JP2014017876A - Communication control device, roadside communication device, mobile communication device, and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication control device, a roadside communication device, a mobile communication device, and a communication system by which efficient use of communication resources is achieved.SOLUTION: A communication control device of the present invention comprises: a determination part 23a for determining whether provided information D1 which one roadside communication device 2 among a plurality of roadside communication devices 2 should transmit is an information amount which can be transmitted during one time slot; and a transmission control unit 23b for making another roadside communication device 2 transmit a part of the provided information D1 which the one roadside communication device 2 should transmit and makes the one roadside communication device 2 transmit a part except the part of the provided information D1 according to determination result of the determination unit 23a.

Description

  The present invention relates to a communication control device, a roadside communication device, a mobile communication device, and a communication system used in, for example, an intelligent transport system (ITS).

In recent years, for the purpose of promoting traffic safety and preventing traffic accidents, advanced road traffic systems that improve the safety of vehicles by receiving information from infrastructure devices installed on the road and utilizing this information have been studied. (For example, refer to Patent Document 1).
This traffic system is mainly composed of a plurality of roadside communication devices that are wireless communication devices on the infrastructure side, and in-vehicle communication devices (mobile communication devices) that are wireless communication devices mounted on each vehicle.

  In this case, the combination of communications performed between the respective communication subjects includes road-to-vehicle (or vehicle-road) communication performed by the roadside communication device and the vehicle-mounted communication device and vehicle-to-vehicle communication performed by the vehicle-mounted communication devices.

Japanese Patent No. 2806801

  In the above traffic system, in order to coexist each communication such as road-to-vehicle communication and road-to-road communication, what kind of communication control is to be performed effectively using a band becomes a problem. In view of this, it has been studied to use a multiple access method in order to perform various communications such as road-to-vehicle and vehicle-to-vehicle within a limited frequency band.

  As this multi-access method, there are frequency division multiplexing (FDMA) and code division multiple access (CDMA), but communication with only a small number of in-vehicle communication devices is assumed in mountainous areas. As a multi-access method for inter-vehicle communication, it is preferable to adopt an autonomous random access method represented by CSMA (Carrier Sense Multiple Access), for example.

However, road-to-vehicle communication and vehicle-to-vehicle communication coexist in an area where roadside communication devices exist. In this case, since the priority of the information handled by the roadside communicator that is the infrastructure side is generally high, a mechanism that gives priority to road-to-vehicle communication and road-to-road communication over vehicle-to-vehicle communication is required. .
Therefore, in order to preferentially transmit information of the roadside communication device, time division multiplexing (TDMA: Time Division) in which the frequency used for communication is time-divided at regular intervals and a time slot dedicated to transmission of the roadside communication device is provided. Multiple access by Multiple Access is enabled.

  Therefore, for example, assuming a communication system composed of a plurality of roadside communication device groups installed at each intersection, a time slot transmitted by each roadside communication device is assigned by the TDMA method, and the remaining time slot is assigned to a vehicle by the CSMA method. It is considered to be a rational communication system to be used for inter-vehicle communication.

Here, as a communication band for ITS, a standard of about 10 MHz width in the 700 MHz band has been studied. However, in the above traffic system, the limited communication resources given by such a relatively narrow bandwidth are not limited. The problem is whether to use it effectively.
That is, in the information transmitted by the roadside communication device, in addition to the signal display information indicating the scheduled color of the traffic signal lamp installed at the intersection, information on the position of the mobile communication device located in the intersection, Road alignment information indicating the road structure such as the length of surrounding roads is included.
Therefore, when the traffic volume in a communication area of a certain roadside communication device increases and the number of mobile communication devices increases, the amount of information that the roadside communication device should transmit increases. If the amount of information to be transmitted increases, the roadside communication device may not be able to transmit all of the information to be transmitted during the time slot (predetermined time zone) allocated by the TDMA method.

However, it does not occur frequently that the traffic volume increases in the communication areas of all roadside communication devices. Even if the traffic volume in the communication area of a certain roadside communication device increases, other roadside communication devices In a communication area, the traffic volume may be small. At this time, in the roadside communication device in which the traffic volume in the communication area has increased, the amount of transmission information increases as the traffic volume increases, and all the information to be transmitted cannot be transmitted, while other roadside communication In the communication area of the aircraft, since the traffic volume is small, there is a case where the amount of transmission information is small with respect to the assigned time slot, resulting in a wasteful transmission time.
Thus, in the conventional communication system, it cannot be said that the communication resources as the whole communication system are effectively used.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a communication control device, a roadside communication device, a mobile communication device, and a communication system capable of effectively using communication resources.

(1) The present invention provides a communication system in which each of a plurality of roadside communication devices transmits roadside information to be transmitted to a mobile communication device on a road to the mobile communication device during a communication time zone assigned in advance. Whether or not the roadside information to be transmitted by one roadside communication device of the plurality of roadside communication devices is an amount of information that can be transmitted during the communication time period. And a part of the roadside information to be transmitted by the one roadside communication device to another roadside communication device according to the determination result of the determination unit, other than the part of the roadside information And a transmission control unit for transmitting the part to the one roadside communication device.

  According to the communication control device having the above configuration, a part of the roadside information transmitted by one roadside communication device is changed to another according to the determination result of whether or not the amount of information can be transmitted during the communication time period. For example, when it is determined that the amount of roadside information transmitted by one roadside communication device is not the amount of information that can be transmitted during the communication time zone. By setting a part of the roadside information to be transmitted to other roadside communication devices, information that cannot be transmitted by one roadside communication device can be transmitted to other roadside communication devices. As a result, communication resources can be utilized across the roadside communication devices, and communication resources can be effectively utilized as the entire communication system.

  Therefore, for example, when the amount of information to be transmitted by the roadside communication device increases due to an increase in the traffic volume of the communication area of one roadside communication device, the amount of information is reduced during the communication time zone of the roadside communication device. Even when transmission is impossible, by transmitting a part of the roadside information to another roadside communication device, information that cannot be transmitted by one roadside communication device can be transmitted to the other roadside communication device. As a result, roadside information to be transmitted by each roadside communication device can be transmitted as the entire communication system.

