTS BSC• alarms;• upload HW database.
TRXSIG:BSC BTS
• telecom signalling (CM, MM, RR);• network parameters;• Power control
BTS BSC• telecom signalling (CM, MM, RR);• measurements.
CTXX 2900 /1.0 en 37 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
AbisAbis InterfaceInterface (Recommended)(Recommended)TS 1 2 3 4 5 6 7 801 TCH0 TCH1 TCH2 TCH32 TCH4 TCH5 TCH6 TCH73 TCH0 TCH1 TCH2 TCH34 TCH4 TCH5 TCH6 TCH75 TCH0 TCH1 TCH2 TCH36 TCH4 TCH5 TCH6 TCH77 TCH0 TCH1 TCH2 TCH38 TCH4 TCH5 TCH6 TCH79 TCH0 TCH1 TCH2 TCH310 TCH4 TCH5 TCH6 TCH711 TCH0 TCH1 TCH2 TCH312 TCH4 TCH5 TCH6 TCH713 TCH0 TCH1 TCH2 TCH314 TCH4 TCH5 TCH6 TCH715 TCH0 TCH1 TCH2 TCH316 TCH4 TCH5 TCH6 TCH717 TCH0 TCH1 TCH2 TCH318 TCH4 TCH5 TCH6 TCH719 TCH0 TCH1 TCH2 TCH320 TCH4 TCH5 TCH6 TCH721 TCH0 TCH1 TCH2 TCH322 TCH4 TCH5 TCH6 TCH723 TCH0 TCH1 TCH2 TCH324 TCH4 TCH5 TCH6 TCH725 TRXSIG1 OMU1 TRXSIG2 OMU226 TRXSIG3 OMU3 TRXSIG4 OMU427 TRXSIG5 OMU5 TRXSIG6 OMU628 TRXSIG7 OMU7 TRXSIG8 OMU829 TRXSIG9 OMU9 TRXSIG10 OMU1030 TRXSIG11 OMU11 TRXSIG12 OMU1231 XX XX XX XX
TCHs FOR TRX 1
TCHs FOR TRX 2
TCHs FOR TRX 12
SIGNALLING (LAPD)
.
.
.
CTXX 2900 /1.0 en 38 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
LAPD LAPD -- Information(I) FrameInformation(I) Frame
F ADDRESS CONTROL INFO FCS F
SAPI 0 TEI
8 16 bits 16 bits 16 bits 8
C/R 1
N (S) N (R)0 P/F
6 bits 1 bit 1 bit 7 bits 1 bit
1 bit 1 bit7 bits 7 bits
EA EA
SAPI : Service Access Point Identifier C/R : Command/Response EA : Ext. AddressTEI : Terminal Endpoint Identifier P/F : Poll/Final bit FCS:Frame CheksumN(S) : Send Sequence # N(R) : Sequence # of next expected frame
Upto 260 octetsFirst bit transmitted
CTXX 2900 /1.0 en 39 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Types of LTypes of LapapD/LD/LapapDm FramesDm Frames ((11) ) • INFORMATION FRAMES (I-Frames)
… transfer Layer 3 Information messages.
Sequencing is used on these frames - N(S), N(R)
• SUPERVISORY FRAMES (S-Frames)... perform data link supervisory control functions like acknowledging I-frames or requesting retransmission of I-frames.
>> RR (Receive Ready): positive acknowledgement to an I-frame.
>> RNR (Receive Not Ready): used as an Indication to the transmitting side to stop sending more messages because the buffer is full. A timer starts at its receiving.
>> REJ (Reject): negative acknowledgement.
Only N(R) is used for sequencing.
CTXX 2900 /1.0 en 40 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Types of LTypes of LapapD/LD/LapapDm Frames (Dm Frames (22) ) • UNNUMBERED FRAMES (U-Frames)
... provide setting up of acknowledged & unacknowledged mode of Information transfer:
>> SABM (Set Asynchronous Balance Mode): sent to begin acknowledged mode of Information transfer.
