JP2011003989A - Communication device - Google Patents

Abstract

Communication is performed with priority given to communication with an information providing apparatus.
A communication device is configured to set a vehicle-to-vehicle transmission prohibited period based on a reception timing of a reply packet, and to a vehicle-to-vehicle transmission prohibited period setting unit and a reception timing of a data packet from another terminal. Road-to-vehicle transmission prohibition period setting unit 16 that sets the transmission timing of the data packet from the next time of the roadside machine as a road-to-vehicle transmission prohibition period, and a reply packet that generates a reply packet indicating the detection result of the data packet from another terminal When the reception timing of the data packet from the generation unit 18 and another terminal is the road-to-vehicle transmission prohibited period, the transmission of the generated reply packet is prohibited, and the reception timing is a period other than the road-to-vehicle transmission prohibited period. In some cases, the generated reply packet is transmitted, and data packets are transmitted during periods other than the vehicle-to-vehicle transmission prohibited period and the road-to-vehicle transmission prohibited period. And a, a transmission circuit 20 for transmitting.
[Selection] Figure 1

Description

  The present invention relates to a communication device.

  2. Description of the Related Art Conventionally, there is known a technique for transmitting information by broadcasting (broadcasting) individual wireless terminal devices to neighboring wireless terminal devices without using a control station such as a base station (see Patent Document 1). reference).

  The wireless terminal device described in Patent Document 1 monitors slot occupancy information in units of frames, and exchanges information with other terminals by embedding slot occupancy information in a transmission packet in addition to transmission data of the terminal itself. To do. The frame is composed of, for example, 100 ms, and each slot is occupied by a different terminal.

JP 2007-28550 A

  However, the technique of Patent Document 1 is premised only on communication between terminals such as inter-vehicle communication, and does not consider road-to-vehicle communication in which a roadside device that provides information and a terminal communicate with each other. Further, in an environment where road-to-vehicle communication and vehicle-to-vehicle communication coexist, it is necessary to reliably provide information to the driver. For this reason, there is a demand for improving the service quality of road-to-vehicle communication and raising the priority over vehicle-to-vehicle communication.

  Moreover, when the technology of Patent Document 1 is used in an environment where road-to-vehicle communication and vehicle-to-vehicle communication coexist, road-to-vehicle communication data and vehicle-to-vehicle communication data collide, and road-to-vehicle communication cannot be prioritized. There is a problem.

  The present invention has been proposed to solve the above-described problems, and an object of the present invention is to provide a communication device capable of communicating with each other while giving priority to communication with an information providing device.

  The communication device according to the first aspect of the present invention is a receiving device for receiving a first data packet and a reply packet transmitted from another communication device, and a second data packet transmitted from an information providing device, and the receiving device. A first transmission prohibition period setting means for setting a first transmission prohibition period indicating a data packet transmission prohibition period based on the reception timing of the reply packet when the reply packet is received by When the second data packet is received by the means, based on the reception timing of the second data packet, the transmission timing of the second data packet from the next time of the information providing device is set to the second transmission. A second transmission prohibition period setting unit that sets the prohibition period; and when the first data packet is received by the reception unit, A reply packet generating means for generating a first reply packet indicating a detection result of one data packet, and when the reception timing of the first data packet by the receiving means is the second transmission prohibition period, When the transmission of the first reply packet generated by the reply packet generator is prohibited and the reception timing of the first data packet is a period other than the second transmission prohibition period, the reply packet generator First reply packet transmitting means for transmitting the first reply packet generated by the above and data packet transmitting means for transmitting a data packet in a period other than the first and second transmission prohibition periods. Yes.

  A second aspect of the present invention is the communication apparatus according to the first aspect, wherein communication use indicates a transmission timing of the information providing apparatus based on a reception timing of the second data packet received by the reception unit. A data packet generating unit configured to generate information and generate a first data packet including the generated communication usage information, wherein the data packet transmitting unit transmits the first data packet generated by the data packet generating unit; To do.

  A third aspect of the present invention is the communication apparatus according to the second aspect, wherein the second transmission prohibition period setting means is based on the communication use information included in the second data packet. Set the transmission prohibition period.

  The invention according to claim 4 is the communication apparatus according to claim 2 or 3, wherein the data packet generation means transfers the number of times the communication usage information is transferred from the communication apparatus to another communication apparatus. If the number of transfers is included in the received first data packet, the first data packet not including the communication usage information is generated if the number of transfers is equal to or greater than the threshold, and the number of transfers is a threshold If it is below, the transfer count is incremented by 1, and a first data packet including the new transfer count is generated.

  A fifth aspect of the present invention is the communication apparatus according to any one of the first to fourth aspects, wherein the second data packet is received when the second data packet is received by the receiving unit. Second reply packet transmitting means is further provided for transmitting the second reply packet within a predetermined time from the packet reception timing.

