JP2014039145A - Radio device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To aim to avoid interference by previously detecting a communication area of another radio system.SOLUTION: A radio device in a vehicle comprises: vehicle-vehicle communication means; another system area detection means; vehicle information extraction means for extracting vehicle information included in a reception signal from a radio device in another vehicle; vehicle information holding means for holding the vehicle information on the other vehicle extracted by the vehicle information extraction means and vehicle information on the vehicle; preceding vehicle detection means for detecting a preceding vehicle which is located in the front of the vehicle and is moving in the same direction as the vehicle on the basis of the vehicle information on the vehicle and the vehicle information on the other vehicle in the vehicle information holding means; preceding vehicle running state monitoring means for monitoring change of a running state of the preceding vehicle; and communication control means for performing interference avoidance processing on the vehicle-vehicle communication means after determining that a communication area of another radio system exists when the running state of the preceding vehicle has changed.

Description

  The present invention relates to a wireless device. For example, in a wireless device that performs inter-vehicle communication, a service area of another wireless system existing in the vicinity is detected in advance to avoid radio wave interference with the other wireless system. It can be applied to a wireless device.

  For example, an inter-vehicle communication system (hereinafter also referred to as “system A”) performs wireless communication directly with an in-vehicle wireless device of a surrounding vehicle without using an infrastructure device such as a base station, and shares driving information with each other, which is dangerous for the host vehicle. If there is a possibility that the problem will occur, the driver will be alerted to realize safe driving support.

  The inter-vehicle communication system (System A) employs a CSMA (Carrier Sense Multiple Access) system in which a transmission is performed after confirming the channel usage state even when a plurality of in-vehicle wireless devices use the same transmission / reception channel. This is a system capable of avoiding communication packet collision in the service area.

  By the way, as shown in FIG. 2, there is a road-to-vehicle communication system (hereinafter also referred to as system B) that constitutes a communication service area at a specific place. The road-to-vehicle communication system (system B) is applied to, for example, an automatic toll collection system, a narrow-area communication system, and the like. In these communication systems, one roadside device 3 communicates with a plurality of in-vehicle wireless devices. I do. Therefore, the road-to-vehicle communication system (System B) employs a TDMA (Time Division Multiple Access) system in which the roadside device controls the transmission timing of the mobile station.

  As shown in FIG. 2, when two different inter-vehicle communication systems (system A) and road-to-vehicle communication system (system B) use the same frequency band and are in an environment where channel frequencies are arranged nearby, When the vehicle 1-1 equipped with the in-vehicle wireless device of the system A enters the service area of the system B, radio wave interference occurs between the system A and the system B. Therefore, a means for avoiding interference between the system A and the system B is required.

  Conventionally, there are the following techniques for detecting other wireless communication service signals and controlling transmission of the own station so as not to interfere with other wireless communication services.

  In the technique described in Patent Document 1, the mobile station checks the state of a received signal from the base station during another wireless communication service period, and when there is a possibility of interference, the channel frequency is switched, transmission power reduction control and transmission are performed. Stop. Then, when the wireless communication service of another mobile station is completed, the mobile station itself implements the wireless communication service with the base station.

  The technology described in Patent Document 2 uses automatic radio toll collection communication means and narrow area communication means for communicating with roadside radio devices using microwave band radio waves, and uses microwave radio waves between vehicles. Vehicle-to-vehicle communication means for performing communication, and when the reception of a signal from the road layer wireless device of the toll gate is detected, automatic communication is performed when communication by the narrow-area communication means or the vehicle-to-vehicle communication means is performed. The communication is switched to communication by toll collection service.

Japanese Patent Publication No. 2003-259414 Japanese Patent Publication No. 2004-246687

  However, even if the above-described conventional technology is used, the signal level of the road-to-vehicle communication system (system B) reaching the service area of the vehicle-to-vehicle communication system (system A) is low, so that the service area of system B cannot be detected. is there.

  For example, in the case where the transmission power value of the in-vehicle wireless device of system A is larger than that of system B and the channel frequency interval between system A and system B is narrow, the in-vehicle wireless device of system A is roadside unit 3 of system B. It is necessary to detect the service area of the system B at a point where a necessary separation distance is sufficiently secured so as not to interfere with the vehicle-mounted wireless device. However, at a point where a large separation distance from the system B is secured, the arrival signal level of the system B that can be received by the in-vehicle wireless device of the system A is low, so the in-vehicle wireless device of the system A detects the signal of the system B. It becomes difficult.

