Density-Aware Rate Adaptation for Vehicle Safety Communications in the Highway Environment

In this letter, we propose a density-aware rate adaptation (DARA) protocol to ensure reliable vehicle safety communication in a highway broadcast environment. DARA significantly improves system reliability by addressing the challenges of estimating channel conditions caused by various dynamics due to factors, including channel fading, interference, and varying traffic density. One salient advantage of DARA is that it can estimate the average packet loss rate for each sender locally without the use of any control frames (such as ACK and RTS/CTS). DARA can also distinguish the interference losses from the fading losses based on an empirical model. It adjusts the bit rate only in response to the packet loss due to channel fading and the change of the traffic density. Simulation results demonstrate that DARA can provide reliability guarantees for vehicle safety communication.