JP5218242B2 - Roadside communication device, mobile communication device, and roadside communication system including these - Google Patents

Description

  The present invention relates to a roadside communication device, a mobile communication device, and a communication system including these.

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 addition, the combination of communication performed between communication subjects includes road-to-road communication performed by roadside communication devices, road-to-vehicle (or roadway) communication performed by the roadside communication device and the vehicle-mounted communication device, and vehicle-mounted communication device. Vehicle-to-vehicle communication performed by each other is included.

Japanese Patent No. 2806801

  Here, in general, when providing blind spot information such as right-straight / left-turn insertion, road-to-vehicle communication is superior to vehicle-to-vehicle communication in terms of restrictions on installation location and equipment capacity. Information can be provided. Therefore, road-to-vehicle communication should be given priority over vehicle-to-vehicle communication.

In order to prioritize road-to-vehicle communication, it is conceivable to allocate a time zone for roadside communication devices that can be transmitted only by roadside communication devices, and prohibit vehicle-to-vehicle communication within the time zone. In this case, the inter-vehicle communication is performed in a time zone other than the time zone for the roadside communication device.
In this case, the inter-vehicle communication is a CSMA method, in which each in-vehicle communication device performs carrier sense and confirms that the in-vehicle communication device of another vehicle is not communicating, and then transmits a radio signal. It is advantageous to do so. In other words, while the roadside communication device does not move, the in-vehicle communication device repeats entering and leaving the communication area of the roadside communication device while an unspecified number of people move, and thus communication between such in-vehicle communication devices. For inter-vehicle communication, the CSMA method is simple.

On the other hand, many vehicles concentrate near the intersection on the road, and there are vehicles that make a right / left turn, a sudden brake, etc., so the incidence of accidents increases. Therefore, in vehicle-to-vehicle communication, information (vehicle position information, speed information, etc.) transmitted from the vehicle-mounted communication device of the vehicle nearest to the intersection is often urgent or important, and conversely, it is far from the intersection. The information transmitted from the in-vehicle communication device of the vehicle is considered to be often less urgent or important than the information transmitted from the in-vehicle communication device nearest to the intersection.
However, when vehicle-to-vehicle communication is simply performed using the CSMA method, a radio signal transmission opportunity is given to any in-vehicle communication device in the communication area under the same conditions, and a certain in-vehicle communication device transmits a radio signal. Since the transmission of wireless signals by other in-vehicle communication devices is restricted during this period, the in-vehicle communication devices that are away from the intersection are transmitting wireless signals, so that the in-vehicle communication devices closest to the intersection are more urgent or important. There is a problem that there are not a few cases where information cannot be transmitted quickly.

  The present invention sets a predetermined priority condition in consideration of the urgency and importance of information for a mobile communication device that performs wireless communication, and transmits a radio signal by a mobile communication device that satisfies the priority condition to another It is an object of the present invention to provide a roadside communication device and a mobile communication device that realize appropriate radio communication according to road conditions by giving priority over a mobile communication device, and a road communication system including these.

(1) A roadside communication device according to a first aspect of the present invention includes a first time slot that prohibits transmission of a radio signal of a mobile communication device and allows transmission of a radio signal by the roadside communication device itself, and a predetermined time slot Time slot information for a second time slot including a priority time slot that allows transmission of a radio signal by the mobile communication device satisfying a priority condition is provided, and the time slot information is supplied to the mobile communication device in a communication area. It is characterized by including a transmission unit for transmission.

The roadside communication device of the present invention transmits time slot information about the first time slot and the second time slot including the priority time slot into the communication area. When the mobile communication device in the communication area acquires the time slot information, the mobile communication device is prohibited from transmitting a radio signal in the first time slot. Without interference.
In the second time slot, transmission of radio signals by mobile communication devices in the communication area is allowed. However, in the priority time slot of the second time slot, not all mobile communication devices but a predetermined priority condition is set. Only satisfying mobile communication devices are allowed to transmit radio signals. Therefore, for example, if the priority is that the mobile communication device is located in the immediate vicinity of the intersection, the transmission from the mobile communication device closest to the intersection is not limited by the mobile communication device that is far from the intersection in the priority time slot. Information with a high degree of urgency or importance can be quickly transmitted, and the information can be used for preventing an accident or the like immediately near an intersection.

(2) The roadside communication device may include an allocating unit that allocates the first and second time slots, and the time slot information may be supplied from the allocating unit to the transmitting unit.

(3) In the roadside communication device, the second time slot is composed of the priority time slot and a general time slot that allows transmission of radio signals by all mobile communication devices in the communication area. Is preferred. In this case, the mobile communication device that satisfies the priority condition can transmit a radio signal in both the priority time slot and the general time slot, and the other mobile communication devices can transmit the radio signal in the general time slot. Can be sent. Therefore, the time zone in which the mobile communication device satisfying the priority condition can transmit the radio signal is longer than the time zone in which the other mobile communication device can transmit the radio signal. A mobile communication device satisfying the condition can transmit more urgent or important information.

(4) In the above configuration, the priority condition may be that the mobile communication device is located in a predetermined priority area set in the communication area.
(5) In this case, the roadside communication device may further include a priority area notification unit for notifying the mobile communication device of priority area information indicating the priority area with the priority area as a transmission range.
According to this, a mobile communication device that has entered a priority area such as the nearest intersection intersects with the priority condition by acquiring the priority area information transmitted from the roadside communication device. I can recognize that.

(6) The roadside communicator instructs the mobile communicator or another mobile communicator to adjust communication conditions so that a radio signal transmission opportunity of the mobile communicator satisfying the priority condition is improved. It is preferable to further include a command notification unit that notifies information.
For example, in the above-described general time slot, transmission of radio signals by all mobile communication devices is allowed. However, if transmission opportunities for radio signals by all mobile communication devices are given under the same conditions, the priority condition is satisfied. Information with high urgency and the like transmitted from the mobile communication device is limited by transmission of radio signals by other mobile communication devices. For this reason, the roadside communication device notifies the mobile communication device or other mobile communication device of command information for adjusting the communication conditions so that the radio signal transmission opportunity of the mobile communication device satisfying the priority condition is improved. Thus, the mobile communication device that has acquired the command information adjusts the communication conditions so that the mobile communication device that satisfies the priority condition can transmit the wireless signal more preferentially even in the general time slot.

Note that the adjustment of the communication conditions for improving the transmission opportunity is performed by, for example, shortening the transmission cycle by the mobile communication device satisfying the priority condition or the backoff time in the CSMA method (actually after detecting no signal by carrier sense). (Time included in idle time until transmission starts) can be shortened. Or it is good also as extension of the transmission period of the mobile communication apparatus which does not satisfy | fill priority conditions, extension of the backoff time in a CSMA system, etc.
Further, the adjustment of the former communication condition may be performed only by the mobile communication device that satisfies the priority condition in the priority time slot.

