Relay selection scheme for amplify-and-forward cooperative communication system with artificial noise

In this chapter, we discuss single and double-differential coding for a two-user cooperative communication system. The single-differential coding is important for the cooperative systems as the data at the destination/relaying node can be decoded without knowing the channel gains. The double-differential modulation is useful as it avoids the need of estimating the channel and carrier offsets for the decoding of the data. We explain single-differential coding for a cooperative system with one relay utilizing orthogonal transmissions with respect to the source. Next, we explain two single-differential relaying strategies: active user strategy (AUS) and passive users relaying strategy (PURS), which could be used by the base-station to transmit data of two users over downlink channels in the two-user cooperative communication network with decode-and-forward protocol. The AUS and PURS follow an improved time schedule in order to increase the data rate. A probability of error based approach is also discussed, which can be used to reduce the erroneous relaying of data by the regenerative relay. In addition, we also discuss how to implement double-differential (DD) modulation for decode-and-forward and amplify-and-forward based cooperative communication system with single source-destination pair and a single relay. The DD based systems work very well in the presence of random carrier offsets without any channel and carrier offset knowledge at the receivers, where the single differential cooperative scheme breaks down. It is further shown that optimized power distributions can be used to improve the performance of the DD system.

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On the Performance of Amplify-and-Forward Cooperative Diversity with the Nth Best-Relay Selection Scheme

10.1109/icc.2009.5199262 ◽

2009 ◽

Cited By ~ 28

Author(s):

S. S. Ikki ◽

M. H. Ahmed

Keyword(s):

Relay Selection ◽

Cooperative Diversity ◽

Amplify And Forward ◽

Selection Scheme ◽

Best Relay Selection

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

Journal of Electrical and Computer Engineering ◽

10.1155/2018/8364594 ◽

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.

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