Exploiting On-Demand 5G Downlink Signals for Opportunistic Navigation

This letter presents the first user equipment (UE)-based 5G navigation framework that exploits the "on-demand" 5G downlink signals. In this framework, the entire system bandwidth of incoming 5G signals is utilized in an opportunistic fashion. The proposed framework involves a cognitive approach to acquire the so-called ultimate reference signal (URS), which includes the "on-demand" as well as "always-on" reference signals (RSs). Experimental results are presented showing that the acquired URS: (i) spans the entire 5G downlink bandwidth, (ii) increases the carrier-to-noise ratio by 10 dB compared to state-of-the-art 5G user equipment (UE)-based opportunistic navigation receiver, and (iii) reduces significantly the carrier and code phase errors. A ranging error standard deviation of 2.75 m was achieved with proposed framework with a stationary receiver placed 290 m away from a 5G gNB in a clear line-of-sight environment, which is lower than the 5.05 m achieved when using the "always-on" 5G downlink signals.