Optimal LED placement in indoor VLC networks

In the upcoming 5G systems, the use of optical attocells will be largely exploited, with the aim of extending connectivity to multiple users while reducing coverage holes in indoor environments. The deployment of light emitting diodes (LEDs) should be well considered in order to use the optimal number of attocells to guarantee both illumination and connectivity, as a large and unnecessary number of attocells in a room is not useful and can cause interference among neighboring lighting cells. On the other hand, a low number of LEDs may not guarantee the whole illumination/data coverage, causing outage to users attempting to access the medium. In this paper, we investigate the problem of optimal LEDs placement in indoor environments, subject to constraints on illumination and outage based on user data rate. Two approaches are introduced, focusing on (i) the minimization of the number of LEDs to be used to provide required services and (ii) the maximization of the number of users to be served with a fixed number of LEDs, respectively. Numerical results are carried out in different room scenarios, which distinguish from the probability density function of users laying in such environments.