On the Performance of Multi-Wavelength Underwater Optical Channels in the Presence of Optical Turbulence
Shideh Tayebnaimi, Kamran Kiasaleh
TL;DR
The paper addresses fading in underwater wireless optical communications (UWOC) caused by optical turbulence, scattering, and absorption. It analyzes a Gaussian beam using IM/DD OOK across multiple wavelengths, employing a modified Nikishov power spectrum and a log-normal fading model to derive irradiance statistics and fade metrics. The key finding is that increasing the number of independent wavelengths ($N$) significantly lowers the fade probability $P_{FD}$, reduces the fade rate $N_{FD}$, shortens the mean fade duration $T_{MFD}$, and increases the mean time between fades $T_{MTBF}$, with longer wavelengths generally offering greater resilience. These results suggest that wavelength diversity is a practical and effective strategy to improve UWOC reliability in weak turbulence, potentially enabling higher data rates and more stable links in challenging underwater environments.
Abstract
This paper presents an analysis of the performance of a Gaussian optical beam as it propagates through the turbulent underwater optical channel (UWOC) under the weak turbulence regime, where optical signal experiences significant fading and scattering, all of which can severely degrade communication quality. It is assumed that on-off keying (OOK) modulation with direct detection is utilized to establish a duplex communication link. A multi-wavelength beam approach is implemented to enhance the performance by leveraging the distinct propagation characteristics of different wavelengths. Performance is established in terms of the probability of fade, number of fade per second, mean fade duration, and mean time between fades. The use of multi-wavelength beam is shown to enhance performance by a sizable margin.