scholarly journals Performance Analysis of Output Threshold-Based Incremental Multiple-Relay Combining Scheme with Adaptive Modulation for Cooperative Networks

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Kyu-Sung Hwang ◽  
MinChul Ju
Keyword(s):  
Fading Channels ◽  
Error Rate ◽  
Spectral Efficiency ◽  
Signal To Noise Ratio ◽  
Adaptive Modulation ◽  
Moment Generating Function ◽  
Cooperative Networks ◽  
Cumulative Distribution ◽  
Amplify And Forward ◽  
Multiple Relay

In this paper, we propose an output threshold-based incremental multiple-relay combining scheme for cooperative amplify-and-forward relay networks with nonidentically distributed relay channels. Specifically, in order to achieve the required performance, we consider both conventional incremental relaying and multiple-relay selection where relays are adaptively selected based on a predetermined output threshold. Moreover, the adaptive modulation technique is adopted by our proposed scheme for satisfying both the spectral efficiency and the required error rate. For the proposed scheme, we first derive an upper bound of the output combined signal-to-noise ratio and then provide its statistics such as cumulative distribution function (CDF), probability density function (PDF), and moment generating function (MGF) over independent, nonidentically distributed Rayleigh fading channels. Additionally, we analyze the system performance in terms of average spectral efficiency, average bit error rate, outage probability, and system complexity. Finally, numerical examples show that our proposed scheme leads to a certain performance improvement in the cooperative networks.

scholarly journals Analysis of Amplify-and-Forward Cooperative Networks with Nakagami-m fading Channels For MRC Diversity Combining

2015 ◽  
Vol 16 (3) ◽  
pp. 546
Author(s):  
Ali Abdulwahhab Mohammed ◽  
Li Yu ◽  
Manar Al-Kali ◽  
Desheng Wang
Keyword(s):  
Density Function ◽  
Fading Channels ◽  
Moment Generating Function ◽  
Symbol Error Rate ◽  
Cooperative Networks ◽  
Diversity Combining ◽  
Amplify And Forward ◽  
Half Duplex ◽  
Shift Keying ◽  
Multiple Relay

In this paper we study the effect of diversity combining for Nakagami -m fading Channels in the amplify-and-forward cooperative networks.We derive the cumulative density function (CDF), probability density function (PDF) and moment generating function (MGF) for the multiple relay amplify-and-forward network with single half duplex channel maximal ratio combiner (MRC). In this network we investigate the cases of MRC at the destination, as well derive the exact Symbol Error Rate (SER) of M-ary phase-shift keying (M-PSK), and quadrature amplitude modulation (M-QAM) in Nakagami -m fading environment. We present a comparison between M-PSK and M-QAM modulation schemes in some representative scenarios where an arbitrary number of cooperative relays is considered.

scholarly journals On the Error Rate Analysis of Dual-Hop Amplify-and-Forward Relaying in Generalized-KFading Channels

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
George P. Efthymoglou ◽  
Nikolaos Bissias ◽  
Valentine A. Aalo
Keyword(s):  
Fading Channels ◽  
Error Rate ◽  
Signal To Noise Ratio ◽  
Geometric Mean ◽  
Moment Generating Function ◽  
Error Rates ◽  
Maximal Ratio Combining ◽  
Closed Form Expression ◽  
Amplify And Forward ◽  
Amplify And Forward Relaying

We present novel and easy-to-evaluate expressions for the error rate performance of cooperative dual-hop relaying with maximal ratio combining operating over independent generalized- fading channels. For this system, it is hard to obtain a closed-form expression for the moment generating function (MGF) of the end-to-end signal-to-noise ratio (SNR) at the destination, even for the case of a single dual-hop relay link. Therefore, we employ two different upper bound approximations for the output SNR, of which one is based on the minimum SNR of the two hops for each dual-hop relay link and the other is based on the geometric mean of the SNRs of the two hops. Lower bounds for the symbol and bit error rates for a variety of digital modulations can then be evaluated using the MGF-based approach. The final expressions are useful in the performance evaluation of amplify-and-forward relaying in a generalized composite radio environment.

