Controlling Sink Mobility in Wireless Sensor Networks: A New Model and Protocols

This research concerns the definition of an analytical model and protocols for determining the routes of a mobile data collector (sink) traveling through the nodes of a wireless sensor network (WSN). The routes are determined with the overall aim of maximizing the network lifetime. The contribution of our work is twofold. First, we introduce a novel mixed integer linear programming formulation for determining the sink’s route and the sojourn time at the different “sink sites.” The model takes into account realistic parameters such as the maximum distance the sink can travel between sites as well as constraints on the sojourn time at a site. Solutions to the model provide the route of the sink as a sequence of sites and the sojourns time at those sites that induce the maximum network lifetime. We then propose the Greedy Maximum Residual Energy (GMRE) protocol for sink mobility. Such protocol is distributed and localized, thus being suitable for wireless sensor networking. In GMRE the sink greedily keeps moving toward those areas in the network where there is the most residual energy, as if “drawn” to them. This heuristic is then compared with a very simple and energy-unaware protocol where the next site in the sink route is chosen randomly and uniformly each time the sink moves. Simulation results show remarkable improvements both for network lifetime and for balancing energy consumptions throughout the network in case GMRE is adopted.