  A sixth aspect of the present invention is the communication apparatus according to the fifth aspect, wherein the reception unit further receives the second reply packet, and the second transmission prohibition period is received by the reception unit. Based on the reception timing of the second reply packet, the transmission timing of the second data packet after the next time of the information providing apparatus is set as the second transmission prohibition period.

  According to the first aspect of the invention, the information providing apparatus prohibits the transmission of the first reply packet at the next transmission timing of the information providing apparatus and transmits the first reply packet during a period other than the transmission timing. It is possible to communicate with other communication devices while giving priority to communication with.

  According to the second aspect of the present invention, the transmission timing of the information providing apparatus can be notified to another communication apparatus by transmitting the first data packet including the communication usage information indicating the transmission timing of the information providing apparatus. it can.

  According to the invention of claim 3, the first data packet including the communication usage information is received, and the second transmission prohibition period is set based on the communication usage information included in the received first data packet. Thus, even if the information providing apparatus is not in direct communication, the communication of the information providing apparatus can be prioritized.

  According to the invention of claim 4, by restricting the transfer of the first data packet including the communication usage information, it is possible to prevent the communication of the communication device far away from the information providing device from being restricted.

  According to the fifth aspect of the present invention, the transmission timing of the information providing apparatus can be notified to other communication apparatuses by using the second reply packet having a simple configuration.

  According to the sixth aspect of the present invention, the information providing apparatus can be configured by simply receiving the second reply packet having a simple configuration by setting the second transmission prohibition period based on the reception timing of the second reply packet. Communication can be prioritized.

It is a block diagram which shows the structure of the communication apparatus of the radio | wireless communication network which concerns on embodiment of this invention. It is a figure which shows the structure of the basic transmission period transmitted / received by a communication apparatus. It is a figure which shows the detection information of a reception detection packet and a collision detection packet, (A) can receive the data packet of another terminal with an own terminal, and when there is no data packet collision, (B) is data with an own terminal. This is a case where a packet can be received and there is a data packet collision. It is a state transition diagram of a communication apparatus. It is a flowchart which shows the process routine of a "data packet transmission process". It is a flowchart which shows the process routine of the "reply packet reception process with respect to the data of the own terminal." It is a timing chart for demonstrating the transmission prohibition period between vehicles. It is a flowchart which shows the processing routine of a "signal reception process". It is a timing chart for demonstrating the transmission prohibition period between vehicles. It is a timing chart regarding a transmission prohibition period when the own terminal receives a reply packet (collision detection packet). It is a flowchart which shows the processing routine of a "reply packet transmission process". It is a timing chart for demonstrating the transmission prohibition period for between-vehicles set after the own terminal transmits a reception detection packet. It is a timing chart for demonstrating the transmission prohibition period between vehicles. It is a figure for demonstrating the collision of a road-vehicle data packet and a vehicle-vehicle data packet. It is a figure explaining the communication situation of the roadside machine and vehicles A, B, and C when the communication device concerning the embodiment of the present invention is carried in vehicles A and B. It is a timing chart which shows the data which a roadside machine and vehicles A, B, and C transmit / receive. It is a timing chart which shows the data which a roadside machine and vehicles A, B, and C transmit / receive. It is a figure which shows the state which the communication apparatus mounted in the vehicle A transmits the reply packet for road-vehicles. It is a figure which shows the timing chart of the transmission / reception data of a roadside machine and vehicles A, B, and C when the communication apparatus mounted in the vehicle A transmits the reply packet for road-to-vehicle. It is a flowchart which shows the 2nd processing routine of a "reply packet transmission process."

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

[First Embodiment]
FIG. 1 is a block diagram showing a configuration of a communication device of a wireless communication network according to the first embodiment of the present invention. The wireless communication network is dynamically configured by each communication device broadcasting a packet. Hereinafter, a communication device to be described is referred to as a self terminal, and a communication device around the self terminal is referred to as a peripheral terminal or another terminal. The communication device not only communicates with peripheral terminals (vehicle-to-vehicle communication) while being mounted on a moving body such as a vehicle, but also communicates with a roadside device that is installed on a road and provides various information (road Vehicle-to-vehicle communication).

  The communication device receives a packet transmitted from another wireless terminal device via the reception antenna 11, and a packet that detects a received packet and detects at which slot (at which timing) the received packet is transmitted. Detection unit 13, vehicle-to-vehicle transmission prohibition period setting unit 14 that sets a vehicle-to-vehicle transmission prohibition period based on the detected packet timing information, and demodulating and receiving data transmitted from the detected packet And a packet demodulator 15 for generating information.

  Further, the communication device includes a road-to-vehicle transmission prohibition period setting unit 16 that sets a road-to-vehicle transmission prohibition period based on the detected packet timing information, and a packet generation unit 17 that generates a packet based on the transmission information. A reply packet generator 18 that generates a reply packet based on the demodulated packet, a transmission timing controller 19 that controls the transmission timing of the packet, and a transmission circuit 20 that transmits the generated packet via the antenna 21. And.

