In-vehicle communication system

Abstract

To provide an in-vehicle communication system capable of communication even in emergency situations.SOLUTION: An in-vehicle communication system installed in a vehicle includes an in-vehicle communication device and a plurality of antennas including a first antenna and a second antenna connected to the in-vehicle communication device. The first antenna is provided inside or on top of an instrument panel of the vehicle, and the second antenna is provided on a front window glass of the vehicle. The first and second antennas constitute MIMO in which a plurality of antennas transmit and receive radio waves and at frequencies between 410 MHz and 7 GHz, the correlation coefficient between the first and second antennas is equal to or less than 0.3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The present disclosure relates to an in-vehicle communication system, and particularly to an in-vehicle communication system having a plurality of antennas.

Background Art

[0002] In a mobile phone system, MIMO (Multi Input Multi Output) using antennas installed at spatially separated locations is adopted. Therefore, in an in-vehicle communication system, a plurality of antennas are installed on a glass window that forms the boundary between the inside and outside of the vehicle and on the roof of the vehicle body.

[0003] As the background art in this technical field, there is the following prior art. Patent Document 1 (International Publication No. 2017 / 7025) describes an in-vehicle antenna used for wireless communication of a vehicle, which includes a horizontally polarized antenna and a vertically polarized antenna spaced apart from the horizontally polarized antenna by a predetermined distance, and the in-vehicle antenna obtains a plurality of signals simultaneously transmitted using polarization technology from a plurality of signals received using the horizontally polarized antenna and the vertically polarized antenna.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Recently, there has been a demand to equip vehicles with emergency call systems. For example, 5G mobile phone systems use four antennas to configure MIMO to send and receive signals, but it is necessary to enable communication via the emergency call system even in the event of an accident in which airbags deploy.

[0006] This disclosure aims to provide an in-vehicle communication system that enables communication even in emergency situations. [Means for solving the problem]

[0007] In other words, the present disclosure (1) is an in-vehicle communication system mounted in a vehicle, comprising an in-vehicle communication device and a plurality of antennas including a first antenna and a second antenna connected to the in-vehicle communication device, wherein the first antenna is provided inside or on the instrument panel of the vehicle, and the second antenna is provided on the front windshield of the vehicle, and the first antenna and the second antenna constitute MIMO for transmitting and receiving radio waves with a plurality of antennas, and the correlation coefficient between the first antenna and the second antenna is 0.3 or less in the frequency range of 410 MHz to 7 GHz. The in-vehicle communication device transmits and receives confirmation signals that allow it to confirm the connection with the second antenna. If the confirmation signal cannot be detected for a predetermined time, it determines whether the front window glass on which the second antenna is installed has been damaged in a vehicle accident. If the front window glass has been damaged in a vehicle accident, it transmits an emergency notification signal to one or all of the antennas. This is an in-vehicle communication system characterized by the following features.

[0008] Furthermore, Disclosure (2) is an in-vehicle communication system as described in Disclosure (1), wherein the second antenna is provided on the upper side of the front window glass.

[0009] Furthermore, Disclosure (3) may be an in-vehicle communication system as described in Disclosure (2), wherein the second antenna is provided within 120 mm from the top edge of the front window glass.

[0010] Furthermore, Disclosure (4) may be an in-vehicle communication system as described in Disclosure (3), wherein the second antenna is located within 20% of the distance between the upper and lower edges of the front windshield, from the upper edge of the front windshield.

[0011] Furthermore, Disclosure (5) may be an in-vehicle communication system as described in any one of Disclosures (1) to (4), wherein the in-vehicle communication device is provided inside the instrument panel and is an in-vehicle communication system having a wireless circuit that processes radio waves transmitted and received by the first antenna and the second antenna.

[0012] Furthermore, disclosure (6) may also be an in-vehicle communication system described in any one of disclosures (1) to (5), wherein the second antenna is an in-vehicle communication system in which the average value obtained by combining the antenna sensitivity measured in horizontal polarization and vertical polarization while not mounted on a vehicle in the operating frequency band is -5 dBi or higher.

[0013] Furthermore, Disclosure (7) may also be an in-vehicle communication system described in any one of Disclosures (1) to (6), wherein the second antenna is an antenna that transmits or receives radio waves in multiple operating frequency bands between 410 MHz and 7 GHz.

