scholarly journals Trust Degree-Based MISO Cooperative Communications with Two Relay Nodes

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Jong Yeol Ryu ◽  
Jung Hoon Lee
Keyword(s):  
Cooperative Communications ◽  
Relay Selection ◽  
Cooperative Transmission ◽  
Achievable Rate ◽  
Selection Strategy ◽  
Relay Nodes ◽  
Transmission Strategy ◽  
Single Output ◽  
Multiple Input ◽  
Channel Conditions

In this paper, we propose transmission strategies in multiple-input-single-output (MISO) cooperative communications with two relay nodes in cases when the relay nodes have different trust degrees, where the trust degrees represent how much the relay nodes can be trusted for cooperation. For the given trust degrees and channel conditions, we first derive a relay selection strategy that maximizes the expected achievable rate. We then propose a cooperative transmission strategy of relays with an optimal cooperative beamforming vector that maximizes the expected achievable rate, which is a linear combination of weighted channel vectors. Finally, we derive the optimal transmission strategy, which is a mixed strategy between the relay selection and cooperative transmission strategies with respect to the trust degrees. Our analysis and numerical results show that the proposed transmission strategies increase the expected achievable rate by exploiting the trust degrees of the relay nodes, along with the channel conditions.

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 Network-coded cooperative communications with multiple relay nodes: Achievable rate and network optimization

2016 ◽  
Vol 53 ◽  
pp. 79-93 ◽  
Author(s):  
Sushant Sharma ◽  
Yi Shi ◽  
Y. Thomas Hou ◽  
Sastry Kompella ◽  
Scott F. Midkiff
Keyword(s):  
Network Optimization ◽  
Cooperative Communications ◽  
Achievable Rate ◽  
Relay Nodes ◽  
Multiple Relay

scholarly journals Improved two-way double-relay selection technique for cooperative wireless communications

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Samer Alabed ◽  
Issam Maaz ◽  
Mohammad Al-Rabayah
Keyword(s):  
Relay Selection ◽  
Analytical Approximation ◽  
Selection Strategy ◽  
Relay Nodes ◽  
Space Time Coding ◽  
Current State ◽  
Three Phase ◽  
Coding Method ◽  
Novel Strategy ◽  
Ber Performance

AbstractIn this article, a novel two-way double-relay selection strategy with its bit error rate (BER) performance analysis is proposed. In this novel strategy, as a first step we choose two relays out of a set of relay-nodes in a way to maximize the system performance in terms of BER and complexity. In the second step, the selected relays apply orthogonal space-time coding scheme using the three-phase protocol to establish a two-way communication between the transceivers, which will lead to a significant improvement in the achievable diversity and coding gain with a very low decoding complexity by using a symbol-wise decoder. Furthermore, the performance of the overall system is further enhanced through the use of a network coding method at the selected relay-nodes. Moreover, this paper proposes the analytical approximation of the BER performance. As well, we show that the analytical results match perfectly the simulated ones. In addition, we prove that our strategy outperforms the current state-of-the-art ones by proposing a better cooperative communication system in terms of BER.

scholarly journals Characterization of Path-Loss Disparity in Virtual Multiple-Input-Single-Output Links

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Haejoon Jung ◽  
Mary Ann Weitnauer
Keyword(s):  
Antenna Array ◽  
Signal To Noise Ratio ◽  
Multiple Input Multiple Output ◽  
Path Loss ◽  
Spatial Diversity ◽  
Cooperative Transmission ◽  
Single Output ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Log Normal

Cooperative transmission (CT) is an effective technique to achieve spatial diversity in fading environments, where spatially separated wireless nodes collaborate to form a virtual antenna array or virtual multiple-input-multiple-output (VMISO) link. Many authors model the path loss of the VMISO link as though the elements in the virtual antenna array are colocated, even though they are spread out. In this paper, we show that the spreading causes a signal-to-noise-ratio (SNR) penalty of up to 3 dB. Moreover, in the high SNR regime, we show that the performance degradation caused by the path-loss disparity can be characterized equivalently by log-normal distribution. We use these two observations to propose a new CT link model, expressed in closed form as an outage probability based on the log-normal shadowing model. The quality of the model is evaluated by a statistical test based on Kolmogorov-Smirnov method.

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