GSM Protocol Stack

Shrish Mammattva Bajpai

What is Protocol Stack ?A protocol stack (sometimes communications stack) is a particular software implementation of a computer networking protocol suite. The terms are often used interchangeably. Strictly speaking, the suite is the definition of the protocols, and the stack is the software implementation of them. In Windows the TCP/IP stack is implemented by the Winsock DLL.

What is Protocol Stack ? The term stack also refers to the actual software that processes the protocols. So, for example, programmers sometimes talk about loading a stack, which means to load the software required to use a specific set of protocols.

Um Interface

A Interface

MS End Protocol StackPhysical LayerData Link LayerLayer 3 Radio Recourse Management Mobility Management Connection Management

BTS End Protocol StackPhysical LayerData Link LayerLayer 3 Radio Recourse Base Transreceiving Station Management

BSC End Protocol StackPhysical LayerData Link LayerLayer 3 Radio Recourse Base Tranreceiving Station Management Signaling Connection Control Part Direct Transfer Application Part Base Station Subsystem Management Application Part

MSC End Protocol Stack Message Transfer Part Signaling Connection Control Part Direct Transfer Application Part Base Station Subsystem Management Application Part Connection Management Mobility ManagementMobile Application PartTransaction Capabilities Application Part.

Link Layers

Um InterfacePhysical Layer Implement Logic channels,coding and frames. Access Capabilities. Error Detection. Encryption.

Um Interface Physical Layer ModeMode of operations Idle Mode. Dedicated Mode.

Um Interface Physical Layer Mode

Um Interface Physical Layer Frame

Um Interface Physical Layer Frame21 Blocks.Power level.Timing advance. Use by ACCH, CCCH, BCCH & DCCH.

Um Interface Data Link Layer Task

Um Interface Data Link Layer Operation Mode 1Unacknowledged Operation Data Transmitted in UI frame. No Ack No Flow control Mechanism. No L2 error correction technique. Use for all channels except RACH. .

Um Interface Data Link Layer Operation Mode 2Acknowledged Operation Mode Data Transmitted in I frame. + Ve Ack Flow control Mechanism. Error correction technique. Use for DCCH Channel

Um Interface Data Link Layer

Um Interface Data Link Layer Connection End Point Identifiers of L2 connections are labeled with Data Ling Layer Identifiers 1.Service Access End Point Identifiers 2.Connection End Point Identifiers SAPI =0 for Signaling. SAPI = 3 for SMS.

Um Interface Data Link LayerProcedure 1Distribution Procedure SAP is associated with only one signaling channel Distribution of L2 frame receive by one channel to the respective data link procedure. Not used for RACH

Um Interface Data Link LayerProcedure 2Random Access Procedure Only for RACH Unidirectional Procedure Deals with random control procedure Retransmission of Random Access Brust

Um Interface Data Link LayerFrame Formats 1Points No flag at start and at last. Octets are depend upon type of channel. The end of information field is given by length indicator. Frame format contains address field and variable length. Connection of SAPI = 0 is initiated by MS. Address Field is one for control channels

Um Interface Data Link LayerFrame Formats 2

Um Interface Data Link LayerFrame FormatsType A. Used in dedicated channels Bi-directional Use. No Information Contain. Ack Mode Operation.

Um Interface Data Link LayerFrame Formats 2

Um Interface Data Link LayerFrame FormatsType B. Used in dedicated channels Bi-directional Use. Information Contain. Ack Mode Operation.

Um Interface Data Link LayerFrame Formats

Um Interface Data Link LayerFrame FormatsType Bbis Used in common control channels Uni-directional Use. Information Contain. Un Ack Mode Operation. SAPI =0 is used.

Um Interface Data Link LayerFrame Formats

Um Interface Data Link LayerFrame FormatsType Abis Used in common control channels Uni-directional Use. No Information Contain. Un Ack Mode Operation. SAPI =0 is used.

Um Interface Layer 3Layer 3 RR Management. CM Management. MM Management.

Um Interface Layer 3 Frame Format 1Common for RR, MM and CM.

Um Interface Layer 3 Frame Format 2Transaction ID- Enable to perform several parallel signaling transaction.Protocol Discriminator Operation type.Message Type Different type of process.Information ID Information elements.Length Indicator Length of the Information ID.

Um Interface Layer 3 Radio Recourse Management. Functions

Um Interface Layer 3 Radio Recourse Management. ProcessesConnection Set Up And Release.Handoff.Channel ChangeCiphering.

Um Interface Layer 3 Radio Recourse Management. Connection Set Up And Release Processes

Um Interface Layer 3 Radio Recourse Management. Connection Set Up And Release Processes

Um Interface Layer 3 Radio Recourse Management. Connection Set Up And Release Processes

Um Interface Layer 3 Radio Recourse Management. Connection Set Up And Release ProcessesRR Connection between MS & Nwk..LAPDm Connection between MS & Nwk..Initiated by MS or Nwk. .RR connection Establish then higher link comes in picture.SAPI =0 is used.

