Performance Evaluation of Underwater Medium Access Control Protocols: At-Sea Experiments

In this paper, we investigate the performance of three medium access control (MAC) protocols (CSMA, T-Lohi, and DACAP) representing simple, intermediate, and fully negotiated protocols, to access the underwater acoustic channel, during two at-sea campaigns. Various tests were conducted in the waters surrounding Pianosa island during the NATO ACommsNet10 experiment in September 2010 and off the coast of the Palmaria island during the NATO CommsNet13 experiment in 2013. Different types of application loads and communication devices have been used to investigate the performance of the various protocols under different transmission rates and introduced overhead. The presence of more stable and reliable communication links and of a highly dynamic communication channel has also been explored. The collected results show that there is no single solution that is best for all the possible scenarios and configurations and that the selection of different protocols is required for different contexts. This highlights the importance of understanding the performance of each protocol at sea, under various conditions, to design novel and adaptive schemes, which are able to react in an efficient and effective way to possible changes in the network and in the communication channel.