乘性噪声背景下基于三阶循环矩的二维近场源定位方法

 本文提出一种基于三阶循环矩的近场源二维参数估计方法.该方法以均匀线阵为接收传感器阵列,通过构造三个三阶循环矩矩阵估计出近场源的方位角和距离参数,利用循环统计量去除加性噪声,通过预校准法消除乘性噪声,适用于乘性噪声或乘性噪声和加性噪声共存背景下的二维近场源定位.仿真实验验证了该方法的有效性.     

一种基于二阶统计量的近场源三维参数估计方法

该文研究近场源的距离、角度和频率的三维参数估计问题。提出了一种仅需利用二阶统计量和相应的配对程序就能直接估计出参数的新方法。该方法无需谱峰搜索,同时避免应用四阶累积量,减轻了算法的计算量。仿真实验证明了该算法的有效性。     

基于二阶统计量的四维近场源定位

本文针对近场窄带信源频率、仰角、方向角和距离四维参数的估计问题，提出了一种基于二阶统计量的近场源四维参数估计方法。该方法利用中心对称的十字阵列和多重旋转矢量不变技术估计信源参数，无需谱峰搜索，同时避免应用四阶累积量，减轻了算法的计算量。仿真实验证明了该算法的有效性。     

基于二阶统计量的近场定位新方法

该文针对近场源的方向角和距离的二维参数估计,提出了一种新的近场源二维参数估计方法。该方法利用双极化阵列的极化信息和二阶统计量估计近场源的波达方向和距离参数。该方法具有估计精度高和无需谱峰搜索的优点。仿真实验证明了该算法的有效性。     

冲击噪声背景下宽频段信号的多维参数估计

提出了一种基于协变异矩阵的宽频段信号频率、二维到达角和极化参数联合估计的算法.该算法利用非均匀L型极化敏感阵列的时空数据构造了一个时空协变异矩阵,通过对其进行特征分解,并利用分解得到的特征值和特征矢量估计出宽频段信号的多维参数.在冲击噪声环境下,该算法能够精确地估计信号的多维参数,无需多维谱峰搜索和参数配对过程,并具有较好的信源参数兼并能力.计算机仿真结果验证了算法的有效性.     

一种冲击噪声环境中的二维DOA估计新方法

该文提出了一种新的在冲击噪声环境中基于阵列输出信号分数低阶矩的二维测向方法稳健的协变异波达方向矩阵法。该方法利用冲击噪声和SS过程的特点,扩展了原波达方向矩阵法的信号模型和应用环境,对冲击噪声有较好的抑制作用,增强了算法的通用性和稳健性,弥补了传统的基于二阶或高阶统计量的子空间测向算法不能应用于冲击噪声环境的不足,计算机仿真验证了该算法的可行性和有效性。     

冲击噪声背景下相干信号源的DOA估计方法

针对冲击噪声背景下相干信号源的波达方向(Direction of Arrival,DOA)估计问题,提出一种基于时延分数低阶矩的分组解相干算法——FLOM-TDD(Fractional Lower Order Moment Time Delay Decorrelation)。首先基于两个时延不同的分数低阶矩矩阵,利用DOA矩阵方法得到每组相干源的广义导向矢量;然后根据多径衰减的特征,对每组相干源进行时域解相干,得到相干源的波达方向估计。该方法适用于冲击噪声背景下的波达方向估计而且可以估计大于阵元数目的相干源,计算机仿真分析验证了算法的性能优势。     

基于旋转干涉仪的近场源参数估计算法

该文基于旋转干涉仪提出了一种新的近场源参数估计算法.该算法利用单个长基线干涉仪的旋转和相位积分实现相位解模糊,有效解决了单基线干涉仪在近场源情况中存在的无模糊视角范围和测角精度之间的矛盾.该算法只需两个接收天线即可得到近场源俯仰角、方位角和距离参数的闭式解,无需构造高阶累积量矩阵和多维搜索,同时也降低了多基线组合对通道一致性的要求.相比于传统的双长基线干涉仪方法,该文算法具有更高的参数估计精度和解模糊能力,具有结构简单、易于工程实现的优点.计算机仿真实验表明了所提算法的有效性和正确性.      

基于双电磁矢量传感器的近场源多参数估计

基于双电磁矢量传感器(EVSs),提出一种新的近场源频率、波达方向(DOA)、距离和极化参数联合估计方法.该方法首先计算近场源的频率以及其在两个电磁矢量传感器处的二维DOA和极化参数,然后利用几何方法或搜索方法,得到近场源的距离估计.该方法仅需要两个电磁矢量传感器,节约了阵列孔径,适合于阵列孔径有限的场合.估计过程中仅需一次互相关以及特征分解等简单的运算,且各参数自动配对,节省了运算量.实验结果验证了该方法的有效性.     

模糊函数在宽带近场源ISM及CSM算法中的应用

为了更好地处理宽带近场源非平稳信号,将模糊函数引进到经典的宽带ISM及CSM算法中,提出了AF-ISM及AF-CSM算法。该算法利用了模糊函数在模糊域内能有效滤除干扰逐一处理信号的优势,将信号与噪声、交叉项分离,从而达到对宽带近场源信号各参数进行估计的目的。为了验证算法的优越性,本文对其进行了仿真实验,并对实验结果进行了分析。     

近场源DOA、距离和极化参数联合估计新算法

研究近场源波达方向(DOA)、距离和极化参数联合估计问题.利用特殊的线性极化阵列,提出一种基于三阶循环矩的新方法.该方法利用信号的循环平稳特性以及空、时域信息,通过时空矩阵的构造和特征分解获得各参数的闭式解.估计过程中无需谱峰搜索,并且能够抑制任意分布的加性平稳噪声以及具有不同循环频率的干扰信号.计算机仿真实验验证了该方法的有效性.     

