Hybrid Precoding and Combining for Millimeter Wave/Sub-THz MIMO-OFDM Systems with Beam Squint Effects

In this paper, we consider the problem of hybrid precoding and combining for wideband millimeter wave (mmWave) and sub-terahertz (THz) MIMO-OFDM systems with beam squint effects. In the presence of the beam squint effect, the conventional spatially sparse precoding-based hybrid precoding method which approximates the optimal precoder/combiner with a set of array response vectors suffers severe performance degradation. To address this difficulty, we propose a new set of basis vectors to approximate the optimal precoder/combiner. Each new basis vector is devised to form a radiation pattern with a wide beam to cover the squinted beam directions caused by different frequencies. Simulation results show that the proposed method can effectively alleviate the beam squint effect and achieve a substantial performance improvement over the existing state-of-the-art hybrid precoding method.