JP4251036B2 - Roadside communication system - Google Patents

Description

  The present invention relates to a roadside communication system capable of road-to-vehicle communication between an in-vehicle device mounted on an automobile and a roadside device installed on a road or a parking lot, for example.

  In recent years, many services such as toll collection services such as parking lots and gas stations and services for providing necessary information have been studied using road-to-vehicle wireless communication used in ETC (automatic toll collection system) and the like. Yes.

  By the way, when such a service is performed, a plurality of roadside devices are installed at predetermined intervals, and a wide communication area defined in advance as a whole is covered by these roadside devices, and vehicles or the like are included in the communication area. It is conceivable to receive the service when entering.

  In such a case, even if a certain in-vehicle device becomes communicable with a roadside device, if a vehicle equipped with the in-vehicle device moves, the communication state with the roadside device gradually deteriorates and communication is impossible. Therefore, it is necessary to smoothly switch to another roadside device.

A technique for automatically and smoothly switching to another roadside device to continue communication when the vehicle moves and the communication state deteriorates has been widely known (see, for example, Patent Document 1).
JP 2001-345750 A (pages 8-9, FIG. 4)

  However, what is described in Patent Document 1 is to constantly monitor the communication state with the roadside device, and to switch to another roadside device when the communication state deteriorates. To solve a problem that communication efficiency is reduced when a predetermined communication area is covered and a predetermined service can be received in the communication area, concentrated on a roadside device that communicates with the in-vehicle device. I couldn't.

  That is, when a predetermined communication area is covered by a plurality of roadside devices and a predetermined service can be received in the communication area, each roadside device can communicate with a plurality of in-vehicle devices. In this case, the roadside device is configured to accept communication link requests of the in-vehicle device up to the maximum number of in-vehicle devices owned by itself, and with which roadside device the in-vehicle device communicates Therefore, the communication links of a plurality of in-vehicle devices may be concentrated on some roadside devices, and communication efficiency is thus determined. There was a problem that decreased.

  The present invention has been made in view of such a conventional problem. Even when the number of in-vehicle devices capable of communication increases, a road-side communication system in which these on-vehicle devices are allocated relatively evenly to a plurality of road-side devices. It is to provide.

The roadside communication system of the present invention includes a plurality of roadside devices that perform respective road-to-vehicle communication with in-vehicle devices that have respective communication areas and have entered the respective communication areas, and manage the plurality of roadside apparatuses, respectively. Storage means for storing information on how many in-vehicle devices are currently communicating with each roadside device in at least one of the roadside management device and the roadside device, and information stored in the storage means And determining means for determining whether or not to permit a communication link request from the in-vehicle device so that the in-vehicle device currently communicating is substantially equal in each roadside device.

  With this configuration, in-vehicle devices that are in communication with each roadside device are allocated almost evenly, and efficient communication is possible.

  In addition, the roadside communication system of the present invention communicates with the storage means how many in-vehicle devices are currently communicating, and how many in-vehicle devices each of the roadside devices may communicate with. Information on the number of in-vehicle devices that can be permitted is stored, and when the number of in-vehicle devices that are currently communicating reaches the number of in-vehicle devices that can be permitted, the determination means in the roadside device no longer has more in-vehicle devices. Has a configuration for rejecting a communication link request from the in-vehicle device because communication is impossible.

  With this configuration, the number of in-vehicle devices that can communicate with each roadside device is determined by the number of in-vehicle devices that can permit communication, and the number of in-vehicle devices that can allow communication is equalized in each in-vehicle device. By simply doing so, the number of in-vehicle devices that can communicate with each roadside device can be made equal, and efficient communication can be easily performed.

  Further, the roadside communication system of the present invention has a case where each roadside device communicates with one vehicle-mounted device in addition to information on how many vehicle-mounted devices are currently communicating with the storage means. The maximum data transfer rate is stored, and the determination means determines whether the on-vehicle device is based on the throughput per in-vehicle device in each roadside device calculated based on the number of in-vehicle devices in communication and the data transfer rate. The communication link request is determined to be permitted.

  With this configuration, even when the maximum data transfer rate that can be communicated with each roadside device is different from each other, in-vehicle devices are allocated to each roadside device 20 almost equally in accordance with their capabilities in consideration of these values. And efficient road-to-vehicle communication can be realized.

