Carrier-to-Noise Ratio Improvement of 5G Signals via Beamforming for TOA-Based Opportunistic Navigation

A method to improve the carrier-to-noise ratio <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(C/N_{0})$</tex> of received cellular fifth-generation (5G) signals via beamforming is developed. The developed method utilizes the direction-of-arrival (DOA) estimated from an antenna array, which is processed and fed to the receiver's tracking loops estimating the time-of-arrival (TOA). Experimental results are presented demonstrating a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$C/N_{0}$</tex> improvement of about 7 dB in a stationary scenario and 6 dB in a moving scenario, compared to a non-beamformed approach. Using fused TOA and DOA measurements from two 5G gNBs via an extended Kalman filter (EKF), it is shown that starting from an initial position estimate 470 m away, the receiver can localize itself to within 10.6 m. In the moving scenario, fusing non-beamformed TOA measurements to two 5G gNBs via an EKF yielded a two-dimensional position root mean-squared error (RMSE) of 8.1 m, while using beamformed TOA measurements reduced the RMSE to 5.4 m.