JP6337920B2 - Light beacon - Google Patents

Description

The present invention relates to an optical beacon that performs wireless communication between road vehicles using an optical signal.

As a traffic information service using a road-to-vehicle communication system, so-called VICS (Vehicle Information and Communication System: registered trademark of Road Traffic Information Communication System Center) using optical beacons, radio beacons or FM multiplex broadcasting has already been developed. ing.
Among these, the optical beacon employs optical communication using near infrared rays as a communication medium, and is capable of bidirectional communication with the in-vehicle device. Specifically, uplink information including travel time information between beacons held by the vehicle is transmitted from the in-vehicle device to the infrastructure-side optical beacon.

On the other hand, downlink information including traffic jam information, section travel time information, event regulation information, lane notification information, and the like is transmitted from the optical beacon to the in-vehicle device (see, for example, Patent Document 1).
For this reason, the optical beacon includes a beacon head (projector / receiver) that transmits / receives an optical signal to / from the vehicle-mounted device, and the transmitter / receiver inputs the transmission signal input from the beacon controller to the light emitting diode. An optical transmitter that transmits downlink light and an optical receiver that converts an optical signal received by the photodiode into an electrical signal and outputs the electrical signal to the beacon controller are mounted.

JP 2005-268925 A

Between 1993 and the present, about 54,000 heads of optical beacons have been deployed on roads throughout the country, but the communication capacity has been expanded compared to conventional optical communication systems using such existing optical beacons. It is being considered to improve the system.
As measures for expanding the communication capacity, there are measures such as increasing the transmission rate for each of the uplink and downlink, expanding the communication area, or changing the communication protocol. Of these, if the uplink speed is increased from the current level (64 kbps), a large amount of probe data can be collected from the optical beacon without greatly expanding the communication area, which can be used to enhance traffic signal control. .

As described above, in order to realize a higher uplink speed, an optical beacon (hereinafter also referred to as “new optical beacon”) corresponding to high-speed uplink reception and an in-vehicle device (hereinafter referred to as “high-speed uplink transmission”). , Also referred to as “new in-vehicle device”).
However, even if new optical beacons and new in-vehicle devices are introduced, these new devices will not be compatible with existing road-to-vehicle communication systems unless they are compatible with conventional devices that can only perform low-speed uplink communication. Increase in link speed is hindered.

For example, when a new optical beacon can receive a high-speed optical signal from a new in-vehicle device, but cannot receive a low-speed optical signal from an in-vehicle device that performs only low-speed uplink transmission (hereinafter also referred to as “old in-vehicle device”). Cannot acquire uplink information from the old in-vehicle device.
In this case, since the new light beacon cannot detect the old in-vehicle device, it cannot perform downlink switching triggered by the uplink transmission of the old in-vehicle device, and cannot provide information for vehicles equipped with the old in-vehicle device. . For this reason, the incentive to newly install a new optical beacon is diminished, and the increase in the uplink speed does not progress.

Similarly, a new in-vehicle device can transmit a high-speed optical signal for a new optical beacon, but a low-speed optical signal for an optical beacon that performs only low-speed uplink reception (hereinafter also referred to as “old optical beacon”). Cannot transmit uplink information to the old optical beacon.
In this case, since the old optical beacon cannot detect the new in-vehicle device, it is not possible to perform downlink switching triggered by the uplink transmission of the new in-vehicle device, and to provide information for vehicles equipped with the new in-vehicle device. Can not. For this reason, the incentive to newly install a new in-vehicle device is reduced, and the increase in the uplink speed does not progress.

The present invention, according view of the conventional problems, and purpose thereof is to provide a multi-rate at which Shinko beacons in the uplink direction.

(1) The optical beacon of the present invention relates to an optical beacon having two systems of analog receiving circuits in accordance with two types of transmission rates, high and low.
That is, the optical beacon 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 receiver that can perform photoelectric conversion at two high and low transmission rates; A signal processing unit that performs digital signal processing on a reception signal output from the optical reception unit, wherein the optical reception unit converts the received optical signal into an electrical signal, and the following first and second and a receiving circuit, the signal processing unit, based on the CRC value both of the receiving circuit is calculated, the transmission rate of the received signal, wherein the determining which one of the high or low speed .

First receiving circuit: a low-speed amplifier circuit that operates and amplifies the converted electric signal in a low-speed band, a low-speed filter that can extract a low-speed component of the amplified electric signal, and the extracted low-speed signal as a threshold value A reception circuit including a low-speed comparator that outputs a digital reception signal for comparison and calculates a CRC value of the reception signal. Second reception circuit: High-speed amplification that operates and amplifies the converted electric signal in a high-speed band. A high-speed filter capable of extracting a circuit, a high-speed component of an amplified electric signal, a digital received signal by comparing the extracted high-speed signal with a threshold value, and calculating a CRC value of the received signal Receiving circuit including a comparator

According to the optical beacon of the present invention, the optical receiving unit includes a light receiving element that converts a received optical signal into an electrical signal, and the first and second receiving circuits, and the signal processing unit includes both receiving circuits. Therefore, it is determined whether the transmission speed of the received signal is high speed or low speed based on the CRC value calculated by the Appropriate digital signal processing can be performed.
Therefore, it is possible to provide an optical beacon that supports multi-rates in the uplink direction and that can receive uplink at two types of transmission rates, high and low, and the object is achieved.

