Semi-blind channel estimation in MIMO-OFDM systems without guard interval and virtual carriers

Multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems use multiple antennas both at the transmitter and the receiver, which can increase the channel capacity and provide high data rate, but coherent signal detection requires reliable estimation of channel impulse responses between transmit and receive antennas. A semi-blind algorithm based on the noise subspace method for the channel estimator in MIMO-OFDM systems is investigated. The algorithm is different with the reported subspace methods, which need the guard interval or virtual carriers. The idea is to take advantage of the signal redundancy of receiver diversity and noise space characteristics and make it possible to accomplish the estimation without using cyclic prefix and virtual carriers, thereby improves the channel utilization. For MIMO-OFDM systems with Cyclic prefix (CP) or Virtual carriers (VCs), the proposed method provides additional performance gain to the existing blind channel estimation methods. Results of the numerical simulations are provided to illustrate the effectiveness of the proposed method.