JP2008099085A - On-vehicle device for wireless communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle device for wireless communication that suppresses increase of a circuit size and avoids interference caused by use of the same frequency band. <P>SOLUTION: The device comprises: first and second antenna sections 2, 3 used in road-to-vehicle communication and vehicle-to-vehicle communication; a switch 4 for switching signals transmitted and received by the antenna sections 2, 3 and for outputting and inputting them for a vehicle-to-vehicle transmitting and receiving section 5 and a road-to-vehicle transmitting and receiving section 6; and a control device 7 connected with the vehicle-to-vehicle transmitting and receiving section 5 or the road-to-vehicle transmitting and receiving section 6, antenna sections 2, 3 are switched by the switch 4 for diversity. In addition, a received signal in a receiver on-vehicle device in vehicle-to-vehicle communication is fed back to a transmitter on-vehicle device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to wireless communication between a roadside machine installed on a road and a vehicle (hereinafter referred to as “road-to-vehicle communication”) or wireless communication between a vehicle and another vehicle (hereinafter referred to as “vehicle-to-vehicle communication”). It is related with the onboard equipment for radio | wireless communication used for.

Conventionally, in order to perform stable mobile communication with a vehicle-mounted device for wireless communication, it is necessary to suppress the influence of fading caused by reflection of radio waves from road surfaces, buildings, and the like. Is known to be effective.
Diversity is a technique that uses a plurality of highly independent communication paths to ensure communication quality using the signal of the other communication path even if the signal of one communication path deteriorates.

As a conventional vehicle-mounted device for wireless communication, a technique using diversity is proposed not only in road-to-vehicle communication between a roadside machine and a vehicle but also in vehicle-to-vehicle communication between the vehicle and the vehicle (for example, a patent) Reference 1 and Patent Reference 2).
In addition, “Narrowband Communication (DSRC) System Standard ARIB-STD T75” is defined by the radio wave industry, and the standard sensitivity of road-to-vehicle communication mobile stations (vehicles) conforming to this standard is “− 60 dBm ".
The standard sensitivity is a recommended reception sensitivity. In road-to-vehicle communication, establishment of communication cannot be compensated with a reception sensitivity equal to or less than the above value “−60 dBm”.

JP 2002-271125 A JP 2005-341293 A

Conventional on-board devices for wireless communication have proposed the effectiveness of diversity in road-to-vehicle communication and vehicle-to-vehicle communication. However, it is necessary to newly provide an antenna for diversity, and the circuit scale becomes large. was there.
In vehicle-to-vehicle communication, for example, the impedance of the antenna changes depending on the state of use, so the transmission power radiated from the antenna may become extremely small due to mismatch between the antenna and the transmission circuit. In spite of good reception sensitivity, there is a problem that communication may not be established because the transmission output is small.

  Also, in road-to-vehicle communication, in order to avoid interference, the use frequency band of each roadside machine is assigned so that no roadside machine in the same frequency band exists within the radio wave transmission range. When each frequency band used for inter-vehicle communication is in the same band, since the vehicle is movable, between the frequency used for road-to-vehicle communication and the frequency used for inter-vehicle communication performed by the host vehicle, Alternatively, there is a problem that interference may occur between a frequency used for road-to-vehicle communication and a frequency used for vehicle-to-vehicle communication performed by another vehicle.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to obtain a wireless communication vehicle-mounted device that suppresses an increase in circuit scale and avoids interference caused by using the same frequency band. .

  A vehicle-mounted device for wireless communication according to the present invention is installed in a vehicle and transmits / receives via the first antenna unit for performing vehicle-to-vehicle communication between the vehicle and another vehicle close to the vehicle. Vehicle-to-vehicle communication transceiver for processing the first signal, a second antenna unit for performing road-to-vehicle communication between the vehicle and a roadside unit adjacent to the vehicle, and a second antenna unit. A transmission / reception unit for road-to-vehicle communication that processes a second signal transmitted / received by the switch, and a switch that individually switches the first and second signals to input / output to / from the vehicle-to-vehicle communication transmission / reception unit or the road-to-vehicle communication transmission / reception unit; The switch performs reception diversity by inputting a reception signal received by the first or second antenna unit to either the vehicle-to-vehicle communication transceiver unit or the road-to-vehicle communication transceiver unit. is there.

