Speech decoding
Channel decoding
De-interleaving
Burst Formatting
De-ciphering
DemodulationModulation
Ciphering
Burst Formatting
Interleaving
Channel Coding
Speech coding
Radio Interface
Speech Speech
13 Kbps
22.8 Kbps
22.8 Kbps
33.6 Kbps
33.6 Kbps
270.83 Kbps
CM
MM
RR
LAPDm
MS
RR
LAP Dm
Um
LAPD
BTSM
LAPD
Abis
RR
BTSM SCCP
MTP3
BS SAP
BTS BSC
MTP2
SCCP
MTP3
BS SAP
MTP2
CM
MM
MSC
A
Trafficchannels
(TCH)
Signalingchannel
TCH/F: Full-rate Traffic Channel
TCH/H: Half-rate Traffic Channel
FCCH: Frequency correction
SCH: Synchronization
BCCH: Broadcast control
PCH: Paging
AGCH: Access grant
RACH: Random accessSDCCH: Stand-alone dedicated control
SACCH: Slow associated control
FACCH: Fast associated control
Two-way
Base-to-mobile
Two-way
Logical Channel List
BCH
CCCH
DCCH
Logical Channels Characteristics
LogicalChannel
Uplink-only
Downlink-only
Both uplink& downlink
Point-to-pint
Broadcast Dedicated shared
BCCHFCCHSCHRACHPCHAGCHSDCCHSACCHFACCHTCH
√
√√√
√√ √
√
√√√√√√√
√√√
√√√√
√√√√√√
√√
Message name Transmitted by
AUTHENTICATION REQUESTAUTHENTICATION RESPONSEAUTHENTICATION REJECTIDENTITY REQUESTIDENTITY RESPONSETSMI REALLOCATION COMMANDLOCATION UPDATING REQUETLOCATION UPDATING ACCEPTLOCATION UPDATING REJECTIMSI DETACH REQUESTCM SERVICE REQUESTCM RE-ESTABLISHMENT REQUESTMM-STATUS
BaseMobileBaseBaseMobileBaseMobileBaseBaseMobileMobileMobileMobile/Base
Mobility Management Messages
Message nameStarting a call
Transmitted by
SETUPEMERGENCY SETUPCALL PROCEEDING
PROGRESSCALL CONFIRMED
ALERTINGCONNECT
Mobile/basemobile
basebase
mobilemobile/basemobile/base
During a callSTART DTMFSTOP DTMF
MODIFYUSER INFORMATION
Mobilemobile
mobile/basemobile/base
Ending a callDISCONNECT
RELEASERELEASE COMPLET
Mobile/basemobile/basemobile/base
Abnormal conditionsSTATUS
STATUS ENQUIRYCONGESTION CONROL
Mobile/basemobile/basemobile/base
Call management messages
Message name Logical channel Transmitted by
SYNC CHANNEL INFORMATIONSYSTEM INFORMATION (TYPE 1,2,3,4,5)SYSTEM INFORMATION (TYPE 6)CHANNEL REQUESTPAGING REQUEST (TYPE 1,2.3)IMMEDIATE ASSIGNMENTIMMEDIATE ASSIGNMENT EXTENDEDIMMEDIATE ASSIGNMENT REJECTASSIGNMENT COMMANDADDITIONAL ASSIGNMENTPAGING RESPONSEMERSUREMENT REPORTHANDOVER COMMANDHANDOVER ACCESSPHYSICAL INFORMATIONHANDOVER COMPLETECIPHERING MODECHANNEL RELEASEPARTIAL RELEASEFREQUENCY REDEFINITION
CLASSMARK CHANGE
CHANNEL MODE MODIFYRR STATUS
SCHBCCHSACCHRACHPCHAGCHAGCHAGCHFACCHFACCHSDCCHSACCHFACCHTCHFACCHFACCHFACCHFACCHFACCHSACCHFACCHSACCHFACCHFACCHFACCHSACCH
BaseBaseBaseMobileBaseBaseBaseBaseBaseBaseMobileMobileBaseMobileBaseMobileBaseBaseBaseBase
Mobile
BaseMobile/base
Radio Resources Management Messages
Mobilestation
Basestation
Category Logical Channel
SYNC CHANNEL INFORMATION
Carrier sine wave
SYSTEM INFORMATION TYPE3
CHANNEL REQUEST
IMMEDIATE ASSIGNMENT
LOCATION UPDATING REQUEST
AUTHENTICATION REQUEST
CIPHERING MODE COMMAND
CIPHERING MODE ACK
LOCATION UPDATING ACCEPT
TMSI ALLOCATION COMPLETE
AUTHENTICATION RESPONSE
CHANNEL RELEASE
RRM
RRM
RRMRRM
MMMMMM
MMMM
RRMRRM
RRM
FCCH
SCH
BCCH
RACHAGCH
SDCCHSDCCHSDCCHSDCCHSDCCH
SDCCHSDCCHSDCCH
Location-Updating Procedure
Mobilestation
Basestation
Category Logical Channel
RRMRRMRRMRRMRRMRRMMMMMRRMRRMCMCMCMCMRRMRRMCM
CMCMCMRRM
FCCHSCHBCCHPCHRACHAGCHSDCCHSDCCHSDCCHSDCCHSDCCHSDCCHSDCCHSDCCHSDCCHSDCCHSDCCHFACCHTCHTCHFACCHFACCHFACCHFACCH
Carrier sine waveSYNC CHANNEL INFORMATIONSYSTEM INFORMATIONPAGING REQUESTCHANNEL REQUESTIMMEDIATE ASSIGNMENTPAGING RESPONSEAUTHENTICATION REQUESTAUTHENTICATION RESPONSECIPHERING MODECIPHERING MODE ACKSETUPCALL CONFIRMEDALERTINGCONNECTASSIGNMENT COMMANDASSIGNMENT ACKCONNECT ACKconversationconversationconversationDISCONNECTRELEASERELEASE COMPLETECHANNEL RELEASE
Call Deliver to MH
Mobile-Assisted HandoverMobilestation
Basestation
Logical Channel
TCHTCHSACCHTCHTCHTCHSACCHTCHFACCHnew TCHTCHTCHTCH
FACCHTCHTCHSACCHTCHTCHTCHSACCHTCH
conversationconversation
MEASUREMENT REPORTconversationconversationconversation
MEASUREMENT REPORTconversation
HANDOVER COMMANDHANDOVER ACCESSHANDOVER ACCESSHANDOVER ACCESS
