Reverse infrastructure location system and method

Abstract

Embodiments include methods and systems by which an object can be located within an area. The system includes a moveable radio frequency identification (RFID) tag reader and multiple RFID tags, which are positioned at known locations. The RFID tag reader is associated with the object, and is adapted to interrogate the RFID tags, to receive unique identifiers from responding RFID tags, to correlate the unique identifiers with tag location information stored in memory to determine fixed positions for the responding RFID tags, and to mathematically determine at least one location solution for the RFID tag reader using the fixed positions. A responding RFID tag is adapted to respond to an interrogation signal from the RFID tag reader by transmitting a unique identifier.

1 . A system by which an object can be located within an area, the system comprising:
 a moveable radio frequency identification (RFID) tag reader associated with the object and in signaling contact with multiple RFID tags positioned at known locations within the area, wherein the RFID tag reader is adapted to interrogate at least some of the multiple RFID tags, to receive two or more unique identifiers from two or more responding RFID tags, to correlate the two or more unique identifiers with tag location information stored in memory to determine fixed positions for each of the two or more responding RFID tags, and to mathematically determine at least one location solution for the RFID tag reader within the area using the fixed positions.   
   
   
       2 . The system of  claim 1 , further comprising:
 the multiple RFID tags, wherein a responding RFID tag of the multiple RFID tags is adapted to respond to an interrogation signal from the RFID tag reader by transmitting a unique identifier.   
   
   
       3 . The system of  claim 2 , wherein at least some of the multiple RFID tags are associated with light fixtures within the area. 
   
   
       4 . The system of  claim 3 , wherein the at least some of the multiple RFID tags derive energy from the light fixtures. 
   
   
       5 . The system of  claim 4 , wherein the at least some of the multiple RFID tags derive energy from the light fixtures by optical coupling. 
   
   
       6 . The system of  claim 4 , wherein the at least some of the multiple RFID tags derive energy from the light fixtures by inductive coupling. 
   
   
       7 . The system of  claim 4 , wherein the at least some of the multiple RFID tags derive energy from the light fixtures by capacitive coupling. 
   
   
       8 . The system of  claim 2 , wherein the unique identifier includes location coordinates of the responding RFID tag. 
   
   
       9 . The system of  claim 2 , wherein each of the multiple RFID tags also are adapted to respond to an interrogation signal with a location of the RFID tag. 
   
   
       10 . The system of  claim 1 , wherein the moveable RFID tag reader comprises a primary function. 
   
   
       11 . The system of  claim 10 , wherein the primary function is a function selected from a group that includes a bar code reader, an inventory checker, a cell phone, and a hasmat detector. 
   
   
       12 . The system of  claim 1 , wherein the moveable RFID tag reader comprises a transceiver adapted to communicate with a base station. 
   
   
       13 . A method for determining the position of an object associated with a radio frequency identification (RFID) tag interrogator within an area having multiple RFID tags in known locations, the method comprising the steps of:
 interrogating multiple RFID tags by the RFID tag interrogator transmitting an interrogation signal;   receiving information from two or more responding RFID tags of the multiple RFID tags, wherein such information includes two or more unique identifiers transmitted by the two or more responding RFID tags;   correlating the two or more unique identifiers with tag location information stored in memory to determine fixed positions for each of the two or more responding RFID tags; and   mathematically determining at least one location solution for the RFID tag interrogator within the area using the fixed positions.   
   
   
       14 . The method of  claim 13 , wherein the interrogating step comprises transmitting an interrogation signal. 
   
   
       15 . The method of  claim 14 , further comprising:
 an RFID tag receiving an interrogation signal from the RFID tag reader; and   the RFID tag responding to the interrogation signal by transmitting a unique identifier.   
   
   
       16 . The method of  claim 15 , wherein the unique identifier includes location coordinates of the RFID tag. 
   
   
       17 . The method of  claim 14 , further comprising:
 an RFID tag receiving an interrogation signal from the RFID tag reader; and   the RFID tag responding to the interrogation signal with a location of the RFID tag.   
   
   
       18 . The method of  claim 13 , wherein the interrogating step comprises interrogating an RFID tag associated with a light fixture in the area. 
   
   
       19 . The method of  claim 18 , further comprising the RFID tag deriving energy from the light fixture. 
   
   
       20 . The method of  claim 19 , wherein deriving energy from the light fixture comprises deriving energy using an energy derivation technique selected from a group that includes optical coupling, inductive coupling, and capacitive coupling.