  Therefore, the present invention is to solve the above-described problems and to provide a wireless device that tries to detect a communication area of another wireless system in advance.

  In order to solve this problem, the first aspect of the present invention includes (1) vehicle-to-vehicle communication means for performing vehicle-to-vehicle communication with a wireless device of another vehicle, and (2) detecting a communication area of another wireless system. System area detection means, (3) vehicle information extraction means for extracting vehicle information contained in the received signal received from the radio device of the other vehicle, and (4) vehicle information of the other vehicle extracted by the vehicle information extraction means, Vehicle information holding means for holding vehicle information of the own vehicle; and (5) based on the vehicle information of the own vehicle and the vehicle information of other vehicles of the vehicle information holding means and in front of the own vehicle and Preceding vehicle detection means for detecting a preceding vehicle traveling in the same direction as the vehicle, (6) preceding vehicle traveling state monitoring means for monitoring the transmission of the preceding vehicle and changes in traveling state, and (7) transmission and traveling state of the preceding vehicle. When the other changes It is determined that the communication area of the radio system exists, a radio apparatus, characterized in that it comprises a communication control means for performing interference avoidance processing for inter-vehicle communication means.

  According to the present invention, communication areas of other wireless systems existing in the vicinity can be detected in advance, and radio interference with other wireless systems can be avoided by performing interference avoidance processing of the wireless communication device of the host vehicle. it can.

It is an internal block diagram which shows the internal structure of the radio | wireless apparatus which concerns on embodiment. It is explanatory drawing explaining the system configuration | structure in which the communication system between vehicles and another radio system coexist. It is a flowchart which shows the area interference avoidance process of the other radio | wireless system by the radio | wireless apparatus of embodiment. It is a flowchart which shows the 1st transmission resumption process by the radio | wireless apparatus of embodiment. It is a flowchart which shows the 2nd transmission resumption process by the radio | wireless apparatus of embodiment.

(A) Embodiment Hereinafter, an embodiment of a wireless device of the present invention will be described in detail with reference to the drawings.

  This embodiment exemplifies a case where the present invention is applied to, for example, an in-vehicle wireless device corresponding to an inter-vehicle communication system.

(A-1) Configuration of Embodiment Also in this embodiment, description will be given assuming an environment in which a vehicle-to-vehicle communication system (system A) and a road-to-vehicle communication system (system B) can coexist.

  That is, in FIG. 2, the road on which the roadside machine 3 of the system B is arranged is divided into a vehicle 2 equipped with the in-vehicle wireless device of the system B, and vehicles 1-1 and 1-2 equipped with the in-vehicle wireless device of the system A. Assume a case of progress.

  In this embodiment, a road-to-vehicle communication system (system B) is illustrated as an example of another wireless system that causes radio wave interference with the vehicle-to-vehicle communication system (system A), but is the same as the vehicle-to-vehicle communication system (system A). Any wireless system using a frequency band and having channel frequencies arranged in the vicinity of each other is not limited to a road-to-vehicle communication system and can be widely applied.

  FIG. 1 is an internal configuration diagram illustrating an internal configuration of a wireless device according to an embodiment. In FIG. 1, a wireless device 100 according to this embodiment includes an antenna unit 1, a transmission / reception switching unit 2, a transmission unit 3, a local oscillation unit 4, a reception unit 5, an RSSI (received electric field strength) signal detection unit 6, and a data extraction unit 7. , A database unit 8, another system area detection determination unit 9, another system area detection threshold setting unit 10, and an inter-vehicle communication control unit 11.

  The wireless device 100 includes a communication circuit device, a control circuit device, and the like, and can perform various functions when the CPU executes a processing program. Even in this case, the functions realized by the wireless device 100 can be expressed as a block diagram shown in FIG.

  The antenna unit 1 captures an incoming radio wave, converts the captured radio wave signal into an electrical signal, and supplies the signal to the reception unit 5 via the transmission / reception switching unit 2 or from the transmission unit 3 via the transmission / reception switching unit 2. A transmission signal is emitted on a radio wave.

