Reliable message forwarding in VANETs for delay-sensitive applications

Multi-hop forwarding in VANETs remains a challenging task. Existing protocols either focus on high packet delivery ratios or low latencies. In this paper, we propose Low-Delay Forwarding with Multiple Candidates (LDMC), a novel geographic routing approach using a combination of sender-based forwarder selection and receiver-based coordination of multiple contenders. Candidates are rated based on a combination of position and relative speed information. Contention among forwarders is realized with priority-dependent timers. Our evaluation shows substantial improvement of the forwarding delay while maintaining high packet deliver ratios comparable to contention-based algorithms for different scenarios. Hence, the proposed concept is well suited for delay-sensitive applications like cooperative positioning or coordinated driving.