  Furthermore, the roadside communication system of the present invention is provided with communication quality acquisition means for acquiring communication quality with the in-vehicle device in each roadside device, and when the communication quality acquired by the communication quality acquisition means is worse than the predetermined communication quality, In the roadside device with poor communication quality, the judging means rejects the communication link request from the in-vehicle device to the roadside device.

  With this configuration, roadside devices with poor communication quality are excluded in advance, and when a new communication link is established, there is an effect that the communication quality is always higher than that.

  According to the present invention, at least one of the roadside management device and the roadside device stores storage means for storing information on how many in-vehicle devices are currently communicating with each roadside device, and based on the information stored in the storage means. By providing a judging means for judging whether or not to allow a communication link request from the in-vehicle device so that the in-vehicle devices in communication are almost equal in each road-side device, it communicates to each road-side device almost evenly. It is possible to provide a road-side communication system having an effect that an on-vehicle device can be allocated and efficient communication is possible.

  Hereinafter, a roadside communication system according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a roadside communication system according to an embodiment of the present invention, FIG. 2 is a schematic block diagram of the system, and FIG. 3 is an example of communication management information used in the system. FIG. 4 is a diagram illustrating an example of roadside management information used in the system.

  As shown in FIGS. 1 and 2, the roadside communication system according to the embodiment of the present invention has different communication areas A, B,..., And vehicles 30a are respectively provided in these communication areas A, B,. , 30b, 30c,... (Hereinafter, a collection of these vehicles will be referred to as the vehicle 30), and the in-vehicle devices 40a, 40b, 40c,. A plurality of roadside devices 20a, 20b that communicate with each other (hereinafter referred to as a roadside device 20), and these roadside devices. 20 and a roadside management apparatus 10 that performs communication on the same network.

  The roadside device 20a includes a narrow area communication unit 21a that communicates with the in-vehicle device 40, a communication management information storage unit 23a that stores communication management information received from the roadside management device 10, and a roadside management device 10. The communication part 22a which communicates between them, and the control part 24 which controls each of these parts are provided. The same applies to the roadside devices 20b. Here, the communication management information stored in the communication management information storage units 23a to 23 indicates how many in-vehicle devices can communicate with each roadside device 20a to each other as shown in FIG. This is information such as the number of possible in-vehicle devices and the number of in-vehicle devices currently in communication.

  In addition, the roadside management device 10 can communicate with the communication unit 11 that communicates with the roadside device 20 and the number of onboard devices that can communicate with the roadside devices 20a, 20b,. A roadside management information generation unit 12 that generates information on the number of devices, these information, and a roadside management information storage unit 13 that stores roadside management information for managing each of the roadside devices 20a to control each of these units. And a control unit 14 for performing the operation.

  Here, the roadside management information stored in the roadside management information storage unit 13 is a vehicle-mounted device that can communicate with a maximum number of vehicle-mounted devices in each roadside device 20a to 20 as shown in FIG. This is information such as the maximum value of the number of 40, the number of vehicle-mounted devices 40 that can be communicated for each roadside device 20 described above, and the number of vehicle-mounted devices 40 that are currently communicating.

  On the same network as the roadside management device 10 and the roadside devices 20a to, although not shown, a network device or a gateway device for connecting to an external network is connected.

  Next, the operation of the roadside communication system according to the present embodiment will be described in detail with reference to FIGS. FIG. 5 is a flowchart showing the operation of the in-vehicle device constituting the roadside communication system according to the embodiment of the present invention, FIG. 6 is a flowchart showing the operation of the roadside device constituting the system, and FIG. It is a flowchart which shows operation | movement of the roadside management apparatus which comprises the system.

When the vehicle 30a enters one of the communication areas A, B,..., The in-vehicle device 40a mounted on the vehicle 30a receives the radio waves of the communication areas A, B,. Then, the operation of selecting a communication channel for performing narrow area communication is started (S502). For example, a communication channel can be captured with any roadside device 20a that covers the communication area A that has entered (Y in S503).

  When the communication frame from the roadside device 20a is continuously received by a predetermined frame, a communication link connection request is transmitted to the roadside device 20a using the uplink channel corresponding to the channel (S504). If the communication channel cannot be acquired (N in S503), the process returns to the communication channel selection operation (S502) again, and the same operation is repeated.

