一种改进的数字同频直放站自适应反馈干扰抑制算法

基于数字地面电视广播(Digital Terrestrial Televisi on Broa dcasting,DTTB)同频直放站的回波干扰抑制,提出了一种变步长块LMS(Variable Step-siz e Block Normalized Least Mean Square,VSSBNLMS)自适应算法。此算法的目的是为了提 高传统回波干扰抑制的自适应算法的收敛速度和降低计算复杂度。其将输入信号分为长度相 等的块,在每一个数据块内,权值向量只更新一次,有效地降低了计算复杂度。〖JP2〗另 外,该算 法通过输出误差控制更新步长的变化,与传统的归一化LMS (NLMS)和块LMS (BLMS)算法相比 ,提高了收敛速度。仿真结果表明,该算法具有良好的收敛速度和回波干扰抑制性能。     

知识辅助的两级自适应抗干扰技术

机载雷达通常工作在强杂波、强干扰的复杂电磁环境中,如何有效消除压制干扰抑制杂波是其中的关键问题。传统的两级空时自适应处理（STAP）算法在静默期采集信号得到干扰子空间,在开机阶段运用空间投影技术抑制干扰并采用降维STAP抑制杂波。虽然该算法在干扰平稳时具有较好的效果,但是在实际应用中,复杂的干扰环境会破坏广义平稳假设。因此,仅采集单个静默期的干扰样本来估计协方差矩阵会出现偏差。为了克服该问题,提出采集多个静默期的干扰信号来估计当前的干扰协方差矩阵,以此来提高估计准确度,可以更好地抑制干扰。仿真结果表明即使在当前静默期采集的干扰信息不完整时,该技术仍然能够利用以前的干扰信息准确估计干扰协方差矩阵。     

一种基于自适应阵列天线的波束赋形算法

自适应阵列天线中的数字波束赋形(DBF)技术是智能天线数字信号处理部分的核心.提出了一种可用于自适应阵列波束赋形的SMI-LMS算法--由SMI(采样协方差矩阵求逆)算法决定LMS(最小均方)算法的初始权向量.该算法充分结合了SMI算法收敛速度快和LMS算法稳态误差小的优点,能在较强干扰环境下,确保权向量的快速收敛和跟踪速度.与传统的LMS算法相比,SMI-LMS算法具有良好的收敛性能、较快的跟踪速度和较小的输出误差,并可以有效改善自适应方向图的副瓣性能.仿真结果验证了该结论.     

一种基于四相编码和优化阵列的MIMO STAP实现方法

多输入多输出（MIMO）雷达多信号间正交性和天线阵列结构影响空时自适应处理(STAP)性能。为了提高多信号间正交性,提出了基于遗传算法优化提高四相编码的自相关峰值并降低互相关峰值方法,保证了多发射信号间良好正交性,基本抑制了盲速影响。针对天线阵列稀疏导致盲速、阵元密布导致天线孔径过小的问题,基于最大连续孔径思想,提出了一种优化阵列结构,在不显著增加天线阵列长度和阵元数目条件下,与四相编码信号结合,实现了动目标检测。仿真实验证明,基于四相编码正交信号和收发阵列设计,MIMO STAP可实现良好动目标检测性能。     

TD-SCDMA系统中智能天线的重复迭代自适应算法

提出一种用于TD-SCDMA系统的重复迭代自适应智能天线算法。通过在自适应算法中把阵列输入信号和作为参考信号的训练序列重复使用,可以在短训练序列情况下实现较好的收敛,提高通信系统的传输效率。对LMS算法中全训练序列重复迭代和滑动窗口重复迭代算法进行了仿真,结果表明,在有限训练序列时本算法比传统LMS算法更好地逼近最佳解。     

基于自适应惯性权重粒子群优化的多跳频信号盲源分离

针对跳频通信中多跳频信号的盲源分离问题,提出了一种基于自适应惯性权重粒子群的盲源分离算法。该算法将分离信号的负熵作为目标函数,依据迭代前后每个粒子适应度值间差值自适应地调节惯性权重。把适应度值变差的粒子惯性权重设成零,以消除惯性分量不利影响,这样可以减少无效迭代次数,提高收敛速度。应用于盲源分离时,比经典算法分离效果好且克服了激活函数选取难题。实验结果表明该算法用于多跳频信号盲分离时性能稳定且收敛速度快,与经典算法比较优势明显,为智能算法在盲源分离方面的研究提供了一定的参考。     

