JP6760137B2 - Communication device and communication terminal device - Google Patents

Description

The present invention relates to a communication device and a communication terminal device, and is mainly used for communication between vehicles or between vehicles.

It is extremely important to ensure the safety of road traffic in order to realize smooth and safe movement and logistics. In recent years, in order to prevent traffic accidents and the like, technological development and rule making for the sophistication of safe driving support systems have become active.

Safe driving support systems using communication generally prevent accidents by communicating various information including location information with automobiles, pedestrians, and road facilities. In the communication of the safe driving support system, the CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) method, which can autonomously and decentrally control the transmission timing without synchronizing each communication device, is often adopted.

However, in the CSMA / CA method, when there are a large number of devices that attempt communication, there is a problem that information conflicts occur when a plurality of devices simultaneously transmit information, and the success rate of communication decreases. In particular, if the success rate of communication in a safe driving support system decreases, it becomes impossible to exchange information closely between vehicles, pedestrians, etc., and it becomes difficult to achieve the purpose of preventing accidents. Therefore, conventionally, in a communication device, when congestion of a communication channel is detected, congestion control is performed to reduce the frequency of transmitting information to alleviate the congestion of the communication channel, thereby preventing information collision.

For example, in Patent Document 1, in a communication device used for a safe driving support system, information on the channel load factor of the own vehicle and another vehicle communicating with the own vehicle, the transmission interval of a message, and the like is acquired, and the channel of the own vehicle is obtained. A technique for controlling congestion by controlling the transmission interval at which a message is transmitted from the own vehicle based on a comparison between the load factor and the channel load factor of another vehicle is disclosed.

Japanese Unexamined Patent Publication No. 2014-241653

However, according to the technique described in Patent Document 1, since the message transmission interval is controlled without considering the vehicle speeds of the own vehicle and other vehicles, the faster the traveling speed of the vehicle, the more the vehicle becomes. The distance traveled from the transmission of the message including the position information of the vehicle to the transmission of the next message becomes large. That is, as the traveling speed of the vehicle increases, the error between the position information transmitted by the own vehicle to another vehicle and the actual position of the own vehicle after a certain period of time after the message is transmitted (hereinafter, position error) becomes larger. growing. Since this position error differs depending on the traveling speed of the vehicle, variations occur between the vehicles. Therefore, it becomes difficult for the vehicles to accurately grasp each other's positions.

Therefore, an object of the present invention is to obtain the positional error of the own device and the peripheral device by obtaining the transmission interval of the message transmitted from the own device based on the moving speed of the own device and the peripheral device and the target channel load. It is an object of the present invention to realize a communication device and a communication terminal device capable of performing congestion control by controlling the load applied to the communication channel by the own device while making it uniform.

In order to solve the above problems, the communication device (100, 200, 300) of the present invention is used.
A receiving unit (101) that receives the moving speed of the peripheral device transmitted from the peripheral device as speed information of another device, and
The own device information acquisition unit (103) that acquires the moving speed of the own device as the own device speed information, and
The target communication load information, which is an index of congestion of the target communication channel, is stored, and the total speed obtained by adding the speed information of the other device and the speed information of the own device, the target communication load information, and the transmission time per unit message are used. Based on this, the control unit obtains the own device reference distance information, which is the distance at which the message is transmitted each time the own device moves, and obtains the transmission interval of the message transmitted from the own device based on the own device reference distance information. (104, 105, 106) and
It has a transmission unit (101) for transmitting the message including the speed information of the own device based on the transmission interval.

According to the communication device of the present invention, it is possible to make the position error of the own device and the peripheral device uniform, that is, to eliminate the difference in the position error between the own device and the peripheral device, or to perform congestion control while reducing the position error to a certain degree. ..

A block diagram illustrating the configuration of the communication device according to the first to third embodiments of the present invention. A flowchart illustrating a procedure for obtaining a reference distance in the first embodiment of the present invention. The figure explaining the operation of the communication apparatus of Embodiment 1 of this invention. The figure explaining the processing content of the control part in Embodiment 1 of this invention. A block diagram illustrating a configuration of a communication device according to a fourth embodiment of the present invention. A block diagram illustrating a configuration of a communication device according to a fifth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention means the invention described in the claims, and is not limited to the following embodiments. Further, at least the words in brackets mean the words described in the claims, and are not limited to the following embodiments. Further, the configuration and method described in the dependent clause of the claims and the configuration and method of the embodiment corresponding to the configuration and method described in the dependent argument are arbitrary configurations and methods in the present invention.

(Embodiment 1)
1. 1. Configuration of Communication Device First, the configuration of the communication device 100 of the first embodiment will be described with reference to FIG. The communication device 100 includes a transmission / reception unit 101, a peripheral device information storage unit 102, an own device information acquisition unit 103, a memory 104, a congestion control unit 105, and a data generation unit 106.

The transmission / reception unit 101 of the communication device 100 receives a message transmitted from a "peripheral device" which is another communication device mounted on a pedestrian's mobile device or a vehicle via the antenna A. In the message sent from the peripheral device, the moving speed of the peripheral device, which is generally transmitted and received in the safe driving support system, is used as the speed information of the peripheral device (corresponding to "speed information of other devices"), and the position and traveling direction of the peripheral device. Is included as position direction information. Of course, this message may contain information other than the information described above.
The "peripheral device" refers to a communication device that exists within the communication range of the communication device of the present invention, which is the "own device", and can communicate with the communication device of the present invention. Further, the "own device" means the communication device of the present invention.
Then, the transmission / reception unit 101 outputs the moving speed, position, and traveling direction of the peripheral device to the peripheral device information storage unit 102.

