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%。     

优化参数对CPM-PSWF信号性能的影响

基于椭圆球面波信号的连续相位调制（Continuous Phase Modulation Based on Prolate Spheroidal Wave Function,CPM-PSWF）方法是一种新颖的数字调制方式,调制参数的优化与其调制信号性能有着直接联系。分析不同调制参数对CPM-PSWF信号性能的影响,优化选择调制参数,对获得能量聚集性和功率效率都较高的CPM信号具有重要意义。首先,对基于椭圆球面波信号的CPM信号进行描述;其次,采用韦尔奇(Welch)谱密度估计法,对时间带宽积、调制指数、关联长度等不同参数对CPM-PSWF调制信号的功率谱密度和带宽特性的影响进行了仿真分析。实验结果表明,选用0阶椭圆球面波信号,小时间带宽积、调制指数和符号进制数越小,关联长度越大时,CPM-PSWF信号具有频谱带外高频滚降快、占用带宽小的特点。     

非正弦短波通信方案及性能分析

为了提高短波通信容量和数据传输速率,缓减短波信道拥挤状况,提出了基于椭圆 球面波的非正弦短波通信方案。该方案利用快速设计方法设计椭圆球面波脉冲信号,利用新 方法构建椭圆球面波时域正交脉冲集,利用基于椭圆球面波的非正弦调制方法调制发送数据 ,利用基于椭圆球面波的非正弦相关解调方法解调发送数据。对基于椭圆球面波的非正弦调 制解调原理进行了推导和分析,对基于椭圆球面波的非正弦调制方法频带利用率和峰均功率 比性能进行了理论分析和仿真。在Watterson短波信道模型的基础上,仿真了基于椭圆球面 波的非正弦相关解调误码率性能。理论分析和仿真结果表明,基于椭圆球面波的非正 弦短波通信方案频带利用率高,可快速接近2 bit/s·Hz-1的理论极限值,频带利用 率、峰均功率比和误码率性能均优于OFDM技术。     

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。     

一种改进的BPSK/QPSK信号调制识别算法

提出了一种基于顺序统计量特征的二进制相移键控/正交相移键控（BPSK/QPSK）信号调制识别算法。对观测信号进行平方并做离散傅里叶变换运算，将变换结果取模后去除最大值得到修正频谱，并取修正频谱的最大值作为识别特征量，利用恒虚警准则确定判决门限，将识别特征量与门限比较来完成对BPSK和QPSK两种调制信号的识别。计算机仿真表明，当信噪比适度时，所提算法可对BPSK及QPSK两类信号进行有效识别。当信噪比大于1 dB时，算法的平均识别正确率达到90%以上。     

一种级联两箱通用数字预失真器及其辨识算法

提出了一种由单形规范线性分段(SCPWL)函数与记忆多项式级联的数字预失真器，并给出了复数域两步最小二乘参数辨识算法。不同于以往一种预失真器适用一种功放模型的情况，所提的预失真算法利用SCPWL函数的分段特性以及记忆多项式的非线性记忆特性，在完成参数辨识的同时自动地调整结构，可适用于传统以及强非线性新型功放模型的线性化补偿。将所提预失真器分别应用于传统记忆多项式、两箱模型以及新型包络跟踪功放。经过计算机仿真，功放输出的幅频特性和频谱曲线表明所提预失真器能够有效地补偿多种功放的非线性特性。算法仿真比较结果也表明，针对包络跟踪功放，所提复数两步最小二乘算法的邻道泄漏比(ACLR)可改善约35 dB，性能优于最小均方(LMS)类算法约30 dB。     

一种适合软件无线电的符号定时估计算法

研究了一种适合软件无线电的符号定时估计算法,该算法通过并行方法估计线性和非线性调制方式的符号定时。计算机仿真结果表明,通过设置观测时间间隔数和并行估计样本值的个数,算法可以满足多种调制方式对符号定时估计指标的要求,在误比特率为10-5时,相对于理想的相干解调性能,信噪比最大损失0. 5dB。算法全数字实现,复杂度适中,适合于软件无线电系统中对多种调制方式条件下符号定时估计的需要。     

基于噪声分布特性的脉冲信号自适应门限检测

通过分析数字脉冲信号幅度差分的概率分布模型，得到噪声的分布特性，并推导出用于脉冲信号检测的时域自适应门限。该门限可通过计算信号幅度差分绝对值的均值直接得到。该门限算法的第一个优点是门限值仅与噪声统计特性相关，与信号无关，可避免传统自适应算法中检测门限被强信号拉高，造成强信号附近的弱信号漏检问题;第二个优点是计算复杂度低，非常适合于实时性要求高而资源不足的现场可编程逻辑门阵列（FPGA）等硬件平台实现，为脉冲信号的实时捕获和后续的侦察处理提供支撑。     

