Analysis and design of effective and low-overhead transmission power control for VANETs

The control of vehicles ’ radio communication behavior to deal with the constrained available wireless bandwidth has been identified as a key challenge in VANETs. As an ele-ment of congestion control, this paper addresses distributed transmission power control as a means to control the impact of periodic transmissions (‘beacons’) on the overall channel load. By also considering recently discussed fairness issues, we first examine the trade-off between the effectiveness of controlling the channel load on the one hand and the cor-responding costs in terms of the required packet overhead on the other hand. We provide insights to the underlying estimation problems and present a sensitivity analysis with respect to non-homogeneous vehicular traffic densities and non-perfect channel conditions. Second, based on the analy-sis, we propose a segment-based power adjustment approach based on a distributed vehicle density estimation. The ap-proach put forward in this paper reduces overhead by two orders of magnitude compared to previous approaches while still being effective in controlling the channel load.