Joint carrier frequency offset, sampling time offset and channel estimation in multiuser OFDM/OQAM systems

摘要

A derivative of orthogonal frequency division multiplexing (OFDM) based on offset quadrature amplitude modulation, OFDM/OQAM, is among the waveform contenders for future wireless networks. Focusing on multiuser scenarios, i.e. uplink of a multiple access system, we propose an improved joint estimation method for carrier frequency offset, sampling time offset and channel impulse response needed for the practical application of OFDM/OQAM. The proposed method offers a pilot-based maximum-likelihood (ML) estimation of the unknown parameters in multiuser OFDM/OQAM systems. Formulation of the estimator is based on the splitting of each received pilot symbol into contributions from surrounding pilot symbols, non-pilot symbols, additive noise and multiuser interference. The proposed estimator is compared with a highly cited previous work of the same focus where the improvements in the results indicate the superiority of the former.