According to this invention, each antenna unit used for road-to-vehicle communication and vehicle-to-vehicle communication is switched and shared to perform diversity, so that the on-vehicle device for wireless communication can communicate between road vehicles and between vehicles that constitute diversity. The increase in the circuit scale can be suppressed.
In addition, during road-to-vehicle communication between the roadside unit and the vehicle-mounted device mounted on the vehicle, when the vehicle-to-vehicle communication is started at the same time, the vehicle-to-vehicle transmission / reception unit that does not use the frequency used around the vehicle for communication. By receiving and starting inter-vehicle communication, it is possible to avoid interference caused by using the same frequency band.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a block configuration diagram showing a wireless communication vehicle-mounted device 1 (hereinafter simply referred to as “vehicle-mounted device 1”) according to Embodiment 1 of the present invention.
In FIG. 1, an on-vehicle device 1 installed in a vehicle (described later) includes first and second antenna units 2 and 3, a switch 4, a vehicle-to-vehicle communication transceiver unit 5, and a road-to-vehicle communication transceiver unit. 6 and a control device 7.

The 1st antenna part 2 transmits / receives the 1st signal for performing vehicle-to-vehicle communication between a vehicle and the other vehicle (after-mentioned) close to a vehicle.
The second antenna unit 3 transmits and receives a second signal for performing road-to-vehicle communication between the vehicle and a roadside machine (described later) adjacent to the vehicle.

The vehicle-to-vehicle communication transmission / reception unit 5 processes a first signal transmitted / received via the first antenna unit 2.
The road-vehicle communication transmitter / receiver 6 processes a second signal transmitted / received via the second antenna unit 3.

The switch 4 switches the first and second signals individually and inputs / outputs them to / from the vehicle-to-vehicle communication transceiver 5 or the road-to-vehicle communication transceiver 6.
Therefore, the switch 4 includes a switch terminal 24 connected to the first antenna unit 2, a switch terminal 34 connected to the second antenna unit 3, and a switch terminal connected to the vehicle-to-vehicle communication transceiver unit 5. 45 and a switch terminal 46 connected to the transmission / reception unit 6 for road-to-vehicle communication.

That is, the switch 4 switches the switch terminals 24 and 34 and connects the switch terminals 24 and 34 to the switch terminals 45 and 46, respectively, so that the first and second signals transmitted and received by the first and second antenna units 2 and 3 are transmitted. The vehicle-to-vehicle communication transmitter / receiver 5 or the road-to-vehicle communication transmitter / receiver 6 inputs or outputs.
Thereby, the switch 4 inputs the reception signal received by the first or second antenna unit 2 or 3 to either one of the vehicle-to-vehicle communication transmission / reception unit 5 or the road-to-vehicle communication transmission / reception unit 6. Diversity of the antenna units 2 and 3 is performed.

The control device 7 is connected to the transmission / reception unit 5 for vehicle-to-vehicle communication and the transmission / reception unit 6 for road-to-vehicle communication, and the transmission / reception unit 5 for vehicle-to-vehicle communication and transmission / reception for road-to-vehicle communication are transmitted from the antennas 2 and 3 via the switch 4. It has a function of switching the switch 4 so that the reception signal input to the unit 6 is captured, the reception level at a predetermined frequency is detected and compared, and the antenna unit that can obtain the reception signal of the maximum reception level is selected. .
In addition, the control device 7 sends information obtained from the received signal to the vehicle-to-vehicle communication transmitter / receiver 5 or the road-to-vehicle communication transmitter / receiver 6.

Note that the selection and switching functions of the switch 4 by the control device 7 may be included in the functions in the switch 4 or may be included in the functions in the transmission / reception units 5 and 6.
Moreover, as a use frequency of radio | wireless communication, although the 5.8 GHz band has been mainly used conventionally, it is not necessarily limited to these frequencies.
The antenna units 2 and 3, the vehicle-to-vehicle communication transmitter / receiver 5 and the road-to-vehicle communication transmitter / receiver 6 are designed according to the communication frequency to be used.
Furthermore, the number of antennas provided in each of the antenna units 2 and 3 is at least one, and the antenna shape is arbitrary.

Hereinafter, the diversity operation in the vehicle-to-vehicle communication and the road-to-vehicle communication according to Embodiment 1 of the present invention shown in FIG. 1 will be described in detail with reference to FIG.
FIG. 2 is an explanatory diagram showing the state of inter-vehicle communication and road-to-vehicle communication.
In FIG. 2, two vehicles 8a and 8b and vehicles 8c and 8d each travel in the direction of an arrow on a two-lane highway.

