R & D

Action 1 : Network Energy Autonomy.

A sensor network consists /is composed of a set of elements called”nodes”.

These nodes are composed of :

• Wireless communication interfaces to communicate either between them or with the base station, which retrieves the information transmitted by the nodes to the database
• Sensors, that can be of different natures (temperature, movement, light, wind, etc…). These sensors will provide the information that will be fed back into the database.

Enable the network to be autonomous

For this, the CARERC team is working on :

• Network software optimization : various methods relating to the transmission of information in the network are the subject of doctoral work at the LE²P laboratory , in order to optimize the energy consumed by a node through time.
• Low power protocols are used by the nodes in order to minimize the energy consumption; then some additionnal wake-up mechanism can be implemented using external signals .

Energy recovery for on-board batteries

Energy recovery solutions will be installed on the nodes to recharge the on-board batteries. In addition to the solar resource, the team is working, as part of LE²P’s research activities, on a particular source : wireless energy transmission.

The principle is to recover energy from the electromagnetic waves around the laboratory, transform it into direct voltage and store it in a battery. To do this, the CARERC team use rectifier antennas called “rectena” as well as charge pump circuits to accumulate the low voltage levels recovered.

Action 2 : Electromagnetic power level sensor implementation

In order to perform electromagnetic mapping, an electromagnetic power measurement tool in a given space will be implemented. For this, several solutions have been studied, developed and under development.

The first one consists in measuring the RSSI level (Received Signal Strength Indication) at each sensor network’s node.  This measurement is made through the antenna used by the node for its communications and provides information on the power level of the electromagnetic waves received by the node in its communication band.

The second is the use of commercial integrated circuits such as logarithmic sensors (coupled with low noise amplifiers and possibly a mixer) that produce a proportional voltage to the input power level. After calibration of these circuits it is possible, from the measured voltage level, to return to the electromagnetic power level.

An integrated circuit embodying these various functions is to be realized in an leading-edge technology. That will allow to free itself from losses due to the adaptations of the various circuits used in the previous solution.

Action 3 : 3d storage and visualization of measured data

All the measured data will then be stored in a Big data tool. This database will be able to adapt to the different types of data that will be uploaded via the network.

Once this data stored correctly, the CARERC team will be able to visualize it, first of all in order  to monitorate the quality of measurement and the proper functioning of the network ; Then to visualize the electromagnetic power level measured in the sensor network deployment space.

It is intended for this visualization to use 3D web tools.