Novel Backoff Mechanism for Mitigation of Congestion in DSRC Broadcast

Abstract: Due to the recent re-allocation of the 5.9 GHz band by the US Federal Communications Commission (FCC), it will be inevitable that dedicated short-range communications (DSRC) and cellular vehicle-to-everything (C-V2X), two representative technologies for V2X, have to address coexistence. Especially, the distributed nature of DSRC makes it not trivial to control congestions due to an asynchronous structure, which makes it inefficient to disseminate a controlling signal. To this end, we propose a method to "lighten" a distributed V2X networking. Technically, it is to allocate the backoff counter according to the level of an accident risk to which a vehicle is temporarily exposed. We provide an analysis framework based on a spatiotemporal analysis. The numerical results show the improvement in the successful delivery of basic safety messages (BSMs).