In-Band Full-Duplex Underwater Acoustic Communication Based on OAM

In-band full-duplex (IBFD) technology enables simultaneous transmission and reception with the same frequency band, resulting in a twofold increase in communication rate. However, IBFD systems always suffer from severe self-interference induced by near-transmission signals during reception. Due to excessive self-interference, IBFD system not only requires accurate self-interference cancellation but also demands receiving antennas with a large dynamic range to prevent saturation and error rate. Orbital angular momentum (OAM) has a unique ring-shaped energy distribution with a zero-intensity area at its center, which can help suppress self-interference in IBFD systems. In this paper, we investigate the impact of array element misalignment on self-interference suppression under different OAM modes, with simulation results demonstrating the effectiveness of OAM vortex in suppressing self-interference. The results show that lower-frequency carriers and higher OAM modes are more effective at suppressing self-interference, resulting in higher signal-to-interference-plus-noise ratio (SINR) and increased channel capacity.