Optimizing the placement of anchor nodes in RSS-based indoor localization systems

We address the problem of optimizing the placement of anchor nodes for an indoor localization system based on a Wireless Sensor Network (WSN) when the Received Signal Strength (RSS) indicator is used as input of the localization algorithm. We consider as objective function the Cramer Rao Lower Bound (CRLB) as well as a simpler surrogate function, and we focus on the case where anchor nodes are constrained to lie on the walls of the buildings to monitor. For the problem version with the surrogate objective function, we propose two alternative mathematical programming formulations that are based on a discrete or continuous solution space. The resulting mixed-integer nonlinear problems (MINLP) can be solved to optimality for small-sized instances. For larger instances arising in practical scenarios, we propose a Tabu Search heuristic that provides near-optimal solutions in short computing time, and that can also directly minimize the CRLB.