Chapter 24: Powering Communicating Objects

Didier Marquet, France T l com R&D,

France

1 The powering issue

There is not one single problem and a simple solution to the issue of powering the communicating objects, because their perimeter is fuzzy and they have scattered functions over a wide variety of familiar objects (household appliances, clothes, vehicles etc). They have very different uses, and data processing, interfaces, communication, and fixed objects are linked through nano networks (like Bluetooth) with portable objects like PDA, mobile phones, PC.

So their power consumption spreads over a very wide range, from nanowatts to some tenth of a watt, depending on the object, the operating mode (standby or activity) and its interactivity.

To determine the adapted energy sources and the charging methods , we have tried, with our present knowledge, to determine and classify the communicating objects with respect to their power consumption and use constraints. The most difficult objects to power are, obviously, those that are mobile and have higher energy consumption. Because they are not always connected to an electric grid, they must have a pretty long duration autonomy, with the weight and volume are limited. Unfortunately, the energy density of electric power source or storage is rather small.

Energy management must also be manageable for these objects that become more and more ubiquitous in our environment.

The power supply of these objects consists of a complex chain with one part internal to the object (battery + safety circuit), internal power management (activity control, energy level-metering, fault detection), and a second external part, an intelligent charger, a power distribution network (electricity mains, fuel pellet resellers ), and external management (charge level, ageing level of power sources) etc.

This approach to the powering of communicating objects may help to indicate future ways for future development.