鄭士康臺灣大學：電信工程學研究所張育嘉Chang, Yu-ChiaYu-ChiaChang2007-11-272018-07-052007-11-272018-07-052007http://ntur.lib.ntu.edu.tw//handle/246246/58805MC-CDMA系統在經過傳輸通道後，由於通道的影響，失去正交性，使得不同使用者間彼此產生干擾，稱之為MAI(Multiple Access Interferences)。本篇論文主要是藉由MAI功率的數學式，了解通訊碼選取對MAI功率的影響，再經由反覆過濾影響MAI功率的因素，找出最佳的通訊碼以降低MAI的干擾。Because of the channel effect, the MC-CDMA signals will lose orthogonality and result in the Multiple Access Interference (MAI). This thesis will derive the MAI formula to get the correlation between the spreading sequence and MAI. According to this correlation, we can find the optimal spreading sequence sets to mitigate MAI.目錄 誌謝.....................................................ii 中文摘要................................................iii 英文摘要.................................................iv 圖目錄.................................................viii 表目錄...................................................xi 第一章 緒論..........................................1 1.1 研究背景與動機...................................1 1.2 文獻回顧.........................................1 1.3 論文章節介紹.....................................2 第二章 OFDM系統的原理與架構..........................3 2.1 OFDM的特性.......................................3 2.1.1 正交性......................................4 2.2 傳統OFDM系統的架構..............................6 2.3 離散傅立葉OFDM系統的架構........................8 2.4 OFDM系統的傳輸與接收.............................9 2.5 保護區間與循環字首..............................10 2.6 OFDM的優缺點....................................12 第三章 結合OFDM與CDMA之系統........................14 3.1 Walsh Code......................................14 3.2 MC/DS-CDMA......................................15 3.3 MT-CDMA.........................................17 3.4 MC-CDMA.........................................18 3.5 系統比較........................................23 3.6 無線通道模型....................................24 3.6.1 小尺度衰落.................................25 3.6.2 Rayleigh分布...............................28 3.6.3 Rician分布.................................28 3.6.4 頻率選擇性衰落通道模型.....................29 第四章 MC-CDMA降低MAI之通訊碼選取最佳化............30 4.1 MC-CDMA系統描述.................................30 4.2 MAI數學式.......................................31 4.3 MAI 功率........................................33 4.4 通訊碼選取最佳化................................34 4.4.1 文獻方法...................................35 4.4.2 本論文提出之改善方法.......................36 第五章 模擬架構.....................................40 5.1 領航訊號........................................40 5.2 通道估測........................................42 5.3 組合法..........................................44 5.3.1 MRC........................................45 5.3.2 EGC........................................45 5.3.3 ORC........................................46 5.3.4 MMSEC......................................47 5.3.5 組合法整理.................................48 5.4 COST 259 通道模型...............................49 第六章 模擬結果與討論...............................54 6.1 文獻方法與改善方法效能比較.......................54 6.2 最佳化通訊碼相對於組合法.........................55 6.3 最佳化通訊碼相對於使用者人數......................58 第七章 結論.........................................66 參考文獻.................................................671043734 bytesapplication/pdfen-US通訊碼選取使用者間干擾MC-CDMAMAIlAllocationthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/58805/1/ntu-96-R93942103-1.pdf