Frequency Hopping System and Method for Communicating with RFID Tags
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Abstract
Radio frequency (RF) power is sent out by a base station to radio frequency identification transponders (RFID tags) for a first time at a first frequency. The frequency is changed to a second frequency, and the RF power sent out for a second time substantially different from the fist time so as to tend to improve data throughput. In one embodiment forced frequency “hops” are implemented if the time it takes to perform a particular transaction is greater than the time available on a particular carrier frequency. In one embodiment, a radio frequency identification (RFID) base station processor (in conjunction with program information stored in a base station memory) is adapted to (i) determine the amount of time available on a particular carrier frequency (e.g., pursuant to Federal Communications Commission (FCC) regulations, European Telecommunications Standardization Institute (ETSI) regulations, etc.), (ii) determine the amount of time it would take to perform a particular transaction, and (iii) force the base station to “hop” to another carrier frequency if the transaction time is longer than the available time. In one embodiment, the time it would take to perform a particular transaction is the time it would take to perform the next transaction. In another embodiment, the time it would take to perform a particular transaction is the time it would take to perform the longest (or “worst-case”) transaction. In alternate embodiments, a transaction is defined as the transmission of information (e.g., data, commands, etc.) or both the transmission of information and the reception of related information.
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Citations
45 Claims
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1-20. -20. (canceled)
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21. A radio frequency identification (RFID) system, comprising:
- an RFID base station adapted to communicate with at least one RFID transponder;
said RFID base station comprising;
a transmitter adapted to transmit radio frequency (RF) signals to said at least one RFID transponder;
a receiver adapted to receive RF signals backscattered from said at least one RFID transponder; and
a processor electrically connected to said transmitter and said receiver, and adapted to;
determine the amount of time available on a first carrier frequency;
determine the amount of time it would take to perform a particular transaction; and
change to a second carrier frequency before said amount of time available on said first carrier frequency expires if said amount of time on said first carrier frequency is less than said amount of time it would take to perform said particular transaction. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
- an RFID base station adapted to communicate with at least one RFID transponder;
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32. A method for improving transmission rates in a radio-frequency-identification (RFID) base station, comprising:
- performing a first transaction with at least one RFID transponder over a first carrier frequency;
during a first time interval, transmitting a second carrier frequency for a second time interval, and controlling the duration of the second time interval to be greater or less than said first time interval so as to tend to increase data throughput. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40)
- performing a first transaction with at least one RFID transponder over a first carrier frequency;
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41. A frequency-hopping-spread-spectrum (FHSS) method for use in a radio-frequency-identification (RFID) device, comprising:
- transmitting a first radio frequency (RF) signal over a first carrier frequency for a first time period;
transmitting a second RF signal over said first carrier frequency; and
transmitting a second RF signal over a second carrier so as to tend to improve data throughput. - View Dependent Claims (42, 43, 44, 45)
- transmitting a first radio frequency (RF) signal over a first carrier frequency for a first time period;
Specification