A broadcast path diversity mechanism for delay sensitive VANET safety applications

Reliable multi-hop broadcast protocols for vehicular ad hoc networks have been widely discussed recently. However, most of them use acknowledgement based retransmissions to provide reliability. The retransmission method incurs delays when a packet loss cannot be detected on time. Acknowledgement messages also increase the MAC layer contention time at each node. In this paper, we propose a mechanism to use path diversity to provide the reliability. In the proposed mechanism, a message is disseminated by two different paths. By cooperation of these two paths, broadcast messages can be disseminated with a short delay and a high reliability compared with acknowledgement based retransmission approach. The proposed mechanism does not use any explicit acknowledgement message. We evaluate the proposed mechanism using both theoretical analysis and computer simulations.