On-vehicle devices 1a to 1d having the same configuration as in FIG. 1 are mounted on the vehicles 8a to 8d.
As described above, the number of antennas, the antenna shape, and the installation position of the antenna units 2a to 2d and 3a to 3d of the vehicle-mounted devices 1a to 1d are arbitrary.
A roadside machine 9 is installed on the highway, and the roadside machine 9 performs road-to-vehicle communication with a vehicle that has entered the communication area 10 of the roadside machine 9.

Here, vehicle-to-vehicle communication when the vehicle 8a is the transmission side and the vehicle 8b following the vehicle 8a is the reception side will be described.
First, the vehicle-mounted device 1a of the vehicle 8a transmits a transmission signal from the first or second antenna unit 2a, 3a to the vehicle-mounted device 1b via the switch 4a from the vehicle-to-vehicle communication transmitting / receiving unit 5a.
At this time, in the vehicle-mounted device 1b of the vehicle 8b, the switch 4b first receives the transmission signal from the vehicle-mounted device 1a with the first antenna unit 2b in a state where the switch terminal 24b and the switch terminal 45b are connected, and receives the received signal. Is input to the vehicle-to-vehicle communication transceiver 5b via the switch terminals 24b and 45b of the switch 4b.

  Subsequently, the vehicle-mounted device 1b of the vehicle 8b switches the switch 4b, connects the switch terminal 34b and the switch terminal 45b, receives the transmission signal from the vehicle-mounted device 1a by the second antenna unit 3b, and receives the received signal. The signal is input to the vehicle-to-vehicle communication transceiver 5b via the switch terminals 34b and 45b of the switch 4b.

The vehicle-to-vehicle communication transceiver 5b detects the reception level of the received signal received via the antenna units 2b and 3b, selects the higher signal among the detected reception levels, and controls the selected received signal. Send to device 7b.
In addition, although the case where the received signal selection function is incorporated in the vehicle-to-vehicle communication transceiver 5b is described here, it may be incorporated in the road-to-vehicle communication transceiver 6b or the control device 7b.

In this way, by performing diversity of the antenna units 2b and 3b, the control device 7b can select a state with a high reception level, and stable communication is possible.
The diversity of the antenna units 2 and 3 is performed not only in the vehicle-mounted device 1b of the vehicle 8b but also in the vehicle-mounted devices 1a to 1d of the vehicles 8a to 8d.

  That is, when attention is paid to communication between the vehicle 8a (own vehicle) and the vehicle 8b (other vehicle), first, the first or second antenna portion 2a, 3a (usually inter-vehicle communication) of the vehicle-mounted device 1a of the vehicle 8a. The transmission signal transmitted from the first antenna unit 2a for the vehicle is the first or second antenna unit 2b, 3b of the vehicle-mounted device 1b of the vehicle 8b (usually the first antenna unit 2b for inter-vehicle communication). ).

Subsequently, the vehicle-mounted device 1b of the vehicle 8b transmits (sends back) information on the received signal received from the vehicle-mounted device 1a of the vehicle 8a to the vehicle-mounted device 1a of the vehicle 8a.
Thereby, the vehicle-mounted device 1a of the vehicle 8a performs diversity of the antenna units 2a and 3a on the received signal after feedback of the transmission signal transmitted by itself.
That is, the vehicle-mounted device 1a of the vehicle 8a determines which antenna the signal transmitted from which the signal transmitted from a plurality of antennas is received well, and selects a reception antenna.

In transmission / reception between vehicles at this time, the vehicle-mounted device 1a of the vehicle 8a switches between the first and second antenna units 2a and 3a (a plurality of antennas) and transmits them, and the vehicle-mounted device 1b of the vehicle 8b You may receive only with the 1st antenna part 2b for communication.
At this time, the vehicle-mounted device 1b of the vehicle 8b basically receives the reception level at the vehicle-mounted device 1b as transmission antenna selection information fed back to the vehicle-mounted device 1a so that the reception environment is improved (for example, the reception level is maximized). Send information.

  Further, the vehicle-mounted device 1b of the vehicle 8b switches the reception of the first and second antenna units 2b and 3b (a plurality of antennas) to thereby receive 2 × 2 (= 4) the number of diversity branches (route options). ) To select the best antenna combination among the four. However, since the vehicle-to-vehicle communication is a mobile communication, a positional shift occurs in the time required for the communication, so it is better to have as few options as possible.

