衰落

Based on the analysis of the Doppler effect of the mobile channel, the performance of two MIMO-OFDM systems (STTC-OFDM and SFBC-OFDM) in the fast-moving environment is studied. Then, the algorithm for channel estimation based on the training sequence is extended into the fast-moving environment by introducing the space-frequency coding, the method of the equal-interval pectinate pilot-inserting, and the complete Maximum-Likelihood space-frequency decoding.

针对快速移动环境中存在的多普勒效应，研究了两种多输入多输出正交频分复用系统在快衰落信道中的误码性能，采用空频编码梳状等间隔导频插入方式，以及完全最大似然空频分组码解码算法，使用导频与接收信号进行信道参数估计，将一般多输入多输出正交频分复用系统中的基于训练序列的最小均方误差信道估计算法推广到了快衰落信道环境中。

For the instability of the wireless channel and remotion of the terminal, the performance of the wireless channel is not good as the one of the wire channel, which is not fit for transmitting high-speed date.

中文摘要：无线信道的衰落效应和终端的移动严重制约了通信系统的性能，因此克服信道衰落效应，提高频谱利用率，确保数据高效可靠的传输是个非常重要的研究问题。

In frequency selective fading channels, different channel has different fading, that is to say, different channel has different transmission quality.

在频率选择性衰落信道中，不同的子信道受到不同的衰落，也就是说有不同的传输质量。

Doppler frequency offsets in rapid mobile environments result in both the fast fading of radio channels and intercarrier interference in Orthogonal Frequency Division Multiplexing systems. In order to combat the impact of ICI on OFDM systems in fast fading channels, an ICI mitigation technique is proposed in this paper.

针对高速移动环境下多普勒频偏造成移动信道的快衰落和正交频分复用系统中子载波间干扰问题，提出了一种适合快衰落环境的OFDM系统子载波间干扰抑制算法。

While Haass thought that, the present powerful US can not cover up the relative decline in the world position and the absolute decline in the influence and independence, monopolarity era is only a twinkle,21th century is a "dangerous and confused nonpolarity era ".

哈斯则认为，当前美国的强大实力不能掩盖其在世界所处地位的相对衰落及其在影响力和独立性上的绝对衰落，单极时代只是历史的一瞬，21世纪是&混乱危险的无极时代&。

Chapter 2 According to the rule of development of Chinese ancient capital, this chapter describes the rise and fall of Jiankang in four phases and points out the chose links between the city's fate and that of the dynasty's. Chapter 3 This chapter explores and finally relocates Jiankang's palace, its capital and its outer city.

第二章 根据中国古代都城由发展、破坏、衰落，到再发展、再破坏、再衰落这样循环往复、螺旋式发展的规律，将建康城的盛衰起伏分为四个阶段进行评述，勾勒出建康城的发展轨迹，指出城市的兴衰与王朝的兴衰密切相联。

Finally we combine turbo code with OFDM technology ,then make some emulations under several kinds of channel fading types in the mobile communication ,it has offered new choice for turbo code applying in fading channel.

所以最后我们将Turbo码与OFDM技术相结合，针对移动通信信道的各种不同的衰落类型进行仿真分析，为Turbo码在衰落信道中的应用提供了新的选择。

So, channel fadings can be exploited. But the multi-user diversity gains are limited in two ways. First, there may be a line-of-sight path and little scattering in the environment, and hence the dynamic range of channel fluctuations is too small.

因此，信道衰落是可以利用的，但这种多用户分集受到两方面因素的制约：一是在LOS和非散射信道环境，信道变化范围太小；二是如果信道衰落变化太慢，则不能满足对时延要求严格的应用。

Information Theory has shown that if the channel fadings of multiple users are independent and scheduling the transmissions to the users when their instantaneous channel quality is near the peak, the total throughput of system can be maximized and it is direct ratio to the number of users.

信息论分析结果表明，如果多用户的信道衰落相互独立，任一时隙只服务于信道最好的用户，则系统的总吞吐量可以最大化，而且与用户数成正比，对于不同的用户数，衰落信道的容量几乎都能高于AWGN信道。

To demodulate the OFDM signals accurately, channel estimation algorithms are adopted. This paper examines the slow-fading estimation algorithms based on block pilot arrangement: LS and LMMSE algorithms, as well as the fast-fading channel estimation algorithms based on comb-type pilot arrangement: linear and transform domain interpolation algorithms.

本文分析了导频分布的两种方案：1块状导频分布，对基于块状导频分布方案的慢衰落信道估计算法：最小平方和线性最小均方误差算法进行了计算机仿真，比较了二者的估计性能，以及各自的优缺点；2梳状导频分布，对基于这种分布方案的快衰落信道估计算法进行了研究，对两类经典算法：线性插值法和基于变换域的插值法分别进行了理论分析和计算机仿真。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了