Efficient packet relay scheme with payload combining for ITS V2V communications

The reliability of CSMA/CA vehicle-to-vehicle (V2V) broadcast communication is seriously affected by propagation issues such as propagation loss, fast fading by multipath propagation, and hidden terminal problem. In order to improve the V2V communication reliability, a vehicle-roadside-vehicle relaying communication scheme has been proposed and its effectiveness has been shown. However, relaying increases air time occupancy ratio in a wireless channel which results in more chances of collision and limits the improvement by relaying. This paper proposes an improved V2V packet relay scheme with payload combining at relay station to save air time and mitigate the collision. Simulated results assuming an intersection show that the average packet delivery ratio is significantly improved with the proposed scheme.