JP6229520B2 - Road-to-vehicle communication system and in-vehicle device - Google Patents

Description

  The present invention relates to a road-to-vehicle communication system capable of performing road-to-vehicle communication by wireless communication using optical communication between an optical beacon disposed on a roadside or the like and an in-vehicle device mounted on an automobile or the like, and the road-to-vehicle communication system. It is related with the vehicle equipment used for.

  In recent years, a so-called VICS (Vehicle Information AND Communication System: registered trademark) using an optical beacon, a radio beacon, an FM multiplexing method, and the like has been developed as a traffic information service using a road-vehicle communication system.

  Among these, the optical beacon employs optical communication using near infrared as a communication medium, and can perform two-way communication with the vehicle-mounted device. Between 1993 and the present, about 54,000 optical beacons have been placed on roads throughout the country. Recently, it has been considered to expand the communication capacity and upgrade the system. .

  As a solution to this problem, research has been conducted on increasing the speed of communication (uplink) from the in-vehicle device side to the optical beacon side (high-speed uplink communication). In order to realize this high-speed uplink communication, the introduction of a new optical beacon and a new in-vehicle device with better communication performance are being studied. However, these devices are not compatible with conventional devices that can only perform conventional low-speed uplink communication. Must be compatible.

  In the following, regarding uplink communication, a device capable of only conventional low-speed uplink communication (for example, 64 kbps) is referred to as an old in-vehicle device and an old optical beacon, and uplink communication (for example, 256 kbps) at a higher speed than conventional. Possible devices are sometimes referred to as new in-vehicle devices and new light beacons.

  Various techniques have been proposed as techniques for ensuring this compatibility. For example, Patent Document 1 below is an optical beacon that transmits identification information indicating that the optical beacon is a new style from the new optical beacon side to the in-vehicle device side, and that corresponds to the new specification by the identification information in the new in-vehicle device. In such a case, a technique is disclosed in which predetermined information (high-speed uplink information) on the vehicle side such as travel time measurement information is transmitted by high-speed uplink communication.

  Conventionally, as shown in FIG. 2, areas A1 and A2 are defined as specified communication areas, and in area A1, low-speed uplink communication, high-speed uplink communication, downlink communication (high-speed down) Link communication) is possible, and in area A2, only downlink communication (high-speed downlink communication) is possible.

JP 2012-176170 A

  However, in the above-described conventional technology, high-speed uplink information can be transmitted from the new in-vehicle device based on the identification information transmitted from the new optical beacon. However, depending on the positional relationship between the new optical beacon and the new in-vehicle device, information can be appropriately transmitted and received. There was something that could not be done.

  For example, as shown in FIG. 2, in addition to area A1 and area A2, communication areas such as area A4 and area A3 (not enough communication) are formed in front of the area (left side of the figure). In the conventional technology, the in-vehicle device may receive the identification information in the area A3. In that case, the in-vehicle device immediately transmits the high-speed uplink information even in the area A3 in accordance with the communication regulations. End up.

  However, in this case, since the area A3 is an area where it is difficult to receive high-speed uplink information (or an area where high-speed uplink information cannot be received), as shown in FIG. However, there is a problem that high-speed uplink information may not be received.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a road-to-vehicle communication system and an in-vehicle device that can more reliably receive information transmitted from the in-vehicle device through high-speed uplink communication. Is to provide.

  (1) As one aspect, the present invention performs wireless communication by optical communication between an in-vehicle device of a traveling vehicle and an optical beacon on the road side, and performs low-speed uplink communication and high-speed uplink communication higher than that. In a road-to-vehicle communication system capable of communication by switching between the first beacon side and the initial information on the optical beacon side in the high-speed uplink communication from the optical beacon to the in-vehicle device, and the initial information The in-vehicle device that receives the initial information on the in-vehicle device side and the initial information on the in-vehicle device side are transmitted to the optical beacon in the low-speed uplink communication at each predetermined transmission time. The optical beacon having received the identification information indicating that the high-speed uplink communication is possible by the high-speed uplink communication to the vehicle-mounted device, and the identification information The vehicle-mounted device that has received the fourth processing step of transmitting uplink information including information related to the host vehicle to the optical beacon through the high-speed uplink communication, The number of transmissions of the initial information on the vehicle-mounted device side performed until receiving the identification information is determined, and when the number of transmissions is a plurality of times, the uplink is more than when the number of transmissions is one. The transmission timing of information is delayed.

