JP2009278366A - Roadside device, communication method of roadside device, and communication program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform broadcast communication even when retry frequently occurs in individual communication in a communication system between a road and a vehicle, which performs the broadcast communication and the individual communication. <P>SOLUTION: A data processing part 111 outputs N pieces of individual communication data 303 and M pieces of broadcast communication data 302 to a communication control part 112 when the number of pieces of individual communication data 303 is equal to or more than a predetermined upper limit number N, and outputs all the pieces of individual communication data 303 and N+M-k pieces of broadcast communication data 302 to the communication control part 112 when the number of individual communication data 303 is less than the predetermined upper limit number N (k pieces). The communication control part 112 generates a communication frame 305 including the number of broadcast communication data 302 equal to or more than a compensated number M by the broadcast communication data 302 and the individual communication data 303 output from the data processing part 111. A radio wave transmitting/receiving part 120 transmits the communication frame 305 generated by the communication control part 112 to each onboard unit by a DSRC beacon. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to, for example, a roadside device that performs broadcast communication and individual communication with an in-vehicle device of each vehicle, a communication method of the roadside device, and a communication program.

  Currently, road-to-vehicle communication systems that perform communication between a roadside station (roadside device) and a vehicle wireless device (onboard device) mounted on the vehicle, such as a DSRC (Dedicated Short Range Communication) system, are becoming widespread.

  The signal configuration used in the road-to-vehicle communication system includes, for example, a broadcast communication unit for reporting information such as traffic information of the jurisdiction from the roadside station side to the subscriber by broadcast, vehicle transmission and vehicle reception, etc. An individual communication unit relating to each participating vehicle that is running is included (Patent Document 1).

In addition, when the number of in-vehicle devices that communicate with the roadside device increases, in the individual communication between the roadside device and the in-vehicle device, for example, the data transmitted from the in-vehicle device to the roadside device disappears for some reason, so the roadside device There may be a retry (retransmission control) in which a retransmission request is made to the in-vehicle device and the in-vehicle device retransmits the data.
Conventionally, when performing individual communication with a specific communication partner, individual communication is performed with priority over broadcast communication performed with an unspecified number. For this reason, when a retry occurs in the individual communication, the individual communication has priority over the broadcast communication.
Accordingly, when retrying of individual communication frequently occurs due to an increase in the number of vehicles that communicate, the communication band of the communication frame configuration is occupied by the individual communication data, and the band for broadcast communication data is lost.
As a result, broadcast communication cannot be performed, and there is a problem that information cannot be provided in a system that provides information mainly by the broadcast communication.

In addition, the conventional ETC (Electronic Toll Collection) performs billing processing between one roadside device (roadside device) and one in-vehicle device. I was only communicating.
In the conventional ETC, the communication data set in the communication frame is only individual communication data. For this reason, in the conventional ETC, a data path provided between a data processing unit that creates individual communication data and a communication control unit that creates a communication frame including individual communication data is one for individual communication data. Met. Further, the data structure of the data path is a queue structure in which the data input first is output first. Such an input / output method is called FIFO (First-In First-Out).
Therefore, when the function is expanded from ETC to DSRC, the ETC individual communication data and the DSRC broadcast data are sequentially stored in one data path. When the retry of the individual communication data occurs frequently, the data path becomes a queue in which the individual communication data that have been retried are arranged.
For this reason, in a system that provides information mainly by broadcast communication, when creating a communication frame, broadcast data cannot be output from the data path forming the queue of individual communication data to the communication control unit. . As a result, the communication control unit cannot generate a communication frame including broadcast communication data, and there is a problem that the broadcast communication is interrupted.
Japanese Patent Publication No. 6-066673

  For example, in a road-to-vehicle communication system that performs broadcast communication and individual communication, an object of the present invention is to enable broadcast communication even if retries occur frequently in individual communication.

  The roadside device of the present invention is a roadside device that performs data communication with an in-vehicle device mounted on a vehicle, and uses a CPU (Central Processing Unit) as data transmitted to each in-vehicle device of a plurality of vehicles. A data processing unit that generates data transmitted to an in-vehicle device of a specific vehicle as individual communication data using a CPU, the broadcast communication data generated by the data processing unit, and the data processing unit The broadcast data and the individual communication data that are equal to or larger than the broadcast compensation size that is set in advance as a compensation size to be secured for transmission of the broadcast data are input. Including the individual communication data having an upper limit size for limiting the transmission size and a predetermined upper limit size for individual use. A communication control unit that generates a communication frame using a CPU, and a radio wave communication unit that transmits the communication frame generated by the communication control unit to an in-vehicle device of each vehicle by radio waves.

