共查询到19条相似文献,搜索用时 109 毫秒
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异步DS-CDMA系统盲空时信道估计及多用户检测 总被引:1,自引:0,他引:1
该文提出了适用于频率选择性瑞利衰落信道中的异步DS-CDMA系统盲空时信道估计及多用户检测算法。通过研究多径信号码空间和数据矢量空间,采用噪声子空间技术进行异步DS-CDMA系统盲空时信道参数估计,同时利用了多径传播和接收机同步失调的特性,以利于把盲线性滤波优化技术应用于稳健的干扰抑制。使用一种修改的ULV更新算法进行噪声子空间跟踪,该算法不需要相关矩阵的秩估计,直接估计噪声子空间,不进行信号子空间跟踪。并且研究了线性约束最小方差(LCMV)盲空时多用户检测及其基于Householder变换约束最小均方算法(HCLMS)的自适应实现。仿真结果验证了该文算法的有效性。 相似文献
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考虑实际的MC-CDMA上行链路,深入研究了基于RLS算法实现的MOE(RLS-MOE)盲自适应多用户检测,提出了MC-CDMA系统下一种基于子空间约束RLS的半盲多用户检测算法.在MOE盲多用户检测的基础上,利用小区内用户的已知扩频码设计了一种MOE半盲多用户检测器.将子空间方法和RLS算法相结合提出一种基于子空间约束的RLS 算法,使用该算法自适应得到MOE的权向量.本文算法利用所有已知用户的扩频码抑制了小区内用户的干扰,子空间约束的RLS 算法降低了噪声的影响,从而改善了系统的性能.修正的PASTd算法实现了信号的自适应跟踪,大大降低了计算量.仿真实验表明,本文算法的输出信干噪比和误码率性能优于RLS-MOE盲多用户检测,更接近于最优值. 相似文献
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针对多径衰落CDMA信道,提出了一种基于信号子空间估计的联合盲特征波形估计与多用户检测方案,分析了两处线性多用户检测器(解相关检测器和线性MMSE检测器)在信号子空间参数下的闭式解及其抗远近效应能力,并讨论了用于联合盲特征波形估计与多用户检测实现的PASTd算法。最后给出了仿真结果。 相似文献
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文章提出了一种基于卡尔曼滤波的盲空时多用户检测方法。卡尔曼滤波是一种线性最小方差状态估计,把它有效地结合阵列天线与多用户检测。该自适应多用户检测方法不需要发送训练序列。在多径衰落信道下,仿真结果表明该方法收敛速度比LMS算法更快,有较强的抗多径和多址干扰能力。 相似文献
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在分析阵列天线接收的多径CDMA信号的基础上,发掘阵列信号子空间与扩频用户伪码序列的关系,对传统的子空间波束成形器结构做了改进,提出一种新的基于盲波束成形的伪随机码序列盲估计算法。算法采用复独立分量分析法迭代,得到盲波束成形器系数,能在波达方向未知的情况下,估计各个用户的扩频序列。本文同时提出一种基于盲波束形成的异步多径CDMA信号多用户检测算法,可以在未知各个用户扩频码和波达方向的先验知识条件下,完成多径异步CDMA信号的多用户检测。算法由于同时利用了扩频增益和阵列天线分集增益,相比于单天线多用户检测算法性能有所提高。理论分析和仿真结果验证了算法的可行性。 相似文献
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该文提出了用于MC DS-CDMA系统中的两种SDCMA(最陡下降常模算法)盲检测方法,一种是SDCMA盲均衡算法,在此基础上,提出了另一种联合均衡和多用户检测的SDCMA盲算法。同时还将这两种算法与基于子空间的MMSE(最小均方误差)盲检测算法进行比较。仿真结果表明,这两种SDCMA算法的BER(误比特率)性能均优于子空间法,而且联合均衡和多用户检测的SDCMA盲算法利用同时对均衡权值向量和多用户检测器向量进行自适应更新,能较大程度地改善系统性能,是这3种盲算法中性能最佳的一个。 相似文献
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Blind adaptive multiuser detection based on Kalman filtering 总被引:9,自引:0,他引:9
Xian-Da Zhang Wei Wei 《Signal Processing, IEEE Transactions on》2002,50(1):87-95
Although several Kalman filtering algorithms have been presented for adaptive multiuser detection, none is "blind" due to requiring training data sequences and/or more knowledge than the spreading waveform and delay of the desired user. This paper proposes a novel blind adaptive multiuser detector based on Kalman filtering and compares it with previously published LMS and RLS algorithms for blind adaptive multiuser detection. It is shown that the steady-state excess output energy of the Kalman filtering algorithm is identically zero for a stationary environment. Simulation results show the effectiveness of the new Kalman filtering algorithm 相似文献
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Space-time multiuser detection in multipath CDMA channels 总被引:3,自引:0,他引:3
The problem of multiuser detection in multipath CDMA channels with receiver antenna array is considered. The optimal space-time multiuser receiver structure is first derived, followed by linear space-time multiuser detection methods based on iterative interference cancellation. Blind adaptive space-time multiuser detection techniques are then proposed, which require prior knowledge of only the spreading waveform and the timing of the desired user's signal. Single-user-based space-time processing methods are also considered and are compared with the multiuser approach. It is seen that the proposed multiuser space-time processing techniques offer substantial performance gains over the single-user-based methods, especially in a near-far situation 相似文献
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Recently developed subspace techniques for blind adaptive multiuser detection are briefly reviewed first. In particular, blind
methods based on signal subspace tracking for adapting linear multiuser detectors in AWGN CDMA channels are considered, as
well as extensions of these techniques to frequency selective fading channels, dispersive channels, and antenna array spatial
processing. In addition, subspace‐based nonlinear adaptive techniques for robust blind multiuser detection in non‐Gaussian
ambient noise channels are also described. Several new techniques are then developed within the subspace framework for blind
joint channel estimation and multiuser detection, under some specific channel conditions. These include (1) an adaptive receiver
structure for joint multiuser detection and equalization in dispersive CDMA channels, (2) a subspace method for joint multiuser
detection and equalization in unknown correlated noise, and (3) a method for joint interference suppression and channel tracking