Next, road-to-vehicle communication when the roadside device 9 is the transmission side and the vehicle 8a is the reception side will be described.
First, the roadside device 9 transmits a transmission signal to the vehicle-mounted device 1 a of the vehicle 8 a in the communication area 10.
At this time, in the vehicle-mounted device 1a of the vehicle 8a, the switch 4a first receives the transmission signal from the roadside device 9 with the second antenna unit 3a in a state where the switch terminal 34a and the switch terminal 46a are connected, and receives the received signal. Is input to the road-vehicle communication transceiver 6a via the switch terminals 34a and 46a of the switch 4a.

  Subsequently, the vehicle-mounted device 1a of the vehicle 8a switches the switch 4a, connects the switch terminal 24a and the switch terminal 46a, receives the transmission signal from the roadside unit 9 by the first antenna unit 2a, and receives the received signal. The signal is input to the road-to-vehicle communication transceiver 6a via the switch terminals 24a and 46a of the switch 4a.

The transmission / reception unit 6a for road-to-vehicle communication detects the reception level of the reception signal received via each antenna unit 2a, 3a, selects the higher signal among the detected reception levels, and controls the selected reception signal Send to device 7a.
Also in this case, the reception signal selection function is not limited to the road-vehicle communication transceiver 6a, and may be incorporated in the control device 7a.

In this way, by performing diversity of the antenna units 2a and 3a, the control device 7a can select a state with a high reception level, and stable communication is possible.
Note that, when the reception level does not decrease, it is not always necessary to perform diversity. For example, only the first antenna unit 2a, 2b for inter-vehicle communication is installed in the vehicle-mounted devices 1a, 1b of the vehicles 8a, 8b. Diversity may be used only when the used transmission / reception is performed and a feedback signal from the vehicle-mounted device 1b cannot be obtained for the vehicle-mounted device 1a.

Moreover, any of spatial diversity, polarization diversity, and angle diversity may be used as the configuration of transmission diversity or reception diversity.
However, in the case of space diversity, it is necessary to arrange the antenna units 2 and 3 at positions sufficiently separated in space.
In the case of polarization diversity, it is necessary to use vertical and horizontal polarization for diversity if it is linear polarization, and diversity for left and right circular polarization if it is circular polarization. There is.

As described above, according to the vehicle-mounted device 1 sharing the vehicle-to-vehicle communication and the road-to-vehicle communication according to Embodiment 1 of the present invention, the diversity of the antenna units 2 and 3 is performed, so A communication state with a high reception level can be selected in both communication and vehicle-to-vehicle communication, and stable communication is possible.
Further, in the vehicle-mounted device 1, communication is possible between the road vehicles and between the vehicles constituting the diversity by using the diversity by switching and sharing the antenna units 2 and 3 used for road-to-vehicle communication and vehicle-to-vehicle communication. An increase in the circuit scale of the vehicle-mounted device 1 can be suppressed.

Embodiment 2. FIG.
Although not mentioned in the first embodiment, the vehicle-to-vehicle communication transmission / reception unit 5 uses only the road-to-vehicle communication using the road-to-vehicle communication transmission / reception unit 6 by using the reception level detection function of the vehicle-mounted device 1. If it is performed, the reception level is detected by receiving surrounding radio waves, the frequency assigned to the vehicle-to-vehicle communication of the vehicle (the first frequency assigned to the road-to-vehicle communication of the own vehicle, and the other vehicle (Including the second frequency used for vehicle-to-vehicle communication), the frequency band with the lowest reception level may be used for vehicle-to-vehicle communication of the host vehicle.

In this case, during the road-to-vehicle communication between the roadside device 9 and the vehicle-mounted device 1, when the vehicle-to-vehicle communication is started at the same time, the vehicle-to-vehicle communication transmission / reception unit 5 that is not used for the communication in the vehicle-mounted device 1 A frequency used in the vicinity of 1 is received to detect a reception level, and vehicle-to-vehicle communication is started using a frequency at which the reception level is minimized.
Thereby, in vehicle-to-vehicle communication, the transmission-side vehicle-mounted device 1 is adjusted so that the reception-side vehicle-mounted device can receive optimally, and the same frequency band as the frequency used in other communication is used. Interference due to can be avoided.

