Constructing Strong Barriers With Underwater Sensor Networks

Using sonar to detect submarines used to be an effective method. Current technologies, however, have made it possible for submarines to thwart standard (active or passive) sonar mechanisms [1]. One viable alternative is to use magnetic or acoustic sensors in close proximity to 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. Previous work has focused on 2-dimensional sensor networks. We show new results for 3-dimensional sensor networks which is fundamentally different. We first 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. In other words, there always exists a path by which an adversary informed of the locations of the sensors can move without being detected. We then 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. Finally, we describe energy conserving approaches to constructing a strong 3-dimensional barrier using mobile nodes so that intruding submarines cannot pass through without being detected. We start by implementing an optimal approach to mapping sensors to grid positions. We then focus on developing an approximate approach for better time efficiency using Auction algorithms. We conclude by comparing the results of both approaches using simulations. Our results show that the Auction algorithm produces similar results to the optimal approach at a reduced computational expense. This provides us an effective approach to constructing strong barriers for area coverage.