  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.
