JP2005174191A - Electronic license plate system and auxiliary communicator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable both an intrinsic function of an electronic license plate and another application on an electronic license plate body, and to configurate it at low cost. <P>SOLUTION: When the intrinsic function of the electronic license plate body 12 is utilized, a high frequency cable 14 is disconnected from a high frequency coaxial switch 23 or 24 to switch on the transmission of a high frequency signal between a transmission/reception switching part 22 and a body reception part 21. When the electronic license plate body 12 communicates with a base station 1 of an ETC system, an auxiliary communicator 13 can be electrically connected to the body reception part 21 and a body transmission part 20 via the high frequency cable 14 to establish communication with the base station 1 while improving a system gain. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electronic license plate system using an electronic license plate in which information such as vehicle specification information is stored in an IC chip provided on a license plate, and an auxiliary communication device thereof.

  In recent years, mounting an electronic license plate on a vehicle has been studied. This electronic license plate stores information such as number information and vehicle specification information described in an automobile registration file in an IC chip, and is attached to a license plate installed in front of or after a vehicle, thereby enabling a reader / writer. This is a system that enables reading and writing (transmission and reception) of information stored in the IC chip from the outside by short-distance communication of several centimeters by means of RW (corresponding to a first wireless communication device) or the like. This electronic license plate has been studied for application to automatic reading of vehicle specification information during vehicle inspection, vehicle life cycle management, and the like.

  On the other hand, an attempt has been made to enjoy, for example, an existing DSRC (Dedicated Short Range Communication) application using the individual information (ID) stored in the IC chip of the electronic license plate. This DSRC application is used for contract parking lots, logistics centers, gas stations, convenience stores and entrance / exit management for specific facilities, automatic toll collection systems (ETC: Electronic Toll Collection System), commercial vehicle management, logistics, Passenger management, road pricing, automatic speed control, etc. can be enjoyed based on narrow-band communication between base stations installed on roads and various facilities and transceivers installed on the vehicle side Shows the application. That is, if an existing DSRC application can be enjoyed using an electronic license plate, the convenience is further improved.

An ETC system is an example of a narrow area communication (DSRC) system for providing current DSRC applications. In the ETC system, as shown in FIG. 8, a base station 1 (corresponding to a second wireless communication device) such as an ETC gate may be installed at a high place. The technical idea is different from that of the present invention, and detailed description thereof is omitted. However, as a related document, Patent Document 1 discloses an electronic license plate.
JP 2001-354084 A

When the base station 1 is installed above the vehicle A, in order to enjoy the existing DSRC application on the electronic license plate 2 side, even if the current electronic license plate is used as it is, there is a problem particularly on the receiving system. .
A schematic explanation of the defect is shown in FIG. When the electronic license plate 2 is installed on the front (or rear) of the vehicle A, the transmitter / receiver 3 provided on the electronic license plate 2 is formed in a flat plate shape without protruding on the metal license plate plane. Need to form. This is to prevent destruction due to mischief, collision, etc., and to maintain a good appearance. Therefore, since the electronic license plate 2 extends in the vertical direction with respect to the ground, the antenna that constitutes the transmitter / receiver 3 is also necessarily provided with directivity in front (or rear) of the vehicle A. Thus, the system gain when communicating with the base station 1 of the DSRC system installed above the vehicle A of the electronic license plate 2 becomes difficult to apply to the existing DSRC system. In FIG. 8A, the directivity is schematically shown by a dotted line.

  Further, the antenna constituting the transmitter / receiver 3 of the electronic license plate main body 2 needs to be formed in a flat plate shape as described above, and also needs to be configured to meet the recent demands for miniaturization and cost reduction. Therefore, it is difficult to use a ceramic chip antenna (gain of about 5 dBi) used in the on-board device for ETC. Therefore, when the antenna of the transmitter / receiver 3 is configured with a patch antenna (gain of about 0 dBi) on a high frequency glass epoxy substrate, for example, the system gain is also greatly deteriorated.

  9A and 9B, the electronic license plate body 2 is generally installed at a relatively low position from the ground of the vehicle A, and the large vehicle B is positioned in front of the vehicle A. In the structure of the vehicle A, when the bumper A1 of the vehicle A protrudes above the electronic license plate main body 2, the carrier frequency band is particularly in the 5.8 GHz band, so the straightness of the radio signal is also strong. As is apparent from the above, propagation of radio signals between the base station 1 and the transmitter / receiver 3 is hindered, and the above-described system gain may be further deteriorated.

