JP2018139347A - Communication device and communication terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deal with the situation in which the communication quantity of random transmissions can be degraded since the opportunities of conducting the random transmissions are limited if a large number of intervals for transmitting regular transmissions are set in the system which conducts the regular transmissions and the random transmissions.SOLUTION: A communication device 100 includes: a reception unit 101 for receiving reception data sent from a peripheral device; communication quality detection units 102 and 103 for obtaining a communication quality estimation value on the basis of the reception data; control units 104 and 105 for switching between a reserved transmission performed at a first transmission interval which the peripheral device was notified of and a random transmission performed at a second transmission interval which is different from the first transmission interval, on the basis of the communication quality estimation value and the communication quality target value; and a transmission unit 110 for sending transmission data, using a reversed transmission or a random transmission switched by the control unit.SELECTED DRAWING: Figure 1

Description

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

  In order to realize transportation and logistics smoothly and safely, it is extremely important to secure road traffic. In recent years, in order to prevent traffic accidents and the like, technological development and rule making for the advancement of safe driving support systems have become active.

  In general, a safe driving support system prevents accidents by communicating various information including positional information with automobiles, pedestrians, and road equipment. In the communication of the safe driving support system, a CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) system that can autonomously control transmission timing without synchronizing each communication device is often used.

  However, in the CSMA / CA system, when there are a large number of devices attempting communication, a plurality of devices transmit information at the same time, which causes information to collide with each other, resulting in a decrease in communication success rate. In particular, if the success rate of communication decreases in the safe driving support system, information cannot be exchanged closely between vehicles, between pedestrians, etc., and it becomes difficult to achieve the purpose of preventing accidents.

  Here, in the 700 MHz band intelligent transportation system, a roadside device that transmits data with high quality requirements performs regular transmission, and other vehicle-mounted devices perform random transmission according to the CSMA / CA method. And in patent document 1, the transmission period which is not utilized from the information of the transmission period received from the other roadside machine so that the transmission period of the roadside machine which performs regular transmission and the transmission period of the other roadside machine may not overlap. An apparatus is disclosed that can automatically set the transmission period by determining the transmission period and selecting the transmission period for transmission from the vacant transmission period.

JP 2012-186707 A

However, if a large number of periodic transmission periods are set, the chance of random transmission is limited, and the communication quality of random transmission may deteriorate. In particular, when a transmission period for regular transmission is set in a time zone in which communication apparatuses for random transmission are concentrated, the influence becomes large.
Further, in the above 700 MHz band intelligent transportation system, roadside equipment uses periodic transmission and onboard equipment uses random transmission, so onboard equipment cannot send data with high quality requirements by methods other than random transmission. There was a problem that the transmission method according to the request could not be selected.

  An object of the present invention is to realize a communication device and a communication terminal device that can reliably transmit and receive data with high quality requirements and can suppress a decrease in the success rate of communication.

In order to solve the above problem, a communication device (100) of the present invention includes:
A receiving unit (101) for receiving received data transmitted from the peripheral device;
A communication quality detection unit (102, 103) for obtaining a communication quality estimate based on the received data;
Based on the communication quality estimation value and the communication quality target value, the reserved transmission transmitted in the first transmission period notified to the peripheral device and the random transmission in the second transmission period other than the first transmission period A control unit (104, 105) for switching between random transmission,
A transmission unit (110) for transmitting transmission data using the reserved transmission or the random transmission switched by the control unit;
Is provided.

  According to the communication device and the like of the present invention, it is possible to reliably transmit and receive data with high quality requirements, and to suppress a decrease in the success rate of communication.

The block diagram explaining the structure of the communication apparatus of Embodiment 1 of this invention. The flowchart explaining operation | movement of the communication quality observation part of the communication apparatus of Embodiment 1 of this invention. Explanatory drawing of the communication quality information table of the communication apparatus of Embodiment 1 of this invention. The flowchart explaining operation | movement of the transmission method switching part of the communication apparatus of Embodiment 1 of this invention. Explanatory drawing explaining the transmission period of reservation transmission and random transmission of this invention The flowchart explaining operation | movement of the transmission period selection part of the communication apparatus of Embodiment 1 of this invention. The block diagram explaining the structure of the communication apparatus of Embodiment 2 of this invention. The flowchart explaining operation | movement of the traffic observation part of the communication apparatus of Embodiment 2 of this invention. Explanatory drawing of the transmission period information table (communication amount information) of the communication apparatus of Embodiment 2 of this invention. The flowchart explaining operation | movement of the transmission period selection part of the communication apparatus of Embodiment 2 of this invention. The flowchart explaining operation | movement of the traffic observation part of the communication apparatus of Embodiment 2 of this invention. Explanatory drawing of the transmission period information table (communication amount information) of the communication apparatus of Embodiment 2 of this invention. Packet configuration diagram for explaining information included in received data and transmitted data packets in the first and second embodiments Explanatory drawing explaining the application example of Embodiment 1,2.

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

(Embodiment 1)

1. Configuration of Communication Device First, the configuration of the communication device according to the first embodiment of the present invention will be described with reference to FIG.