(2), (3) It is preferable that the roadside information includes first information and second information classified according to a predetermined criterion. In this case, the importance of information, the amount of information, and the like can be classified as predetermined criteria. Specifically, the information is classified according to the update frequency of the information, and the first information is frequently updated with high frequency of update. It is preferable that the update information and the second information be low-frequency update information having a lower update frequency than the first information.
(4) More specifically, the second information is information indicating different contents in each of the plurality of roadside communication devices, and the transmission control unit uses the second information as a part of the roadside information. It is preferable to transmit to the other roadside communication device.
According to this configuration, even when it is determined that the amount of roadside information transmitted by one roadside communication device is not the amount of information that can be transmitted during the communication time zone, The first information having a high update frequency can be preferentially transmitted by the one roadside communication device. Thereby, since the update frequency is high, it is possible to promptly transmit the first information that is information that must be transmitted early in time.
Moreover, the transmission opportunity can be ensured in 2nd information by transmitting with another roadside communication apparatus. In addition, since the second information has a low update frequency, it is not necessary to transmit the second information at an early stage, and even if the second information is transmitted later by another roadside communication device, the effectiveness as information is not impaired.

(5) Moreover, said 2nd information is information which shows the mutually same content in each of these several roadside communication apparatuses, According to the determination result of the said determination part, said 2nd information is made into several division | segmentation information. A division unit may be further provided, and the transmission control unit may cause the other roadside communication device to transmit a part or all of the plurality of pieces of division information as a part of the roadside information.
Also in this configuration, if it is determined that the amount of roadside information transmitted by one roadside communication device is not the amount of information that can be transmitted during the communication time period, the first information with a high update frequency is preferentially set. Can be transmitted by other roadside communication devices. Thereby, the 1st information with high update frequency can be transmitted rapidly.
On the other hand, for the second information with low update frequency, a part or all of the plurality of pieces of division information divided by the division unit is transmitted to the other roadside communication device, so that the transmission opportunity as the whole second information is obtained. Secured.

(6) In addition, at least some of the roadside communication devices among the plurality of roadside communication devices communicate with the mobile communication device using communication media different from roadside communication devices other than the some roadside communication devices. It may be what performs.
In this case, for example, a part other than a part of the roadside information and a part of the roadside information can be transmitted with different communication media, and information according to the characteristics of each communication medium can be transmitted.

  (7) The communication control device may be a roadside communication device or a device provided independently of the mobile communication device, but the roadside communication device may include the communication control device. Good.

  (8) Further, the present invention provides a mobile communication device that receives roadside information transmitted by each of the plurality of roadside communication devices in a communication system including a communication control device having a dividing unit and a plurality of roadside communication devices. A receiving unit that receives the plurality of division information transmitted from each of the plurality of roadside communication devices, and a combining unit that combines the received plurality of division information and restores the second information. It is characterized by that.

  According to the mobile communication device having the above-described configuration, even if a plurality of pieces of division information are received from different roadside communication devices, the second information can be restored by the combining unit, so that the second information can be reliably acquired.

(9) Further, according to the present invention, each of the plurality of roadside communication devices transmits roadside information to be transmitted to the mobile communication device on the road to the mobile communication device during a pre-assigned communication time zone. A communication system comprising: a determination unit that determines whether one roadside communication device can transmit the roadside information during the communication time period; and the one roadside communication according to a determination result of the determination unit It is characterized by comprising a transmission control section for transmitting a part of the roadside information to be transmitted in a machine to other roadside communication equipment.
According to the communication system having the above configuration, communication resources can be effectively used as described above.

  As described above, according to the communication control device, roadside communication device, mobile communication device, and communication system of the present invention, it is possible to effectively use communication resources.

It is a schematic perspective view which shows one Embodiment of an intelligent road traffic system. It is a top view which shows the jurisdiction area of an intelligent transport system. It is a conceptual diagram which shows an example of the time slot in the radio | wireless communication of this system. It is a block diagram which shows the internal structure of a roadside communication apparatus and a vehicle-mounted communication apparatus. It is the schematic diagram which showed the aspect of the provision information stored in the time slot of each roadside communication apparatus installed in each intersection in FIG. It is a block diagram which shows the roadside communication apparatus which concerns on 2nd embodiment of this invention, and the internal structure of a vehicle-mounted communication apparatus. It is the schematic diagram which showed the aspect of the provision information stored in each time slot of the roadside communication apparatus installed in each intersection in FIG. 2 in 2nd embodiment of this invention. It is the schematic diagram which showed the aspect at the time of restoring this while showing the road linear information D divided | segmented in FIG. It is a top view which shows the jurisdiction area of an intelligent transportation system when an optical beacon is installed.

[Overall system configuration]
FIG. 1 is a schematic perspective view showing an embodiment of an intelligent road traffic system (ITS). The intelligent traffic system of this embodiment includes a traffic signal 1, a roadside communication device 2, an in-vehicle communication device 3 (see FIG. 2), a central device 4, a vehicle 5 equipped with an in-vehicle communication device (mobile communication device) 3, and A roadside sensor 6 composed of a vehicle sensor, a surveillance camera, or the like is included.
Each traffic signal 1 and roadside communication device 2 are installed at each of a plurality of intersections Ji (i = 1 to 12 in the example), and are connected to a router 8 via a communication line 7. 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 1 and the roadside communication device 2 of each intersection Ji included in the monitoring area under its control. Therefore, the central device 4 can perform bidirectional communication with each traffic signal 1 and each roadside communication device 2. 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 Ji. The roadside sensor 6 is composed of a vehicle detector that detects the vehicle 5 passing directly below by ultrasonic waves or infrared rays, or a monitoring camera that shoots the traffic situation of the road in time series, and the traffic as the traffic situation of the intersection Ji. The amount is detected and acquired as sensor information indicating the traffic volume of the intersection Ji. The roadside sensor 6 transmits to the central device 4 via the communication line 7 the sensor information obtained by the vehicle detector, which is a sensor signal generated when the vehicle passes.
In FIG. 1 and FIG. 2, only one signal lamp is depicted at each intersection Ji for the sake of simplicity of illustration, but each actual intersection Ji is used for ascending and descending roads that intersect each other. At least four signal lamps are installed.

