JP5251642B2 - Mobile communication device, roadside communication device, method for adjusting transmission conditions, and computer program - Google Patents

Description

The present invention relates to a mobile communication device, a roadside communication device , a method for adjusting transmission conditions , and a computer program .

In recent years, for the purpose of promoting traffic safety and preventing traffic accidents, vehicle safety has been achieved by receiving information from infrastructure devices installed on the road and exchanging information such as the position and speed of each other between vehicles. An intelligent road traffic system that improves the above has been studied (for example, see 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, a combination of communication performed between communication subjects includes road-to-road communication between road-side communication devices, road-to-vehicle (or vehicle-road) communication between road-side communication devices and vehicle-mounted communication devices, and vehicle-mounted communication. Vehicle-to-vehicle communication performed between aircraft.

Japanese Patent No. 2806801

Generally, in the above-described intelligent transportation system, each communication is realized by assigning limited communication resources to road-to-road communication, road-to-vehicle communication, and vehicle-to-vehicle communication.
However, when the above-described intelligent road traffic system is applied to, for example, a highway with a large amount of vehicle traffic, traffic in vehicle-to-vehicle communication increases, so communication resources allocated for vehicle-to-vehicle communication are sufficient for each vehicle. Communication opportunities could not be provided, and there was a risk that information could not be sufficiently transmitted and received in each vehicle.
For this reason, even if the traffic in vehicle-to-vehicle communication increases, there has been a demand for a method that enables more efficient vehicle-to-vehicle communication and effective use of communication resources in order to give each vehicle sufficient communication opportunities.

The present invention has been made in view of such circumstances, a mobile communication device, a roadside communication device , a method for adjusting transmission conditions , capable of more efficiently performing communication between vehicles and effectively using communication resources, And to provide a computer program .

(1) The present invention is a mobile communication device mounted on a mobile body, a transmission unit for transmitting a radio signal to another communication device, prediction means for predicting the behavior of the mobile body, and the prediction Transmission condition adjusting means for adjusting a transmission condition of the transmission unit based on a prediction result of the means, and the prediction means behaves based on the surrounding information indicating the surrounding situation of the moving object. The peripheral information includes information on the current status and future display of the signal lamp installed in front of the path of the mobile body, and the presence of other mobile bodies located in front of the mobile body. It is characterized by including at least one of the information regarding .

For example, when it is predicted that the future behavior of the mobile body is in a stopped state, the mobile body is unlikely to come into contact with other mobile bodies, etc. There is little need for a communication device to transmit its information to the surroundings. In such a case, according to the mobile communication device of the present invention, the behavior of the moving body is predicted by the prediction means, and the transmission condition for transmitting the radio signal to another communication device is adjusted based on the prediction result. Therefore, it is possible to adjust the transmission conditions of the transmission unit so as to expand the transmission opportunities of other communication devices, and as a result, the mobile communication device with less need for transmitting its own information can be used. Communication resources can be used by other communication devices.
That is, according to the mobile communication device of the present invention, vehicle-to-vehicle communication can be performed more efficiently by adjusting the transmission condition for transmitting a radio signal to another communication device according to the predicted behavior of the moving body. Communication resources can be used effectively.

(2) The prediction means predicts whether or not the behavior of the moving body becomes a stopped state or a deceleration state within a predetermined time, and the transmission condition adjusting means uses the prediction means to It is preferable that the transmission condition is adjusted so as to widen the transmission opportunity of the communication device when the behavior is predicted to be a stopped state or a deceleration state.
In this case, if the behavior of the moving body is predicted to be stopped or decelerated, there is less possibility of contact with other moving bodies as described above. Less need to send to communication equipment. For this reason, by adjusting the transmission conditions to expand the transmission opportunities of other communication devices, communication resources that can be used by this mobile communication device can be used by other communication devices, and communication resources can be used effectively. can do.

  (3) More specifically, the prediction means may predict the behavior of the moving body when it reaches the vicinity of an intersection located in front of the path of the moving body. It is possible to predict the behavior at an intersection where contact or the like is likely to occur with respect to the moving body.

  (4) Since the behavior of the moving body is determined by the surrounding situation of the moving body, the predicting means predicts the behavior of the moving body based on surrounding information indicating the surrounding situation of the moving body. Is preferred. In this case, the prediction means can accurately predict the future behavior of the mobile object.

(5) The peripheral information includes information on the current status and future display of the signal lamp installed in front of the path of the mobile body, and information on the presence of other mobile bodies located in front of the mobile body. , At least one of them may be included.
The future behavior of a moving object is determined by the indication of a signal lamp installed in front of the path or the presence of another moving object located in front of the moving object. In addition, it is possible to predict the behavior of the mobile body more accurately by using at least one of the information on the future display and the information on the presence of the other mobile body located in front of the mobile body. it can.

  (6) It is preferable that the said prediction means acquires the said periphery information with the radio signal which the roadside communication apparatus installed in the roadside transmits, and the prediction means can acquire accurate periphery information easily.

(7) The mobile communication device further includes detection means for detecting the current behavior of the mobile body, wherein the transmission condition adjustment means is configured to detect the prediction result and the current behavior of the mobile body detected by the detection means. Based on the above, the transmission condition of the transmission unit may be adjusted.
In this case, the transmission condition adjusting means can take into account the behavior of the current mobile body in addition to the behavior of the future mobile body predicted by the prediction means, and can adjust to a more suitable transmission condition.

(8) The transmission condition adjusting means may adjust at least one of transmission power, transmission interval, back-off time, and carrier sense level. In this case, the transmission condition adjusting means Adjustments can be made by selecting or combining the transmission conditions, and the transmission conditions can be adjusted according to the prediction result of the prediction means.
(9) Further, the present invention is a roadside communication device that performs radio communication with a mobile communication device mounted on a mobile body, and grasps a surrounding state of the mobile body, and predicts the behavior of the mobile body The mobile communication device that adjusts the transmission condition for transmitting a radio signal to another communication device from the prediction result indicates the surrounding situation, which is information necessary for predicting the behavior of the mobile object. It is characterized by comprising peripheral information generating means for generating peripheral information and transmitting means for transmitting the peripheral information to the mobile communication device.