The communication device 100, which is the “own device” of the present invention, is a “peripheral device” that is mounted on the host vehicle or possessed by the pedestrian, and is also mounted on the surrounding vehicle or possessed by the surrounding pedestrian. Data is transmitted / received as a message to / from other communication devices. In the present embodiment, an example of an in-vehicle device mounted on a vehicle (the host vehicle and the surrounding vehicle) will be described with respect to the host device and the peripheral device. In other words, vehicle-to-vehicle communication is normally performed by random transmission between each vehicle-mounted device, and vehicle-to-vehicle communication is performed by reserved transmission under specific conditions.
Here, the “self apparatus” of the present invention refers to the communication apparatus of the present invention.
In addition, the “peripheral device” of the present invention refers to a communication device that exists within the communication distance range of its own device.

  The communication apparatus 100 includes a reception unit 101, a communication quality observation unit 102, a communication quality information table 103, a transmission method switching unit 104, a communication quality target value table 105, a transmission period information table 106, a transmission period selection unit 107, and a message generation unit 108. A transmission timing determination unit 109 and a transmission unit 110.

The receiving unit 101 receives a message having information on the position, speed, and traveling direction of the surrounding vehicle transmitted from the surrounding vehicle equipped with the “peripheral device” as reception data in a packet via the antenna A.
The position information of the surrounding vehicles received by the receiving unit 101 is used for controlling the host vehicle by the vehicle control device via the driving support device, or a display device such as a car navigation system as an HMI (Human Machine Interface). And audio playback device provide audiovisual information to the driver.

The communication quality observation unit 102 obtains a “communication quality estimated value” based on “based on reception data” input from the reception unit 101. A specific example of how to obtain the communication quality estimated value will be described later with reference to FIG.
Here, “based on received data” of the present invention includes not only the case based on the content of the received data but also the case based on the reception status of the received data.
Further, the “communication quality estimated value” of the present invention refers to a value indicating the communication quality of the communication channel, and examples thereof include a packet arrival rate, a received power value, and an S / N ratio.

The communication quality information table 103 stores the communication quality estimated value obtained by the communication quality observation unit 102 as communication quality information. In addition, the communication quality information table 103 may be received directly by the reception unit 101 from the communication quality information transmitted from another communication apparatus and stored directly.
The communication quality observation unit 102 and the communication quality information table 103 constitute the “communication quality detection unit” of the present invention.

The transmission method switching unit 104 is based on the communication quality estimation value stored in the communication quality information table 103 and the “communication quality target value” stored in the communication quality target value table 105, and is a transmission method reservation. “Switch” between transmission and random transmission. The reserved transmission is a transmission method for transmitting in the first transmission period notified to the peripheral device, and the random transmission is a transmission method for transmitting “randomly” in the second transmission period other than the first transmission period. is there. The specific operation of the communication method switching unit 104 will be described later with reference to FIG.
The transmission method switching unit 104 and the communication quality target value table 105 constitute a “control unit” of the present invention.
Here, the “communication quality target value” of the present invention refers to a value representing the communication quality target of the communication channel. For example, a desired packet arrival rate, a desired received power value, a desired S / N ratio, etc. Can be mentioned. In addition to a fixed value, a value whose value is uniquely determined by giving a condition is also included.
Further, “based on” of the present invention refers to comparing the communication quality estimated value with the communication quality target value, comparing at least one with weighting, or comparing the communication quality estimated value and the communication quality target value. This includes a case where some kind of calculation is performed on and the determination is made based on the calculation result.
Further, the term “randomly” of the present invention means that the transmission start time is distributed as a whole based on a certain rule, not based on the random number, in addition to the case where the transmission start time is distributed based on the random number. Such cases are also included.
The “switching” of the present invention only needs to determine as a result which transmission method is used for transmission. For example, as a determination process, one transmission method is selected from a plurality of transmission methods. Including cases.

  The transmission period information table 106 stores transmission period information included in the reception data. In this embodiment, the transmission period length and the number of transfers correspond to the transmission period information. Details of the transmission period information will be described later with reference to FIG.

  The transmission period selection unit 107 refers to the transmission period information table 106 and selects a reserved transmission candidate period (corresponding to the “first transmission period” in the present invention) used at the time of reserved transmission. The specific operation of the transmission period selection unit 107 will be described later with reference to FIGS.

  The message generation unit 108 acquires the position, speed, and traveling direction of the vehicle from the vehicle position information generation device (GPS) connected to the communication device 100 and the vehicle behavior acquisition unit (vehicle speed sensor and gyro), respectively. Then, a message is generated and packetized by adding a header. The message generator 108 may be connected to a map database and receive supply of road map information. In addition, the message generation unit 108 also transmits the communication quality information output from the communication quality information table 103 and / or the transmission period information output from the transmission period information table 106 to the peripheral device. You may share. The generated packet is output to the transmission unit 110.

  The transmission timing determination unit 109 determines the transmission timing of transmission data based on the transmission method switching instruction from the transmission method switching unit 104 and the reserved transmission candidate period selected by the transmission period selection unit 107. That is, at the time of reserved transmission, the transmission unit 110 is instructed to transmit a message during the selected reserved transmission candidate period, and at the time of random transmission, the transmission unit 110 is transmitted at random during a period other than the selected reserved transmission candidate period. To instruct.

