MAC protocols that exploit propagation delay in underwater networks

This paper discusses novel medium access control (MAC) protocols for underwater acoustic networks that utilize propagation delay to increase the network throughput. Traditional MAC design considers propagation delay as undesirable and attempts to mitigate its impact on throughput. The essential idea in this paper is to do simultaneous pairwise transmissions and utilize the propagation delay to avoid collisions at the receiver. The throughput and queueing delay performance of the protocols proposed here is superior compared to the corresponding traditional protocols. We discuss static and dynamic variations of time division multiple access (TDMA) based protocols we call Twin-TDMA and Twin-DTDMA. We shall also see how the same concept can be utilized in an ALOHA-like protocol, which we term Twin-ALOHA. The protocols are primarily designed to have utility in large propagation delay underwater networks, where the performance of traditional MAC protocols is significantly degraded due to the large propagation delays.