>> UI (Unnumbered Information): used for unacknowledged mode Information transfer.
>> DISC (Disconnect): used for termination of acknowledged mode of Information transfer.
>> UA (Unnumbered Acknowledge): used as a response to acknowledge SABM & DISC frames.
Sequencing (N(S), N(R)) is not used in U-Frames.
CTXX 2900 /1.0 en 41 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
LapDLapD FrameFrameFLAG FLAGSAPI C
REATEIE
A CONTROL INFO (opt.) FCS
8 6 1 1 1 8168 or 16* n
PF
PF
0
0 1
N(S) N(R)
N(R)not used
I-frame
S-frame
1 1U-frame
C/R shows if the message is either a command or a response to a command SAPI is the logical address of a group of elementsTEI is used to access an element belonging to a group addressed by SAPIN(R), N(S) (7+7) are the Sequence Numbers: N(S) is the number of theN(S) is the number of the framframe e being sentbeing sent;;
N(R) is the number of the next N(R) is the number of the next expected frameexpected frame..P/F Poll/Final bit
FCS Error detection field.
S
PFM M M = SABM, DISC, UA, UI
* always 8 bits for LapDm
7
S = RR, RNR, REJ
First bit transmitted
CTXX 2900 /1.0 en 42 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Modes of LModes of LapapD/LD/LapapDm transmission in GSMDm transmission in GSM• ACKNOWLEDGED MODE
Sent frames are acknowledged (using N(R) field of a RR frame or I-frame) according to the defined “ ack window” (1...127)
Default window size (LapD): 2 for TRXSIG; 1 for BCFSIGDefault window size (LapDm) : 1
If the expected acknowledgement is lacking, “polling” is used to force it.
• UNACKNOWLEDGED MODENo acknowledgement required for sent frames.
CTXX 2900 /1.0 en 43 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
EExamplesxamples ofof generic generic LLapDapD operationsoperationsA B A AB B
SABM
UA
UA
DISC
INFO,N(S)=0,N(R)=0
INFO,N(S)=0,N(R)=1
INFO,N(S)=1,N(R)=1
RR,N(R)=2
INFO,N(S)=3,N(R)=0
RNR,N(R)=4
RR,N(R)=0,P
RNR,N(R)=4,F
RR,N(R)=0,P
RR,N(R)=4,F
INFO,N(S)=4,N(R)=0
INFO,N(S)=3,N(R)=0
INFO,N(S)=4,N(R)=0
INFO,N(S)=5,N(R)=0
RR,N(R)=4
INFO,N(S)=4,N(R)=0
INFO,N(S)=5,N(R)=0
N.B. There may be differences with GSM specific implementation.
CTXX 2900 /1.0 en 44 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
LAPDm LAPDm (GSM 04.06)(GSM 04.06)• LAPDm is a modified version of LAPD for use over the air
interface.• Frame delineation and the Frame Check Sequence are not
necessary.• The amount of data contained in a single frame is limited to 23
bytes (octets) in BCCH/SDCCH/AGCH/PCH and 21bytes in SACCH.
• A segmentation and reassembly facility is introduced for longer messages.
CTXX 2900 /1.0 en 45 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
LLapapDm FDm Framerame
Address : SAPI 0 for MM, CC, RR; 3 for SMS
information
Control : supervisory
unnumbered
ADDRESS CONTROL L3 INFO
8 bits 8 bits 20(18) octets
LENGTH
8 bits
Fill Bits(00101011)
SDCCH, FACCH(SACCH)
LAYER 3 INFORMATION
8 bits 22 octets
LENGTH Fill Bits (00101011)
BCCH, AGCHPCH
EA
CR SAPI 0 0
0 N(S)
1 0
1 1
P/F N(R)
P/F
P/FS S N(R)
MM M M 0
CTXX 2900 /1.0 en 46 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SSignalling Channels ignalling Channels CCodingoding inin thethe AAirir IInterfacenterface(BCCH,(BCCH, PCH,PCH, AGCH,AGCH, SACCH,SACCH, SDCCH,SDCCH, FACCH)FACCH)
L3 INFO + L2 INFO = 23 OCTECTS = 184 BIT(APPL.) (LAPDm)
224 BIT
BLOCK CODING (FIRE)using g(D) = D40 + D26 + D23 + D17 + D3 + 1
4 TAIL BIT ‘0’
228 BIT
CONVOLUTIONAL CODINGR=1/2 (THE SAME USED FOR SPEECH), with generators: g0(D) = D4 + D3 + 1 ; g1(D) = D4 + D3 + D + 1.
