JP2006303939A - Mobile identifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile communications apparatus which holds proper communication conditions, using a simple constitution. <P>SOLUTION: A frequency hopping communication system is adopted as a radio communication means, an interrogator 20 comprises antennas 5, 6 that have different polarization planes, it is synchronized with a hopping timing by a frequency hopping controller 13, and a switch 4 switches over the antennas 5, 6 in turn to transmit and receive signals. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mobile unit identification device that performs wireless communication with a mobile information communication unit.

  Mobile identification devices using IC tags and readers / writers that use radio frequency bands and IC chips and antennas, and systems using such devices have been put to practical use in various fields such as distribution, transportation, and medical care. Yes.

  In such a mobile object identification device, generally, power is supplied from a reader / writer (interrogator) to an IC tag (responder) via an antenna, and data communication is performed mutually. Many of the 1C tags used in the system have linearly polarized antennas in order to reduce the size and simplify the structure of the 1C tags. However, when a linearly polarized antenna is used, the direction of the antenna coil of an IC tag that is put to practical use changes depending on the situation, and does not always face a certain direction. Therefore, the antenna polarization plane between the reader / writer and the IC tag is displaced, the wireless communication range is narrowed, and communication may be disabled in some cases.

  As a means for solving the communication quality deterioration due to the deviation of the polarization plane between the reader / writer and the IC tag as described above, a diversity system is used in which a plurality of antennas are provided on the reader / writer side, and an optimum antenna is selected to perform transmission / reception. It has been. In particular, as described above, when the orientation of the 1C tag changes, a polarization diversity system that switches antennas having different polarizations is effective. Note that the polarization diversity method is one of antenna diversity methods.

  FIG. 3 is a block diagram illustrating a typical receiving unit configuration of the antenna diversity method. A first antenna 31 and a first receiver 33 connected to the first antenna 31; a second antenna 32 and a second receiver 34 connected to the second antenna; The receiver outputs of 33 and 34 are combined by diversity combining section 35 and demodulated by demodulation section 36. According to this configuration, a receiver is required for each antenna. If the number of antennas is increased in order to improve reception performance, it is necessary to increase the number of receivers correspondingly, and the circuit scale increases.

  On the other hand, as described above, as a method for performing antenna diversity without increasing the number of receivers corresponding to the increase in the number of antennas, a method using an antenna selection switch has been proposed.

  FIG. 4 is a block diagram illustrating a configuration of a receiving unit using an antenna selection switch. The first antenna 5 and the second antenna 6 are arranged in the receiving unit 7 via the antenna switching switch 4, and reception is performed while switching the respective antennas so as to select the antenna of the maximum reception level before communication. The level detection unit 8 detects and holds the reception level, and the antenna that has obtained the maximum reception level is selected by a signal from the control unit 1. Furthermore, a threshold value is provided for the reception level, and switching to another antenna is performed when the reception level is equal to or less than a predetermined threshold value. There exists patent document 1 as an example of such a system.

JP-A-5-75506

  According to the antenna switching technique described above, the number of receivers increases according to the number of antennas to be switched, and the entire circuit becomes complicated. Further, when the antenna changeover switch is used, even if the number of antennas increases, one receiver is sufficient. However, the reception level detection means, the detection level / threshold value storage means, the level comparison means, the switch An additional means such as a switching timing control means is required, and there is a problem that the circuit configuration becomes complicated.

  A technical problem of the present invention is to provide a mobile object identification device that can obtain a good communication state with a simple configuration regardless of the polarization state of a responder.

  The mobile object identification device of the present invention employs a frequency hopping communication method as a wireless communication means. A plurality of antennas having different polarization planes are arranged in the interrogator, and signals are transmitted and received by sequentially switching the plurality of antennas having different polarization planes in synchronization with the frequency hopping timing of the interrogator. The interrogator repeatedly transmits at least the same signal as the number of the plurality of antennas, and employs a signal received in a good communication state among a plurality of the same response signals transmitted from the responder. Furthermore, the interrogator repeats the step of sequentially transmitting the same signal from the plurality of antennas a plurality of times, and adopts a signal received in a good communication state among a plurality of the same response signals transmitted from the responder.

