Power Splitting Protocol Research Articles

On spectrally-efficient device-to-device communication with wireless information and power transfer

In this paper, the model of cooperative cognitive radio network is used to explore the two-way communications between a pair of unlicensed users by sharing the spectrum of any existing pair of licensed users. The licensed users of the spectrum are considered as primary users (PUs) and the unlicensed users of the spectrum are considered as secondary users (SUs). SUs are able to access the PUs spectrum by serving the relaying action between PU-to-PU communications. SUs are enabled by harvesting the energy from radio frequency signal following the principle of power splitting (PS) scheme of simultaneous wireless information and power transfer protocol. The closed form outage expressions of both PU and SU systems are derived. Analytical results validated through the simulations results. The results are also compared with existing work on two-way SU communications in presence of two-way PU communications. Based on the comparison, it is found that about $${\sim 191\%}$$ and $${\sim 656\%}$$ performance gains are possible to achieve by using proposed PS protocol in terms of spectrum efficiency and energy efficiency, respectively as compared to similar system using time switching protocol.

System Outage Probability of PS-SWIPT Enabled Two-Way AF Relaying With Hardware Impairments

In this paper, we investigate the system outage probability of a simultaneous wireless information, and power transfer (SWIPT) based two-way amplify-and-forward (AF) relay network, where transceiver hardware impairments (HIs) are considered. The energy-constrained relay node processes the received signals based on a power splitting protocol, and the two terminals employ a selection combining (SC) scheme to exploit the signals from the direct and relaying links. Assuming independent but non-identically distributed Nakagami-m fading channels, we derive the system outage probability in a closed-form, which enables us to identify two crucial ceiling effects on the system outage probability caused by HIs in the high data rate regions, i.e., relay cooperation ceiling (RCC) and overall system ceiling (OSC). Specifically, the RCC prevents the relaying link from participating in cooperative communications, while the OSC leaves the overall system in outage. Furthermore, we derive the achievable diversity gain of the considered network, which shows that the diversity gain equals either the shape parameter of the direct link or zero. Computer simulations are provided to validate the correctness of our analytical results, and study the effects of various system parameters on the system outage performance and the optimal power splitting ratio, as well as the energy efficiency.

NOMA With Battery-Assisted Energy Harvesting Full-Duplex Relay

This paper investigates the performance of a non-orthogonal multiple access (NOMA) network with simultaneous wireless information, and power transfer (SWIPT) based battery-assisted energy harvesting (EH) full-duplex relay (FDR). In each signalling interval, the base-station communicates directly to a near user (NU), and through an EH FDR to a far user (FU). Considering the power-splitting (PS) protocol with a non-linear EH model, we derive closed-form expressions for the NU, and FU outage probabilities. We also demonstrate how the battery energy, and PS parameter can be chosen to maximize the FU throughput while ensuring a desired NU throughput when there is imperfect interference cancellation at the NU. Computer simulation results validate the accuracy of the derived expressions, and demonstrate that augmenting the harvested energy with a small quantum of the relay's battery energy can considerably improve the FU performance.

Full-duplex wireless information and power transfer in two-way relaying networks with self-energy recycling

In this paper, we consider full-duplex (FD) two-way relaying networks, where wireless power transfers from hybrid power access-point, H to user and wireless information transmits from user to H via relay. We propose FD-based power splitting (PS) and time-switching (TS) protocols which enables the energy harvesting (EH) and information processing at relay. These protocols overcome the limitation of spectral efficiency and in band self-interference caused by half-duplex relaying and operation of FD respectively. The energy constraint nodes such as relay and user harvest energy from H by radio-frequency signal, where relay also harvests energy by self-energy recycling. The optimal PS ratio and the optimal TS ratio are investigated and expressed in closed-form. With Rayleigh fading channel, we derive the end-to-end ergodic capacity for PS and TS protocols. Numerical results show that our proposed FD-based EH schemes outperform the benchmark schemes significantly. In particular, the PS protocol is superior to TS protocol at high transmit power of H while at low transmit power of H, TS protocol is better than the PS protocol.

