A Distributed Algorithm for Virtual Traffic Lights with IEEE 802.11p

A virtual traffic light (VTL) is a mechanism that allows vehicles to autonomously solve priorities at road junctions in the absence of fixed infrastructures (i.e., conventional traffic lights). To develop an effective VTL system, communication between vehicles is a crucial factor and can be handled either using cellular infrastructure or adopting a vehicle-to-vehicle (V2V) communication paradigm. In this paper we present the design, the implementation, and the field trial of a VTL which exploits V2V communications based on IEEE 802.11p. Specifically, we propose a decentralized algorithm, that adopts both broadcast signaling and unicast messages to assign priorities to the vehicles approaching intersections, thus preventing accidents and reducing traffic congestions. The algorithm has been tested both in a controlled laboratory environment and in a field trial with equipped vehicles.1