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2 RFID System Physical Anti-Collision Experimental Verification
the first part of this paper, the definition of tag group sensitivity is described and a
method for measuring tag group sensitivity is proposed. Secondly, a dynamic testing
system based on photoelectric sensing is designed based on the practical application
scenarios and measurement needs. Finally, the structure and number of tags in tag
group were changed, and the influence of key tag positions on the sensitivity of tag
group was studied. In the second part, according to the built RFID tag group dynamic
test system, aiming at the impact of the tag group sensitivity due to the different
arrangement positions of tags in the batch reading of RFID tags, the tag matching and
positioning is carried out in combination with the image processing method to find
the impact of the relative position of tags on the tag group sensitivity. This study is of
great significance to the evaluation and optimization of RFID multi-tag performance
and provides an important basis for upgrading the sensitivity measurement system
of tag group to the performance optimization analysis system.
2.1 RFID Tag Group Performance Measurement
2.1.1 Tag Group Sensitivity
The test items defined in the RFID tag performance test specification mainly include
two categories: static performance test and dynamic performance test. The dynamic
performance test is a sports-oriented test item and it can reflect the performance index
of the tag in the motion identification application. According to the international
standard EPC global, the unipolar radiated power received by the tag is expressed as
the tag sensitivity in the dynamic test of the tag.
Friis Transmission formula is one of the most important antenna theories. It relates
transmission power, antenna gain, distance, wavelength, and received power. The
Friis formula is used to calculate the received power from one antenna to the second,
also known as the power transfer equation, as shown in (2.1).
r =
λ
4π
P t G t G t τ
P r
(2.1)
where r is the distance of the sensor to the tag, also known as read distance, P t
is the transmitting antenna power, G t is the transmitting antenna gain, G r is the
receiving antenna gain, P r is the receiving power, λ is the working wavelength, and
τ is the matching coefficient of tag and antenna. According to Friis formula, we can
intuitively get the tag power expression, as shown in (2.2).
P r =
λ
2 P t G t G r τ
(4π)
2
×
1
r 2
(2.2)
2 RFID System Physical Anti-Collision Experimental Verification
the first part of this paper, the definition of tag group sensitivity is described and a
method for measuring tag group sensitivity is proposed. Secondly, a dynamic testing
system based on photoelectric sensing is designed based on the practical application
scenarios and measurement needs. Finally, the structure and number of tags in tag
group were changed, and the influence of key tag positions on the sensitivity of tag
group was studied. In the second part, according to the built RFID tag group dynamic
test system, aiming at the impact of the tag group sensitivity due to the different
arrangement positions of tags in the batch reading of RFID tags, the tag matching and
positioning is carried out in combination with the image processing method to find
the impact of the relative position of tags on the tag group sensitivity. This study is of
great significance to the evaluation and optimization of RFID multi-tag performance
and provides an important basis for upgrading the sensitivity measurement system
of tag group to the performance optimization analysis system.
2.1 RFID Tag Group Performance Measurement
2.1.1 Tag Group Sensitivity
The test items defined in the RFID tag performance test specification mainly include
two categories: static performance test and dynamic performance test. The dynamic
performance test is a sports-oriented test item and it can reflect the performance index
of the tag in the motion identification application. According to the international
standard EPC global, the unipolar radiated power received by the tag is expressed as
the tag sensitivity in the dynamic test of the tag.
Friis Transmission formula is one of the most important antenna theories. It relates
transmission power, antenna gain, distance, wavelength, and received power. The
Friis formula is used to calculate the received power from one antenna to the second,
also known as the power transfer equation, as shown in (2.1).
r =
λ
4π
P t G t G t τ
P r
(2.1)
where r is the distance of the sensor to the tag, also known as read distance, P t
is the transmitting antenna power, G t is the transmitting antenna gain, G r is the
receiving antenna gain, P r is the receiving power, λ is the working wavelength, and
τ is the matching coefficient of tag and antenna. According to Friis formula, we can
intuitively get the tag power expression, as shown in (2.2).
P r =
λ
2 P t G t G r τ
(4π)
2
×
1
r 2
(2.2)