Application-level scheme to enhance VANET event-driven multi-hop safety-related services
In this paper, we focus on the design and analysis of channel access in vehicular ad hoc networks (VANETs) for event-driven multi-hop safety services. First, a novel channel access scheme that incorporates an application-level distance (timer)-based rebroadcast is designed to enhance the reliability and efficiency of safety message delivery. In the scheme, an effective new approach integrating transmitter-oriented repetitions, ESD bitmap, message sequence number, and modulo based waiting mini-slot is provided to overcome possible concurrent timer due among close nodes and possible message collisions in the conventional distance-based timer for selection of multi-hop forwarders. The reliability and performance of the proposed scheme are analyzed and compared with that of other broadcast schemes for VANET event-driven safety services on highways. The new analytic models account for the impact of the Nakagami fading channel with distance dependent path loss and vehicle mobility on the reliability and performance. Extensive simulations are conducted to verify the correctness of our proposed scheme and models under realistic network parameter settings.