[0014] Furthermore, Disclosure (8) may also be an in-vehicle communication system according to any one of Disclosures (1) to (7), wherein the first antenna is provided in the vicinity of the in-vehicle communication device (preferably with a cable length of 100 cm or less between the first antenna and the in-vehicle communication device, preferably 60 cm or less), or is configured integrally with the in-vehicle communication device.

[0015] Furthermore, disclosure (9) may be an in-vehicle communication system described in any one of disclosures (1) to (8), wherein the first antenna and the second antenna constitute a 2x2 MIMO system that transmits or receives radio waves using two antennas.

[0016] Furthermore, Disclosure (10) may also be an in-vehicle communication system according to any one of Disclosures (1) to (8), further comprising a third antenna and a fourth antenna connected to the in-vehicle communication device, wherein the first antenna, the second antenna, the third antenna and the fourth antenna constitute a 4x4 MIMO system that transmits and receives radio waves using four antennas.

[0017] Further, the present disclosure (11) may be an in-vehicle communication system according to any one of the present disclosures (1) to (9), further comprising a third antenna connected to the in-vehicle communication device and provided on the rear window glass of the vehicle.

[0018] Further, the present disclosure (12) may be an in-vehicle communication system according to any one of the present disclosures (1) to (9), further comprising a fourth antenna connected to the in-vehicle communication device and provided on the front window glass.

[0019] Further, the present disclosure (13) may be an in-vehicle communication system according to any one of the present disclosures (1) to (12), wherein the in-vehicle communication device receives a signal outputted with the operation of an airbag from an electronic control device mounted on the vehicle, and transmits an emergency notification signal to one or all of the antennas.

[0022] Further, the present disclosure ( 14 ) may be the in-vehicle communication system according to the present disclosure (13), wherein the in-vehicle communication device transmits and receives a confirmation signal capable of confirming connection with the second antenna, and when the confirmation signal cannot be detected for a predetermined time and the operation of the electronic control device cannot be confirmed, it is determined that the front window glass has been damaged due to an accident of the vehicle, and an emergency notification signal is transmitted to one or all of the antennas.

[0023] Further, the present disclosure ( 15 ) may be the in-vehicle communication system according to the present disclosure (13), wherein the in-vehicle communication device transmits and receives a confirmation signal capable of confirming connection with the second antenna, and when the confirmation signal cannot be detected for a predetermined time, it may inquire the occupant whether an accident has occurred in the vehicle.

Advantages of the Invention

[0024] According to one aspect of the present disclosure, communication can be performed by the in-vehicle communication system even when an emergency occurs in the vehicle.

Brief Description of the Drawings

[0025] [Figure 1] It is a block diagram showing the configuration of the in-vehicle communication system of Example 1. [Figure 2] In Example 1, it is a diagram showing the arrangement of devices installed in the vehicle. [Figure 3] In Example 2, it is a diagram showing the arrangement of devices installed in the vehicle. [Figure 4] In Example 3, it is a diagram showing the arrangement of devices installed in the vehicle. [Figure 5] It is a diagram showing the arrangement of the second antenna in the front window glass of Example 3.

Modes for Carrying Out the Invention

[0026] <Example 1> FIG. 1 is a block diagram showing the configuration of the in-vehicle communication system of Example 1 of the present disclosure.

[0027] The in-vehicle communication system of Embodiment 1 includes an in-vehicle communication device 10, a first antenna 1A, and a second antenna 2A. The in-vehicle communication device 10 is connected to the first antenna 1A and the second antenna 2A, and communicates by configuring 2x2 MIMO (Multi Input Multi Output) with the first antenna 1A and the second antenna 2A. The first antenna 1A and the second antenna 2A are antennas that transmit or receive radio waves in multiple operating frequency bands between 410 MHz and 7 GHz. The in-vehicle communication device 10 is a communication device for a mobile phone system and may be a communication device that supports both 4G and 5G, or a communication device that supports either 4G or 5G. The in-vehicle communication device 10 is a communication device referred to as a TCU (Telematics Control Unit), DCM (Data Communication Module), etc., and has a baseband processing unit 11, a wireless circuit unit 12, and a control unit 13. The baseband processing unit 11 performs digital signal modulation and demodulation processing. The wireless circuit unit 12 converts and amplifies the digital signal modulated by the baseband processing unit 11 to a radio frequency and outputs it to the first antenna 1A and the second antenna 2A. The wireless circuit unit 12 also amplifies the signals received by the first antenna 1A and the second antenna 2A and converts them to baseband signals. The control unit 13 controls the operation of the in-vehicle communication device 10, including the baseband processing unit 11 and the wireless circuit unit 12.