According to the roadside communication device having the above configuration, the peripheral information necessary for predicting the behavior of the mobile object can be generated and transmitted to the mobile communication device by the peripheral information generation unit and the transmission unit. It is possible to cause the machine to predict its future behavior and to adjust the transmission conditions for transmitting the radio signal to other communication apparatuses according to the prediction result.
As a result, it is possible to cause the mobile communication device to perform more efficient vehicle-to-vehicle communication and to effectively use communication resources.

Further, the present invention is a method for adjusting a transmission condition for a mobile communication device mounted on a mobile body to transmit a radio signal to another communication device, and predicting the behavior of the mobile body; Adjusting a transmission condition for transmitting a radio signal to the other communication device based on a prediction result of the predicting step, and predicting the behavior of the mobile object includes: The behavior of the moving body is predicted based on the surrounding information indicating the surrounding situation, and the surrounding information includes information on the current state and future display of the signal lamp installed in front of the path of the moving body, and And at least one of the information on the presence of other moving bodies located in front of the moving body.
The present invention is also a computer program for causing a mobile communication device mounted on a mobile body to execute processing for adjusting a transmission condition for transmitting a radio signal to another communication device. Predicting body behavior, and adjusting a transmission condition for transmitting a radio signal to the other communication device based on a prediction result of the predicting step. Computer program for
The step of predicting the behavior of the mobile object is to predict the behavior of the mobile object based on the peripheral information indicating the peripheral condition of the mobile object, and the peripheral information is placed in front of the course of the mobile object. It includes at least one of information on the current status and future display of the installed signal lamp and information on the presence of other moving bodies located in front of the moving body.
(10) Further, the present invention relates to a roadside communication device that performs wireless communication with a mobile communication device mounted on a mobile body, and relates to a grasping means for grasping a surrounding situation of the mobile body, and a position of the mobile communication device. Position information acquisition means for acquiring position information, peripheral information generation means for generating peripheral information indicating the peripheral situation, prediction means for predicting the behavior of the mobile body based on the positional information and the peripheral information, Based on the prediction result of the prediction means, transmission condition determination means for determining a transmission condition for the mobile communication device to transmit a wireless signal to another communication device, and adjustment of the wireless signal transmission condition to the mobile communication device In order to do so, it is characterized by comprising transmission means for transmitting transmission condition information indicating the transmission condition to the mobile communication device.

According to the roadside communication device having the above configuration, the behavior of the mobile body is predicted from the peripheral information indicating the peripheral information of the mobile body and the position information of the mobile communication device, and based on the prediction result, the mobile communication device performs other communication. It is possible to determine the transmission conditions for transmitting a radio signal to the machine and transmit the transmission condition information indicating the transmission conditions to the mobile communication apparatus. Transmission conditions can be adjusted according to the expected future behavior.
As a result, it is possible to cause the mobile communication device to perform more efficient vehicle-to-vehicle communication and to effectively use communication resources.

(11) The present invention is a road communication system comprising a roadside communication device installed on the road side and a mobile communication device mounted on a mobile body and performing wireless communication with the roadside communication device, The roadside communication device has a grasping means for grasping a surrounding situation of the mobile body, and the mobile communication device transmits a radio signal to another communication device based on a prediction result of the behavior of the mobile body. A transmission condition adjusting means for adjusting a transmission condition for performing at least one of the roadside communication device and the mobile communication device based on a surrounding situation grasped by the grasping means, The apparatus further comprises prediction means for predicting the behavior of the mobile body, and adjusting the transmission conditions of the mobile communication device based on the behavior of the mobile body predicted by the prediction means.

According to the road communication system configured as described above, at least one of the roadside communication device and the mobile communication device includes the prediction unit that predicts the behavior of the mobile body based on the surrounding situation of the mobile body. The mobile communication device can adjust transmission conditions for transmitting a radio signal to another communication device according to the predicted behavior of the mobile communication device.
As a result, it is possible to cause the mobile communication device to perform more efficient vehicle-to-vehicle communication and to effectively use communication resources.

As described above, according to the mobile communication device, the roadside communication device , the method for adjusting transmission conditions , and the computer program of the present invention, it is possible to more efficiently perform vehicle-to-vehicle communication and effectively use communication resources.

It is a schematic perspective view which shows the whole structure of an intelligent road traffic system. It is a top view which shows a part of intelligent traffic system. It is a block diagram which shows the internal structure of the roadside communication apparatus and vehicle-mounted communication apparatus which comprise the communication system which is 1st embodiment. 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 shows the condition where the vehicle is approaching the intersection which enters the communication area and is located ahead of the advancing direction. It is a top view which shows the relationship with the other vehicle in the intersection of a vehicle when future behavior is estimated to be an advancing state. It is a top view which shows the relationship with the other vehicle in the intersection of a vehicle when a future behavior is estimated as a stop state. It is a block diagram which shows the internal structure of the roadside communication apparatus and vehicle-mounted communication apparatus which comprise the communication system which is 2nd embodiment of this invention.

[Overall system configuration]
FIG. 1 is a schematic perspective view showing an overall configuration of an intelligent road traffic system (ITS).
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 a vehicle (moving body) 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. 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 and FIG. 2, 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 A of 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 A. The communication area A 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.
In the suburbs where the roadside communication device 2 is not installed, the communication area of the roadside communication device 2 does not exist.

  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.
On the other hand, in the suburbs where there are few intersections where signals are installed and the number of roadside communication devices 2 is not set or set, there is no communication area A 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 there is a margin in the communication band compared to the city center.

