GSM Signaling Procedure Huawei Vietnam RF Team

GSM Network Protocol DTAP RSL OML OSI : Open System Interconnection SCCP : Signalling Connection Control Part (OSI Layer 3 complementary Software in SS7 code, used to manage signalling channel without associated speech channel) MTP : Message Transfert Part DTAP : Direct Transfert Application Part (BSC <-> MS transfert protocol) MAP : Mobile Application Part (Protocol Used between NSS Machine) TCAP : Transaction Capabilities Application Part (Layer 7 sub-set in CCITT n°7 signalling system)

GSM Network Protocol Layer 3 Introduction RR :（Radio Resource Management） Control by MS、BTS and BSC Function Sample Paging Management Ciphered Mode Management Frequency Redefinition Dedicated Channel Assignment Handover Management Measures and Power Control MM :（Mobility Management） Control by MS and MSC / VLR Authentication / Identification Procedures Location Updating IMSI Attach / Detach Example of RR procedure message: Immediate Assignment (seizure of a SDCCH) Assignment Command (seizure of SD or TCH) Handover Command Channel Release Paging Request Measurement Report Example of MM procedure message : IMSI Detach Indication Location Updating Request Authentication Request Identity Request CM Service Request Example of CCprocedure message : Alerting Connect Progress Setup Disconnect Release

GSM Network Protocol CC : （Call Control） Control by MS and MSC Function Sample Call processing and routing Short Message Service Supplementary Service

GSM Frame Structure

GSM Multi-Frame Channel

GSM Multi-Frame Channel

Singling Link Establish Procedure Content Establish Signaling Link, used for signaling transmission When MS want to connect to network, firstly must establish the radio signaling link and A-interface link Step included Paging Procedure Random Access Procedure Immediate Assignment Procedure SCCP Connection Establishment Procedure RR Management : functions related to the management of the common transmission resources. Functions can establish, maintain or release RR connections. RR includes the reception of BCCH and CCH when no RR connection is established. Paging Procedure : Network inform that a MS is called Random Access Procedure : Method by which the MS requests Air Interface Resource from the network Immediate Assignment Procedure : BSS allocates a resource to the MS and the MS & Network establish a radio signalling link between themseleves. This procedure is carried out automatically by the BSC without informing the MSC SCCP : Signaling Connection Control Part SCCP Connection Establishment Procedure : When Air interface signalling connection is succesfully established, the MSC is informed of the presence of the mobile by the use of SCCP

Singling Link Establish Procedure Entity MS BTS RACH_TA_Filtering BSC MSC Channel Request ST3126 Channel Required Timer； S -- Start； E -- End （RACH）（Est Cause，Rnd Nbr） （Est Cause，Rnd Nbr，FN，TA） Channel Activation（SD） ST9103 （TA，BS/MS_TxPwr -->Max，Chann） Channel Act Ack （SD） ET9103 Immediate Assignment Command For 2 MS at same time ST3101 （Rnd Nbr，TDMA Frame Nbr，Chan ，TA） （AGCH） Channel Request : available causes : Emergency call, Call re-establishment, Answer to paging, OC and LU. Contains a Random Number to distinguish the answer of the BTS. Send on the RACH. The mobile can send several Ch Req. At the end of the sequence, T3126 is tarted Channel Required : Common Channel Management. Transmission of the Random Number. Timing Advance Estimation Immediate Assign CMD : send on the AGCH to the mobile in IDLE mode to change the channel configuration to a dedicated configuration while staying in the same cell SABM (Set Asynchronous Balanced Mode: to) : create a LAPDm connection. Upon the seizure of the assigned dedicated channel, the mobile station establishes the main signalling link on this channel by sending a L2 SABM frame containing the L3 service request message (CM Serv Req, LU Req, IMSI Detach, Pagres). Send on SDCCH UA (Unnumbered Acknoledge). The service request send by the MS is retruned by the network. The MS compares the message send in the SABM and received in the UA, and leaves the channel in case they do not match.(Send on SDCCH). This allow the discrimination of 2 mobiles Establish Ind : idem as SABM. C01 is incremented with Paging Response. C02 with LU,OC. SCCP Connection Required : the LAC and CI of the BTS are given C40 : number of seconds a SDCCH channel is used UI Imm Assignment / Imm Ass Ext CM Serv Req，Pag Res，Loc Update Req ET3126 Set Asynchronous Balance SABM [L3 Info] （SDCCH） Est Ind [L3 Info] ET3101 UA [L3 Info] SCCP Con Rqrd [L3] ST9105 Unnumbered Ack SCCP Conn Confirm ET9105 Um Abis A