[0028] The airbag ECU 20 is an electronic control unit having a microcontroller 21, an output unit 22, and a communication interface 23. The microcontroller 21 has a processor that executes programs and a memory that stores programs and data, and controls the operation of the airbag 25. The output unit 22 is connected to the airbag 25 and outputs an operation signal to the airbag 25. The communication interface 23 communicates with other ECUs and the in-vehicle communication device 10 using predetermined protocols such as CAN (Controller Area Network), FlexRay, and Ethernet. When a connected sensor (not shown) detects a large acceleration or a large pressure, the airbag ECU 20 outputs an operation signal to the airbag 25.

[0029] Airbag 25 deploys by igniting the incendiary agent in response to an operating signal output from the airbag ECU 20.

[0030] The in-vehicle communication device 10 is connected to the airbag ECU 20. If communication with the airbag ECU 20 to confirm the driver's status is lost, or if the in-vehicle communication device 10 receives an emergency communication request signal from the airbag ECU 20, it transmits an emergency communication to a predetermined recipient. For example, the airbag ECU 20 transmits an emergency communication request signal to the in-vehicle communication device 10 in conjunction with the operation of the airbag 25. The emergency communication request signal may be the operation signal of the airbag 25 itself, or a signal transmitted by the airbag ECU 20 after detecting the operation of the airbag 25. The in-vehicle communication device 10 transmits an emergency notification signal to some or all of the available antennas. This emergency communication may be voice communication or data communication.

[0031] The in-vehicle communication device 10 communicates with the airbag ECU 20 to confirm whether the airbag ECU 20 is operationally stable. The in-vehicle communication device 10 can determine if the airbag ECU 20 has stopped operating if the confirmation response from the airbag ECU 20 to the confirmation request sent from the in-vehicle communication device 10 at a predetermined timing is interrupted, if the confirmation communication sent from the airbag ECU 20 at a predetermined timing is interrupted, or if the results of the monitoring of the airbag ECU by other ECUs become abnormal.

[0032] Furthermore, the in-vehicle communication device 10 transmits a weak high-frequency signal (preferably outside the aforementioned operating frequency band) to the second antenna 2A as a connection confirmation signal, detects the reflection level of the high-frequency signal, and confirms the connection with the second antenna 2A. If the in-vehicle communication device 10 cannot detect the connection confirmation signal with the second antenna 2A for a predetermined time, it transmits an emergency notification signal to some or all of the available antennas. The connection confirmation signal from the in-vehicle communication device 10 to the second antenna 2A should preferably be transmitted at predetermined intervals (for example, continuously or intermittently).

[0033] Furthermore, if the in-vehicle communication device 10 cannot detect a connection confirmation signal with the second antenna 2A for a predetermined time, it may determine whether the front window glass 41 on which the second antenna 2A is installed has been damaged in an accident involving the vehicle 100. If the front window glass 41 has been damaged in an accident involving the vehicle 100, it may transmit an emergency notification signal to some or all of the available antennas.

[0034] One method for determining whether the front windshield 41 was damaged in an accident involving vehicle 100 is to check the operation of the airbag ECU. Specifically, if the in-vehicle communication device 10 cannot detect a connection confirmation signal with the second antenna 2A for a predetermined time, and the live / death confirmation signal with the airbag ECU 20 is interrupted, and the operation of the airbag ECU 20 cannot be confirmed, it may determine that the front windshield 41 was damaged due to an accident involving vehicle 100, and may transmit an emergency notification signal to some or all of the available antennas.

[0035] One way to determine whether the front windshield 41 of vehicle 100 has been damaged in an accident is to inquire with the occupants. That is, if the in-vehicle communication device 10 cannot detect a connection confirmation signal with the second antenna 2A for a predetermined time, it may display a screen on the control panel or navigation device prompting the occupants to input whether an accident has occurred in vehicle 100, or it may emit a voice message asking the occupants whether an accident has occurred in vehicle 100, thereby inquiring with the occupants about the occurrence of an accident.

[0036] Figure 2 shows the arrangement of equipment installed on the vehicle 100 in Example 1, and depicts the vehicle 100 as viewed from above.

