An improved least squares channel estimation algorithm for coherent optical FBMC/OQAM system

Abstract

In this paper we propose an improved least squares (LS) based channel estimator for 60 Gbps optical filter bank multicarrier with off-set quadrature amplitude modulation (FBMC/OQAM) system by employing an interference suppression technique based on discrete Fourier transform (DFT). The interference approximation method (IAM) is used to combat the inherent intrinsic interference in FBMC/OQAM system, however, residual intrinsic interference still exists in the system and it has significant impact to the LS channel estimator. The proposed technique suppresses the residual intrinsic interference and channel noise effects in the estimated optical channel impulse response by adaptive optimal channel energy criterion. Simulation results show that, the improved channel estimator is capable of estimating the channel that includes attenuation and chromatic dispersion, and suppressing the residual intrinsic interference and channel noise more effectively than the conventional LS-based channel estimator. The proposed approach is an appropriate alternative for optical FBMC/OQAM system with good trade-off between complexity and performance.