但是这种正交性却被多径衰落信道破坏，产生了多码道干扰，严重影响了系统高速传输数据的性能。
The orthogonality, however, is impaired by multipath fading channels, thus causing multicode interference (MCI) and deteriorating the system's performance at high data transmission rates.
第二章分析了无线信道的多径效应和小尺度衰落效应。
The second chapter of this paper analyzes the multipath effects and fading effects of wireless channel.
特别地，能够利用发送天线和接收天线之间的多径分量来抵抗信道衰落影响，并且改善通信链路可靠性。
In particular, a large number of propagation paths between transmit and receive antennas can be utilized to combat channel fading effect and gain link reliability.
在多径衰落信道下，这些参数是很难获得的。
These parameters are difficult to obtain in multipath fading channels.
在此基础上提出了一种新的无线信道模型；结合分形插值方法，对多径衰落信号的重构进行了研究。
Then a novel channel model is proposed and fractal interpolation is applied to reconstruct the signals.
在多径衰落信道CDMA系统中，扩频码设计与联合检测为提高系统容量的两个重要手段。
Spreading code design and joint detection are two efficient ways to increase CDMA system capacity in multi-path fading channels.
他能有效地对抗多径效应，消除符号间干扰，对抗频率选择性衰落，而且信道利用率高。
It can waken the multipath effect availably, eliminate symbol interference and fight against frequency select fading. Moreover, the channel utilization rate is high.
本文在瑞利衰落模型下，研究了高频电离层信道中多径时延与多普勒频移的随机特性。
In this paper, with Rayleigh fading the random characteristics of multipath time delay and Doppler shift in HF ionospheric channels is discussed.
本文研究多径衰落信号的多重分形性质，分析并指出了信号多重分形维数是描述无线信道传播特性的重要参数；
Fractal characteristic of multipath fading signal is studied in the paper which shows that multifractal dimension is a key parameter for describing the signal propagation in wireless channels.
本文将分形理论引入多径衰落信道的描述，提出了一种利用分形滤波进行最小均方误差意义下信道参数估计的方法。
The fractal theory was applied to describe multipath fading channels, and a novel channel estimation scheme using fractal filter in the sense of minimum mean square error (MMSE) was presented.
由多径色散及多普勒频移造成的频率—时间选择性衰落是城市移动无线信道的一个重要特性。
The frequency time selective fading resulted from multipath dispersion and Doppler frequency shift is an important characteristic of urban mobile radio channel.
本文主要介绍由实验测量和统计分析方法得到的UWB信道模型，包括UWB系统的路径损耗模型和多径衰落模型。 u。
This paper will introduce the channel models for UWB, which include path loss models and multi-path fading models obtained by large measurements and statistical analysis.
OFDM技术可以把频率选择性衰落的信道转化成一组正交的平坦衰落的信道，因此可将OF DM技术应用在MIMO系统中来克服多径衰落的影响。
OFDM has the ability of transforming the frequency-selective channel into a collection of parallel flat-fading subchannels and therefore can be adopted in MIMO systems to combat multi-path effects.
本文第一章绪论首先分析了无线信道的特性，介绍了小尺度衰落模型，多径衰落模型以及WSSUS信道模型。
The first chapter introduced the characteristics of the wireless channel, the small-scale fading model, multi-path fading model and WSSUS channel model.
在短波通信系统中，由于多径效应常常引起信道衰落，直接结果是码间串扰非常严重。
In shortwave communication system, Intersymbol Interference is serious and signal is distorted extremely because of fading channel resulted in by the effect of multipath.
研究表明，该算法既能在AWGN信道中也能在多径衰落信道中完成频偏跟踪工作。
The study shows that the algorithm can complete frequency offset tracking in AWGN channel and multipath fading channel.
重点分析了实现信道特性仿真的两种算法：慢衰落的相关性整形和频率选择性多径衰落。
Two simulation algorithms of realization channel characteristic are analyzed emphatically: shaping of slow fading with correlation and generation of frequency-selected multipath fading.
然后在分析移动信道衰落特性的基础上，分析了多径瑞利信道的数学模型，并对基于这种模型的各种信道估计性能进行了仿真分析。
Then mathematic model of multi-path Rayleigh fading channels are presented based on the discussion of mobile fading channel characteristics. At last, the simulation results and analysis are given.
算法所用的小波变换相位信息特征对平坦衰落信道具有衰落不变性，对频率选择性衰落信道也具有很强的抗多径能力。
The phase information of wavelet transform used in the algorithm is invariant with respect to flat fading, and can resist multipath fading of frequency-selecting channel in quite a few degree.
空地通信信道的主要统计特性包括多径衰落特性、多普勒功率谱和时延功率谱。
The statistic model of air-ground radio communication channel is characterized by the multipath fading, Doppler power spectrum and delay power spectrum.
算法根据多径信道选择性衰落的特性，结合查表法和拉格朗日乘子的混合迭代搜索法，最优地分配各个子载波的传输比特数。
Based on the characteristic of multi-path frequency selective channel, the algorithm combines rapid table lookup and Lagrange-multiplier method to iteratively search the optimal bit allocation scheme.
无线环境中存在多径衰落、多谱勒频移和信道快速时变等许多不利因素。
There are lots of disadvantages in wireless environment, such as multi-paths fading, Doppler frequency shift and fast time varying of channel.
在多径衰落信道中，本文分析了导引辅助的二维扩频相干解调的误码率性能。
In this paper, we analyze the BER performance of pilot symbol assisted two-dimensional spread spectrum systems with coherent demodulation in multi-path fading channels.
在宽带无线数字通信系统中，影响信息高速传输的最主要的一类干扰是由信道的多径效应所引起的频率选择性衰落。
The bandwidth efficiency and ability to combat the effects of frequency selective channels are critical issues in the design of wideband wireless digital communications system.
现代短波通信系统，其信道大多数具有频率的选择性，多径传输产生了信号的相干衰落与符号干扰。
In modern shortwave communication systems, the channels are mostly frequency-selective, multipath transmission causes the coherent attenuation and symbol interference.
算法所用特征对平坦衰落信道具有衰落不变性，对频率选择性衰落信道也具有很强的抗多径能力。
The feature used in the algorithm is invariant with respect to flat fading, and can resist multipath fading of frequency-selecting channel in quite a few degree.
实际上，数字蜂窝移动通信中的多径衰落信道特性已成为许多理论分析和现场实测的课题，并已得出了许多有价值的结论。
In fact, the characteristics of the multipath fading channel in digital cellular mobile communications have become the research of academic analysis and field measure.
在未来的宽带无线通信系统中，存在着两个严峻的挑战：无线信道的多径衰落和频谱效率。
There are two serious challenges in the future broadband wireless communication systems: multi-path fading in the wireless channel and spectral efficiency.
本文分析了数字电视地面广播通信信道具有长脉冲响应的多径衰落的特点，从频域上表达了其多径衰落信道模型；
The characteristics of the digital television terrestrial broadcasting (DTTB) channels with long impulse responses are analyzed, and the frequency domain multipath channel model is given.
本文中提出的这种算法适用于多径衰落信道，能很好抵消多址干扰和克服多径衰落。
It can be used in multipath channels to suppress multi-address interference and overcome multi-channel fading.
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