JP5754638B2 - Communication system, in-vehicle communication device, and roadside communication device - Google Patents

Description

  The present invention relates to a communication system including an in-vehicle communication device and a roadside communication device, and an in-vehicle communication device and a roadside communication device constituting the system.

  As the communication system, signals transmitted from the in-vehicle communication device are set to different timings by setting the timing at which the in-vehicle communication device transmits a signal according to the distance (radio wave intensity) from the roadside communication device to the in-vehicle communication device. A configuration that does not easily collide is known (for example, see Patent Document 1).

JP 2010-041145 A

  By the way, in wireless communication such as wireless LAN, communication control is performed so that signals transmitted from each communication device do not collide. As the communication control, for example, there is a CSMA / CA method.

  In the above communication system, in order to perform communication control so that signals transmitted from each in-vehicle communication device do not collide, it is necessary for each in-vehicle communication device to grasp that a signal is transmitted from another communication device. There is. This is because the in-vehicle communication device performs control so that signals do not collide by deferring transmission of signals from itself when signals are transmitted from other in-vehicle communication devices.

  However, in the above communication system, the timing at which the in-vehicle communication device transmits data is set to a different timing according to the distance from the road-side communication device to the in-vehicle communication device, so that in-vehicle communication devices located at the same distance from the road-side communication device. If they can grasp each other's signal transmission, good communication can be performed without collision of signals (see FIG. 19 (a)). There is a possibility that the communication device transmits signals at the same timing and the communication does not occur due to the collision of signals (see FIG. 19B).

  Accordingly, in view of such problems, a communication system including an in-vehicle communication device and a roadside communication device can perform good communication even when there are shielding objects such as buildings. Is an object of the present invention.

  In the communication system of the first configuration configured to achieve such an object, the roadside communication device supports different data transmission timings for each divided area obtained by dividing its own communicable area into a plurality according to the direction. Timing data transmission means for transmitting the attached timing data to the communicable region, and the in-vehicle communication device receives data transmitted from the in-vehicle communication device or roadside communication device mounted on another vehicle, and When timing data is included, timing data extracting means for extracting timing data, position information acquiring means for acquiring position specifying information for specifying the position of the own vehicle, and the position of the own vehicle specified by the position specifying information Is one of a plurality of divided regions, and the position of the host vehicle is determined based on the timing data. The transmission timing associated with those split region, and a timing setting means for setting a timing to transmit the vehicle data is data to be transmitted from itself.

  According to such a communication system, since the transmission timing from the in-vehicle communication device is set according to the direction, if each vehicle transmits the vehicle data at the timing set by the timing setting means, the vehicle data transmitted from a different direction Can be prevented from interfering with each other. Therefore, good communication can be performed even when a shield such as a building exists.

  The direction in the present invention is a concept including a mere direction, and indicates an direction based on the intersection center, a direction based on a roadside communication device (such as an antenna portion), and the like. Also, the location information acquisition means is by a GPS receiver, by a gyroscope or an inertial traveling device, by a beacon or responder installed on the ground, by radio wave induction from ground facilities, by recognition of surrounding landscape images The position specifying information obtained by any of the above may be acquired.

  By the way, in the communication system, as in the second configuration, in the timing data, a plurality of roads connected to a specific intersection may be divided into a plurality of groups, and a divided region may be set for each group. .

According to such a communication system, different transmission timings can be set for each group.
In addition, in the communication system, as in the third configuration, in the timing data, a divided region may be set for each road connected to the intersection.

  According to such a communication system, in view of the fact that there is almost no shielding on each road connected to the intersection, a divided area is set for each road connected to the intersection. Therefore, good communication can be surely performed.

  Further, in the communication system, as in the fourth configuration, in the timing data, a plurality of roads are allocated to a plurality of groups according to the position of the shielding object that shields communication between the in-vehicle communication devices, and each of these groups. A divided area may be set in the area.

  According to such a communication system, the divided areas are set according to the position of the shielding object so that the in-vehicle communication apparatuses having the possibility of transmitting data at the same time do not become in a situation where the communication state cannot be grasped by the shielding object. be able to.

  In this case, it is only necessary to set different roads between the roads connected to the intersection and sandwiching the shield. Specifically, for example, as in the fifth configuration, in the timing data, opposing roads connected to the intersection may be set in the same group.

