Scheduling Algorithm for Beacon Safety Message Dissemination in Vehicular Ad-Hoc Networks

Beacon safety message dissemination in Vehicular Ad-hoc Networks (VANETs) suffers from poor reliability especially in congested road traffics. The main origin of this problem is CSMA nature of Dedicated ShortRangeCommunications (DSRC) in MAC layer. In this paper, a scheduling algorithm in the application layer is proposed to alleviate the problem. We first divide the road into a number of geographical sections. In each section, we form a cluster between moving vehicles. Then we perform a scheduling algorithm including two levels. In the first level, nonadjacent clusters can transmit at the same time. While the second level of scheduling deals with inside of each cluster in which we implement a TDMA-like approach. Simulation results show that the proposed algorithm improves the reliability in beacon message dissemination. Moreover, the accuracy of the information which each vehicle can obtain from its neighboring vehicles is significantly increased. Thus the proposed scheduling scheme leads to considerable enhancement of the safety level provided by Beacon Safety Messages (BSMs).