(7) A mobile communication device according to a second aspect of the present invention is a mobile communication device that performs wireless communication in a communication area of a roadside communication device, and is configured to transmit radio signals from the mobile communication device that satisfies a predetermined priority condition. A time slot information acquisition unit that acquires time slot information including a priority time slot that allows transmission, a determination unit that determines whether or not the priority condition is satisfied, and the priority condition is satisfied by the determination unit A transmission unit that transmits a radio signal in the priority time slot when it is determined that the transmission is performed.

  The mobile communication device of the present invention determines whether or not the predetermined priority condition is satisfied by the determination unit, and determines that the time slot information acquisition unit acquires the time when the priority condition is satisfied. Radio signals are transmitted in the priority time slots included in the slot information. Therefore, in the priority time slot, transmission of radio signals by the mobile communication device that satisfies the priority condition is not restricted by other mobile communication devices that do not satisfy the priority condition. For example, the mobile communication device is located in the immediate vicinity of the intersection. Is the priority condition, the mobile communication device nearest to the intersection can transmit information of higher urgency or importance more preferentially than the mobile communication device away from the intersection. It can be used to prevent the latest accidents.

(8) In the mobile communication device having the above-described configuration, whether the determination unit satisfies the priority condition depending on whether the mobile communication device is located in a predetermined priority area set in the communication area. It can be determined whether or not. For example, whether the mobile communication device itself is located in the priority area is specified based on whether the reception level of the signal from the roadside communication device is equal to or higher than a predetermined threshold value.

(9) The determination unit may be configured to detect the current position of the mobile communication device itself and determine whether or not the mobile communication device is located within the priority area from the result. For example, the current position of the mobile communication device is specified based on the position information from the GPS, and it is determined whether or not the mobile communication device itself is located in the priority area. In addition, the current position of the mobile communication device itself is detected from the travel distance obtained by integrating the moving speed of the mobile communication device from a specific time, such as when an optical beacon passes, and distance information to the priority area at the specific time , It may be determined whether the mobile communication device itself is located in the priority area.

(10) Further, the determination unit indicates the priority area and determines whether or not the mobile communication device has acquired the priority area information transmitted from the roadside communication device using the priority area as a transmission range. It may be configured to determine whether or not it is located within. In this case, the mobile communication device can recognize that it is located in the priority area by acquiring the priority area information. In addition, it may be determined whether or not the mobile communication device is located in the priority area from the combinations of the determination results illustrated in (8) to (10).

(11) In the mobile communication device having the above-described configuration, a predetermined behavior in the present or future of a mobile body equipped with the mobile communication device may be set as the priority condition. Predetermined behavior in the present or future of a mobile unit equipped with a mobile communication device may cause contact with other mobile units depending on its mode. Can be achieved.

(12) Specifically, the predetermined behavior is preferably a behavior related to the speed of the moving object. For example, when a moving body such as a vehicle decelerates or stops in a short time by sudden braking, there is a high possibility that a moving body behind the vehicle will collide. In this case, if the rear moving body recognizes that the moving body has suddenly applied the brake (or is scheduled to be applied), the rear-end collision can be avoided. In addition, for example, when a moving body such as a vehicle suddenly accelerates at an intersection, there is a high possibility that another moving body trying to make a right turn in the opposite lane will collide. In this case, if another moving body recognizes that the moving body has accelerated (or is scheduled to accelerate), the collision can be avoided. Therefore, the predetermined behavior (deceleration, acceleration, etc.) relating to the speed of the moving object is set as a priority condition, and the speed information, position information, etc. of the moving object that satisfies the priority condition are transmitted preferentially, and the information is acquired. It is possible to prevent the occurrence of an accident or the like by alerting the moving body.

(13) The predetermined behavior may relate to a change in the moving direction of the moving body. For example, when a moving body such as a vehicle makes a right or left turn at an intersection or when changing lanes, other moving bodies on the opposite lane, other moving bodies behind the opposite lane, other moving bodies running in parallel, etc. There is a high possibility of contact between the two. Therefore, given a predetermined behavior regarding the change of the moving direction as a priority condition, priority is given to speed information, position information, etc. of a mobile object that satisfies this priority condition, that is, a mobile object that has made (or is scheduled to turn). By transmitting to, it is possible to call attention to other mobile units that have acquired the information and prevent an accident or the like from occurring.

(14) It is preferable that the mobile communication device further includes an adjustment unit that adjusts the communication condition so that a radio signal transmission opportunity of the mobile communication device that satisfies the priority condition is improved.

(15) Specifically, the adjustment of the communication condition performed by the adjustment unit may be adjustment of a radio signal transmission waiting time by the transmission unit. For example, if the transmission waiting time of the radio signal by the mobile communication device that satisfies the priority condition is shortened, the transmission opportunities of the mobile communication device can be increased. Conversely, if the transmission waiting time of radio signals by other mobile communication devices that do not satisfy the priority condition is extended, the transmission opportunities of mobile communication devices that satisfy the priority condition can be relatively increased. In order to adjust the transmission waiting time, it is convenient to adjust the backoff time in the CSMA method.

(16) A road communication system according to a third aspect of the present invention is a road communication system having a road communication device installed on a road and a mobile communication device mounted on a mobile body, the road communication device. A first time slot that permits transmission of a radio signal by the roadside communication device itself and prohibits transmission of the radio signal by the mobile communication device, and a radio signal by the mobile communication device that satisfies a predetermined priority condition A transmission unit that transmits time slot information about a second time slot including a priority time slot that permits transmission to the mobile communication device in a communication area, and the mobile communication device transmits the time slot information to the mobile communication device. An acquisition unit to acquire, a determination unit that determines whether or not the priority condition is satisfied, and the priority when the determination unit determines that the priority condition is satisfied Characterized in that it comprises a transmitting unit for transmitting a radio signal during the slot.

  According to the present invention, by setting a predetermined priority condition in consideration of the urgency and importance of information transmission for a mobile communication device, priority is given to transmission of a radio signal by a mobile communication device that satisfies the priority condition. In addition, appropriate wireless communication according to road conditions and the like can be realized.

1 is a schematic perspective view showing an overall configuration of an intelligent road traffic system according to a first embodiment of the present invention. It is a top view which shows a part of intelligent traffic system. It is a block diagram which shows the internal structure of a roadside communication apparatus and a vehicle-mounted communication apparatus. It is a time chart which shows the slot of road-to-vehicle communication and vehicle-to-vehicle communication. It is a top view which expands and shows a priority area. It is a flowchart explaining the communicability state of the vehicle-mounted communication apparatus according to advancing of the vehicle which passes a communication area. It is a block diagram which shows the internal structure of the roadside communication apparatus and in-vehicle communication apparatus of the intelligent transport system which concerns on the 2nd Embodiment of this invention. It is the schematic explaining the determination method of the priority area in 2nd Embodiment. It is a block diagram which shows the internal structure of the roadside communication apparatus and vehicle-mounted communication apparatus of an intelligent road traffic system which concern on the 3rd Embodiment of this invention.

