利用最大長度碼(M-sequence)的循環特性與平衡光檢測(balanced detection)架構，光頻域振幅分碼多工(Spectral-amplitude coding optical CDMA)網路在光譜平坦的理想狀態下可完全地消除傳輸中的多重擷取干擾(Multiple access interference, MAI)。然而，光源相位擾動在光檢測器所引致的強度雜訊(Phase induced intensity noise, PIIN)仍是光頻域振幅分碼多工架構的重要干擾來源且此雜訊無法藉由提高接收端功率來抑制。前向糾錯(Forward error correcting)編碼即可作為一種有效降低相位引致強度雜訊造成之位元錯誤率的編碼技術。
在此論文中，我們提出一種有效方法來結合籬柵編碼與光頻域振幅分碼多工技術，以最大長度編碼來拉長籬笆圖(Trellis diagram)中枝節(branch)所構成的自由距離(Free distance)，進而改善系統的錯誤率。相較於其它的前向糾錯編碼，我們的方法更為簡單、有效率，更適合應用在高速度與高容量的通訊光網路上，同時也保留了光頻域振幅分碼多工消除多重擷取干擾的功能。
在本論文中，我們在傳輸同步與光譜平坦的假設下分析系統效能，因此平衡檢測器輸出的多重擷取干擾將被完全消除。散粒雜訊(shot noise)和熱雜訊(thermal noise)與主要的相位引致強度雜訊相較下可被忽略。我們進一步分析了使用者數目與錯誤率的關係，結果顯示我們的架構更具有彈性，可適當的調整以因應不同的通道環境，並維持一定的錯誤率表現。

Utilizing the cyclic characteristic of m-sequences and corresponding balanced detection scheme, spectral amplitude coding optical code-division multiple access (SAC-OCDMA) networks can be operated without multiple-access interference (MAI) under assumption of spectrum flatness. However, the phased-induce intensity noise (PIIN), the mixed term of incoherent light fields caused by photodetector, is still the dominative problem and cannot be eliminated by increasing the received power. Forward error correcting (FEC) code is a useful coding technique to reduce the error bits caused by PIIN.
We present one novel method to employ trellis-coded scheme in the SAC-OCDMA system using m-sequence code for larger free distance in trellis. To figure out the problems caused by PIIN, FEC has been considered as a useful solution. However, in a high speed and large capacity networks, it is suitable to use a simple and efficient coding scheme. Our configuration not only preserves the ability of multiple-access interference (MAI) cancellation and provides multiple users to access in SAC OCDMA system, but also can eliminate the errors caused by PIIN.
This research is under the assumption of synchronous case and MAI cancellation ideally. Shot noise and thermal noise can be neglected since PIIN is the dominative noise taken into consideration. The relation between number of active users and bit error rate (BER) is schematized in this thesis. The results suggest that this configuration is flexible and can be adjusted for further BER improvement.

[01]. R. Dixon, “Why spread spectrum?,” IEEE Communications Soc. Mag., vol. 13, pp. 21-25, July 1975][ R. Scholtz, “The spread spectrum concept,” IEEE Transactions on Communications, vol. 25, no. 8, pp. 748-755, August 1977][ R. Scholtz, “The spread spectrum concept,” IEEE Transactions on Communications, vol. 25, no. 8, pp. 748-755, August 1977.
[02]. R. Dixon, Spread Spectrum Systems with Commercial Applications, Wiley- Interscience, New York, 1994.
[03]. M. Sust, “Code division multiple access for commercial communications,” in Review of Radio Science 1992-1994, pp. 155-179, International Union of Radio Science (URSI).
[04]. D. Grosbie, “The new space race: satellite mobile communications,” IEE Review, vol. 39, no. 3, pp. 111-114, May 1993.
[05]. J. A. Salehi, “Code division multiple-access techniques in optical fiber network-Part I: Fundamental principles,” IEEE Transactions on Communications, vol. 37, no. 8, pp. 824-833, August 1989.
[06]. E. Marom and O. G. Ramer, “Encoding-decoding optical fiber network,” Electron. Lett., vol. 14, no. 3, pp. 48, 1978.
[07]. G. Vannucci, “Combining frequency division multiplexing and code division multiplexing for high capacity optical network,” IEEE Network, vol. 3, no. 2, pp. 21-30, March 1989.
[08]. N. Karafolas and D. Uttamchandani, “Optical fiber code division multiple access networks: a review,” Optical Fiber Technol., vol. 2, no. 17, pp. 149-168, 1996.
