JP2017073030A - On-vehicle device and optical beacon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to increase the possibility that an optical beacon may appropriately receive a high-speed frame transmitted after a low-speed frame from an on-vehicle apparatus in road-to-vehicle communication performed between the optical beacon and the on-vehicle apparatus that support multiple rates in an uplink direction.SOLUTION: An on-vehicle device is mounted on a vehicle and performs wireless communication with an optical beacon installed on a road by an optical signal. The on-vehicle device comprises: a light receiving unit capable of photoelectric conversion at a prescribed transmission speed; a light transmitting unit capable of electro-optical conversion at two types of high and low transmission speeds; and a communication control unit capable of transmitting one or more high-speed frames after transmission of a low-speed frame. The communication control unit re-transmits a prescribed high-speed frame when a prescribed condition is met.SELECTED DRAWING: Figure 16

Description

  The present invention relates to an in-vehicle device and an optical beacon that perform wireless communication using an optical signal.

  In road-to-vehicle communication systems where optical beacons and in-vehicle devices communicate optically, optical beacons that support high-speed uplink reception (hereinafter also referred to as “new optical beacons”) and in-vehicle devices that support high-speed uplink transmission ( Hereinafter, introduction of “new vehicle-mounted device”) is being studied (for example, see Patent Document 1).

Specifically, the new optical beacon can communicate with an in-vehicle device that performs only low-speed uplink transmission (hereinafter referred to as “old in-vehicle device”), and the new in-vehicle device is an optical beacon that performs only low-speed uplink reception ( Hereinafter, it is also necessary to be able to communicate with the “old optical beacon”.
Therefore, in Patent Document 1, a new in-vehicle device transmits a low-speed frame storing vehicle identification information (hereinafter referred to as “vehicle ID”) before a high-speed frame, and a new-type device that supports high-speed uplink communication. Even in such a case, a communication procedure for performing communication using a low-speed frame first has been proposed.

When the new vehicle-mounted device transmits a high-speed frame after a low-speed frame, an area that can receive the low-speed frame but cannot receive the high-speed frame depending on the traveling speed of the vehicle (insensitive area F in FIG. 11 of Patent Document 1). ), A new in-vehicle device may transmit a high-speed frame.
When a high-speed frame is transmitted in such a dead area, the new optical beacon cannot receive the high-speed frame.

Therefore, in Patent Document 1, a high-speed frame is received so as to be upstream or substantially at the same position as the upstream end (hereinafter referred to as “first uplink upstream end”) of an area where low-speed frames can be received. It has been proposed to set the position (hereinafter referred to as “uplink position setting”) of the upstream end of the possible area (hereinafter referred to as “second uplink upstream end”).
As a result, the insensitive area does not occur in the new light beacon, and the new light beacon can appropriately receive the high speed frame transmitted after the low speed frame.

JP 5300107 A

In the above-described new optical beacon, the downlink region may be set up to a portion (hereinafter referred to as “downlink upstream portion”) that extends upstream from the second uplink upstream end.
When the new in-vehicle device enters the inside of the above-described downlink upstream portion, the new in-vehicle device starts transmission of the low-speed frame including the vehicle ID of the own vehicle, triggered by reception of the downlink frame.

On the other hand, the uplink region is defined as a region where the bit error rate satisfies a predetermined communication quality (for example, 10 ⁻⁵ or less). Therefore, even if the new in-vehicle device transmits a low-speed frame in the downlink upstream portion, the communication quality is rarely satisfied, and normally, the new optical beacon cannot receive the low-speed frame.
However, since the low-speed frame transmitted first by the new in-vehicle device has a relatively small data size and is often only one frame, the probability is not high, but the new optical beacon receives the low-speed frame transmitted in the upstream of the downlink. there's a possibility that.

In this case, since the new light beacon performs downlink switching and transmits a downlink frame in which the vehicle ID of the new in-vehicle device is stored, the new in-vehicle device starts transmission of a high-speed frame in response to reception of the downlink frame.
Since the high-speed frame has a relatively large data size and a large number of frames, if the position of the new in-vehicle device in the vehicle traveling direction has not reached the upstream end of the second uplink at the start of transmission of the high-speed frame, The beacon may not receive all high speed frames properly.

As described above, even if the above-described uplink position setting is performed, the new optical beacon may not be able to properly receive the high-speed frame depending on the optical beacon, the position condition / installation condition of the vehicle-mounted device, and the like.
In view of such circumstances, in the road-to-vehicle communication between the multi-rate compatible optical beacon and the vehicle-mounted device in the uplink direction, the present invention provides the optical beacon for the high-speed frame transmitted from the vehicle-mounted device after the low-speed frame. The purpose is to increase the possibility of receiving properly.

  An in-vehicle device according to an aspect of the present invention is an in-vehicle device that is mounted on a vehicle and performs wireless communication using an optical beacon and an optical signal installed on a road, and can perform photoelectric conversion at a predetermined transmission speed. An optical receiver, an optical transmitter capable of electro-optical conversion at two high and low transmission rates, and a communication controller capable of transmitting one or more high-speed frames after transmission of a low-speed frame, The communication control unit is an in-vehicle device that retransmits a predetermined high-speed frame when a predetermined condition is satisfied.

  An in-vehicle device according to an aspect of the present invention is an in-vehicle device that is mounted on a vehicle and performs wireless communication using an optical beacon and an optical signal installed on a road, and can perform photoelectric conversion at a predetermined transmission speed. An optical receiver, an optical transmitter capable of electro-optical conversion at two high and low transmission rates, and a communication controller capable of transmitting one or more high-speed frames after transmission of a low-speed frame, The communication control unit is an in-vehicle device that retransmits an arbitrary high-speed frame among the plurality of high-speed frames.

  An optical beacon according to an aspect of the present invention is an optical beacon that performs wireless communication with an in-vehicle device of a traveling vehicle using an optical signal, and an optical receiving unit capable of photoelectric conversion at two high and low transmission speeds. An optical transmission unit capable of electro-optical conversion at a predetermined transmission rate; and a communication control unit capable of reproducing a low-speed frame or a high-speed frame from an electric signal output from the optical reception unit. The unit is an optical beacon that includes reception information that can identify a high-speed frame that the device itself has not received in a downlink frame that the optical transmission unit performs downlink transmission.

  An optical beacon according to an aspect of the present invention is an optical beacon that performs wireless communication with an in-vehicle device of a traveling vehicle using an optical signal, and an optical receiving unit capable of photoelectric conversion at two high and low transmission speeds. An optical transmission unit capable of electro-optical conversion at a predetermined transmission rate; and a communication control unit capable of reproducing a low-speed frame or a high-speed frame from an electric signal output from the optical reception unit. The unit is an optical beacon that includes retransmission instruction information for instructing retransmission of a high-speed frame in a downlink frame transmitted by the optical transmission unit when there is an unreceived high-speed frame.

  According to the present invention, in road-to-vehicle communication between a multi-rate optical beacon and an in-vehicle device in the uplink direction, the optical beacon can appropriately receive a high-speed frame transmitted after the low-speed frame from the in-vehicle device. Can increase the sex.

It is a block diagram which shows the whole structure of a road-vehicle communication system. It is the top view of the road which looked at the installation part of an optical beacon from the top. It is a side view which shows the communication area | region of an optical beacon. It is a sequence diagram which shows the conventional communication procedure. It is a figure which shows the mixed state of the old and new optical beacons and vehicle equipment. It is a flowchart which shows upward compatible control of a new light beacon. It is a frame block diagram of uplink information. It is a frame block diagram of downlink information. It is a sequence diagram which shows the road-to-vehicle communication when not providing a transmission interruption period. It is a sequence diagram which shows the road-to-vehicle communication in the case of providing a transmission interruption period. It is explanatory drawing which shows an example of a downlink upstream part which is a part of the downlink area | region located in the upstream of an uplink area | region. It is a frame block diagram of the high-speed frame in 1st Embodiment. It is a frame block diagram of the downstream frame after the downlink switch in 1st Embodiment. It is a flowchart which shows an example of the process which the beacon controller of 1st Embodiment performs. It is a flowchart which shows an example of the process which the vehicle-mounted controller of 1st Embodiment performs. It is a sequence diagram which shows the road-vehicle communication of the new vehicle equipment of 1st Embodiment and a new light beacon. It is a frame configuration diagram of a downlink frame after downlink switching in the second embodiment. It is a flowchart which shows an example of the process which the beacon controller of 2nd Embodiment performs. It is a flowchart which shows an example of the process which the vehicle-mounted controller of 2nd Embodiment performs. It is a flowchart which shows an example of the process which the vehicle-mounted controller of 3rd Embodiment performs. It is a flowchart which shows an example of the process which the vehicle-mounted controller of 4th Embodiment performs. It is a sequence diagram which shows the road-vehicle communication performed between the new vehicle equipment and new light beacon of 5th Embodiment. It is explanatory drawing which shows the structure of the upstream frame group which the new vehicle equipment which concerns on the modification 1 of 5th Embodiment transmits initially. It is explanatory drawing which shows the structure of the upstream frame group which the new vehicle equipment which concerns on the modification 2 of 5th Embodiment transmits initially. It is a sequence diagram which shows the road-vehicle communication performed between the new vehicle equipment of the reference example 2, and a new light beacon. It is a side view which shows the preferable communication area | region of the new light beacon of the reference example 2. The current waveform at the time of the light emission of the uplink light by the conventional new vehicle equipment is shown, (a) is a current waveform of a low-speed frame, (b) is a current waveform of a high-speed frame. The actual current waveform at the time of light emission of the uplink light of the new vehicle-mounted device according to the optical countermeasure example is shown, (a) is the current waveform of the low-speed frame, and (b) is the current waveform of the high-speed frame. It is a side view which shows the communication area | region of the new light beacon which concerns on the countermeasure example 1. FIG. It is a side view which shows the communication area | region of the new light beacon which concerns on the example 2 of a countermeasure. It is a circuit block diagram of the new light beacon which concerns on the countermeasure example 2. FIG. It is explanatory drawing of the measurement principle of an uplink position using the position detection element of the countermeasure example 2. FIG. 12 is a flowchart illustrating an example of a reception restriction process performed by the main CPU according to countermeasure example 2;

[Description of Embodiment of the Present Invention]
First, the contents of the embodiment of the present invention will be listed and described.
(1) An in-vehicle device according to an embodiment of the present invention is an in-vehicle device that is mounted on a vehicle and performs wireless communication using an optical beacon and an optical signal installed on a road, and is an optoelectronic device at a predetermined transmission speed. An optical receiver capable of conversion; an optical transmitter capable of electro-optical conversion at two high and low transmission rates; and a communication controller capable of transmitting one or more high-speed frames after transmission of a low-speed frame. The communication control unit retransmits a predetermined high-speed frame when a predetermined condition is satisfied.

  According to the above vehicle-mounted device, the communication control unit retransmits a predetermined high-speed frame when a predetermined condition is satisfied. For example, a part of a plurality of high-speed frames transmitted first is an optical beacon. Even if the packet cannot be received, the possibility that the unreceived high-speed frame can be received by the retransmission increases. For this reason, in road-to-vehicle communication performed between a multi-rate compatible optical beacon and an in-vehicle device in the uplink direction, the possibility that the optical beacon appropriately receives the high-speed frame transmitted from the in-vehicle device after the low-speed frame is increased. be able to.

(2) In the in-vehicle device, the predetermined condition is that a downstream frame received from the optical beacon includes reception information that can identify a high-speed frame from which the optical beacon has not been received. Is preferred.
In this case, when reception information that can identify a high-speed frame from which an optical beacon has not been received is included, a predetermined high-speed frame is retransmitted, so a high-speed frame from which an optical beacon has not been received is received. The possibility of being able to be further increased.
In addition, since the in-vehicle device can identify the high-speed frame that has not been received by the optical beacon, the time to retransmit the high-speed frame that has been received by the optical beacon can be retransmitted by retransmitting the high-speed frame that has not been received. It can be omitted. Thereby, since the retransmission time can be shortened, the reception time of the downlink frame that the own device receives in the downlink can be lengthened accordingly. As a result, the in-vehicle device can acquire more provision information from the optical beacon.

(3) In the on-vehicle apparatus, the predetermined condition may be that a downlink frame received from the optical beacon includes retransmission instruction information for instructing retransmission of a high-speed frame.
In this case, when the optical beacon instructs to retransmit the high-speed frame, the predetermined high-speed frame is retransmitted, so that the possibility of receiving the high-speed frame that has not been received by the optical beacon can be further increased.

(4) In the in-vehicle device, the predetermined condition may be that a predetermined frame provided by the optical beacon is included in a downlink frame received from the optical beacon.
In this case, when the predetermined provision information is acquired from the optical beacon, the predetermined high-speed frame is retransmitted, so that the in-vehicle device can receive the high-speed frame that has not been received by the optical beacon while acquiring the provision information. Can increase the sex.
In addition, when the in-vehicle device acquires all the provision information provided by the optical beacon or only the provision information required by the own device as the predetermined provision information, it is no longer necessary to spend time for downlink communication. Instead, time can be spent on uplink communication. As a result, the in-vehicle device can effectively use the limited communication time.

(5) In the on-vehicle device, the predetermined condition may be that a speed of the vehicle satisfies a predetermined speed condition.
In this case, when the vehicle speed satisfies a predetermined speed condition, a predetermined high-speed frame is retransmitted. For example, when the vehicle speed is low, that is, a vehicle in an area where an optical beacon can receive a high-speed frame. If the high-speed frame is retransmitted when the travel time is long, the possibility of receiving the high-speed frame that has not been received by the optical beacon can be further increased. Further, when the speed of the vehicle is low, the in-vehicle device has a longer time in the area, so there is a time margin for retransmitting the high-speed frame.

(6) In the on-vehicle apparatus, it is preferable that the communication control unit retransmits the high-speed frame that has not been received based on the reception information.
In this case, since the communication control unit retransmits the high-speed frame that has not been received by the optical beacon, the possibility that the optical beacon can receive the high-speed frame that has not been received can be further increased.
Moreover, the vehicle-mounted device can save time for retransmitting a high-speed frame that has been received by an optical beacon. Thereby, since the retransmission time can be shortened, the reception time of the downlink frame that the own device receives in the downlink can be lengthened accordingly. As a result, the in-vehicle device can acquire more provision information from the optical beacon.

(7) An in-vehicle device according to an embodiment of the present invention is an in-vehicle device that is mounted on a vehicle and performs wireless communication by using an optical beacon and an optical signal installed on a road, and is photoelectric at a predetermined transmission speed. An optical receiver capable of conversion; an optical transmitter capable of electro-optical conversion at two high and low transmission rates; and a communication controller capable of transmitting one or more high-speed frames after transmission of a low-speed frame. The communication control unit retransmits an arbitrary high-speed frame among the one or a plurality of high-speed frames.

  According to the in-vehicle device, since the communication control unit retransmits an arbitrary high-speed frame, for example, even if the optical beacon cannot be received from some of the plurality of high-speed frames transmitted first, The possibility of receiving a high-speed frame that has not been received due to retransmission increases. For this reason, in road-to-vehicle communication performed between a multi-rate compatible optical beacon and an in-vehicle device in the uplink direction, the possibility that the optical beacon appropriately receives the high-speed frame transmitted from the in-vehicle device after the low-speed frame is increased. be able to.

(8) In the in-vehicle device, when the communication control unit transmits a plurality of high-speed frames, the communication control unit selects some high-speed frames from the top of the plurality of high-speed frames (K is a positive integer). It may be retransmitted.
When the transmission of multiple high-speed frames is started after transmission of low-speed frames, if the position of the in-vehicle device in the vehicle traveling direction has not reached the upstream end of the area where high-speed frames can be received, high-speed frames for several frames from the beginning Is less likely to be received by optical beacons. On the other hand, in the above-mentioned in-vehicle device, the communication control unit retransmits K high-speed frames from the top of a plurality of high-speed frames, so that it is possible to receive a high-speed frame that has not received an optical beacon. Can be further enhanced.
In addition, since the in-vehicle device can shorten the retransmission time compared to the case of retransmitting all of the plurality of high-speed frames, the reception time of the downlink frame for downlink reception can be increased by that amount. Thereby, the vehicle equipment can acquire more provision information from the optical beacon.

(9) In the in-vehicle device, it is preferable that the communication control unit adds the arbitrary high-speed frame to an uplink frame group that transmits the one or more high-speed frames.
In this case, the retransmission-reliable high-speed frame is transmitted in addition to the upstream frame group that transmits one or a plurality of high-speed frames, so that the optical beacon can quickly receive a high-speed frame that has not been received.

(10) In the on-vehicle device, when the communication control unit transmits a plurality of high-speed frames, the communication frame from the top of the plurality of high-speed frames up to K (K is a positive integer) It is preferable to add to the upstream frame group.
In this case, it is possible to further increase the possibility of receiving the high-speed frame that has not been received by the optical beacon by retransmitting up to K high-speed frames that are highly likely to be unreceived by the optical beacon. .

(11) In the in-vehicle device, when the maximum number of high-speed frames that can be included in the uplink frame group is N and the total number of frames of the plurality of high-speed frames is M, the communication control unit It is preferable to add some high-speed frames from the top to K as retransmission credits so as to satisfy the following expression (1).
K = N−M (1)
Here, N is a positive integer, and M is a positive integer smaller than N.
In this case, since the number (K) of retransmission-reliable high-speed frames added to the uplink frame group can be increased as much as possible, the possibility of receiving a high-speed frame that has not been received by an optical beacon is further increased. Can do.

(12) In the on-vehicle apparatus, when the communication control unit transmits a plurality of high-speed frames, the communication control unit may retransmit all of the plurality of high-speed frames.
In this case, for example, the optical beacon increases the possibility of receiving a high-speed frame that has not been received even if any of the high-speed frames transmitted first cannot be received. it can.

(13) In the in-vehicle device, when the maximum number of high-speed frames that can be included in the uplink frame group is N and the total number of frames of the plurality of high-speed frames is M, the communication control unit: It is preferable that the K high-speed frames from the top are added R times to the uplink frame group as retransmission trust within a range satisfying the following expression (2).
K × R ≦ N−M Formula (2)
Here, N is a positive integer, M is a positive integer smaller than N, K is a positive integer less than or equal to M, and R is a positive integer greater than or equal to 2.
In this case, K high-speed frames may be repeatedly retransmitted in a range where the total number of high-speed frames to be transmitted and retransmitted (N + K × R) does not exceed the maximum number of frames (N) in the uplink frame group. it can. For this reason, it is possible to further increase the possibility of receiving a high-speed frame in which an optical beacon has not been received.

(14) In the in-vehicle device, it is preferable that N is set according to a speed of the vehicle.
In this case, the communication control unit sets the maximum number of high-speed frames (N) that can be included in the uplink frame group according to the vehicle speed. For example, the maximum number of frames increases as the vehicle speed decreases. By setting so, it is possible to increase the number of retransmission-reliable high-speed frames to be added to the uplink frame group, so that it is possible to further increase the possibility of receiving a high-speed frame that has not been received by an optical beacon.

