Simultaneous Wireless Information And Power Transfer Research Articles

Joint Resource Allocation in a Two-Way Relaying Simultaneous Wireless Information and Power Transfer System

Simultaneous wireless information and power transfer (SWIPT) technology provides an efficient solution to energy-limited communication terminals in a wireless network. However, in the current application scenario of SWIPT technology, relays use all the collected energy forwarding to assist communication between source nodes, while ignoring the fact that relays can accumulate and store energy. This is of great practical significance in collaborative communication. By using a transmission scheme of a time-division broadcast for the direct transmission link, improvement of the system diversity gain through combining the technology at the receiver can be realized. Based on the above, we propose a two-way relay energy accumulation communication system, which is extended from a single relay system to a multi-relay system. The instantaneous transmission rate of the system link and the system equivalent profit are optimized by jointly optimizing the relay selection, time slot allocation factor, power splitting factor and relay transmit power. Compared with the comparison algorithm, the proposed algorithm shows a significant improvement in the performance of the system.

Robust Sum-Rate Maximization in Transmissive RMS Transceiver-Enabled SWIPT Networks

In this article, we propose a state-of-the-art downlink communication transceiver design for transmissive reconfigurable metasurface (RMS)-enabled simultaneous wireless information and power transfer (SWIPT) networks. Specifically, a feed antenna is deployed in the transmissive RMS-based transceiver, which can be used to implement beamforming. According to the relationship between wavelength and propagation distance, the spatial propagation models of plane and spherical waves are built. Then, in the case of imperfect channel state information (CSI), we formulate a robust system sum-rate maximization problem that jointly optimizes RMS transmissive coefficient, transmit power allocation, and power splitting ratio design while taking account of the nonlinear energy harvesting model and outage probability criterion. Since the coupling of optimization variables, the whole optimization problem is nonconvex and cannot be solved directly. Therefore, the alternating optimization (AO) framework is implemented to decompose the nonconvex original problem. In detail, the whole problem is divided into three subproblems to solve. For the nonconvexity of the objective function, successive convex approximation (SCA) is used to transform it, and the penalty function method and difference-of-convex (DC) programming are applied to deal with the nonconvex constraints. Finally, we alternately solve the three subproblems until the entire optimization problem converges. Numerical results show that our proposed algorithm has convergence and better performance than other benchmark algorithms.

Energy‐efficient resource allocation and passive beamforming design for multiuser IRS‐aided OFDM SWIPT

This letter studies an OFDM based intelligent reflecting surface (IRS)‐aided multiuser simultaneous wireless information and power transfer (SWIPT) system. With subcarrier allocation, users use the assigned subcarriers for information decoding (ID), and use signals received on subcarriers allocated to other users for energy harvesting (EH). An optimization problem is formulated to maximize the system energy efficiency by jointly optimizing subcarrier and power allocation and IRS reflection coefficients matrix. It can be solved by an alternating optimization algorithm. Simulation results reveal that energy efficiency can be enhanced in our proposed scheme compared with the benchmark schemes.

Design of a Reconfigurable Intelligent Surface- Assisted FM-DCSK-SWIPT Scheme With Non-Linear Energy Harvesting Model

In this paper, we propose a reconfigurable intelligent surface (RIS)-assisted frequency-modulated (FM) differential chaos shift keying (DCSK) scheme with simultaneous wireless information and power transfer (SWIPT), called RIS-FM-DCSK-SWIPT scheme, for low-power, low-cost, and high-reliability wireless communication networks. In particular, the proposed scheme is developed under a non-linear energy-harvesting (EH) model which can accurately characterize the practical situation. The proposed RIS-FM-DCSK-SWIPT scheme has an appealing feature that it does not require channel state information, thus avoiding the complex channel estimation. We further derive the closed-form theoretical expressions for the energy shortage probability and bit error rate (BER) of the proposed scheme over the multipath Rayleigh fading channel. In addition, we investigate the influence of key parameters on the performance of the proposed transmission scheme in two different scenarios, i.e., RIS-assisted access point (RIS-AP) and dual-hop communication (RIS-DH). Finally, we carry out various Monte-Carlo experiments to verify the accuracy of the theoretical derivation, illustrate the performance advantage of the proposed scheme, and give some design insights for future study.

