Communications are difficult to maintain in dynamic networks. Vehicular networks are an example of these dynamic ad hoc networks. In this thesis, we focus on the unicast communications in dynamic ad hoc networks (vehicular networks in particular). We conducted road tests to analyze the performance of vehicular networks. Results allowed us to propose improvements to V2I and V2V communications. Following to the study of performances, we proposed an opportunistic architecture for V2I communications (data sending from a vehicular network to the infrastructure via a gateway). In V2V communications, both source and destination are mobile. The communication is then threatened of being interrupted. To overcome this problem, we proposed a path maintaining algorithm that guarantees the delivery of messages between two moving entities moving. This algorithm uses the local exchange to adjust the path, and thus overcome the networks dynamics. To better understand the limitations of routing in general and of our path maintaining algorithm in particular, we used the "best effort" specifications which formalizes a contract between the network dynamics and the properties of an algorithm. We introduced the p-dynamic graphs to characterize the dynamics. We can then express a topological property, which is essential to ensure a continuity property, characterizing the service offered by the algorithm. This modeling approach is a first step towards defining algorithmic metrics for dynamic networks.
