JP4193627B2 - Inter-vehicle communication device - Google Patents

Description

  The present invention relates to a vehicle-to-vehicle communication device that performs communication between vehicles.

2. Description of the Related Art Conventionally, as a vehicle-to-vehicle communication device that performs communication between vehicles, a device that communicates using a CSMA method is known as described in JP-A-2001-45013. When this apparatus is in a busy state at the time of transmission, it sets a time for performing carrier sense in accordance with the number of vehicles that perform communication, and attempts to increase the number of vehicles that can be successfully transmitted.
JP 2001-45013 A

  In the inter-vehicle communication described above, there is a problem in that appropriate communication may not be performed. For example, when the number of vehicles that can communicate is large, there is a certain limit on the number of vehicles that can be transmitted even if the carrier sense time is set according to the number of vehicles that communicate, and there is a risk that communication cannot be performed properly. There is.

  Accordingly, the present invention has been made to solve such a problem, and an object thereof is to provide an inter-vehicle communication device capable of performing appropriate inter-vehicle communication.

  That is, the inter-vehicle communication apparatus according to the present invention is characterized in that, in the inter-vehicle communication apparatus that performs inter-vehicle communication using the CSMA method, the transmission output of the inter-vehicle communication decreases as the degree of congestion of the inter-vehicle communication increases.

  According to this invention, the transmission output of each vehicle is narrowed by lowering the transmission output as the degree of congestion in inter-vehicle communication is higher, and the degree of congestion in inter-vehicle communication is reduced. For this reason, the number of vehicles that succeed in transmission increases, and appropriate inter-vehicle communication becomes possible.

  The inter-vehicle communication apparatus according to the present invention is characterized in that in inter-vehicle communication, received information such as vehicle ID and vehicle position information is transmitted to another vehicle.

  According to this invention, even if the transmission output is reduced and the transmission range becomes narrow, the other vehicle receives the information transmitted by the own vehicle and transmits it again, so that the transmission information of the own vehicle is transmitted to the transmission range of the own vehicle. It can be transmitted to other vehicles outside. Therefore, transmission information can be transmitted to a desired other vehicle while improving the success rate of transmission, and appropriate inter-vehicle communication can be realized.

  The inter-vehicle communication apparatus according to the present invention transmits at least position information of the own vehicle in the inter-vehicle communication.

  According to this invention, the position information of the own vehicle can be transmitted to other vehicles outside the transmission range of the own vehicle. As a result, the presence of the own vehicle can be recognized by other vehicles, and a collision accident or the like can be prevented in advance.

  Further, the inter-vehicle communication device according to the present invention is an inter-vehicle communication device that performs inter-vehicle communication using the CSMA method. When the information transmitted by inter-vehicle communication is information on another vehicle that is closer than a predetermined distance, in other cases. Compared to this, the transmission output of inter-vehicle communication is lowered.

  According to the present invention, it is possible to prevent the transmission range from being unnecessarily widened by reducing the transmission output according to the transmission information in the inter-vehicle communication, and the inter-vehicle communication may be congested due to the expansion of the transmission range. Is prevented. For this reason, the number of vehicles that succeed in transmission increases, and appropriate inter-vehicle communication becomes possible.

Further, the inter-vehicle communication device according to the present invention is an inter-vehicle communication device that performs inter-vehicle communication using the CSMA method. The own vehicle position detecting means that can detect the traveling position of the own vehicle on a map and another vehicle for identifying other vehicles. Based on the receiving means capable of receiving the identification information and other vehicle position information for detecting the position of the other vehicle, the traveling position of the own vehicle, the other vehicle identification information, and the other vehicle position information, the own vehicle Distance measuring means for measuring the distance between the vehicle and the other vehicle in front of the vehicle, and the received information can be transmitted to the other vehicle, and when the vehicle enters a specific area on the map, Increasing the transmission output of communication, when the own vehicle approaches the intersection, when there is another vehicle ahead of the own vehicle, a transmission means for setting the transmission output of the inter-vehicle communication according to the distance between the own vehicle and the other vehicle; It is characterized by providing. In this case, it is preferable to adjust the transmission output of the inter-vehicle communication according to the congestion degree of the inter-vehicle communication.

