Blind frequency-offset estimation for OFDM-OQAM systems

This paper deals with the problem of blind carrier-frequency offset (CFO) estimation in orthogonal frequency- division multiplexing (OFDM) systems based on offset quadrature amplitude modulation (OFDM/OQAM). Specifically, by assuming that the number of subcarriers is sufficiently large,the received signal is modeled as a complex Gaussian random vector (CGRV). Since the OFDM/OQAM signal results to be a noncircular (NC) process (i.e., its relation function is different from zero), by exploiting the generalized probability density function for NC-CGRVs, the unconditional maximum-likelihood algorithm for CFO estimation in nondispersive channel is derived. Moreover, due to its computational complexity, a more feasible estimator is considered. The performance of the proposed estimators, assessed via computer simulation, is compared with that of recently proposed CFO estimators exploiting second-order cyclostationarity and with the Gaussian Cramér–Rao bound.