The peripheral device information storage unit 102 stores the moving speed, position, and traveling direction of the peripheral device input from the transmission / reception unit 101. A peripheral device identification code is associated with the moving speed, position, and traveling direction of the peripheral device, and the peripheral device information storage unit 102 stores the moving speed, position, and traveling direction of the peripheral device for each identification code. be able to. Therefore, when the speed information and the position / traveling direction associated with the same identification code as the identification code already stored in the peripheral device information storage unit 102 are newly input, the peripheral device information storage unit 102 is peripheral. The moving speed, position, and traveling direction of the device may be updated with new information. Alternatively, the moving speed, position, and traveling direction of peripheral devices having the same identification code may be accumulated for a certain number or for a certain period of time. Then, the peripheral device information storage unit 102 outputs the stored information to the congestion control unit 105.

The own device information acquisition unit 103 uses GPS, a speed sensor, a gyro, etc. provided outside the communication device 100 to set the moving speed of the own device as the speed information of the own device (corresponding to "own device speed information"). The position / traveling direction of the device is acquired as position direction information and output to the congestion control unit 105 and the data generation unit 106.

The memory 104 stores target channel load information (corresponding to “target communication load information”) that is an index of congestion of the target communication channel in the communication device 100, and stores this target channel load information in the congestion control unit 105. Output. In the first embodiment, the memory 104, the congestion control unit 105, and the data generation unit 106 collectively correspond to the "control unit" of the present invention.
Here, the "target communication load information" of the present invention refers to information related to a communication load that is uniquely determined when a condition is given, for example, a target channel load and a communication device density (when the communication device is an in-vehicle device). Refers to information on vehicle density). The channel load is the ratio of the own device receiving power above a certain level within a unit time and using the communication channel, and the communication device density is the information received by the own device within the unit time. Refers to the number of peripheral devices that have transmitted.

The memory 104 may store not only one target channel load information but also a plurality of target channel load information. When the memory 104 stores a plurality of target channel load information, the congestion control unit 105 collects the plurality of target channel load information so as to satisfy the communication quality required according to the situation in which the communication device is placed. Select the appropriate one from the list. For example, when the communication device is an on-board unit and cooperative merging support using communication is carried out in the vicinity of a merging point such as an expressway, the cooperative merging support requires higher communication quality than usual. Therefore, in such a situation, in order to improve the communication quality between the merging vehicle and the receiving vehicle by alleviating the congestion of the communication channel as compared with the normal time, the congestion control unit 105 of the vehicle traveling near the merging point Select a lower target channel load than normal.

The congestion control unit 105 sets the moving speed of the peripheral device input from the peripheral device information storage unit 102, the moving speed of the own device input from the own device information acquisition unit 103, and the target channel load information input from the memory 104. Based on this, the transmission interval of the message for transmitting the message including the moving speed, position, and traveling direction of the own device from the own device is obtained. The process of obtaining the transmission interval will be described later.

Here, the transmission interval is obtained "based on" the moving speed of the peripheral device of the present invention, the moving speed of the own device, and the target channel load information, which means that the transmission interval is directly obtained using these information. The transmission interval is not limited to the above, and includes the case where the transmission interval is obtained from the numerical value obtained by the calculation using this information. For example, in the first embodiment, the distance at which the message is transmitted each time the own device moves based on the total speed obtained by adding the moving speeds of the peripheral device and the own device, the target channel load information, and the “message transmission time”. The reference distance (corresponding to "reference distance information of own device") is obtained, and the transmission interval is obtained based on this reference distance. However, based on the above information, the transmission interval may be directly obtained without obtaining the reference distance.
Further, "obtaining" the reference distance or the transmission interval of the present invention means that the result can be obtained, and includes not only the case of calculation but also the case of selecting from a table prepared in advance. The "message transmission time" means the time required for the communication device from the start of transmission to the end of transmission per unit message, for example, 128 bytes of application data are transmitted using ARIB STD-T109 and ITS FORUM RC-010. If so, it is 296 μs.

The data generation unit 106 inputs the movement speed, position, and traveling direction of the own device acquired from the own device information acquisition unit 103 to the transmission / reception unit 101 at a timing set based on the transmission interval obtained by the congestion control unit 105. ..

When the moving speed, position, and traveling direction of the own device are input from the data generation unit 106, the transmission / reception unit 101 transmits a message including the information to the peripheral device via the antenna A.

The configuration of the communication device according to the first embodiment of the present invention has been described above. Next, the procedure for obtaining the reference distance in the first embodiment will be described below.

2. 2. Procedure for obtaining the reference distance FIG. 2 is a flowchart showing a process for obtaining a reference distance in the control unit of the first embodiment. First, congestion control unit 105, the peripheral device information storage unit 102, the moving velocity _v i of the peripheral device received within the last one second peripheral device (i = 2, ···, N ) and obtains (S11) .. Congestion control unit 105 is further from the own device information obtaining unit 103 obtains the moving speed _{v 1} of the own device (S12). Here, N indicates the number of communication devices including the own device that exist within the communication range of the own device.

The congestion control unit 105 obtains a reference distance based on the total speed of the movement speeds of the peripheral devices and the own device acquired in S11 and S12, and the target channel load information and message transmission time stored in the memory 104 ( S13). The method for obtaining the reference distance will be specifically described below.

First, when the reference distance was x [m], the moving velocity _v i send a message communication device moving in [m / s] interval _ITT i [s] can be obtained based on equation (1) ..

By the way, the message transmission frequency r [Hz] per unit time of each communication device can be obtained from the reciprocal of the message transmission interval (1 / ITT _i ) of each communication device. Therefore, when there are N communication devices including the own device within the communication range of the own device, the average message transmission frequency per device is expressed as follows using the equation (1).
Here, [sigma] v _i represents the sum rate obtained by adding the moving speed of the total N number of its own device and the peripheral device.

