JP6056376B2 - WIRELESS COMMUNICATION SYSTEM, ROAD COMMUNICATION DEVICE, COMMUNICATION CONTROL DEVICE, COMPUTER PROGRAM, AND COMMUNICATION METHOD USED FOR THE SAME - Google Patents

Description

  The present invention relates to, for example, a wireless communication system that can be suitably used as a component of an intelligent transport system (ITS).

In recent years, for the purpose of promoting traffic safety and preventing traffic accidents, mobile bodies (vehicles, etc.) receive information from infrastructure devices installed on the road, or exchange information between vehicles, and use these information Thus, an intelligent road traffic system that improves the safety of vehicle travel has been studied (see, for example, Patent Document 1).
A wireless communication system used in such an intelligent road traffic system mainly includes a plurality of roadside communication devices that are infrastructure-side wireless communication devices and a plurality of in-vehicle communication devices (mobile communication devices) that are wireless communication devices mounted on each vehicle. ).

  In this case, the combination of communication performed between each communication subject includes road-to-vehicle (or vehicle-road) communication performed by a roadside communication device and a vehicle-mounted communication device, and vehicle-to-vehicle communication performed between vehicle-mounted communication devices, roadside communication Inter-road communication performed by communication devices is included (see, for example, Patent Document 2).

Japanese Patent No. 2806801 JP 2011-114647 A

  In general, the roadside communication device has a significant effect on traffic management if it is installed at an important intersection that has an extremely high traffic volume and affects traffic on other roads, and an intersection adjacent to this important intersection. It is thought that it is obtained.

Actually, if traffic concentrates on important intersections and intersections adjacent to important intersections, traffic volume will increase even at other intersections, for example, intersections where narrow streets intersect around important intersections. It is possible.
Then, there is a possibility that more effective traffic management can be performed if a roadside communication device is arranged at such an intersection where narrow streets intersect.

However, since the usable frequency band is limited (for example, about 10 MHz) in the above-mentioned intelligent road traffic system, the band is sufficient even by sharing road-to-vehicle communication (road-to-road communication) and inter-vehicle communication. However, it is difficult to secure an extra band for the roadside communication device.
For this reason, it is difficult from the viewpoint of securing radio resources to install roadside communication devices up to intersections where narrow streets around important intersections cross in addition to intersections with heavy traffic such as important intersections.

  The present invention has been made in view of such circumstances, and a wireless communication system capable of performing traffic management more effectively by installing a roadside communication device without wasting wireless resources, and An object is to provide a roadside communication device, a communication control device, a computer program, and a communication method used for this.

(1) The present invention for achieving the above object is a wireless communication system including a plurality of roadside communication devices, wherein the plurality of roadside communication devices are time slots for roadside communication devices arranged in a radio frame. Includes a first roadside communication device that is assigned as a transmission period, and a second roadside communication device that is not assigned a time slot for the roadside communication device, and the second roadside communication device includes: When it is determined that there is a need to transmit wireless data to the roadside communication device, wireless data transmission is performed to the other roadside communication device in a period other than the time slot for the roadside communication device.

According to the wireless communication system having the above configuration, the second roadside communication device transmits wireless data in a period other than the time slot for the roadside communication device assigned to the first roadside communication device. A larger number of second roadside communication devices can be installed on the road without consuming radio resources allocated to the. In other words, according to the present system, it is possible to install a large number of second roadside communication devices in addition to the first roadside communication device without wastefully consuming radio resources. It can be carried out.
The second roadside communication device can receive data transmitted by the first roadside communication device in the time slot assigned to the first roadside communication device. For example, the first roadside communication device is installed in the data. It is possible to include traffic information relating to traffic flow and traffic signal control relating to traffic flow at the designated location. That is, the second roadside communication device has a function of receiving information that contributes to traffic management in the vicinity of itself from the adjacent roadside communication device, so that, for example, the traffic signal control at its installation point is enhanced. Can improve the efficiency of traffic management.

(2) In the wireless communication system, when the second roadside communication device receives predetermined transmission data that is the transmission source of the first roadside communication device, the second roadside communication device transmits data to the other roadside communication device. It is preferable to judge that the necessity has arisen.
In this case, the first roadside communication device can transmit wireless data to the second roadside communication device by transmitting predetermined transmission data.

(3) It is preferable that the predetermined transmission data is an abnormality notification for notifying that a communication abnormality has occurred. In this case, the second roadside communication device has a communication abnormality in the first roadside communication device. By receiving an abnormality notification notifying that it has occurred, wireless data is transmitted to another roadside communication device.

(4) More specifically, when the second roadside communication device receives the abnormality notification, the second roadside communication device can transmit wireless data by transferring the abnormality notification to the other roadside communication device.
As a result, the second roadside communication device can recognize the presence of the roadside communication device in which the communication abnormality has occurred in other surrounding roadside communication devices.

(5) (6) In the wireless communication system, the first roadside communication device is preferably installed at an important intersection or a general intersection, and the second roadside communication device is It is preferable to be installed at an intersection where streets intersect.
In this case, since the second roadside communication device is installed at the intersection where the narrow streets cross each other, even if the wireless data transmission to the in-vehicle communication device or the roadside communication device is restricted, the traffic management is effectively performed. It can be carried out.

