Method and System for Aiding Environmental Characterization by Ultra-Wideband Radiofrequency Signals

• US 20110163905A1
• Filed: 12/15/2008
• Published: 07/07/2011
• Est. Priority Date: 12/18/2007
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: French Alternative Energies and Atomic Energy Commission
• Inventors: Uguen, Bernard, Tchoffo-Talom, Friedman, La Tosa, Vincenzo, Denis, Benoît
• Granted Patent: US 8,674,871 B2
• Time in Patent Office: Days
• US Class Current: 342/21
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01S 7/412 based on a comparison between measured values and known or stored values

Abstract

The invention relates to environmental characterization on the basis of an Ultra Wide Band (UWB) radiofrequency communication network. Pulses are emitted and the waveform received is compared with predicted waveforms corresponding to well determined interactions between the wave and its environment. The comparison is done by searching for maximum temporal correlation. The interactions can be notably reflections of the wave on walls or obstacles. The deformations are very dependent on the nature of the materials and directions in which the pulses are emitted and received. If predicted waveforms are stored for various pairs of direction of emission and of reception, it is possible through these correlation operations to find where a wall which gave rise to a reflection is situated.

Claims

1. A method for aiding environmental characterization using an ultra-wideband multi-node wireless communication network, comprising the emission of impulse radiofrequency signals by a radio emitter node having an emission antenna and the reception of the corresponding signal by a radio receiver node different from the emitter node and having a reception antenna, the method comprising:

the storage, in a memory associated with the receiver, of a series of descriptors of predicted elementary waveforms, each descriptor corresponding to an elementary waveform expected at the level of the receiver for a determined interaction between the electromagnetic wave emitted by the emission antenna and constituent materials of surfaces potentially present in the environment which may affect the propagation of the wave up to the receiver,

the digitization of the signal received and the determination of several temporal portions of the waveform of signal received which, because of their temporal distribution of energy, are apt to contain one of the predicted waveforms and to correspond to the arrival of one and the same impulse signal having followed several paths of different orientations between the emitter node and the receiver node,

the comparison between on the one hand a descriptor of the signal received for each of these temporal portions and on the other hand several descriptors of predicted waveforms, which descriptors are stored in the memory or calculated on the fly on the basis of the stored descriptors, these descriptors being dependent on an angle of emission and/or of reception.

the selection for each temporal portion of a descriptor for which the comparison indicates a resemblance between the predicted form and the temporal portion of form received,

the storage of an item of information about each descriptor thus selected and about the position over time of the corresponding temporal portion, representing an item of information regarding presence and position in the environment of a noteworthy object which causes an interaction corresponding to the interaction associated with the selected descriptor.

2. The method as claimed in claim 1, wherein certain descriptors of predicted waveform are each associated with a triple of determined angular parameters, which are a direction of emission, referenced with respect to the emission antenna, and a direction of reception, referenced with respect to the reception antenna, an angle of incidence on a reflecting surface, referenced with respect to the direction normal to the surface, and with an electromagnetic parameter which carries an item of information about the type of material constituting the reflecting surface, the waveform associated with this descriptor being the waveform predicted in the case where the reception antenna receives along said direction of reception an impulse electromagnetic wave emitted by the emission antenna along said direction of emission, after a reflection at this angle of incidence on a surface whose electromagnetic characteristics are represented by said electromagnetic parameter.

3. The method as claimed in claim 2, wherein the presence and position information represents a position and an orientation of a surface reflecting the electromagnetic waves, the position being the intersection of a straight line passing through the emission antenna and directed along the direction of emission corresponding to the selected descriptor and of a straight line passing through the reception antenna and directed along the direction of reception corresponding to the selected descriptor, and the orientation being that of a plane perpendicular to the bisector of these two straight lines.

4. The method as claimed in claim 1, wherein the temporal position of a portion of waveform received, for which a descriptor has been selected, is determined and used to establish or confirm the information regarding position of the noteworthy object.

5. The method as claimed in claim 1, wherein certain waveform descriptors are associated with a triple of angular parameters which are a direction of emission referenced with respect to the emission antenna, a direction of reception referenced with respect to the reception antenna, and an angle of incidence on a reflecting surface, referenced with respect to the direction normal to the surface.

6. The method as claimed in claim 1, wherein certain descriptors are associated with particular materials and represent the predicted waveforms associated with an electromagnetic wave diffraction on the edges of objects made from these materials.

7. The method as claimed in claim 1, wherein the memory contains descriptors of electromagnetic characteristics of the antennas used and of various materials and descriptors of probability distributions induced by certain geometric constraints.

8. The method as claimed in claim 1, wherein the receiver provides, in a facility for predicting waveforms, descriptors of complex waveforms on the basis of descriptors contained in the memory.

