Impact of radio range on contact characteristics in bus-based delay tolerant networks

In bus-based delay tolerant networks the duration of a contact between two nodes limits the amount of data that can be transferred. For the implementation of such networks it is important to determine which contact durations can be expected. Moreover, this information can be used by scheduling and routing algorithms to increase efficiency. In this paper we structure and characterize the different types of contacts and examine the effects of radio range on contact duration. For realistic results we experimentally investigate the typical range of IEEE 802.11a/b and use a real mobility trace of a large-scale public transport network. We report the simulation results for different types of contacts and the probability distribution of contact durations for various realistic ranges. Furthermore we show that the angle of contacts is an appropriate criterion for the classification of contacts, and propose to use it as input for routing and scheduling decisions.