Outage probability analysis of a vertical underwater wireless optical link subject to oceanic turbulence and pointing errors

The reliability of an underwater wireless optical communication (UWOC) network is seriously impacted by beam misalignment between transmitters (Txs) and receivers (Rxs). Also, the performance of UWOC systems can be affected by oceanic turbulence-induced fading due to fluctuations in the water refractive index as a result of variations in the pressure, water temperature, and salinity. In this work, we investigate the performance analysis of a vertical UWOC link subject to oceanic turbulence and pointing errors and further investigate the appropriate selection of link parameters to optimize link performance. This study is based on an accurate mathematical framework for link modeling while taking into account realistic Tx/Rx and channel parameters under different turbulence and beam misalignment conditions. We provide an analytical expression for calculating the link outage probability, whose accuracy is validated through numerical simulations. Last, the necessity of optimal Tx/Rx parameter selection to minimize the link outage is demonstrated. A laser beam is considered at the Tx, as well as an ultra-sensitive photodetector (silicon photo-multiplier) at the Rx to enable working at relatively long link ranges. The presented results give valuable insight into the practical aspects of deployment of UWOC networks.