JP2012015714A - Terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preferentially transmit travel data useful to determine a congestion situation in each on-vehicle device among travel data of each vehicle exchanged in vehicle-vehicle communication.SOLUTION: A road-vehicle receiving unit 118 receives congested area information from a road side device. A vehicle-vehicle receiving unit 120 receives a packet including travel data and transfer priority from another vehicle terminal device 150. A priority determination unit 122 obtains congested area information and travel area information of its own vehicle and another vehicle, and sets transfer priority of corresponding travel data to "high" if the own vehicle and the other vehicle are in a congested area. An other vehicle data selection unit 124 selects data having "high" transfer priority among the travel data of the other vehicle. A frame creation unit 126 creates a frame including the selected travel data of the other vehicle and the travel data of the own vehicle. A vehicle-vehicle transmission unit 128 transmits a packet signal including the created frame by vehicle-vehicle communication.

Description

  The present invention relates to a technique for transmitting and receiving vehicle travel data in an in-vehicle terminal device.

  Systems such as ITS (Intelligent Transport Systems) that predict traffic congestion by inter-vehicle communication are being constructed. In such a system, it is considered that each in-vehicle device acquires travel data of other vehicles existing around the host vehicle through inter-vehicle communication and notifies a driver of a traffic jam estimated based on the travel data. Each in-vehicle device not only transmits the travel data of the own vehicle, but also transfers the received travel data of other vehicles, so that travel data of a large number of vehicles can be propagated over a wide range.

  As described above, when each in-vehicle device transfers the traveling data of other vehicles, the amount of communication data between vehicles becomes enormous and traffic congestion occurs. Therefore, in the inter-vehicle communication device of Patent Document 1, the nearest intersection and the same traveling direction are defined as the same vehicle group as the own vehicle, the transmission cycle in the representative vehicle of the vehicle group is shortened, and the representative vehicle Increasing the transmission cycle in vehicles other than the above is disclosed. Thereby, the increase in the communication traffic between the vehicles which comprise a vehicle group is suppressed.

JP 2009-188527 A

  In the technique described in Patent Document 1, since the amount of communication data is reduced based on the travel data received by inter-vehicle communication, the important travel data for determining the traffic jam condition is removed in each in-vehicle device. There is a possibility that.

  The present invention has been made in view of such circumstances, and its purpose is to prioritize travel data useful for determining a traffic jam situation in each in-vehicle device among travel data of each vehicle exchanged by inter-vehicle communication. It is to provide the technology to transfer.

  In order to solve the above-described problems, an embodiment of the present invention is a terminal device mounted on a vehicle in order to perform inter-vehicle communication. The device includes a transmission unit configured to transmit a frame including travel data of another vehicle received from a terminal device of the other vehicle and travel data of the host vehicle, and the travel data includes at least a place where each vehicle is traveling. The frame includes the transfer priority for determining which of the traveling data of other vehicles is preferentially transmitted.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, driving | running | working data useful for judgment of the traffic congestion condition in each terminal device can be preferentially transferred among the driving | running | working data of each vehicle exchanged by vehicle-to-vehicle communication.

It is a figure which shows the structure of the communication system which performs vehicle-to-vehicle communication and road-to-vehicle communication. It is a figure which shows the structure of a base station apparatus. FIG. 3A to FIG. 3D are diagrams showing frame formats defined in the communication system. It is a figure which shows the structure of a sub-frame. FIGS. 5A to 5B are diagrams illustrating the format of a MAC frame stored in a packet signal defined in the communication system. It is a figure which shows the structure of the terminal device mounted in the vehicle. It is a figure which shows the structure of the terminal device which concerns on one Embodiment of this invention. It is a figure which shows an example of the map image to which road ID was provided. It is a figure which shows an example of the map image to which point ID was provided. It is a figure which shows the structure of the flame | frame transmitted / received by vehicle-to-vehicle communication. It is a flowchart of the vehicle-to-vehicle communication process which concerns on one Embodiment of this invention. It is a figure which shows a mode that vehicle-to-vehicle communication is implemented between the vehicles currently drive | working the intersection vicinity where the roadside machine is installed. It is a figure which shows a mode that vehicle-to-vehicle communication is implemented between the vehicles currently drive | working the intersection vicinity where the roadside machine is installed.

  Before describing the present invention, a communication system that performs vehicle-to-vehicle communication between terminal devices mounted on a vehicle and also performs road-to-vehicle communication from a base station device installed at an intersection or the like to a terminal device will be described.