[First Embodiment]
[Overall system configuration]
FIG. 1 is a schematic perspective view showing an overall configuration of an intelligent road traffic system (ITS) according to a first embodiment of the present invention.
As shown in FIG. 1, the intelligent traffic system includes a traffic signal 1, a roadside communication device 2, an in-vehicle communication device 3 (see FIGS. 2 and 3), a central device 4, and an in-vehicle communication device (mobile communication device) 3. Including vehicles 5 and the like.

Each traffic signal 1 is installed at each of a plurality of intersections Ci (i = 1 to 12 in the figure), and is connected to a router 8 via a 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 LAN (Local Area Network) with the traffic signal device 1 and the roadside communication device 2 of each intersection Ci 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.

  In FIG. 1 to FIG. 3, for simplification of illustration, only one signal lamp is depicted at each intersection Ci, but at each actual intersection Ci, at least 4 for ascending and descending roads intersecting each other. There are two signal lights.

[Wireless communication systems, etc.]
FIG. 2 is a road plan view showing a part of the monitoring area of the intelligent road traffic system.
In FIG. 2, each of two roads intersecting each other is illustrated as one lane on one side in the up and down directions, but the road structure is not limited to this.
As shown also in FIG. 2, the traffic system of this embodiment includes a plurality of roadside communication devices 2 capable of wireless communication with the in-vehicle communication device 3, and other communication devices using a carrier sense method (CSMA / CA). 2 and 3 and an in-vehicle communication device 3 that is a kind of mobile wireless transceiver that performs wireless communication.

The plurality of roadside communication devices 2 are installed at each intersection on the roadside, and are attached to the pillars of the traffic signal device 1 in the examples of FIGS. 1 and 2. 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 communication area A1 within a predetermined range extending around the roadside communication device 2, and can communicate with the in-vehicle communication device 3 of each vehicle 5 traveling in the communication area A1. The communication area A1 is an area where the roadside communication device 2 is transmitting radio waves, and the in-vehicle communication device 3 is an area where the radio waves can be received.
Note that the communication area A1 of the roadside communication device 2 does not exist at an intersection in the suburbs where the roadside communication device 2 is not installed.

  In the traffic system (communication system) of the present embodiment, wireless communication is used between the roadside communication devices 2 (communication between roadways), and between the roadside communication device 2 and the in-vehicle communication device 3 (from the “road”). Wireless communication is also used for both the vehicle-to-vehicle communication to “car” and the vehicle-to-vehicle communication from “car” to “road”. . The same communication band is used for these communications.

In the communication system of this embodiment, since the transmission of the roadside communication device 2 is prioritized over the transmission of the in-vehicle communication device 3, a time (slot) for the roadside communication device 2 to transmit is secured. A time division multiplexing (TDMA) system is used for slot allocation to a plurality of roadside communication devices 2 within this time.
During the time other than the time for the roadside communication device 2 to communicate, the in-vehicle communication device 3 is used for inter-vehicle communication by the CSMA method. That is, the in-vehicle communication device 3 performs wireless communication with another in-vehicle communication device 3 around the roadside communication device 2 by the carrier sense method.
Each roadside communication device 2 has a time synchronization function with other roadside communication devices 2 in order to control its own transmission timing.

In addition, the above description presupposes the downtown area where there are many intersections and many roadside communication devices 2 are installed. In the city center, in addition to vehicle-to-vehicle communication, road-to-vehicle communication and road-to-road communication are performed, and since the number of vehicles 5 is large, the limited communication band is in a tight situation, and the communication system of this embodiment is It becomes more useful.
On the other hand, in the suburbs where there are few intersections where signals are installed and roadside communication devices 2 are not installed or set, there is no communication area A1 of the roadside communication device 2, and only vehicle-to-vehicle communication is performed. Is called. In the suburbs, road-to-vehicle communication and road-to-road communication are hardly performed, and the number of vehicles 5 is small, so that the communication band has a margin as compared to the city center. However, even if the communication band has a relatively large area, it does not prevent the introduction of the communication system of the present embodiment.

[Configuration of roadside communication device]
FIG. 3 is a block diagram showing internal configurations of the roadside communication device 2 and the in-vehicle communication device 3.
The roadside communication device 2 includes a wireless transmission / reception unit (wireless communication unit) 21 connected to an antenna 20 for wireless communication, a wired transmission / reception unit (wired communication unit) 22 that performs bidirectional communication with the central device 4, and these communications A control unit 23 including a processor (CPU: Central Processing Unit) that performs control and a storage unit 24 including a storage device such as a ROM and a RAM connected to the control unit 23 are provided.
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.

The control unit 23 of the roadside communication device 2 causes the wireless communication unit 22 to perform wireless communication between roads and roads and between roads by a time division multiplexing method. For this reason, the control unit 23 performs the first time slot T1 (see FIG. 4) that the roadside communication device 2 itself wirelessly transmits and the wireless transmission of the in-vehicle communication device 3 as functional units achieved by executing the computer program. An allocation unit 23a that allocates the allowed second time slot T2 in a time-sharing manner for each predetermined period is provided.
Note that the assignment of the first time slot T1 and the second time slot T2 need not be determined periodically. Further, the allocation of the first time slot T1 and the second time slot T2 may be an allocation determined mainly by the roadside communication device 2 or a device (such as a central control device) that controls the roadside communication device 2. Therefore, the allocation unit may be provided in a device other than the roadside communication device 2, for example, the central device 4.

FIG. 4 is a time chart showing the first time slot T1 and the second time slot T2. In principle, the first time slot T1 is a period in which only the roadside communication device 2 has the authority to transmit a radio signal, and transmission of the radio signal (vehicle-to-vehicle communication) by the in-vehicle communication device 3 is prohibited. In the first time slot T1, road-to-vehicle communication is mainly performed, but road-to-road communication may be performed.
Each first time slot T1 may be used by only one roadside communication device 2 or may be shared by a plurality of roadside communication devices 2 by time division. Further, the number of roadside slots corresponding to the first time slot T1 is not limited to one in one cycle, and there may be a plurality of slots.

  The second time slot T2 refers to a time other than the first time slot T1, and in this time zone, a plurality of in-vehicle communication devices 3 acquire transmission opportunities by the CSMA / CA method, and the inter-vehicle communication and the inter-road communication are performed. I do. The second time slot T2 includes a priority time slot T21 and a general time slot T22. As described later, the priority time slot T21 is a period in which only the in-vehicle communication device 3 of the vehicle 5 that satisfies a predetermined priority condition is allowed to transmit a radio signal, and the general time slot T22 is in-vehicle communication of all the vehicles 5. This is a period during which the machine 3 is allowed to transmit radio signals.

