Apparatus and method for processing RFID signals

• US 8,994,506 B2
• Filed: 03/08/2013
• Issued: 03/31/2015
• Est. Priority Date: 03/08/2012
• Status: Expired due to Fees

• Current Assignee: University of British Columbia
• Original Assignee: University of British Columbia
• Inventors: Lampe, Lutz, Hoffmann, Dana
• Primary Examiner(s): Nguyen, Phung
• Application Number:
  US13/791,725
• Publication Number:
  US 20130234834A1
• Time in Patent Office: 753 Days
• Field of Search: 340/10.2, 340/10.1, 340/10.4, 340/13.26, 3405721-5729, 370/527, 370/227, 375/316
• US Class Current: 340/10.2
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/10069 the collision being resolved in the frequency domain, e.g. by hopping from one frequency to the other frequency hopping or spread spectrum techniques H04B7/00
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

A method of processing RFID data packets at an RFID receiver includes performing channel estimation and data detection on a first received RFID data packet in a single-user reception mode, the first RFID data packet being transmitted by a first RFID tag and in response to detection of a second received RFID data packet from a second RFID tag while the first RFID data packet is being processed in the single-user reception mode, performing channel estimation and data detection in a multi-user reception mode to recover data transmitted from both the first and second RFID tags in a collision-less manner.

Claims

1. A method of processing RFID data packets at an RFID receiver, comprising:

performing channel estimation and data detection on a first received RFID data packet in a single-user reception mode, the first RFID data packet being transmitted by a first RFID tag;

acquiring a second received RFID data packet from a second RFID tag while the first RFID data packet is being processed in the single-user reception mode; and

in response to acquiring the second received RFID data packet, performing channel estimation and data detection in a multi-user reception mode to recover data transmitted from both the first and second RFID tags in a collision-less manner;

wherein acquiring the second received RFID data packet comprises using a residual received signal.

2. The method according to claim 1, further comprising:

determining that a preamble of the second received RFID data packet overlaps in time a preamble of the first RFID data packet; and

in response to the determining, improving the channel estimation of the first received RFID data packet determined in the single-user reception mode, prior to performing the channel estimation and the data detection in the multi-user reception mode.

3. The method according to claim 2, wherein improving the channel estimation comprises applying a least-square estimation filter to the first and second received RFID data packets in response to determining that the preamble of the second received RFID data packet overlaps in time with the preamble of the first RFID data packet.

4. The method according to claim 1, further comprising, in the multi-user reception mode, performing a frequency offset estimation for the second received RFID data packet.

5. The method according to claim 1, wherein performing data detection in the multi-user reception mode comprises utilizing widely linear detection in a mode of one of linear multi-user detection, decision-feedback multi-user detection, and maximum-likelihood multi-user detection.

6. The method according to claim 1, wherein the first received data packet and the second received data packet are acquired by applying oversampling or by utilizing multiple RFID antennae.

7. The method according to claim 1, wherein performing data detection in the multi-user reception mode comprises utilizing filters optimized according to criterion from one of zero-forcing and minimum mean-square error.

8. The method according to claim 1, wherein performing data detection in the multi-user reception mode comprises utilizing filters that are adaptively optimized using a recursive algorithm.

9. The method according to claim 1, wherein performing channel estimation in the multi-user reception mode comprises determining an estimate of the interfering data symbols of the first received data packet.

10. An RFID receiver for processing RFID data packets, comprising:

a data packet acquisition unit for receiving RFID data packets transmitted by RFID tags;

a channel estimator; and

a data detector;

wherein the channel estimator and the data detector perform channel estimation and data detection on a first received RFID data packet in a single-user reception mode, the first RFID data packet being transmitted by a first RFID tag; and

wherein the data packet acquisition unit is configured to acquire a second received RFID data packet while the first RFID data packet is being processed in the single-user reception mode, the second RFID data packet being transmitted by a second RFID tag, and, in response to acquiring a second received RFID data packet, the channel estimator and the data detector perform channel estimation and data detection in a multi-user reception mode to recover data transmitted from both the first and second RFID tags in a collision-less manner;

wherein, in the multi-user reception mode, acquiring the second received RFID data packet comprises using a residual received signal.

11. The RFID receiver according to claim 10 further comprising a preamble overlap detector that determines whether a preamble of the second received RFID data packet overlaps in time with a preamble of the first RFID data packet.

12. The RFID receiver according to claim 11, wherein, in the multi-user reception mode, the channel estimator applies a least-square estimation filter to the first and second received RFID data packets in response to the preamble overlap detector determining that the preamble of the second received RFID data packet overlaps in time with the preamble of the first RFID data packet.

13. The RFID receiver according to claim 10, wherein, in the multi-user reception mode, the data detector utilizes widely linear detection in a mode of one of linear multi-user detection, decision-feedback multi-user detection, and maximum-likelihood multi-user detection.

14. The RFID receiver according to claim 10, wherein, in the multi-user reception mode, the data detector utilizes filters optimized according to criterion from one of zero-forcing and minimum mean-square error.

15. The RFID receiver according to claim 10, wherein, in the multi-user reception mode, the data detector utilizes filters that are adaptively optimized using a recursive algorithm.

16. The RFID receiver according to claim 15, wherein the recursive algorithm is one of a least mean squares algorithm and a recursive least squares algorithm.

17. The RFID receiver according to claim 10, wherein, in the multi-user reception mode, the channel estimator determines an estimate of the interfering data symbols of the first received data packet.

18. The RFID receiver according to claim 10, wherein, in the multi-user reception mode, the data packet acquisition unit performs a frequency offset estimation for the second received RFID data packet.