  The inter-vehicle transmission prohibition period refers to a period during which transmission of data packets of the own terminal is prohibited in order to ensure communication between other vehicles (peripheral terminals). The road-to-vehicle transmission prohibition period refers to a period during which transmission of data packets and reply packets of the terminal itself is prohibited in order to ensure communication between the roadside machine and the vehicle.

  The reply packet generator 18 generates a reception detection packet and a collision detection packet as a reply packet. Specifically, the reply packet generator 18 determines whether or not the packet is normally detected based on the packet demodulated by the packet demodulator 15. If the packet is normally detected, the packet is normally detected. A reception detection packet indicating that is generated. In addition, when a plurality of packets are detected at the same timing (the same slot), the reply packet generation unit 18 generates a collision detection packet indicating that the packets collide.

  The transmission timing control unit 19 controls the transmission timing of the data packet generated by the packet generation unit 17 and the return packet generated by the return packet generation unit 18 with respect to the transmission circuit 20. In particular, for the reply packet, the transmission timing control unit 19 controls the transmission circuit 20 so as to be surely transmitted after a predetermined period (same slot as the reception timing) after the reception of the data packet is completed. The predetermined time is common to all terminals. Therefore, when a large number of terminals are crowded around, reply packets from the terminals collide. Although this will be described in detail later, this is used for detecting a hidden terminal by intentionally colliding a reply packet.

  FIG. 2 is a diagram illustrating a configuration of a basic period transmitted and received by n communication apparatuses. A data packet and a reply packet indicate one transmission / reception combination. One basic period is set to 100 msec, for example, and is divided into n slots. In each slot, there is one set of a data packet and a reply packet indicating a reply to the data packet, and there are n combinations in FIG.

  The data packet includes a data packet (vehicle-to-vehicle data packet) transmitted from each communication device and a data packet (road-to-vehicle data packet) transmitted from the roadside device. The inter-vehicle data packet includes inter-vehicle data and road-to-vehicle usage information. Road-to-vehicle usage information includes, for example, information provided from roadside devices (road information, traffic jam information, etc.) and road-to-vehicle communication usage time information (information indicating occupied slots). In the communication area where there is no roadside device, the road-to-vehicle usage information is blank. The return packet includes a reception detection packet and a collision detection packet.

  In this embodiment, the reception detection packet and the collision detection packet have different packet time lengths. For example, the reception detection packet has a shorter time length than the collision detection packet.

  FIG. 3 is a diagram showing detection information of the reception detection packet and the collision detection packet. FIG. 3A shows that when the terminal can receive the data packet of another terminal and there is no data packet collision, FIG. This is a case where the terminal can receive the data packet and there is a data packet collision.

  When each terminal receives only one data packet, it returns a reception detection packet (FIG. (A)), and when it receives a plurality of data packets, it returns a collision detection packet (FIG. (B)). .

  Each terminal receives only the reception detection packet when the duration is shorter than the predetermined value based on the time during which the reception power of the reply packet continues, and only the collision detection packet when the duration is longer than the predetermined value. Alternatively, it can be determined that both the reception detection packet and the collision detection packet are received.

  Each terminal may use two reply packets in which the combination of subcarriers to be used is changed. This makes it possible to determine whether or not two or more types of return packets are included depending on the combination of subcarriers to be used. Each terminal may transmit a reply packet a plurality of times, or may use a spread spectrum signal as a reply packet. As described above, the formats of the plurality of types of reply packets are not particularly limited.

  FIG. 4 is a state transition diagram of the communication apparatus. The communication apparatus transits the states of “reception standby state”, “data packet transmission process”, “reply packet reception process for data of own terminal”, “signal reception process”, and “reply packet transmission process”.

  Specifically, in a reception standby state, the communication apparatus shifts to a data packet transmission process when there is no reception signal and there is data to be transmitted, and shifts to a signal reception process when a reception signal is detected.

  When the data packet cannot be transmitted in the data packet transmission process, the communication apparatus shifts to a reception standby state. When the data packet transmission process is completed, the communication apparatus shifts to a reply packet reception process for the data of the terminal itself. Then, in the reply packet reception process for the data of the terminal itself, the communication apparatus shifts to a reception standby state when the process is completed or when a predetermined period has elapsed.

  On the other hand, in the signal reception process, the communication apparatus shifts to a reception standby state when the process is completed, and shifts to a reply packet transmission process when the process is completed and a return packet needs to be transmitted. Then, when the processing is completed in the reply packet transmission processing, the communication device shifts to a reception standby state. Hereinafter, the data packet transmission process, the data packet transmission process of the own terminal, the signal reception process, and the reply packet transmission process will be described.