(15) In the in-vehicle device, it is preferable that the communication control unit retransmits the high-speed frame a plurality of times, and sets the number of retransmissions according to the speed of the vehicle.
In this case, the communication control unit sets the number of retransmissions of the high-speed frame according to the speed of the vehicle. For example, if the setting is made so that the number of retransmissions increases as the vehicle speed decreases, the communication control unit retransmits the frames. Since the number of high-speed frames increases, the possibility of receiving a high-speed frame in which an optical beacon has not been received can be further increased.

(16) In the on-vehicle apparatus, when the high-speed frame is retransmitted, the communication control unit preferably sets a transmission interval between the high-speed frame transmitted immediately before the high-speed frame according to the speed of the vehicle.
In this case, the communication control unit sets the transmission interval of the high-speed frame according to the speed of the vehicle. For example, if the transmission interval is set longer as the vehicle speed becomes slower, the optical beacon is retransmitted at a higher speed. Since the frame can be properly received, it is possible to further increase the possibility of receiving the high-speed frame in which the optical beacon has not been received.
In addition, if the transmission interval is set longer as the vehicle speed becomes slower, the distance that the vehicle travels before the high-speed frame is retransmitted correspondingly increases. Therefore, the upstream end of the area where the high-speed frame can be received. There is a high possibility that a vehicle that has not yet reached will reach the area at the time of retransmission. As a result, the possibility of receiving a high-speed frame in which an optical beacon has not been received can be further increased.

(17) An optical beacon according to an embodiment of the present invention is an optical beacon that performs wireless communication with an in-vehicle device of a traveling vehicle by an optical signal, and is capable of photoelectric conversion at two high and low transmission speeds. A receiving unit, an optical transmitting unit capable of electro-optical conversion at a predetermined transmission rate, and a communication control unit capable of reproducing a low-speed frame or a high-speed frame from an electric signal output from the optical receiving unit, The communication control unit includes reception information that can identify a high-speed frame that the device itself has not received in a downlink frame that the optical transmission unit performs downlink transmission.

According to the optical beacon, the communication control unit includes reception information that can identify a high-speed frame that has not been received among a plurality of high-speed frames transmitted from the in-vehicle device, in the downlink frame to be downlink transmitted, The in-vehicle device that has received the downlink frame can recognize the high-speed frame in which the optical beacon has not been received. For this reason, for example, if the in-vehicle device retransmits a high-speed frame that has not been received, the possibility that the optical beacon can receive the high-speed frame increases. For this reason, in road-to-vehicle communication performed between a multi-rate compatible optical beacon and an in-vehicle device in the uplink direction, the possibility that the optical beacon appropriately receives the high-speed frame transmitted from the in-vehicle device after the low-speed frame is increased. be able to.
Further, the in-vehicle device can save time for retransmitting the high-speed frame that has been received by the optical beacon by retransmitting the high-speed frame from which the optical beacon has not been received. Thereby, since the retransmission time can be shortened, the reception time of the downlink frame that the own device receives in the downlink can be lengthened accordingly. As a result, the in-vehicle device can acquire more provision information from the optical beacon.

(18) An optical beacon according to an embodiment of the present invention is an optical beacon that performs wireless communication using an optical signal with an in-vehicle device of a running vehicle, and is capable of photoelectric conversion at two high and low transmission speeds. A receiving unit, an optical transmitting unit capable of electro-optical conversion at a predetermined transmission rate, and a communication control unit capable of reproducing a low-speed frame or a high-speed frame from an electric signal output from the optical receiving unit, The communication control unit includes retransmission instruction information for instructing retransmission of a high-speed frame in a downlink frame transmitted by the optical transmission unit when there is an unreceived high-speed frame.

  According to the above-described optical beacon, the communication control unit transmits downlink information indicating that retransmission of a high-speed frame is present when there is a high-speed frame that has not been received among a plurality of high-speed frames transmitted from the in-vehicle device. Therefore, the in-vehicle device that has received the downlink frame can recognize that there is a high-speed frame that could not be received by the optical beacon. For this reason, for example, if the in-vehicle device retransmits a specific high-speed frame set in advance, the possibility of receiving a high-speed frame that has not been received by the optical beacon increases. For this reason, in road-to-vehicle communication performed between a multi-rate compatible optical beacon and an in-vehicle device in the uplink direction, the possibility that the optical beacon appropriately receives the high-speed frame transmitted from the in-vehicle device after the low-speed frame is increased. be able to.

[Details of the embodiment of the present invention]
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, you may combine arbitrarily at least one part of embodiment described below.
[System overall configuration]
FIG. 1 is a block diagram showing an overall configuration of a road-vehicle communication system according to an embodiment of the present invention. As shown in FIG. 1, the road-to-vehicle communication system of the present embodiment includes an infrastructure-side traffic control system 1 and an in-vehicle device 2 mounted on a vehicle 20 (see FIG. 3) traveling on a road R.

The traffic control system 1 includes a central device 3 provided in a traffic control room or the like, and optical beacons (optical vehicle detectors) 4 installed in many places on the road R. The optical beacon 4 can perform wireless communication with the in-vehicle device 2 by optical communication using near infrared as a communication medium.
The optical beacon 4 includes a beacon controller (communication controller) 7 and a plurality (four in FIG. 1) of beacon heads (also referred to as projectors / receivers) 8 connected to the sensor interface of the beacon controller 7. have.

The beacon controller 7 is connected to a communication unit 6 on the infrastructure side, and the communication unit 6 is connected to the central apparatus 3 by a communication line 5 such as a telephone line.
The communication unit 6 can be configured by, for example, a traffic signal controller that controls the color of a signal lamp, an information relay device that performs a relay process of traffic information on the infrastructure side, and the like.

The optical beacon 4 of this embodiment employs a full-duplex communication method. That is, the beacon controller 7 to be described later can simultaneously perform transmission control in the downlink direction for the optical transmission unit 10 and reception control in the uplink direction for the optical reception unit 11.
On the other hand, the in-vehicle device 2 of the present embodiment employs a half-duplex communication method. That is, the below-described vehicle-mounted controller 21 does not simultaneously perform uplink direction transmission control for the optical transmission unit 23 and downlink direction reception control for the optical reception unit 24.

  The uplink direction transmission control for the optical transmission unit 23 and the downlink direction reception control for the optical reception unit 24 may be performed at the same time, but as a matter of fact, only one of them is configured to function. It shall be. That is, it is difficult to receive the downlink during uplink transmission.

[Configuration of optical beacon]
The beacon head 8 of the optical beacon 4 has an optical transmitter 10 capable of electro-optical conversion and an optical receiver 11 capable of photoelectric conversion inside the casing.
Among these, the optical transmission unit 10 has a light emitting element that transmits downlink light (optical signal in the downlink direction) made of near infrared rays to the downlink area DA (see FIG. 3), and the optical reception unit 11 is up It has 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 2 in the link area UA (see FIG. 3).

The optical transmitter 10 transmits a downstream frame transmitted from the beacon controller 7 into a serial transmission signal having a predetermined transmission rate, and converts the output transmission signal into an optical signal in the downlink direction. It is equipped with a light emitting element made of a diode or the like.
In the optical beacon 4 of the present embodiment, the transmission speed of the optical signal transmitted by the optical transmitter 10 is 1024 kbps as in the conventional old optical beacon.

The light receiving unit 11 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.
In the optical beacon 4 of the present embodiment, the optical receiver 11 is multi-rate capable of performing photoelectric conversion at two types of transmission rates, high and low. The lower transmission rate is 64 kbps as in the conventional old optical beacon. The higher transmission speed may be 128 kbps, 192 kbps, 256 kbps, 384 kbps, 512 kbps, 1024 kbps, etc., but in this embodiment, it is assumed to be 256 kbps.

FIG. 2 is a plan view of the road R when the installation portion of the optical beacon 4 of this embodiment is viewed from above.
As shown in FIG. 2, the optical beacon 4 of the present embodiment is installed on a road R having a plurality (four in the illustrated example) of lanes R1 to R4 in the same direction. The optical beacon 4 includes a plurality of beacon heads 8 provided corresponding to the lanes R <b> 1 to R <b> 4 and a single beacon controller 7 that is a control unit that collectively controls these beacon heads 8.

The beacon controller 7 is composed of a computer device having a signal processing unit, a CPU, a memory, and the like. The beacon controller 7 communicates with the central device 3 via the communication unit 6 (see FIG. 1) and road-to-vehicle communication with the in-vehicle device 2. It has a function as a communication control part which performs.
The beacon controller 7 stores a computer program for communication control in a storage device, and the CPU functions as the communication control unit when the CPU reads and executes the program.

The beacon controller 7 is installed on a support column 13 standing on the side of the road. Each beacon head 8 is attached to an erection bar 14 installed horizontally on the road R side from the support column 13 and is disposed immediately above each lane R1 to R4 of the road R.
The light emitting element of the beacon head 8 emits near infrared rays toward the upstream side in the vehicle traveling direction from directly below the lanes R <b> 1 to R <b> 4, thereby performing road-to-vehicle communication with the in-vehicle device 2. A communication area A is set on the upstream side of the head 8.

[Communication area of optical beacons]
FIG. 3 is a side view showing the communication area A of the optical beacon 4.
As shown in FIG. 3, the communication area A of the optical beacon 4 includes a downlink area (area provided with solid hatching in FIG. 3) DA and an uplink area (area provided with dashed hatching in FIG. 3) UA. It consists of.

In FIG. 3, the downlink area DA is a range indicated by Δdac having apexes at the light emitting / receiving position d of the beacon head 8 and the positions a and c at a height of 1 m above the ground.
In the downlink area DA, the in-vehicle head 22, which is a projector / receiver of the in-vehicle device 2, transmits an optical signal in the downlink direction transmitted by the beacon head 8 at a predetermined bit error rate (for example, 10 ^{−5 in the} standard value) or less. It is an area that can be received.

In FIG. 3, the uplink area UA is a range indicated by Δdbc with the light emitting / receiving position d of the beacon head 8 and the positions b and c at a height of 1 m above the ground as vertices.
In the uplink area UA, the beacon head 8 which is a light emitter / receiver of the optical beacon 4 transmits an optical signal in the uplink direction transmitted by the vehicle-mounted head 22 at a predetermined bit error rate (for example, 10 ^{−5 in the} standard value) or less. It is an area that can be received.

As shown in FIG. 3, in the communication standard, the downlink area DA and the upstream end c of the uplink area UA are defined to coincide. In this case, the uplink area UA overlaps with the upstream part (the right part in FIG. 3) of the downlink area DA in the vehicle traveling direction.
Further, the downlink area DA extends downstream from the uplink area UA. Therefore, the vehicle traveling direction length of the downlink area DA matches the same direction length of the entire communication area A.

In the communication standard of the old optical beacon (optical vehicle sensor), the area dimensions to be applied to the downlink area DA and the uplink area UA are defined as follows.
That is, in the case of an old optical beacon for a general road, the downstream end a of the downlink area DA is located 1.0 to 1.3 m upstream immediately below the beacon head 8, and from the downstream end a of the downlink area DA. The distance to the downstream end b of the uplink area UA is defined as 2.1 m. The distance from the downstream end b of the uplink area UA to the upstream end c of the area UA is defined as 1.6 m. Accordingly, the total length (the length between ac) of the communication area A in the vehicle traveling direction is 3.7 m.

  On the other hand, in the optical beacon 4 (new optical beacon) of the present embodiment, the downstream end a of the downlink area DA is extended to a position immediately below the beacon, and the upstream end c is extended to the upstream side of the above-mentioned regulation, thereby the downlink area DA The vehicle traveling direction range is set wider than in the case of an old optical beacon that does not support high-speed uplink reception.

As a specific numerical example, when the area directly below the beacon head 8 is 0 m (origin) and the upstream direction is a positive direction, the range of the downlink area DA of this embodiment (position from position a in FIG. 3) The range up to c) is 0.70 to 6.04 m.
When the downlink area DA is set wider in this way, the reliability of the in-vehicle device 2 receiving the optical signal in the downlink direction is increased and the communication time is increased, so that the communication capacity in the downlink direction can be increased. .

In addition, the range of the uplink area UA (the range from the position b to the position c in FIG. 3) of the present embodiment is 3.04 to 6.04 m, and the position of the upstream end c is 1. It is extended upstream by 04m.
When the uplink area UA is set to be wider in this way, the reliability of the optical beacon 4 to receive the optical signal in the uplink direction is increased and the communication time is increased, so the communication capacity in the uplink direction can be expanded. .

[Configuration of in-vehicle device]
As shown in FIG. 3, the in-vehicle device 2 of the present embodiment includes an in-vehicle controller (communication control unit) 21 and an in-vehicle head 22, and inside the in-vehicle head 22, an optical transmitter 23 and an optical receiver. The part 24 is accommodated.
Among these, the optical transmission unit 23 includes a light emitting element that emits uplink light (an optical signal in the uplink direction) made of near infrared rays. The optical receiver 24 includes a light receiving element that receives downlink light (an optical signal in the downlink direction) made of near infrared rays transmitted to the downlink area DA.

The optical transmission unit 23 is a light emitting circuit that converts an upstream frame output from the in-vehicle controller 21 into a serial transmission signal having a predetermined transmission rate, and converts the output transmission signal into an optical signal in the uplink direction. And a light emitting element made of a diode or the like.
In the in-vehicle device 2 of the present embodiment, the optical transmission unit 23 is multi-rate capable of electro-optical conversion at two types of transmission speeds, high and low. The lower transmission speed is 64 kbps as in the conventional old vehicle-mounted device. The higher transmission speed may be 128 kbps, 192 kbps, 256 kbps, 384 kbps, 512 kbps, 1024 kbps, etc., but in this embodiment, it is assumed to be 256 kbps.

The light receiving unit 24 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.
In the in-vehicle device 2 of the present embodiment, the transmission speed of the optical signal received by the optical receiving unit 24 is 1024 kbps as in the conventional old in-vehicle device.

The in-vehicle controller 21 includes a computer device having a signal processing unit, a CPU, a memory, and the like, and has a function as a communication control unit that performs road-vehicle communication with the optical beacon 4.
The in-vehicle controller 21 stores a computer program for communication control in a storage device, and the CPU functions as the communication control unit when the CPU reads and executes the program.

Furthermore, the in-vehicle controller 21 generates traveling data of the host vehicle (for example, probe information that is traveling locus data in which passing positions and passing times are arranged in time series) as uplink data, and the optical transmission unit 23. It also has a function of transmitting to the uplink.
In this embodiment, since the uplink speed is increased, more probe information (the road section where the travel locus is recorded is lengthened, or the recording density of the passing position and the passing time in the same road section is increased. Information) can be transmitted.

In addition, the vehicle-mounted controller 21 of this embodiment may have a circuit configuration in which a simple control unit including an ASIC (Application Specific Integrated Circuit) is provided separately from the main body control unit including the CPU.
This simple control unit, for example, has a function of generating a low-speed uplink frame including identification information (hereinafter referred to as “vehicle ID”) of the own vehicle 20 when the optical receiver 24 receives some downlink frame. Have

[Definition of terms]
Here, terms used in this specification are defined.
Downstream frame DL: A general term for communication frames transmitted by the optical beacon 4 in downlink. The downlink frame DL includes a downlink frame DL1 and a downlink frame DL2 described later.
Uplink UL: A general term for communication frames transmitted by the in-vehicle device 2 through uplink. The upstream frame UL includes an upstream frame UL1 and an upstream frame UL2, which will be described later.

Downlink frame DL1: Refers to a downlink frame DL that the optical beacon 4 repeatedly transmits toward the downlink area DA before downlink switching described later.
Uplink frame UL1: The uplink frame UL transmitted by the vehicle-mounted device 2 in response to the reception of the downlink frame DL1 has a low transmission rate. Also referred to as “low speed frame UL1”.

Uplink frame UL2: An uplink frame UL transmitted by the in-vehicle device 2 in response to reception of the downlink frame DL1 and having a high transmission rate. Also referred to as “high-speed frame UL2”.
When the in-vehicle device 2 is a new in-vehicle device 2A (see FIG. 5) that supports high-speed uplink transmission, both the low-speed frame UL1 and the high-speed frame UL2 can be transmitted as the uplink frame UL, and the in-vehicle device 2 transmits the high-speed uplink. In the case of the old vehicle-mounted device 2B (see FIG. 5) that does not support the above, only the low-speed frame UL1 can be transmitted as the uplink frame UL.

Downstream frame DL2: A downlink frame DL (including a case of a series of frames) that the optical beacon 4 repeatedly transmits toward the downlink area DA after downlink switching described later.
ID storage frame: “Low speed” generated by the in-vehicle device 2 by writing the value of the vehicle ID of the host vehicle in a predetermined storage area (for example, “Vehicle ID” (see FIG. 7) in the header portion of the uplink information). This is the uplink frame UL1.

Loop frame: When the optical beacon 4 receives an ID storage frame, it refers to the downlink frame DL2 generated by writing the same value as the vehicle ID included in the frame in a predetermined storage area.
ID loopback: When the optical beacon 4 receives an ID storage frame, it refers to a process of generating a loopback frame and performing downlink transmission.

In addition, when the optical beacon 4 receives the ID storage frame, the downlink switching may be performed without continuously transmitting the return frame.
Loopback of vehicle ID: the vehicle-mounted device 2 generates an ID storage frame, uplink-transmits the generated ID storage frame, and the optical beacon 4 performs ID loopback to loop the vehicle ID to the vehicle-mounted device 2 that is the transmission source. This is a series of processing to be backed up.

Downlink switching: Refers to changing the substantial data content included in the downlink frame DL transmitted repeatedly by the optical beacon 4 before and after the switching.
In the present embodiment, the downlink frame DL2 after downlink switching includes a turn-back frame and a downlink frame DL2 including provision information for the vehicle corresponding to the vehicle ID. The provided information can include information such as traffic jam information, section travel time information, and event regulation information.

Such information is also provided to old in-vehicle devices that do not support high-speed uplink transmission.
However, in the optical beacon 4 (new optical beacon 4A) of the present embodiment, for example, signal information including switching timing of the signal lamp color at the intersection is provided as information provided for vehicles equipped with a new in-vehicle device that supports high-speed uplink transmission. Also, dedicated information predetermined for the new vehicle-mounted device can be provided, such as charging station information indicating a route to the nearest charging station, which is useful information when the vehicle 20 is an electric vehicle (FIGS. 9 and 10). reference).

Any area may be used as the data storage area of the vehicle ID of the uplink frame UL and the downlink frame DL, but for example, a “header part” or “lane notification information” can be used.
The lane notification information in the downlink frame DL includes a field for storing a vehicle ID for each lane R1 to R4 (FIG. 2), and a lane number can be assigned to each vehicle ID. For this reason, the vehicle-mounted device 2 of the vehicle 20 traveling in different lanes R1 to R4 reads which lane R1 to R4 the host vehicle is traveling by reading which of the vehicle IDs of the host vehicle is included in the storage field. Can be determined.

