Method and apparatus for efficiently querying and identifying multiple items on a communication channel

• US 20060103505A1
• Filed: 11/21/2005
• Published: 05/18/2006
• Est. Priority Date: 03/16/2001
• Status: Active Grant

• Current Assignee: Robert Hulvey
• Original Assignee: Robert Hulvey
• Inventors: Hulvey, Robert
• Granted Patent: US 7,173,518 B2
• Time in Patent Office: Days
• US Class Current: 340/10.200
• 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 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10049 binary tree

Abstract

Systems and methods for efficiently querying and identifying multiple items on a communication channel are disclosed. The invention is well suited to use with radio frequency identification with interrogation devices and systems that identify radio frequency identification transponders. A depth-first tree traversal protocol algorithm, including commands and symbols, is used to more efficiently interrogate a plurality of transponders in a short amount of time.

Claims

1-29. -29. (canceled)

30. A method for interrogating objects to be identified over a communication medium, wherein the objects provide predetermined responses indicative of object identification numbers and each include a counter, the method comprising the steps of:

sending interrogation signals to and receiving responses from the objects over the communication medium, the interrogation signals operating to interrogate a single digit from the objects to be identified;

recording incomplete identification numbers whenever two or more predetermined responses are received from the objects;

retrieving incomplete identification numbers whenever two or more predetermined responses are received from the objects;

sending a signal to the objects to cause the objects to selectively add a number to their respective counter, wherein the number is determined by each object and is dependent upon one or more previous responses of the object to interrogation signals;

sending a signal to the objects to cause the objects to selectively subtract a number from their respective counter, wherein the number is determined by each object and is dependent upon one or more previous responses of the object to the interrogation signals; and

recording complete identification numbers as they are determined.

31. The method of claim 30, wherein the objects are identified based on a depth-first tree traversal algorithm.

32. The method of claim 31, wherein a speed for determining the identification numbers is deterministic given a set of objects to have their identification numbers determined.

33. The method of claim 30, wherein, in response to interrogation of a signal digit from the objects, each object provides a response regardless of the value of the digit being interrogated.

34. The method of claim 30, wherein the communication channel comprises a radio channel.

35. The method of claim 34, wherein the objects each include an RFID transponder.

36. The method of claim 35, wherein the counter is included in control circuitry for the RFID transponder.

37. The method of claim 30, wherein the communication channel comprises a wired communication channel.

38. The method of claim 30, wherein values of the counters selectively inhibit objects from responding to interrogation signals.

39. The method of claim 30, wherein the selective inhibit occurs as part of a depth-first tree traversal algorithm.

40. A method for interrogating objects to be identified over a communication medium, wherein the objects provide predetermined responses indicative of object identification numbers and each includes a counter, the interrogation comprising the steps of:

sending signals to and receiving signals from the objects over the communication medium;

recording and later retrieving incomplete identification numbers whenever two or more predetermined responses are received from the objects;

sending a signal to the objects to cause the objects to selectively add a number to their respective counter, the number to be determined by each individual object and dependent upon one or more previous responses of the individual object to the interrogation;

sending a signal to the objects to cause the objects to selectively subtract a number from their respective counter, the number to be determined by each individual object and dependent upon one or more previous responses of the individual object to the interrogation;

recording complete identification numbers as they are determined; and

sending a signal to interrogate a single digit from the objects to be identified.

41. The method of claim 40, wherein the objects are identified based on a depth-first tree traversal algorithm.

42. The method of claim 41, wherein a speed for determining the identification numbers is deterministic given a set of objects to have their identification numbers determined.

43. The method of claim 40, wherein, in response to interrogation of a signal digit from the objects, each object provides a response regardless of the value of the digit being interrogated.

44. The method of claim 40, wherein the communication channel comprises a radio channel.

45. The method of claim 44, wherein the objects each include an RFID transponder.

46. The method of claim 45, wherein the counter is included in control circuitry for the RFID transponder.

47. The method of claim 40, wherein the communication channel comprises a wired communication channel.

48. The method of claim 40, wherein values of the respective counters selectively inhibit objects from responding to interrogation signals.

49. The method of claim 40, wherein the selective inhibit occurs as part of a depth-first tree traversal algorithm.