Singling Link Establish Procedure——Abis Abis Signaling Channel Required

Singling Link Establish Procedure——Abis Channel Activation

Singling Link Establish Procedure——Abis Immediately Assignment

Authentication, Identification, Ciphering, TMSI Re-allocation RAND and Ki by A3 algorithm get SRES; by A8 algorithm get Kc VLR get from HLR the RAND/SRES/Kc MS BTS BSC MSC Authentication Req Authentication Req （RAND） ST3260 Authentication Req Authentication Resp Authentication Authentication Resp Check SRES （SRES） Authentication Resp ET3260 *Authentication Reject* Identification Request Identification Request Identification Request ST3270 Identification Identification Response Identification Response （IMSI） Identification Resp ET3270 （Alg（A5）） （Alg，Kc） （Permitted Alg，Kc） Ciphering Mode Cmd Encryption Command Ciphering Mode Cmd Authentifiaction procedure (MM Procedure): To check if the identity of the mobile is acceptable or not. Provide parameters enabling MS to calculate the new ciphering key. This procedure is used at each call setup, suplementary service, location updating. Identification procedure (MM Procedure) : Procedure used by the network to request a Mobile station to provide his IMSI Ciphering Mode setting procedure (RR Procedure) :Used to set the ciphering mode. Indicate wether ciphering shall be used or not and if yes which algortihm to use TMSI Realloc Proc (MM Procedure) : Provide identity confidentiality to the MS. The TMSI has significance only within a location area. Ciphering Ciphering Mode Cmp Ciphering Mode Cmp Ciphering Mode Cmp TMSI Realloc Cmd TMSI Realloc Cmd （TMSI） ST3250 TMSI Realloc Cmd TMSI Realloc TMSI Realloc Cmp TMSI Realloc Cmp TMSI Realloc Cmp ET3250

Authentication, Identification, Ciphering, TMSI Re-allocation Authentication Request

Authentication, Identification, Ciphering, TMSI Re-allocation Authentication Response

Authentication, Identification, Ciphering, TMSI Re-allocation Identification Response

TCH Assignment Procedure Content Normal Assignment for TCH Special case Queuing Directed Retry OACSU : Off Air Call Setup : allow the late assignment of the TCH (after the Alerting). This feature allows an increase of the efficiency of the TCH. Queuing : allows a TCH channel allocation to be queued for a time whilst no TCH free Directed Retry : allows the BSS to assign a TCH on another cell by internal handover

TCH Assignment Procedure MS BTS BSC MSC Assignment Request （SDCCH） STrr1 Physical Context Request （Chn Type，Priority，CIC，DL DTX，Queuing Flag） ST9108 （TA，MS/BS_TxPwr） Physical Context Confirm ET9108 （TA，MS/BS_TxPwr） Channel Activation TCH ST9103 Channel Activation Ack. ET9103 （MA，TS，HSN，MAIO，MS_TxPwr） Assignment Command Assignment Command ST3107 On TCH if need signaling, then use Stealing Flag transfer TCH into FACCH SABM (FACCH) Establish Indication Phys Con Req : Allow the BSC to obtain information on the phsical context of a radio channel just prior to a channel change.Includes the BS Power, MS Power, TA Assignment Request : Detail of the resource that is required (channel rate, channel type,...). It also include the terrestrial circuit that shall be used between the BSC & MSC. If the Assignment is not completed, the Assigenemtn failure is send on A interface with cause : RIMF : the BSS doesn't receive the Assigenemtn complete RIF : failure on the Radio or A-bis interface during activation of the channel No Radio Resource available Requested Terrestrial Resource unavailable Requested Terrestrial Resource alreqdy allocated Radio Interface Failure, Reversion to old channel Ciphering Algo not supported Assignment Command : send on SDCCH -> to change the Channel configuration SABM, ESTIN, UA : see Radio & Link Establishment C16 : incremented when a RTCH channel has been successfully selected for any other purpose than HO. C18 : incremented when a RTCH has been successfully seized by the MS for any other purpose than HO UA Assignment Complete Assignment Complete ET3107 Assignment Cmp ETrr1 RF Channel Release (SD) RF Channel Release Ack.

