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標題: 多速率光纖多波長分碼多工系統之可變長度展頻碼之設計
Multiple-Length, Multiple-Wavelength Optical Orthogonal Codes for Optical CDMA Systems with Multirate Services
作者: 林茂富
Lin, Mao-Fu
關鍵字: O-CDMA;光纖分碼多工系統;Multiple-wavelength optical orthogonal code;multi-length;multimedia;prime code;Frequency-hopping code division multiple access;多波長光纖正交碼;可變長度;多影像;質數碼;跳頻分碼多工系統
出版社: 電機工程學系

The thesis consists of two parts: the first topic is O-CDMA with multi-length multiple-wavelength optical orthogonal codes. Multiple-wavelength optical orthogonal codes (MWOOCs) with autocorrelation sidelobes and cross-correlation values of both at most one were recently proposed for wavelength-time optical code-division multiple- access (O-CDMA) systems. Their cardinality is a quadratic function of the number of wavelengths. The codes find applications in high bit-rate optical CDMA systems with broadband supercontinuum lasers, in which the number of available wavelengths is larger than the number of time slots. To support multimedia services with different bit-rate and quality-of-service requirements, a new class of multiple-length, constant- weight, MWOOCs with autocorrelation sidelobes of zero and cross-correlations of at most one is constructed algebraically in this paper. The performance of these new codes in an O-CDMA system with double-media services is analyzed. In contrary to conve- ntional single-length codes, our study shows that the performance of these multiple- length codes improves as the code length decreases. This unique property supports ‘‘ prioritization'' in O-CDMA.
The second topic is FH-CDMA with Prime Code. Frequency-hopping code division multiple access (FH-CDMA) wireless systems have been known as one of the wireless multiple access techniques, which can provide various services with flexibility. By assigning a distinct FH pattern to each other, the FH- CDMA wireless systems can allow multiple users to share the same frequency band simultaneously. In this thesis, we first review a FH-CDMA system [19], which utilizes the advantage of the good cross- correlation properties of prime code. By using the quadratic combinations of prime code sequences, the scheme can increase the data rate. However, the analysis reported in old one was not accurate enough. Therefore, we correct some equations from old analysis to make it more precise. We compare the old analysis with the new one and show that the results from the new old agree with the simulation results.
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