Transceiver Design of Optimum Wirelessly Powered Full-Duplex MIMO IoT Devices

In this paper, we investigate the energy harvesting (EH) technique and accordingly design transceivers for a K link multiple-input multiple-output interference channel. Each link consists of two full-duplex (FD) Internet of Things (IoT) nodes exchanging information simultaneously in a bi-directional communication channel. All the nodes suffer from interference, in particular strong self-interference and inter-node interference, due to operating in FD mode and simultaneous transmission at each link, respectively. Further, we divide the received signal at each node into two parts. While one part of the signal is used for information decoding, the other part is used for EH. We jointly design the transmit and receive beamforming vectors and receiver power splitting ratios by minimizing the total transmission power of the system, subject to both signal-to-interference-plus-noise ratio and EH threshold constraints. Furthermore, the case of multiple-input single-output interference channel is also included for the sake of comparison. We also revisit the above problems for the case when the available channel state information (CSI) at the transmitters is imperfect, where the errors of the CSI are assumed to be norm bounded. Simulation results show that the EH technique can harvest enough energy to support power consumption limited IoT devices by aiding in recharging their respective batteries.

I. Introduction

Wireless data traffic has exponentially increased over the last decade and it is projected to increase even further. As a result, effective and efficient utilization of the scarce spectrum resources has become an extremely important issue. The currently deployed half-duplex (HD) wireless communication systems do not utilize the spectrum efficiently as transmission and reception happen orthogonally, either in time, denoted as time division duplexing (TDD), or in frequency, denoted as frequency division duplexing (FDD). Among the emerging technologies for next-generation wireless networks, full-duplex (FD) communication is considered as a way to potentially double the capacity of wireless communications. Simultaneous transmission and reception of overlapping signals in the same frequency had generally been assumed impossible in wireless communications due to the challenges involved in handling the self-interference [1], which is caused due to the signal received at the receive antennas of a FD node from its own transmitter antennas. However, thanks to the recent progress of cancellation made on self-interference suppression, FD communication systems have triggered enormous research interests [2], [3]. Consequently, FD is being considered as a key enabling technique for 5G and beyond systems [4], since it enables available spectral resources to be fully utilized in both time and frequency.