臺灣博碩士論文加值系統

展碼分相鍵移調變 (Code-Phase Shift Keying，簡稱CPSK) 是一種使用於分碼多重接取系統 (第三代行動通訊系統CDMA)中的新的技術，它結合了M陣列信號調變和展頻傳送部分。展碼分向鍵移調變的基本想法就是對於M個不同的因編碼而產生的傳送符號 (symbol)，每個符號由特定的碼序列 (code sequence) 來代表。這M個不同的碼序列其實是取自於同樣的一組最大長度虛擬隨機碼序列 (Maximal-Length sequence)，只是彼此之間有著不同的碼相 (code phase) 而已。根據m-sequence的週期大小還有碼序列長度 (即展頻增益) 的不同，我們又可將碼序列分為短碼序列 (short code sequences) 還有長碼序列(long code sequences) 兩種形式。要完成展碼分相的動作,我們在此提出一種方式,它是利用固定的一組Maximal-Length sequence產生器 (m-sequence generator) 和一個子碼遮罩 (code mask) 的機制。本篇論文中，我們考慮在一個標準的高斯雜訊通道 (AWGN channel) 且包含了多用戶干擾 (multi-user interference) 情形下，利用兩種不同的碼序列取樣方式，探討並分析系統的效能評比。我們也會使用數值分析軟體Matlab來模擬不同的環境，並將模擬的結果理論分析值相比較。而對於不完美通道所造成的載波相位偏移，我們將利用非同調檢測接收器,也就是能量偵測 (energy detection) 的方式來消除相位偏移。這些分析也會在本文中詳細討論。最號我們還會討論當通道遭遇多重通道效應 (multi-path effect) - 雷利衰減 (Rayleigh fading) 的情況，並且將分析結果根傳統的BPSk，BFSK等信號調變分是做比較。

Code-phase shift keying modulation is a new technology presented recently. It derives from the conventional DSSS system and is modified by employing distinct symbols with distinct code phases of a single periodic m-sequence. According to the length of period and sampling interval of the m-sequence, CPSK can be separated into two kinds: short code sequences and long code sequences. The advantages of using M-ary CPSK is to advance the power efficiency compared to conventional BPSK and advance the bandwidth efficiency by increasing . It also raises the system flexibility by using long code sequences. We will show the analysis about system performance and illustrate the implementation of two methods.

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附錄 英文論文本……………………………………………………….5

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