Highly Efficient Sparse Multipath Channel Estimator with Optimal Chu-sequence Premable for MIMO Frequency-Domain DFE Receiver

In this paper, a multiple input multiple output (MIMO) channel estimation scheme is proposed with both high accuracy and computational efficiency for sparse multipath channel. This algorithm exploits the optimal MIMO preamble based on repeated phase-rotated Chu sequences, and iteratively estimates the number and positions of the sparsely spaced multipath components by using the generalized AIC criterion (GAIC). In the light of the orthogonality of the Chu sequence, an efficient and order-recursive least squares channel update in frequency domain is derived. This scheme is simulated for 802.16d SCa-PHY and SUI-5 sparse channel model under a 2times2 spatial multiplexing scenario, with the MIMO frequency domain DFE as the receiver. The result shows that the channel estimation accuracy is significantly improved, and a performance loss of only 0.7-dB is incurred at the BER of 10^-3, as compared to the case of perfect channel knowledge