Smith预估器无线网络的拥塞控制机制及仿真研究

摘要近年来，随着无线网络设备的使用越来越广泛,无线网络已经应用到了人们生活中的方方面面。由于无线网络本身带宽小、时滞大的特点，无线网络拥塞控制已经变得非常重要。本文针对无线网络时滞大的特点，在原有主动队列算法的基础上，结合Smith预估器，提出了一种结构简单，易于配置的主动队列管理算法，并与现有的传统PID、RED和REM算法进行比较。通过仿真验证，能够有效克服大时滞对于无线网络队列长度的影响，同时对于系统振荡超调量有着较为明显的限制作用，具有较好的鲁棒性和网络控制性能。65301

毕业论文关键词无线网络拥塞控制大时滞 Smith预估器主动队列管理

毕业设计说明书（论文）外文摘要

Title A Study on Wireless Network Congestion Control Mechanism and Simulation

Abstract

In recent years, as wireless devices have been widely used, the wireless network has been taking part in many aspects of human lives. The congestion control of wireless network has been very important because of the limited bandwidth and the large time delay. In this paper, a new kind of wireless network congestion control algorithm combined with the Smith predictor is designed on the base of former AQM algorithm to deal with the large time delay. The new algorithm is simply structured and easy to be deployed. Then，make comparison with former algorithm like traditional PI,RED and REM. It is illustrated by several simulations that with application of the new algorithm, the negative impact on the queue length stability caused by the large time delay can be overcome. Meanwhile, the overshoot of system can be limited quite obviously. It has robustness and better performance on wireless network control.

Keywords Wireless Network, Congestion Control, Large Time Delay,

Smith Predictor, AQM

1 绪论 1

1.1网络拥塞控制 2

1.1.1 无线网络拥塞概述 2

1.1.2 网络拥塞产生的原因 4

1.1.3 拥塞控制的研究现状 4

2 主动队列管理算法 6

2.1 RED算法 6

2.2 REM算法 6

3 Smith预估控制 7

3.1 Smith预估控制基本思路 7

3.2 TCP/AQM 控制模型及其一阶近似 7

3.3 PI-Smith 预估补偿控制 8

3.4 PI-Smith 算法设计及离散化 9

4 PI-Smith算法的仿真及结果 10

4.1 NS2简介 10

4.2 仿真及结果分析 11

结论 21

致谢 22

参考文献 23

1 绪论

随着无线网络的飞速发展，越来越多的终端设备通过无线方式接入互联网。由于无线网络传输受到非线性、大时滞以及随机链路丢包等因素的影响，经典AQM算法在实际应用于无线网络中时，出现了数据队列收敛速度慢、响应时间长等问题，因此研究适用于无线网络，能够改善无线网络服务质量的拥塞控制机制具有重要意义。 Smith预估器无线网络的拥塞控制机制及仿真研究:http://www.youerw.com/tongxin/lunwen_72858.html