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Luo, Yi, Chenyang Wu, Yi Leng, Nüshan Huang, Lingxi Mao i Junhao Tang. "Throughput Optimization for NOMA Cognitive Relay Network with RF Energy Harvesting Based on Improved Bat Algorithm". Mathematics 10, nr 22 (19.11.2022): 4357. http://dx.doi.org/10.3390/math10224357.
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Due to the shortcomings of the standard bat algorithm (BA) for multi-parameter optimization, an improved bat algorithm is proposed. The benchmark function test shows that the proposed algorithm has better realization of high-dimensional function optimization by introducing multiple flight modes, adopting adaptive strategy based on group trend, and employing loudness mutation flight selection strategy based on Brownian motion. Aiming at the characteristics of complex networks structure and multiple design variables of energy harvesting non-orthogonal multiple access cognitive relay networks (EH-NOMA-CRNs), we utilize the proposed hybrid strategy improved bat algorithm (HSIBA) to optimize the performance of EH-NOMA-CRNs. At first, we construct a novel two-hop underlay power beacon assisted EH-NOMA-CRN, and derive the closed-form expressions of secondary network’s outage probability and throughput. Then, the secondary network performance optimization is formulated as the throughput maximation problem with regard to EH ratio and power allocation factors. Subsequently, the HSIBA is employed to optimize the above parameters. Numerical results show that the proposed HSIBA can achieve optimization to the constructed EH-NOMA-CRN with faster convergence speed and higher stability.
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Sarkar, Nurul I., Dev Pal Singh i Monjur Ahmed. "A Survey on Energy Harvesting Wireless Networks: Channel Capacity, Scheduling, and Transmission Power Optimization". Electronics 10, nr 19 (24.09.2021): 2342. http://dx.doi.org/10.3390/electronics10192342.
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This paper presents a survey on energy harvesting (EH) wireless communication networks focusing on channel capacity, transmission schemes, and power optimization. While many network researchers focus on energy management policies addressing the intermittency and randomness of the EH processes, but the channel capacity, and transmission power optimization have not been fully explored yet. In this paper, we provide a review and analysis of channel capacity, offline and online transmission schemes, and power optimization from an information theory perspective. By reviewing and analyzing wireless networking literature, we found that EH is a technologically feasible and economically viable paradigm for cost-effectiveness in the design and deployment of next-generation wireless networks. Finally, we identify open research problems and future research directions in the emerging field of EH wireless networks. We expect this study to stimulate more research endeavors to build energy-efficient scalable next-generation wireless network systems.
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Zhu, Long, Liang Xue, Xuan Gong i Chunjie Wang. "Resource Allocation for a Secure SWIPT Network Based on a Quantitative Energy Harvesting Mechanism". Sensors 23, nr 11 (27.05.2023): 5117. http://dx.doi.org/10.3390/s23115117.
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Simultaneous wireless information and power transfer (SWIPT) technology can effectively extend the lifecycle of energy-constrained networks. In order to improve the energy harvesting (EH) efficiency and network performance in secure SWIPT networks, this paper studies the resource allocation problem based on the quantitative EH mechanism in the secure SWIPT network. Based on a quantitative EH mechanism and nonlinear EH model, a quantified power-splitting (QPS) receiver architecture is designed. This architecture is applied in the multiuser multi-input single-output secure SWIPT network. With the goal of maximizing the network throughput, the optimization problem model is established under the conditions of meeting the legal user’s signal-to-interference-plus-noise ratio (SINR), EH requirements, the total transmit power of the base station, and the security SINR threshold constraints. Due to the coupling of variables, the problem is a nonconvex optimization problem. To deal with the nonconvex optimization problem, a hierarchical optimization method is adopted. Firstly, an optimization algorithm based on the optimal received power of EH circuit is proposed, and a power mapping table is constructed through the optimization algorithm, from which the optimal power ratio to meet the user’s EH requirements is obtained; then, the nonconvex problem is transformed into a convex problem by using variable substitution, semidefinite relaxation, dichotomous optimization, etc. The simulation results show that compared with the power splitting receiver architecture, the input power threshold range of the QPS receiver architecture is larger, which can avoid the EH circuit falling into the saturated working area and maintain high network throughput.
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Zhang, Jinxi, Gang Chuai i Weidong Gao. "Energy-Efficient Optimization for Energy-Harvesting-Enabled mmWave-UAV Heterogeneous Networks". Entropy 24, nr 2 (20.02.2022): 300. http://dx.doi.org/10.3390/e24020300.
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Energy Harvesting (EH) is a promising paradigm for 5G heterogeneous communication. EH-enabled Device-to-Device (D2D) communication can assist devices in overcoming the disadvantage of limited battery capacity and improving the Energy Efficiency (EE) by performing EH from ambient wireless signals. Although numerous research works have been conducted on EH-based D2D communication scenarios, the feature of EH-based D2D communication underlying Air-to-Ground (A2G) millimeter-Wave (mmWave) networks has not been fully studied. In this paper, we considered a scenario where multiple Unmanned Aerial Vehicles (UAVs) are deployed to provide energy for D2D Users (DUs) and data transmission for Cellular Users (CUs). We aimed to improve the network EE of EH-enabled D2D communications while reducing the time complexity of beam alignment for mmWave-enabled D2D Users (DUs). We considered a scenario where multiple EH-enabled DUs and CUs coexist, sharing the full mmWave frequency band and adopting high-directive beams for transmitting. To improve the network EE, we propose a joint beamwidth selection, power control, and EH time ratio optimization algorithm for DUs based on alternating optimization. We iteratively optimized one of the three variables, fixing the other two. During each iteration, we first used a game-theoretic approach to adjust the beamwidths of DUs to achieve the sub-optimal EE. Then, the problem with regard to power optimization was solved by the Dinkelbach method and Successive Convex Approximation (SCA). Finally, we performed the optimization of the EH time ratio using linear fractional programming to further increase the EE. By performing extensive simulation experiments, we validated the convergence and effectiveness of our algorithm. The results showed that our proposed algorithm outperformed the fixed beamwidth and fixed power strategy and could closely approach the performance of exhaustive search, particle swarm optimization, and the genetic algorithm, but with a much reduced time complexity.
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Galmés, Sebastià, i Soledad Escolar. "Analytical Model for the Duty Cycle in Solar-Based EH-WSN for Environmental Monitoring". Sensors 18, nr 8 (1.08.2018): 2499. http://dx.doi.org/10.3390/s18082499.
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A technology drift is currently taking place from traditional battery-powered sensor networks, which exhibit limited lifetime, to the new Energy-Harvesting Wireless Sensor Networks (EH-WSN), which open the way towards self-sustained operation. However, this emergent modality also brings up new challenges, especially due to the time-varying nature and unpredictability of ambient energy sources. Most proposals for implementing EH-WSN rely on heuristic approaches to redesign the duty-cycling mechanism at the MAC layer, with the ultimate goal of optimizing network performance while preserving self-sustained and continuous operation. In contrast to the common system-wide reduced duty cycle of battery-powered sensor networks, the duty cycle in EH-WSN is much larger and adapted to the energy harvesting rate and traffic load of each node in the network. In this paper, we focus on solar-based EH-WSN devoted to environmental monitoring. In contrast to current works, we follow an analytical approach, which results into closed-form expressions for the duty cycle and initial energy storage that guarantee self-sustained operation to any node in a solar-based EH-WSN. To center the analysis, we consider TinyOS sensor nodes, though we postulate that the essential components of the obtained formulation will contribute to further develop duty cycle adaptation schemes for TinyOS and other software platforms.
