Efficient Message Composition and Coding for Cooperative Vehicular Safety Applications

Wireless intervehicular communication will enable a broad range of applications in the future. However, multiple vehicles, multiple diverse applications, multiple vehicle manufacturers, and the mobile vehicular environment raise several issues related to utilizing the wireless medium effectively. In this paper, we present a method for efficiently communicating vehicle data among neighboring vehicles, primarily for safety applications. The ldquomessage dispatcherrdquo (MD) coordinates communication between applications and the wireless channel at the application level. It addresses technical implementation issues, business deployment considerations, and issues of extensibility and system architecture. The MD concept has become an integral part of the Society of Automotive Engineers´ safety message-standardization effort. We describe the MD and present results illustrating its utility. We also describe a deployment in several vehicles at Toyota Technical Center in Ann Arbor, MI. Then, using data collected from the vehicles, we investigate a predictive-coding method for data transmission using the MD. We show that this scheme can reduce wireless-channel utilization and bandwidth requirements by over 80%, as compared to regular transmission methods. Several insights for future wireless-channel usage optimization are provided.