Methods to Reduce DSRC Channel Congestion and Improve V2V Communication Reliability

Abstract

The U.S. Government, automotive industry, and DENSO have been developing prototype systems to evaluate the effectiveness of using Dedicated Short Range Communications (DSRC) to support vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) safety applications. Many V2V safety applications rely on each vehicle periodically broadcasting a Basic Safety Message (BSM) at a sufficient interval to provide an accurate representation to surrounding vehicles about the transmitter’s current position, speed, heading, and other critical information. A vehicle may also transmit a BSM immediately if some critical event occurs that requires immediate attention by neighboring vehicles. However, as the number of vehicles in communication range increases, the ability for each vehicle to reliably receive messages decreases due to increased congestion and packet collisions on the wireless medium. This paper shows how the congestion level affects the Packet Error Rate (PER) and describes parameters that can reduce the wireless channel congestion level and transmission methods that can increase the likelihood of receiving critical safety messages. Methods to detect high congestion levels and dynamically adapt these parameters are also provided. Test results using DSRC radios show the benefits of changing these parameters in real world situations.