| The problem of data gathering is considered in a wireless sensor network using mobile elements. In particular, we consider a case where data is produced at a particular node and it needs to be delivered to a predefined sink in a given time interval. Mobile elements in a wireless sensor network travel in a predefined path; they collect the data from the nodes and they deliver it to the sink. Each and every node must be visited by the mobile element, which must reach the sink within a given time constraint. Therefore, the goal is to plan a path for the mobile element that minimizes the total length travelled. We propose an algorithmic solution that builds node-disjoint tours that always include the sink, that cover the network and also optimize the total length travelled. We provide an Integer Linear Programming Algorithm (LPF) for the problem and propose two heuristic approaches for building the tours. We also evaluate the performance of our algorithm by comparing it to our optimal solution, also working on few alternative heuristic, commonly used in time-window vehicle routing problems, and demonstrating the superiority of our solution. |
