RFID communication control method and RFID system using same
First Claim
1. An RFID system, comprising:
- a reader/writer, which has a reader/writer main unit and a polarization-switchable antenna, and which transmits a continuous carrier wave; and
a tag, which modulates the continuous carrier wave with tag information and returns a response signal to the reader/writer;
wherein the reader/writer main unit judges the level of a received interference signal and determines a polarization direction for which the level of the interference signal is equal to or less than a threshold;
a command signal is transmitted to the tag with a polarization direction different from the determined polarization direction; and
a response signal from the tag to the command signal is received with the determined polarization direction.
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Accused Products
Abstract
An RFID system, which increases the probability of detection of an unused channel and which can reduce the effect of interference between reader/writers, has a reader/writer which has a reader/writer main unit and a polarization-switchable antenna and which transmits a continuous carrier wave, and a tag which modulates the continuous carrier wave with tag information and returns a response signal to the reader/writer; the reader/writer main unit judges the level of a received interference signal, determines a polarization direction for which the level of the interference signal is equal to or less than a threshold, transmits a command signal to the tag with a polarization direction different from the polarization direction thus determined, and receives a response signal from the tag to the command signal with the polarization direction thus determined.
22 Citations
11 Claims
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1. An RFID system, comprising:
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a reader/writer, which has a reader/writer main unit and a polarization-switchable antenna, and which transmits a continuous carrier wave; and
a tag, which modulates the continuous carrier wave with tag information and returns a response signal to the reader/writer;
wherein the reader/writer main unit judges the level of a received interference signal and determines a polarization direction for which the level of the interference signal is equal to or less than a threshold;
a command signal is transmitted to the tag with a polarization direction different from the determined polarization direction; and
a response signal from the tag to the command signal is received with the determined polarization direction. - View Dependent Claims (2, 3, 4, 7, 8)
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5. An RFID system, comprising:
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a reader/writer, which has a reader/writer main unit and a plurality of antennas each having a specific polarization, and which transmits a continuous carrier wave; and
a tag, which modulates the continuous carrier wave with tag information and returns a response signal to the reader/writer;
wherein the reader/writer main unit judges the level of received interference signals for each of the plurality of antennas and determines an antenna with polarization at which the judged level of the interference signal is equal to or less than a threshold;
a command signal is transmitted from an antenna with a polarization other than the determined polarization; and
a response signal from the tag to the command signal is received by the antenna with the determined polarization. - View Dependent Claims (6)
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9. An RFID communication control method, in an RFID system having a reader/writer which has a reader/writer main unit and a plurality of antennas each set to different polarization directions and which transmits a continuous carrier wave, and a tag which modulates the continuous carrier wave with tag information and returns a response signal to the reader/writer,
the RFID communication control method comprising the steps of: -
measuring an interference signal level for a specific channel sequentially for all switchable polarizations of the antenna;
when the measured interference signal level is equal to or greater than a threshold, switching a specific channel to another channel and measuring the interference signal level;
determining a channel and polarization direction for which the measured interference signal level does not exceed the threshold are determined;
sending a command signal to the tag with a polarization direction other than the determined polarization direction; and
receiving a response signal to the command signal at the determined channel and polarization direction. - View Dependent Claims (10, 11)
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Specification