Abstract

Vehicular Ad Hoc Networks (VANETs) are characterized by highly speed nodes, highly dynamic topology and frequent link disconnections. This raises a number of challenges especially in the field of data dissemination. Our study focuses on Geocast routing which consists of routing a message from a unique source vehicle to all vehicles located in a well geographically defined destination area called ZOR (Zone Of Relevance). In this work, we introduce some existing Geocast routing protocols for VANETs as well as a classification of these protocols based on the relay selection technique they use. We then provide a comparison of these protocols according to different criteria. While in literature ZORs are often assumed to be of any form and still chosen according to the scenarios and motivation needs of the authors [1], we consider a ZOR as a set of sub-ZORs and we choose simple geometrical forms for each sub-ZOR so that they would be easy to implement and to represent mathematically. We provide a geometrical vision angles based technique to define if two sub-ZORs are in the same direction in order to send them a single message, and hence, reduce messages overhead. Finally, we introduce a new routing protocol in Sub-ZORs (GeoSUZ) for VANETs based on our geometrical vision angles and greedy forwarding techniques. We compare GeoSUZ to GPSR routing protocol [3] and some numerical results show a significant gain in term of number of messages sent over the network.