456
114 BIT
114 BIT
114 BIT
114 BIT
4 NORMAL BURSTS(no 2nd level interleaving
procedure is used)
CTXX 2900 /1.0 en 47 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Channel codingChannel coding
Interleaving
Burst Formatting
CipheringModulation
SpeechDigitising andSource Coding
Channel Coding
Block coding
Convolutionalcoding
22.8kbits/s456 bits
CTXX 2900 /1.0 en 48 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Interleaving Interleaving -- 11stst levellevelb1b9
b17
b2b10
b18
b3b11
b19
b4b12
b20
b5b13
b21
b6b14
b22
b7b15
b23
b8b16
b24
b441 b442 b443 b444 b445 b446 b447 b448
b449 b450 b451 b452 b453 b454 b455 b456
8 sub-blocks (SB#1 .. SB#8) of 57 bits
SB#1 SB#2 SB#3 SB#4 SB#5 SB#6 SB#7 SB#8
CTXX 2900 /1.0 en 49 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Burst FormattingBurst FormattingThe information sent in the Air interface is formatted
and packed. Its physical content is called "BURST"
Speech Digitising andSource Coding
Channel Coding
Interleaving
Burst Formatting CipheringModulation
Stealing Flags
3 357 571 126 8.25
TB Encrypted bits Encrypted bitsTraining Seq. TB GP
33.8 kbit/s = 156.25 bits per 4.615 ms
CTXX 2900 /1.0 en 50 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Logical ChannelsLogical ChannelsLOGICAL
CHANNELS
COMMONCHANNELS
DEDICATEDCHANNELS
BROADCASTCHANNELS
FCCH SCH BCCH
COMMONCONTROL
CHANNELS
PCH RACH AGCH
SDCCH SACCH FACCH
DEDICATEDCONTROL
CHANNELS
TCH/FR TCH/HR
TRAFFICCHANNELS
TCH/EFR
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
CTXX 2900 /1.0 en 51 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
r
f s bb b b c fc fc sc c c c cc c c fc fsc c c c cc c c f fc c c c cc c c fs fc c c c cc c cs
r rr r r r rr rr r r r r rr r r rr r r r r r rr r r r r r r r rr r r rr r r r rr r rr
Downlink
Uplink
CHANNELS: f = FCCH b = BCCH r = RACH i = idles = SCH c = CCCH (PCH - AGCH)
51 TDMA frames = 235 ms
i
1 51
CHANNEL CONFIGURATIONSCHANNEL CONFIGURATIONSBCCH/CCCHBCCH/CCCH MultiframeMultiframe
i
1. 8. 9.6. 7.4. 5.2. 3.
r
CTXX 2900 /1.0 en 52 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
CHANNEL CONFIGURATIONSCHANNEL CONFIGURATIONSSDCCH/8SDCCH/8 MultiframeMultiframe
t t tt t t t ft tt t t t t t tt t t tt ft t t t t tt t t t fs s s s ss s s s fs s s s ss
s s ss s s s fs ss s t tt t t ts ft t t t t tt t t t ft t t t tt t t tt ft t t t st s st
Downlink
Uplink
CHANNELS: t = SDCCH/8 s = SACCH/8 i = idle
s
t
51 TDMA frames = 235 ms
s
5. 6. 7. 8.1. 2. 3. 4.
1 51
iii
iii
1. 2. 3. 4.5. 6. 7. 8.
5. 6. 7. 8.1. 2. 3. 4.1. 2. 3. 4.5. 6. 7. 8.
