  Software-defined metasurfaces are electromagnetically ultra-thin, artificial
components that can provide engineered and externally controllable
functionalities. The control over these functionalities is enabled by the
metasurface tunability, which is implemented by embedded electronic circuits
that modify locally the surface resistance and reactance. Integrating
controllers within the metasurface cells, able to intercommunicate and
adaptively reconfigure it, thus imparting a desired electromagnetic operation,
opens the path towards the creation of an artificially intelligent (AI) fabric
where each unit cell can have its own sensing, programmable computing, and
actuation facilities. In this work we take a crucial step towards bringing the
AI metasurface technology to emerging applications, in particular exploring the
wireless mm-wave intercell communication capabilities in a software-defined
HyperSurface designed for operation is the microwave regime. We examine three
different wireless communication channels within the landscape of the
reflective metasurface: Firstly, in the layer where the control electronics of
the HyperSurface lie, secondly inside a dedicated layer enclosed between two
metallic plates, and, thirdly, inside the metasurface itself. For each case we
examine the physical implementation of the mm-wave transponder nodes, we
quantify communication channel metrics, and we identify complexity vs.
performance trade-offs.
