共查询到18条相似文献,搜索用时 156 毫秒
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RLS算法自适应信道估计的性能分析 总被引:2,自引:1,他引:1
文中首先介绍了基本的RLS算法,分析了RLS算法中的初始化系数δ和遗忘因子λ对RLS算法收敛性能的影响。通过仿真可以看出,在相同的信噪比下,不同的δ对应不同的收敛性能。而不同的λ对收敛性能也有较大的影响。 相似文献
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通过时LMS和RLS自适应算法在无人机数据链路不同信道特性均衡中的应用进行研究,得出了两种均衡算法在对于不同信道均衡效果的差异,给出了两种均衡算法的最佳应用条件。 相似文献
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基于LMS及RLS的自适应均衡算法仿真分析 总被引:2,自引:0,他引:2
在通信系统中采用均衡技术是改善信道特性行之有效的方法,为此从时域均衡原理出发,讨论了基于LMS和基于RLS的自适应均衡算法,并利用Matlab对两类算法进行了仿真,从均衡前后信号的星座图、算法收敛特性以及均衡前后系统的误码特性这三个方面对两类算法的性能进行了比较. 相似文献
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简要介绍了固定宽带无线接入标准IEEE 802.16以及一种用于信道均衡的自适应算法——指数加权RLS,对判决导引信道均衡技术的原理进行了具体描述。最后分别就两种自适应的均衡算法(LMS、RLS),结合一种具体IEEE 802.16单载波调制系统推荐测试信道进行了仿真,得出RLS算法优于LMS的结论。 相似文献
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本文着重研究了自适应滤波器的重要实现形式——递推最小二乘算法(RLS)的原理,分析了RLS算法在应用中的优点及存在问题。为解决RLS算法收敛速度和稳态误差的矛盾及系统在趋于平稳时跟踪效果差的问题,本文从实现可变遗忘因子和增加自扰动项两个方面介绍了RLS算法的几种改进方法。并将它们应用于复杂电磁环境、强干扰背景下的信号分离中去。通过仿真实验,对RLS算法及其两种改进方法在信号分离中的效果进行了比较,得出可变遗忘因子RLS算法在收敛速度和分离信号的准确性上都具有较好的性能。 相似文献
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传统的MMSE均衡算法需要作信道估计,算法复杂度也很高,采用了一种基于最陡梯度下降的LMS迭代算法,该算法不需要信道估计,也不需要复杂的矩阵逆运算,其算法复杂度远远低于MMSE均衡算法的复杂度。仿真结果表明,该LMS迭代算法的收敛速度比RLS算法的收敛速度稍慢,而误码率与RLS算法相当,但其算法复杂度远远低于RLS算法和传统的MMSE均衡算法。 相似文献
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为了克服弥散信道的影响,改善通信质量,提高传输数据速率,近年来出现了多种解决方案,其中最有效的方法就是采用NLMS算法的自适应信道均衡技术.设计NLMS算法的自适应信道均衡器的关键就是寻找一组最佳的自适应滤波器的长度L和步长因子,使系统误码率最低.基于此,本文提出了一种能有效搜索均衡滤波器参数的方法,并构建了该方法的Simulink仿真平台.通过仿真,搜索寻找到了系统误码性能最佳条件下自适应滤波器的长度和步长,同时分析了自适应均衡器的性能,仿真结果证明了其有效性.该平台为最优自适应弥散信道均衡滤波器的设计提供了一个很好的平台,具有很高的实用价值. 相似文献
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In a high-rate indoor wireless personal communication system, the delay spread due to multipath propagation results in intersymbol interference (ISI) which can significantly increase the transmission bit error rate (BER). Decision feedback equalizer (DFE) is an efficient approach to combating the ISI. Recursive least squares (RLS) algorithm with a constant forgetting factor is often used to update the tap-coefficient vector of the DFE for ISI-free transmission. However, using a constant forgetting factor may not yield the optimal performance in a nonstationary environment. In this paper, an adaptive algorithm is developed to obtain a time-varying forgetting factor. The forgetting factor is used with the RLS algorithm in a DFE for calculating the tap-coefficient vector in order to minimize the squared equalization error due to input noise and due to channel dynamics. The algorithm is derived based on the argument that, for optimal filtering, the equalization errors should be uncorrelated. The adaptive forgetting factor can be obtained based on on-line equalization error measurements. Computer simulation results demonstrate that better transmission performance can be achieved by using the RLS algorithm with the adaptive forgetting factor than that with a constant forgetting factor previously proposed for optimal steady-state performance or a variable forgetting factor for a near deterministic system. 相似文献
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在时变信道下正交频分复用(OFDM)系统中,通过导频辅助,提出基于可变遗忘因子RLS(VFF-RLS)的载波频偏(CFO)估计改进算法。针对传统RLS(CFF-RLS)算法中遗忘因子无法同时满足CFO估计收敛速度和收敛精度的缺陷,本文设计了线性变化遗忘因子(LFF)和非线性变化遗忘因子(NLFF) 两种可变遗忘因子方案来提升CFO估计性能。仿真结果显示:在低信噪比的情形下,基于VFF-RLS算法的CFO估计性能明显优于基于CFF-RLS算法的CFO估计性能。 相似文献
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Seongwook Song Jun-Seok Lim Seong Joon Baek Koeng-Mo Sung 《Vehicular Technology, IEEE Transactions on》2002,51(3):613-616
In this article, the variable forgetting factor linear least squares algorithm is presented to improve the tracking capability of channel estimation. A linear channel model with respect to time change describes a time-varying channel more accurately than a conventional stationary channel model. To reduce the estimation error due to model mismatch, we incorporate the modified variable forgetting factor into the proposed algorithm. Compared to the existing algorithms-exponentially windowed recursive least squares algorithm with the optimal forgetting factor and linear least squares algorithm-the proposed method makes a remarkable improvement in a fast fading environment. The effects of channel parameters such as signal-to-noise ratio and fading rate are investigated by computer simulations 相似文献
