call setup scenario

RNC RN1.5

Call Setup and Release DESCRIPTIONS

RNC3004_NOLSPDN99580908 Nokia Corporation 1 (52)Issue 2-0 en Nokia Proprietary and Confidential

Call Setup and Release

The information in this documentation is subject to change without notice and describes onlythe product defined in the introduction of this documentation. This documentation is intended

for the use of Nokia's customers only for the purposes of the agreement under which thedocumentation is submitted, and no part of it may be reproduced or transmitted in any form ormeans without the prior written permission of Nokia. The documentation has been prepared tobe used by professional and properly trained personnel, and the customer assumes fullresponsibility when using it. Nokia welcomes customer comments as part of the process ofcontinuous development and improvement of the documentation.The information or statements given in this documentation concerning the suitability, capacity,or performance of the mentioned hardware or software products cannot be considered bindingbut shall be defined in the agreement made between Nokia and the customer. However, Nokiahas made all reasonable efforts to ensure that the instructions contained in the documentationare adequate and free of material errors and omissions. Nokia will, if necessary, explain issueswhich may not be covered by the documentation.Nokia's liability for any errors in the documentation is limited to the documentary correction oferrors. NOKIA WILL NOT BE RESPONSIBLE IN ANY EVENT FOR ERRORS IN THISDOCUMENTATION OR FOR ANY DAMAGES, INCIDENTAL OR CONSEQUENTIAL(INCLUDING MONETARY LOSSES), that might arise from the use of this documentation orthe information in it.This documentation and the product it describes are considered protected by copyrightaccording to the applicable laws.NOKIA logo is a registered trademark of Nokia Corporation.Other product names mentioned in this documentation may be trademarks of their respectivecompanies, and they are mentioned for identification purposes only.

Copyright Nokia Corporation 2002. All rights reserved.2 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en

ContentsContents 3

List of tables 4

List of figures 5

1 Purpose of call setup and release 7

2 Functionality of real-time services 9

3 Functionality of non-real-time services 15

4 Call setup and release procedures 254.1 Paging 264.1.1 Paging an idle mode MS (paging procedure) 264.1.2 Paging a connected mode MS (UE dedicated paging procedure) 274.1.3 RNC originated paging 294.2 RRC connection setup 294.2.1 Directed RRC Setup 314.3 RRC connection release 314.4 Radio link setup 324.5 Radio link reconfiguration 334.6 Radio link deletion 354.7 Radio access bearer setup 364.8 Radio access bearer reconfiguration 384.9 Radio access bearer release 404.10 Signalling connection release 414.11 Direct transfer 434.12 Ciphering and integrity protection setup 444.13 Cell update 454.14 URA update 474.15 Parameters of call setup and release 484.16 Statistics of call setup and release 48

5 Related features of call setup and release 51DN99580908 Nokia Corporation 3 (52)Issue 2-0 en Nokia Proprietary and Confidential


List of tablesTable 1. MS cell states. 204 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en

List of figuresFigure 1. Mobile originated call (CS), 1/2. 10Figure 2. Mobile originated call (CS), 2/2. 11Figure 3. Mobile terminated call (CS), 1/2. 12Figure 4. Mobile terminated call (CS), 2/2. 13Figure 5. Mobile originated call (PS), 1/2. 16Figure 6. Mobile originated call (PS), 2/2. 17Figure 7. Mobile terminated call (PS), 1/2. 18Figure 8. Mobile terminated call (PS), 2/2. 19Figure 9. MS cell state transitions. 19Figure 10. CELL_DCH to CELL_FACH state transition using Radio Bearer

Reconfiguration. 21Figure 11. CELL_FACH to CELL_DCH UL state transition. 22Figure 12. CELL_FACH to CELL_DCH DL state transition. 23Figure 13. Cell update due to UL data transmission. 24Figure 14. Paging an MS in idle mode. 27Figure 15. Paging an MS in connected mode (CELL_FACH or CELL_DCH

state). 28Figure 16. Paging an MS in connected mode (CELL_PCH or URA_PCH state). 28Figure 17. RNC-originated paging. 29Figure 18. Setting up an RRC connection. 30Figure 19. RRC connection setup failure and retry. 30Figure 20. RRC connection release in CELL_DCH state. 31Figure 21. Radio link setup. 32Figure 22. Radio link setup failure. 33Figure 23. Synchronised radio link reconfiguration. 34Figure 24. Radio link reconfiguration failure. 35Figure 25. Radio link deletion. 35Figure 26. Radio access bearer establishment procedure (DCH to DCH). 37Figure 27. Failure in radio access bearer establishment. 38Figure 28. Radio access bearer reconfiguration procedure (DCH to DCH). 39DN99580908 Nokia Corporation 5 (52)Issue 2-0 en Nokia Proprietary and Confidential


Figure 29. Failure in radio access bearer reconfiguration. 40

Figure 30. Radio access bearer release. 41Figure 31. Signalling connection release requested by the CN. 42Figure 32. Signalling connection release requested by the MS (all flows are not

released). 43Figure 33. Signalling connection setup. 44Figure 34. Setting up ciphering and integrity protection. 45Figure 35. Cell update due to periodic update. 46Figure 36. Periodic URA update. 486 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en

Purpose of call setup and release1 Purpose of call setup and releaseCall setup and release refers to setting up or releasing a speech or data connectionbetween the end-user mobile station (MS) and the core network (CN). When theMS is in idle state, it has no radio resource control (RRC) connection to the radioaccess network. Radio resource control (RRC) connection is set up when the MSrequests it or when it is paged. The RRC connection is needed for radio accessbearer establishment. Radio access bearer services can involve a circuit switchedspeech call, a circuit switched data call or a packet switched call.