  The present invention has been made in view of the above circumstances, and an object thereof is to be used for an electronic license plate system that can enjoy both the original functions of the electronic license plate and other applications on the electronic license plate body side, and the system. It is to provide an auxiliary communication device.

  According to the characteristics of the present invention, the transmitter / receiver of the electronic license plate main body has a license plate installed in front of or behind the vehicle, and the first wireless communication device for the electronic license plate located outside the vehicle. The auxiliary communicator receives a radio signal from a second radio communication device outside the vehicle having a function different from that of the first radio communication device, converts the radio signal into a wired signal, and converts it into an electronic license plate. Therefore, the electronic license plate main body side can enjoy an application different from the function of the electronic license plate.

  According to another feature of the present invention, the transmitter / receiver of the electronic license plate body is configured to transmit a wired signal, and the auxiliary communication device converts the wired signal transmitted from the electronic license plate body into a wireless signal. Transmitting a radio signal to the third radio communication device for another application in order to transmit to the third radio communication device having a function different from that of the first radio communication device located outside the vehicle after conversion Even if it is necessary to do so, it will be applicable to this system.

  In another feature of the present invention, the auxiliary communication device transmits a radio signal from the second radio communication device in the same carrier frequency band as the radio signal transmitted from the first radio communication device by the electronic license plate body. It is configured to be receivable, or the auxiliary communicator can transmit a radio signal to the third radio communication device in the same carrier frequency band as the radio signal transmitted from the electronic license plate body to the first radio communication device. It is configured. In this case, for example, when communication can be performed in the same carrier frequency band in an electronic license plate system and other DSRC systems, hardware for processing the high frequency band can be shared for the transceiver mounted on the vehicle side. The system developed for the existing electronic license plate can be used as it is, and the period required for system design can be shortened.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 mainly shows an electrical configuration of an electronic license plate system, and FIG. 2 schematically shows an installation state of the electronic license plate system in a vehicle. As shown in FIG. 2, the electronic license plate system 11 includes an electronic license plate main body 12 and an auxiliary communication device 13, and these configurations 12 and 13 are connected by a high-frequency cable 14.

  The electronic license plate main body 12 is installed at a predetermined position on the front and rear (not shown) of the vehicle A. As shown in FIG. 2 (c), the electronic license plate main body 12 has a module 12b (corresponding to an electronic license plate transmitter / receiver) attached to the upper left part of a plate-shaped metal license plate 12a. It is comprised by. The module 12b is also formed in a flat plate shape and includes an IC chip for control and an antenna 15 for external transmission / reception of information (see FIG. 1). The electronic license plate body 12 is generally extended vertically to the road surface at the front or rear of the vehicle.

  On the other hand, the auxiliary communicator 13 is installed on the dashboard 16 in the vehicle A as shown in FIG. 2 (a), or above the front seat of the automobile vehicle A as shown in FIG. 2 (b). There are cases where it is installed in the vicinity of the installed room mirror 17, etc., and it is provided above the electronic license plate body 12. The auxiliary communicator 13 is configured to be able to bidirectionally transmit and receive wired signals by the module 12b of the electronic license plate body 12 and the high frequency cable 14.

  FIG. 1 is a block diagram schematically showing the electrical configuration of an electronic license plate system. The electronic license plate main body 12 is electrically operated, for example, by being supplied with power from a power supply unit 18 incorporating a lithium battery, and the main unit transmission connected to the control unit 19 as a main body. A transmission / reception switching unit 22 that switches transmission / reception of the unit 20 (main transmission unit), the main body reception unit 21 and the main body built-in antenna 15 is provided.

  The main body transmission unit 20 and the transmission / reception switching unit 22 are connected via a high-frequency switch 23 having a high-frequency coaxial connector with a switch. If the auxiliary communication device 13 is not connected to the high-frequency switch 23, A high-frequency signal is transmitted between the main body transmission unit 20 and the transmission / reception switching unit 22. Similarly, the main body reception unit 21 and the transmission / reception switching unit 22 are connected via a high-frequency switch 24 having a high-frequency coaxial connector with a switch, and the high-frequency switch 24 must be connected to an auxiliary communication device 13 described later. For example, a high-frequency signal is transmitted between the main body reception unit 21 and the transmission / reception switching unit 22.

