On the Connectivity Problem of ETSI DCC Algorithm

The intelligent transportation systems (ITS) framework from European Telecommunication Standards Institute (ETSI) imposes requirements on the exchange of periodic safety messages between components of ITS such as vehicles. In particular, it requires ETSI standardized Decentralized Congestion Control (DCC) algorithm to regulate the beaconing activity of vehicles based on wireless channel utilization. However, the DCC state that defines the beaconing behavior under heavy channel congestion, i.e., the Restrictive state, has a serious connectivity problem that safety beacons do not reach other vehicles in safety-critical distances. In this paper, we demonstrate the problem through analysis, simulation, and on-road measurements. We suggest that DCC change the transmit power setting for the Restrictive state before a full-scale deployment of the ETSI ITS framework starts, and we discuss its consequences in terms of changes in communicability and channel utilization.