  In the present invention, the optical beacon side initial information (predetermined information on the optical beacon side) is transmitted from the optical beacon to the vehicle-mounted device (on the optical beacon side) by high-speed uplink communication. (On the in-vehicle device side) The in-vehicle device transmits initial information on the in-vehicle device side (predetermined information on the in-vehicle device side) to the optical beacon at a predetermined transmission timing by low-speed uplink communication. The optical beacon (on the optical beacon side) transmits identification information indicating that high-speed uplink communication is possible to the vehicle-mounted device through high-speed uplink communication. (On the vehicle-mounted device side) The vehicle-mounted device transmits uplink information including information related to the host vehicle to the optical beacon by high-speed uplink communication. And when an in-vehicle device transmits uplink information to an optical beacon, it determines the number of transmissions of the initial information on the on-vehicle device side performed until receiving the identification information, and when the number of transmissions is multiple times Delays the timing for transmitting uplink information compared to the case where the number of transmissions is one.

  As described above, the in-vehicle device, for example, in the area A3 on the upstream side of the travel route of the vehicle from the specified communication area (area A1), that is, in the area where the high speed uplink communication is not specified, by the high speed uplink communication, If the uplink information is transmitted, it is difficult for the optical beacon to receive the uplink information. As a countermeasure against this, in the present invention, the in-vehicle device determines the number of transmissions of the initial information on the in-vehicle device side performed until the identification information is received, and transmits the uplink information when the number of transmissions is multiple times. Delay the timing to do. As a result, the optical beacon can be received in an area where high-speed uplink communication is defined, and uplink information can be reliably received.

  In other words, the optical beacon transmits identification information to the in-vehicle device when initial information on the in-vehicle device side is received, but the upstream side of the prescribed communication area is an area where the uplink is unstable (high-speed uplink communication is not possible). Therefore, it is difficult to receive the initial information on the in-vehicle device side, and thus it is difficult to transmit the identification information to the in-vehicle device.

  In other words, “the state where the identification information from the optical beacon cannot be obtained unless the initial information on the in-vehicle device side is transmitted more than once from the in-vehicle device” means that the in-vehicle device is unstable in the uplink that is not the specified communication area. Region (that is, for example, area A3 on the upstream side of the specified communication area). Therefore, in the present invention, when initial information on the in-vehicle device side is transmitted a plurality of times, uplink information is not immediately transmitted by high-speed uplink communication, but for example, in the area A1 downstream from the area A3. The transmission timing is delayed so that information is transmitted, that is, transmission is possible in a communication area where high-speed uplink communication is possible.

Thereby, the optical beacon can reliably receive the uplink information transmitted by the high-speed uplink communication from the in-vehicle device.
Here, the delay timing may be set by investigating how much delay is possible to achieve high-speed uplink communication (for example, whether the probability is high) by experiments or the like.

  As is well known, the uplink is communication for transmitting information from the vehicle-mounted device side to the optical beacon side, and high-speed uplink communication is communication capable of communication at a higher transmission rate than low-speed uplink communication. (The same applies hereinafter).

  (2) As another aspect, the present invention performs wireless communication by optical communication between an in-vehicle device of a running vehicle and an optical beacon on the road side, and performs low-speed uplink communication and high-speed uplink higher than that. In the in-vehicle device used in the road-to-vehicle communication system that can communicate by switching communication, in the high-speed uplink communication, when receiving the initial information on the optical beacon side, in the low-speed uplink communication, Identification information indicating that the high-speed uplink communication is possible in the high-speed uplink communication from the optical beacon with a first transmission unit that transmits initial information on the vehicle-mounted device side at each predetermined transmission time. A second transmission means for transmitting uplink information including information related to the host vehicle in the high-speed uplink communication in the optical beacon when transmitted. In addition, when the uplink information is transmitted by the second transmission means, the number of transmissions of the initial information on the vehicle-mounted device performed until the identification information is received is determined. In the case of a plurality of times, transmission control means for delaying the timing for transmitting the uplink information as compared with the case where the number of times of transmission is one is provided.

  In the present invention, when transmitting uplink information, the number of times of transmission of initial information on the in-vehicle device performed until reception of identification information is determined, and when the number of transmissions is multiple, the number of transmissions is The timing for transmitting the uplink information is delayed compared to the case of one time.

  Thereby, in this invention, as above-mentioned, since an onboard equipment can transmit uplink information in the communication area (for example, area A1) which can perform high-speed uplink communication suitably, it is an optical beacon. Can reliably receive the uplink information transmitted from the in-vehicle device by the high-speed uplink communication.