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Andrawes, Admoon, Rosdiadee Nordin i Mahamod Ismail. "Wireless Energy Harvesting with Cooperative Relaying under the Best Relay Selection Scheme". Energies 12, nr 5 (7.03.2019): 892. http://dx.doi.org/10.3390/en12050892.
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One of the most notable challenges in wireless communications is energy scarcity, which has attracted considerable attention in Fifth Generation (5G) wireless network research. This paper investigates the performance of energy harvesting (EH) relays under the best relay selection (BRS) scheme. The results show degradation of spectral efficiency (SE) due to EH relaying compared with conventional cooperative relaying (CR). Conversely, EH relaying provides a positive gain compared with conventional CR, increasing the lifetime of the network and decreasing energy consumption (EC) and operational cost. Moreover, the EH relaying network has better energy efficiency (EE) compared with conventional relaying networks. Results show that when EH relaying is applied, EE is improved through an increased number of relays. Finally, the SE-EE metric is presented for both conventional and EH relays. Results show that the performance of the proposed technique was able to achieve a maximum SE of 1.4 bits/s/Hz and maximum EE at 0.6 bits/s/Hz, and for the case of conventional relays, a maximum SE of 2 bits/s/Hz and EE at 1.1 bits/s/Hz. This result implies that the proposed EH scheme provides an optimum solution for energy-constrained wireless CR systems.
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Wang, Yaqing, Shiyong Chen, Yucheng Wu i Chengxin Zhao. "Maximizing Average Throughput of Cooperative Cognitive Radio Networks Based on Energy Harvesting". Sensors 22, nr 22 (18.11.2022): 8921. http://dx.doi.org/10.3390/s22228921.
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Energy harvesting (EH) and cooperative communication techniques have been widely used in cognitive radio networks. However, most studies on throughput in energy-harvesting cooperative cognitive radio networks (EH-CCRNs) are end-to-end, which ignores the overall working state of the network. For the above problems, under the premise of prioritizing the communication quality of short-range users, this paper focuses on the optimization of the EH-CCRN average throughput, with energy and transmission power as constraints. The formulated problem was an unsolved non-deterministic polynomial-time hardness (NP-hard) problem. To make it tractable to solve, a multi-user time-power resource allocation algorithm (M-TPRA) is proposed, which is based on sub-gradient descent and unary linear optimization methods. Simulation results show that the M-TPRA algorithm can improve the average throughput of the network. In addition, the energy consumed by executing the M-TPRA algorithm is analyzed.
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Zareei, Mahdi, Cesar Vargas-Rosales, Mohammad Hossein Anisi, Leila Musavian, Rafaela Villalpando-Hernandez, Shidrokh Goudarzi i Ehab Mahmoud Mohamed. "Enhancing the Performance of Energy Harvesting Sensor Networks for Environmental Monitoring Applications". Energies 12, nr 14 (20.07.2019): 2794. http://dx.doi.org/10.3390/en12142794.
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Fast development in hardware miniaturization and massive production of sensors make them cost efficient and vastly available to be used in various applications in our daily life more specially in environment monitoring applications. However, energy consumption is still one of the barriers slowing down the development of several applications. Slow development in battery technology, makes energy harvesting (EH) as a prime candidate to eliminate the sensor’s energy barrier. EH sensors can be the solution to enabling future applications that would be extremely costly using conventional battery-powered sensors. In this paper, we analyze the performance improvement and evaluation of EH sensors in various situations. A network model is developed to allow us to examine different scenarios. We borrow a clustering concept, as a proven method to improve energy efficiency in conventional sensor network and brought it to EH sensor networks to study its effect on the performance of the network in different scenarios. Moreover, a dynamic and distributed transmission power management for sensors is proposed and evaluated in both networks, with and without clustering, to study the effect of power balancing on the network end-to-end performance. The simulation results indicate that, by using clustering and transmission power adjustment, the power consumption can be distributed in the network more efficiently, which result in improving the network performance in terms of a packet delivery ratio by 20%, 10% higher network lifetime by having more alive nodes and also achieving lower delay by reducing the hop-count.
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Al_Issa, Huthaifa Ahmad, La’aly Ahmed Al-Samrraie, Khalideh Al bkoor Rawashdeh i Aya Sate’ Jaradat. "Collecting data in smart cities using energy harvesting technology". International Journal of Power Electronics and Drive Systems (IJPEDS) 13, nr 2 (1.06.2022): 846. http://dx.doi.org/10.11591/ijpeds.v13.i2.pp846-855.
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<p>This work investigates the problems of extending the sensors network lifetime in smart cities. The limited capacity of the sensors’ batteries, and the difficulty of replacing the sensors’ batteries in hard-to-reach areas are some of the main challenges that contribute in reducing the lifetimes of the networks. The direction of this study is to use renewable energy as an energy source for collecting data from various infrastructures that are distributed throughout these cities. We present a model for data collection based on combining energy harvesting (EH) with the cluster head rotation feature, which results in flexible and sustainable networks that can be used in smart cities. Simulation results depict the performance of the proposed model with and without EH technology. The metrics used to compare the performance of the proposed model with and without EH technology include the consumed energy by sensors, number of live and dead sensors, and energy variance. The results show that the network lifetime increases when EH technology is used.</p>
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Li, Pengxu, Gaofeng Cui i Weidong Wang. "Distributed Optimal Random Access Scheme for Energy Harvesting Devices in Satellite Communication Networks". Sensors 19, nr 1 (28.12.2018): 99. http://dx.doi.org/10.3390/s19010099.
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This paper considers satellite communication networks where each satellite terminal is equipped with energy harvesting (EH) devices to supply energy continuously, and randomly transmits bursty packets to a geostationary satellite over a shared wireless channel. Packet replicas combined with a successive iteration cancellation scheme can reduce the negative impact of packet collisions but consume more energy. Hence, appropriate energy management policies are required to mitigate the adverse effect of energy outages. Although centralized access schemes can provide better performance on the networks’ throughput, they expend extra signallings to allocate the resources, which leads to non-negligible communication latencies, especially for the satellite communication networks. In order to reduce the communication overhead and delay, a distributed random access (RA) scheme considering the energy constraints is studied. Each EH satellite terminal (EH-ST) decides whether to transmit the packet and how many replicas are transmitted according to its local energy and EH rates to maximize the average long-term network throughput. Owing to the nonconvexity of this problem, we adopted a game theoretic method to approximate the optimal solution. By forcing all the EH-STs to employ the same policy, we characterized and proved the existence and uniqueness of the symmetric Nash equilibrium (NE) of the game. Moreover, an efficient algorithm is proposed to calculate the symmetric NE by combining a policy iteration algorithm and the bisection method. The performance of the proposed RA scheme was investigated via numerous simulations. Simulation results showed that the proposed RA scheme is applicable to the EH devices in the future low-cost interactive satellite communication system.
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Adu-Manu, Kofi Sarpong, Nadir Adam, Cristiano Tapparello, Hoda Ayatollahi i Wendi Heinzelman. "Energy-Harvesting Wireless Sensor Networks (EH-WSNs)". ACM Transactions on Sensor Networks 14, nr 2 (21.07.2018): 1–50. http://dx.doi.org/10.1145/3183338.