  In this communication system, as inter-vehicle communication, the terminal device broadcasts a packet signal storing information such as the speed and position of the vehicle (hereinafter referred to as “data”). Further, the other terminal device receives the packet signal and recognizes the approach of the vehicle based on the data. Further, as road-to-vehicle communication, the base station apparatus repeatedly defines a frame including a plurality of subframes. The base station apparatus selects any one of the plurality of subframes, and broadcasts a packet signal in which control information and the like are stored in the period of the head portion of the selected subframe.

  The control information includes information related to a period for the base station apparatus to broadcast the packet signal (hereinafter referred to as “road vehicle transmission period”). The terminal device specifies a road and vehicle transmission period based on the control information, and transmits a packet signal in a period other than the road and vehicle transmission period. Thus, since the road-to-vehicle communication and the vehicle-to-vehicle communication are time-division multiplexed, the collision probability of packet signals between them is reduced. That is, when the terminal device recognizes the content of the control information, interference between road-vehicle communication and vehicle-to-vehicle communication is reduced. In addition, the area where the terminal device performing inter-vehicle communication is mainly classified into three types.

  One is an area formed around the base station apparatus (hereinafter referred to as “first area”), and the other is an area formed outside the first area (hereinafter referred to as “second area”). Another one is an area formed outside the second area (hereinafter referred to as “outside the second area”). Here, in the first area and the second area, the terminal device can receive the packet signal from the base station apparatus with a certain quality, whereas outside the second area, the packet signal from the base station apparatus is received. The terminal device cannot receive with a certain quality. The first area is formed closer to the center of the intersection than the second area. Since the vehicle existing in the first area is a vehicle existing near the intersection, the packet signal from the terminal device mounted on the vehicle can be said to be important information from the viewpoint of suppressing collision accidents.

  Corresponding to such area regulations, a period for vehicle-to-vehicle communication (hereinafter referred to as “vehicle transmission period”) is formed by time division multiplexing of a priority period and a general period. The priority period is a period for use by a terminal apparatus existing in the first area, and the terminal apparatus transmits a packet signal in any of a plurality of slots forming the priority period. The general period is a period for use by a terminal apparatus existing in the second area, and the terminal apparatus transmits a packet signal by the CSMA method in the general period. In addition, the terminal device existing outside the second area transmits a packet signal by the CSMA method regardless of the frame configuration. Here, it is determined in which area the terminal device mounted on the vehicle is present.

  FIG. 1 shows the configuration of a communication system 100 as described above. This corresponds to a case where one intersection is viewed from above. The communication system 100 includes a base station device 10, a first vehicle 12a, a second vehicle 12b, a third vehicle 12c, a fourth vehicle 12d, a fifth vehicle 12e, a sixth vehicle 12f, and a seventh vehicle 12g, collectively referred to as a vehicle 12. , The eighth vehicle 12h, and the network 202. Each vehicle 12 is equipped with a terminal device (not shown). The first area 210 is formed around the base station apparatus 10, the second area 212 is formed outside the first area 210, and the second outside area 214 is formed outside the second area 212. ing.

  As shown in the drawing, the road that goes in the horizontal direction of the drawing, that is, the left and right direction, intersects the vertical direction of the drawing, that is, the road that goes in the up and down direction, at the central portion. Here, the upper side of the drawing corresponds to the direction “north”, the left side corresponds to the direction “west”, the lower side corresponds to the direction “south”, and the right side corresponds to the direction “east”. The intersection of the two roads is an “intersection”. The first vehicle 12a and the second vehicle 12b are traveling from left to right, and the third vehicle 12c and the fourth vehicle 12d are traveling from right to left. Further, the fifth vehicle 12e and the sixth vehicle 12f are traveling from the top to the bottom, and the seventh vehicle 12g and the eighth vehicle 12h are traveling from the bottom to the top.

  The communication system 100 arranges the base station device 10 at an intersection. The base station device 10 controls communication between terminal devices. The base station device 10 repeatedly generates a frame including a plurality of subframes based on a signal received from a GPS satellite (not shown) and a frame formed by another base station device 10 (not shown). Here, the road vehicle transmission period can be set at the head of each subframe. The base station apparatus 10 selects a subframe in which the road and vehicle transmission period is not set by another base station apparatus 10 from among the plurality of subframes. The base station apparatus 10 sets a road and vehicle transmission period at the beginning of the selected subframe. The base station apparatus 10 stores control information including information on a road and vehicle transmission period in a packet signal. The base station apparatus 10 also stores predetermined data in the packet signal. The base station apparatus 10 notifies the packet signal in the set road and vehicle transmission period.

