Routing Schemes in Community-Based Vehicular Ad Hoc Networks

Abstract

As wireless communication technologies have become commodities, it is expected that more and more vehicles will be equipped with wireless communication interfaces. The wireless communication module in vehicles will be used not only for in-vehicle communications, but also for (inter-)vehicular communications. We focus on the latter, which can form a vehicular ad hoc network.

Vehicular ad hoc networks (VANETs) open an opportunity for new applications. For instance, the message dissemination of traffic congestion, accident notification across vehicles may be needed and helpful for safe and efficient driving. VANETs with some fixed roadside infrastructure (e.g. static WiFi access points) also allows the geography-based advertisement like local events, free parking spots, and so on.

In this dissertation, we focus on routing schemes in VANETs, where i) vehicles move within a specific area, and ii) belong to a specific community. We call this type of networks community-based VANETs. The representative examples are buses and taxis belonging to local transportation service companies.

In community-based VANETs, we first propose a single-copy forwarding scheme enhanced by exploiting mobility information, and then extend the scheme to a multicopy version. To do so, we maintains the mobility information in a distributed manner. Second, we present the analysis of the expected delivery delay for single-copy schemes, using a simple model: the expected time to absorption in a continuous-time Markov chain. Third, we propose a novel geographic routing protocol in high vehicle density environments. The proposed scheme models a road topology by a graph in which the intersections of roads and road segments between adjacent intersections correspond to the sets of vertices and edges, respectively. Then, routing is performed vertex by vertex at the macro level and node by node at the micro level.