Large Intelligent Surface-Assisted Wireless Communication Exploiting Statistical CSI

TLDR

Large intelligent surfaces (LIS) enable low‑cost, wall‑mounted reflectors that can steer signals by phase control, providing supplementary links for wireless systems. This study evaluates LIS‑assisted large‑scale antenna systems by deriving a tight upper bound on ergodic spectral efficiency and proposing an optimal phase‑shift design based on that bound and statistical CSI. The authors also determine the minimum quantization bits required for the LIS to keep spectral‑efficiency loss within acceptable limits. Numerical results confirm that the proposed design attains maximum ergodic spectral efficiency and that a 2‑bit quantizer limits degradation to no more than 1 bit/s/Hz.

Abstract

Large intelligent surface (LIS)-assisted wireless communications have drawn attention worldwide. With the use of low-cost LIS on building walls, signals can be reflected by the LIS and sent out along desired directions by controlling its phases, thereby providing supplementary links for wireless communication systems. In this paper, we evaluate the performance of an LIS-assisted large-scale antenna system by formulating a tight upper bound of the ergodic spectral efficiency and investigate the effect of the phase shifts on the ergodic spectral efficiency in different propagation scenarios. In particular, we propose an optimal phase shift design based on the upper bound of the ergodic spectral efficiency and statistical channel state information. Furthermore, we derive the requirement on the quantization bits of the LIS to promise an acceptable spectral efficiency degradation. Numerical results show that using the proposed phase shift design can achieve the maximum ergodic spectral efficiency, and a 2-bit quantizer is sufficient to ensure spectral efficiency degradation of no more than 1 bit/s/Hz.