Next, as described in paragraph 0017, the channel load indicates the ratio of the own device using the communication channel using a certain level or more of power per unit time. Therefore, the values of the channel load CBP [%] (CBP: Channel Busy Percentage) per second are the average value of the message transmission frequency r per second, the message transmission time d [ms], and the number of communication devices N. Based on, it can be obtained from the following equation (3).

Then, when the equation (2) is substituted into the equation (3), the channel load CBP is expressed as the following equation (4) using the reference distance x.

Among the parameters included in the equation (4), the moving speed v2 _{, ..., N} of the peripheral device and the message transmission time d cannot be controlled by the own device. The moving speed v ₁ of the apparatus typically need to be changed according to the placed circumstances of the own device. Therefore, it can be said that the channel load CBP depends on the value of the reference distance x. Therefore, by adjusting the value of the reference distance x, it is possible to control the value of the channel load CBP and bring it closer to the value of the target channel load. Conversely, if the target channel load has already been determined, the reference distance x is determined according to the target channel load.

Here, assuming that the target channel load is a CBP _target , the reference distance x can be obtained based on the equation (5) which is a modification of the equation (4).

According to Equation (5), congestion control unit 105, to obtain the reference distance x based on the total rate obtained by adding the moving velocity v _i of the own device and the peripheral device, the target channel load CBP _target, and the transmission time of the message d Can be done.

It is desirable that the congestion control unit 105 obtains the reference distance x at regular time intervals. In the example of FIG. 2, the congestion control unit 105 obtains the reference distance x every second, and in accordance with this, acquires the moving speed of the peripheral device received from the peripheral device information storage unit 102 within the past 1 second (S11). )are doing. However, the congestion control unit 105 may obtain the reference distance x every time of 1 second or more or 1 second or less. Alternatively, the congestion control unit 105 may obtain the reference distance x each time the own device transmits a message.

FIG. 3 specifically shows the operation of the communication device 100 when the communication device 100 of the first embodiment is an on-board unit. FIG. 3 shows a vehicle A moving at a speed of 40 km / h (11.1 m / s) (v ₁ ), a vehicle B moving at a speed of 60 km / h (16.7 m / s) (v ₂ ), and a vehicle B moving at a speed of 60 km / h (16.7 m / s) (v ₂ ). Vehicle C moving at 80 km / h (22.2 m / s) (v ₃ ) is shown, but the vehicle communication range shown in FIG. 3 includes vehicles moving at v ₁ , v ₂ , and v _3. It is assumed that there are 100 of each. Further, in this example, it is assumed that the target channel load CBP _target is 40% and the message transmission time d is 0.296 ms.

Substituting each numerical value into the equation (5), the reference distance x of the vehicle A is 3.7 m. Similarly, the reference distance x of the vehicles B and C is also 3.7 m. That is, in order to satisfy the target channel load (40%) in the communication channels of vehicles A, B, and C, it is necessary to set the reference distance to 3.7 m. The time required for the vehicles A, B, and C to move the reference distance of 3.7 m is 333 ms, 222 ms, and 167 ms, respectively, based on the equation (1). Therefore, vehicle A sends a message every 333 milliseconds, vehicle B sends a message every 222 milliseconds, and vehicle C sends a message to neighboring vehicles every 167 milliseconds.

Here, the vehicle A transmits a message including the position of the vehicle A to neighboring vehicles every time the vehicle A travels a reference distance (3.7 m). Therefore, the position between the position (a) of the vehicle A at the time when the vehicle A sends a message to the surrounding vehicles and the actual position (a') of the vehicle A after a certain period of time after transmitting the message. The error distance does not exceed the reference distance. Therefore, in the example of FIG. 3, the maximum distance of the positional error of the vehicle A, the vehicle B, and the vehicle C is uniform at 3.7 m.

3. 3. Processing at the time of message transmission Next, the processing in the control unit when the own device transmits a message to the peripheral device will be described with reference to FIG.
The congestion control unit 105 determines whether or not the message transmission timer has expired (S21). When it is determined that the message transmission timer has expired, the congestion control unit 105 and the data generation unit 106 acquire the movement speed of the own device from the own device information acquisition unit 103 (S22).

The data generation unit 106 inputs the moving speed of the own device acquired from the own device information acquisition unit 103 to the transmission / reception unit 101 together with the position and the traveling direction. Then, the transmission / reception unit 101 transmits a message including such information to the peripheral device (S23).

When the message transmission (S23) is completed, the congestion control unit 105 sets the time for transmitting the next message in the message transmission timer (S24). Specifically, congestion control unit 105 substitutes the movement speed v ₁ of the reference distance x, and the own apparatus determined based on equation (5) into equation (1), the message to be transmitted from the own device Obtain the transmission interval ITT ₁ . Then, the time for transmitting the next message is calculated based on the current time and the message transmission interval ITT ₁ , and the message transmission timer is set.

As a modification of the first embodiment, the transmission interval obtained based on the equation (1) may be discretized and used as the transmission interval of the own device. For example, the transmission interval may be divided into 10 steps every 100 ms from 100 ms to 1000 ms, and the discrete value according to the transmission interval obtained based on the equation (1) may be used as the actual message transmission interval.

As described above, according to the communication device 100 of the first embodiment, the reference distance can be obtained based on the moving speed of the own device and the peripheral device, the target channel load, and the message transmission time. Furthermore, since the peripheral devices existing within the communication range of the own device also obtain the reference distance, the reference distances of the communication devices existing within the communication range are similar, and by extension, the maximum position error of each communication device is maximized. The value can be kept within a certain level.

