Simultaneous Wireless Information And Power Transfer Technique Research Articles

Energy-Efficient Adaptive Bidirectional Transmission Strategy in Simultaneous Wireless Information and Power Transfer (SWIPT)-Enabled Cognitive Relay Network

Introducing collaborative relay and simultaneous wireless information and power transfer (SWIPT) techniques into a cognitive wireless network, named the SWIPT-enabled cognitive relay network (CRN), is considered a promising approach to deal with insufficiency and the low utilization of spectrum resources, as well as the node’s energy-constrained issues in wireless networks. In this paper, to improve the network spectrum efficiency (SE) and energy efficiency (EE) of the SWIPT-enabled CRN, we design an energy-efficient adaptive bidirectional transmission strategy. To be specific, we first select an energy-constrained best relay node with the consideration of signal-to-noise ratio and global channel gain to achieve a better bidirectional relay transmission (BRT). At the same time, we let the energy-constrained best relay node transmit a signal with the SWIPT technique, which can solve the node’s energy-constrained issue and improve the network EE. Then, with the selected energy-constrained best relay node, we design a total transmit power threshold (TTPT) determining algorithm to find the TTPT, which lets the total transmission rate of the BRT be equal to the bidirectional direct transmission (BDT). Based on this TTPT, we further design an adaptive bidirectional transmission strategy and let the network achieve adaptive transmission between the BRT and BDT to obtain a higher network SE. Furthermore, to further achieve the energy-efficient transmission of the adaptive bidirectional transmission strategy, we optimize the nodes’ power under the requirement of primary users’ interference threshold and obtain the analytical expressions of the optimal power. Simulation results show that the transmission rate, the outage probability, and the EE of the designed energy-efficient adaptive bidirectional transmission strategy in the SWIPT-enabled CRN are, respectively, 3.01, 0.07, and 3.10 times that of the non-collaborative transmission, which show the effectiveness of our designed transmission strategy.

Performance Analysis of AF Cooperative Relaying Networks with SWIPT

Cooperative communication networks have received more attention due to its ability to improve the signal quality of terminal devices by spatial diversity. Under recent advance in internet of things, In order to extend the service life of terminal devices powered by battery, simultaneous wireless information and power transfer (SWIPT) technique has been emphasize. The terminal devices can harvest energy and decode information from the same radio frequency (RF) signal using by SWIPT technique. In this paper, we combine both techniques to study the performance of both conventional cooperative relaying networks without SWIPT and cooperative relaying networks with SWIPT under an amplify-and-forward (AF) relaying network. To the best of our knowledge, no one simultaneously studies and compares the performance of both systems. Therefore, the outage probabilities of both systems are carried out, and numerical results are compared in this paper. The main results include: (1) Compared with conventional cooperative communication, the cooperative communication with SWIPT has better outage probability only when the distance between relay node and source node is less than one. It implies that, to outperform the conventional cooperative communication, the relay node should harvest enough energy for signal transmission. (2) With the diversity of direct path and relay path, the outage probability of cooperative communication with EH under an AF relaying network has been significantly reduced.

Energy-Efficient Optimal Power Allocation for SWIPT Based IoT-Enabled Smart Meter.

This paper presents an internet of things (IoTs) enabled smart meter with energy-efficient simultaneous wireless information and power transfer (SWIPT) for the wireless powered smart grid communication network. The SWIPT technique with energy harvesting (EH) is an attractive solution for prolonging the battery life of ultra-low power devices. The motivation for energy efficiency (EE) maximization is to increase the efficient use of energy and improve the battery life of the IoT devices embedded in smart meter. In the system model, the smart meter is equipped with an IoT device, which implements the SWIPT technique in power splitting (PS) mode. This paper aims at the EE maximization and considers the orthogonal frequency division multiplexing distributed antenna system (OFDM-DAS) for the smart meters in the downlink with IoT enabled PS-SWIPT system. The EE maximization is a nonlinear and non-convex optimization problem. We propose an optimal power allocation algorithm for the non-convex EE maximization problem by the Lagrange method and proportional fairness to optimal power allocation among smart meters. The proposed algorithm shows a clear advantage, where total power consumption is considered in the EE maximization with energy constraints. Furthermore, EE vs. spectral efficiency (SE) tradeoff is investigated. The results of our algorithm reveal that EE improves with EH requirements.