SecGreen: Secrecy Ensured Power Optimization Scheme for Software-Defined Connected IoV

Software-Defined Internet of Vehicles (SD-IoV) is an emerging technology that is being used in modern intelligent transportation systems (ITS). The ultimate goal of SD-IoV is to provide seamless connectivity to the end-users with low latency and high-speed data transfer. However, due to the increase in the density of the connected IoV using an open channel, i.e., the Internet, the foremost challenges of high power consumption and secure data transfer are inevitable in such an environment. An external eavesdropper may intercept the transmitted message to access the legitimate information over the public channel, i.e., the Internet. Most of the solutions reported in the literature to tackle these issues may not be applicable in the SD-IoV environment due to high computation and communication costs. Motivated from this, in this paper, the problems of high power consumption and secure data transfer in SD-IoV are formulated using mixed-integer non-linear programming (MINLP) with associated constraints. To solve the aforementioned problem, we propose a joint power optimization and secrecy ensured scheme known as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SecGreen</i> . <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SecGreen</i> has an efficient energy harvesting algorithm using simultaneous wireless information and power transfer (SWIPT) to maximize the energy efficiency. Moreover, to mitigate various security attacks, a resilient lightweight secrecy association protocol is designed between vehicle and trusted gateway node of SD-IoV so that only trusted vehicles can communicate with each other and with the nearest base stations. The secrecy association protocol uses security primitives such as– physically unclonable function (PUF), one-way hash function, and bitwise exclusive OR (XOR) operations which are suitable for energy-constraint sensors in SD-IoV. The performance of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SecGreen</i> is compared with the existing schemes, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Stable &amp; Scalable Link Optimization (SSLO), and Secure &amp; Energy-Efficient Blockchain-enabled (SEEB)</i> respectively. The result shows that when the number of packets across the subchannel increases, the energy consumption increases. Also, the result shows that the proposed scheme attains 22.5% and 20.34% better energy efficiency as compared to SSLO and SEEB schemes, respectively. In addition, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SecGreen</i> scheme achieves 37.48% and 32.15% higher throughput as compared to SSLO and SEEB schemes. The results obtained show the superior performance of the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SecGreen</i> scheme in comparison to these existing competitive schemes in the literature.

Transmission Design for Active RIS-Aided Simultaneous Wireless Information and Power Transfer

Reconfigurable intelligent surface (RIS) is a revolutionary technology to enhance both the spectral efficiency and energy efficiency of wireless communication systems. However, most of the existing contributions mainly focused on the study of passive RIS, which suffers from the “double fading” effect. On the other hand, active RIS, which is equipped with amplifiers, can effectively address this issue. In this letter, we propose an active RIS-aided simultaneous wireless information and power transfer (SWIPT) system. Specifically, we maximize the weighted sum rate of the information receivers, subject to the minimum power received at all energy receivers, amplification power constraint at the active RIS, and the maximum transmit power constraint at the base station (BS). By adopting alternating optimization framework, suboptimal solutions are obtained. Simulation results show that the active RIS-aided SWIPT system has higher performance gain with the same power budget.

RF Energy Harvesting and Wireless Power Transfer for Energy Autonomous Wireless Devices and RFIDs

Radio frequency (RF) energy harvesting and wireless power transmission (WPT) technologies —both near-field and far-field—have attracted significant interest for wireless applications and RFID systems. We already utilize near-field WPT products in our life and it is expected that RF EH and far-field WPT systems can drive the future low-power wireless systems. In this article, we initially present a brief historical overview of these technologies. The main technical challenges of rectennas and WPT transmitters are discussed. Furthermore, this paper presents the recent advances on the development of these technologies, including the possibility of powering RFID systems through the millimeter wave power from 5G networks, the trends in flexible rectennas design and the technological developments on the simultaneous wireless information and power transfer (SWIPT).

System Outage Performance of SWIPT Enabled Full-Duplex Two-Way Relaying With Residual Hardware Impairments and Self-Interference

This article investigates the joint impact of residual hardware impairments (RHIs) and residual self-interference (RSI) at all transceivers on the system outage performance for a simultaneous wireless information and power transfer (SWIPT) enabled full-duplex two-way decode-and-forward (DF) relay network. Considering a time switching scheme at the relay node, we derive the system outage probability in a closed-form, and further identify the overall system ceiling (OSC) effect caused by only RHIs. More specifically, when the data rate exceeds the OSC threshold determined by the RHIs level, the communication of the entire network ceases no matter what the signal-to-noise ratio is. In addition, we derive the achievable diversity gain of the considered network, and demonstrate that the diversity gain always equals zero due to the existence of RHIs and RSI. Finally, numerical simulations are provided to study the influence of multifarious network parameters on the system outage performance and the performance gap between the DF and amplify-and-forward strategies.

