WCDMA系统智能天线通道不一致性在线校正方法

研究智能天线通道不一致性的注入校正方法。基于WCDMA移动通信系统智能天线通道的物理层协议标准,提出一种新的注入校正方法。该方法首先采用搜索器估计通道的复增益,然后利用复增益的估计值实现通道不一致性的校正。理论分析和Matlab仿真表明,该注入校正方法能使智能天线的性能得以改善。     

阵列天线通道误差的盲估计

基于特征值分解的高分辨DOA估计算法,在理想阵列天线条件下,性能很好,能够精确估算出信号的方位角。但是当存在噪声扰动和天线自身存在误差时,会严重恶化这一类算法的性能,使其分辨率下降。本文提出了一种盲估计方法,此方法不需要知道信号源的方位角,就能精确估计出阵列天线的通道误差。     

一种基于阵列虚拟平移的互耦自校正算法

阵元间的互耦和相干信源对阵列的DOA(Direction-Of-Arrival)估计性能产生了严重影响.针对这一问题,在应用子空间原理的基础上,利用均匀线阵互耦矩阵的带状循环特性及时称Toeplitz性,并结合阵列虚拟平移,提出了一种阵元互耦条件下的相干信源的波达方向估计新算法.该算法无需阵元的互耦参数信息,就可准确地估计出相干信源的DOA,估计性能优良,而且只需一维搜索,计算量较小.计算机仿真结果验证了该算法的有效性.     

一种针对规则集不一致性的测试数据包选取算法

在防火墙规则集正确性测试中,现有的测试数据包选取算法大多随机选取数据包和从规则顶点选取数据包。然而,这种做法忽略了存在规则不一致性的区域,从而导致不能检测出所有因规则不一致性而产生的配置错误。针对这一情况,提出了一种针对规则集不一致性的测试数据包选取算法。该算法以两条规则为基本单位,计算其不一致性区域。算法不但从规则顶点选取数据包,而且从规则集不一致性区域选取数据包。测试表明,与常见测试数据包选取算法相比,该算法只需增加少量测试数据包,就能检测出所有因规则不一致性而带来的配置错误。     

基于频域均衡的宽带阵列通道校正

通道失配会严重影响阵列天线的性能,需要校正失配.窄带阵列只需在中心频率上校正即可,而宽带阵列因带宽相对较大需要对整个通道特性采取均衡的方法来保证各通道间的幅度和相位一致性.首先建立了失配通道模型,然后介绍了基于最小二乘准则的频域均衡算法,最后通过计算机仿真验证了频域均衡算法的有效性.同时,新算法采用LFM信号作为校正信号,克服了时域校正时校正权值不收敛的问题.     

一种解决视频检索中语义不一致性方法

近年来,领域本体作为实现知识共享的基础已应用于视频语义检索。然而,同一或不同应用或领域知识可能存在多个本体,这些本体之间缺乏对术语使用的约定。这种现状所产生的语义不一致性导致难以实现检索过程中的知识推理和互操作过程的自动化,因而严重影响视频检索的效率和结果。提出一个两层本体结构,把同一或不同领域共享或共用的概念与知识映射到一个上层本体,从而解决多本体间语义上的不一致性,实现本体间知识的共享。并通过应用于视频场景的检索实验,说明该方法是有效和可行的。     

一种快速暗通道去雾算法

基于暗通道的去雾算法计算初始透射率需要进行大量的数据比较,优化透射率时需要计算融合矩阵,这两个过程耗时巨大,使其难以投入实际应用。针对这一问题,提出了一种快速暗通道去雾方法。首先利用分区最小表的数据结构,提高初始透射率的计算速度;接着,在优化透射率时,采用基于形态学梯度的彩色图像边缘检测算法提取图像边缘信息,减少优化范围,再利用边缘信息与像素的空间信息优化透射率,避免计算复杂矩阵,从而加快了优化速度;最后,运用最小可觉差模型补偿前两个步骤导致的图像画质下降,提高图像清晰度。实验证明,快速暗通道去雾算法在保持恢复图像效果基本不变的基础上,很大程度提高了算法速度。     

