Interference Exploitation Precoding for Intelligent Reflecting Surface Aided Communication System

In this letter, we propose a novel precoding design for a multi-user multi-input-single-output (MU-MISO) communication system with the assistance of an intelligent reflecting surface (IRS). By jointly designing the precoder at the base station (BS) and the phase shift matrix at the IRS, we exploit the constructive effect of the multi-user interference (MUI) to improve the performance of the communication system. While the objective function and constraints of the problem are both non-convex, an alternating optimization (AO) based algorithm with two different solvers is proposed. This algorithm is guaranteed to converge to at least locally optimal solution. Simulations show that by applying the proposed symbol level precoding technique, the communication performance can be significantly enhanced compared with the existing linear precoding method, at the price of slightly increased computational overhead.