Relay Selection of Cooperative Diversity Networks With Interference-Limited Destination

2013 ◽  
Vol 62 (9) ◽  
pp. 4658-4665 ◽  
Author(s):  
MinChul Ju ◽  
Kyu-Sung Hwang ◽  
Hyoung-Kyu Song
Author(s):  
L. Ge ◽  
G. J. Chen ◽  
J. A. Chambers

The implementation of cooperative diversity with relays has advantages over point-to-point multiple-input multiple-output (MIMO) systems, in particular, overcoming correlated paths due to small inter-element spacing. A simple transmitter with one antenna may exploit cooperative diversity or space time coding gain through distributed relays. In this paper, similar distributed transmission is considered with the golden code, and the authors propose a new strategy for relay selection, called the maximum-mean selection policy, for distributed transmission with the full maximum-likelihood (ML) decoding and sphere decoding (SD) based on a wireless relay network. This strategy performs a channel strength tradeoff at every relay node to select the best two relays for transmission. It improves on the established one-sided selection strategy of maximum-minimum policy. Simulation results comparing the bit error rate (BER) based on different detectors and a scheme without relay selection, with the maximum-minimum and maximum-mean selection schemes confirm the performance advantage of relay selection. The proposed strategy yields the best performance of the three methods.


Author(s):  
Maryleen U. Ndubuaku ◽  
Kennedy Chinedu Okafor ◽  
Chidiebele Chinwendu Udeze ◽  
Omar Salih

The growing demand for bandwidth and spectrum has inspired the ongoing efforts to establish the future 5G network supporting vertical sectors such as cyber-physical systems (CPS). Cooperative communication is one of the requisite techniques to improve coverage, network capacity and reduce power consumption in the network. In this paper, a symbiotic two-phase intelligent transmission is considered. The first phase occurs between the source and the candidate relays, and involves the selection of a set of “reliable relays”. The second phase occurs between the reliable relays and the destination, and involves the selection of the “best relay” for transmission. Dynamic relay selection using k-means clustering is used to detect the most significant correlation between all the channel state information (CSI) attributes in the system. The work identified the reliable relays while reducing the number of relay nodes for the second transmission phase. Contextual scenarios are created with typical network configuration using three geographical locations Coventry, Birmingham and London. An experimental validation is done with Omnet++ environment for the scenarios of three geographical locations. A natural grouping of mobile users is carried out leveraging the relay capabilities. The results are validated using support vector machine (SVM) classification algorithm. Considering urban environment deployment of relay nodes, metrics such as signal-to-noise-plus-interference ratio (SINR), attenuation, signal to noise ratio (SNR), link quality, k-means clustering, accuracy, and root mean square error (RMSE) are investigated for the Direct-2-Direct (D2D) capable relays. It was observed that the proposed technique both outperforms the other fixed-parameter relay selection techniques and improves with larger datasets unlike the other techniques.


Author(s):  
Essam Saleh Altubaishi

<span>Relay selection strategy under maximum-signal-to-noise ratio (MAX-SNR) criterion was proven to maximize performance but at the expense of losing fairness among the cooperative relays. In this work, the effect of controlling the MAX-SNR criterion on the spectral efficiency of cooperative wireless communication system with adaptive modulation is investigated. Specifically, the probability density function (PDF) of the end-to-end SNR for the considered system is derived when the controlled selection criterion is considered. Base on that PDF, the average spectral efficiency is then derived and investigated. The results show how the spectral efficiency of the system deteriorates as controlling the selection of a relay. Furthermore, the results of Monte Carlo simulation validate the derived expression.</span>


2020 ◽  
Author(s):  
Wei Jiang

Single-relay selection is a simple but efficient scheme for cooperative diversity among multiple user devices. However, the wrong selection of the best relay due to aged channel state information (CSI) remarkably degrades its performance, overwhelming this cooperative gain. Multi-relay selection is robust against channel aging but multiple timing offset (MTO) and multiple carrier frequency offset (MCFO) among spatially-distributed relays hinder its implementation in practical systems. In this paper, therefore, we propose a deep learning-based cooperative diversity method coined predictive relay selection (PRS) that chooses a single relay with the largest predicted CSI, which can alleviate the effect of channel aging while avoiding MTO and MCFO. Performance is evaluated analytically and numerically, revealing that PRS clearly outperforms the existing schemes with a negligible complexity burden.


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