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一種架構於近乎正交布雷格光纖光柵之非同調光纖分碼多重進接網系統
Abstract
本文構想出一種適於非同調光纖分碼多重進接網路系統的頻域編解碼裝置,此編解碼裝置是根據預先蝕刻於布雷格光纖光柵的近乎正交序碼的良好相關特性來設計。我們在光柵光纖內預寫入對應於最大長度序碼(m-sequence codes)的布雷格波長序碼列,則類如發光二極體的寬頻光源訊號將被切剖成好幾個波頻細片元(spectral chips),每個波頻細片的中心波長都不同且分佈在入射光源的頻寬之中。一個周期長度為N的最大長度序碼,可以提供N個不同位移循環的序碼語句給N位多工使用者,造到N倍的分碼多工網路系統容量。光纖分碼多重進接系統在每個接收端往往會遭遇到其他使用者所造成的多重擷取干擾(Multiple-Access Interference, MAI),這使得接收端易於發生錯誤,降低系統的性能。透過最大長度序碼的移位-相加(shift-and-add)族群特性以及搭配新式的編解碼器設計,就能適切地排除多重擷取干擾的影響,這不僅降低了錯誤率的發生,也大大提升了整個系統的性能。This paper devises a spectral coding scheme for incoherent optical code-division multiple-access (OCDMA) networks. The spectral coding is based on the pseudo-orthogonality of OCDMA codes properly written in the fiber Bragg grating (FBG) devices. For an incoming broadband optical signal having spectral components equal to the designed Bragg wavelengths of the FBG, the spectral components will be reflected and spectrally coded with the written address codes. Each spectral chip has different central wavelength and is distributed over the spectrum of the incoming light source. To overcome the limiting factor of multiple-access interference (MAl) of OCDMA network, FBG decoder is configured on the basis of orthogonal correlation functions of the nearly orthogonal m-sequence codes. An intended receiver user that operates on the defined orthogonal correlation functions will reject any interfering user and obtain a quasi-orthogonality among the OCDMA users in the network system.
Keywords
光分碼多重進接; 布雷格光纖光柵; 多重擷取干擾; 近乎正交最大長度序碼; Optical Code-Division Multiple-Access (OCDMA); Fiber Bragg Gratings (FBGs); Multiple-Access Interference (MAI); Nearly Orthogonal M-sequence Codes
Citation Format:
黃振發(Jen-Fa Huang), 楊朝欽(Chao-Chin Yang), 鄭旭志(Hsu-Chih Cheng), "一種架構於近乎正交布雷格光纖光柵之非同調光纖分碼多重進接網系統," Journal of Internet Technology, vol. 2, no. 4 , pp. 343-350, Oct. 2001.
黃振發(Jen-Fa Huang), 楊朝欽(Chao-Chin Yang), 鄭旭志(Hsu-Chih Cheng), "一種架構於近乎正交布雷格光纖光柵之非同調光纖分碼多重進接網系統," Journal of Internet Technology, vol. 2, no. 4 , pp. 343-350, Oct. 2001.
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Published by Executive Committee, Taiwan Academic Network, Ministry of Education, Taipei, Taiwan, R.O.C
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