  According to these inventions, by increasing the transmission output when the own vehicle enters a specific area such as a dangerous area on the map, the existence of the own vehicle can be informed to other vehicles beforehand, and safe driving can be performed. Yes. Thereby, necessary information can be appropriately transmitted to other vehicles according to the position of the own vehicle, and appropriate inter-vehicle communication can be realized.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle-to-vehicle communication apparatus which can perform appropriate vehicle-to-vehicle communication can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
(First embodiment)
FIG. 1 shows a schematic configuration diagram of an inter-vehicle communication apparatus according to the present embodiment.

  The inter-vehicle communication device 1 according to the present embodiment is a device that performs wireless communication between vehicles by a CSMA (Carrier Sense Multiple Access) method. Here, the CSMA method means a method in which information is transmitted after the communication apparatus confirms a vacant (idle) period of a certain time or more on the communication path.

  As shown in FIG. 1, the inter-vehicle communication device 1 is a device installed in a vehicle (not shown), and includes a transmission unit 2, a reception unit 3, an antenna 4, and a control unit 5. The transmission unit 2 functions as a transmission unit that transmits transmission information to another vehicle through the antenna 4. For example, the transmission unit 2 modulates a carrier wave according to transmission information transmitted from the control unit 5 to generate a transmission signal, and transmits the transmission signal from the antenna 4. As the carrier wave, for example, a radio wave of 5.8 GHz is used. Note that radio waves of other frequencies may be used as this carrier wave.

  The transmission unit 2 is provided with an output variable unit 21. The output variable unit 21 changes the transmission output of the transmission unit 2 by lowering or increasing it, and functions as a transmission output variable means. As the output variable unit 21, for example, an amplifier capable of adjusting the amplification degree of the transmission signal is used. In this case, the transmission output can be changed by changing the amplification degree.

  The reception unit 3 is a reception unit that performs reception processing on a reception signal received by the antenna 4. For example, the reception unit 3 demodulates a reception signal and extracts reception information. The extracted reception information is input to the control unit 5.

  The control unit 5 performs overall control of the vehicle-to-vehicle communication device 1 and is mainly configured by a computer including a CPU, a ROM, and a RAM, for example. The control unit 5 is connected to the transmission unit 2 and the reception unit 3 and functions as a communication control unit. For example, the control unit 5 outputs a transmission output control signal to the output variable unit 21 of the transmission unit 2 and controls the transmission output.

  The control unit 5 also functions as information processing means for processing an application executed by communication. For example, the control unit 5 processes information received from the receiving unit 3 and executes an application based on the received information.

  Next, the operation of the vehicle-to-vehicle communication device according to this embodiment will be described.

  FIG. 2 is a flowchart of the operation of the vehicle-to-vehicle communication device 1 according to this embodiment. FIG. 3 is a calculation map in the transmission output setting process. As shown in S10 of FIG. 2, a carrier monitoring process is performed. The carrier monitoring process is a process for monitoring the transmission state of another vehicle in communication. For example, carrier sense that senses radio waves transmitted from other vehicles is performed, and the degree of congestion in inter-vehicle communication is detected from the result of the carrier sense.

  And it transfers to S12 and a transmission output setting process is performed. The transmission output setting process is a process for setting the transmission output of the inter-vehicle communication according to the congestion degree of the inter-vehicle communication. That is, it is set so that the transmission output of inter-vehicle communication decreases as the congestion degree of inter-vehicle communication increases. For example, as shown in FIG. 3, a calculation map of communication congestion level and transmission output is set in the control unit 5 in advance, and a transmission output corresponding to the congestion level of inter-vehicle communication is determined based on this calculation map.

  Note that the transmission output is not limited to the one that changes linearly according to the communication congestion level as shown in FIG. 3, but several transmission output levels are set and the transmission output level level is changed according to the communication congestion level. It may be a thing to do.

  Then, the process proceeds to S14, and it is determined whether or not it is a transmission timing. As to whether or not it is the transmission timing, for example, as a result of carrier sense, it is determined that it is the transmission timing when there is a vacancy for a certain time or longer in the communication network, and otherwise it is determined that it is not the transmission timing.

