Design and development of a wireless colour-based optical modulation system

In visible light communication(VLC),arrays consisting of a single or multi-colour light sources are employed for a dual purpose being: the provision of illumination and data transmission. Therefore, it is substantial to come up with efficient techniques for resource allocation. The aim of this thesis is to design and develop a multi-user colour-based optical spatial modulation VLC framework using a line-of-sight (LoS) model. An optimisation problem with the intention of minimising the total luminous intensities of the light emitting diode (LED) arrays subject to the transmitting LED array’s optical power budget, minimum required illuminance level, LED-user channel conditions and latency intolerant users’ (LITUs) quality-of-service (QoS) target constraints is proposed. With the adaptation of spatial modulation and convex optimisation, the design and development of a colour-based algorithm is carried out. Firstly, a coordinated algorithm for the selection of a transmitting array, maintenance of a particular illuminance and signal-to-interference-plus noise ratio (SINR) levels during symbol transmission is designed. Secondly, through computer simulations, a numerical analysis is carried out to demonstrate and evaluate the performance of the algorithm. The proposed scheme is capable of satisfying the user required SINR target for LITUs while reducing the optical power by approximately 20% to 25% during the transmission of symbols. Additionally, the system can provide adequate illuminance as per the users’ requirement at all areas where users are located while there is low illuminance ranging from 100 lux to 250 lux at any other location. The proposed algorithm is capable of satisfying the user’s required illuminance provided it is specified within the standardised levels of 300 lux to1500 lux. Furthermore, the algorithm can meet the SINR targets for the LITUs while minimising the optical power of the LED arrays. However, fair SINR levels for the latency tolerant users(LTUs) are not guaranteed. The proposed system is able to achieve data rates of 5Mbps to 25Mbps using commercially-off-the-shelf LEDs.