Simultaneous Wireless Information And Power Transfer Relay Research Articles

Best sum-throughput evaluation of cooperative downlink transmission nonorthogonal multiple access system

In cooperative simultaneous wireless information and power transfer (SWIPT) nonorthogonal multiple access (NOMA) downlink situations, the current research investigates the total throughput of users in center and edge of cell. We focus on creating ways to solve these problems because the fair transmission rate of users located in cell edge and outage performance are significant hurdles at NOMA schemes. To enhance the functionality of cell-edge users, we examine a two-user NOMA scheme whereby the cell-center user functions as a SWIPT relay using power splitting (PS) with a multiple-input single-output. We calculated the probability of an outage for both center and edge cell users, using closed-form approximation formulas and evaluate the system efficacy. The usability of cell edge users is maximized by downlink transmission NOMA (CDT-NOMA) employing a SWIPT relay that employs PS. The suggested approach calculates the ideal value of the PS coefficient to optimize the sum throughput. Compared to the noncooperative and single-input single-output NOMA systems, the best SWIPT-NOMA system provides the cell-edge user with a significant throughput gain. Applying SWIPT-based relaying transmission has no impact on the framework’s overall throughput.

Throughput Analysis of HARQ Scheme Based on Full-Duplex Two-Way AF SWIPT Relay

The simultaneous wireless information and power transfer (SWIPT) relay system is one of the emerging technologies. Xiaomi Corporation and Motorola Inc. recently launched indoor wireless power transfer equipment is one of the most promising applications. To tap the potential of the system, hybrid automatic repeat request (HARQ) is introduced into the SWIPT relay system. Firstly, the time slot structure of HARQ scheme based on full duplex two-way amplify and forward (AF) SWIPT relay is given, and its retransmission status is analyzed. Secondly, the equivalent signal-to-noise ratio and outage probability of various states are calculated by approximate simplification. Thirdly, the energy harvesting power in each state is calculated. Finally, the energy harvested-throughput sum function is constructed to characterize the performance of energy harvesting and data transmission. Simulation results show that the proposed HARQ scheme has better energy harvested-throughput sum function than the traditional HARQ scheme. When P2 = 22 dB, the maximum sum function is 54.86% (the proposed HARQ scheme) and 52.307% (the traditional HARQ scheme), respectively.

Joint Optimization on Power Allocation and Splitting for WSNs With SWIPT-Based Relay

How to prolong network lifetime has become an important issue in the design of large scale wireless sensor networks (WSNs). In this paper, a novel power saving scheme for conventional WSNs via simultaneous wireless information and power transfer (SWIPT) based relays is proposed. Unlike conventional relays based communications need extra energy supply for data forwarding, the relay applied in this paper works in an energy-free manner with the support of SWIPT. The power saving model with both power splitting (PS) and time switching (TS) based SWIPT are proposed. Then, we formulate the joint power allocation and splitting problems of SWIPT relay assisted WSNs as non-convex constrained optimization problems. Since the formulated problems are non-convex, semi-positive definite programming (SDP) algorithms are proposed to find the joint optimization on power allocation and splitting with low complexity. The simulation results show that the PS model has more advantages than the traditional direct communication model in long distance transmission. Under the same information receiving strategy, the PS model outperforms the TS model.

Secure beamforming design of SWIPT relay network with multiple users and eavesdroppers

This paper studies the secure beamforming design for simultaneous wireless information and power transfer (SWIPT) in a amplify-and-forward (AF) relay networks with multiple users and eavesdroppers. Each user node adopts the power splitting (PS) scheme to decode information and harvest energy simultaneously. Our objective is to minimize the total relay transmit power under the constraints of secure transmission rate and energy harvesting requirements by jointly optimizing the beamforming matrix, artificial noise covariance matrix and PS ratios. For this non-convex problem, we propose a two-stage optimization approach to convert the original problem into two sub-problems. The first subproblem uses semidefinite relaxation (SDR) technique to transform the original problem into a convex problem, and then finds the optimal solution of the second subproblem through k-dimensional exhaustive search algorithm. Furthermore, we also propose a low complexity suboptimal solution scheme based on particle swarm optimization (PSO) algorithm. Simulation results show that the proposed scheme saves transmitting power and achieves better performance than other schemes.

Simultaneous wireless information and power transfer in energy‐augmented amplify and forward cooperative cognitive networks

Simultaneous wireless information and power transfer (SWIPT) and energy harvesting (EH) have been considered as the promising technique to enhance the lifetime of energy constrained relay nodes of the amplify and forward (AF)-based cognitive wireless network. The amalgamation of cognitive and cooperative communication has emerged as a powerful method for improving spectrum utilisation. In this study, an energy-augmented AF (EAF) protocol has been proposed to enhance the throughput and minimise the outage probability of cooperative cognitive relay networks. A power splitting based SWIPT relay secondary user in the EH module harvests the energy and uses the harvested energy to forward the amplified version of the signal to the destination. System model and analytical equations have been developed for the proposed EAF protocol. Simulation results demonstrate that the proposed EAF protocol outperforms the conventional schemes in terms of capacity, outage probability and throughput.