[First embodiment]
[Roadside communication devices and in-vehicle communication devices]
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. Therefore, 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 (see FIG. 4) in a time-sharing manner at regular intervals is provided.
The allocation of the first time slot T1 and the second time slot T2 does not need to be determined periodically, and the roadside communication device 2 or a device (such as a central control device) that controls the roadside communication device 2 is mainly used. It may be the allocation determined in the above.

FIG. 4 shows an example of the first time slot and the second time slot. In principle, the first time slot T1 is a period in which only the roadside communication device 2 has the authority to transmit, and transmission (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. Further, the slot T1 may be assigned to a specific vehicle permitted by the roadside communication device 2 in advance, and the vehicle may be used for inter-vehicle communication.
Note that 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. Also, the number of roadside slots corresponding to the first time slot T1 is not limited to one in one cycle, and may be plural.

  The second time slot T2 is a time other than the first time slot T1, and in this time zone, a plurality of in-vehicle communication devices 3 acquire a transmission opportunity by the CSMA / CA method, and the inter-vehicle communication and the inter-road communication Communicate. 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 allocation unit 23a indicates a time zone (time zone for roadside communication devices) assigned to the in-vehicle communication device 3 for the roadside communication device 2 in order to prohibit inter-vehicle communication in the first time slot T1. A process of transmitting roadside slot information is performed. The slot information is transmitted (broadcast transmission) to the in-vehicle communication device 3 by the wireless transmission / reception unit 21.

Returning to FIG. 3, 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. Further, the traffic jam information acquisition unit 23c is information regarding whether or not there is a vehicle 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. Is acquired from the central device 4 via the wired transmission / reception unit 22. In other words, the traffic jam information acquisition unit 23c acquires vehicle information related to the presence of another vehicle located in front of the vehicle 5. 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 the vehicle information from the vehicle detector.

The peripheral information generation unit 23d is a peripheral that indicates the peripheral situation of each vehicle 5 located in its own communication area A from the signal information, the traffic jam information, and the vehicle information acquired by the signal information acquisition unit 23b and the traffic jam information acquisition unit 23c, respectively. Generate information. That is, the signal information acquisition unit 23b and the traffic jam information acquisition unit 23c constitute a grasping unit that grasps the signal information, the traffic jam information, and the vehicle information as the surrounding situation of the vehicle 5, and the surrounding information generation unit 23d Peripheral information generation means for generating peripheral information indicating the peripheral situation 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 A via the wireless transmission / reception unit 21.

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 causes the transmission / reception unit 31 to perform wireless communication by the carrier sense method (CSMA / CA method) for inter-vehicle communication. The carrier sense control unit 32a of the control unit 32 detects whether or not a radio signal having a predetermined carrier frequency exists in the radio signal propagation path, and gives a transmission opportunity after the state in which the radio signal does not exist is maintained for a predetermined time. Acquire and control transmission.
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.

Further, when acquiring the road side slot information transmitted from the roadside communication device 2 or the other in-vehicle communication device 3, the control unit 32 stores the roadside slot information in the storage unit 33. Furthermore, the control unit 32 also has a function of performing processing for transferring (wireless transmission) the acquired roadside slot information to the other in-vehicle communication device 3.
In the state where the roadside slot information is acquired, the control unit 32 prohibits transmission in the time zone indicated by the roadside slot information. That is, in the time slot T1 indicated by the roadside slot information, transmission is limited so that a transmission opportunity is not obtained even if a radio signal does not exist in the propagation path. As a result, in the time zone 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 roadside slot information is not acquired (including the case where the acquired roadside slot information is invalidated), transmission is not prohibited for the roadside communication device 2 and the vehicle-mounted communication device 3 transmits it. The time zone in which the opportunity can be acquired 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 roadside slot information does not need to be acquired from the roadside communication device 2, and may be acquired by, for example, an optical beacon installed near the communication area before entering the communication area.

  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.

[Other functions of the control unit of the in-vehicle communication device]
The control unit 32 of the in-vehicle communication device 3 is a behavior prediction unit for predicting the future behavior of the vehicle 5 in addition to the carrier sense control unit 32a as a function unit executed by the computer program stored in the storage unit 33. 32b, a detection unit 32c for detecting the current behavior of the vehicle 5, and an adjustment unit 32d for adjusting the transmission power of the transmission / reception unit 31 based on the behaviors.

  The detection unit 32c detects the current behavior of the vehicle 5 on which it is mounted, and outputs the current behavior information as a result to the adjustment unit 32d. The detection unit 32c detects the vehicle speed, the position, and the traveling direction (or whether the vehicle 5 is traveling straight or curved) as the current behavior of the vehicle 5. These current behaviors can be detected by 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 32b predicts the future behavior of the vehicle 5 on which the behavior prediction unit 32b is mounted, and outputs the future behavior information as a result thereof to the adjustment unit 32d. The behavior predicting unit 32b 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 related to 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. The behavior prediction unit 32b includes information related to the detection result of the vehicle sensor 42 that detects whether or not there is a vehicle around the vehicle 5 in addition to the surrounding information and the current state of the detection unit 32c. It is also possible to predict future behavior by adding behavior information.

When the vehicle 5 enters the communication area A of the roadside communication device 2 and receives the peripheral information transmitted from the roadside communication device 2, the behavior prediction unit 32 b indicates the future behavior of the vehicle 5 as the future behavior of the vehicle 5. It is comprised so that the behavior of the said vehicle 5 when the vicinity of the intersection located in may be estimated.
More specifically, when the behavior prediction unit 32b receives the peripheral information, the behavior prediction unit 32b enters a stop state in the future within a predetermined time until the vehicle 5 reaches the vicinity of the intersection, or travels straight (turns straight or turns right or left). ) Is predicted. The behavior prediction unit 32b also predicts whether or not the vehicle 5 is currently in a so-called dilemma zone, or whether the vehicle 5 will enter the dilemma zone when it reaches the vicinity of the intersection. Note that when the predicted behavior of the vehicle 5 is, for example, a traveling state, the predicted behavior of the vehicle can be further subdivided by the speed or the like.
The predetermined time until reaching the vicinity of the intersection is set to a time required for the vehicle 5 to reach the vicinity of the intersection while maintaining the current speed (for example, about several tens of seconds).

