Wave phase coding applied to frequency-shift keying for spectrally efficient underwater optical communication

In the last decade, the advances in optoelectronics have led optical wireless communication to become an effective technology to transmit data in challenging environments like the underwater one. Unlike the well-established acoustic signaling, underwater optical communication enables high rates transmission even though they are limited to a shorter distance on the order of tens of meters. In fact, light propagation strongly suffers from attenuation caused by the channel. In such conditions, data transmission is typically based on modulation schemes providing high reliability at the expense of poor spectral efficiency. In this direction, herein we propose a novel modulation scheme that, by combining the principles of frequency and a novel phase modulation, referred to as wave phase coding, achieves a high spectral efficiency while maintaining a remarkable robustness to errors. Simulation results demonstrate that the proposed solution is able to achieve a convenient trade-off between spectral efficiency and reliability, outperforming both conventional schemes and hybrid techniques proposed in the literature.