( 2 ) The optical beacon of the present invention viewed from another point of view relates to an optical beacon having a single analog receiving circuit capable of receiving two types of transmission rates, high and low.
That is, the optical beacon of the present invention includes an optical receiving unit capable of uplink reception at two types of transmission rates, high and low, and a signal processing unit that performs digital signal processing on a reception signal output from the optical receiving unit. the light receiving unit includes a light receiving element for converting the optical signal received into an electric signal, and a subsequent common receiver circuit, the signal processing unit to said received signal said common receiving circuit outputs Thus, bit synchronization is performed at two types of high speed and low speed, and the transmission speed with which synchronization is established is determined to be the transmission speed of the received signal .

Co-receiver circuit: a common amplifier circuit for amplifying the converted electrical signals operating at high speed band, and a shared filter extractable both low speed component and high speed component of the amplified electrical signal, the extracted signal A receiving circuit including a shared comparator that outputs a digital received signal in comparison with a threshold value

According to the optical beacon of the present invention, the optical receiving unit includes a light receiving element that converts a received optical signal into an electric signal and the shared receiving circuit, and the signal processing unit is faster than the shared receiving circuit . Since bit synchronization is performed with two types of low speeds and the transmission speed of which synchronization has been established is determined to be the transmission speed of the received signal , either the old in-vehicle device or the new in-vehicle device is the transmission source. In addition, the received signal can be appropriately digital signal processed.
Therefore, it is possible to provide an optical beacon that supports multi-rates in the uplink direction and that can receive uplink at two types of transmission rates, high and low, and the object is achieved.
If a comparator that can compare both the high-speed signal and the low-speed signal that passed through the common filter, or a comparator that performs comparison processing alternatively by specifying whether it is high-speed or low-speed, is used as the common comparator. Good.

As described above, according to the present invention, a multi-rate at which Shinko beacons is obtained in the uplink direction.

It is a block diagram which shows schematic 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 conceptual diagram which shows the procedure and data content of the road-vehicle communication performed in a communication area. 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 flowchart which shows the upward compatible control of a new vehicle equipment. It is a figure which shows the specific example of the downlink transmission after downlink switching. It is a figure which shows the modification of the downlink transmission after downlink switching. It is a circuit block diagram which shows the internal structure of the optical receiver of an optical beacon. It is a circuit block diagram which shows the modification of the internal structure of the optical receiver of an optical beacon.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Overall system 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 traveling on a road R.

The traffic control system 1 includes a central device 3 provided in a traffic control room and the like, and a large number of optical beacons (optical vehicle detectors) 4 installed in various places on the road R. The optical beacon 4 transmits near infrared rays. Wireless communication can be performed with the in-vehicle device 2 by optical communication as a communication medium.
The optical beacon 4 includes a beacon 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. .

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 includes, for example, a traffic signal controller that controls the color of a signal lamp, an information relay device that relays traffic information on the infrastructure side, and the like.

[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 transmission unit 10 converts a downstream frame (parallel electrical signal) transmitted from the beacon controller 7 into a serial transmission signal having a predetermined transmission rate, and outputs the output transmission signal in the downlink direction. It is composed of a light emitting element made of a light emitting diode or the like that converts the signal.
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 photoelectric conversion at two types of transmission rates, high and low, and the lower transmission rate is 64 kbps as in the conventional old optical beacon. It is. 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 1024 kbps. A specific example (FIGS. 10 and 11) of the receiving circuit of the optical receiving unit 11 will be described later.

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 of (four in the illustrated example) lanes R1 to R4 in the same direction, and corresponds to the lanes R1 to R4. A plurality of beacon heads 8 provided, and one beacon controller 7 serving as a control unit that collectively controls these beacon heads 8 are provided.

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.

Among these, the downlink area DA is an area in which an in-vehicle head 22 that is a projector / receiver of the in-vehicle device 2 can receive an optical signal in the downlink direction transmitted from the beacon head 8. d, a range indicated by Δdac having apexes at positions a and c at a height of 1 m above the ground.
The uplink area UA is an area where the beacon head 8 can receive an optical signal in the uplink direction transmitted from the in-vehicle head 22, and the light projecting / receiving position d and the positions b and c at a height of 1 m above the ground. This is the range indicated by Δdbc as the apex.

Accordingly, the upstream end c of the downlink area DA and the uplink area UA coincide with each other, and the uplink area UA overlaps with the upstream portion of the downlink area DA in the vehicle traveling direction (the right side portion in FIG. 3). Further, the vehicle traveling direction length of the downlink area DA coincides with the same direction length of the entire communication area A.
In the case of the old optical beacon (optical vehicle sensor), the formal area dimensions of the downlink area DA and the uplink area UA are defined by the regulations.