  Here, the dilemma zone means that the traffic light in front of the vehicle changes from blue to yellow before the vehicle enters the intersection, so that it cannot safely stop at the stop line at normal deceleration and the traffic light is red. This is a temporal and spatial area where it is impossible to enter an intersection before it becomes. When the vehicle 5 enters the dilemma zone when it reaches the intersection, it is difficult to make an accurate prediction because the driver's judgment is high in predicting whether or not the vehicle 5 will stop. There is a case. For this reason, the behavior predicting unit 32b also predicts whether or not the vehicle enters the dilemma zone (or is currently in the dilemma zone) in addition to the stopped state and the traveling state (straight, left / right turn). To do.

Hereinafter, the aspect of prediction of the future behavior of the vehicle 5 performed by the behavior prediction unit 32b will be described. Here, as shown in FIG. 5, a description will be given along the case where the vehicle 5 is traveling toward the intersection C entering the communication area A and positioned forward in the traveling direction.
As described above, the behavior predicting unit 32b determines the intersection as the future behavior of the vehicle 5 based on the received peripheral information and the direction information on the future traveling direction of the vehicle 5 acquired from the winker relay 45 of the vehicle 5 or the like. The behavior of the vehicle 5 when C is reached is predicted.
The behavior predicting unit 32 b of the in-vehicle communication device 3 can acquire the signal information of the traffic signal 1 at the intersection C by the peripheral information transmitted from the roadside communication device 2. As described above, 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 durations of other lamp colors displayed after the current status. It is a number, including the number of seconds that each lamp color will continue for several cycles.
In predicting the behavior of the vehicle 5, the behavior prediction unit 32 b predicts the color of the traffic light 1 when the vehicle 5 travels as it is and reaches the intersection C based on the signal information. In addition, when the peripheral information from the roadside communication device 2 includes traffic jam information on the upstream side of the traffic signal 1 generated based on the vehicle sensor 6 on the upstream side of the lane where the traffic signal 1 is installed, The prediction unit 32b also considers a vehicle train due to traffic congestion near the intersection C. The behavior prediction unit 32b also considers the current behavior information output by the detection unit 32c.

  The behavior prediction unit 32b predicts the color of the traffic light 1 when the vehicle 5 reaches the intersection C, or when the vehicle 5 is behind the vehicle train in a traffic jam. As a result of the prediction, if the lamp color is red, the behavior predicting unit 32b predicts that the vehicle 5 is stopped when it reaches the intersection C or at the rear of the train. On the other hand, when it is predicted that the light color of the traffic light 1 when the vehicle 5 reaches the intersection C is blue, the behavior predicting unit 32b predicts that the vehicle 5 is traveling in the intersection C as it is. . Furthermore, when the vehicle 5 travels in the intersection C, the behavior predicting unit 32b further predicts whether to go straight or turn left or right based on the direction information.

The behavior prediction unit 32b also predicts whether or not the vehicle 5 will enter the dilemma zone (or is currently in the dilemma zone) when it reaches the intersection C. For example, when it is predicted that the light color of the traffic light 1 will be yellow or red immediately before the vehicle 5 reaches the intersection C, or when it cannot be predicted that the vehicle will surely stop and cannot be predicted that it will surely advance. The vehicle 5 can be predicted to enter the dilemma zone.
As described above, the behavior prediction unit 32b determines whether the behavior when the vehicle 5 reaches the intersection C is in a stopped state, a traveling state (straight forward, left / right turn), or a state in which the vehicle enters the dilemma zone. Predict.

As described above, the future behavior of the vehicle 5 is determined by the surrounding situation of the vehicle 5. As described above, in the present embodiment, the behavior predicting unit 32b predicts the behavior of the vehicle 5 based on the surrounding information indicating the surrounding situation of the vehicle 5, and therefore accurately predicts the future behavior of the vehicle 5. Can do.
More specifically, the behavior of the vehicle 5 when the vehicle 5 reaches the intersection C is determined by the display of the traffic light 1 installed at the intersection C. In this respect, the surrounding information includes information on the current state and future display of the traffic light 1 installed at the intersection C, and vehicle information on the presence of other vehicles located in front of the vehicle 5, so that the behavior prediction unit 32b can predict the future behavior of the vehicle 5 more accurately by using information on the current state and future display of the traffic light 1 and the vehicle information.
Furthermore, since the behavior prediction unit 32b acquires the peripheral information from a radio signal transmitted by the roadside communication device 2, the behavior prediction unit 32b can easily acquire the accurate peripheral information.

  The adjustment unit 32d controls the transmission / reception unit 31 to adjust the transmission conditions based on the current state and future behavior of the vehicle 5. The adjustment unit 32d has a plurality of modes (stop mode, progress mode, dilemma mode, and later details) according to the future behavior of the vehicle 5 predicted by the behavior prediction unit 32b (stop state, progress state, and dilemma mode). Select) and adjust the transmission conditions.

  In the present embodiment, the adjustment unit 32d adjusts the transmission interval, backoff time, carrier sense level, and transmission power in the CSMA scheme as transmission conditions. These transmission conditions are parameters that affect the transmission opportunities of other in-vehicle communication devices 3.

In general, if the transmission power is reduced under the transmission conditions, it is difficult for radio waves to reach far away, so that it is difficult for other in-vehicle communication devices to receive them. For this reason, when the adjustment unit 32d adjusts the transmission power to be relatively small, there is a probability that the radio signal transmitted by the in-vehicle communication device 3 is received (detected by carrier sense) by the other in-vehicle communication device 3. Lower. For this reason, the transmission opportunity of the other vehicle-mounted communication apparatus 3 expands.
On the other hand, when the adjustment unit 32d adjusts the transmission power to be relatively large, compared to the case where the transmission power is adjusted to a relatively small transmission power, the radio wave is likely to reach far. The probability that the radio signal is received (detected by carrier sense) by the other in-vehicle communication device 3 increases. For this reason, the transmission opportunity of the other vehicle-mounted communication apparatus 3 reduces.