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Modem, Sudhakar, i Shankar Prakriya. "Performance of EH Protocols in Two-Hop Networks With a Battery-Assisted EH Relay". IEEE Transactions on Vehicular Technology 67, nr 10 (październik 2018): 10022–26. http://dx.doi.org/10.1109/tvt.2018.2853614.
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LI, QIULI, i WANTAO NING. "Matching Preclusion for Exchanged Hypercubes". Journal of Interconnection Networks 19, nr 03 (wrzesień 2019): 1940008. http://dx.doi.org/10.1142/s0219265919400085.
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As spanning subgraphs of hypercubes, exchanged hypercubes contain less edges but maintain lots of desired properties of hypercubes. This paper considers matching preclusion, a kind of measures of edge-fault tolerance, of exchanged hypercubes EH(s, t). We show that EH(s, t) is maximally matched, that is, for s ≥ t, mp(EH(s, t)) = t + 1 and EH(s, t) is super matched if and only if (s, t) ≠ (1, 1). Comparing with results of matching preclusion for hypercubes, we conclude that exchanged hypercubes maintain the matching preclusion property of hypercubes, except for EH(1, 1).
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Liu, Xiaoying, Ming Xia, Ping Hu, Kechen Zheng i Shubin Zhang. "Optimal Time Allocation for Energy Harvesting Cognitive Radio Networks with Multichannel Spectrum Sensing". Wireless Communications and Mobile Computing 2022 (21.08.2022): 1–11. http://dx.doi.org/10.1155/2022/3940132.
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From the perspective of time domain and frequency domain, we investigate the energy harvesting cognitive radio networks (EH-CRNs) with multichannel, where the secondary transmitter (ST) opportunistically accesses the licensed subchannels to transmit packets by consuming the harvested energy. To explore the spectrum holes and improve the lifetime of the EH-CRNs, the ST scavenges energy from the radio-frequency (RF) signal in the wide band during the energy harvesting (EH) phase and exploits the harvested energy for sequential sensing and packet transmission during the rest of the time slot. Under the energy constraint, the secondary throughput is improved by optimizing the time allocation among the EH phase, sensing phase, and transmission phase. We formulate the secondary throughput with respect to the durations of the three phases, prove the existence of the optimal time allocation, and discuss the secondary throughput in three cases of the EH-CRNs. Finally, numerical results validate the theoretical results about the secondary throughput and explore the impacts of key system parameters.
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Le, Anh-Tu, i Dinh-Thuan Do. "Joint impacts of relaying scheme and wireless power transfer in multiple access of cellular networks". Bulletin of Electrical Engineering and Informatics 10, nr 2 (1.04.2021): 811–19. http://dx.doi.org/10.11591/eei.v10i2.1936.
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This paper considers ergodic capacity of energy harvesting (EH) based cellular networks. Such a network employs non-orthogonal multiple access (NOMA) together with relaying scheme to serve two far users. In this system model, relay is facilitated power splitting (PS) protocol to implement energy harvesting (EH). To examine capacity, expressions of signal to noise ratio (SNR) need be computed to achieve capacity. Power allocation factors are different for two users in such system and hence performance gap happens to distinguish requirements for separated users. It can be confirmed that the proposed paradigm exhibits maximal achievable capacity in some scenarios of setting parameters. To confirm exactness of the analytical expressions and show advantages of the proposed EH-NOMA, simulation results are performed in terms of ergodic capacity.
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Jiang, Ruihong, Ke Xiong, Yu Zhang, Li Zhou, Tong Liu i Zhangdui Zhong. "Outage and Throughput of WPCN-SWIPT Networks with Nonlinear EH Model in Nakagami-m Fading". Electronics 8, nr 2 (29.01.2019): 138. http://dx.doi.org/10.3390/electronics8020138.
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This paper analyzes outage probability and reliable throughput performance of a multi-user wireless-powered communication network-simultaneous wireless information and power transfer (WPCN-SWIPT) network with the logistic function-based (LG) nonlinear energy-harvesting (EH) model in Nakagami-m fading. Power-splitting (PS) receiver architecture is considered. The closed-form expressions of the system outage probability and the system reliable throughput are derived, and then the corresponding asymptotic expressions are also provided to achieve simpler calculation in the high-transmit power scenarios. Simulation results demonstrate the correctness of our derived analytical results and show that the systems under the LG nonlinear and linear EH models have very different performance behaviors. Moreover, since the LG nonlinear EH model is closer to the features of practical EH circuit than the linear one, using the LG nonlinear EH model can avoid the false output results of the system performance evaluation.
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Huang, Xueqing, i Nirwan Ansari. "Energy sharing within EH-enabled wireless communication networks". IEEE Wireless Communications 22, nr 3 (czerwiec 2015): 144–49. http://dx.doi.org/10.1109/mwc.2015.7143338.
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Cheng, Yulun, i Longxiang Yang. "An Energy-Efficient Transmission Protocol for RNC-Based Cooperative WSNs with Partial Energy Harvesting Nodes". International Journal of Distributed Sensor Networks 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/937404.
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This paper addresses the energy-efficient transmission for the scenario of cooperative wireless sensor networks with partial energy harvesting (EH) nodes. A new EH decoding-recoding policy is proposed by regarding the EH constraints and the characteristics of random network coding. We develop an energy efficiency model to investigate the tradeoff mechanism between the saved energy and the waiting time of the EH node, through which the corresponding parameters in the policy are also optimized. Moreover, we propose a novel transmission protocol by embedding the considered policy in the opportunistic reception algorithm. The decoding failure probability is then derived to examine its transmission reliability. The obtained theoretical and simulation results indicate that the proposed protocol achieves superiority in energy efficiency; meanwhile, it can also provide similar transmission reliability under specific conditions, as compared to the conventional algorithms in the two-hop model.
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Elshrkasi, Ahmed, Kaharudin Dimyati, Khairol Amali Bin Ahmad i Ezmin Abdullah. "Employing an Energy Harvesting Strategy to Enhance the Performance of a Wireless Emergency Network". Sensors 22, nr 12 (9.06.2022): 4385. http://dx.doi.org/10.3390/s22124385.
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Establishing a wireless communication network (WCN) is critical to saving people’s lives during disasters. Since the user equipment (UE) must transfer their information to the functioning area, their batteries will be significantly drained. Thus, technologies that can compensate for battery power consumption, such as the energy harvesting (EH) strategy, are highly required. This paper proposes a framework that employs EH at the main cluster head (MCH) selected by the enhanced clustering technique (CFT) and simultaneously transmits information and power wirelessly to prolong the lifetime of the energy-constrained network. MCH harvests energy from the radio frequency signal via the relay station (RS) and uses the harvested energy for D2D communications. The suggested framework was evaluated by analyzing the EH outage probability and estimating the energy efficiency performance, which is expected to improve the stability of the network. Compared to the UAV scenario, the simulation findings show that when RS is in its optimal location, it enhances the network EH outage probability performance by 26.3%. Finally, integrating CFT with wireless communications links into cellular networks is an effective technique for maintaining communication services for mission-critical applications.
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Xu, Yi-Han, Jing-Wei Xie, Yang-Gang Zhang, Min Hua i Wen Zhou. "Reinforcement Learning (RL)-Based Energy Efficient Resource Allocation for Energy Harvesting-Powered Wireless Body Area Network". Sensors 20, nr 1 (19.12.2019): 44. http://dx.doi.org/10.3390/s20010044.
