scholarly journals Performance Analysis of Hybrid Protocol Based AF EH Relaying over Asymmetric Fading Channels

Information ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 50 ◽  
Author(s):  
Xutao Sheng ◽  
Guangyue Lu ◽  
Liqin Shi ◽  
Yinghui Ye
Keyword(s):  
Fading Channels ◽  
Rayleigh Fading ◽  
Signal To Noise Ratio ◽  
System Capacity ◽  
Rician Fading ◽  
High Signal ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Energy Constrained ◽  
Selection Of

Simultaneous wireless information and power transfer is a practicable solution to encourage energy-constrained relay nodes to cooperate with the source to transmit information to the destination. In this paper, we study the outage performance of hybrid protocol based amplify-and-forward (AF) relay networks over asymmetric fading channels, where the source-relay link and the relay-destination link are subjected to Rician fading and Rayleigh fading, respectively. In particular, we derive the lower bound of outage probability and the upper bound of outage capacity based on a high signal-to-noise ratio approximation, respectively. We further investigate the effects of various system parameters, such as the parameters of hybrid protocol, the target rate, and the Rician K-factor, on the investigated network. It is shown that a good selection of parameters of hybrid protocol is of significance to improve system capacity, and that a larger Rician factor is desirable in the investigated network.

Cognitive Multi-Relay Transmission over Asymmetric Fading Channels with Imperfect CSI

2017 ◽  
Vol 3 (1) ◽  
pp. 46
Author(s):  
Nguyen Hong Giang ◽  
Vo Nguyen Quoc Bao ◽  
Hung Nguyen-Le
Keyword(s):  
Fading Channels ◽  
Rayleigh Fading ◽  
Signal To Noise Ratio ◽  
Rician Fading ◽  
Channel State ◽  
Relay System ◽  
Relay Systems ◽  
Secondary Network ◽  
Secondary Networks ◽  
Good Agreement

Outage performance of a cognitive multi-relay system using imperfect channel state information (CSI) of interfering links is formulated in this paper. In the considered cognitive system, it is assumed that wireless channels in the secondary network (source-to-relay and relay-to-destination links) experience Rician fading whereas interfering channels between primary and secondary networks undergo Rayleigh fading. Under the assumption of asymmetric fading, an outage probability (OP) expression of the secondary network is approximately formulated. Analytical OP values are in good agreement with related empirical ones in low signal-to-noise ratio (SNR) regimes. As a result, the approximate OP expression can be used to quantify the effect of asymmetric fading channels and CSI imperfection on the performance of cognitive multi-relay systems in practical SNR ranges.

scholarly journals Secrecy Performance Analysis of Half/Full Duplex AF/DF Relaying in NOMA Systems Over κ - μ Fading Channels

2021 ◽  
Author(s):  
Nesrine Zaghdoud ◽  
Adel Ben Mnaouer ◽  
Hatem Boujemaa ◽  
Farid Touati
Keyword(s):  
Fading Channels ◽  
Signal To Noise Ratio ◽  
Multipath Fading ◽  
Full Duplex ◽  
High Signal ◽  
Secrecy Outage Probability ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Special Cases ◽  
Secrecy Outage

Abstract Although the progress in understanding 5G and beyond techniques such as Non-Orthogonal Multiple Access (NOMA) and full-duplex techniques has been overwhelming, still analyzing the security aspects of such systems under different scenarios and settings is an important concern that needs further exploration. In particular, when considering fading in wiretap channels and scenarios, achieving secrecy has posed many challenges. In this context, we propose to study the physical layer security (PLS) of cooperative NOMA (C-NOMA) system using the general fading distribution κ - μ. This distribution facilitates mainly the effect of light-of-sight as well as multipath fading. It also includes multiple distributions as special cases like: Rayleigh, Rice, Nakagami-m which help to understand the comportment of C-NOMA systems under different fading parameters. The use of Half-Duplex and Full-Duplex communication is also investigated for both Amplify-and-forward (AF) and Decode-and-Forward (DF) relaying protocols. To characterize the secrecy performance of the proposed C-NOMA systems, closed form expressions of the Secrecy Outage Probability (SOP) and the Strictly Positive Secrcey Capacity (SPSC) metrics for the strong and weak users are given for high signal-to-noise ratio (SNR) due to the intractable nature of the exact expressions. Based on the analytical analysis, numerical and simulation results are given under different network parameters.

