The Release 10 WI for HNB and HeNB Mobility Enhancements (RP-101426) introduced signalling via horizontal RAN interfaces (Iurh, X2) for the support of H(e)NB to H(e)NB mobility. A new Release 11 work package was agreed at RAN#51, starting with a feasibility study, taking both 3G and LTE aspects into account:

• UMTS only: Work on support for enhanced mobility in CELL_FACH for 3G home access was discontinued in Rel-10. This SI considers support of CELL_FACH state and the benefits that support of CELL_PCH and URA_PCH states can provide.
• The extension of SHO capability to include operation with the macro network can allow better integration of HNB cells with the macro network. To support SHO an extension of Iur from the HNB-GW to a macro RNC can be used, and this can also be used to link HNB-GWs as the Iur is a symmetrical interface. If supported for SHO, the presence of an Iur between the HNB-GW and macro RNC would allow use of enhanced SRNS relocation between the HNB and macro networks to further improve Hand-in/Hand-out performance compared to the CN involved methods already specified.
• Support for inter-CSG HO was discontinued in Rel-10. The issues involved in supporting inter-CSG HO need to be studied.
• LTE only: Support for eNB to HeNB was de-scoped in Rel-10, but provides significant benefits for open mode HeNBs used in mall environments and to extend the macro network coverage. Also deferred from Rel-10 was support for inter-CSG HeNB-HeNB HO.
• Support of X2 via GW proxy for HeNB to HeNB mobility will be studied.
• RAN Sharing (UMTS and LTE): RAN sharing, supported on the macro network has not been considered in relation to H(e)NBs. This will be studied in the context of any further requirements from SA.

This document captures the results of the study item on H(e)NB enhanced mobility in RP-110456[2]. It identifies the existing mobility functions for UMTS and LTE, the use cases and requirements for enhancements, and reviews and compares scenarios and techniques for enhancement of the mobility functionality. Aspects of RAN sharing related to H(e)NB mobility are also included.