Optimization trade-offs in the design of wireless sensor and actor networks

Wireless sensor and actor networks (WSANs) are composed of static sensor nodes and mobile actor nodes. We assume actors have a random initial location in the two-dimensional sensing area. The objective is to move each actor to a location such that every sensor node is within a bounded number of hops from some actor. Because sensor nodes have limited energy, the new actor locations are chosen as to minimize the transmission range required from the sensor nodes. However, actors also have a limited (although larger) power supply, and their movement depletes their resources. It follows that by carefully choosing the new actor locations, the total actor movement can be minimized. In this paper, we study the trade-off between minimizing sensor transmission radius and minimizing actor movement. Due to the complexity of the problem, we introduce an optimal ILP formulation, and compare its results against a proposed heuristic. For the ILP solution to be feasible, we introduce a finite set of potential actor positions such that an optimal solution is guaranteed to be found within this set.