JP2009219031A - In-vehicle communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the frequency of transmitting travel information of one's own device-mounted vehicle in a time period overlapped with a time period for another in-vehicle communication device to transmit travel information of another device-mounted vehicle, in an in-vehicle communication device that transmits the travel information of the device-mounted vehicle. <P>SOLUTION: The in-vehicle communication device comprises a frame generating section for generating a frame including information to be transmitted and a transmission section for transmitting the frame, the in-vehicle communication device further comprises a situation acquisition section for acquiring traveling situation information of a device-mounted vehicle and a frame range designation section for designating a frame use range based on the information acquired by the situation acquisition section, wherein the frame generating section generates a frame including information to be transmitted, within the frame use range designated by the frame range designation section. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-vehicle communication device that transmits travel information of a mounted vehicle by a signal divided into a plurality of frames.

  2. Description of the Related Art An in-vehicle communication system in which an in-vehicle communication device is mounted on each vehicle traveling on a road and each vehicle notifies its own position information, own speed information, and the like is widely known. The in-vehicle communication device of each vehicle receives the information transmitted from the other vehicle and performs traveling control of the own vehicle based on the received information so that contact with the other vehicle is avoided.

JP 2004-62381 A

  In the in-vehicle communication system, the in-vehicle communication device of each vehicle performs carrier sense based on a broadcast signal transmitted from another vehicle. Here, carrier sense refers to processing for detecting a time zone used by other vehicles for communication. Based on the carrier sense, the in-vehicle communication device of each vehicle transmits the travel information of the host vehicle in a time zone that does not overlap with the time zone in which the travel information is transmitted from another vehicle.

  However, it is difficult to perform carrier sense between vehicles in which radio signal propagation is not good. In this case, traveling information may be transmitted from a plurality of vehicles that have not undergone carrier sense to each other in overlapping time zones. In this case, in the in-vehicle communication device of a vehicle different from the plurality of vehicles, a plurality of pieces of travel information are received in an overlapping manner. At this time, the in-vehicle communication device that receives a plurality of pieces of traveling information in a superimposed manner does not acquire any information. For this reason, there is a problem in that the amount of information transmission between vehicles decreases when the radio signal propagation state is not good.

  The present invention has been made for such a problem. That is, in the in-vehicle communication device that transmits the travel information of the mounted vehicle, the frequency of transmitting the travel information of the own vehicle is reduced in a time zone that overlaps the time zone in which the other in-vehicle communication device transmits the travel information of the mounted vehicle. The purpose is to do.

  The present invention is an in-vehicle communication device including a frame generation unit that generates a frame including transmission target information, and a transmission unit that transmits the frame, and a situation acquisition unit that acquires travel situation information of the mounted vehicle; A frame range specifying unit that specifies a frame use range based on information acquired by the situation acquisition unit, and the frame generation unit adds the transmission target information to the frame use range specified by the frame range specifying unit. It is characterized by generating a frame including it.

  Further, in the in-vehicle communication device according to the present invention, the frame range designation unit includes a frame segmentation unit that segments a frame according to an environment in which the mounted vehicle travels, acquisition information by the situation acquisition unit, frame segmentation, It is preferable that the frame use range is designated based on the association by the association unit.

  In the in-vehicle communication device according to the present invention, it is preferable that the acquisition information by the situation acquisition unit is information indicating a traveling direction azimuth of the mounted vehicle.

  According to the present invention, in the in-vehicle communication device that transmits the travel information of the mounted vehicle, the travel information of the own vehicle is transmitted in a time zone that overlaps the time zone in which the other in-vehicle communication device transmits the travel information of the mounted vehicle. The frequency of transmission can be reduced.

(1) Basic Processing FIG. 1 shows the configuration of the in-vehicle communication device according to the first embodiment of the present invention. The in-vehicle communication device mounted in each of the plurality of vehicles constitutes an in-vehicle communication system. Each in-vehicle communication device notifies and transmits travel information including the position information and speed vector of the mounted vehicle. The in-vehicle communication device that has received the traveling information transmitted from the other vehicle performs traveling control of the own vehicle based on the traveling information so that contact between the transmission source vehicle and the own vehicle is avoided.

  The travel information of the mounted vehicle is given to the information processing unit 10 as follows. The positioning device 20 receives the satellite signal via the positioning antenna 18, obtains the position information of the mounted vehicle, and outputs it to the speed vector calculation unit 22 and the information processing unit 10. The velocity vector calculation unit 22 calculates a velocity vector based on the time change of the position information output from the positioning device 20 and outputs the calculated velocity vector to the information processing unit 10. The information processing unit 10 uses the set of the position information output from the positioning device 20 and the speed vector output from the speed vector calculation unit 22 as travel information of the mounted vehicle.