TCH Assignment Procedure---A interface Assignment Request EFR Queuing

TCH Assignment Procedure---Abis interface

TCH Assignment Procedure---Abis interface Physical Context Comfirm

TCH Assignment Procedure---Abis interface System Information Type 5 BA List

TCH Assignment Procedure---Abis interface System Information Type 6 LAC/CI

TCH Assignment Procedure---Abis interface Assignment Command Frequency Encoding （Bitmap 0）

TCH Assignment Procedure---Abis interface Frequency Encoding Fixed Bitmap —— Bitmap 0 —— Use for 1~124 AFRCN

TCH Assignment Procedure---Queue and Direct Retry MS BTS BSC MSC Assignment Request Queuing Indication TCH Queue ST11 ET11 Physical Con Req At this time, a TCH become free Assignment Request Direct Retry Queuing Indication ST11 A Handover alarm is raised. A target BTS is selected T Channel Activation ET11 ST9103 Chan. Act. Ack. T ET9103 HO CMD HO CMD S ST3103 The purpose of the Queuing Indication message is to inform the MSC about a delay in the allocation of the necessary dedicated radio resource. In case of Assignment Procedure, T11 is started (T11 specified the maximum queuing delay and is determined by the operator) HO Access ST3124 T HO Detection Phys. Info T ET3124 SABM (FACCH) T Establish Indication UA T HO CMP T HO CMP ET3103 Assignment Cmp

MOC（Early Assignment） MS BTS BSC MSC RR Connection Establishment RR Connection Establishment RR Connection Establishment ESTIN (CM_Serv_Req) CM_Serv_Req （CM Serv Type，Mobile ID，Classmark2，Priority，） Authentication Procedure Authentication Procedure Authentication Procedure SDCCH Ciphering Procedure Ciphering Procedure Ciphering Procedure TMSI Realloc Procedure TMSI Realloc Procedure TMSI Realloc Procedure SETUP SETUP SETUP （called party nbr） Call Proceeding Call Proceeding Call Proceeding Assignment Procedure Assignment Procedure Assignment Procedure Alerting Alerting Alerting Establish TCH first, then connect another part. Alerting transfer on TCH SETUP : to indicate a mobile Originating Call establishment (contains the call number) Progress : from the Network to the MS to indicate the progress of a call Call Proceeding : send by the network to the calling MS to indicate that the requested call establishment information has been receivedand no more call establishment will be accepted Alerting : to indicate the called user alerting has been initiated Connect : indicate the call acceptance by the called user Connect Acknowledge : to acknowledge the offered connection Connect Connect Connect TCH Connect Ack. Connect Ack. Connect Ack. Speech

MOC —— A interface A interface Two times Classmark Update, the 1st one is caused by Early Classmark Sending (ECSC); 2nd caused by BSC send Classmark Enquiry

MOC —— A interface CM Service Request MOC est/pkt mode con estab Short message service Suppl service activation CLASSMARK

MOC —— A interface CLASSMARK Include MS Revision Level MS Ciphering Capability MS Frequency Capability MS RF Power Capability in Each Band

MOC —— A interface CLASSMARK

MOC —— A interface Setup Called Number

MOC（Late Assignment） Speech MS BTS BSC MSC ESTIN (CM_Serv_Req) RR Connection Establishment RR Connection Establishment RR Connection Establishment ESTIN (CM_Serv_Req) CM_Serv_Req Authentication Procedure Authentication Procedure Authentication Procedure Ciphering Procedure Ciphering Procedure Ciphering Procedure TMSI Realloc Procedure TMSI Realloc Procedure TMSI Realloc Procedure SDCCH SETUP SETUP SETUP Call Proceeding Call Proceeding Call Proceeding Alerting Alerting Alerting Establish another side channel, then setup TCH , Alerting send on SDCCH Assignment Procedure Assignment Procedure Assignment Procedure Connect Connect Connect Connect Ack. Connect Ack. Connect Ack. TCH Speech

MTC Speech MS BTS BSC MSC Paging Request Paging Command Paging Paging Group Number: defined by BS_AG_BLKS_RES and BS_PA_MFRMS;MS belong to the Paging Group = (IMSI mod 1000) mod N;MS only monitor its own Paging Group’s Paging Req message MTC MS （MS ID（TMSI/IMSI）） （Max 4 TMSI） BTS （MS ID（TMSI/IMSI），Paging Group） BSC （MS ID（TMSI+IMSI/IMSI），Cell ID（LAC/LAC+CI）） MSC Paging Request Paging Command Paging ST3113 RR Connection Establishment RR Connection Establishment RR Connection Establishment ESTIN (Paging Resp) Paging Response ET3113 （Mobile ID，Classmark2，Priority，） Authentication Procedure Authentication Procedure Authentication Procedure Ciphering Procedure Ciphering Procedure Ciphering Procedure TMSI Realloc Procedure TMSI Realloc Procedure TMSI Realloc Procedure SETUP SETUP SETUP （calling party nbr） Call Confirmed Call Confirmed Call Confirmed Assignment Procedure Assignment Procedure Assignment Procedure Alerting Alerting Alerting Connect Connect Connect Connect Ack. Connect Ack. Connect Ack. Speech