It is explanatory drawing which shows schematic structure of the road-vehicle communication system of Example 1. FIG. It is explanatory drawing which shows the kind of communication in a communication area (it shows from a side surface) in a road-to-vehicle communication system of Example 1, and a communication area. It is explanatory drawing which shows the procedure of transmission and reception in the road-vehicle communication system of Example 1. FIG. The data stored in the frame is shown, (a) is the first downlink information DL1, (b) is the first uplink information UL1, (c) is the second downlink information DL2, (d) is the second uplink information. It is explanatory drawing which shows an example of the content of the data of information UL2. It is a flowchart which shows the control processing in the optical beacon side of the road-to-vehicle communication system of Example 1. It is a flowchart which shows the control processing in the vehicle equipment side of the road-vehicle communication system of Example 1. FIG. It is explanatory drawing which shows the procedure of transmission and reception in the road-to-vehicle communication system (between new light beacon and new vehicle equipment) of a prior art.

  Next, an embodiment of a road-to-vehicle communication system and an in-vehicle device according to the present invention will be described with reference to the drawings.

[System overall configuration]
First, the overall configuration of the road-vehicle communication system according to the first embodiment will be described.
As shown in FIG. 1, the road-to-vehicle communication system according to the first embodiment includes a road-side (infrastructure-side) traffic control system 1 and an in-vehicle device 5 mounted on a vehicle 3 traveling on a road.

  The traffic control system 1 includes a central control device 7 provided in a traffic control room or the like, a large number of optical beacons 9 installed in various places on the road, and a communication unit that performs communication between the central control device 7 and the optical beacons 9 11.

  The optical beacon 9 is a device that performs wireless communication with the vehicle-mounted device 5 by optical communication using near infrared as a communication medium. The beacon control unit 13 and a plurality of beacon side projectors connected to the beacon control unit 13 are used. A light receiver (beacon head) 15.

The beacon control unit 13 is connected to the communication unit 11, and the communication unit 11 is connected to the central control device 7 through a communication line such as a telephone line.
On the other hand, the vehicle-mounted device 5 is a device that performs wireless communication with the optical beacon 9 by the optical communication, and includes a vehicle-mounted control unit 17 and a vehicle-mounted side projector (vehicle mounted head) 19 connected to the vehicle-mounted control unit 17. have.
[Configuration of optical beacon]
Next, the configuration of the optical beacon 9 will be described.

As described above, the optical beacon 9 includes the beacon control unit 13 (which is an electronic control device) and the beacon head 15.
The beacon head 15 includes an optical transmission unit 21 that can perform electro-optical conversion and an optical reception unit 23 that can perform photoelectric conversion.

  Among these, the optical transmission unit 21 transmits a light emitting element that transmits downlink light (optical signal in the downlink direction) made of near infrared rays to the areas A1, A2, A3, and A4 (refer to FIG. 2) which are downlink regions. Have. On the other hand, the optical receiver 23 includes a light receiving element that receives uplink light (an optical signal in the uplink direction) made of near infrared rays from the vehicle-mounted device 5 in the area A1 (see FIG. 2) that is an uplink region.

  The optical transmission unit 21 converts a downstream frame (parallel electrical signal) transmitted from the beacon control unit 13 into a serial transmission signal having a predetermined transmission rate (communication rate), and an output transmission signal. It is composed of a light emitting element such as a light emitting diode that converts to an optical signal in the downlink direction.

The transmission speed of the optical signal transmitted by the optical transmission unit 21 is 1024 kbps as in the conventional old optical beacon.
The light receiving unit 23 includes a light receiving element such as a photodiode and a receiving circuit that amplifies an electric signal output from the light receiving element and generates a digital reception signal.

  The optical receiving unit 23 is multi-rate capable of photoelectric conversion at two types of high and low transmission rates, and the lower transmission rate is 64 kbps as in the conventional old optical beacon. The transmission speed is, for example, 256 kbps.

  That is, in the first embodiment, when the optical beacon 9 transmits to the in-vehicle device 5 side, high-speed transmission (high-speed downlink communication) at 1024 kpbs is possible, while communication from the in-vehicle device 5 side. Is received at the optical beacon 9 side, low-speed reception at 64 kpbs (low-speed uplink communication) and high-speed reception at 256 kpbs (high-speed uplink communication) are possible.

