Preamble Based Frequency Domain Channel Estimation Method for Optical OFDM/OQAM System

Orthogonal frequency division multiplexing (OFDM) combined with offset quadrature amplitude modulation (OQAM) have aroused wide interest for optical communication recently. For optical OFDM/OQAM systems, the intrinsic imaginary interference (IMI) seriously deteriorated the system performance. Channel estimation methods based on the using of interference approximation method have been proved effective in suppressing IMI. In this paper, the straight angle phase offset (SAPO) method, the right angle phase offset (RAPO) method, and the combined phase offset (CPO) method have been introduced to combat the IMI effect. As demonstrated in the Montel Carlo simulation results, the BER performance obtained by CPO outperforms the SAPO and the RAPO significantly both in linear channel and the nonlinear channel. This result is also applicable when the phase noise caused by laser linewidth is added to the system.