  As shown in FIG. 6, when the narrow area communication unit 21a of the roadside apparatus 20a receives a communication link request from the in-vehicle apparatus 40a (Y in S601), the control unit 24a stores the communication link request in the communication management information storage unit 23a. The communication management information is checked (S602), and it is determined whether or not the communication link request from the in-vehicle device 40a is permitted. Then, the result is notified to the in-vehicle device 40a (S603).

  That is, as described above, the communication management information storage unit 23 stores information on the number of in-vehicle devices 40 that can be allowed to communicate and the number of in-vehicle devices 40 that are currently communicating. It is determined whether or not the requested communication link may be permitted from the information. If the number of in-vehicle devices 40 that are allowed to communicate is larger than the number of in-vehicle devices 40 that are currently communicating, the communication link request from the in-vehicle device 40a is permitted (Y in S604).

  If the number of in-vehicle devices 40 that can be allowed to communicate is equal to or less than the number of in-vehicle devices 40 that are currently communicating, no more communication links can be accepted anymore, and the communication link from that in-vehicle device 40a. The request is rejected (N in S604).

  When the in-vehicle device 40a receives the notification from the roadside device 20a (S505) and the result is that the communication link request from the in-vehicle device 40a is rejected (N in S506), or at that time or Then, after waiting for a certain time from that time, the operation of selecting the communication channel is started again (S501, S502). Thereafter, the same operation as the previous operation is repeated.

  If the notification from the roadside device 20a permits the request for the communication link from the in-vehicle device 40a (Y in S506), then the in-vehicle device 40a establishes the communication link (S507), The result is notified to the roadside apparatus 20a (S508).

  When the roadside device 20a receives a communication link establishment notification from the in-vehicle device 40a (S605), the roadside device 20a also establishes a communication link with the in-vehicle device 40a based on this (S606). In this state, the in-vehicle device 40a It becomes possible to communicate with an external network via the roadside device 20a, and a service from the external network can be received.

  When a communication link is established between the in-vehicle device 40a and the road-side device 20a and a service from an external network can be received, the road-side device 20a is next installed in the in-vehicle device as shown in FIG. Information indicating that the communication link request from the device 40a is permitted is notified to the roadside management device 10 via the communication unit 22a (S607).

  When the information indicating that the permission is given is notified to the roadside management apparatus 10, the roadside management apparatus 10 receives the information from the roadside apparatus 20a via the communication unit 11 as illustrated in FIG. 7 (Y in S701). Based on the information, the control unit 14 updates the roadside management information stored in the roadside management information storage unit 13 (S702).

That is, as described above, the roadside management information storage unit 13 stores information on the number of in-vehicle devices 40 currently communicating with each roadside device 20a to how many in-vehicle devices 40 are currently communicating. The number of pieces of information is updated in such a manner that 1 is added to the roadside device 20a that permits the communication link.

  Then, when the information on the number of in-vehicle devices 40 that are currently communicating, that is, how many in-vehicle devices 40 are currently communicating is updated (S702), roadside management information generation is performed based on the updated number of information. The unit 12 newly generates information on the number of in-vehicle devices that can be allowed to communicate for each roadside device 20a˜ that indicates how many in-vehicle devices 40 may communicate with each roadside device 20a˜ (S703). The information is stored in the roadside management information storage unit 13 as roadside management information (S704).

  When the roadside management information storage unit 13 stores information on the number of in-vehicle devices 40 that can permit communication for each roadside device 20a (S704), the information is stored in the roadside management information storage unit 13. It is transmitted to each roadside device 20a- together with information on the number of in-vehicle devices 40 currently communicating with each other (S705).

  The number of pieces of information transmitted to each roadside device 20a is received by the communication unit 22a of each roadside device 20a (S608) and stored in each communication management information storage unit 23a (S609). .

  Thus, according to the present embodiment, in the roadside management device 10, each roadside device 20 a to 20 can communicate with up to how many onboard devices 40, or the number of onboard devices 40 that can permit communication. When the number of in-vehicle devices 40 currently communicating with each roadside device 20a ~ reaches the number of in-vehicle devices 40 that can be permitted, it is no longer possible to communicate with any more in-vehicle devices 40, Since the in-vehicle device 40a is urged to communicate with the other roadside devices 20b ~ again, the number of in-vehicle devices 40 that communicate with each other can be made relatively uniform in each roadside device 20a ~. Can be improved.