[Frame structure of upstream frame]
FIG. 7 is a frame configuration diagram of uplink information (uplink frame UL).
As shown in FIG. 7, the uplink frame UL is sequentially transmitted from the top in order to synchronize with the receiving side, a transmission control unit for synchronization (hereinafter referred to as “synchronizing unit”), a header part, an actual data part, and a CRC ( Cyclic Redundancy Check) transmission control unit (hereinafter referred to as “CRC unit”).

As shown in FIG. 7, in the case of the uplink frame UL, 1 byte is assigned to the synchronization part, 10 bytes are assigned to the header part, 59 bytes at the maximum are assigned to the actual data part, and 4 bytes ( 1 byte idle part + 2 bytes CRC + 1 byte final synchronization part).
The header portion of the uplink information includes storage areas such as “number of subsystem key information”, “vehicle ID”, “vehicle equipment type”, “information type”, and “last frame flag”.

In the “number of subsystem key information” (hereinafter sometimes abbreviated as “number of information”), the number of “subsystem key information” stored in order from the top of the actual data portion is stored.
That is, when the number of information is zero, “subsystem key information” is not included in the actual data portion, and when the number of information is “1”, one “subsystem key information” is included in the actual data portion. When the number of information is “n”, n “subsystem key information” is included in the actual data part.

The above-mentioned “subsystem key information” indicates that the optical beacon 4 is downlink information such as public vehicle priority system (PTPS), vehicle operation management system (MOCS), field express support system (FAST), and safe driving support system (DSSS). Key information for selecting the additional information.
The in-vehicle device 2 determines the contents of “subsystem key information” and “subsystem key information” according to which system of the UTMS standard the host vehicle is compatible with.

For example, the in-vehicle device 2 sets the value of the “number of subsystem key information” in the header part to “1” when the host vehicle corresponds to one system of the UTMS standard, and follows the standard of the one system. The “subsystem key information (1)” of the contents is stored in the actual data part.
In addition, when the host vehicle is compatible with two systems of the UTMS standard, the in-vehicle device 2 sets the value of the “number of subsystem key information” in the header part to “2”, and sets the standard of the two systems respectively. The “subsystem key information (1)” and “subsystem key information (2)” having the contents are stored in the actual data part.

  Note that the data format of the “subsystem key information” differs depending on the standard of each system and will not be described in detail. For example, in the case of a safe driving support system (DSSS), the brake state, the turn signal state, the hazard Information such as state, vehicle speed, traveling direction, acceleration / deceleration, and accelerator pedal position is included.

On the other hand, the optical beacon 4 determines which system included in the in-vehicle device 2 is included in the UTMS standard according to the type of “subsystem key information” included in the uplink information, and conforms to the standard of the system. The provided information is stored in the downlink frame DL2 after downlink switching and transmitted in downlink. This provided information may be referred to as “value service information” in the sense that it is provided as a price for subsystem key information.
Thus, the “subsystem key information” is used by the old and new optical beacons 4 to determine the type of provision information after downlink switching.

“Vehicle ID” is an area for storing a vehicle ID value generated by the in-vehicle device 2 by itself or automatically generated by the optical beacon 4. The in-vehicle device 2 stores the vehicle ID stored at the time of uplink transmission. Is stored in the vehicle ID of the header portion of the upstream frame UL1.
“In-vehicle device type” is an area for storing the type of the in-vehicle device 2, and “Information type” is an area for storing the type of uplink information. In the present embodiment, the values of these storage areas indicate whether the uplink transmission subject is new or old and whether the uplink information is high speed or low speed.

Specifically, when the in-vehicle device 2 (new in-vehicle device 2A) of the present embodiment transmits the low-speed uplink frame UL1, a predetermined value (eg, “6” ”) And a predetermined value (for example,“ 1 ”) indicating low speed is stored in“ Information Type ”.
Further, when the new in-vehicle device 2A transmits the high-speed uplink frame UL2, the new in-vehicle device 2A stores a predetermined value (for example, “6”) indicating the new in-vehicle device 2A in the “in-vehicle device type” and the high-speed in the “information type”. A predetermined value (for example, “4”) is stored.

Therefore, the optical beacon 4 (new optical beacon 4A) of the present embodiment is received from the new in-vehicle device 2A when the in-vehicle device type value of the received uplink frame UL is “6” and the information type value is “1”. If the value of the in-vehicle device type of the received uplink frame UL is “6” and the value of the information type is “4”, the high-speed frame from the new in-vehicle device 2A can be determined. It can be determined that it is UL2.
In the case of the old vehicle-mounted device 2B, since the value of the vehicle-mounted device type is set to other than “6”, the new light beacon 4A receives an uplink frame UL having a value of “vehicle-mounted device type” other than “6”. Can be determined to be the low-speed frame UL1 from the old vehicle-mounted device 2B.

When the new light beacon 4A completes reception of the low-speed frame UL1 from the new in-vehicle device 2A and the old in-vehicle device 2B, it generates a return frame in which the value of the vehicle ID included in the header part is stored in the lane notification information. Perform downlink switching with continuous transmission.
On the other hand, in this embodiment, the new light beacon 4A does not perform downlink switching when the reception of the high-speed frame UL2 from the new in-vehicle device 2A is completed. But you may employ | adopt the standard which performs downlink switching according to the completion of reception of the high-speed frame UL2.

As described above, in this embodiment, the completion of the reception of the low-speed frame UL1 from the new in-vehicle device 2A and the old in-vehicle device 2B is a condition for the new optical beacon 4A to perform downlink switching with continuous transmission of the return frame (the opportunity or Trigger).
The completion of the reception of the high-speed frame UL2 from the new in-vehicle device 2A is not a condition (an opportunity or a trigger) for the new light beacon 4A to continuously transmit the return frame or perform downlink switching.

The “final frame flag” is used to indicate which of the uplink frame groups is the final frame when the in-vehicle device 2 (which may be new or old) transmits an uplink frame group including a plurality of uplink frames UL. Storage area.
That is, the in-vehicle device 2 stores a predetermined flag value (for example, “1”) only in the “final frame flag” of the last frame among a plurality of uplink frames UL constituting the uplink frame group, and other uplink frames UL The flag value is not stored in the frame UL.

[Frame structure of downstream frame]
FIG. 8 is a frame configuration diagram of the downlink information (downlink frame DL).
As shown in FIG. 8, the frame configuration of the downlink frame DL is also composed of a synchronization portion, a header portion, an actual data portion, and a CRC portion in order from the top, as in the case of the frame configuration of the uplink frame UL (FIG. 7). .

In the case of the downlink frame DL, 1 byte is allocated to the synchronization unit, 5 bytes are allocated to the header unit, 123 bytes are allocated to the actual data unit, and 4 bytes are allocated to the transmission control unit (1 byte idle unit + 2 bytes). CRC + 1 byte final synchronization part) is allocated.
In the actual data portion of the downlink frame DL, any one of various information shown in FIG. 9 is stored as provision information for the vehicle 20.

Specifically, the optical beacon 4 (which may be old or new) includes “lane notification information” in the actual data portion of the downlink frame DL1 before downlink switching.
The optical beacon 4 corresponds to the subsystem key information uplinked from the vehicle-mounted device 2 in the actual data portion of the downlink frame DL2 after downlink switching, except when the downlink frame DL2 is a folded frame. The provided information is selected, and the selected provided information is included in the actual data part.

  The optical beacon 4 transmits the provision information in one downlink frame DL when the provision information fits in the capacity of the actual data part (123 bytes). If the provision information does not fit, the optical beacon 4 is provided in a plurality of downlink frames DL. Information may be sent.

As shown in FIG. 8, the storage area of “lane notification information” includes “vehicle ID”, “lane number”, “beacon identification flag”, and the like.
In the case of the downlink frame DL1 before downlink switching, the optical beacon 4 does not store a value in the “vehicle ID” of the “lane notification information”, but includes an ID storage frame from the in-vehicle device 2 and is included in the header portion thereof. The value of the vehicle ID to be stored is stored in the “vehicle ID” of the “lane notification information” to generate a return frame. The optical beacon 4 writes the lane number value corresponding to the beacon head 8 that acquired the uplink information in “lane number”.

The “beacon identification flag” is a storage area indicating whether or not the own device supports high-speed uplink reception.
That is, when the optical beacon 4 is the new optical beacon 4A that supports high-speed uplink reception, the optical beacon 4 stores a predetermined flag value (for example, “01”) in the “beacon identification flag” of the downlink frame DL. In the case of the old optical beacon 4B that does not support high-speed uplink reception, other values (for example, “00”) are stored in the “beacon identification flag” of the downlink frame DL.

  Therefore, the vehicle-mounted device 2 (new vehicle-mounted device 2A) of the present embodiment that supports high-speed uplink transmission uses the value of the “beacon identification flag” included in the “lane notification information” of the downlink frame DL to determine the optical beacon of the communication partner. 4 is a new light beacon 4A or an old light beacon 4B.

Note that the type of the downlink frame DL whose flag field is turned on (beacon identification flag = 01) may be both downlink frames DL1 and DL2 before and after downlink switching, or only the downlink frame DL2 after downlink switching. It may be.
Any of the new light beacons 4A of the present embodiment may be adopted, but the latter setting method is assumed in the following description. In the case of the latter setting method, the flag field of the downlink frame DL1 is set to off (beacon identification flag = 00), and the flag field of the downlink frame DL2 is set to on (beacon identification flag = 01) (see FIG. 6). .

The downlink frame group repeatedly transmitted from the optical transmission unit 10 of the optical beacon 4 after downlink switching is configured with 1 to 80 downlink frames DL2, and the transmission possible time for the repeated transmission is 250 msec.
The downlink frame DL2 is composed of an arbitrary number of frames corresponding to the amount of data to be transmitted in the downlink direction, and is repeatedly transmitted within the range of the transmittable time. Further, the transmission period of the downstream frame DL2 is about 1 msec.

Therefore, for example, when one significant data is composed of three downstream frames DL2, the transmission cycle is about 3 milliseconds, so that the data is repeated about 80 times within a predetermined transmittable time (250 milliseconds). Will be sent.
However, if the downlink area DA is expanded to the vicinity immediately below the beacon head 8 as in this embodiment (see FIG. 3), the number of downlink frames DL2 to be repeatedly transmitted can be increased up to about 200.

As shown in road-to-vehicle communication in FIG. 10 described later, when the optical beacon 4 performs downlink switching according to the ID storage frame, the time when the new in-vehicle device 2A performs uplink transmission of the high-speed frame DL2 and There are cases where the time zones for receiving the downlink frame DL2 overlap and the new in-vehicle device 2A cannot receive the first part of the downlink frame DL2.
Therefore, it is preferable that the transmittable period of the downlink frame DL2 after downlink switching by the new optical beacon 4A is (250 + α) m seconds (for example, 350 msec).

[Conventional road-to-vehicle communication]
FIG. 4 is a sequence diagram showing a conventional communication procedure performed in the communication area A.
Here, in FIG. 4, a frame with a white circle indicates that the frame does not include a vehicle ID (a frame having lane notification information without a vehicle ID), and a frame with a black circle indicates an ID loopback between road vehicles. Indicates that the frame is used (upstream “ID storage frame” or downstream “folding frame”). The same applies to FIGS. 9 and 10.

  In the following description of road-to-vehicle communication, it is assumed that the operation subject is the optical beacon 4 and the in-vehicle device 2, but the actual communication control is performed by the beacon controller (communication control unit) 7 of the optical beacon 4 and the in-vehicle device. The in-vehicle controller (communication control unit) 21 of the machine 2 executes. This also applies to the road-to-vehicle communication shown in FIGS.

As shown in FIG. 4, the optical beacon 4 (the old optical beacon 4B in the case of FIG. 4) continues to transmit the downlink frame DL1 at a predetermined transmission cycle from the beacon head 8 provided for each of the lanes R1 to R4. Yes. At this stage, the vehicle ID is not stored in the lane notification information.
When the vehicle 20 enters the downlink area DA, the vehicle-mounted device 2 (the old vehicle-mounted device 2B in the case of FIG. 4) receives the downlink frame DL1 including the lane notification information (no vehicle ID) or the other downlink frame DL1, It is detected that 20 has entered the communication area A of the optical beacon 4.

At this time, the in-vehicle device 2 generates a low-speed uplink frame UL1 (ID storage frame U0 in FIG. 4) in which the vehicle ID is stored in the header portion, and switches the communication of the own device from reception to transmission once to generate the low-speed Uplink frame UL1 is transmitted in uplink, and then the communication of the own device is returned from transmission to reception.
When there is information to be provided to the optical beacon 4 such as travel time information, the information is stored in the actual data portion of the ID storage frame U0.

When the ID storage frame U0 is properly received in the optical beacon 4 through the CRC check of the received frame, etc., the optical beacon 4 starts the repeated transmission of the downlink frame DL2 after switching the downlink within 10 milliseconds at the latest. To do.
A plurality of downlink frames DL2 repeatedly transmitted after downlink switching includes a plurality of loopback frames (downlink frames DL2 with black circles) continuously transmitted at the head portion, and downlink frames including predetermined provision information repeatedly transmitted thereafter. It consists of DL2.

This repeated transmission of the downlink frame DL2 is repeated as much as possible within the predetermined time.
Also, as shown in FIG. 4, the return frame (downlink frame DL2 with a black circle) is a series of a plurality of downlink frames DL2 (for example, five downlink frames DL2) that constitute downlink information during the transmission period of provided information. Conventionally, it is included only at the beginning of a series of a plurality of downlink frames DL2, and is repeatedly transmitted (every 5 frames in the example of FIG. 4).

In addition, since a series of downlink frames DL2 constituting the downlink information can be stored up to 80, the return frames (downlink frames DL2 with black circles) are stored at a rate of one in 80 frames in the least frequent case. Will be.
The in-vehicle device 2 receives a plurality of downlink frames DL2 from the optical beacon 4, and determines whether or not any of the plurality of downlink frames DL2 includes lane notification information in which the vehicle ID of the host vehicle is written. To do.

When the determination result is affirmative, the in-vehicle device 2 confirms that the loopback of the vehicle ID of the own vehicle has been successful, and maintains the communication of the own device as received at this time.
Conversely, while the determination result is negative, the in-vehicle device 2 determines that the loopback of the vehicle ID of the host vehicle is not successful, switches the communication of the host device from reception to transmission, Retransmit UL1. In this case, the in-vehicle device 2 transmits the uplink frame UL1 again after a predetermined time (for example, 30 milliseconds) has elapsed after the transmission of the previously transmitted uplink frame UL1. The in-vehicle device 2 repeats this retransmission operation until the vehicle ID loopback is successful.

[Problems in mixed situations]
FIG. 5 is a diagram illustrating a mixed state of old and new optical beacons 4A and 4B and in-vehicle devices 2A and 2B.
As shown in FIG. 5, the new optical beacon 4A supports uplink reception not only at a low transmission rate (64 kbps) but also at a high transmission rate (for example, 256 kbps). The optical beacon 4 of this embodiment corresponds to the new optical beacon 4A.
Similarly, the new in-vehicle device 2A supports uplink transmission not only at a low transmission rate (64 kbps) but also at a high transmission rate (for example, 256 kbps). The in-vehicle device 2 of the present embodiment corresponds to the new in-vehicle device 2A.

In contrast, the old optical beacon 4B is an optical beacon that performs only uplink reception at a low transmission rate (64 kbps), that is, an optical beacon that does not support uplink reception at a high transmission rate (for example, 256 kbps). It is.
Similarly, the old in-vehicle device 2B is an in-vehicle device that performs only uplink transmission at a low transmission rate (64 kbps), that is, an in-vehicle device that does not support uplink transmission at a high transmission rate (for example, 256 kbps). .

As described in the definition of terms above, “DL1” in FIG. 5 indicates a downlink frame transmitted by the old and new optical beacons 4A and 4B before downlink switching, and “UL1” in FIG. 5 indicates the downlink frame DL1. In response to reception, the old and new vehicle-mounted devices 2A and 2B indicate low-speed frames that can be transmitted, and “UL2” in FIG. 5 indicates a high-speed frame that can be transmitted only by the new vehicle-mounted device 2A.
Further, “DL2” in FIG. 5 indicates a downlink frame transmitted by the old and new optical beacons 4A and 4B after downlink switching.

Here, it is assumed that the new light beacon 4A and the new in-vehicle device 2A perform road-to-vehicle communication. When the new and old types of the optical beacon 4 cannot be discriminated, the new in-vehicle device 2A performs uplink transmission at a low speed in order to reliably receive and receive the uplink frame.
In this case, since the transmission speed in the downlink direction is “1024 kbps” in both the old and new cases, the new in-vehicle device 2A only receives the downlink frame DL1 from the new optical beacon 4A, and the communication partner is the new optical beacon 4A. I can't detect that.

As described above, if the new vehicle-mounted device 2A cannot recognize that it is communicating with the new optical beacon 4A while passing through the downlink area DA of the new optical beacon 4A, it is possible to perform high-speed uplink transmission. The in-vehicle device 2A performs uplink transmission at a low speed for the new optical beacon 4A, and the uplink speed cannot be increased.
Therefore, in the present embodiment, beacon identification information (for example, “beacon identification flag” in FIG. 8) indicating that the own apparatus is the new optical beacon 4A corresponding to high-speed uplink reception is transmitted to the downlink frame DL2. Can be included.

Specifically, as described above, a flag field indicating the new and old types of the optical beacon 4 is previously stored in the “lane notification information” (or “header portion”) of the downlink frame DL2 to be transmitted by the optical transmission unit 10 in the downlink. Define it.
The beacon controller 7 turns on the flag field of the downlink frame DL2 when operating the own apparatus as the new optical beacon 4A, and sets the flag of the downlink frame DL2 when operating the own apparatus as the old optical beacon 4B. Turn off the field.

When the flag field of the received downlink frame DL2 is on, the new in-vehicle device 2A can determine that the communication partner is the new optical beacon 4A, and when it is off or when the flag field cannot be detected, It can be determined that the communication partner is the old optical beacon 4B.
The new light beacon 4A may set the flag field to ON for both the downlink frames DL1 and DL2, but in this embodiment, the flag field is set to ON only for the downlink frame DL2 (see FIG. 6). ).

However, if the low-speed frame UL1 is always included in the upstream frame group, the new in-vehicle device 2A can communicate with both types of optical beacons 4 without determining the new and old types of the optical beacon 4 of the communication partner. It is.
The reason is that if the low-speed frame UL1 is used, both the old and new optical beacons 4A and 4B can communicate with each other as usual, and the old optical beacon 4B is able to communicate with other frames in the upstream frame group evenly as the high-speed frame UL2. This is because there is no particular problem.

Therefore, the new in-vehicle device 2A of the present embodiment may be a type that does not perform the new / old determination of the optical beacon 4 of the communication partner, or may be a type that performs the new / old determination.
The former type new vehicle-mounted device 2A does not perform the new / old determination of the optical beacon 4 based on the flag field of the downlink frame DL2, and continuously transmits the uplink frame UL2 after the low-speed frame UL1. The latter type new vehicle-mounted device 2A transmits the high-speed frame UL2 only when the communication partner is determined to be the new optical beacon 4A as a result of the new / old determination of the optical beacon 4 based on the flag field of the downlink frame DL2.

