基于并联FIR滤波器组的Hammerstein预失真器

采用预失真技术对功率放大器的记忆非线性失真进行补偿的关键是预失真器建模的准确性,尤其是模型对功率放大器逆记忆特性的描述能力。针对目前预失真器模型对功率放大器逆记忆效应描述不充分的问题,提出了将查找表(LUT)级联一个具有并联结构的有限长单位冲激响应(FIR)滤波器组作为实现形式的Hammerstein预失真器,以提高传统Hammerstein预失真器的补偿性能,并采用一种两步算法对其参数进行辨识。仿真实验表明,提出的Hammerstein预失真器能更好地补偿带强记忆效应的功率放大器的非线性失真。     

RLS算法在基带预失真系统中的应用

传统的最小二乘（LS）类预失真算法运算量大,且不能跟踪功放的变化特性。推导了基于 递归最小二乘（RLS） 算法和间接学习型结构的自适应基带预失真算法,并仿真和分析了算法的性能,结果显示该 算法与传统的LS类预失真算法对系统功放非线性改善的效果相当。为了进一步验证算法的有 效性,设计和构建了具有预失真功能的短波发射系统。硬件测试结果表明,该算法对功放输 出的双音信号的三阶互调改善量达25 dB,所有互调分量均低于-53 dB。     

一种改进并行两箱预失真方法

针对现有椭圆球面波调制信号预失真方法算法复杂度高、预失真器工作效率较低的问题，结合椭圆球面波调制信号的幅值特点和功率放大器对信号非线性失真特性，引入分段处理的思想，提出了一种改进并行两箱预失真方法。通过设置阈值门限，对调制信号进行分段处理，仅对信号中大幅值分量进行处理，算法复杂度低，更易于工程实现。理论分析和仿真结果表明，当阈值门限为0.5时，与并行两箱预失真方法相比，所提预失真方法算法复杂度降低为原算法10%以下；当误比特率为10-5时，相对于未经放大器失真的调制信号，所需信噪比仅增加约0.02 dB。     

一种低复杂度的自适应并行两箱预失真方法

自适应预失真方法能自适应调节阈值，仅对调制信号中大幅值分量进行预失真处理，有效降低了预失真算法复杂度，但由于该方法仍采用正交记忆多项式进行预失真处理，算法复杂度仍旧较高。围绕如何进一步降低预失真处理算法复杂度，引入信号并行处理思想和递推最小二乘算法，提出了一种低复杂度的自适应并行两箱预失真方法。结合调制信号的解析信号表达式，利用算法复杂度更低的递推最小二乘算法分支路对实部和虚部进行预失真处理，有效降低了预失真算法复杂度。理论分析和仿真结果表明，在保证系统误码性能正常的前提下，与并行两箱预失真方法和自适应预失真方法相比，所提算法复杂度分别降低约93%和27.62%。     

一种基于模糊辨识的OFDM系统预失真器设计

将有记忆的高功率放大器(HPA)描述成一个线性动态系统级联一个无记忆非线性系统的Wiener系统模型,由Sugeno模糊模型自适应跟踪HPA的无记忆非线性曲线,通过离线过程设计OFDM系统数字预失真器。为了消除HPA记忆效应,首先在频域得到信号的均衡补偿,然后通过傅里叶逆变换后得到时域记忆性补偿。该预失真器具有收敛速度快、系统稳定、补偿效果好的特点。     

卫星信道中高阶APSK调制的非线性失真补偿算法

针对高阶APSK调制在卫星信道中存在有记忆非线性失真的现象,提出一种联合补偿算 法,该算法充分利用APSK调制信号星座图的特点,在大幅度减小无记忆数据预失真计算量的 基础上,联合非线性均衡实现对有记忆非线性卫星信道的自适应补偿。其优点是存储量和计 算复杂度随调制阶数的增加变化很小。仿真结果表明,该算法能够达到有记忆数据预失真的 补偿性能,且最佳工作点提高0.2 dB。     

基于自适应基带预失真的高效率发射技术

在Volterra级数系统理论框架下,阐述并分析了自适应基带预失真系统的间接学习结 构、记忆多项式行为模型与递归最小二乘算法,针对卫星通信提出了一种基于自适应基带预 失真的高功率高效率发射技术。仿真验证了该方法的有效性。     

宽带卫星功率放大器失真补偿技术研究进展及应用

针对宽带卫星通信系统中高功率放大器的记忆非线性失真问题,对不同补偿技术进行 了综述,重点研究了预失真的学习结构、数据预失真、信号预失真、时频域预失真和自适应 均衡等补偿技术并对它们进行了相应的优缺点比较,最后提出了宽带卫星功放实际应用环境 下的4种补偿方案,为我国宽带卫星功放失真补偿研究提供理论参考。     

一种新型数字预失真算法的设计

针对WCDMA系统中功率放大器的非线性特征,设计了一种基于Volterra级数的有记忆数字基带预失真算法,能够自适应地补偿功放的非线性.理论分析和计算机仿真验证了该算法的有效性和实用性.     

一种用于补偿卫星通信信道记忆非线性的数字基带预失真技术

研究了卫星通信系统中记忆非线性信道的自适应数字基带预失真线性化技术，提出了一种基于记忆多项式的非直接学习结构的自适应基带预失真方案，给出了自适鹰算法。仿真结果表明，该方案能有效抑制带外频谱扩散，减小带内失真，降低误比特率，实现卫星通信系统中记忆非线性失真的自适应预失真。     

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.     

Universal Coverage, Pinpoint Illustration and Profound Impact HTC 2008 Intermedia Recommendation and Introduction Meeting

Holding 88 percent of train media resources across China, based on "Time Cube", on the 2008 Intermedia Recommendation and Introduction Meeting on December 19, 2007, HTC announced its high-profile strategy of tour marketing and tapping the immeasurable potentials on the train. Meanwhile, HTC officially launched its brand new product Olympic Train on the meeting, providing a fabulous platform for all the brands that are prepared to do a smart marketing on the occasion of 2008 Olympic Games.     

Market presence in China strengthened Network growth and Dual-Chinese-Hub Strategy More frequet Flyer Benefit——Air China and shanhai Airlines Join Star Alliance

In the end of 2007, Air China Limited (hereinafter "Air China") and Shanghai Airlines, formally joined Star Alliance at a ceremony held in the new Terminal Three at Beijing Capital International Airport. With the addition of the two Chinese airlines, Star Alliance now has 19 member carriers operating 17,000 daily flights to 897 destinations in 160 countries.     

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,     

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＂.     

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,     

A World of Love 2008 Music Grand Ceremony

Under the guidance of the theme slogan of the 29th Olympic Games - One World One Dream, with dream, love and dedication as its theme, the 2008 Music Grand Ceremony ＆ 1000 People Charity Concert on 100 days cotmtdown to Paralympic Gamesis officiaily launched on December 22, 2007. The 2008 Music Grand Ceremony is sponsored by China Disabled Persons＇ Federation, and co-hosted by National Paralympic Committee of China,