Brief announcement: routing with obstacle avoidance mechanism with constant approximation ratio

We study the problem of routing messages in sensor networks where the energy saving issue is essential. In this paper, we propose ROAM2, an improvement of ROAM (Routing protocol with Obstacle Avoidance Mechanism) proposed in [HJL+09]. This distributed protocol has a light obstacle detection and avoidance component with low message and computation overhead and a routing component which sends messages along short paths, thus saving energy. We improved it so that is has an 100% delivery rate and we prove that ROAM finds with high probability paths whose lengths are comparable to the length of the shortest paths. Furthermore, we prove a general result on the length of any path computed in a greedy way. Whereas ROAM uses one bit of memory in nodes (even if there are several destinations), in [KWZ08], it was shown that no geographic routing algorithm not using any sensor memory can compute a path whose length is guaranteed to be of order less than O(l2), where l is the length of the shortest path. Finally, we compare the energy efficiency of ROAM against GPSR (or GFG) [KK00], the algorithm proposed in [MLNR08] and SLGF [JMLW08], by running simulations which validates our theoretical results