  When there is no reception signal and there is data to be transmitted in the reception standby state, the communication apparatus shifts to a data packet transmission process and executes the next process.

  FIG. 5 is a flowchart showing a processing routine of “data packet transmission processing”. In step S1, the transmission timing control unit 19 sets the current timing at the vehicle-to-vehicle transmission prohibited period set by the vehicle-to-vehicle transmission prohibited period setting unit 14 or the road set at the road-to-vehicle transmission prohibited period setting unit 16. It is determined whether or not it is a vehicle-to-vehicle transmission prohibited period. If it is affirmative determination, that is, if any of the above-described transmission prohibition periods, the state of “data to be transmitted” remains in the state of waiting for reception, and negative determination, that is, if it is not any of the above-described transmission prohibition periods, step The process proceeds to S2.

  In step S2, the transmission timing control unit 19 measures the reception sensitivity of each slot based on the detection result of the reception circuit 12 or the packet detection unit 13 to determine whether or not a carrier has been detected. Shifts to the reception standby state in the state of “data to be transmitted”, and shifts to step S3 when a negative determination is made.

  In step S3, the packet generator 17 generates a data packet from transmission information such as inter-vehicle data. The packet generation unit 17 includes the usage time information when the packet demodulating unit 15 demodulates the road-to-vehicle data packet and knows the usage time information of the road-to-vehicle communication (the slot occupied between the road and vehicle). Road-to-vehicle usage information is generated, and a data packet is generated from the vehicle-to-vehicle data and road-to-vehicle usage information. The transmission timing control unit 19 controls the transmission circuit 20 to transmit the data packet generated by the packet generation unit 17 and ends this routine. Thereby, the data packet is transmitted to each terminal via the antenna 21. And it transfers to the reply packet reception process with respect to the data of the own terminal.

  In addition, when it is not any of the above-described transmission prohibition periods (negative determination in step S1) and the condition of carrier non-detection (negative determination in step S2) is not satisfied, there is “data to be transmitted”, but “waiting for reception” It goes back and forth between “status” and “data packet transmission processing”. In this case, when it is time to transmit the next data packet, processing for discarding the previous data to be transmitted and transmitting new data is performed.

  FIG. 6 is a flowchart showing a processing routine of “reply packet reception processing for data of own terminal”. In step S11, the transmission timing control unit 19 determines whether a predetermined period has elapsed since the data packet transmission in step S3 described above. If the determination is affirmative, the routine is terminated and the process proceeds to a reception standby state. In this case, the process proceeds to step S12.

  In step S12, the packet receiving unit 13 determines whether reply packets for the data of the terminal itself have been received from all the peripheral terminals. If the determination is affirmative, the process proceeds to step S13. If the determination is negative, the process returns to step S11. . In addition, when the reception detection packet among the reply packets is received within a predetermined period after the transmission of the data packet of the own terminal, it is regarded as a reply packet to the own terminal, and is received during other periods. If it is, it is regarded as a reply packet to the hidden terminal.

  In step S13, the vehicle-to-vehicle transmission prohibition period setting unit 14 determines the type (reception detection packet or collision detection packet) of the return packet detected by the packet detection unit 13, and if it is a reception detection packet, the process proceeds to step S14. If it is a collision detection packet, the process proceeds to step S15.

  In step S14, the vehicle-to-vehicle transmission prohibition period setting unit 14 sets the vehicle-to-vehicle transmission prohibition period to reserve the next transmission timing, ends this routine, and shifts to a reception standby state.

  In step S15, the inter-vehicle transmission prohibition period setting unit 14 sets the inter-vehicle transmission prohibition period to change the next transmission timing of the terminal itself.

  FIG. 7 is a timing chart for explaining the inter-vehicle transmission prohibited period. Here, after the terminal transmits a data packet, all (or a part) of peripheral terminals transmit a reply packet (collision detection packet) to the data packet.

  Specifically, the vehicle-to-vehicle transmission prohibition period setting unit 14 sets a predetermined period including the next scheduled transmission timing of the own terminal after 100 msec from the transmission timing of the data packet of the own terminal as the inter-vehicle transmission prohibition period. To do. As a result, the next scheduled transmission timing of the terminal is changed compared to the previous time. Then, when the vehicle-to-vehicle transmission prohibition period is set, this routine is terminated and the process shifts to a reception standby state.

  Further, when the communication apparatus detects a reception signal in the “reception standby state”, the communication apparatus shifts to “signal reception process” and executes the next process.

  FIG. 8 is a flowchart showing the processing routine of “signal reception processing”. In step S21, the receiving circuit 12 shown in FIG. 1 receives a packet of another terminal (peripheral terminal), the packet detection unit 13 detects the packet, and the process proceeds to step S22.

  In step S22, the vehicle-to-vehicle transmission prohibition period setting unit 14 determines the type of the packet detected by the packet detection unit 13. If the packet is a vehicle-to-vehicle data packet, the process proceeds to step S23. The process proceeds to S24, and if it is a road-vehicle data packet, the process proceeds to step S27.

