Design and analysis of a propagation delay tolerant ALOHA protocol for underwater networks

Joon Ahn, Affan Syed, Bhaskar Krishnamachari, John Heidemann
2011 Ad hoc networks  
Acoustic underwater wireless sensor networks (UWSN) have recently gained attention as a topic of research. Such networks are characterized by increased uncertainty in medium access due not only to when data is sent, but also due to significantly different propagation latencies from spatially diverse transmitters-together, we call these space-time uncertainty. We find that the throughput of slotted ALOHA degrades to pure ALOHA in such an environment with varying delay. We therefore propose
more » ... ng this spatial uncertainty by adding guard times to slotted ALOHA, forming Propagation Delay Tolerant (PDT-)ALOHA. We show that PDT-ALOHA increases throughput by 17-100% compared to simple slotted ALOHA in underwater settings. We analyze the protocol's performance both mathematically and via extensive simulations. We find that the throughput capacity decreases as the maximum propagation delay increases, and identify protocol parameter values that realize optimal throughput. Our results suggest that shorter hops improve throughput in UWSNs.
doi:10.1016/j.adhoc.2010.09.007 fatcat:wzih5csqfjeurfgxzfd5uxucgm