On the impact of Multi-channel Technology on Safety-Message Delivery in IEEE 802.11p/1609.4 Vehicular Networks

The IEEE 1609.4-Multi-Channel Operation protocol has been proposed to support the co-existence of safety and non-safety (infotainments) applications over the Dedicated Short Range Communication (DSRC) channels at the 5.9 GHz band. However, the multi- channel approach over a single-radio transceiver might result in several performance degradations that have not been thoroughly investigated yet. In this paper, we analyze the performance of safety- related applications over multi-channel vehicular networks. We demonstrate through a simulation study that the synchronous channel switching enforced by the IEEE 1609.4 protocol might easily compromise the performance of safety applications that rely on the periodic exchange of short lived broadcasts. Thus, we propose in this work the WAVE-enhanced Adaptive Broadcast (WAB) scheme. WAB provides a novel MAC contention control mechanism intended to reduce the impact of packet collisions caused by the synchronous channel switching, and to increase the packet delivery rate of broadcast messages in congested vehicular scenarios. The WAB scheme dynamically adapts to the channel conditions through a distributed load estimator metric, and implements priority mechanisms to ensure fairness among vehicles. Simulation results reveal that the proposed WAB scheme can significantly increase the packet delivery rate of broadcast messages when compared to the existing IEEE 802.11p/1609.4 scheme.