基于协方差矩阵重构的阵元失效MIMO雷达DOA估计

在实际应用中由于恶劣环境或人为干扰等因素而导致多输入多输出(Multiple-Input Multiple-Output,MIMO)雷达部分阵元失效,使得其接收数据缺失及其协方差矩阵秩亏,从而导致子空间类算法的波达方向(Direction of Arrival,DOA)估计性能恶化甚至完全失效。针对上述问题,提出了一种接收阵元失效下基于协方差矩阵重构的MIMO雷达DOA估计方法。该方法根据MIMO雷达协方差矩阵中以接收阵元数划分的子方块矩阵具有Toeplitz特性,利用正常工作接收阵元的协方差矩阵元素来恢复相应的缺失元素,从而重构出完整的数据协方差矩阵,提高阵元失效MIMO雷达的DOA估计性能。仿真结果验证了所提方法的有效性。     

Khatri-Rao积变换下的离格信号DOA估计

当存在离格信号时,基于稀疏表示的波达角（DOA）估计算法性能损失严重。为解决这个问题,在对接收数据协方差矩阵进行Khatri-Rao积变换的基础上,推导了离格信号网格偏离量与紧邻信号原子系数之间的关系,提出了一种单一离格信号DOA估计方法。为提高对邻近离格信号DOA的估计性能,利用矩阵的广义逆性质提出了基于多原子系数的联合估计方法。仿真实验表明,单一离格信号DOA估计方法在低信噪比下有较好的性能,联合估计方法在高信噪比条件下对邻近离格信号DOA有较高的估计精度,同时所提算法估计性能几乎不受网格划分间距的影响,可以通过增大网格间距降低算法运算量。相关研究对阵列天线DOA估计具有一定的参考价值。     

采用降秩多级维纳滤波器的二维DOA估计快速算法

针对双平行线阵的二维波达方向（DOA）估计问题,为有效降低计算复杂度,提出了一种基于降秩多级维纳滤波器（MSWF）的快速算法。首先利用MSWF的前向递推实现信号子空间的快速估计,无需估计协方差矩阵和特征分解;然后,通过MUSIC算法对方位角和俯仰角的估计进行分维估计,使二维DOA估计退化为两个一维DOA估计问题,且方位角和俯仰角自动配对,进一步降低了运算量。仿真结果表明,该方法的估计精度优于同样基于双平行线阵提出的波达方向矩阵法（DOAM）,俯仰角兼并时同样适用,计算复杂度低,适用于实时性要求高的应用背景。     

基于截断修正平滑l0范数的MIMO雷达目标参数估计

在多输入多输出(MIMO)雷达中，针对平滑l0范数(SL0)因感知矩阵的病态性而导致其失效的问题，提出了一种基于截断修正SL0的MIMO雷达目标参数估计方法。该方法在对MIMO雷达感知矩阵进行截断奇异值分解(TSVD)处理的基础上，将保留的奇异值以均值为截断门限，分成较大和较小的两部分，分别采用不同的修正准则进行修正；然后经奇异值分解(SVD)反变换获得非病态感知矩阵，利用该非病态感知矩阵通过SL0算法对MIMO雷达目标参数进行估计，从而显著提高了MIMO雷达目标参数估计的精度和速度。仿真结果验证了该方法的有效性。     

一种MIMO中继系统的自适应自干扰消除方法

为节省频率资源,全双工中继一般采用相同的频率接收和发射信号。由于收发天线之间无法充分隔离,接收天线容易受到自身发射天线的回波干扰。针对宽带全双工多输入多输出（MIMO）中继的自干扰问题,提出了一种基于梯度下降自适应算法的自干扰消除方法。该方法利用中继反馈的已知信号进行自干扰信道估计,并产生一个对自干扰信号的估计信号,从而在接收端将干扰抑制。仿真结果表明,该方法在自适应滤波器的跟踪性能、收敛分布和不同MIMO配置下的均方误差（MSE）性能等方面均取得良好效果。     

