【作者】 张凯；

【导师】 谭晓衡；

【作者基本信息】 重庆大学 ， 通信与信息系统， 2008， 硕士

【摘要】 在无线通信系统中,由于多径效应常常引起信道衰落,直接结果是码间干扰非常严重。为了克服码间干扰所带来的信号畸变,必须在接收端增加均衡器,以补偿信道特性,正确恢复发送序列。盲均衡器由于不需要训练序列,仅利用接收信号的统计特性就能对信道特性进行补偿,消除码间干扰。因而,盲均衡技术在数字通信、雷达、地震和图像处理等领域获得了广泛的应用。本文首先分析了无线通信信道的传输特性以及码间干扰产生的原因,接着概述了自适应均衡技术,对常用的Bussgang盲均衡算法进行了研究、分析和仿真。在信道盲均衡器的计算机仿真部分,通过MATLAB建模仿真,分析了噪声和步长对恒模(CMA)算法的收敛性能的影响。然后利用Simulink仿真工具,构建QPSK调制系统平台,分别在高斯白噪声信道和多径信道的环境下,通过眼图、星座图和误码率对CMA算法的性能做了进一步的分析。在信道盲均衡器的实现部分,本文探讨了以FPGA为平台,利用VHDL语言,使用TOP-DOWN的数字系统设计方法,实现了基于判决引导(DDLMS)算法的盲均衡器。本文详细阐述了基于FPGA的信道盲均衡器的设计思想,设计结构和VHDL设计实现,以及分别给出了各个模块的结构框图和验证结果。本文所设计和实现的信道盲均衡器,为电子设计自动化(EDA)技术做了有益的探索性尝试,对今后无线通信系统中的单芯片可编程系统(SOPC)的设计应用有着积极的借鉴意义。更多还原

【Abstract】 In wireless communication system, Inter-symbol Interference is serious and signal is distorted extremely because of fading channel resulted in by the effect of multipath.The adaptive equalizer should be used in order to compensate channel characteristic and recover received signal correctly.Blind equalizers can compensate channel characteristic and reduce Inter-symbol Interference without training sequence,so are used widely in many fields such as digital communication system,radar system,earthquake and image processing system and so on.The characterization of the wireless communication channel and the appearance of ISI are discussed in this paper firstly.Then, the adaptive equalization technology are summarized. This paper analyses and simulates the common blind equalization algorithms based on Bussgang family.In the computer simulation part of the channel equalizer, this paper simulate the CMA by the MATLAB software.The effect of noise and step-size to the convergence are discussed with the module.Then we establish the QPSK modulation plat with the Simulink tool.In the AWGN and multi-path channels,the eye diagram,the constellation diagram and the BER curve are discussed furtherly.During the process of the implementation, we establish the FPGA hardware plat,and VHDL code had been coded to implement blind equalizer of DDLMS algorithm based on TOP-DOWN digital design methodology. Design principle,structures and VHDL implementations of modules in enhancement blind equalizer are described in detail in follow sections. Each section closed with the structure graph and the test results of module in verification.This thesis investigates the design technologies of EDA (Electronic Design Automation) by means of designing and implementing blind equalizer. It provides preliminary study for large scale SOPC (System on Programmable Chip) in wireless communication system field.更多还原