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Basis expansion model based spectral efficient channel estimation scheme for massive MIMO systems

In this paper, a spectral efficient channel estimation scheme is proposed for spatial-correlated sparse massive multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with superimposed time-frequency training sequences (TSs) based on basis expansion model (BEM). This scheme first relies on the identical time-domain TS to acquire the partial channel common support, based on which the frequency-domain TSs inserted into the OFDM block are then utilized for accurate channel state information (CSI) acquisition. Besides, the superimposed TSs are adopted to reduce the TS overhead. Meanwhile, by exploiting the spatial correlations of massive MIMO channels, BEM can be utilized to reduce the number of the frequency-domain TSs and improve the spectral efficiency drastically from 22% to 95%. Simulation results show that the proposed scheme with 200 frequency-domain TSs can achieve almost the same performance as the conventional approach with 3200 frequency-domain TSs in massive MIMO systems with 256 transmit antennas.