  In this paper, we consider an indoor visible light communication (VLC) system
with multiple "white" light emitting diodes serving to form overlapping
wireless communication cells. In order to maintain seamless connectivity to
mobile users, a handover procedure should be implemented. In particular,
practical conditions such as blockages due to obstacles inside the room
environment and the mobility of users can affect direct VLC connectivity. The
use of reconfigurable intelligent surfaces (RISs) in optical wireless systems
allows to exploit non-direct connectivity links, thus providing efficient
communication links. In this paper, we present a proactive handover mechanism
that exploits the presence of a RIS, in order to redirect the communication
links in case of blockages. The proposed approach has been implemented both in
hard and soft modes and assessed in terms of achievable data rate and handover
latency for a user walking in a given reference room at different user speeds
and blockage conditions. Our presented results and comparisons with
conventional handover methods (i.e., without RIS) are helpful in showing the
superiority of the presented algorithm.
