Abstract: Channel estimation based on training sequences in the time domain for wireless MIMO OFDM is proposed. The training sequences are modulatable orthogonal polyphase sequences. The time domain periodic autocorrelation of the sequence emanated from all the transmit antennas is completely ideal. The absolute value of the cross-correlation function between any two modulatabale sequences is constant and satisfies the mathematical lower bound. The multi-channel estimator relies on correlation between the received training sequences and the locally generated training sequences. The advantages of the proposed method, over existing alternatives, are low complexity and the ability to track the time-varying channel. Simulation results show satisfactory performance even at a low SNR.

Key words: orthogonal frequency division multiplexing (OFDM), multiple-input multiple-output(MIMO), channel estimation, modulatable orthogonal polyphase sequences