IP Handoff and Mobility
The ability to support seamless handoff is the over-riding concern in designing networks for mobility. Mobile WiMAX standard talks about three physical-layer handoff mechanisms:
- Optimized Hard Handover (OHHO) - most efficient
- Fast Base Station Switching (FBSS) - optional
- Macro-diversity Handover (MDHO) - optional
Handoff can be BS or MS or network initiated, depending on the implementation. In addition to the physical handoff, the NWG has defined an end-to-end infrastructure for IP based network that supports the process of inter-vendor and inter-network handover to ensure continuity of authentication, billing, security and ongoing session.