For more information, see:

2Functionality of real-time services

3Functionality of non-real-time services

Call setup and release procedures

Related featuresDN99580908 Nokia Corporation 7 (52)Issue 2-0 en Nokia Proprietary and Confidential

Call Setup and Release8 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en

Functionality of real-time services2 Functionality of real-time servicesReal-time services involve mobile-originated and mobile-terminated speech ordata calls. The following figures illustrate the process of establishing these twotypes of call. Individual procedures mentioned in the figures are described insection Call setup and release procedures.DN99580908 Nokia Corporation 9 (52)Issue 2-0 en Nokia Proprietary and Confidential

Call Setup and ReleaseFigure 1. Mobile originated call (CS), 1/2.

MS BTS RNC MSC

AAL2 Setup

RRC:RRC CONNECTION SETUP

RANAP:INITIAL UE MESSAGE

NBAP:SYNCHRONIZATION INDICATION

RRC:CONNECTION SETUP COMPLETE

RRC:INITIAL DIRECT TRANSFER

NBAP:RADIO LINK SETUP REQUEST

RRC:RRC CONNECTION REQUEST

NBAP:RADIO LINK SETUP RESPONSE

MS-CN signalling

RANAP:COMMON ID

MS-CN signalling

RANAP:SECURITY MODE COMMANDRRC:SECURITY MODE COMMAND

RRC:SECURITY MODE COMPLETE

RANAP:SECURITY MODE COMPLETE

L1 synchronisation10 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en

Functionality of real-time services

MS BTS RNCMS MSCFigure 2. Mobile originated call (CS), 2/2.

The following figure illustrates the mobile terminated circuit switched call. Theonly difference between a mobile originated and mobile terminated call is thatonly mobile terminated calls include paging the MS.

AAL2 Setup

RANAP:RAB ASSIGNMENT REQUEST

NBAP:RADIO LINK RECONFIGURATION PREPARE

NBAP:RADIO LINK RECONFIGURATION READY

AAL2 Setup

Connection established

NBAP:RADIO LINK RECONFIGURATION COMMIT

RRC:RADIO BEARER SETUP

RRC:RADIO BEARER SETUP COMPLETE

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Call Setup and ReleaseFigure 3. Mobile terminated call (CS), 1/2.

MS BTS RNC MSC

AAL2 Setup









MS-CN signalling

RANAP:COMMON ID

MS-CN signalling




RRC: PAGING TYPE 1

RANAP: PAGING


Functionality of real-time services

MS BTS RNCMS MSCFigure 4. Mobile terminated call (CS), 2/2.

For the whole topic summary, see

AAL2 Setup




AAL2 Setup

Connection established





Functionality of non-real-time services3 Functionality of non-real-time servicesNon-real-time services involve packet switched data calls. For NRT (non-realtime) services, the radio access bearer is created without immediately reservingradio resources. The resources are allocated on demand by using the signallinglink between the MS and the RNC. The following figures illustrate the process ofestablishing a packet switched call.DN99580908 Nokia Corporation 15 (52)Issue 2-0 en Nokia Proprietary and Confidential

Call Setup and ReleaseFigure 5. Mobile originated call (PS), 1/2.

MS BTS RNC SGSN

AAL2 Setup









MS-CN signalling

RANAP:COMMON ID

MS-CN signalling





Functionality of non-real-time services

MS BTS RNCMS SGSNFigure 6. Mobile originated call (PS), 2/2.

The following figure illustrates the mobile terminated packet switched call. Theonly difference between mobile originated and mobile terminated calls is thatonly mobile terminated calls include paging the MS.


GTP Tunnel setup

Connection established (CELL_DCH state)




Call Setup and ReleaseFigure 7. Mobile terminated call (PS), 1/2.

MS BTS RNC SGSN

AAL2 Setup









MS-CN signalling

RANAP:COMMON ID

MS-CN signalling




RRC:PAGING TYPE 1

RANAP: PAGING



MS BTS RNCMS SGSNFigure 8. Mobile terminated call (PS), 2/2.

When the MS has a dedicated physical channel, it is in CELL_DCH state. Statetransitions are illustrated in the following figure:

Figure 9. MS cell state transitions.


