Analysis of optical wireless communication links in turbulent underwater
channels with wide range of water parameters
Abstract
In this study, the performance of underwater optical wireless
communication links is investigated by taking into account turbulence,
absorption and scattering effects. Weak turbulent channel is modeled
using log-normal distribution while moderate and strong turbulence
channels are modeled using gamma-gamma distribution. Rytov variance of
Gaussian beam is derived analytically for oceanic turbulence optical
power spectrum. Subsequently, scintillation index is calculated using
the computed Rytov variance. Moreover, the closed-form expression of
bit-error-rate (BER) for underwater wireless optical communication
(UWOC) systems using intensity-modulated/direct detection (IM/DD)
implementation and on-off-keying (OOK) modulation scheme is obtained.
Results show that the performance of wireless optical communication link
between two platforms in underwater medium is degraded significantly due
to turbulence, absorption and scattering. In fact, as the turbulence
level increases, its effect becomes quantitatively comparable to those
of absorption and scattering effects. The variation of both
scintillation index and BER performance are presented for various
underwater medium and communication system parameters, such as
chlorophyll concentration, average temperature, average salinity
concentration, temperature and dissipation rates, wavelength, link
length and receiver aperture size. Optical network and internet of
underwater things (IoUT) applications, which are growing day by day and
requiring high data rates, will benefit from the results of this study.