一种属性不一致性加权的K近邻分类方法

针对传统的K近邻算法在计算样本之间相似度时将每个属性视为同等重要的问题,提出了一种基于推土机距离的方法来计算每个条件属性的权重。首先根据近邻关系划分用于比较一致性的两个分布;之后根据推土机距离设计不一致性评价函数,用于衡量每个属性下各个样本的近邻样本集与这一集合由决策属性细化的等价划分之间的不一致性程度;最后将近邻的不一致性程度转换为相应属性的重要性,用于实现属性加权K近邻分类器。通过在多个数据集上进行实验,该方法对参数的敏感程度低,在多个参数下可以显著提高K近邻的分类精度,并且在多个指标下的表现优于现有的一些分类方法。结果表明,该方法可以通过属性加权选择出更加准确的近邻样本,可广泛应用于基于近邻的机器学习方法中。     

具有双检测通道SISO系统的一种自校正算法

一、前言对于一类工业过程如窑炉等不可能利用热电偶直接测量工件表面温度,间接量测则具有较大的时延和测量误差.采用红外测温计虽然可以直接测量工件表面温度,但具有较大的随机误差.针对这类工业过程的特点,本文试图利用热电偶具有较高的精度以及红外测温计比较敏感的特点,提出了一种基于双通道检测的自校正算法.该算法对双通道     

上下文不一致性检测及消除的研究

在普适计算环境下,由于获得的上下文信息存在不一致性,使得上下文感知应用无法正常进行响应。研究了普适计算环境下的上下文不一致性的检测及消除,针对其提出了基于置信度数据库的反馈机制,并且丰富和扩展了上下文不一致性的消除算法。实现了相关算法,并通过实验给出了各个算法的效率和正确性的比较。     

A versatile pattern synthesis algorithm for circular antenna array

This article presents a versatile pattern synthesis algorithm for controlling the sidelobe level and nulling region for circular antenna arrays. Nonuniform fast Fourier transform using the min–max interpolation method is utilized to overcome the nonlinear feature of circular arrays. The major advantage of the proposed algorithm is low complexity, which is key for hardware implementation. Moreover, the proposed algorithm functions well in amplitude‐only pattern synthesis, which may be required for low‐cost array systems using attenuators instead of complete amplitude and phase adjustment modules. Additionally, element failure of antenna arrays can be minimized in practical operations by resynthesizing the pattern by using the remaining antennas to achieve satisfactory performance. Simulation results indicate the lower complexity and higher versatility of the proposed algorithm compared with the conventional methods.     

Design of a linear array antenna for shaped beam using genetic algorithm

A linear array antenna design with desired radiation pattern has been presented based on genetic algorithm (GA) approach. Examples of cosecant and flat‐topped beam patterns are illustrated to show the flexibility of GA to solve complex antenna synthesis problems by suitably selecting the fitness function, even with a simple GA. The results have been validated by IE3D electromagnetic simulation. The antenna arrays with different element geometries can also be implemented using the proposed technique. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Near optimal conformal antenna array structure for direction‐of‐arrival estimation

This article determines the near optimal conformal antenna array structure for direction‐of‐arrival (DOA) estimation through a comprehensive study on the planar and usual conformal antenna arrays including the cylindrical and hemispherical by using the directive antenna elements in all designs. To model the hemispherical structure, an improved multi‐face antenna array with three different tilts is proposed and compared with previous works in order to investigate the tilt effect and obtain the conclusive results. The Cramer‐Rao lower bound, multiple signal classification, and root‐mean‐square error algorithms are utilized to evaluate the estimation accuracy of all conformal structures. Finally, by comparing the estimation precision of all conformal structures it is shown that the purposed multi‐face structure as the hemispherical model has a better performance than other conformal structures in terms of the maximum angular coverage of the spatial resource. Moreover, the proposed study method in this article fully examines the impacts of the different conformal antennas geometric structure on the DOA estimation performance by involving the directive antennas radiation patterns.     

Pattern synthesize of a cylindrical conformal array antenna by PSO algorithm

Pattern synthesize of conformal array antennas is often a challenging problem. Various optimization algorithms such as genetic, particle swarm optimization (PSO), and invasive weed optimization have already been used for pattern synthesizing of conformal arrays. In this paper, a focused beam is synthesized for a quarter cylindrical conformal array antenna using the PSO algorithm with small computations. The desired pattern is a focused beam at θ = 90° and ? = 45° with 10° beamwidth in elevation and 15° beamwidth in azimuth with ?20 dB side‐lobe level. This method can be used in general for synthesizing arbitrary desired patterns and array geometries.     

