Optical wireless communications (OWC) in general
and resource allocation in OWC networks particularly have
gained lots of attention recently. In this work, we consider the
resource allocation problem of a visible light communication
downlink transmission system based on time division multiple
access with the objective of maximizing spectral efficiency (SE).
As for the operational conditions, we impose constraints on
the average optical intensity, the energy consumption and the
quality-of-service. To solve the non-convex problem, we transform
the objective function into a difference of concave functions by
solving a second order differential inequality. Then, we propose
a low-complexity algorithm to solve the resource allocation
problem. Finally, we show by simulations the SE performance
gains achieved by optimizing the power allocation over equal
power allocation in the considered system. Numerical results
show the SE gains achieved by using this solution.