A Novel Transceiver Design with Low-Overhead Pilot Pattern and Low-Complexity Channel Estimation in MIMO-OTFS Systems

Multiple-input multiple-output orthogonal time frequency space (MIMO-OTFS) systems have gained increasing attention due to their superior performance in double-selective channel scenarios. However, MIMO-OTFS systems typically suffer from high pilot overhead and complex channel estimation (CE) when the number of antennas is large. To tackle these issues, in this paper, we propose a novel transceiver design, consisting of a new transceiver architecture, a low-overhead pilot pattern, and the corresponding low-complexity CE algorithm. Specifically, firstly, we apply the Inverse Discrete Fourier Transformation (IDFT) module at the transmitter (TX) and the corresponding Discrete Fourier Transformation (DFT) module at the receiver (RX), by resorting to which the received signals can be separated effectively in the time-delay-angular (TDA) domain to greatly reduce the inter-path and inter-antenna interferences. Secondly, at the TX, we design a new pilot pattern that removes the guard region and the length of which does not increase with the number of transmit antennas (TAs), leading to significantly reduced pilot overhead and increased spectral efficiency. Thirdly, at the RX, we utilize the three-dimensional (3D) sparsity of the MIMO-OTFS channel in the delay-Doppler-angular (DDA) domain to correspondingly achieve a low-complexity CE algorithm. Extensive numerical results demonstrate the effectiveness of our proposed transceiver design.