Spatial/Spectral OCDMA System Using Partial Modified Prime Code and Error Correcting Code
Date Issued
2006
Date
2006
Author(s)
Huang, Wen-Jeng
DOI
en-US
Abstract
Code division multiple access (CDMA) plays an important role in communications technologies nowadays. In mobile communications, it has been well developed due to its advantage of multiple access, anti-jamming, high-level security, asynchronous transmission, multi-path resistance, and multi-rate transmission. In all-optical communications, many optical CDMA (OCDAM) systems are proposed and getting more and more attention.
The early OCDMA network proposals were based on coded sequences of noncoherent pulses. The used optical orthogonal codes (OOCs) generally have poorer correlation properties and limited code size. Recently, several alternative OCDMA schemes based on spectral amplitude coding (SAC) have been proposed. These proposals do not require the complexity of coherent system. SAC OCDMA systems can cancel the multiuser interference (MUI) by employing the code sequences with fixed in-phase cross correlation. However, the phase-induced intensity noise (PIIN) due to the intensity fluctuation of the broadband light source (BLS) still severely affects the system performance.
Another issue is to support a large number of simultaneous users, thus two-dimensional (2-D) coding schemes attract a lot of attention. Among those schemes, spatial/spectral coding OCDMA has the advantage of SAC coding scheme while the maximum number of users under a specific performance can be increased. Because fibers are inexpensive nowadays, spatial/spectral coding scheme is a realizable solution.
In this thesis, we propose a new system architecture of spatial/spectral coding 2-D OCDMA systems combining with error correcting codes (ECC). The scheme of using partial modified prime (PMP) codes can completely eliminate the MUI due to its zero cross-correlation property. And the PIIN can be suppressed. Further more, the system performance is improved by employing ECC on spectral domain while no additional wavelength is needed comparing to the conventional 2-D OCDMA system using PMP codes. The results show that data bit error rate can be as low as at data rate of 10Gbps. Compared with other 2-D OCDMA systems, our proposed system is much simpler and has better performance without any extra wavelength.
Subjects
光分碼多工
部分變異質數碼
錯誤更正碼
OCDMA
PMP code
ECC
Type
thesis
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