The central device 4 has a control unit including a workstation (WS), a personal computer (PC), and the like. This control unit centrally collects, processes (calculates) and records various traffic information from the roadside communication device 2 and the roadside sensor 6, performs signal control, and provides information.
The central device 4 has a communication unit that is a communication interface connected to the LAN side via a communication line 7, and this communication unit sends a signal control command relating to the switching timing of the traffic signal 1 at a predetermined time. Transmit to the traffic light 1.
Further, the communication unit of the central device 4 receives from the roadside communication device 2 vehicle information including the current position of the vehicle-mounted communication device 3 (vehicle 5) received by the communication device 2 and the roadside sensor 6. Sensor information including vehicle sensor detection information, image information, and the like is received in substantially real time (for example, in a cycle of 0.1 to 1.0 second), and the control unit of the central device 4 receives these various pieces of information. Based on the above, the system control and the wide area control are executed.
The control unit of the central device 4 generates traffic information including traffic jam information and intersection information related to the traffic status of each intersection by grasping the traffic jam status of the road based on the received vehicle information and sensor information. To do. The central device 4 communicates the signal control command, the signal display information, the traffic information, the road alignment information indicating the shape of the road, and the provision information D1 including the sensor information via the communication unit. It transmits to the machine 2. (See Figure 1)

[Wireless communication systems, etc.]
FIG. 2 is a plan view showing the jurisdiction area of the intelligent transportation system. The traffic system of this embodiment includes a roadside communication device 2 capable of wireless communication with an in-vehicle communication device 3, and a mobile wireless transceiver (mobile communication) that performs wireless communication with other communication devices 2 and 3 using a carrier sense method. A vehicle-mounted communication device 3 which is a kind of a machine. In FIG. 2, the road extending in the vertical direction of the paper constituting the intersection J1 is a two-lane road on one side, and the other roads are exemplified as one-lane roads, but the road structure is limited to this. is not.

The roadside communication device 2 is installed at each intersection Ji on the roadside, and is attached to the column of the traffic signal 1 in FIG. On the other hand, the in-vehicle communication device 3 is mounted on each vehicle 5 traveling on the road.
Each roadside communication device 2 has a predetermined range of communication area A (range in which a transmission signal of the roadside communication device 2 can sufficiently reach) spreading around the roadside communication device 2, and the vehicle-mounted communication device 3 of each vehicle 5 that travels in this communication area A. Wireless communication is possible. In addition, when the communication area A overlaps, each roadside communication device 2 can wirelessly communicate with other roadside communication devices 2 with the same communication area A.

  In the traffic system (communication system) of the present embodiment, between the roadside communication device 2 and the vehicle-mounted communication device 3 (road-to-vehicle communication from “road” to “car” and between roads from “car” to “road”. Wireless communication is used for communication (road-to-vehicle communication) and communication between the vehicle-mounted communication devices 3 (vehicle-to-vehicle communication). The central device 4 can perform two-way communication with each roadside communication device 2 in a wired manner. However, the communication between the central device 4 and the roadside communication device 2 may be wireless communication.

  The roadside communication device 2 allocates time (roadside time slot) for wireless transmission by itself in a time division multiplexing (TDMA) system, and does not perform wireless transmission in a time zone other than the roadside time slot. A time zone other than the time slot for the roadside is opened as a transmission time by the CSMA method for the in-vehicle communication device 3. In this time zone, the plurality of in-vehicle communication devices 3 acquire transmission opportunities by the CSMA / CA method, and perform inter-vehicle communication and inter-road communication.

  In addition, each roadside communication device 2 has a time synchronization function for performing time synchronization with other roadside communication devices 2 in order to control its transmission timing. The time synchronization of the roadside communication device 2 is performed by, for example, GPS synchronization that adjusts its own clock to the GPS time, air synchronization that adjusts its own clock based on a transmission signal from another roadside communication device 2, or the like.

  In the present embodiment, one parent device is selected in advance from the plurality of roadside communication devices 2. This master unit generally has a function of assigning roadside time slots, autonomously assigns slots to itself, and includes a plurality of other roadside communication devices 2 (slave units) managed by the master unit. Therefore, the time slot is also assigned to the slave unit so that the radio interference does not occur.

FIG. 3 is a conceptual diagram showing an example of a time slot in the wireless communication of this system. In FIG. 3, the horizontal axis indicates the time axis, and the time set on the time axis with respect to the roadside communication device 2 and the two other roadside communication devices 2 set as the slave units S1 and S2. Shows the slot.
As shown in the figure, the base unit M (roadside communication device 2) sets a roadside time slot Ta for wireless transmission by itself and other roadside communication devices 2 (child devices S1, S2). Set for each. In the time zone in which the roadside time slot Ta is set, wireless communication by the target roadside communication device 2 is allowed. A time zone other than the time slot Ta for each roadside communication device 2 is opened as a time slot Tb for the vehicle-mounted communication device 3 to perform inter-vehicle communication. For this reason, each roadside communication device 2 does not perform wireless transmission in the in-vehicle time slot Tb. Each roadside time slot Ta and in-vehicle time slot Tb are alternately assigned in a time division manner, and both slots Ta and Tb are repeated at a constant cycle.

More specifically, base unit M sets time slot Ta for transmission by itself at a constant cycle (first cycle Δt1). Further, during this first period Δt1, each time slot Ta for the slave managed by itself is allocated in a predetermined order with a time for the vehicle time slot Tb. As a result, the time slots Ta of these slave units are also set with the first period Δt1.
In the illustrated example, the first period Δt1 is set to 100 milliseconds. Further, when the time slot Ta for the child device S1 is started, the time slot Ta is set for 40 milliseconds after the time slot Ta for the parent device M is started, and when the time slot Ta for the child device S2 is started, the parent device M is set. It is set 70 milliseconds after the start of the time slot Ta. In addition, the time widths of the time slots Ta of the master unit M, the slave unit S1, and the slave unit S2 are set to 4 milliseconds, 4 milliseconds, and 3 milliseconds, respectively.

  The base unit M repeats for each time slot Ta set in the first period Δt1 as described above for each first period Δt1, and is used for roadside for wireless transmission by itself and the slave units S1 and S2. A time slot Ta is set for each roadside communication device 2.

