JP2010213146A - Communication terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely transfer data of a vehicle, in which emergency communication is required, to the other vehicle even when packet collision frequently occurs. <P>SOLUTION: A control section 6 of a communication terminal device 1 causes a communication section 3 to transmit an interruption request signal, and when receiving a signal indicating the permission of an interruption signal from the other communication terminal device which has received the interruption request signal, the control section 6 causes the communication section 3 to perform packet communication in a partial interval of a slot which has transmitted the interruption request signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication terminal device used for autonomous inter-vehicle communication.

In recent years, an inter-vehicle communication system for assisting safe driving has been studied as a preventive safety technology that leads to accident reduction and collision avoidance. In this inter-vehicle communication, an autonomous distributed TDMA communication protocol (D-TDMA system) is used without using a base station that centrally controls communication terminal apparatuses mounted on each vehicle. This D-TDMA system will be described. FIG. 5 is a diagram for explaining a packet format of a conventional D-TDMA system. As shown in FIG. 5, a frame repeated at a predetermined period _TF is divided into N frames, and a packet is transmitted using a time frame called a slot. As shown in FIG. 5, a packet to be transmitted is composed of four pieces of data, ie, payload data such as preamble, frame information and position information, and transmission cycle information. The frame information indicates the slot usage status. The usage status of each slot includes: FREE in an empty state, ACK in a state in which reception from another communication terminal device is successful, NACK in a state in which reception from another communication terminal device has failed, and packet collision. It is expressed in one of RTC. Conventionally, vehicles existing in the vicinity have determined the slot utilization status by exchanging frame information, and determined the transmission slot used by the own vehicle for transmission. When the received frame information is NACK, that is, when communication with another vehicle fails, the vehicle transmits the next packet with a shorter transmission cycle. As a result, even if communication fails once, the maximum information update distance is within 5 m (for example, see Non-Patent Document 1).
Harada Tomoaki, Suzuki Tokusho, Makito Tomofumi, Ito Shuro, Hayashi Hiroaki, Terada Shigeo “Development of Autonomous Distributed TDMA Inter-Vehicle Communication System” (Information Processing Society of Japan Research Report Vol. 2007 No. 116 Nov 2007)

  However, as in the past, if communication with other vehicles fails and the transmission cycle of packet transmission is shortened, there is a problem that packet collisions occur frequently, and emergency vehicles cannot transmit information preferentially .

  An object of the present invention is to reliably transmit vehicle data requiring emergency communication to other vehicles even when packet collisions occur frequently.

  A communication terminal device according to the present invention is a communication terminal device that is mounted on a host vehicle and performs autonomous decentralized inter-vehicle communication with other surrounding vehicles, and includes packet information to which frame information indicating a slot usage state is added. A communication means for communicating with another communication terminal apparatus; a storage means for storing the frame information received by the communication means from the other communication terminal apparatus; and a first section of a slot of the frame information stored in the storage means, And a control means for controlling the communication terminal device to transmit an interrupt request.

  According to the present invention, even when packet collisions occur frequently, vehicle data that requires emergency communication can be reliably transmitted to other vehicles.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
First, the communication terminal device 1 of the present invention will be described with reference to FIG.

  FIG. 1 is a diagram illustrating the overall concept of a communication terminal device 1 according to the present invention.

As shown in FIG. 1, the communication terminal apparatus 1 includes an antenna 2, a communication unit 3 connected to the antenna 2, a bus 4 connected to the communication unit 3, and a storage unit connected to the bus 4. 5 and the control unit 6.
Note that the communication unit 2 demodulates packet information received by a demodulation unit (not shown) and modulates packet information transmitted by a modulation unit (not shown).

  The storage unit 5 includes an information storage medium (not shown). The information storage medium is configured by at least one of, for example, an HDD and a DVD. The storage unit 5 is a frame for managing frame information obtained from each vehicle participating in the vehicle-to-vehicle communication network, types of vehicles such as police cars, fire engines, ambulances, and general vehicles, the number of packet collisions, and chassis numbers. An information management table is stored. The frame information indicates a slot usage state, a free FREE, an ACK that has been successfully received from another communication terminal device, a NACK that has failed to be received from another communication terminal device, and a packet collision. It is represented by one of the RTCs in the status.

