31 大尺度衰落和信道建模 - read

毕 业 设 计(论文)

题 目 无线局域网室内无线信道模型分析及仿真

电信学 院 信通 系 班

学 生

指导教师

设计所在单位

2006年6月

摘 要

在移动通信技术高速发展的今天，无线局域网也迅猛发展，成为当今移动通信的一个热点，越来越受到人们的关注。要实现高质量的无线局域网，保证传输质量，首先要解决的是无线信道问题。无线信道是一个时变的复杂的混合体，对无线局域网来说，主要是在室内环境中，需要综合考虑大尺度和小尺度的衰落，同时还要考虑到802.11标准。应用于室内环境的无线局域网标准有多种，如工作于2.4GHz频段的802.11b/g和工作于5GHz频段的802.11a等，由于工作的频率和采用的技术不同，进而系统的整体性能不同。对室内无线信道模型进行研究对于分析无线局域网系统性能以及无线局域网标准的选择都具有重要的指导意义。

本文在介绍无线局域网802.11a标准的工作原理、结构及其关键技术的基础上，重点阐述了无线局域网中无线信道的大尺度衰落、小尺度衰落及其建模仿真的方法，确定了适用于室内环境的大尺度和小尺度衰落模型，基于MATLAB编程实现了802.11a通信链路仿真系统中的无线信道模块，最后对链路仿真结果进行了分析，仿真结果表明无线信道模块实现正确。

关键词：无线局域网，信道模型，大尺度衰落，小尺度衰落，多径，OFDM

ABSTRACT

Nowadays, the mobile communication has a great development, and so does the WLAN, which has become a hot point in mobile communication area, more and more attention has been taken to it. In order to build a high quality WLAN, making sure the communication quality, fist of all the problem of wireless channel should be studied. Wireless channel is a time-varied environment mixed with many complex factors, to WLAN, it is mostly the indoor environment, both the big scale fade and the small scale fade should be considered. At the same time the consideration should include 802.11 standards. There are many kinds of WLAN standards, such as 802.11b/g at 2.4GHz and 802.11a at 5GHz, because of the work frequency and technique is different, the whole system performance is different. Studying the indoor wireless channel will have important instructing value in analyzing WLAN system and choosing WLAN standards.

This text first gives an introduction of WLAN 802.11a standards' work principle, structure and key technique. The most important part in this text is WLAN wireless channel's big-scale fading and small-scale fading and their modeling and simulating methods. The models of big-scale fading and small-scale fading are selected and the wi