(7) (8) Moreover, when the time slot for vehicle-mounted communication apparatuses which are the periods when a vehicle-mounted communication apparatus transmits is provided in the said radio | wireless frame, a said 2nd roadside communication apparatus is for roadside communication apparatuses. As a period other than the time slot, wireless data can be transmitted during the period of the time slot for the in-vehicle communication device in the previous period.
In this case, the second roadside communication device can transmit wireless data during a time slot for the in-vehicle communication device by a carrier sense method.

(9) Further, the present invention is a roadside communication device, and the roadside communication device is not assigned a time slot for a roadside communication device assigned as a transmission period to other roadside communication devices. And a communication control unit for transmitting wireless data to the other roadside communication device in a period other than the time slot for the roadside communication device when it is determined that the necessity of transmitting wireless data to the other roadside communication device has occurred. It is characterized by having.

(10) The present invention is a communication control device for a roadside communication device in which a time slot for a roadside communication device assigned as a transmission period to another roadside communication device is not assigned, and the other roadside communication device When it is determined that there is a need to transmit wireless data to a communication device, wireless data is transmitted to the other roadside communication device in a period other than the time slot for the roadside communication device.

(11) Further, the present invention is a computer program for causing a computer to function as the communication processing device of (10).

(12) The present invention is a communication method performed by a roadside communication device to which a time slot for a roadside communication device assigned as a transmission period to another roadside communication device is not assigned, and the other roadside communication When it is determined that there is a need to transmit wireless data to a vehicle, wireless data is transmitted to the other roadside communication device in a period other than the time slot for the roadside communication device.

  According to the above (9) to (12), traffic management can be performed more effectively without wastefully consuming radio resources.

  ADVANTAGE OF THE INVENTION According to this invention, traffic management can be performed more effectively by installing a roadside communication apparatus without consuming radio resources wastefully.

It is a schematic perspective view which shows one Embodiment of an intelligent road traffic system. It is a figure which shows an example of the aspect of the communication connection of each roadside communication apparatus 2 in this system. It is a block diagram which shows the structure of a roadside communication apparatus. (A) shows a frame, and (b) is a diagram showing the structure (partial) of slots in the frame and how to assign them. It is a figure which shows the slot allocation of each intersection. It is a figure which shows the example of installation of an online roadside communication apparatus, a stand-alone roadside communication apparatus, and a function limited roadside communication apparatus. It is the flowchart which showed the procedure of the transmission process for a function-limited roadside communication apparatus to perform wireless data transmission. It is a figure which shows an example of the radio | wireless frame provided with the slot for a maintenance. FIG. 7 is a sequence diagram for explaining processing in road-to-road communication of the entire system when communication abnormality occurs in the arrangement of roadside communication devices shown in FIG. 6. It is a figure which shows the other aspect of a radio | wireless frame.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[1. Overall system configuration
FIG. 1 is a schematic perspective view showing an overall configuration of an intelligent road traffic system (ITS) according to an embodiment of the present invention. In this embodiment, as an example of the road structure, a grid structure in which a plurality of roads in the north-south direction and the east-west direction intersect with each other is assumed.
As shown in FIG. 1, the intelligent transportation system of this embodiment includes a traffic signal 1, a roadside communication device (radio device) 2, an in-vehicle communication device (radio device) 3 (see FIG. 3), a central device 4, and in-vehicle communication. A vehicle 5 on which the machine 3 is mounted, and a roadside sensor 6 including a vehicle detector, a monitoring camera, and the like are included.

Traffic signal machine 1 and roadside communication machine 2 are installed in each of a plurality of intersections A1-A5, B1-B5, C1-C5, D1-D5. The traffic signal 1 and some roadside communication devices 2 are connected to a router 8 via a wired communication line 7 such as a telephone line. This router 8 is connected to the central device 4 in the traffic control center.
The central device 4 constitutes a local area network (LAN) with the traffic signal device 1 and the roadside communication device 2 in the area that it is in charge of. The central device 4 may be installed on the road instead of the traffic control center.

The roadside sensor 6 is installed in various places on the road in the jurisdiction area for the purpose of counting the number of vehicles flowing into each intersection. The roadside sensor 6 is composed of a vehicle sensor for ultrasonically sensing the vehicle 5 passing underneath, or a monitoring camera for photographing road traffic conditions in time series, and the sensing information and image data are transmitted via the communication line 7. To the central device 4.
In FIG. 1, for simplification of illustration, only one signal lamp is depicted at each intersection. However, at each actual intersection, at least four signal lamps are used for ascending and descending roads that intersect each other. Is installed.

In an intelligent road traffic system, a plurality of roadside communication devices (radio devices) 2 installed at each of a plurality of intersections constituting a wireless communication system are wirelessly communicated with an in-vehicle communication device 3 of a vehicle traveling around the roadside communication device. (Road-to-vehicle communication) is possible.
Each roadside communication device 2 is also capable of wireless communication (inter-road communication) with other roadside communication devices 2 that are located within a predetermined range within which their transmission waves reach.
An in-vehicle communication device (radio device) 3 that also constitutes a wireless communication system performs wireless communication with the roadside communication device 2 and also wirelessly communicates with other in-vehicle communication devices 3 using a carrier sense method (inter-vehicle communication). Is possible.

