A semi-empirical performance study of two-hop DSRC message relaying at road intersections

This paper is focused on a vehicle-to-vehicle (V2V) communication system operating at a road intersection, where the communication links can be either line-of-sight (LOS) or non-line-of-sight (NLOS). We present a semi-empirical analysis of the packet delivery ratio of dedicated short-range communication (DSRC) safety messages for both LOS and NLOS scenarios using a commercial transceiver. In a NLOS scenario in which the reception of a safety message may be heavily blocked by concrete buildings, direct communication between the on-board units (OBUs) of vehicles through the IEEE 802.11p standard tends to be unreliable. On the basis of the semi-empirical result of safety message delivery at an intersection, we propose two relaying mechanisms (namely, simple relaying and network-coded relaying) via a road-side unit (RSU) to improve the delivery ratio of safety messages. Specifically, we designed RSU algorithms to optimize the number of relaying messages so as to maximize the message delivery ratio of the entire system in the presence of data packet collisions. Numerical results show that our proposed relaying schemes lead to a significant increase in safety message delivery rates.