  When it is determined in S14 that the transmission timing is not reached, the process returns to S10 and the carrier monitoring process is performed again. On the other hand, when it is determined that it is the transmission timing, the process proceeds to S16, and a transmission process is performed. The transmission process is a process of transmitting transmission information with a set transmission output. For example, a transmission information signal and a transmission output control signal are output from the control unit 5 to the transmission unit 2. The transmission unit 2 modulates the carrier wave according to transmission information to generate a transmission signal, and amplifies the transmission signal to be transmitted at a predetermined transmission output, and performs transmission.

  According to such an inter-vehicle communication device 1, the transmission range of each vehicle is narrowed by lowering the transmission output as the degree of congestion of inter-vehicle communication is higher, and the degree of congestion of inter-vehicle communication is reduced. As a result, the number of vehicles that succeed in transmission increases, and appropriate inter-vehicle communication can be performed.

  In the inter-vehicle communication of the inter-vehicle communication device 1, it is preferable to include information received from other vehicles as transmission information. For example, even if the transmission output is lowered and the transmission range is narrowed as described above by transmitting information received from another vehicle such as the vehicle ID and vehicle position information of the other vehicle, the information transmitted by the own vehicle is reduced. When the other vehicle receives and transmits again, the transmission information of the own vehicle can be transmitted to other vehicles outside the transmission range of the own vehicle. Therefore, transmission information can be transmitted to a desired other vehicle while improving the success rate of transmission, and appropriate inter-vehicle communication can be realized.

  Further, in the inter-vehicle communication of the inter-vehicle communication device 1, it is preferable to transmit at least the position information of the own vehicle as transmission information and transmit the position information of the own vehicle. In this case, the position information of the own vehicle can be transmitted to other vehicles outside the transmission range of the own vehicle. As a result, the presence of the own vehicle can be recognized by other vehicles, and a collision accident or the like can be prevented in advance.

  For example, as shown in FIG. 4, when the own vehicle 60 is traveling toward the intersection C and the road is crowded, the degree of congestion in inter-vehicle communication increases and the transmission output decreases. Thereby, the transmission range S of the own vehicle 60 becomes narrow. In this case, the own vehicle 60 wants to transmit the position of the own vehicle 60 to the other vehicle 61 entering the intersection C at the same time, but since the transmission output is low and the transmission range is narrow, the position information of the own vehicle 60 directly to the other vehicle 61. Cannot be sent. In particular, when there is a building X in the vicinity of the intersection C, it becomes difficult for radio waves to reach the other vehicle 61 traveling on the intersecting road.

  However, the inter-vehicle communication device 1 according to the present embodiment transmits the position information of the host vehicle 60 within a transmittable range. And after the other vehicle 62 which drive | works within the transmission range receives the information, the positional information on the own vehicle 60 is further transmitted. And the other vehicle 61 can confirm the position of the own vehicle 60 because the other vehicle 61 receives the transmission information of the other vehicle 62.

On the other hand, when there is no vehicle at an intermediate position such as the other vehicle 62, the degree of communication congestion is low, and the transmission output is set high, so that the vehicle 60 can directly transmit to the other vehicle 61. Accordingly, even when there is no vehicle at an intermediate position such as the other vehicle 62, it is possible to appropriately transmit the transmission information to the desired other vehicle 61, and it is possible to realize appropriate inter-vehicle communication.
(Second embodiment)
Next, the vehicle-to-vehicle communication device according to the second embodiment will be described.

  The inter-vehicle communication device according to the present embodiment has the same hardware configuration as the inter-vehicle communication device according to the first embodiment of FIG. 1 except that the transmission output is changed according to the type of information to be transmitted. Yes.

  FIG. 5 shows a flowchart of the operation of the inter-vehicle communication device according to this embodiment.

  As shown in S50 of FIG. 5, application setting processing is first performed. The application setting process is a process for setting an application executed by the inter-vehicle communication device. For example, an application to be executed in the control unit 5 is set in accordance with a switch operation of the driver of the vehicle, and transmission information signal generation processing is performed.