[Upward compatibility control of new light beacons]
FIG. 6 is a flowchart showing the upward compatible control performed by the beacon controller 7 of the new optical beacon 4A, which is the optical beacon 4 of the present embodiment.
As shown in FIG. 6, the beacon controller 7 of the new optical beacon 4A repeatedly transmits the downlink frame DL1 with the flag field set to OFF repeatedly in a predetermined cycle (step ST1 in FIG. 6).

In this state, the beacon controller 7 determines whether or not the uplink frame UL1 (low speed frame UL1) has been received (step ST2 in FIG. 6), and continues the downlink transmission in step ST1 until the reception is detected. To do.
When detecting the reception of the upstream frame UL1, the beacon controller 7 determines whether or not the transmission subject of the received upstream frame UL1 is the new in-vehicle device 2A corresponding to a high transmission rate (256 kbps in this embodiment). Determination is made (step ST3 in FIG. 6).

The determination in step ST3 can be made, for example, depending on whether the transmission rate of the upstream frame UL1 received by the optical receiver 11 is high or low. In this case, if the received upstream frame UL1 is high speed, it can be determined that the transmission subject is the new in-vehicle device 2A, and if it is low speed, it can be determined that the transmission subject is the old in-vehicle device 2B.
In addition, the in-vehicle controller 21 of the new in-vehicle device 2A may adopt a standard that includes the in-vehicle device identification information indicating that the own device is the new in-vehicle device 2A that supports high-speed uplink transmission in the uplink frame UL1.

Specifically, a flag field (for example, “vehicle equipment type” in FIG. 7) indicating the new and old types of the in-vehicle device 2 is defined in advance in the header portion of the uplink frame UL1 that the optical transmission unit 23 performs uplink transmission. .
When the in-vehicle controller 21 of the new in-vehicle device 2A operates the own device as the new in-vehicle device 2A, the on-vehicle controller 21 turns on the flag field of the uplink frame UL1 that is transmitted at high speed, and operates the own device as the old in-vehicle device 2B. In this case, the flag field of the upstream frame UL1 is turned off.

  Therefore, if such a standard is adopted, the beacon controller 7 can determine that the transmission subject is the new in-vehicle device 2A when the flag field of the received upstream frame UL1 is on, and the upstream frame UL1 When the flag field is off or when the flag field cannot be detected, it can be determined that the transmission subject is the old vehicle-mounted device 2B.

When the determination result of step ST3 is affirmative, that is, when the transmission subject of the uplink frame UL1 is the new in-vehicle device 2A, the beacon controller 7 performs downlink transmission for the new in-vehicle device after downlink switching ( Step ST4 in FIG. 6).
Downlink transmission for new in-vehicle equipment includes provision information for new in-vehicle equipment such as signal information and charging station information in addition to provision information for old in-vehicle equipment such as traffic jam information, section travel time information and event regulation information This is done by repeatedly transmitting the downstream frame DL2.

When the determination result of step ST3 is negative, that is, when the transmission subject of the uplink frame UL1 is the old vehicle-mounted device 2B, the beacon controller 7 performs downlink transmission for the old vehicle-mounted device after downlink switching ( Step ST5 in FIG. 6).
This downlink transmission for the old in-vehicle device is performed by repeatedly transmitting only the downlink frame DL2 including provision information for the old in-vehicle device such as traffic jam information, section travel time information, and event regulation information.

In the downlink frame DL2 used for downlink transmission for the new vehicle-mounted device, the flag field of the downlink frame DL2 is set to ON (beacon identification flag = 01) (step ST4 in FIG. 6).
Further, in the downlink frame DL2 used for downlink transmission for the old vehicle-mounted device, the flag field of the downlink frame DL2 is set to off (beacon identification flag = 00) (step ST5 in FIG. 6).

  As described above, downlink transmission of the downlink frame DL2 in steps ST4 and ST5 performed after downlink switching is performed until a predetermined time (for example, 250 milliseconds) elapses from the downlink switching time point.

[Road-to-vehicle communication when no transmission interruption period is provided]
FIG. 9 is a sequence diagram showing road-to-vehicle communication when the new in-vehicle device 2A fails in the ID confirmation because the new in-vehicle device 2A transmits the upstream frames UL1 and UL2 without providing the “transmission interruption period”.

In FIG. 9, U0 to U3 indicate a plurality of upstream frames (upstream frame groups) UL1 and UL2 that are transmitted by the new vehicle-mounted device 2A that has detected the downstream frame DL1.
In FIG. 9, the number of frames in the upstream frame group is four, but the number of frames is not limited to four. For example, in the uplink frame group, three or more high-speed frames UL2 may be transmitted, or only one high-speed frame UL2 having a relatively long data length may be transmitted.

The uplink frame U0 that is not hatched indicates that the transmission rate is “low speed frame UL1” (64 kbps in this embodiment), and the uplink frames U1 to U3 that are hatched have a high transmission rate ( In the present embodiment, it indicates that it is a “high-speed frame UL2” of 256 kbps).
Note that the illustrated distinction between the low-speed frame U0 and the high-speed frames U1 to U3 is the same in the road-to-vehicle communication in FIG.

When transmitting a large amount of data such as probe information in the uplink, the data cannot often be stored in the low-speed frame U0. Therefore, in the example of FIG. 9, the new in-vehicle device 2A transmits a total of three high-speed frames U1 to U3 following the low-speed frame U0.
Specifically, when the new in-vehicle device 2A receives the downlink frame DL1 in the downlink area DA, the new vehicle-mounted device 2A immediately uplinks the low speed frame U0 at a low speed, and subsequently uplinks the high speed frames U1 to U3.

In the example of FIG. 9, it is assumed that the new in-vehicle device 2A does not determine whether the communication partner is new or old. Therefore, continuous transmission of the low-speed frame U0 and the high-speed frames U2 to U4 is executed regardless of whether the communication partner of the new in-vehicle device 2A is the new optical beacon 4A or the old optical beacon 4B.
The optical beacon 4 of the communication partner of the new in-vehicle device 2A extracts the vehicle ID value from its header part upon completion of reception of the low-speed frame U0 included in the upstream frame group, and stores the value in the lane notification information. Perform frame continuous transmission and downlink switching.

That is, when the optical beacon 4 is the new optical beacon 4A, when it is detected that the value of “vehicle equipment type” in the low-speed frame U0 is “6” and the value of “information type” is “1”, Perform continuous transmission and downlink switching.
Further, when the optical beacon 4 is the old optical beacon 4B, the type determination as described above cannot be performed. Therefore, when the reception of the low-speed frame U0 is completed, the return frame is continuously transmitted and the downlink is switched as usual. I do.

As described above, when the old optical beacon 4B receives the low-speed frame U0, which is an ID storage frame, under the assumption that large-capacity uplink transmission is not performed, it can immediately switch the downlink by continuously transmitting the return frame. The new light beacon 4A also immediately switches the downlink when the reception of the low-speed frame U0 is completed in order to maintain compatibility with the old vehicle-mounted device 2B.
Therefore, as shown in FIG. 9, depending on the transmission period of the high-speed frames U1 to U3 (U3 in the example of FIG. 9), the return frame may reach the new in-vehicle device 2A during the transmission.

In this case, when the new in-vehicle device 2A adopts the half-duplex communication method, the new light beacon 4A has already recognized the vehicle ID even though the return frame has arrived at the light receiving unit 24. Cannot be detected by the new in-vehicle device 2A.
In this case, as indicated by a broken line in FIG. 9, the new in-vehicle device 2 </ b> A retransmits the large-capacity uplink frame groups U <b> 0 to U <b> 3 including the low-speed frame U <b> 0 that is the ID storage frame.

This phenomenon is more likely to occur as the amount of provision information other than the lane notification information to be included in the downlink information increases.
The reason is that, as the amount of data of the provided information increases, the frequency of including the return frame in the downlink frame DL2 repeatedly transmitted by the new optical beacon 4A decreases, and thus the probability that the new in-vehicle device 2A cannot recognize the loopback increases. is there.

Therefore, for the return frame that is downlink transmitted periodically after every downlink switching (every 5 frames in the example of FIG. 9), the new in-vehicle device 2A has a timing that overlaps with the transmission period of the uplink frame groups U0 to U3. The possibility of receiving may be reduced.
In this case, even after retransmitting the uplink frame groups U0 to U3, the new in-vehicle device 2A does not notice the return frame, and uplink transmission (retransmission) of the uplink frame groups U0 to U3 is continued unnecessarily.

Then, as the number of frames transmitted by the new in-vehicle device 2A increases, the possibility that transmission of the uplink frame groups U0 to U3 is continued in the uplink area UA without noticing the return frame increases.
Therefore, the new in-vehicle device 2A that tries to uplink more data to the new optical beacon 4A greatly loses the opportunity to receive the downlink frame DL2 that is transmitted only for a limited period (for example, 250 milliseconds), In such a case, there is a possibility that an unreasonable result may occur such as passing through the communication area A without receiving the downlink frame DL2.

[Road-to-vehicle communication when there is a transmission interruption period]
FIG. 10 is a sequence diagram showing road-to-vehicle communication when the new in-vehicle device 2A succeeds in ID confirmation because the new in-vehicle device 2A transmits the upstream frames UL1 and UL2 with a “transmission interruption period”.
In the example of FIG. 10, when the new in-vehicle device 2A continuously transmits the high-speed frames U1 to U3 after the low-speed frame U0, by providing a “transmission interruption period” between the first low-speed frame U0 and the high-speed frame U1, The above-mentioned problems associated with the failure of the return frame are solved.

This “transmission interruption period” is set to a predetermined time length necessary for the new in-vehicle device 2A to confirm the success of the loopback of the vehicle ID performed by the own device and to prepare for transmission of the high-speed frame U1. The
For example, it is assumed that the new light beacon 4A takes about 5 to 10 milliseconds from the reception of the ID storage frame U0 to the start of transmission of the downlink frame DL2, and the new in-vehicle device 2A confirms the loopback of the vehicle ID of the own vehicle, Assuming that the delay time required to start transmission of the high-speed frame U1 is 10 milliseconds, the transmission interruption period may be set in a range of approximately 15 to 20 milliseconds.

If this transmission interruption period is provided, the return frame continuously transmitted after downlink switching reaches the optical receiver 24 of the new in-vehicle device 2A during the period, and the new in-vehicle device 2A receives the received return frame. By determining whether or not the included vehicle ID matches that of the own device, the success of the loopback of the vehicle ID can be confirmed.
After the above confirmation, the new in-vehicle device 2A continuously transmits the high-speed frames U1 to U3, and after the continuous transmission ends, switches the communication of the own device to reception.

Thus, according to the new vehicle-mounted device 2A that provides the transmission interruption period between the low-speed frame U0 and the high-speed frame U1, the new light beacon 4A has recognized the vehicle ID by the return frame received from the new light beacon 4A during the transmission interruption period. It can be surely detected.
For this reason, it is possible to prevent the loss of the opportunity to receive the downstream frame DL2 due to the new in-vehicle device 2A continuing uselessly transmitting a plurality of upstream frames U0 to U1.

As a method for setting the transmission interruption period, a method in which the in-vehicle controller 21 continues to output a signal indicating the light-off state to the optical transmission unit 23 during the period, or the light transmission element 23 of the optical transmission unit 23 at the beginning of the period is set. There is a method in which power supply is stopped and extinguished, and power supply to the light emitting element is restarted and light is emitted again at the end of the period.
Moreover, you may employ | adopt the method of reducing the power of a light emitting element to such an extent that an optical signal cannot reach | attain the optical beacon 4. In this way, there is an advantage that power at the time of re-emission of the light emitting element can be quickly returned and disturbance of the synchronization part on the head side of the upstream frame U1 can be suppressed.

On the other hand, if the low-speed frame U0 that is the ID storage frame does not reach the new light beacon 4A for some reason (such as the windshield of the vehicle 20 being clouded), the light beacon 4 does not return the return frame. The in-vehicle device 2A cannot confirm the success of the loopback.
Therefore, if the new in-vehicle device 2A fails to confirm the success of the loopback during the transmission interruption period, only the low-speed frame U0 that is the ID storage frame is retransmitted to the optical transmission unit 23 as shown by the broken line in FIG. The transmission interruption period is after the low-speed frame U0 that is transmitted and retransmitted.

  Accordingly, when the new light beacon 4A can properly receive the retransmitted low-speed frame U0, the success of the vehicle ID loopback is confirmed by the return frame received from the new light beacon 4A during the transmission interruption period, as described above. be able to.

In the example of FIG. 10, it is preferable that the data size of the low-speed frame U0 that is the first upstream frame is as small as possible. For example, it is preferably smaller than at least one of the high-speed frames U1 to U3.
More preferably, for example, the data size of the low-speed frame U0 is reduced by minimizing the data stored in the low-speed frame U0 such as vehicle ID information, travel time between beacons, and the service type supported by the new in-vehicle device 2A. Is preferably set to the minimum (for example, about 5 bytes in the actual data portion) among the plurality of upstream frames U0 to U3 transmitted in one communication.

  The reason for this is that if the frame length of the low-speed frame U0 that can be retransmitted is long, the remaining time in which uplink transmission can be performed when the low-speed frame U0 is retransmitted is reduced accordingly, and uplink transmission is performed. This is because, for example, the last high-speed frame U3 among the plurality of high-speed frames U1 to U3 to be performed may not normally reach the new light beacon 4A.

  In the example of FIG. 10, the new in-vehicle device 2A receives a new optical beacon corresponding to high-speed uplink reception by the communication partner based on the beacon identification flag included in the downlink frame DL1 or the downlink frame DL2 received during the transmission interruption period. It may be determined whether the old optical beacon 4B is 4A or non-compliant, and whether to transmit the high-speed frames U1 to U3 after the transmission interruption period may be determined according to the determination result.

As described above, the communication partner of the new optical beacon 4A is preferably the new in-vehicle device 2A (FIG. 10) that performs uplink transmission with a transmission interruption period between the low-speed frame U0 and the high-speed frames U1 to U3. The new vehicle-mounted device 2A (FIG. 9) that continuously transmits the upstream frames U0 to U3 without providing a transmission interruption period may be used.
The reason for this is that if the number of frames and the transmission time of the high-speed frame UL2 are set to be small, the new in-vehicle device 2A displays the folded frame that is downlinked corresponding to the low-speed frame UL1, even without providing a transmission interruption period. It is because it can receive appropriately.

[Example of receiving all or part of a high-speed frame]
FIG. 11 is an explanatory diagram showing an example of the downlink upstream portion DA0 that is a portion of the downlink region DA located on the upstream side of the uplink region UA.
In FIG. 11, an alternate long and short dash line boundary DB0 indicates an upstream boundary of the downlink area DA in which the new and old vehicle-mounted devices 2 can receive the downlink frame DL1 before the downlink switching from the new optical beacon 4A.

A broken boundary line UB1 indicates an upstream boundary of the uplink area UA in which the new light beacon 4A can receive the low-speed frame UL1 from the old and new vehicle-mounted devices 2. A solid boundary line UB2 indicates an upstream boundary of the uplink area UA in which the new optical beacon 4A can receive the high-speed frame UL2 from the new vehicle-mounted device 2A.
The above “receivable” means that an upstream frame UL or downstream frame DL having a light amount corresponding to the minimum reception sensitivity can be received at a predetermined bit error rate (for example, 10 ^{−5 in the} standard value) or less. .

In FIG. 11, P0 is an intersection position (hereinafter referred to as “downlink upstream end”) between the upstream boundary DB0 and a predetermined installation height H (for example, H = 1.0 m) of the in-vehicle device 2.
In FIG. 11, P1 is an intersection position (= first uplink upstream end) between the upstream boundary UB1 and the installation height H, and P2 is an intersection position (= second) between the upstream boundary UB2 and the installation height H. Upstream upstream end).

In the new optical beacon 4A of the present embodiment, position setting is performed such that the second uplink upstream end P2 is on the upstream side (may be coincident) with respect to the first uplink upstream end P1.
The reason is that if the first uplink upstream end P1 is upstream of the second uplink upstream end P2, the range between the upstream ends P1 and P2 indicates that the new optical beacon 4A can receive the low-speed frame UL1, but the high-speed frame This is because the “insensitive area” (see FIG. 11 of Patent Document 1) in which UL2 cannot be received, and the new optical beacon 4A cannot appropriately receive the high-speed frame UL2.

As shown in FIG. 11, the downlink upstream end P0 of the optical beacon 4 is configured so that uplink transmission can be reliably performed when the vehicle-mounted device 2 approaches the uplink area UA. In the example, it may be set upstream of the second uplink upstream end P2).
In this case, a downlink upstream portion DA0, which is a portion of the downlink region DA located on the upstream side of the upstream boundary UB2 of the uplink region UA, is formed. Accordingly, when the new in-vehicle device 2A enters the downlink upstream part DA0, the new in-vehicle device 2A receives the downlink frame DL1 and starts transmitting the low-speed frame UL1.

On the other hand, the uplink area UA is an area satisfying communication quality with a bit error rate of 10 ⁻⁵ or less. Therefore, even if the new in-vehicle device 2A transmits the low speed frame UL1 in the downlink upstream part DA0, the new light beacon 4A cannot normally receive the low speed frame UL1.
However, the low-speed frame UL1 that is first transmitted by the new vehicle-mounted device 2A has a relatively small data size and is often only one frame. For this reason, although the probability is not high, there is a possibility that the new optical beacon 4A receives the low-speed frame UL1 transmitted in the downlink upstream part DA0.

In this case, since the new optical beacon 4A performs downlink switching and transmits the downlink frame DL2 storing the vehicle ID of the new vehicle-mounted device 2A, the new vehicle-mounted device 2A receives the downlink frame DL2 in response to the reception of the downlink frame DL2. Start sending.
Since the high-speed frame UL2 has a relatively large data size and a large number of frames, the position of the new in-vehicle device 2A in the vehicle traveling direction has not reached the second uplink upstream end P2 at the start of transmission of the high-speed frame UL2. In this case, there is a possibility that the new optical beacon 4A cannot properly receive all the high-speed frames UL2.

For example, when the new vehicle-mounted device 2A starts transmission of the high-speed frame UL2 in the vicinity of the upstream side of the second uplink upstream end P2, a plurality of high-speeds in the latter half of the upstream frame group composed of the plurality of high-speed frames UL2 Although the frame UL2 may be received, there is a high possibility that the new optical beacon 4A cannot receive the high-speed frame UL2 for the first several frames.
As described above, when the new vehicle-mounted device 2A transmits the low-speed frame UL1 in the downlink upstream portion DA0, the position setting is performed so that the second uplink upstream end P2 is upstream or coincides with the first uplink upstream end P1. However, the new light beacon 4A may not be able to receive some high-speed frames UL2.

Therefore, in the present embodiment, the new in-vehicle device 2A executes processing for retransmitting the high-speed frame UL2 (hereinafter referred to as “retransmission processing”). Thereby, even if the new optical beacon 4A cannot receive the high-speed frame UL2 because the new in-vehicle device 2A starts transmission of the high-speed frame UL2 in the downlink upstream section DA0, the new optical beacon 4A can be Increase the likelihood of properly receiving UL2.
Hereinafter, there are some specific examples of such retransmission processing. Hereinafter, embodiment of new vehicle equipment 2A and new light beacon 4A is explained for every example.