  The information processing unit 10 generates a broadcast signal for informing and transmitting the traveling information of the mounted vehicle and outputs the broadcast signal to the transmission unit 12. The transmission unit 12 transmits a broadcast signal via the communication antenna 14. The receiving unit 16 receives a broadcast signal transmitted from another vehicle via the communication antenna 14 and outputs it to the information processing unit 10.

  The information processing unit 10 extracts travel information of other vehicles from the broadcast signal output from the receiving unit 16 and outputs the traveling information to the vehicle control unit 24. Further, the information processing unit 10 outputs traveling information of the host vehicle to the vehicle control unit 24. The vehicle control unit 24 switches the steering, braking, transmission gear, accelerator, etc. of the own vehicle based on the traveling information of the other vehicle and the traveling information of the own vehicle so that the contact between the own vehicle and the other vehicle is avoided. Take control.

  FIG. 2 shows the configuration of the broadcast signal 30. The broadcast signal 30 is divided into a plurality of frames 32. The information processing unit 10 determines a range to be used for transmitting travel information, out of the entire range of one frame 32, based on the time position in the frame 32. Then, the travel information of the mounted vehicle is recorded and transmitted in the determined use range.

  Each in-vehicle communication device constituting the in-vehicle communication system transmits a broadcast signal at a predetermined time interval based on the timing indicated by the satellite signal. Moreover, each vehicle-mounted communication apparatus synchronizes when transmitting a broadcast signal based on the timing which a satellite signal shows. Thereby, the frame leading end time and the frame trailing end time of the broadcast signal transmitted by each in-vehicle communication device are the same. In order to perform such synchronization processing, the positioning device 20 outputs the received satellite signal to the information processing unit 10. The information processing unit 10 outputs each frame of the broadcast signal to the transmission unit 12 based on the timing indicated by the satellite signal.

(2) Determination of use range of frame The in-vehicle communication device according to the present embodiment specifies a frame assignment range based on the traveling direction of the mounted vehicle. Then, the other vehicle use range is detected based on the carrier sense, and travel information is recorded and transmitted in a frame use range in which the other vehicle use range is excluded from the specified frame allocation range.

  First, the specification of the frame allocation range based on the traveling direction of the mounted vehicle will be described. For example, the traveling direction is defined as a positive rotation direction in which the north direction is 0 °, and the direction of turning to the north-west-southeast direction with the mounted vehicle as the center.

  In order to specify the frame allocation range, the information processing unit 10 performs processing for associating the time position in the frame with the azimuth scale. For example, as shown in FIG. 2, the scale value of the azimuth scale 34 at the frame front end time is set to 0 °, and the scale value of the azimuth scale 34 at the frame rear end time is set to 180 °. For this association, the information processing unit 10 includes a memory address table in which the address of the memory provided in the information processing unit 10 for storing the frame before transmission is associated with the scale value of the azimuth scale 34. Can be done with.

  When the travel direction indicated by the travel vector output from the speed vector calculation unit 22 is φ °, the information processing unit 10 assigns a frame with an azimuth scale range of φ ° or more and less than φ ° + α × 180 °. Specify as a range. Here, α is a usage rate determined as a positive value less than 1, and is determined according to the traveling environment of the mounted vehicle, such as the width of the road on which the mounted vehicle travels, the traffic volume (the number of vehicles traveling per unit time), and the like. It is preferable to do. These values from which the usage rate α is determined can be obtained based on a broadcast signal transmitted from another vehicle. The usage rate α is, for example, a larger value as the width of the road on which the mounted vehicle travels is larger, and a larger value as the traffic volume on the road on which the mounted vehicle travels is larger.

  Here, when α = 0.5, an azimuth angle scale range of φ ° or more and less than φ ° + 90 ° is a frame allocation range. For example, when the travel direction φ ° indicated by the travel vector is 45 °, the range of the scale value of 45 ° or more and less than 135 ° is the frame allocation range, as indicated by hatching in FIG.

