- 學位論文
乙太被動式光纖網路之三模式節能機制設計
The design of three mode based power saving mechanisms in Ethernet Passive Optical Network
摘要
本論文探討降低乙太被動式光纖網路(EPON)之能源消耗，目前已有研究指出終端的光網路單元(ONU)在存取網路(Access Network)中所消耗的電力占整體網路上的比重最高。為了減少存取網路的能源使用率，本論文的研究將節能的重點放在位於終端的ONU上，探討ONU配合節能、服務品質與延遲限制下之運作方式。大多數有關ONU節能的研究成果是讓ONU的模式處於Active mode與Sleep mode之間互相作切換，而鮮少有研究將Sleep mode與Doze mode搭配作節能。Doze mode的運作方式為只能接收而無法發送資料，所以在某些情境下，例如使用者瀏覽網頁或觀看線上影片時，皆有機會讓ONU進入Doze mode節能，而不需要維持在Active mode。 本研究將封包分類為高與低兩種優先權，ONU的模式在正常運作下為Active mode，可選擇進入之節能模式分別有Doze mode或Sleep mode。在節能模式下，若ONU無資料收送，將待在Sleep mode；若無上傳資料卻有下傳資料需接收，則留在Doze mode，當ONU處於節能模式時，若有高優先權的上傳資料產生，此ONU會迅速回至Active mode，以減少高優先權的資料延遲時間，滿足這類資料對於延遲時間較嚴格的需求。ONU可在Sleep mode及Doze mode之間互相轉換，以兼顧節能與下載資料效能的需求。我們利用模擬結果比較不同負載度下的節能與效能，並與單向節能轉換機制比較彼此節能與效能的優劣性。
並列摘要
Energy saving techniques, which allow an ONU to reside in the doze or sleep mode, have been proposed for passive optical networks (PONs). In general, if the traffic loading of both downstream and upstream is light, the ONUs should stay in the sleep mode for most of the time. However, if downstream traffic persists while upstream traffic is lightly loaded, the ONUs should reside in the doze mode frequently. This paper proposes a mechanism with full energy transition path, enabling an ONU in any one of the three energy modes to transit to its neighbor mode directly with both forward and backward paths. In addition, this mechanism allows the OLT to be synchronized with ONUs’ energy mode without receiving REPORT message when an ONU transits to a power saving mode. In order to avoid sensitive data being delayed extensively, we classify packets into high and low priorities. While residing in the energy saving mode, the ONU can thus wake up instantaneously if high priority packets arrive. On the other hand, we put an ONU into energy saving mode immediately while the traffic becomes lower. The transition time of waking up from the energy saving mode is ignored in our mechanism. The carried out simulation results have revealed the energy efficiency and frame delay performance with the limited service of IPACT.