  The proliferation of connected devices and emergence of
internet-of-everything represent a major challenge for broadband wireless
networks. This requires a paradigm shift towards the development of innovative
technologies for next generation wireless systems. One of the key challenges is
the scarcity of spectrum, owing to the unprecedented broadband penetration rate
in recent years. A promising solution is the proposal of visible light
communications (VLC), which explores the unregulated visible light spectrum to
enable high-speed communications, in addition to efficient lighting. This
solution offers a wider bandwidth that can accommodate ubiquitous broadband
connectivity to indoor users and offload data traffic from cellular networks.
Although VLC is secure and able to overcome the shortcomings of RF systems, it
suffers from several limitations, e.g., limited modulation bandwidth. In this
respect, solutions have been proposed recently to overcome this limitation. In
particular, most common orthogonal and non-orthogonal multiple access
techniques initially proposed for RF systems, e.g., space-division multiple
access (SDMA) and NOMA, have been considered in the context of VLC. In spite of
their promising gains, the performance of these techniques is somewhat limited.
Consequently, in this article a new and generalized multiple access technique,
called rate-splitting multiple access (RSMA), is introduced and investigated
for the first time in VLC networks. We first provide an overview of the key
multiple access technologies used in VLC systems. Then, we propose the first
comprehensive approach to the integration of RSMA with VLC systems. In our
proposed framework, SINR expressions are derived and used to evaluate the
weighted sum rate (WSR) of a two-user scenario. Our results illustrate the
flexibility of RSMA in generalizing NOMA and SDMA, and its WSR superiority in
the VLC context.
