Localization Using Virtual Antenna Arrays in Modulated Backscatter Rfid Systems

Abstract

A localization method for use in a tag communication system includes associating a supertag having a plurality of tags with an item, reading backscatter signals from the tags of the plurality of tags to provide a plurality of backscatter signals, estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters, and localizing the item in accordance with the plurality of derived signal parameters. The backscatter signals are read by a tag reader having a single antenna and the item is localized in accordance with an antenna array technique performed upon the plurality of derived signal parameters. The backscatter signals are read with an antenna array to provide a further plurality of derived signal parameters for each tag of the plurality of tags, and the item is localized in accordance with the further pluralities of derived signal parameters.

1 . A localization method for use in a tag communication system, comprising:
 associating a supertag having a plurality of tags with an item;   reading a backscatter signal from each one of the tags of the plurality of tags to provide a plurality of backscatter signals;   estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters; and   localizing the item in accordance with the plurality of derived signal parameters.   
     
     
         2 . The localization method for use in a tag communication system of  claim 8 , wherein the backscatter signals are read by a tag reader having a single antenna further comprising localizing the item in accordance with an antenna array technique performed upon the plurality of derived signal parameters. 
     
     
         3 . The localization method for use in a tag communication system of  claim 8 , further comprising:
 reading the backscatter signals with an antenna array to provide a further plurality of derived signal parameters for each tag of the plurality of tags; and   localizing the item in accordance with the further pluralities of derived signal parameters.   
     
     
         4 . The localization method for use in a tag communication system of  claim 3 , further comprising calibrating the plurality of derived signal parameters in accordance with the further pluralities of derived signal parameters. 
     
     
         5 . The localization method for use in a tag communication system of  claim 8 , further comprising:
 performing the step of reading backscatter signals from the tags of the plurality of tags at a plurality of different positions to provide a further plurality of derived signal parameters for each tag of the plurality of tags; and   localizing the item in accordance with the further pluralities of signals.   
     
     
         6 . The localization method for use in a tag communication system of  claim 8 , wherein the signal parameter comprises phase information. 
     
     
         7 . The localization method for use in a tag communication system of  claim 8 , wherein the signal parameter comprises time information. 
     
     
         8 . The localization method for use in a tag communication system of  claim 1 , wherein the tags of the plurality of tags are disposed on the supertag with a known geometric relationship with each other. 
     
     
         9 . The localization method for use in a tag communication system of  claim 8 , wherein the tags of the plurality of tags are disposed on the supertag in a linear array. 
     
     
         10 . The localization method for use in a tag communication system of  claim 8 , wherein the tags of the plurality of tags are disposed on the supertag in a two dimensional array. 
     
     
         11 . The localization method for use in a tag communication system of  claim 8 , wherein the tags of the plurality of tags are disposed on the supertag in a three dimensional array. 
     
     
         12 . The localization method for use in a tag communication system of  claim 8 , further comprising determining a tag reader location in accordance with the plurality of derived signal parameters. 
     
     
         13 . The localization method for use in a tag communication system of  claim 8 , further comprising:
 assigning identity information to at least one tag of the plurality of tags;   determining the identity information of the at least one tag in accordance with a backscatter signal from the at least one tag; and   communicating with the at least one tag in accordance with the determined identification information.   
     
     
         14 - 20 . (canceled)