GTP Tunnel setup

Connection established (CELL_DCH state)



RANAP:RAB ASSIGNMENT RESPONSE

URA_PCH

CELL_DCH

Idle Mode

CELL_FACH

RAN Connected Mode

CELL_PCH

Release RRC connectionRelease RRC connectionEstablish RRC connectionDN99580908 Nokia Corporation 19 (52)Issue 2-0 en Nokia Proprietary and Confidential

Call Setup and ReleaseWhen the RNC detects inactivity in either uplink or downlink, it starts aninactivity timer in that direction. If the timer in both directions expires and theinactivity continues, the RNC releases the dedicated resources and starts the MS'stransition from CELL_DCH to CELL_FACH state. The transition is usually donewith the radio bearer reconfiguration procedure. In some special cases it is donewith either the physical channel reconfiguration procedure or the radio bearerrelease procedure.

The radio bearer reconfiguration procedure is used, if the radio link control (RLC) parameters of the NRT RB need to be reconfigured when the DCH of the NRTRB is released.

The physical channel reconfiguration procedure is used, if the DCH of the NRTRB is released, and there are no other DCH allocations.

The radio bearer release procedure is used when a NRT RAB and a RT RAB aresimultaneously used for the same MS, and the NRT RAB has been inactive (theinactivity timer has expired) when the CN releases the RT RAB.

The following figure illustrates the state transition using radio bearerreconfiguration:

Table 1. MS cell states.

MS cell state Description

CELL_DCH MS receives and transmits on the dedicated trafficchannel (DCH). The location of the MS is known on celllevel.

CELL_FACH MS receives on the forward access channel (FACH)and transmits on the random access channel (RACH).The location of the MS is known on cell level.

CELL_PCH MS receives on the paging channel (PCH). Thelocation of the MS is known on cell level. If the MS hassomething to transmit, it transfers to CELL_FACH state.

URA_PCH MS receives on the paging channel (PCH). Thelocation of the MS is known on URA level. If the MS hassomething to transmit, it transfers to CELL_FACH state.20 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en


RNCMS BTSFigure 10. CELL_DCH to CELL_FACH state transition using Radio BearerReconfiguration.

The transition from CELL_FACH state to CELL_DCH state is started when theRNC has user or control data waiting for transmission in downlink direction orwhen the MS requests capacity for user data in uplink direction. The RNC's RM(resource manager) checks that there are resources available and allocates therequested resources. It also requests a radio link setup procedure (refer to sectionRadio link setup).

Once a radio link is set up, the transition is done either with the transport channelreconfiguration procedure, the radio bearer reconfiguration procedure, or theradio bearer setup procedure.

The transport channel reconfiguration procedure is used, if a state transition isneeded and it does not need reconfiguration.

The radio bearer reconfiguration procedure is used, if the radio link control (RLC)parameters of the NRT RB need to be reconfigured.

MS is in CELL_DCH state

Inactivity timer expires

RRC:RADIO BEARER RECONFIGURATION

RRC:RADIO BEARER RECONFIGURATION COMPLETE

MS is in CELL_FACH state

NBAP: RADIO LINK DELETION REQUEST

NBAP: RADIO LINK DELETION RESPONSE

CELL UPDATE CONFIRM

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The radio bearer setup procedure is used, if a NRT RAB already exists and a newRT RAB must be established.The following figure illustrates the state transition from CELL_FACH toCELL_DCH:

Figure 11. CELL_FACH to CELL_DCH UL state transition.

RNCMS BTS


RRC: RADIO BEARER RECONFIGURATION

RRC: RADIO BEARER RECONFIGURATION COMPLETE

NBAP Radio Link Setup

RRC:MEASUREMENT REPORT

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RNCMS BTSFigure 12. CELL_FACH to CELL_DCH DL state transition.

Uplink data transmission may cause a cell update as illustrated in the figurebelow.


RRC: RADIO BEARER RECONFIGURATION

RRC: RADIO BEARER RECONFIGURATION COMPLETE

NBAP Radio Link Setup

MS is in CELL_DCH state

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RNCMS BTSFigure 13. Cell update due to UL data transmission.

For the whole topic summary, see

UL capacity need is detected by MAC

MS moves to CELL_FACH state

MS is in CELL_PCH state or URA_PCH state

RRC:CELL UPDATE CONFIRM

RRC:CELL UPDATE

RRC:UTRAN MOBILITY INFORMATION CONFIRM

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Call setup and release procedures4 Call setup and release proceduresThis section describes the procedures involved in real-time and non-real-time callsetup and release. See sections Functionality of real-time services andFunctionality of non-real-time services for the illustration of call setup andrelease phases. This section also briefly describes parameters and statistics.

The signalling protocols mentioned in the figures are:

RANAP (radio access network application part) RNSAP (radio network subsystem application part) NBAP (Node B application part) RRC (radio resource control)RANAP layer

RANAP layer includes all the RANAP signalling entities of the RNC and therelated application for RANAP signalling entity management.

RANAP signalling entity is a serving RNC functionality responsible for theRANAP-connection-specific signalling and information management betweenthe RNC and core network for one MS.

RNSAP layer

RNSAP layer includes all the RNSAP signalling entities of the RNC and therelated application for RNSAP signalling entity management.

RNSAP signalling entity is an RNC functionality responsible for RNSAP-connection-specific signalling and information management between two RNCsfor one MS.