  Here, in FIG. 1, the antenna unit 1 exemplifies a case where the vehicle-to-vehicle communication system and another wireless system are shared. However, the antenna unit 1 includes separate antenna units for the vehicle-to-vehicle communication system and the other wireless system. You may do it. Further, FIG. 1 illustrates a case where transmission and reception are shared, but separate antenna units may be provided for transmission and reception.

  The transmission / reception switching unit 2 switches connection with the transmission unit 3 when transmitting a transmission signal, and switches connection with the reception unit 5 when receiving a reception signal. When the antenna unit 1 is separate for transmission and reception, the transmission / reception switching unit 2 may not be provided.

  The transmission unit 3 gives the transmission signal of the inter-vehicle communication system to the antenna unit 1 via the transmission / reception switching unit 2 under the control of the inter-vehicle communication control unit 11. That is, the transmission unit 3 receives a digital transmission packet signal from the inter-vehicle communication control unit 11, converts the transmission packet signal into an analog transmission signal, modulates the converted transmission signal, performs power amplification, and performs power amplification. The transmitted signal is given to the antenna unit 1.

  The transmission unit 3 performs transmission processing according to transmission control from the vehicle-to-vehicle communication control unit 11 or performs transmission processing by reducing transmission power value. When there is an instruction to reduce the transmission power value from the vehicle-to-vehicle communication control unit 11, the transmission unit 3 transmits at a lower transmission power value than when performing normal vehicle-to-vehicle communication.

  At this time, for example, a plurality of different transmission power values may be set in advance, and the transmission unit 3 may perform transmission processing with any one of the transmission power values in accordance with an instruction from the inter-vehicle communication control unit 11. As another method, the transmission unit 3 may perform transmission processing with the transmission power value instructed from the inter-vehicle communication control unit 11.

  The transmission unit 3 has a carrier sense function. That is, when transmitting the transmission signal, the transmission unit 3 determines whether the state of the carrier frequency is an idle state or a busy state based on the reception power on the carrier path. If transmission is busy, transmission of a transmission signal is awaited and carrier sense is performed again. Furthermore, the transmission part 23 performs the modulation system employ | adopted by the communication system (system A) between vehicles. The modulation scheme is not particularly limited, but for example, an OFDM modulation scheme can be applied.

  The local oscillator 4 generates a carrier wave having a frequency used for inter-vehicle communication and oscillates in the transmitter 3 or the receiver 4. Based on the frequency setting signal from the inter-vehicle communication control unit 11, the local oscillation unit 4 generates a frequency carrier wave and performs channel setting.

  The receiving unit 5 demodulates the signal received via the transmission / reception switching unit 2 and gives the demodulated signal to the data extraction unit 7 and the RSSI signal detection unit 6 as a received packet signal.

  The data extraction unit 7 receives a reception packet signal from the reception unit 5 and extracts vehicle information (vehicle data) included in the reception packet signal. Here, the vehicle information extracted by the data extraction unit 7 includes, for example, vehicle speed information, vehicle position information (for example, latitude / longitude information), traveling direction information, vehicle identification information, and the like. The data extraction unit 7 gives the extracted vehicle information to the database unit 8.

  The database unit 8 stores the vehicle information extracted by the data extraction unit 7 and the vehicle information of the host vehicle acquired from the inter-vehicle communication control unit 11. When the database unit 8 acquires new vehicle information of the same other vehicle or the host vehicle from the data extraction unit 7 and the inter-vehicle communication control unit 11, the database unit 8 updates the new vehicle information. Thereby, the database part 8 can hold | maintain the newest vehicle information of another vehicle and the own vehicle. The database unit 8 holds vehicle information acquired within a preset holding time.

  The RSSI signal detector 6 receives the received packet signal from the receiver 5, detects the received electric field strength of the received signal, and generates an RSSI signal. The RSSI signal detection unit 6 gives the generated RSSI signal to the other system area detection determination unit 9 and the inter-vehicle communication control unit 11.

  The other system area detection determination unit 9 receives the RSSI signal of the reception signal from the RSSI signal detection unit 6 and receives the threshold value from the other system area detection threshold setting unit 10 and compares the received electric field strength of the reception signal with the threshold value. To do.