Hereinafter, a second embodiment of the present invention in which a frequency for vehicle-to-vehicle communication is set so as to avoid interference will be described with reference to FIGS. 1 and 2.
Here, in FIG. 2, road-to-vehicle communication is performed between the roadside machine 9 and the vehicle 8a traveling in one lane, and between the vehicle 8c and the vehicle 8d traveling in the other lane. The case where the vehicle 8a starts the vehicle-to-vehicle communication with the subsequent vehicle 8b in the state where the vehicle-to-vehicle communication is performed will be described as an example.

First, the vehicle-mounted device 1a of the vehicle 8a receives the transmission signal from the roadside unit 9 by the second antenna unit 3a for road-to-vehicle communication, and the received signal via the switch terminals 34a and 46a of the switch 4a, It inputs into the transmission / reception part 6a for road-to-vehicle communication.
At the same time, the vehicle-mounted device 1a receives radio waves around the vehicle 8a by the first antenna unit 2a, and transmits and receives the received signals via the switch terminals 24a and 45a of the switch 4a. Input to part 5a.

The vehicle-to-vehicle communication transmitter / receiver 5a detects the frequency at which the reception level is minimum, including the frequency used for road-to-vehicle communication with the roadside device 9.
In this situation, the vehicle-mounted device 1a of the vehicle 8a receives an inter-vehicle communication signal between the vehicle 8c and the vehicle 8d as a surrounding radio wave.

The vehicle-to-vehicle communication transmission / reception unit 5a performs vehicle-to-vehicle communication of the host vehicle using the frequency at which the reception level detected as described above is minimized.
Accordingly, the same frequency band as the inter-vehicle communication of the vehicles 8c and 8d around the vehicle 8a is not used as the frequency for the inter-vehicle communication of the vehicles 8a and 8b. Interference at the start of communication can be avoided.

Here, the detection function of the reception level and the frequency is incorporated in the vehicle-to-vehicle communication transmission / reception unit 5, but may be incorporated in the control device 7 to perform the same operation.
In addition, the switch 4 connects the switch terminal 34 and the switch terminal 46 and connects the switch terminal 24 and the switch terminal 45, but connects the switch terminal 34 and the switch terminal 45, and connects the switch terminal 24 and the switch terminal 46. And may be connected.

  As described above, according to the second embodiment of the present invention, the frequency allocated to the inter-vehicle communication performed by the vehicle on which the vehicle-mounted device 1 is mounted and the vehicle on which the vehicle-mounted device 1 is mounted between the roadside device 9. A vehicle in which the vehicle-mounted device 1 is mounted with a frequency having a minimum reception level, among a first frequency assigned to road-to-vehicle communication performed and a second frequency used for vehicle-to-vehicle communication performed by another vehicle. Therefore, it is possible to avoid interference caused by using the same frequency as that used in the vicinity.

Embodiment 3 FIG.
In the first embodiment, the reception diversity is described exclusively and the transmission diversity is not described in detail. However, the switch 4 in the vehicle-mounted device 1 is not limited to the reception diversity of the antenna units 2 and 3, but the transmission diversity. Also has to do.
Hereinafter, transmission diversity performed according to the third embodiment of the present invention will be described with reference to FIGS. 1 and 2.

In this case, in FIG. 2, the switches 4 a to 4 d in the vehicle-mounted devices 1 a to 1 d of the vehicles 8 a to 8 d are respectively connected to the antenna units 2 a to 2 d in a state in which vehicle-to-vehicle communication is performed with other vehicles. 3a-3d receive diversity and transmit diversity are performed.
That is, the switches 4a to 4d switch the antenna units 2a to 2d and 3a to 3d to transmit transmission signals, and receive reception level information of transmission signals transmitted from other vehicles that have received the transmission signals. Transmission diversity is performed based on the received signal information received as feedback signals from the units 2a to 2d and 3a to 3d.

Here, as described above, a case will be described in which inter-vehicle communication is performed with the vehicle 8a as a transmission side and the vehicle 8b following the vehicle 8a as a reception side.
First, the vehicle-to-vehicle communication transceiver 5a of the vehicle-mounted device 1a transmits a transmission signal from the first antenna unit 2a to the vehicle-mounted device 1b via the switch terminals 45a and 24a of the switch 4a, and then switches the switch 4a. Then, the transmission signal is transmitted from the second antenna unit 3a to the vehicle-mounted device 1b via the switch terminals 45a and 34a.

