共查询到20条相似文献,搜索用时 15 毫秒
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Li Jun Liao Guisheng Wu Yuntao 《电子科学学刊(英文版)》2006,23(1):121-123
Most of the blind Orthogonal Frequency Division Multiplexing (OFDM) Carrier Frequency Offset (CFO) estimators necessitate large number of samples to ensure the estimation accuracy. However, the number of samples can not be selected too large because of the carrier offset drift. In this letter, a new closed form algorithm for blind OFDM CFO estimation in frequency-selective channel is proposed. This method utilizes the propagator obtained from data matrix and the diagonal loading technique, thus it has better performance even only using one or two OFDM blocks. Furthermore, the range of the CFO estimation which can be handled is overall transmission spectral. Simulation results confirm its effectiveness. 相似文献
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基于相关函数的递推最小二乘算法及其在回波消除中的应用 总被引:7,自引:0,他引:7
本文给出一种新的类似于RLS(recursive least squares)算法的递推最小二乘算法,该算法直接对输入信号的相关函数进行处理而不是对输入信号本身进行处理,理论分析表明了该算法的收敛性。该算法应用于回波消除问题中,克服了常规自适应滤波算法在出现双方对讲的情况下需停止调节自适应滤波器系数这一不足。计算机模拟仿真表明该算法在双方对讲的情况下有良好的收敛性能。 相似文献
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研究了多径信道下OFDM系统的一种新的载波频率跟踪算法,这种算法以判决反馈和接收端的时域信号重构为基础。推导了估计结果的精确解,比较了使用原估计结果和新的估计结果进行频偏补偿时系统跟踪性能的不同。通过对算法的仔细分析,发现除了通常的加性噪声外,信道估计误差、子载波数目和子载波的调制方式也影响频偏的估计结果和跟踪范围,而且子载波的数目和调制方式是决定性的因素。这种频率跟踪方法的优点是即使在很低的信噪比下仍然能获得高的跟踪精度,且实现相对简单。 相似文献
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Ouyang Shan Bao Zheng Liao Guisheng 《电子科学学刊(英文版)》2000,17(3):270-278
Based on the least-square minimization a computationally efficient learning algorithm for the Principal Component Analysis(PCA) is derived. The dual learning rate parameters are adaptively introduced to make the proposed algorithm providing the capability of the fast convergence and high accuracy for extracting all the principal components. It is shown that all the information needed for PCA can be completely represented by the unnormalized weight vector which is updated based only on the corresponding neuron input-output product. The convergence performance of the proposed algorithm is briefly analyzed.The relation between Oja's rule and the least squares learning rule is also established. Finally, a simulation example is given to illustrate the effectiveness of this algorithm for PCA. 相似文献
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针对正交频分复用系统频偏估计问题,提出了一种基于遗传算法的高精度盲频偏估计器。该算法首先将带载波间干扰的正交频分复用系统视为正交码分多址接入系统,将载波间干扰系数视为码分多址接入系统的扩频码,利用估计的载波频偏构造扩频码,进而重建接收信号;然后利用重建信号跟实际接收信号最小重建误差原则构造了盲频偏估计的代价函数,并设计了对应于遗传算法的适应度函数;最后利用遗传算法强大的并行搜索和全局寻优能力,通过最小化代价函数求得最佳频偏估值。仿真结果表明,所提算法具有较高的估计精度,低信噪比下性能显著,有效降低了时间复杂度,且不受频偏估计范围和信号调制类型的限制。 相似文献
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Orthogonal frequency division multiplexing (OFDM) systems with direct-conversion receiver (DCR) are vulnerable to carrier frequency offset (CFO), dc offset (DCO) and in-phase/quadrature (I/Q) imbalance. In this paper, we propose blind estimator for joint estimation of CFO, DCO and I/Q imbalance in OFDM systems with DCR. Simulation results show that performance of proposed estimator approaches Cramér-Rao lower bound (CRLB) asymptotically, which demonstrates its effectiveness. 相似文献
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Fang Zhi Xiao Wan'ang Shi Yin 《电子科学学刊(英文版)》2008,25(1):1-6
A new fine carrier frequency offset estimation algorithm in Orthogonal Frequency Division Multiplexing (OFDM) system is proposed. The correlation item is the training sequence instead of the received signal in the new algorithm. Simulation results show that the performance of the new algorithm is 4dB-9dB better than that of Schmidl's algorithm. Coarse frequency offset estimation is also discussed in this paper, which is the improvement of Zhang's method. The estimation range using the improvement method is twice as that using the Zhang's method. Based on the hardware of the receiver and the improved algorithm, a method using Fast Fourier Transform (FFT) is proposed to implement the coarse frequency estimation. The chip area of OFDM system can be reduced by using the proposed method. 相似文献
