A Topology Independent TDMA-based MAC protocol for Vehicular Networks

Abstract

Resolving the problem of collision efficiently in a vehicular network is an essential requirement for providing real-time communication experience to the applications when the vehicles in the network use a common wireless channel to communicate. In general, the time division multiple access (TDMA) based media access control (MAC) protocols are considered to be better than the contention-based MAC protocols when it comes to providing QoS to the applications. However, the continually changing neighborhood, due to the highly dynamic nature of vehicular networks makes the static allocation of time slots to the vehicles inefficient. In this paper, we propose a topology independent MAC (TI-MAC) protocol for vehicular networks, in which, the time-slots to the vehicles are not assigned statically but, calculated by the vehicles themselves in a conflictfree manner using their current position on the road. The structure of the time frame, the duration of time slots and the time synchronization among the vehicles, is supported through the roadside units (RSUs) by transmitting a special message called “Beacon” periodically. The simulation results show the performance of the proposed TI-MAC protocol in terms of the average access delay experienced by the vehicles the packet drop rate due to collisions.