臺灣博碩士論文加值系統

TCP/IP 是現今主要的網際網路協定，它原本只是針對有線環境的擁塞控制而設定的。封包在無線環境中經常的random loss是有線環境中所沒有的。因此，TCP在無線環境的效能比在有線環境還差。所以用數學分析來模擬無線TCP的效能是有必要的，此外在我們的分析中也考慮到RED及DropTail路由的效應。因而無線TCP的傳輸率可以用RED路由的平均佇列長度及無線環境random loss機率的函式來表示。

此外我們也使用Forward Error Correction 來減低封包的遺失率，並且自動的調整Reed-Solomon碼的比率來最佳化無線TCP的傳輸效能。而使用Reed-Solomon碼的無線TCP傳輸率也以數學來加以分析。

TCP/IP is the dominant protocol in today’s Internet. Basically, it was designed only to perform congestion control for wired environment. The wireless environment is quite different from wired one, and packet loss in the wireless environment is due to random loss frequently. For this reason, the performance of TCP in the wireless environment is worse than in the wired one. Therefore, modeling the wireless TCP throughput by mathematical analysis is a desirable method to understand the performance of TCP in wireless. In addition, the effect of RED and DropTail routers are considered in our mathematical analysis. The wireless TCP throughput is modeled as a function of wireless loss rate and average queue length of RED router.

Moreover, we use Forward Error Correction to improve the packet loss rate and maximize the wireless TCP performance by adjusting the Reed-Solomon code rate automatically. The throughput of wireless TCP with Reed-Solomon codes was also modeled.

Content
Chapter 1 Introduction 1
Chapter 2 Related Works 4
2.1 Overview of Reed-Solomon Codes 4
2.1.1 Introduction of Reed-Solomon Codes 4
2.1.2 Properties of Reed-Solomon Codes 6
2.2 TCP Problems over Wireless Links 8
2.2.1 Corruption 8
2.2.2 Excess Delays 9
2.2.3 High Loss Probability 10
2.3 Algorithms improving TCP performance over wireless links 10
Chapter 3 Performance Analysis of Wireless TCP 13
3.1 Wired TCP Throughput Model 14
3. 2 Mathematical Model for Wireless TCP 16
3.2.1 A Single Congested Router 17
3.2.2 A Network of Multiple Congested Routers 18
3.2.3 Multiple Congested Routers And Wireless Links with RS Code 21
3.2.4 DropTail Routers 23
Chapter 4 Simulations 24
4.1 A Single Congested Router 24
4.1.1 TCP Reno for A Single Congested Router 25
4.1.2 TCP with RS Code for Single Congested Router 28
4.2 A Network of Multiple Congested Routers 29
4.2.1 TCP Reno in A Network of Multiple Congested Routers 30
4.2.2 TCP Reno with RS Code in A Network of Multiple Congested Routers 32
Chapter 5 Experiments for Wireless TCP with Reed-Solomon Codes 33
Description & Components 34
5.1 Experiments for Wireless TCP with Reed-Solomon Codes 35
5.1.1 RS with Block Size 127 Symbols 35
5.2 RS with Block Size 63 Symbols 37
5.3 Decoding Time for Various RS Block Size 38
Chapter 6 Experiments for Wireless TCP with Adaptive Reed-Solomon Codes 41
6.1 ARSC Design 42
6.1.1 Adaptive Reed-Solomon Code in Client Site (ARSCCS) 42
6.1.2 Adaptive Reed-Solomon Code in Server Site (ARSCSS) 42
6.1.3 Communication Between ARSCCS And ARSCSS 45
6.2 The State Diagram for Adaptive Reed-Solomon Codes 46
6.3 Experiments for Adaptive Reed-Solomon Codes 47
Chapter 7 Conclusions 53
Bibliography 55

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