  Then, the process proceeds to S52, and a transmission output setting process is performed. The transmission output setting process is a process of setting the transmission output of the inter-vehicle communication according to the application executed by the inter-vehicle communication device. In other words, when the transmission information in the application is information on another vehicle at a shorter distance than the predetermined distance, the transmission output is set lower than in other cases. Examples of applications that are transmitted to other vehicles in a short distance include a message transmission application that transmits a message to another vehicle instead of passing, horn, or hazard lighting, and a follow-up traveling application that performs transmission to the preceding and following vehicles. When these applications are set, the transmission output is set low.

  On the other hand, an accident reduction application that transmits the vehicle's position information to vehicles over a predetermined distance, an SOS application that transmits an SOS signal to recognize danger, and content exchange for the purpose of exchanging traffic information and photo information When an application or the like is set, the transmission output is set high.

  Then, the process proceeds to S54 and carrier sense is executed. Carrier sense is a process of sensing radio waves transmitted by other vehicles. Then, the process proceeds to S56, and it is determined whether or not it is a transmission timing. As to whether or not it is the transmission timing, for example, as a result of carrier sense, it is determined that it is the transmission timing when there is a vacancy for a certain time or longer in the communication network, and otherwise it is determined that it is not the transmission timing.

  If it is determined in S56 that the transmission timing is not reached, the process returns to S54 and carrier sense 54 is performed again. On the other hand, when it is determined that it is the transmission timing, the process proceeds to S58, and a transmission process is performed. The transmission process is a process of transmitting transmission information with a set transmission output. For example, a transmission information signal and a transmission output control signal are output from the control unit 5 to the transmission unit 2. The transmission unit 2 modulates the carrier wave according to transmission information to generate a transmission signal, and amplifies the transmission signal to be transmitted at a predetermined transmission output, and performs transmission.

According to such a vehicle-to-vehicle communication device 1, it is possible to prevent the transmission range from being unnecessarily widened by lowering the transmission output in accordance with the transmission information in the vehicle-to-vehicle communication. Is prevented from becoming crowded. For this reason, the number of vehicles that succeed in transmission increases, and appropriate inter-vehicle communication can be performed.
(Third embodiment)
Next, the vehicle-to-vehicle communication device according to the third embodiment will be described.

  FIG. 6 shows a schematic configuration diagram of the inter-vehicle communication device according to the present embodiment.

  The inter-vehicle communication apparatus according to the present embodiment is also an apparatus that performs the CSMA method in the same manner as the inter-vehicle communication according to the first embodiment and the second embodiment described above. As shown in FIG. 6, the inter-vehicle communication device 1a according to the present embodiment has a hardware configuration substantially similar to that of the inter-vehicle communication device 1 according to the first embodiment shown in FIG. It is different in point.

  The navigation system 6 functions as own vehicle position detecting means that can detect the traveling position of the own vehicle on a map. For example, the navigation system 6 stores map information in advance and detects the own vehicle position using GPS (Global Positioning System). What to do is used.

  FIG. 7 shows a flowchart of the operation of the inter-vehicle communication device according to this embodiment.

  As shown in S70 of FIG. 7, first, the vehicle position detection process is performed. The own vehicle position detection process is a process of detecting the position of the own vehicle on a map. For example, the navigation system 6 detects the traveling position of the vehicle on the map.

  Then, the process proceeds to S72, and a transmission output setting process is performed. The transmission output setting process is a process for setting the transmission output of the inter-vehicle communication according to the own vehicle position. For example, when the own vehicle enters a specific area on the map, the transmission output of the inter-vehicle communication is set to be increased. Here, the specific area refers to an area that is highly dangerous in traveling the vehicle and that allows traffic safety to be ensured by causing another vehicle to recognize the presence of the own vehicle. As a specific example, a region within a predetermined distance range from the intersection is applicable. In this transmission output setting process, it is preferable to set the output according to the distance from the preceding vehicle when a preceding vehicle exists when approaching an intersection.

  Then, the process proceeds to S74, and carrier sense is executed. Then, the process proceeds to S76, where it is determined whether or not it is a transmission timing. As to whether or not it is the transmission timing, for example, as a result of carrier sense, it is determined that it is the transmission timing when there is a vacancy for a certain time or longer in the communication network, and otherwise it is determined that it is not the transmission timing.