(Embodiment 2)
In the first embodiment, based on the equation (1), seeking the transmission interval ITT ₁ message reference distance x by dividing the movement speed v ₁ of the apparatus. Therefore, when the moving speed of the own device is extremely slow, or when the own device is stopped (that is, v ₁ = 0), the message transmission interval required by the equation (1) becomes extremely long.

Therefore, in the second embodiment, when the moving speed of the communication device is smaller than a predetermined speed, a configuration for obtaining the transmission interval based on a speed different from the moving speed of the actual communication device will be described. The detailed description of the common points with the first embodiment will be omitted, and the differences will be mainly described.

Congestion control unit 105 of the second embodiment acquires the moving speed v ₁ of the own apparatus from the self information acquisition unit 103 compares the moving speed v ₁ of the device itself and the "threshold speed" v _min. When the moving speed v ₁ of the self-device determines the threshold velocity v _min "more" is also small (v 1 _{<v min),} congestion control unit 105, instead of the moving velocity v ₁ of the actual self-device, the memory 104 The correction speed v ₁ ′ stored in the above is substituted into the equation (5) to obtain the reference distance x, and the correction speed v ₁ ′ is substituted into the equation (1) to obtain the transmission interval ITT ₁ . The compensation velocity v _{1 'has} a speed in excess of the moving velocity v ₁ of the apparatus.

Here, the "threshold speed" includes not only a specific speed but also a speed obtained by a predetermined calculation according to a condition. Further, the term "less than" the threshold velocity includes both the case where the same value as the threshold velocity to be compared is included and the case where the value is not included.

The congestion control unit 105 further outputs a control signal instructing the data generation unit 106 to transmit the correction speed v ₁ ′ in addition to the movement speed v ₁ of the own device. The data generation unit 106 that has received the control signal inputs the correction speed v ₁ ′ and the position / traveling direction of the own device to the transmission / reception unit 101. That is, the transceiver 101 of the own apparatus to a message to be transmitted to peripheral devices include correction velocity v _{1 'in} addition to the moving speed of the actual self-device. In the present embodiment, the correction speed is transmitted in addition to the movement speed of the own device that is generally transmitted and received in the safe driving support system, but the correction speed may be transmitted instead of the movement speed of the own device.

According to the second embodiment, even when the own device moves at a low speed or is stopped, it is possible to prevent the own device from transmitting an extremely long transmission interval. Furthermore, even if the moving speed of the peripheral device is extremely slow, or even if the peripheral device is stopped, the correction speed received from the peripheral device is substituted into the equation (5) for transmission based on the reference distance x obtained. By determining the interval, the own device does not mistakenly set the transmission interval abnormally short, and it is possible to prevent an increase in the load applied to the communication channel and packet collision.

Comparative As a modification of the second embodiment, the congestion control unit 105, in addition to the moving speed _{v 1} of the apparatus, the moving velocity _v i of the peripheral device (i = 2, ···, N ) and the threshold speed v _min You may. When the moving velocity v _i of the peripheral device is determined to the threshold speed v _min "more" is also small (v i _{<v min),} congestion control unit 105, instead of the moving velocity v _i of the actual peripheral equipment, determined reference distance x a correction velocity v _{i 'stored} in the memory 104 into equation (5), determine the transmission interval ITT ₁ based on the reference distance. This correction speed v _i'has a speed that exceeds the moving speed v _i of the peripheral device.
Note that the formula in place of the moving speed v ₁ of the apparatus (1), and (5) substituted into corrected velocity v _{1 '(corresponding} to the "first correction speed information"), the moving velocity v _i peripherals place of the formula corresponding to the correction speed is substituted into (5) v _{i '(} "second correction speed information)) may be better or different values even with the same value.

In the case of the modification of the second embodiment, the message transmitted by the transmission / reception unit 101 includes the actual moving speed of the own device acquired from the own device information acquisition unit 103, and the position / traveling direction of the own device.

According to the modification of the second embodiment, by substituting the correction speed into the equation (5) and determining the transmission interval based on the reference distance obtained, the movement of the own device or the peripheral device is performed as in the second embodiment. Messages can be sent at appropriate transmission intervals even when the speed is extremely slow or stopped. Further, since it is not necessary to transmit the correction speed information, the amount of information transmitted and received by the communication device can be reduced.

(Embodiment 3)
Next, the configuration of the third embodiment will be described. In the third embodiment, the communication device transmits and receives a reference distance in addition to the moving speed and the position / traveling direction, so that even if the moving speed of a specific peripheral device cannot be received, the communication device transmits based on an appropriate reference distance. The configuration for obtaining the interval will be described. Hereinafter, the differences of the first embodiment will be mainly described.

In the communication device 100 of the third embodiment, the transmission / reception unit 101 sets a reference distance of the peripheral device, which is a distance for transmitting a message each time the peripheral device moves, in addition to the moving speed, position, and traveling direction of the peripheral device. Receives a message included as reference distance information (corresponding to "reference distance information of other devices").

The transmission / reception unit 101 outputs the moving speed, position / traveling direction, and reference distance of the peripheral device received from the peripheral device to the peripheral device information storage unit 102. Similar to the first embodiment, the peripheral device information storage unit 102 stores the information input from the transmission / reception unit 101, and outputs this information to the congestion control unit 105.

The congestion control unit 105, similarly to Embodiment 1, the moving velocity _{v i} of the peripheral device, the movement speed _{v 1} of the own device, based on the target channel load CBP _target, and the transmission time of the message d, equation (5) The reference distance x ₁ of the own device is obtained from. The reference distance x ₁ of the own device is input to the data generation unit 106.