  For example, there are now roadside devices 20a˜ that cover the respective communication areas A, B, C,..., And the maximum number of in-vehicle devices 40 that can communicate with these roadside devices 20a˜ is shown in FIG. 4, each is “8”, the number of in-vehicle devices that are allowed to communicate is “4”, and the number of in-vehicle devices currently communicating is “4”, “4”, “3”,. Suppose that another vehicle 30d (not shown) enters the communication area A in this state.

  In this case, in the roadside devices 20a and 20b covering the communication areas A and B, the number “4” of the in-vehicle devices 40 in communication has already reached the number “4” of the in-vehicle devices 40 that can permit communication. In this case, the communication link request from the in-vehicle device 40d (not shown) mounted on the vehicle 30d is rejected.

  The rejected in-vehicle device 40d makes a communication link request again. When the communication link request is already made to the roadside device 20c (not shown) that covers the communication area C when the communication link request is made, the communication area C is already in the communication area C (not shown). Since there is a margin in the number of in-vehicle devices 40 that can permit communication in the roadside device 20c to be covered, in this case, a communication link is formed with the roadside device 20c that covers the communication area C.

  When a communication link is formed and communication becomes possible, the number of in-vehicle devices 40 currently communicating is incremented by 1 to “4”. Therefore, even if another vehicle 30e (not shown) enters the area C in this state, a communication link can no longer be formed with the roadside device 20d covering the area C.

  However, in this embodiment, when the number of in-vehicle devices 40 currently in communication is updated in this way, efficient communication with any one of the roadside devices 20 is performed in advance based on the updated number of information. Considering the arrangement of the communication areas A, B, C,... And the vehicle entry condition so that a link is formed, for example, communication permission of the roadside devices 20a and 20b covering the communication areas A and B Whether new roadside management information is generated by the roadside management information generation unit 12, such as setting the number of possible in-vehicle devices 40 to “5”, and thereafter whether or not to accept a communication link request from the in-vehicle device 40 I am trying to judge.

  Therefore, according to the present embodiment, the in-vehicle devices 40a can be assigned almost equally to the plurality of road devices 20a, depending on how new road management information is generated, and efficient communication is performed. be able to.

  In this embodiment, when the roadside device 20a finishes communication with the in-vehicle device 40a, the number of the in-vehicle devices 40 currently communicating with the roadside device 20a is reduced by one and updated based on the information. It goes without saying that it is done.

  In the present embodiment, information on how many in-vehicle devices 40 can communicate with the communication management information storage unit 23a in each roadside device 20a in the own roadside device 20a and the current number of in-vehicle devices. 40 is stored in the roadside management device 10. The roadside management device 10 generates information about how many remaining in-vehicle devices 40 can be communicated with, and stores the information in each roadside device. You may make it memorize | store in the communication management information storage part 23a ~ of 20a ~.

  In this case, when it is possible to communicate with each of the in-vehicle devices 40a to until information indicating how many remaining in-vehicle devices 40 can be communicated becomes 0, it is determined whether communication is permitted. In addition, it is not necessary to use information on how many in-vehicle devices 40 can communicate with each other and information on how many in-vehicle devices 40 are currently communicating, and the determination can be made more easily.

  Moreover, in this Embodiment, the communication management information storage part 23a ~ in each roadside apparatus 20a ~ of the vehicle-mounted apparatus 40 which can permit communication of how many in-vehicle apparatuses 40 can communicate in the own roadside apparatus 20a. Information on the number of in-vehicle devices 40 that are currently communicating, such as the number of information and the number of in-vehicle devices 40 that are currently communicating, are stored for each new communication link request based on these information. Each of them decides whether or not to accept.

  As another method, information on the number of in-vehicle devices 40 currently communicating with all the roadside devices 20a is stored in the communication management information storage units 23a of each roadside device 20a, and the information of these numbers is stored. Based on this, when the number of in-vehicle devices 40 currently communicating with the roadside device 20a is smaller than the number of in-vehicle devices 40 currently communicating with the other roadside devices 20b, the new communication link request is accepted. Also good.