  The other system area detection determination unit 9 determines that the service area of the other radio system has been detected when the received electric field strength of the received signal is larger than the threshold, and if the received electric field strength of the received signal is equal to or lower than the threshold, It is determined that the service area of the wireless system is not detected. Moreover, the other system area detection determination part 9 will give an area detection signal to the vehicle-to-vehicle communication control part 11, if the service area of another wireless system is detected.

  The other system area detection threshold setting unit 10 sets a threshold to be compared with the received electric field strength of the received signal in the other system area detection determination unit 9 based on the threshold setting signal received from the inter-vehicle communication control unit 11. Here, the threshold set by the other system area detection threshold setting unit 10 may be different for each channel frequency set by the local oscillation unit 4, for example.

  The inter-vehicle communication control unit 11 controls inter-vehicle communication. As main functions performed by the inter-vehicle communication control unit 11, the inter-vehicle communication control unit 11 includes an inter-vehicle communication control function unit 11a that controls inter-vehicle communication, another system radio wave interference avoidance function unit 11b, and a transmission resumption function unit 11c.

  The inter-vehicle communication control function unit 11a performs transmission / reception control of the existing inter-vehicle communication system. The inter-vehicle communication control function 11a issues a connection switching instruction to the transmission / reception switching unit 2, an instruction of a channel frequency setting signal to the local oscillation unit 4, and the like.

  Further, the inter-vehicle communication control function unit 11a acquires vehicle information of the host vehicle from a host control unit (not shown) that executes an inter-vehicle communication application, and stores the acquired vehicle information in the database unit 8 or a receiving unit. The vehicle information acquired from 5 is given to the host control unit.

  When the other system radio wave interference avoidance function unit 11b obtains the area detection signal from the other system area detection determination unit, the other system radio wave interference avoidance function unit 11b determines the own vehicle based on the vehicle information of the other vehicle and the vehicle information of the own vehicle held in the database unit 8. Monitoring vehicle information of other vehicles that are ahead and traveling in the same direction, and based on changes in the transmission state and traveling state of the inter-vehicle communication of the other vehicle, transmission stop or transmission power of the own vehicle's inter-vehicle communication It is determined whether or not to perform a value reduction process. The method using the other system radio wave interference avoiding function unit 11b will be described in detail in the section of operation.

  The transmission restart function unit 11c is configured to restart the transmission processing of the inter-vehicle communication after the other system radio wave interference avoiding function unit 11b stops the transmission of the inter-vehicle communication of the own vehicle. A method for resuming transmission processing by the transmission resumption function unit 11c will be described in detail in the section of operation.

(A-2) Operation of Embodiment Next, the processing operation of the area interference avoidance method of another radio system in the radio apparatus 100 of this embodiment will be described in detail with reference to the drawings.

  FIG. 3 is a flowchart illustrating area interference avoidance processing of another wireless system by the wireless device 100 according to the embodiment.

  The inter-vehicle communication control unit 11 gives a frequency setting signal to the local oscillation unit 4 in order to set a channel frequency to be searched. The local oscillating unit 4 gives a carrier wave having a channel frequency to the transmitting unit 3 or the receiving unit 5 based on the frequency setting signal.

  Here, the inter-vehicle communication control unit 11 gives a frequency setting signal of the transmission channel frequency to the local oscillator 4 during the transmission period, and gives a frequency setting signal of the reception channel frequency to the local oscillator 4 during the reception period. Further, the inter-vehicle communication control unit 11 provides the local oscillator 4 with a frequency setting signal of the channel frequency of the other radio system in order to search for the channel frequency used in the other radio system during the reception period.

  The radio wave signal captured by the antenna unit 1 is given to the receiving unit 5 through the transmission / reception switching unit 2, and the receiving unit 5 demodulates the received signal. At this time, when the reception unit 5 demodulates the signal of the reception channel frequency of the inter-vehicle communication, the reception packet signal is given to the data extraction unit 7.

  The vehicle information extracted by the data extraction unit 7 is held in the database unit 8. The host control unit (not shown) periodically acquires vehicle information of the host vehicle, and the vehicle information of the host vehicle is also held in the database unit 8 by the inter-vehicle communication control unit 11.

  Here, the vehicle information is, for example, vehicle speed information, vehicle position information (for example, latitude / longitude information), traveling direction information, vehicle identification information, and the like, and each information is associated and held in the database unit 8. The

  When the receiving unit 5 demodulates a signal of a channel frequency of another wireless system, the received packet signal is given to the RSSI signal detecting unit 6, and the RSSI signal detecting unit 6 determines the received electric field strength (RSSI) of the received signal. The other system area detection determination unit 9 is obtained.