Multiuser Full-Duplex IoT Networks With Wireless-Powered Relaying: Performance Analysis and Energy Efficiency Optimization

This paper considers an Internet-of-Things (IoT) network where a multi-antenna access point (AP) and several single-antenna IoT devices (IoDs), operating under the full-duplex (FD) mode, communicate with each other bidirectionally through the help of a wireless-powered FD relay. In particular, the power splitting (PS) protocol is adopted at the amplify-and-forward (AF) relay to implement a simultaneous wireless information and power transfer (SWIPT) receiver. For such a multiuser FD-IoT network assisted by a wireless-powered two-way relay, we derive exact overall outage probability (OOP) expressions and tight closed-form expressions for the ergodic sum rate (ESR) under generalized Nakagami-m fading channels. Furthermore, aiming to maximize the energy efficiency (EE), we obtain optimal power allocation (OPA) under the total power and rate threshold constraints. Finally, extensive numerical and simulation results are presented to corroborate our analytical findings.

Secrecy capacity analysis of untrusted relaying energy-harvesting systems with hardware impairments

In this paper, we study the impact of hardware impairments, which can act as one of the factors that cause degradation in the performance of communication systems, on the secrecy capacity of an untrusted relaying wireless energy-harvesting (WEH) system. In the system, the energy-constrained relay is an untrusted node which can overhear the source’s confidential signal while assisting the source-destination communication. The relay operates in the amplify-and-forward (AF) mode and uses the power-splitting (PS) protocol for harvesting energy. The destination sends an artificial noise (AN) signal during the source-relay communication. The AN signal acts as an additional energy source and an interference source at the relay. In our study, we derive an approximation of the average secrecy capacity (ASC) for the high-power-regime approximation in order to evaluate the secrecy performance of the proposed system, which is also the upper bound for the ASC. The analytical results are confirmed via Monte Carlo simulations. The numerical results provide valuable insights into the effect of the various system parameters, such as the power-splitting ratio, the relay’s location, the trade-off between the source’s power and the destination’s power, and the level of hardware impairments, on the secrecy performance.

Wireless information and power transfer using single and multiple path relays

SummaryA relay‐based wireless communication model can relay information along with the power bidirectionally using the amplify‐and‐forward scheme. This paper studies such model extensively. Three information and power relaying protocols, that is, time‐based switching relaying, power‐based splitting relaying, and hybrid time switching‐based and power splitting‐based relaying (HTPSR) are used to carry forward bidirectional information and power transfer. First, a solo relay model is studied, for which, we derived a throughput expression for end‐to‐end information transfer, and this is done for all the three relaying protocols. The paper indicates that the system throughput depends upon the time switching and the power splitting ratio.Further, to make the system more reliable and robust, multiple relays are used in the path. Various relay selection schemes are used for path selection in each transmission, thereby yielding different throughput performances. The results show that an optimal throughput is obtained for a given relay location at an optimal set of values of splitting and switching ratio. Moreover, the HTPSR outperforms both the power splitting and time switching protocol in system throughput performance for a single as well as a multiple‐relay model. Whereas, in relay selection schemes, the best SNR selection scheme outperforms in all the schemes used. The simulated results confirm that the system throughput is an active function of relay placement.

Secrecy analysis of a Cognitive Radio Network with an adaptive path selection based transmission scheme and JTAPS relay

This paper investigates the secrecy outage performance of a Cognitive Radio Network (CRN), where we propose an adaptive path selection based transmission scheme to transmit the information from the source to destination. The transmit power of the secondary user (SU) and relay is limited due to underlay CRN to maintain the maximum acceptable interference at the primary user (PU) receiver. The secondary network uses an intermediate relay between source and destination to harvest energy from the transmission of the radio frequency (RF) signal of SU following a joint time allocation and power splitting (JTAPS) protocol. Here we use the hybridization of two known energy harvesting (EH) protocols by combining the time allocation (TA) and power splitting (PS) factor to make more efficient use of the EH method in evaluating physical layer secrecy. We develop analytical expressions for secrecy outage under JTAPS and the effect of time allocation (TA) and power splitting (PS) factor on the secrecy outage probability (SOP) is investigated. Our proposed JTAPS scheme yields 12% reduction in SOP with respect to TSR scheme at an energy harvesting factor α=0.6.