  A first area 210 and a second area 212 are formed around the communication system 100 according to the reception status when the terminal apparatus receives a packet signal from the base station apparatus 10. As shown in the figure, a first area 210 is formed in the vicinity of the base station apparatus 10 as an area having a relatively good reception status. It can be said that the first area 210 is formed near the central portion of the intersection. On the other hand, the second area 212 is formed outside the first area 210 as a region where the reception situation is worse than that of the first area 210. Further, outside the second area 212, an area outside the second area 214 is formed as an area where the reception status is worse than that in the second area 212. Note that the packet signal error rate and received power are used as the reception status.

  The plurality of terminal apparatuses receive the packet signal broadcasted by the base station apparatus 10 and, based on the reception status of the received packet signal, in any of the first area 210, the second area 212, and the second outside area 214 Estimate if it exists. When it is estimated that the data exists in the first area 210 or the second area 212, the terminal device generates a frame based on the control information included in the received packet signal. As a result, the frame generated in each of the plurality of terminal devices is synchronized with the frame generated in the base station device 10. Further, the terminal device recognizes the road and vehicle transmission period set by each base station device 10 and specifies the vehicle and vehicle transmission period for transmission of the packet signal. Specifically, when it exists in the first area 210, the priority period is specified, and when it exists in the second area 212, the general period is specified. Further, the terminal device transmits a packet signal by executing TDMA in the priority period and executing CSMA / CA in the general period.

  Note that the terminal apparatus also selects subframes having the same relative timing in the next frame. In particular, in the priority period, the terminal device selects slots having the same relative timing in the next frame. Here, the terminal device acquires data and stores the data in a packet signal. The data includes, for example, information related to the location. The terminal device also stores control information in the packet signal. That is, the control information transmitted from the base station device 10 is transferred by the terminal device. On the other hand, when the terminal device is estimated to exist outside the second area 214, the terminal device transmits a packet signal by executing CSMA / CA regardless of the frame configuration.

  FIG. 2 shows the configuration of the base station apparatus 10. The base station apparatus 10 includes an antenna 20, an RF unit 22, a modem unit 24, a processing unit 26, a control unit 30, and a network communication unit 80. The RF unit 22 receives a packet signal from a terminal device (not shown) or another base station device 10 by the antenna 20 as a reception process. The RF unit 22 performs frequency conversion on the received radio frequency packet signal to generate a baseband packet signal. Further, the RF unit 22 outputs a baseband packet signal to the modem unit 24. In general, baseband packet signals are formed by in-phase and quadrature components, so two signal lines should be shown, but here only one signal line is shown for clarity. Shall be shown. The RF unit 22 includes an LNA (Low Noise Amplifier), a mixer, an AGC, and an A / D conversion unit.

  As a transmission process, the RF unit 22 performs frequency conversion on the baseband packet signal input from the modem unit 24 to generate a radio frequency packet signal. Further, the RF unit 22 transmits a radio frequency packet signal from the antenna 20 during the road-vehicle transmission period. The RF unit 22 also includes a PA (Power Amplifier), a mixer, and a D / A conversion unit.

  The modem unit 24 demodulates the baseband packet signal from the RF unit 22 as a reception process. Further, the modem unit 24 outputs the demodulated result to the processing unit 26. The modem unit 24 also modulates the data from the processing unit 26 as a transmission process. Further, the modem unit 24 outputs the modulated result to the RF unit 22 as a baseband packet signal. Here, since the communication system 100 corresponds to an OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme, the modem unit 24 also performs FFT (Fast Fourier Transform) as reception processing and IFFT (Inverse Fast Forward) as transmission processing. Also execute.

  The processing unit 26 receives a signal from a GPS satellite (not shown), and acquires time information based on the received signal. In addition, since a well-known technique should just be used for acquisition of the information of time, description is abbreviate | omitted here. The processing unit 26 generates a plurality of frames based on the time information. For example, the processing unit 26 generates 10 frames of “100 msec” by dividing the period of “1 sec” into 10 on the basis of the timing indicated by the time information. By repeating such processing, the frame is defined to be repeated. Note that the processing unit 26 may detect control information from the demodulation result. Such processing corresponds to generating a frame synchronized with the timing of the frame formed by another base station apparatus 10. Details of the processing of the processing unit 26 at that time will be described later.

