Joint estimation of DOA, frequency, and polarization based on cumulants and UCA

A joint estimation algorithm of direction of arrival （DOA）, frequency, and polarization, based on fourth-order cumulants and uniform circular array （UCA） of trimmed vector sensors is presented for narrowband non-Gaussian signals. The proposed approach, which is suitable for applications in arbitrary Gaussian noise environments, gives a closed-form representation of the estimated parameters, without spectral peak searching. An efficient method is also provided for elimination of cyclic phase ambiguities. Simulations are presented to show the performance of the algorithm.

Resolution performance analysis of cumulants-based rank reduction estimator in presence of unexpected modeling errors

Compared to the rank reduction estimator （RARE） based on second-order statistics （called SOS-RARE）, the RARE employing fourth-order cumulants （referred to as FOC-RARE） is capable of dealing with more sources and mitigating the negative influences of the Gaussian colored noise. However, in the presence of unexpected modeling errors, the resolution behavior of the FOC-RARE also deteriorate significantly as SOS-RARE, even for a known array covariance matrix. For this reason, the angle resolution capability of the FOC-RARE was theoretically analyzed. Firstly, the explicit formula for the mathematical expectation of the FOC-RARE spatial spectrum was derived through the second-order perturbation analysis method. Then, with the assumption that the unexpected modeling errors were drawn from complex circular Gaussian distribution, the theoretical formulas for the angle resolution probability of the FOC-RARE were presented. Numerical experiments validate our analytical results and demonstrate that the FOC-RARE has higher robustness to the unexpected modeling en＇ors than that of the SOS-RARE from the resolution point of view.

Performance of cumulant-based rank reduction estimator in presence of unexpected modeling errors

Compared with the rank reduction estimator(RARE) based on second-order statistics(called SOS-RARE), the RARE based on fourth-order cumulants(referred to as FOC-RARE) can handle more sources and restrain the negative impacts of the Gaussian colored noise. However, the unexpected modeling errors appearing in practice are known to significantly degrade the performance of the RARE. Therefore, the direction-of-arrival(DOA) estimation performance of the FOC-RARE is quantitatively derived. The explicit expression for direction-finding(DF) error is derived via the first-order perturbation analysis, and then the theoretical formula for the mean square error(MSE) is given. Simulation results demonstrate the validation of the theoretical analysis and reveal that the FOC-RARE is more robust to the unexpected modeling errors than the SOS-RARE.

Joint frequency, 2D AOA and polarization estimation using fourth-order cumulants

Based on fourth-order cumulant and ESPRIT algorithm, a novel joint frequency, two-dimensional angle of arrival (2D AOA) and the polarization estimation method of incoming multiple independent spatial narrow-band non-Gaussian signals in arbitrary Gaussian noise environment are proposed . The array is composed of crossed dipoles parallel to the coordinate axes. The crossed dipole positions are arbitrarily distributed. Computer simulation confirms its feasibility.

Array gain of fourth-order cumulants beamforming under typical probability density background

The fourth-order cumulant of zero mean Gaussian distribution noise always equals to zero theoretically. In practice the probability density of noise and reverberation is the key problem to performance of the fourth-order cumulant beamforming technique. In this paper, the array gain functions of the fourth-order cumulant beamforming are deducted considering the instantaneous amplitude distribution of the ambient sea noise and bottom reverberation respectively. And the relationships are determined between array gain and the factors including the number of the array elements, the fourth-order and second-order statistical properties of the noise and reverberation, and the input signal-to-noise ratio. It is also verified that there is a critical signal-to-interference ratio and the fourth-order cumulant beamforming can obtain higher gain and resolution than the conventional beamforming method when the ratio is larger than it. The results of experiment data processing demonstrate that the gain and the resolution of the fourth-order cumulant beamforming coincide with the theoretic.

色噪声下双基地MIMO雷达DOD和DOA联合估计

针对双基地多输入多输出(multiple-input multiple-output,MIMO)雷达在色噪声环境中的收发角度估计问题,提出了一种基于改进四阶累积量的角度估计算法。该算法首先构造回波信号的四阶累积量矩阵,然后根据四阶累积量矩阵的形成规律,在保证虚拟阵列孔径有效扩展的前提下去除其中的冗余项,达到矩阵降维的目的。最后将降维后的矩阵特征分解得到噪声子空间,再利用四阶累积量的多重信号分类(multiple signal classification,MUSIC)算法实现最终的收发角度估计。所提算法不仅可以有效抑制高斯色噪声,并且能够减小四阶累积量矩阵的维数,降低计算的复杂度,仿真结果验证了该算法的有效性。

