Efficient UWB Localization with Slotted TWR and Relay-Based TDoA: Experimental Validation

Precise Ultra-Wideband (UWB) localization often relies on tightly synchronized clocks, which limits scalability and increases deployment complexity, especially for real-time, multi-user environments. This constraint is a critical obstacle for lightweight, real-time positioning systems. To address this, we propose three synchronization-free localization models: Centralized-Relay-Based TDoA (i) and Distributed-Relay-Based TDoA (ii), which employ controlled signal relaying and pairwise clock rate estimation to accurately compute the Time Difference of Arrival (TDoA) without the need for global clock synchronization, and Slotted TWR (iii), a collision-free, TDMA-based Two-Way Ranging (TWR) protocol that assigns deterministic retransmission slots at the MAC layer, enabling reliable and scalable localization for many users simultaneously. Experimental evaluation on DWM3001CDK development kits demonstrates that Slotted TWR, in particular, achieves sub-15 cm accuracy and maintains robust performance both within and beyond the anchor region while significantly reducing channel usage compared to conventional TWR.