[First Embodiment]
The new optical beacon 4A according to the first embodiment executes a process of including reception information that can identify the high-speed frame UL2 that has not been received by the own apparatus in a downlink frame that is downlink transmitted.
Then, the new in-vehicle device 2A executes processing (retransmission processing) for retransmitting a predetermined high-speed frame UL2 when a predetermined condition is satisfied. When the received information is included in the downlink received downlink, the new in-vehicle device 2A of the first embodiment executes a process of retransmitting the high-speed frame UL2 from which the new optical beacon 4A has not been received based on the received information. To do.

FIG. 12 is a frame configuration diagram of the high-speed frame UL2 (uplink information) in the first embodiment.
As shown in FIG. 12, the high-speed frame UL2 of the first embodiment includes a “frame number” storage area in the header. In addition, since the other structure of the high-speed frame UL2 of 1st Embodiment is the same as the upstream frame UL shown in FIG. 7, the description is abbreviate | omitted.

The “frame number” is an area for storing the frame number of the high-speed frame UL2 included in the uplink frame group when an uplink frame group including a plurality of high-speed frames UL2 is transmitted.
That is, the new vehicle-mounted device 2A stores the frame numbers of the plurality of high-speed frames UL2 constituting the uplink frame group in the “frame number”. For example, the new in-vehicle device 2A of the first embodiment stores “1” in the “frame number” of the high-speed frame UL2 to be uplink-transmitted first among the plurality of high-speed frames UL2 constituting the uplink frame group, The serial number after “2” is stored in the “frame number” of the high-speed frame UL2 for uplink transmission after the second.

FIG. 13 is a frame configuration diagram of the downlink frame DL2 (downlink information) after downlink switching in the first embodiment.
As illustrated in FIG. 13, the downlink frame DL2 of the first embodiment includes a plurality of “reception state identification flag” storage areas in the storage area of “lane notification information”, except in the case of a return frame. In addition, since the other structure of downlink frame DL2 of 1st Embodiment is the same as downlink frame DL shown in FIG. 8, the description is abbreviate | omitted.

A capacity corresponding to the maximum number of frames of the high-speed frame UL2 that can be included in the uplink frame group transmitted by the new in-vehicle device 2A is allocated to the storage areas of the plurality of “reception state identification flags” in the first embodiment. . For example, when the maximum number of frames is 16, 2 bytes (16 bits) are allocated to the storage areas of a plurality of “reception state identification flags”.
Each bit is assigned a plurality of high-speed frames UL2 included in the upstream frame group. In the illustrated example, the “reception state identification flag (1)” is assigned the high-speed frame UL2 having the frame number “1” of the upstream frame group, and the “reception state identification flag (n)” is the frame of the upstream frame group. The high-speed frame UL2 with the number “n” is assigned. Hereinafter, “n” of the “reception state identification flag (n)” is referred to as a flag ID.

Each “reception state identification flag” is a storage area for indicating whether or not the new optical beacon 4A has received the allocated high-speed frame UL2.
Specifically, the new light beacon 4A stores a predetermined initial value (for example, “0”) in advance in all “reception state identification flags” of the downlink frame DL2. The new light beacon 4A stores a predetermined flag value (for example, “1”) only in the “reception state identification flag” corresponding to the received high-speed frame UL2 among the plurality of high-speed frames UL2 constituting the upstream frame group. To do. Accordingly, the new optical beacon 4A includes the “reception state identification flag” storing the flag value, that is, information that can identify the high-speed frame UL2 that the own device can receive in the downlink frame DL2 as the reception information.

The new in-vehicle device 2A that has received the downlink frame DL2 including the received information in the downlink receives the communication partner's new optical beacon 4A for each of the plurality of high-speed frames UL2 uplink-transmitted by the own device according to the value of the “reception state identification flag”. Can be recognized.
That is, when the flag value is stored in the “reception state identification flag”, the new in-vehicle device 2A can recognize that the new optical beacon 4A of the communication partner has received the corresponding high-speed frame UL2, When the value of the “reception state identification flag” is an initial value, it can be recognized that the corresponding new high-speed frame UL2 cannot be received by the communication partner's new optical beacon 4A.

[Contents of processing performed by Shinko Beacon]
FIG. 14 is a flowchart illustrating an example of processing executed by the beacon controller 7 of the new light beacon 4A according to the first embodiment.
As shown in FIG. 14, the beacon controller 7 always determines whether or not uplink data has been acquired from the optical receiver 11 (step ST11). If uplink data is acquired, the uplink data is further determined. Is a high-speed frame UL2 (step ST12).

The determination in step ST12 can be made based on, for example, the value of “information type” (see FIG. 12) included in the header portion of the uplink data. Specifically, the beacon controller 7 determines that the frame is the high-speed frame UL2 if a predetermined value (in this case, “4”) indicating high speed is stored in the “information type”. If a predetermined value (in this case, “1”) indicating low speed is stored, it is determined that the frame is not the high speed frame UL2.
If the determination result of step ST12 is negative, the beacon controller 7 returns the process to before step ST11.

When the determination result in step ST12 is affirmative, the beacon controller 7 acquires the value of “frame number” (see FIG. 12) included in the header portion of the acquired uplink data (high-speed frame UL2) (step ST13). ).
Then, the beacon controller 7 stores the flag value (“1” here) in the “reception state identification flag” corresponding to the downlink frame DL2 corresponding to the acquired “frame number” value (step ST14). For example, when the acquired value of “frame number” is “3”, “1” is stored in “reception state identification flag (3)” having the same flag ID as this value.

Next, the beacon controller 7 causes the optical transmission unit 10 to perform downlink transmission of the downlink frame DL2 (step ST15). Thereafter, the beacon controller 7 determines whether or not the transmittable period of the downlink frame DL2 (here, 350 msec) has elapsed (step ST16).
If the determination result of step ST16 is negative, the beacon controller 7 returns the process to before step ST11. Thereby, beacon controller 7 repeats processing of Steps ST11-ST15 about received high-speed frame UL2 among a plurality of high-speed frames UL2 which constitute an uplink frame group.

If the determination result in step ST16 is affirmative, the beacon controller 7 returns the values of all “reception state identification flags” of the downlink frame DL2 to the initial values (here, “0”) (step ST17), and processing Exit.
In step ST16 and step ST17, the condition for returning the “reception state identification flag” to the initial value is that the transmittable period of the downlink frame DL2 has passed, but the downlink frame DL2 can be transmitted. Before the period elapses, the following condition 1 or 2 may be satisfied.
Condition 1: The low-speed frame UL1 is received from the new in-vehicle device 2A. Condition 2: The low-speed frame UL1 is received from either the new in-vehicle device 2A or the old in-vehicle device 2B. As a condition for returning “” to the initial value, an independent time (for example, 100 milliseconds) elapses from any one of the following reference points 1 to 4 without using the transmittable period as described above. It is good also as a condition.
Reference point 1: Time point when the high speed frame UL2 is received Reference point 2: Time point when the high speed frame UL2 having the same vehicle ID as the low speed frame UL1 is received for the first time Reference point 3: Time point when the low speed frame UL1 is received from the new in-vehicle device 2A Reference Point 4: Time when flag value “1” is set in any “reception state identification flag” Note that in the above-described conditions 1 and 2 and reference point 3, whether the in-vehicle device is new or old is determined by the low-speed frame UL1. The determination may be made based on the value of “in-vehicle device type” included in.

[Processing content to be executed by the new in-vehicle device]
FIG. 15 is a flowchart illustrating an example of processing executed by the in-vehicle controller 21 of the new in-vehicle device 2A according to the first embodiment.
As shown in FIG. 15, the in-vehicle controller 21 always determines whether or not downlink data has been acquired from the light receiving unit 24 (step SS11). Is a downlink frame DL2 after downlink switching (step SS12).

The determination in step SS12 can be performed based on, for example, information stored in the actual data portion of the downlink data. Specifically, when the provided information is included in the actual data part of the downlink data, the in-vehicle controller 21 determines that the downlink frame DL2 after the downlink switching is included, and the provided information is not included. Is determined not to be a downlink frame DL2 after downlink switching.
The determination in step SS12 may be made based on the “vehicle ID” of “lane notification information” included in the actual data portion of the downlink data. In this case, when the vehicle ID of the host vehicle is set in the “vehicle ID” of the downlink data, the in-vehicle controller 21 determines that the downlink frame DL2 has been switched to the downlink, and the vehicle of the host vehicle. If the ID is not set, it may be determined that it is not the downlink frame DL2 after downlink switching.
When the determination result of step SS12 is negative, the in-vehicle controller 21 returns the process to before step SS11.

If the determination result in step SS12 is affirmative, the in-vehicle controller 21 determines whether or not there is a high-speed frame UL2 that the new light beacon 4A could not be received (step SS13).
In step SS13, the initial value is stored among all “reception state identification flags” (see FIG. 13) included in the “lane notification information” of the acquired downlink data (downstream frame DL2). This can be done depending on whether or not an “identification flag” exists.

Specifically, when there is a “reception state identification flag” in which the initial value is stored, the in-vehicle controller 21 determines that there is a high-speed frame UL2 in which the communication partner's new light beacon 4A could not be received. . On the other hand, when there is no “reception state identification flag” in which the initial value is stored, the in-vehicle controller 21 determines that there is no high-speed frame UL2 in which the communication partner's new light beacon 4A could not be received.
However, even if there is a “reception state identification flag” in which the initial value is stored, the in-vehicle controller 21 performs uplink transmission of the high-speed frame UL2 corresponding to the “reception state identification flag”. If not, it is not determined that there is a high-speed frame UL2 that the new light beacon 4A could not be received. For example, when the new in-vehicle device 2A transmits an uplink frame group having a maximum number of frames of 16 including 10 high-speed frames UL2, “reception” corresponding to the remaining 6 frames in the downstream frame UL2 received thereafter. The “state identification flag” remains the initial value. In such a case, the in-vehicle controller 21 determines that there is a high-speed frame UL2 in which the new light beacon 4A could not be received even if the initial value is stored in the “reception state identification flag” corresponding to the above six frames. Not performed.

If the determination result of step SS13 is negative, the in-vehicle controller 21 ends the process.
If the determination result in step SS13 is affirmative, the in-vehicle controller 21 retransmits the high-speed frame UL2 in which the new light beacon 4A has not been received, based on the “reception state identification flag” in which the initial value is stored. (Step SS14).

  The in-vehicle controller 21 of the present embodiment acquires the flag ID of the “reception state identification flag” in which the initial value is stored as the frame number of the high-speed frame UL2 that has not been received by the new light beacon 4A. For example, when the initial value is stored in the “reception state identification flag (1)”, the flag ID “1” is acquired as the frame number of the high-speed frame UL2 that has not been received by the new optical beacon 4A.

Then, when acquiring the frame number, the in-vehicle controller 21 retransmits the high-speed frame UL2 (upstream frame) of the acquired frame number. At that time, when there are a plurality of the frame numbers, the in-vehicle controller 21 continuously transmits all the high-speed frames UL2 corresponding to the plurality of frame numbers. At that time, the in-vehicle controller 21 can perform continuous transmission using any one of the following continuous transmission patterns 1 to 3.
Continuous pattern 1: Consecutive transmission in ascending order of frame number Continuous transmission pattern 2: Continuous transmission in order of large frame number Continuous transmission pattern 3: Continuous transmission in random frame number

[Example of road-to-vehicle communication between new in-vehicle device and Shinko Beacon]
FIG. 16 is a sequence diagram showing road-to-vehicle communication executed between the new in-vehicle device 2A and the new light beacon 4A according to the first embodiment.
Here, a case where the new in-vehicle device 2A adopts a communication standard that provides a transmission interruption period is illustrated. In addition, U1 to U10 indicated by solid line hatching indicate a plurality of uplink frames (uplink frame group) UL2 that is first uplink-transmitted by the new vehicle-mounted device 2A that has detected the downlink frame DL1, and is indicated by broken line hatching. U <b> 1 and U <b> 2 indicate a plurality of uplink frames (upstream frame group) UL <b> 2 that is retransmitted by the new in-vehicle device 2 </ b> A. For convenience of explanation, the numbers “1” to “10” following “U” indicate the frame number of the upstream frame UL2.

  In the example of FIG. 16, the new light beacon 4A cannot receive the first and second high-speed frames U1 and U2 in the upstream frame group transmitted by the new vehicle-mounted device 2A after the transmission interruption period. Therefore, the new optical beacon 4A sets all the values of the “reception state identification flag (1)” to the “reception state identification flag (10)” of the downlink frame DL2 to the initial value (here, “0”) until the high-speed frame U3 is received. )) And dowlink transmission.

  When the new optical beacon 4A receives the third high-speed frame U3, the new optical beacon 4A acquires the frame number “3” of the high-speed frame U3 (step ST13 in FIG. 14), and the downlink frame to be downlink transmitted after the reception of the high-speed frame U3. The flag value “1” is stored in the “reception state identification flag (3)” of DL2 (step ST14 in FIG. 14). Thereby, the flag value “1” is always stored in the “reception state identification flag (3)” of the downlink frame DL2 transmitted by downlink after receiving the high-speed frame U3 until the transmittable period elapses (FIG. 14). (See steps ST16 and ST17).

Similarly, each time the new optical beacon 4A sequentially receives the high-speed frames U4 to U10, the new optical beacon 4A acquires the frame number “n” of the received high-speed frame Un, and transmits the downlink frame DL2 for downlink transmission after the reception time of the high-speed frame Un. The flag value “1” is stored in the “reception state identification flag (n)”. As a result, the flag value “1” is always stored in the “reception state identification flag (n)” of the downlink frame DL2 transmitted by downlink after receiving the high-speed frame Un until the transmittable period elapses.
The new light beacon 4A does not necessarily need to update the “reception state identification flag” every time the high-speed frame UL2 is received. For example, as a method for updating the “reception state identification flag”, any one of the following update patterns 1 to 3 can be used.
Update pattern 1: Update “Reception status identification flag” corresponding to high-speed frame UL2 received during a certain period Update pattern 2: Receive high-speed frame UL2 in which the flag value is stored in “last frame flag” Sometimes, the "reception state identification flag" is updated for a series of high-speed frames UL2 up to that time. Update pattern 3: At the time when a certain time (for example, 3 milliseconds) has elapsed since the last reception of the high-speed frame UL2 Update “Reception status identification flag” corresponding to high-speed frame UL2 received in

In this embodiment, after the new in-vehicle device 2A transmits the high-speed frame U10 that is the final frame and then switches its own communication from transmission to reception, each “ The “reception state identification flag” stores the following values.
“Reception status identification flag (1)” and “Reception status identification flag (2)”: Initial value “0”
“Reception Status Identification Flag (3)” to “Reception Status Identification Flag (10)”: Flag Value “1”

  The new in-vehicle device 2A determines that the “reception state identification flag (1)” and “reception state identification flag (2)” in which the initial values are stored exist in the received downlink frame DL2 (in step SS13 of FIG. 15). In the case of “Yes”), it is recognized from these flag IDs that the new optical beacon 4A has not received the high-speed frames U1 and U2. Therefore, after switching the communication of the own device from reception to transmission, the new in-vehicle device 2A retransmits the high-speed frames U1 and U2 from which the new light beacon 4A has not been received, as indicated by the hatching in FIG. (Step SS14 in FIG. 15).

In addition, although the new light beacon 4A of this embodiment uses the information which can identify the high-speed frame UL2 which the own machine has received as reception information which can identify the high-speed frame UL2 which the own machine has not received, Information that can identify the high-speed frame UL2 that the device itself could not receive may be used.
In this case, for example, the new light beacon 4A stores all the above-mentioned “reception state identification flags” in its own storage area, and the “final frame flag” included in the header portion of the high-speed frame UL2 (see FIG. 12). ) Based on the value, the frame number of the high-speed frame UL2 corresponding to the “reception state identification flag” in which the initial value is stored at that time is recognized. The reception information may be included in the downlink frame DL2.
In addition, the new in-vehicle device 2A of the present embodiment retransmits the high-speed frame UL2 from which the new optical beacon 4A has not been received. However, even if the arbitrary high-speed frame UL2 is retransmitted (for example, several from the top) Good.

  As described above, according to the new in-vehicle device 2A and the new optical beacon 4A of the present embodiment, the new optical beacon 4A can identify the unreceived high-speed frame UL2 among the plurality of high-speed frames UL2 transmitted from the new in-vehicle device 2A. Such reception information is included in the downlink frame DL2 for downlink transmission. Therefore, the new in-vehicle device 2A that has received the downlink frame DL2 can recognize the high-speed frame UL2 that has not been received by the communication partner's new light beacon 4A.

Then, when the received information is included in the downlink frame DL2, the new in-vehicle device 2A retransmits the high-speed frame UL2 that has not been received based on the received information, so the new optical beacon 4A transmits the high-speed frame UL2 The possibility of receiving increases. Therefore, in road-to-vehicle communication performed between the new optical beacon 4A that supports multi-rate in the uplink direction and the new in-vehicle device 2A, the new optical beacon 4A appropriately selects the high-speed frame UL2 that is transmitted after the low-speed frame UL1 from the new in-vehicle device 2A. It is possible to increase the possibility of receiving.
Further, since the new vehicle-mounted device 2A transmits only the high-speed frame UL2 that has not been received by the new optical beacon 4A, it is possible to save time for the new optical beacon 4A to retransmit the received high-speed frame UL2. As a result, the re-transmission time can be shortened, so that the reception time of the downlink frame UL2 that the own device receives in the downlink can be lengthened accordingly. As a result, the new in-vehicle device 2A can acquire more provision information from the new light beacon 4A.

[Second Embodiment]
When the new optical beacon 4A of the first embodiment described above fails to receive the high-speed frame UL2, the reception information that can identify the high-speed frame UL2 that has not been received is transmitted in the downlink, but the second embodiment The new optical beacon 4A transmits, in place of the above reception information, downlink retransmission information indicating that retransmission is instructed. Specific examples thereof will be described below.

FIG. 17 is a frame configuration diagram of the downlink frame DL2 (downlink information) after downlink switching according to the second embodiment.
As shown in FIG. 17, the downlink frame DL2 of the second embodiment includes a storage area for a “retransmission instruction flag” in the storage area for the “lane notification information”, except in the case of a return frame. Note that the other configuration of the downlink frame DL2 is the same as that of the downlink frame DL shown in FIG.

  The storage area of the “retransmission instruction flag” is a storage area for indicating whether or not the new light beacon 4A instructs the retransmission of the high-speed frame UL2. Specifically, if the new optical beacon 4A fails to receive any of the plurality of high-speed frames UL2 transmitted by the new in-vehicle device 2A, a new flag value (for example, “1”) is set in the “retransmission instruction flag”. ) And all of the plurality of high-speed frames UL2 are received, other values (for example, “0”) are stored in the “retransmission instruction flag”.

