Transmission design for ISAC-WPT backscatter RFID systems

In this letter, a novel integrated sensing and communication (ISAC) scenario with wireless power transfer (ISAC-WPT) is investigated. In this new setup, an access point simultaneously employs communication and sensing beams to serve a communication user, detect an RFID tag, and power an energy receiver. The objective is to design the sensing and communication beams to minimize the total transmit power while satisfying the requirements of tag detection, communication, and energy harvesting. To address the corresponding non-convex problem, the constraints are reformulated into convex second-order cone constraints, thereby obtaining the globally optimal solution. To further reduce computational complexity, zero-forcing is employed to design the beamforming vectors, followed by solving a convex optimization problem to determine the optimal power allocation between sensing and communication beams. The simulation results demonstrate the effectiveness of the proposed beamforming designs, highlighting the potential of ISAC-WPT Backscatter RFID systems.