  Of the azimuth scale range of φ ° or more and less than φ ° + α × 180 °, the range of 180 ° or more is based on the value indicated by the remainder obtained by dividing the value of the range of 180 ° or more by 180 °. The frame allocation range is specified with reference to the azimuth scale. For example, when α = 0.5 and the travel direction indicated by the travel vector is 300 °, the range of φ ° or more and less than φ ° + α × 180 ° is 300 ° or more and less than 390 °. In this case, in the azimuth scale range of 300 ° or more and less than 390 °, the range defined by the remainder obtained by dividing the value of the range of 180 ° or more by 180 ° is 120 ° or more and less than 180 °, and 0 ° or more and 30 Less than °. Therefore, in this case, an azimuth scale range of 120 ° or more and less than 180 ° and an azimuth scale range of 0 ° or more and less than 30 ° are frame allocation ranges.

  Next, the in-vehicle communication device determines the use exclusion range within the frame allocation range specified based on the traveling direction by carrier sense. The information processing unit 10 detects the range used by the in-vehicle communication device of the other vehicle as the other vehicle use range out of the entire range of the broadcast signal frame output from the reception unit 16. And the range which excluded the other vehicle use range from the frame allocation range specified previously is made into a frame use range. The information processing unit 10 generates a broadcast signal in which travel information is recorded in the frame usage range, and outputs the broadcast signal to the transmission unit 12. The transmission unit 12 transmits a broadcast signal via the communication antenna 14.

  In the conventional in-vehicle communication device, each in-vehicle communication device uses the entire frame range as the frame allocation range. And the other vehicle use range was determined based on carrier sense, and the broadcast signal which recorded driving information was transmitted to the range which excluded the other vehicle use range among the whole frame ranges. However, carrier sense can be performed between vehicles that can sense the carrier waves of the broadcast signal with each other. Therefore, it is difficult to perform carrier sense between vehicles having a poor radio signal propagation environment. A plurality of vehicles that have not performed carrier sense with each other may transmit travel information in overlapping time zones. In this case, in the in-vehicle communication device of a vehicle different from the plurality of vehicles, a plurality of transmission information is received in an overlapping manner. At this time, there is a problem that the in-vehicle communication device that receives a plurality of pieces of traveling information in a superimposed manner cannot acquire any information.

  For example, as shown in FIG. 3, an example in which vehicles 42 </ b> A, 42 </ b> B, and 42 </ b> C exist in the road 36, the road 38, and the intersection at the intersection where the road 36 and the road 38 intersect, respectively. There is a building 40 between the vehicle 42A and the vehicle 42B, and a broadcast signal is blocked between the vehicle 42A and the vehicle 42B. This makes it difficult for the in-vehicle communication devices of the vehicles 42A and 42B to perform carrier sense. At this time, the traveling information may be transmitted from the vehicle 42A and the vehicle 42B in the overlapping time zone. In this case, the in-vehicle communication device of the vehicle 42C cannot obtain travel information from either of the vehicles 42A and 42B.

  According to the in-vehicle communication device according to the present embodiment, the in-vehicle communication device specifies the frame allocation range based on the traveling direction of the mounted vehicle. Then, the use exclusion range is determined based on the carrier sense, and the travel information is recorded and transmitted in the frame use range excluding the other vehicle use range from the frame allocation range. Therefore, it is possible to shift the frame usage range of each in-vehicle communication device of a plurality of vehicles having different traveling directions. Therefore, it is possible to reduce the frequency at which the traveling information is transmitted from a plurality of vehicles with overlapping time zones. This can reduce the frequency of not acquiring information based on the fact that the traveling information is received in an overlapping manner, and can improve the amount of information transmitted between vehicles.

  For example, in the situation shown in FIG. 3, the vehicle 42A travels on the road 36 in the east direction (270 ° direction), and the vehicle 42B travels on the road 38 in the north direction (0 ° direction). The difference in travel direction between the vehicle 42A and the vehicle 42B is 90 °. Therefore, if α = 0.5, the vehicle 42A records the traveling information within the frame allocation range of the azimuth angle scale of 90 ° to less than 180 °, and the vehicle 42B has the azimuth angle scale of 0 ° to less than 90 °. Travel information is recorded within the frame allocation range. Therefore, the in-vehicle communication device of the vehicle 42C can obtain travel information from both the vehicles 42A and 42B.

(3) Another Example of Azimuth Scale In the above, the information processing unit 10 sets the azimuth scale value at the frame front end time to 0 ° and the azimuth scale value at the frame rear end time to 180 °. Corresponding position and azimuth scale. However, the azimuth range of the azimuth scale can be determined arbitrarily. For example, as shown in FIG. 4, the azimuth scale value at the frame front end time may be set to 0 °, and the azimuth scale value at the frame rear end time may be set to 360 °.