CTXX 2900 /1.0 en 53 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
CHANNEL CONFIGURATIONSCHANNEL CONFIGURATIONSCombined CCCH/SDCCH/4Combined CCCH/SDCCH/4 MultiframeMultiframe
f s bb b b c fc fc sc c c c cc c c fc fs t t t t tt t t f ft t t t tt t t fs fh hh h hh h hs
t t tt r r h fh hh h h hr r rr r r rh fr r r r r rr r r r fr r r r tr t t tr ft t t r tr t tt
Downlink
Uplink
CHANNELS: f = FCCH b = BCCH h = SACCH/4 s = SCHc = CCCH r = RACH t = SDCCH/4 i = idle
51 TDMA frames = 235 ms
t
1 51
1. 2. 3. 4.
i
1. 2.1. 2. 3.3. 4.
1. 2. 3.4. 1. 2.3. 4.
CTXX 2900 /1.0 en 54 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
CHANNEL CONFIGURATIONSCHANNEL CONFIGURATIONSFull Rate Traffic Channel (TCH/FR)Full Rate Traffic Channel (TCH/FR) MultiframeMultiframe
t t tt t t t ft tt t t tt t t tt ft t t tt
Downlink and Uplink
CHANNELS: t = TCH s = SACCH i=idle
ts
26 TDMA frames = 120 ms
0 25
i
CTXX 2900 /1.0 en 55 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Normal BurstNormal BurstStealing Flags
3 357 571 126 8.25
TB Encrypted bits Encrypted bitsTraining Seq. TB GP
Used to carry information on traffic and control channels:
TCH, BCCH, CCCH, SDCCH, SACCH and FACCH
156.25 bits per slot duration 577 µs
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
CTXX 2900 /1.0 en 56 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Frequency Correction BurstFrequency Correction Burst
3 3142 8.25
TB TB GPFixed bits
156.25 bits per slot duration 577 µs
FCCH is used for synchronization of the Mobile Station
It is equivalent to an unmodulated carrier = pure sine wave, the bits being all fixed at "0"s
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
CTXX 2900 /1.0 en 57 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Synchronization BurstSynchronization Burst
3 339 64 8.2539
156.25 bits per slot duration 577 µs
TB TB GPSynchronization seq.Information bits
Information bits
It is used for time synchronization of the Mobile Station
it contains a long synchronization sequence, since the training sequence of the cell is not kown yet.
It contains information about the TDMA frame number, FN
It contains Base Station Identity Code, BSIC
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
CTXX 2900 /1.0 en 58 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Access BurstAccess Burst
8 341 68.2536
156.25 bits per slot duration 577 µs
TB TB Guard PeriodFIXED Synchro. seq.
The Access Burst has a long guard period to cater for burst transmission from a mobile that does not know the timing advance at the first access or after a handover
Encrypted bits
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
Air Interface
CTXX 2900 /1.0 en 59 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
SegmentationSegmentation of of LapDm messagesLapDm messages
LapDm message over 23 octects
1 T
1 T
1 T
0 TFF
0,1 = “more” bits
T = tail bits
F = fill bits
CTXX 2900 /1.0 en 60 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
GSM Application PartsGSM Application Parts• BTSM - used for BTS Management and transporting
high layer messages across the Abis interface.• RR - responsible for management and allocation of
Radio Resources• BSSAP - BSS Applications are divided into 2 parts:
• BSSMAP - BSS Management used for resource allocation assignments, circuit handling, paging, handovers, etc. Also used to transport higher layer messages across the A interface.
• DTAP - the Direct Transfer Application Part is used to carry the transparent messages from Connection Management (CM) and Mobility Management (MM)applications.
CTXX 2900 /1.0 en 61 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
More on DTAPMore on DTAP• MM - Mobility Management is responsible for registration,
identification and authorization of users.
• CM - Connection Management is the highest GSM signallinglayer and provides a direct interface between the network and the user, via:
• CC - Call Control for establishing, maintaining & clearing calls.
