Distributed topological convex hull estimation of event region in wireless sensor networks without location information

In critical event (e.g., fire or gas) monitoring applications of wireless sensor networks (WSNs), convex hull of the event region is an efficient tool in handling the usual tasks like event report, routes reconstruction and human motion planning. Existing works on estimating convex hull of event region usually require location information of sensor nodes, which needs high communication cost or hardware cost. In this paper, to avoid the requirement of location information, we define topological convex hull (T-convex hull) which presents the convex contour of an event region directly with a route passing by nodes, and hence becomes more efficient in handling the above tasks. To obtain the T-convex hull of event region in the absence of locations, we propose a low-weight (in terms of computation and storage resource requirement) distributed algorithm, with which sensor nodes just need to count the hop counts from some nodes. The communication cost of the algorithm is also low and independent of the network size. Comprehensive and largescale simulations are conducted, showing the effectiveness and much lower communication cost of the proposed algorithm, compared with related method. Index Terms- Wireless sensor networks (WSNs), event region, convex hull, topological methods, the shortest path tree.