臺灣博碩士論文加值系統

本論文針對在乙太被動光纖網路(Ethernet Passive Optical Network)的差異性服務提出一套基於預測型公平剩餘頻寬分配(Prediction-based Fair Excessive Bandwidth Reallocation，PFEBR)的演算法，目的是為了增加預測的準確度及提升系統效能。在PFEBR 的 Early-DBA機制中，PFEBR 利用統計需求頻寬變異數的方式來決定是否須延遲ONU的REPORT上傳時間，由於每延遲一個ONU的REPORT上傳時間將會增加一個Guard time，如何決定有多少個ONU 必須延遲REPORT的上傳時間，是本篇論文的一個研究課題。另外，PFEBR在預測所需頻寬的預測值上分成三種等級，為了能讓不同服務等級的預測頻寬值隨著需求頻寬的變異而有所不同，以達更確的預測及頻寬分配，本論文利用模糊理論針對所須延遲上傳REPORT的ONU數量及預測頻寬做了最佳化的調整。

A Fuzzy Prediction-based Dynamic Bandwidth Allocation (FPDBA) algorithm is proposed to enhance the differentiated services for EPONs based on the Prediction-based Fair Excessive Bandwidth Reallocation (PFEBR) in our previous work. The PFEBR proposed an Early-DBA mechanism which improves prediction accuracy by delaying report messages of unstable traffic ONUs and assign estimation credit to predict the traffic arrival during waiting time. However, delaying one report message will increase a guard time in one transmission cycle, how many report messages should be delayed and what is the optimal linear estimation credit are important issues. Both Fuzzy Unstable Degree List Controller (FUDLC) and Fuzzy Credit Estimator (FCE) mechanisms are incorporated to improve the prediction accuracy and enhance the system performance for differentiated services. The FUDLC chooses the second traffic variance and the mean traffic variance of ONUs as input linguistic variables to determine the optimal number of ONUs in the unstable degree list. In addition, the FCE chooses the degree of traffic variance and the degree of waiting time among ONUs as input linguistic variables for the credit estimation, so that the request bandwidth for the next cycle can be predicted more precisely. Simulation results show that the proposed FPDBA algorithm outperforms the efficient bandwidth allocation algorithm (EAA) and DBA with multiple services algorithm (DBAM) in terms of wasted bandwidth, gain ratio of bandwidth, throughput, downlink available bandwidth, average end-to-end delay and average queue length, especial in heavy traffic load.

書名頁 I
論文口試委員審定書 II
授權書 III
中文摘要 IV
英文摘要 V
誌謝 VI
INDEX VII
INDEX OF FIGURES VIII
INDEX OF TABLES IX
1. INTRODUCTION 1
2. RELATED WORK 4
3. PROPOSED FPDBA ALGORITHM 6
3.1 Fuzzy Unstable Degree List Control (FUDLC) 8
3.2 Fuzzy Prediction Scheme based on the Unstable Degree List 11
3.3 Fair Excessive Bandwidth Allocation 14
4. PERFORMANCE EVALUATION 15
A. Wasted bandwidth and Gain ratio of bandwidth 16
B. Throughput 17
C. End-to-end delay 18
D. Downlink data available bandwidth 19
E. Average queue length 20
5. CONCLUSIONS 20
REFERENCES 21

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