An Interference-aware and Collision-free MAC Protocol for Underwater Wireless Sensor Networks

In the realm of underwater wireless communication, vast oceanic expanses often demand large-scale deployment of Underwater Wireless Sensor Networks (UWSNs). UWSNs rely on acoustic communication channels, presenting distinct challenges like prolonged propagation delays, restricted bandwidth, and dynamic topologies. Furthermore, the far-reaching and multi-path nature of acoustic signals results in significant hidden terminal problems and ubiquitous interference between neighboring nodes. Therefore, an efficient medium access control (MAC) protocol is crucial for optimizing UWSN performance. This article proposes IC-MAC, a MAC protocol tailored for UWSNs to avoid collisions and improve network performance. IC-MAC employs distributed clustering to group sensor nodes and the cluster head degree is defined for each node, which is a coefficient that accentuates nodes characterized by a higher incidence of collision associations. To identify interfering nodes and construct an interference-free graph, an interference identification algorithm is proposed. In addition, a heuristic graph coloring technique, guided by particle swarm optimization, allocates time slots efficiently to achieve collision-free transmission scheduling and enhanced spatial reuse. Simulations demonstrate the effectiveness of the IC-MAC protocol in enhancing throughput, reducing delay, and improving packet delivery ratio and energy efficiency. This is achieved through efficient spatial resource utilization and robust management of collisions and interference, specifically tailored for underwater acoustic channels, outperforming existing MAC protocols.