Constructions of Non-Coherent Optical CDMA Systems With Variations of Perfect Difference Codes
Date Issued
2009
Date
2009
Author(s)
Yeh, Bih-Chyun
Abstract
Optical code-division multiple access (OCDMA) techniques, which allow multiple users to access the network simultaneously, provide a flexible and secure transmission in the local area network. In recent years, the multi-user interference (MUI) can be completely eliminated by coding. Because the SAC (spectral Amplitude coding) OCDMA has a phase-induced intensity noise (PIIN) of the non-coherent light sources, the system performance is hence degraded severely by the PIIN. In the thesis, we investigate the codes and their corresponding system architecture to reduce the impact of the PIIN.n the first part of the thesis, we study the tree-dimensional (3-D) spectral/spatial/time OCDMA. We propose the novel system architecture using the 3-D perfect difference codes (3-D PD codes). Due to the M spectral devices based on the fiber Bragg gratings (FBGs), the N time devices based on the time delay, and the P spatial devises based on the optical splitter/combiner, the code size is the MNP. The development of the 3-D PD codes increases the system performance.n the second part of the thesis, we research the 2-D diluted perfect difference codes (2-D DPD codes). Since the 2-D DPD codes are derived by the dilution method based on the 2-D PD codes, the cross-correlation of the 2-D DPD codes is lower than that of the 1-D and 2-D codes. Even if the operation of 2-D DPD codes has the MUI cancellation property, we propose a family of newly constructed codes and a corresponding system structure. Due to the spectral/spatial OCDMA, we use the 2-D DPD codes and study the associated encoding/decoding scheme. In spectral domain, we utilize the 2-D DPD codes and the spectral encoding/decoding device based on the fiber Bragg gratings (FBGs). In spatial domain, we adopt the 2-D DPD codes and the spatial encoding/decoding device based on the optical splitter/combiner. inally, we propose the 2-D hybrid codes and the corresponding system architecture. The 2-D hybrid codes are derived from the combination of the 1-D integer lattice codes and the 1-D perfect difference codes. This characteristic of the 2-D hybrid system has the tuning ability, the MUI cancellation property and the PIIN decrement. Therefore, a low cost, simple, and easy implementation OCDMA system is presented.
Subjects
multi-user interference
OCDMA
perfect difference codes
diluted perfect difference codes
hybrid codes
phase-induced intensity noise
Type
thesis
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