Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/7801
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
摘要: 
這篇論文是由兩個部份組成:第一個部分是使用可變長度展頻碼之多波長光纖分碼多工系統。自相關與互相關最多為一的多波長光纖正交碼最近被提出來應用到波長─時域光纖分碼多工系統。此正交碼的基數值是波長數目的二次方程式。為了要支援不同速率和質素的多影像裝置,在這篇論文中我們代數地建構了新的自相關為零、互相關最多為一的可變波長、固定權重的多波長光纖正交碼。我們將分析這些新的碼在光纖分碼多工系統中應用於多影像裝置的效能。相對於傳統的單波長碼,我們的研究顯示出當碼長減少時,這些可變波長的碼在效能上會有所改善。而這獨特的特性是可以在光纖分碼多工系統中支援“優先處理性”的。
第二個部份要介紹的是使用質數碼的跳頻分碼多工系統。無線跳頻分碼多工系統被認知為是具有靈活性而且能支援多種裝置的無限多工技術之ㄧ。這個系統可以藉由給定與其他使用者不同的跳頻碼來允許多使用者共用相同的頻帶。在這篇論文中,首先我們先回顧一個利用質數碼具有良好互相關特性優點的跳頻分碼多工系統[19]。這個架構可以藉由使用質數碼序列的二次組合來提高資料速率。然而,在舊的分析中提到的並不夠精確。因此,我們從舊的分析中修正了一些方程式使分析更為準確。我們將比較新舊分析並將他們與模擬結果做比較。

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.
URI: http://hdl.handle.net/11455/7801
Appears in Collections:電機工程學系所

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