CAMS transmission rate adaptation for vehicular safety application in LTE

Researchers have started to investigate the possibility of using cellular networks for vehicular applications. Among cellular networks, LTE is the most promising technology that supports high data rate, low latency and wide coverage. Vehicular safety applications are based on broadcast of vehicle's information to it's neighbours periodically. As LTE is an infrastructure-based network, all communications should pass through the infrastructure. Due to the expense of using LTE bandwidth and the fact that most of the bandwidth is used by other applications, limited amount of bandwidth can be allocated for safety applications. As vehicles do not know number of other vehicles and their transmission rate, they might send more than available bandwidth and make the infrastructure congested which leads to high latency. In this paper we propose an algorithm to control transmission rate of vehicles by a remote host as a central node which knows the available bandwidth and total data rate of vehicles at each time. Our proposed algorithm also considers the vehicles speed for rate adaptation. Simulation results show that applying our algorithm can control the latency. It also improves the position accuracy of faster vehicles by considering the vehicles speed in adaptation.