Uplink and Downlink Communications Fusion for Enhanced Radar Sensing

This paper proposes reusing uplink (UL) and downlink (DL) communication signals for target sensing. In this scenario, the dual functional radar and communication (DFRC) base station (BS) listens to the DL backscattered signal on a dedicated frequency band, as well as the UL signals transmitted by communication users via a frequency-division duplex protocol. The DL backscattered signal is sensed through a mono-static radar scheme, whereas the UL backscattered signal naturally forms a bi-static one. We derive the maximum likelihood criterion of the sensing problem, and propose an efficient iterative method to solve it. Simulations show the promising potential of the hybrid radar model and the capability of the proposed method to reach the Cramér-Rao bound.