Lightweight Single-Antenna Direction-of-Arrival Estimation for Curvilinear Trajectories in Mobile Embedded Systems

Accurate direction-of-arrival (DOA) estimation is valuable for spatially selective communication in noisy industrial environments. This work investigates a lightweight single-antenna framework in which receiver motion forms a virtual aperture. The receiver uses onboard inertial measurement unit (IMU) headings and two-way-ranging (TWR) measurements to a known fixed beacon, avoiding GPS, optical tracking, and high-precision external tracking of the mobile receiver. The curvilinear virtual-array MUSIC formulation is evaluated numerically using phase-coherent narrowband snapshots over arbitrary trajectories. Hardware experiments validate a range- domain TWR-IMU bearing estimator using corrected and averaged ranging observations. In a campaign of 100 consecutive four-revolution sweeps, all trials are retained. Phase-aligned accumulation recovers a 123 mm range-modulation amplitude, in close agreement with the measured 120 mm antenna lever arm. The single-sweep bearing precision is 8.2° absolute world-frame accuracy is limited by systematic BNO055 magnetometer drift in the motorized setup. The embedded bearing-estimation computation consumes 144.9 mJ per estimate, approximately 3 % of the measured cycle energy in the tested configuration. These results establish the feasibility of onboard range-domain bearing estimation and motivate future experimental validation of phase-coherent MUSIC during free-form mobile trajectories.