For example, in the case of an old optical beacon for general roads, 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.
Further, 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 of the official communication area A in the vehicle traveling direction (the length between ac) 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 at least to the position immediately below the beacon, so that the range in the vehicle traveling direction of the downlink area DA is increased in the high-speed uplink. It is set wider than the old optical beacon that does not support 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 to 6.0 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. .

Further, 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 3.4 to 6.0 m, and the position of the upstream end c is 1. It is extended upstream by 0m.
When the downlink area UA is set 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 that 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 21 and an in-vehicle head 22, and an optical transmitter 23 and an optical receiver 24 are accommodated in the in-vehicle head 22. ing.
Among these, the optical transmission unit 23 has a light emitting element that emits uplink light (uplink direction optical signal) made of near infrared, and the optical reception unit 24 uses near infrared transmitted to the downlink area DA. A light receiving element that receives downlink light (an optical signal in the downlink direction).

The optical transmission unit 23 converts an upstream frame (parallel electrical signal) output from the in-vehicle controller 21 into a serial transmission signal having a predetermined transmission rate, and outputs the output transmission signal in the uplink direction. It is composed of a light emitting element made of a light emitting diode or the like that converts the signal.
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 high and low transmission rates, and the lower transmission rate is 64 kbps as in the conventional old in-vehicle device. It is. 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 1024 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-to-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.

Further, the in-vehicle controller 21 generates traveling data of the host vehicle (for example, probe information that is traveling locus data in which passage positions and passage times are arranged in time series) as uplink data, and the optical transmission unit 24. It also has a function of transmitting to the uplink.
In this case, by increasing the uplink speed, more probe information (information that lengthens the road section that records the travel trajectory or increases the recording density of the passing position and the passing time in the same road section) Can be sent.

[Contents of road-to-vehicle communication]
FIG. 4 is a conceptual diagram showing the procedure and data contents of road-to-vehicle communication performed in the communication area A. Note that the road-to-vehicle communication procedure shown in FIG. 4 is also followed by communication between the optical beacon 4 (new optical beacon) and the in-vehicle device 2 (new in-vehicle device) of the present embodiment.

First, the beacon controller 7 uses the beacon head 8 provided for each of the lanes R1 to R4 to obtain the first downlink information 34 including the lane notification information as the first information before switching the downlink, for each lane R1. The transmission continues to the downlink area DA of ~ R4 at a predetermined transmission cycle (F1 in FIG. 4). At this stage, the vehicle ID is not stored in the lane notification information.
When the vehicle 20 equipped with the in-vehicle device 2 enters the downlink area DA, the in-vehicle head 22 of the in-vehicle device 2 receives the first downlink information 34 including the lane notification information (no vehicle ID).

Thereby, the vehicle-mounted controller 21 recognizes that the vehicle 20 exists in the communication area A of the optical beacon 4.
Thereafter, the in-vehicle controller 21 starts transmission of the uplink information 35 (F2 in FIG. 4), and transmits this uplink information 35 to the beacon head 8 at a predetermined transmission cycle (F3 in FIG. 4).

  In the present embodiment, since the optical beacon 4 and the in-vehicle device 2 are multi-rate compatible in the uplink direction, the in-vehicle device 2 performs uplink transmission of the uplink information 35 at a high transmission rate (1024 kbps). For example, by storing a large amount of data such as probe data in the uplink information 35, it is possible to uplink a larger amount of data to the optical beacon 4 than before.

The in-vehicle controller 21 stores a specific vehicle ID in the uplink information 35 for the vehicle 20 and transmits the uplink information 35. If the vehicle-mounted controller 21 has travel time information between beacons, this information is also uploaded. It is included in the link information 35.
Moreover, the vehicle-mounted controller 21 continues to transmit the uplink information 35 intermittently until it detects that the beacon controller 7 of the optical beacon 4 has switched the downlink.

When the beacon head 8 receives the uplink information 35 (F4 in FIG. 4), the beacon controller 7 switches the downlink within 10 milliseconds at the latest, and then the lane notification information having the vehicle ID information as the second information. The transmission of the 2nd downlink information 36 containing is started (F5 of FIG. 5).
The transmission of the second downlink information 36 is repeated as much as possible within a predetermined time (F6 in FIG. 5).

The lane notification information 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 in-vehicle controller 21 of the vehicle 20 traveling in different lanes R1 to R4 reads which lane R1 to R4 the own vehicle reads by reading which of the vehicle IDs of the own vehicle is included in the storage field. You can determine whether you are running.

