scholarly journals Energy Efficiency Optimization for AF Relaying with TS-SWIPT

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 993 ◽  
Author(s):  
Guangyue Lu ◽  
Chan Lei ◽  
Yinghui Ye ◽  
Liqin Shi ◽  
Tianci Wang
Keyword(s):  
Energy Efficiency ◽  
Relay Node ◽  
Relay Networks ◽  
Low Complexity ◽  
Maximization Problem ◽  
Amplify And Forward ◽  
Transmit Power ◽  
Time Switching ◽  
Energy Constrained ◽  
Performance Gains

In this paper, we focus on energy efficiency (EE) maximization for simultaneous wireless information and power transfer (SWIPT) based energy-constrained and amplify-and-forward (AF) relay networks. We adopt low-complexity time-switching (TS) protocol to realize SWIPT at the energy-constrained relay node, and formulate an EE maximization problem in which TS factor and transmit power control are needed to be jointly optimized. Since the formulated problem is non-convex and difficult to solve, we propose an algorithm combining fractional programming and alternating convex optimization to optimize TS factor and transmit power iteratively with low complexity. Simulation results are provided to demonstrate the convergence of the proposed algorithm, as well as the performance gains in terms of EE compared with other existing schemes.

scholarly journals On Maximum of Energy-Efficiency in Amplify-and-Forward Relay Networks Under Channel Estimation Errors

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 149641-149648
Author(s):  
Mengmeng Xu ◽  
Fei Liu ◽  
Hengzhou Xu ◽  
Hai Zhu ◽  
Baofeng Wang
Keyword(s):  
Energy Efficiency ◽  
Channel Estimation ◽  
Relay Networks ◽  
Amplify And Forward ◽  
Estimation Errors ◽  
Channel Estimation Errors

scholarly journals Power Control Method for Energy Efficient Buffer-Aided Relay Systems

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3234
Author(s):  
Jingon Joung ◽  
Han Lim Lee ◽  
Jian Zhao ◽  
Xin Kang
Keyword(s):  
Energy Efficiency ◽  
Power Control ◽  
Control Method ◽  
Relay Node ◽  
Destination Node ◽  
Transmit Power ◽  
Channel Condition ◽  
Relay Systems ◽  
Fixed Power ◽  
Fitting Model

In this paper, a power control method is proposed for a buffer-aided relay node (RN) to enhance the energy efficiency of the RN system. By virtue of a buffer, the RN can reserve the data at the buffer when the the channel gain between an RN and a destination node (DN) is weaker than that between SN and RN. The RN then opportunistically forward the reserved data in the buffer according to channel condition between the RN and the DN. By exploiting the buffer, RN reduces transmit power when it reduces the transmit data rate and reserve the data in the buffer. Therefore, without any total throughput reduction, the power consumption of RN can be reduced, resulting in the energy efficiency (EE) improvement of the RN system. Furthermore, for the power control, we devise a simple power control method based on a two-dimensional surface fitting model of an optimal transmit power of RN. The proposed RN power control method is readily and locally implementable at the RN, and it can significantly improve EE of the RN compared to the fixed power control method and the spectral efficiency based method as verified by the rigorous numerical results.

scholarly journals The Exploration of Network Coding in IEEE 802.15.4 Networks

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Deze Zeng ◽  
Song Guo ◽  
Victor Leung ◽  
Jiankun Hu
Keyword(s):  
Energy Efficiency ◽  
Network Coding ◽  
Ieee 802.15.4 ◽  
Low Complexity ◽  
Personal Area Networks ◽  
Wireless Personal Area Networks ◽  
Home Office ◽  
Improve Energy Efficiency ◽  
Energy Constrained ◽  
Time Critical

Wireless personal area networks (WPANs) are getting popular in a variety of fields such as smart home, office automation, and e-healthcare. In WPANs, most devices are considerably energy constrained, so the communication protocol should be energy efficient. The IEEE 802.15.4 is designed as a standard protocol for low power, low data rate, low complexity, and short range connections in WPANs. The standard supports allocating several numbers of collision-free guarantee time slots (GTSs) within a superframe for some time-critical transmissions. Recently, COPE was proposed as a promising network coding architecture to essentially improve the throughput of wireless networks. In this paper, we exploit the network coding technique at coordinators to improve energy efficiency of the WPAN. Some related practical issues, such as GTS allocation and multicast, are also discussed in order to exploit the network coding opportunities efficiently. Since the coding opportunities are mostly exploited, our proposal achieves both higher energy efficiency and throughput performance than the original IEEE 802.15.4.

