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Closed-form expressions for outage probability of decode-and-forward relaying over Nakagami-m fading channels

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The Journal of China Universities of Posts and Telecommunications 2010年第2期17卷 72-75页

作者： CHUAI Gang LI Xiu-xin LIU Sheng HU Yang SHI Fang-wen Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China School of Network Education Beijing University of Posts and Telecommunications Beijing 100876 China

In this article, an exact closed-form expression is derived for outage probability of decode-and-forward （DF） cooperative communications over independent identically distributed Nakagami-m fading channels. Simulation results verify that the theoretical expressions for the outage probability are correct. The optimal power allocation based on the derived outage probability is also studied.

关键词： decode-and-forward Nakagami-m fading ,outage probability optimal power allocation

Outage performance of OFDM-based selective decode-and-forward cooperative networks over Weibull fading channels

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High Technology Letters 2011年第3期17卷 285-289页

作者： Cai Chunxiao Yang Wendong Cai Yueming Institute of Communications Engineering PLA University of Science and Technology Nanjing 210007 P. R. China National Mobile Communications Research Laboratory Southeast University Nanjing 210096P. R. China

The outage performance of OFDM-based decode-and-forward cooperative networks is studied. The channels are modeled as independent Weibull distributed coefficients. A closed-form expression for the outage probability is obtained for three selective relaying schemes in the Weibull fading channels and a derived optimum power allocation method based on the closed form expressions of outage probability debases the outage probability. Monte Carlo simulations verify the analytical results.

关键词： OFDM cooperative communication Weibull fading channels decode-and-forward outage probability.

BER Modified decode-and-forward Protocol for OFDM-Based Linear Multihop Networks

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China Communications 2014年第11期11卷 34-43页

作者： MIAO Tingting WANG Ning YANG Hongwen YANG Dachcng Beijing University of Posts and TeLecommunications Beijing 100876 China

In orthogonal frequency division multiplexing （OFDM） based multihop communications, the conventional decodeand-forward （DF） relay scheme severely suffers from the error propagation problem. This drawback is serious in multihop networks as errors made by any relay node may fail the decoder at the destination in great chance. In this paper, we propose a bit error rate （BER） modified DF protocol （BMDF） which can be applied to systems where error correction channel coding and M-ary modulation are used. By modeling all links except the last one as a binary symmetric channel （BSC）, we derive a log likelihood ratio （LLR） modification function relying only on the accumulated BER of all previous links to be applied to the output of the soft demapper. Furthermore, to reduce the computational complexity and signaling overhead, the modification function is simplified from its original exponential expression and less BERs are delivered between nodes by making successive subcarriers share the same BER. In addition, for situations where the channel state information （CSI） of forward link is available, the proposed BMDF can be further enhanced by combining with subcarrier pairing （SP） and power allocation （PA）, where a sorted-channel gain SP scheme and a greedy PA algorithm are proposed. The simulation results verify thesignificant performance improvement to the conventional DF.

关键词： wireless multihop networks decode-and-forward BER modified decode-and-forward (BMDF) OFDM M-arymodulation subcarrier pairing (SP) powerallocation (PA)

Beamforming based decode-and-forward cooperation via backward synchronization

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Science China. Information Sciences 2012年第4期55卷 805页

作者： Li, YuBo Yin, QinYe Wang, Chen Xi’an Jiaotong University Ministry of Education Key Lab for Intelligent Networks and Network Security Xi’an China (GRID:grid.43169.39) (ISNI:***)

In this paper, a beamforming (BF) based cooperation scheme with decode-and-forward (DF) protocol is proposed and its performance analysis is provided. Firstly, to solve the issue of carrier synchronization in distributed networks, a backward synchronization (B-Sync) method is introduced, where participating relays synchronize to the reference carrier broadcast by the destination and make signals superimposed coherently at the destination without any phase feedback. Then, based on B-sync, a cooperation scheme with DF protocol is proposed to carry out BF forwarding among relays. The outage probability of this scheme is derived and analyzed, which shows that the full diversity order can be achieved by the proposed scheme. Furthermore, symbol error probability (SEP) analysis is presented to evaluate the practical performance. Simulation results validate the analysis, and show that the proposed scheme outperforms other existing ones in terms of outage probability and SEP.

关键词： cooperative diversity decode-and-forward distributed beamforming outage probability symbol error probability

Modified Cooperative Subchannel Allocation Algorithms and PSO Based Power Allocation for an Alamouti decode and forward Relaying Protocol in Multiuser OFDMA Systems

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Circuits and Systems 2016年第8期7卷 1769-1786页

作者： K. Shoukath Ali P. Sampath Department of ECE Bannari Amman Institute of Technology Sathyamangalam India

The present work is a discussion on the performance analysis of Modified Cooperative Subchannel Allocation (CSA) Algorithms which is used in Alamouti decoded and forward (Alamouti DF) Relaying Protocol for wireless multi-user Orthogonal Frequency Division Multiplexing Access (OFDMA) systems. In addition, the performance of approximate Symbol Error Rate (SER) for the Alamouti DF Relaying Protocol with the Cooperative Maximum Ratio Combining Technique (C-MRC) is analyzed and compared with SER upper bound. The approximate SER is asymptotically tight bound at higher Signal-to-Noise Ratio (SNR). From the asymptotic tight bound approximate SER, Particle Swarm Optimization (PSO) based Power Allocation (PA) is determined for the Alamouti DF Relaying Protocol. The simulation results suggested that the Modified Throughput based Subchannel Allocation Algorithm achieved an improved throughput of 6% to 33% compared to that of existing cooperative diversity protocol. Further, the Modified Fairness based Subchannel Allocation Algorithm rendered fairness of 7.2% to 17% among the multiuser against the existing cooperative diversity protocol.

