共查询到18条相似文献,搜索用时 120 毫秒
1.
2.
3.
4.
粒子滤波是一种基于贝叶斯估计的算法,在信道盲辨识和盲均衡问题上具有快收敛、抗深衰信道等优势。Turbo盲均衡在低信噪比条件下有较好的误码性能。为了在深衰信道下使通信具有良好的误码性能,对粒子滤波盲均衡算法进行改进,改进算法的重要性采样函数利用了粒子的先验信息,得到一种软输入软输出的粒子滤波盲均衡算法。依据Turbo盲均衡的框架结构实现了一种基于粒子滤波的Turbo盲均衡算法,该算法利用信道编码带来的编码增益,提高了均衡和信道辨识的性能。仿真结果表明相比粒子滤波盲均衡算法本文提出算法的误码率性能提高1dB左右,误帧率性能则提高了3dB以上,经分析可知在信道系数估计较为准确的条件下,系统数据帧几乎没有误码。 相似文献
5.
信噪比(SNR)是现代通信信号处理中一个重要参数,许多算法需要它作为先验信息以获取最佳估计性能。针对单输入多输出(SIMO)系统的信噪比估计问题,本文提出了一种盲信噪比估计算法。该算法利用多路信号协方差矩阵的奇异值分解(SVD),通过计算矩阵的最大特征值实现各路信号信噪比估计。该算法无需知道信号的先验信息,能够对加性高斯白噪声信道(AWGN)和多径信道下常用的数字调制信号进行信噪比估计。仿真结果表明该算法具有良好的估计性能。与单路信号中基于SVD信噪比估计算法相比,该算法无需估计信号空间与噪声空间维数,提高了估计精度,同时大大减小计算复杂度。 相似文献
6.
7.
在低信噪比情况下,该文提出一种新的针对正交频分复用(OFDM)系统信道阶数和噪声方差的非数据辅助(NDA)估计算法。算法中应用了一种新的基于联合极大几何均值(MGM)的代价函数。新的代价函数不仅利用了循环前缀(CP)冗余性,同时也利用了信道记忆性。对比只利用了CP的方法,该算法可以在低信噪比情况下更准确地估计信道阶数和噪声方差。仿真结果表明,在低信噪比情况下,该算法针对信道阶数的估计得到约10 dB的信噪比增益;同时,对噪声方差的估计,该算法显著提高了估计精度,抑制了信噪比20 dB以下估计性能恶化的现象。 相似文献
8.
针对多用户正交频分复用/空分多址(OFDM/SDMA)系统上行链路多址信道,基于噪声信道提出了一种新的信道有效阶数和信道冲激响应联合估计算法。该算法以最大似然为目标函数,构建了基于差分进化并行搜索信道有效阶数并进行信道冲激响应估计的联合框架。算法引入赤池信息量准则作为搜索阶数最优的评判函数,以提高信道有效阶数和信道冲激响应的估计精度。仿真验证了所提算法的有效性和可靠性,结果表明引入赤池信息量准则(AIC)在降低有效信道阶数估计误差的同时提高了时域最大似然信道估计器的性能。特别地,在误码率为10-5时,所提算法能够获得约1.5 dB的性能增益。 相似文献
9.
根据联合阶数估计最小二乘平滑算法(J-LSS)中投影误差矩阵的特点,利用其零空间向量形成的特殊矩阵的秩与信道阶数的关系,分别构造2个阶数估计代价函数。将2个代价函数归一化后联合构建成新的代价函数,新的代价函数较使用单一代价函数提升了在低信噪比下的辨识率。仿真结果表明,与传统算法相比,该算法在较低的信噪比和小样本观测数据条件下,有很好的估计性能。 相似文献
10.
11.
本文针对异步DS-CDMA系统,在理论上分析了信道阶、信道头和尾对子空间盲特征波形估计算法性能的影响,并进行了计算机仿真.首先提出了一个特征波形分解模型,将特征波形分解为m阶主要部分和次要部分,得到了相应的m阶子空间算法;然后运用矩阵扰动理论,证明了特征波形分解的可行性,即m阶子空间算法的特征波形估计逼近于m阶主要部分;最后从矩阵特征值分解的稳定程度出发,推导了特征波形分解准则,该准则指出应该避免考虑次要部分,采用尽可能小的信道阶.仿真结果验证了理论分析的正确性. 相似文献
12.