NBAP layer

NBAP layer includes all common and dedicated NBAP signalling entities of theRNC or the BTS and the related application for the NBAP signalling entitymanagement.DN99580908 Nokia Corporation 25 (52)Issue 2-0 en Nokia Proprietary and Confidential


Common NBAP signalling entity is a BTS or a controlling RNC functionalityresponsible for the logical resource management, BCH management and

communication context creation for one BTS.

Dedicated NBAP signalling entity is a BTS or a controlling RNC functionalityresponsible for the radio link management for a group of MSs.

RRC layer

RRC layer includes all RRC signalling entities of the RNC and the relatedapplication for RRC signalling entity management.

RRC signalling entity is a serving RNC functionality responsible for the RRC-connection-specific signalling and information management for one MS.

4.1 Paging

Core network (CN) requests the RNC to page an MS. RNC receives pagingrequests from the core network over the Iu interface.

The MS may use discontinuous reception (DRX) in idle mode to reduce powerconsumption. In discontinuous transmission, the MS only monitors one pageindicator (PI) in one paging occasion per DRX cycle. The DRX cycle is anindividual time interval between the monitoring paging occasions for a specificMS. The maximum DRX cycle is the time interval for the longest possible DRXcycle in a cell.

The MS may be attached to the circuit switched and packet switched corenetworks with different CN-domain-specific DRX cycle lengths. The MS storeseach domain-specific DRX cycle length for each CN domain it is attached to anduses the shortest of those DRX cycle lengths. If the CN sends a specific DRXcycle length coefficient, RAN uses it in the paging message. If there is no CN-specific coefficient, RAN uses the default value for CN-specific DRX cyclelength coefficient in the radio network database.

RNC sends paging requests to all WCDMA BTSs which belong to the pagingarea where the MS is currently registered. The cells in a single BTS may belongto different paging areas.

Each paging message on the Iu interface involves only one MS and therefore, theRNC has to pack the pages into the relevant radio interface paging message.

4.1.1 Paging an idle mode MS (paging procedure)The RNC checks whether the paged MS is engaged in an ongoing radio resourcecontrol (RRC) connection. If there is no connection, the RNC starts the idle modepaging procedure. As a result, the MS starts the RRC connection setup procedure.26 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en


The procedure using the PAGING TYPE 1 message is referred to as pagingprocedure in the 3GPP RRC specification.Figure 14. Paging an MS in idle mode.

4.1.2 Paging a connected mode MS (UE dedicated paging procedure)The RNC checks whether the paged MS already has an RRC connection. If itdoes, the connected mode paging procedure is applied. RNC sends a pagingmessage (RRC:PAGING TYPE 2) to an RRC-connected MS through the existingRRC connection if the MS is in CELL_DCH or CELL_FACH state. If the MS isin CELL_PCH or URA_PCH state, the RNC originates the paging procedure(RRC:PAGING TYPE1).

The procedure using the PAGING TYPE 2 message is referred to as UE dedicatedpaging procedure in the 3GPP RRC specification.

CNMS BTS

PAGING TYPE 1

RANAP:PAGING

MS has no RRC connection

RRC connection establishment

Paging response

RNCDN99580908 Nokia Corporation 27 (52)Issue 2-0 en Nokia Proprietary and Confidential


CN 2MS BTS RNC CN 1Figure 15. Paging an MS in connected mode (CELL_FACH or CELL_DCHstate).

Figure 16. Paging an MS in connected mode (CELL_PCH or URA_PCH state).

MS has signalling connection to CN1

MS is in CELL_FACH or CELL_DCH state

Paging response to CN 2

RRC:PAGING TYPE 2

RANAP:PAGING

CN 2MS BTS RNC CN 1

MS has signalling connection to CN1

MS is in CELL_PCH or URA_PCH state

Paging response to CN 2

RRC:PAGING TYPE 1

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4.1.3 RNC originated pagingTo save its battery, an MS may reside on common channels (the paging channel)while still maintaining the RRC connection to RNC. In such a case, the RNCneeds to page the MS when there is downlink user data or a downlink signallingmessage addressed to the MS. This is because in CELL_PCH or URA_PCH state,the DCCH logical channel cannot be used. Therefore, the RNC transmits a pagingrequest on the PCCH logical channel in the known cell or within the URA wherethe MS is located. RNC's RRC signalling entity starts the paging procedure. As aresponse, the MS moves to the CELL_FACH state and starts the cell updateprocedure with the cause paging response.

If an MS in CELL_PCH or URA_PCH state needs to transmit anything to theRAN, it moves to the CELL_FACH state and executes a cell update procedurewith the cause UL data transmission.

Figure 17. RNC-originated paging.

4.2 RRC connection setup

RRC connection is always started by the MS. MS sends a message to the RNCrequesting RRC connection setup. RNC sets up a radio link and sends the MS thephysical channel information. After the MS has synchronised itself to theWCDMA BTS, it transmits an acknowledgement to the RNC.

Once the MS has set up the RRC connection, it may send higher-layer messages,for instance, a call setup message.