• SS - Supplementary Services provide call forwarding, call barring, conference calls etc.
• SMS - Short Message Service allows the subscribers to send and receive text messages of up to 160 characters
CTXX 2900 /1.0 en 62 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
BTSMBTSM Message StructureMessage Structure
F ADDRESS CONTROL FCS F
MD MT CH. NO. LINK ID. ADDITIONAL INFO.
MD MT CH. NO. ADDITIONAL INFO.
MD MT CH. NO. ADDITIONAL INFO.
MD MT ADDITIONAL INFO.
RLLM
CCM
DCM
TRXMMD: Message Discriminator MT: Message TypeAdditional Info. : Information Elements of BTSM or/and L3 Info.
8 16 bits 16 bits 16 bits 8
BTSM MESSAGES
Radio Link Layer Mgmt.
Common Channel Mgmt.
Dedicated Channel Mgmt.
TRX Mgmt.
up to 260 octets
8 bits 8 bits 8 bits 8 bits
LapD INFO
CTXX 2900 /1.0 en 63 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
BTSM Message BTSM Message HeaderHeader
8 7 6 5 4 3 2 1MESSAGE GROUP T
Ext MESSAGE TYPE
Message Discriminator + Message Type
Message Discriminator
Message type
T = Transparent bit “0” non- transparent message“1” transparent message
Message type = (channel activation, etc…) in 08.58
Message group0000001 Radio Link Layer Mangement0000100 Dedicated Channel Management 0000110 Common Channel Management 0001000 TRX management
Ext = extension bit (reserved for future use)
CTXX 2900 /1.0 en 64 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
BTSM Messages (GSM 08.58)BTSM Messages (GSM 08.58)RADIO LINK LAYER (RLLM) DEDICATED CHANNEL (DCM) TRX MANAGEMENT MESSAGESMANAGEMENT MESSAGES MANAGEMENT MESSAGES (TRXM)
Data Request Channel Activation RF Resource IndicationData Indication Channel Activation Ack SACCH FillingError Indication Channel Activation Nack OverloadEstablish Request Connection Fail Error ReportEstablish Confirmation Deactivate SACCHEstablish Indication Encryption CommandRelease Request Handover DetectRelease Confirm Measurement ResultRelease Indication Mode Modify RequestUnit Data Request Mode Modify AckUnit Data Indication Mode Modify Nack
Physical Context RequestCOMMON CHANNEL (CCM) Physical Context ConfirmationMANAGEMENT MESSAGES RF Channel Release
MS Power ControlBCCH Information BS Power ControlCCCH Load Indication Preprocess ConfigureChannel Required Preprocessed Measurement ResultDelete Indication RF Channel release Ack Paging CommandImmediate assignment CommandSMS Broadcast Request
CTXX 2900 /1.0 en 65 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
GSM GSM L3 Message StructureL3 Message Structure
8 7 6 5 4 3 2 1
MESSAGE TYPEN(SD)SProtocol DiscriminatorTI ValueTf CC e MM
8 7 6 5 4 3 2 1
MESSAGE TYPEN(SD)SProtocol DiscriminatorSkip Indicator RR
Skip Indicator = always equal 0000
Protocol discriminator0011 CC 0101 MM (GSM Ph2, no GPRS)0110 RR1000 MM (for GPRS)1010 Session Management (GPRS)
Message type = (setup, immediate assignment,…) in 04.08
Tf = “0” if the sender of message is the side that has initiated the transaction;
TI Value: Transaction Identifier; value indicating the transaction which the message is part of.
S = spare
N(SD) = sequence number
CTXX 2900 /1.0 en 66 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
RRadioadio RResourceesource MManagementanagement (RR)(RR)• The role of radio resource management is to establish and release
stable physical connections between MS and MSC - for instance - for the duration of a call, and to maintain them despite of user movements.
• Its functions are: • initialization (RACH or PGCH);• definition of required service;• measurements;• handover handling;• timing advance and power control management; • handling of logical channels on physical channels (i.e. inserting in
these channels the system information).• The functions of the RR layer are mainly performed by the BSC and MS.
