Simultaneous Wireless Information and Power Transfer Based on Generalized Triangular Decomposition

Chapter 10 - Transmit beamforming for simultaneous wireless information and power transfer

5G-based green broadband communication system design with simultaneous wireless information and power transfer

Radio frequency (RF) signals have been relied upon for both wireless information delivery and wireless charging to the massively deployed low-power Internet of Things (IoT) devices. Extensive efforts have been invested in physical layer and medium-access-control layer design for coordinating simultaneous wireless information and power transfer (SWIPT) in RF bands. Different from the existing works, we study the coding controlled SWIPT from the information theoretical perspective with practical transceiver. Due to its practical decoding implementation and its flexibility on the codeword structure, unary code is chosen for joint information and energy encoding. Wireless power transfer (WPT) performance in terms of energy harvested per binary sign and of battery overflow/underflow probability is maximised by optimising the codeword distribution of coded information source, while satisfying required wireless information transfer (WIT) performance in terms of mutual information. Furthermore, a Genetic Algorithm (GA) aided coding design is proposed to reduce the computational complexity. Numerical results characterise the SWIPT performance and validate the optimality of our proposed GA aided unary coding design.

This paper studies the simultaneous wireless information and power transfer (SWIPT) in the multi-carrier differential chaos shift keying (MC-DCSK) communication system. Two energy harvesting protocols with a power splitting (PS) receiver are considered. In the first protocol, only a fraction of reference sub-carrier signal are used for energy harvesting (EH). In another one, a fraction of all sub-carriers signal are used for EH. We derive the error performance of information decoding (ID) of the two protocols with harvested energy constraints. Then we further optimize the power allocation on sub-carriers by minimizing bit error ratio (BER) of information decoding. The tradeoffs between error performance and harvested energy are obtained with the optimal sub-carrier power ratio. In addition, we compare the throughput and harvested energy of two protocols with total transmitted power and bandwidth constraints.

In this paper, we investigate a new approach for simultaneous wireless information and power transfer (SWIPT) in point-to-point multiple-input multiple-output (MIMO) system with spatial switching (SS) reception. The new approach is based on the generalized triangular decomposition (GTD). The approach takes advantage of the GTD structure to allow the transmitter to use the strongest subchannel jointly for energy harvesting and information exchange while these transmissions can be separated at the receiver to comply with the SS system requirements. An optimal solution is developed in the paper for SWIPT based on GTD that jointly obtains the optimal subchannels assignment and maximizes the total data rate while meeting the minimum requirement of the harvested energy with limited total transmitted power. The theoretical and numerical results presented in this paper show that the proposed approach significantly outperforms the state of the art spatial domain SWIPT systems based on the singular value decomposition (SVD).

Antenna beamforming for Simultaneous Wireless Information and Power Transfer (SWIPT) and Wireless Power Transfer (WPT) in an indoor 6G communication system is presented in this paper. The objective function is to maximize the total harvesting power for the SWIPT and WPT nodes with the constraints of the bit error rate and minimum harvesting power. In the study, the power-splitting ratio between harvesting power and decoding information can be adjusted for the SWIPT node. Due to the non-convex problem, we use Self-Adaptive Dynamic Differential Evolution (SADDE) to optimize the designed multi-objective function. We use a symmetric antenna array to study three situations of distance—closer, farther, and similar—between the transmitting antenna and the individual SWIPT and WPT nodes in this paper. Experimental results show that the overall harvesting efficiency is improved, especially in the case of SWIPT nodes closer to the transmitter. The total harvesting power can be improved by 86.7% in the total short-distance case, and by 7.87% in the total long-distance case.

