Opportunistic Navigation Exploiting Always-On and On-Demand 5G Downlink Signals on a Ground Vehicle

An opportunistic navigation receiver that exploits always-on and on-demand 5G downlink signals is presented. The semi-cognitive receiver operates in two stages: (i) acquisition, which utilizes the "always-on" signals to detect gNBs, and (ii) Kalman filter (KF)-based tracking, which continuously estimates the on-demand reference signals (RSs) to refine the receiver’s local replica. Experimental results show that the estimated replica effectively utilizes nearly the entire channel bandwidth, spans almost all orthogonal frequency division multiplexing (OFDM) symbols for longer integration time, and achieves higher processing gain, enhancing the carrier-to-noise ratio for reliable acquisition and tracking. An experiment with real 5G signals on a ground vehicle demonstrated a significant 62% reduction in position root-mean squared error (RMSE) compared to a conventional opportunistic navigation 5G receiver which only utilized always-on signals.