  The transmission / reception switching unit 22 switches transmission / reception timing based on the on / off control signal from the control unit 19. At the transmission timing, a transmission system circuit is formed so that power is supplied to the antenna 15 from the control unit 19 through the main body transmission unit 20 and the high frequency switch 23, and a radio signal is transmitted from the antenna 15 through the transmission system circuit to an external reader / writer RW (first output). 1 wireless communication device). At this transmission timing, the main body transmitter 20 modulates and amplifies the data signal transmitted from the controller 19. Then, a carrier wave signal obtained by modulating the data signal is transmitted from the antenna 15 to the reader / writer RW.

  The antenna 15 is configured by a patch antenna on a high-frequency glass epoxy substrate. This patch antenna is formed with a relatively small ground area, and the gain of this antenna is set to about 0 dBi, which is lower than that of a general ceramic chip antenna. The reason for using a low-gain antenna is to prevent mischief and to maintain a good appearance by forming the electronic license plate main body 12 in a flat shape without providing a protrusion on the flat plate surface. Yes (see also the problem description column). The main body reception unit 21 includes a signal switching unit 25, a detection unit 26, a wakeup unit 27, and a main reception unit 28. The signal switching unit 25 switches the high-frequency signal from the transmission / reception switching unit 22 to the detection unit 26 side or the main reception unit 28 side based on the control signal from the control unit 19. Specifically, for example, the control unit 19 switches to the detection unit 26 side in the low power consumption mode, and controls to the main reception unit 28 side in the normal operation mode.

  At the reception timing, when a radio signal is given from the reader / writer RW or the like, the detection unit 26 receives the signal received from the antenna 15 in a state where the signal switching unit 25 is switched to the detection unit 26 side in the low power consumption mode. Diode detection is applied to the wake-up unit 27. The wake-up unit 27 switches the control unit 19 to the normal operation mode when the detection signal indicating the received power exceeds a predetermined threshold value. Therefore, in the low power consumption mode, it is configured to stand by with lower power consumption than in the normal operation mode, so even if a battery power supply is used, it is possible to prevent malfunction and reduce power consumption. And can be driven by inexpensive batteries.

  When the control unit 19 is switched to the normal operation mode, the signal switching unit 25 switches the transmission direction of the high-frequency signal from the antenna 15 to the main reception unit 28 side. The main receiver 28 amplifies and shapes the applied high-frequency signal (such as down-conversion processing) and supplies the signal to the controller 19. The control unit 19 can obtain data transmitted from the reader / writer RW by performing data demodulation processing based on the given signal. In this way, when the function of the electronic license plate main body 12 is utilized, communication can be performed with the external reader / writer RW for reading the electronic license plate with the high frequency cable 14 disconnected.

  The auxiliary communicator 13 includes an auxiliary transmission unit 29 as a transmission amplifying unit and an auxiliary transmission unit, an antenna 30 connected to the auxiliary transmission unit 29, an auxiliary reception unit 31 as a reception amplifying unit and an auxiliary reception unit, An antenna 32 and a power supply unit 33 connected to the reception unit 31 are provided, and the auxiliary reception unit 31 and the auxiliary transmission unit 29 are energized from the external in-vehicle battery 34 through the power supply unit 33. The auxiliary receiving unit 31 is configured by an amplifier using a low noise amplifier, and the auxiliary transmitting unit 29 is configured by an amplifier using a power amplifier.

  The auxiliary communication device 13 is connected to the module 12 b of the electronic license plate body 12 by a high frequency cable 14. The high-frequency cable 14 is configured to efficiently transmit a bidirectional signal (high-frequency signal) in at least a frequency region of, for example, 5.8 GHz, in both directions. The frequency region of the 5.8 GHz band is a frequency region that is used in electronic license plates, ETC systems, narrow-area communication systems (various DSRC services), and the like, and is substantially the same frequency.

  In the electronic license plate system 11 and other DSRC systems, there are applications that use the same carrier frequency region (5.8 GHz band), so the hardware in the high frequency band is shared as a transceiver mounted on the vehicle A side. This is convenient for configuring the system. In the present embodiment, since the electronic license plate main body 12 is provided with the auxiliary communication unit 13, it is not necessary to change the hardware configuration of the electronic license plate main body 12 as much as possible, and the system can be constructed in a short period of time when designing the system. Become.

  Since a frequency range of 4.9 GHz band is used as the wireless LAN system, a high frequency cable 14 that efficiently transmits the frequency range applied to the wireless LAN is used, and the electronic license plate main body 12 and auxiliary communication are used. If the unit 13 is configured to be applicable to a wireless LAN system, it can be applied to an application using the wireless LAN system, which is further desirable.