MTC —— A interface A-interface

MTC —— A interface Paging IMSI, BSC use it for calculate Paging Group TMSI, it’s save bits number in radio resource for Paging LAC Paging

MTC —— A interface Paging Response

MTC —— A interface Setup Calling Number

Location Update MS BTS BSC MSC ESTIN (Loc Up Req) Loc Up Req RR Connection Establishment RR Connection Establishment RR Connection Establishment （LU Type，MS ID，LAI，Classmark1，） ESTIN (Loc Up Req) Loc Up Req ST3210 Authentication Procedure Authentication Procedure Authentication Procedure Ciphering Procedure Ciphering Procedure Ciphering Procedure TMSI Realloc Procedure TMSI Realloc Procedure TMSI Realloc Procedure Loc Up Accept Loc Up Accept Loc Up Accept ET3210 Clear CMD Channel Release Channel Release Three Location Updating tye : Normal Location updating : used to update the regeistration of the actual LA of a MS in the Network Periodic Location Updating : to notifiy periodically the availability of the mobile in the network. This procedure is controlled by a timer (T3212) in the MS. The timer is stopped and reset to 0 when : LU accept or Reject message is received, MS has respond to a paging, MS is deactivated. IMSI Attach : to activate a MS in the Network If T3210 expires, then T3211 starts. When T3211 reaches 0, the location update procedure is restarted. Deactivate SACCH DISC UA Release Indication RF Ch Release RF Ch Release Ack Clear CMP

Location Update —— A interface

Location Update —— A interface Location Update Request （Follow-on） call procedure Old LAC Current TMSI

Location Update —— A interface Location Update Accept New LAC Re-allocated TMSI

Old TA、MS/BS_TxPwr will be reused in new channel Intra Cell HO MS BTS BSC MSC Measurement Rep Measurement Res Intra cell HO Phys Context Req OC ST9108 Phys Context Conf ET9108 OC Old TA、MS/BS_TxPwr will be reused in new channel Channel Activation NC ST9103 Channel Activation Ack ET9103 NC OC Handover Command ST3107 OC Assignment Command SABM NC NC Establish Indication UA NC C10 : incremented when a successfull SDCCH Handover is completed. C15 : incremented when a RTCH channel has been successfully selected for HO Purpose C17 : incremented on the target cell when a succesffull RTCH HO is completed. C39 incremented when an SDCCH subchannel of a TS is selected by the BSS. Assignment Complete NC Assignment Complete ET3107 （HO Cause，Cell ID，Chn Type） Handover Performed OC RF Channel Rel ST_RCR_ACK OC RF Channel Rel Ack. ET_RCR_ACK OC : Old Channel NC : New Channel

Intra Cell HO —— Abis Abis

Intra Cell HO —— Abis Assignment Command Old TCH New TCH Channel

Internal Inter Cell HO——Synchronized HO MS BTSserving BTStarget BSC MSC Meas Report Meas Result HO Alarm & Candidate Cell Phys Context Req ST9108 Phys Context Conf ET9108 Old TA is reused in new channel, but MS/BS_TxPwr will use the MAX in new channel Channel Activation ST9103 Channel Act Ack. ET9103 HO Command HO Command （Cell，MA，MAIO，HSN，TS，TA） ST3103 HO Access （AB，DCH） HO Detection ST3106 C15 : incremented when a RTCH has been successfully selected for HO Purpose. C10 : incremented when a successfull SDCCH HO has been performed. C17 : Incremented on the target cell when a successfull RTCH HO is completed ST200 SABM ET3106 Establish Ind UA ET200 Handover Complete Handover Complete ST3103 Handover Performed RF Channel Release ST_RCR_ACK RF Channel Rel. Ack. ET_RCR_ACK

Internal Inter Cell HO——asynchronous MS BTSserving BTStarget BSC MSC Meas Report Meas Result HO Alarm & Candidate Cell No Physical Cont Req procedure, old channel TA can’t reuse for new channel Channel Activation ST9103 Channel Act Ack. ET9103 HO Command HO Command ST3103 HO Access ST3124 Measure TA HO Detection Physical Info ST3105 ET3124 （TA） ST200 SABM （TA is reused） ET3105 Establish Ind C15 : incremented when a RTCH has been successfully selected for HO Purpose C56 : incremented on the serving cell C52 : incremented on the target cell ET200 UA Handover Complete Handover Complete ST3103 Handover Performed Phys Context Req ST9108 Phys Context Conf ET9108 RF Channel Release ST_RCR_ACK RF Channel Rel. Ack. ET_RCR_ACK

