Multipath Credibility Selection for Robust UWB Angle-of-Arrival Estimation in Narrow Underground Corridors.

Area of Science:

• Signal Processing
• Wireless Communications
• Localization and Navigation

Background:

• Elongated underground environments like utility corridors and logistics tunnels create dense multipath propagation.
• Standard ultra-wideband (UWB) angle-of-arrival (AoA) estimators (e.g., PDOA, MUSIC) fail when the strongest channel impulse response (CIR) component is a reflection, not line-of-sight (LOS).
• Existing methods often require explicit line-of-sight/non-line-of-sight (LOS/NLOS) classification, which is challenging in these environments.

Purpose of the Study:

• To develop a robust AoA estimation algorithm for UWB systems operating in challenging underground environments with dense multipath.
• To overcome the limitations of traditional AoA estimators that rely on selecting a single dominant CIR component.
• To introduce a method that does not require explicit LOS/NLOS classification for accurate AoA determination.

Main Methods:

• Proposed the multipath credibility selection AoA estimator (MCS-AoA).
• MCS-AoA utilizes four credibility factors: amplitude significance, time-of-flight (TOF) consistency, inter-baseline phase-geometry agreement, and cross-baseline coherence.
• Fuses credible CIR components into a weighted spatial covariance matrix for 2D MUSIC search.

Main Results:

• In field experiments within an underground corridor (5-40 m), MCS-AoA achieved mean absolute errors (MAE) of 1.00° azimuth and 1.46° elevation, outperforming six baseline algorithms.
• In a logistics tunnel (5-80 m), MCS-AoA achieved a 1.19° azimuth MAE, demonstrating superior performance in longer-range scenarios.
• Simulations showed a 0.71° azimuth root-mean-square error (RMSE) at 80 m, a 69.3% reduction compared to PDOA, with 86.6% of estimates within 1°.

Conclusions:

• MCS-AoA provides significantly improved AoA accuracy in underground environments compared to existing methods.
• The algorithm's ability to handle multipath without explicit LOS/NLOS classification makes it highly practical for UWB localization.
• MCS-AoA offers a robust solution for precise positioning in challenging, signal-reflected environments.