Enhancing AoA Estimation Via Phase Modeling of Bluetooth 5 CTE Signals

Angle of Arrival (AoA) estimation based on Constant Tone Extension (CTE) signals in Bluetooth 5 suffers from carrier frequency offsets (CFO) arising from the carrier frequency mismatch between the receiver and the transmitter, extra noises coming from switching frequencies when sampling CTE signals, as well as the phase folding problem due to the usage of mod2π in mapping the increasing phase values in estimation models into [0, 2π). To address these issues, a generalized phase model involving the CFO compensation and the time offset is established, and an adaptive gradient descent optimization algorithm based on the real sampling mechanism is proposed to solve the phase folding problem efficiently while obtaining high-precision AoA estimation. Experimental results show that our method reduces the average estimation error by at least 10% in outdoor scenes and 61% in indoor scenes compared to the conventional methods.