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Carrier frequency offset (CFO) in OFDM systems results in loss of channel orthogonality and hence degrades the system's performance. In this paper, we propose a new method for joint CFO/channel estimation for OFDM systems with two receive antennas. Our method avoids the complexity of full search methods in one or two dimensions. Using one training OFDM symbol and utilizing the knowledge of the structure of the inter‐channel interference that results from CFO, we develop a two‐stage estimation procedure. The first stage derives an initial CFO/channel estimate based on a one shot minimization step. The second stage refines this joint estimate by conducting a small CFO search in the vicinity of the initial estimate. This procedure provides CFO estimates over a full range of −N /2–N /2, (N : number of subcarriers), as well as the channel estimates. Computer simulations show an excellent performance that is very close to the Cramer–Rao lower bound and superior to some existing methods. The effect of antenna correlation on performance is also investigated through computer simulations, showing small performance degradation even at medium correlation coefficients (0.3–0.6). Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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分析了OFDM系统信号模型与经典ESPRIT方法所要求的观测向量之间的相合之处,给出了利用经典ESPRIT算法估计OFDM系统载频偏移的方法。然后尝试使用了一种经典ESPRIT算法(TLS—ESPVaT)估计载波频率偏移,仿真结果表明使用该方法比类ESPRIT算法具有更高的估计精度,证明了使用经典ESPRIT方法估计栽波频率偏移的可行性与有效性。 相似文献
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Particle filter with ant colony optimization for frequency offset estimation in OFDM systems with unknown noise distribution 总被引:2,自引:0,他引:2
Orthogonal frequency division multiplexing (OFDM) is sensitive to carrier frequency offset (CFO) that causes inter-carrier interference (ICI). In this paper, a particle filter (PF) method augmented with ant colony optimization (ACO) is developed to estimate the CFO. The ACO for continuous domains is incorporated into PF to optimize the sampling process. Unlike the standard PF, resampling is not required in the method. Moreover, it does not require the noise distribution. Simulation results show that the proposed method is effective when estimating the CFO and can effectively combat the effect of ICI in OFDM systems. 相似文献
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一种时频双选信道下OFDM系统的低复杂度迭代干扰抵消算法 总被引:1,自引:0,他引:1
为了消除正交频分复用(OFDM)系统在时频双选信道条件下由于信道快时变带来的载波间干扰,本文提出了一种新的低复杂度迭代干扰抵消方法.为了消除载波间干扰,已经提出了不少方法,但这些方法要么因为矩阵求逆运算带来了高计算复杂度,要么以性能退化为代价换来低计算复杂度.利用并行迭代干扰抵消技术,本文算法可以明显改善系统性能,同时借助带状矩阵近似和最小二乘QR分解(LSQR)迭代计算的特点来降低计算复杂度.仿真结果表明,在高信噪比条件下,随着迭代次数的增加,本文所提出的算法可以有效的减少"地板效应",在系统性能和计算复杂度之间取得更好的折中. 相似文献
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Zhongshan Zhang Keping Long Yuanan Liu 《Broadcasting, IEEE Transactions on》2004,50(2):159-164
A new carrier frequency offset estimation scheme in the orthogonal frequency division multiplexing (OFDM) system is proposed. The proposed algorithm is an extension of the Michele Morelli (M&M) algorithm. By dividing one training symbol into L>1 identical small blocks, the carrier frequency offset estimation range up to /spl plusmn/L/2 times subcarrier spacing can be obtained. The proposed algorithm can utilize the correlativity among all small blocks of a training symbol more sufficiently than the M&M algorithm, and thus it is more accurate and robust. Without increasing the estimation errors, the computational complexity of the proposed algorithm can be further reduced by increasing parameters H/sub l/ and H/sub h/ with a positive value simultaneously. 相似文献