  When it is determined in S76 that the transmission timing is not reached, the process returns to S70, and the vehicle position detection process is performed again. On the other hand, when it is determined that it is the transmission timing, the process proceeds to S78, and a transmission process is performed. The transmission process is a process of transmitting transmission information with a set transmission output. For example, a transmission information signal and a transmission output control signal are output from the control unit 5 to the transmission unit 2. The transmission unit 2 modulates the carrier wave according to transmission information to generate a transmission signal, and amplifies the transmission signal to be transmitted at a predetermined transmission output, and performs transmission.

  According to such an inter-vehicle communication device, it is possible to widely inform other vehicles of the existence of the own vehicle by increasing the transmission output when the own vehicle enters a specific area such as a dangerous area on the map. Can run.

  Also, in the transmission output setting process, when a vehicle is ahead, when the vehicle is ahead, the transmission output can be reduced by setting the output according to the distance from the vehicle ahead, and the degree of congestion of communication Can be reduced. That is, even if the transmission output is lowered, the vehicle position can be notified to other vehicles via the preceding vehicle, and danger at the intersection can be avoided. Thereby, necessary information can be appropriately transmitted to other vehicles according to the position of the own vehicle, and appropriate inter-vehicle communication can be realized.

  In the transmission output setting process, it is preferable to adjust the transmission output of the inter-vehicle communication according to the congestion degree of the inter-vehicle communication. For example, the higher the congestion level of inter-vehicle communication, the smaller the transmission output is set. In the control process of FIG. 7, the carrier sense of S74 is performed before the transmission output setting process of S72, and the transmission output is set according to the communication congestion level detected by the carrier sense and the vehicle position. At that time, when the own vehicle enters an area near the intersection and the degree of congestion of inter-vehicle communication is high, communication information is transmitted to many vehicles near the intersection, so that it is not necessary to increase the transmission output of inter-vehicle communication so much. Therefore, when the communication congestion level is high, the transmission output is set smaller than when the communication congestion level is low. Thereby, the communication efficiency as the whole system can be improved. On the other hand, when the degree of congestion is low, the transmission output is set large. Thereby, the transmission range can be expanded, the presence of the own vehicle can be widely notified to other vehicles approaching the intersection, and traffic safety is improved.

1 is a schematic configuration diagram of an inter-vehicle communication device according to a first embodiment of the present invention. It is a flowchart which shows operation | movement of the inter-vehicle communication apparatus of FIG. It is explanatory drawing of the transmission output setting process in the flowchart of FIG. It is a specific explanatory view of the operation of the inter-vehicle communication device of FIG. It is a flowchart which shows operation | movement of the vehicle-to-vehicle communication apparatus which concerns on 2nd embodiment. It is a structure schematic diagram of the vehicle-to-vehicle communication apparatus which concerns on 3rd embodiment. It is a flowchart which shows operation | movement of the vehicle-to-vehicle communication apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inter-vehicle communication apparatus, 2 ... Transmission part, 3 ... Reception part, 4 ... Antenna, 5 ... Control part, 21 ... Output variable part.

Claims (1)

In the inter-vehicle communication apparatus that performs inter-vehicle communication using the CSMA method,
Own vehicle position detecting means capable of detecting the traveling position of the own vehicle on a map;
Receiving means capable of receiving other vehicle identification information for identifying another vehicle and other vehicle position information for detecting the position of the other vehicle;
Distance measuring means for measuring the distance between the host vehicle and the other vehicle existing in front of the host vehicle based on the traveling position of the host vehicle and the other vehicle identification information and the other vehicle position information;
The received information can be transmitted to other vehicles, and when the own vehicle enters a specific area on the map, the transmission output of the inter-vehicle communication is increased, and when the own vehicle approaches an intersection, the own vehicle A transmission means for setting a transmission output of the inter-vehicle communication according to a distance between the own vehicle and the other vehicle when there is another vehicle in front of the vehicle;
A vehicle-to-vehicle communication device comprising:

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