A Fast, Reliable, Adaptive Multi-hop Broadcast Scheme for Vehicular Ad Hoc Networks

Multi-hop broadcasting serves as an effective countermeasure against the negative impacts of rapid vehicular movement and internal interference on data transmission in Vehicular Ad Hoc Networks (VANETs), thereby enhancing support for safety-critical applications. The selection of candidate forwarding vehicles within this multi-hop broadcasting paradigm significantly impacts network performance. This paper proposes a Fast, Reliable, and Adaptive (FRA) multi-hop broadcast scheme, specifically designed to lower collision probability and reduce communication overhead. Initially, we examine the correlation between transmission distance and packet reception ratio under different channel conditions, leading to the development of an adaptive forwarding priority function. This function prioritizes data forwarding by preferentially selecting vehicles that exhibit higher packet reception ratios, depending on the channel's collision rates. Following this, we propose a contention-based scheme to assign waiting times to candidate vehicles based on the adaptive priority function. The proposed scheme can adaptively adjust the contention window size according to the forwarding priority and vehicular density, effectively differentiating waiting times among candidate vehicles and reducing the collision probability. Significantly, it guarantees that high-priority vehicles obtain shorter waiting times than their low-priority counterparts, aiming to minimize communication overhead. Simulation results indicate that FRA excels in terms of packet delivery ratio, average delivery time, and network overhead.