ML frequency offset and carrier phase estimation in OFDM systems with noncircular transmissions

In this paper the problem of blind frequency offset and carrier phase estimation in orthogonal frequency-division multiplexing (OFDM) systems with noncircular transmissions is considered. In this case, if the number of subcarriers is sufficiently large, the OFDM signal becomes an improper complex Gaussian process. By exploiting the joint probability density function for improper (or noncircular) complex Gaussian random vectors maximum likelihood estimators for the parameters of interest are derived, and moreover, the Cramér-Rao lower bound is evaluated.