  The transmission interval in the transmission condition is, for example, a case where transmission of a radio signal is determined every 100 milliseconds during high-speed traveling and transmission of a wireless signal is determined every 500 milliseconds when stopped. This is a time interval of a cycle for determining transmission of a radio signal, and is a parameter for setting a frequency for determining transmission of a radio signal.

In wireless communication using the carrier sense method (CSMA / CA method), after the vehicle-mounted communication device determines transmission of a wireless signal, carrier sensing is performed and a state in which a wireless signal from another wireless device is not received is determined in advance. When the time is continuously maintained for a total time obtained by adding the time (Distributed Coordination Function Interframe Space) and a back-off time having a predetermined CW value (Contention Window size) as a maximum value, transmission of a radio signal is performed. To start.
When a radio signal from another radio is received during the total time, transmission of the radio signal is given up and carrier sensing is performed again. And if the radio signal from another radio | wireless machine is not received during the said total time, the said vehicle-mounted communication apparatus will transmit a radio signal.
The back-off time is multiplied by a predetermined time (for example, time per slot) to a value that is randomly determined from a value between “0” and a predetermined CW value (Contention Window size). It is a value set by doing.
The adjustment unit 32d of the present embodiment adjusts the back-off time by adjusting the CW value.

In the in-vehicle communication device, when the back-off time is increased, the transmission opportunity is reduced as compared with the case where the back-off time is short. In other words, an in-vehicle communication device with a long backoff time has a relatively long carrier sensing time from when transmission is decided to when it is actually transmitted, and the probability that another communication device starts transmission during that time increases. , Transmission opportunities are reduced. On the other hand, the in-vehicle communication device with a short back-off time has a relatively short waiting time for transmission, and the transmission opportunity is expanded. That is, the in-vehicle communication device having a relatively long back-off time is set to have a substantially lower priority for transmission of the radio signal than the in-vehicle communication device having a relatively short back-off time.
When the adjustment unit 32d adjusts the back-off time to be long, the priority for transmission of the radio signal is set low, and the transmission opportunity decreases. As a result, the priority with respect to the transmission of the radio signal of the other in-vehicle communication device 3 is relatively increased, and the transmission opportunity for transmitting the radio signal of the other in-vehicle communication device 3 is expanded.

  Also, the transmission interval is the same as the back-off time, and if the in-vehicle communication device lengthens the transmission interval, the frequency of determining the transmission of the radio signal is less than when it is short, so the transmission opportunity decreases, and the radio signal Is set to a substantially lower priority.

In addition, the carrier sense level in the transmission condition is the sensitivity of carrier sensing performed during the transmission interval described above. When the level is lowered, the sensitivity of carrier sensing increases, and the radio signal is a relatively low level radio signal. However, the presence is set to be detected with high probability. For this reason, if the carrier sense level is lowered, it becomes easier to receive radio signals from other radio units during the transmission interval, and transmission is actually started after carrier sensing even if transmission of radio signals is determined. Probability decreases. That is, when the carrier sense level is lowered, the own transmission opportunity decreases, and the transmission opportunity for transmitting the radio signal of the other in-vehicle communication device 3 increases.
On the contrary, when the carrier sense level is increased, the transmission opportunity of itself increases and the transmission opportunity of transmitting the radio signal of the other in-vehicle communication device 3 decreases.

Table 1 below shows an example of an aspect of adjustment of transmission conditions based on the current state and future behavior of the vehicle 5 by the adjustment unit 32d.
The adjustment unit 32d selects the stop mode when the prediction result of the behavior prediction unit 32b is “stop state”, selects the progress mode when the prediction result is “progress state”, and enters the “dilemma zone”. If it is “entered”, the dilemma mode is selected. Table 1 shows an example of transmission power adjusted in each mode with respect to the speed of the current vehicle 5 as the current behavior. In the example of Table 1, the transmission interval, backoff time, and carrier sense level are set to be constant.
Here, the “result of entering the dilemma zone”, which is a prediction result by the behavior predicting unit 32b, is the current dilemma in addition to the case where the vehicle 5 is predicted to enter the dilemma zone when it reaches the intersection C. This includes cases that are in a zone.

The table shown in Table 1 is stored in the storage unit 33. When any of the modes is selected, the adjustment unit 32d refers to the table shown in Table 1 stored in the storage unit 33 and selects each mode. The transmission power of the radio signal is adjusted according to the current speed.
In Table 1, the adjustment unit 32d adjusts the transmission power to increase as the current speed increases in each mode. If the speed is low, the possibility of touching other vehicles is low, and the higher the speed, the more likely it is to come into contact with other vehicles. This is because transmission over a wider range is necessary.

  Further, the adjustment unit 32d is set to a smaller transmission power in the stop mode in which the vehicle 5 is predicted to be stopped in the future as compared with the traveling mode (or dilemma mode). For this reason, in the stop mode, the probability that the wireless signal transmitted by the in-vehicle communication device 3 is received (detected by carrier sense) by the other in-vehicle communication device 3 becomes lower in the stop mode. The transmission opportunity of the machine 3 is expanded.

  The control unit 32 causes the behavior prediction unit 32b to predict behavior at any time from entering the communication area A until reaching the intersection, and causes the adjustment unit 32d to select each mode accordingly. Thereby, even if the situation around the vehicle 5 changes before the vehicle 5 reaches the intersection, the transmission power (transmission condition) can be adjusted according to the change.

