Patent ID: 8237546

Claim:
A method of communicating with a population of radio frequency identification (RFID) tags, comprising: transmitting a first interrogation signal; receiving a first response to the first interrogation signal from at least one RFID tag at a first received signal strength, wherein the response includes at least a portion of a first identification code; determining a secure power level as a lowest power level such that a second response to a second interrogation signal is received; transmitting the second interrogation signal that includes a request for confidential information, a command to transmit a response to the second interrogation signal at the determined secure power level, and said first identification code, wherein said at least one RFID tag is configured to adjust power to transmit the response to the second interrogation signal at the determined secure power level based on the request receiving the second response to the second interrogation signal at a second received signal strength, wherein the second response includes confidential information, wherein the second received signal strength is less than the first received signal strength; wherein if the second response to the second interrogation is not received, transmitting a third interrogation signal that includes a command to re-transmit the confidential information at an increased power level, and receiving a third response to the third interrogation signal at a third received signal strength, wherein the third response includes confidential information, wherein the third received signal strength is less than the first received signal strength and is higher than the second received signal strength.