  In the second time slot T2, the roadside communication device 2 may perform communication (such as road-to-vehicle communication) by the CSMA / CA method. Furthermore, the roadside communication device 2 may have a function of securing a transmission period in a system that presupposes the CSMA / CA scheme, such as HCCA in IEEE 802.11e.

  The allocating unit 23a prohibits inter-vehicle communication in the first time slot T1 and allows inter-vehicle communication in the second time slot T2, so that the in-vehicle communication device 3 is used for the roadside communication device 2 and the in-vehicle communication device. The time slot information indicating the time zone allocated for 3 is supplied to the wireless transmission / reception unit 21. This time slot information is transmitted (broadcast transmission) to the in-vehicle communication device 3 by the wireless transmission / reception unit 21.

The control unit 23 of the roadside communication device 2 further includes a signal information acquisition unit 23b, a traffic jam information acquisition unit 23c, and a surrounding information generation unit 23d.
The signal information acquisition unit 23b acquires signal information related to the current state and future display (light color) of the traffic signal device 1 corresponding to the roadside communication device 2 from the traffic signal device 1 or the central device 4 via the wired transmission / reception unit 22. . Specifically, the signal information includes the currently displayed lamp color information and the scheduled duration in terms of the current color of the lamp, and the scheduled duration in other lamp colors that are displayed after the current status. And the number of seconds for which each lamp color is to be continued is included for several cycles when one cycle is a change from red to blue to yellow.

  The traffic jam information acquisition unit 23 c acquires traffic information such as traffic jam information given from the central device 4 via the wired transmission / reception unit 22. In addition, the traffic jam information acquisition unit 23c relates to whether or not the vehicle 5 exists in the lane detected by the vehicle detector located upstream of the lane where the traffic signal 1 corresponding to the roadside communication device 2 is installed. Information is acquired from the central apparatus 4 via the wired transmission / reception unit 22. The traffic jam information acquisition unit 23c generates traffic jam information on the upstream side of the traffic signal 1 based on the traffic information and information from the vehicle detector.

The surrounding information generation unit 23d generates surrounding information indicating the surrounding situation of each vehicle 5 located in its own communication area A1 from the signal information and the congestion information acquired by the signal information acquisition unit 23b and the congestion information acquisition unit 23c, respectively. . That is, the signal information acquisition unit 23b and the traffic jam information acquisition unit 23c constitute a grasping unit that grasps the traffic jam information and signal information as the surrounding situation of the vehicle 5, and the surrounding information generation unit 23d displays the grasping surrounding situation. Peripheral information generation means for generating the peripheral information shown is configured.
The control unit 23 broadcasts the peripheral information generated by the peripheral information generation unit 23d to each vehicle 5 located in its own communication area A1 via the wireless transmission / reception unit 21. At this time, the time slot information described above may be broadcasted together with the traffic information.

  The control unit 23 of the roadside communication device 2 further includes a command notification unit 23b. This command notification unit 23b notifies the command for causing the in-vehicle communication device 3 to adjust the communication conditions so that the transmission opportunity of the radio signal by the in-vehicle communication device 3 that satisfies a predetermined priority condition described later is improved. . The in-vehicle communication device 3 that has acquired this notification adjusts the communication conditions in the adjustment unit 32d.

[Configuration of in-vehicle communication device]
The in-vehicle communication device 3 includes a transmission / reception unit (wireless communication unit) 31 connected to an antenna 30 for wireless communication, a control unit 32 including a processor that performs communication control on the transmission / reception unit 31, and the control unit 32. And a storage unit 33 including a storage device such as a ROM or a RAM connected thereto.
The transmitter / receiver 31 can be configured to be normally used for wireless communication, and functions as a transmitter (transmitter) and a receiver (receiver) of radio signals. Equipment, amplifier, etc.
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 has a function as a carrier sense control unit 32a that causes the transmission / reception unit 31 to perform wireless communication by a carrier sense method (CSMA / CA method) for inter-vehicle communication. The carrier sense control unit 32a detects whether a radio signal having a predetermined carrier frequency exists in the radio signal propagation path. If the radio signal does not exist, the carrier sense control unit 32a acquires a transmission opportunity after the back-off time has elapsed, The transmission / reception unit 31 is controlled to be performed.
When determining whether or not a radio signal having a predetermined carrier frequency exists in the radio signal propagation path, if the reception level received by the transmission / reception unit 31 is equal to or higher than a predetermined threshold (carrier sense level) It is determined that there is a radio signal having a predetermined carrier frequency, and if it is less than the threshold (carrier sense level), it is determined that there is no radio signal having a predetermined carrier frequency.

  The control unit 32 of the in-vehicle communication device 3 wirelessly transmits the current position information and speed information of the vehicle 5 from the transmission / reception unit 31 to the outside. For this reason, in the other vehicle 5 or the roadside communication device 2 that has received the position information, the speed information, and the like, for example, safe driving support control for avoiding a right-handed collision or a head-on collision can be performed. The current position information can be acquired from, for example, the GPS 43 mounted on the vehicle 5, and the speed information can be acquired from the vehicle speed sensor 41 of the vehicle 5.

The control unit 32 includes a time slot information acquisition unit 32b that performs a process of acquiring time slot information transmitted from the roadside communication device 2 or another in-vehicle communication device 3 as the function unit. When the time slot information acquisition unit 32 b acquires time slot information, the time slot information is stored in the storage unit 33.
The control unit 32 also has a function of performing processing for transferring (wireless transmission) time slot information acquired from the roadside communication device 2 or other vehicle-mounted communication device 3 to the other vehicle-mounted communication device 3. ing. Thus, by transferring the time slot information to the other in-vehicle communication device 3, the position where the time slot information cannot be directly acquired from the road side communication device 2 (for example, the outer edge of the communication area A1 of the road side communication device 2). The time slot information can be acquired even in the in-vehicle communication device 3 in the vicinity or a narrow street in the communication area A1).

  In a state where the time slot information is acquired, the control unit 32 prohibits transmission of a radio signal in the first time slot T1 included in the time slot information. That is, in the first time slot T1, the transmission of the wireless signal by the in-vehicle communication device 3 is limited so that a transmission opportunity is not obtained even if the wireless signal does not exist in the propagation path. As a result, in the first time slot T1 allocated for the roadside communication device 2, vehicle-to-vehicle communication does not occur, and interference with road-to-vehicle communication is prevented.

However, in a state where the in-vehicle communication device 3 has not acquired the time slot information (including the case where the acquired time slot information is invalidated), transmission is not prohibited for the roadside communication device 2, and the in-vehicle communication device 3 The time zone in which the communication device 3 can acquire the transmission opportunity is all the time zones. Therefore, in the suburbs where the roadside communication device 2 does not exist, there is no time zone in which transmission is prohibited, and vehicle-to-vehicle communication can be performed efficiently.
The time slot information does not necessarily need to be acquired from the roadside communication device 2 or the vehicle-mounted communication device 3, for example, acquired by the optical beacon 40 or the like installed in the vicinity of the communication area A1 before entering the communication area A1. May be.