FIG. 6 is a plan view showing a relationship with another vehicle at the intersection of the vehicle 5 when the future behavior is predicted to be the progress state. In FIG. 6, when the behavior prediction unit 32 b predicts that the future behavior of the vehicle 5 is in the progress state based on the surrounding information or the like, the vehicle 5 that has entered the communication area A will eventually enter the intersection C and go straight ahead. Or turn right or left. In this case, since the vehicle 5 enters the intersection C, for example, when the vehicle 5 makes a right turn, there is a possibility of a so-called right-right collision with the vehicle 52 that goes straight on the opposite lane, and the vehicle 5 makes a left turn. There is a possibility of a collision involving another vehicle. Thus, when it is predicted that the vehicle 5 does not stop at the traffic light 1 and enters the intersection C, there is a high possibility that contact or the like will occur with another vehicle. Need to be transmitted over the Therefore, in the traveling mode, the transmission power is adjusted to a relatively high value, and its information is transmitted over a wide range.
Specifically, for example, if the current speed of the vehicle 5 entering the communication area A in FIG. 6 is 40 km / h, the transmission power is adjusted to 15 dBm as shown in Table 1. At this time, the transmission signal of the in-vehicle communication device 3 can be received in a range B1 indicated by a two-dot chain line in the drawing. That is, it is received by the in-vehicle communication device mounted on each vehicle existing around the intersection C.

  In the dilemma mode, it should be basically determined that the vehicle is in the progress state. However, in the dilemma mode, it may be possible to accelerate even if the current speed is low, according to the judgment of the driver of the vehicle. Therefore, in Table 1, in the case where the current speed is low compared to the traveling mode, The transmission power is adjusted to be high. For this reason, in the case of the dilemma mode, the transmission signal is transmitted in a wider range than in the traveling mode, and safety support for each vehicle can be more effectively performed.

FIG. 7 is a plan view showing a relationship with another vehicle at the intersection of the vehicle 5 when the future behavior is predicted to be stopped. In FIG. 7, when the behavior prediction unit 32 b predicts that the future behavior of the vehicle 5 is in a stopped state based on the peripheral information or the like, the vehicle 5 that has entered the communication area A will eventually stop behind the vehicle 51. Become.
In this case, it can be said that the vehicle 5 is unlikely to come into contact with other vehicles other than the vehicle 51 in front of it, and it is sufficient to transmit its own information to the vehicle 51 from the viewpoint of safety. is there.
Specifically, for example, in FIG. 7, if the current speed of the vehicle 5 entering the communication area A is 40 km / h, the transmission power is adjusted to 5 dBm as shown in Table 1. At this time, the transmission signal of the in-vehicle communication device 3 can be received in a range B2 indicated by a two-dot chain line in the drawing. That is, the transmission range of the transmission signal is a range that is received by the vehicle 51 located in front of the vehicle 5.

  That is, the behavior predicting unit 32b of the in-vehicle communication device 3 according to the present embodiment predicts whether or not the behavior of the vehicle 5 when reaching the intersection C located in front of the course is in a stopped state. When the behavior of the vehicle 5 predicted by the behavior prediction unit 32b is predicted to be stopped, the adjustment unit 32d is configured to adjust the transmission conditions so as to widen the transmission opportunities of other in-vehicle communication devices.

  Here, when it is predicted that the future behavior of the vehicle 5 on which the in-vehicle communication device 3 is mounted is in a stopped state, the vehicle 5 may come into contact with other surrounding vehicles. Therefore, it is less necessary to transmit information about itself over a wide range. For this reason, it is less necessary to transmit own information over a wide range, transmission power can be further reduced, and transmission opportunities of other in-vehicle communication devices 3 can be expanded. As a result, it is possible to cause other in-vehicle communication devices to use communication resources that can be used by the in-vehicle communication device 3 with less need for transmitting its own information, and the vehicle is determined by the second time slot T2 (see FIG. 4). Communication resources allocated for inter-vehicle communication can be used effectively.

  That is, according to the in-vehicle communication device 3 of the present embodiment, the behavior prediction unit 32b predicts the behavior of the vehicle 5, and based on the prediction result, the transmission condition for transmitting a radio signal to another in-vehicle communication device is set. Since adjustment can be performed, vehicle-to-vehicle communication can be performed more efficiently and communication resources allocated to the vehicle-to-vehicle communication can be effectively utilized.

In the example shown in Table 1, the transmission interval, the back-off time, and the carrier sense level are set to be constant. However, the transmission interval, the back-off time, and the carrier sense level may be adjusted according to each mode as with the transmission power.
In this case, the transmission interval and the back-off time in the stop mode are set to large values as compared with the progress mode and the dilemma mode. In the stop mode in which the necessity of transmitting own information over a wide range is small, by setting the transmission interval to be relatively large, the opportunity for transmitting a radio signal by itself decreases, and the transmission opportunity of other in-vehicle communication devices 3 It is because it can be expanded.
In addition, the carrier sense level in the stop mode is set to a lower value compared to the advance mode and the dilemma mode. This is because by setting the carrier sense level to a relatively low value, it is possible to reduce the opportunity for itself to transmit a radio signal and to expand the transmission opportunities of other in-vehicle communication devices 3.

  Also, in Table 1 above, when the predicted behavior is right / left turn and straight travel, all cases are predicted as progress and the transmission power is adjusted, but a mode is provided for each of right turn, left turn and straight travel. Thus, the transmission power can be adjusted. Furthermore, when the speed is also predicted as the behavior of the vehicle predicted in the traveling mode, the adjustment of the transmission power can be subdivided according to the predicted speed.

Moreover, in this embodiment, the detection part 32c for detecting the present behavior of the vehicle 5 is provided, and as shown in the said Table 1, the adjustment part 32d and the prediction result of the behavior prediction part 32b, and detection The transmission condition of the transmission / reception unit 31 is adjusted based on the current vehicle speed that is the behavior of the current moving body detected by the unit 32c.
In this case, the adjustment unit 32d can take into account the current behavior of the vehicle 5 in addition to the future behavior of the vehicle 5 predicted by the behavior prediction unit 32b, and can adjust to a more suitable transmission condition. . In other words, if the current speed of the vehicle 5 is low, the possibility of contact with another vehicle is low, and the higher the speed is, the possibility that contact with other vehicles may occur. Rise. For this reason, if the current speed of the vehicle 5 is low, it may not be necessary to transmit its own information over a wider range.
In the present embodiment, the current speed of the vehicle 5 is also taken into consideration, so that even in such a case, the opportunity for transmitting a radio signal by itself can be reduced, and the transmission opportunity for other in-vehicle communication devices 3 can be expanded. Therefore, communication resources can be used more effectively.

