  The main limitation of visible light communication (VLC) is the narrow
modulation bandwidth, which reduces the achievable data rates. In this paper,
we apply the non-orthogonal multiple access (NOMA) scheme to enhance the
achievable throughput in high-rate VLC downlink networks. We first propose a
novel gain ratio power allocation (GRPA) strategy that takes into account the
users' channel conditions to ensure efficient and fair power allocation. Our
results indicate that GRPA significantly enhances system performance compared
to the static power allocation. We also study the effect of tuning the
transmission angles of the light emitting diodes (LEDs) and the field of views
(FOVs) of the receivers, and demonstrate that these parameters can offer new
degrees of freedom to boost NOMA performance. Simulation results reveal that
NOMA is a promising multiple access scheme for the downlink of VLC networks.