  According to such a communication system, the opposite roads connected to the intersection are set in the same group in view of the fact that the opposite roads connected to the intersection have a good view and there is often no shielding. Therefore, the in-vehicle communication device can satisfactorily grasp the communication state of other in-vehicle communication devices belonging to the same group.

  Alternatively, in the communication system, as in the sixth configuration, in the timing data, among the plurality of roads connected to the intersection, a plurality of adjacent roads where no obstacle exists between the roads is set in the same group. May be.

According to such a communication system, if there is no obstacle between the roads, even adjacent roads can be set in the same group, and communication can be performed satisfactorily.
Further, in the communication system, as in the seventh configuration, in the timing data, further subdivided divided areas may be set according to the distance to the roadside communication device or a specific intersection.

According to such a communication system, since the divided areas are further subdivided, data collision can be further suppressed.
Further, in the communication system, as in the eighth configuration, in the timing data, the transmission period for transmitting the vehicle data as the risk level indicating the probability of occurrence of a traffic accident for each divided region increases. The transmission timing for each divided region may be associated so that the ratio increases.

  According to such a communication system, since the transmission period for transmitting the vehicle data transmitted from the high-risk division area is set longer than the transmission period of the low-division division area, the danger level is It is possible to easily prevent collision between vehicle data transmitted from a high divided area. Moreover, even if the collision between the vehicle data occurs, the transmission period is set to be long, so that there is a high possibility that retransmission will be completed within the transmission period. Therefore, it can contribute more safely.

  Further, in the communication system, as in the ninth configuration, the roadside communication apparatus sets the transmission timing according to the divided area risk level acquisition means for acquiring the risk level for each divided area and the acquired risk level. Timing data generating means for generating timing data, and the timing data transmitting means may transmit the timing data generated by the timing data generating means.

  According to such a communication system, it is possible to set the transmission timing corresponding to the changing risk. Here, the risk level is, for example, a separate configuration that detects the position and behavior of the vehicle using a sensor that detects the position and traveling speed of the vehicle, and the first party (accidents in the accident). It is conceivable to set a value corresponding to the number of vehicles that can be the heaviest), the magnitude of the traveling speed of the vehicle traveling in each divided area, and the like.

  Further, in the communication system, as in the tenth configuration, the adjacent risk level for acquiring the adjacent risk level indicating the risk level in the communicable region by the other roadside communication device adjacent to the communicable region of the roadside communication device. You may provide the acquisition means and the risk level estimation means which estimates the risk level for every division area based on the adjacent risk level.

According to such a communication system, the risk in the communicable area can be estimated using the adjacent risk.
Moreover, in the said communication system, like the 11th structure, the communication between vehicle-mounted communication apparatuses may be implemented by a CSMA / CA system.

According to such a communication system, communication can be performed satisfactorily without collision of signals from the in-vehicle communication devices.
Further, in the communication system, as in the twelfth configuration, the timing data includes information related to the effective range indicating the range in which the timing data is effective, and the in-vehicle communication device has its own position valid. A transmission prohibiting means for prohibiting the transmission of vehicle data based on the timing data when outside the range may be provided.

  According to such a communication system, the range in which the timing data is valid can be set. Therefore, even when the plurality of roadside communication devices are arranged at a relatively short distance and the in-vehicle communication device can communicate with the plurality of roadside communication devices, at the transmission timing specified by any roadside communication device. Since communication can be performed, the frequency of data collision can be reduced.

  Moreover, as a structure for achieving the said objective, it is good also as the vehicle-mounted communication apparatus (13th structure) and roadside communication apparatus (14th structure) which comprise the said system. In such an in-vehicle communication device and a roadside communication device, the above system can be configured, and therefore, when the above system is configured, the same effect as the above system can be enjoyed.