A Detection Scheme for Integrated SWIPT Receivers With Rectenna Arrays

Smart devices and their applications led to a rapid evolution of the Internet of Things. As a result, there is an emerging need on energizing those low-power devices, while at the same time achieving information transfer. In this context, simultaneous wireless information and power transfer (SWIPT) is considered as an appealing technology, since it can power wirelessly and remotely such devices, simultaneously with information transfer. Motivated by this, we herein propose a system model with an integrated SWIPT receiver, succeeding enhanced performance in terms of information decoding (ID) and energy harvested (EH). Specifically, we adopt a single input multiple output topology, where at the receiver’s side we examine two antenna architectures, one based on the direct-current (DC) combining and the other on the radio-frequency (RF) combining. For both schemes, we consider multiple receive antennas and rectifiers, comparing their performances. Furthermore, we adopt a piece-wise linear EH model, which takes into account the sensitivity and saturation effects of the rectifiers. By using a maximum likelihood-based soft decoding, a non-coherent energy detection is achieved. Finally, an asymptotic analysis is conducted, providing upper and lower bounds for ID and EH, respectively. Simulation results along with theoretical analysis, validate the enhanced performance both in terms of ID and EH.

Simultaneous Wireless Information and Power Transfer in mmWave Networks Under User-Centric Base Station Clustering

User-centric base station (BS) deployment has been designed for the fifth-generation (5G) dense millimeter wave (mmWave) networks for alleviating the inter-cell interference and improving the cell-edge user experience. However, the system power consumption increases sharply with the network density. In this paper, we investigate a user-centric simultaneous wireless information and power transfer (SWIPT) mmWave system employing a time-switching protocol at users to allow both energy harvesting (EH) and data decoding. To enable user-centric BS cooperation, adaptive BS clustering model is used to determine the user’s serving cluster based on its channel condition. Considering both linear and non-linear EH models, we analyze the joint coverage, namely, the probability that the user harvests enough energy in a given time slot and receives the required data from its serving cluster. The random serving clusters and the correlation between the amount of harvested energy and received data rate make the joint coverage analysis more challenging. A tractable tight approximation of the joint coverage probability is thus derived for ultra-dense networks. A mathematical optimization model for the time switching coefficient is also developed to maximize the system joint rate and energy coverage performance. All mathematical expressions are validated by Monte-Carlo simulations. Our results show that the proposed analytical framework is accurate and efficient for the design and deployment of SWIPT-enabled user-centric mmWave networks.

Mixed RF/FSO SWIPT-Based OSLMD Coded AF Cooperative Communication System: Performance Analysis

In this paper, the performance analysis of simultaneous wireless information and power transfer (SWIPT) using time switching (TS) protocol-based amplify-and-forward (AF) dual-hop mixed radio-frequency/free-space optic (RF/FSO) coded and uncoded communication system (CC and UC) is investigated. Specifically, we look at using the One-Step Majority-Logic Decodable (OSMLD) codes at the source and a majority logic decoding algorithm (MLGD) at the destination, jointly with the use of maximal-ratio combining and SWIPT/TS techniques at the relay. Furthermore, the RF link undergoes Nakagami- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$m$ </tex-math></inline-formula> model, while the second-hop is subject to Máalaga- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal {M}$ </tex-math></inline-formula> atmospheric turbulence with the effect of pointing errors. Closed-form and asymptotic formulations for the average bit error probability (ABEP) are obtained in terms of the system parameters for both CC and UC scenarios in addition of the average channel capacity analysis. Computer-based Monte Carlo simulations were used to numerically validate all of the obtained mathematical formulations. Expectedly, it is shown that significant coding gains are achieved using OSMLD codes in comparison with UC. In addition, above a specific threshold of energy efficiency, the system performance gets steady in the high signal-to-noise-ratio regime. Moreover, the decoding method used in this work has been shown to be suitable for the SWIPT/TS-assisted RF/FSO coded AF cooperative communication system where high performance alongside low computational complexity are required.

An energy balance cluster network framework based on Simultaneous Wireless Information and Power Transfer

Wireless NanoSensor Network (WNSN) is a brand-new type of sensor network with broad application prospects. In view of the limited energy of nano-nodes and unstable links in WNSNs, we propose an energy balance cluster network framework (EBCNF) based on Simultaneous Wireless Information and Power Transfer (SWIPT). The EBCNF framework extends the network lifetime of nano-nodes and uses a clustering algorithm called EBACC (an energy balance algorithm for intra-cluster and inter-cluster nodes) to make the energy consumption of nodes more uniform. Simulation shows that the EBCNF framework can make the network energy consumption more uniform, reduce the error rate of data transmission and the average network throughput, and can be used as an effective routing framework for WNSNs.

