Barrier coverage in a sensor network has the goal of ensuring that all paths through the surveillance domain joining points in some start region S to some target region T will intersect the coverage region associated with at least one sensor. In this paper, we revisit a notion of redundant barrier coverage known as k-barrier coverage. We describe two different notions of width, or impermeability, of the barrier provided by the sensors in A to paths joining two arbitrary regions S to T. The first, what we refer to as the thickness of the barrier, counts the minimum number of sensor region intersections, over all paths from S to T. The second, what we refer to as the resilience of the barrier, counts the minimum number of sensors whose removal permits a path from S to T with no sensor region intersections. Of course, a configuration of sensors with resilience k has thickness at least k and constitutes a k-barrier for S and T. Our result demonstrates that any (Euclidean) shortest path ...
Sergey Bereg, David G. Kirkpatrick