  Based on an instruction from the transmission timing determination unit 109, the transmission unit 110 uses reservation transmission or random transmission for the surrounding vehicle via the antenna A using the packet storing the message generated by the message generation unit 108 as transmission data. To send.

2. Communication Quality Detection Next, the operation of the communication quality observation unit 102 of the communication device 100 of this embodiment will be described.
The communication quality observation unit 102 obtains the data by measuring the “reception quality” of the reception data randomly transmitted from the peripheral device. A specific example will be described below with reference to FIG.
Here, the “reception quality” of the present invention includes, for example, a packet arrival rate, a received power value, and an S / N ratio.

  When receiving a packet randomly transmitted from the peripheral device, the communication quality observation unit 102 calculates an expected value of the number of received packets within a predetermined observation period (S21). The expected value of the number of received packets can be obtained, for example, by observing the sequence number of the received packet and calculating the difference between the sequence numbers of the first and last received packets within a predetermined observation period.

  Also, the communication quality observation unit 102 calculates the actual number of received packets within a predetermined observation period (S22).

Then, as described below, an estimated value of the packet arrival rate (corresponding to “communication quality estimated value” or “reception quality” of the present invention) is obtained by dividing the number of receptions by the expected value (S23).
Estimated value of packet arrival rate = number of received packets / expected number of received packets

  Finally, the estimated value of the packet arrival rate is output as communication quality information to the communication quality information table 103, and the communication quality information table 103 stores the communication quality information (S24).

  The “communication quality estimated value” may be shared with peripheral devices. That is, the “communication quality estimation value” obtained by the communication quality observation unit 102 of the own device is transmitted to the message generation unit 108 as a transmission data included in the packet, and the “communication quality estimation value” obtained by the peripheral device is transmitted. A packet including “value” may be received as reception data by the receiving unit 101 and stored in the communication quality information table 103. In this case, the “communication quality estimated value” observed by the host vehicle and the “communication quality estimated value” observed by the other vehicle are stored in the communication quality information table 103. The packet configuration in this case will be described later with reference to FIG.

  FIG. 3 shows data stored in the communication quality information table 103. In the communication quality information table 103, an estimated value of the packet arrival rate obtained by the own device (for example, 1.0 for the own vehicle) is written. When the “communication quality estimated value” is shared with peripheral devices, the estimated packet arrival rate obtained by the peripheral device acquired from the received data (for example, 0.98 for the vehicle 1 and 0.00 for the vehicle 2). 85) is written.

3. Switching between Reserved Transmission and Random Transmission Next, the operation of the transmission method switching unit 104 of the communication apparatus 100 according to the present embodiment will be described with reference to the flowchart of FIG. FIG. 4 describes transmission method switching processing performed by the communication method switching unit 104.

  The communication method switching unit 104 acquires “communication quality target value” from the communication quality target value table 105 (S41). Examples of the communication quality target value include a desired packet arrival rate, a desired received power value, and a desired S / N ratio. The communication quality target value may always be a constant value, but, for example, in conjunction with map data, the vicinity of intersections and intersections on the expressway is high, the other places are low, the time zone during rush hours is high, It can be set individually according to the position and time, such as lowering other times. Alternatively, a target value is specified when receiving transmission data from the driving support device, for example, at the time of joining or receiving, at the time of lane change, emergency stop (accident, breakdown, accident of another vehicle, stop due to breakdown or falling object), etc. The communication quality target value is set higher than that during normal driving.

Next, the communication method switching unit 104 acquires the type of communication to be reserved and transmitted (S42). For example, if a specific destination is specified when receiving transmission data from the driving support device, it is determined that the transmission is unicast.
When the reserved transmission is executed by broadcast without specifying the other party, the estimated value of the packet arrival rate, which is the “communication quality estimated value”, is calculated based on the received data from all the peripheral devices, for example, using the steps of FIG. (S43).

On the other hand, when the reserved transmission is executed by unicast for specifying the other party, the packet arrival rate is estimated as the “communication quality estimated value” using, for example, the steps in FIG. 2 based on the received data received from the specific peripheral device. A value is calculated (S44).
Instead of this, an estimated value of the packet arrival rate, which is the “communication quality estimated value” included in the received data received from the specific partner may be acquired (S44). In this case, it is assumed that the estimated communication quality value is shared with peripheral devices.

  Then, the transmission method switching unit 104 compares the desired packet arrival rate that is the “communication quality target value” acquired in S41 and the estimated value of the packet arrival rate that is the “communication quality estimated value” acquired in S43 or S44. (S45). If the estimated value of the packet arrival rate is smaller than the desired packet arrival rate, it is determined that the communication quality expected by the communication quality target value cannot be achieved by random transmission, and reserved transmission start processing is executed (S46). The reservation transmission start process will be described later with reference to FIG. If the estimated value of the packet arrival rate is equal to or higher than the desired packet arrival rate, the current transmission operation is confirmed (S47). If the transmission method is random transmission, the communication quality target value assumed by the random transmission is the communication quality target value. The random transmission is continued as it is, and if the reserved transmission is in progress, the reserved transmission is terminated (S48).

