Alex Mouapi

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

Energy Harvesting techniques are increasingly seen as the solution for freeing the wireless sensor nodes from their battery dependency. However, it remains evident that network performance features, such as network size, packet length, and duty cycle, are influenced by the sum of recovered energy. This paper proposes a new approach to defining the specifications of a stand-alone wireless node based on a Radio-frequency Energy Harvesting System (REHS). To achieve adequate performance regarding the range of the Wireless Sensor Network (WSN), techniques for minimizing the energy consumed by the sensor node are combined with methods for optimizing the performance of the REHS. For more rigor in the design of the autonomous node, a comprehensive energy model of the node in a wireless network is established. For an equitable distribution of network charges between the different nodes that compose it, the Low-Energy Adaptive Clustering Hierarchy (LEACH) protocol is used for this purpose. The model considers five energy-consumption sources, most of which are ignored in recently used models. By using the hardware parameters of commercial off-the-shelf components (Mica2 Motes and CC2520 of Texas Instruments), the energy requirement of a sensor node is quantified. A miniature REHS based on a judicious choice of rectifying diodes is then designed and developed to achieve optimal performance in the Industrial Scientific and Medical (ISM) band centralized at 2.45 GHz. Due to the mismatch between the REHS and the antenna, a band pass filter is designed to reduce reflection losses. A gradient method search is used to optimize the output characteristics of the adapted REHS. At 1 mW of input RF power, the REHS provides an output DC power of 0.57 mW and a comparison with the energy requirement of the node allows the Base Station (BS) to be located at 310 m from the wireless nodes when the Wireless Sensor Network (WSN) has 100 nodes evenly spread over an area of 300 × 300 m2 and when each round lasts 10 min. The result shows that the range of the autonomous WSN increases when the controlled physical phenomenon varies very slowly. Having taken into account all the dissipation sources coexisting in a sensor node and using actual measurements of an REHS, this work provides the guidelines for the design of autonomous nodes based on REHS.

A novel piezoelectric micro-generator to power Wireless Sensors Networks in vehicles

This paper proposes an autonomous power supply to feed the nodes of a Wireless Sensor Network (WSN) used in vehicles. The vibration levels detected in a moving vehicle in an urban or semi urban area are used as the primary form of autonomous energy. Measurements show that a maximum power density of -16.9 dB/Hz is observed around 15 Hz for cruising speed up to. Our design is based on a cantilever piezoelectric transducer 90 km/h mechanically adjustable in frequency designed and manufactured to resonate very close to 15 Hz. Experimental results clearly demonstrate a level of energy sufficient to adequately supply power to a wireless sensor node. Specifically, for an optimum load resistance of 73.13 kΩ, a power of 3 μW is achieved by our autonomous supply.

Energy harvesting design for autonomous Wireless Sensors Network applied to trains

Wireless Sensor Networks (WSNs) technology is considered an excellent compromise for supporting monitoring applications on old trains operated by railway systems around the world. Although WSNs are optimized for energy management with regards to sensor nodes and communication protocols, their lifetimes remain limited by battery capacity. Deployment of new sensors or replacement of empty batteries is often required to extend the life of the WSN. These solutions are often expensive and challenging, particularly when the sensors are in unreachable places. Energy harvesting is a promising approach that addresses these issues: it powers WSNs by scavenging energy from the ambient train environment. This paper proposes a system that gathers energy generated by the trains vibration. The objective of this work is designing a harvester according to real measured vibration sources from a train and the energy requirement of a temperature/humidity sensor. Then we propose in this paper a guideline for configuring an autonomous wireless sensor node powered by a piezoelectric vibration energy harvester.

Performance evaluation of wireless sensor node powered by RF energy harvesting

In this paper, a method of designing an autonomous Wireless Sensor Node (WSN) powered by RF energy Harvesting is proposed. The autonomous sensor node is composed of two components, the WSN and the RF energy harvesting system. The RF harvester is based on a rectenna that consists of an antenna associated with a rectifier circuit. The used rectifier circuit is an optimized Schenkel voltage doubler rectifier. The designed harvester show a recovered DC power of 115.7 μW with 0. 27 V of the output voltage at 0 dBm of input power. A material block-level modeling of a WSN in a star topology network is proposed and used to estimate the energetic budget of the node. The sensor node performance is then evaluated regarding packet size and time ratio between standby and active state. It is observed that the recovered RF power allows considering a minimum transmit packet size of 801 bits for applications where measurements are made every 100 s.

High efficiency rectifier for RF energy harvesting in the GSM band

In this paper, a miniature RECtifying antENNA (rectenna) operating in the GSM band is designed and realized. The RF micro-generator consists of a simple rectifier circuit combined with a dipole antenna. The miniaturization of the circuit lies in avoiding the adaptation input filter and in optimizing the transmission lines by the gradient method search. The designed circuit is based on a Schenkel voltage doubler rectifier and Schottky diodes HSMS 2850 of AVAGO and is optimized through electromagnetic simulation software, Agilent ADS 2014 environment. Experimental results show an RF-DC conversion efficiency up to 40% with an output DC voltage of 1.8 V at 10 dBm of input power. A Wireless Power Transmission (WPT) experience demonstrates an average voltage of 22 mV over a distance of 3 m.