SYSTEM FOR READING INFORMATION TRANSMITTED FROM A TRANSPONDER

• US 20110122015A1
• Filed: 07/30/2009
• Published: 05/26/2011
• Est. Priority Date: 07/30/2008
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Muehlmann, Ulrich
• Granted Patent: US 8,638,255 B2
• Time in Patent Office: Days
• US Class Current: 342/118
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station

Abstract

A reader device (110) for reading information transmitted from a transponder (130) via a backscatter signal (132) generated by the transponder (130) in response to a stimulus signal (112) generated by the reader device (110), the reader device (110) comprising a first power estimation unit (114) adapted for estimating a first power value indicative of the power of the stimulus signal (112) at a position of the transponder (130) by evaluating a power information included in the backscatter signal (132), a second power estimation unit (116) adapted for estimating a second power value indicative of the power of the backscatter signal (132) at a position of the reader device (110), and a distance estimation unit (118) adapted for estimating a distance (d₁) between the reader device (110) and the transponder (130) based on the first power value and the second power value.

Claims

1. A reader device for reading information transmitted from a transponder via a backscatter signal generated by the transponder in response to a stimulus signal generated by the reader device, the reader device comprising

a first power estimation unit adapted for estimating a first power value indicative of the power of the stimulus signal at a position of the transponder by evaluating a power information included in the backscatter signal;

a second power estimation unit adapted for estimating a second power value indicative of the power of the backscatter signal at a position of the reader device;

a distance estimation unit adapted for estimating a distance between the reader device and the transponder based on the first power value and the second power value.

2. The reader device according to claim 1, wherein the first power estimation unit is adapted for estimating the first power value by evaluating the backscatter signal based on a predefined or based on a modelled nonlinear transfer function of an available power versus modulation efficiency by which the stimulus signal is manipulated by the transponder.

3. The reader device according to claim 1, wherein the first power estimation unit is adapted for estimating the first power value by evaluating a clock rate of the backscatter signal manipulated by the transponder.

4. The reader device according to claim 1, wherein the second power estimation unit is adapted for estimating the second power value by determining a received signal strength of the backscatter signal at a position of the reader device.

5. The reader device according to claim 1, wherein the distance estimation unit is adapted for estimating the distance between the reader device and the transponder by applying a path-loss-model based on the first power value and the second power value.

6. The reader device according to claim 1, comprising a determination unit adapted for determining whether the backscattering signal belongs to a communication between the reader device and the transponder based on the evaluated distance.

7. The reader device according to claim 1, comprising a determination unit adapted for determining that the backscattering signal belongs to a communication between the reader device and the transponder when the evaluated distance is smaller than a predefined threshold distance.

8. The reader device according to claim 6, comprising a decoding unit adapted for decoding information encoded in the backscattering signal upon determination, by the determination unit, that the backscattering signal belongs to a communication between the reader device and the transponder.

9. The reader device according to claim 1, adapted as a UHF long-range reader device.

14. A communication system, comprising a transponder for transmitting information to a reader device via a backscatter signal generated by the transponder in response to a stimulus s generated by the reader device, the transponder comprising

a backscatter signal generation unit adapted for generating the backscatter signal based on the stimulus signal including power information indicative of the power of the stimulus signal at a position of the transponder;

and

the reader device according to claim 1 for reading information transmitted from the transponder.

10. A transponder for transmitting information to a reader device via a backscatter signal generated by the transponder in response to a stimulus signal generated by the reader device, the transponder comprising

a backscatter signal generation unit adapted for generating the backscatter signal based on the stimulus signal including power information indicative of the power of the stimulus signal at a position of the transponder.

11. The transponder according to claim 10, wherein the backscatter signal generation unit is adapted for generating the backscatter signal by manipulating the stimulus signal in accordance with a nonlinear transfer function of an available power versus modulation efficiency.

12. The transponder according to claim 10, wherein the backscatter signal generation unit is adapted for generating the backscatter signal by manipulating the stimulus signal with a clock rate in accordance with the power of the stimulus signal at a position of the transponder.

13. The transponder according to claim 10, wherein the transponder comprises one of the group consisting of a radio frequency identification tag and a contactless chip card.

15. A method of reading, by a reader device, information transmitted from a transponder via a backscatter signal generated by the transponder in response to a stimulus signal generated by the reader device, the method comprising

estimating a first power value indicative of the power of the stimulus signal at a position of the transponder by evaluating a power information included in the backscatter signal;

estimating a second power value indicative of the power of the backscatter signal at a position of the reader device;

estimating a distance between the reader device and the transponder based on the first power value and the second power value.

16. A non-transitory computer-readable medium, in which a computer program of reading, by a reader device, information transmitted from a transponder is stored, which computer program, when being executed by a processor, is adapted to carry out or control a method according to claim 15.

17. A program element of reading, by a reader device, information transmitted from a transponder, which program element, when being executed by a processor, is adapted to carry out or control a method according to claim 15.