用逐步扩展法处理输电网规划中不确定性因素

输电网规划中不可避免地会涉及大量规划人员控制或预料之外的不确定性因素,合理的规划方法是将处理不确定性因素的方法与最优方法有机结合。针对电力市场环境下输电网规划面临大量不确定因素的影响,结合逐步扩展法,提出了采用半不变量法处理输电网规划中的不确定性因素。改进的"19节点系统"验证了所提方法的可行性。计算结果表明:所提方法的特点是计算速度快、且不存在不收敛问题。

Hierarchical space–time block codes signals classification using higher order cumulants

An efficient method for blind classification of space time block codes （STBCs） based on fourth-order cumulants is proposed for a single receiver antenna. This paper presents a model of received STBCs signals in multiple input single output （MISO） communication systems and applies the characteristics of coding matrices to derive analytical expressions for the fourth-order cumu- lants to be used as the basis of an algorithm. The fourth-order cumulants at various delay vectors present non-null values that depend on the transmitted STBCs. Tests of nullity are accomplished by hypothesis testing. The proposed algorithm avoids the need for a priori information of modulation scheme, channel coefficients, and noise power. Consequently, it is well suited for non-cooperative scenarios. Simulations show that this method performs well even at low signal-to-noise ratios （SNRs）.

村镇用地扩张损益模型及土地适宜性评价——以五大连池镇为例

为科学辨识土地自然和社会经济属性,综合评定其适建水平、质量高低及其限制状况,立足于损益分析视角以五大连池为例,借助RS与GIS技术,从空间区位、自然地理、社会经济、生态保护4个方面构建17个因子的用地扩低张阻力赋值体系,应用最小累积阻力模型模拟村镇建设用地扩张与生态用地覆盖过程,探讨空间土地利用动态演变的潜在趋势,据此通过损益模型划定镇域空间适建类型,进行土地适宜性评价.结果表明,五大连池镇Ⅰ类(高适宜建设区)、Ⅱ类(较为适宜建设区)、Ⅲ类(较为不适宜建设区)、Ⅳ类(不适宜建设区)用地面积为41.01、138.97、387.85、492.26 km2,分别占镇域面积的3.86%、13.11%、36.59%、46.44%,划分结果可为镇域土地适宜性评价及空间管制规划提供辅助判别的技术方法.

An Array Extension Method in a Noisy Environment

An array extension method in a noisy environment was proposed to improve angular resolution and array gain. The proposed method combines the FOC （fourth-order cumulants） technique with the ETAM （extended towed array measurements） method to extend array aperture and suppress Gaussian noise, First, successive measurements of a virtual uniform linear array were constructed by applying lburth-order cumulants to measurements of uniform linear array; Gaussian noise in these measurements was also eliminated. Then, the array was extended by compensating phase differences using the ETAM method, Finally, the synthetic aperture was extended further by the fourth-order cumulants technique. The proposed FOC-ETAM-FOC method not only improves angular resolution and array gain, but also effectively suppresses Gaussian noise. Furthermore, it inherits the advantages of the ETAM method. Simulation results showed that the FOC-ETAM-FOC method achieved better angular resolution and array gain than the ETAM method. Furthermore this method outperforms the ETAM method in Gaussian noise environment.

JOINTLY ESTIMATING BOTH RANGE AND DOA OF NEAR FIELD SOURCE

A computationally efficient method for jointly estimating both Directions Of Arrival (DOA) and ranges of near field sources is presented. The proposed algorithm does not need any spectral peak searching and the 2-D parameters are automatically paired. It is suitable for arbitrary additive Gaussian noise environment. Furthermore, its performances are confirmed by computer simulations.

基于动态语音源数的自适应盲源分离算法

针对特定场合中语音信号源数动态变化的不确定性盲源分离问题,提出了拓展四阶累积量矩阵估计语音信号源数的自适应方法.该方法克服了传统盲源分离方法中事先假定已经确定语音信号源个数的前提下才能进行盲分离的不足,仅根据观测语音信号数与源信号数目的关系,自适应地选择盲源分离算法实现语音信号的分离.仿真实验结果表明,该语音源数估计的自适应盲源分离算法能有效地实现超定、适定与欠定情况下的语音信号的分离,而且分离效果及鲁棒性都较好.

创新能力培养案例——二叉累计运算树及其拓展应用

提升大学生创新能力是国家新世纪人才培养的方向。提出了二叉累计运算树概念,并用实例说明其使用于二元累计运算中,还可以拓展应用于十进制到二(八、十六)进制的转换中。

Estimation method of DOA for DS-UWB signal

Direction of arrival(DOA)estimation is one of the key technologies in smart antennas in the direct sequence ultra wideband(DS-UWB)system.Traditional DOA estimation methods based on narrow-band signals are not suitable for such system.Therefore,a fourth-order cumulant-based estimation method of DOA for DS-UWB signal is proposed.This method is set on the frequency domain model of DS-UWB array signal.Simulation results show that the algorithm is effective and can guarantee adequate estimation accuracy.