The second downlink information 36 can include information such as traffic jam information, section travel time information, and event regulation information in addition to the lane notification information including the vehicle ID.
These pieces of information are also provided to old in-vehicle devices that are not compatible with high-speed uplink transmission. However, in this embodiment, in-vehicle device 2 (new in-vehicle device) of this embodiment that supports high-speed uplink transmission. For example, signal information including the timing of switching the signal lamp color at the intersection, and route information to the nearest charging station, which is useful information when the vehicle 20 is an electric vehicle. Predetermined dedicated information shall be provided.

  The in-vehicle controller 21 determines that downlink switching has been performed in the optical beacon 4 at the time when the second downlink information 36 is received (F7 in FIG. 5), and transmission of the uplink information 35 is performed at this time. To stop.

[Frame structure of downlink information]
As shown in FIG. 4, the downlink information 35 and 36 includes a plurality of minimum unit downlink frames 37.
According to the old optical beacon protocol, the downstream frame 37 includes, in order from the top, a synchronization unit 38 for synchronizing with the receiving side, a header unit 39, a real data unit 40, and a CRC (Cyclic Redundancy Check) unit 41. Have.

1 byte is allocated to the synchronization unit 38, 5 bytes are allocated to the header unit 39, 123 bytes are allocated to the actual data unit 40, and 2 bytes are allocated to the CRC unit 41. Also in the present embodiment, it is assumed that the frame configuration according to this rule is followed. However, although not shown in FIG. 4, there is an idle part for 1 byte between the actual data part 40 and the CRC part 41, and a synchronizing part is further provided after the CRC part 41.
The downlink information 36 transmitted from the optical transmission unit 10 after downlink switching is composed of 1 to 80 downlink frames 37, and the transmittable time during which this downlink frame 37 can be transmitted repeatedly is set to 250 ms. Yes.

  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 37 to be repeatedly transmitted can be increased up to about 200.

The second downlink information 36 is composed of an arbitrary number of downlink frames 37 corresponding to the amount of data to be transmitted in the downlink, and is repeatedly transmitted within the range of the transmittable time. The transmission period of the downstream frame 37 is about 1 ms.
Therefore, for example, when one significant data is constituted by three downlink frames 37, the transmission period of the downlink information 36 is about 3 ms, so that the downlink information 36 is within a predetermined transmittable time (250 ms). Will be transmitted approximately 80 times.

[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 (eg, 1024 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 (eg, 1024 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 (eg, 1024 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 (eg, 1024 kbps). .

In FIG. 5, “DL1” indicates a downlink frame (first downlink information 34 in FIG. 4) transmitted by the old and new optical beacons 4A and 4B before downlink switching, and “UL1” indicates the downlink frame DL1. An uplink frame (uplink information 35 in FIG. 4) transmitted by the new and old vehicle-mounted devices 2A and 2B with reception as an opportunity is shown.
“DL2” indicates a downlink frame (second downlink information 36 in FIG. 4) transmitted by the old and new optical beacons 4A and 4B after downlink switching.

Here, it is assumed that the new optical beacon 4A and the new in-vehicle device 2A that also support high-speed transmission in the uplink direction perform road-to-vehicle communication. If the new and old optical beacons cannot be discriminated, the new in-vehicle device 2A performs uplink transmission at a low speed in order to receive and receive the upstream frame UL1.
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 optical beacon 4 of the present embodiment, the beacon controller 7 includes beacon identification information indicating that the own apparatus is the new optical beacon 4A corresponding to high-speed uplink reception in the downlink frames DL1 and DL2.

Specifically, a flag field indicating the old and new types of optical beacons is defined in advance in the header part 39 of the downlink frames DL1 and DL2 to be transmitted by the optical transmission unit 10 in the downlink.
The beacon controller 7 turns on the flag fields of all the downstream frames DL1 and DL2 when operating the own device as the new optical beacon 4A, and all the operations when operating the own device as the old optical beacon 4B. The flag fields of the downstream frames DL1 and DL2 are turned off.

Therefore, the new vehicle-mounted device 2A can determine that the communication partner is the new optical beacon 4A when the flag field of the received downlink frames DL1 and DL2 is on, and cannot detect the flag field when it is off. If it is determined that the communication partner is the old optical beacon 4B.
Hereinafter, upward compatible control performed by the new optical beacon 4A and the new in-vehicle device 2A on the assumption that the beacon identification information described above is included in the downlink frames DL1 and DL2 will be described.

[Upward compatibility control of Shinko beacon]
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 ON (step ST1 in FIG. 6), so that the own optical device is the new optical beacon 4A. Notifying the outside that there is.

In this state, the beacon controller 7 determines whether or not the uplink frame UL1 has been received (step ST2 in FIG. 6), and continues the downlink transmission in step ST1 until the reception is detected.
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 (1024 kbps in the present 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 vehicle-mounted controller 21 of the new vehicle-mounted device 2A may adopt a rule for including vehicle-mounted device identification information indicating that the device is the new vehicle-mounted device 2A compatible with high-speed uplink transmission in the uplink frame UL1.