MS BTS RNC

MS is in CELL_PCH or URA_PCH state

RRC: PAGING TYPE 1

DL data or DL signalling messages

MS makes a transition from CELL_PCH or URA_PCH to CELL_FACH state

MS performs a cell update with the cause "paging response"DN99580908 Nokia Corporation 29 (52)Issue 2-0 en Nokia Proprietary and Confidential


RNCMS BTSFigure 18. Setting up an RRC connection.

The following figure illustrates an example of an RRC connection failure. TheRNC may fail in its attempt to set up a radio link due to hardware blocking, forinstance. Also, admission control may reject the setup attempt. In an errorsituation, the RNC transmits an RRC connection setup reject message, and theMS initiates an RRC connection setup retry timer. When the timer expires, theMS attempts to set up the RRC connection again.

Figure 19. RRC connection setup failure and retry.

RRC: RRC CONNECTION SETUP

L1 synchronisation

Radio link setup

RRC: RRC CONNECTION SETUP REQUEST

RRC: RRC CONNECTION SETUP COMPLETE

MS BTS RNC

RRC: RRC CONNECTION REJECT

RRC: RRC CONNECTION SETUP REQUEST

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4.2.1 Directed RRC SetupDirected RRC connection setup provides an efficient way to balance the loadbetween two (or more) carrier frequencies (cells having equal coverage areas)within one BS. The RNC balances the load by establishing an RNC connectionon the carrier frequency (cell) which has the less load. The admission control ofRNC makes a decision on whether to perform the Directed RRC connection setupprocedure. Directed RRC connection setup is controlled with RNP parameters.

4.3 RRC connection release

Radio resource control connection is released when the MS no longer has anactive signalling connection to any core network node. MS and CN negotiateabout the release, and after that, the CN sends a release command. The MS inCELL_DCH state sends an acknowledgement message in unacknowledged modeto the radio access network. If the MS receives the release message while inCELL_FACH state, it responds in acknowledged mode to the RAN.

After the MS response, the RNC starts the radio link release procedure towardsBTS, releases transport bearers on the Iub interface, and sends anacknowledgement to the core network. The RNC can delete the RRC entity of theMS at the same time with the radio link release procedures.

Figure 20. RRC connection release in CELL_DCH state.

MS BTS RNC CN

MS has signalling connection to one CN

Radio link deletion procedure

RANAP: IU RELEASE COMMAND

RRC: RRC CONNECTION RELEASE

RANAP: IU RELEASE COMPLETE

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4.4 Radio link setupRadio link setup procedure is started when a new radio link is needed, forinstance, when a new signalling link is set up or when handover is performed.RNC determines the radio link parameters and requests radio link activation at theBTS. In the first radio link setup, the BTS selects the traffic termination point forthe communication context and sends the identification of the associated NBAPsignalling link to the RNC. The radio link allocation is valid at the BTS until theRNC orders radio link deletion.

The procedure also starts the creation or modification of a communicationcontext. Communication context contains information about all activity in onetraffic termination point concerning one MS. It is used to associate a set of radiolinks together at the BTS.

Figure 21. Radio link setup.

Error situations that may occur during radio link setup are illustrated in thefollowing figures. Radio link setup may fail because resources are not availableor because the controlling RNC communication context is already in use, forexample. If radio link setup fails, the BTS sends a failure message to the RNCindicating the cause value. The BTS's L3 Common NBAP signalling entity sendsthe message to the RNC's L3 Common NBAP signalling entity.


AAL2 Setup


RRC:Assignment to MS

L1 synchronisation

MS RNCBTS

NBAP:SYNCHRONIZATION INDICATION32 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en


MS BTS RNCFigure 22. Radio link setup failure.

4.5 Radio link reconfiguration

Synchronised radio link reconfiguration is used to add, delete or modify a DCH(dedicated channel) or to modify the radio links belonging to the samecommunication context. The resource manager of the RNC initiates thereconfiguration procedure.

The situations that may trigger the radio link reconfiguration procedure are:

radio access bearer setup (AAL2 setup) radio access bearer negotiation (possible AAL2 setup, switching, and

release) radio access bearer release (AAL2 release) NRT radio access bearer scheduling (AAL2 setup, possible AAL2

switching, AAL2 release).

NBAP:RADIO LINK SETUP FAILURE

NBAP:RADIO LINK SETUP REQUESTDN99580908 Nokia Corporation 33 (52)Issue 2-0 en Nokia Proprietary and Confidential


MS BTS RNCFigure 23. Synchronised radio link reconfiguration.

Radio link reconfiguration may fail because of a BTS capability failure orbecause there are not enough resources, for example. The BTS responds with afailure message to the RNC's prepare message. The failure message indicates thefailed radio links and the cause value for the failure.


AAL2 Setup if needed

RRC:Assignment to MS


AAL2 Switching if needed

AAL2 Release if needed

NBAP:RADIO LINK RECONFIGURATION PREPARE34 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en


MS BTS RNCFigure 24. Radio link reconfiguration failure.