基于确定性观测的压缩感知MIMO信道参数反馈

在实际资源受限（带宽受限或功率受限）的无线通信系统中,多径信道具有很强的稀疏特性,如何利用这一特点更加高效地将接收端获得的多径信道状态信息（CSI）进行压缩、反馈,是目前信道状态信息反馈技术的研究热点。针对现有多入多出（MIMO）信道状态信息反馈方法中随机观测矩阵需要较大存储空间的问题,引入了确定性Golay测量矩阵,提出了一种基于确定性观测的压缩感知MIMO多径信道参数反馈方法。在接收端对由信道估计得出的信道状态信息利用确定性Golay测量矩阵进行观测,将较少数目的观测值反馈到发送端,在发送端通过重构算法恢复出完全信道状态信息。仿真实验表明,与随机观测相比,采用确定性Golay观测矩阵的方法虽然需要的观测值数目会有所增加,但所需存储空间远小于随机观测矩阵,且利用确定性观测反馈信道状态信息的重构性能与随机观测矩阵相当。     

统计MIMO雷达的多目标定位和速度估计方法

在多目标情况下,统计多输入多输出（MIMO）雷达需要对不同观测通道中估计出的目标参数 进行配对,才能完成多个目标定位及其速度估计 。针对这一问题,对统计MIMO雷达提出了一种映射搜索配对法来实现在不同观测通道中的目 标距离延时和多普勒频率估计值的配对,从而获得目标位置及其速度估计值。仿真结果表明 ,该方法在目标雷达散射截面（RCS）闪烁情况下能对多个目标进行有效定位和速度估计。     

干扰条件下的“北斗”信号解扩重构DOA估计

在干扰条件下,卫星导航抗干扰波束形成算法往往需要卫星信号波达方向（Direction-of-Arrival,DOA）的先验信息。但当存在低信噪比信号或主动干扰源时,常规的DOA估计算法性能急剧下降甚至失效。针对此问题,提出了一种被干扰信号压制的低信噪比“北斗”信号的DOA估计算法。该算法首先通过对接收信号进行子空间投影抑制干扰信号,然后对抑制干扰后的信号进行解扩重构处理,最后通过多重信号分类算法完成对“北斗”信号的DOA估计。仿真结果表明,在干扰信号干信比80 dB条件下,“北斗”信号DOA估计误差在5°以内,为下一步进行波束形成计算提供了高精度的入射角信息。     

基于时频子空间的多分量宽带调频信号DOA估计

为在复杂电磁环境下实现对多分量宽带线性调频信号的到达角(DOA)估计,研究了基于时频 子空间的到达角估计算法,对阵列接收信号通过二维时频掩膜滤波逐一提取各信源的时频自 项,建立了空时频矩阵,运用子空间技术得到各信源的到达角估计,并与宽带聚汇算法比较 ,进行了仿真实验。仿真结果表明,由于充分利用了多分量线性调频信号的时频信息,在低 信噪比条件下,宽带时频子空间方法比宽带聚汇算法具有更高的DOA估计的分辨率和估计精 度。     

多星测控中波达方向估计传播因子虚拟ESPRIT算法

针对多星测控中涉及的阵列天线信号波达方向估计问题,给出了一种新的基于传播 因子的二维波达方向估计（2D-DOA）算法——传播因子虚拟ESPRIT算法（PMV-ESPRIT）。传 统的虚拟ESPR IT算法需要对互相关矩阵进行特征值分解（EVD）或对数据接收矩阵进行奇异值分解（SVD） ,因此其运算量较大。而新算法基于传播因子方向向量分割的线性运算对传统算法做了进 一步改进,其运算量明显降低,且具有更高的信号波达方向测向精度。仿真实验结果表明了 PMV-ESPRIT算法的有效性和可行性。     

Brown＇s Blossom in Britain-China

The overall strategic relationship between U.K. and China is ＂better than ever＂, China- Britain relations have maintained good momentum, with increased high-level exchanges and the reinforcement of strategic mutual trust, with more room for growth in the future.     

Challenge and Opportunity Go Hand in Hand——What Global Economic Agitation Brings to the China's Economy?

