  Reconfigurable Intelligent Surfaces (RISs) constitute the key enabler for
programmable electromagnetic propagation environments, and are lately being
considered as a candidate physical-layer technology for the demanding
connectivity, reliability, localization, and sustainability requirements of
next generation wireless networks. In this paper, we first present the
deployment scenarios for RIS-enabled smart wireless environments that have been
recently designed within the ongoing European Union Horizon 2020 RISE-6G
project, as well as a network architecture integrating RISs with existing
standardized interfaces. We identify various RIS deployment strategies and
sketch the core architectural requirements in terms of RIS control and
signaling, depending on the RIS hardware architectures and respective
capabilities. Furthermore, we introduce and discuss, with the aid of
simulations and reflectarray measurements, two novel metrics that emerge in the
context of RIS-empowered wireless systems: the RIS bandwidth and area of
influence. Their extensive investigation corroborates the need for careful
deployment and planning of the RIS technology in future networks.