  According to the present invention, for example, in a road-to-vehicle communication system that performs broadcast communication and individual communication, broadcast communication can be performed even if retries frequently occur in individual communication.

Embodiment 1 FIG.
FIG. 1 is an overall block diagram of a DSRC road-to-vehicle communication system 200 according to the first embodiment.
The configuration of DSRC road-to-vehicle communication system 200 in the first embodiment will be described below with reference to FIG.

  The DSRC road-to-vehicle communication system 200 includes an in-vehicle device 210 mounted on each vehicle, a higher-level device 220 that generates broadcast data 301 transmitted to the in-vehicle device 210, and broadcast data 301 generated by the higher-level device 220. The roadside device 100 includes the divided broadcast communication data 302 included in the communication frame 305 and transmits it to the in-vehicle device 210.

The roadside device 100 includes a data processing unit 111, a communication control unit 112, a radio wave transmission / reception unit 120, and a memory unit 119. The roadside device 100 broadcasts the broadcast communication data 302 to a plurality of in-vehicle devices 210, and individually The communication data 303 is communicated individually. Hereinafter, the data processing unit 111, the communication control unit 112, and the memory unit 119 are collectively referred to as the control unit 110.
Broadcast communication is one-to-many one-way communication performed in a broadcast type. In the DSRC road-to-vehicle communication system 200, broadcast data 302 is transmitted from one roadside device 100 to a plurality of in-vehicle devices 210 as broadcast communication.
The individual communication is bi-directional communication performed on a one-to-one basis, for example, communication at the time of billing processing performed in ETC. In the DSRC road-to-vehicle communication system 200, individual communication data 303 is transmitted and received between one roadside device 100 and one in-vehicle device 210 as individual communication.

The data processing unit 111 generates data to be transmitted to the in-vehicle devices 210 of each of the plurality of vehicles as broadcast data 302 using a CPU (Central Processing Unit) and transmits the data to the in-vehicle devices 210 of a specific vehicle. Data is generated using the CPU as the individual communication data 303.
Next, the data processing unit 111 stores the plurality of generated broadcast data 302 in a predetermined order (data arrangement order, generation order, etc.) in a broadcast buffer (for example, a broadcast communication queue 312 described later). The plurality of generated individual communication data 303 is stored in an individual buffer (for example, an individual communication queue 311 described later) in a predetermined order.
Then, the data processing unit 111 acquires a plurality of broadcast communication data 302 from the broadcast buffer in a storage order at a specific timing (for example, when a frame interrupt signal 306 described later is output from the communication control unit 112). The plurality of broadcast communication data 302 acquired together with the communication control unit 112 is output to the communication control unit 112, and the plurality of individual communication data 303 is acquired from the individual buffer in the storage order at a specific timing, and the acquired plurality of individual communication data 303 is subjected to communication control. Output to the unit 112.

The data processing unit 111 performs the following processing using the CPU. The corresponding steps of the flowchart described later are shown in parentheses [].
(A) Determination of generation time interval of broadcast communication data 302 [S1]
(B) Determination of timing for performing individual communication [S5]
(C) Generation of broadcast communication data 302 based on the broadcast data 301 [S4]
(D) Generation of individual communication data 303 [S6]
(E) Confirmation of the number of queues of the individual communication data 303 [S8]
(F) Output of frame setting data 304 (broadcast communication data 302, individual communication data 303) to communication control unit 112 [S9, S10]

