Priority-Based Access for DSRC and 802.11p Vehicular Safety Communication

IEEE 802.11p/WAVE (Wireless Access in Vehicular Environments) is an emerging family of standards intended to support wireless access in Vehicular Ad Hoc Networks (VANETs). Broadcasting of safety-related messages especially emergency messages is expected to be crucial in this environment. In this paper, we propose a Priority-based medium Access (PA) mechanism for Dedicated Short-Range communication (DSRC) vehicular safety communication over IEEE 802.11p, called Vehicular PA (VPA). VPA supports two types of safety-related services (emergency and routine safety-related messages) with different priorities and strict requirements on delay, especially for emergency safety-related messages. VPA can guarantee the most important emergency messages to be transmitted as soon as possible by improving their priority for accessing the wireless channel. Simulation results show that our scheme clearly outperforms the classical DCF scheme adopted by IEEE 802.11p in terms of delay and the number of successfully transmitted packets during a synchronization interval defined in 802.11p.