[0037] The vehicle 100 is equipped with at least an on-board communication device 10, a first antenna 1A, a second antenna 2A, and an airbag ECU 20. The on-board communication device 10, the first antenna 1A, and the airbag ECU 20 are preferably located near the instrument panel 30. For example, the on-board communication device 10 and the airbag ECU 20 may be mounted inside the instrument panel 30 (for example, behind the speedometer) or below it (for example, at the passenger's feet), and the first antenna 1A may be mounted inside or on top of the instrument panel 30. The instrument panel 30 is an interior component that covers the area or space in front of the driver's seat where instruments, switches, monitors, etc. are housed, and is mounted below the front windshield 41. The first antenna 1A may be installed near the in-vehicle communication device 10 (for example, the cable length between the first antenna 1A and the in-vehicle communication device 10 is 100 cm or less, preferably 60 cm or less), or it may be integrated with the in-vehicle communication device 10. The first antenna 1A may consist of one antenna or multiple antennas. First antenna For example, in 1A, antennas capable of transmitting and receiving over a wide bandwidth, such as a bowtie antenna, or antennas composed of multiple elements optimized for transmitting and receiving across multiple frequency bands can be used.

[0038] The second antenna 2A is provided on the upper side of the front window glass 41. As shown in Figure 5, the second antenna 2A is preferably provided within 120 mm of the upper edge of the front window glass 41. Alternatively, the second antenna 2A may be provided within 20% of the distance between the upper and lower edges of the front window glass 41 from the upper edge of the front window glass 41. Furthermore, the second antenna 2A may be provided within 100 mm of the body flange (end of the body opening) of the vehicle 100 to which the front window glass 41 is attached. Second antennaAs 2A, an antenna device having L-shaped, triangular, or square planar elements with two sides of different lengths and a core wire side feed section can be used, as disclosed in International Publication No. 2022 / 163447. The planar elements may be formed from a conductive material in a solid planar form or in a mesh-like planar form. The second antenna 2A may be formed by printing a conductive ceramic paste containing metal powder such as silver onto a glass surface, drying it, and then baking it in a heating furnace. Alternatively, an antenna conductor may be formed by a conductive pattern formed on a resin film, and the resin film may be attached to a glass plate. The second antenna 2A may also be an antenna composed of a three-dimensionally formed conductor (e.g., a patch antenna, an antenna housed in a case, or a bent metal plate disclosed in International Publication No. 2019 / 151407). Furthermore, the second antenna 2A may be attached to a bracket or cover of a forward-facing camera mounted on the front window glass 41.

[0039] The second antenna 2A may have good characteristics at a portion of the operating frequency band and transmit or receive signals, or it may have good characteristics at the entire operating frequency band and transmit or receive signals.

[0040] In Example 1, by arranging the first antenna 1A and the second antenna 2A in this manner, the correlation coefficient between the first antenna 1A and the second antenna 2A becomes 0.3 or less in the frequency range of 410 MHz to 7 GHz, and sufficient characteristics are obtained in MIMO.

[0041] Furthermore, it is desirable that either or both of the first antenna 1A and the second antenna 2A have a combined average value of antenna sensitivity measured with horizontal polarization and vertical polarization when not mounted on a vehicle, in the operating frequency band (the frequency band used by the in-vehicle communication device 10 between 410 MHz and 7 GHz, particularly 700 to 960 MHz).

[0042] Next, a modified example of Embodiment 1 will be described. In the modified example of Embodiment 1, two first antennas 1A are provided. Specifically, two first antennas 1A are provided in an antenna unit located within the instrument panel 30.

[0043] <Example 2> In the in-vehicle communication system of Example 2, four antennas are connected to the in-vehicle communication device 10, and these four antennas constitute a 4x4 MIMO configuration. In Example 2, the differences from Example 1 described above will be mainly explained, and the same reference numerals will be used for components identical to those in Example 1, and their explanations will be omitted.

[0044] Figure 3 shows the arrangement of equipment installed on the vehicle 100 in Example 2, and shows the vehicle 100 as viewed from above.

[0045] The in-vehicle communication system of Embodiment 4 includes an in-vehicle communication device 10, a first antenna 1A, a second antenna 2A, a third antenna 3, and a fourth antenna 4.

