Centre National De La Recherche Scientifique

Time Reversal Communications

Ecole Superieure De Physique Et De Chimie Industrielles De La Ville De Paris

Université Paris 7—denis Diderot

Centre National De La Recherche (cnrs)

Centre National De La Recherche Scientifique-cnrs

Orange Sa

Avantix

Julien De Rosny

Mathias Fink

Geoffroy Lerosey

Arnaud Tourin

Fabrice Lemoult

Arnaud Derode

Christian Leray

Ourir Abdel Waheb

Nissem Selmene

Dinh-Thuy Phan-Huy

Ourir Abdelwaheb

The present invention relates to an ambient backscattering communication system (), the communication system () comprising:

Ambient backscattering communication system, associated apparatus and method

A device () for receiving and/or emitting an electromagnetic wave, comprising a medium () of dielectric material, a plurality of passive resonant elements () incorporated inside said medium, the plurality of passive resonant elements () comprising a frequency band-gap, two neighbor passive resonant elements belonging to the plurality being spaced apart from each other of a first distance lower than &#x3bb;/4, and at least one active resonant element () incorporated inside said plurality, said active resonant element () having a second structure different from a first structure of the passive resonant elements (), so that said active resonant element () has at least a second resonance frequency comprised inside the frequency band-gap of said plurality of passive elements ().

Device for receiving and/or emitting a wave, a system comprising the device, and use of such device

A system for illuminating an object with a wave or for imaging an object with a wave comprises a lens, a plurality of transducers and a control unit connected to the plurality of transducers. The lens comprises a plurality of resonator elements incorporated inside a medium and is able to convert a near field wave of the lens to a far field wave, or reciprocally. The resonator elements are at a sub wavelength distance from each others. The control unit provides signals to the transducers so that a plurality of points on the object are illuminated as desired, or obtains signals from the transducers to build an image of a plurality of points of the object. The points are at sub wavelength distance from each others.

System for illuminating an object with a wave or for imaging an object with a wave

A device for receiving and/or emitting an electromagnetic wave having a free space wavelength &#x3bb;comprised between 1 mm and 10 cm, comprising a medium () of solid dielectric material and the free space wavelength &#x3bb;corresponding to a wavelength &#x3bb; inside the medium, a plurality of conductor elements () incorporated inside the medium and spaced apart from each other of a distance lower than &#x3bb;/10, and one antenna element (). The conductor elements form small loop elements. A tuned conductor element among the conductor elements has a first end at a distance from the antenna element which is lower than &#x3bb;/10, and has an electric resonance frequency corresponding to the wavelength &#x3bb;.

Device for receiving and/or emitting an electromagnetic wave, system comprising said device, and use of such device

A device for receiving and/or emitting an electromagnetic wave having a free space wavelength &#x3bb;comprised between 1 mm and 10 cm, comprising a medium () of solid dielectric material and the free space wavelength &#x3bb;corresponding to a wavelength &#x3bb; inside the medium, a plurality of conductor elements () incorporated inside the medium and spaced apart from each other of a distance lower than &#x3bb;/10, and one antenna element (). The conductor elements are not loop elements. A tuned conductor element among the conductor elements has a first end at a distance from the antenna element which is lower than &#x3bb;/10, and has a length Hadapted to generate an electromagnetic resonance in the tuned conductor element corresponding to the wavelength &#x3bb;.

A method for transmitting digital data on a communication channel, between a transmitter base comprising N transmission antennas and K receivers. A signal carrier of frequency fand M sub-carriers of index m are used, adapted to transport K streams of digital data sin parallel between the transmitter base and each receiver. The method comprises a step in which N.M complex symbols t(m) are calculated from K.M symbols s(m), by where * denotes a complex conjugate, H(m) is a complex value estimating the transfer function of the communication channel between the transmission antenna n and the receiving antenna k at a corresponding frequency of the sub-carrier m, and &#x3b1;is a normalization coefficient.

Method for transmitting digital data, and transmitter base implementing such a method

According to the invention, a wave, corresponding to a signal s(t) may be temporally inverted by application of a first transformation to lower the central frequency thereof to produce a first set of transformed signals Ki(t) then a second set of transformed signals K'i(t) is produced representing the temporal inversion signal s(&#x2212;t) and a third transformation is applied to said second set to generate the temporally-inverted signal s(&#x2212;t)

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Nogent-Sur-Marne, France

Julien De Rosny