Hybrid Transceiver Design and Sparse CSI Learning in MU THz Hybrid MIMO systems

This paper conceives a new generalized simultane-ous orthogonal matching pursuit (GSOMP)-based algorithm to effectively estimate the sparse channel state information (CSI) in a multiuser (MU) THz hybrid MIMO system. The proposed framework also incorporates low-resolution analog-to-digital converters (ADCs) together with a sampled version of the transmit pulse shaping filter. The proposed techniques are based on a practical dual-wideband THz channel model that is developed initially, which considers both the spatial and frequency wide-band effects. The model also embraces the reflection, absorption and free-spaces losses that are a characteristic feature of the THz band. Subsequently, a novel MU hybrid transceiver design framework is advanced, based on the generalized alternating direction method of multipliers (MU-GADMM), which generates a new set of basis vectors toward robust approximation of the optimal precoder, in order to account for the beamsquint effect. Extensive simulations are conducted to evaluate the performance of the proposed CSI learning and beamforming techniques in a practical THz channel generated using the high-resolution transmission (HITRAN) database.