  When the travel direction indicated by the travel vector output from the speed vector calculation unit 22 is φ °, the information processing unit 10 sets an azimuth scale range of φ ° or more and less than φ ° + α × 360 ° to the frame allocation range. As specified. When the usage rate α is α = 0.25, an azimuth scale range of φ ° or more and less than φ ° + 90 ° is a frame allocation range. For example, when the travel direction φ ° indicated by the travel vector is 45 °, the range of the scale value of 45 ° or more and less than 135 ° is determined by the azimuth angle scale 34 associated with the frame 32 of FIG. It becomes.

  Of the azimuth angle scale range of φ ° or more and less than φ ° + α × 360 °, the range of 360 ° or more is based on the value indicated by the remainder obtained by dividing the value exceeding 360 ° by 360 °. Specify the frame allocation range by referring to the angular scale. For example, when α = 0.25 and the travel direction indicated by the travel vector is 300 °, the range of φ ° or more and less than φ ° + α × 360 ° is 300 ° or more and less than 390 °. In this case, the frame allocation range defined by the remainder obtained by dividing the value of the range of 360 ° or more by 360 ° in the azimuth scale range of 300 ° or more and less than 390 ° is 0 ° or more and less than 30 °. Therefore, in this case, an azimuth scale range of 300 ° to less than 360 ° and an azimuth scale range of 0 ° to less than 30 ° are frame allocation ranges.

  When the azimuth scale value at the frame front time is 0 °, the azimuth scale value at the frame end time is 180 °, the time position in the frame is associated with the azimuth scale, and α = 0.5 On the other hand, the oncoming vehicle having a difference in travel direction of 180 ° uses the same range as the frame allocation range. On the other hand, when the azimuth scale value at the frame front end time is 0 °, the azimuth scale value at the frame rear end time is 360 °, the time position in the frame is associated with the azimuth scale, and α = 0.25. On the other hand, an oncoming vehicle having a difference in traveling direction of 180 ° sets a different range as the frame allocation range.

(4) Switching of processing based on distance from intersection The in-vehicle communication device according to the first embodiment specifies a frame allocation range based on the traveling direction of the mounted vehicle. Then, the other vehicle use range is detected based on the carrier sense, and the travel information is recorded and transmitted in the frame use range excluding the other vehicle use range from the frame allocation range. In such a frame division method, the range determined by the usage rate α in the entire frame range is the frame allocation range. Therefore, the amount of information transmission per unit time is limited as compared with the case where the entire frame range is allocated.

  Therefore, in the in-vehicle communication device according to the second embodiment, when the mounted vehicle is traveling at a position sufficiently away from the intersection, processing based on the frame division method is not performed, and the entire frame range is normally set as the allocated frame range. The frame use range is determined by the carrier sense method. When the mounted vehicle approaches the intersection, the frame usage range is determined based on the frame division method.

  FIG. 5 shows the configuration of the in-vehicle communication device according to the second embodiment. The same components as those in the in-vehicle communication device in FIG. This in-vehicle communication device includes a map information storage unit 26. The map information stored in the map information storage unit 26 includes intersection position information. The information processing unit 10 acquires the position information of the mounted vehicle from the positioning device 20. Further, map information is read from the map information storage unit 26. Then, based on the position information of the mounted vehicle and the map information, the distance from the intersection located closest to the mounted vehicle is calculated.

  When the distance from the intersection is equal to or greater than a predetermined approach threshold, the information processing unit 10 determines the frame usage range based on the normal carrier sense method. On the other hand, when the distance from the intersection is less than the predetermined approach threshold, the frame use range is determined based on the frame division method. The information processing unit 10 outputs a broadcast signal in which travel information is recorded in the determined frame use range to the transmission unit 12. The transmission unit 12 transmits a broadcast signal via the communication antenna 14.

  On the road away from the intersection, there is little need for carrier sense with vehicles traveling on the intersection. Therefore, it is sufficient that the carrier sense is performed between the vehicle traveling in the same direction as the own vehicle or the oncoming vehicle. There are many cases where the propagation state of the radio signal is good between the vehicle in the same direction or the oncoming vehicle, and carrier sense can be performed well. Therefore, even if the frame use range is determined by the normal carrier sense method, the frequency at which the traveling information is transmitted from a plurality of vehicles with overlapping time zones is low. According to the in-vehicle communication device according to the second embodiment, when the mounted vehicle is away from the intersection, it is possible to increase the amount of information transmission per unit time by executing processing based on the normal carrier sense method.