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Wireless body area networks (WBANs) have attracted great attention from both industry and academia as a promising technology for continuous monitoring of physiological signals of the human body. As the sensors in WBANs are typically battery-driven and inconvenient to recharge, an energy efficient resource allocation scheme is essential to prolong the lifetime of the networks, while guaranteeing the rigid requirements of quality of service (QoS) of the WBANs in nature. As a possible alternative solution to address the energy efficiency problem, energy harvesting (EH) technology with the capability of harvesting energy from ambient sources can potentially reduce the dependence on the battery supply. Consequently, in this paper, we investigate the resource allocation problem for EH-powered WBANs (EH-WBANs). Our goal is to maximize the energy efficiency of the EH-WBANs with the joint consideration of transmission mode, relay selection, allocated time slot, transmission power, and the energy constraint of each sensor. In view of the characteristic of the EH-WBANs, we formulate the energy efficiency problem as a discrete-time and finite-state Markov decision process (DFMDP), in which allocation strategy decisions are made by a hub that does not have complete and global network information. Owing to the complexity of the problem, we propose a modified Q-learning (QL) algorithm to obtain the optimal allocation strategy. The numerical results validate the effectiveness of the proposed scheme as well as the low computation complexity of the proposed modified Q-learning (QL) algorithm.
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Lee, Kisong. "Low-Complexity Transmit Power Control for Secure Communications in Wireless-Powered Cognitive Radio Networks". Sensors 21, nr 23 (25.11.2021): 7837. http://dx.doi.org/10.3390/s21237837.
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In this study, wireless-powered cognitive radio networks (WPCRNs) are considered, in which N sets of transmitters, receivers and energy-harvesting (EH) nodes in secondary networks share the same spectrum with primary users (PUs) and none of the EH nodes is allowed to decode information but can harvest energy from the signals. Given that the EH nodes are untrusted nodes from the point of view of information transfer, the eavesdropping of secret information can occur if they decide to eavesdrop on information instead of harvesting energy from the signals transmitted by secondary users (SUs). For secure communications in WPCRNs, we aim to find the optimal transmit powers of SUs that maximize the average secrecy rate of SUs while maintaining the interference to PUs below an allowable level, while guaranteeing the minimum EH requirement for each EH node. First, we derive an analytical expression for the transmit power via dual decomposition and propose a suboptimal transmit power control algorithm, which is implemented in an iterative manner with low complexity. The simulation results confirm that the proposed scheme outperforms the conventional distributed schemes by more than 10% in terms of the average secrecy rate and outage probability and can also considerably reduce the computation time compared with the optimal scheme.
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Garcia, Carla E., Mario R. Camana i Insoo Koo. "Joint Beamforming and Artificial Noise Optimization for Secure Transmissions in MISO-NOMA Cognitive Radio System with SWIPT". Electronics 9, nr 11 (18.11.2020): 1948. http://dx.doi.org/10.3390/electronics9111948.
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The integration of non-orthogonal multiple access (NOMA) in cognitive radio (CR) networks has demonstrated how to enhance spectrum efficiency and achieve massive connectivity for future mobile networks. However, security is still a challenging issue due to the wireless transmission environment and the broadcast nature of NOMA. Thus, in this paper, we investigate a beamforming design with artificial noise (AN) to improve the security of a multi-user downlink, multiple-input single-output (MISO) NOMA-CR network with simultaneous wireless information and power transfer (SWIPT). To further support power-limited, battery-driven devices, energy-harvesting (EH) users are involved in the proposed network. Specifically, we investigate the optimal AN, power-splitting ratios, and transmission beamforming vectors for secondary users and EH users in order to minimize the transmission power of the secondary network, subject to the following constraints: a minimum signal-to-interference-plus-noise ratio at the secondary users, minimum harvested energy by secondary users and EH users, maximum power at the secondary transmitter, and maximum permissible interference with licensed users. The proposed solution for the challenging non-convex optimization problem is based on the semidefinite relaxation method. Numerical results show that the proposed scheme outperforms the conventional scheme without AN, the zero-forcing-based scheme and the space-division multiple-access-based method.
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Nguyen, Tan N., Minh Tran, Thanh-Long Nguyen, Duy-Hung Ha i Miroslav Voznak. "Performance Analysis of a User Selection Protocol in Cooperative Networks with Power Splitting Protocol-Based Energy Harvesting Over Nakagami-m/Rayleigh Channels". Electronics 8, nr 4 (19.04.2019): 448. http://dx.doi.org/10.3390/electronics8040448.
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In this work, the system performance analysis of cooperative networks with power splitting protocol-based energy harvesting (EH) over Nakagami-m/Rayleigh channels is proposed. The exact-form expressions of the outage probability (OP) and ergodic capacity (EC) is demonstrated and derived. Using the proposed probabilistic models for wireless channels, we derive OP and EC as a research result. Finally, we conduct Monte Carlo simulations to verify a system performance analysis of the proposed system. The research results demonstrate the effectiveness of EH in the network over Nakagami-m/Rayleigh channels.
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Liao, Jianbin, Hongliang Yu, Weibin Jiang, Ruiquan Lin i Jun Wang. "Optimal resource allocation method for energy harvesting based underlay Cognitive Radio networks". PLOS ONE 18, nr 1 (5.01.2023): e0279886. http://dx.doi.org/10.1371/journal.pone.0279886.
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This paper proposes an optimal resource allocation method. The method is to maximize the Energy Efficiency (EE) for an Energy Harvesting (EH) enabled underlay Cognitive Radio (CR) network. First, we assumed the Secondary Users (SUs) can harvest energy from the surrounding Radio Frequency (RF) signals. Then, we modelled the EE maximisation problem as a joint time and power optimization model. Next, the optimal EH time allocation factor can be calculated. After that the optimal power allocation strategy can be obtain by the fractional programming and Lagrange multiplier method. Finally simulation results show that the proposed iterative method can be better performance advantages compared with the exhaustive method and genetic algorithm. And the EE of this system model is significantly improved compared to the EE model without considering EH.
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Shang, Xiaohui, Hao Yin, Yida Wang, Mu Li i Yong Wang. "Secrecy Performance Analysis of Wireless Powered Sensor Networks Under Saturation Nonlinear Energy Harvesting and Activation Threshold". Sensors 20, nr 6 (14.03.2020): 1632. http://dx.doi.org/10.3390/s20061632.
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In this paper, we investigate the impact of saturation nonlinear energy harvesting (EH) and activation threshold on the multiuser wireless powered sensor networks (WPSNs) from the physical layer security (PLS) perspective. In particular, for improving the secrecy performance, the generalized multiuser scheduling (GMS) scheme is exploited, in which the Kth strongest sensor is chosen based on the legitimate link. For evaluating the impact of various key parameters on the security of system, we obtain the exact closed-form expressions for secrecy outage probability (SOP) under linear EH (LEH), saturation nonlinear EH (SNEH) and saturation nonlinear EH with activation threshold (SNAT), respectively, and solve the maximization problem of secure energy efficiency (SEE). Simulation results demonstrate that: (1) the number of source sensors, the EH efficiency and the transmit power of power beacon (PB) all have positive impact on SOP, and the smaller generalized selection coefficient is advantageous for secrecy performance; (2) LEH is an ideal situation for SNEH when the saturation threshold is large enough and SNEH is a special situation for SNAT when the activation threshold is low enough; (3) the time-switching factor and the activation threshold both have an important impact on the secrecy performance, which are worth considering carefully.