  Therefore, this optical beacon 9 is a new optical beacon with higher communication performance than the old optical beacon. The downlink transmission rate of the old optical beacon is 1024 kbps as in the new optical beacon, but the uplink transmission rate is as low as 64 kbps.

The beacon control unit 13 is an electronic control device including a well-known computer having a CPU, a memory, and the like. The beacon control unit 13 is a two-way communication with the central control device 7 via the communication unit 11 and a road-vehicle communication with the in-vehicle device 5. It has the function as a communication control part which performs.
[Configuration of in-vehicle device]
Next, the configuration of the in-vehicle device 5 will be described.

As described above, the in-vehicle device 5 includes the in-vehicle control unit 17 (which is an electronic control device) and the in-vehicle head 19.
Similarly to the beacon head 15, the in-vehicle head 19 includes an optical transmission unit 25 that can perform electro-optical conversion and an optical reception unit 27 that can perform photoelectric conversion.

  Among these, the optical transmission unit 25 includes a light emitting element that emits uplink light (an optical signal in the uplink direction) made of near infrared rays. On the other hand, the optical receiving unit 27 includes a light receiving element that receives downlink light (an optical signal in the downlink direction) made of near infrared rays transmitted to the areas A1 and A2 which are downlink regions.

  The optical transmission unit 25 converts the upstream frame (parallel electrical signal) output from the in-vehicle control unit 17 into a serial transmission signal having a predetermined transmission rate, and outputs the output transmission signal in the uplink direction. It is composed of a light emitting element made of a light emitting diode or the like that converts the signal.

  Note that the optical transmission unit 25 is multi-rate capable of electro-optical conversion at two types of high and low transmission rates, and the lower transmission rate is 64 kbps as in the case of a conventional old vehicle-mounted device. The higher transmission rate is, for example, 256 kbps.

The light receiving unit 27 includes a light receiving element such as a photodiode and a receiving circuit that amplifies an electric signal output from the light receiving element and generates a digital reception signal.
The transmission speed of the optical signal received by the optical receiver 27 is 1024 kbps as in the conventional old vehicle-mounted device.

  That is, in the first embodiment, when the in-vehicle device 5 receives communication from the optical beacon 9 side, high-speed reception (high-speed downlink communication) at 1024 kpbs is possible, while the in-vehicle device 5 side When transmitting to the optical beacon 9 side (uplink), transmission at a low speed of 64 kpbs (low-speed uplink communication) and high-speed transmission at 256 kpbs (high-speed uplink communication) are possible.

Therefore, this in-vehicle device 5 is a new in-vehicle device having higher communication performance than the old in-vehicle device. The downlink transmission speed of the old in-vehicle device is 1024 kbps as in the new optical beacon, but the uplink transmission speed is as low as 64 kbp.
[Communication area of optical beacons]
Next, the communication area of the optical beacon 9 will be described.

  As shown in FIG. 2, the communication area of the optical beacon 9 includes areas A1, A2, A3, and A4 that are downlink areas in which downlink communication is possible, and an area A1 that is an uplink area in which uplink communication is possible. have. The area A1 is provided adjacent to the area A2 and upstream of the area 2, that is, on the upstream side (left side in the figure) in the traveling direction of the vehicle 3 (arrow direction in the figure).

  In other words, the optical beacon 9 is attached to a pillar provided on the road side, and on the road so as to irradiate near infrared light toward the road surface so as to form the areas A1, A2, A3, A4. Is arranged. Specifically, the beacon head 15 of the optical beacon 9 can irradiate near infrared light toward the areas A1, A2, A3, and A4 on the road surface, and receives near infrared light from the in-vehicle device 5 in the area A1. It is installed so that it can.

  Areas A1 and A2 are communication areas defined by a predetermined communication rule (for example, “optical vehicle detector near infrared interface standard”). The start position, the distance in the front-rear direction, the end position, the distance in the width direction of the road, etc. in each area A1 and A2 in the left-right direction in FIG.

Therefore, as shown in the table of FIG. 2, in the communication area of the optical beacon 9, the communication states are different in the areas A1 to A4.
The area A3 formed adjacent to the upstream side of the area A1 and the area A4 formed adjacent to the upstream side of the area A3 are not communication areas set by the predetermined communication rule, This is an example of an area that may actually be in such a communication state as the areas A1 and A2 are formed.

  Specifically, as shown in the table, in area A1, all of low speed uplink communication, high speed uplink communication, and downlink communication (here, high speed downlink communication) are possible.

In area A2, only downlink communication (high-speed downlink communication) is possible.
In area A3, only low-speed uplink communication and downlink communication (high-speed downlink communication) are possible.

