Effect of node mobility on highway mobile infostation networks

Abstract

In a mobile infostation network, any two nodes communicate when they are in proximity. Under this transmission constraint, any pair of nodes is intermittently connected as mobility shuffles the node locations. In this paper, we evaluate the effect of node mobility on highway mobile infostation networks. Each node enters a highway segment at a Poisson rate with a random speed drawn from a known but arbitrary distribution. Moreover, each node changes speed at each highway segment. Since nodes have different speed, a node may overtake other nodes or be overtaken as time evolves. Using arguments from renewal reward theory, the long run fraction of time an observer node is connected, and the long run average data rate can be derived. In this paper, however, we consider the special case of no speed change in each highway segment. In this case, the performance metrics are functions of the observer node speed. We consider both forward traffic scenarios, in which two nodes moving in the same direction have a transient connection when they are within range from each other, and reverse traffic scenarios in which two nodes travelling in opposite directions are connected transiently when they are in range. For node speed that is uniformly distributed, we reveal that the expected fraction of connection time, or expected number of connections in queuing terminology, is independent of the observer node speed in reverse traffic. In forward traffic, on the other hand, the fraction of connection time increases with observer speed. That is, the network performance improves with node mobility, which is unique to the mobile infostation networking paradigm.