A linear antenna array failure correction using improved bat algorithm

The failure of antenna array elements causes disturbance in the sidelobe power level. In this article, an improved flexible approach that use bat algorithm is proposed and applied to solve the problem of antenna array failure by controlling only the amplitude excitation of array elements. An adaptive inertia weight approach is applied to the standard bat algorithm to improve the quality of the solution and the speed of convergence. The effectiveness of the proposed improved bat algorithm (IBA) is verified on different standard test functions. Numerical examples of element failure correction are presented to show the capability of this flexible approach in antenna array failure correction.     

Dielectric resonator array antenna for triple band WLAN applications with enhanced gain

An H‐shaped dielectric resonator array antenna is presented for wideband applications. The proposed antenna is excited by slot feed mechanism and investigated experimentally. The antenna covers the frequency ranges from 1.41 to 2.59 GHz, and 4.73 to 6.06 GHz with the corresponding impedance bandwidth of 59% and 24.65%, respectively. The simulation results fulfill the bandwidth requirements of IEEE 802.11a/b/g (2.4‐2.484 GHz/5.15‐5.35 GHz/5.725‐5.825 GHz) for Wireless local area network (WLAN) applications. The proposed antenna has simple structure, easy to fabricate and its measured radiation pattern shows a reliable performance in the desired operating bands.     

带内拟合宽带阵列通道误差校正方法

在整个第一Nyquist域进行宽带自适应阵列天线的幅相误差校正时,由于带宽宽,需要的横向滤波器阶数非常高。为了减少滤波器阶数,新方法仅仅对信号带宽内的幅相误差进行校正,采用最小二乘拟合的最优化准则,获得校正滤波器的实系数。同时,通过增加一个前置带通滤波器,保证带外噪声控制在可接受范围内。相对传统方法,该设计在相同滤波器阶数情况下,可以提高带内校正精度。通过对实际MSK信号下的阵列校正实验,证明了新方法的有效性。     

一种高增益宽频带圆极化微带阵列天线的研制

针对微带天线阻抗匹配带宽一般较窄的自身缺陷,基于相控阵雷达天线的应用背景,设计了一种工作在X波段的双层圆极化微带天线结构,且优化发现,其各电磁参数良好。为提高其增益,还在此基础上设计并最终制作了双层2×2结构的微带天线阵列,其实测性能与设计值相符,增益达到10.7dB,带宽1.2GHz,相应轴比为4dB,符合圆极化要求。     

Antipodal tapered slot antenna array using broadband decoupling structure for mutual coupling reduction

In this article, an effective method to reduce the mutual coupling between the antipodal tapered slot antenna (ATSA) array is proposed. This method is mainly implemented by loading a set of decoupling structures (DS) perpendicular to the dielectric substrate between two antenna elements. The proposed DS can provide transmission forbidden band which can effectively prevent leaked electromagnetic waves. DS can operate in most frequency bands within 4 to 17.5 GHz. It can enhance about 23 dB isolation between the ATSA array without affecting bandwidth and radiation characteristics. The proposed ATSA arrays are fabricated and tested. The measured results can verify its excellent properties. The proposed broadband decoupling method is a suitable candidate for restrain mutual coupling of ultra‐wideband planar end‐fire antennas. This design sheds new light on broadband decoupling.     

Circularly polarized slot antenna array with sequentially rotated feed network for broadband application

This article presents a novel circularly polarized sequentially rotated slot antenna array (CPSSAA) designed to operate at a frequency of 5.5 GHz. This antenna is suitable for communication applications such as WLAN/WiMAX. Method of feeding is based on sequential rotation with seven quarter‐wavelength transformers. In this case, the elements with 200 Ω impedance could be replaced by other elements with different input impedance. Reducing the elements input impedance, maximum power can be transferred to the elements. Because the lower losses in transmission line occur in presence of lower impedance, the 3 dB axial‐ratio bandwidth of the CPSSAA extends to ～1.3 GHz. The CPSSAA was designed to operate over the frequency range between 4.5 and 6.4 GHz corresponding to an impedance bandwidth of 34.86% for VSWR < 2. Acceptable agreement between the simulation and measured results validates the proposed design. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:358–363, 2015.