Location management for radio frequency identification readers

• US 7,295,114 B1
• Filed: 01/21/2005
• Issued: 11/13/2007
• Est. Priority Date: 01/21/2005
• Status: Active Grant

• Current Assignee: RUIZHANG TECHNOLOGY LIMITED COMPANY
• Original Assignee: Alien Technology Corporation
• Inventors: Drzaic, Paul Stephen, Penzias, Arno Allan
• Primary Examiner(s): Lee, Benjamin C.
• Assistant Examiner(s): BLOUNT, ERIC
• Application Number:
  US11/040,551
• Time in Patent Office: 1,026 Days
• Field of Search: 340/572.1
• US Class Current: 340/572.1
• CPC Class Codes: A62B 99/00 Subject matter not provided for in other groups of this subclass
• CPC Class Codes: G01S 13/75 using transponders powered from received waves, e.g. using passive transponders , or using passive reflectors
• 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: G08B 13/1427 with transmitter-receiver for distance detection
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 21/0275 Electronic Article Surveillance [EAS] tag technology used for parent or child unit, e.g. same transmission technology, magnetic tag, RF tag, RFID

Abstract

A Radio Frequency Identification (RFID) system for managing and identifying locations for an RFID reader is disclosed. An expected location of a fixed radio frequency identification (RFID) reader is determined. A first signal is transmitted from the reader to a first RFID tag to determine whether the reader is at the expected location. The first tag is a fiducial RFID tag fixed at a first location. In one aspect, the reader receives a first response to the first signal from the first tag. The first response identifies the first location of the first tag. The first location is compared to the expected location. If the first location and the expected location are different, an alarm is triggered.

Claims

1. A method comprising:

determining an expected location of a fixed radio frequency identification (RFID) reader;

transmitting first signal from the reader to a first RFID tag for the reader to determine whether the reader is at the expected location, wherein the first tag is a fiducial RFID tag, including an antenna, fixed at a first location;

receiving at the reader a first response to the first signal from the first tag, wherein the first response identifies the first location; and

comparing the first location with the expected location and if the first location and the expected location are different, assigning the first location as the expected location of the reader.

2. A method comprising:

determining an expected location of a fixed radio frequency identification (RFID) reader;

transmitting first signal from the reader to a first RFID tag for the reader to determine whether the reader is at the expected location, wherein the first tag is a fiducial RFID tag, including an antenna, fixed at a first location; and

wherein the determining the expected location of the reader comprises;

transmitting a second signal from the reader to the first tag;

receiving a response from the first tag, the response indicating that the first tag is associated with the first location; and

assigning the first location as the expected location of the reader.

3. A machine-readable medium having instructions to cause a machine to perform a machine-implemented method comprising:

determining an expected location of a fixed radio frequency identification (RFID) reader;

transmitting a first signal from the reader to a first RFID tag for the reader to determine whether the reader is at the expected location, wherein the first tag is a fiducial RFID tag, including an antenna, fixed at a first location;

receiving at the reader a first response to the first signal from the first tag, wherein the first response identifies the first location; and

comparing the first location with the expected location, and if the first location and the expected location are different, assigning the first location as the expected location of the reader.

4. A machine-readable medium having instructions to cause a machine to perform a machine-implemented method comprising:

determining an expected location of a fixed radio frequency identification (RFID) reader;

transmitting a first signal from the reader to a first RFID tag for the reader to determine whether the reader is at the expected location, wherein the first tag is a fiducial RFID tag, including an antenna, fixed at a first location; and

wherein the determining the expected location of the reader comprises;

transmitting a second signal from the reader to the first tag;

receiving a response from the first tag, the response indicating that the first tag is associated with the first location; and

assigning the first location as the expected location of the reader.

5. An apparatus comprising:

means for determining an expected location of a fixed radio frequency identification (RFID) reader;

means for transmitting a first signal from the reader to a first RFID tag for the reader to determine whether the reader is at the expected location, wherein the first tag is a fiducial RFID tag, including an antenna, fixed at a first location;

means for receiving at the reader a first response to the first signal from the first tag, wherein the first response identifies the first location; and

means for comparing the first location with the expected location, and if the first location and the expected location are different, means for assigning the first location as the expected location of the reader.