In area A4, only downlink communication (high-speed downlink communication) is possible.
[Outline of road-to-vehicle communication]
Next, the procedure of road-to-vehicle communication and the contents of the communication will be described.

In the first embodiment, as shown in FIG. 3, road-to-vehicle communication is performed according to the following procedure (time series).
(1) First, the first downlink information DL1 (that is, the optical beacon) including various types of information (actual data) to be transmitted from the optical beacon 9 side to the in-vehicle device 5 side by the high-speed downlink communication. 9 side initial information) is transmitted.

The first downlink information DL1 is high-speed downlink information transmitted at high speed (1024 kbps), and is composed of a plurality of frames.
Specifically, in each frame, as shown in FIG. 4A, the header part (downlink header) stores data such as information type, provision time, last frame flag, frame number, and effective data length. ing.

  Among these, the last frame flag indicates the last frame among the plurality of frames divided by the information type, and the frame number indicates the sequence number of the plurality of frames divided by the information type. .

The final frame flag is set to on (for example, 1) when it is the final frame, and is set to off (for example, 0) otherwise.
The actual data portion (downlink actual data) stores current position information, traffic jam link information, travel time link information, and the like as the conventional information.

The transmission of the first downlink information DL1 is continuously performed until the first uplink information UL1 described later is received (on the optical beacon 9 side).
(2) Next, when the first downlink information DL1 is received on the in-vehicle device 5 side, the low-speed uplink is performed from the in-vehicle device 5 side to the optical beacon 9 side regardless of the content (actual data) of the data. The first uplink information UL1 (that is, initial information on the in-vehicle device 5 side) is transmitted by communication.

  In particular, in the first embodiment, the in-vehicle device 5 repeats transmission of the first uplink information UL1 every predetermined time. The transmission of the first uplink information UL1 is repeatedly performed until the identification information from the optical beacon 9 is received, as will be described later.

The first uplink information UL1 is low-speed uplink information transmitted at a low speed (64 kbps), and is composed of a plurality of frames.
Specifically, as shown in FIG. 4B, the header (uplink header) includes vehicle identification information, vehicle ID, vehicle type, vehicle-mounted device type, information type, final frame flag, frame number, effective data length, and the like. Is stored.

  Among these, the vehicle identification information indicates a service to which the vehicle 3 corresponds, the vehicle ID indicates a unique number of each vehicle 3, and the vehicle-mounted device type indicates whether or not the vehicle is a new vehicle-mounted device capable of high-speed uplink communication. The information type indicates whether the first uplink information UL1 (uplink 1) or second uplink information UL2 (uplink 2) described later, and the last frame flag indicates the last frame in the same information type. The frame number indicates the frame number within the same information type, and the effective data length indicates the effective data length of the actual data portion.

  For example, when the on-vehicle device type data is on (for example, set to 1), this indicates that the on-vehicle device 5 is a new on-vehicle device capable of high-speed uplink communication, and is off (for example, set to 0). In this case, the old vehicle-mounted device that can only perform low-speed uplink communication is shown.

The actual data part (uplink actual data) stores actual data such as vehicle measurement information similar to the conventional one.
(3) Next, when the first uplink information UL1 is received on the optical beacon 9 side, the in-vehicle device 5 performs high-speed uplink communication based on the in-vehicle device type data stored in the header portion. It is determined whether or not it is a possible new in-vehicle device. For example, when the data of the vehicle-mounted device type is turned on (for example, set to 1), it is determined that the vehicle is a new vehicle-mounted device.

  And when it is judged that it is a new vehicle equipment, it switches to a downlink and the identification information which shows that high speed uplink communication is possible by the high speed downlink communication from the optical beacon 9 side to the vehicle equipment 5 side 2nd downlink information DL2 containing is transmitted.

  For example, when the data of the vehicle-mounted device type is off (for example, set to 0), it is determined that the vehicle is an old vehicle-mounted device. In this case, the second downlink information DL2 that does not include identification information indicating that high-speed uplink communication is possible is transmitted.

The second downlink information DL2 is high-speed downlink information and includes a plurality of frames.
Specifically, as shown in FIG. 4 (c), like the first downlink information DL1, the header part (downlink header) includes an information type, a provision time, a last frame flag, a frame number, and an effective data length. Data such as size is stored.