  3A to 3D show frame formats defined in the communication system 100. FIG. FIG. 3A shows the structure of the frame. The frame is formed of N subframes indicated as the first subframe to the Nth subframe. For example, when the frame length is 100 msec and N is 10, a subframe having a length of 10 msec is defined. FIG. 3B shows a configuration of a frame generated by the first base station apparatus 10a. The first base station apparatus 10a sets a road and vehicle transmission period at the beginning of the first subframe. Moreover, the 1st base station apparatus 10a sets a vehicle transmission period following a road and vehicle transmission period in a 1st sub-frame. The vehicle transmission period is a period during which the terminal device can notify the packet signal. That is, in the road and vehicle transmission period which is the head period of the first subframe, the first base station apparatus 10a can notify the packet signal, and in the frame, the terminal apparatus transmits in the vehicle and vehicle transmission period other than the road and vehicle transmission period. It is defined that the packet signal can be broadcast. Furthermore, the first base station apparatus 10a sets only the vehicle transmission period from the second subframe to the Nth subframe.

  FIG. 3C shows a configuration of a frame generated by the second base station apparatus 10b. The second base station apparatus 10b sets a road and vehicle transmission period at the beginning of the second subframe. Also, the second base station apparatus 10b sets the vehicle transmission period from the first stage of the road and vehicle transmission period in the second subframe, from the first subframe and the third subframe to the Nth subframe. FIG. 3D shows a configuration of a frame generated by the third base station apparatus 10c. The third base station apparatus 10c sets a road and vehicle transmission period at the beginning of the third subframe. In addition, the third base station apparatus 10c sets the vehicle transmission period from the first stage of the road and vehicle transmission period in the third subframe, the first subframe, the second subframe, and the fourth subframe to the Nth subframe. As described above, the plurality of base station apparatuses 10 select different subframes, and set the road and vehicle transmission period at the head portion of the selected subframe.

  FIG. 4 shows the structure of a subframe. As illustrated, one subframe is configured in the order of a road and vehicle transmission period, a priority period, and a general period. The priority period and the general period correspond to the vehicle transmission period shown in FIG. When the road and vehicle transmission period is not included in the subframe, the subframe is configured in the order of the priority period and the general period. In the priority period, a plurality of slots are time-division multiplexed. With such a configuration, a frame including at least a plurality of slots is repeated. Returning to FIG.

  The processing unit 26 inputs a demodulation result from another base station device 10 or a terminal device (not shown) via the RF unit 22 and the modem unit 24. Here, the configuration of the MAC frame stored in the packet signal will be described as a demodulation result. The MAC frame input to the processing unit 26 and the MAC frame output from the processing unit 26 have the same configuration. FIGS. 5A and 5B show the formats of MAC frames stored in packet signals defined in the communication system 100. FIG. FIG. 5A shows the format of the MAC frame. In the MAC frame, “MAC header”, “RSU control header”, “application data”, and “CRC” are arranged in order from the top. The RSU control header corresponds to the control information described above. The application data stores data to be notified to the terminal device such as accident information.

  FIG. 5B shows the format of the RSU control header. The RSU control header includes “basic information”, “timer value”, “transfer count”, “subframe number”, “frame period”, “used subframe number”, “start timing & time length” in order from the top. Deploy. Note that the configuration of the RSU control header is not limited to that shown in FIG. 5B, and some elements may be excluded, or other elements may be included. The number of times of transfer indicates the number of times that the control information transmitted from the base station apparatus 10, particularly the content of the RSU control header, has been transferred by a terminal device (not shown). Here, the base station device 10 corresponds to the base station device 10 for the MAC frame output from the processing unit 26, and the base station device 10 corresponds to the MAC frame input to the processing unit 26. Corresponds to another base station apparatus 10. This is common in the following description.

  The MAC frame output from the processing unit 26 has the transfer count set to “0”. In addition, the number of transfers for the MAC frame input to the processing unit 26 is set to “0” or more. The number of subframes indicates the number of subframes forming one frame. The frame period indicates the period of the frame, and is set to, for example, “100 msec” as described above. The used subframe number is a number of a subframe in which the base station device 10 sets a vehicle transmission period. As shown in FIG. 3A, the subframe number is set to “1” at the head of the frame. In the start timing & time length, the start timing of the road and vehicle transmission period at the beginning of the subframe and the time length of the road and vehicle transmission period are indicated. Returning to FIG.