  In this way, the in-vehicle device 40 that is currently communicating can be stored without storing information on how many in-vehicle devices 40 can communicate with each of the communication management information storage units 23a of the roadside devices 20a. It is possible to accurately determine permission or non-permission for a new communication link request with only the number of information, and to easily make the number of in-vehicle devices 40 in communication in each roadside device 20a to approximately equal. it can.

In the present embodiment, the maximum number of in-vehicle devices 40 that can communicate is described as being the same in each of the roadside devices 20a to 20, but these numbers are different from each other in the in-vehicle devices 20 a to 20. May be. When the maximum number of in-vehicle devices 40 that can communicate is different from each other in each roadside device 20a ~, the number of in-vehicle devices 40 that can permit communication of each roadside device 20a ~ in consideration of the maximum value of these numbers. Can be set appropriately.

  For example, when the maximum number of in-vehicle devices 40 that can communicate with the roadside devices 20a, 20b, 20c,... Is “8”, “10”, “12”,. If the number of in-vehicle devices 40 that can communicate is increased or decreased in proportion to the maximum value of the number of in-vehicle devices 40 that can communicate, such as “4”, “5”, “6”,. Good. If it does in this way, it can be made equal distribution according to each ability.

  Moreover, without using the maximum value of the number of in-vehicle devices 40 that can communicate, the throughput per in-vehicle device in each road-side device 20a- is used, and the in-vehicle devices 40 that can communicate in each road-side device 20a-. It is also possible to make the number equal according to the capability of each roadside device 20a-. FIG. 8 is a diagram illustrating an example of communication management information and roadside management information used in a roadside communication system according to another embodiment of the present invention.

  In this case, first, the throughput per in-vehicle device in each roadside device 20a˜ is calculated as follows based on the data transfer speed in each roadside device 20a˜. Then, as shown in FIG. 8, those throughput values are stored in the roadside management information storage unit 13 as roadside management information. All the stored information is transmitted to the roadside devices 20a and stored in the communication management information storage units 23a of the respective roadside devices 20a.

  If there is a communication link request from the in-vehicle device 40a to the roadside device 20a, the roadside device 20a that has received the communication link request checks the throughput per in-vehicle device stored in the communication management information storage unit 23a. Then, it is determined whether or not the throughput per in-vehicle device in the own roadside device 20a is the highest. When it is the largest, it accepts the request for the communication link and enables road-to-vehicle communication with the in-vehicle device 40a having the communication link request.

  If it does in this way, it will come to receive a communication link request | requirement in the direction in which the throughput per vehicle-mounted apparatus in each roadside apparatus 20a ~ becomes substantially equal, respectively, and substantially equal according to the capability of each roadside apparatus 20a ~. Distribution.

  Here, the throughput per in-vehicle device can be calculated based on the following equation.

SP = S × 1 / n
However, SP is the throughput per in-vehicle device S is the data rate (kbps) when the roadside device 20 communicates with one in-vehicle device
n is the number of in-vehicle devices 40 currently in communication.

  The throughput values shown in FIG. 8 are an example in the case where the data transmission rates S in the respective roadside devices 20a˜ are different from 4096 Kbps, 2048 Kbps, and 1024 Kbps. In this example, since the throughput of the roadside device 20b (roadside device ID: B) is the highest compared to the other devices, when the roadside device 20b receives a communication link request from the in-vehicle device 40a, the roadside device 20b The communication link request is accepted and a communication link with the in-vehicle device 40a is established.

  And when there is a communication link request to other roadside devices 20a (roadside device ID: A), 20c (roadside device ID: C), 20d (roadside device ID: D), 20e (roadside device ID: E), Since the throughput in these roadside devices 20a, 20c, 20d, and 20e is smaller than that of the roadside device 20b, the communication link request from the in-vehicle device 40a is rejected.

  In this way, if the throughput per in-vehicle device in each roadside device 20a is calculated and configured to accept a communication link request only to the roadside device 20 having the largest value, the respective roadside devices 20a to 20a. Communication link requests will be accepted in a direction in which the throughput per in-vehicle device in each becomes almost equal, and the in-vehicle devices will be allocated almost equally to each roadside device 20a ~ in accordance with their capabilities. Efficient road-to-vehicle communication can be realized.

  FIG. 9 is a schematic block diagram showing a configuration of a roadside device of a roadside communication system according to still another embodiment of the present invention. FIG. 10 is an example of communication management information and roadside management information used in the system. FIG.