It is a block diagram which shows schematic structure of the communication system of 1st Embodiment. It is the flowchart (a) which shows a roadside packet transmission process, and explanatory drawing (b) which shows the data structure of alerting | reporting information. It is the block diagram (a) which shows a position and transmission period information table, and explanatory drawing (b) which shows a frame structure. It is a bird's-eye view which shows the division method of an area in a 1st embodiment. It is a flowchart which shows the vehicle side packet reception process of 1st Embodiment. It is the flowchart (a) which shows a vehicle side packet transmission process, and the flowchart (b) which shows a transmission start time determination process. It is the bird's-eye view (a) which shows the division method of an area in the modification (the 1) of 1st Embodiment, and the block diagram (b) which shows a position and transmission period information table. It is the bird's-eye view (a) which shows the division method of an area in the modification (the 2) of 1st Embodiment, and the block diagram (b) which shows a position and transmission period information table. It is the bird's-eye view (a) which shows the division method of an area in the modification (the 3) of 1st Embodiment, and the block diagram (b) which shows a position and transmission period information table. It is a bird's-eye view which shows schematic structure of the communication system of 2nd Embodiment. It is the flowchart (a) which shows a transmission period information setting process, and the graph (b) which shows the setting method of a risk level. It is explanatory drawing (a) which shows the relationship between an area and a risk, and the graph (b) which shows the example of a setting of the transmission period according to the risk. It is a bird's-eye view which shows the division method of an area in the modification (the 1) of 2nd Embodiment. It is a bird's-eye view which shows the example of detection of a danger in the modification (the 1) of 2nd Embodiment. It is explanatory drawing which shows the relationship between an area and a risk (average driving speed, traffic volume). It is a bird's-eye view which shows the division method of an area in the modification (the 2) of 2nd Embodiment. It is a flowchart which shows a roadside packet reception process. It is the flowchart (a) which shows a vehicle side packet reception process in the modification of 2nd Embodiment, and the block diagram (b) which shows a position and transmission period information table. It is a bird's-eye view which shows the outline | summary of the communication system of a conventional structure.

  Embodiments according to the present invention will be described below with reference to the drawings. The embodiment of the present invention is not limited to the above-described embodiment, and can take various forms as long as they belong to the technical scope of the present invention.

[First Embodiment]
[Configuration of First Embodiment]
FIG. 1A is a block diagram showing a schematic configuration of a communication system 1 to which the present invention is applied. FIG. 1B is a block diagram showing a schematic configuration of the ground facility 20 (roadside communication device) constituting the communication system 1.

  In the communication system 1, an in-vehicle communication device 10 (10a, 10b, etc.) mounted on each of a plurality of vehicles traveling on a road and a ground facility 20 arranged on the road side can wirelessly communicate with each other. In particular, in the communication system 1 according to the present embodiment, the ground facility 20 transmits notification information that designates a transmission timing for transmitting data to the in-vehicle communication device 10, and the in-vehicle communication device 10 transmits at a transmission timing based on the notification information. Send data. Here, it is assumed that the antenna for transmitting and receiving radio waves in the ground facility 20 is arranged at the center of the intersection with good visibility.

  As shown in FIG. 1A, the in-vehicle communication device 10 includes a communication controller 11, a position grasping device 12, and a transceiver 13. The position grasping device 12 is configured to grasp the absolute position of the host vehicle, and is configured as a GPS receiver, for example. The position grasping device 12 is configured as a device using a gyroscope or an inertial traveling device, a device using a beacon or a responder installed on the ground, a device using radio wave guidance from ground equipment, or a device that recognizes surrounding landscape images. It may be configured as any combination thereof.

  The transceiver 13 is configured as a well-known communication module, and performs communication with other in-vehicle communication devices 10 and communication with the ground facility 20 in accordance with instructions from the communication controller 11.

  The communication controller 11 is configured as a well-known microcomputer including a CPU, a ROM, a RAM, and the like, and the CPU performs processing according to a program stored in the ROM or the like. In particular, the communication controller 11 of the present embodiment includes a vehicle that includes the position of the host vehicle, the traveling speed, and the like according to the position of the host vehicle detected by the position grasping device 12 and various signals input via the transceiver 13. A process (such as a vehicle-side packet transmission process or a vehicle-side packet reception process described later) for transmitting information to another in-vehicle communication device 10 or the ground facility 20 is performed.

  Next, as shown in FIG. 1B, the ground facility 20 includes a control unit 21, a position condition / transmission period information storage unit 22, and a signal transmission / reception unit 23. The position condition / transmission period information storage unit 22 stores a position / transmission period information table to be described later.

The signal transmission / reception unit 23 has the same configuration as the transceiver 13 of the in-vehicle communication device 10 and performs communication with each in-vehicle communication device 10.
The control unit 21 is configured as a well-known microcomputer including a CPU, a ROM, a RAM, and the like, and the CPU performs processing according to a program stored in the ROM or the like. In particular, the control unit 21 generates notification information indicating the timing at which each in-vehicle communication device 10 transmits data, and transmits a signal including this notification information to each in-vehicle communication device 10.