The operation of the above configuration will be described with reference to FIGS.
For example, as shown in FIG. 2A or 2B, the auxiliary communication device 13 is installed on the dashboard 16 or in the vicinity of the rearview mirror 17, and the module 12b and the auxiliary communication device 13 are electrically connected by the high-frequency cable 14. Can be communicated with the base station 1 of the existing ETC system. In this case, it becomes possible to communicate with the base station 1 by connecting the auxiliary transmission unit 29 and the auxiliary reception unit 30 of the auxiliary communication device 13 to the high frequency switches 23 and 24 via the high frequency cable 14.

  This will be specifically described below. When the auxiliary transmission unit 29 of the auxiliary communication device 13 is connected to the high frequency switch 23, the connection state between the main body transmission unit 20 and the transmission / reception switching unit 22 is cut off. A high frequency signal (wired signal) is transmitted to the auxiliary transmission unit 29 of the device 13 via the high frequency cable 14. When the auxiliary receiving unit 31 of the auxiliary communication device 13 is connected to the high frequency switch 24 by the high frequency cable 14, the connection state between the main body receiving unit 21 and the transmission / reception switching unit 22 is interrupted, and conversely, the auxiliary communication device 13. A high-frequency signal (wired signal) is transmitted from the auxiliary receiver 31 to the main-body receiver 21 via the high-frequency cable 14.

At this time, as shown in FIG. 3, the auxiliary communicator 13 is installed in the vehicle A so that the antenna directivities between the base station 1 and the antennas 30 and 32 of the auxiliary communicator 13 in the ETC system face each other. Then, the propagation condition of the radio signal can be improved as compared with the case where the auxiliary communication device 13 is not used.
FIG. 4 shows simulation conditions when downlinking the ETC system and simulation conditions when downlinking is performed only with the electronic license plate body shown in the background art section of the present application. In this simulation condition, the carrier frequency band of the base station 1 (the carrier frequency band of the ETC in-vehicle communication device and the electronic license plate transceiver), the polarization of the radio signal of the base station 1, the installation height of the base station, the depression angle, Antenna directivity, transmission I. R. P is compared. Also, the installation height, elevation angle, antenna directivity, antenna gain, reception sensitivity, and communication distance of the in-vehicle communication device (electronic license plate body 12) are compared.

Of these, transmission E.I. I. R. P (Equivalent Isotropic Radiation Power) is defined as equivalent isotropic radiated power in ARIB STD-T75, and is determined by the product of antenna gain (Gt: cable loss etc.) and transmitter output (Pt). .
The gain of the antenna for the vehicle communication device in the ETC system is 5 dBi, and the gain of the antenna for the vehicle communication device in the electronic license plate system is 0 dBi. This is because the electronic license plate needs to be formed in a flat plate shape, and is about 5 dB lower than a ceramic antenna generally used for in-vehicle communication equipment of the ETC system.

  In addition, the simulation is performed assuming that the elevation angle of the antenna of the in-vehicle communication device in the ETC system is 67 degrees and the elevation angle of the antenna in the electronic license plate system is 0 degrees. 5 (a) shows the directivity of the antenna for the ETC base station 1, and FIG. 5 (b) shows the directivity of the antenna of the electronic license plate transceiver and the ETC in-vehicle communication device. . In consideration of these, FIG. 8 for explaining the conventional example schematically shows the directivity by a dotted line.

The license plates provided at the front and rear of the vehicle extend in the vertical direction on the road surface, and the in-vehicle communication device of the ETC system can be installed at the user's desired location in the vehicle. The condition is bad because it does not face station 1.
Furthermore, the installation position of the electronic license plate (about 0.5 m from the road surface) should be installed close to the road surface compared to the installation position of the in-vehicle communication equipment for ETC (on the dashboard: 1 m). So the condition is bad.

  Therefore, in FIG. 6 showing the simulation result in terms of distance versus received power, the received power is reduced by 10 dB or more. In order to adapt the electronic license plate system to the DSRC system (DSRC application), the threshold level at a frequency of 5.8 GHz and a modulation speed of 2048 kbaud should be about −40 dBm (detection output about 5 mV: see FIG. 7). Is needed. Further, as a system design requirement required on the electronic license plate side, it is necessary to consider a fluctuation margin of about 5 dB in total, which is a loss 2 dB due to an angle and a fluctuation 3 dB due to reflection. Taking these fluctuation margins into consideration, it is difficult to secure about 4 m as the communication range in the traveling direction when -40 dBm is set as the threshold value as described above.

