Map Call Flow Important

17/03813 LZU 108 897/1 Rev B WCDMA Systems – Signaling in the Core NetworkChapter 17 - Slide 1

Objectives

Upon completion of this chapter the student will be able to:

Explain the basic functions of different protocols used in the Base Station System and on the GSM air interface

Explain the basic functions of different protocols used towards and between GPRS Support Nodes


GSM network structure

…………BTS

MSC

SSF

IWF

GMSC HLRAUC

EIR

SMSGMSC

SMSIWMSC

SGSN

GGSN

BSC

Switching System

Base Station System

GPRS

PSTN/ISDN

Internet

TRC

SC

SCF

IN

VLR


Signaling between MS and MSC

GSM L1 GSM L1 Layer 1 Layer 1

LAPDm LAPDm LAPD LAPDMTP MTP MTP

TU

P / IS

UP

SCCP SCCPSCCPBTSMBTSMRR

BSSAPRR

BSSAP

RR

MM

CM

MAP

TCAP

RR

MM

CM

Um Abis A

MSCBSCBTSMS

CM Connection ManagementMM Mobility ManagementRR Radio Resource Management

CM,MM,RR = Radio Interface Layer 3LAPDm Link Access Procedures for Dm-channelGSM L1 Air interface layer 1BTSM BTS Management

BSSAP Base Station System Application PartMAP Mobile Application PartTCAP Transaction Capabilities Application PartSCCP Signaling Connection Control PartISUP ISDN User PartTUP Telephony User PartMTP Message Transfer Part


Overview of air interface layer 3 functions

…………

…………

………… BSCConnection Management

Mobility Management

Radio Resource Management

BSC

BSC

MSC

MSC

MSC

Call Control: SET-UP, CALL PROCEEDING, ALERTING, CONNECT, DISCONNECT, RELEASESS Control: HOLD, RETRIEVE, FACILITY, RELEASE COMPLETEOther: START DTMF, STOP DTMF, EMERGENCY SETUP

Location Management: LOCATION UPDATE REQUEST, IMSI DETACH INDICATIONSecurity Management: AUTHENTICATION REQUEST, IDENTITY REQUEST, TMSI REALLOCATION COMMANDCM Service Control: CM SERVICE REQUEST, CM SERVICE ACCEPT, ABORT

Channel Control: IMMEDIATE ASSIGNMENT, ASSIGNMENT COMMAND, CHANNEL RELEASEHandovers: HANDOVER COMMAND, HANDOVER ACCESS, HANDOVER COMPLETESystem Info: SYSTEM INFORMATION TYPE 1 … 8Other: PAGING, CIPHERING MODE COMMAND, CLASSMARK CHANGE


Example LAPDm signaling

SABM

UA

I

RR

I

RR

I

…

UI

UI

UI

…

Acknowledged Mode

Unacknowledged Mode

Selected LAPDm Frame Types:

SABM Set Asynchronous Balanced ModeUA Unnumbered AcknowledgementI Information frameRR Receiver ReadyDISC DisconnectDM Disconnected ModeUI Unnumbered Information frame

SABM and UA frames are used to start acknowledged modeDISC and DM (not shown) are used to end acknowledged mode

Every I frame contains a send sequence number

Every RR or I frame contains a receive sequencenumber and can be used as acknowledgementor request for retransmission

Long layer 3 messages can be segmented

Every frame is 23 octets long

No acknowledgements for UI frames

No segmentation possible

Every frame is 23 octets long


BSC-BTS layer 3 messages

…………

…………

Radio Link Layer Management

ESTABLISH REQUEST, ESTABLISH INDICATION,DATA REQUEST, DATA INDICATIONUNIT DATA REQUEST, UNIT DATA INDICATION………… BSCBTS

LAPDm events

Dedicated Channel Management

CHANNEL ACTIVATION, CHANNEL RELEASE,ENCRYPTION COMMAND, POWER CONTROLHANDOVER DETECTION, MEASUREMENT RESULT………… BSCBTS

Dedicated channel

Common Channel Management

BCCH INFORMATION, PAGING COMMAND,CHANNEL REQUIRED, IMMEDIATE ASSIGN COMMAND

BSCBTSCommon channels…………

Transceiver Management

SACCH FILLING, OVERLOAD,RF RESOURCE INDICATION

BSCBTS

Transparent layer 3 messages


BSSAP signaling at location updatingMSMSC

BSSMAP: Complete layer 3 info(MM: Location Updating Request)SCCP: CR (Connection Request)

MM: Location Updating Request

BSS

Radio connection establishment

SCCP: RLSD (Released)

DTAP: (MM: Authentication Request)SCCP: DT1 (Data Form 1)

