Energy Efficient Multi-User MISO Communication using Low Resolution Large Intelligent Surfaces

TL;DR

This paper explores the use of low-resolution Large Intelligent Surfaces (LIS) to enhance energy efficiency in multi-user MISO systems, demonstrating significant gains even with 1-bit resolution elements.

Contribution

It introduces a novel design for LIS-assisted multi-user MISO systems that optimizes energy efficiency using low-resolution surface elements.

Findings

LIS with 1-bit resolution elements significantly improves energy efficiency.

Joint optimization of transmit power and surface parameters enhances system EE.

Simulation results confirm EE gains over traditional relay systems.

Abstract

We consider a multi-user Multiple-Input Single-Output (MISO) communication system comprising of a multi-antenna base station communicating in the downlink simultaneously with multiple single-antenna mobile users. This communication is assumed to be assisted by a Large Intelligent Surface (LIS) that consists of many nearly passive antenna elements, whose parameters can be tuned according to desired objectives. The latest design advances on these surfaces suggest cheap elements effectively acting as low resolution (even $1$-bit resolution) phase shifters, whose joint configuration affects the electromagnetic behavior of the wireless propagation channel. In this paper, we investigate the suitability of LIS for green communications in terms of Energy Efficiency (EE), which is expressed as the number of bits per Joule. In particular, for the considered multi-user MISO system, we design the transmit powers per user and the values for the surface elements that jointly maximize the system's EE performance. Our representative simulation results show that LIS-assisted communication, even with nearly passive $1$-bit resolution antenna elements, provides significant EE gains compared to conventional relay-assisted communication.