A performance modeling of connectivity in Vehicular Ad hoc NETworks (VANETs).

摘要

An emerging new type of ad hoc networks is Vehicular Ad hoc NETworks (VANETs) which envision Inter-Vehicle Communications. Since, nodes in VANETs are both mobile as well as carrier of information; the network may not have full communication connectivity all the time and they may form several clusters where the nodes in each cluster may communicate with each other directly or indirectly. Multi-clustering happens whenever the minimum distance between two adjacent nodes becomes more than the transmission range of a node. Therefore, two important performance measures which affect the functionality in VANETs are communications connectivity and path availability .;In this thesis, we study the statistical properties of these performance measures in VANETs at the steady state. First, it is assumed that the nodes travel along a multi-lane highway which allows vehicles to overtake each other. We derive the probability distributions of the node population size and node's location in the highway segments. Then, we determine the mean population size in a cluster and probability that nodes will form a single cluster.;Then we extend the single highway model to a network of highways with arbitrary topology. We determine the joint distribution of the node populations in the highways' segments by application of the BCMP theorem. We model the number of clusters within the node population in a network path as a Markovian birth-death process. This model enables derivation of the probability distribution of the number of clusters and determination of mean durations of continuous communication path availability and unavailability times as functions of mobility and node arrival parameters. At the end, mean packet delay is presented for end to end communication in a path. We give numerical results which illustrate the effect of mobility on continuous communication path availability and communication delay. The results of this work may be helpful in studying the optimal node transmission range assignment, routing algorithms, network throughput, optimization of cross layer design schemes and MAC protocols in VANETs.