  In recent years, the demand for high speed wireless networking has increased
considerably due to the enormous number of devices connected to the Internet.
In this context, optical wireless communication (OWC) has received tremendous
interest in the context of next generation wireless networks where OWC offers a
huge unlicensed bandwidth using optical bands. OWC systems are directional and
can naturally provide multiple-input and multiple-output (MIMO) configurations
serving multiple users using a high number of transmitters in the indoor
environment to ensure coverage. Therefore, multiuser interference must be
managed efficiently to enhance the performance of OWC networks considering
different metrics. A transmission scheme referred to as blind interference
alignment (BIA) is proposed for OWC systems to maximize the multiplexing gain
without the need for channel state information (CSI) at the transmitters, which
is difficult to achieve in MIMO scenarios. However, standard BIA avoids the
need for CSI at the cost of requiring channel coherence time large enough for
transmitting the whole transmission block. Moreover, the methodology of BIA
results in increased noise with increase in the number of transmitters and
users. Therefore, various network topologies such as network centric (NC) and
user centric (UC) designs are proposed to relax the limitations of BIA where
these topologies divide the receiving area into multiple clusters. The results
show a significant enhancement in the performance of topological BIA compared
with standard BIA.