Adaptive time-switching and power-Splitting protocols for energy harvesting sensor networks with multiple relays

In the conventional energy-harvesting (EH) relaying protocols based on time switching (TS) and power splitting (PS), the system performance depends on the parameters such as TS and PS ratios. In order to achieve the optimum performance, these parameters need to be optimized. In the distributed cooperative networks, where relay operates independently, the optimization of PS and TS ratios becomes cumbersome and challenging. In this work, we overcome this issue by proposing two relaying protocols referred to as adaptive time-switching (ATS) and adaptive time-switching adaptive power-splitting (ATS-APS) protocols. In the proposed protocols, the relay can dynamically optimize their respective TS and PS ratios according to their local channel condition among relays, i.e., without any external help from the source or destination, which makes the proposed protocols promising for the distributed relaying network. Through rigorous numerical analysis, we show that the proposed protocols can outperform the conventional approach. We also derive mathematical expressions for the outage probability and the effective transmission rate in the framework of decode-and-forward (DF) relaying with partial relay selection (PRS) scheme based on various diversity combining techniques including maximum ratio combining (MRC), selection combining (SC), and selective relaying (SR). Through numerical analysis, we demonstrate that the proposed adaptive SR technique, where the source receives assistance from the relay only if the source-to-destination link is in deep fading, can achieve better performance than the other techniques compared here in terms of the achievable effective transmission rate. All the theoretical results developed are confirmed by numerical simulations.

Joint Optimization of Energy-Harvesting-Powered Two-Way Relaying D2D Communication for IoT: A Rate–Energy Efficiency Tradeoff

Device-to-device (D2D) communication is a key enabling technology to facilely realizing the Internet of Things (IoT) due to its spectral and energy efficiencies features. Exploiting the physical-layer network coding (PNC) and energy harvesting (EH) technology, two-way relaying (TWR) D2D communication can achieve significant performance for IoT in terms of data rate and energy efficiency (EE). In this article, we investigate the EH-aided TWR D2D communication sharing the uplink (UL) spectrum of the traditional cellular networks. We assume that the D2D transmitters, receivers, and participating relays can collect renewable energy (RE) from natural resources. Also, the relays are considered to be powered by radio-frequency (RF) signals utilizing the power splitting (PS) protocol. Subject to the Quality of Service (QoS), power, subchannel assignment, EH, and maximum practical power constraints, two nonconvex mixed-integer nonlinear programming (MINLP) problems are formulated. The two problems provide a tradeoff on either maximizing the TWR D2D link (TDL) rate or its EE depending on the IoT application needs. Based on the particle swarm optimization (PSO) algorithm, we propose the rate and EE tradeoff EH-based algorithm (REET-EH) to deal with these problems. The proposed algorithm can optimally perform the resource allocation (RA), PS factors determination, power allocation (PA), and relay selection processes. The numerical results investigate the performance of the REET-EH algorithm and show its consistency over several parameters. Also, the results illustrate that our proposed algorithm improves the system performance compared with other state-of-the-art algorithms with regard to the D2D link rate and EE.

Capitalizing Backscatter-Aided Hybrid Relay Communications With Wireless Energy Harvesting

In this work, we employ multiple energy harvesting relays to assist information transmission from a multi-antenna hybrid access point (HAP) to a receiver. All the relays are wirelessly powered by the HAP in the power-splitting (PS) protocol. We introduce the novel concept of hybrid relay communications, which allows each relay to switch between two radio modes, i.e., the active RF communications and the passive backscatter communications, according to its channel and energy conditions. We envision that the complement transmissions in two radio modes can be exploited to improve the overall relay performance. As such, we aim to jointly optimize the HAP's beamforming, individual relays' radio mode, the PS ratio, and the relays' collaborative beamforming to enhance the throughput performance at the receiver. The resulting formulation becomes a combinatorial and non-convex problem. Thus, we firstly propose a convex approximation to the original problem, which serves as a lower bound of the relay performance. Then, we design an iterative algorithm that decomposes the binary relay mode optimization from the other operating parameters. In the inner loop of the algorithm, we exploit the structural properties to optimize the relay performance with the fixed relay mode in the alternating optimization framework. In the outer loop, different performance metrics are derived to guide the search for a set of passive relays to further improve the relay performance. Simulation results verify that the hybrid relaying communications can achieve 20% performance improvement compared to the conventional relay communications with all active relays.

