Blind symbol timing, frequency offset and carrier phase estimation in OFDM systems

Abstract

This paper deals with the problem of joint symbol timing, frequency offset and carrier phase estimation in orthogonal frequency division multiplexing (OFDM) systems with noncircular transmissions. In this case, for a sufficiently large number of subcarriers, the OFDM signal results to be an improper complex Gaussian process since its pseudoautocorrelation function is different from zero. By exploiting the joint probability density function for improper complex Gaussian processes, maximum-likelihood (ML) estimators for the parameters of interest are derived, and moreover, their performance is compared with that of previously proposed ML estimators for proper complex Gaussian processes.