An Energy Efficient Tracking Algorithm in UWB-based Sensor Networks

This paper presents a novel ‘Energy Efficient Tracking’ (EET) algorithm that tries to meet the localization accuracy requirement, Pa, imposed by a generic location-based application while the energy consumption for ranging and communication is optimized. More specifically, given the set of range measurements performed by a mobile node with respect to its neighboring anchors (i.e., nodes whose exact positions are known a priori), the proposed EET algorithm selects, on the basis of the Cram´er- Rao lower bound (CRLB), the closest set of anchors such that the resulting positioning error is lower than the required Pa. At the same time, the EET approach minimizes the average energy consumption by dynamically adapting the transmitted power, Pt, to be used in the next positioning estimation step. Based on timeof- arrival (TOA) estimation with ultra-wide bandwidth (UWB) nodes, the EET approach uses an Extended Kalman Fitler (EKF) to track the mobile node’s position. Simulation results show that the EET algorithm effectively reduces the energy consumption while the achieved positioning performance is almost identical to the one achieved by a classical EKF with fixed Pt, named ‘Energy Fixed Tracking’ (EFT) algorithm.