A Cross-Layer Fast Handover Scheme For Mobile WiMAX

The Mobile WiMAX standard (IEEE 802.16e-2005) brings wireless broadband to a new level due to the support of nomadism. Still, handover latency in Mobile WiMAX is an issue that may affect real-time continuity of application sessions. This is partially due to the Layer 2 scanning/ranging, as well as the network re-entry procedure, which may result in a latency of hundreds of milliseconds, far exceeding the requirement of typical real-time services (e.g., 150 ms for Voice over IP). In this paper, we describe a mechanism which incorporates information from several OSI Layers to speed up the Layer 2 handover. We show by means of simulations that this new mechanism can decrease the handover latency significantly, to less than 100 ms in most cases.