Internal Inter Cell HO——A interface HO Performed HO Cause Target Cell

External Inter Cell HO MS BTSserving BTStarget BSCserving BSCtarget MSC Meas Report Meas Result HO Alarm & Candidate Cell HO Required ST_HO_REQ_Lost HO Request STrr2 Channel Activation （SCCP Con Required） ST9103 Channel Act Ack. ST9103 HO Request Ack. ETrr2 HO Command HO Command ST9113 （SCCP Con Conf）. HO Command ET_HO_REQ_Lost ST3103 HO Access ST3124 HO Detection ST8 Phys Information ST3106 ET3124 SABM ST200 ET3106 Establish Ind UA ET200 T8 : toi supervise the Handover procedure with the MS. C15 is incremented when a RTCH channel has been successfully for HO Purpose. Handover Complete Handover Complete ET9113 HO Complete ET3103 RF Channel Release Clear Command RF Ch. Rel. Ack. ET8 Clear Complete SCCP Released SCCP Rel. Cmp.

External Inter Cell HO---A interface A interface——outgoing A interface------incoming

External Inter Cell HO——A interface HO Required HO Cause Target Cell

External Inter Cell HO——A interface HO Command Target cell：BCCH/BSIC Target cell channel type Use for HO Access Initial power for new channel

External Inter Cell HO——A interface Clear Command

External Inter Cell HO——A interface HO Request （1 of 2） Channel type encryption Classmark2

External Inter Cell HO——A interface HO Request （2 of 2） Source cell Priority and Queuing A interface’s CIC Target cell Classmark3

External Inter Cell HO——A interface HO Request Ack HO Command

External Inter Cell HO——A interface HO Complete

Channel Release MS release Network release MS BTS BSC MSC Disconnect Release Complete Release Complete Release Complete Network release Disconnect Disconnect Disconnect Release Release Release Release Complete Release Complete Release Complete

Channel Release——A interface A interface ——MS release Call release（DTAP layer） BSSM release SCCP release Disconnect MS release Normal call clear

Channel Release——A interface A interface ——Network Release Disconnect Network release Another side hung up

Channel Release Channel Release Um Channel Release A interface Release Um and A interface release is separated with each other Um Channel Release BSC send Channel Release message to MS Radio Link Failure A interface Release MSC send CLEAR COMMAD to BSC BSC send CLEAR REQUEST to MSC The MS receives a Channel Release : the MS instruct the LAPDm function to perform a dsiconnection of the LAPDm and start T3110. The radio link failure algorithm in the MS is trigerred by the BSS when it stops the sending of SACCH frames to the MS. SACHH frames should be stopped for a period of T3109 for the algorithm in the MS to detect a radio link failure condition. The BSC initiate by sending the DEACTIVATE SACCH to the BTS. BTS intiated release : when LAPD failure or O&M intervention. In both case, the BTS ensure that the TRX and MS are released and send an ERROR REPORT to the BSC.

Channel Release ——Radio Channel MS BTS BSC MSC ST3110 Channel Release (DCH) Deactivate SACCH DISC (DCH) Release Indication ST3111 BSC send Channel Release To MS UA ET3110 T3111 Expiry Phy Context Request ST9108 Phy Context Confirm Wait for T3111 expired, then release BTS channel, to ensure the UA message have time to send ET9108 RF Channel Release ST_RCR_ACK RF Channel Release Ack ET_RCR_ACK C´hannel Release : cause is included (Normal Release, Abnormal Release (Unspecified, Channel Unacceptable, Timer Expiry, No activity on the Radio Path)). Disconnect : when the MS doesn't receive any SACCH message, the MS steal some TCH for Signalling (FACCH). T3111 : this timer allows the exchange of DISC and UA (the process go on when T3111 expires). Physical Context procedure : by verifying the BS_Power, the BSC detect that the connection is not anymore active. Radio Link Failure : BTS count the number of missing SACCH frame, when this value reach the Radio Link Time Out, the release procedure starts. T_RCR_ACK expiry : the BSC attempts the procedure again. In event that this procedure fails again, the BSC will free the channel for reuse and send an O&M error report No SACCH received from the MS Connection Fail Ind Radio Link Failure RF Channel Release ST_RCR_ACK RF Channel Release Ack ET_RCR_ACK

Channel Release ——Abis

Channel Release——A Interface Release BSC MSC Clear Request ST9104 Clear Command ET9104 BSC Trigger the release ST9101 Clear Complete SCCP Released ET9101 SCCP Released Complete Clear Command MSC Trigger the release Clear Complete ST9101 SCCP Released SCCP Released Complete ET9101

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