Radio Frequency Time-of-Flight Distance Measurement for Low-Cost Wireless Sensor Localization

TLDR

Accurate range estimation is critical for location‑aware wireless sensor networks, yet low‑cost solutions relying on RSS suffer poor accuracy, while high‑accuracy methods require wide bandwidths or complex infrastructure, making precise low‑cost ranging challenging due to the sensitivity of timing errors. This paper proposes a two‑way ranging technique that approaches the Cramér‑Rao bound and delivers 1–3 m accuracy, offering a low‑cost alternative to RSS and complex wide‑bandwidth methods. The method employs two‑way ranging, achieving near‑Cramér‑Rao‑bound accuracy in white noise and delivering 1–3 m precision in real‑world experiments. Prototype experiments confirm 1–3 m accuracy in real‑world ranging and localization.

Abstract

Location-aware wireless sensor networks will enable a new class of applications, and accurate range estimation is critical for this task. Low-cost location determination capability is studied almost entirely using radio frequency received signal strength (RSS) measurements, resulting in poor accuracy. More accurate systems use wide bandwidths and/or complex time-synchronized infrastructure. Low-cost, accurate ranging has proven difficult because small timing errors result in large range errors. This paper addresses estimation of the distance between wireless nodes using a two-way ranging technique that approaches the Cramér-Rao Bound on ranging accuracy in white noise and achieves 1-3 m accuracy in real-world ranging and localization experiments. This work provides an alternative to inaccurate RSS and complex, wide-bandwidth methods. Measured results using a prototype wireless system confirm performance in the real world.