共查询到20条相似文献,搜索用时 703 毫秒
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为了改善存在信道误差、空时相关条件下多用户多入多出(MIMO)系统的性能,给出了一种基于信漏噪声比(SLNR)的鲁棒预编码算法.通过推导空时相关信道环境下信道向量的条件均值和协方差,分别建立了发送端信道状态信息(CSIT)和接收端信道状态信息(CSIR)模型.在此模型基础上,推导了收发两端信道状态信息(CSI)均不理想情况下的鲁棒SLNR 预编码以及相应的接收滤波矩阵.仿真结果表明,该算法对空间相关性、时间相关性以及信道误差均具备一定的鲁棒性. 相似文献
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不同传输环境下MIMO信道的空间相关性的研究 总被引:1,自引:0,他引:1
基于宏小区及微小区MIMO信道模型,比较了MIMO信道在两种传输环境中的空间相关特性,通过数值分析方法得到了两类信道空间相关性随发送端、接收端天线阵列的分布而变化的特征曲线,并分析比较了信道参数,即到达角的角度扩展,对空间相关性的影响。在此基础上,讨论了空间相关系数对系统功率有效性和频带有效性的影响,找到了在不同传输环境下,影响系统BER性能的空间相关系数的门限。 相似文献
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基于准正交空时分组编码的空间激光通信 总被引:1,自引:0,他引:1
准正交空时分组编码(QOSTBC)是一种正交空时编码的变换编码结构,将时间分集和空间分集相结合,具有高效的分集利用率和编码效率。QOSTBC是解决大气湍流对光通信影响的有效手段之一。在研究了大气信道特性的基础上,提出一种基于QOSTBC结构和空间分集光通信系统的信道模型;介绍了QOSTBC原理,分析了系统的信道容量和误码率(BER);利用蒙特卡罗仿真比较了采用空时分集编码与未使用分集编码系统的容量及BER的情况。结果表明,使用QOSTBC系统的信道容量随发射天线数增加而递增,误码性能得到有效改善。QOSTBC与Alamouti编码系统相比系统信噪比节省约9dB,说明该系统具有编码所提供的良好信道容量和误码性能,能够有效地抑制大气湍流对光通信所产生的光强起伏影响。 相似文献
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一般在空时编码解码时接收端需要信道状态信息(CSI),因而必须获得精确的信道估计,而差分空时编码(DSTC)接收端在解码时不需要CSI,因而不需要信道估计。在信道衰落快或信息传输速率高的情况下,实时而精确的信道估计非常困难或代价太高,此时接收端不能获得CSI,因而需要差分空时编码。对非相干系统中空时编码的编译码原理、特点和性能进行了分析和比较,并对其中的部分空时编码给出了具体的实例和仿真结果。 相似文献
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在实际的多输入多输出(MIMO:Muhiple Input Multiple Output)移动通信系统中,信道的空间相关性通常会使得现有的空时编码方案难以获得最佳的误码性能。为了解决该问题,本文提出了一种适用于MIMO空间相关信道的空时预编码方案。该方案在完成对发射信号的空时编码后,针对发射天线的空间相关矩阵设计了合理的预编码矩阵,进而能够在保证分集增益的前提下克服相关信道的不利影响。仿真结果证实,该方案能够在一定程度上有效提高整个系统的误码性能。 相似文献
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In this paper, we deal with the design of a full-rate space-time block coding (STBC) scheme optimized for linear iterative decoding over fast fading multiple-input multiple-output (MIMO) channel. A general and simple coding scheme called diagonal threaded space-time (DTST) code is presented for an arbitrary number of transmit and receive antennas. Theoretical analysis shows that DTST code associated with linear iterative decoding tends towards full diversity performance while providing maximum MIMO multiplexing gain. Simulation results confirm the ability of DTST to outperform the state-of-the-art STBC and conventional spatial data multiplexing schemes under iterative processing. 相似文献
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Performance analysis of space-time block codes over keyhole Nakagami-m fading channels 总被引:2,自引:0,他引:2
Hyundong Shin Jae Hong Lee 《Vehicular Technology, IEEE Transactions on》2004,53(2):351-362
In multiple-input-multiple-output (MIMO) fading environments, degenerate channel phenomena, called keyholes or pinholes, may exist under the realistic assumption that the spatial fading is uncorrelated at the transmitter and the receiver, but the channel has a rank-deficient transfer matrix. In this paper, we analyze the exact average symbol error rate (SER) of orthogonal space-time block codes (STBCs) with M-PSK and M-QAM constellations over Nakagami-m fading channels in the presence of the keyhole. We derive the moment generating function (MGF) of instantaneous signal-to-noise ratio (SNR) after space-time block decoding (signal combining) in such channels. Using a well-known MGF-based analysis approach, we express the average SER of the STBC in the form of single finite-range integrals whose integrand contains only the derived MGF. Numerical results show that the keyhole significantly degrades the SER performance of the STBC from idealistic behaviors in independent identically distributed MIMO channels. 相似文献
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Chih-Wei Jen 《Wireless Personal Communications》2014,77(4):3041-3049
Under Rayleigh fading channels, a common problem with blind multiuser space-time block coded (STBC) multicarrier code division multiple access (MC-CDMA) detectors is that their performance is very sensitive to the signature waveform mismatch (SWM) induced by channel estimation distortion. This paper presents a robust detector using the generalized sidelobe canceller with a double-feedback filter that effectively mitigates the channel estimation distortion for the STBC MC-CDMA system during multipath fading. Numerical simulations show that the proposed detector substantially provides robustness against small-to-medium SWM scenarios for a downlink STBC MC-CDMA system. 相似文献
