共查询到20条相似文献,搜索用时 15 毫秒
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Liang Yang 《Wireless Communications and Mobile Computing》2008,8(10):1247-1253
In this paper, we present a comprehensive performance analysis for multiple‐input multiple‐output (MIMO) systems with multiuser diversity over Rayleigh fading channels. We derive exact closed‐form expressions of the outage probability and the average bit error rate (BER) for different MIMO schemes, including the selective combining (SC), maximum ratio combining (MRC) and space‐time block codes (STBC). We also provide the explicit upper bounds on the BER performance. Finally, the mathematical formalism is verified by numeric results that study the interaction between the antenna diversity and the multiuser diversity. It is observed that the system performance is deteriorated as the number of transmit antennas increases in multiuser scenario, which is unlike the case in single‐user systems. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Conditional error rate and combining schemes for hybrid automatic repeat request with M‐pulse amplitude modulation
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Hang Long Wei Xiang Jing Wang Yueying Zhang Yuanan Liu Wenbo Wang 《International Journal of Communication Systems》2014,27(10):1798-1813
In hybrid automatic repeat request (HARQ), maximum ratio combining (MRC) is usually employed at the receiver if the retransmitted signal is the same as that of the first transmission. However, it is proved that MRC is not the optimum combining scheme with binary phase shift keying modulation in terms of the conditional error rate. In this paper, the conditional error rate of HARQ with M‐pulse amplitude modulation (M‐PAM) and arbitrary combining schemes at the receiver is analyzed. Then, the optimum combining scheme with M‐PAM is proposed with the aim of minimizing the conditional error rate.Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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混合自动重传请求(HARQ)是一种保证可靠通信的差错控制方式。通过采用空分复用MIMO技术和HARQ机制,可以进行高速可靠的通信。该文提出了一种MIMO-HARQ系统中以低反馈量进行序贯功率分配的传输方法,接收机根据当前的信道信息,搜索下次HARQ重传使用的最优天线间功率分配矢量,并将其序号反馈给发射机,序贯地实现码流间的功率分配。这种方法不仅需要的反馈量少,而且对反馈延迟的要求也很低。仿真分析表明,该方法可以显著提高系统在空间相关信道下的误码性能。 相似文献
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This article investigates the performance of hybrid automatic repeat request (HARQ) with code combining over the ideally interleaved Nakagami-m fading channel. Two retransmission protocols with coherent equal gain code combining are adopted, where the entire frame and several selected portions of the frame are repeated in protocols Ⅰ and Ⅱ, respectively. Protocol Ⅱ could be viewed as a generalization of the recently proposed reliability-based HARQ. To facilitate performance analysis, an approximation of the product of two independent Nakagami-m distributed random variables is first developed. Then the approximate analysis is utilized to obtain exact frame error probability (FEP) for protocol Ⅰ, and the upper bound of the FEP for protocol Ⅱ. Furthermore, the throughput performance of both two protocols is presented. Simulation results show the reliability of the theoretical analysis, where protocol Ⅱ outperforms protocol Ⅰ in the throughput performance due to the reduced amount of transmitted information. 相似文献
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Liang Yang 《Wireless Personal Communications》2007,43(4):1717-1725
In this paper, we consider the multiple-input multiple-output (MIMO) wireless systems employing maximal ratio combining (MRC)
in the absence and presence of multiuser diversity. First, using the well-known moment generating function-based analysis
approach, we derive the error performance of the MIMO MRC systems without multiuser diversity over spatially correlated fading
channels. Second, we present the average capacity of MIMO MRC systems with multiuser diversity. Numerical results demonstrate
the accuracy of our analytical expressions. 相似文献
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Richard Demo Souza André Gustavo Degraf Uchôa Marcelo Eduardo Pellenz 《AEUE-International Journal of Electronics and Communications》2010,64(11):1078-1081
A novel HARQ scheme using turbo codes is proposed. The method jointly utilizes diversity combining, partial retransmission, and power scaling. Computer simulations and density evolution analysis show that the new method outperforms equal gain diversity combining and soft information combining techniques for a wide Eb/N0 range. 相似文献
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《AEUE-International Journal of Electronics and Communications》2014,68(9):893-898
