A Fast Message-Delivery Mechanism to Support Broadcast in Vehicular Ad hoc Networks

Traffic-related problems such as accidents, traffic jams and pollution are being addressed with the use of Intelligent Transportation Systems (ITS). ITS creates a network connecting vehicles and enabling the exchange of useful information to improve safety and provide efficient content delivery. In congested areas, however, the communication efficiency of a vehicular ad-hoc network (VANET) is greatly affected due to the number of generated messages. Packet collision and transmission errors are likely to increase as the messages are carried over radio waves. Hence, to improve coverage, redundant relay nodes are usually considered in the literature. However, such schemes increase channel contention and, consequently, the overall delay to cover a zone of interest (ZoI). This paper proposes a mechanism that explores the characteristics of the IEEE 802.11p standard to improve message dissemination to support broadcast tasks in VANETs. Simulation results show that the proposed scheme reduced delivery delay by 63.5% and presented 15 times less retransmissions when compared to a 802.11-based scheme. Even in congested scenarios, it presented a stable behavior in terms of delivery delay.