DTAP: (MM: Authentication Response)SCCP: DT1 (Data Form 1)

DTAP: (MM: Location Updating Accept)SCCP: DT1 (Data Form 1)

Radio connection release

BSSMAP: Clear CommandSCCP: DT1 (Data Form 1)

BSSMAP: Clear CompleteSCCP: DT1 (Data Form 1)

SCCP: CC (Release Complete)

SCCP: CC (Connection Confirm)


Part of call setup signaling between BSC and TRC

BSSMAP: Assignment Complete [SCCP: DT1]

BTAP: Seize Transmission Result [SCCP: CC]

BTAP: Seize Transmission [SCCP: CR]

MSTRC BSS

Traffic channel assignment

BSSMAP: Assignment Request [SCCP: DT1]

MSC

Call through-connection and conversation

BSSMAP: Clear Complete [SCCP: DT1]

BTAP: Release Transmission Ack [SCCP: DT1]

BTAP: Release Transmission [SCCP: DT1]

Channel deactivation and release

BSSMAP: Clear Command [SCCP: DT1]

[SCCP: RLC]

[SCCP: RLSD]


Transmission plane in GPRS

GSM L1 GSM L1 L1 bis L1 bis

MAC MAC NS

L1

IPBSSGPBSSGPRLC

TCP / UDPLLCLLC

SNDCP

IP

Um Gb Gn

GGSNSGSNBSSMS

IP Internet ProtocolSNDCP Sub-network Dependent Convergence ProtocolLLC Logical Link ControlRLC Radio Link ControlMAC Medium Access ControlBSSGP Base Station System GPRS Protocol

GTP GPRS Tunneling ProtocolTCP Transmission Control ProtocolUDP User Datagram ProtocolL1 Layer 1L2 Layer 2NS Network Service

RLC

Application

NS

SNDCP

L2

GTP

L1

L2

GTP

IP

IP

TCP / UDP

Gi


RLC/MAC protocol data unit handling

RLC/MAC header

RLC/MAC block

LLC protocol data unit

Normal burst

Radio block after channel coding


MS—SGSN signaling plane in GPRS

GSM L1 GSM L1 L1 bis L1 bis

MAC MAC NS

BSSGPBSSGPRLC

LLCLLC

GMM/SM

Um Gb

SGSNBSSMS

LLC Logical Link ControlRLC Radio Link ControlMAC Medium Access ControlBSSGP Base Station System GPRS Protocol

GMM GPRS Mobility ManagementSM Session ManagementNS Network Service

RLC

NS

GMM/SM


Incoming call to GSM network

MSC/VLRGMSC HLR

ISUP: IAMcalled no = MSISDN MAP: AARQ

Send Routing Infocalled no = MSISDN

TCAP: BEGIN, INVOKESCCP: UDT

MAP: AARQProvide Roaming Nocalled no = IMSI

TCAP: BEGIN, INVOKESCCP: UDT

MAP: AAREProvide Roaming NoMSRN returned

TCAP: END, RESULTSCCP: UDT

MAP: AARESend Routing InfoMSRN returned

TCAP: END, RESULTSCCP: UDT

ISUP: IAMcalled no = MSRN

All SCCP messages are sentin MTP Message SignalUnits (MSU)


RR connection establishmentBSC BTS

BSSMAP: PagingIMSI [,TMSI]

SCCP: UDT CCM: Paging CommandIMSI/TMSI, … RR: Paging request

IMSI/TMSIPCH channel

RR: Channel requestreason, rand ref

RACH channelCCM: Channel Required

time adv, frame no[RR: Channel request]

…………MSC/VLR

DCM: Channel Activationchannel type, power, ...

DCM: Channel Activation Ack

All SCCP messages are sentin MTP Message SignalUnits (MSU)

LAPDm unacknowledgedmode is used on commonand broadcast channels

LAPD I-frames (information)are used for L3 messages

CCM: Imm Assign Commandchannel type, time adv,reason, ref, frame no

RR: Imm Assign Commandchannel type, time adv,reason, ref, frame no

AGCH channel

PCH Paging ChannelRACH Random Access ChannelAGCH Access Grant ChannelCCM Common Channel ManagementDCM Dedicated Channel Management


Service request from MS

BSC BTS

RR: Paging ResponseIMSI/TMSI, capabilities

LAPDm: SABMSDCCH channel

RLM: Establish Indication[RR: Paging Response]

…………MSC/VLR

SCCP: CC

A new SCCP connectionis established for this call

Paging Response is sent backto the MS to make sure that oneMS uses the allocated channel

RLM Radio Link Layer ManagementCR Connection RequestCC Connection Confirm

SDCCH Stand-alone Dedicated Control ChannelSABM Start Asynchronous Balanced ModeUA Unnumbered Acknowledgement