The traffic signal device 1 and the roadside communication device 2 (online roadside communication device 2a) connected to the central device 4 via the wired communication line 7 are one of all the roadside communication devices 2 included in the area controlled by the central device 4. There is also a roadside communication device 2 (stand-alone roadside communication device 2b) that is not connected to the central device 4 via the wired communication line 7.
In FIG. 1, the roadside communication device 2 installed at intersections A3, B3, C3, and D3 is an online roadside communication device 2a, and the roadside communication devices 2 installed at other intersections are standalone roadside communication devices 2b. is there.

  In FIG. 1, intersections A3, B3, C3, and D3 are important intersections, and the online roadside communication device 2a is mainly installed at an important intersection. An important intersection is an intersection where the load factor is usually large and has a great influence on traffic flow improvement and accident prevention, and generally an intersection where highways intersect.

The stand-alone roadside communication device 2b performs wireless communication with other online roadside communication devices 2a and other stand-alone roadside communication devices 2b, and is used for information necessary for the system such as traffic information, signal information, and device management information. Exchange.
The stand-alone roadside communication device 2b belongs to one of a plurality of subareas provided in the area.
The sub-area is an area including at least one online roadside communication device 2a and a stand-alone roadside communication device 2b wirelessly connected to the online roadside communication device 2a.
In FIG. 1, four stand-alone roadside communication devices 2b installed at the intersections A1, A2, A4, and A5 are connected to the online roadside communication device 2a installed at the intersection A3 by wireless communication. Two groups of roadside communication devices installed at intersections A1 to A5 constitute one subarea.

FIG. 2 is a diagram illustrating an example of a communication connection mode of each roadside communication device 2 in the present system. As shown in the drawing, each online roadside communication device 2a is connected to the central device 4 via a wired communication line 7 and lower devices such as a router and a communication processing device. The stand-alone roadside communication device 2b is communicably connected to the online roadside communication device 2a through road-to-road communication by wireless communication. A plurality of (four in the illustrated example) stand-alone roadside communication devices 2b are connected to one online roadside communication device 2a.
In this system, by connecting a plurality of standalone roadside communication devices 2b to one online roadside communication device 2a, a subarea is configured, and by arranging a plurality of subareas, Control is in progress.

  Returning to FIG. 1, the other roadside communication devices 2 are similarly the group of five roadside communication devices 2 installed at the intersections B1 to B5 and the five roadside communication devices 2 installed at the intersections C1 to C5. The group and the two roadside communication device groups of two installed at the intersections D1 to D5 each constitute a sub-area.

FIG. 3 is a block diagram illustrating a configuration of the roadside communication device 2. As shown in FIG. 3, the stand-alone roadside communication device 2b includes a wireless communication unit (transmission / reception unit) 21 to which an antenna 20 for wireless communication is connected, and a communication processing device 25 that performs communication control processing. .
The communication processing device 25 includes a control unit 23 and a storage unit 24 that stores necessary information. The control unit 23 performs communication control processing for wireless communication and wired communication. The storage unit 24 stores information necessary for wireless communication and priority communication.
The online roadside communication device 2 a connected to the central device 4 via the wired communication line 7 further includes a wired communication unit 22 for communicating with the central device 4 via the wired communication line 7.

In this embodiment, as will be described later, a function-limited roadside communication device 2c may be installed. As shown in FIG. 3, the basic function of the function-limited roadside communication device 2c is substantially the same as that of the stand-alone roadside communication device 2b.
However, the function-limited roadside communication device 2c is functionally restricted in road-to-vehicle communication compared to the stand-alone roadside communication device 2b. This function-limited roadside communication device 2c will be described in detail later.

  The communication processing device 25 of each roadside communication device 2 may have a part or all of its functions configured by a hardware circuit, or part or all of its functions are realized by a computer program. Also good. When some or all of the functions of the communication processing device 25 are realized by a computer program, the communication processing device 25 (control unit 23) includes a computer, and the computer program executed by the computer is stored in the storage unit 24. The

[2. (Wireless communication system etc.)
FIG. 4A shows a radio frame used in the radio communication system. This radio frame has a time axis length (frame length) set to 100 milliseconds. That is, 10 frames are generated per second.
The frame is generated based on, for example, 1 PPS (signal with a period of 1 second) included in a GPS signal received by a GPS receiver (not shown) included in the roadside communication device 2.

FIG. 4B shows a structure (a part) inside one radio frame. As shown in FIG. 4B, one radio frame is configured to include a first slot SL1 and a second slot SL2.
The first slot SL1 is a time slot for road-to-vehicle communication (road-to-vehicle communication period) assigned to the roadside communication device 2, and wireless transmission by the roadside communication device 2 is permitted in this time zone.
On the other hand, the second slot SL2 is a time slot (vehicle communication period) for the in-vehicle communication device 3, and the in-vehicle communication device 3 wirelessly transmits to each other by the carrier sense method using the period of the second slot SL2. It has a function.

The first slots SL1 and the second slots SL2 included in the radio frame are alternately arranged in the time axis direction.
Each first slot SL1 is assigned a slot number i.

