節能無線數據網路之基地台設計

Abstract

隨著環境議題的抬頭，以節能省電為導向的設計遂變成一股趨勢。根據研究顯示，資訊及通訊科技產業(Information and Communication Technology, ICT)的碳排放占全球總量的2~4%，且持續增加中。更進一步指出，蜂巢式網路(Cellular Network)所消耗之能量佔ICT 產業的十分之一。因此，許多研究計畫著重在發展具降低能量消耗之技術，即綠色通訊(Green Communications)。這對許多營運業者除了是一種維持生態永續發展的責任外，也在成本控管上具有經濟效益，是許多廠商投入的方向。

而在蜂巢式網路中，維持基地台運作所消耗的能量更超過整體的80% 。於是，如 何在細胞佈建時最佳化基地台的個數、降低能量消耗，是我們想討論的議題。在本篇論文中，我們探討不同的流量負載(Traffic Load)下，細胞的涵蓋範圍應如何設計，以提高在頻寬及能量上使用的效率。根據討論的結果，我們可以依不同使用情形，得到最佳的細胞半徑，並發現維持細胞邊界上使用者之服務品質，為決定細胞涵蓋範圍的主要因素。最後，我們也提出一對系統負荷小、低複雜度的節能運作方式，在具節能潛力的時段可減少75%的功率使用，進而幫助整體網路節省約15.6%的能量消耗。

With the rise in environmental issues, energy saving-oriented design becomes a trend. According to the current study, 2~4% of worldwide carbon emissions are caused by ICT (Information and Communication Technology) industry and is constantly increasing. It further pointed out that the energy consumption of cellular networks is one-tenth of the amount of ICT infrastructures. Therefore, many projects focus on developing new techniques that reducing energy consumption, that is, green communications. In addition to a responsibility for preserving the environment, it is also with economic benefits in cost control and thus dedicated by many service providers and manufactures

In the cellular network, over 80% energy consumption is used to maintain the operation of base stations. Hence, that is what we want to discuss in cell design for optimizing the number of base stations and reducing the energy consumption. In this thesis, we discuss how to choose the cell radius under different traffic profile in order to enhance the efficiency in the use of bandwidth and energy. According to the results, we can decide the optimal cell radius base on different situations. Moreover, we find that to determine the cell coverage, the QoS requirement of cell-edge users is the main factor. In the end, we propose a less-overhead and low-complexity operation mode to reduce the power consumption for 75% during time period with power-saving potentiality and save for up to 15.6% of daily energy consumption.