RFID carrier sensing method and FRID system using this FRID carrier sensing method
First Claim
1. An RFID system, comprising:
- a reader/writer which has a reader/writer main body section and an antenna capable of polarization switching, and which sends a continuous carrier wave; and
a tag which uses tag information to modulate the continuous carrier wave and sends back a response signal to the reader/writer, wherein the reader/writer main body section judges the level of a received interference signal and determines a channel and polarization direction for which the level of the interference signal is equal to or less than a threshold value, and receives a response signal from the tag in the determined channel and polarization direction.
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Accused Products
Abstract
An RFID system that is capable of increasing the probability of a spare channel being detected and reducing the influence of interference between reader/writers comprises: a reader/writer which has a reader/writer main body section and an antenna capable of polarization switching, and which sends a continuous carrier wave; and a tag which uses tag information to modulate the continuous carrier wave and sends back a response signal to the reader/writer. The reader/writer main body section judges the level of a received interference signal and determines a channel and polarization direction for which the level of the interference signal is equal to or less than a threshold value, and receives a response signal from the tag on the determined channel and in the polarization direction.
12 Citations
20 Claims
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1. An RFID system, comprising:
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a reader/writer which has a reader/writer main body section and an antenna capable of polarization switching, and which sends a continuous carrier wave; and
a tag which uses tag information to modulate the continuous carrier wave and sends back a response signal to the reader/writer, wherein the reader/writer main body section judges the level of a received interference signal and determines a channel and polarization direction for which the level of the interference signal is equal to or less than a threshold value, and receives a response signal from the tag in the determined channel and polarization direction. - View Dependent Claims (2, 3, 5, 7, 13, 15)
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4. An RFID system, comprising:
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a reader/writer which has a reader/writer main body section and a plurality of antennae each with characteristic polarization, and which sends a continuous carrier wave; and
a tag which uses tag information to modulate the continuous carrier wave and sends back a response signal to the reader/writer, wherein the reader/writer main body section judges the level of the interference signal to be received by each of the plurality of antennae for each of the plurality of channels and determines a channel and antenna for which the judged level of the interference signal is equal to or less than the threshold value, and receives a response signal from the tag by means of the determined antenna via the determined channel. - View Dependent Claims (6, 8)
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9. A carrier sensing method of an RFID system which has a reader/writer that has a reader/writer main body section and an antenna capable of polarization switching and which sends a continuous carrier wave, and a tag which uses tag information to modulate the continuous carrier wave and sends back a response signal to the reader/writer,
the method comprising the steps of: - in the reader/writer,
sequentially measuring the interference signal level using a specified channel for all of the switchable polarization of the antenna;
measuring the interference signal level by switching the specified channel to another channel when the interference signal level to be measured is equal to or more than the threshold value;
determining a channel and polarization direction for which the interference signal level thus measured does not exceed the threshold value; and
setting to receive the response signal from the tag on the determined channel and in the determined antenna polarization direction. - View Dependent Claims (10, 11, 14, 16)
- in the reader/writer,
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12. A carrier sensing method of an RFID system which has a reader/writer that has a reader/writer main body section and a plurality of antennae each set with a different polarization direction, and which sends a continuous carrier wave, and a tag which uses tag information to modulate the continuous carrier wave and sends back a response signal to the reader/writer,
the method comprising the steps of: - in the reader/writer,
sequentially measuring the interference signal level using a specified channel for the respective polarization of the plurality of antennae;
measuring the interference signal level by switching the specified channel to another channel when the interference signal level to be measured is equal to or more than the threshold value;
determining an antenna set to a channel and polarization direction for which the interference signal level thus measured does not exceed the threshold value; and
setting to receive the response signal from the tag using the determined channel and antenna.
- in the reader/writer,
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17. A reader/writer of a RFID system which has a reader/writer main body section and an antenna capable of polarization switching, and which sends a continuous carrier wave to a tag, wherein
the level of a received interference signal is judged and a channel and polarization direction for the antenna for which the level of the interference signal is equal to or less than a threshold value are determined, and a response signal that is generated by using tag information to modulate the continuous carrier wave and sent back by the tag is received on the determined channel and in the determined polarization direction.
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20. A reader/writer of an RFID system which has a reader/writer main body section and a plurality of antennae each with characteristic polarization, and which sends a continuous carrier wave to a tag, wherein
the reader/writer main body section judges the level of the interference signal to be received by each of the plurality of antennae for each of the plurality of channels and determines a channel and antenna for which the judged level of the interference signal is equal to or less than the threshold value, and receives, by means of the determined antenna via the determined channel, a response signal which is generated by using tag information to modulate the continuous carrier wave and which is sent back by the tag.
Specification