  FIG. 5 shows an example of a transmission period used for reserved transmission and a transmission period used for random transmission. In the present embodiment, 16 reserved transmission candidate periods are prepared within a period of 100 ms, which is a “certain period”. Of the reserved transmission candidate periods, the reserved transmission candidate period (corresponding to the “first transmission period” of the present invention) selected by the transmission period selection unit 107 is used for reserved transmission, and the selected reserved transmission candidate period is selected. The transmission data is transmitted within. Further, a reserved transmission candidate period other than the selected period and a period other than the reserved transmission candidate period (corresponding to the “second transmission period” of the present invention) are used for random transmission, and transmission data is transmitted.

  In FIG. 5, the reservation transmission candidate period may be preferentially used by the roadside device, and the vacant period may be used for reservation transmission of the vehicle-mounted device. And the reservation transmission candidate period which is not used for the roadside machine or the reservation transmission of the vehicle-mounted device may be used for the random transmission of the vehicle-mounted device.

4). Reservation Transmission Start Process An example of the reservation transmission start process of the transmission period selection unit 107 of the communication apparatus 100 according to the present embodiment will be described with reference to FIG.

  The transmission period selection unit 107 acquires an unused reserved transmission candidate period from the transmission period information table 106 (S61). For example, referring to the transmission period length of the transmission period information stored in the transmission period information table 106, it can be seen that the reserved transmission candidate period is not used if the transmission period length is zero.

  Then, the transmission period selection unit 107 selects one of the unused reserved transmission candidate periods, and selects the selected reserved transmission candidate period (corresponding to the “first transmission period” of the present invention) as a transmission timing determination unit. 109 is instructed. The selection method may select an unused reserved transmission candidate period that is closest in time after the current time, or may randomly select from a plurality of unused reserved transmission candidate periods.

  Instead of S61 and S62, a reserved transmission candidate period used for reserved transmission may be randomly selected from a plurality of reserved transmission candidate periods.

  As described above, according to Embodiment 1 of the present invention, it is possible to switch to reserved transmission only when it is predicted that the communication quality expected by the communication quality target value cannot be achieved by random transmission. Thereby, quality degradation of random transmission can be suppressed.

(Embodiment 2)

1. Configuration of Communication Device Next, the configuration of the communication device according to the second embodiment of the present invention will be described with reference to FIG. In addition, the same structure as Embodiment 1 gives the same figure number, and Embodiment 1 is used for description. Also in the present embodiment, the self-device and the peripheral device will be described as an example of the vehicle-mounted device mounted on the vehicle (the host vehicle and the peripheral vehicle), but the present invention is not limited to this.

  The communication apparatus 200 includes a receiving unit 101, a communication quality observation unit 102, a communication quality information table 103, a communication method switching unit 104, a communication quality target value table 105, a message generation unit 108, and a transmission timing determination unit, as in the first embodiment. 109, a transmission unit 110, and a communication amount observation unit 201, a transmission period information table 202, and a transmission period selection unit 203 unique to the second embodiment.

The traffic monitoring unit 201 calculates “communication volume” based on “based on received data” input from the receiving unit 101 and randomly transmitted from the peripheral device. A specific example of how to determine the communication amount will be described later with reference to FIGS.
Here, “based on received data” of the present invention includes not only the case based on the reception status of the received data but also the case based on the contents of the received data.
In addition, the “communication amount” of the present invention includes not only a direct measurement of the communication amount but also an indirect measure of the amount representing the communication amount. For example, as the former example, the number of received packets in a certain period Examples of the latter include the number of vehicles that have been able to receive a packet within a certain period, and the percentage of time that received power has exceeded a predetermined value within a certain period. Moreover, what performed predetermined calculation with respect to these may be used.

  The transmission period information table 202 stores the transmission period information as in the first embodiment, and stores the communication amount measured by the communication amount observation unit 201.

  In addition to the transmission period information stored in the transmission period information table 202, the transmission period selection unit 203 is based on the communication volume stored in the transmission period information table 202, and the reserved transmission candidate period used in the reserved transmission (“ Corresponding to “first transmission period”). The specific operation of the transmission period selection unit 203 will be described later with reference to FIG.

2. Communication Quality Detection The communication quality observation unit 102 obtains the communication quality estimated value according to the example of FIGS. 2 and 3 as in the first embodiment.

3. Next, an example of the operation of the traffic monitoring unit 201 of the communication device 200 according to the present embodiment will be described with reference to FIG.

  The traffic monitoring unit 201 measures the number of packets received in the immediately preceding predetermined observation period, and temporarily stores it in a memory provided in the traffic monitoring unit 201 (S81). The measurement is preferably performed for each reservation transmission candidate period, but is not limited thereto. Instead of the number of received packets, the number of vehicles that have been able to receive a packet within a certain period, the percentage of time that received power exceeded a predetermined value within a certain period, and the like may be used.

  Next, the traffic monitoring unit 201 acquires a predetermined number of past packet receptions from the memory provided in the traffic monitoring unit 201 (S82). For example, for a predetermined observation period, five periods are acquired starting from the current one.