  The other system area detection determination unit 9 compares the received electric field strength (RSSI) of the received signal with the threshold set by the other system area detection threshold setting unit 10.

  When the received electric field strength of the received signal is larger than the threshold value, the other system area detection determination unit 9 gives the area detection signal to the inter-vehicle communication control unit 11, and when the received electric field strength of the received signal is less than the threshold value, the other system area detection The determination unit 9 does not give an area detection signal.

  In FIG. 3, the inter-vehicle communication control unit 11 monitors the presence / absence of an area detection signal (S101), and if there is an area detection signal, it can determine that the host vehicle has entered a service area of another wireless system. Therefore, the vehicle-to-vehicle communication control unit 11 shifts the process to S107 and stops transmission of the vehicle-to-vehicle communication.

  On the other hand, when there is no area detection signal, the inter-vehicle communication control unit 11 refers to the database unit 8 and is ahead of the own vehicle based on the vehicle information of the own vehicle and the vehicle information of all other vehicles. And the preceding vehicle (vehicle identification information) which is drive | working in the same direction as the own vehicle is extracted (S102).

  For example, in FIG. 2, it is assumed that the host vehicle is a vehicle 1-2. In this case, the vehicle 1-1 corresponds to a preceding vehicle that is ahead of the host vehicle and traveling in the same direction as the host vehicle.

  As for the traveling direction of the vehicle, the traveling direction information is included in the vehicle information. Therefore, the inter-vehicle communication control unit 11 can specify the preceding vehicle by searching for other vehicles in the traveling direction information in the same direction as the traveling direction information of the host vehicle.

  Further, whether or not the vehicle is ahead of the host vehicle, the inter-vehicle communication control unit 11 is based on the vehicle position information of the host vehicle and the vehicle position information of the other vehicle with respect to the vehicle traveling in the same traveling direction as the host vehicle. The preceding vehicle can be specified by determining the positional relationship. When there are a plurality of preceding vehicles traveling in the same direction as the own vehicle, the inter-vehicle communication control unit 11 may set the immediately preceding vehicle as the preceding vehicle, or may arbitrarily select the preceding vehicle.

  Next, the inter-vehicle communication control unit 11 refers to the database unit 8 and confirms whether or not the vehicle information is updated at the transmission interval period or more with respect to the extracted vehicle information of the preceding vehicle (vehicle identification information) (S103). ).

  When the vehicle information is updated at the transmission interval period for the preceding vehicle, the inter-vehicle communication control unit 11 moves the process to S101 and returns to the confirmation state of the area detection signal. Extract the preceding vehicle.

  On the other hand, when the vehicle information is not updated for the preceding vehicle in a time longer than the transmission interval cycle, the inter-vehicle communication control unit 11 refers to the past vehicle information of the preceding vehicle stored in the database 8 and travels. A change in state is confirmed (S104).

  That is, the inter-vehicle communication control unit 11 confirms whether or not the preceding vehicle is still located in front of the host vehicle and is traveling in the same traveling direction as the host vehicle.

  When there is a change in the traveling state of the preceding vehicle (S105), the inter-vehicle communication control unit 11 moves the process to S101 and returns to the area detection signal confirmation state.

  On the other hand, when there is no change in the traveling state of the preceding vehicle (S105), that is, the preceding vehicle detects a service area of another wireless system, stops transmission of inter-vehicle communication, and the own vehicle It can be determined that information cannot be acquired.

  When there is no change in the traveling state of the preceding vehicle, the inter-vehicle communication control unit 11 determines that the own vehicle and the preceding vehicle are based on the latest vehicle position information of the own vehicle and the latest vehicle position information of the preceding vehicle. The separation distance L1 is obtained (S106).

  When the separation distance L1 between the host vehicle and the preceding vehicle is larger than the separation distance Lth1 necessary for interference resistance, the inter-vehicle communication control unit 11 moves the process to S101 and returns to the area detection signal confirmation state.

  On the other hand, when the separation distance L1 between the host vehicle and the preceding vehicle is equal to or less than the separation distance Lth1 necessary for interference resistance, the inter-vehicle communication control unit 11 stops transmission of inter-vehicle communication (S107).

