利用前項糾錯碼結合高波峰裁剪技術降低高功率峰均比效應於光的正交分頻多工系統

近年來，由於高頻寬需求用戶的增加，都會光纖網路已逐漸成為未來的主流，以目前的趨勢來說，如何在傳統摻鉺光纖放大器的頻寬中將骨幹網路的頻寬效率提升已經是一個重要的課題，由於正交分頻多工 (OFDM) 技術具有高頻譜效益及抵抗符號間干擾 (ISI) 的優點，在10Gbps甚至於更高的傳輸速率下幾乎不需用到色散補償，即使是運用在高距離傳輸上。另一方面對以正交多頻分工為基礎的第四代行動通訊系統來說，正交分頻多工在光纖網路上的研究能有助於未來簡化無線通訊系統基地台與電信機房的調變模式，對於未來無線網路與都會光纖網路的整合有莫大助益。在本篇論文中，我們提出了一個利用前向糾錯碼結合高波峰剪裁技術的光正交分頻多工系統，能有效的降低正交分頻多工無法避免的高功率峰均比效應，並解決在長距離光纖傳輸系統上限制傳輸距離頻頸的色散效應。我們的模擬數據指出，經過8000公里的單模光纖 (SMF) 傳輸，我們的系統在6-dB的剪裁比率(clipping ratio) 配合前向糾錯碼下可以提升5-dB的光雜訊比 (OSNR)，此外此系統相對於完全沒有作波峰剪裁的系統，在同樣加入前向糾錯碼情形下，有1.5-dB左右的光雜訊比的增進，同時證明了我們在長距離傳輸完全不需用到色散補償光纖，另外由於正交分頻多工本身的特性也能大幅簡化等化器 (equalizer) 的複雜度。

關鍵字

正交分頻多工；高功率峰均比；波峰裁剪；色散；前項糾錯；單模光纖

並列摘要

Orthogonal Frequency Division Multiplexing (OFDM) is a popular modulation format by splitting a high-speed data stream into a number of substreams of lower data rate and then transmits these data substreams on adjacent orthogonal subcarriers [1]. Due to its multi-carrier nature, one of the biggest drawbacks of OFDM is the high peak-to-average power ratio (PAPR), which introduces several disadvantages, such as increasing complexity of the analog-to-digital and digital-to-analog converters (ADC/DAC) and reducing power efficiency of the optical modulator [2]. The simplest way to reduce PAPR is peak power clipping. In this thesis, we proposed a Forward Error Correction (FEC) enhanced data clipped 10-Gbps optical OFDM system to reduce PAPR effect. After 8000km of single mode fiber (SMF) transmission, numerical simulations indicate >5-dB optical signal-to-noise ratio (OSNR) improvements under high clipping ratio of 6-dB with FEC. In addition, our system also exhibits a 1.5-dB OSNR improvement over the case with only FEC applied but without peak power clipping.

並列關鍵字

OFDM ； PAPR ； Peak Power Clipping ； Dispersion ； FEC ； Single Mode Fiber (SMF)

參考文獻

[3] A. J. Lowery and J. Armstrong, “Orthogonal-frequency-division multiplexing for dispersion compensation of long-haul optical systems” Opt. Express, 14, pp. 2079-2084, 2006.

[4] W. Shieh and C. Athaudage, “Coherent Optical Orthogonal Frequency Division Multiplexing,” IEE Electron. Lett., vol. 42, No. 10, May, 2006.

[5] I. B. Djordjevic and B. Vasic, “Orthogonal frequency division multiplexing for high-speed optical transmission,” Opt. Express, 14, pp. 3767-3775, 2006.

[6] A. J. Lowery, L. Du, and J. Armstrong, “Orthogonal Frequency Division Multiplexing for Adaptive Dispersion Compensation in Long Haul WDM Systems,” OFC 2006, Paper PDP3, Anaheim, CA, USA.

[7] J. M. Tang, P. M. Lane, and K. A. Shore, “High-Speed Transmission of Adaptively Modulated Optical OFDM Signals Over Multimode Fibers Using Directly Modulated DFBs,” IEEE/OSA J. Light. Tech., vol. 24, pp. 429-441, 2006.

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利用前項糾錯碼結合高波峰裁剪技術降低高功率峰均比效應於光的正交分頻多工系統

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