Semi-Blind Multiuser Detection Under the Presence of Reconfigurable Intelligent Surfaces

TL;DR

This paper analytically investigates a multiuser MIMO system aided by a reconfigurable intelligent surface, deriving outage performance and exploring the impact of channel information and array size on system efficiency and complexity.

Contribution

It provides a novel analytical framework for outage performance in RIS-assisted multiuser MIMO systems with zero-forcing detection and joint coherent/noncoherent schemes.

Findings

Outage performance expressions derived for various configurations.

Channel state information significantly affects system performance.

Joint detection schemes improve efficiency and reduce complexity.

Abstract

A multiuser multiple-input multiple-output wireless communication system is analytically studied, which operates with the aid of a reconfigurable intelligent surface (RIS). The intermediate RIS is equipped with multiple elements and operates via random phase rotations to simultaneously serve multiple users. Independent Rayleigh fading conditions are assumed among the included channels. The system performance is analytically studied when the linear yet efficient zero-forcing detection is implemented at the receiver. In particular, the outage performance is derived in closed-form expression for different system configuration setups with regards to the available channel state information at the receiver. Further, a joint coherent/noncoherent linear detection is analytically presented. Finally, some new engineering insights are provided, such as how the channel state information and/or the volume of antenna/RIS arrays impact on the overall system performance as well as the arising efficiency on the performance/complexity tradeoff by utilizing the joint coherent/noncoherent scheme.