  Can the smart radio environment paradigm measurably enhance the performance
of contemporary urban macrocells? In this study, we explore the impact of
reconfigurable intelligent surfaces (RISs) on a real-world sub-6 GHz MIMO
channel. A rooftop-mounted macrocell antenna has been adapted to enable
frequency domain channel measurements to be ascertained. A nature-inspired beam
search algorithm has been employed to maximize channel gain at user positions,
revealing a potential 50% increase in channel capacity in certain
circumstances. Analysis reveals, however, that the spatial characteristics of
the channel can be adversely affected through the introduction of a RIS in
these settings. The RIS prototype schematics, Gerber files, and source code
have been made available to aid in future experimental efforts of the wireless
research community.