  Then, the “communication amount” is determined for each reserved transmission candidate period from the number of received packets measured in S81 and the number of received packets for the past five periods acquired in S82 (S83). For example, the average value (average number of received packets) or the maximum value (maximum number of received packets) is obtained, and this is set as “communication amount” and stored as communication amount information in the transmission period information table 202 (S84). .

The “communication amount” may be shared with peripheral devices. That is, the "first traffic" detected by the traffic monitoring unit 201 of the own device is sent to the message generating unit 108 and included in the packet and transmitted as transmission data from the own device, and detected by the traffic monitoring unit of the peripheral device. The packet including the “second communication amount” may be received as reception data and stored in the transmission period information table 202. The packet configuration in this case will be described later with reference to FIG.
Here, the “first traffic volume” and the “second traffic volume” of the present invention are, as with the “communication volume”, a quantity that directly represents the traffic volume in addition to a direct measurement of the traffic volume. For example, as the former example, the number of received packets in a certain period, as the latter example, the number of vehicles that could receive a packet within a certain period, and the received power exceeded a predetermined value within a certain period. Percentage of time. Moreover, what performed predetermined calculation with respect to these may be used.

FIG. 9 shows the traffic information portion of the transmission period information table 202. In the transmission period information table 202, the number of packets received by the own device is recorded as “communication amount” or “first communication amount” (vehicle ID: own vehicle). In addition, when sharing the traffic information with the peripheral device, the number of received packets obtained by the peripheral device is acquired from the received data, and this is set as the “second traffic” for each peripheral device. It is recorded in the table 202 (vehicle ID: 1, 2).
Each traffic information is recorded in the past from the newest one. In the example of FIG. 9, the past three periods are recorded. The number of received packets is recorded for each reserved transmission candidate period described with reference to FIG. The communication amount information is updated every time the own device observes or receives from another device.

4). Switching between reserved transmission and random transmission Switching between reserved transmission and random transmission in the transmission method switching unit 104 is based on the example of FIG.

5. Reservation Transmission Start Processing An example of reservation transmission start processing in the transmission period selection unit 203 of the communication apparatus 200 according to this embodiment will be described with reference to FIG.

  The transmission period selection unit 203 acquires an unused reserved transmission candidate period (S101). The acquisition method is the same as in the first embodiment.

  Next, the transmission period selection unit 203 acquires the communication amount for each reserved transmission candidate period measured by the own apparatus from the transmission period information table 202 (S102). Specifically, in FIG. 9, the number of received packets with the vehicle ID of the own vehicle column is acquired.

Next, the transmission period selection unit 203 acquires the type of communication to be reserved and transmitted (S103). The acquisition method is the same as in the first embodiment.
When performing reservation transmission by broadcast that does not specify the other party, reservation transmission candidates from the communication volume for each reservation transmission candidate period received from all peripheral devices and the communication volume for each reservation transmission candidate period measured by the own apparatus The “communication amount” for each period is obtained (S104). For example, in FIG. 9, the vehicle ID acquires the number of received packets in the acquisition order 1 from the traffic information of the own vehicle, and the acquisition order 1 from the traffic information of all the vehicle IDs other than the own vehicle. The number of received packets is acquired, and the total value, average value, or maximum value of the number of received packets is determined for each reserved transmission candidate period. Alternatively, in FIG. 9, for each reservation transmission candidate period, a total value or an average value of the received number of packets for the past three periods (acquisition order 1, 2, 3) of all vehicle IDs including the own vehicle is obtained, or a reservation is made. You may make it obtain | require the maximum value of the reception number of the packets for the past 3 periods (acquisition order 1, 2, 3) of all vehicle IDs including the own vehicle for every transmission candidate period.

  On the other hand, when the reserved transmission is executed by unicast for specifying the other party, the reserved transmission candidate is determined based on the “second traffic” received from the specific peripheral device and the “first traffic” measured by the own device. “Communication traffic” for each period is obtained (S105). For example, in FIG. 9, the total number of packets received in the column where the vehicle ID is the own vehicle and the number of packets received in the column where the vehicle ID is 2 (when the specific peripheral device is the vehicle 2) Every time, the total or average value of the number of received packets is obtained. Alternatively, the maximum value of the number of received packets may be obtained for each reserved transmission candidate period.

Then, the transmission period selection unit 203 selects a reserved transmission candidate period that is unused and whose “communication amount” obtained in S104 or S105 is smaller than “predetermined value” or “less than” (S106). For example, it is assumed that the average value of the number of received packets for the past three periods in the column of vehicle ID 1 is “communication amount”. In FIG. 9, when the predetermined value is 1, only the reserved transmission candidate period # 0 (average value 0.33) is smaller than 1, so the reserved transmission candidate period # 0 is selected. When there are a plurality of candidates, for example, when the predetermined value is 2, reservation transmission candidate periods # 0 (average value 0.33) and # 1 (average value 1.66) are smaller than 2, so select one To do. The selection method may be selected at random in addition to selecting the smallest one among the reserved transmission candidate periods smaller than the predetermined value. Further, the minimum value after the current time may be selected without comparison with a predetermined value.
If there is a reserved transmission candidate period in which the variation in the past communication amount is larger than the predetermined range, the reserved transmission candidate period may be excluded from selection targets on the assumption that the accuracy of the estimated value is low.
Here, the “predetermined value” of the present invention includes not only a constant value but also a value whose value is uniquely determined by giving a condition.
In addition, “more” in the present invention includes both the case where the same value as the comparison target is included and the case where the same value is not included.