Power line communication (PLC) networks for a smart grid require high reliability for data communications. In order to improve the reliability of PLC networks, we consider a maximal ratio combining (MRC) diversity scheme for a power line orthogonal frequency division multiplexing (OFDM) system. An optimal subcarrier pairing scheme is proposed to maximize the MRC gain. Numerical results are presented to verify that the proposed scheme provides enhanced performance. 相似文献
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考虑存在来自其他蜂窝的不同功率同信道干扰的多用户上行链路,分析了多天线基站采用多用户调度和最大比合并接收时的系统性能。在期望信号和干扰信号分别经历Nakgami-m和Rayleigh衰落时,运用基于概率密度函数的性能分析法推导了系统中断概率的闭合表达式。仿真结论显示,系统中断概率的解析曲线与数值仿真结果一致,系统性能随着天线数和用户数的增大而提升,多天线和多用户分集增益明显,干扰功率有较大差异时系统中断概率性能有所下降。 相似文献
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Unified performance analysis of maximal‐ratio combining for spectrum sharing systems with antenna correlation
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Yuzhen Huang Qihui Wu Jinlong Wang Yunpeng Cheng Yuming Zhang 《International Journal of Communication Systems》2015,28(2):201-212
A comprehensive analytical framework of a spectrum sharing system, in which secondary receiver (SR) is equipped with multiple antennas, is presented over Rayleigh fading channels. The impact of spatial fading correlation on the performance of spectrum sharing system with maximal‐ratio combining at the SR is investigated. In particular, we explicitly derive the CDF and moment generating function of the end‐to‐end signal‐to‐noise ratio by assuming a correlation model with arbitrary eigenvalue multiplicities at the SR. On the basis of these results, we conduct an evaluation of secondary system performance in terms of the outage probability, the average symbol error probability, and the ergodic capacity. All analytical results are verified by Monte Carlo simulations. Furthermore, to obtain an insight of system performance, the asymptotic analysis is studied to obtain the diversity gain and the coding gain in the peak transmit power dominated region. Our results show that the diversity gain is unaffected by antenna correlation whereas the coding gain is degraded. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Song Fei Tong Xiaobing Wu Qihui Wang Jinlong 《电子科学学刊(英文版)》2008,25(1):53-58
A multi-Cyclic Redundancy Check (CRC) selective Hybrid Automatic-Repeat-reQuest (HARQ) scheme for improving the throughput efficiency of Multiple Input Multiple Output (MIMO) systems is proposed in this paper. According to different feedback information from the receiver, the proposed HARQ scheme employs two strategies, referred to as retransmission frame selection and space diversity. These two strategies decrease the successive frame errors upon retransmission. Theoretic analysis and computer simulation results show that this HARQ scheme achieves higher throughput than the existing HARQ schemes even in poor conditions of low Signal-to-Noise Ratio (SNR). 相似文献
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针对随机波束成形(RBF)只有在包含大量用户的系统中才能获得较好性能的局限性,提出了一种新的收发联合波束成形方案,用于多用户多入多出(MIMO)下行链路传输。该方案有效地结合了RBF与接收天线合并技术。分析及仿真结果表明,即使在用户数为中等甚至较小时仍然能获得较高的和速率性能。由于每个用户的反馈开销没变,从而使获得同样和速率时系统的总反馈开销明显减少。仿真结果还显示,所提方案的和速率性能不仅优于原RBF,也比RBF结合最大比合并或者等增益合并的性能有明显改善,同时还保持了最优的随用户数变化的增长速度。 相似文献
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Víctor Elvira Javier Vía 《Signal processing》2012,92(3):757-766
In this paper we study space-time coding schemes for a novel OFDM-based MIMO system which performs adaptive signal combining in radio-frequency (RF). Assuming perfect channel knowledge at the receiver and statistical channel state information at the transmitter, we consider the problem of selecting the transmit and receive RF weights (beamformers), as well as the time and frequency linear precoders, under the assumption of Rayleigh channels. The transmission scheme is based on orthogonal beam division multiplexing (OBDM) and minimum mean-square error (MMSE) receive beamforming, i.e., the data is transmitted by means of several transmit beamformers matched to the spatial correlation matrix, whereas the receive beamformers are selected to minimize the MSE of the linear MMSE receiver. Finally, the performance of the proposed scheme is evaluated by means of Monte Carlo simulations. 相似文献
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A new method called joint Matched Filter (MF) combining and turbo equalization is proposed for wireless communications over
Inter-Symbol Interference (ISI) channels with diversity reception. This method takes diversity combining and equalization
