  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.
