星载DBF多波束发射有源阵列天线

 低轨通信卫星大容量、终端小型化要求卫星采用多波束天线技术来实现高增益、宽覆盖.本文针对低轨CDMA通信系统,设计了具有近"等通量"覆盖的平面阵列多波束发射天线,该天线由61微带单元天线阵、61个发射射频通道和数字波束形成网络组成;数字波束成形网络对输入的16个波束信号进行正交化、加权处理输出61路中频信号,由发射射频通道完成上变频和信号放大,最后通过天线阵辐射出去在空间形成期望的16个赋形波束覆盖.文章详细介绍了天线的实现方法和试验结果,通过对16波束发射天线原理样机的测试,结果表明天线各指标都符合设计要求,有效验证了天线系统设计的正确性.     

基站智能天线多波束合成技术

采用数字波束形成的技术，给出了基站智能天线多波束合成的有效算法。对圆环阵分布的基站天线多波束方向图进行了综合，得到了空间隔离度很好的多个波束，并将副瓣控制在30dB以下，结果令人满意。该方法可用于任意单元构成的不均匀阵列天线，还可用于波束展宽及扇形波束的合成。     

智能天线数字波束形成的LMS-DRMTCMA算法

本文提出一种适用于TD-SCDMA智能天线系统数字波束形成的LMS(最小均方)解扩重扩多目标恒模阵列(LMS-DRMTCMA)算法。该算法通过将Z.Rong等提出的LS解扩重扩多目标恒模阵列(LS-DRMTCMA)参考信号形成方法应用到LMS算法,并将TD-SCDMA标准提供的训练序列用于加速算法的收敛,使运算量远低于LS-DRMTCMA算法,明显低于导频LMS解扩重扩多目标阵列(LMS-DRMTA)算法。LMS-DRMTCMA算法还适用于激活用户数远大于天线阵元数的移动通信系统。仿真实验表明,LMS-DRMTCMA算法比LS-DRMTCMA算法和导频LMS-DRMTA算法具有更低的误码率,适合在极低信噪比环境中工作。LMS-DRMTCMA算法具有运算量低、易于实时实现的特点。     

智能天线波束形成算法分析

本文重点介绍了自适应方式下的智能天线;然后研究了三种经典的自适应波束形成算法——最小均方误差算法、递归最小二乘算法、恒模算法,并对这三种算法在MATLAB中进行了仿真,分别得出了期望信号在迭代过程中的误差变化,期望信号和干扰信号在迭代过程中的增益变化及迭代完成达到收敛后的天线方向图,分析了收敛速度及各项性能指标,并对三种算法做了性能比较。     

智能天线波束形成原理与实现

波束形成技术是智能天线的核心技术之一。文章介绍波束形成的原理和分类,详细分析波束形成的具体实现结构,并讨论目前智能天线波束形成所面临的挑战。     

基于FPGA的智能天线数字波束形成设计

通讯系统的频谱资源日益紧张,智能天线是增加系统容量最有希望的解决方法之一。智能天线的数字波束形成是通讯系统实现空分多址的基础。在介绍了数字波束形成的基本原理基础上,提出了一种基于FPGA实现的实时数字波束形成方法,并使用嵌入式逻辑分析仪进行了实测分析。实验结果表明,该数字波束形成设计能实时调整各通道的幅度和相位,实现数字波束形成。     

一种新的智能天线波束形成算法

在DS/CDMA系统中采用智能天线技术可以增加系统的容量,提高抗干扰性能.智能天线技术的核心是波束形成算法,基于遗传算法提出了一种新的智能天线波束形成算法,算法采用了内插和外推两种交叉算子,克服了遗传算法的早熟收敛问题,提高了全局收敛能力.研究结果表明,提出的智能天线波束形成算法具有良好的收敛性和稳定性,可用于DS/CDMA系统抵抗干扰的影响.     