关键词： Amplify-and-forward decode-and-forward Cooperative Relay Maximal Ratio Combining Symbol Error Rate

Power allocation for non-orthogonal decode-andforward cooperation protocol

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Science in China(Series F) 2009年第6期52卷 1037-1042页

作者： ZHANG Yong XU YouYun CAI YueMing Institute of Communications Engineering PLA University of Science and Technology Nanjing 210007 China

This paper studies the power allocation problem for the non-orthogonal decode-and-forward （NDF） cooperation protocol with selection *** the availability of the magnitudes of all channel gains at the source, the power allocation is explored that maximizes the mutual information between the source and destination subject to a total power *** minimum power that avoids the outage of the relay is set as a condition, under which the power allocation problem becomes one of selecting the optimal one from several allocation factor *** is shown that the power allocation scheme can provide considerable performance gain, and the non-orthogonal cooperation protocol is superior to the orthogonal protocol and direct transmission.

关键词： non-orthogonal decode-and-forward power allocation relaying

Throughput and BER of wireless powered DF relaying in Nakagami-m fading

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Science China(Information Sciences) 2017年第10期60卷 204-216页

作者： Yan GAO Yunfei CHEN Aiqun HU School of Electronic Information Nanjing College of Information Technology College of Computer and Information Hohai University College of Information Science and Engineering Southeast University

Energy harvesting provides a promising solution to the extra energy requirement at the relay due to relaying. In this paper, the throughput and bit error rate of a decode-and-forward relaying system are studied using power splitting wireless power. Three different transmission scenarios are considered: instantaneous transmission, delay-or error-constrained transmission and delay-or error-tolerant transmission. For each scenario,exact expressions for the throughput and bit error rate are derived. Numerical results show that, for instantaneous transmission, the optimum splitting factor is not sensitive to the channel gain of the source-to-relay *** delay-or error-constrained transmissions, the optimum splitting factor increases with the quality of the source-to-relay link and decreases with the quality of the relay-to-destination link. For delay-or error-tolerant transmissions, the optimum splitting factor is insensitive to the quality of the source-to-relay link.

关键词： decode-and-forward energy harvesting power-splitting relaying

Energy-efficient resource allocation for OFDMA relay systems with imperfect CSIT

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Science China(Information Sciences) 2015年第8期58卷 131-143页

作者： WANG XiaoMing ZHENG FuChun ZHU PengCheng MENG Chao YOU XiaoHu National Mobile Communications Research Laboratory Southeast University School of Systems Engineering University of Reading

In this paper, we propose an energy-efficient resource allocation scheme for the downlink of decodeand-forward relay-assisted orthogonal frequency division multiple access systems. The resource allocation is designed based on imperfect channel state information at the transmitter. We jointly optimize the power allocation, data rate allocation, and subcarrier allocation to maximize the system energy efficiency(EE). We formulate the EE problem as a probabilistic mixed non-convex optimization problem, in which the individual power constraints and the outage probability requirements are considered. An iterative algorithm based on bisection method is given to transform the optimization problem into a standard concave form. Also, we consider a proportional fairness design for the EE maximization problem. Simulation results illustrate the effectiveness of the proposed algorithm.

关键词： energy efficiency relay systems OFDMA decode-and-forward imperfect CSIT

Outage Probability Minimization for Low-Altitude UAV-Enabled Full-Duplex Mobile Relaying Systems

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China Communications 2018年第5期15卷 9-24页

作者： Meng Hua Yi Wang Zhengming Zhang Chunguo Li Yongming Huang Luxi Yang School of Information Science and Engineering Southeast UniversityNanjing 210096China National Digital Switching System Engineering and Technological Research Center Zhengzhou 450002China School of Electronics and Communication Engineering Zhengzhou University of AeronauticsZhengzhou 450046China

In this paper, a novel unmanned aerial vehicle(UAV)-enabled full duplex decode-and-forward(DF) technique is used in mobile relaying system. Compared with conventional static relaying, mobile relaying provides more degree of freedom for experiencing better channel conditions and further improving the system reliable performance. The source and relay transmit power as well as relay trajectory are jointly optimized for sum outage probability minimization in mobile relaying system. Due to the non-convex nature of the original problem, block coordinate decent optimization techniques are employed to decompose it into two sub-problems, which leads to an efficient iterative algorithm. Specifically, for the pre-determined relay trajectory, the optimal transmit power of source and relay are obtained by solving Karush-Kuhn-Tucker(KKT) conditions. For the given source/relay power allocation, the optimal UAV trajectory is obtained by solving dual problem. Based on the two steps, an iterative algorithm is proposed to jointly optimize source/relay power allocation and UAV trajectory alternately. Numerical results show the performance gain of our proposed scheme.

关键词： unmanned aerial vehicle decode-and-forward full-duplex power allocation trajectory optimization