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Baljon, Mohammed, i Lian Zhao. "Resource Allocation for Wireless Networks with Energy Harvesting Constraints Over Fading Channels". Journal of Science and Technology: Issue on Information and Communications Technology 2, nr 1 (31.08.2016): 9. http://dx.doi.org/10.31130/jst.2016.20.
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This research work considers the utilize of energy harvesters, instead of conventional time-invariant energy sources, in wireless communication. For the purpose of exposition, we study the traditional two-hop communication system for delay limited (DL) and delay tolerant (DT) relaying networks over fading channels, in which the source node transmits with power drawn from energy harvesting (EH) sources and the relay transmits with conventional non-EH sources. We address the throughput maximization problem for the proposed system model for DL and DT cases. We find that the optimal power allocation algorithm for the single-hop communication system with EH constraints, namely, recursive geometric water-filling(RGWF), can be utilized as a guideline for the design of the two-hop system. We first introduce RGWF algorithm and we show the advantages of the geometric approach in eliminating the complexity of the Karush-Kuhn-Tucker (KKT) condition as well as providing a closed-form and exact solutions to the proposed problem. Based on the RGWF algorithm, we propose offline joint power allocation and transmission time scheduling schemes for DL relaying network and DT relaying network. We also propose efficient online resource allocation schemes for both relays’ cases. The performance of the proposed schemes is evaluated via simulation and the results demonstrate that a network with delay tolerant ability provides better performance in term of throughput.
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Neyland, Blake R., Robert Kraft, Mary Lyles, Stephen Kritchevsky, Paul J. Laurienti, Barbara M. Nicklas i Christina Hugenschmidt. "EFFECTS OF FUNCTIONAL BRAIN NETWORKS AND WHITE MATTER DISEASE ON MOBILITY OF OLDER ADULTS IN AN EXERCISE INTERVENTION". Innovation in Aging 3, Supplement_1 (listopad 2019): S851—S852. http://dx.doi.org/10.1093/geroni/igz038.3132.
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Abstract Declining mobility is associated with increased accumulation of white matter hyperintensities (WMH). However, a high WMH burden is not always accompanied by impaired mobility. Our previous work demonstrates that some variance in mobility may be explained by brain network connectivity. Here, we extended this work by measuring WMHs and brain networks in older adults participating in a lifestyle intervention. The Short Physical Performance Battery (SPPB) and resting state functional magnetic resonance imaging (fMRI) were collected before and after a 5-month caloric restriction plus aerobic exercise intervention in 57 obese, sedentary adults aged 65-78. Participants were categorized based on median splits of baseline SPPB scores and WMH burden: Expected Healthy (EH: low WMH, SPPB≥11, n=16), Expected Impaired (EI: high WMH, SPPB≤10, n=17), Unexpected Healthy (UH: high WMH, SPPB≥11, n=12), and Unexpected Impaired (UI: low WMH, SPPB≤10, n=12). Graph theory-based methods were used to characterize brain networks and compare the four groups. At baseline, the somatomotor cortex community structure (SMC-CS) was less consistent in EI (p=0.05) and UI (p=0.23) compared to EH. The EI (mean=1.25, p=0.003) and UI (mean=1.57, p=0.001) significantly improved their SPPB scores following the intervention. Although both groups had equivalent SPPB scores, SMC-CS was less consistent in the UH than EH (p=0.16). However, UH displayed a significant (p=0.004) increase in second-order connections to the precuneus compared to EH. These data suggest that studying brain networks could improve the understanding of the development of mobility disability and the CNS contributions to mobility independent of white matter disease.
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Ahmed, Sheeraz, Malik Taimur Ali, Asma A. Alothman, Asif Nawaz, M. Shahzad, Ahmed Ali Shah, Awais Ahmad, M. Yousaf Ali Khan, Zeeshan Najam i Asma Shaheen. "EH-UWSN: Improved Cooperative Routing Scheme for UWSNs Using Energy Harvesting". Journal of Sensors 2020 (22.09.2020): 1–18. http://dx.doi.org/10.1155/2020/8888957.
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The harsh testing environments of underwater scenarios make it extremely hard to plan a reasonable routing protocol for Underwater Sensor Networks (UWSNs). The main challenge in UWSNs is energy confinement. It is needed to plan an energy effective scheme which increases the life span of the network and also reduces the energy usage in data transfer from supplier to sink. In this research, we present the design of a routing protocol known as Energy Harvesting in UWSN (EH-UWSN). EH-UWSN is a compact, energy efficient, and high throughput routing protocol, in which we present utilization of energy gaining with coordinating transfer of data packets through relay nodes. Through Energy Harvesting, the nodes are capable to recharge their batteries from the outside surrounding with the ultimate objective to improve the time span of network and proceed data through cooperation, along with restricting energy usage. At the sink node, the mixing plan applied is centered on Signal-to-Noise Ratio Combination (SNRC). Outcomes of EH-UWSN procedure reveal good results in terms of usage of energy, throughput, and network life span in comparing with our previous Cooperative Routing Scheme for UWSNs (Co-UWSN). Simulation results show that EH-UWSN has consumed considerably lesser energy when compared with Co-UWSN along with extending network lifetime and higher throughput at the destination.
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Salari, Soheil, Il-Min Kim, Dong In Kim i Francois Chan. "Joint EH Time Allocation and Distributed Beamforming in Interference-Limited Two-Way Networks With EH-Based Relays". IEEE Transactions on Wireless Communications 16, nr 10 (październik 2017): 6395–408. http://dx.doi.org/10.1109/twc.2017.2723466.
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Thien Van, Hoang, Quyet-Nguyen Van, Danh Hong Le, Lukas Sevcik, Nguyen Hoang Duy, Hoang-Sy Nguyen i Miroslav Voznak. "Threshold-based Wireless-based NOMA Systems over Log-Normal Channels: Ergodic Outage Probability of Joint Time Allocation and Power Splitting Schemes". Elektronika ir Elektrotechnika 27, nr 3 (28.06.2021): 78–83. http://dx.doi.org/10.5755/j02.eie.28971.
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Due to the development of state-of-the-art fifth-generation communication (5G) and Internet-of-Things (IoT), the demands for capacity and throughput of wireless networks have increased significantly. As a promising solution for this, a radio access technique, namely, non-orthogonal multiple access (NOMA) has been investigated. Particularly, in this paper, we analyse the system performance of a joint time allocation and power splitting (JTAPS) protocol for NOMA-based energy harvesting (EH) wireless networks over indoor scenarios, which we modelled with log-normal fading channels. Accordingly, for the performance analysis of such networks, the analytical expression of a metric so-called “ergodic outage probability” was derived. Then, thanks to Monte Carlo simulations done in Matlab, we are able to see how different EH power splitting (PS) and EH time switching (TS) factors influence the ergodic outage probability. Last, but not least, we plot the simulation results along with the theoretical results for comparison studies.
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Boulerial, Dalila, Bouabdellah Kechar i Ali Benzerbadj. "Enhancing Network Lifetime of Duty Cycle-Based WSN With Mobile Sink Using Ambient Energy Harvesting". International Journal of Distributed Systems and Technologies 14, nr 1 (10.02.2023): 1–16. http://dx.doi.org/10.4018/ijdst.317413.
