RFID PROTOCOL FOR IMPROVED TAG-READER COMMUNICATIONS INTEGRITY

• US 20080165003A1
• Filed: 01/04/2007
• Published: 07/10/2008
• Est. Priority Date: 01/04/2007
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Johnson, Timothy Lee, Graichen, Catherine
• Granted Patent: US 8,120,463 B2
• Time in Patent Office: Days
• US Class Current: 340/572.1
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal

Abstract

The present invention provides a means by which the reliability of communication between any RFID reader and tag in an RFID system is improved by using an “interleaved parity” algorithm. The improved reliability is obtained by computing, on one RFID device, an interleaved parity code for a message, sending the message with the code from the RFID device, receiving the message on the other RFID device which computes another interleaved parity code for the received message. The two parity codes are compared and if the codes are the same, the message can be parsed and interpreted. If the codes indicate that one bit of the message is incorrect, the incorrect bit is corrected and the message is parsed and interpreted. Otherwise, a request for a new message is sent to the RFID device, and, if appropriate, an indication of two erroneous bits is also sent.

Claims

1. A method for improving the reliability of communication in an RFID system, said method comprising the steps of:

computing on a first device a first interleaved parity code for a message;

sending the message and the first interleaved parity code from the first device;

receiving the message and interleaved parity code at a second device;

computing on the second device a second interleaved parity code for the message;

comparing the first interleaved parity code and the second interleaved parity code; and

based on the comparison, performing one of;

parsing and interpreting the message;

detecting an error in the message and requesting a new message from the first device; and

requesting a new message from the first device.

2. The method according to claim 1, wherein the first device is an RFID reader and the second device is an RFID tag.

3. The method according to claim 2, wherein writing onto the tag requires the tag to confirm a request for writing and receive an acknowledgement to execute.

4. The method according to claim 2, wherein the tag is an active tag.

5. The method according to claim 1, wherein the first device is an RFID tag and the second device is an RFID reader.

6. The method according to claim 5, wherein writing onto the tag requires the tag to confirm a request for writing and receive an acknowledgement to execute.

7. The method according to claim 5, wherein the tag is an active tag.

8. The method according to claim 1, wherein the RFID system is a multi-reader system.

9. The method according to claim 1, wherein the RFID system is a multi-tag system.

10. The method according to claim 1, wherein based on the comparison, the performing step further includes correcting the message and parsing and interpreting the corrected message.

11. The method according to claim 1, wherein the error detected is in two bits of the message.

12. The method according to claim 1, wherein the first interleaved parity code further comprises a parity signature for the message where each bit of the signature is based on computing parity of selected bits of the message.

13. The method according to claim 1, wherein the message comprises command encodings having at least a two bit difference between each command and data type.

14. The method according to claim 1, wherein the message comprises one or more 32 bit blocks and a last bit of the one or more 32 bit blocks is not used.

15. The method according to claim 1, wherein the message comprises a command, and if the command requests data, the command and the data are returned.

16. A computer readable medium having computer readable program code for operating on a computer for improving the reliability of communication in an RFID system, said computer readable program code comprising the steps of:

computing on a first device a first interleaved parity code for a message;

sending the message and the first interleaved parity code from the first device;

receiving the message and interleaved parity code at a second device;

computing on the second device a second interleaved parity code for the message;

comparing the first interleaved parity code and the second interleaved parity code; and

based on the comparison, performing one of;

parsing and interpreting the message;

detecting an error in the message and requesting a new message from the first device; and

requesting a new message from the first device.

17. The computer readable program code of claim 16, wherein the first device is an RFID reader and the second device is an RFID tag.

18. The computer readable program code of claim 17, wherein writing onto the tag requires the tag to confirm a request for writing and receive an acknowledgement to execute.

19. The computer readable program code of claim 17, wherein the tag is an active tag.

20. The computer readable program code of claim 16, wherein the first device is an RFID tag and the second device is an RFID reader.

21. The computer readable program code of claim 20, wherein writing onto the tag requires the tag to confirm a request for writing and receive an acknowledgement to execute.

22. The computer readable program code of claim 20, wherein the tag is an active tag.

23. The computer readable program code of claim 16, wherein the RFID system is a multi-reader system.

24. The computer readable program code of claim 16, wherein the RFID system is a multi-tag system.

25. The computer readable program code of claim 16, wherein based on the comparison, the performing step further includes correcting the message and parsing and interpreting the corrected message.

26. The computer readable program code of claim 16, wherein the error detected is in two bits of the message.

27. The computer readable program code of claim 16, wherein the first interleaved parity code further comprises a parity signature for the message where each bit of the signature is based on computing parity of selected bits of the message.

28. The computer readable program code of claim 16, wherein the message comprises command encodings having at least a two bit difference between each command and data type.

29. The computer readable program code of claim 16, wherein the message comprises one or more 32 bit blocks and a last bit of the one or more 32 bit blocks is not used.

30. The computer readable program code of claim 16, wherein the message comprises a command, and if the command requests data, the command and the data are returned.

31. A system for improving the reliability of communication in an RFID system, said system comprising:

a first device for computing a first interleaved parity code for a message; and

a second device for computing a second interleaved parity code for the message, wherein said first device sends the message and the first interleaved parity code to the second device, the second device compares the first interleaved parity code and the second interleaved parity code and based on the comparison, the second device performs one of;

parsing and interpreting the message;

detecting an error in the message and requesting a new message from the first device; and

requesting a new message from the first device.

32. The system according to claim 32, wherein the RFID system is a multi-reader system.

33. The system according to claim 32, wherein the RFID system is a multi-tag system.

34. The system according to claim 32, wherein the first device is an active tag and the second device is an RFID reader.

35. The system according to claim 32, wherein the second device is an active tag and the first device is an RFID reader.