  High reliability and availability of communication services is a key
requirement that needs to be ensured by service providers. Since the direct
line-of-sight (LOS) beam is prone to blockage in indoor optical wireless
communication systems, a backup link needs to be at hand in case of blockage,
and hence channel allocation algorithms should be blockage-aware. In this
paper, the impact of beam blockage due to a disc with varying size and distance
from the receiver is studied where blockage is quantitatively evaluated using
percentage blockage for 512 room locations at 25 cm separation. It was found
that assigning two links with maximum separation between the serving access
points can reduce or eliminate blockage compared to the case when resilience is
not implemented. Increasing the number of allocated access points per user
further increases resilience.
