Method and apparatus for electronic item identification in a communication system using known source parameters

• US 20040179588A1
• Filed: 03/11/2003
• Published: 09/16/2004
• Est. Priority Date: 03/11/2003
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Gurney, David P., Collins, Timothy, Kuffner, Stephen, Eastmond, Bruce
• Granted Patent: US 6,970,518 B2
• Time in Patent Office: Days
• US Class Current: 375/224
• 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
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous

Abstract

A communications method including the steps of: receiving signals from at least one signal source during a first signal source transmission; estimating at least one signal source parameter based on the received signals during the first signal source transmission; receiving signals from at least one signal source during a second signal source transmission; and determining a difference between the first and second signal source transmissions using the at least one estimated signal source parameter.

Claims

1. A communications method comprising the steps of:

receiving signals from at least one signal source during a first signal source transmission;

estimating at least one signal source parameter based on said received signals during said first signal source transmission;

receiving signals from at least one signal source during a second signal source transmission; and

determining a difference between said first and second signal source transmissions using said at least one estimated signal source parameter.

2. The method of claim 1, wherein at least a portion of the received signal from a signal source during said first signal source transmission is also received during said second signal source transmission.

3. The method of claim 1, wherein the step of determining the difference between the first and second signal source transmissions comprises suppressing at least one expected signal as a function of said at least one estimated signal source parameter.

4. The method of claim 3, wherein said at least one expected signal is suppressed by performing a collision mitigation algorithm using said at least one estimated signal source parameter.

5. The method of claim 4, wherein the collision mitigation algorithm is a forward collision mitigation algorithm.

6. The method of claim 4, wherein the collision mitigation algorithm is a bi-directional collision mitigation algorithm.

7. The method of claim 3, wherein said at least one expected signal is suppressed from at least one transmission pass of a multiple pass transmission algorithm.

8. The method of claim 1, wherein the step of determining the difference between said first and second signal source transmissions comprises determining that a signal source transmitting during said first signal source transmission is no longer transmitting during said second signal source transmission.

9. The method of claim 8, wherein detecting a negative image of a received data sequence from a signal source during said first signal source transmission is used to determine that the signal source is no longer transmitting during said second signal source transmission.

10. The method of claim 1, wherein the step of estimating at least one signal source parameter is performed for each signal source during said first signal source transmission.

11. The method of claim 1, wherein the step of receiving signals from at least one signal source during said first signal source transmission comprises performing a complete read cycle.

12. The method of claim 1, wherein the step of estimating at least one signal source parameter comprises estimating a received signal amplitude for a signal source.

13. The method of claim 1, wherein the step of estimating at least one signal source parameter comprises estimating a received signal phase for a signal source.

14. The method of claim 1, wherein the step of estimating at least one signal source parameter comprises demodulating a received signal data sequence for a signal source.

15. The method of claim 14, wherein at least a portion of said data sequence determines a communications channel over which the data sequence is received.

16. The method of claim 1, wherein the signal sources transmit simultaneously during each said signal source transmission according to a multiple pass transmission algorithm having at least one transmission pass.

17. The method of claim 1, wherein the step of determining the difference between the first and second signal source transmissions comprises determining whether at least one new signal source is transmitting during said second signal source transmission.

18. The method of claim 17, wherein determining that a new signal source is transmitting during said second signal source transmission involves demodulating a received signal data sequence for said new signal source.

19. The method of claim 1, wherein the step of determining the difference between said first and second signal source transmissions comprises determining a difference between a received data sequence from a signal source in said first signal source transmission and said received data sequence in said second signal source transmission.

20. An electronic item identification communications system comprising:

at least one source device having a signal source; and

at least one destination device adapted for receiving signals from at least one signal source during a first signal source transmission, estimating at least one signal source parameter based on said received signals during said first signal source transmission, receiving signals from at least one signal source during a second signal source transmission, and determining a difference between said first and second signal source transmissions using said at least one estimated signal source parameter.

21. The system of claim 20, wherein said at least one source device transmits in accordance with a multiple pass transmission algorithm.

22. The system of claim 20, wherein said destination device is further adapted for performing a complete read cycle for receiving signals during said first signal source transmission.

23. The system of claim 22, wherein said destination device is further adapted for performing a complete read cycle for receiving signals during said second signal source transmission upon determining that an estimated signal source parameter is invalid.

24. The system of claim 20, wherein said destination device is further adapted for performing a collision mitigation algorithm using said at least one estimated signal source parameter to determine the difference between said first and second signal source transmissions.

25. The system of claim 24, wherein said collision mitigation algorithm is a forward collision mitigation algorithm.

26. The system of claim 24, wherein said collision mitigation algorithm is a bi-directional collision mitigation algorithm.

27. The system of claim 20 further comprising at least one other device adapted for receiving from said destination device the difference between said first and second signal source transmissions.

28. The system of claim 27, wherein said at least one other device is a central controller device.

29. The system of claim 20, wherein said at least one destination device includes a network node for enabling communication to at least one other network node.

30. The system of claim 29 further comprising a central controller device, wherein at least one said network node is adapted for communicating with said central controller device.