JP5159862B2 - DSRC OBE - Google Patents

Description

  The present invention relates to a DSRC (Dedicated Short-Range Communication) vehicle-mounted device used in an ETC (Electronic Toll Collection) system of ITS (Intelligent Transport System). is there.

  Conventionally, an automatic toll collection system (ETC) for toll roads is well known, and in Japan, DSRC is used as its communication method. DSRC is standardized as ARIB STD-T75 by the Association of Radio Industries and Businesses (ARIB).

  A communication frame used in DSRC is composed of a plurality of slots, and a road unit assigns which slot is used. Mobile stations such as in-vehicle devices communicate using slots assigned to themselves. In downlink communication from the roadside unit to the vehicle-mounted device, a plurality of message data slots (MDS) can be allocated following the frame control message slot (FCMS) (FCMS, MDS (1, 1, 2) shown in FIGS. 2,))), the OBE needs to process all assigned slots.

  However, if a large number of MDSs are assigned, such as processing individual communications and broadcast communications at the same time, or if processing capacity is temporarily under pressure due to cooperation with a car navigation system, data processing will not be in time. There is a problem that all received MDSs cannot be processed until the next frame is received.

  In the following Patent Document 1, when the data transmitted from the road device and received by the vehicle-mounted device cannot be stored in the reception data storage buffer of the vehicle-mounted device, a negative response is transmitted from the vehicle-mounted device to the road device through the response channel, Based on the negative response of the response channel, the road unit dynamically adjusts the slot allocation frequency of the slots allocated to the on-board unit based on the negative response of the response channel. A method is disclosed.

  In this method, since the road unit recognizes the processing performance of the OBE in real time and slot allocation adjustment can be performed only when the processing performance of the OBE is not in time, countermeasures when the processing performance temporarily fails This is an effective method.

  On the other hand, in Patent Document 2 below, the processing load detection means is provided in the vehicle-mounted device, and when the data is received from the roadside device, the CPU load state or the broadcast information and the number of unprocessed information of the individual information are detected by the processing load detection means. Discloses a method for prohibiting the reception operation of broadcast information when it is determined that has exceeded a preset load threshold.

JP 2007-318646 A JP 2009-123083 A

  However, the method according to Patent Document 1 has a problem in that an uplink from an in-vehicle device to a road device is indispensable, so that it cannot cope with a situation where a service is performed using only broadcast communication.

  In addition, when the road unit controls the allocation frequency of broadcast (information) data, if there are multiple on-board units with different processing capabilities in the communication area of the road unit, Therefore, there is a problem that it is impossible to transmit data optimally to the vehicle-mounted device having a high processing capability.

  In the method disclosed in Patent Document 2, broadcast (information) data is sequentially stored in a plurality of received data storage buffers. However, the number of broadcast data that have not been processed (that is, the received data storage buffer being used) If the number is equal to or greater than a preset number (for example, N), the broadcast data is not recorded when the broadcast data is received (that is, not stored in the received data storage buffer). When one piece of broadcast data that has not been processed in the prohibited state is processed and the number of received data storage buffers in use reaches N-1, the reception prohibition is immediately canceled and the reception of the broadcast data is resumed. As a result, the number of received data storage buffers in use immediately returns to N, and the operation of entering the reception prohibited state is repeated again.

  As shown in FIG. 5, ARIB STD-T75 stipulates that data of 193 octets or more is divided into 193 octets of LPDU (Link Protocol Data Unit) in layer 2 of the base station and transmitted. An application sub layer (ASL: Application Sub Layer) that is an upper layer of layer 2 and layer 7 defined by ARIB STD-T75 is standardized by ARIB STD-T88, and is a maximum transmission unit (MTU: Maximum Transmission Unit). ) Is 522 octets.

  Therefore, the broadcast service data is handled in 522 octets in the ASL, and the broadcast service data is divided into three LPDUs in layer 7 and layer 2 and transmitted to the vehicle-mounted device. The in-vehicle device can receive and assemble all the three LPDUs and provide them to the user as one service data.

  For this reason, broadcast data reception prohibition and permission determination are made consistent, such as reception prohibition when the number of received data storage buffers in use is N or more, and reception permission when the number of reception data storage buffers is less than N. As described above, since the reception of broadcast data is resumed and the reception data is prohibited as soon as the broadcast data is received as described above, if the configuration is implemented only with the truth of the condition, the 3 One LPDU cannot be received and cannot be assembled as service data. Therefore, there is a problem that service data cannot be provided to the user.

