Dynamic Feedback Power Control for Cooperative Vehicle Safety Systems

Cooperative vehicle safety systems rely on periodic broadcast of each vehicle’s state information to track neighbors’ positions and therefore to predict potential collisions. The shared wireless channel in such systems is heavily affected by vehicle density and even medium vehicle density can cause channel congestion. Moreover, the interference factors can also heavily degrade the performance of the network. The vehicle tracking accuracy is the basis of cooperative vehicle safety systems and is significantly affected by the network. In order to enhance the robustness of the network against dynamical vehicle density and interference, a dynamic feedback power control scheme based on proportional-integral-derivative control is proposed. In this scheme, a dynamic information dissemination model that captures the time-varying nature of vehicle density is firstly proposed. This model qualities the network performance in terms of tracking information dissemination rate under the effect of dynamic vehicle density. Then, a predictive model is presented to predict, in a dynamic and receding-horizon fashion, the ideal information dissemination rate by considering the dynamics of vehicle density. Finally, a feedback control model that adjusts the transmission power in a closed-loop fashion is introduced. The feedback control model integrates the ideal state of information dissemination rate and the current real state that may be affected by interference to generate real-time power control strategies. These power control strategies will guide the actual network to evolve towards the ideal information dissemination rate. Experimental results confirm that the proposed power control scheme can gain a high accurate vehicle tracking performance for each vehicle and is robust to variations of traffic situation.