REIHE INFORMATIK 3/2002 A Comparison of Routing Strategies for Vehicular Ad-Hoc Networks

In this paper we investigate the use of ad-hoc routing algorithms for the exchange of data between vehicles. There are two main aspects that are of interest in this context: the specific characteristics of ad-hoc networks formed by vehicles and the applicability of existing ad-hoc routing schemes to networks that display these characteristics. In order to address both aspects we generate realistic vehicular movement patterns of highway traffic scenarios using a well validated traffic simulation tool. Based on these patterns we show that the characteristics of vehicular ad-hoc networks are quite different from the frequently used random waypoint model. We then proceed to evaluate the performance of a reactive ad-hoc routing protocol (DSR) and of a position-based approach (greedy forwarding as done in GPSR) in combination with a simple reactive location service. Our analysis suggests that for vehicular networks where communication spans more than 2 or 3 hops position-based ad-hoc routing has significant advantages over reactive non-position-based approaches both in the number of successfully delivered packets and in routing overhead.