  In step S23, the inter-vehicle transmission prohibition period setting unit 14 waits for a predetermined period, ends this routine, and proceeds to a reply packet transmission process.

  In step S24, the inter-vehicle transmission prohibition period setting unit 14 determines the type of the return packet (reception detection packet or collision detection packet) detected by the packet detection unit 13, and if it is a reception detection packet, the process proceeds to step S25. If it is a collision detection packet, the process proceeds to step S26.

  In step S25, since a reply packet (reception detection packet) that is not a reply to the data packet of the terminal itself is detected, it can be seen that there is a hidden terminal. Therefore, the inter-vehicle transmission prohibition period setting unit 14 sets the inter-vehicle transmission prohibition period as follows.

  FIG. 9 is a timing chart for explaining the vehicle-to-vehicle transmission prohibition period. Here, the reply packet of the hidden terminal (terminal that is detected by the peripheral terminal but not detected by the own terminal) is transmitted every basic transmission cycle (for example, 100 msec), but is not detected by the own terminal. Also, the reply packet of the peripheral terminal is detected by the own terminal.

  When a reply packet is detected, the inter-vehicle transmission prohibition period setting unit 14 predicts 100 msec after the reply packet detection timing as the reception timing of the next reply packet, and the time before the predetermined period from the predicted timing. Is set as the transmission prohibition period.

  There is a possibility that the return packet is a packet transmitted from a peripheral terminal in response to a data packet transmitted from a hidden terminal. Therefore, the inter-vehicle transmission prohibition period setting unit 14 sets a period during which the hidden terminal may transmit the next data packet as the transmission prohibition period based on the detection timing of the return packet. Then, after setting the transmission prohibition period, this routine is ended and a transition is made to a reception standby state.

  In step S26, the inter-vehicle transmission prohibition period setting unit 14 cancels the inter-vehicle transmission prohibition period by predicting that the transmission timing of the other terminal will be changed. Here, it is assumed that a data packet collision of a hidden terminal (a terminal that is detected by a peripheral terminal but not detected by its own terminal) has occurred, and the peripheral terminal that has detected it transmits a reply packet (collision detection packet). ing.

  FIG. 10 is a timing chart regarding a transmission prohibition period when the terminal receives a reply packet (collision detection packet).

  At this time, it can be predicted that the peripheral terminal that has received the collision detection packet (the hidden terminal that has caused the packet collision) changes the transmission timing of the next data packet in the same manner as the terminal itself. Therefore, the vehicle-to-vehicle transmission prohibition period setting unit 14 sets the time after 100 msec from the reception timing of the reply packet (collision detection packet) as the reference time, and sets the time from the reference time to a predetermined time as the transmission prohibition period. Is prohibited. Alternatively, the inter-vehicle transmission prohibition period setting unit 14 cancels the setting when the period has already been set as the transmission prohibition period. Then, when the transmission prohibition period is canceled, this routine is ended, and a transition is made to a reception standby state.

  In step S27, the road-to-vehicle transmission prohibition period setting unit 16 sets the road-to-vehicle transmission prohibition period so that the terminal does not transmit a packet at the next scheduled transmission timing of the roadside device. Specifically, the road-to-vehicle transmission prohibition period setting unit 16 uses the road-to-vehicle communication usage time information demodulated by the packet demodulation unit 15 to receive the road-to-vehicle data at the next transmission cycle (slot (slot). ) Is set as the road-to-vehicle transmission prohibited period. Thereby, in the transmission cycle after the next time, it is avoided that the own terminal transmits the data packet in the slot occupied by the roadside device. Then, the process proceeds to step S28.

  In step S28, the packet demodulator 15 demodulates the road-vehicle data of the road-vehicle data packet detected by the packet detector 13, and generates road-vehicle usage information based on the road-vehicle data. This road-to-vehicle usage information is given to the vehicle-to-vehicle data packet by the packet generation unit 17 when this routine ends and the process proceeds to “data packet transmission processing” (in the case of vehicle-to-vehicle communication). Then, this routine is terminated and the process proceeds to a reception standby state.

  FIG. 11 is a flowchart showing a processing routine of “reply packet transmission processing”.

  In step S31, the transmission timing control means 19 determines whether or not the slot at the timing of receiving the packet (step S21 in FIG. 8) is a road-to-vehicle transmission prohibited period. If there is, the process ends. If a negative determination is made, the process proceeds to step S32. Thereby, when the timing at which the inter-vehicle data packet is received is the road-to-vehicle transmission prohibition period, neither the reception detection packet nor the collision detection packet is transmitted.

  In step S32, the reply packet generator 18 shown in FIG. 1 determines whether or not the data packet has been successfully received based on the packet demodulated by the packet demodulator 15, and proceeds to step S33 if successful. If not successful, the process proceeds to step S36.

