A Novel CSI-RS Reporting Scheme for RIS Optimization in O-RAN-based NextG Networks

TL;DR

This paper introduces an efficient CSI-RS reporting scheme for RIS in O-RAN networks, validated through real-world experiments, enabling improved signal power and practical RIS optimization.

Contribution

It proposes a novel CSI-RS based reporting framework for RIS in O-RAN, including extraction and reporting procedures, validated on a real testbed.

Findings

Enhanced received signal power for near and far users.

Effective integration of RIS optimization algorithms into O-RAN.

Practical validation on a real-world testbed.

Abstract

Reconfigurable intelligent surface (RIS) technology is a promising enabler for next-generation (NextG) wireless systems, capable of dynamically shaping the propagation environment. Integrating RIS within the open radio access network (O-RAN) architecture enables flexible and intelligent control of wireless links. However, practical RIS-assisted operation requires efficient acquisition and reporting of channel state information (CSI) to support real-time control from the base station side. This paper proposes a CSI reference signal (CSI-RS)-based reporting scheme for downlink complex channel information (CCI) to facilitate RIS optimization in an O-RAN-compliant environment. The proposed framework establishing CCI extraction and CSI-RS reporting procedures is experimentally validated on a real-world testbed integrating an open-source O-RAN system with an RIS prototype operating in the n78 frequency band. Existing channel estimation-based RIS optimization algorithms, including Hadamard and orthogonal matching pursuit (OMP), are tailored for integration into the O-RAN architecture. Experimental results demonstrate notable improvements in received signal power for both near and far users, highlighting the effectiveness and practical viability of the proposed scheme.