臺灣博碩士論文加值系統

在這次研究中我們探討的是只須在TCP來源端做改變的TCPW。基本上它與TCP Reno不同於TCP擁塞控制演算法。其設計為AIAD演算法，而不是AIMD法。
這個模擬模型是建構在會遺失封包的無線區域網路通道上。經由ns-2的模擬結果顯示，TCPW在會大量遺失封包的無線區域網路中，其平均吞吐量優於TCP Reno。同時也顯示TCPW在有瓶頸頻寬及緩衝記憶體不足的環境中有好的表現。

In this thesis we studied the TCPW which requires modifications only in the TCP stack at the source node. Basically it differs from TCP Reno in the TCP congestion control algorithm. It was designed by following the principle of Additive Increase Adaptive Decrease (AIAD), not that of additive increase multiplicative decrease (AIMD, used in TCP Reno.
Our simulation considers both the core links and the WLANs. The results show that, TCP Westwood (TCPW) outperforms TCP Reno in terms of average throughput when bursty losses occurred over the wireless channel. The results also show that TCP Westwood (TCPW) is better under bandwidth bottleneck and limited buffer size.

ACKNOWLEDGEMENTS…..………..………………..…………….…iii
ENGLISH ABSTRACT……….……………….………………………...iv
CHINESE ABSTRACT…….……………...............……………………..v
TABLE OF CONTENTS….……………......…….…………..………….vi
LIST OF FIGURES………………………………………………..……viii
CHAPTER
1 INTRODUCTION….…...………………………………………1
1.1 Introduction of TCP ……………………………………..1
1.2 Introduction of TCP Westwood …………………………3
1.3 Organization of the Thesis ....………..…........…………..7
2 WIRELESS LAN BACKGROUND…………………………….8
2.1 An Overview of Wireless LAN ………………………….8
2.2 Wireless LAN local error control ……………………....10
3 AN OVERVIES OF TCP WWESTWOOD..…………………...11
3.1 Overview ..………………………………………...…….11
3.2 Setting cwnd and ssthresh in TCP Westwood …………..12
3.3 Bandwidth Estimation………………………………......14
4 SIMULATION RESULTS…..…............................…………….16
4.1 Compare TCP Reno, TCP Westwood, and Its Variants…16
4.2 Comparison between wired LAN and wireless LAN…...17
4.3 Performance of Congestion Control with Bandwidth Bottleneck.........................................................................23
4.4 Comparison with Different Buffer Sizes ……………….26
5 CONCLUSIONS..........................................................…...……29
REFERENCES …........…………………….…………………...……..….30

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