模糊控制相容碼率與低密度同位元檢查碼應用於區域多點分配服務系統

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研究生：	沈經緯 Ching-wei Shen
論文名稱：	模糊控制相容碼率與低密度同位元檢查碼應用於區域多點分配服務系統 Fuzzy-Based Rate Compatible LDPC code for LMDS systems.
指導教授：	蔡木金 Mu-king Tsai
口試委員:
學位類別：	碩士 Master
系所名稱：	資訊電機學院 - 通訊工程學系在職專班 Executive Master of Communication Engineering
畢業學年度：	96
語文別：	英文
論文頁數：	81
中文關鍵詞：	區域多點分配服務系統
外文關鍵詞：	LMDS
相關次數：	點閱：21 下載：0
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在各項微波傳輸技術中，LMDS 可以說是最受到注目的，它是雙向數位蜂巣式通訊系統，因為它可以提供雙向的語音、影像及數據傳輸的寬頻整合服務。LMDS能夠滿足各類型的用戶分佈與應用，從住家到商業用途均能提供服務，因此更具有彈性及擴充性。但是，在LMDS系統中雨衰及細胞內干擾是影響服務品質之重要因素。因此為了減少LMDS系統中因為雨衰和細胞內干擾的問題，造成頻寬不必要的浪費。我們提出新的想法，利用LMDS系統分析的結果，建立模糊控制的歸屬函數與規則，來判斷通道品質的好壞來，決定碼率的使用，運用錯誤更正碼之LDPC碼改進LMDS系統的效能。根據系統的干擾環境影響下，減少冗餘碼的使用增加頻寬，來決定調整碼率，
在不損失誤碼率下，提升頻寬效益。

In every microwave transmission technology, LMDS can be said and receive the note purpose most. LMDS system is a two-way digital cellular system operating at 20-50 GHz. It offers the multiple services of the audio, video, multimedia and data transmission and can meet all kinds of
users'' demands. However, it is to influence the important factor in LMDS system which is rain attenuation and inter-cell interference (ICI).
Therefore, LMDS is affected the interference problem by rain attenuation and inter-cell interference (ICI). Avoiding the band-width unnecessary waste, we proposed new idea that is the fuzzy-based rate compatible LDPC code for LMDS system. It utilized fuzzy control and according to the LMDS system channel quality to determine the code ate. We simulated the LMDS system interference factors such as rain attenuation, Cross-Polarization Discrimination (XPD) and beam-width. Those factors will be influence the LMDS system performance.
The fuzzy membership function and fuzzy rule was defined by LMDS simulation results. And we implement the LDPC code of error correction coding to increasing the system performance and reduce the redundancy bit. Base on LMDS system does not loss Bit-Error-Rate and got the good spectrum efficiency.

摘要....................................................i
Abstracts	...............................................ii
誌謝....................................................iii
List of Figures.........................................vi
List of Tables..........................................vii
Chapter 1 Introduction...................................1
1-1. Local Multipoint Distribution Service (LMDS)........1
1-1-1. Introduction of LMDS..............................1
1-1-2. FCC Band Plan for LMDS............................6
1-2. Motivation..........................................9
1-3. Structure of thesis.................................10
Chapter 2 Background of LMDS.............................11
2-1. Characteristics of Propagation Channel..............11
2-1-1. Propagation in Free Space.........................11
2-1-2. Propagation Loss..................................12
2-2. Inter-Cell interference calculation.................12
2-2-1.The well-know radio formula........................12
2-2-2. ITU-R Rain Attenuation Prediction Model...........13
2-2-3. Cross-Polarization Discrimination (XPD)...........17
2-2-4. Path loss exponent (α)............................17
2-3. Layout of Cellular Configuration....................18
2-3-1. System Deployment Trade-offs......................18
2-3-2. Frequency Reuse...................................19
2-3-3. Alternating Polarizations.........................20
2-3-4. Cell Planning of LMDS.............................21
2-4. Link Budget Calculation.............................22
2-5. Typical architecture................................23
2-5-1. Co-channel interference...........................24
Chapter 3  Fuzzy control system..........................29
3-1. Fuzzy Introduction..................................29
3-2. Fuzzy Controllers...................................29
3-3. Logical Inference...................................31
3-4. Fuzzy Sets..........................................32
3-4-1. Fuzzification.....................................33
3-4-2. Defuzzification...................................35
Chapter 4 LDPC codes.....................................37
4-1. Introduction........................................37
4-1-1. Representations for LDPC codes....................37
4-1-2. Regular and irregular LDPC codes..................39
4-1-3. Constructing LDPC codes...........................39
4-2. Performance complexity..............................40
4-3. Decoding LDPC codes.................................41
4-3-1. Hard-decision decoding............................41
4-3-2. Soft-decision decoding............................44
4-4. Encoding............................................47
Chapter 5 Performance Analysis and Simulation Results....49
5-1. Analysis construction of LMDS Systems...............49
5-1-1. Effects of XPD....................................49
5-1-2. Effects of Rain...................................55
5-2. Channel Quality.....................................60
5-3. Simulation Results used in Fuzzy control and LDPC code of LMDS system......................................64
Chapter 6 Conclusions....................................67
References...............................................68

                                

References
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