  On the other hand, in the vicinity of an intersection, there is a high need to acquire travel information of a vehicle traveling on an intersection road. However, due to the presence of a building or the like at a corner, it is often difficult to perform carrier sense with a vehicle traveling on a crossing road. This increases the frequency with which the traveling information is transmitted from a plurality of vehicles with overlapping time zones. According to the in-vehicle communication device according to the second embodiment, when the mounted vehicle approaches the intersection, the processing based on the frame division method is executed, and the traveling information is obtained from the plurality of vehicles on the intersection road in the time zone. It is possible to reduce the frequency of transmission by overlapping.

(5) Intersection aspect frame division method The vehicle-mounted communication apparatus which concerns on 3rd Embodiment which deform | transformed 2nd Embodiment is demonstrated. The in-vehicle communication device according to the third embodiment specifies the frame allocation range according to the mode of the intersection when the mounted vehicle approaches the intersection. The configuration of the in-vehicle communication device according to the third embodiment is the same as the configuration of the in-vehicle communication device in FIG. 5 and will be described with reference to FIG.

  When the distance from the intersection is equal to or greater than a predetermined approach threshold, the information processing unit 10 determines the frame usage range based on the normal carrier sense method. On the other hand, when the distance from the intersection is less than the predetermined approach threshold, the frame allocation range is specified based on the intersection mode frame division method described below, and the frame usage range is determined.

  The intersection aspect frame division method will be described. When the distance from the intersection is less than a predetermined approach threshold, the information processing unit 10 acquires intersection information indicating the mode of the intersection from the map information. The intersection information includes information such as the number of branch roads connected to the intersection, the extension direction of the branch roads, and the width of each branch road. For example, in the case of an intersection where a road extending from east to west and a road extending from north to south intersect, the number of branch roads is four. A branch road extending from the south to the north in the direction of the intersection, a branch road extending from the east to the west in the direction of the intersection, a branch road extending from the north to the south in the direction of the intersection, and a direction from the west to the east in the direction of the intersection The extending directions of the extending branch road are 0 °, 90 °, 180 °, and 270 °, respectively.

  The information processing unit 10 assigns a branch road identification code to each branch road. For example, a numerical value indicating the extension direction of a branch road is used as a branch road identification code of the branch road. The information processing unit 10 divides the time position of the frame by the number of branch roads, and associates a road identification code with each divided range. For example, in the example of FIG. 6A, the frame allocation range is associated with each branch road whose extension directions are 0 °, 90 °, 180 °, and 270 ° in order from the front end of the frame.

  Based on the speed vector output from the speed vector calculation unit 22, the information processing unit 10 determines the identification code of the branch road on which the mounted vehicle has traveled. Then, the frame allocation range associated with the identification code is specified as the frame allocation range for the mounted vehicle.

  The information processing unit 10 detects the other vehicle usage range based on carrier sense with the in-vehicle communication device of the other vehicle. And the range which excluded the other vehicle use range from the specified frame allocation range is made into a frame use range.

  According to such processing based on the intersection mode frame division method, the frame usage range can be determined for each vehicle according to the number of branch roads at the intersection. As a result, it is possible to increase the effect of reducing the frequency with which the traveling information is transmitted from a plurality of vehicles with overlapping time zones.

  The frame may be divided according to the width of each branch road. In this case, the information processing unit 10 determines the division ratio based on the width of each branch road. For example, if the ratio of the widths of four branch roads is 1: 4: 1: 4, the frame allocation range corresponding to each branch road is 1: 4: 1 as shown in FIG. : Divide by 4 ratio.

  In general, wider roads have more traffic. Therefore, by determining the frame allocation range according to the width of each branch road, it is possible to increase the effect of reducing the frequency with which the traveling information is transmitted from a plurality of vehicles over time.

(6) Intersection determination by speed vector and transmission of intersection information In the in-vehicle communication device according to the second and third embodiments, whether or not the mounted vehicle has approached the intersection based on the position information and map information of the mounted vehicle. Determine. In the in-vehicle communication device according to the third embodiment, the intersection information is acquired from the map information, and the frame allocation range is determined for the vehicle traveling on each branch road by dividing the frame based on the aspect of the intersection. The

  However, some intersections that actually exist do not include intersection information in the map information. When the mounted vehicle approaches such an intersection, processing according to the approach to the intersection is not performed. The fourth embodiment to be described next solves such a problem. FIG. 7 shows the configuration of the in-vehicle communication device according to the fourth embodiment. The same components as those in the in-vehicle communication device in FIG.