9. The method as claimed in claim 1, wherein the comparison between the waveform of signal received and the predicted waveforms whose descriptors are in the memory is done by comparing descriptors stored in the memory and descriptors calculated by the receiver on the basis of the waveform received.

10. The method as claimed in claim 1, wherein the digitization of waveforms of signal received is performed for a series of pulses emitted successively by the emission antenna.

11. The method as claimed in claim 10, wherein the series of pulses is a series emitted during the header of a communication message dispatched by the radio emitter node to the radio receiver node, so as to perform an environmental characterization during the current use of the communication network.

12. The method as claimed in claim 1, wherein, after selection of a particular descriptor for a determined temporal portion of the waveform received, the predicted waveform corresponding to this descriptor is subtracted from the waveform received, while tailoring it to this temporal portion, and the determination of temporal portions and the comparison with predicted forms is recommenced, using the result of this subtraction as signal received.

13. The method as claimed in claim 12, wherein the subtraction, the determination of temporal portions and the comparison with predicted forms is iteratively recommenced.

14. The method as claimed in claim 12, wherein the determination of temporal portions and the comparison with predicted waveforms are performed in parallel for several choices of descriptors corresponding to one and the same wave propagation path.

15. The method as claimed in claim 1, wherein the radio emitter node emits several identical successive impulse signals shifted by determined time intervals, a coherent integration of the signals received is performed by compensating at the receiver level for the time intervals which separate them, so as to produce an equivalent signal received having an improved signal/noise ratio, and the waveform of this equivalent signal received is used to perform the comparisons with the predicted waveforms.

16. The method as claimed in claim 1, comprising an iteration of the calculations for each time window corresponding to a noteworthy wave path present in the signal received, and the estimation of a probable environmental configuration as a function of the information detected for each time window.

17. A wireless communication system comprising a network of several ultra-wideband emission/reception nodes, including at least one node having an emission antenna so as to emit in the network impulse communication signals, and at least one node, different from the emitter node and having a reception antenna capable of receiving signals corresponding to the signals emitted, the system comprising:

a memory containing a series of descriptors of predicted waveforms, each descriptor corresponding to an elementary signal waveform expected at the receiver node for a determined interaction between the electromagnetic wave emitted by the emission antenna and objects potentially present in the environment which may affect the transmission of this wave in its path up to its reception by the receiver,

digitization means for digitizing the waveform of a signal received and means for determining several temporal portions of the waveform of signal received which, because of their temporal distribution of energy, are apt to contain one of the predicted waveforms and to correspond to the arrival of one and the same impulse signal having followed several paths of different orientations between the emitter node and the receiver node,

comparison means for comparing between on the one hand a descriptor of the signal received for each of these temporal portions and on the other hand several descriptors of predicted waveforms, which descriptors are stored in the memory or calculated on the fly on the basis of the stored descriptors,

means for selecting, for each temporal portion, a descriptor for which the comparison indicates a resemblance between the corresponding predicted form and the temporal portion of signal received,

and means for storing an item of information about each descriptor thus selected and the position over time of the corresponding temporal portion, representing an item of information regarding presence and position in the environment of a noteworthy object which causes an interaction corresponding to the interaction associated with the selected descriptor.

18. The system as claimed in claim 17, comprising means for iterating the calculations for each time window corresponding to a noteworthy wave path present in the signal received, and the estimation of a probable environmental configuration as a function of the information detected for each temporal portion.

19. The system as claimed in claim 18, wherein certain waveform descriptors are associated with a triple of angular parameters which are a direction of emission referenced with respect to the emission antenna, a direction of reception referenced with respect to the reception antenna, and an angle of incidence on a reflecting surface, referenced with respect to the direction normal to the surface.

20. The system as claimed in claim 17, comprising a function for predicting descriptors of complex waveforms on the basis of the descriptors of elementary waveforms and of descriptors of electromagnetic characteristics of materials, the two sets of descriptors being contained in the memory.

21. The system as claimed in claim 17, further comprising means for optimizing the routing of the communication in the network on the basis of the environmental information obtained.

22. The system as claimed in claim 17, further comprising means for aiding the orientation of the blind or of persons placed in conditions of poor visibility in a building, on the basis of the environmental information obtained.

23. The system as claimed in claim 17, further comprising means for optimizing a spatial equalization of a high fidelity music rig or of some other public address sound system in a building, on the basis of the environmental information obtained.

24. The system as claimed in claim 17, further comprising means for detecting changes in relation to physical parameters such as the temperature or the presence of gas or smoke or else the presence of intruders, including for the production of an alarm, on the basis of the environmental information obtained.