Improving VANET Protocols via Network Science

Developing routing protocols for Vehicular Ad Hoc Networks (VANETs) is a significant challenge in these large, self- organized and distributed networks. We address this challenge by studying VANETs from a network science perspective to develop solutions that act locally but influence the network performance globally. More specifically, we look at snapshots from highway and urban VANETs of different sizes and vehicle densities, and study parameters such as the node degree distribution, the clustering coefficient and the average shortest path length, in order to better understand the networks' structure and compare it to structures commonly found in large real world networks such as small-world and scale-free networks. We then show how to use this information to improve existing VANET protocols. As an illustrative example, it is shown that, by adding new mechanisms that make use of this information, the overhead of the urban vehicular broadcasting (UV-CAST) protocol can be reduced substantially with no significant performance degradation.Comment: Proceedings of the 2012 IEEE Vehicular Networking Conference (VNC), Korea, November 201

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1 VANETs can be based on vehicle-to-infrastructure (V2I) and/or vehicle-to-vehicle (V2V) communications. 2 V2X is an abbreviation used for both V2I and V2V communications. 3 The price quote includes the cost of both roadside equipment and roadside wireless communications. INTRODUCTION Successful deployment of vehicular ad hoc networks (VANETs) where information (e.g., traffic, road information, and safety messages) is sent, forwarded, and received by vehicles depends on the adoption of a new wireless technology, dedicated short-range communications (DSRC). Since it is anticipated that DSRC technology might be a mandate for modern vehicles effective 2017, with high probability, vehicle-toinfrastructure (V2I) communications-based networks will be the first type of vehicular ad hoc networks (VANETs) 1 that might be implemented and, as such, could accelerate the adoption of DSRC. Besides V2I applications (e.g., Internet access), additional infrastructure can also be used to improve connectivity of vehicle-to-vehicle (V2V) networks. In addition to growing demand for V2X traffic 2 and the fact that V2V applications are confined to a particular geographical area, installing special roadside units (RSUs) has emerged as an attractive solution (especially to the U.S. Department of Transportation) for providing infrastructure support as RSUs limit information to being disseminated within a confined area, thus resulting in smaller message delay, better information security, and possibly lower communications cost. While RSUs seem to be a very promising solution for improving V2V communications, the cost of manufacturing, installing, and maintaining these units seem to be prohibitive for the large-scale deployment of RSUs. For example, a simplistic form of RSU (e.g., roadway probe beacons) requires $13,000-$15,000 per unit capital cost and up to $2400 per unit per year 3 for operation and maintenance PROBLEM STATEMENT The U.S. Department of Transportation (DoT) was expected to have nationwide deployment of the roadside infrastructure in 2008 [4]. This plan, however, did not materialize, and to date very few RSUs have been deployed. The major reasons that prevented the success of the plan are summarized below. JUSTIFYING THE BENEFITS THAT RSUS PROVIDE IS DIFFICULT Determining the value of such a radical proposition in uncertain future markets has proven to be nontrivial and fairly complicated. Even though the benefits of V2V and V2I systems in terms of safety, traffic efficiency, and environment are clear and have been reported in ABSTRACT Deploying roadside units, RSUs, for increasing the connectivity of vehicular ad hoc networks is deemed necessary for coping with the partial penetration of DSRC radios into the market in the initial stages of DSRC deployment. Several factors, including cost, complexity, existing systems, and lack of cooperation between government and private sectors, have impeded the deployment of RSUs. In this article, we propose to solve this formidable problem by using a biologically inspired self-organizing network approach whereby certain vehicles serve as RSUs. The proposed solution is based on designing local rules and the corresponding algorithms that implement them. Results show that the proposed approach can increase the message reachability and connectivity substantially

Cars as roadside units: a selforganizing network solution

Abstract Deploying Roadside Units (RSUs) for increasing the connectivity of vehicular ad hoc networks is deemed necessary for coping with the partial penetration of Dedicated Short Range Communications (DSRC) radios into the market at the initial stages of DSRC deployment. Several factors including cost, complexity, existing systems, and lack of cooperation between government and private sectors have impeded the deployment of RSUs. In this paper, we propose to solve this formidable problem by using a biologically inspired self-organizing network approach whereby certain vehicles serve as RSUs. The proposed solution is based on designing local rules and the corresponding algorithms that implement such local rules. Results show that the proposed approach can increase the message reachability and connectivity substantially