Relocation procedure in 3G

The source RNC initiates the procedure by sending a RELOCATION REQUIRED message. The source RNC shall decide whether to initiate an intra-system Relocation or an inter-system handover. In case of intra-system Relocation, the source RNC shall indicate in the Source ID IE the RNC-ID of the source RNC and in the Target ID IE the RNC-ID of the target RNC only including the RAC if the message is sent towards the PS domain. In case of inter-system handover, the source RNC shall indicate in the Source ID IE the Service Area Identifier and in the Target ID IE the cell global identity of the cell in the target system

In case of intra-system Relocation, the source RNC shall include in the RELOCATION REQUIRED message the Source RNC to Target RNC Transparent Container IE. This container shall include the Relocation Type IE and the Number of Iu Instances IE containing the number of Iu signalling connections existing for the UE .

In case of inter-system handover to GSM the RNC:
-           shall include the MS Classmark 2 and MS Classmark 3 IEs
received from the UE in the RELOCATION REQUIRED message to the CN.

-           shall include the Old BSS to New BSS Information IE within the RELOCATION REQUIRED message only if the information is available.