Spectral Efficiency in Large Intelligent Surfaces: Asymptotic Analysis under Pilot Contamination

Large intelligent surfaces (LISs) have emerged as a new and promising wireless communication paradigm that relies on equipping man-made structures such as walls with a massive number of antennas. However, despite their potential benefits, a fundamental analysis on the performance limits of LIS systems is lacking. In this paper, the system spectral efficiency (SSE) of an uplink LIS system is asymptotically analyzed under a practical frame structure and LIS environment. In order to quantify the impact on the SSE of pilot contamination, the SSE of a multi-LIS system is asymptotically studied and a theoretical bound on its performance is derived. Simulation results show that the derived analyses are in close agreement with the exact mutual information in presence of a large number of antennas. Moreover, the results show that the achievable SSE is limited by the effect of pilot contamination and intra/inter-LIS interference through the line-of-sight path, even if the LIS is equipped with an infinite number of antennas.