In addition, the identification information which shows the new optical beacon which the optical beacon 9 can perform high-speed uplink communication is stored in the real data part of a specific information type.
For example, when the identification information data is on (for example, set to 1), this indicates that the optical beacon 9 is a new optical beacon capable of high-speed uplink communication, and is off (for example, set to 0). The old optical beacon that can only perform low-speed uplink communication.

The transmission of the second downlink information DL2 is continuously transmitted and is performed until a predetermined time elapses.
The in-vehicle device 5 stops the transmission of the first uplink information UL1 when the vehicle ID included in the actual data portion in the frame of the second downlink information DL2 matches the own vehicle ID. .

  (4) Next, when the second downlink information DL2 is received on the in-vehicle device 5 side, the optical beacon 9 can perform high-speed uplink communication based on the identification information stored in the header portion. It is determined whether it is a beacon. For example, when the identification information is on (for example, set to 1), it is determined that the light is a new light beacon.

  And when it is judged that it is a new light beacon, the 2nd including various information (actual data) regarding the own vehicle 3 which should be transmitted by the high-speed uplink communication from the vehicle equipment 5 side to the optical beacon 9 side. Uplink information UL2 is transmitted once.

  In particular, in the first embodiment, when the in-vehicle device 5 receives the second downlink information DL2 (and thus the identification information), the in-vehicle device 5 receives the first beacon 9 before receiving this identification information. The number of times that the uplink information UL1 is transmitted is confirmed. If the number of times of transmission is plural (two or more times), it is determined that the area is an unstable communication area, and the second uplink information UL2 is transmitted. Delay timing.

  That is, when the number of transmissions of the first uplink information UL1 is 1, the second uplink information UL2 is immediately transmitted. When the number of transmissions is a plurality of times, the timing is later than the initial timing. The second uplink information UL2 is transmitted (for example, transmission is started in detail) (for example, 5 ms after receiving the identification information).

Note that the time for delaying the second uplink information UL2 (delay time) is, for example, a maximum of 10 ms, so the delay time is within that range.
In addition,
The second uplink information UL2 is high-speed uplink information and is composed of a plurality of frames.

  Specifically, as shown in FIG. 4 (d), as in the first uplink information UL1, the header portion (uplink header) includes vehicle identification information, vehicle ID, vehicle type, vehicle-mounted device type, information type, Data such as a final frame flag, a frame number, and an effective data length are stored.

As described above, the final frame flag is set to on (for example, 1) when it is the final frame, and is set to off (for example, 0) otherwise.
The optical beacon 9 always transmits the first downlink information DL1 or the second downlink information DL2 every predetermined time, and after receiving the first uplink information UP1 from the in-vehicle device 5. The second downlink information DL2 is continuously transmitted for 350 ms, and the transmission is switched to the transmission of the first downlink information DL1 after 350 ms.
[Processing performed on the optical beacon side]
Next, although the process in transmission / reception of the road-to-vehicle communication system described above will be described separately for the optical beacon 9 side and the in-vehicle device 5 side, here, the process performed by the beacon control unit 13 on the optical beacon 9 side explain.

As shown in FIG. 8, on the optical beacon 9 side, first, in step (S) 100, first downlink information DL1 is transmitted (downlink 1 transmission).
In the following step 110, it is determined whether there is a downlink stop request. That is, it is determined whether there is a request to stop transmission of the first downlink information DL1. Specifically, when the power is OFF, it is determined that there is a downlink stop request. If an affirmative determination is made here, the process proceeds to step 120, while if a negative determination is made, the process proceeds to step 130.

In step 120, since there was a downlink stop request, downlink stop processing is performed, that is, transmission of the first downlink information DL1 is stopped, and this processing is once ended.
On the other hand, in step 130, since there is no downlink stop request, it is determined whether or not the first uplink information UL1 has been received (uplink 1 received). If an affirmative determination is made here, the process proceeds to step 140, while if a negative determination is made, the process returns to step 100.

In step 140, the downlink is switched. That is, a state in which downlink communication is possible is set.
In subsequent step 150, second downlink information DL2 (downlink 2) including identification information indicating that optical beacon 9 is a new optical beacon is transmitted.

In the following step 160, it is determined whether or not the second uplink information UL2 (uplink 2) has been received. If an affirmative determination is made here, the present process is once terminated, while if a negative determination is made, the process waits.
[Processing performed on the vehicle-mounted device side]
Here, the process performed in the vehicle-mounted control part 17 by the side of the vehicle equipment 5 is demonstrated.