When the base unit M sets each time slot Ta as described above, the base unit M generates slot information D2 indicating the setting, and broadcasts to the in-vehicle communication device 3 using the time slot Ta set for itself. . In addition, the base unit M transmits slot information D2 to the slave unit via road-to-road communication or the central device 4.
By transmitting the slot information D2, the parent device M informs each child device and the in-vehicle communication device 3 that the time slot is set as shown in FIG. Thereby, each roadside communication device 2 and the vehicle-mounted communication device 3 can communicate according to the time slot.

  In the present embodiment, the case where the roadside communication device 2 set in advance as the base unit M has a function of assigning a roadside time slot is exemplified, but this function is provided for each roadside communication device 2. Alternatively, it may be installed on the roadside separately from the roadside communication device 2 or may be provided in the central device 4.

[Configuration of roadside communication device]
FIG. 4 is a block diagram showing the internal configuration of the roadside communication device 2 and the in-vehicle communication device 3.
The roadside communication device 2 includes a wireless communication unit 21 connected to an antenna 20 for wireless communication, a wired communication unit 22 for bidirectional communication with the central device 4, and a processor (CPU: Central: And a storage unit 24 including a storage device such as a ROM or a RAM connected to the control unit 23.
The wireless communication unit 21 can be configured to be normally used for wireless communication, and includes an oscillator, a modulator, a demodulator, an amplifier, and the like.
The storage unit 24 stores a computer program for communication control executed by the control unit 23, communication device IDs of the communication devices 2 and 3, and the like.

When the roadside communication device 2 is set to the above-mentioned base device M, the control unit 23 of the roadside communication device 2 sets a time slot and generates slot information D2 indicating the setting. Then, the wireless communication unit 21 performs wireless communication according to the set time slot, and broadcasts the slot information D2 via the wireless communication unit 21.
When the roadside communication device 2 is set as a child device, the control unit 23 acquires slot information D2 transmitted from the parent device M, and performs wireless communication according to the time slot indicated by the slot information D2. To the wireless communication unit 21. The control unit 23 of the roadside communication device 2 that is the child device further broadcasts the slot information D2.
As described above, the control unit 23 causes the wireless communication unit 21 to perform wireless communication between road vehicles using a time division multiplexing method.

As shown in FIG. 4, the control unit 23 of the roadside communication device 2 includes a determination unit 23a and a transmission control unit 23b.
Among these, the transmission control unit 23 b temporarily stores the vehicle information of the in-vehicle communication device 3 received by the wireless communication unit 21 in the storage unit 24 and transfers the vehicle information to the central device 4 via the wired communication unit 22.
The transmission control unit 23b includes the signal control command from the central device 4 received by the wired communication unit 22, the signal display information, the traffic information, road linear information indicating the shape of the road, sensor information, and the like. The provision information D1 is temporarily stored in the storage unit 24 and broadcasted via the wireless communication unit 21.

Provided information D1 as roadside information transmitted by the roadside communication device 2 includes information acquired by itself from other devices in addition to the information acquired by itself from the central device 4, and is equipped with the in-vehicle communication device 3. This is useful information for safe driving support control by the vehicle 5.
Specifically, the provision information D1 includes the signal control command, the signal display information, the traffic information, road linear information indicating the shape of the road, sensor information, and the like as described above.
The road alignment information is information indicating a road structure from the information providing point to a certain target point or target section, and is information such as a road length, a slope, a degree of a curve, and the like. The road alignment information is information that can be stored in advance by the roadside communication device 2 or acquired from the central device 4.

Of the provided information D1, the signal control command, the signal display information, the traffic information, and the sensor information are temporally dynamic information that changes every moment, and such information has a high update frequency. Thus, the frequently updated information to be transmitted.
In particular, the signal display information may be changed according to the traffic congestion situation on the road where the traffic signal 1 is installed under the control of the signal controller or the central device 4, so information to be transmitted with a high update frequency. It is.
On the other hand, the road alignment information does not need to be continuously updated because the information is valid until it passes through a certain point (intersection or curve) on the road. For this reason, such road alignment information is static information in time, and is low-frequency update information that may be transmitted at a low update frequency.
For example, a unique identifier is assigned to signal display information, vehicle position information, road alignment information, and the like, and whether the information is high-frequency update information or low-frequency update information is specified in advance for each identifier. As a result, signal display information, vehicle position information, road alignment information, and the like can be classified into high-frequency update information or low-frequency update information according to the update frequency of the information.

  As described above, the provided information D1 transmitted by the roadside communication device 2 includes high-frequency update information (first information) with a high update frequency, and low-frequency update information (second information) with a low update frequency. It is comprised including.

  Furthermore, the transmission control unit 23b transmits road linear information, which is low-frequency update information as a part of the provided information D1 to be transmitted, to other roadside communication devices 2 other than itself according to the determination of the determination unit 23a. A transmission request notification is generated and transmitted to the central device 4, and high frequency update information other than road alignment information (low frequency update information) is transmitted as provision information D1 in its own time slot. It has a function to control. Further, when a transmission request notification is received from another roadside communication device 2 other than itself, in response to the notification, road alignment information that is a part of the provided information D1 to be transmitted by the other roadside communication device 2 is changed. It has a function to transmit. These functions will be described in detail later.

  The determination unit 23a has a function of grasping the information amount of the provided information D1 to be transmitted by its roadside communication device 2, and transmitting the information amount to the central device 4 through the wired communication unit 22 at a predetermined frequency. ing. The determination unit 23a has a function of determining whether or not the provision information D1 to be transmitted by the transmission control unit 23b is an amount of information that can be transmitted during the time slot Ta allocated to itself. Yes. The function of the determination unit 23a will be described in detail later.

[In-vehicle communication device]
The in-vehicle communication device 3 is connected to an antenna 30 for wireless communication, and receives a communication unit 31 that receives information including the provision information D1 and the slot information D2, and a processor that performs communication control on the communication unit 31. And a storage unit 33 formed of a storage device such as a ROM or a RAM connected to the control unit 32.
The storage unit 33 stores a computer program for communication control executed by the control unit 32, communication device IDs of the communication devices 2 and 3, and the like.
The control unit 32 of the in-vehicle communication device 3 includes a communication control unit 32a and a notification unit 32b as functional units achieved by executing the computer program.

