scholarly journals Joint user grouping and time allocation for NOMA with wireless power transfer

2021 ◽  
Author(s):  
Mehak Basharat
Keyword(s):  
Energy Harvesting ◽  
Power Allocation ◽  
Time Allocation ◽  
Data Rate ◽  
Time Sharing ◽  
Wireless Power ◽  
5G Networks ◽  
User Grouping ◽  
Promising Solution ◽  
Information Transfers

Non-Orthogonal Multiple Access (NOMA) has recently been explored to address the challenges in 5G networks such as spectral efficiency, large number of devices, etc. Further, energy harvesting is a promising solution to address the challenges for energy efficiency in 5G networks. In this thesis, joint user grouping, power allocation, and time allocation for NOMA with RF energy harvesting is investigated. We mathematically modeled a framework to optimize user grouping, power allocation, and time allocation for energy harvesting and information transfers. The objective is to maximize data rate while satisfying the constraints on minimum data rate requirement of each user and transmit power. We adopted mesh adaptive direct search (MADS) algorithm to solve the formulated problem. The user grouping in MADS is comparable with the exhaustive search which is computationally very complex. The thesis is supported with simulation results in terms of user grouping, power allocation, user rate, and time sharing.

scholarly journals Joint user grouping and time allocation for NOMA with wireless power transfer

2021 ◽  
Author(s):  
Mehak Basharat
Keyword(s):  
Energy Harvesting ◽  
Power Allocation ◽  
Time Allocation ◽  
Data Rate ◽  
Time Sharing ◽  
Wireless Power ◽  
5G Networks ◽  
User Grouping ◽  
Promising Solution ◽  
Information Transfers

Non-Orthogonal Multiple Access (NOMA) has recently been explored to address the challenges in 5G networks such as spectral efficiency, large number of devices, etc. Further, energy harvesting is a promising solution to address the challenges for energy efficiency in 5G networks. In this thesis, joint user grouping, power allocation, and time allocation for NOMA with RF energy harvesting is investigated. We mathematically modeled a framework to optimize user grouping, power allocation, and time allocation for energy harvesting and information transfers. The objective is to maximize data rate while satisfying the constraints on minimum data rate requirement of each user and transmit power. We adopted mesh adaptive direct search (MADS) algorithm to solve the formulated problem. The user grouping in MADS is comparable with the exhaustive search which is computationally very complex. The thesis is supported with simulation results in terms of user grouping, power allocation, user rate, and time sharing.

scholarly journals Secrecy Performance Maximization for Underlay CR Networks with an Energy Harvesting Jammer

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8198
Author(s):  
Juan Sun ◽  
Shubin Zhang ◽  
Kaikai Chi
Keyword(s):  
Energy Harvesting ◽  
Power Allocation ◽  
Time Allocation ◽  
Information Transfer ◽  
Optimization Problems ◽  
Optimal Time ◽  
Secrecy Rate ◽  
Transmit Power ◽  
Rf Energy Harvesting ◽  
Rf Energy

This paper investigates the secrecy communication in an underlay cognitive radio (CR) networks with one primary user (PU) as well as multiple PUs, where the radio frequency (RF) energy-harvesting secondary user (SU) transmits the confidential information to the destination in the presence of a potential eavesdropper. We introduce a RF energy-harvesting secondary jammer (SJ) to secure the SU transmissions. The system works in time slots, where each time slot is divided into the energy transfer (ET) phase and the information transfer (IT) phase. In ET phase, the SU and SJ capture energy from the PU transmissions; in the IT phase, the SU uses the harvested energy to transmit information to the destination without causing the harmful interference to the PU transmissions, while the SJ utilizes the captured energy to generate jamming signals to the eavesdropper to secure the SU transmissions. We aim to maximize the secrecy rate for SU transmissionsby jointly optimizing the time allocation between ET phase and IT phase and the transmit power allocation at the SU and SJ. We first formulate the secrecy rate maximization as non-convex optimization problems. Then, we propose efficient nested form algorithms for the non-convex problems. In the outer layer, we obtain the optimal time allocation by the one dimension search method. In the inner layer, we obtain the optimal transmit power allocation by the DC programming, where the Lagrange duality method is employed to solve the convex approximation problem. Simulation results verify that the proposed schemes essentially improve the secrecy rate of the secondary network as compared to the benchmark schemes.

