This paper studies the fundamental communication properties of urban vehicle networks by exploiting the selfsimilarity and hierarchical organization of modern cities. We use an innovative model called “hyperfractal” that captures the selfsimilarities of both the traffic and vehicle locations but avoids the extremes of regularity and randomness. We use analytical tools to derive theoretical upper and lower bounds for the information propagation speed in an urban delay tolerant network (i.e., a network that is disconnected at all time, and thus uses a store-carryand-forward routing model). We prove that the average broadcast time behaves as n1-δtimes a slowly varying function, where δ depends on the precise fractal dimension. Furthermore, we show that the broadcast speedup is due in part to an interesting selfsimilar phenomenon, that we denote as information teleportation. This phenomenon arises as a consequence of the topology of the vehicle traffic, and triggers an acceleration of the broadcast time. We show that our model fits real cities where open traffic data sets are available. We present simulations confirming the validity of the bounds in multiple realistic settings, including scenarios with variable speed, using both QualNet and a discrete-event simulator in Matlab.

The goal of this paper is to increase our understanding of the fundamental communication properties in urban vehicle-to-vehicle mobile networks by exploiting the self-similarity and hierarchical organization of modern cities. We use an innovative model called “hyperfractal” that captures the self-similarities of both the traffic and vehicle locations, and yet avoids the extremes of regularity and randomness. We use analytical tools to derive matching theoretical upper and lower bounds for the information propagation speed in an urban delay tolerant network (i.e., a network that is disconnected at all time, and thus uses a store-carry-and-forward routing model). We prove that the average broadcast time behaves as n1-δ(times a slowly varying function), where δ depends on the precise fractal dimension. Furthermore, we show that the broadcast speedup is due in part to an interesting self-similar phenomenon, that we denote as information teleportation. This phenomenon arises as a consequence of the topology of the vehicle traffic, and triggers an acceleration of the broadcast time. We show that our model fits real cities where open traffic data sets are available. The study presents simulations that confirm the validity of the bounds in multiple realistic settings, including scenarios with variable speed.

We introduce a model of Poisson patterns of fixed and mobile nodes on lines designed for urban wireless networks. The pattern obeys to "Hyperfractal" rules of dimension larger than 2. The hyperfractal pattern is best suitable for capturing the traffic over the streets and highways in a city. We show that the network capacity under ad hoc routing algorithms scales much better than with the classic uniform Poisson shot model. The scaling effect depends on the hyperfractal dimensions. We show this results in two different routing models: nearest neighbor routing with no collision, minimum delay routing model assuming slotted Aloha and signal to interference ratio (SIR) capture condition, power-path loss and Rayleigh fading. The novelty of the model is that, in addition to capturing the irregularity and variability of the node configuration, it exploits self-similarity, a characteristic of urban wireless networks.