Multi gigabit/s visible light communications: modelling and demonstrations

Thesis

Traffic in wireless communications is expected to increase exponentially due to demands such as multiple up/downloading, and streaming of ultra-high-definition or multi-dimensional content. This demand requires the development of multi-Giga bit/s communication systems. Insufficient radio spectrum is the main barrier to developing such high-speed wireless systems. Visible light communications (VLC) has the potential to overcome this barrier by providing THz of unlicensed spectrum.

This thesis reports a new generalized modelling method and demonstrations for multi Gigabit/s VLC. For the optimum design of such system, a comprehensive investigation is presented, including the review of existing investigations. Novel design methods, such as optimisation for band-limited optical orthogonal-frequency-division-multiplexing schemes, generalisation of multi-input-multi-output (MIMO) VLC channels, and consideration of device characteristics in the modelling, are introduced for the first time. Then, various VLC techniques are compared considering practical constraints from various VLC channels and devices.

Demonstrations of multi-Gb/s VLC systems are also presented: A 3-Gb/s wireless link with a single Gallium Nitride micro light-emitting-diode (μLED), a 1.68 Gb/s white-light communication link using a conjugated polymer and the μLED, and laser diode (LD) based remote phosphor approach leading to data-rates of up to 6.52 Gb/s for single channel and 10 Gb/s for 2-channel imaging system. These are the fastest demonstrations through a single LED source, and white-light generating LED and LD sources, respectively, at the time this thesis was written.

Authors: Chun, H

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford