A New Approach to Design Autonomous Wireless Sensor Node Based on RF Energy Harvesting System

Area of Science:

• Wireless Sensor Networks (WSNs)
• Energy Harvesting
• Radio-Frequency (RF) Energy Harvesting

Background:

• Wireless sensor nodes traditionally rely on batteries, limiting network size and performance.
• Network parameters like size, packet length, and duty cycle are constrained by harvested energy.
• Existing energy models often overlook critical energy consumption sources in sensor nodes.

Purpose of the Study:

• To propose a novel approach for designing stand-alone wireless nodes powered by Radio-frequency Energy Harvesting Systems (REHS).
• To combine energy-saving techniques with REHS optimization for enhanced Wireless Sensor Network (WSN) range.
• To develop a comprehensive energy model for autonomous nodes, considering multiple dissipation sources.

Main Methods:

• Established a comprehensive energy model for wireless nodes, incorporating five energy consumption sources.
• Quantified sensor node energy requirements using hardware parameters of commercial components (Mica2 Motes, CC2520).
• Designed and developed a miniature REHS optimized for the 2.45 GHz ISM band, including a band-pass filter to minimize reflection losses.
• Employed a gradient search method to optimize the REHS output characteristics.
• Utilized the Low-Energy Adaptive Clustering Hierarchy (LEACH) protocol for equitable network charge distribution.

Main Results:

• The developed REHS achieved an output DC power of 0.57 mW from 1 mW input RF power.
• With 100 nodes spread over 300x300 m², a Base Station (BS) can be located 310 m away with 10-minute rounds.
• The autonomous WSN range increases significantly when the monitored physical phenomenon varies slowly.

Conclusions:

• The proposed design, accounting for all sensor node dissipation sources and utilizing measured REHS performance, provides effective guidelines for creating autonomous nodes.
• This approach enables battery-free wireless sensor networks with extended operational range and improved performance.
• Optimized REHS and energy-efficient node design are crucial for the success of self-powered WSNs.