Performance Analysis for Hybrid Cooperative Beamforming in Wireless Relay Networks

2014 ◽  
Vol 543-547 ◽  
pp. 3435-3440
Author(s):  
Chun Lei Han ◽  
Mei Lu Lin ◽  
Ye Yang
Keyword(s):  
Fading Channels ◽  
Lower Bounds ◽  
Rayleigh Fading ◽  
Signal To Noise Ratio ◽  
Upper And Lower Bounds ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Average Channel Capacity ◽  
Wireless Relay ◽  
Cooperative Beamforming

This paper considers a relay-assisted hybrid cooperative beamforming system in independent and identically Rayleigh fading channels. In this system, each relay can adaptively employ amplify-and-forward (AF) or decode-and-forward (DF) protocol for maximizing the instantaneous signal-to-noise ratio (SNR). Tight upper and lower bounds for the outage probability have been derived in closed form, based on which we investigate the achievable diversity of the hybrid cooperative beamforming system. We also present the corresponding upper and lower bounds of the average channel capacity. Numerical results are provided to validate our theoretic analyses.

Performance Analysis of Multi-Hop Multi-Branch Amplify-and-Forward Cooperative Communication Over Rician Fading Channels

2019 ◽  
Vol 29 (09) ◽  
pp. 2050148
Author(s):  
Hadi Fathollahi ◽  
Mohammad H. Madani
Keyword(s):  
Fading Channels ◽  
Cooperative Communication ◽  
Channel Model ◽  
Asymptotic Expression ◽  
Signal To Noise Ratio ◽  
Moment Generating Function ◽  
Maximal Ratio Combining ◽  
Rician Fading ◽  
Amplify And Forward ◽  
Rician Fading Channels

Performance of multi-hop multi-branch amplify and forward (AF) cooperative communication over Rician fading channels is presented in this paper by a novel analysis method. Rician distribution is used to analyze the system because this channel model is useful in aerospace wireless communication channels. We derive an asymptotic expression for the statistics of the received signal-to-noise ratio (SNR) in the system under study with well-known moment-generating function (MGF)-based approach with maximal ratio combining (MRC) scheme. Moreover, for comparative analysis in different branches and hops, outage probability and symbol error ratio are derived. Finally, numerical simulation results are provided to confirm the theoretical results. These results are presented to illustrate the considerable performance improvement achieved by the increasing number of branches and hops.

scholarly journals Improved S-AF and S-DF Relaying Schemes using Machine Learning based Power Allocation over Cascaded Rayleigh Fading Channels

2020 ◽  
Author(s):  
Yahia Alghorani ◽  
samuel pierre
Keyword(s):  
Machine Learning ◽  
Power Allocation ◽  
Fading Channels ◽  
Rayleigh Fading ◽  
Channel Model ◽  
Machine Learning Algorithms ◽  
Rayleigh Fading Channels ◽  
High Signal ◽  
Approximate Analytic Solution ◽  
Amplify And Forward

<div>We investigate the performance of a dual-hop intervehicular</div><div>communications (IVC) system with relay selection</div><div>strategy. We assume a generalized fading channel model, known as cascaded Rayleigh (also called n*Rayleigh), which involves the product of n independent Rayleigh random variables. This channel model provides a realistic description of IVC, in contrast to the conventional Rayleigh fading assumption, which is more suitable for cellular networks. Unlike existing works, which mainly consider double-Rayleigh fading channels (i.e, n = 2); our system model considers the general cascading order n; for which we derive an approximate analytic solution for the outage probability under the considered scenario. Also, in this study we propose a machine learning-based power allocation</div><div>scheme to improve the link reliability in IVC. The analytical and simulation results show that both selective decode-and-forward (S-DF) and amplify-and-forward (S-AF) relaying schemes have the same diversity order in the high signal-to-noise ratio regime. In addition, our results indicate that machine learning algorithms can play a central role in selecting the best relay and allocation of transmission power.</div>

scholarly journals Analysis of Wireless Energy Harvesting Relay Throughput in Rician Channel