  The information processing unit 10 monitors information stored in the intersection flag storage unit 28. And when the intersection flag is memorize | stored in the intersection flag memory | storage part 28, the information processing part 10 performs the process based on an intersection aspect frame division system. On the other hand, when no intersection flag is stored in the intersection flag storage unit 28, the information processing unit 10 executes processing based on the normal carrier sense method. The intersection flag is information indicating that the mounted vehicle has approached the intersection, and is stored in the intersection flag storage unit 28 by the following process.

(I) Intersection Determination The information processing unit 10 acquires a broadcast signal transmitted from another vehicle from the receiving unit 16. Then, the position information of the other vehicle is extracted as the other vehicle position information from the broadcast signal, and the speed vector of the other vehicle is extracted as the other vehicle speed vector.

  The information processing unit 10 obtains an intersection determination area based on the position information output from the positioning device 20 and the speed vector output from the speed vector calculation unit 22. The intersection determination area is a rectangular area in which the position of the mounted vehicle 42D traveling in the extending direction of the road 46 is the center of gravity, and the direction perpendicular to the speed vector is the longitudinal direction, as in the area surrounded by the alternate long and short dash line in FIG. It is. The length in the velocity vector direction of the intersection determination area 48 is an average value that the width of the intersection road 44 can take. The length of the intersection determination area 48 in the direction perpendicular to the speed vector direction is an average value of the line-of-sight distance of the intersection road 44 viewed from the road intersection.

The intersection determination area may have any shape as long as the intersection determination process can be executed based on the positional relationship with another vehicle. For example, as shown in FIG. 9, an angle θ is formed with respect to the traveling direction of the vehicle 42D, straight lines l ₁ and l ₂ intersecting at the center of gravity of the vehicle 42D, and parallel to the traveling direction of the vehicle 42D. It may be defined as triangular regions T ₁ and T ₂ formed by straight lines l ₃ and l ₄ whose distance from the center of gravity is d.

  Next, the information processing unit 10 obtains a direction difference angle formed by the speed vector output from the speed vector calculation unit 22 and the other vehicle speed vector.

  The information processing unit 10 determines whether or not the intersection existence condition that the position indicated by the other vehicle position information exists in the intersection determination region and the magnitude of the direction difference angle is within the determination angle range is satisfied. . Here, the determination angle range is determined based on a range of angles formed by two roads that intersect at a road intersection. For example, it is set to 45 ° or more and 135 ° or less or −135 ° or more and −45 ° or less.

  The information processing unit 10 stores the intersection flag in the intersection flag storage unit 28 when the intersection existence condition is satisfied. On the other hand, when the intersection existence condition is not satisfied, the null information is stored in the intersection flag storage unit 28.

(Ii) Acquisition of intersection information based on broadcast signals transmitted from other vehicles The information processing unit 10 executes such intersection determination processing and acquires broadcast signals transmitted from a plurality of vehicles from the reception unit 16. . Then, the intersection information is acquired based on the current position information output from the positioning device 20 and the traveling information included in the acquired broadcast signal.

  The intersection information includes information such as the position of the intersection, the number of branch roads connected to the intersection, the extension direction of the branch roads, the width of each branch road, the traffic volume of each branch road, and the approach threshold. The position of the intersection can be acquired based on the position information of the mounted vehicle. The number of branch roads connected to the intersection, the branching direction of the branch roads, the width of each branch road, the traffic volume of each branch road, etc. are obtained from each other vehicle's travel information from broadcast signals sent from multiple other vehicles. It can be acquired based on estimation calculation based on traveling information of a plurality of other vehicles. The approach threshold value here is intended to be transmitted to the in-vehicle communication device of another vehicle, and can be set by the user of the in-vehicle communication device of the own vehicle. Further, the information processing unit 10 may determine the approach threshold value to be a larger value as the width of the intersection road at the intersection or the width of the road on which the mounted vehicle travels increases.

  After storing the intersection flag in the intersection flag storage unit 28, the information processing unit 10 determines the frame use range based on the above-described intersection aspect frame division method. Then, a broadcast signal in which not only traveling information but also intersection information is recorded in the determined frame usage range is generated and output to the transmission unit 12. The transmission unit 12 transmits a broadcast signal via the communication antenna 14.

  According to such a process, the in-vehicle communication device of the vehicle that has entered the intersection can determine whether or not the own vehicle exists at the intersection based on the broadcast signal transmitted from the other vehicle. When it is determined that the vehicle exists at the intersection, a broadcast signal in which the travel information and the intersection information are recorded can be transmitted to the frame usage range determined based on the intersection mode frame division method.