  Here, a procedure for selecting a subframe in which a road and vehicle transmission period is to be set will be described. Processing in which the processing unit 26 generates a frame synchronized with the timing of a frame formed by another base station apparatus 10 will be described. The processing unit 26 extracts a MAC frame whose transfer count is set to “0” from the MAC frames. This corresponds to a packet signal directly transmitted from another base station apparatus 10. The processing unit 26 specifies the value of the used subframe number among the extracted MAC frames. This corresponds to specifying a subframe used by another base station apparatus 10. The processing unit 26 measures the received power of the packet signal arranged at the head of the already identified subframe. This corresponds to measuring the reception power of the packet signal from the other base station apparatus 10.

  The processing unit 26 extracts a MAC frame whose transfer count is set to “1” or more from the MAC frames. This corresponds to a packet signal transmitted from the other base station apparatus 10 and then transferred by the terminal apparatus. The processing unit 26 specifies the value of the used subframe number among the extracted MAC frames. This corresponds to specifying a subframe used by another base station apparatus 10. The terminal device transfers the subframe number when the terminal device receives a packet signal from another base station device 10.

  The processing unit 26 also measures the received power of these packet signals. Further, the processing unit 26 estimates that the acquired received signal is the received power of the packet signal from the other base station apparatus 10 to which the control information is transferred by the packet signal. The processing unit 26 identifies a subframe in which a road and vehicle transmission period is to be set. Specifically, the processing unit 26 checks whether there is an “unused” subframe. If present, the processing unit 26 selects one of the “unused” subframes. Here, when a plurality of subframes are unused, the processing unit 26 selects one subframe at random. When there is no unused subframe, that is, when each of the plurality of subframes is used, the processing unit 26 preferentially specifies a subframe with low reception power.

  The processing unit 26 sets a road and vehicle transmission period at the beginning of the subframe having the specified subframe number. The processing unit 26 generates a MAC frame to be stored in the packet signal. At that time, the processing unit 26 determines the value of the RSU control header of the MAC frame according to the setting of the road and vehicle transmission period. This corresponds to control information related to the frame configuration. The processing unit 26 acquires predetermined information via the network communication unit 80 and includes the predetermined information in the application data. Here, the network communication unit 80 is connected to a network 202 (not shown). The processing unit 26 broadcasts the packet signal to the modem unit 24 and the RF unit 22 during the road and vehicle transmission period. Here, the packet signal includes control information and identification information for identifying the base station apparatus 10. Identification information for identifying the base station apparatus 10 is included in the MAC header of FIG.

  When the packet signal received from the terminal device includes information on another base station device 10 that has failed (hereinafter referred to as “failure information”), the processing unit 26 transmits the failure information to the network communication unit. Output to 80. The network communication unit 80 notifies failure information to a management center (not shown) via the network 202 (not shown). That is, the management center is notified of the failure found. The estimation result may be included in the packet signal and notified from the processing unit 26, the modem unit 24, and the RF unit 22. The control unit 30 controls processing of the entire base station apparatus 10.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it can be realized by a program loaded in the memory, but here it is realized by their cooperation. Draw functional blocks. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 6 shows the configuration of the terminal device 14 mounted on the vehicle 12. The terminal device 14 includes an antenna 50, an RF unit 52, a modem unit 54, a processing unit 56, and a control unit 58. The processing unit 56 includes a generation unit 64, a timing identification unit 60, a transfer determination unit 90, a notification unit 70, an estimation unit 72, a storage unit 74, and a positioning unit 76. The timing specifying unit 60 includes an extraction unit 66, a selection unit 92, and a carrier sense unit 94. The antenna 50, the RF unit 52, and the modem unit 54 execute the same processing as the antenna 20, the RF unit 22, and the modem unit 24 in FIG. Therefore, here, the difference will be mainly described.

  The modem unit 54 and the processing unit 56 receive packet signals from other terminal devices 14 and the base station device 10 (not shown). As described above, a subframe in which the priority period and the general period are time-multiplexed is defined, and the road and vehicle transmission period may be time-multiplexed in the subframe. The road and vehicle transmission period is a period during which a packet signal can be notified from the base station apparatus 10. Here, the modem unit 54 and the processing unit 56 receive the packet signal from the base station apparatus 10 in the road and vehicle transmission period. The packet signal includes identification information for identifying the base station apparatus 10 that is a notification source of the packet signal. The priority period is a period that the terminal apparatus 14 existing in the first area 210 formed around the base station apparatus 10 should use for broadcasting the packet signal. Multiple slots are included in the priority period. The general period is a period that the terminal device 14 existing in the second area formed outside the first area 210 should use for broadcasting the packet signal. Also, a frame in which a plurality of subframes are time-multiplexed is defined.

