臺灣博碩士論文加值系統

摘 要
VDSL是屬於數位用戶線(DSL)技術領域之中最新且最先進之成員。VDSL既可用於對稱式亦可用於非對稱式通訊服務，例如：高速網際網路連線、數位視訊廣播、互動式影像通訊、區域網路相互介接、在家上班及高品質視訊會議之用。
電信業者既設之銅質雙絞線網路，於架構如此高速傳輸技術時，將面臨巨大之挑戰。電信業者可藉著運用VDSL科技發揮銅質雙絞線之潛力，更具競爭力地介入寬頻通訊服務。可是，要在既設的網路上實現數十兆位元傳輸容量，重要關鍵完全在於是否具有一合適的雙絞線接取網路。
橋接線是未終接的無遮蔽雙絞線插接於配分電纜的雙絞線上。橋接線的主要影響是會在被插接的迴路上，耗損迴路轉換函數的功率。
橋接線長度從10公尺至40公尺，在美規26號線徑(公制約0.4mm)之VDSL迴路上，其功率沈降可高達25dB。
電信業者提供客戶VDSL服務時，由於客戶散居各處，所以從客戶住處傳送訊號至電信機房的長度，距離遠近會明顯不相等，長距迴路的上行微弱訊號會被相隣較短距離迴路之強烈上行訊號遮蔽，這種特殊的拓樸會因此產生上行通道容量下降之困擾。
當電信業者在引進VDSL技術，構建超高速數位用戶線網路時，應將此種干擾現象列為最重要的技術評價項目之一。
以台灣目前既設銅質心線0.4mm線徑之接取網路，考量提供使用者充分之多媒體整合通道(含三路MPEG-II視訊頻道、一路高速上網通道及語音電話通道)之需求，則VDSL最適當之提供服務範圍是距離ONU半徑1公里。

Abstract

VDSL is the latest and most advanced member in the family of DSL technologies. Both symmetrical and asymmetrical services can be supported. Examples are fast Internet access for users and content providers, digital video broadcasting, interactive video, LAN interconnection, teleworking and high quality videoconferencing.
The Telco installed copper pair network presents a challenging environment for such high-speed transmission. Telco can leverage this asset to release the potential for competitive broadband services using VDSL technology. However, realization of the megabit capacity of the existing network is critically dependent on the suitable twisted pair access network.
A bridged tap is an unterminated section of UTP wiring connected in shunt to a twisted pair of a distribution cable. The primary effect of a bridged tap is the introduction of “nulls” in the transfer function of the loop to which the bridged tap is attached. Bridged tap lengths range from 10m to 40m on the 26-gauge 300m VDSL loops. The notches could be as deep as 25dB.
Typically, one central node will serve a base of VDSL customers and the loops that carry VDSL signals to the customers could differ significantly in length. This particular topology will raise problems for upstream capacity on the longest loops since the useful signal on these loops could be completely drowned by the strong FEXT coming from the shorter lines. Telco should take it seriously and let it be one of the most important evaluation items when deploying VDSL system.
For providing multimedia services, including 3-channels of MPEG II video, high-speed Internet access, and POTS simultaneously over single pair of 0.4mm-gauge copper wire in Taiwan, 1000-meter VDSL servicing area is the best choice.

目錄
中文摘要 --------------------------------------------------------------- i
英文摘要 -------------------------------------------------------------- ii
誌謝 ------------------------------------------------------------- iii
目錄 -------------------------------------------------------------- iv
表目錄 --------------------------------------------------------------- ix
圖目錄 --------------------------------------------------------------- x
第一章DSL回顧及展望-------------------------------------------------------- 1
1.1 數位通訊緣由--------------------------------------------------------- 1
1.2 數位資料經由類比音頻通道傳送----------------------------------------- 2
1.3 DSL系統發展環境------------------------------------------------------ 3
1.4 DSL送收器一般架構---------------------------------------------------- 4
1.5 DSL系統與標準-------------------------------------------------------- 5
1.5.1 早期DSL系統標準：IDSL------------------------------------------------ 6
1.5.2 HDSL系統標準--------------------------------------------------------- 6
1.5.3 ADSL系統標準--------------------------------------------------------- 7
1.6 xDSL展望------------------------------------------------------------- 7