  In step S33, the road-to-vehicle transmission prohibition period setting unit 16 determines whether there is road-to-vehicle usage information in the packet demodulated by the packet demodulation unit 15. If there is road-to-vehicle usage information, the process proceeds to step S38. If not, the process proceeds to step S34.

  In step S34, the reply packet generator 18 generates a reception detection packet. Then, the transmission timing control unit 19 controls the transmission circuit 20 to transmit the reception detection packet generated by the reply packet generation unit 18, and proceeds to step S35. Thereby, the reception detection packet is transmitted to the peripheral terminal via the antenna 21.

  In step S <b> 35, the inter-vehicle transmission prohibition period setting unit 14 sets an inter-vehicle transmission prohibition period so that the own terminal does not transmit at the next transmission timing of the other terminal, and ends this routine.

  FIG. 12 is a timing chart for explaining a vehicle-to-vehicle transmission prohibition period set after the terminal transmits a reception detection packet. Here, in order to prevent the own terminal from transmitting at the timing of the next transmission schedule of the other terminal, the inter-vehicle transmission prohibition period setting unit 14 sets the period estimated as the next transmission timing as the inter-vehicle transmission prohibition period. Set. Specifically, the inter-vehicle transmission prohibition period setting unit 14 is for inter-vehicle use that ends 100 msec (basic transmission period) after the terminal transmits a reply packet and starts from the end to a predetermined time before the end. Set the transmission prohibition period. Accordingly, the next transmission timing of the other terminal is included in the inter-vehicle transmission prohibition period, and it is possible to prevent the own terminal from transmitting the data packet at the next transmission timing of the other terminal. When the setting of the vehicle-to-vehicle transmission prohibition period is completed, this routine is terminated and the process shifts to a reception standby state.

  On the other hand, in step S36, the reply packet generator 18 generates a collision detection packet. The transmission timing control unit 19 controls the transmission circuit 20 to transmit the collision detection packet generated by the reply packet generation unit 18, and proceeds to step S37. Thereby, the collision detection packet is transmitted to the peripheral terminal via the antenna 21.

  In step S37, the inter-vehicle transmission prohibition period setting unit 14 cancels the inter-vehicle transmission prohibition period in consideration of the change in the transmission timing of the other terminals, and ends this routine.

  FIG. 13 is a timing chart for explaining the inter-vehicle transmission prohibited period. Here, the own terminal receives transmission packets (data packets) from a plurality of other terminals at the same timing, and the own terminal transmits a reply packet (collision detection packet). That is, data between peripheral terminals collide. At this time, each peripheral terminal can be predicted to change the transmission timing of the data packet when it detects a collision detection packet from its own terminal.

  Therefore, the inter-vehicle transmission prohibition period setting unit 14 sets the time after 100 msec from the transmission timing of the reply packet (collision detection packet) of the own terminal as a reference time, and sets the period from the reference time to a predetermined time before the inter-vehicle transmission. It is prohibited to set as a prohibited period. Alternatively, the inter-vehicle transmission prohibition period setting unit 14 cancels the setting when the period has already been set as the inter-vehicle transmission prohibition period. Then, when the inter-vehicle transmission prohibition period is canceled, this routine is terminated and the process shifts to a reception standby state.

  In step S38, the road-to-vehicle transmission prohibited period setting unit 16 sets the road-to-vehicle transmission prohibited period so that the terminal does not transmit at the next scheduled transmission timing of the roadside device. Specifically, the road-to-vehicle transmission prohibition period setting unit 16 uses the road-to-vehicle usage information of the data packet demodulated by the packet demodulation unit 15 to perform a timing at which road-to-vehicle communication is performed in the next transmission cycle. The same timing (slot) as (slot) is set as the road-to-vehicle transmission prohibited period. Thereby, in the transmission cycle after the next time, it is avoided that the own terminal transmits the data packet in the slot occupied by the roadside device. And it progresses to step S34 mentioned above.

  The communication device can avoid collision between the road-to-vehicle data packet transmitted from the roadside device and the vehicle-to-vehicle data packet transmitted from the peripheral terminal by executing the above routines.

  FIG. 14 is a diagram for explaining a collision between a road-to-vehicle data packet and a vehicle-to-vehicle data packet. Vehicles A, B, and C are each equipped with a conventional communication device. At this time, the vehicle A is traveling in a road-to-vehicle communication area that can communicate with the roadside machine, and also travels in a vehicle-to-vehicle communication area that can communicate with the vehicle B. Even when the vehicle A is communicating with the vehicle B between the vehicles, when the vehicle A enters the road-vehicle communication area, the vehicle A wants to give priority to the communication with the roadside device. However, conventionally, the road-to-vehicle data packet and the vehicle-to-vehicle data packet collide, and there is a problem that the vehicle A cannot communicate with the roadside device.

