Opportunistic Navigation Using Sub-6 GHz 5G Downlink Signals: A Case Study on A Ground Vehicle

A user equipment (UE)-based navigation framework that opportunistically exploits 5G signals is developed. The proposed framework exploits the “always on” 5G downlink signals in a time-domain-based receiver. To this end, a so-called ultimate synchronization signal (USS) is proposed to utilize the time-domain orthogonality of the orthogonal frequency division multiplexing (OFDM)-based 5G signals. This approach simplifies the receiver's complexity and enhances the performance of the 5G opportunistic navigation framework. Experimental results are presented to evaluate the efficacy of the proposed framework on a ground vehicle navigating in a suburban environment, while utilizing sub-6 GHz 5G signals from two gNBs. It is shown that while a state-of-the-art frequency-domain-based 5G opportunistic navigation receiver can only reliably track the gNBs' signals over a trajectory of 1.02 km traversed in 100 seconds, producing a position root mean-squared error (RMSE) of 14.93 m; the proposed time-domain-based receiver was able to track over a trajectory of 2.17 km traversed in 230 seconds, achieving a position RMSE of 9.71 m.