Pilot Power Optimization Based Channel Estimation Method for Optical OFDM/OQAM

Orthogonal frequency division multiplexing (OFDM) combined with offset quadrature amplitude modulation (OQAM) have become the hot research topic recently. OFDM/OQAM utilizes the specially designed filter bank with promising time-frequency localization (TFL) property to overcome inter-symbol-interference (ISI). However, the orthogonal condition for OFDM/OQAM only holds in the real field. Optical OFDM/OQAM systems faced with serious intrinsic imaginary interference (IMI) effect induced by chromatic dispersion (CD) and polarization mode dispersion (PMD), which decreased the transmission performance significantly. In this paper, we proposed a pilot power optimization based channel estimation method to improve the system robustness against IMI effect for optical OFDM/OQAM systems. The general pilot design criterion has been proposed in this paper, and numerous pilot structures reported in previous publications have been compared with the proposed method. As demonstrated in the simulation results, the pseudo pilot structures satisfying the proposed structure could obtain optimal pseudo pilot power, which could improve the system robustness against IMI effect and amplified spontaneous emission (ASE) evidently.