  FIG. 15 is a diagram for explaining the communication status of the roadside unit and the vehicles A, B, and C when the communication device according to the embodiment of the present invention is mounted on the vehicles A and B. FIG.16 and FIG.17 is a timing chart which shows the data which a roadside machine and vehicles A, B, and C transmit / receive. Note that, above each horizontal axis, transmitted data (packet) is shown, and below each horizontal axis, received data (packet) is shown. “BUSY” indicates a reply packet.

  In this case, when the communication device mounted on the vehicle A receives the road-to-vehicle data packet from the roadside device, the next transmission scheduled timing of the roadside device is prohibited using the road-to-vehicle communication use time information. The period is set (step S27 in FIG. 8, “road-to-vehicle transmission prohibited period” for vehicle A in FIG. 16). As a result, the communication device prohibits transmission of the data packet of the communication device at the next scheduled transmission timing of the road device, so that the communication state with the road device can be ensured.

  In addition, when the communication device mounted on the vehicle A receives the road-to-vehicle data packet from the roadside machine, the communication device generates road-to-vehicle usage information from the road-to-vehicle data packet (step S28 in FIG. 8). A data packet is generated from the usage information and transmitted (step S3 in FIG. 5, data packet of vehicle A in FIG. 16). Thereby, the said communication apparatus can notify the time (occupation slot) of the road-vehicle communication of the roadside machine and the vehicle A with respect to the communication apparatus of the vehicle B. FIG.

  On the other hand, when the communication device mounted on the vehicle B receives the data packet including the road-to-vehicle usage information, the road-to-vehicle transmission prohibition for the next scheduled transmission timing of the roadside device is performed using the road-to-vehicle usage information in the data packet. It is set as a period (step S38 in FIG. 11, “road-to-vehicle transmission prohibited period” for vehicle B in FIG. 16). Thereby, the said communication apparatus can transmit a data packet in the time different from the time of the road-vehicle communication of the roadside machine and the vehicle A. FIG.

  When the communication device mounted on the vehicle B receives the data packet from the vehicle C and shifts to “reply packet transmission processing” (steps S21 to S23 in FIG. 8), the reception timing is for road-to-vehicle use. In the transmission prohibition period, the reply packet transmission process is terminated without transmitting a reply packet (affirmative determination in step S31 in FIG. 11, “× BUSY” in vehicle B in FIG. 16). On the other hand, if the reception timing is other than the road-to-vehicle transmission prohibition period (negative determination in step S31 in FIG. 11), the communication device transmits a reception detection packet or a collision detection packet (steps S34 and S36 in FIG. 11). , “BUSY” in FIG. Thereby, since a communication apparatus communicates with a peripheral terminal in periods other than the road-to-vehicle transmission prohibition period, it is possible to prevent the road-to-vehicle communication between the roadside machine and the vehicle A from being disturbed.

  As described above, the communication device according to the first embodiment sets the timing at which road-to-vehicle communication is performed between the roadside machine and the vehicle as the road-to-vehicle transmission prohibited period, and the road-to-vehicle transmission prohibited period. Does not transmit a data packet of the communication device, and does not transmit a reply packet even when a data packet is received. In addition, if the reception timing of the data packet is other than the road-to-vehicle transmission prohibited period, the communication device transmits a reply packet even if it is the vehicle-to-vehicle transmission prohibited period.

  As a result, the communication device avoids communication with peripheral terminals at the timing when road-to-vehicle communication is performed, so the quality of service of road-to-vehicle communication is improved, and road-to-vehicle communication is more effective than vehicle-to-vehicle communication. Can be prioritized.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can also be applied to a design modified within the scope described in the claims. For example, in FIG. 15, the communication device mounted on the vehicle A may transmit a road-to-vehicle reply packet instead of transmitting a data packet including road-to-vehicle usage information and vehicle-to-vehicle data.

  FIG. 18 is a diagram illustrating a state in which the communication device mounted on the vehicle A transmits a road-to-vehicle reply packet. FIG. 19 is a diagram illustrating a timing chart of transmission / reception data of the roadside device and the vehicles A, B, and C when the communication device mounted on the vehicle A transmits a road-to-vehicle reply packet. FIG. 20 is a flowchart showing a second processing routine of the “reply packet transmission process”. The routine of FIG. 20 executes steps S33a and S38, respectively, instead of steps S33 and S38 shown in FIG.

  Specifically, in step S33a, the packet demodulator 15 determines the type of the demodulated data packet. If the data packet is an inter-vehicle data packet, the process proceeds to step S34, and if the data packet is a road-to-vehicle data packet, the process proceeds to step S39.

  In step S39, the reply packet generator 18 generates a road-to-vehicle reply packet. The road-vehicle reply packet is not particularly limited as long as it can be distinguished from the reception detection packet and the collision detection packet. For example, it is sufficient that the duration of the received power by the road-to-vehicle reply packet or the combination of subcarriers to be used is different from that of the reception detection packet and the collision detection packet.

