臺灣博碩士論文加值系統

下世代行動通訊系統(International Mobile Telecommunication Advanced；IMT-Advanced)或第四代(4G；4th Generation)行動通訊系統為國際電信聯盟(ITU)制定，目標為接續現有第三代(3G；3rd Generation)行動通訊系統、無線區域網路、與寬頻固接等系統。ITU對於IMT-Advanced行動系統要求為，在高速移動下最高傳輸速率須達100 Mbit/s，在低速移動或靜止時最高傳輸速率可以高達1 Gbit/s。IEEE 802.16m與LTE-Advanced皆致力於發展下世代行動通訊系統，在新標準中也制定了融合極微小基地台的新無線網路技術，除了改善室內無線傳輸訊號嚴重衰減的問題，也可增加系統的涵蓋範圍，是目前網路服務提供業者廣泛討論的技術。

本論文將探討在兩種不同頻率配置的WiMAX網路環境中，佈建開放式極微小基地台其功率設定對於系統效能改善與傳輸訊號品質的變化。經研究，當功率層級愈高訊號強度愈強，極微小基地台連線比例、系統平均SINR與Throughput皆有所提升。雖然各基地台訊號強度提升，但牆壁的效應使得干擾大幅衰減，室內用戶訊號品質因此得到保障；透過Femtocell依Macrocell距離做功率設定(Location-Dependent Power Setting；LDPS)的設計，多數的極微小基地台只需使用低功率即可維持室內涵蓋範圍，而室內用戶一定可以與極微小基地台連線的設計方式，可保障室內用戶傳輸品質並減輕大基地台負擔。進一步地，在射頻電路功率上下限範圍內使用不同功率設定策略，使得細胞中心的極微小基地台能有效降低對週遭用戶的干擾，且細胞邊緣用戶也可藉著連線至開放式的極微小基地台改善訊號品質。

International Mobile Telecommunication Advanced (IMT-Advanced) cellular system is defined by International Telecommunication Union (ITU). According to the ITU requirements, an IMT-Advanced cellular system must have target peak data rates up to 100 Mbit/s for high mobility such as mobile access and up to 1 Gbit/s for low mobility such as nomadic/local wireless access. IEEE 802.16m and 3GPP LTE-Advanced are two candidates of IMT-Advanced technology and both of them incorporate Femtocell Base Station into their next generation mobile network standards. Femtocell Base Station is a low power and low cost small base station in the customer premise. It connects to the core network via cable, DSL or similar backhaul technology. The aim of Femtocell is to improve indoor coverage, enhance system capacity and provide relief to Macrocell’s loading.

In the thesis, we consider a WiMAX network deploying both Macrocells and Open Subscriber Group (OSG) Femtocells. Fisrt, the simulation results show that we can improve average SINR and average throughput by increasing the power level of OSG Femtocells within Macrocells. Second, we introduce a Femtocell Location-Dependent Power Setting (LDPS) scheme to improve indoor signal quality and reduced the power consumption of Femtocell Base Station. By adopting this power setting scheme, Femtocells away from the Macrocell Base Station only need low power setting to maintain indoor coverage, and the scheme also reduces the interference to surrounding users at the same time. Third, we fine-tune the power setting of LDPS scheme. The interference could be lowered by setting LDPS-Upper Bound at 23.2dBm for Femtocells near the cell center, and it won’t decrease the ratio of users connecting to Femtocells. And when we increase cell edge Femtocells’ LDPS-Lower Bound, cell edge users can get better signal quality from Femtocells.

摘要 i
Abstract ii
圖目錄 v
表目錄 vii
第一章 緒論 1
1.1 前言 1
1.2 研究動機與目的 1
1.3 論文章節介紹 3
第二章 背景介紹 4
2.1 下世代行動通訊系統技術 4
2.1.1 下世代行動通訊系統簡介 4
2.1.2 下世代行動通訊系統研究議題與挑戰 5
2.2 正交分頻多工存取技術 6
2.2.1 OFDM與OFDMA技術 7
2.2.2 WiMAX訊框架構 8
2.3 極微小基地台(Femtocell Base Station)技術簡介 9
2.3.1 極微小基地台的定義 9
2.3.2 佈建極微小基地台的優點 10
2.4 極微小基地台技術挑戰 12
2.4.1 Macrocell與Femtocell的同步 12
2.4.2 Macrocell 與Femtocell間頻率配置 13
2.4.3 OSG Femtocell與CSG Femtocell 14
2.4.4 自我參數設定與最佳化 15
2.4.5 功率大小的調整 15
第三章 探討議題：極微小基地台功率設定 17
第四章 模擬環境之設定 19
4.1 環境架構 19
4.2 模擬環境之Macrocell與Femtocell架構 20
4.3 環境參數設定 22
4.3.1 模擬參數設定 22
4.3.2 極微小基地台固定功率設定 23
4.3.3 極微小基地台佈建密度 24
4.4 路徑衰減模型 24
4.5 頻譜資源分配與干擾情境 28
4.5.1 頻譜配置(1, 3, 3) 29
4.5.2 頻譜配置(1, 3, 1) 31
4.6 訊號品質與系統效能評估方式 32
4.6.1 訊號與干擾雜訊比(Signal to Interference plus Noise Ratio) 32
4.6.2 系統傳輸量(Throughput) 34
第五章 模擬結果與數據分析 36
5.1 Fixed Power Setting (FPS) Femtocell基地台對系統的影響 37
5.1.1 佈建FPS之Femtocell基地台於(1, 3, 3)系統 37
5.1.2 佈建FPS之Femtocell基地台於(1, 3, 1)系統 42
5.1.3 Femtocell基地台於不同頻譜配置下的比較 47
5.2 不同功率層級(Power Level)設定對系統的利弊 49
5.2.1 功率層級改變對(1, 3, 3)系統的影響 49
5.2.2 功率層級改變對(1, 3, 1)系統的影響 54
5.3 Location-Dependent Power Setting (LDPS) Femtoell基地台設計與系統效能分析 58
5.3.1 LDPS的設計 58
5.3.2 佈建具LDPS之Femtocell基地台於(1, 3, 3)系統 62
5.3.3 比較不同功率設定方式對(1, 3, 3)系統的影響 64
5.3.4 佈建具LDPS之Femtocell基地台於(1, 3, 1)系統 67
5.3.5 比較不同功率設定機制方式對(1, 3, 1)系統的影響 69
5.4 不同功率設定策略對系統效能分析 72
5.4.1 LDPS Femtocell基地台功率設定策略於(1, 3, 3)系統 72
5.4.2 LDPS Femtocell基地台功率設定策略於(1, 3, 1)系統 78
5.4.3 LDPS Femtocell基地台系統效能與功率消耗 82
第六章 結論與未來展望 86

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