Rate Maximization for Lightwave Power Transfer-Enabled Cooperative Half/Full-Duplex UOWC Systems

In this paper, we consider an uplink cooperative underwater optical wireless communication system in which a seabed sensor communicates with a sink on the water surface via an amplify-and-forward relay. The seabed sensor harvests lightwave energy transmitted from the relay in the first phase and forwards uplink information in the second phase according to the harvest-use protocol. For full-duplex (FD) and half-duplex (HD) modes of operation at the relay, we optimize the instantaneous time-splitting parameter such that the uplink information rate is maximized. In particular, presented expressions are useful to investigate the impact of key system and channel parameters such as the relay transmit power, time-splitting parameter, and relay placement. Our analysis reveals the operational regions of interest where the FD mode is beneficial as compared with the HD mode. Further, the optimal relay position is around 3–6 m for a 15 m link.