  The present invention eliminates such problems of the prior art, and in an in-vehicle device that performs communication using DSRC, an uplink from the on-vehicle device to the road unit is unnecessary, and the capacity of the on-vehicle device having a high processing capacity is wasted. Therefore, it is an object of the present invention to provide a DSRC in-vehicle device capable of providing more service data to a user in response to a situation where processing capacity is temporarily exceeded in broadcast data processing. .

  The present invention relates to a DSRC in-vehicle device of a DSRC system that exchanges data between a road device installed on a road and an on-vehicle device, and performs communication control for performing transmission / reception processing of the data exchanged with the road device And a plurality of received data storage buffers for storing the data, and when the data received by the communication control unit is broadcast data, the number of received data storage buffers used is a predetermined number of reception prohibited buffers The broadcast data received by the communication control unit is stored by switching between prohibition of reception and resumption of reception between a predetermined number of reception resumption permission buffers smaller than the number of reception inhibition buffers by a desired number of 2 or more. And a data processing unit.

  In this invention, the uplink from the vehicle-mounted device to the roadside device is unnecessary, and the processing capability is temporarily exceeded in the processing of broadcast data without wasting the capability of the vehicle-mounted device with high processing capability. Correspondingly, it is possible to provide a DSRC vehicle-mounted device that can provide more service data to the user.

It is a block diagram which shows the structure of the DSRC onboard equipment by one embodiment of this invention. It is an operation | movement flowchart at the time of the DSRC onboard equipment of FIG. 1 receiving data from a roadside machine. It is an operation | movement flowchart at the time of processing the service data of the DSRC onboard equipment of FIG. It is a figure for demonstrating the effect of the process of the reception data of the DSRC onboard equipment of FIG. It is a figure for demonstrating the form of the data transmission from a general roadside machine. It is a figure for demonstrating the problem of the processing of the reception data in an onboard equipment.

  Hereinafter, a DSRC vehicle-mounted device according to the present invention will be described with reference to the drawings according to an embodiment. In addition, in each figure, the same or an equivalent part is shown with the same code | symbol, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a DSRC vehicle-mounted device according to an embodiment of the present invention. In FIG. 1, the DSRC on-vehicle device 1 is centered on a CPU 4 that performs overall control, an HMI (human machine interface) device 9, a communication circuit 3, an EEPROM 13, a power supply circuit 14, an external device I / F (interface) 16, and a SAM ( Security application module (Security-Application-Module) 18 is connected.

  An antenna 2 is connected to the communication circuit 3. The HMI device 9 includes, for example, an operation unit 10 including a volume change button, a sound output unit 11 including a speaker, a light output unit 12 including an LED, and the like. An external power supply 15 is connected to the power supply circuit 14, an external device 17 such as a car navigation device is connected to the external device I / F (interface) 16, and an IC card I / F (interface) 19 is connected to the SAM 18. An external IC card 20 is connected via The CPU 4 includes a communication control unit 5 and a data processing unit 6, and the data processing unit 6 further has a plurality of (first predetermined number N1 (N1: integer equal to or greater than 3)) predetermined received data storage buffer. The received data storage area 7 having 8 is included.

  FIG. 2 is an operation flowchart when the on-board DSRC device of FIG. 1 receives data from a roadside device. Next, the operation will be described with reference to the flowchart of FIG.

  First, the DSRC in-vehicle device 1 determines whether or not the received data from the roadside device is MDS by the communication control unit 5 (S001). If the received data is MDS (YES in S001), the data processing unit 6 determines whether the received data is broadcast (information) data or individual (information) data (S002).

  If the received data is broadcast data in S002 (YES in S002), it is determined whether or not the broadcast data reception is permitted (S003). If the broadcast reception is permitted in S003 (YES in S003), the number of received data storage buffers 8 in use in the received data storage area 7 and the number of reception prohibited buffers (second predetermined number N2 (N2: N1 The following positive integers)) are compared (S004). Assuming that the number of reception-prohibited buffers is N2 (for example, N2 = 5), when the number of received data storage buffers in use is equal to or greater than the number of reception-prohibited buffers N2 in S004 (YES in S004), the broadcast data reception prohibited state is set. (S005).