[09]. P. Prucnal, M. Santoro and T. Fan, “Spread spectrum fiber optic local area network using optical processing,” IEEE Network, vol. 4, no. 5, pp. 547-554, May 1986.
[10]. W. C. Kwong, P. Perrier and P. R. Prucnal, “Performance comparison of asynchronous and synchronous code-division multiple-access techniques for fiber-optic local area networks,” IEEE Transactions on Communications, vol. 39, no. 11, pp. 1625-1634, Nov. 1991.
[11]. K. P. Jackson, G. Xaio and H. J. Shaw, “Coherent optical fiber delay-line processor,” Electron. Lett., vol. 22, no. 25, pp. 1335, 1986]-[ M. E. Marhic, “Trends in optical CDMA,” in Multigigabit Fiber Communications, SPIE Proceedings vol. 1787, pp.80-97, Boston, 1992
[12]. D. D. Sampson and D. A. Jackson, “Spread spectrum optical fiber network based on pulsed coherent correlation,” Electron. Lett., vol. 26, no. 19, pp. 1550-1552, Sept. 1990.
[13]. R. A. Griffin, D. D. Sampson, and D. A. Jackson, “Optical phase coding for code division multiple access,” IEEE Photon. Technol. Lett., vol. 4, no. 12, pp. 1401-1404, Dec. 1992
[14]. D. Sampson, R. A. Griffin, and D. A. Jackson, “Photonic CDMA by coherent matched filtering using time-addressed coding in optical ladder networks,” IEEE J. Lightwave Technol., vol. 12, no. 11, pp. 2001-2010, Nov. 1994
[15]. J. Enriguz-Gabeiras, J. Camany, and R. Fernandez de Caleya, “ Efeect of non ideal and fiber parameters on the performance of an all optical coherent code division multiple access,” in Proceedings of EFOC/LAN’92, pp. 146-151, Paris, June 1992
[16]. M. Brandt-Pearce and B. Aazhang, “Multiuser detection for optical code division multiple access systems,” IEEE Transactions on Communications, vol. 42, no. 2, pp.1801-1810, Feb./Mar./Apr. 1994.
[17]. D. V. Sarwate and M. B. Pursley, “Crosscorrelation properties of pseudorandom and related sequences,” Proceedings of the IEEE, vol. 68, no. 5, 593-619, May 1980.
[18]. M. E. Marhic, “Coherent optical CDMA networks,” IEEE/OSA J. Lightwave Technol., vol. 11, no. 5/6, 854-863, May./June. 1993.
[19]. J.A. Salehi, A.M. Weiner, and J.P. Heritage, “Coherent ultrashort light pulse code-division multiple-access communication systems,” J. Lightwave Technol., vol. 8, no. 3, pp. 478-491, March 1990.
[20]. D. Zaccarin and M. Kavehrad, “An optical CDMA system based on spectral encoding of LED,” IEEE Photon. Technol. Letter, vol. 5, no. 4, pp. 479-482, 1993.
[21]. M. Kavehrad and D. Zaccarin, “Optical code- division-multiplexed systems based on spectral encoding of non-coherent sources,” J. Lightwave Technol., vol. 13, no. 3, pp. 534 -545, March 1995.
[22]. J. F. Huang, and D. Z. Hsu, “Fiber-grating-based optical CDMA spectral coding with nearly orthogonal M-sequence codes,” IEEE Photon. Technol. Letter, vol. 12, pp. 1252-1254, Sept. 2000.
[23]. D. W. Faulkner and Y. Maeda, “PON systems standards developments in FSAN and ITU-T,” in Proc. Eur. Conf. Optical Communications (ECOC), Rimini, Italy, 2003, pp. 20-23, paper Mo3.1.4.
[24]. C.C Yang, J.F Huang, “Optical CDMA network codecs structured with m-sequence codes over waveguide-grating routers”, IEEE Photon. Technol. Letter, vol. 16, pp. 641-643, Feb., 2004.
[25] Z. Wei, H.M.H. Shalaby, and H. Ghafouri-Shiraz, “Modified quadratic congruence codes for fiber Bragg-grating-based spectral-amplitude-coding optical CDMA systems,” IEEE Photon. Technol. Letter, vol. 19, pp.1274-1281, Sept. 2001.
[26]. M. K. Smit, “New focusing and dispersive planar component based on an optical phased array,” Electron. Letter, vol. 24, pp. 385-386, 1998.
