Distributed Fair Transmit Power Adjustment for Vehicular Ad Hoc Networks

Improving the safety of drivers and passengers by wirelessly exchanging information between vehicles represents a major driving force for the design of vehicular ad hoc networks. In a heavy loaded 802.11-based network, however, safety-related packets might collide frequently and cannot be decoded by a receiver, thus they might not be effective in increasing the safety level on the roads. In this paper, we propose to use transmit power control in order to reduce packet collisions, while taking into account the major design goal of vehicular ad hoc networks, i.e. increasing safety. While previous work has addressed the issue of power control primarily for optimizing network capacity and/or connectivity, the optimization criterion for improving safety has to be built upon the concept of fairness: a higher transmit power of a sender should not be selected at the expense of preventing other vehicles to send/receive their required amount of safety information. In this paper, we propose a fully distributed and localized algorithm called D-FPAV (distributed fair power adjustment for vehicular networks) for adaptive transmit power adjustment which is formally proven to achieve max-min fairness. Furthermore, we investigate the effectiveness and robustness of D-FPAV through extensive simulations based on a realistic highway scenario and different radio propagation models