共查询到20条相似文献,搜索用时 156 毫秒
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本文提出了一种新的对周期平稳信号进行检测以及对二阶周期循环频率进行估计的算法。该算法利用信号的递归性质构造高阶自相关矩阵,并通过利用周期平稳信号与自相关矩阵特征值和特征向量的关系,对其进行检测以及对循环频率进行估计。传统检测周期平稳信号的算法是通过计算其循环自相关函数或循环谱实现,相比传统算法而言,本算法由于利用到了信号更多的先验信息,因而在较低信噪比以及较低快拍数下对周期平稳信号均能有较好的检测性能。文中仿真实验表明,本文所提算法估计出的伪循环谱相比传统方法估计出的循环谱更为平滑,在相同快拍和信噪比条件下,检测概率均高于传统方法,特别在低信噪比下对检测概率的改善更为明显。 相似文献
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脉冲噪声环境下基于分数低阶循环相关的MUSIC算法 总被引:2,自引:0,他引:2
该文以稳定分布作为噪声模型,研究了脉冲噪声环境下循环平稳信号的波达方向估计问题。针对在脉冲噪声环境中基于传统2阶循环相关的算法效果显著退化的问题,该文提出了基于分数低阶循环相关的分数低阶循环MUSIC算法(FLOCC-MUSIC)。将分数低阶循环相关与MUSIC算法相结合,可以有效抑制脉冲噪声的同频带干扰。计算机仿真表明了此算法可有效完成高斯噪声和脉冲噪声条件下的波达方向估计,其性能优于传统的基于2阶循环相关的Cyclic-MUSIC。 相似文献
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本文研究阵列信号高分辨波达方向-多普勒频率二维估计问题,在未精确已知阵列流形条件下,利用到达波信号的多普勒频率,提出了一种波达方向-多普勒频率盲估计的新方法。理论分析和计算机仿真结果表明此方法在实际阵列存在增益和相位误差时亦有效,而且与现有二维估计算法相比,其运算量较小。 相似文献
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未知阵列流形条件下波达方向—多普勒频率盲估计方法 总被引:8,自引:0,他引:8
本文研究阵列信号高分辩波达方向-多普勒频率二维估计问题,在未精确已知阵列流形条件下,利用到达波信号的多普勒频率,提出了一种波达方向-多普勒频率盲估计的新方法,理论分析和计算机仿真结果表明此方法在实际阵列存在增益和相位误差时益有效,而且现有二维估计算法相比,其运算量较小。 相似文献
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Ju-Hong Lee Yung-Ting Lee 《Antennas and Propagation, IEEE Transactions on》1999,47(2):233-241
This paper deals with the problem of robust adaptive array beamforming for cyclostationary signals. By exploiting the signal cyclostationarity, the SCORE algorithms presented by Agee, Schell and Gardner (1990) have been shown to be effective in performing adaptive beamforming without requiring the direction vector of the desired signal. However, these algorithms suffer from severe performance degradation even if there is a small mismatch in the cycle frequency of the desired signal. In this paper, we first evaluate the performance of the SCORE algorithms in the presence of cycle frequency error (CFE). An analytical formula is derived to show the behavior of the performance degradation due to CFE. Based on the theoretical result, we then develop an efficient method in conjunction with the SCORE algorithms to achieve robust adaptive beamforming against the CFE. Several simulation examples for confirming the theoretical analysis and showing the effectiveness of the proposed method are also presented 相似文献
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This paper deals with the problem of robust adaptive array beamforming using signal cyclostationarity. The constrained cyclic adaptive beamforming (C-CAB) algorithm presented by Wu and Wong (1996) [6] has been shown to be effective in performing adaptive beamforming without requiring the direction vector or the waveform of the desired signal. However, this algorithm suffers from severe performance degradation even if there is a small mismatch in the cycle frequency of the desired signal. In this paper, we first evaluate the performance degradation of the C-CAB algorithm in the presence of cycle frequency error (CFE). A novel compensation method in conjunction with the subspace projection is then proposed to tackle the problem due to CFE. We reconstruct the required cyclic conjugate correlation matrix by using a compensation matrix to cope with the deterioration of its dominant singular value when CFE exists. Finally, several simulation examples are provided to show the effectiveness of the proposed algorithm. 相似文献
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Many modulated communication signals exhibit a cyclostationarity (or periodic correlation) property, corresponding to the underlying periodicity arising from carrier frequencies or band rates. By exploiting cyclostationarity, i.e. evaluating the cyclic correlations of the received data at certain cycle frequencies, one can extract the cyclic correlations of only signals with the same cycle frequency and null out the cyclic correlations of stationary additive noise and all other cochannel interferences with different cycle frequencies. Thus, the signal detection capability can be significantly improved. An approach for exploiting cyclostationarity that is asymptotically exact for either narrowband or broadband sources, unlike previous methods, is proposed. The method also has significant implementational advantages over the earlier techniques. The simulation results indicate a significantly better performance in some environments 相似文献
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Ju-Hong Lee Yung-Ting Lee Wen-Hao Shih 《Signal Processing, IEEE Transactions on》2000,48(7):1893-1901
