A survey of practical issues in underwater networks
WUWNet '06 Proceedings of the 1st ACM international workshop on Underwater networks
Understanding spatio-temporal uncertainty in medium access with ALOHA protocols
Proceedings of the second workshop on Underwater networks
A reservation mac protocol for ad-hoc underwater acoustic sensor networks
Proceedings of the third ACM international workshop on Underwater Networks
Performance of a Propagation Delay Tolerant ALOHA Protocol for Underwater Wireless Networks
DCOSS '08 Proceedings of the 4th IEEE international conference on Distributed Computing in Sensor Systems
System Design Considerations for Undersea Networks: Link and Multiple Access Protocols
IEEE Journal on Selected Areas in Communications
RIPT: A Receiver-Initiated Reservation-Based Protocol for Underwater Acoustic Networks
IEEE Journal on Selected Areas in Communications
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Standard analyses of wireless random access protocols that are available in the literature assume negligible propagation delay between any two nodes. This assumption holds good in reasonably short-range terrestrial RF (radio frequency) wireless networks. On the contrary, in wireless communications involving acoustic wave propagation, as in underwater wireless networks, even short distance propagation has appreciably large propagation delay. This observation has led to several recent simulation and experimental studies on underwater Aloha and slotted-Aloha (S-Aloha) protocols and also a few new proposals on random access protocols for underwater wireless ad hoc networks (UWN). To study the efficiency of more advanced multiaccess communication protocols for UWN, it is important to benchmark their performances with respect to the two basic random access protocols, Aloha and S-Aloha. This paper provides an analytic framework to capture the performance of Aloha and S-Aloha protocols in an underwater environment with high and random internodal signal propagation delay. The performance of underwater Aloha and S-Aloha are contrasted with those in short-range terrestrial RF wireless networks. The analysis shows that random internodal propagation delay has no effect on the underwater Aloha performance. It also sheds light on the throughput degradation of underwater S-Aloha with a slotting concept that achieves RF S-Aloha equivalent one-slot vulnerability. Additionally, a modified slotting concept is introduced where the slot size is judiciously reduced such that even by allowing some collisions the overall system throughput can be increased. Our calculations show that, with the modified slotting approach up to 17% throughput performance gain can be achieved over the naive (RF S-Aloha equivalent) slotting approach in UWN. Our analytic results are supported by discrete event simulations.