Outage performance of NOMA with Alamouti/MRC in dual-hop energy harvesting relay networks

This paper presents outage performance of Alamouti coding/maximum ratio combining (Alamouti/MRC) scheme in dual-hop non-orthogonal multiple access network taking advantage of simultaneous wireless information and power transfer (SWIPT). In the considered system, a base station simultaneously serves multiple users via energy harvesting enabled amplify-and-forward relay by exploiting Alamouti coding, and the users employ MRC technique. Thereby, not only spatial diversity is exploited but also channel state information burden can be reduced in terms of transmit diversity, in addition to increasing energy efficiency by SWIPT. Exact outage probability for any user is obtained over Nakagami-m fading channels by considering the channel estimation error (CEE), together with asymptotic expression providing more valuable insights. Besides, the sum throughput and energy efficiency are also investigated to characterize the system performance. Finally, the analytical results are verified by the Monte Carlo simulations. Results show that a variety of trade-off cases arise for optimum performance.

When DSA Meets SWIPT: A Joint Power Allocation and Time Splitting Scheme Based on Multi-Agent Deep Reinforcement Learning

Dynamic spectrum access (DSA) and simultaneously wireless information and power transfer (SWIPT) are two promising approaches to address the spectrum and energy supply problems. However, most existing works studied these two techniques separately, and how to effectively realize them simultaneously is non-trivial, because the power allocation of DSA and time splitting of SWIPT will influence both data transmission and energy harvesting performance. Hence, a sophisticated joint design is necessary, which, however, is challenging considering the uncertain dynamic spectrum environment. In this paper, we propose a joint power allocation and time splitting scheme to facilitate devices to implement both DSA and SWIPT simultaneously, which aims at maximizing the long-term throughput while ensuring the interference limitation and energy supply requirements. Considering the environmental uncertainty, we develop a multi-agent deep reinforcement learning solution to make each device autonomously select the best decision that could optimize the whole network performance based on its local observations. Simulation results have shown the effectiveness of the proposed scheme.

User Scheduling and Trajectory Optimization for Energy-Efficient IRS-UAV Networks With SWIPT

This paper investigates user scheduling and trajectory optimization for a network supported by an intelligent reflecting surface (IRS) mounted on an unmanned aerial vehicle (UAV). The IRS is powered via the simultaneous wireless information and power transfer (SWIPT) technique. The IRS boosts users uplink signals to improve the network longevity and energy efficiency. It simultaneously harvests energy with a non-linear energy harvesting circuit and reflects the incident signals by controlling its reflection coefficients and phase shifts. The trajectory of the UAV impacts the efficiency of these operations. We minimize the maximum energy consumption of all users by joint optimization of user scheduling, UAV trajectory/velocity, and IRS phase shifts/reflection coefficients while guaranteeing each user minimum required data rate and harvested energy of the IRS. We first derive a closed-form solution for the IRS phase shifts and then address the non-convexity of the critical problem. Finally, we propose an alternating optimization (AO) algorithm to optimize the remaining variables iteratively. We demonstrate the gains over several benchmarks. For instance, with a 50-element IRS, min-max energy consumption can be as low as 0.0404 (Joule), a 7.13% improvement over the No IRS case (achieving 0.0435 (Joule)). We also show that IRS-UAV without EH performs best at the cost of circuit power consumption of the IRS (a 20% improvement over the No IRS case).

Energy-Efficiency Optimization for D2D Communications Underlaying UAV-Assisted Industrial IoT Networks With SWIPT

The Industrial Internet of Things (IIoT) has been viewed as a typical application for the fifth generation (5G) mobile networks. This article investigates the energy efficiency (EE) optimization problem for the Device-to-Device (D2D) communications underlaying unmanned aerial vehicles (UAVs)-assisted IIoT networks with simultaneous wireless information and power transfer (SWIPT). We aim to maximize the EE of the system while satisfying the constraints of transmission rate and transmission power budget. However, the designed EE optimization problem is nonconvex involving joint optimization of the UAV’s location, beam pattern, power control, and time scheduling, which is difficult to tackle directly. To solve this problem, we present a joint UAV location and resource allocation algorithm to decouple the original problem into several subproblems and solve them sequentially. Specifically, we first apply the Dinkelbach method to transform the fraction problem to a subtractive-form one and propose a mulitiobjective evolutionary algorithm based on decomposition (MOEA/D)-based algorithm to optimize the beam pattern. We then optimize UAV’s location and power control using the successive convex optimization techniques. Finally, after solving the above variables, the original problem can be transformed into a single-variable problem with respect to the charging time, which is linear and can be tackled directly. Numerical results verify that significant EE gain can be obtained by our proposed algorithm as compared to the benchmark schemes.

