长途传输系统中使用改进的DFT窗口去改善长途传输系统的色散容限

长途传输系统中使用改进的DFT窗口去改善长途传输系统的色散容限的相干光OFDM系统(中文5000字,英文4000字)
论文摘要我们提出了使用改进的DFT窗口来改善超长距离传输系统的色散容限的相干光OFDM系统。仿真结果表明，与传统的相干光OFDM系统相比，该系统可以大大提高色散容限。
介绍
相干光正交频分复用（CO-OFDM）已成为需要高速、大容量和长距离传输性能的下一代光网络的有吸引力的技术[1]。最近，CO-OFDM系统由于其诸如高光谱效率和优异的色散耐受性等许多优点而得到了积极的研究。尽管与单载波光传输系统相比，CO-OFDM系统对色散效应具有鲁棒性，但是CO-OFDM系统的传输性能仍然受到超长距离传输系统中的色散的限制。如果信道长度超过循环扩展，则发生符号间干扰（ISI）和载波间干扰（ICI），这降低了CO-OFDM系统的传输性能[2]。为了克服这个问题，方便的技术是使用更长的循环扩展（CE）长度，这可以通过增加CE的比率或使用更大的FFT规模来实现，其中CE的比率是固定的。然而，增加CE的比率会降低频谱效率。此外，使用更大尺寸的FFT也有一些缺点;（1）如果采用更大尺寸的FFT，峰值平均功率比（PAPR）会增加。（2）使用更长的FFT表示符号持续时间增加。长符号持续时间会对激光相位噪声产生更大的灵敏度，从而导致常见的相位误差和ICI，并降低传输性能。在这封信中，我们提出了使用改进的DFT窗口（MDW-CO-OFDM）来改善色散容限的CO-OFDM系统。为了克服由色散引起的ICI和ISI损伤，我们在接收器处采用了两个改进的DFT窗口。使用两个经过修改的DFT窗口，可以最小化ISI和ICI，而无需进行诸如频谱效率和增大FFT大小之类的折衷。
Coherent optical OFDM system using modified DFT windows to improve chromatic dispersion tolerance for long-haul transmission system
Paper Summary
We propose a coherent optical OFDM system using
modified DFT windows to improve dispersion tolerance for ultra-long-haul transmission systems. Simulation results show that the proposed system can greatly enhance the dispersion tolerance compared with the conventional coherent optical OFDM system.
Introduction
Coherent optical orthogonal frequency division multiplexing (CO-OFDM) has been becoming an attractive technology for next-generation optical networks that require high speed, large capacity, and long-haul transmission [1]. Recently, the CO-OFDM system has been actively investigated owing to its many advantages such as high spectral efficiency and superior tolerance to dispersion. However, although the CO- OFDM system has robustness to the dispersion effect compared with a single carrier optical transmission system, the transmission performance of the CO-OFDM system is still limited by chromatic dispersion in ultra- long-haul transmission systems. If the channel length exceeds the cyclic extension, the inter-symbol interference (ISI) and inter-carrier interference (ICI) is occurred, which degrades transmission performances of the CO-OFDM system [2]. To overcome this problem, the convenient technique is using longer cyclic extension (CE) length, which can be realized by increasing the ratio of CE or using larger FFT size where the ratio of CE is fixed. However, increasing the ratio of CE reduces the spectral efficiency. In addition, using larger size of FFT has also some disadvantages; (1) the peak-to-