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An adaptative Backoff mechanism for VANETs

Backoff time is an important mechanism to ensure the stability of the network. This paper presents a simple solution for VANET networks which tries to minimize the probability of collision, and to optimize the back-off distribution. At first, we propose a new scheme for dynamic adaptation of contention window (CW) size in order to achieve better throughput performance and lower average end-to-end delay. The CW is adapted according to the instantaneous information about the channel conditions by using the artificial neural network. Collision rate, the number of network nodes, queue length and distance between sender and receiver are used as inputs of neural network. Our second idea is summarized on trying to retard a communication if it has a strong chance to produce a collision based on distance. Our contribution can be easily implemented as extension of EDCA. The simulation results show that the proposed method is able to increase throughput, reduce packet collision rate and delay time. Keywords— Contention Window; EDCA protocol; IEEE