The communication control unit 112 receives the broadcast communication data 302 generated by the data processing unit 111 and the individual communication data 303 generated by the data processing unit 111 and compensates for transmission of the broadcast communication data 302. An individual upper limit size (described later) that is a predetermined upper limit size for limiting the transmission size of the broadcast communication data 302 and the individual communication data 303 that are equal to or larger than a predetermined broadcast compensation size (the number M of compensation slots described later). The CPU generates a communication frame 305 including the individual communication data 303 equal to or less than the upper limit number of slots N).
The data size (number of data slots described later) of the communication frame 305 generated by the communication control unit 112 is equal to the total size of the broadcast compensation size and the individual upper limit size.
When the total size of the plurality of individual communication data 303 generated by the data processing unit 111 is equal to or greater than the individual upper limit size, the communication control unit 112 and the individual communication data 303 corresponding to the individual upper limit size and the broadcast compensation size The communication frame 305 including the broadcast communication data 302 is generated.
Further, when the total size of the plurality of individual communication data 303 generated by the data processing unit 111 is less than the individual upper limit size, the communication control unit 112 determines all the individual communication data 303 and the data size of the communication frame 305 from The communication frame 305 including the broadcast communication data 302 for the remaining size obtained by subtracting the total size of the individual communication data 303 is generated.

Further, the communication control unit 112 performs the following processing using the CPU. The corresponding steps of the flowchart described later are shown in parentheses [].
(G) Outputting the frame interrupt signal 306 to the data processing unit 111 [S7]
(H) Generation of communication frame 305 based on frame setting data 304 (broadcast communication data 302, individual communication data 303) output from data processing unit 111 [S9, S10]
(I) Outputting the communication frame 305 to the radio wave transmitting / receiving unit 120 [S9, S10]

  The radio wave transmission / reception unit 120 (radio wave communication unit) transmits the communication frame 305 generated by the communication control unit 112 to the in-vehicle device 210 of each vehicle using radio waves of 5.8 GHz band (hereinafter referred to as DSRC beacons).

  The memory unit 119 stores various data (for example, broadcast data 302) used by the control unit 110 using a storage device.

  The in-vehicle device 210 is mounted on each vehicle and communicates with the roadside device 100 by transmitting and receiving DSRC beacons.

The host device 220 generates the broadcast data 301 using the CPU, and transmits the generated broadcast data 301 to the data processing unit 111 of the roadside device 100.
For example, the host device 220 periodically generates traffic information including signal light color information, traveling vehicle information, and information on accidents that have occurred, and the roadside device 100 uses the generated traffic information as broadcast data 301. To the data processing unit 111.

FIG. 2 is a diagram illustrating an outline of communication processing of the roadside device 100 according to the first embodiment.
An outline of communication processing of the roadside device 100 in the first embodiment will be described below based on FIG.

  The roadside device 100 according to the first embodiment includes a buffer memory (hereinafter referred to as an individual communication queue 311) in which individual communication data 303 is stored in FIFO format, and a buffer memory (in which the broadcast communication data 302 is stored in FIFO format). Hereinafter referred to as a broadcast communication queue 312).

Here, it is assumed that N or more individual communication data 303 and M or more broadcast communication data 302 are stored in the memory unit 119.
The number of slots for communication data in the communication frame 305 (hereinafter referred to as the number of data slots) is “N + M”.
Of the number of data slots in the communication frame 305, the number of slots in the compensation band reserved for the broadcast data 302 (hereinafter referred to as the number of compensation slots) is “M”, and the upper limit number of slots for the individual communication data 303. Is “N”.
“Slot” refers to a data unit (data size, communication time) set in the communication frame 305.

(1) The data processing unit 111 acquires the individual communication data 303 and the broadcast communication data 302 from the memory unit 119, stores the individual communication data 303 in the individual communication queue 311 in order, and stores the broadcast communication data 302. The broadcast queues 312 are stored in order.
(2) The communication control unit 112 outputs a frame interrupt signal 306 to the data processing unit 111 at a timing at which the next communication frame 305 can be transmitted.
(3) Upon receiving the frame interrupt signal 306, the data processing unit 111 extracts the N pieces of individual communication data 303 from the individual communication queue 311 in the order of storage and outputs them to the communication control unit 112, and M pieces of broadcast communication. The data 302 is extracted from the broadcast communication queue 312 in the storage order and output to the communication control unit 112.
(4) The communication control unit 112 generates the communication frame 305 including the N pieces of individual communication data 303 and the M pieces of broadcast communication data 302 output from the data processing unit 111.
(5) The generated communication frame 305 is transmitted from the radio wave transmission / reception unit 120.

