GSM Protocol Stack Shrish Mammattva Bajpai

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GSM Protocol StackShrish Mammattva Bajpai
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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.

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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.

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Um Interface
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A Interface
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MS End Protocol Stack

• Physical Layer
• Data Link Layer
• Layer 3
• Radio Recourse Management
• Mobility Management
• Connection Management

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BTS End Protocol Stack

• Physical Layer
• Data Link Layer
• Layer 3
• Radio Recourse
• Base Transreceiving Station Management

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BSC End Protocol Stack

• Physical Layer
• Data Link Layer
• Layer 3
• Radio Recourse
• Base Tranreceiving Station Management
• Signaling Connection Control Part
• Direct Transfer Application Part
• Base Station Subsystem Management Application
  Part

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MSC End Protocol Stack

• Message Transfer Part
• Signaling Connection Control Part
• Direct Transfer Application Part
• Base Station Subsystem Management Application
  Part
• Connection Management
• Mobility Management
• Mobile Application Part
• Transaction Capabilities Application Part.

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Link Layers
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Um Interface

• Physical Layer
• Implement Logic channels,coding and frames.
• Access Capabilities.
• Error Detection.
• Encryption.

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Um Interface Physical Layer Mode

• Mode of operations
• Idle Mode.
• Dedicated Mode.

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Um Interface Physical Layer Mode
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Um Interface Physical Layer Frame
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Um Interface Physical Layer Frame

• 21 Blocks.
• Power level.
• Timing advance.
• Use by ACCH, CCCH, BCCH DCCH.

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Um Interface Data Link Layer Task
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Um Interface Data Link Layer Operation Mode 1

• Unacknowledged Operation
• Data Transmitted in UI frame.
• No Ack
• No Flow control Mechanism.
• No L2 error correction technique.
• Use for all channels except RACH.
• .

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Um Interface Data Link Layer Operation Mode 2

• Acknowledged Operation Mode
• Data Transmitted in I frame.
• Ve Ack
• Flow control Mechanism.
• Error correction technique.
• Use for DCCH Channel

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Um Interface Data Link Layer
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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.

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Um Interface Data Link LayerProcedure 1

• Distribution 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

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Um Interface Data Link LayerProcedure 2

• Random Access Procedure
• Only for RACH
• Unidirectional Procedure
• Deals with random control procedure
• Retransmission of Random Access Brust

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Um Interface Data Link LayerFrame Formats 1

• Points
• 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

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Um Interface Data Link LayerFrame Formats 2
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Um Interface Data Link LayerFrame Formats

• Type A.
• Used in dedicated channels
• Bi-directional Use.
• No Information Contain.
• Ack Mode Operation.

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Um Interface Data Link LayerFrame Formats 2
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Um Interface Data Link LayerFrame Formats

• Type B.
• Used in dedicated channels
• Bi-directional Use.
• Information Contain.
• Ack Mode Operation.

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Um Interface Data Link LayerFrame Formats
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Um Interface Data Link LayerFrame Formats

• Type Bbis
• Used in common control channels
• Uni-directional Use.
• Information Contain.
• Un Ack Mode Operation.
• SAPI 0 is used.

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Um Interface Data Link LayerFrame Formats
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Um Interface Data Link LayerFrame Formats

• Type Abis
• Used in common control channels
• Uni-directional Use.
• No Information Contain.
• Un Ack Mode Operation.
• SAPI 0 is used.

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Um Interface Layer 3

• Layer 3
• RR Management.
• CM Management.
• MM Management.

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Um Interface Layer 3 Frame Format 1

• Common for RR, MM and CM.

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Um Interface Layer 3 Frame Format 2

• Transaction 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.

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Um Interface Layer 3 Radio Recourse Management.
Functions
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Um Interface Layer 3 Radio Recourse Management.
Processes

• Connection Set Up And Release.
• Handoff.
• Channel Change
• Ciphering.

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

• RR 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.

