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Optical wireless communication (OWC) is a breakthrough technology sparked by recent advances in visible-light receiver/transmitter technology and popularized by the prospect of dual-use for indoor lighting. It is defined as any system where a modulated light beam, whether from a laser diode or an LED, is propagated through an open environment to obtain broadband communication. This poster showcases research by the Communication Systems group at the School of Engineering in the University of Warwick. The focus is applications of optical wireless communications, from deep oceans to aviation, including indoor, outdoor and vehicular uses. Advantages over traditional communications: • significantly higher data rates; • licence-free frequency spectrum; • ability to communicate in areas that restrict radio-frequency communications; • more energy efficient communication. Underwater OWC has applications in ocean mapping, environmental monitoring and defence. Research at Warwick includes: • underwater optical sensor networks; • non-line-of-sight underwater links • long range underwater links (>100m); • hybrid underwater/acoustic systems. Optical communications in free space undergo scintillation and turbulence due to changes in weather conditions. A genetic algorithm has been developed which finds the ideal optical parameters for a given set of conditions, where: • the weather condition is described by four parameters (attenuation, fog, rainfall, scintillation); • system condition is described by ten parameters (transmitter/receiver aperture size, beam divergence, transmitted power, wavelength, range, bitrate, receiver responsivity, bandwidth and the photoreceiver hardware Significant results: • multiple Monte Carlo channel simulations; • multi-hop experimental protocol testing for sensor nodes; • ideal wavelength selection algorithm based on chlorophyll surface level and depth; • estimation of refractive displacement when light is propagated through seawater with a refractive gradient. Fig 1: received power from a single centrally located LED OWC has several uses within vehicular technology. Our research includes: • high-bandwidth multimedia systems within the vehicle (fig 1); • replacing electrical or optical wires within the chassis to improve crash safety; • between vehicles to assist control. The algorithm can be used to optimize any of these parameters based on the other fixed parameters. OWC has higher bandwidth, better security and improved energy efficiency over indoor radiofrequency communications. We have researched: • dynamic multi-spot transmission algorithms to adapt to their environment; • a new low-noise receiver, the photo-parametric amplifier, where a photodetector is pumped at microwave frequencies and photodetection and parametric amplification are achieved simultaneously. attenuation (m-1) For each application of optical wireless, we characterize the channel and use it to find optimized transmitter and receiver optics. 1 0.8 0.6 0.4 0.2 0 0 700 -50 600 -100 depth (m) 500 400 wavelength (nm) -150 -200 -250 Fig 2: attenuation coefficient with depth and wavelength Optical wireless communications will continue to grow in popularity as users require higher and higher wireless bandwidths. The technology is planned to be included within 5G mobile wireless and the architecture for including this technology within homes is slowly being implemented as more use LED lighting. Laura Johnson contact details and portfolio References and further reading Communication Systems group research portfolio