共查询到17条相似文献,搜索用时 156 毫秒
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针对频率选择性衰落信道下的多天线盲接收问题,本文提出了一种新的"合成器-均衡器"盲空间分集均衡器结构.基于频域波形合成、均衡器与软符号信息的联合处理框架,首先设计了频域BLOCK-SUMPLE迭代算法,对多路信号频域合成权值进行联合估计,实现频率选择性衰落信道下的波形合成.在此基础上,利用均衡器输出软符号信息重构合成参考,对权值相位予以修正,实现对等效合成信道的优化补偿.与传统盲空间分集均衡算法相比,上述算法实现无需训练序列辅助,并且优化了信号分集合并性能,降低了均衡器的设计难度.仿真结果表明,采用新型结构可有效改善衰落信道下的盲接收效果,逼近最佳空间分集均衡器性能. 相似文献
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针对处于频率选择性衰落环境中的垂直型贝尔实验室分层空时(Vertical Bell iabs LAyered Space-Time,V-BLAST)结构,该文首先对其进行联合空时符号分组,然后提出了一种新颖的空时旋转不变性编码技术(Space-Time Rotational-Invariance Coding Technique,STRICT)。通过巧妙利用上述编码技术中的旋转不变性性质,该文继续为V-BLAST结构提出了一种多输入多输出(Multiple-Input Multiple-Output,MIMO)频率选择性无线信道的盲估计方法。仿真结果表明了该文新颖STRICT的有效性及其信道盲估计方法的性能。 相似文献
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文章研究了OFDM-MIMO系统中的循环延迟分集(CDD),以及基于Alamouti的空时分组编码(STBC)与空频分组编码(SFBC),针对发射分集方案所必须知道的信道信息,对两种信道估计方法,即最小二乘(LS)+线性插值与最小均方误差(MMSE)插值进行了研究。通过链路仿真还给出了以上分集方案在不同信道条件下的性能曲线,此外,对两种信道估计方法的误帧率做了统计。结果表明,CDD结合信道编译码可获得分集增益,有效对抗无线信道的衰落性。STBC,SFBC在不需要外码的情况下便可获得较大分集增益,且分别适用于频率选择性衰落与时间选择性衰落信道。而MMSE估计可以获得较为理想的误帧率,为分集方案提供较准确的信道参数以提高系统的可靠性。 相似文献
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Schober R. Gerstacker W.H. Lampe L.H.-J. 《Wireless Communications, IEEE Transactions on》2004,3(3):734-744
In this paper, space-time block-coded transmission over frequency-selective fading channels is investigated. A lower bound for the pairwise error probability for optimum detection is given. Also, an approximation for the bit-error rate is derived and compared with simulation results for maximum-likelihood sequence estimation (MLSE) for the GSM/EDGE (Enhanced Data Rates for GSM Evolution) system. Furthermore, a novel design rule for space-time block codes (STBCs) for frequency-selective fading channels is provided. A corresponding code is designed and shown to yield higher performance than Alamouti's code. It is demonstrated that for fading channels with L independent impulse response coefficients, STBCs designed for the flat fading channel can achieve at most a diversity order of (N/sub T/+L-1)N/sub R/ if N/sub T/ transmit antennas and N/sub R/ receive antennas are used. On the other hand, the maximum diversity order employing the proposed code design rule is LN/sub T/N/sub R/. 相似文献
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Single-carrier space-time block-coded transmissions over frequency-selective fading channels 总被引:6,自引:0,他引:6
Shengli Zhou Giannakis G.B. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(1):164-179
We study space-time block coding for single-carrier block transmissions over frequency-selective multipath fading channels. We propose novel transmission schemes that achieve a maximum diversity of order N/sub t/N/sub r/(L+1) in rich scattering environments, where N/sub t/ (N/sub r/) is the number of transmit (receive) antennas, and L is the order of the finite impulse response (FIR) channels. We show that linear receiver processing collects full antenna diversity, while the overall complexity remains comparable to that of single-antenna transmissions over frequency-selective channels. We develop transmissions enabling maximum-likelihood optimal decoding based on Viterbi's ( 1998) algorithm, as well as turbo decoding. With single receive and two transmit antennas, the proposed transmission format is capacity achieving. Simulation results demonstrate that joint exploitation of space-multipath diversity leads to significantly improved performance in the presence of frequency-selective fading channels. 相似文献
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An iterative pilot-symbol aided modulation (PSAM) channel estimation approach is proposed for vertical Bell Laboratories layered space-time (V-BLAST) orthogonal frequency division multiplexing systems operating on frequency-selective fading channels. Since the signals at the receive antennas are the superposition of signals from multiple transmit antennas, accurate channel estimates are crucial for good error performance. Furthermore, the time selectivity of the fading channels leads to inter-carrier interference (ICI). While ICI can be ignored for slow fading channels, it should be mitigated for fast fading channels. This paper proposes an ICI mitigation scheme for time-varying channels. We also propose an iterative channel estimator with low-complexity. Simulation results demonstrate the usefulness of the proposed algorithm on frequency-selective fading channels. 相似文献
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We propose an Alamouti-like scheme for combining space-time block-coding with single-carrier frequency-domain equalization. With two transmit antennas, the scheme is shown to achieve significant diversity gains at low complexity over frequency-selective fading channels 相似文献
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本文介绍了两种空-时传输机制,通过在频率选择性衰落信道上使用两根传输天线,来得到全速率和全分集非相干性.第一种机制结合了频域的OFDM微分空-时分组编码;第二种机制采用微分反时空-时分组编码,这样可以保证在不需要当前过采样或多根接收天线的情况下保证盲信道估计. 相似文献