Body-Coupling communication

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The Body-Coupling Communication (a.k.a BCC) study has started in the early 1990 years and numerous papers have been published within initiatives as the "wearable computing group" and later on in the IST Ambient Networks Project (AmI).

Modulated electric field may carry a signal on the user body according to multiple modes. The capacitive coupling is the mode used by the eGo device.

The main BCC mode is illustrated by the figure 1

Figure 1: BCC transmission

This mode uses the capacitance between the devices and the ground surface (green electric field lines) which could be for example the earth ground. In the figure 1 example, the signal is flowing from a transmitter(left side) to a receiver (right side).

The channel of communication is symmetrical then the data communication can be bidirectionnal.

The closer the transmitter or the receiver and the earth ground are, the lower is the signal attenuation. The channel of communication is symmetrical and if the frequency signal is bellow 10 Mhz then the signal is not radiating and the user body does not act as an antenna.

A direct contact between the BCC antenna and the user's skin is not necessary (e.g gloves, shoes, garments...).

Data rates between 100 Kbit/s  up to 10 Mbit/s can be expected. the eGo principle does not require high data rate on the BCC bearer.

The eGo principle uses only a one-way data communication from the eGo compliant device to the eGo device. Few hundred bits are quickly sent to the eGo device then the BCC bearer is not used for transfering application data but only the essential data allowing the fast pairing of the UWB bearer.

 
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