On stochastic model for underwater wireless optical links

Abstract

Light beam suffers attenuation due to absorbtion and multiple scattering when propagating through underwater environment especially in turbid water. The spatial and temporal distribution of photons after propagation can quantify this channel attenuation and therefore is a key issue for underwater wireless optical communications (UWOC). Typically, the spatial distribution of photons consists two key factors which are the moving distance and scattering angle for each photon before and after interacting with a particle, respectively. In this paper, we present a stochastic model for UWOC links by adopting the Henyey-Greenstein (HG) function as probability density function (PDF) of scattering angle and deriving the PDF of step distance for each photon. The proposed stochastic model can be used to evaluate the spatial and temporal distribution of photons, which fits well with Monte Carlo simulation result in turbid seawater such as coastal water.

On received intensity for misaligned underwater wireless optical links

“…However, in less turbid water or over shorter communication distance, the probability of single scattering is much larger than that of multiple scattering which is therefore negligible. In some special case, we can only consider one type of the dominant scattering (single scattering or multiple scattering) similarly to [7] and [8]. In less turbid water and shorter communication, stochastic model is verified by Monte Carlo simulation and is used to characterize the spatial-temporal probability distribution for ballistic and single scattering components.…”

“…In this paper, we consider detector properties such as elevation angle, azimuth angle and FOV and evaluate the received intensity for a misaligned UWOC link. Zhang et al proposed a stochastic channel model verified by Monte Carlo simulations to characterize the spatial-temporal behavior of aligned UWOC links by the spatial-temporal probability distribution for ballistic and single scattering components [7]. And they extended this model by investigating the link misalignment caused by the light source properties [8].…”

“…And they extended this model by investigating the link misalignment caused by the light source properties [8]. Inspired by [7] and [8], we consider the detector properties which cause the link misalignment and evaluate the corresponding received intensity. Simulation results show that a wider FOV has more freedom to adjust the detector to a proper elevation angle pointing to the direction of the light source and then results in a higher light intensity for misaligned UWOC links.…”

Effect of Link Misalignment in the Optical-Internet of Underwater Things

“…Beer Lambert's law Simple to implement Less accurate [34][35][36] Chlorophyl Monte-Carlo Accurate in simulation environment Less efficient for errors [37,38] Analytical Radiative Transfer Equation (RTE) Provide accurate results Offer difficulty in solving [39,40] Analytical stochastic Efficient for performance analysis Difficult derivation with limited assumptions [41,42] Numerical RTE Easy to program, providing accurate results…”

Single scattering impulse response modeling of underwater wireless optical channels

“…To the best of our knowledge, [6] is the first to The corresponding author is Y. Dong. present an analytical model to describe the spatial-temporal probability distribution of non-scattered and scattered photons for UWOC links, which is however quite complicated and requires Monte Carlo integration at each time instant to obtain the impulse response.…”