Blind channel estimation for MIMO-OFDM systems using virtual carriers

Multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems are attractive because of their large capacity and high data rate. The paper presents a blind channel estimation method for MIMO-OFDM systems with and without a cyclic prefix (CP) by using the presence of virtual carriers. The proposed method is based on the noise subspace method. In addition, we establish a sufficient condition for channels to be identifiable. The proposed algorithm can be applied to MIMO-OFDM systems with insufficient CP or no CP, thereby potentially increasing channel utilization. Furthermore, by using reduced CP or no CP, the proposed method can achieve lower computational complexity. We present simulation results demonstrating the performance of the proposed method via numerical experiments.