A Full-Duplex Directional MAC Framework for Underwater Acoustic Sensor Networks

Underwater acoustic communication plays an essential role in underwater wireless information exchange, and nodes with such an ability constitute an underwater acoustic sensor network (UASN). However, UASNs face many challenges, such as high bit error rate and high propagation delay, significantly reducing network performance. Because of the challenging nature of underwater environments, the power consumption and battery energy efficiency of sensor nodes need to be considered. Directional communication technology can conserve energy by restraining beam directivity and diminishing interference between nodes by enabling peer-to-peer communication with intended neighbors. However, the technology suffers from the problems of neighbor discovery, deafness effect, and hidden/exposed terminal. To address these challenges, we propose a full-duplex directional medium access control (MAC) framework based on the vector hydrophone and multimodal transducer in this paper, along with a benchmark MAC protocol, which enables adaptive power control to achieve spatial reuse and energy conservation. Simulation results show that the benchmark MAC protocol outperforms existing representative protocols in terms of throughput, end-to-end delay, and energy efficiency.