  With this configuration, the interrogator reception level detection circuit, the reception level comparison unit, the timing control unit, and the prior maximum reception level that were conventionally required to select an antenna in a good reception state can be obtained. A mobile unit identification apparatus equipped with polarization switching means that can obtain a good communication state regardless of the polarization state of a responder with a simple configuration, eliminating the need for complicated algorithms required for antenna switching, etc. It is realized.

  According to the present invention, there is provided a mobile unit identification apparatus that wirelessly communicates between an interrogator and a responder using a frequency hopping communication method, the interrogator having a plurality of antennas, and having a frequency hopping timing of the frequency hopping communication method. A mobile object identification device having means for switching the plurality of antennas in synchronization can be obtained.

  According to the present invention, there is provided a mobile unit identification apparatus that wirelessly communicates between an interrogator and a responder using a frequency hopping communication method, and the interrogator has a plurality of antennas arranged so that a plurality of polarization planes do not overlap. In addition, there can be obtained a mobile object identification device comprising means for switching the plurality of antennas in synchronization with the frequency hopping timing of the frequency hopping communication method.

  According to the present invention, in the interrogator, each of the plurality of antennas can be sequentially switched so as to continuously transmit the same signal at least once or more.

  According to the present invention, it is not necessary to provide an algorithm associated with reception level detection means, reception level comparison means, switch switching means, etc., thereby suppressing an increase in hardware and software resources and improving communication accuracy with a simple configuration. A mobile object identification device can be provided.

  The mobile object identification device according to the present invention uses a frequency hopping communication method for an interrogator and switches antennas in synchronization with the frequency hopping timing even though a plurality of antennas having different characteristics are used. Communication accuracy is improved by a simple circuit configuration without using a complicated control means for switching the antenna.

  The number of antennas connected to the interrogator used in the present invention is not limited and may be any number as long as it is one or more. In addition, the antenna may be used in combination with a horizontally polarized wave antenna and a vertically polarized wave antenna, as necessary, and antennas whose polarization plane angles are changed more finely. In consideration of the simplification of the configuration of the entire apparatus, two antennas are preferably connected to the interrogator, and it is more preferable that one antenna is a horizontally polarized antenna and the other is a vertically polarized antenna.

  The interrogator repeatedly transmits at least the same signal as the number of the plurality of antennas, and employs a signal received in a good communication state among a plurality of the same response signals transmitted from the responder. Furthermore, the interrogator repeats the step of sequentially transmitting the same signal from the plurality of antennas a plurality of times, and adopts a signal received in a good communication state among a plurality of the same response signals transmitted from the responder. The number of signals transmitted from the interrogator and the number of steps for transmitting the same interrogation signal can be arbitrarily set. However, in consideration of communication efficiency, response speed, and the like, both are preferably 1 to 2 times.

  The combination of the number of antennas, the angle of the polarization plane, the number of repetitions of the interrogation signal, and the number of repetition steps is preferably set arbitrarily as necessary.

  FIG. 1 is a block diagram illustrating the configuration of an interrogator and a responder of the mobile object identification device of the present invention.

Example 1
The interrogator 20 includes a control unit 1, a transmission unit 2, a circulator 3, an antenna switching switch 4, a first antenna 5, a second antenna 6, a reception unit 7, a switch control unit 11, and a hopping control unit 13. The responder 22 includes a storage unit 16, a modulator 15, and an antenna 14. The interrogator 20 and the responder 22 communicate with the antenna 5 or the antenna 6 via the antenna 14. The antenna 5 is a vertical polarization antenna, and the antenna 6 is a horizontal polarization antenna.