This paper deals with the problem of robust adaptive array beamforming for cyclostationary signals. By exploiting the signal cyclostationarity, the LS-SCORE algorithm presented in a paper by Agee et al. (1990) has been shown to be effective in performing adaptive beamforming without requiring the direction vector of the desired signal. However, this algorithm suffers from severe performance degradation even if there is a small mismatch in the cycle frequency of the desired signal. In this paper, we first evaluate the performance of the LS-SCORE algorithm in the presence of cycle frequency error (CFE). An analytical formula is derived to show the behavior of the performance degradation due to CFE. An efficient method is then developed based on the fact that the array output power approaches its maximum as the CFE is reduced. We formulate the problem as an optimization problem for reducing the CFE iteratively to achieve robust adaptive beamforming against the CFE. Simulation examples for confirming the theoretical analysis and showing the effectiveness of the proposed method are provided 相似文献
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《Communications Letters, IEEE》2009,13(7):537-539
Timing and frequency offset estimation based on the second order cyclostationarity have been explored in many literatures [1]- [9]. In this article, we revisit the class of these estimators and propose for both single carrier and OFDM systems, a new method for timing and frequency offset estimation. Different from the previous methods, here, the estimation of timing and frequency offset process are independent of each other. Thus it does not introduce propagation error which is inherent in most of the estimators proposed so far and has an improved performance. Monte Carlo simulations are performed to verify the results. 相似文献
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Orthogonal frequency division multiplexing (OFDM) systems are highly sensitive to carrier frequency offset (CFO), especially in doubly-selective fading environment. Cyclostationarity-based blind synchronization methods are appealing in high-data-rate applications and low signal-to-noise regions. However, the cyclostationarity has not been exploited for frequency synchronization of OFDM systems under doubly-selective fading channels. In this paper, we derive the close-form second order cyclic statistics of the received OFDM signal in presence of CFO, by modeling the doubly-selective fading channel with basis expansion model. Both transmitter-induced cyclostationarity and doubly-selective channel information are contained in the derived cyclic moments, and they are efficiently utilized for CFO estimation. Simulation results demonstrate that the proposed estimator provides significant improvements on frequency synchronization performance. 相似文献
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Lei Yang Zhe Chen Fuliang Yin 《AEUE-International Journal of Electronics and Communications》2012,66(1):89-92
In this paper, a cyclo-energy detector is proposed for the spectrum sensing problem based on the cyclostationary signal analysis. The proposed detector can determine the existence of primary user by estimating the primary user's received power according to the cyclostationarity features of the secondary user. By using this detector, the secondary user does not need to stop transmitting signals when sensing the frequency spectrum. Simulation results are presented to confirm the performance of the proposed detector. 相似文献
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The method for evaluating the tracking performance in the above paper obliterates the contribution to the mean square error which is due to the cyclostationarity of the disturbances. Beside this, the pattern-dependent jitter has not been considered in the paper. Our results include the effect of cyclostationarity and the pattern-dependent jitter. 相似文献
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In order to achieve lower bit error rates (BERs), multiuser detection techniques have been proposed. Generally, multiuser detectors can provide excellent performance only when channel parameters are precisely known. In this paper, we propose a moment-based blind method to estimate down-link channels precisely. The mean square error (MSE) expression of the channel vector estimate has been derived. Through simulations, we show the effect of the channel estimation error on the performance of a multiuser detector. In this paper, we also show that finite impulse response (FIR) channels can be blindly identified by using the proposed method and the spreading operation. Since the spreading operation of the code division multiple access (CDMA) can induce cyclostationarity, any FIR channel can be identified by the proposed method. Of course, in order to guarantee identifiability, some conditions on the spreading codes will be satisfied. In this paper, these conditions are also found 相似文献
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一种LOFDM系统定时和频偏的盲估计算法 总被引:1,自引:0,他引:1
基于网格正交频分复用(LOFDM)信号的周期平稳性,该文提出一种LOFDM系统定时和载波频率偏差的盲估计算法。理论分析和仿真实验证实由该算法构造的估计器能够有效地对抗频率选择性慢时变信道引起的衰落;在信道噪声广义平稳的情况下,估计器性能与信噪比无关,于是估计器在低信噪比条件下也能很好地工作;另外,符号定时和频率偏差估计器的性能互不影响。 相似文献