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In order to guarantee a successful data collection process in wireless sensor networks with mobile sinks (WSN-MS), two primary objectives must be reached: 1) enabling the mobile sink to retrieve the maximum amount of data and 2) making sure that the network operates as long as possible. The first problem has been solved previously by proposing an innovative solution HXMAC. To address the second problem, on which this paper focuses, ambient energy harvesting is used to continuously supply power to each sensor node. Thus, this paper's main contribution is to propose EH-HXMAC (HXMAC with energy harvesting), which is based on all these improvements: seamless handover, duty cycling optimization, and mainly energy harvesting capability. EH-HXMAC has been evaluated using Cooja Contiki simulator. Obtained results based on the evaluation of the proposal EH-HXMAC clearly show its suitability as a good solution to promote unlimited lifetime for WSN-MS.
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Babaei, Mohammadreza, Lütfiye Durak-Ata i Ümit Aygölü. "New Practical Nonlinear Energy-Harvesting Models for Wireless-Powered Communications". Wireless Communications and Mobile Computing 2022 (25.06.2022): 1–19. http://dx.doi.org/10.1155/2022/6534754.
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As a massive number of nodes are expected to be connected to each other in next-generation wireless networks, the power supply of such multiple-antenna nodes is a challenge and requires new and sustainable solutions. Radio frequency energy harvesting (EH) is among the promising approaches to solve this issue. In this paper, two new mathematically tractable nonlinear EH (NL-EH) models are proposed, for which the system performance is evaluated in terms of average harvested power, throughput, and bit error probability. The system consists of one multiantenna power-constraint source harvesting its power from a dedicated power beacon and transmitting its signal to a destination equipped with multiple antennas. For a comprehensive analysis of the system, closed-form expressions are derived for Nakagami- m fading channels and the special case of Rayleigh channels. For comparison purposes, the performance derivations in Nakagami- m fading channels are provided for linear and piece-wise linear EH models given in the literature. Besides, the simulation results are obtained by applying the Monte-Carlo method for NL-EH models existing in the literature. The results provide a broadening view of EH systems and thoroughly compare the proposed NL-EH models with linear, piece-wise linear, and NL-EH models available in the literature. Hence, these provide better insights towards the analyses and design of EH systems.
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Beltramo, Emmanuel, Martín E. Pérez Segura, Bruno A. Roccia, Marcelo F. Valdez, Marcos L. Verstraete i Sergio Preidikman. "Constructive Aerodynamic Interference in a Network of Weakly Coupled Flutter-Based Energy Harvesters". Aerospace 7, nr 12 (24.11.2020): 167. http://dx.doi.org/10.3390/aerospace7120167.
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Converting flow-induced vibrations into electricity for low-power generation has received growing attention over the past few years. Aeroelastic phenomena, good candidates to yield high energy performance in renewable wind energy harvesting (EH) systems, can play a pivotal role in providing sufficient power for extended operation with little or no battery replacement. In this paper, a numerical model and a co-simulation approach have been developed to study a new EH device for power generation. We investigate the problem focusing on a weakly aerodynamically coupled flutter-based EH system. It consists of two flexible wings anchored by cantilevered beams with attached piezoelectric layers, undergoing nonlinear coupled bending–torsion limit cycle oscillations. Besides the development of individual EH devices, further issues are posed when considering multiple objects for realizing a network of devices and magnifying the extracted power due to nonlinear synergies and constructive interferences. This work investigates the effect of various external conditions and physical parameters on the performance of the piezoaeroelastic array of devices. From the viewpoint of applications, we are most concerned about whether an EH can generate sufficient power under a variable excitation. The results of this study can be used for the design and integration of low-energy wind generation technologies into buildings, bridges, and built-in sensor networks in aircraft structures.
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Alghamdi, Ali S., Mohana Alanazi, Abdulaziz Alanazi, Yazeed Qasaymeh, Muhammad Zubair, Ahmed Bilal Awan i Muhammad Gul Bahar Ashiq. "Energy Hub Optimal Scheduling and Management in the Day-Ahead Market Considering Renewable Energy Sources, CHP, Electric Vehicles, and Storage Systems Using Improved Fick’s Law Algorithm". Applied Sciences 13, nr 6 (9.03.2023): 3526. http://dx.doi.org/10.3390/app13063526.
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Coordinated energy scheduling and management strategies in the energy hub plan are essential to achieve optimal economic performance. In this paper, the scheduling and management framework of an energy hub (EH) is presented with the aim of energy profit maximization in partnership with electricity, natural gas, and district heating networks (EGHNs) considering the coordinated multi-energy management based on the day-ahead market. The optimum capacity of EH equipment, including photovoltaic and wind renewable energy sources, a combined heat and power system (CHP), a boiler, energy storage, and electric vehicles is determined in the day-ahead market using the improved Fick’s law algorithm (IFLA), considering the energy profit maximization and also satisfying the linear network and hub constraints. The conventional FLA is inspired by the concept of Fick’s diffusion law, and, in this study, its performance against premature convergence is improved by using Rosenbrock’s direct rotational method. The performance of the IFLA when applied to EH coordinated scheduling and management problems with the aim of profit maximization is compared with the conventional FLA, particle swarm optimization (PSO), and manta ray foraging optimization (MRFO) methods. The results show that the proposed scheduling and multi-energy management framework achieves more energy profit in the day-ahead electricity, gas, and heating markets by satisfying the operation and EH constraints compared to other methods. Furthermore, according to the findings, the increased (decreased) demand and the forced outage rate caused a decrease (increase) in the EH profit. The results show the effectiveness of the proposed framework to obtain the EH maximum energy profit in the day-ahead market.
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Galmés, Sebastià. "Optimal Routing for Time-Driven EH-WSN under Regular Energy Sources". Sensors 18, nr 11 (21.11.2018): 4072. http://dx.doi.org/10.3390/s18114072.
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The recent provision of energy-harvesting capabilities to wireless sensor networks (WSN) has entailed the redefinition of design objectives. Specifically, the traditional goal of maximizing network lifetime has been replaced by optimizing network performance, namely delay and throughput. The present paper contributes to this reformulation by considering the routing problem for the class of time-driven energy-harvesting WSN (EH-WSN) under regular or quasi-periodic energy sources. In particular, this paper shows that the minimum hop count (MHC) criterion maximizes the average duty cycle that can be sustained by nodes in this type of scenarios. This is a primary objective in EH-WSN, since large duty cycles lead to enhanced performance. Based on a previous result, a general expression is first obtained that gives mathematical form to the relationship between duty cycle and traffic load for any node in a time-driven EH-WSN fed by a regular energy source. This expression reveals that the duty cycle achievable by a node decreases as its traffic load increases. Then, it is shown that MHC minimizes the average traffic load over the network, and thus it maximizes the average duty cycle of nodes. This result is numerically validated via simulation by comparison with other well-known routing strategies. Accordingly, this paper suggests assigning top priority to the MHC criterion in the development of routing protocols for time-driven EH-WSN under regular energy sources.
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YANG, Bo, i Lei WANG. "EH-EC: High performance data forwarding mechanism for opportunistic networks". Journal of Computer Applications 30, nr 12 (5.01.2011): 3180–83. http://dx.doi.org/10.3724/sp.j.1087.2010.03180.
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El Shafie, Ahmed, Asma Mabrouk, Kamel Tourki, Naofal Al-Dhahir i Ridha Hamila. "Securing Untrusted RF-EH Relay Networks Using Cooperative Jamming Signals". IEEE Access 5 (2017): 24353–67. http://dx.doi.org/10.1109/access.2017.2768508.