智能天线自适应波束形成算法的研究

巨大的通信需求量与有限的频谱资源之间的矛盾越来越突出,智能天线凭借其特有的空间滤波的特性,采用空分多址方式,高效率地使用频谱资源,在保证通信质量的基础上大规模地提高系统容量。按照非盲算法与盲算法的分类,分别介绍了非盲目算法中的最小均方算法和盲目算法中的最小二乘恒模算法,并对两种算法通过matlab进行仿真。     

基于CMA算法的智能天线自适应波束形成研究

自适应波束形成是智能天线的核心技术,其主要思想是利用自适应算法调整阵列的权向量,将各阵元接收到的信号进行加权求和,把天线阵列形成的波束“导向”到特定方向上。本文介绍了恒模算法（CMA）和最小二乘恒模算法（LS—CMA）两种盲波束形成算法并运用Matlab软件对两种算法进行仿真分析,仿真结果表明,LS—CMA具有更快的收敛速度以及更好的抗干扰能力。     

基于LMS算法的智能天线自适应波束形成研究

自适应波束形成是智能天线的核心技术,其主要思想是利用自适应算法调整阵列的权向量,将各阵元接收到的信号进行加权求和,把天线阵列形成的波束"导向"到一个方向上,使期望用户信号方向得到最大的增益,并相应地使干扰信号方向得到较低的增益,从而提高系统的性能。本文对智能天线中的自适应波束形成进行研究,运用MATLAB软件对固定步长和变步长LMS算法进行计算机仿真实验。仿真结果表明,基于LMS算法的自适应波束形成器能够形成符合要求的波束图,变步长的LMS算法均方误差收敛效果较好,收敛速度更快,具有较强的实用性。     

基于光纤无线电的优化自适应波束形成算法

把智能天线技术和光纤无线电技术相结合,针对光纤中传输的无线电信号许多是具有谱自相干特性的循环平稳信号,提出了非线性约束条件下的优化自适应波束形成算法.通过对R-CAB算法的权向量进行二次优化,调整了R-CAB算法方向图零陷的位置和深度,改善了输出SINR.并且改进算法的输出SINR对导引向量随机误差具有稳健性, 对期望信号的功率变化表现出不敏感的特性.理论分析与计算机仿真试验都证明了算法的有效性.     

数字波束形成技术在智能天线中的应用

研究了波束形成算法在智能天线中的应用,包括直接加权波束形成算法、旁瓣抑制波束形成算法和零点抑制波束形成算法。在研究各种算法的基础上给出了仿真结果,并对比了每一种算法。详细分析了每一种算法的特点及适用条件,为波束形成算法在智能天线中的应用提供了技术参考。     

智能天线自适应波束赋形算法的研究

智能天线作为3G及未来移动通信的核心技术，是当前通信领域的研究热点。阐述了智能天线的基本原理，并对自适应波束赋形算法进行了分类，较为详细地比较和分析了几种算法的特点及其适用条件。基于算法的现状，提出了未来的研究方向。     

数字波束赋形天线在个人通信系统中的应用

文章介绍了一项近十年来发展起来的新技术－数字波束形成技术的基本原理,并探讨了将数字波束形成天线用于个人通信在改善通信质量方面的作用和意义。     

智能天线中的DOA估计算法的研究

波达方向(DOA)估计的基本问题就是确定同时处在空间某一区域内多个感兴趣的信号的空间位置(即各个信号到达阵列参考阵元的方位角,简称波达方向).提取波达方向信息是智能天线技术中的关键任务之一.文中主要研究波速方向估计算法中的延迟一相加法,Capon最小方差法,常规MUSIC算法和改进型MUSIC算法.通过仿真,比较了不同波达方向估计算法的性能.     

极化智能天线的二维矢量波束形成方法研究

针对智能天线的匹配接收与干扰抑制等问题,将现有的基于均匀线阵的极化波束形成方法拓展到二维平面阵,提出了一种基于二阶锥规划的二维极化波束形成方法。在二维观测平面内,该方法通过对主瓣区域进行极化匹配设计以提高系统接收增益和主瓣干扰的抑制能力,在旁瓣区域将零陷凹面与极化约束进行叠加设计以最大限度提高干扰抑制能力,并建立最优的矢量波束优化模型,进而转化为两个等价的标量优化问题,可使用二阶锥规划求解。仿真结果表明:相对于现有的均匀线阵极化波束形成方法而言,该方法能够在方位-俯仰的二维平面上实现极化波束的约束优化,包括了主瓣极化匹配、零陷凹面的极化约束,提高了极化波束形成方法的工程实用性。      

