The new method is a modified pts method , and can make good compromise between performance and computational complexity . the dissertation explores , by means of computer simulation , how the conventional method based on amplitude - limiting and filtering affects the performances of wavelet packet modulation signals , and presents a new method , namely , selective mapping / amplitude limiting / filtering method , which proves to be effective , simple , and have better ber performance 并基于自子波变换和时间、尺度分辨率的概念，从理论和仿真实验两方面对信道建模和时间/尺度rake接收机进行了分析，并与传统的kake接收机进行了比较，结果表明时间/尺度联合分集能有效地克服高速衰落多径信道的影响。
Based on the characteristics of the underwater acoustic channel and channel equalization theory mentioned above , this thesis focuses on the sato and the cma blind equalization algorithms , both of which belong to the bussgang class algorithm . with the work of a lot of computer simulations , the performances of these two algorithms are surveyed from the aspects of equalizer - tap initialization scheme , step - size of the blind algorithms , the order of equalizer , and the signal - to - noise ratio 在水声多径信道特性和信道均衡原理的基础上，本文研究了bussgang盲均衡算法中的sato算法和cma算法，通过大量的计算机仿真工作，采用sato盲算法和cma盲算法对信道进行均衡，分别从均衡器的抽头初始化方案、盲均衡算法的迭代步长和均衡器的阶数以及信噪比几个方面入手，对sato 、 cma盲均衡算法的性能进行了研究。
At this part , it firstly comes up with a quasi - static frequency selective fading channel model . based on this channel model , considering about the characteristics of the model and the lattice reduction complexity , we proposed a new detection strategy , which is the lll detection algorithm combined with decision - feedback technique 首先提出了准静态频率选择性多径信道模型,然后基于该模型提出了一种新的用于准静态频率选择性信道的检测方案,即与判决反馈相结合的格约简辅助检测方案。
The basic principle of ofdm is converting high speed codes flowing in serial transmitting into low speed codes flowing in parallel transmitting , so the period of code is lengthened . it get over multi - channel delay using protective interval . if we deal with the received codes appropriately in receiver , the multi - channel can be matched with single channel , and the effect of channel to signal become multiplication from convolution , so ofdm can eliminate isi effectively Ofdm的基本原理是将高速串行码流变为并行传输的低速码流,增大了每个码元的周期,在传输中又使用了保护间隔来对付多径延迟,在接收端对接收序列进行适当处理后可以将多径信道等效为单径信道,并使信道对信号的影响由卷积关系变为乘积关系,从而可以有效地消除isi 。
This paper firstly introduces the basic principle and characteristics of ofdm , as well as the multi - path channel model and so on , then analyses ofdm system architecture . key technologies such as synchronization and papr of the signal with emphasis on the latter are analyzed . several methods of reducing the papr is presented and analyzed and a novel method is presented 本文首先介绍了ofdm技术的基本原理、特点以及多径信道特征等，然后对ofdm系统结构进行分析；对信号峰平比问题进行了探讨，比较了几类降低峰平比方法的性能，提出了使用虚载波的方法；对同步问题进行了研究，给出了改进的方法；最后，在数字信号处理( dsp )系统上实现了ofdm调制器。
To despread and demodulate the signal correctly in the spread spectrum system , the pn code phase of the receiver must be synchronized with that of the input signal precisely . multipath channel exists in the wireless environment for radio signal reflection by obstacles between transmitters and receivers 在扩频通信系统中，为正确解扩和解调接收到的扩频信号，接收机的pn序列相位和接收信号的pn序列相位必须完全同步；同时移动无线环境中的传输信号总是被收发信机之间的许多障碍物所反射，从而产生多径信道。