One or more first slots SL1 among a plurality of first slots SL1 (for example, 16 first slots) included in the radio frame are allocated to the roadside communication device 2. The roadside communication device 2 recognizes which first slot SL1 is assigned to itself by the slot number i.
When one slot among the plurality of first slots SL1 included in the radio frame is allocated to one roadside communication device 2, for example, the intersection of the first slot SL1 with i = 1 included in the radio frame Assigned to the roadside communication devices 2 of A2, B5, C3, D1, and assigned to the roadside communication device 2 of intersections A3, B1, C4, D2 to the first slot SL1 of i = 2, and the first of i = 3 The slot SL1 is assigned to the roadside communication devices 2 at the intersections A4, B2, C5, and D3, and the i = 4 first slot SL1 is assigned to the roadside communication devices 2 at the intersections A5, B3, C1, and D4. The first slot SL1 with i = 5 is assigned to the roadside communication device 2 at the intersections A1, B4, C2, and D5.

The plurality of roadside communication devices 2 can be divided into groups of roadside communication devices 2 that can use the same slot (transmission period) at the same time because the roadside communication devices 2 do not interfere with each other in road-to-vehicle communication. . In FIG. 4B, the roadside communication device 2 at the intersections A2, B5, C3, D1, the roadside communication device 2 at the intersections A3, B1, C4, D2, the roadside communication device 2 at the intersections A4, B2, C5, D3, and the intersection The roadside communication devices 2 of A5, B3, C1, and D4 and the roadside communication devices 2 of intersections A1, B4, C2, and D5 are divided into five groups.
Even if the roadside communication devices 2 belonging to the same group transmit using the same transmission period, interference does not occur. Therefore, interference is prevented by assigning a different transmission period to each group.

Note that the transmission period assigned differently to each group is also referred to as a time channel. The number of time channels is the same as the number of groups of roadside communication devices 2 that can use the same transmission period.
In FIG. 4B, different first slots SL1 (i = 1 to 5) are assigned to the respective time channels (time channel numbers Ch1 to Ch5).

  FIG. 5 shows a time channel allocation method according to FIG. 4 for the plurality of roadside communication devices 2 shown in FIG. In FIG. 5, the numbers in the circles at the respective intersections indicate the time channel numbers. Each roadside communication device 2 performs road-to-vehicle communication in the first slot SL1 of the time channel number assigned to the own device 2.

  When the same first slot SL1 is assigned to the roadside communication device 2 at the adjacent intersection, the vehicle 5 between the adjacent intersections receives radio waves of road-to-vehicle communication from both roadside communication devices 2, Interference occurs. However, as shown in FIG. 5, by distributing and assigning the same first slot SL <b> 1, interference during road-to-vehicle communication by each roadside communication device 2 can be prevented.

[3. About function-limited roadside communication equipment)
In the present embodiment, the function-limited roadside communication device 2c described above may be installed.
FIG. 6 is a diagram illustrating an installation example of the online roadside communication device 2a, the stand-alone roadside communication device 2b, and the function-limited roadside communication device 2c. The road structure in FIG. 6 has a grid structure including two main roads H that form an important intersection by crossing each other and a plurality of narrow streets S that are narrower than the main road H. ing.
The narrow street S extends in parallel adjacent to both the left and right sides of the main road H, and is provided so as to surround the important intersection. Therefore, the narrow streets S intersect with the main road H, and the narrow streets S also intersect.

Here, the main road refers to a road having a relatively large traffic volume, such as a general national road, a general prefectural road, or a two-lane road on one side.
The narrow streets are roads that are narrower than main roads such as general national roads and general prefectural roads.

In the figure, the online roadside communication device 2a wired to the central device 4 is installed at an important intersection where the main roads H intersect each other.
The stand-alone roadside communication device 2b is installed at a general intersection located around an important intersection.
A general intersection is an intersection where the main road H and the narrow street S intersect as shown in this embodiment, so that the amount of traffic on the secondary road is smaller than that of the main road. An intersection with a low rate.

The online roadside communication device 2 a installed at an important intersection gives information to the surrounding in-vehicle communication device 3 or performs signal control at an important intersection under the control of the central device 4.
In addition, the stand-alone roadside communication device 2b installed at the general intersection around the important intersection is controlled by the central device 4 through the road-to-road communication with the online roadside communication device 2a, and the surrounding in-vehicle communication devices 3 Information and control signals at important intersections. As described above, the online roadside communication device 2a and the stand-alone roadside communication device 2b (first roadside communication device) are assigned the first slot SL1, which is a time slot for use in road-to-vehicle communication. Inter-communication is also performed using the first slot SL1.

  The online roadside communication device 2 a and the stand-alone roadside communication device 2 b are installed along the main road H at intersections with a relatively large traffic volume. For this reason, in the present system, the online roadside communication device 2a and the stand-alone roadside communication device 2b are system-controlled by the central device 4, whereby the traffic flow at intersections with a large amount of traffic can be effectively managed.

On the other hand, the function-limited roadside communication device 2c is installed at a narrow street intersection where the narrow streets S intersect.
The function-limited roadside communication device 2c is not connected to the central device 4 by a wire, like the stand-alone roadside communication device 2b.
The function-limited roadside communication device 2c is not directly controlled by the central device 4 like the stand-alone roadside communication device 2b and the online roadside communication device 2a. The function-limited roadside communication device 2c receives road-to-vehicle communication data and road-to-road communication data transmitted by the roadside communication devices 2 around the own device, and based on that, the narrow street intersection where the own device is installed. The received communication data can be utilized such as autonomously performing signal control.

  Further, the function-limited roadside communication device 2c is functionally limited in wireless communication, particularly wireless transmission in road-to-vehicle communication, and does not have a function of performing wireless data transmission toward the in-vehicle communication device. The wireless data transmission to the other roadside communication device 2 is performed only when the notified notification is received. Further, the function-limited roadside communication device 2c (second roadside communication device) is not assigned the first slot SL1 as a time slot that is a transmission time.