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yifan Hu ◽  
Ning Cao ◽  
Yunfei Chen
Keyword(s):  
Energy Harvesting ◽  
Fading Channels ◽  
Cooperative Communication ◽  
Rayleigh Fading ◽  
Rician Fading ◽  
Amplify And Forward ◽  
Performance Gains ◽  
Wireless Energy Harvesting ◽  
Analytical Expressions ◽  
Rician Fading Channels

Cooperative communication uses idle nodes to achieve performance gains. Energy harvesting allows cooperative communication to be less dependent on batteries. In this paper, the performance of energy harvesting (EH) amplify-and-forward relaying is analyzed for Rician fading channels, in contrast to previous works that focused on Rayleigh fading channels. Continuous time EH protocol and discrete time EH protocol are considered. Analytical expressions for the average throughput are derived. Numerical results are presented to show the good performance of the system in Rician fading channels by examining various system parameters using the analytical expressions.

scholarly journals I/Q Imbalance and Imperfect SIC on Two-Way Relay NOMA Systems

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 249 ◽  
Author(s):  
Xinji Tian ◽  
Qianqian Li ◽  
Xingwang Li ◽  
Hongxing Peng ◽  
Changsen Zhang ◽  
...  
Keyword(s):  
Outage Probability ◽  
Fading Channels ◽  
Interference Cancellation ◽  
Signal To Noise Ratio ◽  
High Reliability ◽  
System Throughput ◽  
Rician Fading ◽  
High Signal ◽  
Decode And Forward ◽  
Outage Performance

Non-orthogonal multiple access (NOMA) system can meet the demands of ultra-high data rate, ultra-low latency, ultra-high reliability and massive connectivity of user devices (UE). However, the performance of the NOMA system may be deteriorated by the hardware impairments. In this paper, the joint effects of in-phase and quadrature-phase imbalance (IQI) and imperfect successive interference cancellation (ipSIC) on the performance of two-way relay cooperative NOMA (TWR C-NOMA) networks over the Rician fading channels are studied, where two users exchange information via a decode-and-forward (DF) relay. In order to evaluate the performance of the considered network, analytical expressions for the outage probability of the two users, as well as the overall system throughput are derived. To obtain more insights, the asymptotic outage performance in the high signal-to-noise ratio (SNR) region and the diversity order are analysed and discussed. Throughout the paper, Monte Carlo simulations are provided to verify the accuracy of our analysis. The results show that IQI and ipSIC have significant deleterious effects on the outage performance. It is also demonstrated that the outage behaviours of the conventional OMA approach are worse than those of NOMA. In addition, it is found that residual interference signals (IS) can result in error floors for the outage probability and zero diversity orders. Finally, the system throughput can be limited by IQI and ipSIC, and the system throughput converges to a fixed constant in the high SNR region.

Dual-Hop Amplify-and-Forward Variable Gain Relaying over Mixture Gamma Fading Channels

2015 ◽  
Vol 719-720 ◽  
pp. 767-772
Author(s):  
Wei Jun Cheng
Keyword(s):  
Fading Channels ◽  
Signal To Noise Ratio ◽  
Symbol Error Rate ◽  
Amplify And Forward ◽  
Variable Gain ◽  
Average Symbol Error Rate ◽  
Simulation Results ◽  
End To End ◽  
The Moment ◽  
Relaying System

In this paper, we present the end-to-end performance of a dual-hop amplify-and-forward variablegain relaying system over Mixture Gamma distribution. Novel closed-form expressions for the probability density function and the moment-generation function of the end-to-end Signal-to-noise ratio (SNR) are derived. Moreover, the average symbol error rate, the average SNR and the average capacity are found based on the above new expressions, respectively. These expressions are more simple and accuracy than the previous ones obtained by using generalized-K (KG) distribution. Finally, numerical and simulation results are shown to verify the accuracy of the analytical results.

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