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Chen, Quan, Zhipeng Cai, Lianglun Cheng, Hong Gao i Jianzhong Li. "Energy-collision-aware Minimum Latency Aggregation Scheduling for Energy-harvesting Sensor Networks". ACM Transactions on Sensor Networks 17, nr 4 (16.07.2021): 1–34. http://dx.doi.org/10.1145/3461013.
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The emerging energy-harvesting technology enables charging sensor batteries with renewable energy sources, which has been effectively integrated into Wireless Sensor Networks (EH-WSNs). Due to the limited energy-harvesting capacities of tiny sensors, the captured energy remains scarce and differs greatly among nodes, which makes the data aggregation scheduling problem more challenging than that in energy-abundant WSNs. In this article, we investigate the Minimum Latency Aggregation Scheduling (MLAS) problem in EH-WSNs. First, we identify a new kind of collision in EH-WSNs, named as energy-collision, and design several special structures to avoid it during data aggregation. To reduce the latency, we try to choose the parent adaptively according to nodes’ transmission tasks and energy-harvesting ability, under the consideration of collisions avoidance. By considering transmitting time, residual energy, and energy-collision, three scheduling algorithms are proposed under protocol interference model. Under physical interference model, several approximate algorithms are also designed by taking account of the interference from the nodes several hops away. Finally, the theoretical analysis and simulation results verify that the proposed algorithms have high performance in terms of latency.
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Do, Dinh-Thuan. "Optimal Energy Harvesting Scheme for Power Beacon-Assisted Wireless-Powered Networks". Indonesian Journal of Electrical Engineering and Computer Science 7, nr 3 (1.09.2017): 802. http://dx.doi.org/10.11591/ijeecs.v7.i3.pp802-808.
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In this paper, we consider one-way relay with energy harvesting system based on power beacon (PB), in which the relay node harvests transmitted power from the PB station to forward signals to destination. We also analyse the relay network model with amplify-and-forward (AF) protocol for information cooperation and Power Splitting-based Relaying (PSR) protocol for power transfer. In particular, the outage probability and optimal energy harvesting (EH) power splitting fraction of novel scheme in are presented. We obtain analytical closed-form expression of optimal energy harvesting (EH) power splitting fraction to minimize the outage probability of system. Using numerical and analytical simulations, the performances of different cases are presented and discussed.
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Yakine, Fadoua, i Adil Kenzi. "Energy Harvesting in wireless communication: A survey". E3S Web of Conferences 336 (2022): 00074. http://dx.doi.org/10.1051/e3sconf/202233600074.
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Wireless Sensor Network is an emerging technology that has the potential to be used in futuristic applications. Sensor nodes are energy-constrained. They rely on batteries with limited capacity which impact their lifetime or mobility. To address this problem, energy harvesting technology is a solution that aims to avoid the premature energy depletion of nodes. It recharges their batteries using an energy harvesting system from the environment. In this review work, we present the concept of energy harvesting technology (EH) and Energy-Harvesting for Wireless Sensor Network (EH-WSN). We then discuss many schemes in the literature to save energy consumption of the energy harvesting sensor networks. We study their protocol design strategies and working principals. We also summarize their merits, demerits along with some future research directions.
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Van, Hoang Thien, Hoang-Sy Nguyen, Thanh-Sang Nguyen, Van Van Huynh, Thanh-Long Nguyen, Lukas Sevcik i Miroslav Voznak. "Outage Performance Analysis of Non-Orthogonal Multiple Access with Time-Switching Energy Harvesting". Elektronika ir Elektrotechnika 25, nr 3 (25.06.2019): 85–91. http://dx.doi.org/10.5755/j01.eie.25.3.23682.
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In recent years, although non-orthogonal multiple access (NOMA) has shown its potentials thanks to its ability to enhance the performance of future wireless communication networks, a number of issues emerge related to the improvement of NOMA systems. In this work, we consider a half-duplex (HD) relaying cooperative NOMA network using decode-and-forward (DF) transmission mode with energy harvesting (EH) capacity, where we assume the NOMA destination (D) is able to receive two data symbols in two continuous time slots which leads to the higher transmission rate than traditional relaying networks. To analyse EH, we deploy time-switching (TS) architecture to comprehensively study the optimal transmission time and outage performance at D. In particular, we are going to obtain closed-form expressions for outage probability (OP) with optimal TS ratio for both data symbols with both exact and approximate forms. The given simulation results show that the placement of the relay (R) plays an important role in the system performance.
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Lee, Kisong. "Energy-Efficient Secure Communications for Wireless-Powered Cognitive Radio Networks". Sensors 21, nr 23 (1.12.2021): 8040. http://dx.doi.org/10.3390/s21238040.
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In this study, we investigate energy-efficient secure communications for wireless-powered cognitive ratio networks, in which multiple secondary users (SUs) share the same frequency band with primary users (PUs) and energy harvesting (EH) nodes harvest energy from the transmitted signals, even though information decoding is not permitted. To maximize the average secrecy energy efficiency (SEE) of SUs while ensuring acceptable interference on PUs and the required amount of energy for the EH nodes, we propose an energy-efficient transmit power control algorithm using dual decomposition, wherein suboptimal transmit powers are determined in an iterative manner with low complexity. Through extensive simulations in various scenarios, we verify that the proposed scheme has a higher average SEE than conventional schemes and a considerably shorter computation time than the optimal scheme.
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K Sonwalkar, Prakash, i Vijay Kalmani. "Energy Harvesting Rectenna Design for Enhanced Node Lifetime in WSNs". International journal of Computer Networks & Communications 14, nr 02 (31.03.2022): 135–52. http://dx.doi.org/10.5121/ijcnc.2022.14208.
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With the rising popularity and advent of many services on Wireless Sensor Networks (WSNs), there is a compelling need to have energy-efficient solutions. The sensors and devices are powered by batteries whose life is limited, and at times it is impossible to replace the batteries, especially in remote applications. In such a scenario, Energy Harvesting (EH) stands as an undisputed candidate for enhancing the network lifetime. Radio Frequency (RF) energy is the most commonly available, ubiquitous, and reliable energy source among all the available energy sources. While RF signal carries both information and energy, EH is possible for long-distance and mobile environments. This work discusses initial research in the domain of EH in wireless networks via Radio Frequency (RF) signals. The paper presents an EH rectenna for energy harvesting over 2.45 GHz (Wi-Fi band). The receiving antenna is designed to pick up the radio signal in the RF range (2.45 GHz) from the free space. The four patch elements design has an antenna substrate made with RT with a dielectric constant of 2.2. The paper presents the simulation results of the basic parameters of the antenna, such as return loss, input impedance, bandwidth, gain, directivity, and efficiency. H-shaped slot antenna and modified H-shaped antenna (with circular slot) are designed with a gain of 8.24 dB and 8.32 dB, return loss of -10 dB and -16 dB, and bandwidth of 64.8 MHz and 868 MHz. The high gain, large bandwidth, properly matched impedance for minimum return loss, and high efficiency of the modified H-shaped patch antenna makes it eligible for energy harvesting.
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Musacchio, Aldo. "Drawing links between Corporate Governance and Networks: Bankers in the Corporate Networks of Brazil, Mexico, and the United States Circa 1910". Entreprises et histoire 54, nr 1 (2009): 16. http://dx.doi.org/10.3917/eh.054.0016.
