Wideband Hybrid Precoding with Angular Spread for THz Massive MIMO

THz (Terahertz) wideband hybrid precoding is important technology for enable TeraBits Per Second (Tbps) transmission in 6G mMIMO systems.In spite of the rich spectrum resources, a strict beam-split effect will be induced in THz mMIMO systems, corrupting the system capacity.The existing THz wideband precoder scheme generally centre of attention on overcome the beam-split effect in LOS (line-of-sight) scenario but cannot manage with the beam-split effect in NLOS(Non-LOS) scenario in the occurrence of angular spread.To solve the issue, first analyze and comparing the difference in the beam split effect in NLOS and LOS scenario.Next, in both LOS and Non-LOS cases, a delay-time joint optimization approach is suggested to reduce the beam-split impact.Lastly, simulations were run to confirm the suggested method's efficacy.We first compare beam splitting behavior in the radius and cluster models, demonstrating that the cluster model introduces greater complexity and significantly degrades the performance of conventional precoding schemes.To address this, we propose a joint timing and phase optimization algorithm that approximates the theoretically optimal unconstrained wideband precoding.This is achieved by jointly optimizing the digital precoding matrix, phase shift matrix, and delay matrix to better align with the cluster-based channel characteristics.Simulation results show that the proposed method improves the achievable rate and significantly reduces the array gain loss caused by beam splitting.The performance improvement is most notable under the cluster model, where traditional methods struggle.