Engineering HDR Seminar Series 41, 2013: Rate Adaptive Multi User Visible Light Communication For Indoor Spaces

Mr Dilukshan Ajith Karunatilaka, ECSE postgraduate student

Date: 2013-08-27
Time: 15:00 to 16:00
Venue: Engineering Meeting Room 1, 5-4-22


Visible light communication (VLC) utilizes the visible portion of the electromagnetic spectrum to transmit data. These systems combine illumination with communication by using Light Emitting Diodes (LEDs), and present an alternative to popular radio frequency communication (RFC) prevalent today. With growing user density in indoor spaces, it has become an important problem to adapt the time varying and location specific wireless channel and update the data rate accordingly.  Existing rate adaptation works are mainly in the Radio Frequency domain, and used widely in communication networks today. However, there is little work done in this field of Optical wireless systems, and no works on VLC. Rate adaptation is important feature in wireless systems, as it is a means of increasing link stability and maintaining quality of service with altering channel conditions due to factors such as shadowing and fading. This project will investigate rate adaptation for VLC, and incorporate methods for larger and uniform signal coverage in indoor spaces.  Typically, rate adaptation in radio frequency networks utilize frame and Signal to Noise Ratio (SNR) based methods. This project will focus on the latter, as spectrally efficient modulation methods such as Orthogonal Frequency Division Multiplexing (OFDM) require SNR data for efficient rate adaptation. Higher coverage and smoother rate transitions can be achieved by using Non- line of sight communication, by bouncing light off walls and other surfaces. However, this configuration comes at the cost of reduction in the highest achievable rate. Furthermore, rate adaptation could be used to augment intelligent lighting solutions by incorporating itself in to dimming, localized transmissions and colored light sources. In order to evaluate the performance of an indoor VLC system using rate adaptation for multiple access, some preliminary works were carried out. These works show that OFDM can be used improve data rate in VLC systems. These works have also helped to identify challenges faced in extending the current setup for implementing rate adaptation techniques for multiple access, diffuse lighting, dimming and colored lighting.

About the Speaker

Mr Dilukshan Ajith Karunatilaka is a postgraduate student in the School of Engineering. He is currently pursuing his PhD study on “Rate Adaptive Multi User Visible Light Coomunication For Indoor Spaces” under the supervision of Dr Rajendran Parthiban and Dr Vineetha Kalavally.