This code was tested on my computer and found to be error-free. Please practise using YALMIP and solvers such as SDPT-3, MOSEK, and others before running the code.
T. N. Do, V. Nguyen, O. Shin and B. An, "Simultaneous Uplink and Downlink Transmissions for Wireless Powered Communication Networks," in IEEE Communications Letters, vol. 23, no. 2, pp. 374-377, Feb. 2019.