(7) Processing executed by in-vehicle communication device that has received a broadcast signal including travel information and intersection information Next, processing executed by an in-vehicle communication device of another vehicle that has received a broadcast signal that includes not only travel information but also intersection information Will be described. The information processing unit 10 stores null information in the intersection flag storage unit 28 when the intersection information is not included in the broadcast signal output from the reception unit 16. After storing the null information in the intersection flag storage unit 28, the information processing unit 10 outputs a broadcast signal in which the traveling information is recorded in the frame usage range determined based on the normal carrier sense method to the transmission unit 12.

  On the other hand, when the broadcast signal output from the receiving unit 16 includes intersection information, the information processing unit 10 causes the intersection flag storage unit 28 to store an intersection flag. After storing the intersection flag in the intersection flag storage unit 28, the information processing unit 10 outputs a broadcast signal in which the travel information and the intersection information are recorded in the frame usage range determined based on the intersection mode frame division method to the transmission unit 12. To do. This intersection information may be included in the broadcast signal output from the receiving unit 16, or based on the processing described in (6) (ii) above, broadcasts transmitted from a plurality of other vehicles. It may be newly acquired based on the signal.

  When intersection information is included in the broadcast signal output from the receiving unit 16, a determination process based on the approach threshold is performed before the intersection flag storage unit 28 stores the intersection flag or null information as follows. Also good.

  When the broadcast information output from the receiving unit 16 includes intersection information, the information processing unit 10 extracts an approach threshold value from the intersection information. And when the distance from the intersection of a mounted vehicle is more than an approach threshold value, null information is memorize | stored in the intersection flag memory | storage part 28. FIG. After storing the null information in the intersection flag storage unit 28, the information processing unit 10 outputs a broadcast signal in which the travel information is recorded in the frame usage range determined based on the normal carrier sense method to the transmission unit 12.

  On the other hand, when the distance from the intersection of the mounted vehicle is less than the approach threshold, the intersection flag storage unit 28 stores the intersection flag. After storing the intersection flag in the intersection flag storage unit 28, the information processing unit 10 outputs a broadcast signal in which the travel information and the intersection information are recorded in the frame usage range determined based on the intersection mode frame division method to the transmission unit 12. To do.

(8) Effects of the Fourth Embodiment According to such processing, the in-vehicle communication device of each vehicle can determine whether or not the mounted vehicle exists at the intersection regardless of the map information. Therefore, even when the mounted vehicle approaches an intersection where the intersection information is not included in the map information, a process corresponding to the approach to the intersection can be executed.

  For example, an example in which the vehicle 42E exists in an intersection where the road 50 and the road 52 intersect as shown in FIG. In this case, the in-vehicle communication device of the vehicle 42E determines based on the broadcast signal transmitted from the vehicle 42F or 42G existing on the road 50 that the own vehicle exists at the intersection. Further, intersection information is generated based on broadcast signals transmitted from the vehicles 42F, 42G, 42H, and 42I existing on each branch road. And the vehicle-mounted communication apparatus of the vehicle 42E transmits the broadcast signal which recorded driving | running | working information and intersection information. Each of the in-vehicle communication devices of the vehicles 42F, 42G, 42H, and 42I executes the process described in the above (7) based on the broadcast signal including the travel information and the intersection information transmitted from the vehicle 42E.

  In addition, here, as the fourth embodiment, the process of determining the frame use range based on the intersection mode frame division method when the mounted vehicle approaches the intersection has been described. As described above, instead of executing the process based on the intersection mode frame division method, the process based on the frame division method may be executed.

  In the above description, as to the intersection mode frame division method, the process of determining the frame allocation range according to the number of branch roads or the width of each branch road has been described, as shown in FIG. In addition to such processing, processing for determining a frame allocation range according to the traffic volume of each branch road may be executed. In this case, the information processing unit 10 determines the division ratio based on the traffic volume of each branch road. For example, if the traffic volume ratio of four branch roads is 1: 4: 1: 4, the frame allocation range corresponding to each branch road is divided at a ratio of 1: 4: 1: 4. By determining the frame allocation range in accordance with the traffic volume of each branch road, it is possible to increase the effect of reducing the frequency with which the traveling information is transmitted from a plurality of vehicles over time.