  At this time, in the vehicle-mounted device 1b of the vehicle 8b, the switch 4b first receives the transmission signal from the vehicle-mounted device 1a with the first antenna unit 2b in a state where the switch terminal 24b and the switch terminal 45b are connected, and receives the received signal. Is input to the vehicle-to-vehicle communication transceiver 5b via the switch terminals 24b and 45b of the switch 4b.

  In the switch 4a in the vehicle-mounted device 1a, when the switch terminals 34a and 45a are connected, or when the switch terminals 24a and 46a are connected, and in the switch 4b in the vehicle-mounted device 1b, the switch terminal 24b, The same operation is performed when 46b is connected or when the switch terminals 34b and 45b are connected.

Further, in the switch 4b in the vehicle-mounted device 1b, the reception signal from the roadside device 9 may be input to the road-to-vehicle communication transmitting / receiving unit 6 with the switch terminals 34b and 46b being connected.
Further, in the switch 4b in the vehicle-mounted device 1b, the transmission signal from the vehicle-mounted device 1a received by the second antenna unit 3b is input to the vehicle-to-vehicle communication transmitting / receiving unit 5b via the switch terminals 34b and 45b, and the received signal Diversity branch may be obtained by increasing the number of options.

The vehicle-to-vehicle communication transceiver 5b in the vehicle-mounted device 1b detects the reception level of each received signal transmitted from each antenna unit 2a, 3a of the vehicle-mounted device 1a, and receives the received signal with the higher reception level. The transmission signal including the selected reception level information is transmitted to the vehicle-mounted device 1a via the switch terminals 45b and 24b of the switch 4b and the first antenna unit 2b.
In the vehicle-mounted device 1b, the reception level detection function and selection function are incorporated in the vehicle-to-vehicle communication transceiver 5b, but may be incorporated in the control device 7b.

  The vehicle-mounted device 1a receives the transmission signal selected and fed back by the vehicle-mounted device 1b, and the switch terminal 24a, 45a from the first antenna unit 2a or the switch terminal 34a from the second antenna unit 3a, It inputs into the transmission / reception part 5a for vehicle-to-vehicle communication via 45a.

Hereinafter, the transmission / reception unit 5a for inter-vehicle communication, based on the received signal including the selected reception level information (feedback signal of the transmission signal), the transmission signal with the higher reception level is received by the vehicle-mounted device 1b. The switch 4 is switched and transmitted.
In the in-vehicle device 1a, the switching control function of the switch 4 is incorporated in the vehicle-to-vehicle communication transceiver 5a, but may be incorporated in the control device 7a.

In the vehicle-mounted device 1b, when the reception level does not decrease at the first or second antenna unit 2b, 3b, it is not always necessary to perform diversity.
Moreover, as a configuration of diversity, any of space diversity, polarization diversity, and angle diversity may be used.
However, in the case of space diversity, it is necessary to arrange the antenna units 2a and 3a of the vehicle-mounted device 1a at positions that are sufficiently separated spatially.
In the case of polarization diversity, it is necessary to use vertical and horizontal polarization for diversity if it is linear polarization, and diversity for left and right circular polarization if it is circular polarization. There is.

Thus, according to the vehicle-mounted device 1 sharing the vehicle-to-vehicle communication and the road-to-vehicle communication according to Embodiment 3 of the present invention, the reception level of the received signal is received by the vehicle-to-vehicle communication transceiver on the receiving side in the vehicle-to-vehicle communication. Since it is configured to monitor information and send it back to the on-vehicle device on the transmission side, transmission diversity can also be performed by the transmission / reception unit 5 for inter-vehicle communication on the transmission side.
In addition, as described above, it is possible to suppress an increase in circuit scale by the antenna units 2 and 3 constituting the diversity and to realize stable communication.

Embodiment 4 FIG.
Although not mentioned in the first to third embodiments, information included in the received signal fed back from the other vehicle via the first or second antenna unit 2 or 3 (reception of the transmission signal in the other vehicle). On the basis of the level information), the vehicle-to-vehicle communication transceiver 5 or the road-to-vehicle communication transmitter / receiver 6 determines that the reception level is the standard when the reception level information indicates outside the standard sensitivity range defined for the vehicle-to-vehicle communication. The transmission power (transmission level) may be adjusted so as to be within the sensitivity range.

