Intersection-based routing for urban vehicular communications with traffic-light considerations

In this article, we explore the impact of traffic lights on routing protocol design in vehicular ad hoc networks. Specifically, we focus on intersection-based routing protocols designed for vehicular communications in urban areas. We find that traffic lights greatly impact routing in urban areas, but this issue has not been well treated in existing routing protocols. In this article, we propose a new protocol called Shortest-Path-Based Traffic-Light-Aware Routing (STAR) for VANETs with traffic light considerations. For STAR, the signals of traffic lights on the intersection, together with the traffic patterns, determine how packets are forwarded. We show via analysis and simulation that our proposed STAR protocol is superior to Green Light First forwarding (i.e., packets are forwarded on the path with green lights). We also conduct ns-2 simulations to evaluate the performance of STAR. The results show that STAR achieves shorter average delay, higher delivery ratio and higher TCP throughput than existing routing protocols for urban VANET communications.