第二章 DSL基本原理-------------------------------------------------------- 10
2.1 電話用戶迴路環境---------------------------------------------------- 10
2.1.1 電信機房及用戶建築物------------------------------------------------ 10
2.1.2 用戶迴路架構及雙絞線電纜-------------------------------------------- 11
2.1.3 橋接(Bridged Taps)-------------------------------------------------- 13
2.1.4 雙絞線迴路之構成---------------------------------------------------- 13
2.1.5 語音通道特性-------------------------------------------------------- 14
2.2 雙絞線通道模式(Twisted-Pair Channel Modeling)----------------------- 14
2.2.1 雙絞線電纜主要及次要參數-------------------------------------------- 15
2.2.2 雙埠網路及ABCD參數-------------------------------------------------- 16
2.2.3 串聯雙埠網路-------------------------------------------------------- 18
2.2.4 電話線的通道轉換函數------------------------------------------------ 19
2.3 送收訊器前端雜訊模式------------------------------------------------ 21
2.3.1 串音雜訊------------------------------------------------------------ 22
2.4 通道容量------------------------------------------------------------ 27
2.4.1 訊號/雜音比--------------------------------------------------------- 29
2.4.2 通道容量計算-------------------------------------------------------- 31
2.4.3 實際受限的通道容量-------------------------------------------------- 34
2.5 數位用戶線(DSL)基本架構--------------------------------------------- 35
2.5.1 IDSL技術------------------------------------------------------------ 35
2.5.2 HDSL技術------------------------------------------------------------ 37
2.5.3 ADSL技術------------------------------------------------------------ 40

第三章 VDSL技術----------------------------------------------------------- 42
3.1 VDSL頻譜計畫-------------------------------------------------------- 43
3.2 VDSL調變技術-------------------------------------------------------- 46
3.2.1 單載波調變技術(SCM)------------------------------------------------- 47
3.2.2 多載波調變技術(DMT)------------------------------------------------- 49
3.3 VDSL頻譜配置技術---------------------------------------------------- 52
3.3.1 VDSL頻譜配置要點---------------------------------------------------- 53
3.3.2 DSL共置問題--------------------------------------------------------- 53
3.3.3 DSL併存問題--------------------------------------------------------- 55
3.3.4 上行訊號發送功率管控------------------------------------------------ 57
3.3.5 無線電波感應及外洩-------------------------------------------------- 59
3.3.6 頻譜管理法令-------------------------------------------------------- 61
3.4 VDSL建置技術-------------------------------------------------------- 61
3.4.1 VDSL傳輸距離限制---------------------------------------------------- 63
3.4.2 從電信機房提供VDSL服務---------------------------------------------- 64
3.4.3 從屋外機箱提供VDSL服務---------------------------------------------- 65
3.4.4 從大樓電信室提供VDSL服務-------------------------------------------- 67
3.4.5 ONU(DSLAM)需求------------------------------------------------------ 68
3.4.6 ILEC/CLEC建置VDSL之優劣勢------------------------------------------- 73

第四章　迴路特性模擬------------------------------------------------------ 76
4.1 迴路橋接之影響------------------------------------------------------ 76
4.2 上行功率管控-------------------------------------------------------- 85
4.3 DSL通道容量及傳輸距離----------------------------------------------- 90

第五章　模擬結果討論------------------------------------------------------ 91
5.1 xDSL橋接線影響之比較------------------------------------------------ 91
5.2 xDSL上行功率管控比較------------------------------------------------ 92
5.3 VDSL傳輸相對較佳範圍------------------------------------------------ 93

第六章 結論--------------------------------------------------------------- 95

參考文獻 --------------------------------------------------------------- 96
附錄A 美規#24線徑(公制:約0.5mm)RLGC值------------------------------------ 98
附錄B 美規#26線徑(公制:約0.4mm)RLGC值------------------------------------ 99
附錄C VDSL TEST LOOPS--------------------------------------------------- 100

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