[Process of First Embodiment]
FIG. 2A is a flowchart showing roadside packet transmission processing executed by the control unit 21 of the ground facility 20. The roadside packet transmission process is a process that is repeatedly activated, and is a process that generates and transmits broadcast information.

  Specifically, as shown in FIG. 2A, first, the presence or absence of a packet transmission request by the ground facility 20 is determined (S110). Note that the notification information is transmitted within a predetermined period (for example, 100 ms). If there is no packet transmission request (S110: NO), the process of S110 is repeated.

  If there is a packet transmission request (S110: YES), the position / transmission period information table is read from the position condition / transmission period information storage unit 22 (S120: timing data generating means), and notification information is generated (S130: timing). Data generation means).

  Here, in the notification information, as shown in FIG. 2B, the ground equipment ID that is information for specifying the source ground equipment 20 and the ground for specifying the position of the source ground equipment 20 are shown. Equipment location information and a location / transmission period information table are included. In the position / transmission period information table, a plurality of roads connected to a specific intersection (intersection where the ground facility 20 is arranged) is divided into a plurality of groups, and an area (divided region) is set for each group. Different transmission periods are set for each area.

The position / transmission period information table, for example, as shown in FIG. 3A, area IDs (1 to G) which are information for specifying each area, position conditions (here, each road connected to the intersection is individually For example, the range of the azimuth with reference to the center of the intersection, etc. X _{1 to} X _G ) and transmission period information (T _{1 to} T _G ) are included. In particular, in this embodiment, an area, a position condition, and a transmission period are set for each road connected to the intersection.

  For example, in the case of a crossroad in which roads are connected to the intersection from four directions, an area, a position condition, and a transmission period are set as G = 4 (see FIG. 4A). Further, in the case of a T-junction where roads are connected to the intersection from three directions, an area, a position condition, and a transmission period are set as G = 3 (see FIG. 4B).

In this embodiment, communication between devices is performed by the CSMA / CA method defined by IEEE 802.11, and the transmission start timing t _g in the area g (g = 1 to G) is expressed by the following equation (1). Given.

Note that SIFS indicates the shortest frame interval defined by IEEE 802.11.
Then, transmission period information Tg (transmission start timing and transmission end timing) in each area is set with transmission start timing t _{g + 1} in area _{g + 1} as transmission end timing in area g.

As shown in FIG. 3B, the time-division frame length T in one cycle includes the road-to-vehicle communication period T _I (period during which the ground facility 20 transmits data) and the vehicle-to-vehicle communication period T _v (in-vehicle communication device 10 Is a period during which data is transmitted. Since the road-to-vehicle communication period T _I is set before the vehicle-to-vehicle communication period T _v , the transmission period information (T _{1 to} T _G ) is set based on the timing delayed by the road-to-vehicle communication period T _I. Is done.

  Subsequently, the notification information is packet-transmitted (S140: timing data transmission means). The notification information may be transmitted as independent information, or may be transmitted as information added when the ground facility 20 distributes information such as traffic information to the in-vehicle communication device 10.

  Then, it is determined whether or not communication for transmitting packets from the ground facility 20 has been completed (S150). If the communication has not ended (S150: NO), the process returns to S140. If the communication is completed (S150: YES), the roadside packet transmission process is terminated.

Next, the process by the vehicle-mounted communication apparatus 10 corresponding to the notification information received from the ground facility 20 will be described with reference to FIG. FIG. 5 is a flowchart showing the vehicle-side packet reception process.
The vehicle-side packet reception process is a process that is repeatedly activated and is a process for registering the received notification information. In the vehicle-side packet reception process, first, the presence / absence of a received packet is determined (S210). If there is no received packet (S210: NO), the process of S210 is repeated.

  If there is a received packet (S210: YES), it is determined whether broadcast information is included in the received packet (S220). If the notification information is included (S220: YES), the notification information is registered in a memory such as a RAM (S240), and the process proceeds to S250.

  If broadcast information is not included (S220: NO), the process immediately proceeds to S250, and received data other than the broadcast information is processed (S250). In this processing, for example, various information such as traffic information transmitted from the ground facility 20 and vehicle information including information on the position and speed of other vehicles transmitted from the other in-vehicle communication device 10 are arranged for each information. And processing for recording.

  Subsequently, it is determined whether or not the communication for receiving data is completed (S260). If the communication has not ended (S260: NO), the process returns to S250. If communication has ended (S260: YES), the vehicle-side packet reception process ends.