  Finally, the transmission period selection unit 203 generates transmission period information related to the selected reserved transmission candidate period, and records it in the transmission period information table 202 (S107). Then, the selected transmission candidate period (corresponding to the “first transmission period” of the present invention) is instructed to the transmission timing determination unit 109.

  As described above, according to Embodiment 2 of the present invention, it is possible to switch to reserved transmission only when it is predicted that the communication quality expected by the communication quality target value cannot be achieved by random transmission. In addition, since the transmission period can be set in a time zone in which the communication amount of random transmission is small, the quality deterioration of random transmission can be further suppressed as compared with the first embodiment while improving the quality of reserved transmission.

(Modification of Embodiment 2)
The operation of the traffic monitoring unit 201 is described with reference to FIG. 8 of the second embodiment, and the traffic information of the transmission period information table 202 is described with reference to FIG. In the second embodiment, the communication amount is obtained and recorded through the process of FIG. 8, but instead of the communication amount, an available reserved transmission candidate period may be obtained and recorded.

  Another example of the operation of the traffic monitoring unit 201 of the communication device 200 will be described with reference to FIG. Portions common to those in FIG. 8 are denoted by the same reference numerals and description thereof is omitted. The difference from FIG. 8 is that after obtaining the communication amount for each reserved transmission candidate period in S83, it is determined whether or not each reserved transmission candidate period is available based on the communication amount, and the available reserved transmission candidate period is specified. (S111).

  That is, the “communication amount” is determined for each reserved transmission candidate period from the number of packets received immediately before measured in S81 and the number of packets received for the past predetermined period acquired in S82 (S83). Then, the communication amount is compared with a predetermined value, and if it is larger than the predetermined value, an unusable flag (N) is set, and if it is smaller than the predetermined value, an available flag (Y) is set (S111).

  FIG. 12 shows the traffic information portion of the transmission period information table 202. In the transmission period information table 202, a flag (corresponding to “first data” of the present invention) set in S111 for each reserved transmission candidate period is recorded as traffic information.

  Note that the flag may be shared with peripheral devices. That is, a flag (corresponding to “first data” in the present invention) generated based on the first traffic detected by the traffic monitoring unit 201 of the own device is sent to the message generator 108 and included in the packet. While transmitting as transmission data from the device, a packet including a flag (corresponding to “second data” in the present invention) generated based on the second traffic detected by the traffic monitoring unit of the peripheral device is received. You may receive as data.

  Then, based on the first data and the second data, a reserved transmission candidate period (corresponding to the “first transmission period” of the present invention) used for reserved transmission is selected from a plurality of reserved transmission candidate periods. . For example, the reserved transmission candidate period in which the first data and the second data are both flags (Y) is selected.

  According to the above modification, the size of the communication amount information can be reduced, the capacity of the transmission period information table 202 can be reduced, and the amount of information to be transmitted when the communication amount is shared with the peripheral device Thus, the quality of reserved transmission can be improved, and the quality deterioration of random transmission can be further suppressed.

(Other configurations related to Embodiments 1 and 2)
1. Information included in packet of transmission / reception data Information included in the packet of reception data and transmission data in the present invention will be described with reference to FIG. It should be noted that packet transmission of the information described here is optional in the present invention, but the effect of the present invention is further enhanced by transmitting / receiving these information and sharing between the own device and the peripheral device. It is something that can be done.

  FIG. 13 is an example of a packet used in the present invention. In such a packet, communication quality information and transmission period information are set in addition to the data to be normally transmitted following the communication protocol header.

  The communication quality information includes the “communication quality estimated value” described in the first embodiment. By sharing the communication quality information, it is possible to improve the estimation accuracy of the communication quality.

  The transmission period information is information related to each reserved transmission candidate period. For each reserved transmission candidate period, the transmission period length of the reserved transmission candidate period, the number of transfers, and the “communication amount”, “ Communication amount information including at least one of “first communication amount” and “first data” is included. By sharing the traffic information, it is possible to improve the estimation accuracy of the traffic.

  The transmission period length indicates that the transmission period length is not used when the transmission period length is zero, and is used when it is not.

  If the transfer count is 1 or more, the received transmission period information is retransmitted after being combined with the transmission period information obtained by the own apparatus. Thereby, it is possible to notify the transmission period information even to the peripheral devices in the hidden terminal relationship.

  The above packets are used for random transmission, but may be used for reserved transmission.

  As described above, by sharing information with peripheral devices using this packet, switching to reserved transmission can be performed with higher accuracy.

  Note that the transmission period information may be determined to be transferred depending on whether the reserved transmission is unicast or broadcast. For example, in the case of unicast, it may be transferred only when the own apparatus is the destination, and may be always transferred in the case of broadcast. By doing so, it is possible to prevent unnecessary transmission period information from being transferred during unicast.

  An expiration date may be set in the transmission period information. By setting the reserved transmission period unnecessarily long, it is possible to prevent the quality of random transmission from deteriorating.