Hereinafter, referring to FIGS. 1 and 2, Embodiment 4 of the present invention configured to adjust the transmission power from the vehicle 8a so that the reception level at the vehicle 8b is within the range of the standard sensitivity will be described. To do.
In this case, first, the vehicle-mounted device 1a of the vehicle 8a transmits a signal from the first or second antenna unit 2a, 3a to the vehicle-mounted device 1b.

In the vehicle-mounted device 1b, the transmission signal transmitted from the vehicle-mounted device 1a is input from the first antenna unit 2b to the vehicle-to-vehicle communication transmission / reception unit 5b via the switch terminals 24b and 45b of the switch 4b, and the received signal The reception level of is detected.
At this time, if the reception level is outside the range of the standard sensitivity specified in the inter-vehicle communication, a detection signal (reception level information) indicating that the standard sensitivity is out of the range is sent to the switch terminals 45b and 24b of the switch 4b and It transmits to the onboard equipment 1a via the 1st antenna part 2b.
The reception level detection function is incorporated in the vehicle-to-vehicle communication transceiver 5b here, but may be incorporated in the control device 7b.

The on-vehicle device 1a receives the transmission signal selected by the on-vehicle device 1b, and the first antenna unit 2a through the switch terminals 24a and 45a or the second antenna unit 3a through the switch terminals 34a and 45a. And input to the vehicle-to-vehicle communication transceiver 5a.
Hereinafter, the vehicle-to-vehicle communication transceiver 5a adjusts the transmission level based on the fed-back received signal so that the received signal at the vehicle-mounted device 1b falls within the standard sensitivity range defined for the vehicle-to-vehicle communication. To send.

The transmission power adjustment function is incorporated in the vehicle-to-vehicle communication transceiver 5a here, but may be incorporated in the control device 7a.
In this case, for example, when the reception level at the on-vehicle device on the receiving side is lower than a predetermined standard sensitivity defined in the inter-vehicle communication, the control device 7 in the on-vehicle device 1a on the transmitting side The vehicle-to-vehicle communication transceiver 5 is adjusted so that the transmission level increases.

  Thus, according to the vehicle-mounted device 1 sharing the vehicle-to-vehicle communication and the road-to-vehicle communication according to Embodiment 4 of the present invention, the reception level of the received signal is set at the reception-side vehicle-to-vehicle communication transmitting / receiving unit in the vehicle-to-vehicle communication. If the reception level is outside the range of the standard sensitivity defined in the vehicle-to-vehicle communication, the reception level information is transmitted to the on-vehicle device on the transmission side and transmitted by the vehicle-to-vehicle communication transmission / reception unit 5 on the transmission side. Since the configuration is such that the level is adjusted, the reception level can be within the range of the standard sensitivity defined in the inter-vehicle communication, and stable communication can be realized.

Embodiment 5 FIG.
In the fourth embodiment, the transmission power (transmission level) is adjusted so that the reception level is within the standard sensitivity range. However, the transmission frequency is adjusted so that the reception level is within the standard sensitivity range. Good.
Hereinafter, a fifth embodiment of the present invention in which the transmission frequency is adjusted to make the reception level within the range of the standard sensitivity will be described with reference to FIGS.

Also in this case, a case will be described in which the transmission frequency from the vehicle 8a is adjusted so that the reception level at the vehicle 8b is within the standard sensitivity range with the vehicle 8a as the transmission side and the vehicle 8b as the reception side.
First, the vehicle-mounted device 1a transmits a signal from the first or second antenna unit 2a, 3a to the vehicle-mounted device 1b.

The vehicle-mounted device 1b receives the transmission signal transmitted from the vehicle-mounted device 1b by the vehicle-to-vehicle communication transmission / reception unit 5b, detects the reception level of the received signal, and the range of standard sensitivity in which the reception level is defined for vehicle-to-vehicle communication. If it is determined that it is outside, the reception level information is transmitted to the vehicle-mounted device 1a via the switch terminals 45b and 24b of the switch 4b and the antenna unit 2b.
The reception level detection function is incorporated in the vehicle-to-vehicle communication transceiver 5b here, but may be incorporated in the control device 7b.

