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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/8383


    Title: 學習向量量化網路與低密度同位元檢查碼應用於區域多點分配服務系統;Learning Vector Quantization Compatible LDPC Code for LMDS Systems
    Authors: 謝福元;Fu-Yung Hsieh
    Contributors: 通訊工程研究所
    Keywords: 向量量化網路;檢查碼;LMDS;LDPC
    Date: 2009-06-23
    Issue Date: 2009-09-22 11:24:14 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 論文名稱:學習向量量化網路與低密度同位元檢查碼應用於區域多點分配服務系統 校所組別:國立中央大學通訊工程研究所 畢業時間及提要別:九十七學年度第二學期 碩士 研究生:謝福元 指導教授:蔡木金 教授 林嘉慶 教授 論文提要內容: 在各項微波傳輸技術中,Local Multipoint Distribution System(區域多點分配服務)可以說是最受到注目的,它是雙向數位蜂?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,服務的範圍相當廣泛,具有很大的彈性及擴充性。但是在LMDS系統中,外在環境的變化會嚴重影響系統的效能,常見的就是落雨。除了落雨會影響系統的效能,另外一個影響的系統效能的就是細胞間互相的干擾。 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,並以學習向量量化網路具有快速學習分類及易於實現的特性來判斷通道品質的好壞來,決定碼率的使用,當系統的外在干擾大於某評估值則使用較長的編碼傳送資料,反之,則以較短的編碼傳送。在編碼的部分則運用錯誤更正碼之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,在不損失錯誤率下,提升頻寬效益,達到增進系統效能的目標。 Abstracts 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-c ell interference (ICI). Avoiding the band-width unnecessary waste, we proposed new idea that is the LVQ compatible LDPC code for LMDS system. It utilized LVQ and according to the LMDS system channel quality to determine the code rate. 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. We use learning vector quantization nets to classify the data. 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.
    Appears in Collections:[通訊工程研究所] 博碩士論文

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