Mobile Element Path Planning for Time-Constrained Data Gathering in Wireless Sensor Networks

We consider the problem of gathering data from a sensor network using mobile elements. In particular, we consider the case where the data are produced by measurements and need to be delivered to a predefined sink within a given time interval from the time the measurement takes place. Mobile elements travel the network in predefined paths, collect the data from the nodes, and deliver them to the sink. Each node must be visited by a mobile element that must then reach the sink within the given time constraint. The goal is to plan the paths for the mobile elements that minimize the total length travelled. Several variations of this problem have been considered in existing literature. We propose an algorithmic solution that builds node-disjoint tours that always include the sink, cover the network, and optimize the total length travelled. We provide an integer linear programming formulation for the problem, and propose two novel heuristics for building the tours. We evaluate the performance of our algorithm by comparing it to the optimal solution as well as to an alternative heuristic, commonly used in related time-window vehicle routing problems, and demonstrate the superior performance of our approach.