As shown in FIG. 9, in step 200, reception of the first downlink information DL1 (downlink 1) is awaited.
In the following step 210, it is determined whether or not there is a vehicle-mounted device stop request. That is, it is determined whether there is a request to stop receiving the first downlink information DL1. Specifically, when the power is OFF, it is determined that there is a request to stop the vehicle-mounted device. If an affirmative determination is made here, the present process is once terminated, whereas if a negative determination is made, the process proceeds to step 220.

  In step 220, since there is no vehicle equipment stop request | requirement, it is determined whether the 1st downlink information DL1 was received (downlink 1 reception). If an affirmative determination is made here, the process proceeds to step 230, whereas if a negative determination is made, the process returns to step 200.

In step 230, first uplink information UL1 (uplink 1) is transmitted.
In the following step 240, reception of the first downlink information DL1 (downlink 1) or the second downlink information DL2 (downlink 2) is waited.

  In the following step 250, it is determined whether or not the second downlink information DL2 (and thus identification information) has been received. If an affirmative determination is made here, the process proceeds to step 280, whereas if a negative determination is made, the process proceeds to step 260.

  In step 260, since the identification information has not been received, the number of times of transmitting the first uplink information UL1 (uplink 1) (here, the number of retransmissions) is counted. That is, the number of retransmissions is counted.

In subsequent step 270, the first uplink information UL1 (uplink 1) is retransmitted, and the process returns to step 240.
On the other hand, in step 280, since the identification information is received, it is determined whether or not there is a reproduction count (that is, whether or not the first uplink information UL1 has been retransmitted (whether or not it has been transmitted twice or more)). If an affirmative determination is made here, the process proceeds to step 290, whereas if a negative determination is made, the process proceeds to step 310.

  In step 290, since it has been transmitted a plurality of times, the second uplink information UL2 (uplink 2) transmission timer is started. This transmission timer is a timer that delays the timing of transmitting the second uplink information UL2 (uplink 2).

  In the following step 300, it is determined whether or not it is the transmission timing (delayed) of the second uplink information UL2 (uplink 2) using the transmission timer. If an affirmative determination is made here, the process returns to step 310, while if a negative determination is made, the process waits.

In step 310, since it is the transmission timing (delayed), the second uplink information UL2 (uplink 2) is transmitted, and this processing is temporarily terminated.
[Effect of the first embodiment]
When the in-vehicle device 5 transmits uplink information by high-speed uplink communication in an area A3 upstream from the specified communication area (area A1), that is, an area where high-speed uplink communication is not specified, the optical beacon is Although it is difficult to receive the uplink information, in the first embodiment, the in-vehicle device 5 determines the number of transmissions of the first uplink information UL1 performed until the identification information is received, and the number of transmissions. In the case of multiple times, since the timing for transmitting the second uplink information UL2 is delayed, the optical beacon 9 can reliably receive the second uplink information UL2.

  That is, “a state where identification information from the optical beacon 9 cannot be obtained unless the first uplink information UL1 is transmitted a plurality of times from the vehicle-mounted device 5” is an area where the uplink that is not a prescribed communication area is unstable. In other words, in the first embodiment, when the first uplink information UL1 is transmitted a plurality of times, it is immediately increased by high-speed uplink communication. Rather than transmitting link information, the transmission timing is delayed so that the second uplink information UL2 is transmitted in a prescribed area A1 downstream of the area A3.

The delay timing is set within a predetermined maximum value range so that the in-vehicle device 5 does not transmit the second uplink information UL2 after passing through the area A1.
Thereby, the optical beacon 9 can reliably receive the second uplink information UL2 transmitted from the in-vehicle device 5 by the high-speed uplink communication.

Next, the second embodiment will be described, but the description of the same contents as the first embodiment will be omitted or simplified. In addition, the same number is used for each component as in the first embodiment (the same applies hereinafter).
The second embodiment has the same hardware configuration as that of the first embodiment, and the contents of processing on the in-vehicle device side are different. Therefore, different points will be described.

In the second embodiment, the delay time of the timing for transmitting the second uplink information UL2 is adjusted based on the speed of the host vehicle 3.
For example, as the speed of the host vehicle 3 increases, the time for passing through the area A1 is shortened. Therefore, a map is set in advance such that the delay time decreases as the speed of the host vehicle 3 increases. The delay time can be obtained from the speed of the host vehicle 3.

  The relationship between the speed and delay time of the host vehicle 3 may be obtained in advance through experiments or the like, and the map data may be stored in the memory of the in-vehicle control unit 17 and used.

