8.4 Common Transport Channel Procedures

25.4233GPPRelease 17TSUTRAN Iur interface Radio Network Subsystem Application Part (RNSAP) signalling

8.4.1 Common Transport Channel Resources Initialisation

8.4.1.1 General

The Common Transport Channel Resources Initialisation procedure is used by the SRNC for the initialisation of the Common Transport Channel user plane towards the DRNC and/or for the initialisation of the Common Transport Channel resources in the DRNC to be used by a UE.

This procedure shall use the connectionless mode of the signalling bearer.

8.4.1.2 Successful Operation

Figure 27: Common Transport Channel Resources Initialisation procedure, Successful Operation

The SRNC initiates the procedure by sending the message COMMON TRANSPORT CHANNEL RESOURCES REQUEST message to the DRNC.

If the value of the Transport Bearer Request Indicator IE is set to “Bearer Requested”, the DRNC shall store the received Transport Bearer ID IE. The DRNC may use the Transport Layer Address and Binding ID IEs included in the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message received from the SRNC when establishing a transport bearer for the common transport channel. In addition, the DRNC shall include its own Binding ID IE and Transport Layer Address IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message.

If the TNL QoS IE is included and if ALCAP is not used, the TNL QoS IE may be used by the DRNC to determine the transport bearer characteristics to apply in the uplink between the DRNS and the SRNC for the related common transport channels.

If the value of the Transport Bearer Request Indicator IE is set to” Bearer not Requested”, the DRNC shall use the transport bearer indicated by the Transport Bearer ID IE.

If the C-ID IE is included in the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message, the DRNC shall allocate a C-RNTI for the indicated cell and include the C-RNTI IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message.

If the C-ID IE is included in the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message, the DRNC shall include the FACH Info for UE Selected S-CCPCH IE valid for the cell indicated by the C-ID IE and the corresponding C-ID IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message. If the C-ID IE is not included in the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message, the DRNC shall include the FACH Info for UE Selected S-CCPCH IE valid for the cell where the UE is located and the corresponding C-ID IE. The DRNC shall include the FACH Scheduling Priority IE and FACH Initial Window Size IE in the FACH Flow Control Information IE of the FACH Info for UE Selected S-CCPCH IE for each priority class that the DRNC has determined shall be used. The DRNC may include several MAC-c/sh SDU Length IEs for each priority class.

If the DRNS has any RACH and/or FACH [FDD – and/or HS-DSCH] [1.28Mcps TDD – and/or HS-DSCH] resources previously allocated for the UE in another cell than the cell in which resources are currently being allocated, the DRNS shall release the previously allocated RACH and/or FACH resources [FDD – and/or HS-DSCH] [1.28Mcps TDD – and/or HS-DSCH].

If the DRNS has successfully reserved the required resources, the DRNC shall respond to the SRNC with the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message.

If the Permanent NAS UE Identity IE is present in the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message, the DRNS shall store the information for the considered UE Context for the lifetime of the UE Context.

If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message includes a C-ID IE corresponding to a cell reserved for operator use and the Permanent NAS UE Identity is available in the DRNC for the considered UE Context, the DRNC shall use this information to determine whether it can reserve resources on a common transport channel in this cell or not.

If the MBMS Bearer Service List IE is included in the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message, the DRNC shall, if supported, perform the UE Linking as specified in TS 25.346 [50], section 5.1.6. If an MBMS session for some MBMS bearer services contained in the UE Link is ongoing in the cell identified by the C-ID IE, the DRNC shall include in the Active MBMS Bearer Service List IE the Transmission Mode IE for each of these active MBMS bearer services in the COMMON TRANPORT CHANNEL RESOURCES RESPONSE message.

[FDD – If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message includes an Enhanced FACH Support Indicator IE, the DRNC may include the Enhanced FACH Information Response IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message. If a HS-DSCH RNTI was not previously allocated to the UE or a new HS-DSCH RNTI is allocated to the UE, the DRNC shall include the HS-DSCH-RNTI IE in the Enhanced FACH Information Response IE. And if Enhanced PCH operation is activated in the cell indicated by the C-ID IE, the DRNC shall include the Priority Queue Information for Enhanced PCH IE in the Enhanced FACH Information Response IE.]