FIG. 7 is a flowchart showing a procedure of a transmission process for the function-limited roadside communication device 2 c to perform wireless data transmission to other roadside communication devices 2.
When receiving the wireless data, the communication processing device 25 of the function-limited roadside communication device 2c determines whether or not the wireless data is roadside communication data (step S0).
When the communication processing device 25 determines that this wireless data is not road-to-road communication data, the wireless data is considered to be road-to-vehicle communication data or the like. If it is determined that the wireless data is not road-to-road communication data, the communication processing device 25 determines that the wireless data includes information necessary for signal control at the intersection where the own device 2c is installed. Information is acquired, and then the wireless data is discarded and the process is terminated (step S5).

When determining that the wireless data is roadside communication data, the communication processing device 25 determines that the transmission source of the roadside communication data that is the received wireless data is an online roadside communication device 2a or a stand-alone roadside communication device 2b. It is determined whether or not (step S1).
When the transmission source of the received roadside communication data is not the online roadside communication device 2a or the stand-alone roadside communication device 2b, the function-limited roadside communication device 2c acquires necessary information included in the roadside communication data. After that, the data is discarded (step S5), and the process is finished.

On the other hand, when the transmission source of the received roadside communication data is the online roadside communication device 2a or the stand-alone roadside communication device 2b, it is determined whether or not the roadside communication data is an abnormality notification (step S2). ).
The abnormality notification is a notification transmitted by the roadside communication when the roadside communication device 2 determines that a communication abnormality has occurred in the roadside communication or the like.

  When the communication processing device 25 acquires the received road-to-road communication data and determines that the road-to-road communication data is an abnormality notification (step S2), the communication processing device 25 sends the road-to-road communication data to another roadside communication device 2. Forward (send) to the destination (step S3). At this time, the communication processing device 25 stores its own ID in the road-to-road communication data as information indicating that the own machine has transferred the road-to-road communication data.

  Here, since the first slot SL1 for transmitting wireless data is not assigned to the function-limited roadside communication device 2c, the communication processing device 25 of the function-limited roadside communication device 2c sets a maintenance slot in the wireless frame. If so, the received inter-road communication data is transferred using the maintenance slot.

FIG. 8 is a diagram illustrating an example of a radio frame in which a maintenance slot is provided.
As shown in the figure, in one radio frame, a first slot SL1 (five in the example) for roadside communication devices allocated as a transmission period to the online roadside communication device 2a and the stand-alone roadside communication device 2b, and In addition, a maintenance slot is provided using one first slot SL1.
This maintenance slot is a time slot that is reserved for use in an emergency in the present system for maintenance and inspection. Therefore, the online roadside communication device 2a and the stand-alone roadside communication device 2b do not perform transmission using this maintenance slot.

The communication processing device 25 of the function-limited roadside communication device 2c according to the present embodiment transfers the inter-road communication data using the maintenance slot, and then ends the processing.
The function-limited roadside communication device 2c may broadcast the roadside communication data when transferring the roadway communication data, or may be a stand-alone roadside other than the transmission source of the received roadside communication data. When the communication device 2b can be specified as a transmission destination, the standalone roadside communication device 2b can be transmitted as the transmission destination.

Returning to FIG. 7, if the communication processing device 25 determines in step S <b> 2 that the received road-to-road communication data is not an abnormality notification, has the own device been designated as the transfer source of the received road-to-road communication data? It is determined whether or not (step S4).
If it is determined that the transfer source of the received roadside communication data is the own device, the communication processing device 25 proceeds to step S3, transfers the received roadside communication data (step S3), and ends the process.

  In step S4, when it is determined that the transfer source of the received road-to-road communication data is not its own device, the communication processing device 25 obtains necessary information such as signal lamp control information included in the received road-to-road communication data. After the acquisition, the data is discarded (step S5), and the process ends.

When the communication processing device 25 of the function-limited roadside communication device 2c according to the present embodiment determines that there is a need to transmit wireless data to another roadside communication device 2, the received roadside communication data is transferred (transmitted). To do.
That is, the communication processing device 25 of the function-limited roadside communication device 2c is configured to transmit predetermined road-to-roadway communication data (the abnormality notification or transfer source is its own device) that is transmitted from the online roadside communication device 2a or the stand-alone roadside communication device 2b. Is determined to be necessary to transmit wireless data to another roadside communication device 2 and is used by the online roadside communication device 2a and the stand-alone roadside communication device 2b. Wireless data is transmitted to other roadside communication devices 2 in a period other than the first slot SL1 for the other roadside communication device.

  Since the narrow streets S intersect each other, the traffic volume of the narrow streets S where the function-limited roadside communication devices 2c are installed is small compared to the important intersections and general intersections. For this reason, compared with an important intersection etc., it is thought that the necessity of installing the roadside communication apparatus 2 in a narrow street intersection is low.

However, in reality, if traffic concentrates at important intersections or general intersections, the traffic volume may increase at other intersections, for example, narrow street intersections around important intersections.
In this respect, in the present embodiment, the function-limited roadside communication device 2c is arranged at the narrow street intersection, so that signal control and the like can be performed at the narrow street intersection, and more effective traffic management can be performed. it can.