RR: Paging ResponseIMSI/TMSI, capabilities

LAPDm: UASDCCH channel

BSSMAP: Complete L3 Info[RR: Paging Response]

cell global identitySCCP: CR

LAPDm acknowledged modeis established. Furthermessages use I-frames


Authentication and ciphering activation

BSC BTS

DTAP: Authentication ReqRAND, CKSN

SCCP: DT1

MM: Authentication ResponseSRES

…………MSC/VLR

Messages sent on SDCCH

RLM: Data Request[MM: Authentication Req

RAND, CKSN] MM: Authentication RequestRAND, CKSN

RLM: Data Indication [MM: Authentication Resp

SRES]DTAP: Authentication Resp

SRESSCCP: DT1

BSSMAP: Ciph Mode Cmdalgorithm, key

SCCP: DT1

MM: Ciph Mode Complete

DCM: Encryption Commandalgorithm, key

[MM: Ciphering Mode Cmdalgorithm]

MM: Ciphering Mode CmdA5 algorithm version

RLM: Data Indication [MM: Ciph Mode Complete]BSSMAP: Ciph Mode Compl

SCCP: DT1


IMEI check and TMSI reallocation

BSC BTS

DTAP: Identity Requesttype=IMEI

SCCP: DT1

MM: Identity ResponseIMEI

…………MSC/VLR

RLM: Data Request[MM: Identity Request

type=IMEI]MM: Identity Request

type=IMEI

RLM: Data Indication [MM: Identity Response

IMEI]

DTAP: Identity ResponseIMEI

SCCP: DT1

DTAP: TMSI Realloc Cmdnew TMSI

SCCP: DT1

MM: TMSI Realloc Complete

RLM: Data Request[MM: TMSI Realloc Cmd

new TMSI]MM: TMSI Reallocation Cmd

new TMSI

RLM: Data Indication [MM: TMSI Realloc Compl]DTAP: TMSI Realloc Compl

SCCP: DT1


Call initiation

BSC BTS

DTAP: Set-upbearer capabilitiescalling number

SCCP: DT1

CM: Call confirmedbearer capabilities

…………MSC/VLR

RLM: Data Request[CM: Set-up

bearer capabilitiescalling number]

CM: Set-upbearer capabilitiescalling number

RLM: Data Indication [CM: Call confirmed

bearer capabilities]

DTAP: Call confirmed bearer capabilities

SCCP: DT1


TCH activation, part 1

TRC

BSC

BSSMAP: Assign Requestcircuit id and type

SCCP: DT1

MSC/VLR

BTAP: Seize Transm ResultSCCP: CC

BTAP: Seize Transmissioncircuit id and type

SCCP: CR

BTS

DCM: Channel Activationchannel type, power, ...

DCM: Channel Activation Ack


TCH activation, part 2

BSC BTS

RR: Assign CompleteFACCH channel

…………MSC/VLR

RLM: Data Request[RR: Assign Command

channel info]

LAPDm: UAFACCH channel

RLM: Data Indication [RR: Assign Complete]

BSSMAP: Assignment ComplSCCP: DT1

DCM: RF Chan Rel Ack

RR: Assign Commandchannel info]

SDCCH channel

RLM: Establish Indication

LAPDm: SABMFACCH channel

DCM: RF Channel Release

FACCH Fast Associated Control Channel

Subsequent messages sent on FACCH. LAPDm I-frames(information) are used.


Call connection

BSC BTS…………MSC/VLR

RLM: Data Indication [CM: Connect ack]

DTAP: Connect ackSCCP: DT1

CM: Connect acknowledge

RLM: Data Indication [CM: Alerting]DTAP: Alerting

SCCP: DT1

User decides to answer call

CM: Alerting

RLM: Data Indication [CM: Connect]DTAP: Connect

SCCP: DT1

CM: Connect

The call is fully through-connected and conversation or data transfer may proceed...


Relationship between ISUP and CM messages

GMSC MSC/VLR…………

Channel release, circuit release, etc.

CM: Release complete

ISUP: IAM

ISUP: REL

ISUP: ANM

CM: Release

ISUP: IAM

CM: AlertingISUP: ACMISUP: ACM

CM: Connect

ISUP: RLC

ISUP: ANM

ISUP: REL

ISUP: RLC

CM: Connect acknowledge

CM: Disconnect

MS disconnects the call

Paging, authentication, channel assign, etc.

CM: Setup

Call in progress


Objectives Revisited

Upon completion of this chapter the student will be able to:

• Explain the basic functions of different protocols used in the Base Station System and on the GSM air interface

• Explain the basic functions of different protocols used towards and between GPRS Support Nodes

Map Call Flow Important

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