  The control unit 6 includes a CPU (not shown), realizes functions corresponding to the third to sixth layers of the OSI reference model by software, and stores them in the storage unit 5 based on packet information received from the communication unit 3. The updated frame information management table is updated. Further, the control unit 6 generates packet information to be transmitted to the communication unit 3 based on the frame information of the frame information management table stored in the storage unit 5. Further, the control unit 6 adds interrupt request information to the frame information in case of an emergency. On the other hand, when the communication unit 3 receives an interrupt request signal for its own transmission slot, the control unit 6 stops the packet transmission for a certain time of its own transmission slot and resumes the packet transmission after a certain time has elapsed. Do. Note that a competitive interval IFS (Inter Frame Space) is provided at the head of each slot. The contention section IFS is not normally used for communication, but is provided only for use when transmitting / receiving an interrupt request signal of an emergency communication vehicle. In the remaining section, a data communication section used for normal packet communication is provided.

  Next, interrupt processing by the communication terminal device 1 of the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart for explaining interrupt request processing by the communication terminal device 1.

  First, as shown in step S201, the control unit 6 confirms whether a request for emergency communication is transmitted from the sixth layer of the OSI reference model, which is an upper layer of software, as the own vehicle. If YES in step S201, as shown in step S202, when the control unit 6 determines that there is a request for emergency communication, the control unit 6 determines whether the section of the slot that has received the emergency communication request signal is a contention section IFS. And waits until the competitive section IFS is reached.

  In the case of YES in step S202, that is, when the control unit 6 determines that the slot section that has received the emergency communication request signal is the contention section IFS, as shown in step S203, the slot that has received the emergency communication request signal. Determines whether it is a transmission slot used by itself.

If YES in step S203, as shown in step S204, when the control unit 6 determines that the slot that has received the emergency communication request signal is a transmission slot used by itself, an interrupt request signal is received from another vehicle. It is determined whether or not there is.

  If NO in step S204, that is, if the control unit 6 determines that the communication unit 3 has not received an interrupt request signal from another vehicle, the control unit 6 performs normal packet communication to the communication unit 3 as shown in step S205. Make it. Then, as shown in step S206, the control unit 6 determines whether or not the communication is completed. If YES in step S206, that is, if the control unit 6 determines that the communication is completed, step S201 is performed. Perform the process.

  If YES in step S204, that is, if the control unit 6 determines that the communication unit 3 has received an interrupt request signal from another vehicle, as shown in step S207, whether or not the interrupt request signal has collided. Determine whether.

  If YES in step S207, that is, if the control unit 6 determines that the interrupt request signals have collided, as shown in step S208, the control unit 6 indicates to the communication unit 3 that the interrupt request has collided. A signal is transmitted to cause the communication unit 3 to perform normal packet communication as shown in step S205.

  On the other hand, in the case of NO in step S207, that is, when the control unit 6 determines that the interrupt request signals do not collide, as shown in step S209, the communication unit 3 acknowledges that the interrupt request has been accepted. Send a signal.

  Next, as shown in step S <b> 210, the control unit 6 determines which of the interrupt request signal received by the communication unit 3 and the emergency communication of the own vehicle should be prioritized when the own vehicle also wants to perform the emergency communication. .

  If YES in step S210, that is, if the control unit 6 determines that priority should be given to the emergency communication of the host vehicle, as shown in step S211, the first half of the data communication section among the transmission slots used by the communication unit 3 for transmission. The communication unit 3 is caused to perform packet communication in the section. Then, as shown in step S212, the control unit 6 determines whether or not the communication is completed. If YES in step S212, that is, if the control unit 6 determines that the communication is completed, step S201 is performed. Perform the process.