  As a result, the new in-vehicle device 2A determines whether or not the communication partner's new light beacon 4A instructs retransmission of the high-speed frame UL2 based on the value of the “retransmission instruction flag” included in the “lane notification information” of the downlink frame DL2. Can be determined. Therefore, the “retransmission instruction flag” is used as retransmission instruction information for instructing the new in-vehicle device 2A to retransmit the high-speed frame UL2 that has not been received by the new optical beacon 4A of the communication partner.

FIG. 18 is a flowchart illustrating an example of processing executed by the beacon controller 7 of the new light beacon 4A according to the second embodiment. In the example of FIG. 18, the number of frames of the high-speed frame UL2 that can be received by the new optical beacon 4A is used as the variable F.
As shown in FIG. 18, the beacon controller 7 first initializes the value of the variable F as 0 (step ST20). Thereafter, the beacon controller 7 always determines whether or not uplink data has been acquired from the optical receiver 11 (step ST21). If uplink data has been acquired, whether or not the uplink data is a high-speed frame UL2. It is determined whether or not (step ST22). The determination at step ST22 is the same as the determination at step ST12 in FIG.

If the determination result of step ST22 is negative, the beacon controller 7 returns the process to before step ST21.
If the determination result of step ST22 is affirmative, the beacon controller 7 adds 1 to the variable F (step ST23).

Next, the beacon controller 7 determines whether or not the acquired uplink data (high-speed frame UL2) is the final frame of the uplink frame group (step ST24).
The determination in step ST24 can be made based on, for example, the value of the “last frame flag” (see FIG. 12) included in the header portion of the uplink data. Specifically, the beacon controller 7 determines that the frame is the final frame if the flag value (here, “1”) is stored in the “final frame flag”, and stores the flag value in the “final frame flag”. If not, it is determined that it is not the last frame.

  If the determination result of step ST24 is negative, the beacon controller 7 returns the process to before step ST21. Thereby, beacon controller 7 repeats processing of Steps ST21-ST23 about received high-speed frame UL2 among a plurality of high-speed frames UL2 which constitute an uplink frame group. Therefore, the value of the variable F indicates the number of received high-speed frames UL2 among the plurality of high-speed frames UL2 constituting the uplink frame group.

If the determination result in step ST24 is affirmative, the beacon controller 7 acquires the value of the “frame number” (see FIG. 12) included in the header part of the high-speed frame UL2 (step ST25), and the frame number It is determined whether or not the value is larger than the value of variable F, that is, whether or not there is a high-speed frame UL2 that could not be received (step ST26).
If the determination result in step ST26 is affirmative, the beacon controller 7 stores the flag value (here, “1”) in the “retransmission instruction flag” (see FIG. 17) of the downlink frame DL2 (step ST27).

If the determination result in step ST26 is negative, the beacon controller 7 stores a value other than the flag value (here, “0”) in the “retransmission instruction flag” of the downlink frame DL2 (step ST28), and optical transmission. The unit 10 is caused to transmit the downlink frame DL2 in the downlink (step ST29).
In addition to the step ST20, the condition for returning the value of the variable F to the initial value “0” is a condition (condition 1 or 2, for returning the “reception state identification flag” in the first embodiment described above to the initial value. Or the condition using any of the reference points 1 to 4 may be included.

FIG. 19 is a flowchart illustrating an example of processing executed by the in-vehicle controller 21 of the new in-vehicle device 2A according to the second embodiment. As shown in FIG. 19, after the on-vehicle controller 21 uplink-transmits all of the plurality of high-speed frames UL <b> 2, the in-vehicle controller 21 switches its own communication from transmission to reception and determines whether or not the downlink data is acquired from the optical receiver 24. Is always determined (step SS21).
And when the vehicle-mounted controller 21 acquires downlink data, it further determines whether the downlink data is the downlink frame DL2 after downlink switching (step SS22). The determination at step SS22 is the same as the determination at step SS12 in FIG.

When the determination result of step SS22 is negative, the in-vehicle controller 21 returns the process to before step SS21.
When the determination result of step SS22 is affirmative, the in-vehicle controller 21 determines whether or not the re-transmission of the high-speed frame UL2 is instructed from the new light beacon 4A (step SS23).

The determination in step SS23 can be made based on whether or not the value of the “retransmission instruction flag” (see FIG. 17) included in the “lane notification information” of the acquired downlink data (downlink frame DL2) is a flag value.
Specifically, when the value of the “retransmission instruction flag” is a flag value, the in-vehicle controller 21 determines that the communication partner's new optical beacon 4A instructs the retransmission of the high-speed frame UL2. Further, when the value of the “retransmission instruction flag” is a value other than the flag value, the in-vehicle controller 21 determines that the communication partner's new light beacon 4A has not instructed retransmission of the high-speed frame UL2.

If the determination result of step SS23 is negative, the in-vehicle controller 21 ends the process.
When the determination result of step SS23 is affirmative, the in-vehicle controller 21 retransmits a specific high-speed frame UL2 (uplink frame) that is set in advance. In the present embodiment, up to three high-speed frames U1 to U3 from the top of the upstream frame group are retransmitted (step SS24).

  The reason is that when the transmission of a plurality of high-speed frames UL2 is started, the position of the new vehicle-mounted device 2A in the vehicle traveling direction has not reached the upstream end of the area where the high-speed frame UL2 can be received (down in FIG. 11). This is because the high-speed frame UL2 for several frames from the beginning is unlikely to be received by the new optical beacon 4A.

  In general, a plurality of high-speed frames UL2 constituting the upstream frame group store travel locus data at different positions. However, as the transmission order of the high-speed frames UL2 becomes earlier (the frame number becomes smaller), the new light The travel locus data at a position close to the beacon 4A is stored. For this reason, when the possibility that the high-speed frame UL2 corresponding to several frames from the head of the upstream frame group is received is low, the possibility that the travel locus data at the position close to the new light beacon 4A, which is the most desired information, is low. There is also a reason to be.

  Of course, the number of high-speed frames UL2 to be retransmitted is not limited to three from the top, and any number of high-speed frames UL2 may be retransmitted from the top according to the situation, or any other than the top The number of high speed frames UL2 may be retransmitted.

The new light beacon 4A of the present embodiment uses the variable F to determine whether or not it has instructed retransmission of the high-speed frame UL2 (step ST26 in FIG. 18). A “reception state identification flag” may be used.
In this case, for example, the new light beacon 4A stores all “reception state identification flags” in its own storage area, and recognizes that it has received the high-speed frame U10 that is the final frame as described above. Whether or not to instruct re-transmission of the high-speed frame UL2 may be determined depending on whether or not the “reception state identification flag” in which the initial value is stored at the time exists. Further, the new light beacon 4A may perform an OR operation on all “reception state identification flags” and determine whether to instruct re-transmission of the high-speed frame UL2 based on the operation result.

  As described above, according to the new in-vehicle device 2A and the new light beacon 4A of the second embodiment, the new light beacon 4A includes the high-speed frame UL2 that has not been received among the plurality of high-speed frames UL2 transmitted from the new in-vehicle device 2A. In this case, retransmission instruction information for instructing retransmission of the high-speed frame UL2 is included in the downlink frame DL2 to be transmitted in downlink. For this reason, the new in-vehicle device 2A that has received the downlink frame DL2 can recognize that there is a high-speed frame UL2 in which the communication partner's new optical beacon 4A could not be received.

  Then, when the new in-vehicle device 2A retransmits the specific high-speed frame UL2 set in advance when the retransmission instruction information is included in the downlink frame DL2, the new optical beacon 4A can receive the high-speed frame UL2 Increases nature. Therefore, in road-to-vehicle communication performed between the new optical beacon 4A that supports multi-rate in the uplink direction and the new in-vehicle device 2A, the new optical beacon 4A appropriately selects the high-speed frame UL2 that is transmitted after the low-speed frame UL1 from the new in-vehicle device 2A. It is possible to increase the possibility of receiving.

In addition, the new in-vehicle device 2A retransmits the high-speed frame UL2 for several frames from the top because there is a high possibility that the new optical beacon 4A has not been received among the plurality of high-speed frames UL2, so the new optical beacon 4A is not yet received. The possibility of receiving the high-speed frame UL2 that has been received can be further increased.
In addition, the new in-vehicle device 2A can shorten the retransmission time compared to the case where all the plurality of high-speed frames UL2 are retransmitted, so that the reception time of the downlink frame for downlink reception is increased accordingly. Can do. Thereby, 2A of new vehicle equipment can acquire more provision information from 4A of new light beacons.

[Third Embodiment]
The new in-vehicle device 2A according to the second embodiment described above performs a retransmission process when the retransmission instruction information is included in the downlink frame DL2, but the new in-vehicle device 2A according to the third embodiment performs predetermined processing for the downlink frame DL2. If the provided information is included, resend processing is performed. Specific examples thereof will be described below.

FIG. 20 is a flowchart illustrating an example of processing executed by the in-vehicle controller 21 of the new in-vehicle device 2A according to the third embodiment. Steps SS31 and SS32 are the same as steps SS21 and SS22 in FIG.
As shown in FIG. 20, when the determination result in step SS32 is affirmative, the in-vehicle controller 21 determines whether or not predetermined provision information provided by the new light beacon 4A has been acquired (step SS33).

The determination in step SS33 is performed based on whether or not predetermined provision information (for example, signal information shown in FIG. 16) is included in the provision information included in the actual data portion of the acquired downlink data (downlink frame DL2). Can do.
If the determination result of step SS33 is negative, the in-vehicle controller 21 ends the process.
If the determination result of step SS33 is affirmative, the in-vehicle controller 21 retransmits the specific high-speed frame UL2 (U1 to U3) set in advance (step SS34), and ends the process.

As described above, according to the new in-vehicle device 2A of the third embodiment, when the predetermined provision information provided by the new optical beacon 4A is acquired, the predetermined high-speed frame UL2 is retransmitted. The possibility of receiving the high-speed frame UL2 that has not been received by the new light beacon 4A can be increased while acquiring the provision information.
In addition, the new in-vehicle device 2A no longer needs time for downlink communication when it acquires all the provision information provided by the new optical beacon 4A or only the provision information required by its own device as the predetermined provision information. Since there is no, you can spend time on uplink communication instead. Thereby, 2 A of new vehicle equipment can utilize limited communication time effectively.

[Fourth Embodiment]
The new in-vehicle device 2A of the second and third embodiments described above performs retransmission processing when predetermined information is included in the downlink frame DL2, but the new in-vehicle device 2A of the fourth embodiment Regardless of the information included in the DL, the retransmission process is performed when the speed of the vehicle 20 on which the vehicle is mounted satisfies a predetermined speed condition. Specific examples thereof will be described below.

FIG. 21 is a flowchart illustrating an example of processing executed by the in-vehicle controller 21 of the new in-vehicle device 2A according to the fourth embodiment.
As shown in FIG. 21, the in-vehicle controller 21 determines whether or not the speed of the vehicle 20 on which the in-vehicle controller 21 is mounted is equal to or less than a predetermined value after uplink transmission of all the plurality of high-speed frames UL2. SS41).

The determination in step SS41 can be performed, for example, by acquiring the speed data measured by the vehicle speed sensor from the vehicle 20 and comparing the speed data with a predetermined value stored in advance in the in-vehicle controller 21. .
In this modification, it is determined whether or not the speed of the vehicle 20 is equal to or lower than a predetermined value. However, the speed is not limited to this condition, and an arbitrary speed condition may be set according to the situation. .

If the determination result of step SS41 is negative, the in-vehicle controller 21 ends the process.
When the determination result of step SS41 is affirmative, the in-vehicle controller 21 retransmits the specific high-speed frame UL2 (U1 to U3) set in advance (step SS42), and ends the process.
Note that the high-speed frame UL2 to be retransmitted may be transmitted in addition to the uplink frame group to be transmitted first (see FIG. 22), as in a fifth embodiment to be described later. In this case, the determination in step SS41 may be performed before transmitting the upstream frame group.

  As described above, according to the new vehicle-mounted device 2A of the fourth embodiment, when the speed of the vehicle 20 on which the vehicle is mounted is traveling at a low speed equal to or lower than a predetermined value, that is, the new light beacon 4A can receive the high-speed frame UL2. Since the predetermined high-speed frame UL2 is retransmitted when the traveling time of the vehicle 20 in such an area becomes long, the possibility of receiving the high-speed frame UL2 that has not been received by the new light beacon 4A can be further increased. Also, if the speed of the vehicle 20 is slow, the new vehicle-mounted device 2A has a longer time in the area, so that there is a time margin for retransmitting the high-speed frame UL2.

[Modifications of Second to Fourth Embodiments]
The new in-vehicle device 2A of the second to fourth embodiments described above retransmits some high-speed frames UL2, but may retransmit all high-speed frames UL2.
In this case, for example, the new in-vehicle device 2A may set in advance all the high-speed frames U1 to U10 that it transmits first as the retransmission-reliable high-speed frame UL2.

  Thereby, when the determination result is affirmative in step SS23 of the second embodiment (FIG. 19), step SS33 of the third embodiment (FIG. 20), and step SS41 of the fourth embodiment (FIG. 21). All the high-speed frames U1 to U10 set in advance are retransmitted.

Thus, if all the preset high-speed frames U1 to U10 are retransmitted, the new optical beacon 4A cannot receive any of the high-speed frames among the plurality of high-speed frames U1 to U10 transmitted first. Even in this case, the possibility of receiving the high-speed frame that has not been received can be increased.
Note that the new in-vehicle device 2A of this modification may retransmit the retransmission-reliable high-speed frame UL2 a plurality of times. In this case, the number of retransmissions may be changed according to the speed of the vehicle 20 on which the new in-vehicle device 2A is mounted, as in Modification 4 of the fifth embodiment to be described later.

[Fifth Embodiment]
The new in-vehicle device 2A of the above-described first to fourth embodiments (including modifications) performs the retransmission process when a predetermined condition is satisfied, but the new in-vehicle device 2A of the fifth embodiment is unconditional. Then, retransmission processing for retransmitting an arbitrary high-speed frame UL2 is performed. Specific examples thereof will be described below.

FIG. 22 is a sequence diagram illustrating road-to-vehicle communication executed between the new in-vehicle device 2A and the new light beacon 4A according to the fifth embodiment.
When the high-speed frame UL2 is continuously transmitted after the low-speed frame UL1, the new in-vehicle device 2A of the present embodiment adds one of the plurality of high-speed frames UL2 to the upstream frame group of the plurality of high-speed frames UL2 transmitted first. A part of the high-speed frame UL2 is added as a retransmission trust.

  In the example of FIG. 22, an upstream frame group of a plurality of high-speed frames U1 to U10 to be transmitted first (the maximum number of frames is 16), and a part of the high-speed frames U1 to U10 from the first three to a high speed A case where frames U1 to U3 are added is shown.

  However, the number of high-speed frames UL2 transmitted first and the number of retransmission-reliable high-speed frames UL2 can be set to arbitrary numbers as long as the sum of these is within the maximum number of frames in the uplink frame group. For this reason, the retransmission-reliable high-speed frame UL2 may include not only a part of the plurality of high-speed frames UL2 to be transmitted first but also all of them, or an arbitrary number of high-speed frames UL2 other than the head.

  When the new in-vehicle device 2A performs uplink transmission of the uplink frame group, it first transmits ten high-speed frames U1 to U10, and then continuously retransmits three high-speed frames U1 to U3. In the example of FIG. 22, the new optical beacon 4A has not received the first and second high-speed frames U1 and U2 among the plurality of first high-speed frames U1 to U10 transmitted in the uplink, Since the frames U1 and U2 are retransmitted, it is possible to increase the possibility of receiving the high-speed frames U1 and U2 that have not been received.

  Note that the new in-vehicle device 2A of the present embodiment transmits the retransmission-reliable high-speed frame UL2 in addition to the uplink frame group to be transmitted first, similarly to the case of the first embodiment (see FIG. 16). Separately from the upstream frame group to be transmitted first, a retransmission-reliable high-speed frame UL2 may be transmitted.

  As described above, according to the new vehicle-mounted device 2A of the fifth embodiment, the new vehicle-mounted device 2A retransmits an arbitrary high-speed frame UL2 after transmitting a plurality of high-speed frames UL2, and therefore the plurality of high-speed frames transmitted first. Even when the new optical beacon 4A cannot receive a part of the frame UL2, the possibility of receiving the high-speed frame UL2 that has not been received by the retransmission increases. Therefore, in road-to-vehicle communication performed between the new optical beacon 4A that supports multi-rate in the uplink direction and the new in-vehicle device 2A, the new optical beacon 4A appropriately selects the high-speed frame UL2 that is transmitted after the low-speed frame UL1 from the new in-vehicle device 2A. It is possible to increase the possibility of receiving. Further, since there is no need to change the communication protocol on the new optical beacon 4A side, the retransmission process can be simplified.

Further, since the retransmission-reliable high-speed frame UL2 is transmitted in addition to the upstream frames of the plurality of high-speed frames UL2 to be transmitted first, the new optical beacon 4A promptly receives the unreceived high-speed frame UL2. Can do.
Moreover, since the new in-vehicle device 2A retransmits the high-speed frame UL2 for several frames from the top, which is likely to be unreceived by the new optical beacon 4A among the plurality of high-speed frames UL2 to be transmitted first, the new optical beacon The possibility of receiving the high-speed frame UL2 that has not been received by 4A can be further increased.

[Modification 1 of Fifth Embodiment]
In the new vehicle-mounted device 2A of the fifth embodiment described above, the sum of the number of high-speed frames UL2 to be transmitted first and the number of retransmission-reliable high-speed frames UL2 is 13, and the maximum number of frames (16 A smaller number of high-speed frames UL2 are transmitted. On the other hand, the new in-vehicle device 2A of the first modification is set so that the sum is always the maximum number of frames in the uplink frame group. Specific examples thereof will be described below.

FIG. 23 is an explanatory diagram illustrating a configuration of an upstream frame group transmitted first by the new vehicle-mounted device 2A according to the first modification of the fifth embodiment.
The new in-vehicle device 2A of the first modified example is configured such that the maximum number of high-speed frames that can be included in the uplink frame group is N, and the total number of high-speed frames UL2 to be transmitted first is M. Among the M high-speed frames UL2, some high-speed frames UL2 from the head to K are added to the uplink frame group as retransmission trust.

At that time, the new in-vehicle device 2A sets the number (K) of retransmission-reliable high-speed frames UL2 so as to satisfy the following expression (1).
K = N−M (1)
Here, K is a positive integer, N is a positive integer, and M is a positive integer smaller than N.

In the example of FIG. 23, the high-speed frame UL2 to be transmitted first is included in the upstream frame group having the maximum number of frames of 16 as the high-speed frames U1 to U10 having the total number of frames of 10.
For this reason, the new in-vehicle device 2A sets the K to 6 (= 16-10), and among the 10 high-speed frames U1 to U10 transmitted first, the 6 high-speed frames U1 to U6 from the head are selected. It adds to the said upstream frame group.

When the new in-vehicle device 2A performs uplink transmission of the uplink frame group, it first transmits ten high-speed frames U1 to U10, and then continuously retransmits six high-speed frames U1 to U3.
The total number of frames (M) is not limited to the case of the present modification, and can be set to an arbitrary value. Therefore, in this modification, the number (K) of high-speed frames UL2 to be retransmitted can be set to an arbitrary number depending on the total number of frames. For example, when the total number of frames is 11, the number of high-speed frames UL2 to be retransmitted is 5 (= 16-11).