[0046] The vehicle 100 is equipped with at least an in-vehicle communication device 10, a first antenna 1A, a second antenna 2A, a third antenna 3, a fourth antenna 4, and an airbag ECU 20. The wireless circuit section 12 of the in-vehicle communication device 10 is connected to the first antenna 1A and the second antenna 2A, as well as the third antenna 3 and the fourth antenna 4. The wireless circuit section 12 outputs radio frequency signals to the first antenna 1A, the second antenna 2A, the third antenna 3, and the fourth antenna 4, and amplifies and detects the signals received by the first antenna 1A, the second antenna 2A, the third antenna 3, and the fourth antenna 4.

[0047] The in-vehicle communication device 10 of Embodiment 2 communicates using a 4x4 MIMO (Multi Input Multi Output) configuration with a first antenna 1A, a second antenna 2A, a third antenna 3, and a fourth antenna 4. The first antenna 1A, the second antenna 2A, the third antenna 3, and the fourth antenna 4 are antennas that transmit or receive radio waves in multiple operating frequency bands between 410 MHz and 7 GHz. The in-vehicle communication device 10, the first antenna 1A, and the airbag ECU 20 are preferably located below the instrument panel 30. The first antenna 1A may be mounted on the back of the instrument panel 30, or it may be mounted on or near the instrument panel 30. The first antenna 1A may be provided near the in-vehicle communication device 10, or it may be configured integrally with the in-vehicle communication device 10. The second antenna 2A is provided on the upper side of the front windshield glass 41. As shown in Figure 5, the second antenna 2A is preferably provided within 120 mm from the upper edge of the front windshield glass 41. Furthermore, the second antenna 2A may be provided at a position within 20% of the distance between the top and bottom edges of the front window glass 41, from the top edge of the front window glass 41.

[0048] The second antenna 2A is formed by printing each wire approximately 0.7 mm wide onto a glass surface using a conductive ceramic paste, drying it, and then firing it in a heating oven. Alternatively, an antenna conductor may be formed by creating a conductive pattern on a light-transmitting resin film, and the resin film may be attached to a glass plate.

[0049] The third antenna 3 is provided on the upper side of the rear window glass 42, preferably within 120 mm from the upper edge of the rear window glass 42. Alternatively, the third antenna 3 may be provided at a position within 20% of the distance between the upper and lower edges of the rear window glass 42, relative to the upper edge of the rear window glass 42.

[0050] The fourth antenna 4 is mounted on the roof of the vehicle, and may be, for example, a whip antenna or a shark fin antenna with a built-in flat plate element. The shark fin in which the fourth antenna 4 is housed contains: Fourth antennaIn addition to 4, antennas for FM and AM radio reception, GPS, ITS, and V2X may also be housed.

[0051] In Example 2, by arranging the first antenna 1A, the second antenna 2A, the third antenna 3, and the fourth antenna 4 in this manner, the correlation coefficients between the first antenna 1A, the second antenna 2A, the third antenna 3, and the fourth antenna 4 become 0.3 or less in the frequency range of 410 MHz to 7 GHz, and sufficient characteristics are obtained in MIMO.

[0052] Furthermore, it is desirable that some or all of the antennas, including the first antenna 1A, the second antenna 2A, the third antenna 3, and the fourth antenna 4, have a combined average value of their antenna sensitivity measured in horizontal and vertical polarization while not mounted on a vehicle, in the operating frequency band (the frequency band used by the in-vehicle communication device 10 between 410 MHz and 7 GHz, particularly 700 to 960 MHz).

[0053] <Example 3> In the in-vehicle communication system of Example 3, six antennas are connected to the in-vehicle communication device 10. Two antennas configure 2x2 MIMO for 4G, and four antennas configure 4x4 MIMO for 5G. In Example 3, the differences from Examples 1 and 2 described above will be explained in detail, and the same reference numerals will be used for components identical to those in Examples 1 and 2, and their explanations will be omitted.

[0054] Figure 4 shows the arrangement of equipment installed on the vehicle 100 in Example 3, and shows the vehicle 100 as viewed from above.

[0055] The in-vehicle communication system of Embodiment 3 includes an in-vehicle communication device 10, first antennas 1A and 1B, second antennas 2A and 2B, third antenna 3, and fourth antenna 4.