基于累积量的盲自适应波束形成技术

本文研究了在阵列信号处理中使用累积量的问题，以及在相干多径环境中基于累积量的盲自适应波束形成技术。该技术能在阵列几何结构和阵列流形未知的条件下，自适应调整权系数使阵列输出的信号干扰加噪声比最大。     

直接序列扩频系统中强窄带干扰抑制的一种非线性自适应抑制快速算法

本文将一种改进的非线性自适应抑制快速算法应用于直接序列扩频通信的强窄带干扰抑制中,并将其与其它时域自适应抑制算法进行仿真比较,在收敛速度和收敛精度相当的情况下,该算法结构简单、计算量适中且误码率小,特别是相对于其它算法,其对窄带干扰的抑制深度具有明显的优势。     

变速率部分更新盲均衡算法

对于长抽头系数自适应算法,基于最大化自适应滤波器系数误差向量原则的变速率部分更新算法,能够在大幅度降低算法实现复杂度的同时,解决部分更新算法收敛速度慢的问题。但是,该变速率算法仅适用于LMS结构,对于具有非线性代价函数的部分更新自适应盲均衡算法并不适用。基于同样的最优化思想,通过替换步长计算表达式中的部分统计量,提出了能够适合于部分更新多模盲均衡算法(MMA)的确定性变步长控制算法,并通过递归的方式计算步长值,简化了实现过程。对固定信道和时变信道的数值仿真结果表明,新算法相比传统基于收敛误差的经验性变步长算法具有更快的收敛速度和更好的跟踪性能,有效解决了部分更新自适应盲均衡算法的确定性变速率控制问题,提升了算法的收敛速度和跟踪性能。     

大规模MIMO系统中的一种自适应SIC检测算法

与传统系统相比,大规模多入多出（MIMO）系统能更加有效地提高频谱效率。利用传统的最小均方误差（MMSE）信号检测算法求解大规模MIMO系统,虽然检测结果接近最优,但是矩阵的求逆运算导致计算的复杂度非常高。提出了一种自适应排序干扰消除（SIC）检测算法,在逐次超松弛（SOR）迭代运算的基础上,通过干扰消除降低待检测矩阵的维度。通过仿真分析,得出所提算法的复杂度低于Jacobi、SOR检测算法,且在迭代次数较少的情况下,算法的误码率（BER）性能明显优于SOR检测算法。     

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.     

Sinosteel：Extraordinary Moves in Industry Chess

Among the Fortune 500 firms,more and more images from China emerge out.On the 2008 list,Sinosteel Corporation,a landmark group of China industries quietly squeezes into the candidate line.As the largest steel service ＆ trade enterprise,its sales reached at RMB 111.24 billion,with a year-on-year increase of 83.03 percent,and the profit grew by 180.03 percent.On the Sinosteel 2008 Work Meeting,the president Huang Tianwen uttered,＂In the coming year,we will work for US$20 billion sales,and look forward to getting a position in Fortune 500 firms for ourselves.＂     

Walk Through Unusual Five Years—— An Exhibitor＇s Canton Fair Course

When the 103rd Canton Fair is approaching, an old friend of Canton Fair, Li Ying from Jiangsu prov-ince recollected his past five years＇ experiences to the grand trade meeting. Each year is special, with some unforgettable memories colored by the year.     

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,     

Public Financial Expenditure——A Reflection of the Livelihood Improvement

In recent years.China's public finance put social construction high on the agenda and attaches more importance on livelihood insurance and improvement.The 2003-2007 public financial expenditure reflects a fact that the government isputting more emphasis on livelihood andissues concerning the people.     

Voices from the MPC and CPPCC

"Crucial for economic growth.energy utilization has its role in all economic sectors and every aspect of people's daily life.Now we are in dire need of a new profession,namely energy manager.We not only need to have passion and responsibility,but also a scientific approach to conserve energy and cut emissions.APpropriate legislation should be in place.and a special profession should be introduced to ensure the implementation of these laws and regulations."