  Then, the transmission timing control unit 19 controls the transmission circuit 20 so as to transmit the road-to-vehicle reply packet within a predetermined time (same slot as the reception timing) after receiving the road-to-vehicle data packet. Thereby, as shown in FIGS. 18 and 19, the communication device mounted on the vehicle A transmits a road-to-vehicle reply packet to the peripheral terminal (vehicle B). The communication time can be notified. On the other hand, when the communication device of the vehicle B receives the road-to-vehicle reply packet, as shown in FIG. 19, in the next transmission cycle, the time during which the road-to-vehicle communication is performed (maximum period of the road-to-vehicle communication service) It can be set to the transmission prohibition period.

  Here, when the communication device receives a data packet including road-to-vehicle usage information, the communication device extracts the road-to-vehicle usage information, embeds the road-to-vehicle usage information in the data packet to be transmitted, Can be sent to the terminal. That is, the road-to-vehicle usage information can be transferred to each terminal. Therefore, the communication device may limit the number of times the road-to-vehicle usage information is transferred as follows.

  Specifically, the packet generation unit 17 of the communication device may embed a transfer count indicating the number of times road-to-vehicle use information is transferred in a data packet to be transmitted. Further, when the transfer number of road-to-vehicle use information is embedded in the previously received data packet, the packet generation unit 17 increments the transfer number by one, and the road-to-vehicle use information and the counted transfer number May be embedded in the data packet.

  On the other hand, the packet generator 17 of the communication apparatus that has received such a data packet uses the reception information (number of transfers) demodulated by the packet demodulator 15 to compare the number of transfers with a predetermined threshold and transfer If the number of times is less than the threshold, the number of transfers is counted up by one, and the road-to-vehicle usage information and the counted up number of transfers are embedded in the data packet. Stop embedding in the data packet. As a result, the transfer count of road-to-vehicle use information can be canceled.

  In the above-described embodiment, the communication device is mounted on the vehicle. However, the communication device may be mounted on an airplane, a ship, or other mobile objects.

DESCRIPTION OF SYMBOLS 12 Reception circuit 13 Packet detection part 14 Inter-vehicle transmission prohibition period setting part 15 Packet demodulation part 16 Road-to-vehicle transmission prohibition period setting part 17 Packet generation part 18 Reply packet generation part 19 Transmission timing control part 20 Transmission circuit

Claims (6)

Receiving means for receiving a first data packet and a reply packet transmitted from another communication device, a second data packet transmitted from the information providing device;
First transmission prohibition period setting means for setting a first transmission prohibition period indicating a data packet transmission prohibition period based on the reception timing of the reply packet when the reception packet is received by the reception means; ,
When the second data packet is received by the receiving means, a second data packet transmission timing after the next time of the information providing device is set based on a reception timing of the second data packet. Second transmission prohibition period setting means for setting as a transmission prohibition period of
A reply packet generating means for generating a first reply packet indicating a detection result of the first data packet when the first data packet is received by the receiving means;
When the reception timing of the first data packet by the reception means is the second transmission prohibition period, transmission of the first reply packet generated by the reply packet generation means is prohibited, and the first First reply packet transmitting means for transmitting the first reply packet generated by the reply packet generating means when the reception timing of the data packet is a period other than the second transmission prohibition period;
Data packet transmitting means for transmitting a data packet in a period other than the first and second transmission prohibition periods;
A communication device comprising: Based on the reception timing of the second data packet received by the reception means, communication usage information indicating the transmission timing of the information providing device is generated, and a first data packet including the generated communication usage information is generated. A data packet generating means;
The communication apparatus according to claim 1, wherein the data packet transmission unit transmits the first data packet generated by the data packet generation unit. The receiving means receives a first data packet including the communication usage information;
The second transmission prohibition period setting unit sets the second transmission prohibition period based on communication usage information included in the first data packet received by the reception unit. Communication device. The data packet generation means, when the transfer count indicating the number of times the communication usage information is transferred from the communication device to another communication device is included in the received first data packet, the transfer count is the threshold value If so, the first data packet not including the communication usage information is generated, and if the transfer count is less than or equal to a threshold, the transfer count is incremented by one and the new transfer count is included. The communication device according to claim 2 or 3, wherein one data packet is generated. When the second data packet is received by the receiving means, further provided is a second reply packet transmitting means for transmitting a second reply packet within a predetermined time from the reception timing of the second data packet. The communication apparatus according to any one of claims 1 to 4. The receiving means further receives the second reply packet;
In the second transmission prohibition period, based on the reception timing of the second reply packet received by the receiving means, the transmission timing of the second data packet after the next time of the information providing apparatus is set to the second transmission packet. The communication device according to claim 5, wherein the communication device is set as a prohibited period.

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