Comparison of channel frequency and impulse response estimation for space-time coded OFDM systems

Accurate channel state information (CSI) is required at the receiver in a space-time coded OFDM system. In this paper, two channel estimation methods based on least squares (LS) criteria for space-time coded OFDM systems are studied and compared in detail. The channel frequency response estimator uses training sequences that rely on real orthogonal designs for acquisition, while the channel impulse response estimator exploits space-time coded sequence for both acquisition and tracking modes. Computer simulations show that both estimators work well in a Rayleigh flat-fading channel. The performance of the estimators is similar in the acquisition mode if the correlation between the subcarriers is taken into account similarly in both cases.