It implements the layer 5 of OSI model (session layer).
CTXX 2900 /1.0 en 67 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
Radio Resource Messages (GSML3) 04.08Radio Resource Messages (GSML3) 04.08RR MESSAGES RR’ MESSAGES
Partial Release Assignment Command Channel requestChannel Release Assignment Failure Ciphering Mode commandPartial Release Complete Ciphering Mode Complete Handover accessChannel Mode Modify Ciphering Mode Command Immediate assignmentRR Status Immediate assignment extended Immediate assignment extended Frequency Redefinition Immediate assignment reject Immediate assignment rejectMeasurement Report Measurement reportClassmark Change Paging request type 1Channel Mode Modify Ack Paging request type 2System information type 1 Paging request type 3System information type 2 Physical informationSystem information type 2bis Synchronisation channel infoSystem information type 3 System information type 1System information type 4 System information type 2System information type 5 System information type 2bisSystem information type 5bis System information type 3System information type 6 System information type 4System information type 7 System information type 5System information type 8 System information type 5bisPaging Response System information type 6Handover Failure System information type 7Assignment Complete System information type 8Handover CommandHandover Complete
CTXX 2900 /1.0 en 68 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
BSS Application Layer (BSSAP)BSS Application Layer (BSSAP)• It is divided in two parts:
• BSSMAP (BSS Management Application Part): it implements the procedures for radio resource managementbetween BSC and MSC. It represents the RR layer in MSC;
• DTAP (Direct Transfer Protocol): it carries messages concerning MM and CM procedures. These messages will pass transparently in the BSS that will change only the layer 2 of these messages.
• The message exchange between MSC and BSC contains a protocol discriminator in order to distinguish between BSSMAP and DTAP messages.
CTXX 2900 /1.0 en 69 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
BSSMAP Messages (GSM 08.08)BSSMAP Messages (GSM 08.08)Assignment Request SAPI n rejectAssignment Complete ResetAssignment Failure Reset ACKHandover Request OverloadHandover Required Trace InvocationHandover Request ACK Reset CircuitHandover Command Reset Circuit ACKHandover Complete BlockHandover Failure Block ACKHandover Performed UnblockHandover Candidate Enquiry Unblock ACKHandover Candidate Response Resource RequestHandover Required Reject Resource IndicationHandover Detect PagingClear Command Cipher Mode CommandClear Complete Classmark UpdateClear Request Cipher Mode CompleteSAPI n Clear Command Queuing IndicationSAPI n Clear Complete Complete L3 Information
CTXX 2900 /1.0 en 70 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MMobilityobility MManagementanagement (MM)(MM)• The two ends of this layer are located in MSC and MS.
It deals with user mobility (i.e. location, paging,...), user authentication and privacy of information exchange on air interface (ciphering).
• It’s possible to identify 3 classes of functions:• MM connected-related procedures: to establish,
maintaining and releasing a MM connection between MS and MSC;
• MM specific procedures: Location Updating, Periodic Location Updating, Implicit Detach and IMSI attach;
• MM common procedures: these procedure can be started when a connection between MS and network has already established. These are: authentication, TMSI reallocations, identification procedures, IMSI detach.
CTXX 2900 /1.0 en 71 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
DTAP Messages (1) DTAP Messages (1) -- GSML3 MM (04.08)GSML3 MM (04.08)
MOBILITY MANAGEMENT MESSAGES (MM)
IMSI Detach Indication Identity responseLocation Update Accept TMSI Reallocation CommandLocation Update Reject TMSI Reallocation CompleteLocation Update Request CM Service AcceptAuthentication Reject CM Service RejectAuthentication Request CM Service RequestAuthentication Response CM Re-Establish RequestIdentity request MM Status
CTXX 2900 /1.0 en 72 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
CConnectiononnection MManagementanagement (CM)(CM)
• It is the highest layer in the GSM implementation of the OSI model. Its functions consist in setting up calls between users at their request, maintaining and releasing these calls.
