scholarly journals Analysis of Packet Diversity in Buffer-Aided Relaying over Symmetric and Asymmetric Rayleigh Fading Channels

Symmetry ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 241 ◽  
Author(s):  
Hina Nasir ◽  
Nadeem Javaid ◽  
Waseem Raza ◽  
Muhammad Shafiq
Keyword(s):  
Outage Probability ◽  
Fading Channels ◽  
Relay Selection ◽  
Signal To Noise Ratio ◽  
Packet Delay ◽  
Cooperative Relaying ◽  
Link Quality ◽  
Relay Channel ◽  
Amplify And Forward ◽  
Active Channels

In this paper, we propose innovative schemes for relay selection that jointly explore packet selection and relay selection for buffer-aided amplify and forward (AF) cooperative relaying networks. The first proposed scheme chooses the most suitable channel based on link quality from all active channels, i.e., channels with neither empty nor full corresponding buffers. In the second proposed scheme, the most suitable channel is chosen based on buffer status. When the source-relay channel is determined, the corresponding relay collects data in the buffer. Likewise, when the relay-destination channel is picked, the most suitable packet is dispatched from the buffer. The most suitable packet is one that provides the highest end-to-end equivalent signal-to-noise ratio. We simulated the outage probability, average throughput and packet delay and analyzed the proposed protocol for both symmetric and asymmetric channel conditions. Comparison is made against the existing buffer-aided schemes. The results show that the proposed relay and packet selection systems help to reduce the outage probability, diversity gain and delay.

scholarly journals Outage probability analysis for hybrid TSR-PSR based SWIPT systems over log-normal fading channels

2021 ◽  
Vol 11 (5) ◽  
pp. 4233
Author(s):  
Hoang Thien Van ◽  
Hoang-Phuong Van ◽  
Danh Hong Le ◽  
Ma Quoc Phu ◽  
Hoang-Sy Nguyen
Keyword(s):  
Outage Probability ◽  
Fading Channels ◽  
System Performance ◽  
Signal To Noise Ratio ◽  
Cooperative Relaying ◽  
Power Splitting ◽  
Amplify And Forward ◽  
Time Switching ◽  
Log Normal ◽  
The Impact

Employing simultaneous information and power transfer (SWIPT) technology in cooperative relaying networks has drawn considerable attention from the research community. We can find several studies that focus on Rayleigh and Nakagami-m fading channels, which are used to model outdoor scenarios. Differing itself from several existing studies, this study is conducted in the context of indoor scenario modelled by log-normal fading channels. Specifically, we investigate a so-called hybrid time switching relaying (TSR)-power splitting relaying (PSR) protocol in an energy-constrained cooperative amplify-and-forward (AF) relaying network. We evaluate the system performance with outage probability (OP) by analytically expressing and simulating it with Monte Carlo method. The impact of power-splitting (PS), time-switching (TS) and signal-to-noise ratio (SNR) on the OP was as well investigated. Subsequently, the system performance of TSR, PSR and hybrid TSR-PSR schemes were compared. The simulation results are relatively accurate because they align well with the theory.

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 Partial Relay Selection for Secure Cooperative NOMA Networks

2021 ◽  
Author(s):  
Wided Hadj Alouane
Keyword(s):  
Fading Channels ◽  
Relay Selection ◽  
Signal To Noise Ratio ◽  
Secrecy Outage Probability ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Partial Relay Selection ◽  
Asymptotic Expressions ◽  
Selection For ◽  
Secrecy Outage

Abstract In this paper, we investigate physical layer security of multi-relay non-orthogonal multiple access (NOMA) networks with partial relay selection considering decode-and-forward (DF) and amplify-and-forward (AF) protocols. We propose a partial relay scheme aiming to select the best relay based on the highest signal-to-noise-ratio (SNR) of the first link. We derive new exact and asymptotic expressions for strictly positive secrecy capacity (SPSC) and secrecy outage probability (SOP) considering Rayleigh fading channels. Numerical results demonstrate that AF and DF provide almost a similar secrecy performance. Moreover, they prove that partial relay selection improves SPSC and reduces SOP when the relay-cluster is closer to the legitimate receiver.

Overview of Amplify-and-Forward Relaying

2010 ◽  
pp. 29-61
Author(s):  
Ioannis Krikidis ◽  
John S. Thompson
Keyword(s):  
Signal Processing ◽  
Mathematical Models ◽  
Outage Probability ◽  
Fading Channels ◽  
Relay Selection ◽  
Ad Hoc ◽  
Amplify And Forward ◽  
Cooperative Strategy ◽  
Block Fading Channels ◽  
Hoc Networks

Amplify-and-Forward (AF) is a simple cooperative strategy for ad-hoc networks with critical power constraints. It involves an amplification of the received signal in the analogue domain at the relays without further signal processing. This chapter gives an overview of the basic AF protocols in the literature and discuss recent research contributions in this area. Based on some well-defined AF-based cooperative configurations, it focuses on the behaviour of AF in block-fading channels, in power allocation problems, in relay selection, and in cross-layer coordination. Mathematical models and outage probability simulations are used in order to show the enhancements of the presented AF techniques.

