梳狀頻譜分碼多重存取之頻率旁波特性

Abstract

In this thesis, general constraints on the employed spreading code are developed for comb spectrum code-division multiple access (CS-CDMA) systems to warrant the desirable spectral property that the power spectral sidelobes decay asymptotically as f-2Q-2, where Q is a preassigned positive integer. Precisely, f-4 and f-6-decaying codewords are designed to provide small sidelobes decaying and thus mitigate adjacent channel interference. It is shown that the sidelobe decaying characteristic of the CS-CDMA signal can be properly described by the code index of the underlined zero-insertion Walsh-Hadamard codeword. Finally, unequal magnitude spectral sidelobe decaying codewords are also devised to achieve the desirable spectral property of the fast sidelobe decaying.