Jointly Optimal Precoder and Power Allocation for an Amplify-and-Forward Half-Duplex Relay System

2011 ◽  
Vol 1 (1) ◽  
Author(s):  
Leonardo J. Rodríguez ◽  
Nghi H. Tran ◽  
Tho Le-Ngoc
Keyword(s):  
Power Allocation ◽  
Cooperative Diversity ◽  
Relay Node ◽  
Total Power ◽  
Asymptotic Performance ◽  
Amplify And Forward ◽  
Coding Gain ◽  
Half Duplex ◽  
Single Relay ◽  
System Power

This paper investigates the optimal precoder design and power allocation between the source and relay for a half-duplex single-relay non-orthogonal amplify-and-forward (NAF) system. Based on the pair-wise error probability (PEP) analysis, an optimal class of 2 × 2 precoders is first derived for the traditional power allocation scheme, where one-third of the system power is spent at the relay node, while two-thirds are spent at the source node. Different from optimal unitary precoders proposed earlier, the derived class of precoders indicates that the source should spend all its power transmitting a superposition of the symbols in the broadcast phase, while being silent in the cooperative phase, for optimal asymptotic performance. We then further address the problem of jointly optimal precoder and power allocation for the system under consideration. It is shown that the total power should be equally distributed to the source and the relay, and the source should again spend no power during the cooperative phase for the best asymptotic performance. Analytical and simulation results reveal that the proposed precoders not only exploit full cooperative diversity, but also provide significant coding gain over the optimal unitary precoders. For instance, a coding gain of around 1dB can be attained at the practical BER level of 10 − 5 for various modulation schemes.

scholarly journals Full-Duplex Mode in Amplify-and-Forward Relay Channels: Outage Probability and Ergodic Capacity

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Rongyi Hu ◽  
Chunjing Hu ◽  
Jiamo Jiang ◽  
Xinqian Xie ◽  
Lei Song
Keyword(s):  
Outage Probability ◽  
Relay Node ◽  
Ergodic Capacity ◽  
Full Duplex ◽  
Relay Channels ◽  
Amplify And Forward ◽  
Half Duplex ◽  
Single Relay ◽  
Close Form ◽  
Loop Interference

This paper investigates the outage probability and ergodic capacity performances for full-duplex mode in two-way amplify-and-forward relay channels. The two-way relay channels which consist of two source nodes and a single relay node working in full-duplex mode, are assumed as independent and identically distributed as Rayleigh fading. The self-interference or loop interference of the relay is unavoidably investigated for full-duplex mode. And the close-form expressions for the outage probability and ergodic capacity of full-duplex mode are derived, considering both loop interference and the coefficients of two-way relay amplify-and-forward channels. To further facilitate the performance of full-duplex mode, the half-duplex modes over different transmission time slots are analyzed. Simulation results point out the effect of loop interference on outage probability and ergodic capacity of two-way amplify-and-forward relay channels with full-duplex mode and show that full-duplex mode can achieve better performance in terms of capacity and even outperform half-duplex modes in the presence of loop interference.

Power Allocation and Relay Selection Algorithm in Multi-Relay Amplify-and-Forward Networks

2014 ◽  
Vol 513-517 ◽  
pp. 3423-3428
Author(s):  
Zhi Kang Zhou ◽  
Qi Zhu
Keyword(s):  
Power Allocation ◽  
Relay Selection ◽  
Relay Network ◽  
Total Power ◽  
Selection Algorithm ◽  
Amplify And Forward ◽  
Power Constraint ◽  
Lower Complexity ◽  
Relay Selection Algorithm ◽  
The Ideal

In this paper, an amplify-and-forward (AF) multi-relay network is considered. In order to minimize the system outage probability, a new power allocation and multi-relay selection algorithm is proposed under total power constraint and each node power constraint. In the proposed algorithm, the ideal of ordering is adopted, which leads to the remarkable decrease of the computation complexity together with simple power reallocation. Simulation results show that the proposed multi-relay selection algorithm performs close to the optimal scheme with optimal power allocation and exhaustive search (OPA-ES) but with much lower complexity.

scholarly journals Energy-Efficient Dual-Iteration Power Allocation for Two-Phase Relay System with Massive Antennas

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Long Zhao ◽  
Wei Xiang ◽  
Jie Mei ◽  
Hui Zhao ◽  
Hang Long ◽  
...  
Keyword(s):  
Power Allocation ◽  
Relay Node ◽  
Spectrum Efficiency ◽  
Amplify And Forward ◽  
Zero Forcing ◽  
Channel State ◽  
Relay System ◽  
Two Phase ◽  
Massive Antennas ◽  
Equal Power Allocation