  If NO in step S210, that is, if the control unit 6 determines that the interrupt request signal received by the communication unit 3 should be prioritized, as shown in step S213, data in the transmission slot used by the communication unit 3 for transmission is displayed. In the first half of the communication section, it is determined whether or not the packet communication of the other vehicle that has transmitted the interrupt request signal is completed. In the case of YES in step S213, that is, when the packet communication of the other vehicle that has transmitted the interrupt request signal is completed, the control unit 6 performs data communication among the transmission slots used for transmission by the communication unit 3 as shown in step S214. The communication unit 3 performs packet communication in the second half of the section. Then, as shown in step S212, the control unit 6 determines whether or not the communication is completed. If YES in step S212, that is, if the control unit 6 determines that the communication is completed, step S201 is performed. Perform the process.

  If NO in step S203, that is, if the control unit 6 determines that the slot that has received the emergency communication request signal is not a transmission slot used by itself, as shown in step S215, the control unit 6 It is confirmed whether a communication request is transmitted from the sixth layer of the OSI reference model, which is an upper layer of software. If YES in step S215, that is, if the control unit 6 determines that there is a request for emergency communication, as shown in step S216, the control unit 6 causes the communication unit 3 to transmit an interrupt request signal.

  Next, as shown in step S217, the control unit 6 determines whether or not the communication unit 3 has received an RTC signal indicating that the interrupt request has collided.

  If NO in step S217, that is, if the control unit 6 determines that the communication unit 3 has not received the RTC signal, an ACK signal indicating that the communication unit 3 has accepted the interrupt request, as shown in step S218. Is received. If YES in step S218, that is, if the control unit 6 determines that the communication unit 3 has received an ACK signal, a collision counter indicating the number of packet collisions stored in the storage unit 5 as shown in step S219. Is cleared, and the process of step S210 is performed. On the other hand, if NO in step S218, that is, if the control unit 6 determines that the communication unit 3 has not received the ACK signal, the control unit 6 causes the communication unit 3 to transmit an interrupt request signal again in the next slot, and step S202. Perform the process.

  In the case of YES in step S217, that is, when the control unit 6 determines that the communication unit 3 has received the RTC signal, the frame information management table stored in the storage unit 5 is transferred to the inter-vehicle communication network as shown in step S220. Read information on the type of participating vehicle. Then, as shown in step S <b> 221, the control unit 6 adds 1 to the collision counter indicating the number of packet collisions stored in the storage unit 5. Next, as shown in step S <b> 222, the control unit 6 calculates the priority of communication based on the interrupt request signal from the information on the collision counter and the vehicle type information stored in the storage unit 5. For example, the control unit 6 calculates a higher communication priority as the product of a specific priority predetermined according to the type of each vehicle and the value of the collision counter set in advance for each vehicle is higher. . More specifically, the unique priority of car A is set to “10”, the unique priority of car B is set to “20”, and the unique priority of car C is set to “30”. When the collision counter value is “5”, the collision counter value of the B car is “3”, and the collision counter value of the C car is “1”, the control unit 6 sets the priority of communication by the interrupt request signal to the B car and A Car, then C car. Next, as shown in step S223, the control unit 6 determines whether or not there is a vehicle having the same communication priority as that of the own vehicle by the interrupt request signal.

  In the case of YES in step S223, that is, when the control unit 6 determines that there is a vehicle having the same communication priority order as the own vehicle according to the interrupt request signal, as shown in step S224, the frame stored in the storage unit 5 A chassis number represented by a serial number in the order of the chassis format and the manufacturing number is read from the management information table. And as shown to step S225, the control part 6 calculates the priority of communication by an interruption request signal from the information of the chassis number memorize | stored in the memory | storage part 5. FIG. Specifically, when the chassis number of the A car is “SX31-9000001” and the chassis number of the B car is “AX31-9000002”, the control unit 6 converts the chassis type of the A car from ASCII characters to a decimal number. The value of the body number “838851499000001” is compared with the value of the body number “658851499000002” obtained by converting the chassis type of the B car from ASCII characters to a decimal number. In order. Next, as shown in step S226, the control unit 6 causes the communication unit 3 to wait for transmission of the interrupt request signal by the number of slots corresponding to the calculated priority order of the interrupt request signal.

