Power management for unattended wireless sensor networks

Extending battery life is one of the main challenges in the design of wireless sensor networks (WSNs). To address this challenge, a substantial research effort has been dedicated to the development of so-called energy efficient protocols for the medium-access-control (MAC) and network layers. For example, low duty cycle is a widely-used technique. The other key element in this challenge is the WSN power supply subsystem. The design of this element has been largely overlooked in the literature. Practical WSN applications require low cost power supplies that can essentially act as a reliable current source under varying environmental conditions. This paper suggests a new systematic approach to the design of the power supply subsystem for WSNs. The proposed design results in improved reliability under varying environmental conditions, regardless of the specific duty cycle parameters. The performance of the proposed approach is evaluated by an experimental WSN deployment.