Specifically, a flag field indicating the new and old types of the in-vehicle device is defined in advance in the header portion (not shown) of the uplink frame UL that is transmitted by the optical transmission unit 23 in the uplink.
The in-vehicle controller 21 turns on the flag field of the upstream frame UL1 when operating the own device as the new in-vehicle device 2A, and all the upstream frames when operating the own device as the old in-vehicle device 2B. Turn off the flag field of UL1.

  Therefore, if such a rule 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, 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).
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).

As described above, downlink transmission of the downlink frame DL2 in the above steps ST4 and ST5 is performed until a predetermined time (for example, 250 ms) elapses from the downlink switching time.
A specific example of downlink transmission of the downlink frame DL2 in steps ST4 and ST5 will be described later.

[Upward compatibility control of new in-vehicle equipment]
FIG. 7 is a flowchart showing the upward compatible control performed by the in-vehicle controller 21 of the new in-vehicle device 2A that is the in-vehicle device 2 of the present embodiment.
As shown in FIG. 7, the in-vehicle controller 21 of the new in-vehicle device 2A always determines whether or not the downlink frame DL1 has been received (step ST11 in FIG. 7). Then, it is determined whether or not the flag field of the downstream frame DL1 is ON (step ST12 in FIG. 7).

As a result of the determination, if the flag field is on, the uplink frame UL1 is uplink-transmitted at high speed (step ST13 in FIG. 7), and if the flag field is off or there is no field itself, the uplink frame UL1 is uplink-transmitted at a low speed (step ST14 in FIG. 7).
As described above, uplink transmission of the uplink frame UL1 in steps ST13 and ST14 is performed until the in-vehicle controller 21 detects the downlink frame DL2.

[Specific example of downlink transmission]
FIG. 8 is a diagram illustrating a specific example of downlink transmission after downlink switching performed by the beacon controller 7.
Here, “Di” in FIG. 8 is an identification number of the downlink information, the identification numbers D1 to D10 are assigned as downlink information for the old in-vehicle device 2B, and the identifier D11 or more is for the new in-vehicle device 2A. Is assigned as downlink information.

The downlink information for the old vehicle-mounted device 2B includes, for example, the above-described traffic jam information, section travel time information, event regulation information, and the like. Further, examples of the downlink information for the new vehicle-mounted device 2A include the signal information described above and route information to the charging station.
Therefore, the downlink frame DL2 with the identification number D11 in FIG. 8 can be provided only to the new in-vehicle device 2A that supports high-speed uplink transmission, and the downlink frame DL2 with the identification numbers D1 to D3 does not support high-speed uplink transmission. This is a downlink frame that has been conventionally provided to the old vehicle-mounted device 2B, and can also be provided to the new vehicle-mounted device 2A.

  In the following, a frame group consisting only of the downlink frames DL2 (which can also be provided to the new in-vehicle device 2A) having the identification numbers D1 to D3 conventionally provided to the old in-vehicle device 2B is referred to as “first frame group”. The frame group including the downlink frame DL2 with the identification number D11 provided only to the new in-vehicle device 2A in addition to the downlink frame DL2 with the identification numbers D1 to D3 is referred to as a “second frame group”.

In step ST4 in FIG. 6, the beacon controller 7 executes “downlink transmission for the old vehicle-mounted device” shown in FIG.
In the downlink transmission for the old vehicle-mounted device, the beacon controller 7 repeatedly transmits the downlink frames DL2 having the identification numbers D1 to D3 in the order of the numbers.

On the other hand, the beacon controller 7 executes “downlink transmission for new in-vehicle device” shown in FIG. 8B in step ST5 of FIG.
In the downlink transmission for the new vehicle-mounted device, the beacon controller 7 repeatedly transmits the downlink frame DL2 in the order in which the downlink frame DL2 with the identification number D11 appears after the downlink frame DL2 with the identification numbers D1 to D3. . That is, the downlink frame DL2 is transmitted in the order of D1, D2, D3, D11, D1,.

Note that the beacon controller 7 may execute “downlink transmission for new in-vehicle device” shown in FIG. 8C in step ST5 of FIG.
In the downlink transmission for this new vehicle-mounted device, the beacon controller 7 repeats the downlink frame DL2 in the order in which the downlink frame DL2 with the identification number D11 is the head and the downlink frame DL2 with the identification numbers D1 to D3 follows. Send. That is, the downlink frame DL2 is transmitted in the order of D11 → D1 → D2 → D3 → D11 →.

Thus, if the transmission order of the downlink frame DL2 with the identification number D11 is advanced, there is an advantage that dedicated information such as signal information useful for the new vehicle-mounted device 2A can be provided to the new vehicle-mounted device 2A more reliably.
However, the transmission order of the downstream frame DL2 with the identification number D11, that is, the position of the identification number D11 in the second frame group is limited to the last case shown in FIG. 8B or the first case shown in FIG. Alternatively, it may be second or third.

