Near Field Communication Method of Detection of a Tag Presence by a Tag Reader

• US 20150303997A1
• Filed: 11/20/2013
• Published: 10/22/2015
• Est. Priority Date: 11/27/2012
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: ST-Ericcson SA (Telefonaktiebolaget LM Ericsson)
• Inventors: DHAYNI, Achraf
• Granted Patent: US 9,729,209 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06K 7/10128 the step consisting of detection of the presence of one or more record carriers in the vicinity of the interrogation device
• CPC Class Codes: G06K 7/10237 the reader and the record carrier being capable of selectively switching between reader and record carrier appearance, e.g. in near field communication [NFC] devices where the NFC device may function as an RFID reader or as an RFID tag
• CPC Class Codes: G06K 7/10297 arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092 cryptographic protocols H04L9/00; network security protocols H04L63/00; real-time communication protocols in data switching networks H04L65/00; network protocols for data switching network services H04L67/00
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

The invention concerns a Near Field Communication method of detection of a tag presence by a tag reader, comprising: stimulating (S2) the transmitter of the reader so as to generate an impulse response of said transmitter, evaluating (S3) the generated impulse response of said transmitter, assessing (S4), from the evaluated impulse response of said transmitter, the presence (S5) or the absence (S6) of a tag.

Claims

1. A Near Field Communication method of detection of a tag (6) presence by a tag reader, comprising:

stimulating the transmitter of the reader so as to generate an impulse response of said transmitter,

evaluating the generated impulse response of said transmitter, and

assessing, from the evaluated impulse response of said transmitter, the presence or the absence of a tag.

2. A Near Field Communication detection method according to claim 1, wherein said assessing comprises:

comparing said evaluated impulse response of said transmitter to a predetermined envelope, and

deducing, either presence of a tag if said evaluated impulse response of said transmitter is completely within said predetermined envelope or absence of a tag if said evaluated impulse response of said transmitter is at least partly outside said predetermined envelope.

3. A Near Field Communication detection method according to claim 2, wherein:

said predetermined envelope extends between a predetermined minimal impulse response and a predetermined maximal impulse response, both predetermined impulse responses being such that any impulse response due to any tag of a predetermined set of tags all able to communicate with said reader will be simultaneously above said predetermined minimal impulse response and below said predetermined maximal impulse response.

4. A Near Field Communication detection method according to claim 2, wherein:

said evaluated impulse response is digital, and

absence of a tag is deduced if at least one sample of said digital evaluated impulse response of said transmitter is outside said predetermined envelope.

5. A Near Field Communication detection method according to claim 1, wherein said evaluating comprises:

digitally evaluating said generated impulse response.

6. A Near Field Communication detection method according to claim 1, wherein said evaluating comprises:

cross-correlating a signal representative of a signal delivered at an output of said transmitter with a signal representative of a signal which has been sent to an input of said transmitter to generate said impulse response.

7. A Near Field Communication detection method according to claim 1, wherein said stimulating comprises:

sending, to an input of said transmitter, a signal representative of a pseudo-random binary sequence.

8. A Near Field Communication detection method according to claim 7, wherein:

said pseudo-random binary sequence is a maximal length sequence preferably generated by a linear feedback shift register.

9. A Near Field Communication detection method according to claim 7, wherein:

said maximal length sequence parameters are chosen such that said reader emits a periodic polling signal for tag detection which emission duration lasts between 1% and 10% of total polling time, preferably between 5% and 10% of total polling time.

10. A Near Field Communication detection method according to claim 8, wherein:

the order of said maximal length sequence ranges from 13 to 16.

11. A Near Field Communication detection method according to claim 8, wherein:

the clock frequency of said maximal length sequence ranges from 1 Mhz to 1.5 Mhz.

12. A Near Field Communication detection method according to claim 1, wherein said stimulating comprises:

sending, to an input of said transmitter, a stimulating signal such as the autocorrelation of said stimulating signal is close enough to a Dirac impulse so that a convolution of a signal representative of a signal delivered at an output of said transmitter with a signal representative of said stimulating signal gives substantially said generated impulse response.

13. A Near Field Communication detection method according to claim 1, wherein said stimulating, said evaluating and said assessing are all performed on chip of said reader.

14. A computer program product comprising a computer readable medium, having thereon a computer program comprising program instructions, the computer program being loadable into a data-processing unit and adapted to cause execution of the method according to any of preceding claims when the computer program is run by the data-processing unit.

15. A Near Field Communication tag reader, comprising:

an emitter adapted to send a stimulating signal to an input of the transmitter of the reader so as to generate an impulse response of said transmitter,

an evaluator adapted to evaluate the generated impulse response of said transmitter,

an assessor adapted to assess, from the evaluated impulse response of said transmitter, the presence or the absence of a tag.