Synchronization challenges in media access coordination for vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) can support a wide range of future cooperative safety and efficiency applications. However, the node density and high demand for wireless media in these networks can lead to the Timeslot Boundary Synchronization Problem, in which increased transmission collisions occur due to back-off timer synchronization. This paper proposes an enhancement to the wireless access in vehicular environments (WAVE) communications architecture to address this problem, called RAndom Propagation Initiation Delay for the Distributed Coordination Function (RAPID DCF). The effectiveness of RAPID DCF is evaluated through simulations of both single-hop and multi-hop emergency messages. In these simulations, RAPID DCF was able to improve message delivery rates by as much as 35% and reduce multi-hop message latency by as much as 18%.