  The antenna 5 and the antenna 6 are simply switched sequentially at the timing of frequency hopping regardless of the state of the responder 22, that is, the reception level of the response signal from the responder 22. The interrogator 20 is in an area where the individual identification data (hereinafter referred to as ID) of the responder 22 can be read. The responder 22 is constantly moving within the above range.

  In the first step, the transmitter 2 of the interrogator 20 modulates the data received from the controller 1, hops the radio frequency that is a carrier wave under the control of the hopping controller 13, and outputs a transmission wave. The transmitted wave passed through the circulator 3 and transmitted an interrogation signal through the vertically polarized antenna 5 selected by the switch 4. The responder 22 cannot receive this signal because the antenna polarization planes do not match. Therefore, the interrogator 20 cannot receive the response signal at a certain level or higher, and communication has not been performed normally.

  In the second step, the switch 4 of the interrogator 20 is automatically switched to the connection to the horizontally polarized antenna 6 in synchronism with the next frequency hopping timing. The same question signal as the question signal transmitted in one step was transmitted. Since the plane of polarization of the antenna of the interrogator 20 has changed, the responder 22 receives the interrogation signal by the antenna 14, demodulates it by the modulation unit 15, and then reads out data from the storage unit 16 according to the interrogation signal. The writing process was performed, and a response signal was transmitted from the modulator 15 to the interrogator 20 via the antenna 14 again. The interrogator 20 received the response signal at a certain level or higher, and communication was performed normally.

  In the third step, the switch 4 of the interrogator 20 is automatically switched to the connection to the vertically polarized antenna 5 in synchronization with the next frequency hopping timing, and the interrogator 20 is switched to the first via the antenna 5. And the question signal different from the question signal transmitted at the 2nd step was transmitted. The responder 22 receives this signal and transmits a response signal to the interrogator 20. The interrogator 20 received the response signal at a certain level or higher, and communication was performed normally.

  In the fourth step, the switch 4 of the interrogator 20 is automatically switched to the connection to the horizontally polarized antenna 6 in synchronism with the next frequency hopping timing. The same question signal as the question signal transmitted in the step was transmitted. The responder 22 receives this signal and transmits a response signal to the interrogator 20. The interrogator 20 received the response signal at a certain level or higher, and communication was performed normally.

Thereafter, the interrogator 20 repeats the operations of the first to fourth steps, and the moving responder 22 is always at a certain level at least once among the interrogation signals repeatedly transmitted from the interrogator 20 twice. As a result, communication was normally performed as a whole.
(Comparative example)

  FIG. 2 is a block diagram for explaining a moving body identification apparatus adopting a diversity method of a comparative example. The interrogator 21 includes a control unit 1, a transmission unit 2, a circulator 3, an antenna switching switch 4, a first antenna 5, a second antenna 6, a reception unit 7, a reception level detection unit 8, a storage unit 9, and a reception level. The comparator 10, the switch controller 11, the timing controller 12, and the hopping controller 13 are included. The first antenna 5 is a vertical polarization antenna, and the second antenna 6 is a horizontal polarization antenna. The responder 22 includes a storage unit 16, a modulation unit 15, and an antenna 14. The interrogator 21 is in an area where the individual identification data (hereinafter referred to as ID) of the responder 22 can be read. The responder 22 is constantly moving within the above range.

  In the first step, the transmission unit 2 of the interrogator 21 modulates the data received from the control unit 1, hops the radio frequency that is a carrier wave under the control of the hopping control unit 13, and outputs a transmission wave. The transmitted wave passed through the circulator 3 and transmitted an interrogation signal through the vertically polarized antenna 5 selected by the switch 4. The responder 22 could not receive this signal at a constant level. Accordingly, the interrogator 21 cannot receive the response signal at a constant level, and communication has not been performed normally.

