Intelligent Reflecting Surface Backscatter Downlink Multi-User Communications With Radar Sensing

This correspondence investigates a system of intelligent reflecting surface (IRS) backscatter downlink multi-user communications coexisting with radar sensing. In the system, the radar signal for target detection is harvested by the IRS to realize downlink communications with multiple users by using the backscatter technology. The goal of this work is to maximize the weighted sum bits per unit bandwidth for the communications by jointly designing the transmitting signal at the radar, the passive beamforming at the IRS, the time allocation among all the users, and the receiving beamforming at the radar. To address the corresponding non-convex optimization problem, a method of alternative optimization as well as fractional programming is developed to handle the objective function and the coupled optimization variables. The simulation results demonstrate the communication performance of system coexisting with the radar sensing and validate the feasibility of the proposed scheme.