as integrity and need just one turbo equalizer for all diversity branches. Computer simulations prove that our method can
take advantage of turbo equalization and diversity reception to combat fading of wireless channels. 相似文献
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Zhang Lin Qin Jiayin 《电子科学学刊(英文版)》2008,25(1):14-19
Bit Error Probability (BEP) provides a fundamental performance measure for wireless diversity systems. This paper presents two new exact BEP expressions for Maximal Ratio Combining (MRC) diversity systems. One BEP expression takes a closed form, while the other is derived by treating the squared-sum of Rayleigh random variables as an Erlang variable. Due to the fact that the extant bounds are loose and could not properly characterize the error performance of MRC diversity systems, this paper presents a very tight bound. The numerical analysis shows that the new derived BEP expressions coincide with the extant expressions, and that the new approximation tightly bounds the accurate BEP. 相似文献
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Shaoyi Xu Qinghai Yang Kyung Sup Kwak 《AEUE-International Journal of Electronics and Communications》2007,61(10):700-704
IEEE 802.11a systems which operate around 5 GHz and overlap the band of UWB signals will interfere with UWB systems significantly. In this letter, a novel narrow-band interference (NBI) suppression technique based on the singular value decomposition (SVD) algorithm is proposed in direct sequence ultra-wideband (DS-UWB) systems in wireless multipath channels. SVD is used to approximate the interference which then is subtracted from the received signals. In contrast to the conventional suppression methods such as the notch filter and the maximal-ratio combining partial RAKE (MRC PRAKE) receiver, our proposed technique is simple and robust, the hardware complexity of the receiver can be reduced greatly. 相似文献
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In this article, we propose an opportunistic transmission protocol for cooperative communication systems with L relay nodes under the influence of fading channels. Unlike the protocols previously known in the literature, and given the fact that direct single-link communication outperforms multilink cooperative communication in terms of throughput for same channel conditions, we adopt the channel conditions of the direct link as a main criterion to use whether the direct link in the transmission or the indirect cooperative link. Different performance metrics are derived to demonstrate the performance of the proposed protocol along with a switching combining with a preferable link scheme. These metrics include the bit error rate (BER), outage probability, signal to interference noise ratio (SNR) gain, average throughput and the sum SNR–throughput product (SSTP). The latter performance metric is introduced to compare the maximum achievable throughput as well as the SNR range at a given quality of service (QoS). Our results show that the proposed opportunistic protocol improves the throughput as compared to the conventional cooperative communication systems for the whole range of average SNR. On the other hand, it improves the coverage range as compared to the direct link communication. 相似文献
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Comparative performance analysis of cooperative and multi dual‐hop relay networks using MGF approach
Muhammad Asshad Adnan Kavak Kerem Küük Sajjad Ahmad Khan 《International Journal of Communication Systems》2020,33(15)
In this paper, we analyzed and compared the performance of cooperative diversity systems such as cooperative and multi dual‐hop networks with non‐regenerative relay nodes. The contributions of this study are twofolds. Firstly, analytical expressions of outage probability Pout and average symbol error rate ASER are derived using moment generating function (MGF) analysis of the received SNR with the assumption that the channel experiences Weibull fading and the best relay selection is used. Then, using the analytical results, comparative performance evaluation of cooperative and multi dual‐hop relay networks is done for varying number of relay nodes and different receive diversity schemes such as maximal ratio combining (MRC) and selection combining (SC). The results show that the cooperative relay network has better performance than a multi dual‐hop relay network in terms of Pout and ASER. The results also show that the multi dual‐hop network can achieve the same performance as the cooperative network with the requirement that it needs the deployment of three times more relay nodes. 相似文献