Outage probability and ergodic capacity analysis in power splitting based full-duplex relaying networks of double rayleigh fading channel for vehicular communications

<p><span>In this </span><span lang="EN-GB">research</span><span>, we present and investigate the system performance analysis in terms of the outage probability (OP) and ergodic capacity (EC) of the Full-duplex (FD) relaying networks via double Rayleigh fading channel. In this system model, we propose the power splitting (PS) protocol for the vehicular communications network. Firstly, we analyze and derive the integral form of the system OP and EC. Then, the correctness of the OP and EC expressions are verified by the Monte Carlo simulation. Finally, we can see that the analytical and the simulation results are matched with each other in the connection with the main system parameter.</span></p>

Secure transmission for energy harvesting relay networks with the destination self-protection mechanism

In this paper, we investigate the physical layer security (PLS) of an energy harvesting (EH) cooperative network with the destination self-protection mechanism. More specifically, we consider a cooperative transmission scenario in which a source communicates with a destination through a wireless-powered relay using power splitting (PS) protocol in the presence of an eavesdropper. To degrade the wiretap channel, the destination is operated in full-duplex (FD) to achieve simultaneous information reception and jamming transmission. Taking into account the residual self-interference (SI) at the destination, the non-convex secrecy rate maximization problem is formulated to jointly optimize the PS factor and power allocation of source and destination. Due to the non-convexity of the joint optimization, a low complexity iterative algorithm based on the alternative search method and difference of convex functions (DC) programming is proposed. The original problem is first decomposed into two sub-problems with the fixed transmission power or PS factor. Since the decomposed two sub-problems are still non-convex, we utilize the DC programming to obtain the local solutions of the two sub-problems. Then the global solutions can be obtained by the alternative search method. Simulation results present that the proposed scheme has fast convergence. Comparing with other conventional schemes, the proposed scheme has the best security performance.

Simultaneous wireless information and power transfer for massive MIMO networks

In this study, the authors propose a simultaneous wireless information and power transfer scheme based on the power-splitting (PS) protocol for a massive multiple-input multiple-output (MIMO) network. On the downlink, the base station transmits the information and energy simultaneously to each terminal and each terminal divides the received signals by its PS device between information decoder and energy harvester (EH). On the uplink, a portion of the energy harvested by EH is drawn for uplink pilot transmission in the coming frame and then the other is used for uplink data transmission in the current frame. Based on this scheme, the closed-form lower bound expressions are obtained for the achievable downlink rate and uplink rate of each terminal and then are utilised to formulate an optimisation problem that is to maximise achievable sum rate of the whole network while ensuring the minimum required uplink and downlink rates of each terminal. However, as the original optimisation problem is non-convex and non-linear and very hard to solve directly, an algorithm is proposed by utilising successive approximation method based on geometric program. Numerical results verify the correctness and feasibility of the proposed algorithm.

Optimization of Rate Fairness in Multi-Pair Wireless-Powered Relaying Systems

This letter considers a multi-pair decode-and-forward relay network where a power-splitting (PS) protocol is adopted at the energy-constrained relay to provide simultaneous wireless information and energy harvesting (EH). To achieve higher efficiency of EH, we propose a new PS-based EH architecture at the relay by incorporating an alternating current (AC) computing logic, which is employed to directly use the wirelessly harvested AC energy for computational blocks. Under a nonlinear EH circuit, our goal is to maximize the fairness of end-to-end rate among user pairs subject to power constraints, resulting in a nonconvex problem. We propose an iterative algorithm to achieve a suboptimal and efficient solution to this challenging problem by leveraging the inner approximation framework. Numerical results demonstrate that the proposed algorithm outperforms the traditional direct current computing and other baseline schemes.

Joint Beamforming and Power Splitting Design for Physical Layer Security in Cognitive SWIPT Decode-and-Forward Relay Networks

In an underlay cognitive simultaneous wireless information and power transfer (SWIPT) network, communication from secondary user (SU) to secondary destination (SD) is accomplished with decode-and-forward (DF) relays. Multiple energy-constrained relays are assumed to harvest energy from SU via power splitting (PS) protocol and complete SU secure information transmission with beamforming. Hence, physical layer security (PLS) is investigated in cognitive SWIPT network. In order to interfere with eavesdropper and improve relay’s energy efficiency, a destination-assisted jamming scheme is proposed. Namely, SD transmits artificial noise (AN) to interfere with eavesdropping, while jamming signal can also provide harvested energy to relays. Beamforming vector and power splitting ratio are jointly optimized with the objective of SU secrecy capacity maximization. We solve this non-convex optimization problem via a general two-stage procedure. Firstly, we obtain the optimal beamforming vector through semi-definite relaxation (SDR) method with a fixed power splitting ratio. Secondly, the best power splitting ratio can be obtained by one-dimensional search. We provide simulation results to verify the proposed solution. Simulation results show that the scheme achieves the maximum SD secrecy rate with appropriate selection of power splitting ratio, and the proposed scheme guarantees security in cognitive SWIPT networks.