  Here, FIG. 3 illustrates a case in which the inter-vehicle communication control unit 11 stops transmission when the separation distance L1 between the host vehicle and the preceding vehicle is equal to or less than the separation distance Lth1, but instead of the transmission suspension, You may make it instruct | indicate to the transmission part 3 to reduce the transmission power value which concerns on the vehicle-to-vehicle communication of a vehicle.

  Moreover, it may replace with the transmission stop by the vehicle-to-vehicle communication control part 11, and you may make it change the channel frequency which concerns on the vehicle-to-vehicle communication of the own vehicle. In this case, the transmission power value may be reduced and the channel frequency may be changed.

  Next, a processing operation in which the wireless device 100 according to the embodiment resumes the transmission process after stopping the transmission of the inter-vehicle communication will be described in detail with reference to the drawings.

  Here, any of the processes illustrated in FIG. 4 or FIG. 5 can be adopted as the transmission restart process by the inter-vehicle communication control unit 11.

  FIG. 4 is a flowchart illustrating a first transmission restart process performed by the wireless device 100 according to the embodiment.

  When the inter-vehicle communication control unit 11 stops the transmission process of the inter-vehicle communication of the own vehicle, the inter-vehicle communication control unit 11 records the stop position information (for example, latitude and longitude). Then, the inter-vehicle communication control unit 11 calculates the travel distance L2 of the host vehicle from the stop position information (S201).

  Here, various methods can be widely applied as the calculation method of the travel distance L2. For example, the inter-vehicle communication control unit 11 may set a distance between two points of the stop position information and the vehicle position information of the own vehicle as the travel distance L2 based on the vehicle position information and the stop position information of the own vehicle as GPS information. . Further, for example, when the vehicle-to-vehicle communication control unit 11 has map information, the vehicle-to-vehicle communication control unit 11 may calculate the travel distance L2 of the host vehicle from the stop position information on the map. Further, for example, the inter-vehicle communication control unit 11 may acquire speed information (vehicle speed pulse information) of the host vehicle, and obtain the travel distance L2 based on the speed information of the host vehicle and time information after transmission stop. .

  When the travel distance L2 from the transmission stop position is equal to or less than the separation distance Lth2, the inter-vehicle communication control unit 11 moves the process to S201 (S202).

  On the other hand, when the travel distance L2 from the transmission stop position is greater than the separation distance Lth2, the inter-vehicle communication control unit 11 confirms the presence or absence of an area detection signal (S203), and if there is no area detection signal, the inter-vehicle communication transmission process is performed. It resumes (S204).

  If there is an area detection signal in S203, it is determined that the host vehicle is in the service area of another wireless system, and the inter-vehicle communication control unit 11 moves the process to S201.

  FIG. 5 is a flowchart illustrating a second transmission restart process performed by the wireless device 100 according to the embodiment.

  First, the inter-vehicle communication control unit 11 acquires the received electric field strength (RSSI) of the received signal from the RSSI signal detecting unit 6. Further, the inter-vehicle communication control unit 11 calculates the travel distance L3 of the host vehicle from the transmission stop position (S301).

  Then, the inter-vehicle communication control unit 11 monitors the RSSI signal level and detects the maximum peak value of the RSSI signal level (S302). When the maximum peak value of the RSSI signal level is not detected, the inter-vehicle communication control unit 11 moves the process to S301.

  On the other hand, when the maximum peak value of the RSSI signal level is detected, the inter-vehicle communication control unit 11 compares the travel distance L3 of the host vehicle with the separation distance Lth3 (S303), and the travel distance L3 of the host vehicle is greater than the separation distance Lth3. In this case, the inter-vehicle communication control unit 11 resumes transmission (S304). Note that when the travel distance L3 of the host vehicle is equal to or less than the separation distance Lth3, the inter-vehicle communication control unit 11 moves the process to S301.

  In the second transmission resumption process shown in FIG. 5, when the own vehicle approaches the service area of another wireless system, the RSSI signal level of the received signal increases, and when the own vehicle approaches the roadside unit 3, the RSSI signal The level reaches the maximum peak value. And when the own vehicle leaves | separates from the roadside machine 3, an RSSI signal level will fall gradually.