  The control unit 32 of the in-vehicle communication device 3 includes a determination unit 32c, an adjustment unit 32d, a distance information acquisition unit 32e, and a vehicle speed information acquisition unit 32f as functional units executed by the computer program stored in the storage unit 33. It has.

  The determination unit 32c determines whether the in-vehicle communication device 3 satisfies a predetermined priority condition. The predetermined priority condition is a condition for acquiring the right to transmit a radio signal in the priority time slot T21 among the second time slots T2 included in the time slot information transmitted from the roadside communication device 2. . If this right cannot be acquired by the in-vehicle communication device 3, the in-vehicle communication device 3 cannot transmit a radio signal in the priority time slot T21. In the present embodiment, the priority condition is that the vehicle 5 is located in a priority area (intersection closest area) A2 (see FIG. 2) set in the immediate vicinity of the intersection in the communication area A1. For example, as shown in FIG. 5, the priority area A2 can be set in a range surrounded by a boundary line that is separated from the intersection by a distance indicated by L2. The distance L2 can be appropriately set according to the width of the road (the number of lanes), the traffic volume, etc., and can be set to 30 m to 70 m, for example. The distance L2 may be variable according to the time zone, day of the week, or the like.

  The distance information acquisition part 32e acquires the distance information regarding the distance L1 to the intersection transmitted from the optical beacon 40 installed on the road. Further, the vehicle speed information acquisition unit 32 f acquires the traveling speed of the own vehicle 5 from the vehicle speed sensor 41. In addition, information indicating the distance L2 from the intersection to the priority area A2 is recorded in the storage unit 33 in advance. The determination unit 32c calculates, for example, the distance to the priority area A2 when the optical beacon 40 passes, and sequentially integrates the traveling speed acquired by the vehicle speed sensor 41 after that time to calculate the distance traveled after that time. To do. Then, the distance to the priority area A2 at that time is compared with the calculated travel distance, and based on the result, it is determined whether the in-vehicle communication device 3 is located in the priority area A2. That is, if the vehicle speed sensor 41 always observes the moving speed after a specific time point such as when passing through the optical beacon 40, the vehicle enters the priority area A2 when the travel distance after the specific time exceeds the distance to the priority area A2. Thus, it can be determined that the in-vehicle communication device 3 is located in the priority area A2.

  The distance L2 from the intersection to the outer edge of the priority area A2 is not necessarily stored in the storage unit 33 in advance, and may be acquired from the outside of the roadside communication device 2 or the like. The distance L1 from the in-vehicle communication device 3 to the intersection may be acquired from the GPS 43 or the like. Whether or not the in-vehicle communication device 3 is located in the priority area A2 can also be determined based on whether or not the current position obtained from the GPS 43 is in the priority area A2.

  In urban areas, many vehicles 5 are concentrated at the intersections of roads, and there are vehicles 5 that turn right and left as well as vehicles 5 that go straight. Therefore, there is a high possibility that the vehicles 5 will cause a contact accident at the intersection. Therefore, the position information, vehicle speed information, etc. transmitted from the in-vehicle communication device 3 of the vehicle 5 located in the priority area A2 closest to the intersection are highly important information in order to prevent contact accidents etc. Yes, it is highly urgent information.

  On the other hand, in the communication by the CSMA method, while a certain in-vehicle communication device 3 is transmitting a radio signal, transmission of the radio signal by another in-vehicle communication device 3 is restricted. Therefore, the in-vehicle communication device outside the priority area A2 3 and the in-vehicle communication device 3 in the priority area A2 are allowed to transmit radio signals under the same conditions, the in-vehicle communication device 3 in the priority area A2 quickly transmits information of urgency or importance. There is a case where information cannot be transmitted and information transmission is delayed.

  In this respect, in the present embodiment, the second time slot T2 in which the transmission of the radio signal by the in-vehicle communication device 3 is allowed is divided into the priority time slot T21 and the general time slot T22, and in the priority time slot T21, Only the transmission of radio signals by the in-vehicle communication device 3 in the priority area A2 is allowed, and the transmission of radio signals by the in-vehicle communication device 3 outside the priority area A2 is prohibited. Therefore, in the priority time slot T21, the transmission of the radio signal by the in-vehicle communication device 3 in the priority area A2 is not limited to the transmission by the in-vehicle communication device 3 outside the priority area A2, and in the priority area A2. It is possible to quickly transmit urgent or important information from the in-vehicle communication device 3.

  Further, since the in-vehicle communication device 3 in the priority area A2 is allowed to transmit a radio signal not only in the priority time slot T21 but also in the general time slot T22, compared with the in-vehicle communication device 3 outside the priority area A2, Wireless signals can be transmitted in a longer time zone.

  FIG. 6 is a flowchart for explaining the communication availability state of the in-vehicle communication device 3 according to the progress of the vehicle 5 passing through the communication area A1. First, the in-vehicle communication device 3 can transmit a radio signal by the CSMA method without being limited to the roadside communication device 2 until the vehicle 5 enters the communication area A1 between road vehicles. When the vehicle 5 enters the road-to-vehicle communication area A1 (S1), the in-vehicle communication device 3 receives time slot information from the roadside communication device 2 (S2). The in-vehicle communication device 3 that has received the time slot information is prohibited from transmitting radio signals in the first time slot T1 and the priority time slot T21 of the second time slot T2, and is allowed to transmit radio signals in the general time slot T22. Is done.

  When the vehicle 5 enters the priority area A2 closest to the intersection (S3), transmission of radio signals in the first time slot T1 is prohibited, but transmission of radio signals in the second time slot T2 is allowed. That is, the in-vehicle communication device 3 in the priority area A2 can acquire the transmission opportunity of the radio signal at all times other than the time when the roadside communication device 2 transmits the radio signal.

  Further, when the vehicle 5 travels and exits from the priority area A2, the transmission of radio signals in the first time slot T1 and the priority time slot T21 of the second time slot T2 is prohibited again, and the radio in the general time slot T22 is prohibited. Signal transmission is allowed. When the vehicle 5 leaves the communication area A1, transmission of a radio signal by the CSMA method is permitted without being restricted to communication by the roadside communication device 2 again.

The adjustment unit 32d adjusts communication conditions so that transmission opportunities by the in-vehicle communication device 3 located in the priority area A2 are improved.
In the general time slot T22 in the second time slot T2, transmission of radio signals is permitted regardless of whether the in-vehicle communication device 3 is located in the priority area A2. Therefore, the transmission of the radio signal by the in-vehicle communication device 3 in the priority area A2 is restricted by the transmission of the radio signal by the in-vehicle communication device 3 outside the priority area A2, and information with high urgency is quickly transmitted from the in-vehicle communication device 3 May not be sent to. Therefore, in the present embodiment, adjustment is performed in the adjustment unit 32d in order to preferentially transmit the radio signal by the in-vehicle communication device 3 located in the priority area A2 even in the general time slot.