  Next, processing when data is transmitted from the in-vehicle communication device 10 will be described with reference to FIG. FIG. 6A is a flowchart showing the vehicle-side packet transmission process, and FIG. 6B is a flowchart showing the transmission start time determination process in the vehicle-side packet transmission process.

  The vehicle-side packet transmission process is a process that is started when the power of the in-vehicle communication device 10 is turned on, and is repeatedly performed thereafter. First, it is determined whether there is a packet transmission request (S310). If there is no packet transmission request (S310: NO), the process of S310 is repeated.

  If there is a packet transmission request (S310: YES), it is determined whether or not the notification information from the ground facility 20 is registered in a memory such as a RAM (S320: timing data extraction means). If the broadcast information is not registered (S320: NO), the process immediately proceeds to S340 and packet transmission is performed at an arbitrary timing.

  If broadcast information is registered (S320: YES), a transmission start time determination process to be described later is performed to set a transmission start time based on the broadcast information (S330), and at the set transmission start time. Then, packet transmission is performed (S340).

  And it is determined whether communication which performs packet transmission from the vehicle-mounted communication apparatus 10 was complete | finished (S350). If the communication has not ended (S350: NO), the process returns to S340. Moreover, if communication is complete | finished (S350: YES), a vehicle side packet transmission process will be complete | finished.

In the vehicle side packet transmission process, when the notification information from the ground facility 20 is not registered (S320: NO), the process may return to S310.
Next, in the transmission start time determination process, as shown in FIG. 6B, the own position information is acquired from the position grasping device 12 (S410: position information acquisition means). Then, the received notification information is read (S420: timing data extracting means), and the existence area of the own vehicle is specified from the position information of the own vehicle and the position condition included in the notification information (S430: timing setting means). For example, when the position information of the host vehicle and the ground equipment is latitude and longitude, and the position condition included in the notification information is a range of azimuth with the center of the intersection as a reference, the ground based on the latitude and longitude of the host vehicle and the ground equipment The direction of the host vehicle with respect to the facility is specified, and the area associated with the position condition including the specified direction is specified as the presence area of the host vehicle.

  Further, the transmission period information (transmission available time zone) corresponding to the existing area is specified (S440: timing setting means), and the transmission start time (the time from the current time to the start of the transmission period) is calculated (S450: timing setting). means). When such processing ends, the transmission start time determination processing ends.

[Effects of First Embodiment]
In the communication system 1 described in detail above, the control unit 21 of the ground facility 20 associates the transmission timing of different data with each area obtained by dividing its own communicable area into a plurality according to the direction. Is transmitted to the communicable area. And the communication controller 11 of the vehicle-mounted communication apparatus 10 receives the data transmitted from the vehicle-mounted communication apparatus mounted in the other vehicle or the ground facility 20, and when the information includes the notification information, extracts the notification information. The position specifying information for specifying the position of the host vehicle is acquired. Then, it is detected which of the plurality of areas corresponds to the position of the host vehicle specified by the position specifying information, and based on the notification information, the position of the host vehicle is associated with the corresponding area. The timing is set as a timing for transmitting vehicle data that is data to be transmitted from itself.

  According to such a communication system 1, since the transmission timing from the in-vehicle communication device 10 is set according to the direction, if each vehicle transmits vehicle data at the set timing, the vehicle data transmitted from different directions are mutually It is possible to prevent interference. Therefore, good communication can be performed even when a shield such as a building exists.

  Further, in the communication system 1, a plurality of roads connected to a specific intersection are assigned to a plurality of groups, and an area is set for each group. According to such a communication system 1, different transmission timings can be set for each group.

  In the communication information in the communication system 1, an area is set for each road connected to the intersection. According to such a communication system 1, in view of the fact that there is almost no shielding on each road connected to the intersection, an area is set for each road connected to the intersection. Therefore, good communication can be surely performed.

  Moreover, in the said communication system 1, the communication between the vehicle-mounted communication apparatuses 10 is implemented by the CSMA / CA system. According to such a communication system 1, communication can be performed satisfactorily without collision of signals from the in-vehicle communication devices 10.

[Modification of First Embodiment]
The communication system in the communication system 1 of the first embodiment is the CSMA / CA system. However, the communication system is not limited to the CSMA / CA system. A method etc. can be adopted. In the first embodiment, a different area (group) is assigned to each road connected to the intersection, but roads connected to the intersection may be assigned to the same area as several sets.