  As described above, according to the new vehicle-mounted device 2A of the first modification, the number (K) of retransmission-reliable high-speed frames UL2 added to the uplink frame group can be increased as much as possible, so that the new optical beacon 4A is not received. The possibility of receiving the high-speed frame UL2 can be further increased.

[Modification 2 of Fifth Embodiment]
The new in-vehicle device 2A of the first modification of the fifth embodiment has only one retransmission reliable high-speed frame UL2 added to the upstream frame group, whereas the new in-vehicle device 2A of the second modification is different from the upstream frame group. The re-transmission credit high-speed frame UL2 is added a plurality of times within a range not exceeding the maximum number of frames. Specific examples thereof will be described below.

FIG. 24 is an explanatory diagram illustrating the configuration of an upstream frame group transmitted first by the new in-vehicle device 2A according to the second modification of the fifth embodiment.
The new in-vehicle device 2A of the modification 2 is configured such that the maximum number of high-speed frames that can be included in the uplink frame group is N, and the total number of frames of the plurality of high-speed frames UL2 to be transmitted first is M. Among the M high-speed frames UL2, some high-speed frames from the top to K are added R times as retransmission credits to the uplink frame group.

At that time, the new vehicle-mounted device 2A sets the number (K) of retransmission-reliable high-speed frames UL2 and the number of times (R) to add the K high-speed frames UL2 so as to satisfy the following equation (2).
K × R ≦ N−M Formula (2)
Here, N is a positive integer, M is a positive integer smaller than N, K is a positive integer less than or equal to M, and R is a positive integer greater than or equal to 2.

In the example of FIG. 24, the case where the high-speed frame UL2 transmitted first is included in the upstream frame group having the maximum number of frames of 16 includes the high-speed frames U1 to U10 having the total number of frames of 10.
Therefore, for example, when the new in-vehicle device 2A adds the three high-speed frames U1 to U3 from the top of the high-speed frames U1 to U10 to the upstream frame group as retransmission credits, for example, the three high-speed frames U1 to U3 are added. Add twice to the upstream frame group.

  When the new in-vehicle device 2A transmits the uplink frame group in the uplink, after the first high-speed frames U1 to U10 are transmitted for the first time, the three high-speed frames U1 to U3 added to the first time continuously, And the three high-speed frames U1 to U3 added in the second time are retransmitted in this order.

  The total number of frames (M) and the number of retransmission-reliable high-speed frames UL2 (K) are not limited to the case of this modification, and can be set to arbitrary values. For example, when the total number of frames is 8 and the number of retransmission-reliable high-speed frames UL2 is 2, these two high-speed frames UL2 can be added to the upstream frame group four times. However, the number of times (R) to be added to the upstream frame group only needs to satisfy the above formula (2), and may be only twice or three times.

  As described above, according to the new in-vehicle device 2A of the modified example 2, the total frame number (M + K × R) of the high-speed frame UL2 to be transmitted and retransmitted does not exceed the maximum frame number (N) of the uplink frame group. K high-speed frames UL2 can be retransmitted repeatedly. For this reason, it is possible to further increase the possibility of receiving the high-speed frame UL2 that has not been received by the new light beacon 4A.

[Modification 3 of Fifth Embodiment]
In the above-described fifth embodiment (including modifications 1 and 2), the maximum number of frames (N) in the uplink frame group is a fixed value (16), but the speed of the vehicle 20 on which the new in-vehicle device 2A is mounted. Depending on, the maximum number of frames may be changed.
In this case, for example, the new in-vehicle device 2A acquires the speed data measured by the vehicle speed sensor from the vehicle 20 at the time when the transmission interruption period (see FIG. 22) has elapsed, and based on the speed data, The maximum number of frames (N) may be set.

At that time, it is preferable that the new in-vehicle device 2A is set so that the maximum number of frames (N) of the uplink frame group is increased as the speed data is smaller (slower).
The reason is that the slower the speed of the vehicle 20, the longer the traveling time of the vehicle 20 in the area where the new light beacon 4A can receive the high speed frame UL2, so the new light beacon 4A receives more high speed frames UL2. Because it will be possible.

For example, when the first modification of FIG. 23 is applied to the present modification, the maximum number of frames N2 from 16 to 18 can be increased from six to eight as the number of retransmission-reliable high-speed frames UL2. Further, when the second modification of FIG. 24 is applied to the present modification, if the maximum frame number N is increased from 16 to 19, the retransmission-reliable high-speed frame UL2 (U1 to U3) is transmitted to the upstream frame group three times. Can be added.
As described above, when the maximum speed of the uplink frame group is increased when the speed of the vehicle 20 is low, the number of retransmission-reliable high-speed frames UL2 added to the uplink frame group can be increased. The possibility of receiving the high-speed frame UL2 that has not been received can be further increased.

[Modification 4 of the fifth embodiment]
In the second modification of the fifth embodiment, the high-speed frame UL2 is retransmitted a plurality of times by adding the retransmission-reliable high-speed frame UL2 to the upstream frame group a plurality of times. The number of retransmissions (the number of times that the retransmission-reliable high-speed frame UL2 is added to the uplink frame group) can be changed according to the speed of the vehicle 20 on which the new vehicle-mounted device 2A is mounted. For this reason, in this modification, the maximum frame number N of the upstream frame group can be set to an arbitrary value.
In addition, the new in-vehicle device 2A acquires speed data measured by the vehicle speed sensor from the vehicle 20 when, for example, a transmission interruption period (see FIG. 22) has elapsed, and based on the speed data, The number of times (R) to add the high-speed frame UL2 for retransmission is set.

At that time, it is preferable that the new vehicle-mounted device 2A is set so that the number (R) of adding the retransmission-reliable high-speed frame UL2 to the upstream frame group increases as the speed data is smaller (slower).
The reason is that the slower the speed of the vehicle 20, the longer the traveling time of the vehicle 20 in the area where the new light beacon 4A can receive the high speed frame UL2, so the new light beacon 4A receives more high speed frames UL2. Because it will be possible.

  In this way, when the speed of the vehicle 20 is slow, if the number of times of adding the retransmission-reliable high-speed frame UL2 to the upstream frame group is increased, the number of high-speed frames UL2 to be retransmitted increases. The possibility of receiving the high-speed frame UL2 that has not been received by the beacon 4A can be further increased.

[Modifications of First to Fifth Embodiments]
In the above-described first to fifth embodiments (including modified examples 1 to 4), when retransmitting the high-speed frame UL2, the transmission frame (or retransmission credit) between the high-speed frame UL2 transmitted immediately before is retransmitted. The transmission interval (hereinafter referred to as “retransmission interval”) may be changed according to the speed of the vehicle 20 on which the new in-vehicle device 2A is mounted.
In this case, for example, the new in-vehicle device 2A acquires the speed data measured by the vehicle speed sensor from the vehicle 20 when the transmission interruption period (see FIG. 22) elapses, and based on the speed data, the high-speed frame UL2 The re-transmission interval may be set.

At that time, the new in-vehicle device 2A is preferably set so that the re-transmission interval becomes longer as the speed data is smaller (slower).
The reason is that the slower the vehicle 20 is, the longer the travel time of the vehicle 20 in the area where the new light beacon 4A can receive the high-speed frame UL2, the longer the retransmission interval, the new light beacon 4A This is because the high-speed frame UL2 can be appropriately received.

Thus, when the speed of the vehicle 20 is slow and the retransmission interval of the high-speed frame UL2 is lengthened, the new optical beacon 4A can appropriately receive the retransmitted high-speed frame UL2, and thus the new optical beacon 4A is not received. The possibility of receiving the high-speed frame UL2 can be further increased.
In addition, if the re-transmission interval is increased as the speed of the vehicle 20 becomes slower, the distance traveled by the vehicle 20 before the high-speed frame UL2 is retransmitted correspondingly increases, so that the area where the high-speed frame UL2 can be received. There is a high possibility that the vehicle 20 that has not reached the upstream end (second uplink upstream end P2) will reach the area at the time of retransmission. As a result, the possibility of receiving the high-speed frame UL2 that has not been received by the new optical beacon 4A can be further increased.

[Reference Example 1]
As another modified example of the first to fifth embodiments described above, the transmission interval of the retransmission-reliable high-speed frame UL2 is changed according to the speed of the vehicle 20, but when a plurality of high-speed frames UL2 are first transmitted. In addition, the transmission interval between the low-speed frame U0 and the leading high-speed frame U1 may be changed.
In this case, in the example of FIG. 22, the new in-vehicle device 2A sets a transmission interruption period, which is a transmission interval between the low speed frame U0 and the leading high speed frame U1, based on the speed data acquired from the vehicle 20 to an arbitrary time length. Should be set.

At that time, it is preferable that the new vehicle-mounted device 2A is set so that the time length becomes longer as the speed data is smaller (slower).
The reason is that the slower the speed of the vehicle 20, the slower the time for the vehicle 20 to reach the second uplink upstream end P2 (see FIG. 11).

  Thus, when the transmission speed of the low-speed frame U0 and the leading high-speed frame U1 is increased when the speed of the vehicle 20 is low, the transmission time point at which the leading high-speed frame U1 is uplink-transmitted is set as the second uplink upstream end. It can be closer to P2. For this reason, it is possible to increase the possibility that the new optical beacon 4A can receive the high-speed frame UL2 transmitted first.

[Reference Example 2]
In the reference example 1 described above, the transmission interval (transmission interruption period) between the low-speed frame U0 and the leading high-speed frame U1 is changed according to the speed of the vehicle 20, but the new in-vehicle device 2A provides predetermined provision information. The transmission interruption period may be continued until the received downlink frame DL2 is received. That is, the new in-vehicle device 2A may interrupt the transmission of the high-speed frame UL2 until it receives the downlink frame DL2 including predetermined provision information. Specific examples thereof will be described below.

FIG. 25 is a sequence diagram showing road-to-vehicle communication executed between the new in-vehicle device 2A and the new light beacon 4A of Reference Example 2.
In the example of FIG. 25, the new in-vehicle device 2A provides a transmission interruption period between the low speed frame U0 and the leading high speed frame U1 when the high speed frames U1 to U10 are continuously transmitted after the low speed frame U0.
When the new in-vehicle device 2A receives the downlink frame DL2 continuously transmitted after downlink switching, the new vehicle-mounted device 2A determines whether or not predetermined provision information (for example, signal information) is included in the actual data portion of the downlink frame DL2. If the predetermined provision information is not included, the transmission interruption period is continued.

When the new in-vehicle device 2A receives the downlink frame DL2 including the predetermined provision information, the new vehicle-mounted device 2A ends the transmission interruption period, and switches its own communication from reception to transmission. Then, the new in-vehicle device 2A starts continuous transmission of the high-speed frames U1 to U10.
At that time, if the acquired provided information is the desired provided information, the new in-vehicle device 2A does not need the remaining downlink frame DL2 provided by the new optical beacon 4A, and therefore after the transmission of the high-speed frames U1 to U10. It is possible to maintain the communication of the own device as it is transmitted until the vehicle 20 passes the downstream end of the uplink area UA of the high-speed frame UL2.

FIG. 26 is a side view showing a preferable communication area of the new optical beacon 4A in the case where the new in-vehicle device 2A of the present reference example maintains its own communication as transmitted after the end of the transmission interruption period as described above. is there.
Hereinafter, the points changed from the communication area of the optical beacon 4 illustrated in FIG. 11 in the communication area of the new optical beacon 4A illustrated in FIG. 26 will be described.

As shown in FIG. 26, the upstream boundary UB1 of the uplink area UA in which the new optical beacon 4A can receive the low-speed frame UL1 is the same as the upstream boundary DB0 of the downlink area DA in which the new vehicle-mounted device 2A can receive the downlink frame DL1. I'm doing it.
Accordingly, the first uplink upstream end P1 is set to coincide with the downlink upstream end P0 upstream of the second uplink upstream end P2.

  By setting in this way, as shown in FIG. 25, the new vehicle-mounted device 2A can quickly uplink the low-speed frame UL1 (storage frame U0) at the time when the downlink frame DL1 is received. Then, the new optical beacon 4A that has received the low-speed frame UL1 starts continuous transmission of the downlink frame DL2 after downlink switching, so that the new in-vehicle device 2A can quickly receive predetermined provision information.

Returning to FIG. 26, the boundary line UC2 indicating the downstream boundary of the uplink area UA in which the new optical beacon 4A can receive the high-speed frame UL2 indicates the downstream boundary of the downlink area DA in which the new vehicle-mounted device 2A can receive the downlink frame DL1. It coincides with the boundary line DC0 shown.
Accordingly, the second uplink downstream end Q2 that is the intersection position between the downstream boundary UC2 and the installation height H of the new vehicle-mounted device 2A is the downlink downstream end Q0 that is the intersection position between the downstream boundary UD0 and the installation height H. Is set to match.

  By setting in this way, even if the vehicle 20 approaches immediately below the new light beacon 4A, the new light beacon 4A can receive the high-speed frame UL2 transmitted by uplink from the new vehicle-mounted device 2A. For this reason, when the new in-vehicle device 2A continues to transmit the high-speed frame UL2 after receiving the downlink frame DL2 including the predetermined provision information, the number of high-speed frames UL2 that can be received by the new optical beacon 4A can be increased. .

  As described above, according to the new in-vehicle device 2A and the new optical beacon 4A in Reference Example 2, the new in-vehicle device 2A transmits the high-speed frame UL2 after acquiring the predetermined provision information. The transmission timing of the high-speed frame UL2 can be delayed until the provision information is acquired. This increases the possibility that the high-speed frame UL2 will be transmitted after the vehicle 20 reaches the second uplink upstream end P2 (see FIG. 11), so that the new light beacon 4A can receive the high-speed frame UL2. Can be increased. Moreover, since the new vehicle-mounted device 2A continues to transmit the high-speed frame UL2 after acquiring the predetermined provision information, the new light beacon 4A can acquire more information from the new vehicle-mounted device 2A.

[Examples of optical measures with new in-vehicle equipment]
In the first to fifth embodiments described above, as shown in FIG. 11, the position of the second uplink upstream end P2 is located upstream (or substantially the same position) from the position of the first uplink upstream end P1. Therefore, the new light beacon 4A is set, but instead of this, the new in-vehicle device 2A may be set. Specific examples thereof will be described below.

  In the new vehicle-mounted device 2A, in order to set the position of the second uplink upstream end P2 upstream (or substantially the same position) from the position of the first uplink upstream end P1, the uplink of the low-speed frame UL1 The light emission amount (hereinafter referred to as “first light emission amount”) and the light emission amount (hereinafter referred to as “second light emission amount”) of the uplink light of the high-speed frame UL2 are the first light emission amount ≦ second. It is only necessary to satisfy the relational expression of the light emission amount.

FIG. 27 shows a current waveform when uplink light is emitted by a conventional new vehicle-mounted device, where (a) shows the current waveform of the low-speed frame UL1, and (b) shows the current waveform of the high-speed frame UL2.
As shown in FIGS. 27A and 27B, the light emitting element of the conventional new vehicle-mounted device is designed so that each current of the low speed frame UL1 and the high speed frame UL2 has a waveform indicated by a broken line. Specifically, the light emitting element includes the first light emission amount of the low-speed frame UL1 (the total area of the hatched portions shown by broken lines in FIG. 27A) and the second light emission amount of the high-speed frame UL2 (FIG. 27B). The total area of the hatched portions of the broken lines is designed to be the same. Thus, at the design stage of the light emitting element, the first light emission amount and the second light emission amount satisfy the relational expression.

However, in reality, as shown by the solid lines in FIGS. 27A and 27B, the current waveforms of the low-speed and high-speed frames UL1 and UL2 are dull. Since this dullness increases as the light emission of the light emitting element becomes faster, the dullness of the current waveform of the high-speed frame UL2 becomes larger than the dullness of the current waveform of the low-speed frame UL1.
For this reason, in the actual current waveform, the second light emission amount (the total area of the hatched portion of the solid line in FIG. 27B) is the sum of the areas of the first light emission amount (the hatched portion of the solid line in FIG. 27A). ) And the first and second light emission amounts do not satisfy the above relational expression. The inventor of the present application paid attention to this point and completed the following optical countermeasure examples.

FIG. 28 shows an actual current waveform when uplink light is emitted by the light emitting element (for example, LED) of the light transmitting unit 23 (see FIG. 3) of the new vehicle-mounted device 2A according to the optical countermeasure example. ) Is a current waveform of the low speed frame UL1, and (b) is a current waveform of the high speed frame UL2.
In FIGS. 28A and 28B, the light emitting element of the optical transmission unit 23 has the current value of the high-speed frame UL2 in the state where each current waveform of the low-speed and high-speed frames UL1 and UL2 is blunted. Designed to be higher than.

At this time, the current value of the high-speed frame UL2 is such that the second light emission amount of the high-speed frame UL2 (the sum of the areas of hatched portions in FIG. 28B) is the first light emission amount of the low-speed frame UL1 (FIG. 28A). The sum of the hatched areas is adjusted to be greater than or equal to the total area.
Thereby, since the first and second light emission amounts satisfy the above relational expression, the second uplink upstream end P2 is positioned upstream (or substantially the same position) from the first uplink upstream end P1. Can do.

However, as described above, when the light emitting element of the optical transmission unit 23 is designed so as to increase the current value of the high-speed frame UL2, there is a demerit that the life of the light emitting element is shortened because the light emission power increases.
Therefore, as a modification of the above optical countermeasure example, the light emitting element is designed so that the current waveform of the high-speed frame UL2 does not become dull, so that the first and second light emission amounts satisfy the above relational expression. May be.

[Countermeasures using Shinko Beacon]
There are some specific examples as other countermeasure examples for setting the new optical beacon 4A in order to increase the possibility that the new optical beacon 4A can appropriately receive the high speed frame UL2 transmitted after the low speed frame UL1. Specific examples of these will be described below.

[Countermeasure 1]
FIG. 29 is a side view showing a communication area of the new optical beacon 4A according to countermeasure example 1. FIG.
As shown in FIG. 29, in Countermeasure Example 1, the upstream boundary DB0 of the downlink area DA in which the new in-vehicle device 2A can receive the downlink frame DL1 is in the uplink area UA in which the new optical beacon 4A can receive the low-speed frame UL1. The new optical beacon 4A is located on the upstream side of the upstream boundary UB1 and on the downstream side of the upstream boundary UB2 of the uplink area UA that can receive the high-speed frame UL2. As a result, the downlink upstream end P0 is positioned upstream of the first uplink upstream end P1 and downstream of the second uplink upstream end P2.

By setting as described above, the new in-vehicle device 2A does not receive the downlink frame DL1 upstream from the second uplink upstream end P2, and therefore does not uplink the low-speed frame UL1. .
Thereby, since the new optical beacon 4A does not return the return frame, the new in-vehicle device 2A can prevent the high-speed frame UL2 from being uplink transmitted upstream of the second uplink upstream end P2. As a result, the new optical beacon 4A can increase the possibility of appropriately receiving the high-speed frame UL2 transmitted after the low-speed frame UL1.

