Mobility management and its applications in efficient broadcasting in mobile ad hoc networks

We study an efficient broadcast scheme in mobile ad hoc networks (MANETs). The objective is to determine a small set of forward nodes to ensure full coverage. We first study several methods to select a small forward node set assuming that the neighborhood information can be updated in a timely manner. Then we consider a general case, where each node updates its neighborhood information based asynchronously on a predefined frequency and node move even during the broadcast process. The virtual network constructed from local views of nodes may not be connected, its links may not exist in the physical network, and the global view constructed from collection of local views may not be consistent. In this paper, we first give a sufficient condition for connectivity at the physical network to ensure the connectivity at the virtual network. We then propose a solution using two transmission ranges to address the link availability issue. The neighborhood information as well as the forward node set are determined based on a short transmission range while the broadcast process is done on a long transmission range. The difference between these two ranges is based on the update frequency and the speed of node movement. Finally, we propose a mechanism called aggregated local view to ensure consistency of the global view. By these, we extend Wu and Dai's coverage condition for broadcasting in a network with mobile nodes. The simulation study is conducted to evaluate the coverage of the proposed scheme.