The communication control unit 32a can cause the communication unit 31 to perform wireless communication by the carrier sense method for vehicle-to-vehicle communication, and has a communication control function in the time division multiplexing method with the roadside communication device 2. Absent.
Therefore, the communication control unit 32a always senses the reception level of the predetermined carrier frequency, and does not perform wireless transmission when the value is equal to or higher than a certain threshold value, and performs wireless transmission only when the value is less than the threshold value. To do.

  In addition, the communication control unit 32a can wirelessly transmit vehicle information including the current position, speed, direction, and the like of the vehicle 5 (the in-vehicle communication device 3) to the outside via the communication unit 31 by broadcast. The position and direction of the vehicle 5 are usually information autonomously measured by sensors on the vehicle 5 side such as GPS, but may be acquired from the infrastructure side such as an optical beacon. The speed is information based on a speed sensor of the vehicle 5.

  The communication unit 31 receives vehicle information about the speed and position of the vehicle 5 transmitted by the other vehicle 5, and the provision information D1 and the slot information D2 transmitted by the roadside communication device 2. When the communication unit 31 receives these pieces of information, the communication control unit 32a can execute processing for safe driving support control based on these pieces of information. That is, when the in-vehicle communication device 3 receives such information, based on the information, the in-vehicle communication device 3 performs a process for safe driving support control for avoiding a right-right collision or a head-on collision, etc. This is performed in cooperation with the mechanism of the vehicle 5.

Further, the communication control unit 32a controls the execution and stop of its own wireless transmission based on the slot information D2 received directly from the roadside communication device 2 or the slot information D2 notified from the other in-vehicle communication device 3. It has a function to perform.
The notification unit 32b has a function of notifying (transferring) the slot information D2 and provision information D1 received by the communication unit 31 to the other mobile communication devices 3 via the communication unit 31. Yes. The slot information D2 and provision information D1 received by the communication unit 31 include information directly received (notified) from another in-vehicle communication device 3 in addition to information directly received from the roadside communication device 2. .

[About functions of determination unit and transmission control unit (first embodiment)]
Next, functions of the determination unit 23a and the transmission control unit 23b of the roadside communication device 2 will be described.
As described above, the roadside communication device 2 broadcasts the provision information D1 including the high-frequency update information with a high update frequency and the low-frequency update information with a lower update frequency.
FIG. 5 is a schematic diagram showing an aspect of provision information stored in each time slot of each roadside communication device installed at each intersection in FIG.
In the following description, it is assumed that the three roadside communication devices 2 installed at the intersections J1, J2, and J3 shown in FIG. 2 form one jurisdiction area.
Further, in FIG. 2, the intersection J1 is configured by intersecting one-sided two-lane main road, and therefore has a larger traffic volume than the other intersections J2, J3 where one-sided one-lane road intersects. It is assumed to be an intersection.

FIG. 5A shows an aspect of provision information stored in each time slot of the roadside communication device 2 when the traffic volume is normal at each intersection. As shown in the drawing, each time slot Ta stores high-frequency update information (broken line hatched portion in the figure) and low-frequency update information (solid line hatched portion in the figure).
Of these, the low-frequency update information is configured by road alignment information. However, in this embodiment, each roadside communication device 2 is configured to transmit the road alignment information of the surrounding area where it is installed. ing. Accordingly, the roadside communication devices 2 (hereinafter also referred to as roadside communication devices 2J1, 2J2, and 2J3, respectively) installed at the intersections J1, J2, and J3 transmit different road alignment information A, B, and C, respectively. .

  In addition, since the frequently updated information includes vehicle information related to vehicles existing in the communication area A set around the intersection (roadside communication device 2), the traffic volume is higher than that of other intersections. The roadside communication device 2J1 at many intersections J1 has a relatively large amount of high-frequency update information than that installed at other intersections. Note that the information amount of the provision information D1 of each of the roadside communication devices 2 is grasped by the transmission control unit 23b possessed by itself and transmitted to the central device 4 at a predetermined frequency as described above.

Here, when the traffic volume at the intersection J1 further increases and the information amount of the frequently updated information to be transmitted by the roadside communication device 2J1 increases, the information amount of the provided information D1 as a whole increases and is transmitted in one time slot Ta. May exceed the amount of information possible.
FIG. 5B shows a state in which the information amount of the provided information D1 to be transmitted by the roadside communication device 2J1 exceeds the information amount that can be transmitted in one time slot Ta.
In FIG. 5B, when the time slot Ta of the roadside communication device 2J1 is viewed, the high frequency update information is increased as compared with the case of FIG. 5A, and the road alignment information that is the low frequency update information. It can be seen that there is not enough time to send A. In addition, since the information content of the road alignment information that is the low-frequency update information is not frequently updated, the amount of information may be considered to be almost constant.

As described above, the determination unit 23a of the roadside communication device 2 grasps the information amount of the provision information D1 to be transmitted by the roadside communication device 2, and the provision information D1 to be transmitted by the transmission control unit 23b is determined by itself. It has a function of determining whether the amount of information that can be transmitted in one allocated time slot Ta.
Therefore, as shown in FIG. 5B, when the information amount of the provided information D1 increases and exceeds the information amount that can be transmitted in one time slot Ta, the determination unit 23 of the roadside communication device 2J1 should transmit It is determined that the provided information D1 is not the amount of information that can be transmitted in one time slot Ta.
When the determination unit 23a determines that the provision information D1 to be transmitted cannot be transmitted in one time slot Ta, the transmission control unit 23b converts the road alignment information that is a part of the provision information D1 to other information other than itself. A transmission request notification for causing the roadside communication device 2 to transmit is generated and transmitted to the central device 4 via the wired communication unit 22.
In addition, the transmission control unit 23b of the roadside communication device 2J1 that has transmitted the transmission request notification uses the high frequency update information that is a part other than the road alignment information (low frequency update information) as the provision information D1 in its own time slot Ta. Control to send.

  When receiving the above transmission request notification, the central device 4 that has received a notification from each roadside communication device 2 about the amount of information to be provided by each roadside communication device 2 is transmitted to the roadside communication device 2J1 that has transmitted the transmission request notification. Reference is made to the information amount of the current provision information D1 to be transmitted by the other roadside communication devices 2J2 and 2J3 in the jurisdiction area to which it belongs.

