Battery assisted rfid command set and interference control

Abstract

Specialized battery assisted command set design methods are disclosed that provide for interference rejection using highly sensitive but relatively broadband RFID tags. The command set design also supports RFID system RF power control for further interference control. The command set design also allows for convenient expansion to active transmitters and receivers in tags operating within the same system. Embodiments of the present invention provide RFID systems having battery-assisted, Semi-Passive RFID tags that operate with sensitive transistor based square law tag receivers utilizing a plurality of tag receiver dynamic range states. Additional enhancement attained via power leveling methods that optimize the amount of transmitted power and interference from a reader in relation to the sensitivity of the RFID tags, their ranges from the reader, and the unique physics of the backscatter RFID radio link.

What is claimed is: 
     
         1 . A method of generating an RFID activation command that is transmitted from an RFID reader and processed in an RFID tag, the method comprising:
 generating an air interface class identification code that identifies a subset of possible air interface classes associated with the RFID tag that are to respond to the reader activation command; and   inserting the air interface class identification code within the RFID activation command; and   transmitting the RFID activation command to the RFID tag.   
     
     
         2 . The method of  claim 1  further comprising:
 generating an active transmitter setup code that provides information to the RFID tag related to operating parameters of an RFID active tag transmitter; and 
 inserting the active transmitter set-up code within the RFID activation command. 
 
     
     
         3 . The method of  claim 2  wherein the active transmitter setup code defines a set of tag transmit characteristics comprising at least one characteristic selected from a group consisting of a tag active transmit frequency or channel, an active transmit power, an active transmit modulation mode, and an active transmit data rate. 
     
     
         4 . The method of  claim 1  further comprising inserting an active receiver set up code within the RFID activation command, the active receiver set up code provides information to the RFID tag related to operating parameters of an RFID active tag receiver. 
     
     
         5 . A method for bringing a set of RFID tags into an interrogation/query round, the method comprising:
 generating air interface class identification code that identifies a class of at least one RFID tag, within the set of RFID tags, that are to participate in the interrogation round;   inserting the air interface class identification code within an RFID interrogation command; and   transmitting the RFID interrogation command to the set of RFID tags.   
     
     
         6 . The method of  claim 5  further comprising:
 generating an active transmitter setup code that provides information to the RFID tag related to operating parameters of an RFID active tag transmitter; and 
 inserting the active transmitter set-up code within the RFID activation command. 
 
     
     
         7 . The method of  claim 6  wherein the active transmitter setup code defines a set of tag transmit characteristics comprising at least one characteristic selected from a group consisting of a tag active transmit frequency or channel, an active transmit power, an active transmit modulation mode, and an active transmit data rate. 
     
     
         8 . The method of  claim 5  further comprising inserting an active receiver set up code within the RFID activation command, the active receiver set up code provides information to the RFID tag related to operating parameters of an RFID active tag receiver. 
     
     
         9 . A method for bringing a set of RFID tags into an interrogation/query round, the method comprising:
 generating a sensor type identification code that identifies at least one sensor type required for each RFID tag, within the set of RFID tags, to participate in the interrogation round,   inserting the sensor type identification code within an RFID interrogation command; and   transmitting the RFID interrogation command to the set of RFID tags.   
     
     
         10 . The method of  claim 9  wherein the at least one identified sensor type is a Simple Sensor type. 
     
     
         11 . The method of  claim 10  wherein an additional field is provided to enable automatic Simple Sensor response by the set of RFID tags as part of a singulation process and wherein the set of RFID tags transmit Simple Sensor data and identifying data without using an additional command to read the Simple Sensor data.