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纠错码是提高信息传输效率与可靠性的重要手段.构造性能良好的线性码类是纠错码研究中的一个基本问题.本文主要讨论了有限非链环Fq[v]/(vm-v)上自对偶常循环码的代数结构,包括Euclidean自对偶常循环码、Hermitian自对偶常循环码以及Hermitian自对偶常循环码的极大距离可分(MDS)码.本文给出了环Fq[v]/(vm-v)上常循环码是Euclidean自对偶码的充分条件,以及是Hermitian自对偶码的充要条件,并利用Gray映射构造了有限域Fq上一些参数较好的自对偶码.特别地,本文得到了有限域F192上一个新的参数为[16,8,6]的Hermitian自对偶码. 相似文献
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最近,剩余类环上的常循环码及常循环自对偶码引起了编码学者的极大关注.本文首先利用一些相关的线性码,建立了一类特殊有限链环上长为N的常循环自对偶码的一般理论,利用其结果给出了该环上长为N的(1+uλ)-常循环自对偶码存在的充分条件,得到了该环上长为N的一些常循环自对偶码,并给出了其生成多项式. 相似文献
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研究了环F4+uF4与域F4上的线性码,利用环F4+uF4上码C的Gray重量wG,Gray距离d G和(F4+uF4)n到F4 2n的Gray映射φ,证明了环F4+uF4上线性码C及其对偶码的Gray像φ(C)为F4上的线性码和对偶且dH G(φ(C))dG(C)。同时,给出了F4+uF4上循环码C的Gray像φ(C)为F4上的2-拟循环码。 相似文献
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研究码字的距离分布是编码理论的一个重要研究方向。该文定义了环R=F2+uF2++uk-1F2上的Homogeneous重量,研究了环R上长为2s的(1+u)-常循环码的Hamming距离和Homogeneous距离。使用了有限环和域的理论,给出了环R上长为2s的(1+u)-常循环码和循环自对偶码的结构和码字个数。并利用该常循环码的结构,确定了环R上长为2s的(1+u)-常循环码的Hamming距离和Homogeneous距离分布。 相似文献
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提出循环码的一种盲识别方法。在码字起点已知的条件下,分析循环码码重分布特点,基于码重分布概率方差识别码长;根据码重分布统计结果选择最佳的码字,求其循环移位后码多项式的公因式,最后通过判决关系识别生成多项式完成循环码的盲识别。仿真实验表明该方法对误码率在10-2时的循环码具有较好的识别效果。 相似文献
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无线定位的圆-角定位技术中,DOA估计极其重要。本文针对基于TD-SCDMA智能天线预处理后的虚拟均匀线阵MUSIC算法带来的阵列孔径小,抗阵元误差扰动性差的不足,研究了基于模式空间虚拟均匀线阵四阶累量的MUSIC算法,由于虚拟线阵四阶累量MUSIC算法的应用范围局限于独立的信号源的DOA估计,不能用于相关信号源DOA估计,因而提出了基于模式空间虚拟均匀线阵四阶累量的修正MUSIC(FOC-MMUSIC)算法,有效地拓展了阵元孔径,改善了系统抗阵元误差扰动和算法对相关信号源DOA的估计性能。 相似文献
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Direction finding algorithms based on high-order statistics 总被引:9,自引:0,他引:9
Two direction finding algorithms are presented for nonGaussian signals, which are based on the fourth-order cumulants of the data received by the array. The first algorithm is similar to MUSIC, while the second is asymptotically minimum variance in a certain sense. The first algorithm requires singular value decomposition of the cumulant matrix, while the second is based on nonlinear minimization of a certain cost function. The performance of the minimum variance algorithm can be assessed by analytical means, at least for the case of discrete probability distributions of the source signals and spatially uncorrelated Gaussian noise. The numerical experiments performed seem to confirm the insensitivity of these algorithms to the (Gaussian) noise parameters 相似文献
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基于MUSIC和ESPRIT的双基地MIMO雷达角度估计算法 总被引:7,自引:3,他引:4
该文基于2阶和4阶统计量,提出了空间高斯白噪声和高斯色噪声的背景下联合MUSIC和ESPRIT的双基地MIMO雷达角度估计算法。在接收端,通过单天线的MUSIC算法和双天线的ESPRIT算法分别估计目标的离开方向(Direction Of Departure, DOD)和波达方向(Direction Of Arrival, DOA),且DOD和DOA自动配对。该方法充分利用了MIMO雷达阵列孔径扩展的特征和ESPRIT的子空间旋转不变性,将2维参数估计问题转化为两个1维形式,降低了运算量和系统复杂度。计算机仿真验证了该方法的有效性。 相似文献
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当独立信号和相干信号共存时,传统四阶累积量方法无法估计出宽带相干信号的来波方向(DOA),针对这个问题提出了一种新方法。该方法首先通过离散傅里叶变换,将宽带阵列接收数据分解为若干个窄带信号,构造出各个窄带频率处的自相关矩阵,再通过MUSIC(Multiple Signal Classification)算法估计出各个窄带信号的DOA,将各个窄带信号的空间谱相加求平均,通过谱峰搜索得到宽带独立信号的DOA;然后分离出独立信号的信息,构造出一个只包含宽带相干信号信息的矩阵,最后通过稀疏重构的方法估计出相干信号的DOA。计算机仿真结果证明该算法的正确性和有效性。 相似文献
