Simple statistical channel model for weak temperature-induced turbulence in underwater wireless optical communication systems

Abstract

In this Letter, we use laser beam intensity fluctuation measurements to model and describe the statistical properties of weak temperature-induced turbulence in underwater wireless optical communication (UWOC) channels. UWOC channels with temperature gradients are modeled by the generalized gamma distribution (GGD) with an excellent goodness of fit to the measured data under all channel conditions. Meanwhile, thermally uniform channels are perfectly described by the simple gamma distribution which is a special case of GGD. To the best of our knowledge, this is the first model that comprehensively describes both thermally uniform and gradient-based UWOC channels.

Light based underwater wireless communications

“…Besides, optimal combining schemes and maximum likelihood detection schemes were investigated in 2012. 153) Additionally, the effects of turbulence and geometries of the system on the received signal energy distribution were studied by Liao et al 154) For UWOC, UV scattering enhanced by water molecules, dissolved organic matters and ions makes it feasible to construct underwater UV NLOS communications, which may mitigate the alignment problems caused by turbulence, such as in the presence of bubbles, 45) the gradient of salinity and temperature, 46) in a UWOC with LOS. An underwater NLOS network concept was proposed by means of backreflection at the ocean-air interface and a corresponding mathematical model was derived.…”

“…The impact of temperature gradient was experimentally investigated in Ref. 46. Similar to salinity gradient, it was found that the log-normal distribution, traditionally used in atmospheric optical turbulent channels, failed to mimic the statistical behavior of the measured irradiance.…”

“…[45][46][47]171) However, more system level tests including vertical link configurations need to be performed in a realistic underwater environment.…”

“…45) The model showed an excellent fit with the measured data under all channel conditions emulated. In another study, 46) the authors have accurately developed a simple statistical channel model for weak temperature-induced turbulence in UWOC systems. The generalized Gamma distribution (GGD) was found to perfectly describe both non-turbulent thermally uniform underwater optical channels and underwater optical channels with temperature gradients.…”

Real-Time Video Transmission Over Different Underwater Wireless Optical Channels Using a Directly Modulated 520 nm Laser Diode

“…Nevertheless, it has also its own challenges and is still in its infancy. Underwater absorption, scattering, and turbulence are the key factors that significantly affect the performance of UWOC links and image-quality of underwater video and imaging systems [5]- [7]. As a matter of fact, only short range links have been established for UWOC [8]- [12].…”