4.6 Radio link deletion

RNC starts the radio link deletion procedure to release one or more radio links ina communication context. Resets and other error situations may trigger thisprocedure.

If the RNC does not receive a response from the BTS before a timer expires, itsends the deletion message again three times. After that, if there is still no answer,the resource manager in the RNC starts recovery actions.

Figure 25. Radio link deletion.

NBAP:RADIO LINK RECONFIGURATION FAILURE


MS BTS RNC

AAL2 Release

NBAP:RADIO LINK DELETION REQUEST

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4.7 Radio access bearer setupThe procedure builds a radio access bearer service between the MS and the CN(core network). The service is negotiated between MS and CN via the signallinglink between the MS and RAN (radio access network) and via the signallingconnection between RAN and CN.

Once the CN has all the necessary information, it forwards it to the RNC. RNCanalyses the parameters for radio access bearer service and checks whether theresources needed exist. After that, the RNC activates or modifies the physicaluplink and downlink radio channels from the WCDMA BTS and creates thetransmission channels at the Iub and Iur interfaces according to the reserved radioresources.

RNC then sends the new radio link parameters to the MS on the existingsignalling link. Once the MS informs the RNC that it uses the new radio linkparameters, the RNC acknowledges the information to the CN and radio accessbearer establishment is then complete.

The same procedure is also used for adding radio access bearers.

For NRT (non-real time) services, the radio access bearers are created withoutimmediate reservation of radio resources. Instead, radio resources are allocatedon demand by using the signalling link between the MS and the RNC.36 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en


BTS RNC CNMSFigure 26. Radio access bearer establishment procedure (DCH to DCH).

Setting up a radio access bearer may fail, for instance, because the RNC cannotprovide the resources requested. If the requested channel type or resource (forexample channel rate) indicated in the RANAP:RAB ASSIGNMENT REQUESTmessage is not available in the RAN, a RANAP:RAB ASSIGNMENTRESPONSE message is sent to the CN. The message contains the appropriatefailure cause.

Signalling link established, MM and CC signalling ...

AAL2 Setup (real time RAB)

CC continues...

RANAP:RAB Assignment Request

RANAP:RAB Assignment Response

RRC:RB Setup

RRC:RB Setup Complete

Radio link reconfiguration(real time RAB)

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RNC CNFigure 27. Failure in radio access bearer establishment.

4.8 Radio access bearer reconfiguration

The MS and CN negotiate about the radio access bearer reconfiguration. MS orCN can request the procedure for radio access bearer reconfiguration. Theprocedure is the same whether MS or CN requests the modification.

If downgrading the radio access bearer parameters is requested, the CNimmediately accepts it and acknowledges the service modification to the MS. TheCN then requests the RNC to modify the RAN radio access bearer. If themodification is allowed, the MS and the WCDMA BTS are informed, and alsothe transmission channels are modified if needed. The RAN acknowledges to theCN that the radio access bearer service was modified.

If upgrading the radio access bearer parameters is requested, the CN first requeststhe RNC to modify radio access bearer services. If the modification is allowed,the MS and WCDMA BTS are informed, and also the transmission channels aremodified if needed.

Required resourcesnot available

RANAP:RAB Assignment Request

RANAP:Assignment Response(cause)

CN may send a new RAB AssignmentRequest to establish a new RAB orIu release Command to release allreserved resources.38 (52) Nokia Corporation DN99580908Nokia Proprietary and Confidential Issue 2-0en


BTS RNC CNMSFigure 28. Radio access bearer reconfiguration procedure (DCH to DCH).

If the requested channel type or resource (for example channel rate) indicated inthe RANAP:RAB ASSIGNMENT REQUEST message is not available in theRAN, a RANAP:RAB ASSIGNMENT RESPONSE message is sent to the CN.The message contains the appropriate failure cause.

AAL2 modification

RRC:RB Reconfiguration Complete

RANAP:RAB Assignment Request (modify)

CC/SM signalling, modification complete


CC/SM signalling between MS and CN, modification of RAB required

RRC:RB Reconfiguration

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MS BTS RNC CNFigure 29. Failure in radio access bearer reconfiguration.

4.9 Radio access bearer release

The MS and CN negotiate about releasing the radio access bearer services. TheCN then commands the RAN (radio access network) to release a radio accessbearer service. RNC sends an indication of the release to the MS, and eitherreleases the radio link or modifies the radio link parameters if all radio accessbearers are not released.

The radio links are also released or modified at the WCDMA BTS, andtransmission channels are released both on the Iu and Iub interfaces. Also Iurbranches are released if the MS had branches via another (drifting) RNC.

The CN may also request releasing the signalling link if all radio access bearersrelated to the CN are released. Then the signalling connection between the RNCand CN is released. The signalling link between the RNC and MS is also releasedif the MS has no active connection to another CN.

CC/SM signaling between MS and CN, modification of Radio Access Bearer required

RL reconfiguration

AAL2 modification

RANAP:RAB AssignmentRequest (modify)

RRC:RB Reconfiguration

RANAP:RAB Assignment Response (cause)

RRC:RB Reconfiguration Failure

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BTS RNC CNMSFigure 30. Radio access bearer release.

