| Summary: | 碩士 === 國立成功大學 === 電腦與通信工程研究所 === 95 === The arrayed-waveguide grating-based (AWG-based) coder/decoder (codec) is configured over optical local-area networks (LANs). In order to increase the number of subscribers and enhance the confidentiality of the optical CDMA (OCDMA) system, we proposed a coding scheme named time-spreading and wavelength-group-hopping (TS/GH scheme), and developed an AWG-based system for excellent data confidentiality over Fiber-to-the-Home (FTTH) network.
The proposed code matrix, which is coded in time and spectral (wavelength) domain, is referred as two-dimensional (2-D) optical codes. In time domain, we utilized conventional prime code. However, both prime code and maximum-length sequence (M-sequence) code were utilized in spectral domain. Importantly, for the proposed broadband light source (BLS), the total number of available wavelengths is partitioned into G different groups based on M-sequence code length. Every group is referred as hopping chip and characterized by the free-spectral-range (FSR) interval of AWG router.
Due to cyclic property of M-sequence codes and hopping chip is characterized by the FSR of AWG router. In this thesis, we exploited the inherent cyclic and periodic FSR properties of AWG router, the proposed scheme is configured by AWG-based codec over FTTH network.
The multiple-access interference (MAI) and bit error rate (BER) of the proposed scheme are also evaluated and the result reveals that the BER of the proposed scheme is better than conventional prime-hop code (PHC). Moreover, the proposed TS/GH scheme provides higher confidentiality for OCDMA system.
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