Transmitter Design in MISO-NOMA System With Wireless-Power Supply

This letter investigated a wireless-powered multiple-input single-output non-orthogonal multiple access downlink system, where an energy-constrained full-duplex (FD) information transmitter (IT) harvests energy from a dedicated energy transmitter (ET) and its loop channel, while IT transmits information to the information receivers (IRs). Given the quality-of-service requirements of the IRs and the constraint of the FD IT's transmit power, the minimal transmit power of the ET and the corresponding optimal beamforming vectors are obtained by applying the technique of semidefinite relaxation (SDR). Moreover, the tightness of the SDR is proved by showing the existence of the rank-one optimal solution. Then, suboptimal scheme based on interference-nulling in closed-form is also proposed by applying the Lagrangian duality method.

I. Introduction

Non-orthogonal multiple access (NOMA) has been recognized as an effective multiple access technique to solve the shortage of spectrum in next generation mobile networks, and it uses the power domain multiplexing at the transceiver to serve multiple users in the same time/code/frequency channels. The user with better channel conditions employs successive interference cancellation (SIC) to decode its own information [1], [2], which can increase the spectrum efficiency at the cost of complexity, especially combining NOMA with multiple-input and multiple-output (MIMO) [3], [4] or multiple-input and single-output (MISO) [5].