The characteristics of the underwater acoustic channel are analyzed in this thesis , with the emphasis on the multipath propagation characteristics . and the underwater acoustic multipath channel model is established on the basis of ray theory 在本论文中，我们对水声信道特性，尤其是水声信道的多径传播特性进行了分析，并且在声线理论的基础上建立了水声多径信道模型。
Then critical technologies of simulation system are discussed , including frame processing structure , fh sequence generator , simulation models of path loss and multipath channel , simulation of signal propagation delay and jamming signal etc 其次，讨论了仿真系统实现的关键技术，包括帧处理结构、跳频序列发生器、路径损耗与多径信道仿真模型、信号传播延时及干扰信号的仿真等。
A chip - level channel estimation technique with varing step size is brought forward to improve the performance of rake receiver for wcdma downlink . for the first place , the effects of different channel parameters for wcdma downlink channel estimation are analyzed 信道估计是rake接收机的关键技术,其目的是获得不同多径信道的参数估计值,估计出移动信道的衰落冲激响应,能够提高rake接收的性能。
In order to utilize the resoluble ability of signals and improve resistant ability to multipath fading , the rake receiver is a good option . but proper rake operation requires information about the delays and attenuations of the channel paths which is difficult to obtain 本文以uwb通信系统为背景,主要研究uwb系统室内密集多径信道的信道估计方法,以及基于turbo原则的迭代信道估计的接收机结构。
At last , two ranging schemes based on the cyclic prefix and pilot sequence were developed , and the performance of ranging based on the novel pilot sequence was mainly analyzed . and theory analysis and computer simulation results were presented in the awgn channel and multi - path channels 最后，结合定时同步提出了两种测距方案，主要分析了基于新的定时同步方法的测距方案性能，并给出了在加性高斯信道和多径信道下的理论分析和仿真结果。
When the channel changes rapidly , this proposed dynamic algorithm is efficient . other than above , this paper also studies the character of ofdm under multipath fading and gives the baseband computer simulation by systemview . at last , it performs ofdm dsp hardware plug - in simulation 利用systemview软件进行模拟多径信道下ofdm系统性能仿真，并探讨了仿真过程中的一些问题，最后搭建了ofdm基带仿真系统，并利用tms320c54dsp芯片，进行了ofdm硬件嵌入式仿真。
Traditional delay estimation based on ica requires the trail sequences to initialize the receiver , but the new algorithm based on ica does not need the trail sequences . it is based on the channel character of downlink , using the ica algorithm to estimate the multi - path mixture matrix , then , find the delay information which is embodied by the column vector of the mixture matrix . the simulation results show that it does enhance the performance of traditional detector without wasting the invaluable frequency resource 传统的信道估计算法需要训练序列使接收端的参数调整到理想状态，而本文提出的基于ica的信道估计的多用户检测算法不需要训练序列，它是利用下行信道的固有特点，用ica的盲源分离法估计出多径信道的卷积矩阵，从而从中提取出信道的延迟信息，仿真实验结果证明这种方法在节省了频谱资源的同时取得较好的估计效果，使得传统的接收机的误码性能得到了很大的提高。
In wcdma system which uses direct sequence to spread spectrum , the spread spectrum code ( pn code ) phase of the receiver must be synchronized with that of the received signal precisely to despread and demodulate the signal correctly . multipath channel exists in the mobile communication environment for the radio signal reflection by obstacles between transmitters and receivers . by using the autocorrelation of the spread sprectrum code , rake receiver can process received signals and therefore multipath components can be resolvable 在wcdma系统中,为正确解扩解调接收到的扩频信号,接收机本地产生的扩频码( pn码)相位必须和接收信号中的扩频码相位完全同步;同时移动通信环境中的传输信号由于接收机和发射机之间的直达路径有可能被建筑物或其他障碍物所阻碍,总是经过折射或反射的多条路径后才到达接收机,从而产生多径信道。
The paper provides a visual modeling scheme using object - oriented technology , and does experiments for current impulse response models from model change to parameter design to graphical modeling . the frame is a visual solve for simulation analysis and transmission forecast of radio channels . on the one hand , the paper takes classic radio channels as independent objects and builds their graphical models , comes into being a visual universal model library 本文深入研究了无线通信信道、尤其是多径信道的传输特性，提出一种基于面向对象的可视化无线信道建模和仿真方案，对具有普适性的信道冲激响应模型进行了从模型转换、参数设计到图形建模等环节的实验，建立起统一的、一体化的信道建模仿真实验框架，为无线移动信道的分析、建模、仿真和传播预测提供了一种可视化的解决方案。
From simulation results , we get the following main conclusions : 1 ) the convergence performance can be improved with the ist - tap initialization strategy for the underwater acoustic channel established in this paper . 2 ) both the convergence rate and the steady - state value of the average squared error should be taken into account when choosing the step - size 得到的主要结论为：对于本文所建立的水声多径信道，盲均衡算法采用第一个抽头初始化方案其收敛性能较好；选取迭代步长时要兼顾收敛速度和稳态误差；在保证收敛性能的基础上，可选择阶数较小的均衡器。