The adjustment unit 32d of the present embodiment adjusts a transmission waiting time in the CSMA method as a communication condition.
The transmission waiting time is a state in which the in-vehicle communication device 3 decides to transmit a radio signal and does not receive a radio signal from another radio device that is required from the start of carrier sensing to the actual start of transmission ( This is the time during which the (idle state) is continuously maintained.

  In wireless communication using the carrier sense method (CSMA / CA method), after the in-vehicle communication device 3 determines transmission of a wireless signal, carrier sensing is performed, and an idle state in which no wireless signal is received from another wireless device is a predetermined time. (Transmission waiting time) When continuously maintained, transmission of a radio signal is started. If a wireless signal is received from another wireless device during the transmission waiting time, transmission of the wireless signal is given up and the same operation is repeated again.

  The transmission waiting time is a time obtained by adding a DIFS time (Distributed Coordination Function Interframe Space) and a back-off time. The back-off time is a time set by generating a random number between 0 and the CW value (Contention Window size) and multiplying the random number by a predetermined time (for example, unit slot time). Set every time you do it. The adjustment unit 32d of the present embodiment adjusts the back-off time by adjusting the CW value, thereby adjusting the transmission waiting time. The back-off time increases as the CW value increases, and decreases as the CW value decreases.

  When the back-off time is shortened, the transmission waiting time is shortened, so that transmission opportunities are increased. Therefore, if the back-off time of the in-vehicle communication device 3 located in the priority area A2 is shortened by the adjustment unit 32d, the transmission opportunities of the in-vehicle communication device 3 can be increased. Therefore, in the general time slot, transmission of all the in-vehicle communication devices 3 is allowed, but among them, the transmission opportunities of the in-vehicle communication devices 3 in the priority area A2 increase, so that the in-vehicle communication devices 3 outside the priority area A2 Transmission is less restricted.

On the contrary, the adjustment unit 32d increases the CW value in the in-vehicle communication device 3 outside the priority area A2 and increases the back-off time, thereby reducing the radio signal transmission opportunity by the in-vehicle communication device 3 outside the priority area A2. However, the radio signal transmission opportunities by the in-vehicle communication device 3 in the priority area A2 may be relatively increased.
Note that the adjustment unit 32d may perform adjustment so as to increase the radio signal transmission opportunities by the in-vehicle communication device 3 in the priority area A2 not only in the general time slot T22 but also in the priority time slot T21.

  The adjustment unit 32d is not limited to adjusting the transmission waiting time, and may adjust the carrier sense level of the in-vehicle communication device 3. When the carrier sense level of the in-vehicle communication device 3 is lowered, the carrier sense sensitivity is increased, and the in-vehicle communication device 3 can detect the presence of a relatively low level radio signal with a high probability. Therefore, the vehicle-mounted communication device 3 with high carrier sense sensitivity has a lower probability of acquiring a transmission opportunity than when the carrier sense sensitivity is low. Conversely, when the carrier sense level of the in-vehicle communication device 3 is increased, the carrier sense sensitivity is lowered, and the in-vehicle communication device 3 is less likely to detect the presence of a relatively high level radio signal. Therefore, by increasing the carrier sense level of the in-vehicle communication device 3 in the priority area A2, the radio signal transmission opportunities can be increased, and conversely, the carrier sense level in the in-vehicle communication device 3 outside the priority area A2 is decreased. Thus, it is possible to reduce radio signal transmission opportunities and relatively increase radio signal transmission opportunities by the in-vehicle communication device 3 in the priority area A2.

  The adjustment unit 32d is not limited to adjusting the transmission waiting time and adjusting the carrier sense level, and may adjust the transmission power of the in-vehicle communication device 3. If the transmission power of the in-vehicle communication device 3 in the priority area A2 is adjusted so as to increase, the transmittable range of the wireless signal is expanded, so that the wireless signal is a carrier of the other in-vehicle communication device 3 outside the priority area A2. The probability of being detected by sense increases. Therefore, the transmission opportunities in the in-vehicle communication device 3 outside the priority area A2 are reduced, and the transmission opportunities of the in-vehicle communication device 3 in the priority area A2 are relatively increased. Further, when the transmission power of the in-vehicle communication device 3 outside the priority area A2 is adjusted to be small, the transmittable range of the wireless signal is reduced, so that the wireless signal is transmitted to the other in-vehicle communication device 3 in the priority area A2. The probability of being detected by carrier sense becomes low. Therefore, the transmission opportunities of the in-vehicle communication device 3 in the priority area A2 can be increased.

  In the present embodiment described above, the in-vehicle communication device 3 in the priority area A2 has a longer time zone in which a radio signal can be transmitted than the in-vehicle communication device 3 outside the priority area A2, and therefore priority is given. Due to the transmission of the radio signal by the in-vehicle communication device 3 outside the area A2, the transmission of the radio signal of the in-vehicle communication device 3 in the priority area A2 is limited. Therefore, information with high urgency or importance can be quickly transmitted from the in-vehicle communication device 3, and the information can be used for preventing traffic accidents.

[Second Embodiment]
FIG. 7 is a block diagram illustrating the internal configuration of the roadside communication device 2 and the in-vehicle communication device 3 according to the second embodiment, and FIG. 8 is a schematic diagram illustrating a determination method for the priority area A2. This embodiment is different from the first embodiment in a method for determining that the in-vehicle communication device 3 of the vehicle 5 is located in the priority area A2.
Specifically, as shown in FIG. 7, the control unit 23 of the roadside communication device 2 includes a priority area information notification unit 23f as a functional unit achieved by executing the computer program. The priority area information notification unit 23f transmits priority area information indicating the priority area A2 in the communication area A1 via the wireless transmission / reception unit 21, and only the in-vehicle communication device 3 in the priority area A2 receives priority area information. It is configured to be able to receive.

  That is, the priority area information notification unit 23f is configured to transmit the priority area information using the priority area A2 as a transmission range, and substantially only the in-vehicle communication device 3 in the priority area A2 can acquire the priority area information. Since the priority area A2 is smaller than the communication area A1, the roadside communication device 2 transmits the priority area information with a transmission power that is smaller than the transmission power of the radio signal when performing normal road-to-vehicle communication and road-to-road communication. To do.

  On the other hand, the control part 32 of the vehicle-mounted communication apparatus 3 is provided with the priority area information acquisition part 32g for acquiring priority area information as the function part. As shown in FIG. 8, the in-vehicle communication device 3 is in a state (indicated by reference numerals 3C and 3B) located outside the communication area A1 and outside the priority area (intersection immediately adjacent to the intersection) A2 by the priority area information notification unit 23f. It is outside the transmission range of the priority area information and cannot receive the priority area information. When the priority area information is not received, the determination unit 32c of the in-vehicle communication device 3 determines that the in-vehicle communication device 3 is not located in the priority area A2.