  In the case of NO in step S223, that is, when the control unit 6 determines that there is no vehicle having the same communication priority as the own vehicle by the interrupt request signal, the control unit 6 sends an interrupt request signal to the communication unit 3 as shown in step S226. The transmission of the interrupt request signal is made to wait for the number of slots corresponding to the priority order of.

After the process of step S226, as shown in step S227, the control unit 6 determines whether or not the number of slots for which the communication unit 3 is waiting for transmission of an interrupt request signal has elapsed. In the case of YES in step S227, that is, when it is determined that the number of slots for which the communication unit 3 is waiting for transmission of the interrupt request signal has elapsed, the control unit 6 causes the communication unit 3 to transmit the interrupt request signal, The process of S202 is performed.

  Next, a specific example of interrupt processing by the communication terminal device 1 of the present embodiment will be described with reference to FIGS.

  FIG. 3 is a diagram for explaining a specific example of the interrupt request processing in the inter-vehicle communication system using the communication terminal device 1 according to the present embodiment. When the B car makes an interrupt request for the slot 2 used for packet transmission by the C car. Is shown. Each vehicle is equipped with a communication terminal device 1 having the same device configuration.

  As shown in FIG. 3, each slot has a contention section IFS at the head of the slot for interrupt processing. The data communication section which is the remaining section of the slot is used for packet communication. In the case of normal packet communication, the communication unit 3 of the A car occupies the slot 1 and transmits a packet. The control unit 6 of the B car that wants to perform the interrupt communication causes the communication unit 3 of the B car to transmit an interrupt request signal to the contention section IFS of the slot 2 and starts packet communication in the data communication section of the slot 2. When receiving the interrupt request signal transmitted from the communication unit 3 of the B vehicle, the communication unit 3 of the C vehicle transmits an ACK signal permitting interruption to the B vehicle. In addition, the control unit 6 of the C car uses information for allowing the communication of the B car and waiting for the communication of the C car for a part of the data communication section of the slot 2 in the frame information management table stored in the storage unit 5. Update. When the data communication section of slot 2 is divided for the B car and the C car, the dividing method is not limited to equal division and may be divided at any ratio. In addition, a frame information management table including priority information for the interrupt request signal of each vehicle is stored in each storage unit 5 of the A vehicle, the B vehicle, and the C vehicle. Therefore, when priority information for the interrupt request signal of the B car is higher than that of the C car, the B car performs packet communication in the first half of the data communication section of the slot 2, and the C car performs the second half of the data communication section of the slot 2. Packet communication is performed with. On the other hand, when the priority information for the interrupt request signal of the B car is lower than the C car, the C car performs packet communication in the first half of the data communication section of the slot 2, and the B car performs the second half of the data communication section of the slot 2. Packet communication is performed with. Car C cannot perform packet communication with the original data length by an interrupt request signal from Car B. In this case, the control unit 6 of the car C causes the communication unit 3 to transmit a packet with coarse data. For example, the control unit 6 causes the communication unit 3 to transmit a packet with the accuracy of the vehicle position, the vehicle speed, and the UTC information being half the original accuracy.

  FIG. 4 is a diagram illustrating a specific example of processing when an interrupt request signal collides in the inter-vehicle communication system using the communication terminal device 1 of the present embodiment. FIG. 4 shows a case where slot 1 is used as a C car, slot 2 is used as a D car, slot 3 is used as an E car as a transmission slot, and A car and B car make an interrupt request. Each vehicle is equipped with a communication terminal device 1 having the same device configuration. Further, it is assumed that the interrupt request signal for the B car has a higher priority than the interrupt request signal for the A car.

