MAC protocol for implementing SDM in large-scale ultraviolet networks

Ultraviolet (UV) optical communication, featuring non-line-of-sight communication, high confidentiality, and robust anti-interference capabilities, is highly suitable for communication on small-sized platforms such as unmanned aerial vehicles (UAV) in electromagnetic interference-prone environments. Nevertheless, its substantial path loss constrains communication distance and data rate. Integrating UV optical communication with self-organizing networks to construct self-organizing UV optical communication networks can effectively address this issue, holding great potential for enabling reliable communication among small-sized platforms in intense electromagnetic interference scenarios. Currently, there are relatively few media access control (MAC) protocols applied to multi-node UV optical communication networks. In this paper, based on the lossless competition-based competition handling mechanism and the bit-simultaneous transmission-based relaying approach, we proposed a neighbor discovery algorithm with low control overhead. This algorithm can establish a topological matrix of the entire network within all nodes. Based on this, we innovatively separate channel competition from data transmission and devise a MAC protocol achieving space-division multiplexing (SDM) through dynamic subnetting. The proposed protocol first forms multiple non-interfering subnets via lossless competition, and then enables all subnets to transmit data concurrently. Simulation analysis using <i>Omnet++</i> reveals that the proposed protocol can significantly enhance the average throughput in large-scale distributed networks, attaining superior network performance.