Distributed Traffic Control and Navigation (DTCN) System for Next-Generation Vehicular Ad Hoc Networks

Vehicular ad hoc networks (VANETs) aim to establish communication among vehicles and between vehicles and nearby roadside equipment, with very limited or no infrastructure support. The next-generation VANETs are able to support various road safeties, intelligent transportation, mobile infotainment, and location-dependent commercial applications.

Traffic safety is a fundamental requirement in VANETs. There are two strategies achieving traffic safety: traffic control and emergency notification. Traffic control is a proactive strategy that alleviates traffic congestion by controlling the timing of traffic signals. Because the number of vehicles passing a bottleneck stays the same, this approach cannot fundamentally solve the problem. Emergency notification is a reactive strategy. When non-safe events occur, vehicles broadcast emergency warning messages to notify surrounding vehicles of the non-safe situations. However, broadcasting in VANETs presents a challenge due to the high vehicle mobility in the networks and the complex network topology dynamics. The existing broadcast protocols in VANETs are limited in one or more of the following ways: they 1) are non-applicable to both freeway and urban scenarios, 2) are non-applicable to bidirectional multi-lane scenarios, or 3) are non-applicable to sparse VANETs.

The aim of the proposed research is to develop a Distributed Traffic Control and Navigation (DTCN) system which can support: 1) distributed traffic control by navigating vehicles to light- traffic routes; 2) effective emergency notification that overcomes the aforementioned limitations of existing broadcast solutions; 3) various location-based services and entertainment applications of VANETs. We classify VANET messages into four categories with different priorities, including emergency warning messages, real-time traffic condition messages, on-demand messages with tight latency constraints, and on-demand messages with loose latency constraints. We propose the design of prioritized broadcasting protocols that make use of the multiple VANET channels for effective message delivery. We further investigate the opportunistic delegation rules such that the prioritized broadcasting protocols can be applied in sparse VANETs in which the network topologies could be disconnected. Finally, we design a sample navigation application of the DTCN system. In the application, vehicles equipped with digital maps opportunistically update real-time road traffic conditions by exchanging real-time traffic condition messages during movement. The vehicles can be dynamically navigated to the best routes, e.g., the routes offering the shortest travel times to their destinations. The proposed DTCN system can be applied in the next-generation VANETs to balance road traffic, improve transportation efficiency, and potentially save people’s lives.