  As shown in FIG. 4, the control unit 6 of the A car that wants to perform the interrupt communication causes the communication unit 3 of the A car to transmit an interrupt request signal in the contention section IFS of the slot 1. On the other hand, the control unit 6 of the B car that wants to perform the interrupt communication causes the communication unit 3 of the B car to transmit an interrupt request signal to the competition section IFS of the slot 1. At this time, in car C having slot 1 as a transmission slot, the interrupt request signal transmitted from car A and the interrupt request signal transmitted from car B collide. At this time, an RTC signal is transmitted from the communication unit 3 of the C car. When receiving the RTC signal, the control unit 6 for the A car and the control unit 6 for the B car follow the processing from step S220 to step S227 in FIG. 2 and then wait for a predetermined slot to transmit an interrupt request. Do. Since the interrupt request signal of the B car has a higher priority than the interrupt request signal of the A car, the control unit 6 of the B car causes the communication unit 3 to transmit the interrupt request signal to the contention section IFS of the slot 2. On the other hand, the control unit 6 of the A vehicle causes the communication unit 3 to transmit an interrupt request signal in the competitive section IFS of the slot 3.

  As shown in FIG. 4, the D vehicle that has received the interrupt request signal from the B vehicle transmits an ACK signal that permits interruption to the B vehicle. In addition, the control unit 6 of the D car uses the information that permits the communication of the B car and waits for the communication of the D car for a part of the data communication section of the slot 2 in the frame information management table stored in the storage unit 5. Update. The control unit 6 of the B car causes the communication unit 3 to perform packet communication for a part of the data communication section of the slot 2. When this packet communication is finished, the control unit 6 of the D car causes the communication unit 3 to perform packet communication for the remaining section of the data communication section of the slot 2.

  As shown in FIG. 4, the control unit 6 for the A car causes the communication unit 3 to wait for the interrupt request process for the slot 2 used for the interrupt request process for the B car, and performs the interrupt request process for the communication unit 3 for the slot 3. Start. The E vehicle that has received the interrupt request signal from the A vehicle transmits an ACK signal permitting interruption to the A vehicle. In addition, the control unit 6 of the E car allows the communication of the A car and allows the communication of the E car to wait for a part of the data communication section of the slot 3 in the frame information management table stored in the storage unit 5. Update. The control unit 6 of the A vehicle causes the communication unit 3 to perform packet communication for a part of the data communication section of the slot 3. When this packet communication is completed, the control unit 6 of the E vehicle causes the communication unit 3 to perform packet communication for the remaining section of the data communication section of the slot 3.

  As described above, according to this embodiment, even when packet collisions frequently occur in inter-vehicle communication, a vehicle that requires emergency communication can perform interrupt request processing, so that packet communication can be reliably performed. it can.

  The communication terminal apparatus according to the present invention is useful for a communication terminal apparatus used in a self-sustained distributed inter-vehicle communication system.

The figure explaining the whole concept of the communication terminal device 1 of Embodiment 1 of this invention The flowchart figure explaining the interruption process by the communication terminal device 1 of Embodiment 1 of this invention. The figure explaining the specific example of an interruption request | requirement process in the inter-vehicle communication system using the communication terminal device 1 of this embodiment. The figure explaining the specific example of a process in case an interruption request signal collides in the inter-vehicle communication system using the communication terminal device 1 of this embodiment. The figure explaining the packet format of the conventional D-TDMA system

DESCRIPTION OF SYMBOLS 1 Communication terminal device 2 Antenna 3 Communication part 4 Bus 5 Memory | storage part 6 Control part

Claims (3)

A communication terminal device that is mounted on the host vehicle and performs autonomous decentralized inter-vehicle communication with other surrounding vehicles,
A communication means for communicating packet information to which frame information indicating the usage status of the slot is added with another communication terminal device;
Storage means for storing frame information received by the communication means from the other communication terminal device;
Control means for controlling the communication terminal apparatus to transmit an interrupt request in the head section of the slot of the frame information stored in the storage means.   The communication terminal apparatus according to claim 1, wherein the control unit performs packet communication in a part of a slot in which the interrupt request is transmitted to the communication unit.   The control means, when there is an interrupt request from the other communication terminal device in the head section of the slot used by the communication means for communication, a part of the slot used by the communication means for communication The communication terminal apparatus according to claim 1, wherein the packet communication is stopped and the packet communication is resumed in the remaining section.