The roadside device 100 according to the first embodiment has two data communication queues 311 and a broadcast communication queue 312 as data paths from the data processing unit 111 to the communication control unit 112.
As a result, the roadside device 100 causes the individual communication data 303 from the broadcast communication queue 312 even if a communication error occurs in the individual communication data 303 and the individual communication data 303 accumulates in the individual communication queue 311 for retransmission of the individual communication data 303. Broadcast data 302 can be easily retrieved.
In addition, the roadside device 100 according to the first embodiment secures M compensation slots for the broadcast communication data 302 in the communication frame 305.
As a result, the roadside device 100 can transmit at least M pieces of broadcast data 302 to a single communication even if many pieces of individual communication data 303 generated before the broadcast data 302 are stored in the individual communication queue 311. It can be transmitted in frame 305.

FIG. 3 is a diagram showing an outline of communication processing of the roadside device 190 different from the first embodiment.
An outline of communication processing of the roadside device 190 different from that of the first embodiment will be described below based on FIG.

The roadside device 190 has only one queue (313) as a data path from the data processing unit 191 to the communication control unit 192, and does not secure a compensation band for the broadcast communication data 302 in the communication frame 305.
Other conditions are the same as those of the roadside apparatus 100 of FIG.

(1) The data processing unit 191 acquires the individual communication data 303 and the broadcast communication data 302 from the memory unit 194, and stores the acquired individual communication data 303 and the broadcast communication data 302 in the communication queue 313 in order. To do. At this time, as shown in FIG. 3, it is assumed that N individual communication data 303 and M broadcast communication data 302 are alternately stored in the communication queue 313.
(2) The communication control unit 192 outputs a frame interrupt signal 306 to the data processing unit 191 at a timing at which the next communication frame 305 can be transmitted.
(3) Upon receiving the frame interrupt signal 306, the data processing unit 191 extracts N + M data (broadcast communication data 302, individual communication data 303) from the communication queue 313 in the order of storage and outputs the data to the communication control unit 192. .
(4) The communication control unit 192 generates the communication frame 305a including N + M pieces of data (broadcast communication data 302, individual communication data 303) output from the data processing unit 191.
(5) The generated communication frame 305 a is transmitted from the radio wave transmission / reception unit 120.

  Here, it is assumed that a retry due to a communication error has occurred in r individual communication data 303 among the individual communication data 303 included in the communication frame 305a.

In this case, since the next communication frame 305b to be transmitted includes r individual communication data 303 that have been retried, the data processing unit 191 receives the frame interrupt signal 306 next time, and N + M−r The pieces of data are output from the communication queue 313 to the communication control unit 192 in the storage order (individual N + 1,..., Individual 2N, broadcast M + 1,..., Broadcast 2M-r).
Then, the communication control unit 192 generates a communication frame 305b including the r individual communication data 303 that has been retried, the new N individual communication data 303, and the M-r broadcast communication data 302. .
That is, when a retry occurs in the individual communication data 303, the number of broadcast communication data 302 set in the communication frame 305b is reduced by the number of retries of the individual communication data 303.
When the retry of the individual communication data 303 occurs frequently, the communication frame 305 is filled with the retryed individual communication data 303, and the broadcast communication data 302 is not transmitted.

The roadside apparatus 100 according to the first embodiment can transmit the broadcast data 302 for at least the compensation band in one communication frame 305 by ensuring the communication band 305 for the broadcast data 302 in the communication frame 305.
Further, the roadside device 100 according to the first embodiment separately has a data path for the individual communication data 303 (individual communication queue 311) and a data path for the broadcast communication data 302 (broadcast communication queue 312). Thus, regardless of the presence or absence of the individual communication data 303, the broadcast communication data 302 can be easily taken out from the data path and included in the communication frame 305.

FIG. 4 is a diagram illustrating an example of hardware resources of the roadside device 100 according to the first embodiment.
In FIG. 4, the roadside apparatus 100 includes a CPU 911 (also referred to as a central processing unit, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a processor) that executes a program. The CPU 911 is connected to the ROM 913, the RAM 914, the communication board 915, the wireless antenna 916, and the magnetic disk device 920 via the bus 912, and controls these hardware devices. Instead of the magnetic disk device 920, another storage device (for example, a semiconductor memory such as a RAM or a flash memory) may be used.
The RAM 914 is an example of a volatile memory and is also used as a buffer memory. The storage medium of the ROM 913 and the magnetic disk device 920 is an example of a nonvolatile memory. These are examples of a storage device, a storage device, or a storage unit. A storage device in which input data is stored is an example of an input device, an input device, or an input unit, and a storage device in which output data is stored is an example of an output device, an output device, or an output unit.
The communication board 915 and the wireless antenna 916 are examples of input / output devices, input / output devices, or input / output units.

