Yen Chih-Ta, Chen Wen-Bin
Department of Electrical Engineering, National Formosa University, Yunlin County 632, Taiwan.
Sensors (Basel). 2016 Sep 7;16(9):1440. doi: 10.3390/s16091440.
Chromatic dispersion from optical fiber is the most important problem that produces temporal skews and destroys the rectangular structure of code patterns in the spectra-amplitude-coding-based optical code-division multiple-access (SAC-OCDMA) system. Thus, the balance detection scheme does not work perfectly to cancel multiple access interference (MAI) and the system performance will be degraded. Orthogonal frequency-division multiplexing (OFDM) is the fastest developing technology in the academic and industrial fields of wireless transmission. In this study, the radio-over-fiber system is realized by integrating OFDM and OCDMA via polarization multiplexing scheme. The electronic dispersion compensation (EDC) equalizer element of OFDM integrated with the dispersion compensation fiber (DCF) is used in the proposed radio-over-fiber (RoF) system, which can efficiently suppress the chromatic dispersion influence in long-haul transmitted distance. A set of length differences for 10 km-long single-mode fiber (SMF) and 4 km-long DCF is to verify the compensation scheme by relative equalizer algorithms and constellation diagrams. In the simulation result, the proposed dispersion mechanism successfully compensates the dispersion from SMF and the system performance with dispersion equalizer is highly improved.
光纤中的色散是基于光谱幅度编码的光码分多址接入（SAC - OCDMA）系统中产生时间偏移并破坏码型矩形结构的最重要问题。因此，平衡检测方案无法完美消除多址干扰（MAI），系统性能将会下降。正交频分复用（OFDM）是无线传输学术和工业领域中发展最快的技术。在本研究中，通过偏振复用方案将OFDM和OCDMA集成来实现光纤无线系统。所提出的光纤无线（RoF）系统使用了与色散补偿光纤（DCF）集成的OFDM的电子色散补偿（EDC）均衡器元件，它能够有效抑制长距离传输中的色散影响。使用一组10 km长的单模光纤（SMF）和4 km长的DCF的长度差，通过相关均衡器算法和星座图来验证补偿方案。在仿真结果中，所提出的色散机制成功补偿了来自SMF的色散，并且使用色散均衡器后的系统性能得到了显著提高。