Further, in the present embodiment, the behavior predicting unit 32b is configured to predict whether the behavior of the vehicle 5 is “a stopped state”, “advancing state”, or “a state in a dilemma zone”. However, in addition to these, it is also possible to predict whether or not the vehicle 5 is in a decelerating state without reaching a stop, or is in a “decelerating state” that is currently in a decelerating state. In this case, the behavior prediction unit 32b acquires the vehicle speed of the vehicle 5 from the detection unit 32c with time, and predicts the current deceleration and the deceleration when the vehicle 5 reaches the intersection C.
Even when the vehicle 5 is in a decelerating state, the possibility that the vehicle 5 will come into contact with other vehicles in the surrounding area is reduced, so there is little need to transmit its own information over a wide range. For this reason, own transmission conditions can be adjusted so that the transmission opportunity of the other vehicle-mounted communication apparatus 3 may be expanded.
As described above, by predicting the behavior of the vehicle 5 in more detail, the in-vehicle communication device 3 can adjust its transmission conditions in more detail according to the behavior of the vehicle 5 and is assigned to inter-vehicle communication. It is possible to make more effective use of communication resources.

Further, the roadside communication device 2 of the present embodiment predicts the future behavior of the vehicle 5 with the signal information acquisition unit 23b and the traffic jam information acquisition unit 23c for grasping the surrounding situation of the vehicle 5, and determines other vehicles from the prediction result. The vehicle-mounted communication device 3 that adjusts transmission conditions for transmitting wireless signals to other vehicle-mounted communication devices mounted on the vehicle generates peripheral information that is information necessary for predicting the future behavior of the vehicle 5 A peripheral information generating unit 23d for generating the peripheral information necessary for predicting the future behavior of the vehicle 5, since the peripheral information generating unit 23d and the wireless transmitting / receiving unit 21 for transmitting the peripheral information to the in-vehicle communication device 3 are provided. It can transmit to the vehicle-mounted communication apparatus 3 located in the communication area A. For this reason, the said vehicle-mounted communication apparatus 3 can be made to estimate the future behavior of self, and according to the prediction result, the transmission conditions for transmitting a radio signal to the vehicle-mounted communication apparatus mounted in the other vehicle can be adjusted. .
As a result, the in-vehicle communication device 3 can perform more efficient vehicle-to-vehicle communication, and communication resources can be used effectively.

[Second Embodiment]
FIG. 8 is a block diagram showing an internal configuration of the roadside communication device 2 and the in-vehicle communication device 3 constituting the communication system according to the second embodiment of the present invention. The difference between the present embodiment and the first embodiment is that the control unit 32 of the in-vehicle communication device 3 does not include the behavior prediction unit 32b, and the control unit 23 of the roadside communication device 2 is different from the in-vehicle communication device. 3, a behavior prediction unit 23 e that predicts future behavior of the vehicle 5 on which the vehicle 3 is mounted, a location information acquisition unit 23 f that acquires location information on the location of the vehicle 5, and other vehicles on which the in-vehicle communication device 3 is mounted on other vehicles. It is a point provided with the transmission condition determination part 23g which determines the transmission conditions for transmitting a radio signal to a vehicle-mounted communication apparatus. About another point, it is the same as that of 1st embodiment.

  The control unit 23 of the roadside communication device 2 according to the present embodiment causes the position information acquisition unit 23f to perform wireless communication with the vehicle 5 that has entered the communication area A and acquire position information regarding the position of the vehicle 5. At this time, the position information acquisition unit 23f can acquire not only the position information of the vehicle 5 but also the current behavior information of the vehicle 5 described above, for example.

When the position information of the vehicle 5 is acquired, the control unit 23 of the roadside communication device 2 of the present embodiment causes the behavior prediction unit 23e to predict the future behavior of the vehicle 5 that has entered the communication area A, and the future as a result thereof. Is sent to the transmission condition determination unit 23g.
The behavior prediction unit 23e predicts the future behavior of the vehicle 5 based on the above-described peripheral information generated by the peripheral information generation unit 23d, the position information of the vehicle 5, or the current behavior information of the vehicle 5.

  As the future behavior of the vehicle 5, the behavior prediction unit 23 e indicates that the behavior when the vehicle 5 reaches the intersection is “stop state”, “advance state (straight or straight turn)”, or “in the dilemma zone” It is predicted whether it is “entered state”. In addition, about the aspect of prediction of the future behavior of the vehicle 5 by the behavior prediction part 23e, it is the same as that of said 1st embodiment.

When the future behavior information of the vehicle 5 is given by the behavior prediction unit 23e, the transmission condition determination unit 23g wirelessly transmits the in-vehicle communication device 3 installed in the vehicle 5 to another in-vehicle communication device installed in another vehicle. A transmission condition for transmitting a signal is determined.
The storage unit 24 stores the same table as in Table 1 above, and the transmission condition determination unit 23g refers to the table stored in the storage unit 24 to determine the transmission condition.
Next, the control unit 23 causes the wireless transmission / reception unit 21 to transmit transmission condition information indicating the transmission condition determined by the transmission condition determination unit 23g.