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In the narrow-band array processing context, the use of higher order statistics has been often advocated because consistent and asymptotically unbiased parameter estimates can be obtained without it being necessary to know, to model, or to estimate the spatial covariance of the noise as long as it is normally distributed. However, experimentation shows that this `noise insensitivity' is traded for increased variability of the parameter estimates. The main purpose of this contribution is to derive and work out closed-form expressions of the asymptotic covariance of MUSIC-like direction-of-arrival estimates based on two fourth-order cumulant matrices: the diagonal slice and the contracted quadricovariance. This is compared with the standard covariance-based MUSIC estimate establishing on a rational basis the domain of applicability of higher order statistics for DOA estimation. In particular, the actual impact of the noise variance and of the dynamic range of the sources is investigated. This asymptotic performance analysis is achieved within a general framework, which we believe to be of general interest 相似文献
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Consideration is given to the analysis of the large-sample second-order properties of multiple signal classification (MUSIC) and subspace rotation (SUR) methods, such as ESPRIT, for sinusoidal frequency estimation. Explicit expressions for the covariance elements of the estimation errors associated with either method are derived. These expressions of covariances are then used to analyze and compare the statistical performances of the MUSIC and SUR estimation (SURE) methods. Both MUSIC and SURE are based on the eigendecomposition of a sample data covariance matrix. The expressions for the estimation error variances derived are used to study the dependence of MUSIC and SURE performances on the dimension of the data covariance matrix used 相似文献
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Herein, we estimate the direction of arrival (DOA) of non-Gaussian signals for nested arrays (NAs) by implementing the fourth-order difference co-array (FODC) and successive methods. In particular, considering the property of the fourth-order cumulant (FOC), we first construct the FODC of the NA, which can obtain O(N4) virtual elements using N physical sensors, whereas conventional FOC methods can only obtain O(N2) virtual elements. In addition, the closed-form expression of FODC is presented to verify the enhanced degrees of freedom (DOFs). Subsequently, we exploit the vectorized FOC (VFOC) matrix to match the FODC of the NA. Notably, the VFOC matrix is a single snapshot vector, and the initial DOA estimates can be obtained via the discrete Fourier transform method under the underdetermined correlation matrix condition, which utilizes the complete DOFs of the FODC. Finally, fine estimates are obtained through the spatial smoothing-Capon method with partial spectrum searching. Numerical simulation verifies the effectiveness and superiority of the proposed method. 相似文献