Full-duplex Underwater Optical Communication Systems: A Review

Underwater Optical Communication (UWOC) systems are attractive to researchers due to their ability of low power consumption, less complexity, high data rates, and covert communication. Various half-duplex (HD) UWOC systems has been proposed in this regard, but due to half-duplex characteristics, these systems have failed to improve the high throughput gain, high power efficiency and high data rates etc. Hence, we provided a review of different Full-Duplex UWOC systems using different light sources, with respect to transmission range, operational power, data rate, wavelength, and different underwater communication mediums. We observed that these FD systems have improved the communication range as well as data transfer rates, while implementing different light sources (i.e. lasers, avalanche photo diodes (APD), green and blue LEDs and lasers) in their transceivers. However, we pointed out that power inefficiency is a major issue faced by FD-UWOC systems. We also presented BER comparison of different FD-UWOC systems, implementing different modulations schemes, and pointed out that FD UWOC systems implementing un-coded 8PPM and BPSK outperformed. Finally, we concluded the paper and also highlighted some future directions for the FD-UWOC systems, and hope that our review can provide a platform for future research in the targeted area.