Performance Comparison of a Platooning Application Using the IEEE 802.11p MAC on the Control Channel and a Centralized MAC on a Service Channel

Abstract – Recent advances in cooperative driving hold the po-tential to significantly improve safety, comfort and efficiency on our roads. An application of particular interest is platooning of trucks, where it has been shown that keeping a minimum inter-vehicle distance results in considerably reduced fuel consump-tion. This, however, puts high requirements on timeliness and reliability of the underlying exchange of control messages be-tween platoon members. The European profile of IEEE 802.11p, recently adopted by ETSI, defines two message types to this end, periodic beacons for basic cooperative awareness (CAM) and event-triggered decentralized environmental notification messag-es (DENM), both of which will use one common control channel. IEEE 802.11p employs a random medium access protocol, which may experience excessive delays during high network loads. To mitigate these effects, ETSI standardizes a decentralized conges-tion control algorithm to, e.g., lower the CAM update frequency during high loads. However, this may prevent proper functionali-ty of a platooning application. In this paper we propose a solution that instead uses a dedicated service channel for platooning ap-plications and compare its performance to standard-compliant IEEE 802.11p inter-platoon communication on the control chan-nel. Service channels typically have less strict requirements on send rates, data traffic types and medium access methods. Our service channel solution combines a random access phase for DENM with a centralized, scheduled access phase for CAM. Using a service channel enables us to guarantee timely channel access for all CAM packets before a specified deadline while still being able to provide a reasonable DENM dissemination delay. I