考慮傳輸壅塞之網路控制系統的模糊方法

在本論文中，我們提出適用於非線性控制系統的T-S模糊模式追蹤控制設計方法，分別處理網路中的壅塞控制和遠端控制問題。在網路壅塞控制中，我們並不是要發展新的TCP通訊協定，而是在現行的TCP Vegas協定架構下，發展新的主動式佇列管理(AQM)方法。我們把TCP網路視為一個控制系統，建構它的數學模型後，透過佇列長度和傳送的速率來測量網路壅塞的程度，經由所設計的模糊控制器去調整路由器上佇列長度，最後使用網路模擬軟體NS-2來實現網路環境與模糊控制器，而實驗結果也顯示，不論是封包排隊長度、頻寬利用率及丟包狀況，皆驗證了所提出的模糊控制器具備強健性以及高效率的控制效果。我們也將TCP Vegas協定加入了Snoop協定之後應用在無線網路傳輸方面，來改善無線網路高位元錯誤率的問題，也能得到不錯的效果。在網路遠端控制中，我們考慮傳統PWM降壓型(Buck)電源轉換器作為遠端系統來進行穩壓控制，在實作上利用PCI-6221資料擷取卡以及Visual Basic來實現模糊控制器。我們分別使用UDP和TCP兩種協定來做比較，經由實驗結果證明利用TCP的暫態反應時間比較慢，因為TCP含有確認機制來保證資料能被正確接收，導致傳送速度比較慢，而UDP並無確認機制，所以UDP的傳送速度會比TCP來的快。最後我們經由實驗展現使用UDP作為遠端控制電源轉換器的滿意效果。

關鍵字

模糊追蹤控制；降壓型電源轉換器. ；傳輸控制協定；線性矩陣不等式；用戶資料流協定； T-S模糊模式；主動式佇列管理

並列摘要

In this thesis, we propose a Takagi-Sugeno (T-S) fuzzy controller for Internet congestion control and remote control. Linear matrix inequality (LMI) technique is utilized to obtain the control feedback gain. In Internet congestion control, the mathematical model of TCP Vegas is established based on TCP Vegas protocol. Moreover, we use the queue length and incoming flow rate to measure the degree of congestion effect on Internet to regulate the queue length at a specified level. We use the network simulation (NS-2) to carry out the experiment. Compared to other AQM schemes, the experiment results show that the proposed AQMs have better performance in terms of packet loss, throughput and the fluctuation of queue length. In remote control system, voltage control of power converter is used to compare the differences between UDP and TCP protocol. Experimental results show that the transient response of TCP protocol is slower. This is because TCP has acknowledgments algorithms to ensure the data have been received and therefore cause slower transmitting rate. UDP protocol is only responsible for sending the data without ensuring whether the data is received or not. Therefore, transmitting rate of UDP is faster than that of TCP. Our experiments reveal that the remote control of the converters using UDP illustrates satisfactory results.

並列關鍵字

User Datagram Protocol(UDP) ； Fuzzy regulation control ； Active queue management(AQM) ； Transmission Control Protocol(TCP) ； T-S fuzzy model ； Buck converter. ； Linear matrix inequality(LMI)

參考文獻

[2] V. Jacobson,“Congestion Avoidance and Control”, ACM SIGCOMM 88, 1988.

[3] V. Jacobson,“Modified TCP Congestion Avoidance Algorithm”, mailling list,

[4] L. Barkmo and L. Peterson,“TCP Vegas:End to End Congestion Avoidance on a Global Internet”, IEEE Journal on Selected Areas in Communication, Vol 13, No.8(October 1995) pages 1465-1480.

[6] S. Floyd, and V. Jacobson,“Random Early Detection Gateways for Congestion Avoidance”, IEEE/ACM Transactions on Networking, Vol. 1, No. 4, August 1993.

[7] S. Athuraliya, S.H. Low, V. H. Li, and Q. Yin,“REM: Active Queue Management”, IEEE Network Magazine, Vol. 15, No. 3, May/June 2001.

國際替代計量

考慮傳輸壅塞之網路控制系統的模糊方法

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