Application-Level Frequency Control of Periodic Safety Messages in the IEEE WAVE

The basic safety message (BSM, also called a “beacon”) is the most fundamental building block that enables proximity awareness in the IEEE Wireless Access in Vehicular Environments. For driving safety and agile networking, the frequency of the BSM transmissions should be maintained at the maximum allowable level, but at the same time, rampant BSM proliferation needs to be curbed to leave room for higher priority messages and other applications that share what small bandwidth we have in the 5.9-GHz Dedicated Short-Range Communications band. In this paper, we describe an application-level messaging frequency estimation scheme called frequency adjustment with random epochs (FARE), which significantly improves the BSM throughput while using less bandwidth than the bare 802.11p delivery. FARE can be implemented purely on the application layer and uses neither cross-layer optimization nor explicit feedback from neighboring vehicles. It is only a few lines of code; therefore, it can easily be embedded in the BSM application program executed in the onboard unit.