應用完美差異編碼的變異性建構非同調光分碼多工系統

Constructions of Non-Coherent Optical CDMA Systems With Variations of Perfect Difference Codes

葉弼群(Bih-Chyun Yeh)

指導教授 ： 吳靜雄

國立臺灣大學/電機資訊學院/電信工程學研究所/博士(2009年)

https://doi.org/10.6342/NTU.2009.10558

摘要

光分碼多工（OCDMA）技術同時地允許多個使用者通過網路並且提供區域網路 (local area network) 彈性和安全的傳輸。近幾年來，因為多使用者干擾 (multi-user interference, MUI) 可完全地藉由編碼除去。光譜振幅編碼光分碼多工(spectral Amplitude coding, SAC OCDMA)系統的非同調光源 (non-coherent light sources) 之相位引發強度雜訊 （phase-induced intensity noise, PIIN）嚴重地影響系統性能 (system performance)，因此，論文中我們將減少相位引發強度雜訊的效應。
這篇論文第一部份，我們研究三維光分碼多工系統 (spectral/spatial/time OCDMA)。我們也提出使用三維完美相差碼 (3-D perfect difference codes, 3-D PD codes) 的新穎之系統架構。由三維光分碼多工系統使用M 頻譜裝置的光纖布拉格(fiber Bragg gratings)，N 個時間裝置的時間延遲，和 P 空間裝置的光學分割器/組合器(splitter/combiner)，故密碼大小(code size) 為 MNP。這的確使三維完美相差碼發展中增加好處。
在二部份中，我們研究二維稀釋完美相差碼 （2-D diluted perfect difference codes, 2-D DPD codes），因為二維稀釋完美相差碼在二維完美相差碼上是一個稀釋方法，二維稀釋完美相差碼的交叉相關係數 (cross-correlation) 比較一維和二維低。二維稀釋完美相差碼擁有多使用者干擾消除特性。我們提出新密碼和對應的系統結構。由於光譜/空間 (spectral/spatial) 的光分碼多工系統使用二維稀釋完美相差碼，我們也研究相關聯的編碼/解碼 (encoding/decoding)。在光譜的領域中，我們利用二維稀釋完美相差碼特性，提出以光纖布拉格（FBGs）為基礎之光譜的編碼/解碼法裝置。在空間的領域中，我們採用分割器/組合器(splitter/combiner) 編碼/解碼法裝置。
最後，我們提出二維混合碼 (2-D hybrid codes) 和對應的系統架構。二維混合碼由一維整數格子碼 (1-D integer lattice codes) 和一維的完美相差碼 (1-D perfect difference codes) 組合而成。此二維混合碼系統具有可調 (tuning)，多使用者干擾消除及減低相位引發強度雜訊效應等特性。因此是一個低成本，簡單，和容易落實的光分碼多工系統。

關鍵字

多使用者干擾 ； 光分碼多工 ； 完美相差碼 ； 稀釋完美相差碼 ； 混合碼 ； 相位引發強度雜訊

並列摘要

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.
In 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.
In 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.
Finally, 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.

並列關鍵字

multi-user interference ； OCDMA ； perfect difference codes ； diluted perfect difference codes ； hybrid codes ； phase-induced intensity noise

參考文獻

[1] N. Karafolas, and D. Uttamchandani, “Optical Fiber Code Division Multiple Access Networks: A Review,” Optical Fiber Technol. 2, no. 0017, pp. 149-168, 1996.

[2] T. Erdogan, “Fiber Grating Spectra,” J. Lightwave Technol., vol. 15, no. 8, pp. 1277-1294, Aug. 1997.

[3] Max Ming-Kang Liu, “Principles and applications of optical communications”, ISBN 0-256-16419-0, pp: 57, 197, 1996

[4] C. J. Koester and E. Snitzer, “Amplification in a Fiber Laser,” Applied Optic, vol. 3, pp. 1182, 1964

[5] R. J. Mearsetal, “Low Noise Erbium Doped Fiber Amplifier Operating at 1.54 μm,” Electronics Letters，vol 23, pp. 1026, 1987