Mobile Network Architecturesuraj.lums.edu.pk/~cs5710s05/CS_CMPE_5710_Slides...5/10/2006...

5/10/2006 CS-CMPE-5710: Mobile Wireless Networks 1

Mobile Network Architecture

MSC

PSTN

ISDN

Internet

Voice/Data

Voice

Data

HLRVLR

AC

EIRAbis

Um

MAPn

MAPn

MS

BTS A

MS

BSC

HLR- Home Location RegisterVLR - Visitor Location registerMSC - Mobile Switching CenterBSC - Base Station Controller BTS - Base Transceiver Station AC - Authentication CenterEIR - Equipment Identity Register

BTS


Mobile Networks - Interface Protocols

Um - Air Interface; between MS and BSAbis - BTS and BSCA - BSS (BTS AND BSC) and BSC MAP - MSC and Network,

or MSC and HLR, VLR, EIR

TCAPMAPn

SCCP

Q.931+ ISUPTUP

DTAP, BSSMAPSCCP

LAPDmQ.931+

LAPDQ.931+ MTP3 MTP3

MTP2 MTP2MTP1Radio Int. T1/E1 MTP1

Abis A MAPUm

MTP- Message Transfer PartSCCP - Signaling Connection Control PartTCAP - Transaction Capabilities Application PartLAPD - Link Access Procedure, DLAPDm - LAPD for mobileBSSMAP- BSS management partDTAP - Direct Transfer Application Part


Major Components in a Mobile Network

MS MS -- Mobile StationMobile Stationmobile transceivermobile transceiver

runs application, control and management functions over the runs application, control and management functions over the air interfaceair interface

BS BS -- Base Station = BTS Base Station = BTS BTS BTS -- Base Transceiver StationBase Transceiver Station

manages air interface between MS and BTSmanages air interface between MS and BTSSlave of MSCSlave of MSCCommunicates to MS on MSC instructionsCommunicates to MS on MSC instructionsResponsible for power management across the AI (air Responsible for power management across the AI (air interface)interface)frequency administration between the BS and MS and power frequency administration between the BS and MS and power control together is Radio Resource (RR) Managementcontrol together is Radio Resource (RR) Management



MSC MSC -- Mobile Switching CenterMobile Switching CenterControl element of the Mobile Network. Responsible for:Control element of the Mobile Network. Responsible for:

Switching the calls to cellsSwitching the calls to cellsprovide backupsprovide backupsinterfacing with telephone or Data Networkinterfacing with telephone or Data Networkbilling informationbilling informationperformance testing, diagnostics and network managementperformance testing, diagnostics and network management

Connection Management (CM) functions are coordinated at Connection Management (CM) functions are coordinated at the MSCthe MSCMSC delegates some functions to BS or BSCMSC delegates some functions to BS or BSC

BSC BSC -- Base Station ControllerBase Station ControllerIf is used it controls BSIf is used it controls BSMay be coMay be co--located with BS or with MSClocated with BS or with MSC

typically with MSCtypically with MSC



Typical responsibilities are call handover and RR Typical responsibilities are call handover and RR managementmanagement

in this case, BS is mainly a bank of wireless modemsin this case, BS is mainly a bank of wireless modems

Databases in Mobile NetworksDatabases in Mobile NetworksHLR HLR -- Home Location RegistryHome Location Registry

Each HLR is associated with a Cellular Service ProviderEach HLR is associated with a Cellular Service ProviderEach subscriber belongs to one HLR Each subscriber belongs to one HLR keeps track of each subscriberkeeps track of each subscriberstores information about the subscriberstores information about the subscriber

is it on the air or not, i.e., subscriber active or inactiveis it on the air or not, i.e., subscriber active or inactivewhat services the user is subscribed to what services the user is subscribed to accounting informationaccounting information

VLR VLR -- Visitor Location RegistryVisitor Location Registrykeeps track of the visiting MSkeeps track of the visiting MSBoth HLR and VLR know the location of the MS if not in the Both HLR and VLR know the location of the MS if not in the default territorydefault territory



VLR informs the HLR when a visiting MS comes inVLR informs the HLR when a visiting MS comes inthis is handover related operationthis is handover related operation

HLR tells VLR about the subscriber info.HLR tells VLR about the subscriber info.