scholarly journals Precoding Design for Energy Efficiency Maximization in MIMO Half-Duplex Wireless Sensor Networks with SWIPT

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4923 ◽  
Author(s):  
Liang Xue ◽  
Jin-Long Wang ◽  
Jie Li ◽  
Yan-Long Wang ◽  
Xin-Ping Guan
Keyword(s):  
Energy Efficiency ◽  
Wireless Sensor Networks ◽  
Energy Harvesting ◽  
Sensor Node ◽  
Optimization Problem ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Maximization Problem ◽  
Half Duplex ◽  
Energy Constrained

This paper explores the energy efficiency (EE) maximization problem in single-hop multiple-input multiple-output (MIMO) half-duplex wireless sensor networks (WSNs) with simultaneous wireless information and power transfer (SWIPT). Such an energy efficiency maximization problem is considered in two different scenarios, in which the number of energy-harvesting (EH) sensor nodes are different. In the scenario where the single energy-harvesting sensor node is applied, the modeled network consists of two multiple-antenna transceivers, of which the energy-constrained energy-harvesting sensor node harvests energy from the signals transmitted from the source by a power splitting (PS) scheme. In the scenario of multiple EH sensor nodes, K energy-constrained sensor nodes are applied and the same quantity of antennas are equiped on each of them. The optimization problem is formulated to maximize the energy efficiency by jointly designing the transceivers’ precoding matrices and the PS factor of the energy-harvesting sensor node. The considered constraints are the required harvested energy, the transmission power limit and the requirement on the data rate. The joint design of the precoding matrices and the PS factor can be formulated as an optimization problem, which can be transformed into two sub-problems. An alternating algorithm based on Dinkelbach is proposed to solve the two sub-problems. The convergence of the proposed alternating algorithm, the solution optimality and the computational complexity are analyzed in the paper. Simulation results demonstrate the convergence and effectiveness of our proposed algorithm for realizing the maximum energy efficiency.

scholarly journals Energy Efficiency-Oriented Resource Allocation for Massive MIMO Systems with Separated Channel Estimation and Feedback

Electronics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 582
Author(s):  
Feng Hu ◽  
Kaiyue Wang ◽  
Shufeng Li ◽  
Libiao Jin
Keyword(s):  
Resource Allocation ◽  
Energy Efficiency ◽  
Channel Estimation ◽  
Massive Mimo ◽  
Mimo Systems ◽  
Optimal Solution ◽  
Optimization Procedure ◽  
Spatial Separation ◽  
Low Complexity ◽  
Maximization Problem

This paper proposes a dynamic resource allocation scheme to maximize the energy efficiency (EE) for Massive MIMO Systems. The imperfect channel estimation (CE) and feedback are explicitly considered in the EE maximization problem, which aim to optimize the power allocation, the antenna subset selection for transmission, and the pilot assignment. Assuming CE error to be bounded for the complex-constrained Cramer–Rao Bound (CRB), theoretical results show that the lower bound is directly proportional to its number of unconstrained parameters. Utilizing this perspective, a separated and bi-directional estimation is developed to achieve both low CRB and low complexity by exploiting channel and noise spatial separation. Exploiting global optimization procedure, the optimal resource allocation can be transformed into a standard convex optimization problem. This allows us to derive an efficient iterative algorithm for obtaining the optimal solution. Numerical results are provided to demonstrate that the outperformance of the proposed algorithms are superior to existing schemes.

Transmit Power Optimization for Amplify-and-Forward Relay Networks With Reduced Overheads

2016 ◽  
Vol 65 (7) ◽  
pp. 5033-5044 ◽  
Author(s):  
Shiwei Huang ◽  
Jun Cai ◽  
Hongbin Chen ◽  
Hong Zhang
Keyword(s):  
Power Optimization ◽  
Relay Networks ◽  
Amplify And Forward ◽  
Transmit Power
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