Patent ID: 8872633

Claim:
A method for communicating with a plurality of radio frequency identification (RFID) devices by, comprising: transmitting a series of signals comprising a first signal and a second signal, using a first RFID reader, the second signal being transmitted at an increased power level relative to the first signal; transmitting a third signal having a power level increasing from a first power level to a second power level in a continuous analog manner where a rate of the continuous increasing slows as the power level of the third signal increases; interrogating RFID devices responding to at least one signal in the series of signals; receiving a selection of each power level from a backend system, at least some of the power levels being selected by the backend system based on response from the first RFID reader and one or more other RFID readers in communication with the backend system so that the selected power levels do not interfere with a query being conducted by a second RFID reader simultaneously with the transmitting of the series of signals, the first and the second RFID readers being connected to the backend system; and at each power level: singulating RFID devices responding to the signal via backscatter communications; instructing the responding RFID devices to change state to an unresponsive state; wherein the first signal is transmitted at the first power level, wherein the second signal is transmitted at the second power level, wherein the transmitting the series of signals, the interrogating the RFID devices, and the instructing the responding RFID devices to change state are performed by the first RFID reader, wherein one or more of the RFID devices responding to the first signal do not respond to the second signal upon changing state in response to the instruction to change state to the unresponsive state; and wherein a variation in a backscattering power level of the RFID devices located within a maximum effective communication range is less than about 100:1.