  Then, the central device 4 selects, for example, another roadside communication device 2 with the smallest amount of the provision information D1 to be transmitted, and forwards a transmission request notification from the roadside communication device 2J1 to the roadside communication device 2. To do. In FIG. 5, the central device 4 transfers the transmission request notification to the roadside communication device 2J2 installed at the intersection J2 where the information amount of the provided information D1 to be transmitted is the smallest.

  When the transmission control unit 23b of the roadside communication device 2J2 receives the transmission request notification, the transmission control unit 23b converts the road alignment information A, which is a part of the provided information D1 to be transmitted by the roadside communication device 2J1, in response to the notification. Transmission is performed using the slot Ta. Here, the roadside communication device 2J2 stores all of the road alignment information A, B, and C in the storage unit 24 in advance, and selects either of them according to the transmission request notification. It can also be transmitted using a slot, or it can be transmitted from the central device 4 at the same time as the transmission request notification and the road alignment information related to the transmission request is transmitted.

  As described above, the roadside communication device 2J1 transmits a transmission request notification to the central device 4 when it determines that the amount of the provision information D1 to be transmitted increases and cannot be transmitted for all the provision information D1. The road alignment information A, which is a part of the provision information D1 to be transmitted by the roadside communication device 2J1, can be transmitted to another roadside communication device 2J2 instead. Thereby, even if the roadside communication device 2J1 does not transmit the road alignment information A, the entire jurisdiction area to which each roadside communication device 2 belongs can secure transmission opportunities of the road alignment information A, B, and C.

  According to the control unit 23 of the roadside communication device 2J1 having the above configuration, the roadside communication device is determined according to the determination result as to whether or not the provided information D1 to be transmitted is the amount of information that can be transmitted during one time slot Ta. Since the transmission control unit 23b that transmits the road alignment information that is a part of the provision information D1 transmitted by 2J1 to the other roadside communication device 2 is provided, the roadside communication device 2J1 transmits the road alignment information as described above. When it is determined that the information amount of the provided information D1 is not the amount of information that can be transmitted during one time slot Ta, a part of the provided information D1 is set to be transmitted to the other roadside communication device 2J2. Information that cannot be transmitted by the roadside communication device 2J1 can be transmitted to the other roadside communication device 2J2. As a result, communication resources can be utilized across the roadside communication devices 2, and communication resources can be effectively utilized as a whole communication system.

  In the above embodiment, the provision information D1 includes high-frequency information with a high update frequency and road alignment information that is low-frequency update information with a lower update frequency than the high-frequency update information. The information is road alignment information A, B, and C showing different contents in each of the roadside communication devices 2J1, 2J2, and 2J3, and the transmission control unit 23b provides the road alignment information according to the determination of the determination unit 23a. It is made to transmit to other roadside communication apparatuses 2 other than self as a part of information D1.

Therefore, even when it is determined that the information amount of the provided information D1 transmitted by the one roadside communication device 2 is not the information amount that can be transmitted during one time slot Ta, the road alignment that is the low-frequency update information By causing the information to be transmitted to the other roadside communication device 2, the high frequency update information can be preferentially transmitted by the one roadside communication device 2. Thereby, since the update frequency is high, the high-frequency update information that is information that must be transmitted earlier in time can be promptly transmitted.
In addition, in the low-frequency update information, the transmission opportunity can be ensured by transmitting by the other roadside communication device 2. In addition, since the update frequency is low, the low-frequency update information is less likely to be transmitted at an early stage, and even if it is transmitted later by another roadside communication device 2, the effectiveness as information is not impaired.

  Moreover, in the said embodiment, when the roadside communication apparatus 2J1 transmitted the transmission request notification with respect to the other roadside communication apparatus 2J2, the case where it transmits via the central apparatus 4 was illustrated, For example, each roadside communication apparatus 2J1, 2J2, and 2J3 may transmit the transmission request notification directly by road-to-road communication.

  Moreover, in the said embodiment, although the control part 23 of each roadside communication apparatus 2J1, 2J2, 2J3 showed the structure which each has the determination part 23a, only the central apparatus 4 is provided with the determination part 23a, and each roadside communication apparatus 2J1, The information amount of the provided information D1 of 2J2 and 2J3 can be grasped, and it can be configured to control the transmission of road alignment information by each roadside communication device 2, and each roadside can be provided with the determination unit 23a. A management device that comprehensively manages functions related to a transmission request for road alignment information performed by the communication device 2 may be provided independently.

[Second Example]
FIG. 6 is a block diagram showing an internal configuration of the roadside communication device and the in-vehicle communication device according to the second embodiment of the present invention. The difference between this embodiment and the first embodiment is that the control unit 23 of the roadside communication device 2 further includes an information dividing unit 23c, and the control unit 32 of the in-vehicle communication device 3 includes the coupling unit 32c. Furthermore, it is a point.

When the determination unit 23a determines that the provided information D1 to be transmitted cannot be transmitted in one time slot Ta, the information dividing unit 23c of the roadside communication device 2 divides the road linear information that is the low-frequency update information. And has a function of obtaining a plurality of pieces of division information.
The combining unit 32c of the in-vehicle communication device 3 has a function of combining a plurality of pieces of division information obtained by the information dividing unit 23c to restore the original road linear information.

FIG. 7 is a schematic diagram showing an aspect of provision information stored in each time slot of each roadside communication device installed at each intersection in FIG. 2 in the present embodiment.
FIG. 7A shows an aspect of provision information stored in each time slot of the roadside communication device 2 when the traffic volume is normal at each intersection. As shown in the drawing, each time slot Ta stores high-frequency update information (broken line hatched portion in the figure) and low-frequency update information (solid line hatched portion in the figure).
Of these, the low frequency update information includes road alignment information, but in this embodiment, each roadside communication device 2 is configured to transmit road alignment information for the entire jurisdiction area. Accordingly, the roadside communication devices 2J1, 2J2, and 2J3 installed at the respective intersections J1, J2, and J3 transmit road alignment information D that is information indicating the same contents.