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.

scholarly journals Performance Analysis of Relay Subset Selection for Amplify-and-Forward Cognitive Relay Networks

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Kiran Sultan ◽  
Ijaz Mansoor Qureshi ◽  
Aqdas Naveed Malik ◽  
Muhammad Zubair
Keyword(s):  
Fading Channels ◽  
Relay Selection ◽  
Subset Selection ◽  
Relay Networks ◽  
Cumulative Distribution ◽  
Amplify And Forward ◽  
Secondary Users ◽  
Coverage Area ◽  
Cognitive Relay Networks ◽  
Multiple Relay

Cooperative communication is regarded as a key technology in wireless networks, including cognitive radio networks (CRNs), which increases the diversity order of the signal to combat the unfavorable effects of the fading channels, by allowing distributed terminals to collaborate through sophisticated signal processing. Underlay CRNs have strict interference constraints towards the secondary users (SUs) active in the frequency band of the primary users (PUs), which limits their transmit power and their coverage area. Relay selection offers a potential solution to the challenges faced by underlay networks, by selecting either single best relay or a subset of potential relay set under different design requirements and assumptions. The best relay selection schemes proposed in the literature for amplify-and-forward (AF) based underlay cognitive relay networks have been very well studied in terms of outage probability (OP) and bit error rate (BER), which is deficient in multiple relay selection schemes. The novelty of this work is to study the outage behavior of multiple relay selection in the underlay CRN and derive the closed-form expressions for the OP and BER through cumulative distribution function (CDF) of the SNR received at the destination. The effectiveness of relay subset selection is shown through simulation results.

Dual-Hop Fixed Gain Relaying Transmissions with Semi-Blind in Asymmetric Multipath/Shadowing Fading Channels

2015 ◽  
Vol 9 (1) ◽  
pp. 82-90
Author(s):  
Weijun Cheng ◽  
Teng Chen
Keyword(s):  
Fading Channels ◽  
Cumulative Distribution Function ◽  
Signal To Noise Ratio ◽  
Ergodic Capacity ◽  
Moment Generating Function ◽  
Symbol Error Rate ◽  
Cumulative Distribution ◽  
Simulation Results ◽  
End To End ◽  
The Moment

In this paper, we investigate the end-to-end performance of a dual-hop fixed gain relaying system with semiblind relay under asymmetric fading environments. In such environments, the wireless links of the considered system undergo asymmetric multipath/shadowing fading conditions, where one link is subject to only the Nakagami-m fading, the other link is subject to the composite Nakagami-lognormal fading which is approximated by using mixture gamma fading model. First, the cumulative distribution function (CDF), the moment generating function (MGF) and the moments of the end-to-end signal-to-noise ratio (SNR) are derived under two asymmetric scenarios. Then, novel closed-form expressions of the outage probability, the average end-to-end SNR, the symbol error rate and the ergodic capacity for the dual-hop system are obtained based on the CDF and the MGF, respectively. Finally, some numerical and simulation results are shown and discussed to validate the accuracy of the analytical results under different scenarios, such as varying average SNR, fading parameters per hop, the choice of the semi-blind gain and the location of relaying nodes.

scholarly journals ADAPTIVE CODING TECHNIQUES TO IMPROVE BER IN OFDM SYSTEM

2013 ◽  
pp. 184-188
Author(s):  
RAJESHREE RAUT ◽  
PRITI SUBRAMANIUM ◽  
KAVITA BRAMAHANKAR
Keyword(s):  
Error Rate ◽  
Spectral Efficiency ◽  
Communication Systems ◽  
Signal To Noise Ratio ◽  
Adaptive Modulation ◽  
Future Generations ◽  
Wireless Communication Systems ◽  
Diversity Combining ◽  
Rate Performance ◽  
Ofdm System

Adaptive modulation and diversity combining represent very important adaptive solutions for the future generations of communication systems. In order to improve the performance and the efficiency of wireless communication systems these two techniques have been recently used jointly in new schemes named joint adaptive modulation and diversity combining .The highest spectral efficiency with the lowest possible combining complexity, given the fading channel conditions and the required error rate performance. Increase the spectral efficiency with a slight increase in the average number of combined path for the low signal to noise ratio (SNR) range while maintaining compliance with the bit error rate (BER).

