A linearly interpolated blind ICI suppressionalgorithmfor CO-OFDM system

We propose a high-performance blind ICI suppression algorithm, LI-BL-ICI, for CO-OFDM system based on linear interpolation. In the proposed algorithm, the difference of averaged optical phase noise between sub-symbols are estimated blindly, which are then linearly interpolated to get a more accurate estimation of the optical phase noise. The carrier phase is partially recovered with the linearly interpolated sub-symbol phase noise estimation, by which the inter-carrier-interference (ICI) is suppressed blindly. After ICI suppression, the common phase error of the residual optical phase noise is compensated with only a few pilot subcarriers. We present the theoretical derivation of the proposed algorithm and investigate the performanceof the proposed algorithm in CO-OFDM systems for both back-to-back and 320 km fiber transmission scenarios through Monte-Carlo simulations. The numerical results show that the linear interpolation based algorithm can effectively mitigate the impact of optical phase noise, and offers a larger laser linewidth tolerance than that of the BL-ICI algorithm.Compared with BL-ICI, the proposed algorithm also supports an arbitrary number of sub-symbols and does not need any angle-related operations when obtaining the observation-based matrix. The simulation results also verify that there exists a moderate number of sub-symbols for the proposed algorithm to balance the performance and complexity. The proposed algorithm is of great importance for the application of CO-OFDM in optical access/metro networks with low-cost laser sources and high-order modulation formats.