偏移正交-正交相位鍵移調變訊號之研究

Abstract

本篇論文提出一對較為平滑（smoother）且相互正交的資料成形脈波（data shaping pulse），使偏移正交-正交相位鍵移調變（offset quadrature-quadrature phase shift keying, OQ2PSK）訊號具備頻譜旁波（spectral sidelobe）快速衰減的特性，能達到比Saha和Chung的正交-正交相位鍵移調變更高的頻譜緊密度與頻譜效率（spectral efficiency），且可確保頻譜旁波以f-2(N+M)-2以上的速度在衰減，其中N和M為與訊號的資料成形脈波有關。在論文中將與Saha及Chung的系統就頻帶外功率比例（fractional out-of-band power）與峰值對平均功率比（peak-to-average power ratio, PAPR）來互相比較。 同時我們在論文中探討偏移正交-正交相位鍵移調變訊號在通過加成性白高斯雜訊（addictive white Gaussian noise，AWGN）通道及多重路徑雷力衰減（multipath Rayleigh fading）通道下之效能分析。在多重路徑雷力衰減通道下中，偏移正交-正交相位鍵移調變訊號將會引起碼際戶擾（inter-symbol interference, ISI）及相互碼際戶擾（cross-symbol interference, CSI）而影響系統效能，這些效應的大小與訊號的資料成形脈波有關，在論文最後將與Chung的系統比較位元錯誤率（bit error probability）。

In this thesis, we propose a much smoother data shaping pulse pairs for offset quadrature-quadrature phase shift keying. Thus, offset quadrature-quadrature phase shift keying provides higher spectral compactness and spectral efficiency than CL-Q2PSK and SB-Q2PSK. Because offset quadrature-quadrature phase shift keying meets the fast sidelobe-decaying constraint, it ensures the power spectral sidelobe decaying asymptotically with f-2(N+M)-2 as f approaches infinity. We compare the fractional out-of-band power and peak-to-average power ratio with SB-Q2PSK and CL-Q2PSK in the thesis. Meanwhile, the error performance over additive white Gaussian noise channel and multipath Rayleigh fading channel will be analyzed in this thesis. In the multipath fading channel, the error performance of offset quadrature-quadrature phase shift keying will be influenced by inter-symbol interference and cross-symbol interference related to the data shaping pulse. We will compare the error performance with CL-Q2PSK in the end.