A Hybrid Broadband Access Network Architecture Designed for Power Saving

隨著近年來全球環保意識的高漲，以及國內節能減碳的呼聲漸高，電資通訊領域的耗電量逐漸受到重視。而不單是因為環保議題，電信業者為了減少電費支出，藉此確保盈餘，亦無不致力於降低其整體網路耗電。 目前在研究中常見的省電策略有兩種，其一是改善個別元件抑或裝置的耗電，其二則是將不使用的設備關閉。通常認為，占耗電大宗的接取網路因為其布建架構為樹枝狀，只能靠前者而非後者來省電。然而本論文認為，藉由在架構中加入可導引流量之新裝置，使的有線接取網路的流量能在離峰時段改送往24小時開啟之無線接取網路基地台，有線接取網路的設備即可被關閉，同時亦不影響使用者連網。 為了驗證上述方法之可行性，本論文採用數篇學術文獻以及台大ADSL記錄檔來產生合理的使用者流量模型，並提出數個與本架構相應之直觀演算法，最後使用電腦程式模擬驗證。模擬的結果顯示，在通常情況底下有高達四成的時間可將有線接取網路關閉，即使在較為極端的環境之中亦有二成的時間如此，且整體節能可達13%。足以證明本架構在未來有十足的潛力可以實行。In recent years, environmental concerns have caught general public’s attentions globally. The Carbon emission of the ICT industry also becomes a well-known issue gradually, not only because of its environmental impact but also due to the growth of operation cost coming from electricity consumptions. There are two kinds of common strategies for power saving in telecommunication networks, one is reducing energy consumption of individual devices; the other is switching off idle network elements. It is well known that broadband access networks fall into the former category rather than the latter because of its tree topology. However, by introducing a new device, such as personal switch router, into the architecture in user-end, one can re-direct the traffic flows from the wired access network to the wireless access network, when the latter is a more power effective solution. In our study, we discover that we can even switch off wired access network during low-traffic periods, if the wireless access network is required to be always active. In order to prove the feasibility of the initiative, in this thesis we adopt models from various academic papers and the log files of NTU ADSL to create a reasonable user profile, and then we propose several heuristic algorithms to support its power saving operations. Finally, we examine the effectiveness of this power-saving approach from the new hybrid architecture via computer simulation. Based on user’s activity of NTU ADSL access networks, the simulation results reveal that the wired access network can be turned off up to 40% of time in normal circumstances and 20% in some extreme conditions, and the total power-saving can be up to 13%. In sum, the brand new architecture we proposed in this thesis should be a promising solution for future hybrid access networks