Next, the congestion control unit 105 compares the reference distance x ₁ of the own device with the reference distance x _i (i = 2, ..., N) of the peripheral device input from the peripheral device information acquisition unit 102. , The one with the maximum distance is specified as the maximum reference distance x _max . Then, the congestion control unit 105 substitutes the maximum reference distance x _max for the reference distance x ₁ of the own device into x in the equation (1), and obtains the transmission interval ITT _{1 of the} message transmitted from the own device.

The data generation unit 106 inputs the moving speed, the position / traveling direction of the own device, and the reference distance of the own device to the transmission / reception unit 101. Then, the transmission / reception unit 101 transmits a message including such information to the peripheral device.

According to the third embodiment, even if the own device cannot receive the moving speed of the peripheral device due to the influence of a shield or the like and an appropriate reference distance cannot be obtained based on the equation (5), the communication of the own device is performed. Since the reference distance of the peripheral device existing within the range can be acquired, the positional error between the own device and the peripheral device can be made uniform.

(Embodiment 4)
Next, the configuration of the fourth embodiment will be described. In the fourth embodiment, the transmission interval is obtained based on the moving speed of the own device and the peripheral device, the target channel load, and the risk of the communication device. Also in this embodiment, the differences of the first embodiment will be mainly described.

FIG. 5 shows the configuration of the communication device 200 of the fourth embodiment. In addition to the configuration of the communication device of the first embodiment, the communication device 200 further includes a risk calculation unit 107.

The transmission / reception unit 101 of the communication device 200 includes the "risk level" of the peripheral device as the risk level information of the peripheral device (corresponding to the "danger level information of other devices") in addition to the moving speed, position, and traveling direction of the peripheral device. Receive a message.
Here, the "risk level" indicates the possibility of a collision accident between the communication device of the present invention, which is the own device, and the communication device, which is another device. For example, the own device is a vehicle group. The "danger level" becomes high when the device is at the beginning or the end, or when another device having a high relative speed is approaching the own device. For example, the risk level shows 1 in normal times, and when the accident occurrence rate of the communication device is higher than normal times, the risk level shows a value larger than 1.

The transmission / reception unit 101 outputs the degree of danger to the peripheral device information storage unit 102 in addition to the moving speed, position / traveling direction of the peripheral device received from the peripheral device. Similar to the first embodiment, the peripheral device information storage unit 102 stores the information input from the transmission / reception unit 101, and outputs this information to the congestion control unit 105.

Further, the risk calculation unit 107 of the communication device 100 is the movement speed, position / traveling direction of the peripheral device input from the peripheral device information storage unit 102, and / or the own device input from the own device information acquisition unit 103. moving speed, based on the position, direction, determining the risk k ₁ of the device itself as risk information of its own apparatus (corresponding to the "self-device risk information"). For example, the risk calculation unit 107 calculates the relative speed between the own device and the peripheral device based on the moving speed of the own device and the moving speed of the peripheral device, and obtains the risk information of the own device based on the calculated relative speed. Ask. However, the risk calculation unit 107 may obtain the risk of the own device based only on the information input from the own device information acquisition unit 103.
Then, the risk calculation unit 107 outputs the risk of the own device to the congestion control unit 105 and the data generation unit 106.

The data generation unit 106 inputs the moving speed, the position / traveling direction of the own device, and the risk level of the own device to the transmission / reception unit 101. Then, the transmission / reception unit 101 transmits a message including such information to the peripheral device.

Congestion control unit 105, the moving velocity v _i of the own device and the peripheral _device, the target channel load CBP _target, in addition to the transmission time of the message d, risk k ₁ of the apparatus which is inputted from the risk calculation unit 107 _and, risk _k i of the peripheral device inputted from the peripheral device information storage unit 102 (i = 2, ···, N) based on the obtained reference distance x from the following equation (6).

The congestion control unit 105 further sets the transmission interval ITT ₁ from the following equation (7) based on the risk level k _{1 of} the own device, the moving speed v ₁ of the own device, and the reference distance x obtained by the equation (6). Ask.
Then, the congestion control unit 105 calculates the time to transmit the next message from the message transmission interval ITT ₁ obtained by the equation (7) and the current time, and sets the message transmission timer.

In the fourth embodiment, when the risk of the peripheral device received from the peripheral device includes a high risk, the value of the reference distance x obtained based on the equation (6) becomes larger than in normal times. The value of the message transmission interval ITT ₁ obtained based on the equation (7) also increases. That is, when there is a peripheral device having a high risk within the communication range of the own device, the transmission interval of the message transmitted from the own device is lengthened to reduce the load given to the communication channel by the own device. Can be done. As a result, even when a high-risk peripheral device sends a message densely, the channel load within the communication range is maintained near the target channel load, so that the risk level does not increase without increasing packet collision. There is a high possibility that messages from high peripheral devices can be received closely.

Further, when the risk degree k ₁ of the own device is high, the value of the message transmission interval ITT ₁ obtained based on the equation (7) becomes small. That is, when the risk of the own device is high, the own device can send a message closely to the peripheral device, and the possibility of collision with the peripheral device can be reduced.

As a modification of the fourth embodiment, the congestion control unit 105 is configured to adjust the speed information v ₁ of the own apparatus based on the risk k ₁ obtained at risk calculation unit 107, to the data generation unit 106, A control signal instructing the transmission / reception unit 101 to output the adjusted movement speed instead of the actual movement speed of the own device may be output. In this modification, the transmission / reception unit 101 receives a message including the moving speed of the peripheral device adjusted based on the risk level of the peripheral device and the position / traveling direction of the peripheral device, and is based on the risk level of the own device. Sends a message including the adjusted movement speed of the own device and the position / traveling direction of the own device. Therefore, since it is not necessary for the own device to transmit and receive both the moving speed and the degree of danger, it is possible to reduce the amount of information to be transmitted and received.