FIG. 7B shows a state where the information amount of the provided information D1 to be transmitted by the roadside communication device 2J1 exceeds the information amount that can be transmitted in one time slot Ta.
In FIG. 7B, compared with the case of FIG. 7A, since the high frequency update information has increased, there is not enough time for transmitting the road alignment information D that is the low frequency update information. Yes.
In this case, as in the first embodiment, the determination unit 23 of the roadside communication device 2J1 determines that the provided information D1 to be transmitted is not the amount of information that can be transmitted in one time slot Ta.
When the determination unit 23a determines that the provision information D1 to be transmitted cannot be transmitted in one time slot Ta, the information division unit 23c includes information that can be transmitted in the one time slot Ta among the low-frequency update information. The first division information d1 is generated by dividing the quantity portion. Here, the information dividing unit 23c divides the road alignment information D in units of packets.

The transmission control unit 23b of the roadside communication device 2J1 transmits the first division information d1 along with the high-frequency update information in its own time slot Ta.
In addition, the transmission control unit 23b of the roadside communication device 2J1 transmits a transmission request notification including address information for recognizing the first division information d1 in the road alignment information D and the remaining second division information d2. Is transmitted to the central device 4 via the wired communication unit 22.
The address information indicates the address of the packet of the portion into which the road alignment information D is divided, and the device that has received the address information later uses the first division information d1 and the second division information d2 based on this address information. Can be recognized.

When the central device 4 receives the transmission request notification, the central device 4 refers to the information amount of the current provision information D1 to be transmitted by the other roadside communication devices 2J2 and 2J3 in the jurisdiction area to which the roadside communication device 2J1 that has transmitted the transmission request notification belongs. To do.
Then, the central device 4 selects another roadside communication device 2 with the smallest amount of provision information D1 to be transmitted, and forwards a transmission request notification from the roadside communication device 2J1 to the roadside communication device 2. . In FIG. 7, the central device 4 transfers the transmission request notification including the address information to the roadside communication device 2J2 installed at the intersection J2 where the information amount of the provision information D1 to be transmitted is the smallest.

  Upon receiving the transmission request notification, the transmission control unit 23b of the roadside communication device 2J2 refers to the address information included in the notification and recognizes the second division information d2. Then, the roadside communication device 2J1 transmits the second division information d2, which is a part of the provision information D1 to be transmitted, using its own time slot Ta. Here, since the roadside communication device 2J2 also transmits the road alignment information D, the roadside communication device 2J2 can generate the second division information d2 by using the road alignment information D and the address information. it can.

As described above, the roadside communication device 2J1 transmits a transmission request notification to the central device 4 when it determines that the amount of the provision information D1 to be transmitted increases and cannot be transmitted for all the provision information D1. The second division information d2 which is a part of the provision information D1 to be transmitted by the roadside communication device 2J1 can be transmitted to the other roadside communication device 2J2 instead.
As a result, as in the first embodiment, communication resources can be utilized across the roadside communication devices 2, and communication resources can be effectively utilized as the entire communication system.

  In the above-described embodiment, the information dividing unit 23c divides the road linear information D into two pieces of information, that is, the first divided information d1 and the second divided information d2. The communication device 2 can also take over the transmission of the division information.

Next, the function of the in-vehicle communication device 3 that has received the first division information d1 and the second division information d2 will be described.
As shown in FIG. 6, the control part 32 of the vehicle-mounted communication apparatus 3 of this embodiment has the coupling | bond part 32c. The combining unit 32c combines the first division information d1 generated by dividing the road alignment information D by the information division unit 23c of the roadside communication device 2 and the second division information d2 as described above. , Has the function of restoring the original road alignment information D.

FIG. 8 is a schematic diagram showing the road linear information D divided in FIG. 7 and a mode for restoring it.
In the figure, road alignment information D of the present embodiment is composed of, for example, n packets. It is assumed that the information dividing unit 23c of the roadside communication device 2J1 generates and broadcasts the first division information d1 composed of m packets.

  In this case, the roadside communication device 2J2 includes, in addition to the road alignment information D to be transmitted by the roadside communication device 2J2, the roadside communication device 2J2 includes a second set of nm packets that are part of the provision information D1 to be transmitted by the roadside communication device 2J1. The division information d2 is broadcasted.

  The in-vehicle communication device 3 receives the first division information d1 composed of m packets from the roadside communication device 2J1, and then receives the second divided information composed of nm packets from the roadside communication device 2J2. The division information d2 is received.

When the coupling unit 32c of the in-vehicle communication device 3 receives the first division information d1 including the m packets, the coupling unit 32c recognizes that the first division information d1 is a part of the road alignment information D, and Is temporarily stored in the storage unit 33.
After that, when receiving the second division information d2 composed of nm packets, the combining unit 32c receives that the second division information d2 is a part of the road alignment information D and receives the first. It is recognized that the information corresponds to the first division information d1.
Next, the combining unit 32c combines the first division information d1 and the second division information d2 to restore the road alignment information D. And the vehicle-mounted communication apparatus 3 performs safe driving assistance control using the restored road alignment information D.

  Thus, according to the vehicle-mounted communication device 3 of the present embodiment, even if the first division information d1 and the second division information d2 in the road alignment information D are received from different roadside communication devices 2, Since the road alignment information D can be restored by the combining unit 32c, the road alignment information D as the low-frequency update information can be reliably acquired.

  The present invention is not limited to the above embodiments. In each of the above embodiments, the case where the road alignment information that is a part of the provision information D1 or the second division information d2 is transmitted to other roadside communication devices 2 other than the self is exemplified. Thus, in addition to the roadside communication device 2 capable of wireless communication with the in-vehicle communication device 3, the optical beacon 40 as a roadside communication device installed on the road and capable of infrared communication with the in-vehicle communication device 3 is used. Can also be sent. Similar to the roadside communication device 2, the optical beacon 40 forms a LAN with the central device 4 and can perform bidirectional communication.

As described above, as a roadside communication device, in addition to the roadside communication device 2 that performs wireless communication with the vehicle-mounted communication device 3, an optical beacon that communicates with the vehicle-mounted communication device 3 through optical communication that is a communication medium different from wireless communication. By providing 40, the part other than a part of the provision information D1 and the road alignment information that is a part of the provision information D1 or the second division information d2 can be transmitted using different communication media.
If one roadside communication device 2 causes the optical beacon 40 to transmit the road alignment information that is part of the provision information D1 or the second division information d2, the wireless communication resources of the other roadside communication devices 2 Consumption can be suppressed. In addition, when the vehicle 5 (the in-vehicle communication device 3) stops on the road due to traffic congestion or the moving speed is low, information transmission by the optical beacon 40 can be sufficiently performed to the in-vehicle communication device 3. As described above, the transmission method can be appropriately selected according to the characteristics of each communication medium.