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Panic, Stefan R., Dushantha Nalin K. Jayakody, Sofiene Affes i Palanivelu Muthuchidambaranathan. "Hardware Impaired Self-Energized Bidirectional Sensor Networks over Complex Fading Channels". Sensors 20, nr 19 (29.09.2020): 5574. http://dx.doi.org/10.3390/s20195574.
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Rapid emergence of wireless sensor networks (WSN) faces significant challenges due to limited battery life capacity of composing sensor nodes. It is substantial to construct efficient techniques to prolong the battery life of the connected sensors in order to derive their full potential in the future Internet of Things (IoT) paradigm. For that purpose, different energy harvesting (EH) schemes are relying on a wide array of sources. Following the same objective, in this work, we have observed a time-switching EH for half-duplex (HD) bidirectional WSN, which performed in-between relaying over Hoyt fading channels. For its comprehensive performance analysis, rapidly converging infinite-series expressions have been provided with focus on the outage probability (OP) and achievable throughput of the hardware-impaired system. Additionally, asymptotic behavior of these performance measures has also been provided. Further, an approach to the symbol-error probability (SEP) analysis is also presented in the context of the observed system. Finally, we consider the shadowing influence along the WSN propagation path. Performance analysis of observed EH system operating over Rician-shadowed fading channels has been carried out, with deriving exact corresponding infinite-series expressions for outage probability (OP) and achievable throughput of the system under the hardware impairment conditions. In addition, bidirectional relaying in a mixed fading environment has been considered.
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Han, Song, Luo Li i Xinbin Li. "Deep Q-Network-Based Cooperative Transmission Joint Strategy Optimization Algorithm for Energy Harvesting-Powered Underwater Acoustic Sensor Networks". Sensors 20, nr 22 (14.11.2020): 6519. http://dx.doi.org/10.3390/s20226519.
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Cooperative transmission is a promising technology for underwater acoustic sensor networks (UASNs) to ensure the effective collection of underwater information. In this paper, we study the joint relay selection and power allocation problem to maximize the cumulative quality of information transmission in energy harvesting-powered UASNs (EH-UASNs). First, we formulate the process of cooperative transmission with joint strategy optimization as a Markov decision process model. In the proposed model, an effective state expression is presented to better reveal interactive relationship between learning and environment, thereby improving the learning ability. Then, we further propose a novel reward function which can guide nodes to adjust power strategy adaptively to balance instantaneous capacity and long-term quality of service (QoS) under the dynamic unpredictable energy harvesting. More specifically, we propose a deep Q-network-based resource allocation algorithm for EH-UASNs to solve the complex coupled strategy optimization problem without any prior underwater environment information. Finally, simulation results verify the superior performance of the proposed algorithm in improving the cumulative network capacity and reducing outages.
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Orians, Carlyn, Shyanika Rose, Brian Hubbard, John Sarisky, Letitia Reason, Tiffiny Bernichon, Edward Liebow, Bradley Skarpness i Sharunda Buchanan. "Strengthening the Capacity of Local Health Agencies through Community-Based Assessment and Planning". Public Health Reports 124, nr 6 (listopad 2009): 875–82. http://dx.doi.org/10.1177/003335490912400616.
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Objectives. We evaluated the effectiveness of the Protocol for Assessing Community Excellence in Environmental Health (PACE EH) in building competency in essential environmental health services and renewing efforts to engage the community in problem solving. Competency and community engagement have been identified by environmental health practitioners as important to meet new threats to public health. Methods. We conducted a national survey and 24 case studies of public health agencies. We invited 917 organizations to participate in the national survey because they had requested a copy of the protocol. Results. We received 656 total responses: 354 had not considered implementation, 302 had considered implementation, and 66 had implemented PACE EH. For the 24 case studies, we interviewed 206 individuals in communities implementing PACE EH. We found that PACE EH has had a positive effect on building community and professional networks, enhancing leadership, developing workforce competence, and expanding definitions of environmental health practice. Conclusions. With appropriate investments, PACE EH can be an effective tool to meet the environmental health challenges identified by local environmental health practitioners and state, tribal, and federal agencies.
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Koistinen, David, i Kenneth Lipartito. "Offshoring, outsourcing and global production networks in historical context". Entreprises et histoire 94, nr 1 (2019): 62. http://dx.doi.org/10.3917/eh.094.0062.
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Liu, Kang, Qi Zhu i Ying Wang. "Outage Analysis and Power Allocation Optimization for Multiple Energy-Harvesting Relay System Using SWIPT". Mobile Information Systems 2018 (13.09.2018): 1–11. http://dx.doi.org/10.1155/2018/7102427.
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Energy harvesting (EH) combined with cooperative relying plays a promising role in future wireless communication systems. We consider a wireless multiple EH relay system. All relays are assumed to be EH nodes with simultaneous wireless and information transfer (SWIPT) capabilities, which means the relays are wirelessly powered by harvesting energy from the received signal. Each EH node separates the input RF signal into two parts which are, respectively, for EH and information transmission using the power splitting (PS) protocol. In this paper, a closed-form outage probability expression is derived for the cooperative relaying system based on the characteristic function of the system’s probability density function (PDF) with only one relay. With the approximation of the outage probability expression, three optimization problems are built to minimize the outage probability under different constraints. We use the Lagrange method and Karush–Kuhn–Tucker (KKT) condition to solve the optimization problems to jointly optimize the relay’s PS factors and the transmit power. Numerical results show that our derived expression of the outage probability is accuracy and gives insights into the effect of various system parameters on the performance of protocols. Meanwhile, compared with the no optimal condition, our proposed optimization algorithms can all offer superior performance under different system constraints.
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Rathore, Rajkumar Singh, Suman Sangwan, Kabita Adhikari i Rupak Kharel. "Modified Echo State Network Enabled Dynamic Duty Cycle for Optimal Opportunistic Routing in EH-WSNs". Electronics 9, nr 1 (3.01.2020): 98. http://dx.doi.org/10.3390/electronics9010098.
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Minimizing energy consumption is one of the major challenges in wireless sensor networks (WSNs) due to the limited size of batteries and the resource constrained tiny sensor nodes. Energy harvesting in wireless sensor networks (EH-WSNs) is one of the promising solutions to minimize the energy consumption in wireless sensor networks for prolonging the overall network lifetime. However, static energy harvesting in individual sensor nodes is normally limited and unbalanced among the network nodes. In this context, this paper proposes a modified echo state network (MESN) based dynamic duty cycle with optimal opportunistic routing (OOR) for EH-WSNs. The proposed model is used to act as a predictor for finding the expected energy consumption of the next slot in dynamic duty cycle. The model has adapted a whale optimization algorithm (WOA) for optimally selecting the weights of the neurons in the reservoir layer of the echo state network towards minimizing energy consumption at each node as well as at the network level. The adapted WOA enabled energy harvesting model provides stable output from the MESN relying on optimal weight selection in the reservoir layer. The dynamic duty cycle is updated based on energy consumption and optimal threshold energy for transmission and reception at bit level. The proposed OOR scheme uses multiple energy centric parameters for selecting the relay set oriented forwarding paths for each neighbor nodes. The performance analysis of the proposed model in realistic environments attests the benefits in terms of energy centric metrics such as energy consumption, network lifetime, delay, packet delivery ratio and throughput as compared to the state-of-the-art-techniques.