[Modified example of downlink transmission]
FIG. 9 is a diagram illustrating a modified example of downlink transmission after downlink switching performed by the beacon controller 7.
Here, when the beacon controller 7 receives the uplink frame UL1, it does not determine the transmission subject of the uplink frame UL1 (step ST3 in FIG. 6), that is, the transmission subject is the new in-vehicle device 2A or the old in-vehicle device. It is assumed that a common downlink transmission is performed regardless of 2B.

In this case, when the downlink frame DL2 with the new identification number D11 is first transmitted in the downlink, the old in-vehicle device 2B that does not know the existence of the identification number D11 determines that the transmission source new light beacon 4A is abnormal, and all the downlink frames There is a possibility of not receiving DL2.
Therefore, in the common downlink transmission shown in FIG. 9A, the beacon controller 7 performs the downlink frame DL2 in the order in which the downlink frame DL2 with the identification number D11 appears after the downlink frame DL2 with the identification numbers D1 to D3. Send repeatedly. That is, the downlink frame DL2 is transmitted in the order of D1, D2, D3, D11, D1,.

  In other words, in the transmission order of FIG. 9A, the second frame group having the identification number D11 last is generated, and the downlink frame DL2 is downlink transmitted in the order in which the second frame group is repeated.

  Thus, if the downstream frame DL2 with the new identification number D11 is transmitted after the downstream frame DL2 with the existing identification numbers D1 to D3, the possibility that the old in-vehicle device 2B performs the abnormality determination as described above is reduced. The old in-vehicle device 2B can receive the conventional downlink frame DL2 more reliably, and there is an advantage that the compatibility with the old in-vehicle device 2B can be improved.

In the common downlink transmission shown in FIG. 9B, the beacon controller 7 transmits the “first frame group” consisting only of the downlink frames DL2 having the identification numbers D1 to D3 and the downlink frame DL2 having the identification numbers D1 to D3. Downlink transmission is performed separately from the “second frame group” to which the downlink frame DL2 having the identification number D11 is added.
For this reason, the first frame group for the old in-vehicle device 2B and the second frame group for the new in-vehicle device 2A can be downlink transmitted substantially equally.

In this modified example, the beacon controller 7 transmits the “first frame group” first, and the “first frame group” and the “second frame group” are alternately repeated in the order in which the “first frame group” and the “second frame group” are alternately repeated. It is designed to perform downlink transmission.
In this way, if the first frame group is transmitted separately from the second frame group, the old in-vehicle device 2B may receive the downlink transmission normally even if the frame selection logic differs depending on the model of the old in-vehicle device. Is expected to increase.

In the modification of FIG. 9B, since the transmission order of the first frame group and the second frame group is alternately set, the first frame group for the old in-vehicle device 2B and the new in-vehicle device 2A. Therefore, it is possible to transmit the second frame group for downlink substantially equally.
Further, in the modification of FIG. 9B, since the first frame group is transmitted in the downlink first, the downlink frame DL2 having identification numbers D1 to D3 that can be recognized by the old and new vehicle-mounted devices 2A and 2B is newly identified. The downlink transmission is performed earlier than the downlink frame DL2 with the number D11, and the old vehicle-mounted device 2B can receive the conventional downlink frame DL2 more reliably.

[Effects of optical beacons and in-vehicle devices]
As described above, according to the optical beacon 4 of the present embodiment, since the multi-rate optical receiver 11 capable of photoelectric conversion at two high and low transmission rates is provided, the old in-vehicle device 2B and the new in-vehicle device 2A can receive optical signals from both.
In addition, according to the in-vehicle device 2 of the present embodiment, since the multi-rate optical transmission unit 23 capable of electro-optical conversion at two types of high and low transmission rates is provided, both the old optical beacon 4B and the new optical beacon 4A are provided. An optical signal can be transmitted.

In addition, in this embodiment, the beacon controller 7 of the optical beacon 4 turns on the flag field of the downlink frame DL1 that the optical transmission unit 10 performs downlink transmission, and the new in-vehicle device 2A that has received the downlink frame DL1 Since high-speed uplink transmission is performed according to the flag field, the new in-vehicle device 2A does not perform low-speed uplink transmission to the new optical beacon 4A.
Therefore, in the road-to-vehicle communication performed between the new optical beacon 4A that supports multi-rate in the uplink direction and the new vehicle-mounted device 2A, it is possible to reliably increase the uplink speed.

[Internal configuration of optical receiver]
FIG. 10 is a circuit configuration diagram showing the internal configuration of the optical receiver 11 of the optical beacon 4.
As shown in FIG. 10, the optical receiver 11 of the present embodiment includes a light receiving element 50 formed of a photodiode that converts a received optical signal in the uplink direction into an electrical signal, and two series connected to the light receiving element 50. First and second receiving circuits 51 and 52.

Digital reception signals output from the reception circuits 51 and 52 are input to a signal processing unit 53 provided in the beacon controller 7.
The signal processing unit 53 is composed of a processor having a decoder for transmission / reception data, an encoder, a DPLL (Digital Phase Locked Loop), a DMAC (Direct Memory Access Controller), etc., and extracts the data of the upstream frame UL1 from the input received signal. Record in the memory 54. Further, the CPU 55 performs relay processing for transmitting data recorded in the memory 54 to an external device such as the central device 3 or performs the above-described communication control.

