Non-repetitive single-hop broadcast model for CAM in IEEE802.11p VANETs

VANETs relies on the repetitive exchange of Cooperative Awareness Messages (CAMs) among vehicle's On­Board Units (OBUs) and vehicles to roadside units (RSUs), thus making CAMs the backbone of the network. This exchange may lead to degradation of network performance caused by the ample amount of data exchange between the vehicles. Therefore, a trade­off between CAM broadcast within the network and optimum utilization of network resources is required. Most of the existing work focuses on retransmission of beacon messages supporting unicast 802.11 models which are not directly suited for the VANET scenario. To deal with this problem, the paper presents a model for non-repetitive single-hop broadcast of CAM within the network, thus supporting IEEE802.11p. For non-repetitive broadcast of CAM, the concept of preemption of messages is introduced in the model. Simulation is carried out using MATLAB 15's Simiilink. The model performance is evaluated by extracting its statistical properties in terms of Channel Utilization, CAM's Average Waiting Time within the queue and Average Queue Length. To validate our model, the simulation is implemented on real world data acquired from wheel speed for all wheels for the duration of a test drive.