| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 99 === In this thesis, short-code direct-sequence-spreading-spectrum (DSSS) signals occupying minimum Nyquist bandwidth are investigated in terms of implementation feasibility and associated with the analysis of the property of temporal sidelobe decaying. The proposed short-code DSSS signals are bandlimited and realizable without consuming any excess bandwidth, as is required in traditional bandlimited short-code DSSS signals using the square-root raised cosine (SRRC) pulse shaping. A general constraint on short code is developed to guarantee that a short-code DSSS signal is realizable and exhibits fast-decaying temporal sidelobes which decay asymptotically as |t|^(-K-1), with K being a positive-integer-valued design parameter. Based on the constraint, existing short codes including Walsh-Hadamard (WH), orthogonal complementary Golay (OCG), discrete Fourier transform (DFT), and modified Zadoff-Chu (ZC) codes, are evaluated for realization feasibility in terms of the minimum-Nyquist-bandwidth DSSS signaling format. It is analytically shown that the realizable signaling formats using WH, OCG, DFT, and modified ZC codes and the corresponding temporal sidelobe decaying properties can be completely described by their code indices.
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