  The communication board 915 is wired or wirelessly connected to a communication network such as a LAN (Local Area Network), the Internet, a WAN (Wide Area Network) such as ISDN, and a telephone line. For example, the communication board 915 is connected to the host device 220 with a communication cable.

  The wireless antenna 916 receives and transmits DSRC beacons and communicates with the in-vehicle device 210.

  The magnetic disk device 920 stores an OS 921 (operating system), a program group 923, and a file group 924. The programs in the program group 923 are executed by the CPU 911 and the OS 921.

  The program group 923 stores a program for executing a function described as “˜unit” in the embodiment. The program is read and executed by the CPU 911.

In the file group 924, in the embodiment, result data such as “determination result”, “calculation result of”, “processing result of” when executing the function of “to part”, “to part” The data to be passed between programs that execute the function “,” other information, data, signal values, variable values, and parameters are stored as items “˜file” and “˜database”. Broadcast data 301, broadcast communication data 302, individual communication data 303, frame setting data 304, etc. are examples of what is included in the file group 924.
The “˜file” and “˜database” are stored in a recording medium such as a disk or a memory. Information, data, signal values, variable values, and parameters stored in a storage medium such as a disk or memory are read out to the main memory or cache memory by the CPU 911 via a read / write circuit, and extracted, searched, referenced, compared, and calculated. Used for CPU operations such as calculation, processing, output, printing, and display. Information, data, signal values, variable values, and parameters are temporarily stored in the main memory, cache memory, and buffer memory during the CPU operations of extraction, search, reference, comparison, operation, calculation, processing, output, printing, and display. Is remembered.
In addition, arrows in the flowcharts described in the embodiments mainly indicate input / output of data and signals, and the data and signal values are recorded in the memory of the RAM 914, the magnetic disk of the magnetic disk device 920, and other recording media. . Data and signal values are transmitted online via a bus 912, signal lines, cables, or other transmission media.

  In addition, what is described as “˜unit” in the embodiment may be “˜circuit”, “˜device”, “˜device”, and “˜step”, “˜procedure”, “˜”. Processing ". That is, what is described as “˜unit” may be realized by firmware stored in the ROM 913. Alternatively, it may be implemented only by software, only hardware such as elements, devices, substrates, wirings, etc., or a combination of software and hardware, and further a combination of firmware. Firmware and software are stored as programs on a magnetic disk or other recording medium. The program is read by the CPU 911 and executed by the CPU 911. That is, the program causes the computer to function as “to part”. Alternatively, the procedure or method of “to part” is executed by a computer.

FIG. 5 is a flowchart showing the operation of the data processing unit 111 according to the first embodiment.
The communication method of the roadside apparatus 100 in Embodiment 1 is demonstrated below based on FIG.

<Step S1>
The data processing unit 111 uses the counter variable to determine whether the queue storage time (T seconds) has elapsed since the previous lapse.
The queue storage time T is determined in advance as an execution interval of processing for retrieving the broadcast communication data 302 from the memory unit 119 and storing it in the broadcast communication queue 312. For example, in DSSS (Driving Safety Support Systems) such as an electronic intersection, a time of about 100 ms may be set as the queue storage time T.
If the queue storage time T has elapsed (Yes), the process proceeds to step S2, and if the queue storage time T has not elapsed (No), the process proceeds to step S3.

<Step S3>
If No in step S <b> 1 (the queue storage time T has not elapsed), the data processing unit 111 determines whether the broadcast data 301 has arrived from the higher-level device 220.
The broadcast data 301 is data that is the basis of the broadcast communication data 302 and is generated by the host device 220.
For example, the host device 220 periodically generates traffic information including signal light color information, traveling vehicle information, and information on an accident that has occurred (> queue storage time T), and broadcasts the generated traffic information. It transmits to the roadside apparatus 100 as the business data 301.
If the broadcast data 301 has arrived (Yes), the process proceeds to step S4. If the broadcast data 301 has not arrived (No), the process proceeds to step S5.