The first receiving circuit 51 includes, in order from the light receiving element 50 side, a low speed amplifier circuit 51A, a low speed filter 51B, and a low speed comparator 51C.
The low speed amplifier circuit 51A amplifies the electric signal converted by the light receiving element 50 by operating in the low speed band, and inputs the amplified electric signal to the low speed filter 51B. The low speed filter 51B extracts the low speed component of the amplified electrical signal and inputs the extracted low speed signal to the low speed comparator 51C. The low speed comparator 51C outputs a digital reception signal obtained by comparing the input low speed signal with a threshold value to the signal processing unit 53 in the subsequent stage.

The second receiving circuit 52 includes, in order from the light receiving element 50 side, a high speed amplifier circuit 52A, a high speed filter 52B, and a high speed comparator 52C.
The high speed amplifier circuit 52A operates and amplifies the electric signal converted by the light receiving element 50 in a high speed band, and inputs the amplified electric signal to the high speed filter 52B. The high speed filter 52B extracts a high speed component of the amplified electrical signal and inputs the extracted high speed signal to the high speed comparator 52C. The high speed comparator 52C outputs a digital reception signal obtained by comparing the input high speed signal with a threshold value to the signal processing unit 53 in the subsequent stage.

The signal processing unit 55 performs the above-described digital signal processing on the digital reception signals output from the first and second reception circuits 51 and 52, respectively.
As described above, in the present embodiment, the optical receiver 11 includes the light receiving element 50 that converts the received optical signal into an electric signal, and the two systems of the first and second receiving circuits 51 and 52, and performs signal processing. The unit 53 performs digital signal processing on the reception signals output from both reception circuits 51 and 52, respectively.

For this reason, even if the transmission source of the optical signal uplink-received by the optical receiver 11 is either the old in-vehicle device 2B or the new in-vehicle device 2A, the received signal can be appropriately digital signal processed. .
In other words, by performing both the processing performed assuming that the received upstream frame UL1 is transmitted at high speed and the processing performed assuming that the received upstream frame UL1 is transmitted at low speed, whichever of the comparator 51C, 52C is used. Therefore, it is possible to reliably process.

Note that the comparators 51C and 52C can determine whether the processing is normal or not by calculating a CRC value.
That is, for the upstream frame UL1 transmitted at high speed, the CRC value performed by the high speed comparator 52C is normal, and the CRC value performed by the low speed comparator 51C is abnormal. For this reason, by determining which CRC value is normal, the optical beacon 4 can detect whether the upstream frame UL1 is performed at high speed or low speed.

In this case, only the digital data extracted by the comparators 51C and 52C having the normal CRC value may be delivered to the CPU that processes the received digital data of the upstream frame UL1.
As described above, when the optical receiving unit 11 having the circuit configuration shown in FIG. 10 is employed, the optical beacon 4 corresponding to the multi-rate in the uplink direction can be obtained, which can perform uplink reception at two kinds of transmission rates.

[Modification of internal configuration of optical receiver]
FIG. 11 is a circuit configuration diagram showing a modification of the internal configuration of the optical receiver 11 of the optical beacon 4.
As shown in FIG. 11, the optical receiving unit 11 according to this modification includes a light receiving element 50 formed of a photodiode that converts a received optical signal in the uplink direction into an electrical signal, and 1 connected to the light receiving element 50. And a shared receiving circuit 60 for the series.

The digital reception signal output from the shared reception circuit 60 is input to the signal processing unit 53 provided in the beacon controller 7.
The main digital signal processing (decoding and encoding of transmission / reception data) performed by the signal processing unit 53 and the relay processing performed by the CPU 55 are the same as in the case of FIG.

The shared receiving circuit 60 includes a shared amplifier circuit 60A, a shared filter 60B, and a shared comparator 60C in order from the light receiving element 50 side.
Among these, the shared amplifier circuit 60A is a high-speed amplifier circuit that operates in a high-speed band, and the shared filter 60B is a high-pass filter that can extract at least a low-speed component. The shared filter 60B may be a bandpass filter that covers from low speed components to high speed components. The common comparator 60C is a high-speed comparator capable of comparing a high-speed signal with a threshold value.

  The common amplifier circuit 60A amplifies the electric signal converted by the light receiving element 50 by operating in a high speed band, and inputs the amplified electric signal to the common filter 60B. The shared filter 60B extracts a low speed component or a high speed component from the amplified electric signal, and inputs the extracted low speed signal or high speed signal to the common comparator 60C. The shared comparator 60 </ b> C outputs a digital received signal obtained by comparing the input low speed signal or high speed signal with a threshold value to the signal processing unit 53 at the subsequent stage.

