Joint Maximum Likelihood Estimation of Carrier Frequency Offsets and Channels in OFDM Systems

A joint estimation method of carrier frequency offset and frequency selective channel response in orthogonal frequency division multiplexing (OFDM) systems is presented in this paper based on the maximum likelihood (ML) criterion. The signal model is introduced and a joint estimator is derived. The proposed algorithm can be divided into two major portions. The first part use the rotation concept to estimate the initial Carrier Frequecy Offset (CFO) and design the time domain equalizer. The second part make use of iterative concept to find the true frequency peak for better estimate. The proposed scheme does not require initial random guess as regular iterative algorithms, in which may suffer from the problem of the convergence to the local maximum. The proposed approach can surely converge to the global maximum for achieving the solution. The computation complexity is much less than the grid-search method and easily be implemented in hardware. The MSE performance of the proposed algorithm is close to the Cramer-Rao Lower bound which is shown in the simulation result.