Channel Estimation Using Orthogonal Transformation in Spatially-Correlated Multi-antenna OFDM Systems

In this paper, we consider channel estimation for the reception of OFDM signal in spatially correlated multi-antenna environments. To improve the accuracy of channel estimation, we exploit the characteristics in three dimensions; time, frequency and spatial domain. The channel information is first estimated from pilot signal by means of a conventional least squared method in the frequency domain. Then the estimated signal is transformed into the time domain by means of inverse discrete Fourier transform (DFT) and further transformed into the spatial domain by exploiting the spatial covariance matrix of the channel. To reduce the effect of channel noise on the estimation performance, we only utilize signal components having enough power strength for the channel estimation to minimize the mean squared error. Finally, the analytic results are verified by computer simulation. Numerical results show that the proposed channel estimation scheme is quite effective in spatially correlated environments.