Robust Secure Beamforming for SWIPT-Aided Relay Systems With Full-Duplex Receiver and Imperfect CSI

This paper investigates an energy-constrained relay-assisted secure communication system in the presence of a legitimate source-destination pair and a passive eavesdropper with imperfect channel state information (CSI). The energy-constrained relay exploits a power splitting (PS) protocol to simultaneously harvest energy and decode information from the received signal from the source, and then forwards the confidential signal to the full-duplex (FD) destination while it simultaneously transmits artificial noise (AN) to confuse the passive eavesdropper. This robust beamforming design is developed by maximizing the secrecy rate under the constraints of energy harvesting (EH) requirement at the relay and AN transmit power at the destination. Specifically, we formulate the joint relay beamforming and PS ratio as well as the AN power optimization as a non-convex quadratically-constrained problem. In order to circumvent this non-convexity issue, we decompose the original problem into three subproblems which can be determined by the proposed semidefinite relaxation (SDR) and successive convex optimization methods. Furthermore, we derive closed-form expressions for the optimal solutions of each subproblem. Finally, the original non-convex problem can be solved through a convergence guaranteed iterative algorithm. Simulation results are provided to demonstrate the effectiveness and superior performance of the proposed robust design compared with the benchmark schemes.

Power Beacon-Assisted Energy Harvesting Wireless Physical Layer Cooperative Relaying Networks: Performance Analysis

In this research, we proposed and investigated the physical layer system called the full-duplex (FD) power beacon-assisted (PB) energy harvesting (EH) relaying cooperative network. The system model has one PB node, one destination (D), one source (S), and one relay (R) node. We investigated the system performance in terms of outage probability (OP) and system throughput (ST) with the power-splitting (PS) protocol in both delay-tolerant (DTT) and delay-limited (DLT) transmission modes. Moreover, the optimal power splitting (PS) factor in both DDT and DLT modes is proposed and derived. Finally, the mathematical closed-form expressions of the OP and ST are derived by using the Monte Carlo simulation with the help of MATLAB software. From the results, it can be observed that the analytical values and simulation values are the same in the effect of the main system parameters.

Security and Reliability Analysis of a Two-Way Half-Duplex Wireless Relaying Network Using Partial Relay Selection and Hybrid TPSR Energy Harvesting at Relay Nodes

In recent years, physical layer security has been considered as an effective method to enhance the information security beside the cryptographic techniques that are used in upper layers. In this paper, we provide the security analysis for a two-way relay network, where the two sources can only communicate through the intermediate relay nodes. In particular, we consider the scenario that there is an eavesdropper in the vicinity of one source node. Both reliability and security aspects are taken into consideration in our work. To enhance the reliability of communication, the intermediate relays are supplied with the energy harvested from the sources' radio frequency (RF) signals using hybrid time-switching and power splitting (TPSR) protocol. Also, we apply the relay selection technique to select the best relay for the information exchange between two sources. Regarding security, the secrecy of information is improved with the help of friendly jammers nearby the eavesdropper. We provide the in-dept reliability and security analysis in terms of the closed-form expressions of the outage probability (OP) at the source nodes, the intercept probability (IP) at the eavesdropper, the secrecy outage probability (SOP), and the average secrecy capacity (ASC) of the system. Finally, the Monte Carlo simulations are also conducted to verify the correctness of our analysis and the effectiveness of the proposed scheme. Numerical results confirms that with the appropriate and feasible choices of involved parameters, both outage OP and IP can be kept at small values to guarantee the reliable and secure communication of the system.

User selection protocols in FD PSP EH cooperative network over rayleigh fading channel: outage and intercept probability

In this paper, we investigate the system performance in term of outage probability (OP) and intercept probability (IP) user selection protocols in full-duplex (FD) power splitting protocol (PSP) energy harvesting (EH) cooperative network over the Rayleigh fading channel. In this network, security and privacy issues are significant due to the possible eavesdropping by surrounding users. In this case, the security performance and reliable performance are represented by outage probability (OP) and intercept probability (IP), respectively. The power-splitting energy harvesting protocol is applied in our analysis. We rigorously derive the closed-form expressions of both OP and IP of the system and study the effect of various parameters. Finally, the Monte Carlo simulation results are also performed to confirm the correctness of all theoretical analysis derived.