The control unit 32 of the in-vehicle communication device 3 includes a detection unit 32c for detecting its own current behavior and an adjustment unit 32d for adjusting the transmission conditions of its own radio signal. Until the control unit 32 receives the transmission condition information transmitted from the roadside communication device 2 toward itself, the control unit 32 adjusts the transmission condition independently by the detection unit 32c and the adjustment unit 32d.
On the other hand, when the control unit 32 receives the transmission condition information transmitted toward itself, the control unit 32 transmits a radio signal to another in-vehicle communication device mounted on another vehicle based on the transmission condition information. Adjust the transmission conditions.

According to the roadside communication device 2 configured as described above, the future behavior of the vehicle 5 is predicted from the peripheral information indicating the peripheral information of the vehicle 5 and the position information of the in-vehicle communication device 3, and based on the prediction result. The vehicle-mounted communication device 3 determines a transmission condition for transmitting a radio signal to another vehicle-mounted communication device mounted on another vehicle, and transmits transmission condition information indicating the transmission condition to the vehicle-mounted communication device 3 Therefore, the in-vehicle communication device 3 can adjust the transmission condition according to the predicted future behavior of the vehicle 5 on which the vehicle-mounted communication device 3 is mounted.
As a result, the in-vehicle communication device 3 can perform more efficient vehicle-to-vehicle communication, and communication resources can be used effectively.

  In the present embodiment, the roadside communication device 2 includes a behavior prediction unit for predicting the future behavior of the vehicle 5, and the transmission condition is also determined by the roadside communication device 2. Therefore, the in-vehicle communication device 3 can perform efficient inter-vehicle communication with a simple configuration without providing a special function unit.

  The present invention is not limited to the above embodiments. For example, in this communication system, the vehicle-mounted communication device 3 of the vehicle 5 includes an adjustment unit for transmitting to other vehicle-mounted communication devices based on future behavior information of the vehicle 5, and further includes the vehicle-mounted communication device 3 or the roadside Any one of the communication devices 2 may be configured to include a behavior prediction unit for predicting the future behavior of the vehicle 5. In this case, the in-vehicle communication device 3 can perform efficient vehicle-to-vehicle communication, and the degree of freedom is increased in configuring the communication system.

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.
Moreover, although this embodiment demonstrated as the vehicle-mounted communication apparatus 3 (mobile communication apparatus for vehicles mounted in the vehicle 5), the mobile communication terminal of this invention may be provided in the mobile telephone terminal.

DESCRIPTION OF SYMBOLS 1 Traffic signal device 2 Roadside communication device 3 In-vehicle communication device (mobile communication device)
5 Vehicle (moving body)
21 Wireless transmission / reception unit 23b Signal information acquisition unit (grasping means)
23c Traffic jam information acquisition unit (grasping means)
23d Peripheral information generation unit (peripheral information generation means)
23e Behavior prediction unit (prediction means)
23f Position information acquisition unit (position information acquisition means)
23g Transmission condition determining unit (transmission condition determining means)
31 Transmission / Reception Unit 32b Behavior Prediction Unit (Prediction Means)
32c detector (detector)
32d adjustment unit (transmission condition adjustment means)

Claims (7)

A mobile communication device mounted on a mobile body,
A transmission unit for transmitting a radio signal to another communication device;
Predicting means for predicting the behavior of the moving body;
Transmission condition adjustment means for adjusting the transmission condition of the transmission unit based on the prediction result of the prediction means ,
The predicting means predicts the behavior of the moving body based on the surrounding information indicating the surrounding situation of the moving body,
The surrounding information includes at least one of information on the current status and future display of a signal lamp installed in front of the path of the moving body, and information on the presence of another moving body located in front of the moving body. A mobile communication device comprising one of the above . 2. The mobile communication device according to claim 1 , wherein the prediction unit acquires the peripheral information by a radio signal transmitted by a roadside communication device installed on a roadside. It further comprises detection means for detecting the behavior of the current moving body,
3. The mobile communication device according to claim 1, wherein the transmission condition adjustment unit adjusts a transmission condition of the transmission unit based on the prediction result and a current behavior of the mobile body detected by the detection unit. . The mobile communication device according to any one of claims 1 to 3 , wherein the transmission condition adjustment unit adjusts at least one of transmission power, transmission interval, back-off time, and carrier sense level. A mobile communication device mounted on a mobile object is a method of adjusting a transmission condition for transmitting a radio signal to another communication device,
Predicting the behavior of the mobile object;
Adjusting a transmission condition for transmitting a radio signal to the other communication device based on a prediction result of the predicting step,
The step of predicting the behavior of the mobile object is to predict the behavior of the mobile object based on the peripheral information indicating the surrounding situation of the mobile object,
The surrounding information includes at least one of information on the current status and future display of a signal lamp installed in front of the path of the moving body, and information on the presence of another moving body located in front of the moving body. A method comprising: A mobile communication device mounted on a mobile body is a computer program for causing a computer to execute a process for adjusting a transmission condition for transmitting a radio signal to another communication device,
Predicting the behavior of the mobile object;
A computer program for causing a computer to execute a process including a step of adjusting a transmission condition for transmitting a radio signal to the other communication device based on a prediction result of the predicting step;
The step of predicting the behavior of the mobile object is to predict the behavior of the mobile object based on the peripheral information indicating the surrounding situation of the mobile object,
The surrounding information includes at least one of information on the current status and future display of a signal lamp installed in front of the path of the moving body, and information on the presence of another moving body located in front of the moving body. A computer program containing one of these. A roadside communication device that performs wireless communication with a mobile communication device mounted on a mobile body,
Grasping means for grasping the surrounding situation of the moving body;
Position information acquisition means for acquiring position information relating to the position of the mobile communication device;
Peripheral information generating means for generating peripheral information indicating the peripheral situation;
Prediction means for predicting the behavior of the moving body based on the position information and the surrounding information;
Transmission condition determining means for determining a transmission condition for the mobile communication device to transmit a radio signal to another communication device based on a prediction result of the prediction means;
A roadside communication device comprising: a transmission unit configured to transmit transmission condition information indicating the transmission condition to the mobile communication device so that the mobile communication device adjusts a transmission condition of a radio signal.

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