  Programmable wireless environments (PWEs) utilize electromagnetic
metasurfaces to transform wireless propagation into a software-controlled
resource. In this work we study the effects of user device mobility on the
efficiency of PWEs. An analytical model is proposed, which describes the
potential misalignment between user-emitted waves and the active PWE
configuration, and can constitute the basis for studying queuing problems in
PWEs. Subsequently, a novel, beam steering approach is proposed which can
effectively mitigate the misalignment effects. Ray-tracing-based simulations
evaluate the proposed scheme.