  For example, as shown to Fig.7 (a), it is good to set the opposing road connected to an intersection in the same area. In the position / transmission period information table in this case, as shown in FIG. 7B, roads belonging to group A and roads belonging to group C facing this road are set in area (area ID) 1, A road belonging to group B and a road belonging to group D opposite to this road are set in area (area ID) 2.

  According to such a communication system 1, in view of the fact that the roads facing each other connected to the intersection have good visibility and there are often no obstructions, the roads facing each other are set to the same group. Therefore, the in-vehicle communication device 10 can grasp the communication state of other in-vehicle communication devices 10 belonging to the same group.

  Moreover, as shown to Fig.8 (a), depending on the position of an obstruction to the building etc. which shield the communication between vehicle-mounted communication apparatuses 10, several adjacent roads among several roads connected to an intersection are the same area. May be set. However, among a plurality of roads connected to the intersection, a plurality of adjacent roads where no obstacle exists between the roads is set in the same area.

  In the position / transmission period information table in this case, as shown in FIG. 8B, the road belonging to group A and the road belonging to group B adjacent to this road are set in area (area ID) 1, A road belonging to group C and a road belonging to group D adjacent to this road are set in area (area ID) 2.

  According to such a communication system 1, according to the position of the shielding object, the in-vehicle communication devices 10 having the possibility of transmitting data at the same time do not become in a situation where the mutual communication state cannot be grasped by the shielding object such as a building. An area can be set. And if there is no obstruction between each road, even if it is an adjacent road, it can set to the same group and can communicate favorably.

  Further, in the communication system 1, as shown in FIG. 9A, a further subdivided area may be set according to the distance to the ground facility 20 or a specific intersection. In the position / transmission period information table in this case, as shown in FIG. 9B, roads belonging to each group are divided by a threshold value Dth, and an area is set for each divided area.

According to such a communication system 1, since the area is further subdivided, data collision can be further suppressed.
[Second Embodiment]
Next, another type of communication system will be described. This embodiment (second embodiment) In the following embodiment, only the parts different from the communication system 1 of the first embodiment will be described in detail, and the same reference numerals will be used for the same parts as the communication system 1 of the first embodiment. The description is omitted.

  FIG. 10 is a bird's-eye view of an intersection showing an outline of the communication system 2 of the second embodiment. In the communication system according to the second embodiment, the ground facility 20 includes the accident information DB 25. In the accident information DB 25, a risk level R is associated with each area.

  In the ground equipment 20 (CPU of the control unit 21) of the second embodiment, the transmission period information setting process shown in FIG. The transmission period information setting process is performed at an arbitrary timing, for example, every time the ground facility 20 transmits a packet or the risk level is updated.

  In the transmission period information setting process, as shown in FIG. 11A, first, the risk set for each area is acquired from the accident information DB 25 (S510: divided region risk acquisition means). Here, as shown in FIG. 11B, the risk level R is set so that the risk level R increases stepwise as the number of traffic accidents increases.

  The risk R information may be information as a fixed value recorded in the accident information DB 25 for each intersection, may be changed for each time zone, or the latest information may be updated by an external command. May be. In this way, as shown in FIG. 12A, a value corresponding to the number of traffic accidents is set as the risk R of the area g.

Subsequently, a transmission period is calculated (S520: timing data generation means, risk level estimation means). In this process, the vehicle-to-vehicle communication period _Tv is divided according to the risk ratio.

  For example, as shown in FIG. 12 (a), assuming that the risk levels of areas 1 to 4 are 3, 1, 2, and 1 in order, as shown in FIG. Are in the order of 3: 1: 2: 1. Subsequently, the set transmission period is stored in a memory such as a RAM (S530: timing data generating means), and the transmission period information setting process is terminated.

  In the communication system 2 as described above, the transmission timing for each area is set such that the ratio of the transmission period for transmitting the vehicle data increases as the degree of risk representing the probability of occurrence of a traffic accident increases for each area. Are associated.

  According to such a communication system 2, the transmission period for transmitting the vehicle data transmitted from the high risk area is set longer than the transmission period of the low risk area, so the risk level is high. It is possible to easily prevent collision between vehicle data transmitted from the area. Moreover, even if the collision between the vehicle data occurs, the transmission period is set to be long, so that there is a high possibility that retransmission will be completed within the transmission period. Therefore, it can contribute more safely.