Analysis of SWIPT based dual-hop AF relay with SSK modulation over Nakagami-m fading channel

Space shift keying (SSK) modulation performance is analyzed with simultaneous wireless information and power transfer (SWIPT) based cooperative amplify-and-forward (AF) relaying system over the Nakagami-m fading channel. SWIPT technique can remove the need for power supply at the relays in cooperative communication. In contrast, SSK is a low complex index modulation technique that eliminates inter antenna synchronization, inter-channel interference and reduces the number of radiofrequency chains. Closed-form expression for average bit error probability (ABEP) is derived using a single AF relay with selection combining (SC) at the receiver, and an Upper bound ABEP expression is derived for multiple AF relays with the direct link (DL) from source to destination. The partial relay selection (PRS) technique has been proposed with energy harvesting (EH) to reduce the hardware complexity compared to the multiple relays. Numerical and computer simulation results are presented with the discussion. The result demonstrates that EH with SSK modulation can improve the system performance.

Massive MIMO Two-Way Relaying Systems With SWIPT in IoT Networks

In sixth-generation (6G) communication networks, ultrahigh-data rate and reliability are greatly vital for massive user connections and network sensors, such as Internet of Things (IoT) devices. Simultaneous wireless information and power transfer (SWIPT) has been evolved as an efficient strategy to enhance the reliability of wireless communication systems through prolonging the battery lifetime by harvesting energy from the received radio-frequency (RF) signals. Furthermore, cooperative relay sensors in IoT networks can extend the network coverage. In this article, we consider a massive multiple-input–multiple-output (MIMO) two-way relaying system, where the relay node splits the received RF signals into two power streams, one for information decoding (ID) and the other for energy harvesting (EH). Two classical and linear relay precodings, i.e., zero-forcing reception/zero-forcing transmission (ZFR/ZFT) and maximum-ratio combining/maximum-ratio transmission (MRC/MRT), are adopted to satisfy the requirements of high rate in this relay system. Different from prior work, the SWIPT technique and large-scale fading effects of MIMO channels are taken into account for deriving the asymptotic sum-rates of four prevalent power scaling cases when the number of relay antennas grows to infinity. Finally, the analytical results are evaluated by the presented simulation and numerical results.

Optimum time/power fraction of energy harvesting in TSR/PSR SWIPT-based cooperative communications with effective capacity maximization approach

In relay-based cooperative communications (RBCC) system, the energy problem of relays is a significant issue needs to be addressed. In the last few years, the simultaneous wireless information and power transfer (SWIPT) technique has been introduced to solve that matter. SWIPT technique aims to carry data and power over the wireless signals from the source node to the destination for the relays system. The SWIPT technique can be implemented utilizing two protocols. The first one has been introduced as time switch relay (TSR) protocol, which is time division between energy harvesting and data transmission. The second one has been introduced as power switch relay (PSR) protocol based on power division between two mentioned processes. The time or power fraction directly affects the quality of service (QoS) parameters in SWIPT-based cooperative communication systems. This paper aims to maximize effective capacity by implementing an optimization to find the optimum time or power fraction of energy harvesting in relays system utilizing TSR or PSR protocols. The optimization is applied using Lagrange multipliers while simulation results are used to verify the theoretical results obtained from the optimization process. In addition, outage probability of the source-relay-destination link is analyzed in both TSR and PSR protocols.

Joint Resource Optimization in Simultaneous Wireless Information and Power Transfer (SWIPT) Enabled Multi-Relay Internet of Things (IoT) System.

The internet of things (IoT) is becoming more indispensable in modern society as the further development and maturity of information technology progresses. However the exponential growth of IoT devices leads to severe energy consumption. As a technology with broad application prospects, simultaneous wireless information and power transfer (SWIPT) enables IoT devices to harvest energy from receiving radio frequency (RF) signals while ensuring information transmission. In this paper, we investigate the transmission rate optimization problem for a dual-hop multi-relay IoT system, where a decode-and-forward (DF) relay supports the SWIPT technique. We jointly optimize the resource including power and subcarrier allocation, to maximize the system transmission rate. The time-sharing strategy and Lagrange dual method are used to solve this optimization problem. Simulation results reveal that the proposed algorithm has a larger transmission rate than other benchmark algorithms when ensuring each relay has no additional energy supply. Specifically, the proposed algorithm improves the information transmission rate by 2.8%, 3.4% and 43% compared with other algorithms in the case of five relays when the source’s power is equal to 0.5 W, respectively.