This paper considers the scenario where multiple source nodes communicate with multiple destination nodes simultaneously with the aid of an amplify-and-forward relay equipped with massive antennas. In order to achieve optimal energy efficiency (EE) of the entire relay system, this paper investigates the power allocation problem for the multiple pairs of nodes at both the source nodes and the relay node, where the relay employs the backward and forward zero-forcing filters. Since the EE optimization problem cannot be solved analytically, we propose a two-phase power allocation method. Given power allocation of one phase, the optimal power allocation is derived for the other phase. Furthermore, two dual-iteration power allocation (DIPA) algorithms with performance approaching that of optimal EE are developed based on the instantaneous and statistic channel state information, respectively. Numerical results show that the proposed DIPA algorithms can greatly improve EE while guaranteeing spectrum efficiency (SE) when compared with the equal power allocation algorithm. Moreover, both algorithms suggest that deploying a rational number of antennas at the relay node and multiplexing a reasonable number of node pairs can improve on the EE and SE.

scholarly journals Outage Performance of Bidirectional Full-Duplex Amplify-and-Forward Relay Network with Transmit Antenna Selection and Maximal Ratio Combining

2018 ◽  
Vol 1 ◽  
pp. 62-69
Author(s):  
R. Rajesh ◽  
P. G. S. Velmurugan ◽  
S. J. Thiruvengadam ◽  
P. S. Mallick
Keyword(s):  
Antenna Selection ◽  
Relay Node ◽  
Maximal Ratio Combining ◽  
Full Duplex ◽  
Relay Network ◽  
Amplify And Forward ◽  
Transmit Antenna Selection ◽  
Outage Performance ◽  
Half Duplex ◽  
Af Relay

In this paper, a bidirectional full-duplex amplify- and-forward (AF) relay network with multiple antennas at source nodes is proposed. Assuming that the channel state information is known at the source nodes, transmit antenna selection and maximal ratio combining (MRC) are employed when source nodes transmit information to the relay node and receive information from the relay node respectively, in order to improve the overall signal-to-interference plus noise ratio (SINR). Analytical expressions are derived for tight upper bound SINR at the relay node and source nodes upon reception. Further, losed form expressions are also derived for end-to-end outage probability of the proposed bidirectional full-duplex AF relay network in the Nakagami-m fading channel environment. Although self-interference at the relay node limits the performance of the full-duplex network, the outage performance of the proposed network is better than that of conventional bidirectional full-duplex and half-duplex AF relay networks, due to the selection diversity gain in TAS and diversity and array gain in MRC.

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 Rate Maximization Using Cooperative Ratio Over Rayleigh Fading Channels

2021 ◽  
Author(s):  
Lavanya Rajagopalan
Keyword(s):  
Power Allocation ◽  
Fading Channels ◽  
Cooperative Diversity ◽  
Spatial Diversity ◽  
Cooperative Transmission ◽  
Total Power ◽  
Destination Node ◽  
Equal Distribution ◽  
Power Simulation ◽  
Diversity Transmission

Cooperative Diversity transmission, a newly upcoming field in the area of wireless communication, has been receiving great attention. This diversity transmission exploits the spatial diversity created by antenna sharing to improve the performance of a wireless network. The working of a cooperative diversity system is such that a source node communicates with a destination node with the help of another partner node. One important question usually raised regarding the operation of this system is that of the amount of power allocation among partnering nodes. Initial stages of research in this area had assumed equal distribution of power resources between the nodes. This approach has been proven as clearly suboptimal. Several works to allocate power optimally are coming up. In this project, optimal power allocation is used as a key approach to analyze the rate performance of the system. This is done with the help of a parameter called cooperative ratio which is the ratio of the power used for cooperative transmission to total power. Simulation results to support the analysis have also been provided.

scholarly journals Rate Maximization Using Cooperative Ratio Over Rayleigh Fading Channels

2021 ◽  
Author(s):  
Lavanya Rajagopalan
Keyword(s):  
Power Allocation ◽  
Fading Channels ◽  
Cooperative Diversity ◽  
Spatial Diversity ◽  
Cooperative Transmission ◽  
Total Power ◽  
Destination Node ◽  
Equal Distribution ◽  
Power Simulation ◽  
Diversity Transmission

Cooperative Diversity transmission, a newly upcoming field in the area of wireless communication, has been receiving great attention. This diversity transmission exploits the spatial diversity created by antenna sharing to improve the performance of a wireless network. The working of a cooperative diversity system is such that a source node communicates with a destination node with the help of another partner node. One important question usually raised regarding the operation of this system is that of the amount of power allocation among partnering nodes. Initial stages of research in this area had assumed equal distribution of power resources between the nodes. This approach has been proven as clearly suboptimal. Several works to allocate power optimally are coming up. In this project, optimal power allocation is used as a key approach to analyze the rate performance of the system. This is done with the help of a parameter called cooperative ratio which is the ratio of the power used for cooperative transmission to total power. Simulation results to support the analysis have also been provided.

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