PERFORMANCE OF UNDERWATER WIRELESS OPTICAL IoT NETWORKS USING CDMA

Abstract

The reliability of an underwater wireless optical communication (UWOC) network is seriously impacted by oceanic turbulence and 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 pressure, water, and temperature. In this work, we investigate the performance analysis of a vertical UWOC link subject to propagation loss, beam spreading and pointing loss, and oceanic turbulence. Furthermore, we investigate optical code-division multiple-access (CDMA), which is utilized to enable asynchronous and simultaneous data transmission between sources (e.g., underwater sensors, submarines, divers, etc.) and the destination, which can be a ship, buoys, unmanned underwater vehicles, and so on. This study is based on an accurate mathematical framework for link modeling while taking into account realistic Tx/Rx and channel parameters under the effects of the oceanic turbulence and beam spreading loss conditions. In addition, we provide an analytical expression for calculating the bit error rate (BER). Moreover, the necessity of optimal Tx/Rx parameter selection is demonstrated to satisfy the quality of service such as BER. The presented results give valuable insight into the practical aspects of the deployment of UWOC systems using CDMA.