Abstract
The well known location-aware routing protocols utilize the local location information for constructing an efficient route with low control overheads in wireless sensor networks (WSNs). However, their performance drops significantly when obstacles exist. To reduce the impact of obstacles on routing performance, developing obstacle-resist routing protocols is one of the most important issues in WSNs and has recently received much attention. The major goal of an obstacleresist routing protocol is to guide the packets along a route without visiting the concave areas of obstacle. Existing passive routing protocols can only lead the packets away from the obstacles, but cannot guide the packet to the best route. Alternatively, a number of active obstacle-resist routing protocols automatically detect and maintain the obstacle information when the obstacle is formed and then establishes a forbidden region for each concave area to improve the performance of location-aware routings. This chapter reviews obstacle-resist locationaware routing protocols from both concept and technique points of view. The location-aware routing protocols, obstacle boundary detection algorithms as well as passive and active routing protocols are reviewed. Finally, we point out some possible future directions and open issues related to the obstacle-resist routing problem.