基于参数选择的数字预失真处理

数字预失真系统中，高精度预失真通常需求高阶多项式，而高阶多项式会导致预失真计算量的急剧上升。针对记忆多项式级数与预失真精度的矛盾，提出了一种基于参数选择的数字预失真结构，使用低阶多项式实现了对复杂度高的功率放大器高精度预失真处理，同时避免了计算量的上升。基于一组功率放大器的实测数据进行仿真，验证了参数选择方法相比于传统方法在同计算量的条件下精度的提升；并以正交频分复用信号作为输入信号进行仿真，得到了21 dB的邻近信道功率比抑制效果，相比于传统方法有6 dB的提升。     

一种适用于16QAM的自适应阈值载波锁定检测算法

为避免传统16阶正交幅度调制（16-Quardrature Amplitude Modulation，16QAM）载波锁定指示锁定阈值受输入信号电平的影响，提出了一种基于归一化信号高阶矩的16QAM载波锁定检测算法。针对传统基于固定阈值的检测算法在数据不满足均匀分布时失效的情况，提出了一种基于输入数据统计特性的自适应阈值载波锁定检测算法。实验结果和工程应用结果表明，所提出的自适应门限能更好地适应不同数据下的载波锁定检测。该方法已经在某卫星对接试验中得到了应用验证，取得了满意的效果。     

Like An Angel

The central bank of China has raised her deposit rate for 6 times,and deposit reserve rate for 16 times,since last year up to now,which resulted to a great suffer to those small and medium sized enterprises in finance collection.30 percent of China s small and medium sized enterprises have to be closed down, and 60 percent of them are because of finance problem.How to gather the fund is the biggest obstacle for China's enterprises to grow.     

Zhang Hao,Health of wealth

Contribution to the society Zhang Hao owns great opportunity to store intelligence and knowledge, in her early year.Zhang Hao was graduated from Economic Management Department of People's University in 1983 and later finished her study in Advanced Training Program of CEO of Chinese Direct Selling Enterprises in Peking University.     

Investigation on Dumpling Issue——Remarks from China''''s State Council Information Office

From the very beginning of the dumpling incident,China has pav great concernontheoroblem and moved rapidly to find the reason and take further actions.Series of investigations carried in both countries by co-organized experts'team received a primary fruit as the true picture of the incident.Each time,China IS sparing no effort responsibly to solve the products quality dilemma,which other countries face in the same.     

Beijing: Next International Financial Hub?

Beijing‘s new financial dream On May 5,the Beijing Municipal Government released a notice regarding its plans to spur the financial industry, vowing to put forth a strong effort to become the national financial decision- making center,financial management center and financial information and ser- vices center,and formally announcing its ambitious aspiration to become a financial hub with international influence.     

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.     

Investment Guide to Qingdao

Qindao is the host city for several events of the 2008 Olympics, including the sailing competitions which will take place along the shoreline by the city. The unique architecture combination of German and Chinese in the city centre, the German demographic roots and a large Korean expat population, give Qingdao a distinct atmosphere. Too many eye-ball catching strengths turn the beautiful seashore city into an attractive place in foreign investor＇s eyes.     

A New Era for Global Business

Asia Society is the leading global organization working to .strengthen relationship and promote understanding among the people, leaders, and institutions of Asia and the U.S. Every year the Society presents a high-profile Corporate Conference in a selected city in Asia to examine the implications of macroeconomic trends and geopolitical developments for the region and the world. It provides a leading forum for executives to meet the policymakers and business leaders who shape the Asia Pacific business environment.     

China-Pakistan Strengthen Bilateral Custom Cooperation

Mr. Abdullah Yusuf, Secretary General/Chairman, Central Board of Revenue of Pakistart, arrived Shenzhen on April 22 to meet with Mr. Sheng Guangzu, the Chinese Minister for Customs Administration for discussing the bilateral customs issues. During his two-day visit, China＇s Foreign Trade Magazine interviewed to Mr. Abdullah Yusuf in Beijing, he gave the high evaluation on this visit and China＇s great development in the recent years.     

Golden South Africa,Great Development

On the occasion of the 10th panniversary of diplomatic relations between China and South Africa in 2008, China is celebrating ＂South Africa Week＂ to commemorate. H.E. Dr. Nkosazana Dlamini Zuma, the minister of South Africa,