  When the in-vehicle communication device 3 enters the priority area A2 (indicated by reference numeral 3A), the priority area information transmitted from the roadside communication device 2 is received by the in-vehicle communication device 3, and the priority area information acquisition unit 32g receives the priority area information. Is acquired. When the priority area information is acquired by the priority area information acquisition unit 32g, the determination unit 32c determines that the in-vehicle communication device 3 has entered the priority area A2.

  In the present embodiment, the fact that the in-vehicle communication device 3 has acquired the priority area information notified by the priority area information notification unit 23f of the roadside communication device 2 is used as a determination criterion for being located in the priority area A2. Since there is no need to acquire the distance from the position of the in-vehicle communication device 3 itself to the priority area A2 as in the first embodiment, the processing load on the control unit 32 can be reduced.

[Third Embodiment]
FIG. 9 is a block diagram illustrating an internal configuration of the roadside communication device 2 and the in-vehicle communication device 3 according to the third embodiment. In the first and second embodiments described above, the priority condition for preferentially transmitting a radio signal is that the in-vehicle communication device 3 is located in the priority area A2 closest to the intersection. However, in this embodiment, regardless of the inside or outside of the priority area A2, it is predicted that the vehicle 5 equipped with the in-vehicle communication device 3 is currently performing a predetermined behavior and that it will be predicted to perform a predetermined behavior in the future. It is a priority condition. Therefore, the control part 32 of the vehicle-mounted communication apparatus 3 of this embodiment is provided with the behavior detection part 32h which detects the present behavior as the function part, and the behavior prediction part 32i which estimates a future behavior.

  The behavior detection unit 32h detects the current behavior of the vehicle 5 on which the behavior detection unit 32h is mounted, and outputs the current behavior information as a result to the determination unit 32c. The behavior detection unit 32 h detects the vehicle speed (including acceleration / deceleration), the position, and the traveling direction of the vehicle 5 as the current behavior of the vehicle 5. These current behaviors can be detected using various sensors such as the vehicle speed sensor 41 of the vehicle 5, the GPS 43 and the gyro sensor 44 mounted on the vehicle 5.

  The behavior prediction unit 32i predicts the future behavior of the vehicle 5 on which the behavior prediction unit 32i is mounted, and outputs the future behavior information as a result to the determination unit 32c. The behavior predicting unit 32 i predicts the future behavior of the vehicle 5 based on the above-described peripheral information transmitted by the roadside communication device 2 and the direction information regarding the future traveling direction of the vehicle 5. The direction information is information indicating whether the right or left turn signal of the current vehicle 5 is blinking, and can be acquired from the turn signal relay 45 of the vehicle 5, for example. In addition to the above-described peripheral information and the like, the behavior prediction unit 32i includes information related to the detection result of the vehicle sensor 42 that detects whether or not the vehicle 5 is present around the vehicle 5 and the detection unit 32c. Future behavior can be predicted by adding current behavior information.

  The determination unit 32c causes the behavior detection unit 32h or the behavior prediction unit 32i to perform a behavior such as sudden braking, rapid acceleration, entry into a dilemma zone, traveling from a stopped state, turning left / right, changing lanes, high-speed traveling, and the like. When it is detected, or when it is predicted that these behaviors are performed, it is determined that the priority condition is satisfied. Hereinafter, each of these behaviors will be described.

  If there is a vehicle 5 that is suddenly braked in the vicinity of the intersection or on a road that is far from the intersection, there is a high possibility that the vehicle 5 traveling behind the vehicle will collide. Therefore, the determination unit 32c of the in-vehicle communication device 3 mounted on the vehicle 5 that has suddenly applied the brake determines that its own vehicle 5 satisfies the priority condition, and the position information and vehicle speed information are preferentially transmitted by the transmission / reception unit 31. Etc. are transmitted. As a result, it is possible to quickly inform the surrounding vehicle 5 (especially the vehicle behind it) that there is a vehicle 5 that has suddenly braked, and to prevent contact between the vehicles. .

  Similarly, when there is a vehicle 5 that is predicted to be suddenly braked in the future, there is a possibility that the vehicle 5 behind it may collide, so that the vehicle 5 that is predicted to be suddenly braked is mounted. The determination unit 32c of the in-vehicle communication device 3 thus determined determines that its own vehicle 5 satisfies the priority condition, and causes the transmission / reception unit 31 to transmit position information, vehicle speed information, and the like preferentially, so that the surrounding vehicle 5 (In particular, the rear vehicle) is quickly notified that the vehicle 5 that has suddenly braked exists in the vicinity.

  As the vehicle 5 predicted to be suddenly braked in the future, for example, the position information and the vehicle 5 located behind the vehicle 5 that is currently suddenly braked, that is, the vehicle 5 ahead of the sudden brake, Examples include the rear vehicle 5 that has received speed information and the like, and the vehicle 5 that is traveling toward a traffic jam. In the latter case, the behavior predicting unit 32i can recognize the traffic jam ahead and predict the occurrence of sudden braking based on the traffic jam information included in the peripheral information transmitted from the roadside communication device 3.

  Further, the vehicle 5 predicted to be suddenly braked may include a vehicle 5 that has entered a dilemma zone near an intersection or a vehicle 5 that is predicted to enter a dilemma zone in the future. The dilemma zone is, for example, as indicated by reference numeral Z in FIG. 5, before the vehicle 5 enters the intersection, the front traffic light changes from blue to yellow, so that it can safely stop at the stop line at a normal deceleration. This is a temporal and spatial area where the traffic light cannot pass through the intersection before the traffic light turns red, and is an area where the driver may be worried about whether to stop the vehicle 5 or not. Therefore, when the vehicle 5 enters the dilemma zone Z, the driver may brake suddenly based on his / her own judgment. Therefore, when the vehicle 5 has entered the dilemma zone Z and when it is predicted that the vehicle 5 will enter the dilemma zone Z in the future, the determination unit 32c determines that the vehicle 5 satisfies the priority condition, and the transmission / reception unit 31 preferentially transmits position information, speed information, and the like.

In addition, when the vehicle 5 that has entered the dilemma zone Z suddenly accelerates trying to pass through the intersection before the signal turns red, for example, there is a possibility that the vehicle 5 collides with the vehicle 5 that is about to turn right in the opposite lane. Get higher. Therefore, the determination unit 32c determines that the priority condition is satisfied also for the vehicle 5 that is rapidly accelerated or the vehicle 5 that is predicted to be suddenly accelerated, and the transmission / reception unit 31 preferentially transmits position information, speed information, and the like, The existence of the vehicle 5 can be informed to the surrounding vehicles 5, and contact between vehicles can be prevented in advance.
Note that the entry into the dilemma zone Z and the prediction that the vehicle will enter is based on the signal information included in the peripheral information transmitted from the roadside communication device 2 (the current or future signal lamp color and the expected duration of the lamp color, It is possible to detect from the light color cycle etc.) and the position and speed of the self.