The vehicle-mounted device 1a transmits the detection signal (reception level information) selected by the vehicle-mounted device 1b via the antenna unit 2a and the switch terminals 24a and 45a or between the vehicle and the vehicle via the antenna unit 3a and the switch terminals 34a and 45a. Input to the communication transceiver 5a.
Based on the reception level information, the vehicle-to-vehicle communication transmitter / receiver 5a changes the transmission frequency so that the signal received by the vehicle-mounted device 1b is within the standard sensitivity range defined for vehicle-to-vehicle communication.
Here, the function of adjusting the transmission frequency is incorporated in the vehicle-to-vehicle communication transceiver 5a here, but may be incorporated in the control device 7a.

  As described above, according to the vehicle-mounted device 1 sharing the vehicle-to-vehicle communication and the road-to-vehicle communication according to Embodiment 5 of the present invention, the reception level of the received signal is received by the vehicle-to-vehicle communication transmitting / receiving unit on the receiving side in the vehicle-to-vehicle communication. If the reception level is out of the standard sensitivity range specified for vehicle-to-vehicle communication, the reception level information is transmitted to the on-board device on the transmission side and transmitted by the vehicle-to-vehicle communication transmission / reception unit on the transmission side. Since it is configured to change the frequency, the reception level can be within the range of the standard sensitivity defined in the inter-vehicle communication, and stable communication can be realized.

  In the first to fifth embodiments, the switching state of the representative switch 4 has been described as an example for easy understanding. However, the combination of the connection states of the switch terminals 24 and 34 and the switch terminals 45 and 46 is described as follows. Needless to say, it can be arbitrarily set, and the use states of the antenna units 2 and 3 and the transmitting and receiving units 5 and 6 can be arbitrarily set when performing diversity.

It is a block block diagram which shows the onboard equipment for radio | wireless communication which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the state of the vehicle-to-vehicle communication and road-to-vehicle communication by Embodiment 1 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 1a-1d On-board unit for radio | wireless communication, 2 1st antenna part, 3 2nd antenna part, 4 switch, 24, 34, 45, 46 switch terminal, transmission / reception part for inter-vehicle communication, 6-road inter-vehicle communication Transceiver unit, 7 control device, 8a-8d vehicle, 9 roadside machine.

Claims (5)

A first antenna unit installed in a vehicle for performing inter-vehicle communication between the vehicle and another vehicle close to the vehicle;
A vehicle-to-vehicle communication transceiver for processing a first signal transmitted / received via the first antenna unit;
A second antenna unit for performing road-to-vehicle communication between the vehicle and a roadside machine adjacent to the vehicle;
A road-to-vehicle communication transceiver for processing a second signal transmitted / received via the second antenna section;
A switch that individually switches the first and second signals and inputs and outputs to the vehicle-to-vehicle communication transceiver unit or the road-to-vehicle communication transceiver unit;
The switch performs reception diversity by inputting a reception signal received by the first or second antenna unit to either the vehicle-to-vehicle communication transceiver unit or the road-vehicle communication transceiver unit. A vehicle-mounted device for wireless communication, characterized by The vehicle-to-vehicle communication transceiver is
When only road-to-vehicle communication using the transmission / reception unit for road-to-vehicle communication is performed, the reception level is detected by receiving surrounding radio waves,
Of the frequencies assigned to the vehicle-to-vehicle communication of the vehicle, including the first frequency assigned to the road-to-vehicle communication of the vehicle and the second frequency used for the vehicle-to-vehicle communication performed by the other vehicle The vehicle-mounted device for wireless communication according to claim 1, wherein a frequency band in which the reception level is minimum is used for inter-vehicle communication of the vehicle. In a state in which vehicle-to-vehicle communication is performed between the vehicle and the other vehicle,
The switch is
While switching the first and second antenna units to transmit a transmission signal,
Information on the transmission signal transmitted from the other vehicle that has received the transmission signal is received as a reception signal from the first or second antenna unit,
The vehicle-mounted device for wireless communication according to claim 1 or 2, wherein transmission diversity is performed based on information of the received signal. The reception signal received from the other vehicle via the first or second antenna unit includes reception level information of the transmission signal in the other vehicle,
The vehicle-to-vehicle communication transceiver unit or the road-to-vehicle communication transceiver unit has the reception level of the standard sensitivity when the reception level information indicates outside the standard sensitivity range defined in the vehicle-to-vehicle communication. The in-vehicle device for wireless communication according to any one of claims 1 to 3, wherein the transmission power or the transmission frequency is adjusted so as to be within a range.   The on-vehicle device for wireless communication according to any one of claims 1 to 4, wherein the reception diversity or the transmission diversity corresponds to space diversity, polarization diversity, and angle diversity.

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