HLR and VLR are attached to MSC or BSC (if used)HLR and VLR are attached to MSC or BSC (if used)Operation of HLR and VLR is known as Operation of HLR and VLR is known as Mobility ManagementMobility ManagementAC AC -- Authentication ControlAuthentication Control

this database contains authentication and encryption this database contains authentication and encryption information for each subscriberinformation for each subscriberAC interacts with HLR and VLR while providing this serviceAC interacts with HLR and VLR while providing this service

EIR EIR -- Equipment Identity RegisterEquipment Identity RegisterInfo on MS Info on MS

manufacturermanufacturerconformance testingconformance testingmanufacturing factory identifiermanufacturing factory identifier

How to implementation of the these databasesHow to implementation of the these databases


Connection Management OperationsFixed phone dials a MSFixed phone dials a MSCall is routed to the gateway MSCCall is routed to the gateway MSCgateway MSC determines that it cannot route further so it asks fgateway MSC determines that it cannot route further so it asks for information to the HLRor information to the HLRThe HLR asks the VLR for verification and routing informationThe HLR asks the VLR for verification and routing informationVLR provides the routing info to HLR and it forwards it to MSCVLR provides the routing info to HLR and it forwards it to MSCGateway MSC routes the call to the terminating MSCGateway MSC routes the call to the terminating MSCTerminating MSC asks VLR to match the incoming call to the identTerminating MSC asks VLR to match the incoming call to the identity of the receiving ity of the receiving subscribersubscriberTerminating MSC sends the BS a paging request which relays the pTerminating MSC sends the BS a paging request which relays the page to the subscriber age to the subscriber and the call is completedand the call is completed


Mobility Management Operations

MS sends a location update request with its identification to thMS sends a location update request with its identification to the BS. The e BS. The message is routed to the new VLRmessage is routed to the new VLRThe new VLR sends the request to the visitorThe new VLR sends the request to the visitor’’s HLRs HLRHLR stores the new VLR for the user and then provides it the subHLR stores the new VLR for the user and then provides it the subscriber scriber informationinformationThe VLR sends the acknowledgement to the MSC through the new MSCThe VLR sends the acknowledgement to the MSC through the new MSC and the and the new MSnew MSHLR sends location cancellation message to the old VLR to clear HLR sends location cancellation message to the old VLR to clear the subscribers the subscribers data form its database.data form its database.


Use of Identifiers

Called party number is relayed to Gateway MSCCalled party number is relayed to Gateway MSCGateway MSC ask for the subscriber routing info from the HLRGateway MSC ask for the subscriber routing info from the HLRHLR contacts visited MSC and VLR about the subscriber locationHLR contacts visited MSC and VLR about the subscriber locationVLR sends the routing information about the subscriber back to HVLR sends the routing information about the subscriber back to HLR that send LR that send this info to the Gateway MSC. this info to the Gateway MSC. Gateway MSC routes the call directly to the MSC that is serving Gateway MSC routes the call directly to the MSC that is serving the subscriberthe subscriberInternal numbers may be used between MSCInternal numbers may be used between MSC’’s, HLR and VLRs, HLR and VLR


Relevant Protocols and Interfaces


Procedures on the Air Interface

NW MS

System AcquisitionPaging Request & Assignment

Service Request and Contention ResolutionAuthentication

Ciphering Mode SettingTransaction PhaseChannel Release


Procedures on the Air InterfaceSystem AcquisitionSystem Acquisition

happens on power onhappens on power onsearch for a control channelsearch for a control channelreceive and provide parametersreceive and provide parametersacquire timingacquire timingThe MS can now stay in idle state The MS can now stay in idle state

Paging Request and AssignmentPaging Request and Assignmentif a call is made to a MS, if a call is made to a MS,

NW sends paging requestNW sends paging requestMS responds MS responds NW provides sufficient information for control channels to useNW provides sufficient information for control channels to use

If MS makes a callIf MS makes a callon an access control channel, MS sends channel request messageon an access control channel, MS sends channel request messageif everything is OK, NW sends immediate assignment message if everything is OK, NW sends immediate assignment message identifying a dedicated channel for the serviceidentifying a dedicated channel for the service



Service request and contention resolutionService request and contention resolutionMS may be involved in contention resolution and send MS may be involved in contention resolution and send several messages for service request several messages for service request MS sends L2 SABM (Set Asynchronous Balanced Mode) MS sends L2 SABM (Set Asynchronous Balanced Mode) frame that may contains the service request message, CM frame that may contains the service request message, CM related, location update, or exchanging identifiers.related, location update, or exchanging identifiers.NW responds with UA (unnumbered acknowledgement) NW responds with UA (unnumbered acknowledgement) frame that contains the same message as the SABM frameframe that contains the same message as the SABM frameMS compares the UA with SABM MS compares the UA with SABM

if messages do not match, it leaves the channel, resolving if messages do not match, it leaves the channel, resolving contentioncontentionelse, it continueelse, it continuea random reference number is used for this operation so that a random reference number is used for this operation so that all MS are likely to send different reference numberall MS are likely to send different reference numberonly send nononly send non--confidential information to the NW that are used confidential information to the NW that are used in RR and MM functions of the networkin RR and MM functions of the network



