During the last decade, networking technologies have revolutionized the ways individuals and organizations exchange information and coordinate their activities. In this decade we will witness another revolution; this time one that involves observation and control of the physical world. The availability of micro-sensors and low-power wireless communications will enable the deployment of densely distributed sensor/actuator networks for a wide range of biological, earth and environmental monitoring applications in marine, soil, and atmospheric contexts. This technology has particular relevance in many Latin American countries because of its applicability to environmental monitoring of the diverse and unique ecosystems.
To achieve scalability, robustness, and long-lived operation, sensor nodes themselves will execute significant signal processing, correlation, and network self-configuration inside the network. In this way these systems will emerge as the largest distributed systems ever deployed. These requirements raise fascinating challenges for Information Technology and communication research, as well as for their application domains. One of the novel issues for network design is the shift from manipulation and presentation of symbolic and numeric data to the interaction with the dynamic physical world through sensors and actuators. This raises the need for good physical models, which requires extensive data analysis of monitored data. A second challenge arises from the greatly increased level of environmental dynamics. While all good distributed systems are designed with reliability in mind, these new target applications present a level of ongoing dynamics that far exceeds the norm. Perhaps the most pervasive technical challenge arises from the energy constraints imposed by unattended systems. These systems must be long-lived and vigilant and operate unattended. Unlike traditional Internet systems the energy constraints on un-tethered nodes present enormous design challenges. Finally, as with the Internet, there are scaling challenges. However, given the other characteristics of the problem space, the traditional techniques are not directly applicable, and alternative techniques must be developed.
This paper focuses on a particular application of embedded wireless sensing technology. The habitat sensing array for bio-complexity mapping emphasizes the need for continual automatic self-configuration of the network to adapt to environmental dynamics, and the use of coordinated actuation in the form of programmed triggering of sensing and actuation to enable identification, recording and analysis of interesting events.
We introduce the key architectural principle for constructing long-lived wireless sensor networks, adaptive self-configuration, and then describe its applicability to Habitat monitoring. In the subsequent section we describe our tiered architecture, time synchronization techniques, and experimental platform developed to support this and other applications.