A Simple Hole-Resistant Technique for Reliable Geocasting in Wireless Sensor Networks

In wireless sensor networks, geocasting is one of the important transmission behaviors when the sink intends to send messages to sensor nodes in a specific area, typically identified by accurate two-dimensional location information (e.g., xand y-coordinates). Unfortunately, this information is not always obtained at sensor nodes, and the network may have environmental holes (e.g., physical obstacles or areas without the functionality of communication). The challenges are more likely to cause a low packet delivery ratio. This paper proposes a Simple HOle-Resistant Technique, called SHORT, to improve the geocast packet delivery ratio in virtual coordinate wireless sensor networks with holes. Sensor nodes in virtual coordinate wireless sensor networks are positioned by two virtual coordinates, direction and distance, respectively represented by a directional code and hop count from sink. To select appropriate nodes to participate in relaying geocast packets, each candidate forwarder depends on its direction and distance to derive an ultimate forwarding probability when it receives geocast packets. As the proposed SHORT can assign a higher forwarding probability to a more appropriate candidate forwarder, it can efficiently resist environmental holes. Simulation results validate that SHORT achieves a higher packet delivery ratio compared with the simple direction-based forwarding scheme under virtual coordinate wireless sensor networks with holes.