Barrier coverage for underwater sensor networks

Using sonar to detect submarines was an effective method. Current technologies, however, have made it possible for submarines to thwart standard (active or passive) sonar mechanisms [1]. Thus, finding alternatives to detect submarines becomes important and timely. One viable alternative is to use magnetic or acoustic sensors in close proximity of possible underwater pathways a submarine may pass through. This approach may require deploying large-scale underwater sensor networks to form strong barriers for coastline protection. In this paper we first derive the notion of 3-dimensional stealth distance to measure how far a submarine can travel in a sensor network before being detected by a sensor. Next we prove that there is no strong barrier coverage in a large 3-dimensional fixed emplacement sensor field where sensor locations follow a Poisson point process, i.e., there always exists a path by which an adversary informed of the locations of the sensors can move without being detected. Finally, we describe an energy conserving approach to constructing a strong 3-dimensional barrier using mobile nodes so that intruding submarines cannot pass through without being detected.