RFID device, RFID system and signal distortion pre-compensation process in RFID systems

• US 8,331,864 B2
• Filed: 05/27/2008
• Issued: 12/11/2012
• Est. Priority Date: 05/30/2007
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Witschnig, Harald
• Primary Examiner(s): Dao, Minh D
• Application Number:
  US12/598,623
• Publication Number:
  US 20100134255A1
• Time in Patent Office: 1,659 Days
• Field of Search: 455/63.1, 455/67.13, 455/114.2, 455/501, 455/570, 455/222, 455/226.3, 455/277.2, 455/278.1, 455/296, 340/572.4, 340/572.1, 340/568.1
• US Class Current: 455/63.1
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

In an RFID system an RFID device (2) comprises a device air interface (C2) witha predefined quality factor (Q2) for transmitting wireless carrier and data signals (CS) being transmitted to a remote RFID transponder(1) comprising a transponder air interface (C1) with a predefined quality factor (Q1). Carrier and data signal pre-compensation means (3) are arranged between the device air interface (C2) and data signal processing means (4), wherein the carrier and data signal pre-compensation means (3) are adapted to pre-compensate signal distortions of the carrier and data signals (CS) caused by the quality factors (Q2, Q1) of the device air interface (C2) and the transponder air interface (C1) of the RFID device (2) and the RFID transponder(1), respectively.

Claims

1. An RFID device comprising a device air interface with a predefined quality factor for transmitting wireless carrier and data signals to a remote RFID transponder comprising a transponder air interface with a predefined quality factor, wherein carrier and data signal pre-compensation means are arranged between the device air interface and data signal processing means, wherein the data signal pre-compensation means are adapted to pre-compensate signal distortions of the carrier and data signals arising during transmission caused by the quality factors of the device air interface and the transponder air interface of the RFID device and the RFID transponder, respectively.

2. The RFID device as claimed in claim 1, wherein the carrier and data signal pre-compensation means comprise a filter with inverse channel characteristics, e.g. having a transfer function following a Zero Forcing Criterion, in respect of the transfer function of the air interfaces of the RFID transponder and the RFID device and optionally of an air transmission path between said air interfaces.

3. The RFID device as claimed in claim 1, wherein the carrier and data signal pre-compensation means have a transfer function following a Minimum Mean Square Error (MMSE) Criterion in respect of the transfer function of the air interfaces of the RFID transponder and the RFID device and optionally of the air transmission path.

4. The RFID device as claimed in claim 1, wherein the carrier and data signal pre-compensation means comprise a digital filter and a digital/analog converter.

5. The RFID device as claimed in claim 4, wherein the digital filter is designed as a Finite Impulse Response filter.

6. The RFID device as claimed in claim 1, wherein the carrier and data signal pre-compensation means comprise an analog filter, e.g. an analog filter with an inverse channel characteristics.

7. The RFID device as claimed in claim 1, being configured either as an RFID reader or an NFC device.

8. An RFID system comprising an RFID device as claimed in claim 1 and at least one RFID transponder.

9. A process for pre-compensating distortions of wirelessly transmitted carrier and data signals in an RFID system comprising an RFID device with a device air interface for transmitting wireless carrier and data signals and at least one RFID transponder with a transponder air interface, wherein the pre-compensating process comprises determining a quality factor of the device air interface of the RFID device, determining a quality factor of the transponder air interface of the RFID transponder, determining a pre-compensation function being adapted to pre-compensate signal distortions of the carrier and data signals arising during transmission to the device air interface caused by the quality factors of the transponder air interface and the device air interface and applying the pre-compensation function to the carrier and data signals to be transmitted.

10. The pre-compensation process as claimed in claim 9, wherein the pre-compensation function has inverse channel characteristics.

11. The pre-compensation process as claimed in claim 9, wherein the equalization function is determined to have a transfer function following a Minimum Mean Square Error Criterion in respect of the transfer function of the air interfaces of the RFID transponder and the RFID device and optionally of the air transmission path.

12. The pre-compensation process as claimed in claim 9, wherein the pre-compensation process is carried out by digital filtering of the carrier and data signals and subsequent digital/analog conversion.

13. The pre-compensation process as claimed in claim 9, wherein the pre-compensation process is carried out by digital/analog conversion and subsequent analog filtering with an inverse channel characteristics