in time‐varying fading channels.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Blind multiuser detection: a subspace approach 总被引:24,自引:0,他引:24
Xiaodong Wang Poor H.V. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1998,44(2):677-690
A new multiuser detection scheme based on signal subspace estimation is proposed. It is shown that under this scheme, both the decorrelating detector and the linear minimum-mean-square-error (MMSE) detector can be obtained blindly, i.e., they can be estimated from the received signal with the prior knowledge of only the signature waveform and timing of the user of interest. The consistency and asymptotic variance of the estimates of the two linear detectors are examined. A blind adaptive implementation based on a signal subspace tracking algorithm is also developed. It is seen that compared with the previous minimum-output-energy blind adaptive multiuser detector, the proposed subspace-based blind adaptive detector offers lower computational complexity, better performance, and robustness against signature waveform mismatch. Two extensions are made within the framework of signal subspace estimation. First, a blind adaptive method is developed for estimating the effective user signature waveform in the multipath channel. Secondly, a multiuser detection scheme using spatial diversity in the form of an antenna array is considered. A blind adaptive technique for estimating the array response for diversity combining is proposed. It is seen that under the proposed subspace approach, blind adaptive channel estimation and blind adaptive array response estimation can be integrated with blind adaptive multiuser detection, with little attendant increase in complexity 相似文献
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一种基于MOE的盲自适应的多用户检测器 总被引:1,自引:0,他引:1
盲自适应多用户检测器由于既能实时跟踪信道信息及用户信息,又不需要发送训练序列而成为研究的热点,但一般的盲自适应多用户检测技术存在收敛速度慢的弱点。提出一种基于MOE(最小输出能量)的盲自适应多用户检测器,通过合理地选取时变步长,可有效地提高多用户检测器的收敛速度,从而提高系统的性能。 相似文献
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S. Nayeb Nazar W.-P. Zhu M.O. Ahmad M.N.S. Swamy 《Circuits, Systems, and Signal Processing》2004,23(5):409-432
In this paper, the problem of multiuser detection for synchronous code division
multiple access systems in both additive white Gaussian noise and multipath channels is
addressed. A new multiuser detection receiver that uses an adaptive blind array along with
an adaptive parallel interference canceler is proposed. The replacement of a conventional
antenna array with a two-dimensional RAKE receiver is also considered for frequency
selective Rayleigh fading channels. By using a constrained optimization criterion along
with the gradient-projection algorithm, a blind algorithm for the adaptation of the array response
vector is proposed. The new algorithm is superior to a few typical blind algorithms
in the literature in terms of both performance and computational complexity. The proposed
receiver has the ability to cancel very strong multiple access interference coming from the
same direction as the desired signal. Simulation results are presented to show the excellent
performance of the proposed combination scheme in comparison to that of using either a
multiuser detection or adaptive antenna arrays in a severe near-far situation. 相似文献
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Robust multiuser detection in non-Gaussian channels 总被引:7,自引:0,他引:7
In many wireless systems where multiuser detection techniques may be applied, the ambient channel noise is known through experimental measurements to be decidedly non-Gaussian, due largely to impulsive phenomena. The performance of many multiuser detectors can degrade substantially in the presence of such impulsive ambient noise. We develop robust multiuser detection techniques for combating multiple-access interference and impulsive noise in CDMA communication systems. These techniques are based on the M-estimation method for robust regression. Analytical and simulation results show that the proposed robust techniques offer significant performance gain over linear multiuser detectors in impulsive noise, with little attendant increase in computational complexity. We also develop a subspace-based technique for blind adaptive implementation of the robust multiuser detectors, which requires only the signature waveform and the timing of the desired user in order to demodulate that user's signal. The robust multiuser detection technique and its blind adaptive version can be applied to both synchronous and asynchronous CDMA channels 相似文献