As another modification, the delay time of the timing for transmitting the second uplink information UL2 may be adjusted based on the acceleration of the host vehicle 3.
For example, it is considered that as the acceleration of the host vehicle 3 increases, the time for passing through the area A1 is shortened. Therefore, a map is set in advance so that the delay time decreases as the acceleration of the host vehicle 3 increases. Thus, the delay time can be obtained from the acceleration of the host vehicle 3.

  In this case as well, the relationship between the acceleration and the delay time of the host vehicle 3 may be obtained in advance through experiments or the like, and the map data may be stored in the memory of the in-vehicle control unit 17 and used.

In the second embodiment, since the delay time is adjusted according to the speed and acceleration of the host vehicle 3, the optical beacon 9 can receive the second uplink information UL2 more reliably.
Needless to say, the present invention is not limited to the above-described embodiments and the like, and can be implemented in various modes without departing from the scope of the present invention.

  (1) For example, in each of the above embodiments, for example, the functions of one component may be distributed to a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the embodiment may be replaced with a known configuration having a similar function. Furthermore, at least a part of the configuration of the embodiment may be added to or replaced with the configuration of another embodiment.

  (2) In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in the Example as one aspect, and limits the technical scope of the present invention. It is not a thing.

DESCRIPTION OF SYMBOLS 1 ... Traffic control system 3 ... Vehicle 5 ... Car equipment 9 ... Optical beacon 13 ... Beacon control part 17 ... Vehicle control part

Claims (6)

Wireless communication by optical communication is performed between the vehicle-mounted device (5) of the traveling vehicle (3) and the optical beacon (9) on the roadside, and low-speed uplink communication and high-speed uplink communication higher than that are performed. In a road-to-vehicle communication system capable of switching communication,
A first processing step (S100) for transmitting initial information on the optical beacon (9) side in the high-speed uplink communication from the optical beacon (9) to the in-vehicle device (5);
The in-vehicle device (5) that has received the initial information transmits the initial information on the in-vehicle device (5) side to the optical beacon (9) at a predetermined transmission time in the low-speed uplink communication. 2 processing steps (S230);
The optical beacon (9) that has received the initial information on the in-vehicle device (5) side is identification information indicating that the in-vehicle device (5) can perform the high-speed uplink communication by the high-speed uplink communication. A third processing step (S150) for transmitting
The in-vehicle device (5) that has received the identification information transmits, to the optical beacon (9), uplink information including information related to the host vehicle (3) through the high-speed uplink communication. (S310),
And having
The in-vehicle device (5) determines the number of transmissions of the initial information on the in-vehicle device (5) performed until the identification information is received. When the number of transmissions is plural, the number of transmissions Compared to the case where there is only one time, the transmission timing of the uplink information is delayed (S300). 2. The road-to-vehicle communication system according to claim 1, wherein when the transmission timing is delayed, the delay timing is set so as not to transmit after passing through an area where the high-speed uplink communication is performed. Wireless communication by optical communication is performed between the vehicle-mounted device (5) of the traveling vehicle (3) and the optical beacon (9) on the roadside, and low-speed uplink communication and high-speed uplink communication higher than that are performed. In in-vehicle devices used in road-to-vehicle communication systems that can communicate by switching,
When the initial information on the optical beacon (9) side is received in the high-speed uplink communication, the initial information on the in-vehicle device (5) side is transmitted at a predetermined transmission time in the low-speed uplink communication. First transmission means for transmitting (S230),
When the optical beacon (9) transmits identification information indicating that the high-speed uplink communication is possible in the high-speed uplink communication, the optical beacon (9) is transferred to the high-speed uplink communication. Second transmission means (S310) for transmitting uplink information including information related to the host vehicle (3);
With
In the second transmission means (S310), when transmitting the uplink information, determine the number of times of transmission of the initial information on the in-vehicle device (5) performed until the identification information is received, When the number of transmissions is a plurality of times, compared to the case where the number of transmissions is one, transmission control means (S300) for delaying the timing for transmitting the uplink information;
An in-vehicle device characterized by comprising: The in-vehicle device according to claim 3 , wherein a delay time of timing for transmitting the uplink information is adjusted based on a speed of the host vehicle (3). The in-vehicle device according to claim 3 or 4 , wherein a delay time of a timing for transmitting the uplink information is adjusted based on an acceleration of the host vehicle (3). The delay timing is set so that the transmission timing is not transmitted after passing through the area where the high-speed uplink communication is performed. The in-vehicle device described .

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