2. Application Example of the Invention An application example of the embodiment of the present invention will be described with reference to FIG. FIG. 14 is an example when the embodiment of the present invention is applied at a junction of expressways.

  In this example, the communication quality target value is set as follows. Normally, in order to notify the driver of the presence of surrounding vehicles, the communication quality target value is set to a value that is successfully received once while traveling 10 m by broadcast communication. Moreover, since it is necessary to always monitor each other's positional information etc. at the time of joining and an intersection, the value which succeeds in reception once is set while driving | running | working 1m by unicast communication. The communication quality target value is linked with the map data, and acquires the communication quality target value corresponding to the position of the own apparatus based on the position information of the own apparatus. Hereinafter, the process from the start of merge to the completion of merge will be described in order.

(1) The joining vehicle and the receiving vehicle usually share position information and the like by random transmission. Further, the joining vehicle and the receiving vehicle measure (or acquire) the communication quality estimated value and the communication amount.

(2) The communication quality target value is set high near the junction. The communication quality target value is specified when receiving the transmission data from the driving support device. For example, when joining or receiving, changing lanes, emergency stop (accidents, breakdowns, accidents of other vehicles, stopping due to breakdowns or falling objects), etc. The communication quality target value is set higher than that during normal driving. In addition, the communication quality target value may be set in cooperation with the map data. And a joining vehicle switches a communication system to reservation transmission according to the flow of FIG. 4 before a joining start. The receiving vehicle switches to reservation transmission according to the flow of FIG. 4 as with the merging vehicle, or switches to reservation transmission when a notification of the start of merging is received from the merging vehicle.

(3) The joining vehicle transmits / receives position information and the like to / from the receiving vehicle using reservation transmission in the reservation transmission candidate period selected according to the flow of FIG. 6 or FIG.

(4) When the joining vehicle is completed, the joining vehicle returns the communication method to random transmission according to the flow of FIG. There are the following triggers for switching to random transmission.
A) The communication quality target value has been returned to the normal value when the merging point is passed, and the merging vehicle ends the reserved transmission and switches to random transmission according to the flow of FIG.
B) The end of joining is detected from position information, traveling direction information, etc., and reserved transmission is switched to random transmission.
C) An expiration date is set during reserved transmission, and the reserved transmission is switched to random transmission when the expiration date has passed.
The receiving vehicle returns the communication method to random transmission in accordance with the flow of FIG. 4 as in the case of the merging vehicle or when the notification of merging completion is received from the merging vehicle.

3. Other Modifications of Each Embodiment When a reserved transmission is performed, whether the peripheral device is transmitting by carrier sense may be investigated as in the case of random transmission. If it is determined that transmission is in progress, the reserved transmission is not performed and the random transmission is performed. Thereby, while preventing collision of a packet, it can also suppress that communication delay increases by waiting for the next transmission period.

  The communication quality may be constantly measured even during reserved transmission, and when the communication quality changes to a state that can satisfy the communication quality target value, the reserved transmission may be returned to random transmission. As a result, unnecessary reserved transmission is not performed, and quality degradation of random transmission can be prevented.

  If the reserved transmission candidate period in use by the peripheral device can be extended to be the reserved transmission candidate period of its own, it is given priority. When a limited number of reserved transmission candidate periods are prepared with a predetermined repetition period, it is possible to prevent the reserved transmission candidate periods from becoming insufficient.

  The situation to which the present invention is applied is effective not only when an intersection or a highway joins but also when an emergency stop is caused by a traffic accident, a fallen object, a traffic jam, or the like.

(Summary)

The characteristics of the communication device according to the embodiment of the present invention have been described above.
In the above embodiment, the communication device of the present invention is mounted on a vehicle, that is, the vehicle-mounted device has been described. However, the pedestrian possesses the communication device of the present invention, and the present invention is applied to the communication device. May be. In other words, it can be applied not only between vehicles, but also between pedestrians, and theoretically between pedestrians.
One communication device may be mounted on the roadside machine. That is, it can be applied between road vehicles. The roadside machine may include one that does not perform random transmission but only performs reserved transmission.

  In the above embodiment, the switch S for switching between the transmission unit and the reception unit of the communication device and the antenna A connected to the switch S are not included in the communication device, but the switch S and the antenna A are connected to the communication device. It may be a communication terminal device. Alternatively, instead of the switch S, separate antennas A may be connected for transmission and reception, respectively. In addition, the communication terminal device may be provided with an amplifier and various filters. Naturally, the communication terminal device may include at least one of the own vehicle position information generation device (GPS), the map database, the own vehicle behavior acquisition unit (vehicle speed sensor, gyro)), the driving support device, the vehicle control device, and the HMI. .

Examples of the communication device as the in-vehicle device include a semiconductor, an electronic circuit, a module, or an ECU (Electronic Control Unit). Examples of the communication terminal device include a car navigation system, a smartphone, a personal computer, and a portable information terminal in addition to a state in which an ECU is mounted on an automobile and connected to an antenna or the like.
Examples of communication devices possessed by pedestrians include smartphones, personal computers, and portable information terminals.
Moreover, a semiconductor, an electronic circuit, and a module are mentioned as an example of the communication apparatus as a roadside machine.