• It uses MM connections.• It is divided in three category:
• Call control (CC) : routing, analysis of users parameters;• Short message Service (SMS);• Supplementary Service.
CTXX 2900 /1.0 en 73 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
DTAP Messages (2) DTAP Messages (2) -- GSML3 CM (04.08)GSML3 CM (04.08)
CALL CONTROL MESSAGES (CC)Alerting DisconnectCall Proceeding Release CompleteProgress ReleaseSetup Stop DTMFConnect Stop DTMF ACKCall Confirmed Status EnquiryEmergency Setup Start DTMFConnect ACK Start DTMF ACKUser Information Start DTMF RejectModify Reject Congestion ControlModify StatusModify Complete Notify
CTXX 2900 /1.0 en 74 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
DTAP Messages (3) DTAP Messages (3) -- GSML3 CM (04.80)GSML3 CM (04.80)SUPPLEMENTARY SERVICES MESSAGES (SS)
RegisterSS GetDigitsEraseSS GetStringActivateSS UnstructuredNotifySSDeactivateSS ForwardChargeAdviseInterrogateSS NotifySSRegisterPassword ForwardCUG infoGetPassword BuildMTPYProcessUnsructuredSSData HoldMTPYForwardCheckSSIndication RetrieveMTPYProcessSSRequest SplitMTPY
CTXX 2900 /1.0 en 75 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
DTAP Messages (4) DTAP Messages (4) -- GSML3 CM (04.11)GSML3 CM (04.11)
SHORT MESSAGES SERVICE MESSAGES (SMS)SMR (relay) SMC (control)RP_Data CP_DataRP_SMMA CP_AckRP_Ack. CP_ErrorRP_Error
CTXX 2900 /1.0 en 76 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MSC BSC BTS MS
CONN. REQ. (SCCP)
COMPLETEL3 INFO (BSSMAP)
ESTABLISH IND.(BTSM)
L3 SERVICE REQ.(MM)
SABM (LAPDm)
CONNECT. CONF.(SCCP)
L3 SERVICE REQ.(MM)
L3 SERVICE REQ.(MM)
UA (LAPDm)
L3 SERVICE REQ.= CM SERVICE REQUEST (MOC)PAGING RESPONSELOC. UPD. REQ.IMSI DETACH IND.
BSSMAP &DTAP in thesame message!
Typical proceduresTypical procedures –– initial messageinitial message
CTXX 2900 /1.0 en 77 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MSC BSC BTS MS
DT1(SCCP)
DTAP
BTSM - DATA REQ.
DTAPDTAP
LAPDmLAPD – I frameMTP
DT1(SCCP)
DTAP
BTSM - DATA IND.
DTAPDTAP
LAPDmLAPD – I frame
MTP
Typical proceduresTypical procedures –– MSC/MS MSC/MS communicationcommunication
Note: no BSSMAP encapsulating
message is used
CTXX 2900 /1.0 en 78 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
MSC BSC BTS MS
DT1(SCCP)
BSSMAP
BTSM
RRRR
LAPDmLAPDMTP
DT1(SCCP)
BSSMAP
BTSM
RRRR
LAPDmLAPD
MTP
Typical proceduresTypical procedures –– MSC/BSS/MS MSC/BSS/MS communicationcommunication
i.e. Cipher_Mode command (BSSMAP & RR): MSC BSC MSAssignment_Complete (RR & BSSMAP): MS BSC MSC
CTXX 2900 /1.0 en 79 Tarun Sharma 15.04.1999 Copyright Nokia Telecommunications – Restyled by Mario Piuri 12-07-2002
COMMUNICATION PROTOCOLS COMMUNICATION PROTOCOLS BETWEEN PEER ENTITIES: HIGH LAYERSBETWEEN PEER ENTITIES: HIGH LAYERS
MSC BSC BTS MS MSC - BSSMAP - DTAPBSC BSSMAP - BTSM RRBTS - BTSM - RR'MS DTAP RR RR' -