Geocast for wireless sensor networks

An important but relatively less studied class of network layer protocol for sensor networks is geocast. It allows a sensor node to send messages to all nodes in a given geographical area without the sender node having any knowledge about which nodes are present in that area. Developing a robust geocast protocol for practical sensor networks poses several challenges. Geocast messages should be reliably delivered to the destination area in the presence of unreliable wireless links, a typical characteristic of practical sensor network deployments. The protocol should minimize the number of radio transmissions and avoid control traffic to save energy, which is a scarce resource in sensor networks. The protocol should be robust against a wide range of network densities. This paper presents the design, implementation, and evaluation of SGcast — a reliable, robust, and energy-efficient geocast protocol that achieves these goals. For a wide range of experiments conducted using networks of real sensor nodes and simulations, we show that compared to a recent geocast protocol, SGcast achieves up to 11.08x reduction in energy consumption and up to 2.17x improvement in successful delivery of geocast messages to the destination area, while being robust against a wide variability in network densities.