Deterministic Pilot Design and Channel Estimation for Downlink Massive MIMO-OTFS Systems in Presence of the Fractional Doppler

Although the combination of orthogonal time frequency space (OTFS) modulation and massive multiple-input multiple-output (MIMO) technology can make communication systems perform better in high-mobility scenarios, there are still many challenges downlink channel estimation owing to inaccurate modeling high pilot overhead practical systems. In this paper, we propose a state information (CSI) acquisition scheme for MIMO-OTFS presence fractional Doppler, including deterministic design algorithm. First, analyze input-output relationship single-input single-output (SISO) OTFS based on division multiplexing (OFDM) modem extend it MIMO-OTFS. Moreover, formulate an accurate model system which Doppler is considered influence subpaths revealed. A then proposed structure matrix reduce save memory consumption. Since geometry changes very slowly relative timescale, put forward modified sensing (MSMCE) algorithm acquire CSI. Simulation results demonstrate that CSI has significant advantages over traditional algorithms.