QoS based enhanced lossless contention MAC protocol for ultraviolet network.

Ultraviolet (UV) communication, with its excellent characteristics of non-line-of-sight propagation, high confidentiality, and flexible networking, has gradually gained traction in the field of research. The UV media access control (MAC) protocol is relatively lacking at present, and the UV lossless contention MAC (UVLLC-MAC) protocol designed by our team earlier is limited by the predictability of communication network topology; hence, it is not applicable to multinode and multi-data networks. In order to be applicable to multinode network and satisfy the quality of service (QoS) for various data, an enhanced UVLLC-MAC (eUVLLC-MAC) protocol is proposed based on the binary exponential backoff (BEB) and UVLLC protocols. A two-dimensional Markov chain is established to analyze the network performance, and the throughput and delay expressions of the UV network are derived systematically. Subsequently, the effects of reset probability, maximum backoff order, and priority types on network performance are analyzed, and the protocol parameters are optimized to obtain the best network performance. Finally, it is observed that compared with the BEB and UVLLC-MAC protocols, the network under the eUVLLC-MAC protocol can obtain better performance in throughput, packet loss rate and delay comprehensively, which demonstrates the effectiveness of the proposed protocol. Additionally, the eUVLLC-MAC protocol can provide guidance for multinode and multi-data UV networking.