  Therefore, as shown in the present embodiment, the system gain can be increased as compared with the conventional system by providing the auxiliary receiving unit 31 as necessary in the receiving circuit. Further, since the antenna 32 connected to the auxiliary receiving unit 31 is installed in the vehicle, it is possible to secure an installation space for the antenna 32, and an antenna having a relatively high gain such as a ceramic chip antenna is used for the antenna 32. Can be used.

  In FIG. 3, the directivity between the auxiliary communication device 13 and the ETC base station 1 is indicated by a dotted line. The auxiliary communicator 13 is installed in the vehicle A, for example, on the dashboard 16 or in the vicinity of the room mirror 17 so as to face the directivity with the ETC base station 1 above the road surface. This improves the radio signal propagation conditions. At this time, for example, the system gain can be improved by adjusting the amplification degree of the amplifier of the auxiliary receiving unit 31 so that the reception power of −60 dBm becomes −40 dBm at the input end of the electronic license plate body 12. Since the auxiliary receiver 31 is supplied with power from the battery 34, it does not affect the battery life of the power supply unit 18 of the electronic license plate body 12. Moreover, since it is the same also about the auxiliary | assistant transmission part 29, the detailed description is abbreviate | omitted.

If data communication can be performed with the base station 1 of the ETC system via the auxiliary communication unit 13 and the control unit 19 of the electronic license plate main body 12, the ETC system function can be achieved on the electronic license plate main body 12 side. Thus, applications such as toll collection on toll roads can be functionally realized on the electronic license plate body 12 side.
As described above, according to the present embodiment, when the original function of the electronic license plate body 12 is utilized, the high-frequency cable 14 is disconnected from the high-frequency coaxial switch 23 or 24 to switch the signal transmission path, and the electronic license plate Communication is possible between the main body 12 and the external reader / writer RW for reading, and when the electronic license plate main body 12 communicates with the base station 1 in the ETC system, it is assisted through the high-frequency cable 14. By connecting the communication device 13 to the main body reception unit 21 and the main body transmission unit 20, the system gain with the base station 1 can be improved, and the application of the ETC system can be changed to the electronic license plate main body 12. You can enjoy it on the side.

  The auxiliary transmission unit 29 and the auxiliary reception unit 31 of the auxiliary communication device 13 are configured to function as transmission amplification means and reception amplification means, respectively, and are installed above the electronic license plate body 12. Therefore, the system gain with the base station 1 can be improved as compared with the case where transmission / reception is performed only with the electronic license plate main body 2 installed near the road surface.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be modified or expanded as described below, for example.
Although the embodiment in which the application of the ETC system is functionally added to the electronic license plate main body 12 is shown, it may be applied to other uses of the DSRC application.

  In the embodiment, the auxiliary communication unit 13 is provided with the auxiliary transmission unit 29 (auxiliary transmission unit) and the auxiliary reception unit 31 (auxiliary reception unit). However, the embodiment is not limited thereto. What is necessary is just to provide as needed. The high frequency switch 23 or 24 may be configured to be switchable by the control unit 19.

The electrical block diagram of the electronic license plate system which shows one Embodiment of this invention (A)-(b) The figure which shows an example of an installation position, (c) The block diagram of an electronic license plate main body Diagram showing the wireless communication status (A) (b) Diagram showing simulation conditions (A) (b) Diagram showing directivity Diagram showing simulation results Diagram showing detection output vs. received power (A) FIG. 3 equivalent figure which shows a prior art example, (b) The figure which shows a conventional structure. (A) (b) is a figure which shows the conventional malfunction roughly

Explanation of symbols

In the drawings, 1 is a base station (second wireless communication device, third wireless communication device), 11 is an electronic license plate system, 12 is an electronic license plate body, 13 is an auxiliary communication device, 14 is a high-frequency cable, and 15 is An antenna, 29 is an auxiliary transmission unit (transmission amplification unit, auxiliary transmission unit), 31 is an auxiliary reception unit (reception amplification unit, auxiliary reception unit), and RW is a reader / writer (first wireless communication device).

