在未來5G的環境中，大量且密集部署低功率小基地台已成不可避免的趨勢，可以有效增加頻譜使用率並滿足更多使用者的需求，雖然單一小基地台的運作所需能源遠小於大基地台，但在高密度部署下，大量的小基地台部署能源消耗便十分可觀，對營運商而言是沉重的負擔，且大量的碳排放對環境也不友善，因此國際電信聯盟(International Telecommunication Union, ITU)提出了綠能通訊的概念，希望在高耗電的通訊產業中，能降低製造或運作的碳排放量。
　　在基地台網路環境中，由於傳輸需求會隨著時間及空間變化，即使基地台下使用者稀少仍需維持開啟狀態，造成不必要長期運作消耗。本篇研究所提出方法便是基於第三代合作夥伴計畫(Third Generation Partnership Project, 3GPP)所提出之小基地台開關技術，結合D2D relay，提出CIR (Capacity Improvement Relay) 及CER (Coverage Extension Relay) 演算法，分別透過提升資源使用效率及服務範圍拓展方式增加關閉基地台數量，將低負載基地台內使用者轉移到至鄰近高負載基地台。
　　本研究所提出CER方法在低負載環境時可透過服務範圍拓展關閉45%基地台；中負載時CIR可避免因單純CUE連線模式導致基地台資源提早耗盡無法幫助鄰近基地台狀況，提升鄰近基地台關閉機會，仍維持25%基地台關閉；高負載時即使無法關閉基地台，但因CIR可節省資源，最終滿足總人數仍高於傳統只有CUE方法。

The deployment of small cells seems a promising and inevitable trend to satisfy the increasing traffic demands. In fact, the deployment of dense small cells in hot spot area plays a key role in frequency reuse enhancement in 5G scenarios. Although the energy consumption of a single small cell is much less than a single large-scale base station, the considerable number of non-stop small cells will still cause huge energy consumption. The OPEX (Operation Expenditure) is a heavy burden for operators. And the carbon footprint is not eco-friendly. Thus, ITU (International Telecommunication Union) proposed the concept of green communication. The main purpose is to reduce the energy consumption in both manufacturing and operating of the huge energy required telecommunication industry.
In traditional cellular network environments, the traffic demands have the characteristics of spatial and temporal fluctuations since users will move separately or get together. In light load scenarios, all the BSs (Base Station) require staying active and will lead to unnecessary energy consumption. Different from previous studies, this thesis is based on the small cell switching on/off mechanism proposed by 3GPP (Third Generation Partnership Project) combining relay techniques. This thesis proposed CIR (Capacity Improvement Relay) and CER (Coverage Extension Relay) algorithm to increase the opportunity for BSs to switch off. CIR aims to enhance the RBs efficiency to reserve more RBs for offloading neighbor cell’s load. CER aims to extend service coverage and assemble loads from neighbor cells.
In light load environments, about 45% of BSs can be turned off through CER. In medium load, the inefficient allocation with only cellular mode will deplete RBs in BSs faster. With CIR, more remaining RBs provides more space to grab users from light load neighbor BSs. The final switched off BSs ratio remains at 25%. In high load, even if no BSs can be turned off, the final user satisfied ratio is higher than purely CUE mode because of allocating RBS efficiently with CIR.

學位論文審定書 i
論文摘要 ii
Abstract iii
目錄 v
圖目錄 vii
表目錄 ix
第一章 導論 1
1.1 前言 1
1.2 研究動機 3
1.3 論文架構 4
第二章 相關背景與研究 5
2.1 頻譜使用現況 5
2.1.1 新頻譜應用情境 5
2.1.2 增加頻譜使用率情境 7
2.2 密集式小基地台網路 8
2.3 D2D 技術簡介 10
2.3.1 D2D直接通訊介紹 10
2.3.2 D2D Relay介紹 11
2.3.3 D2D 裝置搜尋 13
2.3.4 D2D Relay to Network裝置搜尋 14
2.3.5 D2D 資源配置 15
2.4 基地台開關技術 16
2.5 相關研究 18
第三章 提出方法 21
3.1 系統架構 21
3.1.1 環境架構 21
3.1.2 基地台能源架構 23
3.2 問題描述 25
3.3 系統流程與演算法 31
3.3.1 節省能源演算法 31
3.3.2 CIR演算法 36
3.3.3 CER演算法 40
3.3.4 時間複雜度分析 44
第四章 效能與分析 45
4.1 模擬環境與參數設定 45
4.2 模擬結果與效能分析 47
第五章 結論 64
參考文獻 65

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