Investigating the Bistatic Sensing Capability of a Broadcasting 5G-NR BS and a True-Time-Delay Array UE

This paper derives the theoretical sensing capability of the 5G NR synchronization signal (SS) with a True-Time-Delay (TTD) array configuration at UE side. The TTD beamformer separates subcarrier beams into different angular locations for wide-beam coverage, and could potentially be used for opportunistic sensing of environment targets surrounding UE during BS downlink synchronization (before communication data transmission). The bistatic sensing performance is described by the derived bistatic AoA(Angle of Arrival)-delay/range-Doppler ambiguity function. The shape of the ambiguity function in the angular-delay domain with a slowly fluctuating target is observed to vary as a function of the number of array elements, the opening angles of sub carrier beam, the different SS configuration, as well as the target reflectivity. It is shown that with sufficient UE TTD array elements and for the given 5G NR SS block configurations, it is possible to detect environment target and its location, with the help of the extended coverage enabled by the opening of UE's sub carrier beams.