Joint channel and impulsive noise estimation method for OFDM systems

Aiming at the impulsive noise occurring in OFDM systems,an impulsive noise mitigation algorithm based on compressed sensing theory was proposed.The proposed algorithm firstly treated the channel impulse response and the impulsive noise as a joint sparse vector by exploiting the sparsity of both them.Then the sparse Bayesian learning framework was adopted to jointly estimate the channel impulse response,the impulsive noise and the data symbols,in which the data symbols were regarded as unknown parameters.Compared with the existing impulsive noise mitigation methods,the proposed algorithm not only utilized all subcarriers but also did not use any a priori information of the channel and impulsive noise.The simulation results show that the proposed algorithm achieves significant improvement on the channel estimation and bit error rate performance.     

一种改进的电力线通信系统脉冲噪声抑制方法

为了抑制脉冲噪声对电力线正交频分复用（OFDM）通信系统的影响,最常用的方法之一是在接收端OFDM解调器之前前置一个置零非线性单元,即传统置零法。然而,由于引入了非线性失真,其性能并不理想。针对传统置零法引起的非线性失真问题,提出了一种基于迭代消除非线性失真的改进置零法。首先,对接收到的时域OFDM信号进行脉冲噪声检测和置零处理;然后,在频域利用已检测的符号来重构时域置零处理引入的非线性失真,并通过迭代提高重构的准确性;最后,从频域接收信号中减去重构的非线性失真。仿真结果表明,所提改进算法与传统置零法相比,有非常大的性能提升,增强了电力线OFDM通信系统对脉冲噪声的抵抗能力。     

Stable adaptive channel estimation method under impulsive noise environments

Channel estimation is one of the key technologies for ensuring reliable wireless communications under impulsive noise environments. This paper studies robust adaptive channel estimation methods for mitigating harmful impulsive noises, which are described as alpha‐stable (α ‐stable) distribution models. Traditional adaptive channel estimation using the second‐order statistics based least mean square (SOS‐LMS) algorithm does not perform well under α ‐stable noise environments, even though it was considered one of attractive approaches for estimating channels in the case of Gaussian noises. Unlike the traditional SOS‐LMS algorithm, in this research, we propose a stable sign‐function‐based LMS algorithm, which can mitigate the impulsive noises. Specifically, we first construct the cost function with minimum ℓ ₁‐norm error criterion and then derive the updating equation of the proposed algorithm. Compared with the traditional SOS‐LMS, the effectiveness of the proposed algorithm is validated via Monte Carlo simulations in various α ‐stable noise scenarios. Copyright © 2015 John Wiley & Sons, Ltd.     

Time‐domain equalizer for multicarrier systems in impulsive noise

In multicarrier communication systems, a time‐domain equalizer (TEQ) can be applied to shorten the channel impulse response and to eliminate inter‐symbol interference (ISI). However, the presence of impulsive noise in the channel may paralyze the operation of TEQs and subsequently lead to poor error performance. In this paper, a multicarrier receiver that incorporates a constant false alarm rate algorithm and an iterative estimation technique (CFAR‐IET) in conjunction with a TEQ is proposed to increase the robustness of the receiver against impulsive noise. Furthermore, an improved version of the CFAR‐IET‐TEQ scheme, which uses the buffering, sorting, removing and amplitude averaging (BSRA) processes, is presented. Performance comparisons of the proposed schemes with the existing Gaussian‐optimized schemes are made. Simulation results show that the BSRA‐IET‐TEQ scheme is an effective approach to reduce symbol error rate (SER) in impulsive channels while performing satisfactorily in Gaussian channels. Copyright © 2011 John Wiley & Sons, Ltd.     

一种适用于强脉冲噪声下的对数型恒模盲均衡算法

针对脉冲噪声下恒模算法(Constant Modulus Algorithm,CMA)失败的问题,通过分析脉冲噪声的影响,提出了一种基于最小均方（Least Mean Square,LMS）准则的对数型恒模算法（Logarithmic-type CMA,LT-CMA）。LT-CMA利用对数函数的非线性变换特性自适应地抑制强脉冲噪声对误差函数的影响,并且利用l2-范数进行信号归一化处理以增强算法的稳健性。仿真结果表明,所提出的LT-CMA可以适应于高斯噪声环境和脉冲噪声环境;与经典自适应均衡算法相比,在收敛速度和稳健性两方面上,所提出的LT-CMA都有显著的提升。     

Theoretical analysis of iterative signal reconstruction for impulsive noise mitigation in OFDM systems

In this paper a theoretical analysis of the iterative signal reconstruction algorithm for impulsive noise mitigation in orthogonal frequency‐division multiplexing (OFDM) systems is developed. The following main results are developed: first, analytical model for the total noise in the frequency domain, and second the model for the total noise probability density function (pdf) in the frequency domain, both defined for each step of the iterative reconstruction process. Finally, based on the pdf of the total noise, explicit expressions for BER in kth iteration are defined as well. The main intention of the paper is to present the approach to theoretical analysis of the iterative impulsive noise mitigation algorithm that has not yet been appeared in the literature, because the theoretical analysis of the noise pdf during iterations has been considered as too complex a problem. Analyses and analytical results presented in the paper are given for scenario with a fixed number of noise impulses per frame. However, this is not a handicap of the proposed approach, since all presented models can be used as building blocks for scenarios with other impulsive noise distributions including Bernoulli–Gaussian and Middleton's Class A. Copyright © 2009 John Wiley & Sons, Ltd.