[0056] The vehicle 100 is equipped with at least an in-vehicle communication device 10, a first antenna 1A, a first antenna 1B, a second antenna 2A, a second antenna 2B, a third antenna 3, a fourth antenna 4, and an airbag ECU 20. The wireless circuit section 12 of the in-vehicle communication device 10 is connected to the first antenna 1A and the second antenna 2A, as well as the first antenna 1B, the second antenna 2B, the third antenna 3, and the fourth antenna 4.

[0057] In the in-vehicle communication system of Embodiment 3, for example, the first antenna 1B and the fourth antenna 4 configure 2x2 MIMO for 4G communication, and the first antenna 1A, the second antenna 2A, the second antenna 2B, and the third antenna 3 configure 4x4 MIMO (Multi Input Multi Output) for communication. The first antennas 1A and 1B, the second antennas 2A and 2B, the third antenna 3, and the fourth antenna 4 are antennas that transmit or receive radio waves in multiple operating frequency bands between 410 MHz and 7 GHz. The in-vehicle communication device 10, the first antenna 1A, the first antenna 1B, and the airbag ECU 20 are preferably located below the instrument panel 30. The first antennas 1A and 1B may be mounted on the back of the instrument panel 30, or they may be mounted on or near the instrument panel 30. The first antennas 1A and 1B may be provided near the in-vehicle communication device 10, or they may be configured integrally with the in-vehicle communication device 10. The second antennas 2A and 2B are preferably installed on the upper side of the front window glass 41. The arrangement of the second antennas 2A and 2B will be described later with reference to Figure 5.

[0058] The third antenna 3 is provided on the upper side of the rear window glass 42, preferably within 120 mm from the upper edge of the rear window glass 42. Alternatively, the third antenna 3 may be provided at a position within 20% of the distance between the upper and lower edges of the rear window glass 42, relative to the upper edge of the rear window glass 42.

[0059] The fourth antenna 4 is mounted on the roof of the vehicle, and may be, for example, a whip antenna or a shark fin antenna with a built-in flat element. In addition to the fourth antenna 4, the shark fin housing the fourth antenna 4 may also house antennas for FM and AM radio reception, GPS, ITS, and V2X.

[0060] In Example 3, by arranging the first antenna 1A, the second antenna 2A, the third antenna 3, and the fourth antenna 4 in this manner, the correlation coefficient between the first antenna 1A and the second antenna 2A becomes 0.3 or less in the frequency range of 410 MHz to 7 GHz, and sufficient characteristics are obtained in MIMO.

[0061] Furthermore, some or all of the antennas, including the first antenna 1A, the second antenna 2A, the third antenna 3, and the fourth antenna 4, should have a combined average value of their antenna sensitivity measured with horizontal and vertical polarization while not mounted on a vehicle, in the operating frequency band (the frequency band used by the in-vehicle communication device 10 between 410 MHz and 7 GHz, particularly 700 to 960 MHz).

[0062] Figure 5 shows the arrangement of the second antenna 2A in the front window glass 41 of Embodiment 3.

[0063] The front window glass 41 is a roughly trapezoidal curved glass, and a ceramic layer 41B made of fired colored ceramic is provided around it. The second antenna 2A is provided on the upper side of the front window glass 41, preferably within 120 mm from the upper edge of the front window glass 41. Alternatively, the second antenna 2A may be provided at a position within 20% of the distance between the upper and lower edges of the front window glass 41 from the upper edge of the front window glass 41.

[0064] As described above, according to the aforementioned embodiment, at least one of the in-vehicle communication systems Antenna 1A Place it near the instrument panel 30 (below, back, above, etc.), and at least one Antenna 2ASince the antennas are placed on the front window glass 41, high-speed and high-capacity communication is possible using multiple antennas, and even if the front window glass 41 is damaged in a collision, Antenna 1A Communication can be done using this method.

