Target RSU Selection with Low Scanning Latency in WiMAX-enabled Vehicular Networks

WiMAX offers promising data rate, low deployment cost and support for Vehicular Networks (VNs). In VNs, vehicles have high mobility as they move from the coverage area of a Serving-RSU (S-RSU) to a Target-RSU (T-RSU). When moving from a S-RSU to another RSU, every vehicle should complete handover process. However, seamless handover is one of the major challenges in WiMaX while supporting real-time applications for VNs. Handover latency mainly results from the T-RSU selection and scanning of multiple channels. In this paper, we therefore propose an efficient network assisted handover scheme which attempts to reduce the T-RSU selection and scanning time of Mobile Stations (MSs) during the handover process. Our scheme allows a S-RSU to calculate the amount of time during which an MS can receive services from a forthcoming T-RSU based on its velocity and a coverage area of the T-RSU, which is defined as Coverage/Service Time. Later on, S-RSU uses this coverage time for the selection of the T-RSU. In addition, a serving RSU also aids an MS with channel information and estimated time to start scanning in order to get associated with its T-RSU. Thus, our scheme allows the MS to scan only one channel of the selected T-RSU. Using the NS-2 simulator, for evaluation, we compared our scheme with some existing solutions. The simulation results show that due to the pre-selection of a reliable T-RSU, our proposed scheme efficiently reduces the network overhead. Furthermore, aiding an MS with channel information of a T-RSU reduces overall scanning latency and increases the network throughput.