Hole detection and shape-free representation and double landmarks based geographic routing in wireless sensor networks

In wireless sensor networks, an important issue of geographic routing is “local minimum” problem, which is caused by a “hole” that blocks the greedy forwarding process. Existing geographic routing algorithms use perimeter routing strategies to find a long detour path when such a situation occurs. To avoid the long detour path, recent research focuses on detecting the hole in advance, then the nodes located on the boundary of the hole advertise the hole information to the nodes near the hole. Hence the long detour path can be avoided in future routing. We propose a heuristic hole detecting algorithm which identifies the hole easily and quickly and then propose a representation of hole no matter what the shape of the hole is. In addition, we quantitatively figure out the areas in the vicinity of the hole that need to be announced the hole information. With such information, a new routing scheme with two landmarks was developed. Simulation results illustrate that our approach can achieve better performance in terms of the average length and number of hops in routing paths. Simulation also shows that our approach introduces very small computational complexity.