Single-Anchor UWB Localization Using a Switched Directional Antenna Array and First-Path Power

IEEE 802.15.4z High-Rate Pulse (HRP) Ultra-Wideband (UWB) wireless technology supports centimeter-level ranging and is widely utilized for indoor positioning. Conventional single-anchor systems typically combine two-way ranging (TWR) for distance measurement with phase difference of arrival (PDoA) processing for direction estimation. However, PDoA accuracy depends strongly on the array aperture, angle of arrival, and received signal quality, which inherently limits the effective positioning range of the system. To address this limitation, this paper proposes a single-anchor positioning system based on an N-element circular array of directional antennas, in which a single UWB transceiver sequentially switches among the antenna elements. The anchor determines the distance via double-sided two-way ranging (DS-TWR) and estimates the direction based on the relative power between channels, obtained by measuring the first-path power of each antenna channel. Experimental evaluations conducted in a 12.8 m × 22.8 m indoor hall resulted in median and 90th-percentile direction errors of 1.93° and 2.66°, respectively, and median and 90th-percentile positioning errors of 0.24 m and 0.36 m, respectively.