[Modification of Second Embodiment]
When using the degree of risk as in the second embodiment, as shown in FIG. 13, vehicle detectors 24a to 24d that detect the presence and number of vehicles in each area are provided in the area before the intersection. The risk may be set dynamically using the detection results of the vehicle detectors 24a to 24d.

  In this case, the risk level and the inter-vehicle communication period are set, for example, according to the following procedure.

The first party refers to the most negligent vehicle or the like (including bicycles and pedestrians) involved in the traffic accident first when a traffic accident occurs.
For example, in the examples of FIGS. 14A to 14C, the number of vehicles that may become the first party is assumed assuming an intersection between a priority road with a wide road and a non-priority road with a narrow road. Each is detected. In the example shown in FIG. 14A, when it is assumed that an encounter crash occurs, the first party is located in area 2 (g = 2) and the second party is located in area 1 (g ′ = 1). It shows that.

  In the example shown in FIG. 14B, when it is assumed that a right turn collision accident (right side accident) occurs, the first party is located in area 3 (g = 3), and the second party is in area 1 ( It is located at g ′ = 1). Furthermore, in the example shown in FIG. 13C, when it is assumed that a left turn collision accident (a rear-end collision) occurs, both the first party and the second party are located in area 3 (g = 3).

Next, as an example of dynamically setting the risk level, as shown in FIG. 15A, an average speed of a vehicle traveling in each area may be detected, and this average speed may be set as the risk level. . In this case, it is also possible to split the inter-vehicle communication period T _v according to the average speed.

Instead of the average speed, the degree of danger may be set according to the maximum value of the vehicle speed traveling in each area, the number of vehicles (the number of vehicles having a speed equal to or higher than a predetermined threshold), and the like. In order to prevent the transmission period for each area from becoming extremely short, a lower limit value may be provided for the transmission period information (T _{1 to} T _G ).

  Further, the ground facility 20 may exchange information about the risk level with the adjacent ground facility 20 and use it when setting the risk level. Specifically, as shown in FIG. 16, vehicle detectors are provided in the respective areas of adjacent intersections, and the risk level is dynamically set using the detection results of the vehicle detectors. Good.

  In the case of the area arrangement shown in FIG. 16, the area 3 at the intersection at the top of the drawing and the area 1 ′ at the intersection at the bottom of the drawing are connected roads, so if one traffic volume is known, the other traffic volume can be predicted. . In such a case, for example, during roadside packet transmission processing, information on the degree of risk detected by itself as notification information is transmitted, and information on the degree of risk transmitted from other ground facilities is received. What is necessary is just to implement a roadside packet reception process as shown in FIG.

  As the risk level information, for example, traffic volume information of each area at each intersection as shown in FIGS. 15B and 15C is exchanged. In the roadside packet reception process, as shown in FIG. 17, first, the presence / absence of a received packet is determined (S610). If there is no received packet (S610: NO), the process of S610 is repeated.

  If there is a received packet (S610: YES), the received data is processed (S660: adjacent risk acquisition means). In this process, for example, a process of recording traffic volume information transmitted from another ground facility 20 in a memory such as a RAM is performed.

  Subsequently, it is determined whether or not the communication for receiving data is completed (S670). If the communication has not ended (S670: NO), the process returns to S610. If the communication is completed (S670: YES), the roadside packet reception process is terminated.

  In such a configuration, when creating the notification information (S130), the inter-vehicle communication period in each area is set as follows.

  In other words, it is predicted that the risk will increase in the future by adopting the higher risk of the risk at the intersection to which it belongs and the risk at the adjacent intersection. Can control communication.

  Next, in the communication system, the broadcast information includes information related to an effective range indicating the range in which the broadcast information is valid (position restriction information illustrated in FIG. 18B), and the communication controller of the in-vehicle communication device 10 11 may prohibit the transmission of the vehicle data based on the notification information when the position of the vehicle is outside the effective range. The position restriction information includes information indicating the range of the effective area in which the notification information is valid (for example, a distance from an intersection).

  In order to specifically realize such a configuration, a vehicle-side packet reception process as shown in FIG. In the vehicle side packet reception process shown in FIG. 18A, the process of S230 is performed between S220 and S240 in the above-described vehicle side packet reception process. That is, when notification information is included in the received packet (S220: YES), it is determined whether or not the position of the host vehicle is within the effective region set by the position restriction information included in the notification information. (S230: transmission prohibition means).

