Routing in the Vicinity of Multiple Holes in WSNs

In disaster management wireless sensor networks, routing holes may occur due to various reasons such as the presence of obstacles (e.g., lakes, rivers, mountains) or external forces (caused by fire, earthquake, flood, The traditional scheme for bypassing holes is to forward packets along the holes' perimeter. However, this scheme leads to two serious problems: data concentration around the hole boundaries and routing path enlargement. Recently, several approaches have been proposed to address these two problems, wherein a common idea is to form forbidden areas around the holes from which packets are kept to stay away. Unfortunately, most of the protocols proposed so far address only special cases where either the network contains only one hole or the sources and the destinations stay fairly far from the holes. In this paper, we focus on the general case where the network may contain multiple holes and the sources/destinations may stay in the vicinity of the holes. We then propose a hole bypassing protocol which can balance the traffic over the network while ensuring the constant stretch property of the routing path. The theoretical analysis proves that the routing path stretch of the proposed protocol can be controlled to be as small as $1+\epsilon$ (for any predefined $\epsilon\gt0$), and the simulation experiments show that our protocol strongly outperforms state-of-the-art protocols in terms of load balancing.