On the other hand, in this system, since the frequency band that can be used in wireless communication is limited, it cannot be said that sufficient communication resources are secured even if road-to-vehicle communication and vehicle-to-vehicle communication are shared. However, according to the function-limited roadside communication device 2c of the present embodiment, the first slot for the roadside communication device assigned to the online roadside communication device 2a and the stand-alone roadside communication device 2b is difficult. Since it is not necessary to use SL1, radio resources allocated to both roadside communication devices 2a and 2b are not consumed. As a result, a larger number of function-limited roadside communication devices 2c can be installed on the road.
That is, according to the present system, traffic management can be performed more effectively by installing a large number of function-limited roadside communication devices 2c in addition to both roadside communication devices 2a and 2b without wasting wireless resources. be able to.

  In this system, when the function-limited roadside communication device 2c receives the abnormality notification that the online roadside communication device 2a or the stand-alone roadside communication device 2b is the transmission source or the roadside communication data that is the transmission source is the other device, Since the online roadside communication device 2a or the stand-alone roadside communication device 2b determines that there is a need to transmit wireless data to the roadside communication device 2 of the roadside communication device 2, the roadside communication data such as abnormality notification is transmitted as necessary. If the transmission is performed, the road-side communication data can be transferred to the function-limited roadside communication device 2c.

  When the function-limited roadside communication device 2c receives an abnormality notification indicating that a communication abnormality has occurred in another roadside communication device 2, the function-limited roadside communication device 2c further forwards the abnormality notification to the other roadside communication device 2. The presence of the roadside communication device 2 in which the communication abnormality has occurred can be recognized in the roadside communication devices 2 around the roadside communication device 2c.

  Further, since the function-limited roadside communication device 2c is installed at a narrow street intersection, as described above, it does not have a function of performing wireless data transmission toward the vehicle-mounted communication device, and is a predetermined notification. Even when functionally limited in wireless transmission in road-to-vehicle communication, such as being configured to transmit wireless data to other roadside communication devices 2 only when receiving Can be kept small.

  That is, since the function-limited roadside communication device 2c is functionally restricted in road-to-vehicle communication, it can have a simpler functional configuration than the stand-alone roadside communication device 2b, and the cost can be reduced. it can.

  Next, processing when a communication abnormality occurs performed by a system including the function-limited roadside communication device 2c having the above configuration will be described.

[4. (Processing of the entire system when a communication error occurs)
FIG. 9 is a sequence diagram for explaining processing in road-to-road communication of the entire system when a communication abnormality occurs in the arrangement of the roadside communication device 2 shown in FIG.
Here, in FIG. 6, a communication abnormality has occurred between the online roadside communication device 2a installed at an important intersection and the stand-alone roadside communication device 2b-1 located on the left side of the online roadside communication device 2a. The case where communication between roads becomes difficult will be described.

In FIG. 9, before the communication abnormality occurs between the roadside communication devices 2a and 2b-1, the communication data between the roads is exchanged between them.
Each roadside communication device 2 transmits road-vehicle communication data and the like to the in-vehicle communication device 3. Further, the function-limited roadside communication device 2c-1 receives the road-to-road communication data, the road-to-vehicle communication data, and the like transmitted by the stand-alone roadside communication device 2b-1, and receives necessary information such as signal information included therein. Acquired and used for signal control of the intersection where the own device 2c-1 is installed.

  When a communication abnormality occurs between the two roadside communication devices 2a and 2b-1, the online roadside communication device 2a detects that a communication abnormality has occurred with the stand-alone roadside communication device 2b-1 (step S101). Thereafter, the online roadside communication device 2a transmits a notification (roadside device abnormality notification) indicating that a communication abnormality has occurred with the stand-alone roadside communication apparatus 2b-1 to the central device 4 by wired communication (step S102). ). By this notification, the central device 4 can recognize that a communication abnormality has occurred in the system.

Here, the communication abnormality means that an obstacle is installed between the roadside communication devices 2a and 2b-1, or a building or a tree is installed around the roadside communication devices 2a and 2b-1. Thus, it means a state in which an abnormality occurs in the propagation path between the both-side communication devices 2a and 2b-1, and a predetermined DU ratio cannot be obtained.
The online roadside communication device 2a is configured such that the DU ratio value of the roadside communication data from the standalone roadside communication device 2b-1, the presence / absence of roadside communication data to be transmitted periodically, the stand alone roadside communication device 2b. The occurrence of communication abnormality is detected based on the presence / absence of ACK in the inter-road communication from -1.

  On the other hand, the stand-alone roadside communication device 2b-1 also detects that a communication abnormality has occurred with the online roadside communication device 2a (step S103). The method for detecting the communication abnormality of the stand-alone roadside communication device 2b-1 is the same as that of the above-described online roadside communication device 2a.

  When the stand-alone roadside communication device 2b-1 detects that a communication abnormality has occurred with the online roadside communication device 2a, the stand-alone roadside communication device 2b-1 transmits an abnormality notification indicating that a communication abnormality has occurred as roadside communication data (step). S104).

In the header of the roadside communication data, the ID of the roadside communication device 2 that is the transmission destination of the data (transmission destination ID), the ID of the roadside communication device 2 that is the transmission source of the data (transmission source ID), and the data An area for storing the ID (transfer source ID) of the transfer-side roadside communication device 2 to be transferred is secured.
The stand-alone roadside communication device 2b-1 stores the ID of its own device as the transmission source ID and the transfer source ID, and the ID of the online roadside communication device 2a as the transmission destination ID, and transmits it in the header of the abnormality notification.