Threshold-based hybrid relay selection and power allocation scheme

2016 ◽  
Vol 8 ◽  
pp. 16
Author(s):  
Xin Song ◽  
MingLei Zhang ◽  
WenMIn Liu ◽  
ShengBao Wang
Keyword(s):  
Outage Probability ◽  
Power Allocation ◽  
Relay Selection ◽  
Cooperative Relaying ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Opportunistic Relaying ◽  
Transmit Power ◽  
Probability Threshold ◽  
Relaying System

Abstract—To minimize total transmit power in a system while guaranteeing the outage probability at the same time in a cooperative system, we propose and analyse two threshold-based hybrid relay selection and power allocation schemes for a three-node cooperative relaying system. They are designated as: the hybrid amplify-direct-forward relaying (HADF) and incremental hybrid decode-direct-forward relaying (IHDDF) schemes. In the HADF scheme, a specific outage probability threshold is derived to determine that the system chooses to optimize power allocation of its source and relay in amplify-and-forward (AF) mode or optimize the power of its source in direct-transmit (DT) mode without a relay. In IHDDF, according to the outage probability threshold, the system chooses to optimize its power in turn with incremental decode-and-forward opportunistic relaying (IDFO) mode or DT mode. Closed-form expressions of the total transmit power of the proposed HADF and IHDDF schemes are derived. The proposed schemes have low computational complexity and system cost. Theoretical analysis and simulation results show that the HADF scheme outperforms the AF and DT schemes, and the total transmission power of the IHDDF scheme is reduced significantly compared with the IDFO and DT schemes. Compared with the HADF scheme, the IHDDF scheme has a better total transmit power in special channel condition.Keywords—power allocation, three-node cooperative relaying system, amplify-and-forward, incremental decode-and-forward opportunistic relaying.

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.

scholarly journals Analysis and Design of Functional Device for Vehicular Cloud Computing

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 583 ◽  
Author(s):  
Guilu Wu ◽  
Sha Li ◽  
Shujun Wang ◽  
Yutong Jiang ◽  
Zhengquan Li
Keyword(s):  
Outage Probability ◽  
Relay Selection ◽  
Vehicular Networks ◽  
Optimal Path ◽  
Transmission Efficiency ◽  
Link Quality ◽  
Technology Application ◽  
Analysis And Design ◽  
Vehicular Cloud ◽  
Transmission Link

Relay technology application becomes prevalent nowadays, as it can effectively extend the communication distance, especially for vehicular networks with a limited communication range. Combined with vehicular cloud (VC), transmission efficiency can be improved by offloading partial data. Hence, designing a vehicle relay algorithm and implementation embedded vehicle device is critical. In this paper, VC is considered to deal with the complexity computation in our proposed system model. Without a loss of generality, an end-to-end vehicle communication with one assisted vehicle is analyzed firstly on a transmission link based on VC. Here, the signal-to-noise ratio (SNR) on the receiving end and link outage probability is obtained to enhance the link reliability. The VC computing helps us further simplify computational complexity. Subsequently, an embedded vehicle-enabled device is designed to achieve the optimal path relay selection in realistic vehicular environments. In the functional device framework, we display an optimal path relay selection algorithm according to the link quality. Finally, the performance of the transmission link on the outage probability related with SNR is verified in the simulation results. Meanwhile, the effect of the relay gain is also analyzed. The application of a vehicle-enabled embedded device could improve the performance of vehicular networks.

scholarly journals Exact Performance Analysis of Amplify-and-Forward Bidirectional Relaying over Nakagami-m Fading Channels with Arbitrary Parameters

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1277
Author(s):  
Dong Qin ◽  
Yuhao Wang ◽  
Tianqing Zhou
Keyword(s):  
Fading Channels ◽  
Signal To Noise Ratio ◽  
Ergodic Capacity ◽  
Moment Generating Function ◽  
Amplify And Forward ◽  
Relay Systems ◽  
Signal Error ◽  
Bidirectional Relaying ◽  
Fading Parameter ◽  
The Moment

The exact performance of amplify-and-forward (AF) bidirectional relay systems is studied in generalized and versatile Nakagami-m fading channels, where the parameter m is an arbitrary positive number. We consider three relaying modes: two, three, and four time slot bidirectional relaying. Closed form expressions of the moment generating function (MGF), higher order moments of signal-to-noise ratio (SNR), ergodic capacity, and average signal error probability (SEP) are derived, which are different from previous works. The obtained expressions are very concise, easy to calculate, and evaluated instantaneously without a complex summation operation, in contrast to the nested multifold numerical integrals and truncated infinite series expansions used in previous work, which lead to computational inefficiency, especially when the fading parameter m increases. Simulation results corroborate the correctness and tightness of the theoretical analysis.

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