Channel Estimation for MIMO-OFDM Systems in the Case of Insufficient Guard Interval Length

This paper proposes a new channel estimation method for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems in the presence of intersymbol interference (ISI). The proposed method uses special training sequences (TS) mainly for two reasons. Firstly, to obtain a desirable crest-factor of the transmitted training signal. Secondly, to eliminate the influence of ISI on the channel estimation performance. By using the recommended training sequences, one can avoid the ill-conditioned least square (LS) problem. To illustrate the proposed method, we assume that the system does not use a guard interval (GI). Simulation results show that the proposed method outperforms conventional methods with respect to the mean square error (MSE) of the estimated channel by more than 20 dB if the signal-to-noise ratio (SNR) is high.