(9) Application to vehicle group communication system The in-vehicle communication system according to the first to fourth embodiments of the present invention can be applied to a vehicle group communication system. The vehicle group communication system is a system that performs vehicle-to-vehicle communication based on a communication protocol defined between vehicle-mounted communication devices of a plurality of vehicles that form a vehicle group. Here, the vehicle group refers to a group of vehicles that travel in the same direction with a distance to a neighboring other vehicle being a predetermined distance or less. Each in-vehicle communication device transmits the travel information of the host vehicle in a time zone that does not overlap with a time zone in which other in-vehicle communication devices belonging to the same vehicle group transmit travel information. As vehicle group communication systems, RR-ALOHA, modified RR-ALOHA, and the like have been studied.

  The configuration of the broadcast signal 54 used in the vehicle group communication system is shown in FIG. The broadcast signal 54 is divided into a plurality of frames 56. The frame 56 is further divided into a plurality of slots 58. In the vehicle group communication system, each in-vehicle communication device selects a transmission slot so that transmission time zones do not overlap between in-vehicle communication devices belonging to the same vehicle group. This process is performed by a slot selection process based on a communication protocol defined by the vehicle group communication system.

  However, in the communication protocol used in the vehicle group communication system, slot selection processing is not performed between a plurality of in-vehicle communication devices belonging to different vehicle groups. Therefore, when the vehicle groups approach each other, there is a possibility that the traveling information of the host vehicle is transmitted in a time zone that overlaps with the time zone in which other in-vehicle communication devices belonging to the other vehicle group transmit the traveling information. In this case, since the in-vehicle communication device that receives a plurality of pieces of traveling information in a superimposed manner does not acquire any information, there arises a problem that the amount of information transmission between vehicles decreases.

  Therefore, in the present application mode, as in the first to fourth embodiments, processing for specifying the frame allocation range is executed according to the traveling state of the vehicle equipped with the in-vehicle communication device. Each in-vehicle communication device executes slot selection processing for slots included in the specified frame allocation range. For example, when the frame allocation range 60 is specified as shown in FIG. 11, the slot selection process is executed for the hatched slot 58 in FIG.

  According to such a process, it is possible to reduce the frequency of transmitting the traveling information of the host vehicle in a time zone that overlaps with the time zone in which another in-vehicle communication device belonging to the other vehicle group transmits the traveling information. Therefore, it is possible to improve the phenomenon that the amount of information transmission between vehicles due to the vehicle groups approaching each other decreases.

It is a figure which shows the structure of the vehicle-mounted communication apparatus which concerns on 1st Embodiment. It is a figure which shows the structure of a broadcast signal. It is a figure explaining the process example by 1st Embodiment. It is a figure explaining another example of an azimuth angle scale. It is a figure which shows the structure of the vehicle-mounted communication apparatus which concerns on 2nd and 3rd embodiment. It is a figure which shows the example of the frame allocation range which concerns on an intersection mode frame division | segmentation system. It is a figure which shows the structure of the vehicle-mounted communication apparatus which concerns on 4th Embodiment. It is a figure which shows the example of an intersection determination area | region. It is a figure which shows another example of an intersection area | region. It is a figure explaining the process example which concerns on 4th Embodiment. It is a figure which shows the structure of the broadcast signal which concerns on a vehicle group communication system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Information processing part, 12 Transmission part, 14 Communication antenna, 16 Reception part, 18 Positioning antenna, 20 Positioning device, 22 Speed vector calculation part, 24 Vehicle control part, 26 Map information storage part, 28 Intersection flag storage part, 30, 54 broadcast signal, 32, 56 frames, 34 azimuth scale, 36, 38, 44, 46, 50, 52 road, 40 buildings, 42A to 42I vehicles, 48 intersection determination area, 58 slots, 60 frame allocation range.

Claims (3)

A frame generation unit for generating a frame including transmission target information;
A transmitter for transmitting the frame;
An in-vehicle communication device comprising:
A status acquisition unit that acquires travel status information of the mounted vehicle;
A frame range specifying unit for specifying a frame use range based on the acquisition information by the situation acquisition unit;
With
The frame generation unit
A vehicle-mounted communication device that generates a frame including the transmission target information in a frame use range specified by the frame range specifying unit. The in-vehicle communication device according to claim 1,
The frame range designation unit
Frame dividing means for dividing the frame according to the environment in which the vehicle is traveling;
Association means for associating the acquisition information by the situation acquisition unit with the frame classification;
With
An in-vehicle communication device that specifies a frame use range based on association by the association means. The in-vehicle communication device according to any one of claims 1 and 2,
The in-vehicle communication apparatus characterized in that the acquisition information by the situation acquisition unit is information indicating a traveling direction direction of the mounted vehicle.

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