Claims (20)

An electronic license plate body having a license plate installed in front of or behind the vehicle and having an electronic license plate transceiver for transmitting and receiving to and from the first wireless communication device for the electronic license plate located outside the vehicle; ,
An auxiliary communicator that is provided separately from the electronic license plate body and receives a radio signal from a second radio communication device outside the vehicle having a different function from the first radio communication device;
The auxiliary communication device is configured to convert a wireless signal received from a second wireless communication device into a wired signal and transmit the signal to the electronic license plate transceiver. .   The auxiliary communication device includes reception amplification means, converts a wireless signal received from the second wireless communication device into a wired signal, amplifies the reception signal by the reception amplification means, and transmits / receives the electronic license plate of the electronic license plate body The electronic license plate system according to claim 1, wherein the electronic license plate system is configured to be capable of transmitting.   3. The electronic license plate system according to claim 1, wherein the auxiliary communication device is configured to be capable of transmitting the wired signal by a high-frequency signal via a high-frequency cable.   4. The electronic license plate system according to claim 1, wherein the auxiliary communication device is configured to be installed above an installation position of the electronic license plate main body. 5.   5. The electronic license plate system according to claim 1, wherein the auxiliary communication device is configured to be able to receive a radio signal including information on an application other than an electronic license plate application.   The auxiliary communication device is configured to receive a radio signal from the second radio communication device in the same carrier frequency band as a radio signal transmitted from the first radio communication device. The electronic license plate system according to any one of 1 to 5.   7. A high frequency switch for switching to transmit a high frequency signal from the electronic license plate main body to the auxiliary communication device side when the auxiliary communication device is connected via a high frequency cable. Electronic license plate system according to any of the above. The electronic license plate body transceiver is configured to transmit a wired signal,
The auxiliary communicator converts a wired signal transmitted from the electronic license plate main body into a wireless signal to a third wireless communication device having a function different from that of the first wireless communication device located outside the vehicle. 8. The electronic license plate system according to claim 1, wherein the electronic license plate system is configured to be able to transmit.   The auxiliary communicator includes a transmission amplifying unit, amplifies the wired signal transmitted from the electronic license plate body by the transmission amplifying unit, converts the signal into a radio signal, and transmits the radio signal to the third radio communication device. 9. The electronic license plate system according to claim 8, wherein the electronic license plate system is configured to be possible.   The electronic license plate system according to claim 8 or 9, wherein the electronic license plate main body transmits the wired signal to the auxiliary communication device via a high frequency cable as a high frequency signal.   11. The electronic license plate system according to claim 8, wherein the auxiliary communication device is configured to be able to transmit a radio signal including information on an application other than the electronic license plate application.   The auxiliary communicator is configured to transmit a radio signal to the third radio communication device in the same carrier frequency band as the radio signal transmitted from the electronic license plate body to the first radio communication device. The electronic license plate system according to any one of claims 8 to 11,   13. A high frequency switch for switching to receive a high frequency signal from the auxiliary communication device to the electronic license plate main body side when the auxiliary communication device is connected via a high frequency cable. Electronic license plate system according to any of the above. Provided separately from the electronic license plate main body including the electronic license plate transceiver for wireless communication with the first wireless communication device for the electronic license plate installed outside the vehicle,
The wireless signal is received from a second wireless communication device outside the vehicle having a function different from that of the first wireless communication device, and the wireless signal is converted into a wired signal and transmitted to the electronic license plate transceiver. An auxiliary communication device comprising auxiliary reception means configured to be capable of being used.   The auxiliary reception means includes reception amplification means, converts a radio signal received from the second wireless communication device into a wired signal, amplifies the signal by the reception amplification means, and transmits / receives the electronic license plate of the electronic license plate body 15. The auxiliary communication device according to claim 14, wherein the auxiliary communication device is configured to be able to transmit to the communication device.   16. The auxiliary communication device according to claim 14, wherein the auxiliary receiving means is configured to be able to receive a radio signal including information on an application other than an electronic license plate application.   The auxiliary reception means is configured to receive a radio signal from the second radio communication device in the same carrier frequency band as the radio signal transmitted from the first radio communication device. The auxiliary communication device according to any one of 14 to 16.   Auxiliary transmission that can be transmitted to a third wireless communication device having a function different from that of the first wireless communication device installed outside the vehicle by converting a wired signal transmitted from the electronic license plate body into a wireless signal. 18. The auxiliary communication device according to claim 14, further comprising means.   The auxiliary transmission means includes transmission amplification means, and the wired signal transmitted from the electronic license plate body is amplified by the amplification means, converted into a radio signal, and transmitted to the third wireless communication device. The auxiliary communication device according to claim 18, wherein the auxiliary communication device is configured. The auxiliary communication device according to claim 18 or 19, wherein the auxiliary transmission means is configured to be able to transmit a radio signal including information on an application other than an electronic license plate application.

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