Throughput Scaling Laws for Vehicular Ad Hoc Networks

This paper investigates throughput scaling laws for Vehicular Ad Hoc Networks (VANETs). We show that the road geometry greatly affects the throughput of a VANET. To this end we introduce the notion of sparseness to capture the geometrical properties of roads. We then start by addressing scaling laws for single roads. We shall see that even a single road can have very different scaling behaviors based on its path trajectory. Scaling laws for more complex systems such as downtown grids and general road systems are studied next. Here, the concept of road-connectivity plays a major role in determining the scaling behavior. In our analysis we account for a spectrum of node distributions that represent different vehicular traffic conditions. We also introduce the distance-limited throughput, a notion of throughput especially introduced for VANET-specific applications, and see how it scales in a single road system and in the presence of infrastructure. Our results are obtained by combining geometrical analysis, network flow arguments, and the probabilistic study of VANETs.