From the Iu interface's point of view, radio access bearer release is alwayssuccessful. The MS may return a release failure message to the RNC. In this case,the MS uses the old configuration.

4.10 Signalling connection release

Signalling connection release can be requested by the CN or by the MS. The MSmay have an ongoing signalling connection to one circuit-switched and onepacket-switched core network simultaneously. If one network then requests therelease of the signalling connection by running the Iu release procedure, the RNCdetects that there is still another signalling connection using the current RRCconnection. The RRC connection is not released, but the MS is informed that oneof the signalling connections is released.

AAL2 release

RL Reconfiguration

AAL2 release

RANAB:RAB Assignment Request (release)


RRC:RB Release

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RNC CN 1 CN 2BTSMSFigure 31. Signalling connection release requested by the CN.

When the MS requests the release of a signalling connection, either the signallingconnection release or the RRC connection release procedure is run. The numberof current signalling connections determines which of these release procedures isrun. If the MS has two signalling connections then the signalling connectionrelease procedure is run (as in the figure) and the MS continues to have asignalling connection to one core network. If the MS has only one signallingconnection from before, then the RRC connection release procedure is run afterwhich the MS no longer is connected to any core network.

MS-CN 1 signalling connection



RANAP:IU RELEASE COMMAND

RANAP:IU RELEASE COMPLETE

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RNC CN 1 CN 2BTSMSFigure 32. Signalling connection release requested by the MS (all flows are notreleased).

4.11 Direct transfer

After having established an RRC connection, the MS starts setting up a signallingconnection to the core network (CN). MS sends a message to the RNC whichgenerates a different message to the CN, depending on whether or not there is anactive signalling connection to the CN domain.

If low priority DCCH usage is configured in the RNC, SRB#4 (low priority) isused in the downlink direction for the NAS-PDUs using SAPI value 3. If lowpriority DCCH usage is not configured, or the SAPI value of a NAS-PDU is 0,then SRB#3 (high priority) is used.

If the RNC fails in transferring the message to the MS, the CN does not get anindication of the failure. Higher layers are used to repeat the message.




RANAP:IU RELEASE REQUEST

RANAP:IU RELEASE COMPLETE

RRC:SIGNALLING CONNECTION RELEASE REQUEST

Release of one signalling flow

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MS BTS RNC CNFigure 33. Signalling connection setup.

4.12 Ciphering and integrity protection setup

In RNC, two security mechanisms are available: ciphering and integrityprotection. When RRC connection has been set up, the MS sends the RRCCONNECTION SETUP COMPLETE message to the RNC. The messageincludes the HFN (hyperframe number) to be used as part of the input parametersfor the ciphering and integrity algorithms, respectively.

The MS sends an initial L3 message with the MS Classmark information whichthe network needs to start security mode setup. The message is unprotected, butthe MS can verify that the correct information reached the network when thesystem returns a protected message including the MS Classmark received. Thispart is transparent to the radio access network.

Once the initial L3 message is received, user authentication can be done and newsecurity keys (integrity key and ciphering key) as well as a new key set identifier(KSI) are generated. The core network also determines which UMTS encryptionand integrity algorithms (UEAs and UIAs) are used.

Core network starts integrity protection (and possibly ciphering) by sending theSECURITY MODE COMMAND message to the serving RNC. This messagecontains the UIAs and the integrity key (IK) to be used and possibly the UEAsand the ciphering key (CK).

RRC: INITIAL DIRECT TRANSFER

RANAP: INITIAL UE MESSAGE

RANAP: DIRECT TRANSFER

RRC: DOWNLINK DIRECT TRANSFER

RRC: UPLINK DIRECT TRANSFER

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The serving RNC selects the first UIA and UEA it supports from the CN's list.SRNC generates a random value FRESH and starts the downlink integrity

protection by generating the SECURITY MODE COMMAND message. Basedon input parameters, the RNC generates the message authentication code forintegrity protection (MAC-I) which is included in the message. All downlinksignalling messages after that are integrity protected and possibly ciphered.

If SRNC supports no UIAs on the list, it sends a rejection message to the corenetwork.

The MS computes the expected MAC-I value (XMAC-I) and verifies the integrityof the message by comparing the received MAC-I with the generated XMAC-I.The MS acknowledges the RNC's message with SECURITY MODECOMPLETE message which starts the uplink integrity protection. All uplinksignalling messages after that are integrity protected and possibly ciphered.

Figure 34. Setting up ciphering and integrity protection.

4.13 Cell update

Cell update procedure is mainly used to update the RNC information on the MSlocation after a cell reselection. When the MS selects a new cell, it informs theRNC in a cell update. In other words, cell update is used instead of handover. TheMS also performs periodic cell updates according to system information.

After the MS has switched to a new cell, it sends a cell update message to theRNC's RRC (radio resource control). The MS message contains the cell updatecause, which can be:

cell reselection

periodic cell update

uplink data transmission

MS BTS RNC CN



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paging response re-entering service area

radio link failure

RLC unrecoverable error.