AuthenticationAuthenticationAuthentication Request and Authentication Response Authentication Request and Authentication Response messagesmessagesNW send Areq message to the MS that includes info such as NW send Areq message to the MS that includes info such as keyskeysMS returns Ares message that contains the validation of the MS returns Ares message that contains the validation of the useruser’’s identitys identity

Ciphering mode settingCiphering mode settingCipher mode command, cipher mode completeCipher mode command, cipher mode completeTells the MS whether to use ciphering in the transaction Tells the MS whether to use ciphering in the transaction phase or not and what algorithm to use. phase or not and what algorithm to use. MS sends cipher mode complete messageMS sends cipher mode complete message

Transaction phaseTransaction phaseActual traffic flow such as voice call or data transfer Actual traffic flow such as voice call or data transfer



Channel releaseChannel releaseChannel release happens once the transactions are overChannel release happens once the transactions are overthe other side sends the channel release complete messagethe other side sends the channel release complete messageMS goes back to the idle modeMS goes back to the idle mode


GSM - MAP Interfaces

EIR

AC

HLR

VLR

VLR

MSC MSCMAP-E

MAP-B

MAP-D

MAP-C

MAP-H

MAP-F

MAP-G


GSM System - Protocol Architecture

MMDTAP, BSSMAP

TDMALAPDm

RR

T1/E1 or L1LAPDBTSM

MTP1MTP2MTP3SCCP

MTP1MTP2MTP3

CM

SCCP

Q.931+ ISUPTUP

Um Abis A MAPn

MMCM

TDMALAPDm

RR

T1/E1 or L1LAPDBTSM

BSSMAP, DTAP

MTP1MTP2MTP3

BTS BSC

Base Station System - BSS

MS MSC

To from other MSCs and networksTo from other

MSCs


TDMALAC

RR

AAL/ATM/PHYQ.SAAL LAC

BSM

SCCP

Um Abis A MAPn

MM

PHYLAC

RELAYQ.SAAL

RR

To from other MSCs

AAL/ATM/PHY

Q.2140MTP3CM BSMCM

CM BSCM

AAL/ATM/PHYQ.SAALQ.2140

MAP(HLR)

MTP3

TCAP -TCP/UDPConvergence

SCCP

PHYIP

TCP

AAL/ATM/PHYQ.SAAL

PHYLAC

RELAY

BSMCM

UDP

TCAP

APPLICATION

3rd Gen. Mobile Networks - IMT 2000

MS BTS BSC MSC

To from other MSCs and networks

HLR


GSM Addresses and Identifiers


GSM Channel Organization


GSM Authentication


GSM Encryption


Location Update


Initial Channel Usage


Call Establishment to MS


Location Update Operation


MS Originates the Call


MS Receives the Call

Mobile Network ArchitectureMobile Networks - Interface ProtocolsMajor Components in a Mobile NetworkMajor Components in a Mobile NetworkMajor Components in a Mobile NetworkMajor Components in a Mobile NetworkConnection Management OperationsMobility Management OperationsUse of IdentifiersRelevant Protocols and InterfacesProcedures on the Air InterfaceProcedures on the Air InterfaceProcedures on the Air InterfaceProcedures on the Air InterfaceProcedures on the Air InterfaceGSM - MAP InterfacesGSM System - Protocol Architecture3rd Gen. Mobile Networks - IMT 2000GSM Addresses and IdentifiersGSM Addresses and IdentifiersGSM Addresses and IdentifiersGSM Addresses and IdentifiersGSM Channel OrganizationGSM Channel OrganizationGSM Channel OrganizationGSM Channel OrganizationGSM Channel OrganizationGSM Channel OrganizationGSM Channel OrganizationGSM AuthenticationGSM EncryptionLocation UpdateInitial Channel UsageCall Establishment to MSLocation Update OperationMS Originates the CallMS Receives the Call

Mobile Network Architecturesuraj.lums.edu.pk/~cs5710s05/CS_CMPE_5710_Slides...5/10/2006...

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