  Moreover, in the said embodiment, although the provision information D1 was classified into high frequency update information and low frequency update information, the classification | category of the information which should be transmitted is not restricted to this. It can be classified according to other criteria such as importance of information and amount of information. For example, in the case where the high importance information is classified into the first information and the low importance information is classified into the second information in the provision information D1, there is not enough time for one roadside communication device to transmit the provision information D1. The first information may be transmitted from the one roadside communication device, and the second information may be transmitted from the other roadside communication device. When the information with a large amount of information is classified into the first information and the information with a small amount of information is classified as the second information in the provided information D1, there is not enough time to transmit the provided information D1 by one roadside communication device. The first information can be transmitted from the one roadside communication device, and the second information can be transmitted from another roadside transmitter.

  With respect to the present invention, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not meant to be described above, but is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

2 Roadside communication device 3 In-vehicle communication device (mobile communication device)
21 wireless transmission / reception unit 23 control unit 23a determination unit 23b transmission control unit 23c information division unit 31 communication unit 32 control unit 32c coupling unit

Provided information D1 as roadside information transmitted by the roadside communication device 2 includes information acquired by itself from other devices in addition to the information acquired by itself from the central device 4, and is equipped with the in-vehicle communication device 3. This is useful information for safe driving support control by the vehicle 5.
Specifically, the provision information D1 includes the signal control command, the signal display information, the traffic information, road linear information indicating the shape of the road, sensor information, and the like as described above.
The road alignment information is information indicating the road structure such as the length of the surrounding road , and is information such as the length of the road, the inclination, and the degree of the curve, for example. The road alignment information is information that can be stored in advance by the roadside communication device 2 or acquired from the central device 4.

With respect to the present invention, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not meant to be described above, but is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.
Regarding the above, the following additional notes are disclosed.
<Appendix>
(Appendix 1) Each of a plurality of roadside communication devices is used in a communication system that transmits roadside information to be transmitted to a mobile communication device on a road to the mobile communication device during a pre-assigned communication time zone. A communication control device,
A determination unit that determines whether or not the roadside information to be transmitted by one roadside communication device of the plurality of roadside communication devices is an amount of information that can be transmitted during the communication time period;
Depending on the determination result of the determination unit, the one roadside communication device is caused to transmit a part of the roadside information to be transmitted to another roadside communication device, and a part other than the part of the roadside information is transmitted to the one roadside A transmission control unit for transmitting to a communication device,
The roadside information includes first information and second information classified according to a predetermined criterion.
The first information is high-frequency update information with a high update frequency, and the second information is low-frequency update information with a lower update frequency than the first information,
The second information is information indicating the same content in each of the plurality of roadside communication devices,
According to the determination result of the determination unit, further comprising a dividing unit that uses the second information as a plurality of division information,
The transmission control unit is a communication control apparatus that causes a part or all of the plurality of pieces of division information to be transmitted to the other roadside communication device as a part of the roadside information.
(Supplementary Note 2) In a communication system including the communication control device according to Supplementary Note 1 and a plurality of roadside communication devices, the mobile communication device receives roadside information transmitted by each of the plurality of roadside communication devices,
A receiving unit that receives the plurality of pieces of division information transmitted from each of the plurality of roadside communication devices;
A mobile communication device comprising: a combining unit that combines the received plurality of pieces of division information and restores the second information.

Claims (9)

A communication control device used in a communication system in which each of a plurality of roadside communication devices transmits roadside information to be transmitted to a mobile communication device on a road to the mobile communication device during a communication time zone assigned in advance. There,
A determination unit that determines whether or not the roadside information to be transmitted by one roadside communication device of the plurality of roadside communication devices is an amount of information that can be transmitted during the communication time period;
Depending on the determination result of the determination unit, the one roadside communication device is caused to transmit a part of the roadside information to be transmitted to another roadside communication device, and a portion other than the part of the roadside information is transmitted to the one roadside communication device. And a transmission control unit that causes the communication device to transmit.   The communication control device according to claim 1, wherein the roadside information includes first information and second information classified according to a predetermined determination criterion.   The communication control device according to claim 2, wherein the first information is high-frequency update information with a high update frequency, and the second information is low-frequency update information with a lower update frequency than the first information. The second information is information indicating different contents in each of the plurality of roadside communication devices,
The communication control device according to claim 3, wherein the transmission control unit causes the second information to be transmitted to the other roadside communication device as a part of the roadside information. The second information is information indicating the same content in each of the plurality of roadside communication devices,
According to the determination result of the determination unit, further comprising a dividing unit that uses the second information as a plurality of division information,
The communication control device according to claim 3, wherein the transmission control unit causes the other roadside communication device to transmit a part or all of the plurality of pieces of division information as a part of the roadside information.   The at least some roadside communication devices among the plurality of roadside communication devices communicate with the mobile communication device using a communication medium different from roadside communication devices other than the some roadside communication devices. The communication control apparatus as described in any one of -5.   The roadside communication apparatus provided with the communication control apparatus as described in any one of Claims 1-6. A communication system comprising the communication control device according to claim 5 and a plurality of roadside communication devices, wherein the mobile communication device receives roadside information transmitted by each of the plurality of roadside communication devices,
A receiving unit that receives the plurality of pieces of division information transmitted from each of the plurality of roadside communication devices;
A mobile communication device comprising: a combining unit that combines the received plurality of pieces of division information and restores the second information. Each of the plurality of roadside communication devices is a communication system for transmitting roadside information to be transmitted to a mobile communication device on a road to the mobile communication device during a pre-assigned communication time zone,
A determination unit that determines whether one roadside communication device can transmit the roadside information during the communication time period;
A communication system, comprising: a transmission control unit that causes a part of the roadside information to be transmitted by the one roadside communication device to be transmitted to another roadside communication device according to a determination result of the determination unit.

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