Domino effects of the global finance agitation As the origin of the subprime crisis,US financial institutions lost USS45 billion last year,accounted for over half of the total US,EU & Japan loss.Since January 15th,Chtigroup released its financial statement of the 4th quarter,showing a net deficit of USS9.83 billion,which marked the hisoric high of its quarterly deficit.     

Jean-Pierre Duprieu： Willing to Be A Legate of Sino-French Business

Estaing, former French president, Valery Giscard d＇Estaing attended Sino-French Economic Seminar held in Shanghai in early April and said that the world center has shifted from the west to the east with many European and US companies entering into Asia, and China has the ability to play an important role in the world stage. Estaing, naming himself＂French Confucian＂, then said in Chinese that a cook-group includes 10 people in ancient Chinese soldier system and the cook is in charge of cooking for them. And people who belong to the same cook are actually ＂Partners＂.     

China''''s Stock Market Wave

The annual meeting of the World Economy Forum was held in Davos,a little town in Switzerland,on January 23rd to the 27th this year,with the theme"the Power fo Collaborative Innovation",over 2500 celebrates from ture political and cconomic circles of more than 80 countries and challengred logether to talk about the future of the global economy in 2008,A Forum for the problems and challenges that face whole world,some of the keywords which drew attention during the event were:the U.S.subprime mortgage crisis,soaring energy prices,the economic slowdown in the U.S.ermerging economic bodies,authority funds and the general unpredictable nature of the global economy.     

Trade Promotion from Neighborhood

If you are considering to trade with companies in Japan or expanding your .business to Japan, we are ready to help from the very beginning.＂ You will find this greeting at the first sight on the Chinese website of Japan External Trade Organization （JETRO）. JETRO has committed itself in delivering highly efficient and quality services to meet the demand of internal and external customs including Japanese companies, hence winning a good reputation in the international trade arena. In recent years, with its priority in advancing business cooperation in South and East Asia, JETRO has made great achievement in promoting trade between China and Japan. Therefore, China＇s Foreign Trade interviewed Mr. Yoichi Maine, Deputy Director General of JETRO BEIJING.     

Auto Parts Market Potential Coming into Surface

Looking at the increasingly fierce competition in the world auto market. global automobile manufacturing industry, taking Europe, the U.S. and Japan as representatives, is gradually forming a new type of relationship, mutual cooperation between whole vehicle and parts manufacturers. We can clearly see that auto parts manufacturers have become independent from the whole vehicle manufacturing companies, which means that the former structure of auto industry has greatly changed, and a new relationship,     

Domino Effect on Electricity and Coal Prices

In the middle of last December, the key purchase contracts for coal used in power generation in 2008 were signed, reflecting a demand for more than 1.085 billion tons. It is important to note that the country＇s five biggest power producers, China Huaneng Group, China Guodian Corporation, China Power Investment Corporation, China Huadian Corporation and China Datang Corporation, had settled on the prices on their purchase contracts, and they are expected to consume 290 million tons of coal for generating electricity,     

Slimmed May Day Holiday

Last November the State Council of China decided to renew its holiday system by reducing the seven-day May Day holiday to three days and introducing three new one-day public holidays, namely the Qingming Festival, Dragon Boat Festival and Moon Festival. By doing so, the three golden-week holidays that were introduced in 1999, namely the Spring Festival, May Day and National Day, could be better distributed.     

China Ranked the 7th in Global Influence Survey

The results of the Annual Global Public Opinion Survey were released by the British Broadcasting Company （BBC） on April 2,2008,the combination of 7,457 public opinion polls in 34 countries,gave Germany and Japan the No.1 and No.2 spots,respectively, while the last four went to North Korea, Pakistan,Israel,Iran.     

Figures from Government Working Report

Nine o＇clock in the morning of March 5th,2008,the first meeting of the eleventh session of National People＇s Congress was held in the Great Hall of People.As usual,the first performance of this big event in China was from the government working report made by the Premier.Five years of government＇s work in this session was counted in Premier Wen Jiabao＇s working report.