3.3 Kinetic Analysis of Physical Anti-Collision …
93
3.3 Kinetic Analysis of Physical Anti-Collision—Fisher
Information Matrix
In recent years, as one of the core of internet of things (IoT), radio-frequency identification (RFID) has been widely used. With the rapid development of RFID and multiinput multi-output (MIMO) communication, RFID-MIMO system has attracted a
wide spread attention in the IOT industry. In RFID, MIMO technology improves
reliability of the system by using near field spatial multiplexing and far field spatial
diversity to eliminate the interference. Common MIMO system uses several frequencies through multiple channel links while MIMO channel has multiple links operating at the same frequency, which can lengthen RFID reading distance, reduce the
bit error rate of the system and improve the reading efficiency of RFID tag and
the signal bandwidth doesn’t increase [38, 39]. For RFID-MIMO system, Terasaki
made experiments on passive MIMO transmission with load modulation. The results
indicated that the transmission rate of passive MIMO was up to 2 times higher than
that of single-input single-output (SISO) with the same transmission power when
the distance between the reader and the tag was 0.5 m. These results also indicate
that passive MIMO offers high-speed data transmission even when the distance is
doubled [40]. He studied the performance of MIMO RFID backscattering channels,
and found out that these properties of the MIMO RFID channel are significantly
different from that of other types of cascaded channels such as keyhole and double
scattering [41]. In order to get effective biased estimators of the RFID multiple tag
system, Yu took the linear and nonlinear functions in the measurement of RFID
tags as a paradigm to study the equivalence between the bias-corrected estimators
and biased estimators [42]. Aouadi and Belgacem presented an evaluation of MIMO
antennas, with analysis of the mutual coupling, correlation coefficient, diversity gain
and correlation efficiency. They found that the use of the novel LHM (Left Handed
Metamaterial) with multiple bands after fractional removal of substrate was suitable
for MIMO antenna system [43]. Xu studied the uplink transmission in MIMO systems
with antenna correlation and proposed a very efficient scheme in multi-user uplink
MIMO system with distributed channel information [44]. However, few studies have
been done about the influence of multiple tags’ distribution on the reading performance in RFID-MIMO system. Therefore, this paper focuses on the multiple tags’
distribution in RFID-MIMO system.
In the MIMO system, the frequency deviation between transmitter and receiver is
mainly caused by the error between the transmitter and the receiver, and the Doppler
shift caused by the motion of the mobile station. The problem of multi frequency
deviation in MIMO system makes it more complicated to estimate the frequency deviation correctly, and it has become a joint estimation of multi parameter. The multi
parameter joint estimation based on ML principle can almost approximate the ideal
performance with the increase of signal-to-noise ratio, so it becomes a very practical
estimation method [45]. However, the above method has high complexity. Therefore, suboptimal quasi maximum likelihood algorithm is also a common method for
93
3.3 Kinetic Analysis of Physical Anti-Collision—Fisher
Information Matrix
In recent years, as one of the core of internet of things (IoT), radio-frequency identification (RFID) has been widely used. With the rapid development of RFID and multiinput multi-output (MIMO) communication, RFID-MIMO system has attracted a
wide spread attention in the IOT industry. In RFID, MIMO technology improves
reliability of the system by using near field spatial multiplexing and far field spatial
diversity to eliminate the interference. Common MIMO system uses several frequencies through multiple channel links while MIMO channel has multiple links operating at the same frequency, which can lengthen RFID reading distance, reduce the
bit error rate of the system and improve the reading efficiency of RFID tag and
the signal bandwidth doesn’t increase [38, 39]. For RFID-MIMO system, Terasaki
made experiments on passive MIMO transmission with load modulation. The results
indicated that the transmission rate of passive MIMO was up to 2 times higher than
that of single-input single-output (SISO) with the same transmission power when
the distance between the reader and the tag was 0.5 m. These results also indicate
that passive MIMO offers high-speed data transmission even when the distance is
doubled [40]. He studied the performance of MIMO RFID backscattering channels,
and found out that these properties of the MIMO RFID channel are significantly
different from that of other types of cascaded channels such as keyhole and double
scattering [41]. In order to get effective biased estimators of the RFID multiple tag
system, Yu took the linear and nonlinear functions in the measurement of RFID
tags as a paradigm to study the equivalence between the bias-corrected estimators
and biased estimators [42]. Aouadi and Belgacem presented an evaluation of MIMO
antennas, with analysis of the mutual coupling, correlation coefficient, diversity gain
and correlation efficiency. They found that the use of the novel LHM (Left Handed
Metamaterial) with multiple bands after fractional removal of substrate was suitable
for MIMO antenna system [43]. Xu studied the uplink transmission in MIMO systems
with antenna correlation and proposed a very efficient scheme in multi-user uplink
MIMO system with distributed channel information [44]. However, few studies have
been done about the influence of multiple tags’ distribution on the reading performance in RFID-MIMO system. Therefore, this paper focuses on the multiple tags’
distribution in RFID-MIMO system.
In the MIMO system, the frequency deviation between transmitter and receiver is
mainly caused by the error between the transmitter and the receiver, and the Doppler
shift caused by the motion of the mobile station. The problem of multi frequency
deviation in MIMO system makes it more complicated to estimate the frequency deviation correctly, and it has become a joint estimation of multi parameter. The multi
parameter joint estimation based on ML principle can almost approximate the ideal
performance with the increase of signal-to-noise ratio, so it becomes a very practical
estimation method [45]. However, the above method has high complexity. Therefore, suboptimal quasi maximum likelihood algorithm is also a common method for