移动通信中信道均衡技术研究和仿真.doc

毕业设计(论文)任务书
题目移动通信中信道均衡技术的研究与仿真

起讫日期年月日至年月日

学生姓名专业班级
所在学院电气信息学院
指导教师职称讲师
所在单位电子信息工程教研室
2013年 6 月日
摘要
在移动通信领域中,码间干扰始终是影响通信质量的主要因素之一。为了提高通信质量,减少码间干扰,在接收端通常采用均衡技术抵消信道的影响。由于信道响应是随着时间变化的,通常采用自适应均衡器。自适应均衡器能够自动的调节系数从而跟踪信道,成为通信系统中一项关键的技术。
本篇论文在对无线通信信道进行研究的基础上,阐述了信道产生码间干扰的原因以及无码间干扰的条件,介绍了时域均衡的原理。深入研究了均衡器的结构和自适应算法,在均衡器的结构中主要介绍了2种自适应均衡器结构即线性横向均衡器和判决反馈均衡器,并对这几种结构进行了比较。对于系数调整算法主要介绍了常用的几种算法,包括LMS算法、盲均衡常用的恒模算法(CMA),并讨论了它们各自的优缺点。最后选用线性横向均衡器结构与上述2种系数调整算法,利用MATLAB进行仿真,并对结果进行分析与比较,实验结果为CMA算法整体较LMS算法好。
关键字:均衡器 LMS CMA MATLAB
Abstract
In the field of munications, the inter-symbol interferences (ISI) are always one of the primary factor which effects transmission. Adaptive equalization is mainly solution of dealing with ISI. Equalizers are often used bat the influence of channels for munication’s quality and decreasing ISI in receivers. Sometimes, channel response varies due to time, the adaptive equalizer is always necessary. Equalizer coefficients can be automatically adjusted to track the channel as a munication system technology.
On the basis of studying on munication channel, this thesis discusses the reasons of resulting inter-symbol interference (ISI) and presents the theory of adaptive equalizers. The equalizer structures and the adaptive algorithm are particularly studied in this paper. four adaptive equalizer structures are mainly introduced pared, such as linear horizontal equalizer, decision feedback equalizer. Then we research monly used algorithms of the adaptive equalizer, including LMS, CMA, and discuss their respective advantages and disadvantages. Finally, the adaptive equalizers using LMS, CMA is simulated by the MATALB. The simulation results show that CMA is better than LMS.
Keywords: equalizer LMS RLS CAM MATLAB
目录
第一章绪论 1
1
(外)研究现状 1
2
第二章信道、码间干扰及均衡技术简介 4
信道 4
码间干扰 5
6
7
线性横向均衡器结构(LTE) 8
判决反馈均衡器(DFE) 9
本章小结 11
第三章移动通信中均衡算法的研究 12
最小均衡误差算法(LMS) 12
盲均衡算法 1