Performance Analysis of Multi-Hop Multi-Branch Amplify-and-Forward Cooperative Communication Over Rician Fading Channels

2019 ◽  
Vol 29 (09) ◽  
pp. 2050148
Author(s):  
Hadi Fathollahi ◽  
Mohammad H. Madani
Keyword(s):  
Fading Channels ◽  
Cooperative Communication ◽  
Channel Model ◽  
Asymptotic Expression ◽  
Signal To Noise Ratio ◽  
Moment Generating Function ◽  
Maximal Ratio Combining ◽  
Rician Fading ◽  
Amplify And Forward ◽  
Rician Fading Channels

Performance of multi-hop multi-branch amplify and forward (AF) cooperative communication over Rician fading channels is presented in this paper by a novel analysis method. Rician distribution is used to analyze the system because this channel model is useful in aerospace wireless communication channels. We derive an asymptotic expression for the statistics of the received signal-to-noise ratio (SNR) in the system under study with well-known moment-generating function (MGF)-based approach with maximal ratio combining (MRC) scheme. Moreover, for comparative analysis in different branches and hops, outage probability and symbol error ratio are derived. Finally, numerical simulation results are provided to confirm the theoretical results. These results are presented to illustrate the considerable performance improvement achieved by the increasing number of branches and hops.

scholarly journals Performance Analysis of RIS-Assisted FSO Communications over Fisher–Snedecor F Turbulence Channels

2021 ◽  
Vol 11 (21) ◽  
pp. 10149
Author(s):  
Caslav Stefanovic ◽  
Máximo Morales-Céspedes ◽  
Ana García Armada
Keyword(s):  
Fading Channels ◽  
Direct Detection ◽  
Signal To Noise Ratio ◽  
Moment Generating Function ◽  
Cumulative Distribution ◽  
Model Parameters ◽  
Free Space Optical ◽  
F Distribution ◽  
The Moment ◽  
Analytical Expressions

The Fisher–Snedecor (F-S) F distribution has recently been introduced as a tractable turbulence-induced (TI) fading model that fits well with the experimental data. This paper provides a performance evaluation of a free-space optical (FSO) re-configurable intelligent surface (RIS)-assisted communications (ACs) link over the F-S F TI fading channels, assuming the intensity modulation–direct detection (IM–DD) technique. In particular, novel and closed-form (C-F) analytical expressions for the probability density function (PDF) and cumulative distribution function (CDF) of the end-to-end signal-to-noise ratio (SNR) in terms of Gaussian hyper-geometric functions are efficiently derived. Capitalizing on the obtained results, novel C-F analytical expressions for the moment generating function (MMGF), outage probability (OP), average bit error rate (BER) and ergodic channel capacity (Cγ) of the FSO RIS-ACs system over the F-S F TI fading channels are provided and numerically evaluated under the various TI fading severity conditions. Furthermore, the second-order (S-O) statistical expressions for the level crossing rate (LCR) and average fade duration (AFD) are obtained and thoroughly examined for various FSO RIS-ACs system model parameters.

scholarly journals Closed Form Solution for Outage and Average Bit Error Rate of Asymmetric Relaying System

2019 ◽  
Vol 8 (11) ◽  
pp. 3304-3310
Keyword(s):  
Closed Form ◽  
Fading Channels ◽  
Bit Error Rate ◽  
Error Rate ◽  
Signal To Noise Ratio ◽  
Closed Form Solution ◽  
Form Solution ◽  
Amplify And Forward ◽  
Severity Factor ◽  
Special Case

In this paper, closed form solution of outage and bit error rate (BER) is evaluated for the purpose of performance analysis of the amplify and forward relaying scheme under the asymmetric fading environment. In this dual hop system, we have used Rayleigh fading along source S to relay R and Mixture Gamma fading along relay R to destination D. First, we have derived closed form solution of outage and then we have used this derived expression for getting closed form solution of bit error rate (BER) for different kinds of modulation. Since Mixture Gamma fading channel represents many fading channels as its special case, so proposed closed form solution of outage and bit error rate may be used for analysis of outage and bit error rate under various fading scenarios. Specifically, in this paper, for analysis of outage and bit error rate (BER), we have taken Nakagami-m fading as a particular case of Mixture Gamma fading and analyzed the performance of proposed system after observing effect of fading severity factor and signal to noise ratio (SNR) on outage probability and bit error rate (BER)

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.

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