Dissertation Defense - Muhammet Selim Demir (PHDEE)

There has been a growing interest on visible light communications (VLC) in recent years. The existing works in the literature on point-to-point VLC systems are well established and especially the studies on physical layer aspects demonstrate the potential of VLC. However, in order to transform VLC to a multi-user, multi-cell, scalable, and fully networked wireless technology significant further efforts on upper layer issues are needed. This dissertation focuses on mobility management and resource allocation techniques for indoor and vehicular VLC systems.

In the first part of this thesis, we consider a centralized direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) based VLC network and formulate a subcarrier resource allocation problem to maximize the user satisfaction index. For the solution of the resulting problem, we used the bio-inspired particle swarm optimization (PSO) method. In the second part of this thesis, we propose an energy-efficient dynamic resource management framework for indoor orthogonal frequency division multiplexing (OFDM) based VLC networks. Specifically, we formulate and investigate a stochastic cross-layer optimization problem to seemly optimize the network resources under the constraints of queue stability and power to maximize the average system throughput. In the last part of this thesis, we propose handover algorithms for indoor and outdoor VLC networks. First, we propose a handover algorithm for indoor VLC networks with coordinated multipoint (CoMP) transmission and evaluate its performance in physical channel settings based on ray tracing. Then, we present a dynamic soft handover algorithm for outdoor vehicular VLC networks.