Harvested Power Fairness-Based Multi-Carrier NOMA IoT Networks With SWIPT

The integration of simultaneous wireless information and power transfer (SWIPT) in multi-carrier non-orthogonal multiple access (NOMA) systems has been recently investigated as a potential paradigm to improve the lifespan of energy-constrained Internet-of-Things networks. In this letter, we develop a fairness-aware design for a multi-carrier NOMA SWIPT-based system that attempts to maximize the minimum harvested power subject to quality-of-service constraints. With this design, each user’s power allocation, and the power splitting ratio are jointly computed by solving the corresponding optimization problem. To deal with the non-convexity nature of the formulated max-min optimization problem, an iterative mechanism with a second-order cone method is proposed. Simulation results indicate that our design maintains a better user fairness with respect to the harvested power.

Coded Asymmetric Modulation Design for Block-Fading Channels With Nonlinear Energy Harvesting

In this letter, the design of coded modulation for simultaneous wireless information and power transfer (SWIPT) block-fading channels is proposed, for both power-splitting (PS) and time-switching (TS) nonlinear energy harvesting (EH). With PS, although the diversity-rate tradeoff is not affected, nonlinear EH requires asymmetric modulations design which leads to an information transfer (IT) performance penalty. We thus design an asymmetric circular quadrature amplitude modulation (ACQAM) scheme that provides large performance gains compared to conventional modulations. On the other hand, we show that TS negatively impacts the diversity-rate tradeoff of the coded modulation, while an optimal QAM can be employed in the IT phase. We next derive an upper bound on the average word error rate (WER) based on a pairwise error probability analysis for both EH methods. Finally, WER simulation results are shown together with the derived bounds.

Design of a Simultaneous Information and Power Transfer System Based on a Modulating Feature of Magnetron

According to the nonlinear response characteristics of magnetron, this article proves that a 2.45 GHz band continuous-wave magnetron can perform as a modulator in communication system. The intermediate frequency (IF) signal coupled to the power supply of magnetron, as the ripple of anode voltage, can be modulated to a nearby band centered on the resonant frequency of magnetron. We deduced the output expression of free oscillating magnetron under the influence of anode voltage ripple. And electromagnetic simulation was accomplished to testify the validity of the theoretical derivation. Moreover, we designed the circuit to couple signal with frequencies of 2, 3, and 4 MHz to the anode voltage. The output spectrum of magnetron changed as the frequencies were tuned, to satisfy the frequency requirements for modulating. Finally, a simultaneous information and power transfer system based on a magnetron combined with the power supply coupling circuit was developed and tested. This system achieved the modulation, amplification, transmission, and demodulation of low-frequency signal which is equivalent to human voice. This research reveals that the proposed techniques have great potential for future simultaneous wireless information and power transfer (SWIPT) system because they provide higher power at lower cost.

Hybrid Time-Switching and Power-Splitting EH Relaying for RIS-NOMA Downlink

Reconfigurable intelligent surface (RIS) offers a potential performance boost for next-generation wireless networks, with significant improvements in spectral and energy efficiencies. In this paper, considering a two-user multiple-input single-output non-orthogonal multiple access (MISO-NOMA) downlink, we propose a RIS-aided cooperative transmission scheme using hybrid simultaneous wireless information and power transfer (SWIPT) and transmit antenna selection (TAS) protocols. Particularly, in the proposed scheme, the cell-center user servering as a relay helps the cell-edge user with the support of hybrid time-switching (TS), power-splitting (PS) SWIPT protocols and RIS passive beamforming. To evaluate the network performance, we first derive the best- and worst-case of closed-form expressions in terms of outage probability. For gleaning further insights, we also investigate the diversity order and the high signal-to-noise ratio (SNR) slope for the relevant outage probability. Simulation and numerical results demonstrate the achievable performance improvement for our proposed scheme with respect to schemes of orthogonal multiple access (OMA), non-cooperative NOMA and cooperative NOMA without RIS. In addition, the proposed scheme achieves a higher diversity gain with more transmit antennas and RIS elements.