SummaryRadio frequency (RF) energy harvesting (EH) for wireless networks provides a green and sustainable solution and offers an energy‐efficient system. It is most crucial for fulfilling the power requirement of the rising number of low‐powered wireless devices and achieving sustainable development goals (SDG). It ensures the longevity of devices in the network even at inaccessible remote locations. Such RF‐EH‐based mechanisms are utilized in simultaneous wireless information and power transfer (SWIPT) systems. Most of the prevailing studies have analyzed the SWIPT system over conventional fading channels. However, due to the higher rate requirements, the current paradigm shift in frequency usage shifts towards the GHz band, which also offers better EH efficiency. Hence, SWIPT system analysis over the channel that is suitable for mm‐wave signal propagation is dealt with in this study. This study evaluates SWIPT performance over fluctuating two‐ray (FTR) fading channel that is crucial since it provides the best fit for characterizing GHz signal and also provides a generalized framework for most of the conventional fading channels. This study presents new analytical results assuming time switch relaying (TSR) protocol with (i) amplify and forward (AF) and (ii) decode and forward (DF) relaying. The results are also analyzed for H branches maximal ratio combining (MRC) diversity technique and evaluated the diversity gain for both AF and DF relays. The effectiveness of the system is measured in terms of system outage probability (SOP) to envisage the reliability of SWIPT based system. This work presents the simulation and modeling of such system and its obtained results are validated by Monte Carlo simulations for their accuracy.

In this paper, we provide a comprehensive literature survey on simultaneous wireless information and power transfer (SWIPT) in multi-antenna systems. We first review recent contributions on the theory analysis of SWIPT from information theoretic standpoint and introduce the tradeoff between information transfer and power transfer under various settings. Then, we focus on the utilization of multi-antenna techniques to solve existing problems of SWIPT. Contributions on the implementation aspects of multi-antenna SWIPT are summarized. The performance of SWIPT is evaluated by different metrics, therefore, we review the works on dynamic SWIPT optimization based on objective function using multi-antenna techniques. In addition, the implementation of SWIPT brings up secure issue. Thus, we summarize recent works on secure SWIPT. Finally, we present researches combining SWIPT with state-of-the-art techniques due to potential application in different scenarios.

In this paper, we investigate the performance of cache-assisted simultaneous wireless information and power transfer (SWIPT) cooperative systems, in which one source communicates with one destination via the aid of multiple relays. In order to prolong the relays’ serving time, the relays are assumed to be equipped with a cache memory and energy harvesting (EH) capability. Based on the time-splitting mechanism, we analyze the effect of caching on the system performance in terms of the serving throughput and the stored energy at the relay. In particular, two optimization problems are formulated to maximize the relay-destination throughput and the energy stored at the relay subject to some quality-of-service (QoS) constraints, respectively. By using the KKT conditions and with the help of the Lambert function, closed-form solutions are obtained for the two formulated problems. In order to further improve the performance, a relay selection policy is introduced to select the best relay based on either the maximum throughput between the relays’ and destination link or maximum stored energy at the relay, for conveying information to the destination. Numerical results reveal significant benefits of incorporating caching capabilities to SWIPT systems, in terms of improved serving time, throughput, and EH performance at the relays.

Simultaneous wireless information and power transfer (SWIPT) formed by the mixture of communication technology and power transmission is one of the research focuses in the field of wireless communication. This paper introduces the architecture of the SWIPT system, analyzes the key technologies, presents a 2.45GHz microwave rectifier circuit at low input power for energy harvesting. Finally, with the use of Ultra-Narrow Band (UNB) as the modulation scheme, the practical SWIPT receiver system is modeled and simulated. The results provide that using UNB signal as the modulation scheme is a new feasible way for SWIPT.

This letter puts forth a novel way to manage interference in simultaneous wireless information and power transfer (SWIPT) systems by utilizing physical-layer network coding (PNC). We consider multi-user multiple-input single-output (MU-MISO) broadcast channels. Unlike the conventional zero-forcing scheme, the PNC-SWIPT scheme introduced in this letter does not eliminate the interfering signals at the receivers. The PNC-SWIPT scheme cancels out the undesired messages over a finite field during PNC demodulation for information decoding (ID). It preserves the interfering signals which are beneficial energy sources for energy harvesting (EH). Simulation results show that the PNC-SWIPT scheme achieves superior EH performance than conventional interference mitigation schemes, such as zero-forcing (ZF) and maximizing EH precoding (Max EH), while maintaining the same ID performance. The performance improvement of the PNC-SWIPT scheme mainly comes from canceling out the interference at the receivers from the aspect of data by PNC, without eliminating the interfering signals which are beneficial energy sources.

