A.2 General

25.4673GPPRelease 17Stage 2TSUTRAN architecture for 3G Home Node B (HNB)

This Section describes an implementation variant where CN functions of SRNS Relocation are implemented within the HNB-GW in order to hide intra-HNB-GW inter-HNB active mode mobility from the CN.

From a HNB perspective the HNB-GW appears as a CN node (one node per CN domain) providing all necessary protocol functions for SRNS Relocation (Hard Handover), from a CN node perspective, the HNB-GW appears as an RNC serving the inter-HNB relocations as intra-RNC mobility.

The following sub-sections describe the respective mechanisms. The RANAP messages are exchanged over the Iuh interface from the Source-HNB to the HNB-GW and from the HNB-GW to the Target-HNB using appropriate RUA encapsulation.

In this implementation the Iu UP protocol is still terminated in the CN and HNB (Figure 7.2-1), but there is an Iu UP Interworking function (A.10) residing in the HNB-GW. This implementation variant supports SRNS Relocation between HNBs supporting the same RFC combinations if the HNB supports only Iu UP v1 and SRNS Relocation between all HNBs supporting Iu UP v2.