  When the vehicle 5 stopped at an intersection or the like starts to travel, there is a possibility that the vehicle 5 surrounding it, for example, the vehicle 5 that is about to pass through the intersection even if the signal of the intersecting lane turns red Therefore, in this case as well, by transmitting the position information and the like preferentially by the transmission unit 31 of the in-vehicle communication device 3 mounted on the vehicle 5 about to start traveling, the presence of the vehicle 5 is It is possible to inform the vehicle 5 and prevent the vehicles from contacting each other.

When there is a vehicle 5 that is making a right or left turn or a vehicle 5 that is changing lanes, the vehicle 5 that goes straight in the opposite lane, the vehicle 5 that is located in a crossing lane, the vehicle 5 that runs in parallel, etc. In such a case, the vehicle-mounted communication device 3 of the vehicle 5 can prevent the vehicle from contacting each other by transmitting the position information and the like with priority. The same applies when it is predicted that the vehicle will turn left or right or change lanes.
In addition, the vehicle 5 currently traveling at high speed tends to be delayed in response to changes in the surrounding situation, and the possibility of inducing an accident is increased. Therefore, the determination unit 32c of the in-vehicle communication device 3 mounted on the vehicle determines that the vehicle 5 satisfies the priority condition, and causes the transmission unit 31 to transmit position information and the like preferentially, thereby causing an accident. Can be prevented in advance.

  In the third embodiment, some current or future behaviors are listed. However, all of these may be set as priority conditions, or some of them may be set as priority conditions. Which is the priority condition can be determined according to the road conditions (road width, number of lanes, traffic volume, good or bad prospect, etc.). Also, other behaviors other than those described above may be set as the priority conditions.

With respect to the present invention, it should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. 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.
Although this embodiment demonstrated as the vehicle-mounted communication apparatus 3 (mobile communication apparatus for vehicles mounted in the vehicle 5), you may mount the mobile communication apparatus of this invention in addition to a vehicle. For example, a mobile terminal may be used as the mobile communication device. Whether or not the vehicle is an emergency vehicle instead of, or in addition to, the in-vehicle communication device determining whether the priority condition is satisfied according to the behavior of the vehicle or other vehicle as in the above-described embodiment. For example, it may be determined whether or not the priority condition is satisfied based on vehicle attribute information given in advance.
In the above-described embodiment, a plurality of methods for determining that the in-vehicle communication device 3 is located in the priority area A2 have been described. However, the present invention is not limited to this. For example, whether or not the in-vehicle communication device 3 is located in the priority area A2 may be determined based on whether or not the reception level of the signal from the roadside communication device 2 is equal to or higher than a predetermined threshold. Furthermore, it may be determined whether the in-vehicle communication device 3 is located in the priority area A2 by combining these plural methods.

DESCRIPTION OF SYMBOLS 1 Traffic signal device 2 Roadside communication device 3 Car-mounted communication device 5 Vehicle 21 Wireless transmission / reception part 23 Control part 23a Allocation part 23e Command notification part 31 Transmission / reception part 32c Judgment part 32d Adjustment part T1 1st time slot T2 2nd time slot T21 Priority time slot T22 General time slot

Claims (16)

  A first time slot for prohibiting transmission of radio signals from the mobile communication device and allowing transmission of radio signals by the roadside communication device itself, and priority for allowing transmission of radio signals by the mobile communication device satisfying a predetermined priority condition A roadside communication device comprising a transmission unit that is supplied with time slot information about a second time slot including a time slot and transmits the time slot information to the mobile communication device in a communication area. .   The roadside communication device according to claim 1, further comprising an assigning unit that assigns the first and second time slots, wherein the time slot information is supplied from the assigning unit to the transmitting unit.   The roadside according to claim 1 or 2, wherein the second time slot includes the priority time slot and a general time slot that allows transmission of radio signals by all mobile communication devices in the communication area. Communication machine.   The roadside communication device according to any one of claims 1 to 3, wherein the priority condition is that the mobile communication device is located in a predetermined priority area set in the communication area.   The roadside communication device according to claim 4, further comprising a priority area notification unit for notifying the mobile communication device of priority area information indicating the priority area with the priority area as a transmission range.   A command notification unit for notifying command information for causing the mobile communication device or another mobile communication device to adjust communication conditions so that a radio signal transmission opportunity of the mobile communication device satisfying the priority condition is improved; The roadside communication device according to any one of claims 1 to 5. A mobile communication device that performs wireless communication in a communication area of a roadside communication device,
A time slot information acquisition unit for acquiring time slot information including a priority time slot allowing transmission of a radio signal by the mobile communication device satisfying a predetermined priority condition;
A determination unit for determining whether or not the priority condition is satisfied;
A mobile communication device comprising: a transmission unit configured to transmit a radio signal in the priority time slot when the determination unit determines that the priority condition is satisfied.   The determination unit according to claim 7, wherein the determination unit determines whether the priority condition is satisfied based on whether a mobile communication device is located in a predetermined priority area set in the communication area. Mobile communication device.   The said determination part is comprised so that it may determine whether the said mobile communication apparatus is located in a priority area from the result, detecting the position of the present mobile communication apparatus itself. Mobile communication device.   The determination unit indicates the priority area, and the mobile communication device is located in the priority area depending on whether or not the priority area information transmitted from the roadside communication device is acquired with the priority area as a transmission range. The mobile communication device according to claim 8 or 9, wherein the mobile communication device is configured to determine whether or not there is.   The mobile communication device according to claim 7, wherein a current behavior or a future predetermined behavior of a mobile body equipped with the mobile communication device is set as the priority condition.   The mobile communication device according to claim 11, wherein the predetermined behavior is a behavior related to a speed of a moving body.   The mobile communication device according to claim 11, wherein the predetermined behavior is a behavior related to a change in a moving direction of a moving body.   The mobile communication device according to any one of claims 7 to 13, further comprising an adjustment unit that adjusts communication conditions so that a radio signal transmission opportunity of the mobile communication device that satisfies the priority condition is improved. .   The mobile communication device according to claim 14, wherein the adjustment of the communication condition performed by the adjustment unit is adjustment of a transmission waiting time of a radio signal by the transmission unit. A road communication system having a roadside communication device installed on a road and a mobile communication device mounted on a mobile body,
The roadside communication device is
A first time slot for prohibiting transmission of radio signals from the mobile communication device and allowing transmission of radio signals by the roadside communication device itself; and transmission of radio signals by the mobile communication device satisfying a predetermined priority condition. A transmission unit configured to transmit time slot information about a second time slot including a permitted priority time slot to the mobile communication device in a communication area;
The mobile communication device is
A time slot information acquisition unit for acquiring the time slot information;
A determination unit for determining whether or not the priority condition is satisfied;
A road communication system comprising: a transmission unit configured to transmit a radio signal in the priority time slot when the determination unit determines that the priority condition is satisfied.

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