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Space-time block coded (STBC) transmission has been established as an efficient tool to enhance communication performance over wireless fading channels. The success of STBC decoding relies on accurate channel knowledge at receivers. In this work, we present a channel estimation approach that does not require training data to estimate unknown channels. Focusing on STBC from orthogonal designs, we present channel identification conditions that are largely verifiable in terms of the code and the antenna array configuration. We also develop a simple subspace-based algorithm to identify the unknown space-time channel matrix for complex transmission. Finally, we present simulation test results to illustrate the performance of the proposed method. 相似文献
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空时分组编码 ( STBC)可有效的应用于无线系统中 ,提高系统的容量。 STBC采用最大似然译码算法 ,译码过程中需要信道信息。本文利用导频辅助的方式获得信道信息 ,分析了Rayleigh信道下随着移动台速度的变化 STBC- CDMA系统的误码率性能 相似文献
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Due to the crowded orbits and shortage of frequency resources, the use of MIMO technology to improve spectrum efficiency and an increase of the capacity have become a necessary trend of broadband satellite communication. Firstly, we analyze the main influenced factors and compare the bit error rate (BER) performance of space-time block code (STBC) scheme and space-time trellis code (STTC) scheme. Then we build up the model of land mobile satellite (LMS) channel under different environments by using 3-state Markov chain. This paper emphatically studies the BER performance of STTC and STBC in the MIMO satellite channel. The main emphasis is placed on the effects of different factors, such as terminal environment and elevation angles, on the BER performance of STBC and STTC schemes. Simulation results indicate that performance of STTC in Rayleigh channel is obviously improved with the increasing number of transmitting and receiving antennas, but the encoder state has little impact on the performance. In the Rayleigh channel, the performance of Alamouti code is better than that of STTC. In the LMS channel, performance of these two kinds of space-time coding in open area is optimal, and in the urban area it is the worst. Nevertheless, performance of STTC is slightly superior to the performance of STBC under different circumstances. Under the same environmental conditions, BER of STBC and STTC reduces with the increase of the satellite altitude angle, and therefore, the BER curves of STTC fall faster. 相似文献
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We consider the design of iterative receivers for space-time block-coded orthogonal frequency-division multiplexing (STBC-OFDM) systems in unknown wireless dispersive fading channels, with or without outer channel coding. First, we propose a maximum-likelihood (ML) receiver for STBC-OFDM systems based on the expectation-maximization (EM) algorithm. By assuming that the fading processes remain constant over the duration of one STBC code word and by exploiting the orthogonality property of the STBC as well as the OFDM modulation, we show that the EM-based receiver has a very low computational complexity and that the initialization of the EM receiver is based on the linear minimum mean square error (MMSE) channel estimate for both the pilot and the data transmission. Since the actual fading processes may vary within one STBC code word, we also analyze the effect of a modeling mismatch on the receiver performance and show both analytically and through simulations that the performance degradation due to such a mismatch is negligible for practical Doppler frequencies. We further propose a turbo receiver based on the maximum a posteriori-EM algorithm for STBC-OFDM systems with outer channel coding. Compared with the previous noniterative receiver employing a decision-directed linear channel estimator, the iterative receivers proposed here significantly improve the receiver performance and can approach the ML performance in typical wireless channels with very fast fading, at a reasonable computational complexity well suited for real-time implementations 相似文献