A Random Road Network Model and Its Effects on Topological Characteristics of Mobile Delay-Tolerant Networks

Road networks have significant impact on mobility and network characteristics of wireless ad hoc networks. Discovering their characteristics and effects on mobility and network performance in urban environments is a fundamental research task. In this paper, we firstly study the graph attributes of road networks by sampling real road networks in main cities of Europe and USA. We propose a new graph metric, called characteristic central length, in order to estimate the average shortest-path length of a large-scale spatial network. We find that real road networks from Europe and USA have different patterns with regard to some graph attributes and a simple grid model is inadequate to describe them. Considering the diverse patterns of urban road networks caused by obstacles and shortcuts, we propose a random road network model, called the GRE model. The model is validated through fitting it to real road network samples using a genetic algorithm and simulation of delay-tolerant networks. The simulation results have shown that by extending the grid model with new probabilistic parameters, the GRE model has better capability on approximating real road networks. The simulation results have also shown that delay-tolerant networks operating on road networks may have better performance than scenarios without road networks.