The remainder of this paper is organized as follows. Section 5 presents some results of LASR in a simulated underwater network. Radio and acoustics are both shared medium techniques: multiple senders and receivers use the same medium (e.g., the water of the ocean) and there must be some sort of medium access control (MAC) to keep them from all “talking at once”.
Inherent in shared-medium systems is the problem of collision—the interference among multiple, simultaneously-received signals.
Provision for a node tracking system is another novel addition: using the time-division multiple access (TDMA) feature of the simulated acoustic modem, LASR includes a tracking system that predicts node locations, so that LASR can proactively respond to topology changes.
LASR delivers 2-3 times as many messages as flooding in 72% of the simulated missions and delivers 2–4 times as many messages as DSR in 100% of the missions.
In a network, a node is a communication endpoint able to send and receive data.
When two nodes can communicate with one another, they are said to have a link between them.
As autonomous underwater vehicles (AUVs) continue to become less expensive and more capable, they are being deployed in larger groups.
A message may have to be forwarded across one or more links to intermediate nodes before reaching its intended destination.
Routing is the process of choosing the links that will comprise the route the message will follow across the network.
The network must spontaneously organize, learn the topology, and begin routing with a minimum of overhead traffic for route discovery and maintenance.
There has been a great deal of attention paid to this problem, but almost exclusively as it applies to wireless radio networks [1–4].