為了確保接取網路中的能源效率以及保證Voice over IP (VoIP)、Video on Demand (VoD)、即時以及非即時互動等各種不同需求的網路服務品質，在接取網路中，乙太被動光接取網路(Ethernet passive optical network, EPON) 被視為解決能源節約以及保證服務品質的重要議題。許多文獻提出睡眠模式排程機制並考慮每個ONU單一服務類別的平均延遲限制，但是在網路上存在多種服務的情況下，考慮延遲限制較嚴謹的類別會造成節能效果較差，考慮延遲限制較寬鬆的類別會造成延遲限制較嚴謹的類別違反其延遲限制。Green bandwidth allocation (GBA)的作者提出一個新的分析模型，根據最嚴謹的延遲限制類別來決定每個周期ONU最佳的睡眠時間，來得到最佳的節能效果。
雖然GBA機制可以確保不同類別的延遲限制不違反最嚴謹的延遲限制，但是延遲限制較鬆散的封包也會被當成延遲限制較嚴謹的封包，一起做上傳，造成ONU持續在active mode浪費能源來提早上傳這些延遲限制鬆散的封包，因此，本文提出一個新的intra-ONU scheduling機制控制封包在不同延遲限制類別下依照各類別的延遲限制做傳送來加強GBA。接著，為了保證在不同類別封包有自己的延遲限制下，也能符合自己封包延遲限制內上傳，我們在Enhanced GBA機制下透過加強Classifier機制控制封包的延遲，除此之外，我們將Enhanced GBA based on Enhanced Classifier中ONU加入架構切換機制，讓ONU可以根據睡眠長度決定切換架構以達到最佳的能源節約。模擬結果顯示Enhanced GBA 可以讓ONU在不同測試組合中，封包皆維持各類別的延遲限制且能源消耗比GBA少，且Enhanced GBA中加入ONU切換架構機制能達到最佳的能源節約。

In order to ensure the energy efficiency of each optical network unit (ONU) in an access network and guarantee quality of service (QoS) requirements of differentiated services such as Voice over IP (VoIP), Video on Demand (VoD), real-time, near real-time transactions and data traffic, the Ethernet Passive Optical Network (EPON) is considered the solution. Many studies have proposed sleep mechanisms that concern a single class delay constraint. While there exist multiple classes of service on a network transmission, saving energy under different classes considered causes the problem that with the stringent delay constraint classes considered causes the less energy saving, and stringent class will violate their delay constraint while considered with the relaxed delay constraint classes. The authors of Green Bandwidth Allocation (GBA) proposed a new analytical model to determine the optimal sleep time of ONUs in every cycle without violating the maximum class delay constraint.
Although the GBA mechanism guarantees that the different class delay constraints do not violated the maximum class delay constraint, packets with a more relaxed delay constraint will be treated as the most stringent delay constraint and may be sent early. This means that the ONU will waste time in active mode to send packets which did not need to be sent at the current time. Accordingly, we proposed a novel model in intra-ONU scheduling to control the packets under different delay constraints, thereby enhancing GBA performance. Moreover, packets in the same classes may have different packet delay constraints. We improve the classifier on Enhanced GBA to classify packets according to their packet delay constraint. Further, we use the new ONU architecture in which the ONU can switch the architecture according to the sleep time length, thus improving energy saving in the Enhanced GBA based on Enhanced Classifier. The simulation results show that the Enhanced GBA and Enhanced GBA based on Enhanced Classifier ensure that different class packets do not violate their delay constraint and consume less energy than GBA in different cases. The Enhanced GBA based on Enhanced Classifier can be used in traffic where the delay constraint is not according to classes. Instead, packets in same class also have different packet delay constraints.

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