  In S003, if the broadcast data reception permission state is not set (NO in S003), the number of received data storage buffers in use and the number of reception restart permission buffers (third predetermined number N3 (N3: 0 or N2- N3 ≧ 2) (S006) If the number of reception restart permission buffers is a third predetermined number N3 (for example, N3 = 0), the number of received data storage buffers in use is the reception restart permission in S006. When the number of buffers is N3 or less (YES in S006), the broadcast data reception permission state is set (S007).

  Subsequently, it is determined whether or not broadcast data reception is prohibited (S008). If broadcast data reception is prohibited (YES in S008), the process is terminated without storing the received data in the received data storage buffer 8. .

  If the received data is individual (information) data in S002 (NO in S002) and if not in the broadcast data reception prohibited state in S008 (NO in S008), whether the received data is divided data or not Is determined (S009).

  If the received data is not divided data in S009 (NO in S009), the received data is stored in the received data storage buffer 8 that is not in use (S016), and the number of used received data storage buffers is incremented by +1 (S017). The number of unprocessed service data is incremented by +1 (S018), and the process ends (in the case of broadcast data, service data is data composed of one or more broadcast data sent from a road device) (See FIG. 5)).

  If the received data is divided data in S009 (YES in S009), it is determined whether the divided data to be combined with the received data is stored in the received data storage buffer 8 (S010).

  In S010, if the divided data to be combined with the received data is not stored in the received data storage buffer 8 (NO in S010), the received data is stored in the received data storage buffer 8 that is not in use (S014) and is being used. The number of received data storage buffers is incremented by +1 (S015), and the process ends.

  In S010, if the divided data to be combined with the received data is stored in the received data storage buffer 8 (YES in S010), the received data is stored in the received data storage buffer 8 in which the divided data to be combined is stored. It combines (S011), and it is determined whether the assembly of the divided data is completed (S012).

  If the assembly of the divided data is not completed in S012 (NO in S012), the process is finished. In S012, when the assembly of the divided data is completed (YES in S012), the number of unprocessed service data is incremented by +1 (S013), and the process ends.

  That is, the number of reception inhibition buffers with respect to the number of reception data storage buffers 8 (first predetermined number N1 (N1: integer equal to or greater than 3)) is set to a second predetermined number N2 (N2: positive integer equal to or less than N1). The number of restart permission buffers is set to a third predetermined number N3 (N3: 0 or N2−N3 ≧ 2 as a positive integer), and the difference between N2 and N3 is set large (2 or more) to switch between reception inhibition and reception restart permission. Hysteresis is provided to prevent frequent switching of reception prohibition and reception resumption permission (for example, every time).

  FIG. 3 is an operation flowchart for processing service data of the DSRC on-vehicle device of FIG. Next, the operation will be described according to the operation flowchart of FIG. The operation of the operation flowchart of FIG. 3 is periodically executed.

  In FIG. 3, the DSRC on-vehicle device 1 determines whether or not the service data processing state is service data processing (S201). If the service data processing state is not “processing service data” in S201 (NO in S201), it is determined whether or not the number of unprocessed service data is 0 (S202).

  In S202, if the number of unprocessed service data is 0 (YES in S202), the process ends. In S202, if the number of unprocessed service data is not 0 (NO in S202), processing of unoutput service data is started (S203), the service data processing state is set to “processing service data” (S204), and processing is performed. Finish.

  On the other hand, if the service data processing state is “processing service data” in S201 (YES in S201), it is determined whether the processing of the service data is completed (S205).

  If the service data processing has not been completed in S205 (NO in S205), the processing ends. If the service data processing is completed in S205 (YES in S205), the number of unprocessed service data is decremented by -1 (S206), and the service data processing state is set to "IDLE (empty state)" (S207). The number of in-use received data storage buffers is decremented by -1 (S208), and the process ends.

The service data to be processed may be output to the external device 17 by the external device I / F 16 or may be output by the HMI device 9 of the vehicle-mounted device.
In addition, as the number of reception prohibition buffers and the number of reception restart permission buffers, values preset in the program of the vehicle-mounted device 1 may be used, or values input from the external device 17 may be used. Alternatively, the value input from the external device 17 may be stored in the EEPROM 13 and the value stored in the EEPROM 13 may be used.

