XRLoc3D: Single UWB Receiver Array for Real-Time 3D Localization

Abstract

Accurate 3D localization is critical for indoor applications such as XR and drone operation, requiring centimeter-level accuracy, real-time updates, and deployment from a single site. In many indoor XR-style deployments, these requirements arise in LoS-dominant, room-scale environments where the direct path remains observable or separable. Existing optical, acoustic, WiFi/BLE, and prior UWB systems address parts of these requirements but typically struggle to satisfy them simultaneously due to infrastructure cost, limited bandwidth, or computational complexity. We present XRLoc3D, a single-anchor UWB localization framework that combines algorithmic innovation, hardware design, and bias-aware modeling. Instead of brute-force or stochastic likelihood search, XRLoc3D analytically enumerates consistent TDoA/PDoA hyperboloid intersections, collapsing billions of volumetric candidates into a tractable set and achieving maximum-likelihood accuracy with over 107× fewer evaluations than a volumetric maximum-likelihood reference. On the hardware side, we build a compact two-tier array that enables near-field observability from a single site. We further incorporate lightweight calibration to remove angle-dependent antenna biases, sustaining centimeter-level accuracy in room-scale indoor environments where the direct path remains separable. In a 5 m × 5 m × 3 m indoor space, XRLoc3D achieves a median error of 1.51 cm and a 90th-percentile error of 5.76 cm at 60 updates/s, using DW3000-class radios on the globally standardized 8 GHz UWB band. These results demonstrate practical real-time 3D localization for room-scale indoor deployments using a single-site prototype built from off-the-shelf UWB evaluation modules.