Dong, W.; Yang, Q.; Huang, X.; Chen, Y., and Sun, S., 2022. Development of underwater wireless sensor networks (UWSNs): Using MAC protocol with concurrent transmission based on slotted FAMA. Journal of Coastal Research, 38(1), 241–248. Coconut Creek (Florida), ISSN 0749-0208.

With the continuous development of ocean research in recent years, as an extension of terrestrial wireless sensor networks, underwater wireless sensor networks play an increasingly important role in ocean and coastal research. The handshaking efficiency in the traditional slotted floor acquisition multiple access (FAMA) is low. After a successful handshake, only one node is allowed to send data. Moreover, there are unnecessary back-off problems; thus, the channel utilization is low. Aiming at improving the shortcomings of the traditional slotted FAMA, this paper proposes a Medium Access Control protocol with concurrent transmission based on slotted FAMA (SFAMA-CT). The sending node uses the long propagation delay of the network to maintain a sending matrix according to the position information of the nodes in the propagation range. The value of each element of the sending matrix is determined by whether two nodes can simultaneously send data without collision. Then, the sending node determines whether it can choose to send in the DATA phase according to the number of received X Clear-To-Send (XCTS) packets (where “X” indicates a CTS packet intended for another node) and element information of the sending matrix. The proposed protocol has higher handshake efficiency and improves the concurrent transmission of the network compared to that of other protocols. The simulation results show that, compared to slotted FAMA and SFAMA-data train (DT), the throughput of SFAMA-CT is increased by approximately 115% and 20%, respectively. SFAMA-CT also has good performance in the end-to-end delay.