  In this case, for example, as shown in FIG. 9 in the case of the roadside device 20a, the communication quality (communication error rate with the vehicle-mounted device 40a- that is currently communicating or has communicated so far is communicated with each roadside device 20a-. Or the number of retransmissions) is provided, and the communication quality acquired by the communication quality acquisition unit 25a is used as the communication management information storage unit 23a of each roadside device 20a, the roadside management device. 10 in the roadside management information storage unit 13 as shown in FIG. 10, and when the communication quality is worse than the predetermined communication quality (in the case of failure), each roadside device 20a˜ It is also possible not to accept communication link requests for the roadside devices 20a-.

  If it does in this way, in addition to the throughput per in-vehicle device in each roadside device 20a-, in addition, considering the communication quality with each in-vehicle device 40a-, the roadside device 20a that can communicate is selected. Thus, more efficient communication becomes possible.

  As described above, the roadside communication system according to the present invention includes at least one of a roadside device and a roadside management device that stores the number of in-vehicle devices currently communicating with each roadside device, and the storage unit. Based on the number of in-vehicle devices stored in the device, a determination means for determining whether or not to permit a communication link request from a new in-vehicle device is provided so that the number is almost equal. In this case, on-vehicle devices that are communicating with each roadside device are allocated almost equally, and efficient communication is always possible.

  Therefore, it can be used for many services such as toll collection services such as parking lots and gas stations and services for providing necessary information.

The schematic block diagram of the roadside communication system in one embodiment of this invention 1 is a schematic block diagram of a roadside communication system according to an embodiment of the present invention. The figure which shows an example of the communication management information used in the system The figure which shows an example of the roadside management information used in the system Flow chart showing operation of in-vehicle devices constituting the system The flowchart which shows operation | movement of the roadside apparatus which comprises the system The flowchart which shows operation | movement of the roadside management apparatus which comprises the system The figure which shows an example of the communication management information and roadside management information which are used in the roadside communication system in other embodiment of this invention. The schematic block diagram which shows the structure of the roadside apparatus of the roadside communication system in further another embodiment of this invention. The figure which shows an example of the communication management information and roadside management information which are used in the system

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Roadside management apparatus 11 Communication part 12 Roadside management information generation part 13 Roadside management information storage part 14 Control part 20 Roadside apparatus 21 Narrow area communication part 22 Communication part 23 Communication management information storage part 24 Control part 30 Vehicle 40 Vehicle-mounted apparatus

Claims (4)

A plurality of roadside devices that perform road-to-vehicle communication with an in-vehicle device that has entered each communication area, and a roadside management device that manages the plurality of roadside devices,
In the roadside management device ,
For each of the plurality of roadside devices , a storage unit that stores communication management information including the maximum number of in- vehicle devices currently in communication and the number of in- vehicle devices capable of communication ;
Based on the communication management information stored in the storage unit, communication can be permitted for each of the plurality of roadside devices so that the number of in-vehicle devices currently in communication is substantially equal in the plurality of roadside devices. An information generator for generating information on the number of in-vehicle devices;
A transmission unit that transmits information including the number of in-vehicle devices currently communicating and the number of in-vehicle devices that are allowed to communicate to the plurality of roadside devices;
Each of the plurality of roadside devices
Based on the information transmitted from the transmission unit, if the number of in-vehicle devices that are allowed to communicate is larger than the number of in-vehicle devices that are currently communicating, it is determined to permit the communication link request from the in- vehicle device Roadside communication system having a unit . Each of the plurality of roadside devices further includes an output unit that outputs a determination result of the determination unit to the roadside management device,
The said roadside management apparatus further has an update part which updates the number of the vehicle-mounted apparatuses currently communicating memorize | stored in the said memory | storage part based on the said determination result output from the said output part. Roadside communication system. The information generation unit of the roadside management device generates information indicating how many remaining in-vehicle devices can be communicated, and the transmission unit transmits the information,
The roadside communication system according to claim 1 or 2, wherein the determination unit of each of the plurality of roadside devices determines whether to permit the communication link request based on the information. The information generation unit of the roadside management device generates information on the number of in-vehicle devices that are allowed to communicate so as to be proportional to the maximum value of the number of in-vehicle devices that can communicate with each of the plurality of roadside devices. The roadside communication system according to any one of claims 1 to 3.

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