In this paper, we investigate the problem of tworelay beamforming optimization to maximize the achievable sumrate of a simultaneous wireless information and power transfer (SWIPT) system with a full-duplex (FD) multiple-input multipleoutput (MIMO) amplify-and-forward (AF) relay. In particular, we address the optimal joint design of the receiver power splitting (PS) ratio and the beamforming matrix at the relay given the channel state information (CSI). Our contribution is an iterative algorithm and one-dimensional (1-D) search to achieve the joint optimization. Simulation results are provided to demonstrate the effectiveness of the proposed algorithm.

Abstract-This paper studies the joint optimization problem of two-way relay beamforming, the receiver power splitting (PS) ratio as well as the transmit power at the sources to maximize the achievable sum-rate of a simultaneous wireless information and power transfer (SWIPT) system with a full-duplex (FD) multipleinput multiple-output (MIMO) amplify and forward (AF) relay, assuming perfect channel state information (CSI). In particular, our contribution is an iterative algorithm based on the difference of convex programming (DC) and one dimensional searching to achieve the joint solution. Simulation results are provided to demonstrate the effectiveness of the proposed algorithm. I. INTRODUCTIONTraditionally, wireless communication systems use a timedivision or frequency-division approach to bidirectional communication. This involves dividing the spectral resources into orthogonal component resulting in half-duplex (HD) communication. Recent advances, nevertheless, suggest that fullduplex (FD) communication that allows simultaneous transmission and reception of signal over the same radio channel be possible [1]. Since radio signals that carry information can also be used as a vehicle for transporting energy, the emergence of FD technology brings a new opportunity for simultaneous wireless information and power transfer (SWIPT) [2], [3]. A practical application of SWIPT technology is seen in battery-limited devices such as sensor nodes mounted at some inaccessible or difficult-to-access locations [4], [5].Recently, much interest has turned to FD relaying in which information is sent from a source node to a destination node through an intermediate FD relaying node. In the literature, relay aided SWIPT systems have been largely considered for HD relaying [6]. Recently, the authors in [7] considered SWIPT in FD relaying where only the relay node works in FD mode. Most recently, [3] considered SWIPT in FD multipleinput multiple-output (MIMO) relay system and used a power splitting (PS) relaying approach with fixed transmit power at the source nodes. However, the transmit power in FD systems affects the self-interference (SI) and careful optimization is necessary in order to maximize the achievable rate.

This letter studies bi-directional secure information exchange in a simultaneous wireless information and power transfer (SWIPT) system enabled by a full-duplex (FD) multipleinput multiple-output (MIMO) amplify-and-forward (AF) relay. The AF relay injects artificial noise (AN) in order to confuse the eavesdropper. Specifically, we assume a zeroforcing (ZF) solution constraint to eliminate the residual self-interference (RSI). As a consequence, we address the optimal joint design of the ZF matrix and the AN covariance matrix at the relay node as well as the transmit power at the sources. We propose an alternating algorithm utilizing semi-definite programming (SDP) technique and one-dimensional searching to achieve the optimal solution. Simulation results are provided to demonstrate the effectiveness of the proposed algorithm.

Abstract-This paper considers the problem of maximizing the sum-rate for simultaneous wireless information and power transfer (SWIFT) in a full-duplex bi-directional communication system subject to energy harvesting and transmit power constraints at both nodes. We investigate the optimum design of the receive power splitters and transmit powers for SWIFT in full-duplex mode. Exploiting rate-split method, an iterative algorithm is derived to solve the non-convex problem. The effectiveness of the proposed algorithm is justified through numerical simulations.

This paper investigates a multiuser multiple-input single-output (MISO) full-duplex (FD) system for simultaneous wireless information and power transfer (SWIPT), in which a multi-antenna base station (BS) simultaneously sends wirelessly information and power to a set of single-antenna mobile stations (MSs) using power splitters (PSs) in the downlink and receives information in the uplink in FD mode. In particular, we address the joint design of the receive PS ratio and the transmit power at the MSs, and the beamforming matrix at the BS under signalto-interference-plus-noise ratio (SINR) and the harvested power constraints. Using semidefinite relaxation (SDR), we obtain the solution to the problem with imperfect channel state information (CSI) of the self-interfering channels. Furthermore, we propose another suboptimal zero-forcing (ZF) based solution by separating the optimization of the transmit beamforming vector and the PS ratio. Simulation results are provided to evaluate the performance of the proposed beamforming designs.

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For several decades, rural electrification has remained a formidable challenge, particularly in Nigeria. Financial constraints, difficult rural terrain, inefficient policy, and a lack of industrial community development have all contributed to the grid expansion problem in these areas. These areas are energy-deficient, and their energy demands to keep up with cutting-edge communication technology are constantly rising. As a result, rural areas are confronted with the issue of charging. Consequently, many rural residents are forced to rely on diesel/petrol generators or travel long distances and pay a premium to have their mobile phones charged. Thus, this paper proposes an off-grid solar-powered charging system as an alternative, sustainable solution to meet rural mobile phone energy demand. The methodology employed six-tier architectural features, with the economic comparison metric based on net present value and payback period. Furthermore, the proposed model's performance analysis revealed that the charging rate is dependent on the phone battery type and charger type. Furthermore, the off-grid mobile charging system has a higher net present value ($20,658US) and a shorter payback period of 2.5 years than the alternative investment of a gasolne generator.