臺灣博碩士論文加值系統

混合光纖同軸網路（HFC）網路面臨重要且深具挑戰的問題，在於必須能夠提供QoS保證。而影響HFC網路品質保證的層面，其最主要關鍵來自於媒體存取控制（MAC）和上行通道的排程演算法。也由於較長的來回傳遞延遲、不確定性要求存取延遲以及傳送端對資源的預約均不具備時間資訊，以至於頭端的上行通道排程器也就無法知悉資料封包實際到達站台的到達時間。由此而知，在相同的資料流量輸入下，HFC網路的資料封包傳送順序，將不同於傳統交換機網路。因於此，本論文將提出一個新的媒體存取控制協定，稱之為時戳式通用競爭求解演算法（TG－CRA），使得資料封包到達的時間資料，也能主動地提供給頭端的上行通道排程器。另一方面，為了減少過多的時間資訊，利用線性位移法，重新計算新到達的資料封包所到達的時間資訊，據此成為各個要求封包所要搭載的時戳資料。相較於原始的通用競爭求解演算法，模擬的結果顯示，時戳式通用競爭求解演算法在減少不確定性的要求延遲和資料封包存取延遲上，表現出較優異效果。同樣地，在資料封包存取延遲上，也能減少延遲的變異，使得時戳式通用演算法能提供更佳的平均延遲抖動（Delay Jitter）。

Providing QoS guarantees in Hybrid Fiber Coaxial (HFC) networks is a very important and challenging problem. Medium Access Control (MAC) protocol and upstream channel scheduling algorithm are two key mechanisms that will affect the degree of QoS guarantees of HFC networks. Due to the long round-trip propagation delay, uncertain request access delay, and resource reservation without time information, the upstream channel scheduler in the headend cannot obtain the real cell arrival time at the stations. Thus, with the same input traffic, the cell transmission order in HFC networks would be different to the order in traditional switching networks. Therefore, this thesis proposes a new MAC protocol, called Time-stamp General-Contention Resolution Algorithm (TG-CRA), to provide the cell arrival time information to the upstream scheduler in the headend. In order to reduce the overhead of the time information, a linear offset scheme is used to stamp the arrival time information of new arrival cells on the request. Compare to the G-CRA algorithm, simulation result shows that the TG-CRA algorithm can yield better performance in reducing the uncertain request delay and cell access delay. The variance of cell access delay is also reduced, thus the TG-CRA algorithm can provide better mean delay jitter.

誌謝 I
摘要 II
目錄 IV
圖目錄 VI
表目錄 VIII
第一章　導論 1
1.1　研究動機與目的 1
1.3　論文方法和貢獻 3
第二章　HFC網路文獻探討 4
2.1　IEEE 802.14標準 4
2.2　HFC網路架構 5
2.3　MAC層的運作 7
2.3.1　Sea of Minislots 8
2.3.2　預約存取模式（Reservation Access Mode） 9
第三章　時戳式ＨＦＣ網路 19
3.1　時戳的加入 19
3.2　線性位移頁框 20
3.4　修改通用競爭演算法 23
3.4.1 時戳式通用競爭演算法 23
第四章　實驗結果 26
4.1　實驗平台 26
4.2　實驗架構 26
4.2　實驗參數 28
4.3　FIFO排程結果比較 29
4.3.1　Burst對系統的影響 29
4.3.2　RMS量對系統的影響 32
4.3.3　時戳對系統的影響 35
4.4　Virtual Clock排程結果比較 42
4.4.1　時戳對系統的影響 43
第五章　總結 48
參考文獻 49

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