Channel-power profile estimation for orthogonal frequency-division multiplexing systems

In this work, a channel-power profile estimation for orthogonal frequency-division multiplexing systems, based on the cyclic prefix (CP), is introduced. By knowing the delay of each path, the time-dispersion information can be derived. The proposed method, considering long intersymbol interference (ISI) fading channels, requires only the coarse symbol timing information. More specifically, quasi-stationary fading channels are considered. The basic contribution is to obtain the maximum-likelihood estimation of the correlation coefficient based on the CP. Subsequently, the relationship between the correlation coefficient and the channel-tap powers is explored. With the estimate of correlation coefficient, the least-square solution of the channel-tap powers can be determined. The proposed method is suitable for both short and long ISI channels. Furthermore, the Cramér-Rao lower bound of the channel-power profile estimation is analyzed, and simulations confirm the advantages of the proposed estimator.