Performance Analysis of Underwater Visible Light Communication Systems

Abstract

Underwater wireless communication is gaining considerable research interest due newlineto increased exploitation of natural underwater resources, especially in the ocean, newlinewhich has led to a number of technological advances in the domains of oil and gas newlineexploration, environmental monitoring, and the military, among others. Recently, newlineunder water visible light communication (UWVLC) has been preferred, which works newlinewell in the blue-green wavelength range and requires positioning along a line of sight. newlineDue to support of large bandwidth, UWVLC is suitable for real-time image and newlinevideo transmission. However, UWVLC suffers from high path-loss due to absorption newlineand scattering, and turbulence-induced fading. The underwater optical turbulence newlineis caused by fluctuations in the refractive index of water, which is influenced by newlinevariations in temperature and salinity of water. Furthermore, the behaviour of newlinechannel in horizontal and vertical communications is different as concentration of newlinewater is homogeneous in horizontal direction, but it is non homogeneous in vertical newlinedirection. Thus, these impairments severely degrade the performance of UWVLC newlinesystem and limit its communication range to a short distance. Furthermore, the newlineperformance degrades severely with the depth due to the variation of sea parameters newlinesuch as temperature, eddy particles and pressure. newlineIn this thesis, we have modelled the UWVLC channel using the statistical model newlinewith a log normal distribution, where the statistical parameters of the log normal channel depend upon the oceanic parameters such as water temperature, eddy newlineparticles, pressure, scintillation index of water etc. The statistical parameters of newlinehorizontal channel will be uniform, but they vary in the vertical direction. Therefore, the vertical channel has been modelled by cascading log normal distributions newlinewith different statistical channel parameters. To combat the adverse effect of the newlineunderlying channel and improve the performance and range of communication, we newlinehave used spatial diversity with SIMO systems a