scholarly journals Improving Performance of Far Users in Cognitive Radio: Exploiting NOMA and Wireless Power Transfer

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2206 ◽  
Author(s):  
Minh-Sang Van Nguyen ◽  
Dinh-Thuan Do ◽  
Miroslav Voznak
Keyword(s):  
Cognitive Radio ◽  
Energy Harvesting ◽  
Power Allocation ◽  
Signal To Noise Ratio ◽  
Selection Strategy ◽  
Amplify And Forward ◽  
Outage Performance ◽  
Main Observation ◽  
Relaying Systems ◽  
Single Relay

In this paper, we examine non-orthogonal multiple access (NOMA) and relay selection strategy to benefit extra advantage from traditional cognitive radio (CR) relaying systems. The most important requirement to prolong lifetime of such network is employing energy harvesting in the relay to address network with limited power constraint. In particular, we study such energy harvesting CR-NOMA using amplify-and-forward (AF) scheme to improve performance far NOMA users. To further address such problem, two schemes are investigated in term of number of selected relays. To further examine system performance, the outage performance needs to be studied for such wireless powered CR-NOMA network over Rayleigh channels. The accurate expressions for the outage probability are derived to perform outage comparison of primary network and secondary network. The analytical results show clearly that position of these nodes, transmit signal to noise ratio (SNR) and power allocation coefficients result in varying outage performance. As main observation, performance gap between primary and secondary destination is decided by both power allocation factors and selection mode of single relay or multiple relays. Numerical studies were conducted to verify our derivations.

scholarly journals Amplify-forward and decode-forward: a novel power allocation technique for MIMO cognitive radio network

2018 ◽  
Vol 7 (3.3) ◽  
pp. 670
Author(s):  
M Monisha ◽  
M Meena ◽  
C Sharanya ◽  
T Jaya
Keyword(s):  
Cognitive Radio ◽  
Power Allocation ◽  
Communication Channel ◽  
Signal To Noise Ratio ◽  
Input Power ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Radio System ◽  
Wireless Medium ◽  
Efficient Power

Nowadays transmitting data through wireless communication channel requires more power than the wired communication channel. In other words any communication through wireless medium will consume more power. Since power is a limited source, it is hard to conserve it or reduce its usage and this leads to the concept of “Efficient power allocation scheme for MIMO (Multi Input Multi Output) cognitive radio” system. The proposed system uses two algorithms namely On/Off Based Scheduling (OOBS) and Selective Based Scheduling (SBS) in Amplify and Forward (AAF) and Decode and Forward (DAF) techniques. OOBS algorithm is used for efficient allocation of the input power to each user’s Signal to Noise Ratio (SNR) value. The proposed algorithm provides better power utilization with low bit error rate (9.53×10-7).  

scholarly journals Power Optimized Single Relay Selection with an Improved Link-Adaptive-Regenerative Protocol

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Jie Li ◽  
Jianrong Bao ◽  
Shenji Luan ◽  
Bin Jiang ◽  
Chao Liu
Keyword(s):  
Outage Probability ◽  
Cooperative Communications ◽  
Power Efficiency ◽  
Relay Selection ◽  
Relay Node ◽  
Link Quality ◽  
Selection Strategy ◽  
Amplify And Forward ◽  
Selection Scheme ◽  
Single Relay

To improve the reliability and efficiency in cooperative communications, a power optimized single relay selection scheme is proposed by increasing the diversity effort with an improved link-adaptive-regenerative (ILAR) protocol. The protocol determines the forwarding power of a relay node by comparing the signal-to-noise ratio (SNR) at both sides of the node; thus it improves the power efficiency. Moreover, it also proposes a single relay selection strategy to maximize the instantaneous SNR product, which ensures the approximate best channel link quality for good relay forwarding. And the system adjusts the forwarding power in real time and also selects the best relay node participated in the cooperative forwarding. In addition, the cooperation in the protocol is analyzed and the approximate expression of the bit-error-rate (BER) and the outage probability at high SNRs are also derived. Simulation results indicate that the BER and outage probability of the relay selection scheme by the ILAR protocol outperform other contrast schemes of current existing protocols. At BER of 10−2, the proposed scheme with ILAR protocol outperforms those of the decoded-and-forward (DF), the selected DF (SDF), and the amplify-and-forward (AF) protocols by 3.5, 3.5 and 7 dB, respectively. Moreover, the outage probability of the relay system decreases with the growth of the relay number. Therefore, the proposed relay selection scheme with ILAR strategies can be properly used in cooperative communications for good reliability and high power efficiency.

scholarly journals On Performance Analysis of Underlay Cognitive Radio-Aware Hybrid OMA/NOMA Networks with Imperfect CSI

Electronics ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 819 ◽  
Author(s):  
Dinh-Thuan Do ◽  
Anh-Tu Le ◽  
and Byung Moo Lee
Keyword(s):  
Cognitive Radio ◽  
Outage Probability ◽  
Power Allocation ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Primary Source ◽  
Primary Network ◽  
Secondary Network ◽  
Target Rates ◽  
Allocation Factor

This study considers the outage and throughput performance of downlink in the secondary network of cognitive radio assisted non-orthogonal multiple access (NOMA) systems. Both orthogonal multiple access (OMA) mode and NOMA mode are investigated with respect to status of decoding operation of each user. Depending on the transmit signal-to-noise ratio (SNR) at the primary source and interference constraint from the primary network, the closed-form expressions of the outage probability for two users are obtained and compared in terms of performance. To obtain further insights, an asymptotic analysis of the outage probability in the high SNR regime is presented. Optimal throughput also provides insight in the computation of the power allocation factor. Furthermore, power allocation factor, target rates, and transmit SNR are evaluated to obtain reasonable outage performance. Monte Carlo simulations are conducted to confirm the analytical results.

scholarly journals Application of NOMA in Wireless System with Wireless Power Transfer Scheme: Outage and Ergodic Capacity Performance Analysis

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3501 ◽  
Author(s):  
Dinh-Thuan Do ◽  
Chi-Bao Le
Keyword(s):  
Energy Harvesting ◽  
Transmission Rate ◽  
Signal To Noise Ratio ◽  
Ergodic Capacity ◽  
Power Splitting ◽  
Amplify And Forward ◽  
Transfer Scheme ◽  
Power Switching ◽  
The Right ◽  
Capacity Performance

Non-orthogonal multiple access (NOMA) and energy harvesting (EH) are combined to introduce a dual-hop wireless sensor system. In particular, this paper considers a novel EH protocol based on time power switching-based relaying (TPSR) architecture for amplify-and-forward (AF) mode. We introduce a novel system model presenting wireless network with impacts of energy harvesting fractions and derive analytical expressions for outage probability and ergodic rate for the information transmission link. It confirmed that the right selection of power allocation for NOMA users can be performed to obtain optimal outage and ergodic capacity performance. Theoretical results show that, in comparison with the conventional solutions, the proposed model can achieve acceptable outage performance for sufficiently small threshold signal to noise ratio (SNR) with condition of controlling time switching fractions and power splitting fractions appropriately in considered TPSR protocol. We also examine the impacts of transmitting power at source, transmission rate, the other key parameters of TPSR to outage, and ergodic performance. Simulation results are presented to corroborate the proposed system.

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