<Step S4>
If Yes (broadcast data 301 has arrived) in step S3, the data processing unit 111 divides the broadcast data 301 that has arrived from the higher-level device 220 into the slot size of the communication frame 305, and each divided data is The broadcast data 302 is stored in the memory unit 119, respectively. When the previously stored broadcast data 302 is stored in the memory unit 119, the data processing unit 111 updates the previous broadcast data 302 with the new broadcast data 302.
The slot size of the communication frame 305 is assumed to be predetermined. For example, the slot size of the communication frame 305 is determined as a data length that the in-vehicle device 210 can process at a time.
After step S4, the process proceeds to step S5.

<Step S2>
If YES in step S1 (the queue storage time T has elapsed), the data processing unit 111 acquires the broadcast data 302 stored in step S4 from the memory unit 119, and divides the acquired broadcast data 302. The data is stored in the broadcast communication queue 312 in the order of the previous data.
After step S2, the process proceeds to step S5.

<Step S5>
Next, the data processing unit 111 determines whether it is an individual communication timing.
The individual communication timing is a timing at which a signal (DSRC beacon) transmitted from the in-vehicle device 210 of the vehicle is detected, and individual communication between the road-side device 100 and the in-vehicle device 210 is possible when the vehicle approaches the road-side device 100. It shows that it became. For example, in individual communication, communication data for ETC charging processing is transmitted and received as individual communication data 303.
The in-vehicle device 210 that wants to perform individual communication transmits a signal “I want to perform individual communication” to the roadside device 100.
The radio wave transmission / reception unit 120 monitors a signal from the in-vehicle device 210 as needed, and the data processing unit 111 performs an individual communication timing when the intensity of the signal from the in-vehicle device 210 detected by the radio wave transmission / reception unit 120 is equal to or higher than a predetermined strength. Judge that there is.
If it is the individual communication timing (Yes), the process proceeds to step S6, and if it is not the individual communication timing (No), the process proceeds to step S7.

<Step S6>
In the case of Yes (individual communication timing) in step S5, the data processing unit 111 generates individual data (for example, ETC application data) necessary for individual communication.
Then, the data processing unit 111 divides the generated individual data into the slot size of the communication frame 305, and stores the divided data in the individual communication queue 311 in the order of the data before the division. Each data stored in the individual communication queue 311 is referred to as individual communication data 303.
After step S6, the process proceeds to step S7.

<Step S7>
Next, the data processing unit 111 repeatedly determines whether the frame interrupt signal 306 has been output from the communication control unit 112 and waits for the frame interrupt signal 306 to be output from the communication control unit 112.
The frame interrupt signal 306 is a hardware signal periodically output from a communication device (not shown) of the roadside device 100 used for communication with the in-vehicle device 210, and indicates a timing at which the communication frame 305 can be transmitted.
When the frame interrupt signal 306 is output (Yes), the process proceeds to step S8.

<Step S8>
When the frame interrupt signal 306 is output in step S7 (Yes), the data processing unit 111 indicates that the number of individual communication data 303 stored in the individual communication queue 311 (hereinafter referred to as queue number k) is individual. It is determined whether or not the upper limit slot number N for the communication data 303 is greater than or equal to N.
The upper limit slot number N for the individual communication data 303 is determined as a number obtained by subtracting the compensation slot number M for the broadcast communication data 302 from the number of communication data slots of the communication frame 305 (hereinafter referred to as the data slot number Z). It is done. The relationship “Z = N + M” is satisfied.
The broadcast communication data 302 is included in the communication frame 305 at least in the number of compensation slots M, and the individual communication data 303 is included in the communication frame 305 up to the upper limit number of slots N.
If the queue number k of the individual communication data 303 is equal to or greater than the upper limit slot number N for the individual communication data 303 (Yes), the process proceeds to step S9, and the queue number k of the individual communication data 303 is the upper limit for the individual communication data 303. If the number is less than N (No), the process proceeds to step S10.

<Step S9>
If Yes (queue number k ≧ upper limit slot number N) in step S8, the data processing unit 111 extracts N pieces of individual communication data 303 from the individual communication queue 311 in the order of storage and M pieces from the broadcast communication queue 312. The broadcast communication data 302 is extracted in the order of storage, and the extracted N pieces of individual communication data 303 and M pieces of broadcast communication data 302 are output to the communication control unit 112 as frame setting data 304.
It is assumed that M or more broadcast communication data 302 are stored in the broadcast communication queue 312 by step S2.