PHYSICAL INFORMATIONHANDOVER COMPLETE
conversationconversation
MEASUREMENT REPORTconversationconversationconversation
MEASUREMENT REPORTconversation
GSM Registration (simplified)• When an MS needs registration (first turned on, found the current cell has a
different ID)1. MS sends Channel Request to BSC2. BSC replies with Activation Response3. MS sends Activation ACK4. BSC assigns a channel to process registration5. MS sends Location Update Request to MSC6. MSC replies with Authentication Request7. MS replies with Authentication Response8. MSC checks the authentication9. MSC assigns TMSI to MS10. MS sends ACK for TMSI11. MSC updates VLR and HLR12. BSC informs the MS to release the channel for registration
Location Registry
• Registration Message Flow– Inter-LA movement• In the same MSC
– Inter-MSC movement• In the same GSM Operator
– Inter-VLR movement
17
Mobile Switching
Center
VLR
old BSS
1
3
24
5 6
78
GSM: handoff with common MSC
new BSS
1. old BSS informs MSC of impending handoff, provides list of 1+ new BSSs
2. MSC sets up path (allocates resources) to new BSS
3. new BSS allocates radio channel for use by mobile
4. new BSS signals MSC, old BSS: ready 5. old BSS tells mobile: perform handoff to
new BSS6. mobile, new BSS signal to activate new
channel7. mobile signals via new BSS to MSC: handoff
complete. MSC reroutes call8 MSC-old-BSS resources released
MS BSS MSC/VLR HLR PSTN
Channel REQuest
IMMediate ASSignComplete layer 3 Info,
AUThentication REQuest
TMSI REALlocation CoMmanD
SETUP
Mobile-originated call, mobile to land call flow (part 1 of 2)
AUThentication RESponse
Cipher Mode CompleteCipher Mode CMD
Cipher Mode CMDCipher Mode Complete
TMSI REALlocation COMplete
MS BSS MSC/VLR HLR PSTNCALL PROCeeding
Mobile-originated call, mobile to land call flow (part 2 of 2)
Assignment Request
ASSignment CoMmanD
Assignment CompleteAssignment Complete
Initial Address Message (IAM)
Address Complete message (ACM)Alerting
Answer Signal/answer Message(ANM)connect
Connect Acknowledge
PriorMSC
PriorVLR HLR
ServingVLR
ServingMSC
ServingBase
Call setup to a roaming subscriber
Receive callsetup request
LOCATION REQUEST INVOKE
ROUTE REQUEST INVOKE
ROUTE REQUEST INVOKE
ROUTE REQUEST RESULT
ROUTE REQUEST RESULT
LOCATION REQUEST RESULT
Call setup request
(temporary phone number) Page command
PAGE
Delete MIN
conversation VMPS call setup
GMSC
MSC/VLR
BSC
HLR
BTS BTS BTS
MSISDN
MSISDN
MSRN
IMSI
MSISDN-->IMSI-->MSC/VLR Service Area
IMSI<-->MSRN
6.
1.3.
5.
4.
7.
8.
8. 9.
2.
PSTN5.
Call Delivery
MS BSS MSC/VLR HLR PSTN
Mobile-terminated call, land to mobile call flow (part 1 of 2)
Send routing info.Provide roaming numberRoaming number
Routing informationInitial address message
Paging commandPaging request
Channel requestImmediate assign
Complete layer 3 info.Authentication requestAuthentication response
Cipher mode cmdCipher mode cmd
Cipher mode cmdCipher mode complete
Mobile-terminated call, mobile to land call flow (part 2 of 2)
MS BSS MSC/VLR HLR PSTNTMSI reallocation commandTMSI reallocation completeSETUPCall confirmed
Assignment requestAssignment command
Assignment completeAssignment complete
alerting
connect
Connect acknowledge
Address complete message
Answer signal /answer message
MS BSS MSC VLR HLR VLR
Location Update in new MSC
Authenticate
Authentication Resp,
Start ciphering
Forward new TMSI
Loc.n area up. acc
Send para(authentication)
Authentication Prar.
Update location
Insert subscriber data
Subs. Data Ins. Acc.Loc.n update acc
Cancel location
Loc.n cancellation acc.
Location update call flow
Inter-MSC handover
BSS1 MSC-A MSC-B BSS2 VLR-B
Handover request
MS
Perform handover Allocate handover numberHandover request
Send handover reportHandover request ack
Radio channel ackInitial address messageAddress complete message
Handover commandHandover command
Handover accessHandover detect physical information
Handover completeHandover complete
Answer signalSend end signal
Clear commandClear complete End signal
Remove handover report