RSU-supported MAC protocol for vehicular ad hoc networks

Safety and non-safety related vehicular ad hoc network messages have localised spatial scope and limited time relevance. A medium access control protocol must ensure timely delivery of such messages with high reliability over a shared wireless medium to one hop neighbours. In this paper, a Road Side Unit (RSU) supported channel allocation protocol has been proposed to minimise channel allocation time and management overhead. For protocol operation, an RSU divides the limited bandwidth allocated to a region into prefixed overlapping spatial clusters and the channel in each cluster is divided into time slots. A time slot is allotted to a vehicle in accordance to the priority of the request and availability of the channel in its cluster. Simulation results indicate that for channel allocation based on three overlapping clusters, the allocation scheme is able to deliver packets within the stipulated time with high reliability for different vehicle speeds and densities. Moreover, the centralised RSU-based technique does not suffer from the hidden and exposed node problem. Copyright © 2012 Inderscience Enterprises Ltd.