  The second transmission resumption process uses the above characteristics. When the travel distance L3 of the host vehicle exceeds the separation distance Lth3, it can be determined that the host vehicle is sufficiently separated from the service area of another wireless system. In this case, the transmission process is resumed. Alternatively, instead of detecting the maximum peak value, similar detection may be performed by setting a value that exceeds an arbitrary threshold value and again becomes a value that is equal to or less than the threshold value.

(A-3) Effect of Embodiment As described above, according to this embodiment, the vehicle-mounted wireless device including the interference avoidance control method by area detection and transmission stop is a roadside device or vehicle-mounted device of another existing wireless system. Without changing the specifications, the communication service area of another wireless system can be detected in advance, and interference can be avoided.

  Further, according to this embodiment, even in the inter-vehicle communication system, there is no flag signal for notifying the surrounding vehicle that there is another wireless system in the transmission packet of the inter-vehicle communication system, and it varies depending on the application. Even a transmission packet can be notified that it is approaching the service area of another wireless system.

(B) Other Embodiments Although the wireless device of the above-described embodiment has been exemplified for use in interference avoidance processing with another wireless system, the wireless device of the present invention is applied to accident start processing such as collision avoidance. You may make it do.

  For example, as an accident scene on an expressway, a collision of a rear vehicle or contact at the time of lane change is assumed, but in this accident scene, accident avoidance support can be performed by a millimeter wave radar. Therefore, in a service area of a road-to-vehicle communication system such as a toll booth, there is no alternative even if the vehicle-to-vehicle communication system is stopped, so that the safety to the driver is not impaired.

  DESCRIPTION OF SYMBOLS 100 ... Wireless apparatus, 1 ... Antenna part, 2 ... Transmission / reception switching part, 3 ... Transmission part, 4 ... Local transmission part, 5 ... Reception part, 6 ... RSSI signal detection part, 7 ... Data extraction part, 8 ... Database part, 9 ... Other system area detection determination unit, 10 ... Other system area detection threshold setting unit, 11 ... Inter-vehicle communication control unit.

Claims (8)

Vehicle-to-vehicle communication means for performing vehicle-to-vehicle communication with wireless devices of other vehicles;
Other system area detecting means for detecting a communication area of another wireless system,
Vehicle information extraction means for extracting vehicle information contained in a received signal received from a radio device of another vehicle;
Vehicle information holding means for holding vehicle information of other vehicles extracted by the vehicle information extracting means and vehicle information of the own vehicle;
Based on the vehicle information of the own vehicle and the vehicle information of other vehicles of the vehicle information holding means, preceding vehicle detection means for detecting a preceding vehicle that is in front of the own vehicle and travels in the same direction as the own vehicle;
Preceding vehicle running state monitoring means for monitoring changes in the running state of the preceding vehicle;
A communication control means for determining that a communication area of another wireless system exists when the transmission and traveling state of the preceding vehicle change, and performing interference avoidance processing on the inter-vehicle communication means. Wireless device to do.   The communication control means obtains a separation distance between the preceding vehicle and the host vehicle when the transmission and traveling state of the preceding vehicle change, and the separation distance between the preceding vehicle and the host vehicle is equal to or less than a threshold value. The radio apparatus according to claim 1, wherein interference avoidance processing is sometimes performed.   3. The radio apparatus according to claim 1, wherein the communication control unit ends the interference avoidance process for the inter-vehicle communication unit according to a travel distance of the host vehicle after the start of the interference avoidance process. .   The communication control means terminates the interference avoidance process for the inter-vehicle communication means according to the travel distance of the host vehicle after detecting the maximum received electric field strength signal after the start of the interference avoidance process. The wireless device according to claim 1 or 2.   5. The radio apparatus according to claim 4, wherein the detection of the maximum received electric field strength signal is performed when the received electric field strength signal exceeds a predetermined threshold and then becomes equal to or lower than the threshold.   The radio apparatus according to claim 1, wherein the communication control unit stops transmission to the inter-vehicle communication unit as interference avoidance processing.   The radio apparatus according to claim 1, wherein the communication control unit instructs the inter-vehicle communication unit to reduce a transmission power value as interference avoidance processing.   The radio apparatus according to claim 1, wherein the communication control unit instructs the inter-vehicle communication unit to change a channel frequency as interference avoidance processing.

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