A 3-Tier UWB-Based Indoor Localization Scheme for Ultra-Low-Power Sensor Nodes

In this paper, a hierarchical indoor localization scheme is proposed to enable the use of autonomously powered ultra-low-power tags attached to the objects with unknown position. Using the UWB characteristics and the 3-tier organization (consisting of a large number of cost-effective tags, a small number of cheap and low-power hubs and a few synchronized base stations), the proposed localization scheme can provide a wide geographical coverage and precise positioning. Localization is based on the arrival time of the UWB pulses at the reference nodes with known locations. We formalize the hub placement problem as an optimization problem. Simulations investigate the performance degradation due to the nonideal hub placement and hub localization error.