6. An apparatus comprising:

means for determining an expected location of a fixed radio frequency identification (RFID) reader; and

means for transmitting a first signal from the reader to a first RFID tag for the reader to determine whether the reader is at the expected location, wherein the first tag is a fiducial RFID tag, including an antenna, fixed at a first location; and

wherein the means for determining the expected location of the reader comprises;

means for transmitting a second signal from the reader to the first tag;

means for receiving a response from the first tag, the response indicating that the first tag is associated with the first location; and

means for assigning the first location as the expected location of the reader.

7. A system comprising:

a processing unit coupled to a memory through a bus; and

a process executed from the memory by the processing unit to cause the processing unit to;

determine an expected location of a fixed radio frequency identification (RFID) reader;

transmit a first signal from the reader to a first RFID tag for the reader to determine whether the reader is at the expected location, wherein the first tag is a fiducial RFID tag, including an antenna, fixed at a first location;

the process further causes the processing unit to receive at the reader a first response to the first signal from the first tag, wherein the first response identifies the first location; and

the process further causes the processing unit to compare the first location with the expected location and if the first location and the expected location are different, assign the first location as the expected location of the reader.

8. A system comprising:

a processing unit coupled to a memory through a bus; and

a process executed from the memory by the processing unit to cause the processing unit to;

determine an expected location of a fixed radio frequency identification (RFID) reader;

transmit a first signal from the reader to a first RFID tag for the reader to determine whether the reader is at the expected location, wherein the first tag is a fiducial RFID tag, including an antenna, fixed at a first location;

transmit a second signal from the reader to the first tag;

receive a response from the first tag, the response indicating that the first tag is associated with the first location; and

assign the first location as the expected location of the reader.

9. A radio frequency identification (RFID) reader for use in reading RFID tags, the reader comprising:

a transmitter to transmit a first signal from the reader to an RFID tag including an antenna;

a receiver to receive a second signal from the RFID tag, the second signal identifying a first location of the RFID tag, wherein the first location is capable of being compared to an expected location of the reader to determine whether the reader is at the expected location;

wherein the reader is communicatively coupled to a computing device on a network, the computing device to compare the first location with the expected location, and the computing device is further to assign the first location as the expected location of the reader if the first location and the expected location are determined to be different.

10. A method comprising:

transmitting a signal from a radio frequency identification (RFID) reader, the signal to elicit responses from RFID tags;

receiving at the reader a response to the signal from at least one fiducial RFID tag including an antenna, the fiducial RFID tag being fixed at a known location within a space;

receiving at the reader a response to the signal from a first RFID tag, wherein the first RFID tag is attached to a moveable object;

estimating a location of the object within the space based on the responses received from the at least one fiducial RFID tag and the first RFID tag; and

estimating a range within which the reader is able to read RFID tags based on the response received from the at least one fiducial RFID tag.

11. A method comprising:

transmitting a signal from a radio frequency identification (RFID) reader, the signal to elicit responses from RFID tags;

receiving at the reader a response to the signal from at least one fiducial RFID tag including an antenna, the fiducial RFID tag being fixed at a known location within a space;

receiving at the reader a response to the signal from a first RFID tag, wherein the first RFID tag is attached to a moveable object;

estimating a location of the object within the space based on the responses received from the at least one fiducial RFID tag and the first RFID tag;

receiving at the reader a plurality of responses from a plurality of fiducial RFID tags, the plurality of fiducial RFID tags being fixed at known locations within the space; and

wherein estimating the location of the object is based on the responses received from the plurality of fiducial RFID tags and further comprises;

estimating the location of the object comprises;

creating a first matrix based on the responses received from the plurality of fiducial RFID tags over a set of times, each time of the set of times corresponding to a reading taken by the RFID reader at a specific location;

creating a second matrix based on responses received from the first RFID tag over the set of times;

multiplying the first matrix by the second matrix to obtain a third matrix; and

estimating the location of the object based on the values within the third matrix.