(Embodiment 5)
Next, the configuration of the fifth embodiment will be described. In the fifth embodiment, the communication device transmits / receives reception failure rate information of a message indicating the quality of the communication channel in addition to the moving speed, the position / traveling direction, so that the reference distance is taken into consideration in consideration of the communication quality of the communication device. And the configuration for obtaining the transmission interval will be described. Hereinafter, the differences from the first embodiment will be mainly described.

FIG. 6 shows the configuration of the communication device 300 of the fifth embodiment. In addition to the configuration of the communication device of the first embodiment, the communication device 300 further includes a communication quality measuring unit 108.

The transmission / reception unit 101 of the communication device 300 sets the reception failure rate of a message indicating the moving speed, position / traveling direction of the peripheral device, and the quality of the communication channel of the peripheral device as the reception failure rate information of the peripheral device (“other device communication quality information”). Corresponds to)). The "communication quality information" is information indicating the quality of the communication channel of the communication device of the present invention, and refers to, for example, information calculated from a packet arrival rate or a packet error rate.

The transmission / reception unit 101 outputs the moving speed, position / traveling direction, and reception failure rate of the peripheral device received from the peripheral device to the peripheral device information storage unit 102. Similar to the first embodiment, the peripheral device information storage unit 102 stores the information input from the transmission / reception unit 101, and outputs this information to the congestion control unit 105.

The communication quality measuring unit 108 describes, for example, the number of packets received by the own device from a peripheral device existing within 100 m around the own device and the number of packets received in the packet based on the packet reception status for the past 5 seconds every second. Based on the number of packets estimated to have been actually transmitted by the peripheral device from the packet number, the packet error rate is calculated for each peripheral device, and the average of them is used to indicate the quality of the communication channel of the own device. Received as reception failure rate information (corresponding to "own device communication quality information") π ₁ . Then, the communication quality measurement unit 108 outputs the reception failure rate π ₁ of its own device to the congestion control unit 105 and the data generation unit 106.

The data generation unit 106 inputs the reception failure rate of the own device to the transmission / reception unit 101 together with the moving speed, the position / traveling direction of the own device. Then, the transmission / reception unit 101 transmits a message including such information to the peripheral device.

Congestion control unit 105, the moving velocity v _i of the own device and the peripheral _device, the target channel load CBP _target, in addition to the transmission time d of the message, reception failure rate [pi ₁ of the apparatus which is inputted from the communication quality measurement unit 108, Based on the reception failure rate π _i (i = 2, ..., N) of the peripheral device input from the peripheral device information storage unit 102, the reference distance x is obtained from the following equation (8).

The congestion control unit 105 further sets the transmission interval ITT ₁ from the following equation (9) based on the reception failure rate π _{1 of} the own device, the moving speed v ₁ of the own device, and the reference distance x obtained by the equation (8). Ask for.
Then, the congestion control unit 105 calculates the time to transmit the next message from the message transmission interval ITT ₁ obtained by the equation (9) and the current time, and sets the message transmission timer.

In the fifth embodiment, when the quality of the communication channel of the peripheral device is poor, that is, when the reception failure rate of the peripheral device received from the peripheral device includes a high reception failure rate, based on the equation (8). The value of the required reference distance x is larger than that when the reception failure rate is low, and the value of the message transmission interval ITT ₁ obtained based on the equation (9) is also large. That is, if there is a peripheral device with poor quality of the communication channel within the communication range of the own device, the transmission interval of the message transmitted from the own device is lengthened to increase the load on the communication channel within the communication range of the own device. Can be reduced. As a result, the channel load within the communication range can be kept near the target channel load even when the message transmission frequency is increased because the peripheral device having poor quality of the communication channel notifies the existence.

Further, when the quality of the communication channel of the own device is poor, that is, when the reception failure rate π ₁ of the own device is high, the value of the message transmission interval ITT ₁ obtained based on the equation (9) becomes small. That is, when the reception failure rate of the own device is high, the own device sends a message closely to the peripheral device, increasing the possibility that the peripheral device can receive the message of the own device, and collides with the peripheral device. The possibility of doing so can be reduced.

As a modified example 1 of embodiment 5, congestion control unit 105 is configured to adjust the movement speed v ₁ of the own apparatus based on the reception failure rate [pi ₁ acquired by the communication quality measuring unit 108, to the data generation unit 106 Alternatively, a control signal instructing the transmission / reception unit 101 to output the adjusted movement speed instead of the actual movement speed of the own device may be output. In this modification 1, the transmission / reception unit 101 receives a message including the moving speed of the peripheral device adjusted based on the reception failure rate of the peripheral device and the position / traveling direction of the peripheral device, and the reception failure rate of the own device. A message including the movement speed of the own device adjusted based on the above and the position / traveling direction of the own device is transmitted. Therefore, since it is not necessary for the own device to transmit and receive both the moving speed and the reception failure rate, the amount of information to be transmitted and received can be reduced.

As a modification 2 of the fifth embodiment, the congestion control unit 105 compares the reception failure rate π ₁ of its own device acquired by the communication quality measurement unit 108 with the threshold reception failure rate π _min (corresponding to “threshold communication quality”). You may. If it is determined that the reception failure rate π ₁ is higher than the threshold reception failure rate π _min “more” (π ₁ > π _min ) (that is, the communication quality of the own device is lower than the threshold communication quality), the congestion control unit In 105, instead of the reception failure rate π ₁ , the correction reception failure rate π ₁ ′ stored in the memory 104 is substituted into the equation (8) to obtain the reference distance x, and the correction reception failure rate π ₁ ′ is obtained. Substitute in equation (9) to obtain the transmission interval ITT ₁ . The corrected reception failure rate π ₁ ′ has a value lower than the reception failure rate π ₁ of the own device (that is, a value of the communication quality “exceeding the communication quality” of the own device). Further, the correction reception failure rate π ₁ ′ may be the same value as the threshold reception failure rate π _min , or may be a different value.
Here, the reception failure rate is higher than the threshold reception failure rate "" (that is, "the communication quality is lower than the threshold communication quality") when the same value as the threshold reception failure rate to be compared is included. Both are included if not included.