[1.28Mcps TDD – If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message includes an Enhanced FACH Support Indicator IE, the DRNC may include the Enhanced FACH Information Response IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message. If a HS-DSCH RNTI was not previously allocated to the UE or a new HS-DSCH RNTI is allocated to the UE, the DRNC shall include the HS-DSCH-RNTI IE in the Enhanced FACH Information Response IE. And if Enhanced PCH operation is activated in the cell indicated by the C-ID IE, the DRNC shall include the Priority Queue Information for Enhanced PCH IE in the Enhanced FACH Information Response IE.]

[FDD – If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message includes an Common E-DCH Support Indicator IE, the DRNC may include the Common E-DCH MAC-d Flow Specific Information IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message. If the E-DCH MAC-d Flow Multiplexing List for a Common E-DCH MAC-d Flow is configured in DRNC, the DRNC shall include the E-DCH MAC-d Flow Multiplexing List IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message. If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message includes the C-ID IE and the Common E-DCH Support Indicator IE, the DRNC may include the E-RNTI IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message.]

[1.28Mcps TDD – If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message includes a Enhanced FACH Support Indicator IE, the DRNC may include the Common E-DCH MAC-d Flow Specific Information LCR IE in the COMMON TRANSPORT CHANNEL RESOURCES RESPONSE message.]

If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message includes an HS-DSCH physical layer category IE, the DRNC may store the information for the considered UE Context for the lifetime of the UE Context.

[FDD – If the COMMON TRANSPORT CHANNEL RESOURES REQUEST message includes an UE with enhanced HS-SCCH support indicator IE, the DRNC may store the information for the considered UE Context for the lifetime of the UE context.]

8.4.1.3 Unsuccessful Operation

Figure 28: Common Transport Channel Resources Initialisation procedure, Unsuccessful Operation

If the Transport Bearer Request Indicator IE is set to “Bearer Requested” and the DRNC is not able to provide a Transport Bearer, the DRNC shall reject the procedure and respond to the SRNC with the COMMON TRANSPORT CHANNEL RESOURCES FAILURE message, including the reason for the failure in the Cause IE.

If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message contains a C-ID IE corresponding to a cell reserved for operator use and the Permanent NAS UE Identity is not available for the considered UE Context, the DRNC shall reject the procedure and send the COMMON TRANSPORT CHANNEL RESOURCES FAILURE message, including the reason for the failure in the Cause IE.

Typical cause values are:

Radio Network Layer Causes:

– Common Transport Channel Type not Supported;

– Cell reserved for operator use.

Transport Layer Causes:

– Transport Resource Unavailable.

8.4.1.4 Abnormal Conditions

If the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message contains the Transport Layer Address IE or the Binding ID IE, and not both are present for a transport channel intended to be established, the DRNC shall reject the procedure using the COMMON TRANSPORT CHANNEL RESOURCES FAILURE message.

If ALCAP is not used, if the COMMON TRANSPORT CHANNEL RESOURCES REQUEST message contains the Transport Bearer Request Indicator IE set to “Bearer Requested” but does not contain the Transport Layer Address IE and the Binding ID IE, the DRNC shall reject the procedure using the COMMON TRANSPORT CHANNEL RESOURCES FAILURE message.

8.4.2 Common Transport Channel Resources Release

8.4.2.1 General

This procedure is used by the SRNC to request release of Common Transport Channel Resources for a given UE in the DRNS. The SRNC uses this procedure either to release the UE Context from the DRNC (and thus both the D-RNTI and the C-RNTI) or to release only the C-RNTI.

This procedure shall use the connectionless mode of the signalling bearer.

8.4.2.2 Successful Operation

Figure 29: Common Transport Channel Resources Release procedure, Successful Operation

The SRNC initiates the Common Transport Channel Resources Release procedure by sending the COMMON TRANSPORT CHANNEL RESOURCES RELEASE REQUEST message to the DRNC. Upon receipt of the message the DRNC shall release the UE Context identified by the D-RNTI and all its related RACH and/or FACH resources, unless the UE is using dedicated resources (DCH, [TDD – USCH and/or DSCH]) in the DRNS in which case the DRNC shall release only the C-RNTI and all its related RACH and/or FACH [FDD – and/or HS-DSCH] [1.28Mcps TDD – and/or HS-DSCH] resources allocated for the UE.

8.4.2.3 Abnormal Conditions

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