Distributed Coordinate-free Hole Detection and Recovery

A distributed algorithm is introduced which detects and recovers holes in the coverage provided by wireless sensor networks. It does not require coordinates, requiring only minimal connectivity information (for example, whether any two nodes are within either the sensing radius or twice the sensing radius.) The radio communications area is assumed to be larger than the sensed area. Two active nodes are called neighbors, and are said to be connected by a link, if their distance lies between these two values. Redundant nodes are likely to exist inside an active node's sensing range. If all connected neighbors of some active node A can form a ring via links between them, there is no large hole inside the ring. Otherwise A is a boundary node of a large hole. All boundary nodes and most holes can be detected with very low probability of error, and simulation results suggest that redundant nodes are selected efficiently for activation when recovering the hole. Keywords-coordinate-free; hole detection; self-healing