Rfid location systems and methods

Abstract

Embodiments of the present invention include radio frequency identification location systems and methods. In one embodiment, RF signals are transmitted from one or more RFID readers, and in accordance therewith, backscattered signals are received from a tag to be located. A plurality of measured position parameters are used to determine a location of the tag. In one embodiment, one reader may transmit and three readers may receive signals to determine the position of a tag. In other embodiments, multiple readers may transmit and receive. In another embodiment, one reader may transmit from different positions to locate a tag. Embodiments of the invention may be used to track a moving tag. A reader's position may be determined using GPS, reference tags, or the reader may be positioned in a known location. A map may be provided to a user to display the location or movement of a tag or a corresponding item.

1 - 62 . (canceled) 
     
     
         63 . A system for locating radio frequency identification tags comprising:
 a tag;   a computer system including location software; and   one or more RFID readers comprising an RFID transmitter, an RFID receiver, and a first communication unit for communicating with the server;   wherein the one or more RFID readers transmits three or more RF signals, and receives three or more backscattered signals from the tag,   wherein each of the one or more RFID readers transmits a plurality of measured position parameters corresponding to each of the three or more received backscattered signals to the server,   and wherein the location software on the server determines a location of the tag using the plurality of measured position parameters.   
     
     
         64 . The system of  claim 63  wherein the one or more RFID readers comprise three or more RFID readers. 
     
     
         65 . The system of  claim 63  wherein the one or more RFID readers comprise one RFID reader that transmits the three or more RF signals from three or more different locations. 
     
     
         66 . The system of  claim 63  wherein the one or more RFID readers comprise at least a first RFID reader and a second RFID reader, wherein the first RFID reader transmits a first RF signal from a first location, and wherein the second RFID reader transmits a second RF signal from a second location and a third RF signal from a third location. 
     
     
         67 . The system of  claim 63  wherein the one or more RFID readers further comprise a global positioning system. 
     
     
         68 . The system of  claim 63  wherein the measured position parameters comprise power of the backscattered signal, angle of arrival of the backscattered signal, time difference of arrival of the backscattered signal, or phase of the backscattered signal. 
     
     
         69 . The system of  claim 63  further comprising a display, wherein a user enters an item to be located, and said system displays a map to the user showing the location of said item. 
     
     
         70 . A device for locating radio frequency identification tags comprising:
 an RF signal transmitter for transmitting one or more RF signals to a tag;   a backscattering receiver for receiving one or more backscattered signals from said tag;   a position parameter measurement unit for extracting one or more measured position parameters from each backscattered signal; and   a communication unit for establishing a data communication link between said device and an external system,   wherein measured position parameters obtained from at least three backscattering signals from said tag from at least three different positions are used to determine the location of said tag.   
     
     
         71 . The device of  claim 70  further comprising a global position system. 
     
     
         72 . The device of  claim 70  wherein the external system comprises one or more readers. 
     
     
         73 . The device of  claim 72  further comprising location software, wherein measured position parameters from one or more other readers are received by said device, and the location software determines the location of said tag. 
     
     
         74 . The device of  claim 70  wherein the external system comprises a server, and wherein measured position parameters are transmitted to the server, and the server determines the location of said tag. 
     
     
         75 . The device of  claim 70  further comprising mapping software for displaying a map to the user showing the location of said tag. 
     
     
         76 . The device of  claim 70  wherein said device is a cellular phone. 
     
     
         77 . The device of  claim 70  wherein said device is a personal digital assistant. 
     
     
         78 . The device of  claim 70  wherein said device is a portable computer. 
     
     
         79 . A method determining position using radio frequency identification tags comprising:
 transmitting three or more RF signals from an RFID reader, and in accordance therewith, receiving three or more backscattered signals from three or more reference tags;   extracting at least one measured position parameter from each of the three or more backscattered signals;   accessing the position of the three or more reference tags; and   determining a location of the reader using the plurality of measured position parameters.   
     
     
         80 . The method of  claim 79  wherein the position of at least one reference tag is stored on the at least one tag. 
     
     
         81 . The method of  claim 79  further comprising:
 storing one or more locations corresponding to one or more reference tags; 
 receiving one or more tag IDs in one or more backscattered signals; and 
 retrieving the stored location of one or more reference tags using the tag IDs. 
 
     
     
         82 - 88 . (canceled)