ReWarn: An opportunistic relay scheme for cooperative collision warning in VANET

In this paper, we present ReWarn, an opportunistic relay scheme for cooperative collision warning in VANET, which helps to mitigate the impact of package loss caused by shadow fading. When safety messages in VANET, e.g., collision warning messages, are broadcast in air, a vehicle may detect collision risks both of its own and of its neighbors´. If a vehicle has detected its neighboring vehicles are experiencing a collision risk while they keep quiet, it then probabilistically relays the raw data received from the neighboring vehicles with its own detection. Simulation results show that ReWarn can achieve higher reliability in message transmission than the non-relay schemes and keep the transmission efficiency at a satisfied level as well.