  As a second step, the response signal that is less than a certain level transmitted by the responder 22 was received by the receiving unit 7 via the antenna 5 and the circulator 3 of the interrogator 21. The control unit 1 of the interrogator 21 receives the data from the reception unit 7, detects the reception level of the response signal by the reception level detection unit 8, and temporarily stores it in the storage unit 9, while determining a predetermined reception level value. In other words, the reception level comparison unit 10 compares the antenna switching threshold and the signal level of the response signal just received. Since this response signal did not reach a certain level, that is, the threshold for antenna switching, an antenna switching signal was sent from the switch control unit 11 to the switch 4, and the antenna was switched to the horizontally polarized antenna 6.

  In the third step, the interrogator 21 transmits the same question signal as the question signal transmitted in the first step via the antenna 6. Since the plane of polarization of the antenna of the interrogator 21 has changed, the responder 22 receives the interrogation signal by the antenna 14, demodulates it by the modulator 15, and then reads out data from the storage unit 16 according to the interrogation signal. Write processing was performed, and a response signal was transmitted from the modulator 15 to the interrogator 21 via the antenna 14 again. The interrogator 21 receives this response signal, and as a result of detecting, storing, and comparing the level of the response signal in the same routine as in the second step, has reached a certain reception level.

  In the third step, the interrogator 21 receives the response signal from the responder 22 at a constant reception level, so that the communication is considered to have been normally performed, and the interrogator 21 does not perform antenna switching. An interrogation signal different from the next first and second interrogation signals was transmitted.

  Thereafter, the interrogator 21 repeats the operations of the first and second steps, and the moving responder 22 keeps the same interrogation signal transmitted repeatedly from the interrogator 21 until communication is normally established, once each. As a whole, communication was performed normally.

(Example 2)
A mobile unit identification apparatus similar to that of the first embodiment, in which, in addition to the antenna 5 and the antenna 6 of the interrogator 20, an interrogator having four antennas whose polarization planes are different by 45 ° intervals and the same responder as the embodiment Prepared. As a result of conducting an experiment under the same conditions as in Example 1, a good communication result similar to that in Example 1 was obtained. In addition, compared with Example 1, since the number of antennas increased, many different interrogation signals could be transmitted, and communication responsiveness was improved.

(Example 3)
A responder mobile unit identification device similar to that of the first embodiment, which includes an interrogator that can be arbitrarily set to transmit each interrogation signal three times or more in each step, and a responder identical to the first embodiment. As a result of conducting an experiment under the same conditions as in Example 1 by changing the number of repeated transmissions of the same question signal transmitted from the interrogator under the same conditions as in Example 1 to 3, 4, and 5 respectively. Good communication results similar to Example 1 were obtained. Note that each time the number of repeated transmissions increases, the number of receptions of the same response signal with respect to the same question signal exceeding a certain level increases, thereby further improving the reliability of communication.

Example 4
The same responder mobile unit identification apparatus as that of the first embodiment, which is the same as the interrogator and the embodiment that can be arbitrarily set so that each of the first step to the fourth step is repeated three times or more. A responder was prepared. As a result of performing an experiment under the same conditions as in Example 1 by changing the number of repetitions from the first step to the fourth step to 3 times, 4 times, and 5 times under the same conditions as in Example 1. Good communication results similar to those of 1 others were obtained. Each time the number of repetitions increases, the number of receptions of the same response signal with respect to the same question signal exceeding a certain level increases, and the reliability of communication is further improved.

(Example 5)
The responder mobile unit identification apparatus similar to that of the first embodiment includes four antennas having different planes of polarization at 45 ° intervals in addition to the antenna 5 and the antenna 6 of the interrogator 20, and each query signal is processed in each step. The interrogator that can be arbitrarily set to transmit three times or more and the same responder as in Example 1 were prepared. As a result of conducting experiments under the same conditions as in Examples 2 and 3, good communication results similar to those in Example 1 and others were obtained. As in the second embodiment, the number of antennas increases, so that many different interrogation signals can be transmitted, and communication responsiveness is improved. As in the third embodiment, every time the number of repeated transmissions increases, the number of receptions of the same response signal with respect to the same interrogation signal exceeds a certain level, and the communication reliability is further improved.