RF-Based Energy Transfer Through Packets: Still a Dream? or a Dream Come True?

Limitations in battery capacity has held back the active development of novel applications for the Internet of Things (IoT) or have caused embedded systems researchers to design a number of “go-around” schemes, which sacrifice various system performance metrics for energy efficiency. However, with the concept of simultaneous wireless information and power transfer (SWIPT), many researchers accept it as a potential technology that can be the basis of designing various next-generation low-power embedded computing systems. This work presents an experimental validation on RF-based SWIPT techniques. Specifically, using the Powercast P2110 Powerharvester Receiver, we evaluate its potential of being applied to various low-power embedded applications. We analyze the performance of these commercially available energy harvesting RF receivers in packet-based networks to show that energy harvesting in such cases are only possible with packets of long lengths in practical environments. Furthermore, we experimentally show that despite carrying energy, external noise factors on the wireless channel can deteriorate the RF-based energy harvesting performance due to high voltage amplitude fluctuations. Based on such observations, we present a set of system-level suggestions for future SWIPT-based system development.

Analysis of time-switching and power-splitting protocols in wireless-powered cooperative communication system

SWIPT techniques combined with wireless cooperative communication provides a sustainable solution to extend the lifetime of the communication networks. It prolongs the battery life of wireless low-powered devices and enables additional efficiency in terms of power in wireless communications. This paper explores performance difference of two simultaneous wireless information and power transfer (SWIPT) protocols named Time-Switching (TS) and Power-Splitting (PS). Two identical decode-and-forward relaying communication networks with multiple relays are considered, where energy constrained relay nodes harvest energy from the received Radio Frequency (RF) and use harvested energy to assist information transmission between the source and the destination. All relay nodes in one network use TS protocol while the relay nodes in the other network use PS protocol. In particular, we evaluate throughput and outage probability of maximal ratio combiner (MRC) output at the destination node of both systems. In order to evaluate throughput, outage probability is derived for delay-limited transmission mode. The numerical results provide practical insight into the performance difference in various system parameters for both TS and PS protocols. Simulation results obtained depict that the TS protocol is superior to PS protocol in performance parameters, BER, Outage probability and throughput in low transmission rate. However, in higher transmission rates PS becomes superior to TS protocol, though overall performance reduce compare to lower transmission rate.

An efficient time-switching relaying protocol for multiuser cognitive radio relay networks with SWIPT

In this paper, we propose a new time-switching relaying (TSR) protocol for multi-destination dual-hop underlay cognitive radio relay networks with simultaneous wireless information and power transfer (SWIPT) technique. The proposed protocol maintains the same receiver complexity of the conventional TSR protocol with the ability for implementing both of them using the same hardware. We study the performance of the proposed TSR protocol and compare it with the conventional TSR and power-splitting relaying (PSR) protocols. Unified analytical expression is derived for the outage probability, in addition to studying the performance at high signal-to-noise ratio (SNR) values where unified approximate and simple expressions for the outage probability are provided. The results show that the proposed TSR protocol outperforms the conventional TSR protocol in terms of outage probability. Also, findings illustrate that applying the SWIPT technique in multi-destination underlay cognitive relay networks results in a unity diversity order. In contrast to conventional relaying networks, results show that the best location for the relay node in SWIPT relay networks is either near the source or the destinations, but not in between.

A Novel Time-Switching Relaying Protocol for Multi-user Relay Networks with SWIPT

In this paper, we propose a new time-switching relaying (TSR) protocol for dual-hop relay networks with simultaneous wireless information and power transfer (SWIPT) technique. The proposed protocol maintains the same receiver complexity of the conventional TSR protocol with the ability for implementing them using the same hardware. We study the performance of the proposed TSR protocol and compare it with the conventional TSR and power-splitting relaying protocols. Unified analytical expressions are derived for the outage probability, achievable throughput, and the ergodic channel capacity, in addition to studying the performance at high signal-to-noise ratio values where a unified approximate expression for the outage probability and expressions for the diversity order and coding gain are provided. The results show that the proposed TSR protocol outperforms the conventional TSR protocol in terms of outage probability and throughput. Also, findings illustrate that applying the SWIPT technique in multi-destination relay networks results in a unity diversity order. In contrast to conventional relaying networks, results show that the best location for the relay node in SWIPT relay networks is either near the source or the destinations but not in between.