Synergistic Benefits in IRS- and RS-enabled C-RAN with Energy-Efficient Clustering

TL;DR

This paper explores how combining intelligent reflecting surfaces and rate splitting in energy-efficient cloud radio access networks, with dynamic user clustering, significantly improves system performance and energy efficiency.

Contribution

It introduces dynamic RS and user clustering techniques that synergistically enhance energy efficiency in IRS- and RS-enabled C-RANs with practical fronthaul constraints.

Findings

Dynamic RS provides up to 88% gain over static schemes.

Synergistic effects observed between IRS and RS.

Energy efficiency improves drastically at the intersection of dynamic methods.

Abstract

The potential of intelligent reflecting surfaces (IRSs) is investigated as a promising technique for enhancing the energy efficiency of wireless networks. Specifically, the IRS enables passive beamsteering by employing many low-cost individually controllable reflect elements. The resulting change of the channel state, however, increases both, signal quality and interference at the users. To counteract this negative side effect, we employ rate splitting (RS), which inherently is able to mitigate the impact of interference. We facilitate practical implementation by considering a Cloud Radio Access Network (C-RAN) at the cost of finite fronthaul-link capacities, which necessitate the allocation of sensible user-centric clusters to ensure energy-efficient transmissions. Dynamic methods for RS and the user clustering are proposed to account for the interdependencies of the individual techniques. Numerical results show that the dynamic RS method establishes synergistic benefits between RS and the IRS. Additionally, the dynamic user clustering and the IRS cooperate synergistically, with a gain of up to 88% when compared to the static scheme. Interestingly, with an increasing fronthaul capacity, the gain of the dynamic user clustering decreases, while the gain of the dynamic RS method increases. Around the resulting intersection, both methods affect the system concurrently, improving the energy efficiency drastically.