[Countermeasure example 2]
FIG. 30 is a side view showing a communication area of the new optical beacon 4A according to countermeasure example 2.
As shown in FIG. 30, in the countermeasure example 2, when the first uplink upstream end P1 is positioned upstream of the second uplink upstream end P2, the upstream side of the second uplink upstream end P2 is upstream. The “reception restriction process” is executed to prohibit downlink switching by the low-speed frame UL1 transmitted at a far position. Thereby, instead of the first upstream end P1 that is the “physical” uppermost stream end, the apparent logical end that is the “logical” uppermost stream end at a position close to the second upstream upstream end P2 on the downstream side. The first uplink upstream end P1 ′ is adopted to perform the above-described position setting.

FIG. 31 is a circuit configuration diagram of the new optical beacon 4A according to the countermeasure example 2.
As shown in FIG. 31, in the new optical beacon 4A of the countermeasure example 2, the light receiving unit 11 includes a first light receiving system 26 that is a communication light receiving system (light receiving circuit) and a measurement light receiving system (light receiving circuit). A second light receiving system 27.
The beacon controller 7 includes a communication IC (communication processing unit) 28, a position IC (position processing unit) 29, and a main CPU (determination processing unit) 30.

Although not shown in FIG. 31, the beacon controller 7 also includes a memory that temporarily stores “position data” and “upstream data” output from the ICs 28 and 29.
The first light receiving system 26 includes a communication conversion element 32, an amplifier 33, a filter 34, and a comparator 35 in order from the left side of FIG. The communication conversion element 32 includes a light receiving element (for example, a photodiode (hereinafter also referred to as “PD”)) that converts the received optical signal in the uplink direction into an electrical signal.

The amplifier 33 includes a high-speed amplifier circuit that operates in a high-speed band (in this embodiment, 256 kbps). The amplifier 33 operates and amplifies the electrical signal converted by the PD 32 in a high-speed band, and outputs the amplified electrical signal to the subsequent filter 34.
The filter 34 is a low-pass filter that can extract at least a component in the high-speed band (in this embodiment, 256 kbps). The filter 34 may be a bandpass filter that covers from low speed components to high speed components.

The filter 34 extracts a low-speed component or a high-speed component from the amplified electrical signal, and outputs the extracted low-speed signal or high-speed signal to the comparator 35 at the subsequent stage.
The comparator 35 is composed of a high speed comparator capable of comparing a high speed signal with a threshold value. The comparator 35 compares the input low-speed signal or high-speed signal with a threshold value, and outputs a digital reception signal (bit data) extracted by this comparison to the communication IC 28 at the subsequent stage.

  The communication IC 28 determines the transmission rate of the received signal using the idle pattern of the first 5 bytes, samples the bit data at the determined transmission rate, and reproduces the upstream data included in the upstream frames UL1 and UL2. The communication IC 28 sends the reproduced upstream data to the main CPU 30 at the subsequent stage.

The second light receiving system 27 includes a conversion element 36 for measurement, an amplifier 37, and a peak hold circuit 38 in order from the left side of FIG.
The communication conversion element 36 includes a position detection element (hereinafter also referred to as “PSD”) that outputs an electrical signal corresponding to the input position in the light receiving surface of the upstream frames UL1 and UL2. Note that the principle of measuring the uplink position using the PSD 36 (FIG. 32) will be described later.

The PSD 36 of the present embodiment is a two-dimensional PSD, and can output four current values necessary for calculating the two-dimensional coordinates of the spot light incident on the light receiving surface.
The current values output from the four output terminals of the PSD 36 are amplified by the amplifier 37 at the subsequent stage. The electric signal amplified by the amplifier 37 is input to the peak hold circuit 38 at the subsequent stage. The peak hold circuit 38 generates measurement data by holding the maximum amplitude of the amplified signal for a predetermined time, and sends the generated measurement data to the subsequent position IC 29.

The position IC 29 measures the uplink position using the measurement data (the current value of each output terminal of the PSD 36) input from each peak hold circuit 38. The position IC 29 sends position data that is the measurement result to the main CPU 30.
The position data output by the position IC 29 may be based on either coordinates (x, y) on the light receiving surface of the PSD 36 or coordinates (X, Y) on the road side (see FIG. 32).

In this embodiment, the position data is based on coordinates (x, y). In this case, the main CPU 30 needs to perform an operation for converting the coordinates (x, y) to the coordinates (X, Y).
The main CPU 30 sets the low-speed frame UL1 as a downlink switching target depending on whether or not the uplink position of the low-speed frame UL1 represented by the “position data” from the position IC 29 is downstream of the threshold (fixed position). “Reception limited processing” is performed to determine whether or not. Details of this reception restriction process (flow chart in FIG. 33) will be described later.

FIG. 32 is an explanatory diagram of the principle of measuring the uplink position using the position detection element (PSD) 36.
As shown in FIG. 32, the road side coordinates (X, Y) are two-dimensional coordinates within a plane of a predetermined installation height H (for example, H = 1.0 m) of the vehicle-mounted device 2 from the road surface of the road R. Yes, the X direction is along the extending direction of the road R (vehicle traveling direction), and the Y direction is along the width direction of the road R.

The two-dimensional PSD 36 is arranged inside the beacon head 8 so that the x direction of the light receiving surface corresponds to the X direction on the road side and the y direction of the light receiving surface corresponds to the Y direction on the road side. .
In the two-dimensional PSD 36, assuming that the current values of the output terminals x1, x2, y1, and y2 are Ix1, Ix2, Iy1, and Iy2, respectively, the coordinates (x, y) of the incident position of the spot light incident on the light receiving surface are obtained. And can be calculated by the following relational expression.
2x / Lx = {(Ix2 + Iy1)-(Ix1 + Iy2)} / (Ix1 + Ix2 + Iy1 + Iy2)
2y / Ly = {(Ix2 + Iy2)-(Ix1 + Iy1)} / (Ix1 + Ix2 + Iy1 + Iy2)

In the above relational expression, Lx is the length of the light receiving surface in the x direction, and Ly is the length of the light receiving surface in the y direction.
Therefore, when the value of the measurement data Ix1, Ix2, Iy1, Iy2 obtained from the peak hold circuit 38 of the optical receiver 24 exceeds a predetermined threshold, the position IC 29 substitutes these values into the above relational expression, The value of the coordinate (x, y) of the incident position of the spot light is calculated. In the present embodiment, this coordinate value is position data.

On the other hand, as shown in FIG. 32, the optical signal transmitted toward the beacon head 8 at an arbitrary position (X, Y) in the uplink area UA is condensed by the lens and is within the light receiving surface of the PSD 36. Spot light is incident on any one position (x, y).
Therefore, the incident position (x, y) of the upstream optical signal (uplink light) transmitted in the uplink area UA has a one-to-one correspondence with the transmission position (X, Y) on the road side. If the value of the position (x, y) is found, the transmission position (X, Y) of the optical signal (the coordinate value on the road side of the uplink position) can be obtained by coordinate conversion based on a geometric linear relationship. it can.

Therefore, when the main CPU 30 acquires the position data from the position IC, the main CPU 30 converts the value of the coordinate (x, y) of the position data into the value of the coordinate (X, Y) on the road side by the above coordinate conversion, and the uplink position. Ask for.
When obtaining the road side coordinates (X, Y) at the position IC29, the position IC29 also performs the coordinate conversion described above. In this case, the position data output from the position IC 29 is a value based on the coordinates (X, Y) on the road side.

FIG. 33 is a flowchart illustrating an example of reception restriction processing by the main CPU 30.
As shown in FIG. 33, the main CPU 30 always determines whether or not uplink data has been acquired from the communication IC 28 (step ST51). If uplink data has been acquired, it further acquires position data from the position IC 29. It is determined whether or not (step ST52).

When the determination result of step ST52 is negative, the main CPU 30 returns the process to step ST51.
If the determination result of step ST52 is affirmative, the main CPU 30 determines whether or not the acquired uplink data is the high-speed frame UL2 (step ST53). In this determination, the in-vehicle device type value of the uplink frame is a predetermined value (for example, “6”) indicating the new in-vehicle device 2A, and the information type value is a predetermined value (for example, “ 4 ”).

  If the determination result in step ST53 is negative, that is, if the uplink frame is the low-speed frame UL1 that triggers downlink switching, the main CPU 30 stores the latest position data stored in the memory at that time. After adopting the coordinate value (X, Y) (step ST54), it is determined whether or not the uplink position of the low-speed frame UL1 indicated by the coordinate value (X, Y) is downstream of the “fixed point position”. (Step ST56).

  The “fixed point position” is a position set in advance as a threshold value, and is located upstream of the second uplink upstream end P2 (see FIG. 30), and the second uplink upstream end from the first uplink upstream end P1. The position is set to be close to P2. In this countermeasure example, for example, when the second uplink upstream end P2 is set as the upstream end of the uplink area UA (a position that is 6.04 m from immediately below the beacon), the fixed point position is a position that is 7.00 m from immediately below the beacon. Is set to

If the determination result of step ST56 is negative, that is, if the uplink position of the low-speed frame UL1 is upstream or at the same position as the fixed point position, the process is returned before step ST51.
Accordingly, the low speed frame UL1 in this case is not received in the information processing in the main CPU 30.

If the determination result of step ST56 is affirmative, that is, if the uplink position of the low-speed frame UL1 is downstream of the fixed point position, the main CPU 30 generates the downlink frame DL2 (step ST57).
In this case, in order to respond to the reception of the low-speed frame UL1 that triggers the downlink switching, the main CPU 30 performs the downlink switching and the continuous transmission of the return frame, and then the sub-frame described in the low-speed frame UL1 acquired this time. Provided information corresponding to the system key information is included in the downlink frame DL2.

If the determination result in step ST53 is affirmative, that is, if the uplink frame is the high-speed frame UL2 that does not trigger downlink switching, the main CPU 30 coordinates the position data stored in the memory at that time. After discarding the value (X, Y) (step ST55), the downstream frame DL2 is generated (step ST57).
In this case, in order to respond to reception of the high-speed frame UL2 that does not trigger downlink switching, the main CPU 30 includes provision information corresponding to the subsystem key information acquired last time in the downlink frame DL2 without performing downlink switching. .

  As described above, according to the new light beacon 4A of the countermeasure example 2, the main CPU 30 determines that the uplink position of the low-speed frame UL1 is a fixed point position (a position closer to the second uplink upstream end P1 than the first uplink upstream end P1). Only when it is on the downstream side of the threshold value), the reception limiting process (FIG. 33) for performing downlink switching based on the low-speed frame UL1 is executed.

That is, even if the new vehicle-mounted device 2A transmits the low-speed frame UL1 at a position farther upstream than the second uplink upstream end P2 (position closer to the first uplink upstream end P1), downlink switching is not performed. Downlink switching is performed only when the in-vehicle device 2A transmits the low-speed frame UL1 at a position close to the second uplink upstream end P2.
By executing the reception limiting process, the uppermost stream end of the area capable of receiving the low-speed frame UL1 is not the first uplink upstream end P1 which is the “physical” uppermost stream end but the second uplink upstream end P2. The first upstream upstream end P1 ′, which is the “logical” uppermost stream end, is set at a close position (see FIG. 30).

  For this reason, even if the low-speed frame UL1 is transmitted at a position far upstream from the second uplink upstream end P2, the main CPU 30 ignores the low-speed frame UL1 and is the first “logical” upstream end. Only when it is the low-speed frame UL1 transmitted downstream from the uplink upstream end P1 ′, downlink switching is performed.

  Therefore, even when the high-speed frame UL2 transmitted after the low-speed frame UL1 is transmitted upstream of the second uplink upstream end P2, it is transmitted at a position close to the second uplink upstream end P2. The new optical beacon 4A can increase the possibility of appropriately receiving the high-speed frame UL2 transmitted after the low-speed frame UL1.

In this countermeasure example, a two-dimensional PSD is adopted as the position measurement PSD 36. However, a one-dimensional PSD in which the x direction of the light receiving surface is arranged along the vehicle traveling direction may be adopted. Good.
Moreover, although PSD36 is employ | adopted as a conversion element for position measurement, division | segmentation PD (refer FIG. 15, FIG. 16 of patent document 1) may be employ | adopted instead of this.

  In this countermeasure example, the apparent first uplink upstream end P1 ′ is set in the information processing of the main CPU 30, but the low-speed and high-speed reception systems provided in the optical reception unit 11 are used. By performing the optical setting (see FIGS. 19 and 20 of Patent Document 1), the second uplink upstream end P2 which is the “physical” uppermost stream end is the first “physical” uppermost stream end. The positions of the upstream ends P1 and P2 may be set so as to be closer to the upstream side than the one upstream upstream end P1.

[Other variations]
The embodiments (including modifications) disclosed herein are illustrative and non-restrictive in every respect. The scope of rights of the present invention is not limited to the above-described embodiments, but includes all modifications within the scope equivalent to the configurations described in the claims.
For example, in the present specification, the “on-vehicle device” includes those that are always fixed to the state after being mounted on the vehicle 20, and are brought into the vehicle 20 only when the driver wants to use them, and are temporarily The thing mounted in the vehicle 20 is also included.

DESCRIPTION OF SYMBOLS 1 Traffic control system 2 Vehicle equipment 2A New vehicle equipment 2B Old vehicle equipment 3 Central apparatus 4 Optical beacon 4A New light beacon 4B Old light beacon 5 Communication line 6 Communication part 7 Beacon controller (communication control part)
8 Beacon head 10 Optical transmission unit 11 Optical reception unit 13 Post 14 Construction bar 20 Vehicle 21 On-board controller (communication control unit)
22 On-vehicle head 23 Optical transmitter 24 Optical receiver 26 First light receiving system 27 Second light receiving system 28 Communication IC
29 Position IC
30 Main CPU
32 Conversion element 33 Amplifier 34 Filter 35 Comparator 36 Conversion element 37 Amplifier 38 Peak hold circuit R Road R1-R4 Lane A Communication area UA Uplink area DA Downlink area UL1 Low speed frame (up frame)
UL2 high-speed frame (upstream frame)
U0 Low-speed frame (upstream frame)
U1-U3 high-speed frame (upstream frame)
DL1 downlink frame (before downlink switching)
DL2 downlink frame (after downlink switching)

Claims (18)

An in-vehicle device that is mounted on a vehicle and performs wireless communication with an optical beacon and an optical signal installed on a road,
An optical receiver capable of photoelectric conversion at a predetermined transmission rate;
An optical transmitter capable of electro-optical conversion at two transmission speeds, high and low,
A communication control unit capable of transmitting one or more high-speed frames after transmission of the low-speed frames,
The communication control unit is an in-vehicle device that retransmits a predetermined high-speed frame when a predetermined condition is satisfied.   The in-vehicle device according to claim 1, wherein the predetermined condition is that a downlink frame received from the optical beacon includes reception information that can identify a high-speed frame from which the optical beacon has not been received. .   The in-vehicle device according to claim 1, wherein the predetermined condition is that a downlink frame received from the optical beacon includes retransmission instruction information for instructing retransmission of a high-speed frame.   The in-vehicle device according to claim 1, wherein the predetermined condition is that a predetermined frame provided by the optical beacon is included in a downlink frame received from the optical beacon.   The in-vehicle device according to claim 1, wherein the predetermined condition is that the speed of the vehicle satisfies a predetermined speed condition.   The in-vehicle device according to claim 2, wherein the communication control unit retransmits the high-speed frame that has not been received based on the reception information. An in-vehicle device that is mounted on a vehicle and performs wireless communication with an optical beacon and an optical signal installed on a road,
An optical receiver capable of photoelectric conversion at a predetermined transmission rate;
An optical transmitter capable of electro-optical conversion at two transmission speeds, high and low,
A communication control unit capable of transmitting one or more high-speed frames after transmission of the low-speed frames,
The communication control unit is an in-vehicle device that retransmits an arbitrary high-speed frame among the one or a plurality of high-speed frames.   The communication control unit, when transmitting a plurality of high-speed frames, retransmits a part of the high-speed frames up to K (K is a positive integer) among the plurality of high-speed frames. The in-vehicle device according to any one of claims 5 and 7.   The in-vehicle device according to claim 7, wherein the communication control unit adds the arbitrary high-speed frame of retransmission reliability to an uplink frame group that transmits the one or more high-speed frames.   The communication control unit, when transmitting a plurality of high-speed frames, adds up to K frames (K is a positive integer) from the top of the plurality of high-speed frames to the uplink frame group as retransmission trust. Item 14. The vehicle-mounted device according to Item 9. When the maximum number of high-speed frames that can be included in the uplink frame group is N and the total number of frames of the plurality of high-speed frames is M, the communication control unit satisfies the following formula (1) The in-vehicle device according to claim 10, wherein a part of the high-speed frames from the head to K are added to the uplink frame group as retransmission trust.
K = N−M (1)
Here, N is a positive integer, and M is a positive integer smaller than N.   The in-vehicle device according to claim 1, wherein the communication control unit retransmits all of the plurality of high-speed frames when a plurality of high-speed frames are transmitted. When the maximum number of high-speed frames that can be included in the uplink frame group is N, and the total number of frames of the plurality of high-speed frames is M, the communication control unit is configured to select K high-speed frames from the top. The in-vehicle device according to claim 10, wherein R is added to the uplink frame group as retransmission credit within a range satisfying the following expression (2).
K × R ≦ N−M Formula (2)
Here, N is a positive integer, M is a positive integer smaller than N, K is a positive integer less than or equal to M, and R is a positive integer greater than or equal to 2.   The in-vehicle device according to claim 11 or 13, wherein the N is set according to a speed of the vehicle.   15. The communication control unit according to any one of claims 12 to 14, wherein the communication control unit retransmits the high-speed frame a plurality of times, and sets the number of retransmissions according to the speed of the vehicle. In-vehicle device.   The in-vehicle device according to any one of claims 1 to 15, wherein the communication control unit sets a retransmission interval when retransmitting the high-speed frame according to a speed of the vehicle. An optical beacon that performs wireless communication with an in-vehicle device of a running vehicle using an optical signal,
An optical receiver capable of photoelectric conversion at two transmission speeds, high and low;
An optical transmitter capable of electro-optical conversion at a predetermined transmission rate;
A communication control unit capable of reproducing a low-speed frame or a high-speed frame from the electrical signal output by the optical receiver, and
The communication control unit is an optical beacon that includes reception information that can identify a high-speed frame that has not been received by the own device in a downlink frame that the optical transmission unit performs downlink transmission. An optical beacon that performs wireless communication with an in-vehicle device of a running vehicle using an optical signal,
An optical receiver capable of photoelectric conversion at two transmission speeds, high and low;
An optical transmitter capable of electro-optical conversion at a predetermined transmission rate;
A communication control unit capable of reproducing a low-speed frame or a high-speed frame from the electrical signal output by the optical receiver, and
The communication control unit is an optical beacon that includes retransmission instruction information for instructing retransmission of a high-speed frame in a downlink frame transmitted by the optical transmission unit when there is an unreceived high-speed frame.

Images