  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 study, we evaluate the performance of an
LIS-assisted large-scale antenna system by formulating a tight approximation of
the ergodic capacity and investigate the effect of the phase shifts on the
ergodic capacity in different propagation scenarios. In particular, we propose
an optimal phase shift design based on the ergodic capacity approximation and
statistical channel state information. Furthermore, we derive the requirement
on the quantization bits of the LIS to promise an acceptable capacity
degradation. Numerical results show that using the proposed phase shift design
can achieve the maximum ergodic capacity, and a 2-bit quantizer is sufficient
to ensure capacity degradation of no more than 1 bit/s/Hz.