In the second modification, the congestion controlling unit 105 further to the data generation unit 106, the corrected reception failure rate [pi _{1 'outputs} a control signal for instructing to set as the reception failure rate [pi ₁ of the apparatus. The data generation unit 106 that has received the control signal inputs the correction reception failure rate π ₁ ′, the moving speed of the own device, and the position / traveling direction to the transmission / reception unit 101. Then, the transmission / reception unit 101 transmits a message including the correction reception failure rate π ₁ ′ in addition to the moving speed, position / traveling direction of the own device to the peripheral device.

In the second modification as well, as in the first modification, the congestion control unit 105 compares the reception failure rate of the own device with the threshold reception failure rate, and the reception failure rate of the own device is higher than the threshold reception failure rate. The movement speed may be adjusted based on the correction reception failure rate.

As another modification 3 of the fifth embodiment, the congestion control unit 105 sets the reception failure rate π _i (i = 2, ..., N) of the peripheral device as a threshold value in addition to the reception failure rate π ₁ of the own device. It may be compared with the reception failure rate π _min . If the reception failure rate [pi _i peripheral device is determined to be higher than the threshold reception failure rate _{π min (π i> π min} ), congestion control unit 105, instead of the reception failure rate [pi _i peripherals, memory 104 Substitute the correction reception failure rate π _i ′ stored in the above into equation (8) to obtain the reference distance. Similar to the second modification, the corrected reception failure rate π _i ′ has a value lower than the reception failure rate π _i of the own device.
Note that the corrected reception failure rate π ₁ ′ (corresponding to the “first corrected communication quality information”) and the peripheral device are substituted into the equations (8) and (9) instead of the actual reception failure rate π ₁ of the own device. The corrected reception failure rate π _i ′ (corresponding to the “second corrected communication quality information)) that is substituted into the equation (8) instead of the reception failure rate π _i of the above may be the same value or different values. You may.

In the case of the modification 3, the transmission / reception unit 101 includes the actual reception failure rate π ₁ of the own device acquired by the communication quality measurement unit 108 in addition to the moving speed of the own device and the position / traveling direction of the own device. Send a message to a peripheral device.

(Summary)
The features of the communication device according to the embodiment of the present invention have been described above.

Although the embodiments 2 to 5 are described as separate embodiments, the configurations of the embodiments 2 to 5 may be combined with each other. For example, the own device of the present invention transmits / receives one or more information of the risk level, the reception failure rate, and the reference distance in addition to the moving speed and the position / traveling direction, and sets the transmission interval based on these information. You may ask.

Further, in each of the second to fifth embodiments, the reference distance is obtained based on the moving speed of the own device, the moving speed of the peripheral device, the target channel load information, and the transmission time of the message, and the transmission interval is set based on the reference distance. An example is shown. However, as described in paragraph 0020, also in the second to fifth embodiments, the transmission interval may be directly obtained based on the moving speed of the own device, the moving speed of the peripheral device, and the target channel load information, and is not necessarily a reference. It is not necessary to find the distance.

Although the above-mentioned communication device does not include an antenna connected to the transmission / reception unit of the communication device, an antenna may be connected to the communication device to form a communication terminal device. In addition, the communication terminal device may be provided with an amplifier and various filters.

Examples of communication devices 100, 200, and 300 as an on-board unit include semiconductors, electronic circuits, modules, and ECUs (electronic control units). Further, examples of the communication terminal device include a car navigation system, a smartphone, a personal computer, and a mobile information terminal, in addition to a state in which an ECU is mounted on an automobile and connected to an antenna or the like.

Further, in the explanation of the configuration of each embodiment, the processing of the control unit has been described focusing on the procedure for obtaining the reference distance and the transmission interval, but it goes without saying that each of them can be grasped as a feature of the method. That is, the present specification also discloses the present invention as an invention of a method.
In addition, the present invention can be realized not only by the above-mentioned dedicated hardware, but also as a combination of a program recorded on a recording medium such as a memory or a hard disk, and a microcomputer having a dedicated or general-purpose CPU and a memory for executing the program. Can also be realized. The program can also be provided from the server to a dedicated hardware or microcomputer via a communication line without going through a recording medium. This ensures that you always have the latest features through program upgrades.

The communication device and communication terminal device according to the present invention are mainly used for communication between automobiles (communication between vehicles), but may be used for communication between automobiles and pedestrians (communication between pedestrians). Furthermore, the present invention is not limited to these uses.

100 Communication device, 101 Transmission / reception unit, 102 Peripheral device information storage unit, 103 Own device information acquisition unit, 104 Memory, 105 Congestion control unit, 106 Data generation unit, 107 Risk calculation unit, 108 Communication quality measurement unit

Claims (13)