scholarly journals Time and Power Allocation for Energy Efficiency Maximization in Wireless-Powered Full-Duplex Relay Systems

2019 ◽  
Vol 11 (10) ◽  
pp. 205
Author(s):  
Song ◽  
Ni ◽  
Han ◽  
Qin ◽  
Dong
Keyword(s):  
Energy Efficiency ◽  
Energy Harvesting ◽  
Power Allocation ◽  
Full Duplex ◽  
Optimal Time ◽  
Wireless Power ◽  
Time Switching ◽  
Relay Systems ◽  
Single Antenna ◽  
Wireless Power Supply

In this paper, we propose an optimal time and power allocation scheme in a wireless power supply full-duplex (FD) relay system, where we consider the number of relay antennas in the energy harvesting stage. At the same time, the energy efficiency optimization problem of the system is structured, where optimization issues related to time allocation factors and power allocation are established. For the FD dual-antenna and the FD single-antenna energy harvesting system, energy efficiency function is proven to be a concave function over the time-switch factor, and the optimal time-switching factor is theoretically obtained using the Lambert function. Then, according to the given value range of the optimal time switching factor, the optimal power distribution scheme is obtained by analyzing the derivative function of the system energy efficiency and using the properties of the Lambert function. The time-switching factor and transmission power are optimally selected at the wireless power supply FD relay. Results reveal that the performance of energy efficiency of the dual-antenna energy harvesting at the FD relay outperforms that of the single-antenna. Moreover, our results demonstrate that FD relay systems always substantially boost the energy efficiency compared with half-duplex (HD) relay systems.

scholarly journals Outage Performance Analysis of Cell-Center/Edge Users Under Two Policies of Energy Harvesting

2019 ◽  
Vol 25 (4) ◽  
pp. 75-80
Author(s):  
Dinh-Thuan Do ◽  
Anh-Tu Le ◽  
Chi-Bao Le ◽  
Si-Phu Le ◽  
Hong-Nhu Nguyen ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Power Allocation ◽  
Base Station ◽  
Wireless Power ◽  
Factors Affecting ◽  
Outage Performance ◽  
Numerical Result ◽  
Center Edge ◽  
Energy Signal ◽  
Better Than

In this paper, two energy harvesting policies deploying in cooperative non-orthogonal multiple access (NOMA) systems are considered. After period of wireless power transfer, the NOMA users including cell-edge and cell-center users simultaneously transmit the superposition coded symbols to the base station (BS). In the last time slot, the BS decodes to achieve its signal based on superposition coded symbol with corresponding power allocation factors. This paper provides exact expressions of outage probability in two schemes. Performance gap of two NOMA users can be raised by providing different power allocation factors. It is confirmed by numerical result. Distance and data rate are main factors affecting outage performance. Scheme I exhibit scenario where power beacon transmits energy signal to NOMA user while the BS feeds energy to NOMA user in Scheme II. It is shown that outage performance of Scheme I is better than that of Scheme II.

scholarly journals SWIPT in mMIMO system with non-linear energy-harvesting terminals: protocol design and performance optimization

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Kui Xu ◽  
Ming Zhang ◽  
Jie Liu ◽  
Nan Sha ◽  
Wei Xie ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Performance Optimization ◽  
Power Transmission ◽  
Base Station ◽  
Second Phase ◽  
Wireless Power ◽  
Half Duplex ◽  
Non Linear ◽  
Two Phases ◽  
And Performance

Abstract In this paper, we design the simultaneous wireless information and power transfer (SWIPT) protocol for massive multi-input multi-output (mMIMO) system with non-linear energy-harvesting (EH) terminals. In this system, the base station (BS) serves a set of uplink fixed half-duplex (HD) terminals with non-linear energy harvester. Considering the non-linearity of practical energy-harvesting circuits, we adopt the realistic non-linear EH model rather than the idealistic linear EH model. The proposed SWIPT protocol can be divided into two phases. The first phase is designed for terminals EH and downlink training. A beam domain energy beamforming method is employed for the wireless power transmission. In the second phase, the BS forms the two-layer receive beamformers for the reception of signals transmitted by terminals. In order to improve the spectral efficiency (SE) of the system, the BS transmit power- and time-switching ratios are optimized. Simulation results show the superiority of the proposed beam-domain SWIPT protocol on SE performance compared with the conventional mMIMO SWIPT protocols.

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