Near Optimal Hybrid Digital-Analog Beamforming for Point-to-Point MIMO-OTFS Transmissions

In this paper, an orthogonal time frequency space modulation-based point-to-point multiple-input multiple-output (MIMO-OTFS) transmission is devised. Specifically, we propose a low-complexity hybrid digital-analog beamforming (HBF) scheme for MIMO-OTFS transmissions, in which symbols can be transmitted in an interference-free manner. In particular, the designed HBF scheme exploits the delay-Doppler (DD) domain path separability, which gives rise to a low-complexity DD domain precoding that can obtain a near-optimal rate performance facilitated by a path-wise power allocation. Simulation results demonstrate that the proposed HBF scheme achieves near-optimal rate and improved error performance in comparison to the singular value decomposition (SVD) precoding benchmark.