Each roadside communication device 2 arranged around the stand-alone roadside communication device 2b-1 receives the abnormality notification transmitted by the stand-alone roadside communication device 2b-1.
For example, the function-limited roadside communication device 2c (including 2c-1) installed at a narrow street intersection adjacent to the general intersection where the stand-alone roadside communication device 2b-1 is installed receives the abnormality notification. To do. At this time, as shown in FIG. 6, there are two narrow street intersections adjacent to the general intersection where the stand-alone roadside communication device 2b-1 is installed, and both of these two locations are function-limited roadside communication devices. 2c is installed.
The abnormality notification is received by both the function-limited roadside communication devices 2c. Here, the description will be given focusing on the function-limited roadside communication device 2c-1 installed at the narrow street intersection on the lower side of the page.

  Upon receiving the abnormality notification from the stand-alone roadside communication device 2b-1, the function-limited roadside communication device 2c-1 further forwards the abnormality notification to another roadside communication device 2 as shown in FIG. (Step S104). At this time, as described above, the function-limited roadside communication device 2c-1 stores the ID of the own device as the transfer source ID in the abnormality notification as information indicating that the own device has transferred the abnormality notification. Further, in order to indicate that the communication different from the normal route is performed in the abnormality notification, the ID of the own device is stored as the transfer route information.

  The abnormality notification transferred by the function-limited roadside communication device 2c-1 is, for example, another stand-alone roadside communication device 2b- disposed at a general intersection adjacent to the function-limited roadside communication device 2c-1 and the online roadside communication device 2a. 2 is received.

  When the other stand-alone roadside communication device 2b-2 receives the abnormality notification, the other stand-alone roadside communication device 2b-2 transfers the notification to the online roadside communication device 2a through the road-to-road communication (step S106). At this time, the stand-alone roadside communication device 2b-2 stores its own ID as a transfer source ID and route information in the abnormality notification.

When the online roadside communication device 2a receives the abnormality notification transferred by the other stand-alone roadside communication device 2b-2, the transmission source of the abnormality notification is determined as a standalone from the transmission source ID stored in the header of the abnormality notification. It recognizes that it is the roadside communication apparatus 2b-1.
The online roadside communication device 2a matches the roadside communication device 2 that has transmitted the abnormality notification and the roadside communication device 2 that the own device has detected a communication abnormality in step S101, both in the stand-alone roadside communication device 2b-1. Recognize what to do.

Further, the online roadside communication device 2a transmits the abnormality notification transmitted by the stand-alone roadside communication device 2b-1 to the other stand-alone roadside communication device 2b-2, so that the other stand-alone roadside communication device 2b- 2, it is recognized that the roadside communication can be performed with the stand-alone roadside communication device 2b-1 that has transmitted the abnormality notification.
Further, when the transfer route information is stored in the abnormality notification, the online roadside communication device 2a is notified of the abnormality notification in the order of the function-limited roadside communication device 2c-1 and the stand-alone roadside communication device 2b-2. You can recognize what has happened.

Therefore, the online roadside communication device 2a performs inter-road communication with the stand-alone roadside communication device 2b-1 by a detour route via the other stand-alone roadside communication device 2b-2 and the function-limited roadside communication device 2c-1. Is determined (step S107). Then, the online roadside communication device 2a transmits the roadside communication data for the stand-alone roadside communication device 2b-1 to the other stand-alone roadside communication device 2b-2 (step S108).
In this case, the online roadside communication device 2a includes its own ID as the transmission source ID, the ID of the stand-alone roadside communication device 2b-1 as the transmission destination ID, and the stand-alone as the transfer source ID. The IDs of the stand-alone roadside communication device 2b-2 and the function-limited roadside communication device 2c-1 can be stored as the alone roadside communication device 2b-2 and the detour route information, and the roadside communication data can be transmitted. .

  The other stand-alone roadside communication device 2b-2 that has received the road-to-road communication data includes the ID of the own device 2b-2 and the function-limited roadside communication device 2c-1 that has transmitted the abnormality notification in the detour route information. Therefore, the road-to-road communication data is transferred by road-to-road communication (step S109).

The function-limited roadside communication device 2c-1 that has received the road-to-road communication data transferred by the other stand-alone roadside communication device 2b-2 has received the detour route information stored in the header of the road-to-roadway communication data. It can be recognized that it is necessary to transfer roadside communication data.
Then, as shown in FIG. 7, the function-limited roadside communication device 2c-1 transfers the received roadside communication data as it is (step S110).

  The stand-alone roadside communication device 2b-1 that has received the road-to-road communication data transferred by the function-limited roadside communication device 2c-1 receives the transmission destination ID and the transmission source ID stored in the header of the received roadway communication data. Based on the transfer source ID and the detour route information, the communication data is recognized as road-to-road communication data addressed to the own device 2b-1, and the function-limited roadside communication device 2c-1 and other stand-alone roadside communication devices 2b. It recognizes that the road-to-road communication is performed by the detour route via -2.

