Low rank channel estimation for space-time coded wideband OFDM systems

To provide high-speed data transmission for the next generation wireless communication systems employing multiple transmit antennas, a space-time coded orthogonal frequency division multiplexing (OFDM) system has previously been proposed as a promising and efficient approach with both transmit diversity and high coding gains. In this paper, we study the channel estimation for spacetime coded OFDM using least squares (LS) and minimum mean-squared error (MMSE) criteria. In particular, the MSE bounds are given for the temporal channel estimations. By assuming that the channel frequency response is quasi-static over two consecutive OFDM symbols, a low rank Wiener filter based channel estimator is proposed. This significantly reduces the computation complexity while retaining accurate frequency domain channel estimation. Numerical results are provided to demonstrate the performance of the low-rank frequency-domain channel estimation for space-time coded OFDM systems.