Localization scheduling in wireless ad hoc networks

Localization systems typically make use of redundant range or angle measurements from as many neighbours as possible to reduce location error. In dense networks this comes at the cost of excessive messages with limited improvement in location accuracy. This paper presents a scheduling scheme to limit node density to a set of active reference devices, which reduces message overhead and increases network lifetimes while maintaining sufficiently accurate location estimates. We use a method to estimate the amount of location error within a given probability to determine the minimum number of reference devices required for accurate localization. Simulation results show that with the proposed scheme localization messages remain constant with increasing node density, while location error is only marginally affected. Furthermore, network lifetimes are increased by over ten times allowing localization for longer periods of time. Computation times for localization are also reduced, which decreases accumulation of location error due to computation latency for mobile devices with speeds under 20 m/s.