A receiving unit (101) that receives the moving speed of the peripheral device transmitted from the peripheral device as speed information of another device, and
The own device information acquisition unit (103) that acquires the moving speed of the own device as the own device speed information, and
The target communication load information, which is an index of congestion of the target communication channel, is stored, and the total speed obtained by adding the speed information of the other device and the speed information of the own device, the target communication load information, and the transmission time per unit message are used. Based on this, the control unit obtains the own device reference distance information, which is the distance at which the message is transmitted each time the own device moves, and obtains the transmission interval of the message transmitted from the own device based on the own device reference distance information. (104, 105, 106) and
A transmission unit (101) that transmits the message including the speed information of the own device based on the transmission interval, and
(100, 200, 300). The control unit further compares the own device speed information with the threshold speed, and when the moving speed indicated by the own device speed information is smaller than the threshold speed, exceeds the moving speed indicated by the own device speed information. Using the correction speed information as the speed information of the own device, the transmission interval is obtained.
The transmission unit transmits the correction speed information as the own device speed information.
The communication device according to claim 1. The control unit further compares the speed information of the own device and the speed information of the other device with the threshold speed, respectively.
When the moving speed indicated by the own device speed information is smaller than the threshold speed, the first correction speed information exceeding the moving speed indicated by the own device speed information is used as the own device speed information and / or.
When the moving speed indicated by the other device speed information is smaller than the threshold speed, the transmission interval is obtained by using the second correction speed information exceeding the moving speed indicated by the other device speed information as the other device speed information. ,
The communication device according to claim 1. The receiving unit further receives other device reference distance information, which is the distance at which a message is transmitted each time the peripheral device moves.
The control unit further compares the own device reference distance information and the other device reference distance information, and sets the maximum distance among the own device reference distance information and the other device reference distance information as the maximum reference distance information. Identify and obtain the transmission interval based on the maximum reference distance information instead of the own device reference distance information.
The transmission unit further transmits the own device reference distance information in the message.
The communication device according to claim 1. The communication device further has a risk calculation unit (107) for acquiring the risk of the own device as own device risk information.
The receiving unit further receives the risk level of the peripheral device as risk level information of another device, and receives the risk level.
The control unit obtains the transmission interval based on the own device risk information and the other device risk information in addition to the other device speed information, the own device speed information, and the target communication load information.
The transmitter further transmits the own device risk information in the message.
The communication device (200) according to claim 1. The communication device further has a risk calculation unit (107) for acquiring the risk of the own device as own device risk information.
The control unit further adjusts the speed information of the own device based on the risk information of the own device.
The transmitter transmits the adjusted speed information of the own device.
The communication device (200) according to claim 1. The communication device further has a communication quality measuring unit (108) for acquiring the communication quality information of the own device indicating the quality of the communication channel of the own device.
The receiving unit further receives communication quality information of another device indicating the quality of the communication channel of the peripheral device.
The control unit obtains the transmission interval based on the own device communication quality information and the other device communication quality information in addition to the other device speed information, the own device speed information, and the target communication load information.
The transmitter further transmits the communication quality information of the own device in the message.
The communication device (300) according to claim 1. The communication device further has a communication quality measuring unit (108) for acquiring the communication quality information of the own device indicating the quality of the communication channel of the own device.
The control unit further adjusts the speed information of the own device based on the communication quality information of the own device.
The transmitter transmits the adjusted speed information of the own device.
The communication device (300) according to claim 1. The control unit further compares the communication quality information of the own device with the threshold communication quality, and when the communication quality indicated by the communication quality information of the own device is lower than the threshold communication quality, the communication quality information of the own device indicates. The corrected communication quality information exceeding the communication quality is used as the own device communication quality information.
The communication device according to claim 7 or 8. The control unit further compares the communication quality information of the own device and the communication quality information of the other device with the threshold communication quality, respectively.
When the communication quality indicated by the own device communication quality information is lower than the threshold communication quality, the first corrected communication quality information exceeding the communication quality indicated by the own device communication quality information is used as the own device communication quality information. And / or
When the communication quality indicated by the other device communication quality information is lower than the threshold communication quality, the second corrected communication quality information exceeding the communication quality indicated by the other device communication quality information is used as the other device communication quality information. Find the transmission interval,
The communication device according to claim 7. A receiving unit (101) that receives the moving speed of the peripheral device transmitted from the peripheral device as speed information of another device, and
The own device information acquisition unit (103) that acquires the moving speed of the own device as the own device speed information, and
The target communication load information, which is an index of congestion of the target communication channel, is stored, and the total speed obtained by adding the speed information of the other device and the speed information of the own device, the target communication load information, and the transmission time per unit message are used. Based on this, the control unit obtains the own device reference distance information, which is the distance at which the message is transmitted each time the own device moves, and obtains the transmission interval of the message transmitted from the own device based on the own device reference distance information. (104, 105, 106) and
A transmission unit (101) that transmits the message including the speed information of the own device based on the transmission interval, and
An antenna (A) connected to the receiving unit and the transmitting unit,
Communication terminal device having. It is a communication method executed by a communication device.
A step of receiving the moving speed of the peripheral device transmitted from the peripheral device as speed information of another device, and
A step of acquiring the moving speed of the communication device as own device speed information, and
The target communication load information, which is an index of congestion of the target communication channel, is stored, and the total speed obtained by adding the speed information of the other device and the speed information of the own device, the target communication load information, and the transmission time per unit message are used. Based on the step of obtaining the own device reference distance information which is the distance for transmitting a message each time the communication device moves, and obtaining the transmission interval of the message transmitted from the communication device based on the own device reference distance information. ,
A step of transmitting the message including the own device speed information based on the transmission interval, and
Communication methods, including. A communication program executed by a communication device.
A step of receiving the moving speed of the peripheral device transmitted from the peripheral device as speed information of another device, and
A step of acquiring the moving speed of the communication device as own device speed information, and
The target communication load information, which is an index of congestion of the target communication channel, is stored, and the total speed obtained by adding the speed information of the other device and the speed information of the own device, the target communication load information, and the transmission time per unit message are used. Based on the step of obtaining the own device reference distance information which is the distance for transmitting a message each time the communication device moves, and obtaining the transmission interval of the message transmitted from the communication device based on the own device reference distance information. ,
A step of transmitting the message including the own device speed information based on the transmission interval, and
A communication program that includes.