<Step S10>
In step S8, if No (queue number k <upper limit slot number N), the data processing unit 111 extracts all the individual communication data 303 (k pieces) from the individual communication queue 311 in the order of storage, and the broadcast communication queue 312. N + M−k broadcast communication data 302 are taken out in the order of storage, and the extracted k individual communication data 303 and N + M−k broadcast communication data 302 are output to the communication control unit 112 as frame setting data 304. .
It is assumed that N + M−k or more pieces of broadcast communication data 302 are stored in the broadcast communication queue 312 by step S2.

The communication control unit 112 that has received the frame setting data 304 from the data processing unit 111 in step S9 or step S10 sets the frame setting data 304 to the communication frame 305, and outputs the set communication frame 305 to the radio wave transmission / reception unit 120. .
And the radio wave transmission / reception part 120 transmits the communication frame 305 output from the communication control part 112 with respect to the vehicle-mounted apparatus 210 of each vehicle by a DSRC beacon.
Each individual communication data 303 set in the communication frame 305 is received only by the in-vehicle device 210 targeted for individual communication, and each broadcast communication data 302 set in the communication frame 305 is received by all the in-vehicle devices 210. .
Thereafter, the processing from step S1 to step S10 is repeatedly executed.

FIG. 6 is a diagram showing the communication frame 305 in the first embodiment.
The communication frame 305 generated in step S9 (see FIG. 5) and the communication frame 305 generated in step S10 (see FIG. 5) will be described below based on FIG.

When the queue number k of the individual communication data 303 is the upper limit slot number N or more (step S9), N individual communication data 303 and M broadcast communication data 302 are set in the communication frame 305 as frame setting data 304. Is done.
In the first embodiment, it is compensated that at least M pieces of broadcast communication data 302 are included in the communication frame 305. For this reason, even if there are N or more individual communication data 303, the total number N + M of the individual communication data 303 and the broadcast data 302 that can be included in the communication frame 305 is calculated from the compensation number M of the broadcast data 302. Only N frames minus the number are set in the communication frame 305.

  When the individual communication data 303 is less than the upper limit N (k) (step S10), k individual communication data 303 and N + M−k broadcast communication data 302 are set in the communication frame 305 as frame setting data 304. Is done.

  The individual communication data 303 set in the communication frame 305 is individually communicated to each vehicle, and the broadcast communication data 302 set in the communication frame 305 is broadcast to all the vehicles.

In the first embodiment, the following roadside device 100 has been described.
When the DSRC roadside device (roadside device 100) performs broadcast communication and individual communication with the DSRC in-vehicle device (in-vehicle device 210), the DSRC roadside device (roadside device 100) secures the broadcast band M in the communication frame 305.
As a result, the DSRC roadside device does not dedicate the communication frame 305 to the individual communication data 303 even for the retry of individual communication that occurs frequently due to an increase in the number of vehicles that communicate with each other. To.
In addition, the DSRC roadside device separates the data paths (the individual communication queue 311 and the broadcast communication queue 312) between the individual communication data 303 output from the data processing unit 111 to the communication control unit 112 and the broadcast communication data 302. ing.
As a result, even if a retry occurs in the individual communication, the DSRC roadside device has a different data path, so that the broadcast communication is performed regardless of the output of the individual communication data 303 from the data processing unit 111 to the communication control unit 112. Data 302 can be output. Then, the DSRC roadside device can generate the communication frame 305 including the broadcast communication data 302 by the communication control unit 112.

1 is an overall block diagram of a DSRC road-to-vehicle communication system 200 according to Embodiment 1. FIG. The figure which shows the outline | summary of the communication process of the roadside apparatus 100 in Embodiment 1. FIG. The figure which shows the outline | summary of the communication processing of the roadside apparatus 190 different from Embodiment 1. FIG. FIG. 3 is a diagram illustrating an example of hardware resources of the roadside device 100 according to the first embodiment. 5 is a flowchart showing the operation of the data processing unit 111 according to the first embodiment. FIG. 3 shows a communication frame 305 in Embodiment 1.

