Carrier sense multiple access with collision avoidance‐aware connectivity quality of downlink broadcast in vehicular relay networks

In vehicular relay networks, the quality of communication link has a significant impact on the stable and reliable communication requirements. Most earlier studies focused on the influence of relay probability on link connectivity while little attention has been paid to the impact of packet collision. In complex mobile scenarios, vehicle density is proportional to relay probability, while proportional to data packet collision probability. Meanwhile, vehicle density and packet collision affect the quality of communication link in the relay network. This condition inspires them to study the link connectivity in vehicular relay networks based on carrier sense multiple access with collision avoidance. First, the relationships among vehicle density, vehicle speed, packet collision probability and relay probability are studied in relay communication. Second, due to the high-speed movement of vehicles, an analysis model, considering the mobility of vehicle nodes, is conducted to analyse the downlink performance in relay communication networks. Finally, a platoon scheme is proposed to reduce packet collision probability, considering the vehicle density and backoff window size on vehicle-to-roadside unit communication. Extensive numerical results indicate that the platoon model has a great advantage in terms of downlink performance, especially in the case of dense traffic flow.