The stand-alone roadside communication device 2b-1 uses the function-limited roadside communication device 2c-1 and other stand-alone roadside communication devices 2b-2 for inter-road communication data for the subsequent online roadside communication device 2a. Wireless data transmission is performed by a detour route.
At this time, the stand-alone roadside communication device 2b-1 has its own ID as the transmission source ID, the online roadside communication device 2a as the transmission destination ID, the ID of the function-limited roadside communication device 2c-1 as the transfer source ID, and the detour. Stores route information. As a result, the function-limited roadside communication device 2c-1 transfers the roadside communication data transmitted by the stand-alone roadside communication device 2b-1.

  Thus, in this system, even if a communication abnormality occurs between the roadside communication devices 2 by installing the function-limited roadside communication device 2c-1 at the narrow street intersection, the other roadside communication devices 2, A detour path can be configured by the function-limited roadside communication device 2c arranged around the system, and the system function can be maintained.

[5. Others]
The present invention is not limited to the above embodiment. The wireless frame of the above embodiment is provided with a maintenance slot as a period other than the first slot SL1 for road-to-road communication used by the online roadside communication device 2a and the stand-alone roadside communication device 2b. The communication device 2c has shown the case where the communication data between the roads is transmitted using this maintenance slot. For example, when there is no maintenance slot or the like, as shown in FIG. The function-limited roadside communication device 2c may be caused to transmit inter-road communication data using the period of the second slot SL2, which is a time slot.
In this case, in accordance with the communication mode of the in-vehicle communication device 3, the function-limited roadside communication device 2c wirelessly transmits roadside communication data such as abnormality notification by the carrier sense method.

  Moreover, in the said embodiment, although the function-limited roadside communication apparatus 2c showed the case where the abnormality notification from the other roadside communication apparatus 2 was received and transmitted, the vehicle-mounted communication apparatus 3 and pedestrian around the own apparatus carried. By receiving the emergency information transmitted by the terminal or the like and transferring it to the online roadside communication device 2a, it is possible to collect information on the abnormality that has occurred in the jurisdiction area.

  Further, when the function-limited roadside communication device 2c includes a sensor for detecting a disaster such as an earthquake, rainfall, flood, etc., information indicating an abnormality obtained by detecting an abnormality with these sensors is obtained as an inter-road communication. You may comprise so that it may transmit to the other roadside communication apparatus 2 as data.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

2 Roadside communication device 2a Online roadside communication device (first roadside communication device)
2b-1 Stand-alone roadside communication device (first roadside communication device)
2b-2 Stand-alone roadside communication device (first roadside communication device)
2c Function-limited roadside communication device (second roadside communication device)
DESCRIPTION OF SYMBOLS 3 In-vehicle communication apparatus 4 Central apparatus 5 Vehicle 23 Control part 24 Memory | storage part 25 Communication processing apparatus

Claims (12)

A wireless communication system including a plurality of roadside communication devices,
The plurality of roadside communication devices are not assigned a first roadside communication device in which a time slot for roadside communication devices arranged in a radio frame is assigned as a transmission period, and a time slot for the roadside communication device is not assigned. A second roadside communication device,
When the second roadside communication device determines that there is a need to transmit wireless data to another roadside communication device, the second roadside communication device transmits wireless data to the other roadside communication device in a period other than the time slot for the roadside communication device. A wireless communication system characterized by transmitting.   When the second roadside communication device receives predetermined transmission data from which the first roadside communication device is a transmission source, the second roadside communication device determines that it is necessary to transmit wireless data to the other roadside communication device. Item 2. The wireless communication system according to Item 1.   The wireless communication system according to claim 2, wherein the predetermined transmission data is an abnormality notification for notifying that a communication abnormality has occurred.   4. The wireless communication system according to claim 3, wherein, when the second roadside communication device receives the abnormality notification, the second roadside communication device transmits wireless data by transferring the abnormality notification to the other roadside communication device.   The wireless communication system according to any one of claims 1 to 4, wherein the first roadside communication device is installed at an important intersection or a general intersection.   The wireless communication system according to any one of claims 1 to 5, wherein the second roadside communication device is installed at an intersection where narrow streets intersect. The wireless frame is provided with a time slot for an in-vehicle communication device that is a period in which the in-vehicle communication device transmits,
The wireless communication system according to any one of claims 1 to 6, wherein the second roadside communication device transmits wireless data during a time slot for the in-vehicle communication device.   The wireless communication system according to claim 7, wherein the second roadside communication device transmits wireless data during a time slot for the in-vehicle communication device by a carrier sense method. A roadside communication device,
The roadside communication device is not assigned a time slot for a roadside communication device assigned as a transmission period to other roadside communication devices,
When it is determined that there is a need to transmit wireless data toward the other roadside communication device, a communication control unit is provided that transmits wireless data to the other roadside communication device in a period other than the time slot for the roadside communication device. A roadside communication device characterized by A communication control device for a roadside communication device that is not assigned a time slot for a roadside communication device assigned as a transmission period to another roadside communication device,
When it is determined that there is a need to transmit wireless data to the other roadside communication device, wireless data transmission is performed to the other roadside communication device in a period other than the time slot for the roadside communication device. Control device. A computer program for causing a computer to function as the communication control device according to claim 10. A communication method performed by a roadside communication device that is not assigned a time slot for a roadside communication device assigned as a transmission period to another roadside communication device,
When it is determined that there is a need to transmit wireless data to the other roadside communication device, wireless data transmission is performed to the other roadside communication device in a period other than the time slot for the roadside communication device. Method.

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