Sum Rate Maximization for Multi-Carrier SWIPT Relay System With Non-Ideal Power Amplifier and Circuit Power Consumption

In this paper, we investigate the resource optimization algorithm design in a multicarrier relay system with simultaneous wireless information and power transfer (SWIPT). The relay is capable of harvesting energy from the source's signals by using the power splitting method. The non-ideal energy consumption including both the non-ideal power amplifier and non-ideal circuit power consumption is considered. First, we study the transmission rate maximization problem (TRMP) in an asymmetric decode-and-forward (DF) relay transmission, where the transmission power at the source, the transmission power at the relay, the power splitting ratio, and the transmission time are jointly optimized. The formulated problem is a non-convex problem, and it is generally quite difficult to solve it. By exploiting the structure of the problem, we propose two methods (logarithmic operation on constraints and logarithmic change of variables) to transform it into the corresponding difference of convex (DC) optimization problems. Then, we extend the TRMP to an amplify-and-forward (AF) relay transmission. Furthermore, we propose an effective algorithm to solve the DC optimization problem and prove that the algorithm can converge to a stationary point. Finally, extensive simulations are conducted to verify the performance of the proposed algorithm. The simulation results show that the asymmetric DF relay transmission achieves the highest sum rate and the AF relay transmission achieves a much lower sum rate than both the asymmetric and symmetric DF relay transmissions under different conditions.

Performance Analysis of SWIPT Relay Networks With Noncoherent Modulation

In this paper, we investigate the performance of noncoherent modulation in simultaneous wireless information and power transfer (SWIPT) relay networks. Noncoherent modulation schemes eliminate the need for instantaneous channel state information estimation, and therefore, minimize the overall energy consumption of the network. In particular, we adopt a moments-based approach to develop a comprehensive novel analytical framework for the analysis of the outage probability, achievable throughput, and average symbol error rate (ASER) of a dual-hop SWIPT relay system considering the time switching (TS) and power splitting (PS) receiver architectures. In addition, through the derivation of new asymptotic analytical results for the outage probability and ASER, we analytically demonstrate that the diversity order of the considered system is non-integer less than 1 in the high signal-to-noise (SNR) regime. Our results show that there is a unique value for the PS ratio that minimizes the outage probability of the system, while this is not the case for the TS protocol. We also demonstrate that, in terms of system throughput, the TS relaying scheme is superior to the PS relaying scheme at lower SNR values. An extensive Monte Carlo simulation study is presented to corroborate the proposed analytical model.

Performance Analysis of MIMO SWIPT Relay Network with Imperfect CSI

In this paper, we consider a dual-hop multiple-input multiple-output (MIMO) simultaneous wireless information and power transfer (SWIPT) relay network, where the source node (SN) uses a transmission antenna selection (TAS) scheme to concurrently send information and energy to the single-antenna relay node (RN). This helps to utilize the harvested energy to forward the received signal. In addition, the destination node (DN) employs the maximum ratio combining (MRC) scheme to process this forwarded signal. The performance of this MIMO SWIPT relay system is investigated in imperfect channel state information (CSI) condition. Specifically, we derive the exact and approximate closed-form expressions for the outage probability, the average capacity, and the symbol error probability (SEP). This is the first time the exact and approximate formulas for the SEP of the energy harvesting networks are investigated. The Monte Carlo simulation results are provided to demonstrate the relevance of the developed analytical results, showing that the system’s performance is significantly impacted by the CSI imperfection, the number of antennas, and the energy harvesting duration.

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.

Energy-Assisted Decode-and-Forward for Energy Harvesting Cooperative Cognitive Networks

In this paper, we consider a simultaneous wireless information and power transfer (SWIPT)-enabled cooperative cognitive network that addresses energy scarcity and spectral scarcity, two important issues in 5G wireless communications. In the considered network, the self-sustainable, SWIPT-enabled relay assists primary user’s transmission, while the relay itself is also a secondary user with its own information superimposed on the regenerated primary information for transmission. The SWIPT relay employs the proposed energy-assisted decode-and-forward (EDF) protocol, which enhances the conventional decode-and-forward (DF) protocol with energy-dimension-augmented information decoding. We conduct a comparative analysis of the proposed EDF and the conventional DF and amplify-and-forward (AF) protocols in this SWIPT cooperative cognitive framework in terms of capacity, outage probability, and throughput for both primary and secondary networks. Simulation corroborates the analysis and demonstrates performance advantages of EDF over DF/AF from various perspectives.

Transmission strategies for wireless powered MIMO relay systems

This paper studies a multiple input multiple output (MIMO) simultaneous wireless information and power transfer (SWIPT) relay system, in which the source node (SN) send information and energy simultaneously to the relay node (RN), and the RN forward the received signal to the destination node (DN) powered by harvested energy. In particular, we consider two SWIPT receiver designs, namely power splitting (PS) and antenna switching (AS) in the relay system. For each design, iterative algorithms based on convex optimization technique are proposed to maximize the system rate. Furthermore, in order to strike a balance between computational complexity and system performance, based on the AS scheme, we propose a low complexity optimization method for PS scheme where a suboptimal PS ratio is given. Numerical results are provided to evaluate the performance of the proposed algorithm for MIMO SWIPT relay systems. It is shown that the performance of the proposed suboptimal method approaches that of the optimal PS scheme.