The signal processing unit 53 executes processing for determining the transmission rate of the received signal from the received signal output from the shared receiving circuit 60, and performs the above-described digital signal processing on the input received signal at the determined transmission rate. .
Specifically, for example, the signal processing unit 53 performs bit synchronization with respect to an input received signal at two types, high speed and low speed, and sets the transmission rate at which synchronization can be established as the transmission rate of the received signal. It is determined that

Further, the signal processing unit 53 may determine the transmission speed by performing the following processing on the reception signal output from the shared reception circuit 60.
That is, the signal processing unit 53 first regards the received signal as high speed and creates a digital received signal. That is, a received signal is created by sampling at a high sampling rate. Then, CRC calculation processing is performed to determine whether or not the CRC value is normal. If normal, the received signal is output to the signal processing unit 53 as it is.

  On the other hand, if the CRC value is abnormal, there is a high possibility that the received signal was a low speed signal, so the high speed sampled data was resampled to be the same as the result when sampled at a low speed The CRC calculation process is performed on the received signal after the resampling. If the received signal is low speed, the CRC value should be normal, so the received signal after resampling is output to the signal processing unit 53.

If the CRC is not normal after resampling, the data is considered to be noise data, and the data is discarded.
As described above, in this modification, the optical receiving unit 11 includes the light receiving element 50 that converts the received optical signal into an electrical signal, and the single shared receiving circuit 60, and the signal processing unit 53 includes the shared receiving. The transmission speed of the received signal is determined from the received signal output from the circuit 60, and digital signal processing is performed on the received signal at the determined transmission speed.

For this reason, even if the transmission source of the optical signal uplink-received by the optical receiver 11 is either the old in-vehicle device 2B or the new in-vehicle device 2A, the received signal can be appropriately digital signal processed. .
As described above, when the optical receiving unit 11 having the circuit configuration shown in FIG. 11 is employed, the optical beacon 4 corresponding to the multi-rate in the uplink direction can be obtained, which can perform uplink reception at two transmission levels.

[Other variations]
The embodiment disclosed this time (including the above-described modifications) is illustrative in all respects and not restrictive. 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 above-described embodiment, beacon identification information is included in all downlink frames DL1 and DL2, but is included only in downlink frame DL1 including lane notification information transmitted in downlink before downlink switching. May be.
Further, for example, beacon identification information may be included in the downlink frames DL1 and DL2 whose transmission order is odd or even, or beacon identification information may be included in the downlink frames DL1 and DL2 that are generated in a gradually varying cycle. Good.

  In addition, the “on-vehicle device” of the present invention includes those that are always fixed in that state after being mounted on the vehicle 20, and are brought into the vehicle 20 only when the driver wants to use it, and temporarily the vehicle 20. Also included in the.

2 Onboard unit 2A New onboard unit 2B Old onboard unit 4 Optical beacon 4A New optical beacon 4B Old optical beacon 7 Beacon controller (communication control unit)
8 Beacon head 10 Optical transmission unit 11 Optical reception unit 20 Vehicle 21 In-vehicle controller (communication control unit)
22 On-vehicle head 23 Optical transmitter 24 Optical receiver
50 light receiving element 51 first receiving circuit 52 second receiving circuit 53 signal processing unit 60 shared receiving circuit

Claims (2)

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;
A signal processing unit that performs digital signal processing on a reception signal output by the optical reception unit,
The optical receiving unit includes a light receiving element that converts the received optical signal into an electrical signal, and the following first and second receiving circuits, and the signal processing unit includes a CRC calculated by both the receiving circuits. An optical beacon that determines whether a transmission speed of the received signal is high or low based on a value .
First receiving circuit: a low-speed amplifier circuit that operates and amplifies the converted electric signal in a low-speed band, a low-speed filter that can extract a low-speed component of the amplified electric signal, and the extracted low-speed signal as a threshold value A reception circuit including a low-speed comparator that outputs a digital reception signal for comparison and calculates a CRC value of the reception signal. Second reception circuit: High-speed amplification that operates and amplifies the converted electric signal in a high-speed band. A high-speed filter capable of extracting a circuit, a high-speed component of an amplified electric signal, a digital received signal by comparing the extracted high-speed signal with a threshold value, and calculating a CRC value of the received signal Receiving circuit including a comparator 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;
A signal processing unit that performs digital signal processing on a reception signal output by the optical reception unit,
The optical receiving unit includes a light receiving element that converts the received optical signal into an electrical signal and a next shared receiving circuit, and the signal processing unit is configured to output the received signal output from the shared receiving circuit . An optical beacon characterized by performing bit synchronization at two types, high speed and low speed, and determining that the transmission speed with which synchronization has been established is the transmission speed of the received signal .
Shared receiver circuit: A shared amplifier circuit that operates and amplifies the converted electrical signal in a high-speed band, a shared filter that can extract both the low-speed component and the high-speed component of the amplified electrical signal, and the threshold value of the extracted signal Circuit including a shared comparator that outputs a digital received signal in comparison with