A counting-based broadcast model of emergency message dissemination in VANETs

Driving safety application in vehicular ad hoc networks (VANETs) is enabled to avoid traffic accident by broadcasting emergency messages among vehicles. A multi-hop broadcast model is needed to represent a broadcast forwarding mechanism in disseminating an emergency message. However, most of the broadcast models are developed from a periodic single-hop broadcast with a single slot collision probability which cannot exactly represent a single-hop broadcast failure. Broadcast reliability is represented by the broadcast failure or the survivability of emergency message. Thus, we propose a new model to calculate a single-hop survival broadcast packet probability with a forwarding mechanism in a dissemination of emergency message application based on a counting method, which accounts all possible cases of contention window assignments to all the nodes simultaneously receiving a broadcast message. Our model successfully discloses a single-hop broadcast survival probability as a function of the size of contention window and the number of broadcasting nodes.