If the cell update was caused by cell reselection, the RNC updates the MS locationinformation and resets the CELL_FACH or CELL_PCH state supervision timer.RNC's confirmation message to the MS includes a radio network temporaryidentifier for the cell (C-RNTI). If the cell update was performed to a cell notresiding under the serving RNC (SRNC), the message also contains the radionetwork temporary identifier for the RAN (U-RNTI). If the MS is moving veryfast and performs frequent cell updates due to cell reselection, the RNC may orderthe MS to move to URA_PCH state.

If the cause was a periodic cell update, the RNC updates the MS locationinformation and resets the CELL_FACH or CELL_PCH state supervision timer.RNC may also instruct the MS to update its location on URA level.

If the cause was uplink data transmission, the RNC sends a confirmation andpossibly a radio network temporary identifier (C-RNTI). The RNTI for RAN (U-RNTI) is sent if the cell update was performed to a cell not residing under theserving RNC (SRNC). The MS remains in CELL_FACH state.

If the cell update cause was paging response, the RNC updates the MS locationinformation. The RNC sends a confirmation and possibly a new radio networktemporary identifier for cell (C-RNTI). The MS remains in CELL_FACH state.

Figure 35. Cell update due to periodic update.

RRC:CELL UPDATE

RRC:CELL UPDATE CONFIRM

RNCMS BTS

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4.14 URA updateMS mainly uses the UTRAN registration area (URA) update procedure to informthe RNC that it has switched to a new radio access network registration area. Theprocedure is triggered after a change of cell when the MS has decoded the URAidentifiers of the cell. URA updates are also performed periodically after a timerexpires.

RAN (UTRAN) registration areas may be hierarchical to avoid excessivesignalling. This means that several URA identifiers may be broadcast in one celland that different MSs in one cell may reside in different URAs.

When the MS is in URA_PCH state and has switched to a new URA, it sends anupdate message with the U-RNTI (radio network temporary identifier) and URAupdate cause to the RNC. The cause is either URA reselection or periodic URAupdate.

If the update was due to URA reselection, the RNC registers the change of URAand sends a confirmation message to the MS. The message includes a radionetwork temporary identifier for cell (C-RNTI), if the MS remains inCELL_FACH state after the URA update. The message includes a radio networktemporary identifier for RAN (UTRAN, U-RNTI), if the URA update wasperformed to a cell not residing under the serving RNC (SRNC).

If multiple URAs are valid in the cell, RNC assigns the URA to the MS.

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RNCMS BTSFigure 36. Periodic URA update.

4.15 Parameters of call setup and release

For operator-definable parameters, see Radio Network Parameter Dictionary.

4.16 Statistics of call setup and release

The following measurement types are relevant to call setup and release:

Service level measurements

Measurement includes statistics collected from:

RRC connection setup and access (including RRC connection activereleases and failures)

Incoming HOs and relocations

RAB setup, access and reconfiguration.

For more information, see Radio Network Measurements in RNC PerformanceCounters.

MS is in URA_PCH state

RRC:URA UPDATE

RRC:URA UPDATE CONFIRM

MS moves to URA_PCH state

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L3 signalling measurements on IubMeasurement includes statistics collected from:

NBAP procedures for radio link setup, addition, deletion andreconfiguration.

For more information, see Radio Network Measurements in RNC PerformanceCounters

L3 signalling measurements on Iur


RNSAP procedures for radio link setup, addition, deletion andreconfiguration over Iur

For more information, see Radio Network Measurements in RNC PerfromanceCounters

L3 Relocation signalling measurement


RNSAP and RANAP procedures for serving RNC relocation

RNSAP and RANAP procedures for inter-RNC hard handover

For more information see Radio Network Measurements in RNC PerformanceCounters

L3 signalling measurements on Iu


RANAP procedures for radio access bearer establishment/release and Iuconnection setup/release.

For more information, see Radio Network Measurements in RNC PerformanceCounters

RRC signalling measurements


RRC connection management (that is, RRC connection setup/release,paging) procedures

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Related features of call setup and release5 Related features of call setup andrelease

The features related to call setup and release are:

Handover control algorithm

Power control algorithm

Load control algorithm

Admission control algorithm

Resource manager algorithm

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Call Setup and Release1 Purpose of call setup and release2 Functionality of real-time services3 Functionality of non-real-time services4 Call setup and release procedures4.1 Paging4.1.1 Paging an idle mode MS (paging procedure)4.1.2 Paging a connected mode MS (UE dedicated paging procedure)4.1.3 RNC originated paging

4.2 RRC connection setup4.2.1 Directed RRC Setup

4.3 RRC connection release4.4 Radio link setup4.5 Radio link reconfiguration4.6 Radio link deletion4.7 Radio access bearer setup4.8 Radio access bearer reconfiguration4.9 Radio access bearer release4.10 Signalling connection release4.11 Direct transfer4.12 Ciphering and integrity protection setup4.13 Cell update4.14 URA update4.15 Parameters of call setup and release4.16 Statistics of call setup and release

5 Related features of call setup and release

call setup scenario

Documents