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Amit Kumar Kohli Divneet Singh Kapoor 《Circuits, Systems, and Signal Processing》2016,35(10):3595-3618
This paper presents adaptive channel prediction techniques for wireless orthogonal frequency division multiplexing (OFDM) systems using cyclic prefix (CP). The CP not only combats intersymbol interference, but also precludes requirement of additional training symbols. The proposed adaptive algorithms exploit the channel state information contained in CP of received OFDM symbol, under the time-invariant and time-variant wireless multipath Rayleigh fading channels. For channel prediction, the convergence and tracking characteristics of conventional recursive least squares (RLS) algorithm, numeric variable forgetting factor RLS (NVFF-RLS) algorithm, Kalman filtering (KF) algorithm and reduced Kalman least mean squares (RK-LMS) algorithm are compared. The simulation results are presented to demonstrate that KF algorithm is the best available technique as compared to RK-LMS, RLS and NVFF-RLS algorithms by providing low mean square channel prediction error. But RK-LMS and NVFF-RLS algorithms exhibit lower computational complexity than KF algorithm. Under typical conditions, the tracking performance of RK-LMS is comparable to RLS algorithm. However, RK-LMS algorithm fails to perform well in convergence mode. For time-variant multipath fading channel prediction, the presented NVFF-RLS algorithm supersedes RLS algorithm in the channel tracking mode under moderately high fade rate conditions. However, under appropriate parameter setting in \(2\times 1\) space–time block-coded OFDM system, NVFF-RLS algorithm bestows enhanced channel tracking performance than RLS algorithm under static as well as dynamic environment, which leads to significant reduction in symbol error rate. 相似文献
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This paper describes a least squares (LS) channel estimation scheme for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems based on pilot tones. We first compute the mean square error (MSE) of the LS channel estimate. We then derive optimal pilot sequences and optimal placement of the pilot tones with respect to this MSE. It is shown that the optimal pilot sequences are equipowered, equispaced, and phase shift orthogonal. To reduce the training overhead, an LS channel estimation scheme over multiple OFDM symbols is also discussed. Moreover, to enhance channel estimation, a recursive LS (RLS) algorithm is proposed, for which we derive the optimal forgetting or tracking factor. This factor is found to be a function of both the noise variance and the channel Doppler spread. Through simulations, it is shown that the optimal pilot sequences derived in this paper outperform both the orthogonal and random pilot sequences. It is also shown that a considerable gain in signal-to-noise ratio (SNR) can be obtained by using the RLS algorithm, especially in slowly time-varying channels. 相似文献
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Channel estimation is employed to get the current knowledge of channel states for an optimum detection in fading environments. In this paper, a new recursive multiple input multiple output (MIMO) channel estimation is proposed which is based on the recursive least square solution. The proposed recursive algorithm utilizes short training sequence on one hand and requires low computational complexity on the other hand. The algorithm is evaluated on a MIMO communication system through simulations. It is realized that the proposed algorithm provides fast convergence as compared to recursive least square (RLS) and robust variable forgetting factor RLS (RVFF-RLS) adaptive algorithms while utilizing lesser computational cost and provides independency on forgetting factor. 相似文献
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本文给出一种能同时抑制DS-CDMA系统多址干扰(MAI)和窄带干扰(NBI)的盲自适应算法.此方法基于遗忘因子具有自调整器的迭代最小二乘算法(SR-RLS),根据系统的变化自动调整遗忘因子,当系统趋于静态时,遗忘因子趋于1,以提高稳态精度,在动态系统中,遗忘因子减小,使算法能有效的跟踪系统参数.与其它的迭代最小二乘相比,具有较小的稳态误差和良好的动态跟踪能力.文章从理论上分析了算法的收敛性.最后,对算法在静态环境和动态环境中的性能分别进行了仿真分析. 相似文献