Decentralized radio frequency identification system

A decentralized RFID system comprising:

• a plurality of readers, each of the plurality of readers capable of transmitting a respective carrier signal;
• at least one tag in operative communication with one or more of the plurality of readers for receiving one or more of the respective carrier signals from the plurality of readers;
• and
• wherein each of the the plurality of readers includes a module having an algorithm for adjusting a respective power output for each of the plurality of readers as a function of a respective measured interference at that respective plurality of readers in order to achieve a predetermined signal-to-noise ratio (SNR).

A method for adjusting a transmission power level of at least one of a plurality of radio frequency identification (RFID) readers included in a network of RFID readers, the method comprising:

• transmitting a first carrier signal from a first RFID reader included in the network of RFID readers and transmitting a second carrier signal from a second RFID reader of the network included in RFID readers, wherein the first RFID reader operates at a first power level, and wherein the second RFID reader operates at a second power level;
• receiving the first and second carrier signals at a RFID tag;
• generating, at the RFID tag, a first backscatter signal in response to the first carrier signal and a second backscatter in response to the second carrier signal;
• processing the second carrier signal at the first RFID reader to measure a first level of interference and processing the first carrier signal at the second RFID reader to measure a second interference level, the first level of interference corresponding to an amount of interference from the second carrier signal, and the second level of interference corresponding to an amount of interference from the first carrier signal;
• and
• adjusting the first power level of the first RFID reader as a function of the first level of inference and adjusting the second power level of the second RFID reader as a function of the second level of interference.

A processor having executable components for adjusting a transmission power level of at least one radio frequency identification (RFID) reader in a decentralized RFID system, the decentralized RFID system comprising a first reader to transmit a first carrier signal at a first power level;

• a second reader to transmit a second carrier signal at a second power level, and a tag to receive the first and second carrier signals and to generate, at the tag, a first backscatter signal in response to the first carrier signal and a second backscatter in response to the second carrier signal, the processor comprising:
• a power update component to determine a current transmission power corresponding to the first carrel signal and to calculate a current signal-to-noise ratio value based on the current transmission power level and signal-to-noise ratio data retrieved from a memory;
• a signal-to-noise ratio comparator component to compare the current signal-to-noise value to a required signal-to-noise value retrieved from the memory and to generate a first output signal as a function of the comparison;
• a percentage signal-to-noise ratio achieved component to calculate a back-off parameter as a function of the first output signal, wherein the back-off parameter corresponds to a percentage of time the required signal-to-noise ratio is achieved;
• wherein the power update component is further responsive to the first generated output signal to calculate a new transmission power required to achieve the desired signal-to-noise ratio;
• a limiter component to receive the new transmission power and to limit the new calculated transmission power within a specified transmission power range;
• a power comparator component to receive the new transmission power thru the limiter component, to compare the new transmission power to a maximum transmission power value retrieved from the memory, and to generate a second output signal as a function of the comparison;
• and
• a selective back-off component is responsive to the second output signal from the power comparator component, the new transmission power received thru the limiter, and the back-off parameter from the percentage signal-to-noise ratio achieved component to determine whether to operate the first reader in a normal mode or a selective back-off mode, wherein the first reader outputs the new transmission power for generating the first carrier signal during normal mode, and wherein the first reader waits for a determined time period before outputting the new transmission power during the back-off mode.