Delay analysis of VeMAC supporting periodic and event-driven safety messages in VANETs

Vehicular ad hoc networks (VANETs) have a great potential in enhancing the public safety standards and providing a safer environment for people on road. The VeMAC is a recently proposed medium access control protocol which supports a reliable one-hop broadcast service necessary for high priority safety applications in VANETs [1]-[3]. This paper describes how the VeMAC protocol can deliver both periodic and event-driven safety messages in VANETs, and presents a detailed delivery delay analysis, including queueing and service delays, for both types of safety messages. The probability mass function of the service delay is first derived, then the D/G/1 and M/G/1 queueing systems are used to calculate the average queueing delay of the periodic and event-driven safety messages respectively. Simulation results are presented to study the accuracy of the delay analysis under simplified assumptions. The delay analysis will help to determine the VeMAC protocol parameters to satisfy the service requirements of various safety applications in VANETs.