In this letter, we consider a multiple-input-multiple-output (MIMO) downlink system with simultaneous wireless information and power transfer (SWIPT), where the information sent to the desired receiver (DR) may be wiretapped by the malicious energy harvesting (EH) receivers (potential eavesdroppers). Assuming the channel state information (CSI) of the EH receivers is not perfectly known at the transmitter, we aim to maximize the worst-case secrecy rate by jointly designing the precoding matrix, AN covariance matrix and power splitting ratio, under the constraints of total transmit power and harvested energy at receivers. The formulated problem is non-convex and semi-infinite, which is hard to tackle. To solve it, we first deal with the non-convexity caused by CSI errors with the aid of the S-Procedure, and then employ the Taylor series approximation techniques to transfer the nonconvex problem into a convex optimization problem. Based on that, we propose an iterative algorithm with proved convergence to solve the original problem. Simulation results are finally provided to show the effectiveness of our proposed robust transmit design.

This work studies a simultaneous wireless information and power transfer (SWIPT)-enabled relaying network, where a power splitting protocol is applied at the relay before energy harvesting (EH). Due to low-latency requirements, the transmissions are operated with short blocklength codes. We aim at providing a reliability-oriented network design, while for the first time, the finite blocklength (FBL) impact and a realistic nonlinear EH process are jointly considered. In particular, we characterize the overall error probability of the considered network, and formulate the problem minimizing the overall error probability by optimally choosing the power splitting ratio. However, the formulated problem is non-convex due to the nonlinear EH process (which is also non-convex), thus making it challenging to be solved optimally. To tackle this difficulty, we propose a three-step approach to obtain an efficient solution. We first introduce two auxiliary variables, with the assistance of which we reformulate the problem. Then, we apply a convex approximation technique to tightly approximate the problem (at each local point/solution), based on which an efficient iterative algorithm (updating the local point) is finally proposed approaching a high-quality sub-optimal solution. Simulation results are provided to validate the convergence of the proposed algorithm and evaluate the performance in comparison to benchmarks with linear EH.

In 5G wireless networks, the system capacity and the number of users will be significantly increased. However, the energy consumed for the communication will also be increased, which results in low system energy efficiency. Simultaneous wireless information and power transfer (SWIPT) can enable the user to perform energy harvesting from the radio-frequency signals parallel with the information decoding, which can effectively improve the system energy efficiency. In this paper, we study the energy efficiency optimization problem for the orthogonal frequency-division multiplexing-based 5G wireless networks with SWIPT, in which the subcarrier and power allocation are jointly optimized to maximize the system energy efficiency for single user and multiple user cases. For those two cases, through mathematical transforming, we use the Dinkelbach iterative method and the Lagrange dual method to solve the non-convex energy efficiency optimization problem. Simulation results show that compared with other algorithms, our proposed algorithm can achieve higher energy efficiency.

Far-field wireless power transfer (WPT) and simultaneous wireless information and power transfer (SWIPT) have become increasingly important in radio frequency (RF) and communication communities recently. The problem of modulation design for SWIPT has however been scarcely addressed. In this paper, a modulation scheme based on asymmetric phase-shift keying (PSK) is considered, which improves the SWIPT rate-energy tradeoff region significantly. The nonlinear rectifier model, which accurately models the energy harvester, is adopted for evaluating the output direct current (DC) power at the receiver. The harvested DC power is maximized under an average power constraint at the transmitter and a constraint on the rate of information transmitted via a multi-carrier signal over a flat fading channel. As a consequence of the rectifier nonlinearity, this work highlights that asymmetric PSK modulation provides benefits over conventional symmetric PSK modulation in SWIPT and opens the door to systematic modulation design tailored for SWIPT.