A Novel Method for Evaluation of Coexistence between DSRC and Wi-Fi at 5.9 GHz

Co-channel coexistence between Dedicated Short- Range Communications (DSRC) and Wi-Fi needs thorough study. The reason is that although the 5.850-5.925 GHz (5.9 GHz) band has been reserved for DSRC so far, the U.S. government is moving swiftly on opening the band to be shared with Wi- Fi. However, most prior work lacks sufficient scientific rigor by relying on performance metrics such as packet delivery rate (PDR) and packet delay that cannot accurately measure performance of a vehicular network that primarily uses broadcast in dissemination of packets. Precise analysis of such broadcast operation is essential for rigorous investigation of DSRC-Wi- Fi coexistence because most safety-critical applications of DSRC operate based on broadcast. This paper proposes a new performance metric that can more accurately characterize the performance of a broadcast-based DSRC network. Based on the new metric, it characterizes coexistence of DSRC with IEEE 802.11ac-based Wi-Fi and suggests selection of key medium access control (MAC) parameters for DSRC: inter- broadcast interval (IBI) and contention window (CW).

I. Introduction

In August 2015, the United States Department of Transportation (DoT) released a test plan [1] that described tests to characterize the coexistence of Dedicated Short Range Communications (DSRC) and unlicensed devices in the 5.850-5.925 GHz (5.9 GHz) band. As suggested by the Congress in September 2015, the Federal Communications Commission (FCC), in its latest public notice [2], now seeks to refresh the record of its pending 5.9 GHz rulemaking to provide potential sharing solutions between Wi-Fi and DSRC at 5.9 GHz.