[27]. H. Takahashi, K. Oda, H. Toba, and Y. Inoue, “Transmission characteristics of arrayed-waveguide N×N wavelength multiplexer,” J. Lightwave Technol., vol. 13, no. 3, pp. 447-455, March 1995.
[28]. H. Takahashi, K. Oda, and H. Toba, “Impact of Crosstalk in an Arrayed-Waveguide Multiplexer on N×N Optical Interconnection,” J. Lightwave Technol., vol. 14, no. 6, pp. 1097-1105, June 1996.
[29]. L. R. Chen, “Technologies for hybrid wavelength-time optical CDMA transmission”, Conference on Electrical and Computer Engineering, 2001. Canadian, vol. 1, pp. 435-440, 2001.
[30]. E. Pennings, G..-D. Khoe, M. K. Smit, and T. Staring, “Integrated-optic versus micro optic devices for fiber-optic telecommunication systems: A comparison,” IEEE J. Sel. Topics Quantum Electron., vol. 2, pp. 151-164, June 1996.
[31]. M. E. Marhic, “Hierarchic and combinational star couplers,” Optics Letters, vol. 9, pp. 368-370, Aug. 1984.
[32]. D.K. Jung, “WDM PON based on spectrum-sliced fiber amplifier light source”, OFC ’98 Technical Digest.
[33]. Vivek Arya and Ira Jacobs, “Optical preamplifier receiver for spectrum-sliced WDM” J. Lightwave Technol., vol. 15, NO.4, APRIL 1997.
[34]. P.R. Morkel et al., “Noise characteristic of high-power doped-fiber superluminscent sources,” Electron. Lett. vol. 26, no. 2, pp. 96-98, 1990.
[35]. J.F. Massicott, R. Wyatt, and B.J. Ainslie, “Low noise operation of Er3+ doped silica fiber amplifier around 1.6 nm wavelength region,” Electron. Lett., vol. 28, pp. 1924-1925, 1992.
[36]. H. Ono, M. Yamada, and Y. Ohishi, “Gain-flattened Er3+-doped fiber amplifier for a WDM signal in the 1.57-1.60nm wavelength region,” IEEE Photon. Technol. Lett., vol. 9, pp. 596-598, May 1997.
[37]. M. Jinno, T. Sakamoto, J. Kani, S. Aisawa, K. Oda, M. Fuki, H. Ono, and K. Oguchi, “First demonstration of 1580 nm wavelength band WDM transmission for doubling usable bandwidth and suppressing FWM in DSF,” Electron. Lett., vol. 33, pp. 882-883, 1997.
[38]. D. Lowe, R. DiMuro, and S. Wilson, “75 nm of continuous gain using a noval EDFA topology,” in Proc. Euro. Conf. Optical Communications 2000, Munich, Germany, Paper 6.4.1.
[39]. “Error control coding fundamentals and applications”, Shu Lin, Pearson Education International, 2nd edition.
[40]. S. Mason and H. Zimmermann, Electronic Circuits, Signals, and Systems. John Wiley, New York, N.Y., 1960.
[41]. A.J. Viterbi, “Error Bounds for Convolutional Codes and an Asymptotically Optimum Decoding Algorithm,” IEEE Trans. Inform. Theory, IT-13:260-69, April 1967.
[42]. J.K. Omura, “On the Viterbi Decoding Algorithm,” IEEE Trans. Inform. Theory, IT-15: 177-79, January 1969.
[43]. L.R. Bahl, J. Cocke, F. Jelinek, and J. Raviv, “Optimal Decoding of Linear Codes for Minimizing Symbol Error Rate,” IEEE Trans. Inform. Theory, IT-20: 284-87, March 1974.
[44]. E.D.J. Smith, R.J. Blaikie, and D.P. Taylor, “Performance enhancement of spectral-amplitude-coding optical CDMA using pulse-position modulation,” IEEE Transactions on Communications, vol. 46, pp. 1176-1185, Sept. 1998.
[45]. B. Moslehi, “Noise power spectra of optical two-beam interferometers induced by the laser phase noise,” J. Lightwave Technol., vol. 4, no. 11, pp. 1704-1710, Nov. 1986.
[46]. M. Y. Liu, H.W. Tsao, “Trellis-Coded Asynchronous Optical CDMA Systems”, IEEE. Jounal of Lightwave Tech, vol. 19, pp. 180-185, Feb. 2001.