Explanation of symbols

  100 roadside device, 110 control unit, 111 data processing unit, 112 communication control unit, 119 memory unit, 120 radio wave transmission / reception unit, 190 roadside device, 191 data processing unit, 192 communication control unit, 193 radio wave transmission / reception unit, 194 memory unit, 200 DSRC road-to-vehicle communication system, 210 in-vehicle device, 220 host device, 301 broadcast data, 302 broadcast communication data, 303 individual communication data, 304 frame setting data, 305, 305a, 305b communication frame, 306 frame interrupt signal 311 Individual communication queue, 312 Broadcast communication queue, 313 Communication queue, 911 CPU, 912 bus, 913 ROM, 914 RAM, 915 communication board, 916 wireless antenna, 920 magnetic disk unit, 921 OS, 923 program File group, 924 file group.

Claims (6)

A roadside device that performs data communication with an in-vehicle device mounted on a vehicle,
The data transmitted to the in-vehicle devices of each of the plurality of vehicles is generated as broadcast communication data using a CPU (Central Processing Unit), and the data transmitted to the in-vehicle devices of a specific vehicle is used as the individual communication data. A data processing unit to be generated,
The broadcast data generated by the data processing unit and the individual communication data generated by the data processing unit are input and predetermined as a compensation size secured for transmission of the broadcast data A CPU uses a communication frame including the broadcast communication data equal to or larger than the broadcast compensation size and the individual communication data equal to or smaller than an individual upper limit size that is predetermined as an upper limit size for limiting the transmission size of the individual communication data. A communication control unit to generate,
A roadside device comprising: a radio wave communication unit that transmits the communication frame generated by the communication control unit to a vehicle-mounted device of each vehicle by radio waves. The communication control unit
The roadside device according to claim 1, wherein a communication frame having a data size of a total size of the broadcast compensation size and the individual upper limit size is generated. The data processing unit
Generate multiple broadcast data and multiple individual communication data,
The communication control unit
When the total size of the plurality of individual communication data generated by the data processing unit is equal to or greater than the individual upper limit size, the individual communication data for the individual upper limit size and the broadcast communication data for the broadcast compensation size A communication frame including
When the total size of the plurality of individual communication data generated by the data processing unit is less than the individual upper limit size, the total size of all the individual communication data is calculated from all the individual communication data and the data size of the communication frame. The roadside apparatus according to claim 2, wherein a communication frame including the broadcast data for the remaining size of the subtraction is generated. The roadside device
A broadcast buffer for storing the broadcast communication data; and an individual buffer for storing the individual communication data;
The data processing unit
A plurality of broadcast communication data and a plurality of individual communication data are generated, the generated plurality of broadcast communication data are stored in a predetermined order in the broadcast buffer, and the generated plurality of individual communication data are stored in the individual buffer. A plurality of broadcast data at a specific timing is acquired from the broadcast buffer in the storage order, and the acquired plurality of broadcast data is output to the communication control unit, the specific timing A plurality of individual communication data is acquired from the individual buffer in the order of storage and the acquired plurality of individual communication data is output to the communication control unit,
The communication control unit
4. The communication frame is generated based on a plurality of broadcast communication data output by the data processing unit and a plurality of individual communication data output by the data processing unit. A roadside device according to the above. A communication method of a roadside device that performs data communication with an in-vehicle device mounted on a vehicle,
The data processing unit generates data transmitted to the in-vehicle devices of each of the plurality of vehicles as broadcast data using a CPU (Central Processing Unit), and individually transmits the data transmitted to the in-vehicle devices of a specific vehicle. Perform data generation processing to generate using CPU as data,
Compensation size secured for transmission of the broadcast data by the communication control unit receiving the broadcast data generated by the data processing unit and the individual communication data generated by the data processing unit Communication including the broadcast communication data equal to or larger than the predetermined broadcast compensation size and the individual communication data equal to or smaller than the individual upper limit size defined as the upper limit size for limiting the transmission size of the individual communication data. A communication frame generation process for generating a frame using a CPU is performed.
A communication method for a roadside device, wherein a radio wave communication unit performs a radio wave communication process of transmitting the communication frame generated by the communication control unit to an in-vehicle device of each vehicle by radio waves.   A communication program for causing a computer to execute the communication method of the roadside apparatus according to claim 5.

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