Resource Allocation for IRS Assisted mmWave Wireless Powered Sensor Networks with User Cooperation

In this paper, we investigate IRS-aided user cooperation (UC) scheme in millimeter wave (mmWave) wireless -powered sensor networks (WPSN), where two single-antenna users are wireless powered in the wireless energy transfer (WET) phase first and then cooperatively transmit information to a hybrid access point (AP) in the wireless information transmission (WIT) phase, following which the IRS is deployed to enhance the system performance of the WET and WIT. We maximized the weighted sum-rate problem by jointly optimizing the transmit time slots, power allocations, and the phase shifts of the IRS. Due to the non-convexity of the original problem, a semidefinite programming relaxation-based approach is proposed to convert the formulated problem to a convex optimization framework, which can obtain the optimal global solution. Simulation results demonstrate that the weighted sum throughput of the proposed UC scheme outperforms the non-UC scheme whether equipped with IRS or not.