Essential Considerations in Implementing the Smart Antenna System for Downlink Beamforming

This paper addresses some essential problems that have to be taken into consideration in implementing the smart antenna base station (SABS) for downlink beamforming. In order to provide proper downlink beamforming as well as uplink beamforming, a pragmatic procedure of automatic calibration is proposed. Through the experimental test, we confirm that the proposed calibration technique has eliminated the problem of the phase differences of the signal path associated with each antenna. Also, in this paper, we first analyze the multipath condition under which the auxiliary pilot becomes indispensable for detecting the data transmitted on the data channel and what happens if the auxiliary pilot is not available. Then, the performance of the downlink beamforming utilizing the auxiliary pilot is analyzed through the computer simulations. Finally, we present a comparison of downlink communications to uplink ones in terms of throughputs available at each of uplink and downlink communications. Weon-Cheol Lee received the B.S, M.S, and Ph.D. degree in Electronic Communication Engineering from Hanyang University, Korea, in 1992, 1994, 2005, respectively. From 1994 to 2000, he was with LG Electronic Inc., where he had worked for developing the digital VCR, digital cable modem, digital TV. Since 2001, he has been a professor with department of information and communications, Yong-in Songdam College, Korea. His research interests include smart antennas, mobile communications beyond the third generation, digital broadcasting technology, and communication signal processing. Dr. Lee also received the Best Research Paper Award and Excellent Research Engineer Award from LG Electronics, respectively. Seungwon Choireceived the BS degree from Hanyang University, Seoul, Korea, and the M.S. degree from Seoul National University, Korea, 1980 and 1982, respectively, both in electronics engineering, the MS degree (computer engineering) in 1985, and the PhD degree (electrical engineering), in 1988, both from Syracuse University, Syracuse, NY. From 1988 to 1989 he was with the Department of Electrical and Computer Engineering of Syracuse University, Syracuse, NY, as an Assistant Professor. In 1989 he joined the Electronics and Telecommunications Research Institute, Daejeon, Korea. From 1990 to 1992 he was with the Communications Research Laboratory, Tokyo, Japan, as a Science and Technology Agency fellow, developing the adaptive antenna array systems and adaptive equalizing filters. He joined Hanyang University, Seoul, Korea, in 1992 as an assistant professor. He is a professor in the School of Electrical and Computer Engineering of Hanyang University. Since 2003, Dr. Choi has been serving as a Vice Chairman and the representative of the ITU region 3 for SDR (Software Defined Radio) Forum and as a Director of the HY-SDR Research Center, MIC, Korea. His research interests include digital communications and adaptive signal processing with a recent focus on the implementation of the smart antenna systems for both mobile communication systems and wireless data systems. Jae-Moung Kim received the BS degree from Hanyang University, Korea in 1974, the MSEE degree from University of Southern California, USA in 1981, and the PhD degree from Yonsei University, Korea in 1987. He was a Vice President of Radio {&} Broadcasting Technology Laboratory and Director of Satellite Communication System Department at Electronics and Telecommunications Research Institute (ETRI) from September 1982 to March 2003. Since April of 2003, he has been a Professor in the Graduate School of Information Technology and Telecommunications, Inha University. He is a board member of directors of Korean Institute of Communication Science (KICS), a Vice President of Korea Society of Broadcast Engineers (KOSBE) and a senior member of IEEE. His research background is telecommunication systems modeling and performance analysis of broadband wireless access systems, mobile communications, satellite communications and broadcasting transmission technologies.     

基于软件无线电的相控阵雷达系统研究

从软件无线电的概念出法,论述了在相控阵雷达系统中采用软件无线电技术的必要性和可能性;其次详细地论述了相控阵雷达系统中软件无线电的实现形式:即天线子系统,收、发子系统,信号处理子系统。最后对软件无线电技术在现代雷达中的发展进行了展望。