以雙波帶抑制載波調變及數位信號處理技術為基礎的光傳輸系統及網路之研究

Abstract

在本論文中，我們研究以雙波帶抑制載波調變及數位信號處理技術為基礎的光傳輸系統及網路之研究。主要的研究成果可以分為兩大部分。首先，我們以實驗及分析方法驗證一個射頻在18GHz，資料速率為5Gb/s的16QAM信號在100公里光纖上的傳輸品質。我們評估光纖放大器雜訊、光纖非線性、雷射光源的相位雜訊、系統頻率響應以及類比數位轉換器量化雜訊對傳輸系統品質的影響。此18GHz的16-QAM 信號可以直接從基地台以光纖傳送到遠端天線而不需要頻率轉換器，遠端終端機則可以用DSP的方式將信號解調。在本實驗中，我們是以20Gs/s 的數位類比轉換器做為信號干擾(ISI)及相位雜訊抑制數位信號處理(DSP)的前端。這些數位信號處理模組所使用的演算法也在本論文中有詳細說明。在本論文的第二部分中,我們提出並以實驗驗證一個在單一光纖雙向傳輸的光網路中以雙波帶抑制載波為基礎的保護架構。這個架構所需要的光發射機數量將比傳統架構所需的要少，也就是說一個雙波帶抑制載波的發射機就可以同時供工作及保護頻道使用。

In this dissertation, we study the optical transmission systems and networks based on double-sideband modulation with suppressed carrier (DSB-SC) and digital signal processing (DSP) techniques. The main research results are organized in two parts. In the first part, we experimentally and analytically proved the feasibility of a 100km radio-over- fiber (ROF) system using a 16-QAM signal with 5Gb/s bit rate and a carrier frequency of 18 GHz. The transmission system performance was analyzed by considering optical amplifier noise, fiber nonlinearity, phase noise, frequency response, and analog-to-digital converter (ADC) quantization noise. The 18 GHz, 16-QAM signal could be sent from the base station to a remote antenna port without any up-converter, and the remote terminal consists of a down-converter and high-speed digital signal processors (DSPs) to recover the 16-QAM signal. The high-speed DSP, which partially compensates the inter-symbol-interference (ISI) and phase-noise-induced system penalties, was enabled by 20 Gs/s ADCs. The algorithms used in the DSP blocks were also described in details. In the second part of this dissertation, a single-fiber optical unidirectional-path-switched ring (UPSR) based on subcarrier multiplexed double-sideband modulation with suppressed carrier was proposed and experimentally verified. This single-fiber UPSR architecture can be used to reduce the number of required optical transmitters, i.e., a single DSB-SC transmitter can be used for both east- and west-bound wavelengths.