Off-line Power Settings in Wireless Networks

We propose an algorithm for an off-line power assignment in wireless sensor networks. For a given network with two possible transmission powers (low and high), the problem is to find a minimum size subset of nodes such that if they are assigned high transmission power while the others are assigned low transmission power, the network will remain strongly connected. The main purpose behind this efficient setting is to minimize the total communication power consumption while maintaining the network connectivity. In a theoretical point of view, the problem is known to be difficult to solve exactly. An approach to approximate the solution is to work with a spanning tree of clusters. Each cluster is a strongly connected component when consider low transmission power. We follow the same approach, and we formulate the node selection problem inside clusters as an integer programming problem which is solved exactly using specialized codes. We refine our algorithm by exploring different spanning trees following a breath-first exploration procedure. Experimental results show that our algorithm is efficient regarding the execution time as well as the quality of the solution.