A Communication Paradigm for Hybrid Sensor/Actuator Networks*

Abstract

This paper investigates an anycast communication service for a hybrid sensor/actuator network, consisting of both resource-rich and resource-impoverished devices. The key idea is to exploit the capabilities of resource-rich devices (called micro-servers) to reduce the communication burden on smaller, energy, bandwidth and memory constrained sensor nodes. The goal is to deliver sensor data to the nearest micro-server, which can (i) store it (ii) forward it to other micro-servers using out-of-band communication or (iii) perform the desired actuation. We propose and evaluate a reverse tree-based anycast mechanism tailored to deal with the unique event dynamics in sensor networks. Our approach is to construct an anycast tree rooted at each potential event source, which micro-servers can dynamically join and leave. Our anycast mechanism is self-organizing, distributed, robust, scalable, routing-protocol independent and incurs very little overhead. Simulations using Network Simulator (ns-2) show that: our anycast mechanism when added to Directed Diffusion can reduce the network’s energy consumption by more than 50%; can reduce both the mean end-to-end latency of the transmission and the mean number of transmissions by more than 50%; achieves 99% data delivery rate for low and moderate micro-server mobility rate; and handles network dynamics reasonably well.