本文针对异步DS-CDMA系统,在理论上分析了信道阶、信道头和尾对子空间盲特征波形估计算法性能的影响,并进行了计算机仿真.首先提出了一个特征波形分解模型,将特征波形分解为m阶主要部分和次要部分,得到了相应的m阶子空间算法;然后运用矩阵扰动理论,证明了特征波形分解的可行性,即m阶子空间算法的特征波形估计逼近于m阶主要部分;最后从矩阵特征值分解的稳定程度出发,推导了特征波形分解准则,该准则指出应该避免考虑次要部分,采用尽可能小的信道阶.仿真结果验证了理论分析的正确性. 相似文献
13.
14.
Blind MIMO channel identification from second order statistics using rank deficient channel convolution matrix 总被引:5,自引:0,他引:5
Zhi Ding Li Qiu 《Signal Processing, IEEE Transactions on》2003,51(2):535-544
For multiuser systems, several direct blind identification algorithms require that the linear multiple-input multiple-output (MIMO) system have a full rank convolution matrix. This condition requires that the system transfer function be irreducible and column reduced. We show that this restrictive identification condition can be relaxed for some direct blind identification methods to accommodate more practical scenarios. Algorithms such as the outer-product decomposition algorithm only require minor length adjustment to its processing window without the column-reduced condition. This result allows direct blind identification methods to be applicable to MIMO without requiring a full-rank channel convolution matrix. 相似文献
15.
Blind channel approximation: effective channel order determination 总被引:12,自引:0,他引:12
Liavas A.P. Regalia P.A. Delmas J.-P. 《Signal Processing, IEEE Transactions on》1999,47(12):3336-3344
A common assumption of blind channel identification methods is that the order of the true channel is known. This information is not available in practice, and we are obliged to estimate the channel order by applying a rank detection procedure to an “overmodeled” data covariance matrix. Information theoretic criteria have been widely suggested approaches for this task. We check the quality of their estimates in the context of order estimation of measured microwave radio channels and confirm that they are very sensitive to variations in the SNR and the number of data samples. This fact has prohibited their successful application for channel order estimation and hits created some confusion concerning the classification into under- and over-modeled cases. Recently, it has been shown that blind channel approximation methods should attempt to model only the significant part of the channel composed of the “large” impulse response terms because efforts toward modeling “small” leading and/or trailing terms lead to effective overmodeling, which is generically ill-conditioned and, thus, should be avoided. This can be achieved by applying blind identification methods with model order equal to the order of the significant part of the true channel called the effective channel order. Toward developing an efficient approach for the detection of the effective channel order, we use numerical analysis arguments. The derived criterion provides a “maximally stable” decomposition of the range space of an “overmodeled” data covariance matrix into signal and noise subspaces. It is shown to be robust to variations in the SNR and the number of data samples. Furthermore, it provides useful effective channel order estimates, leading to sufficiently good blind approximation/equalization of measured real-world microwave radio channels 相似文献
16.
Adriana Dapena Hctor J. Prez‐Iglesias Vicente Zarzoso 《Wireless Communications and Mobile Computing》2012,12(6):516-528
The popular Alamouti orthogonal space time code attains full transmit diversity in multiple antenna systems. This paper addresses the problem of blind channel identification in (2 × 1) Alamouti coded systems. Under the assumption of independent symbol substreams, the channel can be estimated from the eigendecomposition of matrices composed of second‐ or higher‐order statistics (cumulants) of the received signal. The so‐called joint approximate diagonalization of eigenmatrices (JADE) method for blind source separation via independent component analysis is optimal in that it tries to simultaneously diagonalize a full set of fourth‐order cumulant matrices. To reduce computational complexity, we perform the eigenvalue decomposition of a single cumulant matrix, which is judiciously chosen by maximizing its expected eigenvalue spread. Simulation results show that the resulting technique outperforms existing blind Alamouti channel estimation methods and achieves a performance close to JADE's at a fraction of the computational cost. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
17.
提出一种新的基于子空间分解的信道阶数估计算法.首先基于子空间分解,将观测向量自相关矩阵的几何子空间按照某一正整数La分解为“信号”子空间和“噪声”子空间,由“噪声”子空间构建了一个特殊矩阵Gv,提出了Gv特征分析定理,该定理表明当且仅当La等于信道阶数时,Gv奇异并有唯一的零特征值,并进行了详细的理论和实验证明;然后根据该定理,不断修正“噪声”子空间的大小,判定Gv的奇异性,完成信道阶数的估计.仿真证明该算法不但在低信噪比条件下具有很好的估计性能,而且当信道具有较小的初始和结尾系数时,也能达到很好的效果. 相似文献