Um Interface Layer 3 Radio Recourse Management. Channel Change Processes

Um Interface Layer 3 Radio Recourse Management. Channel Change ProcessesRequested By CM, MM or by RR.Initiated By Nwk..MS get assignment command to shut down the connection.

Um Interface Layer 3 Radio Recourse Management. Handoff Process

Um Interface Layer 3 Radio Recourse Management. Handoff Process

Um Interface Layer 3 Radio Recourse Management. Handoff ProcessCell Information BCCHHandoff Command ACCHHandoff Access DCCH

Um Interface Layer 3 Radio Recourse Management. Activation of Ciphering Process

Um Interface Layer 3 Radio Recourse Management. Activation of Ciphering ProcessDone By BSS.MS get the message and done the task.

Um Interface Layer 3 Mobility Management Functions

Um Interface Layer 3 Mobility Management ProcessCommon Mobility Management Process. TMSI Assignment. Identification Process. Authentication Process. IMSI Detach.Specific Mobility Management Process IMSI Attach Location Updation. MM Connection Management Process

Um Interface Layer 3 Mobility Management Process. TMSI Assignment 1

Um Interface Layer 3 Mobility Management Process. TMSI Assignment 2Unique identifier for each MSChange with every location updation.Send through BCCH with LAI identifier.

Um Interface Layer 3 Mobility Management Process. Identification Process. 1

Um Interface Layer 3 Mobility Management Process. Identification Process. 2At any time when network wants.IMSI + IMEI sends to Network.

Um Interface Layer 3 Mobility Management Process. Authentication Process. 1

Um Interface Layer 3 Mobility Management Process. Authentication Process. 2Started by Network, when MS send the request to establish RR connection.RAND and Kc.When fails then IMSI and TMSI will send.Two time only.Fail then cancel all the connections.Emergency Calls can made only.

Um Interface Layer 3 Mobility Management Process. IMSI Detach. 1

Um Interface Layer 3 Mobility Management Process. IMSI Detach. 2Switch off the cell.Cancel the paging load from network.Send the message to MS on BCCH and SCCH.This process will start after the any specific operation.

Um Interface Layer 3 Mobility Management Process. Location UpadationChannel Used BCCH.Identifier TMSI & LAI.Register HLR & VLR.

Um Interface Layer 3 Mobility Management Process. IMSI Attach.Switch on the cell.New TMSI and LAI.

Um Interface Layer 3 Connection ManagementThree Entities 1.Call Control. 2.Supplementary Services. 3. Short Message Services.

Um Interface Layer 3 Connection Management

A Interface Protocol Stack Message Transfer Part Signaling Connection Control Part Direct Transfer Application Part Base Station Subsystem Management Application Part Connection Management Mobility ManagementMobile Application PartTransaction Capabilities Application Part.

A Interface Message Transfer PartComprise lower 3 layer of OSI model.Routing.Transportation of the signaling message.

A Interface Mobile Application Part

A Interface Signaling Connection Control PartProvides Connection less and connection oriented Services.Messages through BSC.Two Reasons for setting the SCCP Connection. 1.Location Update. 2.Call Connection Setup.

A Interface Transaction Capabilities Application PartConnectionless Service given By SCCP.Exchange of MAP messages(Between different MSC, HLR, VLR and GMSC) done through this part.

A Interface Base Station System Application PartTwo Parts Base Station System Management Application Part. Direct Transfer Application Part.

A Interface Direct Transfer Application Part. The messages through CM & MM are passed on transparently through BSS using DTAP Protocol.Only Connection Oriented Services.One signaling connection for each active MS with one or more transaction.New connection establish each time when the new transaction start between MS and MSC.

A Interface BSSMAP Responsible for all admin and control of the radio recourses.Handoff and channel ass. is control by BSSMAP.Two type of procedure. 1.Global BSSMAP procedure. 2.Dedicated BSSMAP procedure.

A Interface BSSMAP Dedicated BSSMAP procedureChannel Assignment.Channel Release.Cyphering Control.

A Interface BSSMAP Dedicated BSSMAP procedure

A Interface BSSMAP Global BSSMAP procedurePagingFlow ControlClosing and Opening of the channel.

A Interface BSSMAP Global BSSMAP procedure

Abis Interface BTSMTask Random Access of the channel. Paging process of MS. Ciphering process of MS. Power Control of MS.

Abis Interface BTSM Frame

Abis Interface BTSM FrameMessage Discriminator 1 for passes through BTS. 2-5 serve by BTS.