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Um Interface Layer 3 Radio Recourse Management.
Channel Change Processes
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Um Interface Layer 3 Radio Recourse Management.
Channel Change Processes

• Requested By CM, MM or by RR.
• Initiated By Nwk..
• MS get assignment command to shut down the
  connection.

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Um Interface Layer 3 Radio Recourse Management.
Handoff Process
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Um Interface Layer 3 Radio Recourse Management.
Handoff Process
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Um Interface Layer 3 Radio Recourse Management.
Handoff Process

• Cell Information BCCH
• Handoff Command ACCH
• Handoff Access DCCH

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

• Done By BSS.
• MS get the message and done the task.

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Um Interface Layer 3 Mobility Management Functions
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Um Interface Layer 3 Mobility Management Process

• Common Mobility Management Process.
• TMSI Assignment.
• Identification Process.
• Authentication Process.
• IMSI Detach.
• Specific Mobility Management Process
• IMSI Attach
• Location Updation.
• MM Connection Management Process

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Um Interface Layer 3 Mobility Management Process.
TMSI Assignment 1
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Um Interface Layer 3 Mobility Management Process.
TMSI Assignment 2

• Unique identifier for each MS
• Change with every location updation.
• Send through BCCH with LAI identifier.

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Um Interface Layer 3 Mobility Management Process.
Identification Process. 1
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Um Interface Layer 3 Mobility Management Process.
Identification Process. 2

• At any time when network wants.
• IMSI IMEI sends to Network.

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Um Interface Layer 3 Mobility Management Process.
Authentication Process. 1
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Um Interface Layer 3 Mobility Management Process.
Authentication Process. 2

• Started 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.

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Um Interface Layer 3 Mobility Management Process.
IMSI Detach. 1
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Um Interface Layer 3 Mobility Management Process.
IMSI Detach. 2

• Switch 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.

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Um Interface Layer 3 Mobility Management Process.
Location Upadation

• Channel Used BCCH.
• Identifier TMSI LAI.
• Register HLR VLR.

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Um Interface Layer 3 Mobility Management Process.
IMSI Attach.

• Switch on the cell.
• New TMSI and LAI.

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Um Interface Layer 3 Connection Management

• Three Entities
• 1.Call Control.
• 2.Supplementary Services.
• 3. Short Message Services.

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Um Interface Layer 3 Connection Management
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A Interface Protocol Stack

• Message Transfer Part
• Signaling Connection Control Part
• Direct Transfer Application Part
• Base Station Subsystem Management Application
  Part
• Connection Management
• Mobility Management
• Mobile Application Part
• Transaction Capabilities Application Part.

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A Interface Message Transfer Part

• Comprise lower 3 layer of OSI model.
• Routing.
• Transportation of the signaling message.

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A Interface Mobile Application Part
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A Interface Signaling Connection Control Part

• Provides Connection less and connection oriented
  Services.
• Messages through BSC.
• Two Reasons for setting the SCCP Connection.
• 1.Location Update.
• 2.Call Connection Setup.

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A Interface Transaction Capabilities Application
Part

• Connectionless Service given By SCCP.
• Exchange of MAP messages(Between different MSC,
  HLR, VLR and GMSC) done through this part.

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A Interface Base Station System Application Part

• Two Parts
• Base Station System Management Application
  Part.
• Direct Transfer Application Part.

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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.

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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.

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A Interface BSSMAP Dedicated BSSMAP procedure

• Channel Assignment.
• Channel Release.
• Cyphering Control.

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A Interface BSSMAP Dedicated BSSMAP procedure
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A Interface BSSMAP Global BSSMAP procedure

• Paging
• Flow Control
• Closing and Opening of the channel.

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A Interface BSSMAP Global BSSMAP procedure
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Abis Interface BTSM

• Task
• Random Access of the channel.
• Paging process of MS.
• Ciphering process of MS.
• Power Control of MS.

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Abis Interface BTSM Frame
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Abis Interface BTSM Frame

• Message Discriminator
• 1 for passes through BTS.
• 2-5 serve by BTS.