[0065] Although the present disclosure has been described in detail above with reference to the attached drawings, the present disclosure is not limited to such specific configurations and includes various modifications and equivalent configurations within the spirit of the attached claims. [Explanation of symbols]

[0066] 1A, 1B First Antenna 2A, 2B Second Antenna 3. Third Antenna 4. Fourth Antenna 10. In-vehicle communication device 11 Baseband Processing Unit 12 Radio circuit section 13 Control Unit 20 Airbag ECU 21 Microcontroller 22 Output section 23 Communication Interface 25 Airbags 30 Instrument Panel 41 Front window glass 41B Ceramic layer 42 Rear window glass 100 vehicles

Claims

1. An in-vehicle communication system installed in a vehicle, In-vehicle communication device, It comprises a plurality of antennas, including a first antenna and a second antenna connected to the in-vehicle communication device, The first antenna is provided inside or on the instrument panel of the vehicle. The second antenna is provided on the front window glass of the vehicle. The first antenna and the second antenna constitute a MIMO that transmits and receives radio waves using multiple antennas. In the frequency range of 410 MHz to 7 GHz, the correlation coefficient between the first antenna and the second antenna is 0.3 or less. The aforementioned in-vehicle communication device is It transmits and receives confirmation signals that allow confirmation of the connection with the second antenna. If the confirmation signal cannot be detected for a predetermined time, it is determined whether the front window glass on which the second antenna is installed has been damaged in an accident involving the vehicle. An in-vehicle communication system characterized in that, if the front windshield is damaged in an accident involving the vehicle, it transmits an emergency notification signal to one or all of the antennas.

2. The in-vehicle communication system according to claim 1, The in-vehicle communication system is characterized in that the second antenna is provided on the upper side of the front window glass.

3. The in-vehicle communication system according to claim 2, The in-vehicle communication system is characterized in that the second antenna is provided within 120 mm of the upper edge of the front window glass.

4. The in-vehicle communication system according to claim 2, An in-vehicle communication system characterized in that the second antenna is provided at a position within 20% of the distance between the upper and lower edges of the front window glass, from the upper edge of the front window glass.

5. The in-vehicle communication system according to claim 1, The aforementioned in-vehicle communication device is It is provided inside the aforementioned instrument panel, An in-vehicle communication system characterized by having a wireless circuit that processes radio waves transmitted and received by the first antenna and the second antenna.

6. The in-vehicle communication system according to claim 1, The in-vehicle communication system is characterized in that the second antenna has an average value of the combined antenna sensitivity measured in horizontal polarization and vertical polarization while not mounted on a vehicle in the operating frequency band, which is -5 dBi or higher.

7. The in-vehicle communication system according to claim 1, The in-vehicle communication system is characterized in that the second antenna is an antenna that transmits or receives radio waves in multiple operating frequency bands between 410 MHz and 7 GHz.

8. The in-vehicle communication system according to claim 1, An in-vehicle communication system characterized in that the first antenna is provided in the vicinity of the in-vehicle communication device or is configured integrally with the in-vehicle communication device.

9. The in-vehicle communication system according to claim 1, An in-vehicle communication system characterized in that the first antenna and the second antenna constitute a 2x2 MIMO that transmits or receives radio waves using the two antennas.

10. The in-vehicle communication system according to claim 1, The vehicle further comprises a third antenna and a fourth antenna connected to the aforementioned in-vehicle communication device. An in-vehicle communication system characterized in that the first antenna, the second antenna, the third antenna, and the fourth antenna constitute a 4x4 MIMO that transmits and receives radio waves using four antennas.

11. The in-vehicle communication system according to claim 1, An in-vehicle communication system further comprising a third antenna connected to the in-vehicle communication device and provided on the rear window glass of the vehicle.

12. The in-vehicle communication system according to claim 1, An in-vehicle communication system further comprising a fourth antenna connected to the in-vehicle communication device and provided on the front windshield.

13. The in-vehicle communication system according to claim 1, The aforementioned in-vehicle communication device is The signal output in conjunction with the deployment of the airbag is received from the electronic control unit installed in the vehicle. An in-vehicle communication system characterized by transmitting an emergency notification signal to one or all of the aforementioned antennas.

14. The in-vehicle communication system according to claim 13, The aforementioned in-vehicle communication device is It transmits and receives confirmation signals that allow confirmation of the connection with the second antenna. An in-vehicle communication system characterized in that, if the confirmation signal cannot be detected for a predetermined time and the operation of the electronic control device cannot be confirmed, it is determined that the front windshield has been damaged due to an accident involving the vehicle, and an emergency notification signal is transmitted to one or all of the antennas.

15. The in-vehicle communication system according to claim 13, The aforementioned in-vehicle communication device is It transmits and receives confirmation signals that allow confirmation of the connection with the second antenna. An in-vehicle communication system characterized by inquiring with the occupants whether an accident has occurred in the vehicle if the aforementioned confirmation signal cannot be detected for a predetermined period of time.

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