  According to the DSRC on-vehicle device 1 according to Embodiment 1 of the present invention, when the data processing unit determines that the broadcast data is received from the roadside device, the usage status of the received data storage buffer in the received data storage area is determined. If the total number of received data storage buffers is the first predetermined number N1 (N1: integer greater than or equal to 3), the number of received data storage buffers used is less than the second predetermined number N2 (N2: N1 or less). A function of discarding broadcast data received thereafter when the received data storage buffer is used is a third predetermined number N3 (N3: 0 or a positive integer N2−N3 ≧). 2) A function that resumes the process of storing broadcast data in the received data storage buffer when it becomes less than or equal to (in a broader sense, the number of buffers that prohibit reception and the number of buffers that allow reception restart are two or more) With the desired difference For example, if the second predetermined number N2 is set to “5” and the third predetermined number N3 is set to “0”, the vehicle-mounted device can set the broadcast data according to the remaining amount of its buffer area. After limiting the amount of processing and returning from the broadcast data reception disabled state to the broadcast data reception restart enabled state, as shown in FIG. 4, at least five broadcast data until the next broadcast data reception disabled state is entered. Can receive all the service data divided into three, corresponding to the case where the processing capacity is temporarily exceeded by only processing the broadcast data, to the user More information can be provided.

  In addition, by using the values input from the external device 17 as the number of reception prohibition buffers and the number of reception resumption permission buffers, services provided to users in the future will be diversified, and service data transmitted by roadside equipment Even when the number increases, it is possible to provide more information to the user in response to the case where the processing capacity is temporarily exceeded without changing the program of the vehicle-mounted device 1.

  In addition, by storing the value input from the external device 17 in the EEPROM 8, and using the value stored in the EEPROM 8 as the number of reception prohibition buffers and the number of reception restart permission buffers, an external device for shipping inspection at the time of shipment from the manufacturer. If the values input from the device 17 are stored in the EEPROM 8, even if the device is used without being connected to the car navigation, the services provided to the user will be diversified in the future, and the number of service data transmitted by the road unit Even in the case of increasing, it is possible to provide more information to the user in response to a case where the processing capacity is temporarily exceeded without changing the program of the vehicle-mounted device 1.

  DESCRIPTION OF SYMBOLS 1 Onboard equipment, 2 Antenna, 3 Communication circuit, 4 CPU, 5 Communication control part, 6 Data processing part, 7 Received data storage area, 8 Received data storage buffer, 9 HMI apparatus, 10 Operation means, 11 Sound output means, 12 Optical output means, 13 EEPROM, 14 power supply circuit, 15 power supply, 16 external device I / F, 17 external device, 18 SAM, 19 IC card I / F, 20 IC card.

Claims (4)

A DSRC in-vehicle device of a DSRC system that exchanges data between a road device installed on the road and the on-vehicle device,
A communication control unit for performing transmission / reception processing of the data exchanged with the road device;
A plurality of reception data storage buffers for storing the data, and when the data received by the communication control unit is broadcast data, the number of reception data storage buffers used is a predetermined number of reception inhibition buffers and the reception inhibition A data processing unit for storing the broadcast data received by the communication control unit by switching between prohibition of reception and resumption of reception between a predetermined number of reception restart permission buffers smaller than a desired number by two or more than the number of buffers When,
A DSRC in-vehicle device characterized by comprising:   An external device I / F is provided, and the data processing unit uses a value input from the external device via the external device I / F as at least one of the reception prohibition buffer number and the reception restart permission buffer number. The DSRC in-vehicle device according to claim 1.   The data processing unit includes an external device I / F and a non-volatile memory, and the data processing unit assigns a value input from the external device via the external device I / F to at least one of the reception prohibition buffer number and the reception restart permission buffer number. The DSRC on-vehicle device according to claim 1, wherein a value stored in a nonvolatile memory is used.   The data processing unit has a first predetermined number N1 (N1: integer greater than or equal to 3) of received data storage buffers having a predetermined storage capacity for storing data, and the number of reception inhibition buffers is a second predetermined number N2 (N2 : A positive integer less than or equal to N1), the number of reception restart permission buffers is a third predetermined number N3 (N3: 0 or a positive integer, N2−N3 ≧ 2), and the number of received data storage buffers used is the reception prohibition 4. The broadcast data received after the number of buffers is discarded, and the process of storing the received broadcast data in the received data storage buffer is resumed when the number of reception restart permission buffers is less than the number. The DSRC on-vehicle device according to any one of the above.

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