If it is within the range of the effective area (S230: YES), the notification information is registered (S240). If it is out of the valid area (S230: NO), the process returns to S210.
According to such a communication system 1, it is possible to set a range in which broadcast information is valid. Therefore, even when the plurality of ground facilities 20 are arranged at a relatively short distance and the in-vehicle communication device 10 can communicate with the plurality of ground facilities 20, the transmission timing specified by any of the ground facilities 20 Thus, the frequency of data collision can be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Communication system, 2 ... Communication system, 10 ... In-vehicle communication apparatus, 11 ... Communication controller, 12 ... Position grasping device, 13 ... Transmitter / receiver, 20 ... Ground equipment, 21 ... Control part, 22 ... Position condition and transmission period information Storage unit, 23 ... signal transmission / reception unit, 24 ... vehicle detector, 25 ... accident information DB.

Claims (11)

A communication system comprising: an in-vehicle communication device mounted on a vehicle; and a road side communication device arranged on a road side and capable of communicating with the in-vehicle communication device,
The roadside communication device is
Timing data transmitting means for transmitting to the communicable region timing data that associates transmission timings of different data for each divided region obtained by dividing the communicable region into a plurality according to the direction,
The in-vehicle communication device is
Timing data extraction means for receiving data transmitted from an in-vehicle communication device mounted on another vehicle or the roadside communication device, and extracting the timing data when the data includes the timing data;
Position information acquisition means for acquiring position specifying information for specifying the position of the host vehicle;
It is detected which of the plurality of divided areas corresponds to the position of the own vehicle specified by the position specifying information, and the position of the own vehicle is associated with the corresponding divided area based on the timing data. Timing setting means for setting the transmission timing as a timing when transmitting vehicle data that is data to be transmitted from itself;
With
The timing data distributes a plurality of roads connected to a specific intersection according to the position of a shielding object that shields communication between the in-vehicle communication devices into a plurality of groups, and the divided region is set for each group. communication system characterized by the fact that there. The communication system according to claim 1 ,
In the timing data, a facing road connected to the intersection is set in the same group. The communication system according to claim 1 ,
In the timing data, among a plurality of roads connected to the intersection, a plurality of adjacent roads where no obstacle exists between the roads is set in the same group. In the communication system according to any one of claims 1 to 3 ,
In the timing data, a further subdivided divided area is set according to a distance to the roadside communication device or a specific intersection. In the communication system according to any one of claims 1 to 4 ,
The timing data corresponds to the transmission timing for each divided region so that the ratio of the transmission period for transmitting vehicle data increases as the risk level indicating the probability of occurrence of a traffic accident increases for each divided region. A communication system characterized by being attached. The communication system according to claim 5 , wherein
The roadside communication device is
A divided area risk level acquisition means for acquiring a risk level for each of the divided areas;
Timing data generating means for generating timing data in which the transmission timing is set according to the obtained risk level;
With
The communication system characterized in that the timing data transmission means transmits the timing data generated by the timing data generation means. The communication system according to claim 5 or 6 ,
An adjacent risk level acquisition means for acquiring an adjacent risk level indicating a risk level in a communicable area by another road side communication apparatus adjacent to the communicable area of the roadside communication device;
A risk estimation means for estimating a risk for each of the divided areas based on the adjacent risk;
A communication system comprising: The communication system according to any one of claims 1 to 7 ,
The communication between the in-vehicle communication devices is performed by a CSMA / CA method. In the communication system according to any one of claims 1 to 8 ,
The timing data includes information about an effective range indicating a range in which the timing data is effective,
The communication system comprising: a transmission prohibiting unit that prohibits transmission of vehicle data based on the timing data when the position of the vehicle-mounted communication device is outside the effective range. A roadside communication device arranged on the roadside for transmitting to the communicable area timing data in which different data transmission timings are associated with each divided area obtained by dividing the communicable area into a plurality of areas according to the direction; An in-vehicle communication device mounted on a vehicle capable of communicating with
The in-vehicle communication device is configured as an in-vehicle communication device constituting the communication system according to any one of claims 1 to 9 . A roadside communication device arranged on the roadside capable of communicating with an in-vehicle communication device that transmits data at a transmission timing set for its own position,
The roadside communication apparatus, according to claim 1 roadside communication apparatus characterized by being configured as a roadside communication device constituting the communication system according to any one of claims 9.