(Example 6)
The responder mobile unit identification apparatus is the same as that of the first embodiment, and includes four antennas having different planes of polarization at 45 ° intervals in addition to the antenna 5 and the antenna 6 of the interrogator 20. The interrogator that can be arbitrarily set to repeat the steps up to 4 steps each three times or more and the same responder as in Example 1 were prepared. As a result of experiments under the same conditions as in Examples 2 and 4, good communication results similar to those in Example 1 and others were obtained. As in the second embodiment, the number of antennas increases, so that many different interrogation signals can be transmitted, and communication responsiveness is improved. Further, as in the fourth embodiment, each time the number of repetitions increases, the number of receptions of the same response signal with respect to the same question signal exceeding a certain level increases, and the communication reliability is further improved.

  The above-described examples and comparative examples are compared. As is apparent from the block diagrams of FIG. 1 showing the present invention and FIG. 2 showing the comparative example, the antenna switching is performed by the diversity operation in the comparative example. Numerous algorithms including means are indispensable and have a complicated block configuration.

  On the other hand, in each embodiment of the present invention, as shown in FIG. 1, the control unit 1 has the same configuration as the comparative example with a simple configuration having only a switch control unit and a hopping frequency control unit. Yes.

  Also, for example, when a plurality of responders exist in the communication range with the interrogator in different directions, if the reception level value is used as the antenna switching threshold as in the comparative example, the antenna polarization is one of the responses. Even if communication can be satisfactorily communicated with the responder, the reception sensitivity may be poor with respect to other responders, and it is assumed that all the responders cannot be recognized.

  In order to avoid the above phenomenon, it is necessary to further store the state of each responder while switching the antenna polarization, and to further change the antenna polarization plane according to each state. An algorithm is required. When such a complex algorithm is required, the load on hardware and software increases as described above, and the block configuration becomes complicated and the data processing speed also decreases.

  In the interrogator, as another method of selecting an antenna having the maximum reception sensitivity, a means of using a preamble signal for obtaining transmission / reception synchronization can be considered, but more detailed control and communication protocols are included than in the comparative example. It is necessary to introduce a new algorithm, which similarly increases hardware and software resources.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to the embodiments, and the present invention can be applied even if there is a design change without departing from the gist of the present invention. include. That is, it goes without saying that various modifications and corrections that can be made by those skilled in the art are included.

  The present invention can be widely used in general management systems for articles and the like that perform individual identification using a so-called RFID such as an IC tag.

The block diagram explaining the structure of the interrogator and responder of the mobile body identification device of this invention. The block diagram explaining the structure of the interrogator and responder of the mobile body identification device of a comparative example. The block diagram explaining the receiving part of the conventional diversity system. The block diagram explaining the receiving part of the conventional diversity system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control part 2 Transmission part 3 Circulator 4 Switch 5, 6, 14, 31, 32 Antenna 7 Reception part 8 Reception level detection part 9 Storage part 10 Reception level comparison part 11 Switch control part 12 Timing control part 13 Hopping control part 15 Modulation Unit 16 Storage unit 20, 21 Interrogator 22 Response unit 33, 34 Receiver 35 Diversity combining unit 36 Demodulating unit

Claims (3)

  A mobile unit identification apparatus that wirelessly communicates between an interrogator and a responder by a frequency hopping communication method, wherein the interrogator has a plurality of antennas, and the plurality of the plurality of antennas are synchronized with a frequency hopping timing of the frequency hopping communication method. A moving body identification device comprising means for switching the antenna of the mobile phone.   A mobile unit identification apparatus for wirelessly communicating between an interrogator and a responder by a frequency hopping communication method, wherein the interrogator has a plurality of antennas arranged so that a plurality of polarization planes do not overlap, and the frequency hopping communication A moving body identification apparatus comprising means for switching the plurality of antennas in synchronization with a frequency hopping timing of a system.   In the interrogator, each of the plurality of antennas is sequentially switched so as to continuously transmit the same signal at least once or more.

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