This specification discloses the present invention not only as a product invention but also as a method invention.
In addition, the present invention can be realized not only by the above-described 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 memory for executing the program. Can also be realized. The program can also be provided to the above-described dedicated hardware or microcomputer via a communication line from a server without using a recording medium. As a result, the latest functions can always be provided through program upgrades.

  The communication device and the communication terminal device according to the present invention are mainly used for communication between vehicles (communication between vehicles), but between a vehicle and a pedestrian (communication between vehicles) or between a vehicle and a roadside device. May be used for communication (between road and vehicle). Furthermore, the present invention is not limited to these applications.

DESCRIPTION OF SYMBOLS 100 Communication apparatus 101 Reception part 102 Communication quality observation part 103 Communication quality information table 104 Transmission method switching part 105 Communication quality target value table 106 Transmission period information table 107 Transmission period selection part 108 Message generation part 109 transmission timing determination unit, 110 transmission unit

Claims (13)

A receiving unit (101) for receiving received data transmitted from the peripheral device;
A communication quality detection unit (102, 103) for obtaining a communication quality estimate based on the received data;
Based on the communication quality estimation value and the communication quality target value, the reserved transmission transmitted in the first transmission period notified to the peripheral device and the random transmission in the second transmission period other than the first transmission period A control unit (104, 105) for switching between random transmission,
A transmission unit (110) for transmitting transmission data using the reserved transmission or the random transmission switched by the control unit;
A communication device. The communication quality estimate is obtained by measuring the reception quality of the reception data randomly transmitted from the peripheral device.
The communication apparatus according to claim 1. The received data includes the communication quality estimate obtained by the peripheral device,
The control unit switches between the reserved transmission and the random transmission based on the communication quality estimated value and the communication quality target value obtained by the peripheral device,
The transmission data includes the communication quality estimation value obtained by the own device,
The communication apparatus according to claim 1. The transmission unit includes the communication quality estimation value obtained by the own device and includes the transmission data that is randomly transmitted, and transmits the transmission data.
The communication apparatus according to claim 3. Furthermore, it has a traffic detection unit (201) for determining the traffic based on the received data randomly transmitted from the peripheral device,
The control unit further selects the first transmission period from a plurality of reserved transmission candidate periods prepared during a certain period based on the communication amount.
The communication apparatus according to claim 1. The control unit selects the first transmission period from a plurality of reserved transmission candidate periods prepared during a certain period, the communication amount being smaller than a predetermined value.
The communication device according to claim 5. The control unit selects the first transmission period that has the smallest traffic among the reserved transmission candidate periods prepared in a plurality of periods.
The communication device according to claim 5. The traffic is measured at the certain period.
The communication device according to claim 5. Furthermore, it has a traffic detection unit (201) for obtaining a first traffic based on the received data randomly transmitted from the peripheral device,
The received data includes a second communication amount obtained by the peripheral device,
The first transmission period is selected based on the first communication amount and the second communication amount from a plurality of reserved transmission candidate periods prepared for a certain period,
The transmission data includes the first traffic.
The communication apparatus according to claim 1. Furthermore, it has a traffic detection unit (201) for obtaining a first traffic based on the received data randomly transmitted from the peripheral device,
The control unit generates first data indicating whether or not the first communication amount in each of the reservation transmission periods is smaller than a predetermined value,
The received data includes second data indicating whether or not the second communication amount in each of the plurality of reserved transmission periods obtained by the peripheral device is smaller than a predetermined value,
The first transmission period is selected based on the first data and the second data from a plurality of reserved transmission candidate periods prepared for a certain period,
The transmission data includes the first data,
The communication apparatus according to claim 1. A receiving unit (101) for receiving received data transmitted from the peripheral device;
A communication quality detection unit (102, 103) for obtaining a communication quality estimate based on the received data;
Based on the communication quality estimation value and the communication quality target value, the reserved transmission transmitted in the first transmission period notified to the peripheral device and the random transmission in the second transmission period other than the first transmission period A control unit (104, 105) for switching between random transmission,
A transmission unit (110) for transmitting transmission data using the reserved transmission or the random transmission switched by the control unit;
An antenna (A) connected to the receiving unit and the transmitting unit;
A communication terminal device. A reception step of receiving reception data transmitted from the peripheral device;
A communication quality detection step for obtaining a communication quality estimate based on the received data;
Based on the communication quality estimation value and the communication quality target value, the reserved transmission transmitted in the first transmission period notified to the peripheral device and the random transmission in the second transmission period other than the first transmission period A control step for switching between random transmission and
A transmission step of transmitting transmission data using the reserved transmission or the random transmission switched by the control unit;
A communication method comprising: A reception step of receiving reception data transmitted from the peripheral device;
A communication quality detection step for obtaining a communication quality estimate based on the received data;
Based on the communication quality estimation value and the communication quality target value, the reserved transmission transmitted in the first transmission period notified to the peripheral device and the random transmission in the second transmission period other than the first transmission period A control step for switching between random transmission and
A transmission step of transmitting transmission data using the reserved transmission or the random transmission switched by the control unit;
A communication program comprising: