Content for  TS 23.034  Word version:  18.0.0

Figure 5 depicts the procedures for a successful HSCSD intra BSC handover in A/Gb mode.

For a non-transparent call, the HSCSD configuration may be modified during an intra BSS handover within the maximum number of TCH/F and channel codings acceptable for the user and allowed by the network. The same allocation and activation rules as in call establishment apply. At handover completion, the BSC signals to the MSC the new HSCSD configuration and the MSC may adjust the IW resources accordingly.

Figure 5a depicts the procedures for a successful HSCSD intra BSC handover in GERAN Iu mode. For a non-transparent call in GERAN Iu mode, the HSCSD configuration may be modified during an intra BSS handover within the maximum number of TCH/F acceptable for the user and allowed by the network. The outcome of the handover shall be reported to the MSC by means of an Iu UP rate control procedure (see TS 25.415). The BSC shall set the maximum rate permitted downlink over the Iu interface according to the new HSCSD configuration, i.e. according to the AIUR to be used by the IW function when the communication is resumed after the handover. The BSC shall use the same RAB subflow combination in uplink direction. For a transparent call in GERAN Iu mode, the AIUR remains unchanged during the handover. Since the payload format at the Iu interface only depends on the AIUR, the IW resources do not need to be readjusted.

Figure 6 depicts the procedures for a successful HSCSD inter BSC handover in A/Gb mode.

In inter BSS handover the MSC requests the new BSS to allocate a channel configuration using parameters derived from the HSCSD related parameters agreed earlier during the call. Based on these parameters and operator preferences the BSC then allocates a suitable number of TCH/F and a suitable channel coding for the connection. For a non-transparent call, the HSCSD configuration may be modified during an intra BSS handover within the maximum number of TCH/F and channel codings acceptable for the user and allowed by the network. The same channel allocation and activation rules as in call establishment apply. The BSC informs the MSC of the chosen HSCSD configuration and at handover completion the MSC may adjusts the IW resources accordingly.

Figure 6a depicts the procedures for a successful HSCSD inter BSC handover in GERAN Iu mode.

The serving BSC includes the GERAN classmark of the target cell in the RANAP Relocation Required message. The MSC takes this information into account when it selects the RAB parameters for the RANAP Relocation Request message. For a non-transparent call in GERAN Iu mode, the HSCSD configuration may be modified during an inter BSC handover within the maximum number of TCH/F acceptable for the user and allowed by the network. After the successful setup of the radio access bearer towards the new BSC, for non-transparent calls the new BSC initiates the Iu user plane protocol. In the Iu UP initialisation message the first RAB subflow combination proposed in the list of RAB subflow combinations indicates the RAB subflow combination and thus the AIUR to be used by the IW function when the communication is resumed after the handover (see TS 25.415). The new BSC shall use the same RAB subflow combination in uplink direction. For a transparent call in GERAN Iu mode, the AIUR remains unchanged during the handover. Since the payload format at the Iu interface only depends on the AIUR, the IW resources do not need to be readjusted.

In inter MSC handover the requested channel configuration is forwarded to a BSS within the new MSC using MAP protocol between MSCs. Procedures similar to those in inter BSS handover case can be applied in order to establish the HSCSD connection in a new cell. In GERAN Iu mode, the GERAN classmark of the target cell is forwarded to the anchor MSC and to the target MSC using MAP protocol between MSCs.