Asynchronous Designs for Multiuser MIMO Wireless Powered Communication Networks

Abstract

This paper considers multiuser multiple-input multiple-output (MIMO) wireless powered communication networks (WPCNs). In this system, a multiantenna power beacon (PB) transfers wireless energy to several multiantenna users, and then the users transmit data to a multiantenna base station. Time durations for the energy harvesting (EH) operations at each user can be differently set based on the users' channel conditions, which results in an asynchronous protocol on the EH and the information transmission. We maximize the sum rate performance of the asynchronous WPCN by jointly optimizing the energy preceding matrices at the PB, the information preceding matrices, and the EH time durations at the users. By using convex optimization techniques, the optimal algorithm for the sum rate maximization problem is provided with analytical expressions of the optimal preceding matrices. Simulation results verify that the proposed optimal algorithm outperforms conventional schemes.