Underwater optical wireless communication-based IoUT networks: MAC performance analysis and improvement

Underwater Optical Wireless Communication (UOWC) is a high-speed data transmission technology promising to support the concept of the Internet of Underwater Things (IoUT). The performance of UOWC-based IoUT networks, especially medium access control (MAC), could be affected significantly by physical factors in the underwater environment. However, there is a lack of studies on the MAC performance analysis and improvement in the literature. We study in this paper a PHY/MAC cross-layer analysis that theoretically investigates the effect of UOWC PHY transmission errors on the performance of Slotted ALOHA-based MAC. To improve the performance, we propose to enable frame retransmission in the operation of Slotted ALOHA, where the optimal number of retransmissions is studied. As confirmed in the numerical results, frame retransmission could considerably improve the MAC performance. Also, the Monte Carlo simulation verifies the accuracy of our theoretical derivation for the PHY/MAC cross-layer analysis.