在被動乙太光纖網路中，上傳頻寬分配採取時間分多工的方式。但由於每個ONU彼此間無法知道上傳頻寬的起始時間點與可上傳頻寬的大小，可能造成有彼此衝突的問題，再加入上傳頻寬使用率、封包延遲時間以及服務品質等各種考量，使得設計一個有效率且符合服務品質的頻寬分配演算法是非常的重要。
OLT與ONU之間是利用多點控制傳輸協定彼此溝通。在此我們所考慮的是使用inter-scheduling以及intra-scheduling分別管理頻寬分配的系統架構，由各個ONU分別傳送REPORT訊息給OLT，然後由OLT依照收到的REPORT訊息透過inter-scheduling的演算法計算，再依照計算出的傳輸時間點發送GATE訊息，分配各個ONU所能開始上傳資料的時間點與上傳頻寬的大小。而ONU以往則是透過intra-scheduling決定內部每個不同優先權的佇列傳輸的先後順序及傳輸資料的長度。這種只能被動地等待inter-scheduling計算分配頻寬後才執行的intra-scheduling，我們稱之為被動式的intra-scheduling。
而本篇論文主要是著眼在intra-scheduling的設計，本篇論文設計了一個名為主動式intra-scheduling，利用原先REPORT訊息中的保留欄位加以多筆記錄，而記錄欄位的方式則關係到服務品質，在此我們是採取設定門檻值的方式來達成對不同優先權佇列的服務。如此一來使得OLT收到一個REPORT能得知此ONU多個不同的需求頻寬，在經過 inter-scheduling的計算與分配後，OLT會將計算與分配出來的值與原先收到的REPORT訊息作一比對做出最適合的分配。由於最後ONU所得到的上傳頻寬分配，是根據原先送出的REPORT，所以我們稱之為主動式的intra-scheduling。
使用主動式的intra-scheduling，除了必定保證服務品質及各優先權資料封包延遲的合理性外，也可以避免產生未使用溝槽剩餘頻寬(Unused Slotted Remainder)。由於乙太網路封包的不可分割性，使得ONU所分配到的上傳頻寬大小並不一定能被佇列傳輸的資料封包所充分使用，才會導致產生0～1518個bytes大小的未使用溝槽剩餘頻寬。主動式的intra-scheduling事先把欲傳輸的封包大小記錄在REPORT中，而ONU在收到GATE訊息後會根據當時傳送的REPORT，依照佇列的優先權高低上傳資料封包。如此一來，ONU所分配到的上傳頻寬大小一定能被佇列傳輸的資料封包所充分使用，可完全消除未使用溝槽剩餘頻寬。
我們使用相關論文中的演算法作為inter-scheduling，稍加修改使之能與主動式intra-scheduling做結合使用，提高上傳頻寬使用率、達到良好的服務品質以及合理的封包延遲。
最後，我們會使用自我相似(self-similar)網路流量模擬整個網路情形，分別針對本篇所提出的方法、調整不同門檻值後的結果做出模擬比較。並與其他分散式管裡的系統架構分別比較在網路負載大小平均、網路負載大小不平均時的上傳頻寬使用率，與封包延遲、未使用溝槽剩餘頻寬。我們將以這些數據結果來驗證我們所提出方法的優勢所在。

Time-division multiple access scheme on a single wavelength is more attactive for upstream traffic in EPON. Each ONU doesn’t know start time of upstream bandwidth and granted window size each other, and it may cause conflicts. Considering upstream bandwidth utilization, packet delay and Quality-of-Service(QoS), it is very important to design an efficient bandwidth allocation algorithm conforming to requirement of QoS.
OLT and ONU communicate with each other by MPCP. We use inter-scheduling and intra-scheduling algorithms to manage bandwidth allocation for inter-ONU and intra-ONU, respectively. Each ONU sends REPORT message to OLT in their transmission window, and OLT executes inter-scheduling algorithm to calculate transmission window for receiving REPORT message from all ONUs.OLT sends a GATE message which contains start time and size of transmission window to each ONU. ONU used to decide the transmission order of queue data and the transmission size of queue data by executing intra-scheduling, we call it passive intra-scheduling.
The thesis focus on design of intra-scheduling algorithm, and we propose an active intra-scheduling algorithm. The general idea of active intra-scheduling algorithm is recording several queue sets in the reservation fields in REPORT message. We set thresholds for different classes to satisfy requirements of QoS. Therefore, OLT gets several sets of bandwidth requirement for receiving a REPORT message from one ONU. According to the bandwidth computed from inter-scheduling algorithm, OLT determines a appropriate allocation from queue sets in REPORT message. ONU gets granted window size based on REPORT which are send by ONU in previous cycle, so we call it active intra-scheduling algorithm.
Using active intra-scheduling also eliminate unused slotted remainder (USR), besides satisfying requirement of QoS and reasonable packet delay for different class. ONU can’t completely make use of upstream bandwidth which are given by OLT because ethernet packet is not divided, and it will cause USR which is from 0 to 1517bytes.
ONUs contrast granted window size in GATE message with REPORT which was sent to OLT, and it will find a queue set in which sum of queue report equal to granted window size. ONUs transmit packet according to the queue set which is found by contrasting in priority order. For this reason, ONU can completely eliminate USR.
We use the inter-scheduling which is mentioned in other reference and combine it with active intra-scheduling for enhancing throughput, satifying requirement of QoS, and reasonable packet delay.
Finally, we compare the proposed scheme with EAF scheduling in our simulation results. We simulate USR, throughput, packet delay for uniform and non-uniform load to prove our scheme better.

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