  The extraction unit 66 measures the received power of the packet signal from the base station device 10. Based on the measured received power, the extraction unit 66 estimates whether it exists in the first area 210, the second area 212, or outside the second area 214. For example, the extraction unit 66 stores a first threshold for area determination and a second threshold for area determination. Here, the first threshold for area determination is defined to be larger than the second threshold for area determination. If the received power is greater than the first threshold value for area determination, the extraction unit 66 determines that it exists in the first area 210. If the received power is equal to or smaller than the first threshold for area determination and is larger than the second threshold for area determination, the extraction unit 66 determines that the second area 212 exists. If the received power is equal to or smaller than the second threshold for area determination, the extraction unit 66 determines that the power is present outside the second area 212. Note that the extraction unit 66 may use an error rate instead of the received power, or may use a combination of the received power and the error rate.

  Based on the estimation result, the extraction unit 66 determines any one of the priority period, the general period, and the timing unrelated to the frame configuration as the transmission period. More specifically, when it is estimated that the extraction unit 66 exists outside the second area 214, the extraction unit 66 selects a timing unrelated to the frame configuration. When it is estimated that the extraction unit 66 exists in the second area 212, the extraction unit 66 selects the general period. When it is estimated that the extraction unit 66 exists in the first area 210, the extraction unit 66 selects a priority period.

  When the demodulation result from the modem unit 54 is a packet signal from the base station apparatus 10 (not shown), the extraction unit 66 specifies the timing of the subframe in which the road-vehicle transmission period is arranged. Further, the extraction unit 66 generates a frame based on the subframe timing and the content of the RSU control header. Note that the generation of the frame may be performed in the same manner as the processing unit 26 described above, and thus the description thereof is omitted here. As a result, the extraction unit 66 generates a frame synchronized with the frame formed in the base station apparatus 10. Moreover, the extraction part 66 specifies a road and vehicle transmission period based on the content of the RSU control header.

  When selecting the priority period, the extraction unit 66 outputs information on the priority period to the selection unit 92. When the general period is selected, the extraction unit 66 outputs information on the frame and subframe timing and the vehicle transmission period to the carrier sense unit 94. When selecting the timing irrelevant to the frame configuration, the extraction unit 66 instructs the carrier sense unit 94 to execute carrier sense. The selection unit 92 receives information on the priority period from the extraction unit 66. In addition, the selection unit 92 selects any slot from the plurality of slots included in the priority period, and determines the selected slot as the transmission timing. Here, received power may be used to select a slot. For example, a slot with a small reception power is selected. The selection unit 92 notifies the generation unit 64 of the determined transmission timing.

  The carrier sense unit 94 receives information about the timing of frames and subframes and the vehicle transmission period from the extraction unit 66. The carrier sense unit 94 measures the interference power by performing carrier sense in the general period. Further, the carrier sense unit 94 determines the transmission timing in the general period based on the interference power. More specifically, the carrier sense unit 94 stores a predetermined threshold value in advance, and compares the interference power with the threshold value. If the interference power is smaller than the threshold value, the carrier sense unit 94 determines the transmission timing. When receiving the carrier sense execution instruction from the extraction unit 66, the carrier sense unit 94 determines the transmission timing by executing the CSMA without considering the frame configuration. The carrier sense unit 94 notifies the generation unit 64 of the determined transmission timing.

  The positioning unit 76 includes a GPS receiver (not shown), a gyroscope, a vehicle speed sensor, and the like. Based on data supplied from the GPS receiver, the position of the vehicle 12 (not shown), that is, the vehicle 12 on which the terminal device 14 is mounted, Get direction, speed, etc. The existence position is indicated by latitude and longitude. Since a known technique may be used for these acquisitions, description thereof is omitted here. The positioning unit 76 outputs the presence position and the like to the generation unit 64.

  The generation unit 64 receives the presence position and the like from the positioning unit 76. The generation unit 64 uses the MAC frame shown in FIGS. 5A to 5B and stores the presence position in the application data. Further, the generation unit 64 receives identification information from the extraction unit 66, and also stores the most recently received identification information in the application data. The generation unit 64 generates a packet signal including a MAC frame, and generates the packet signal via the modulation / demodulation unit 54, the RF unit 52, and the antenna 50 at the transmission timing determined by the selection unit 92 or the carrier sense unit 94. Broadcast packet signals. The transmission timing is included in the vehicle transmission period.

  The transfer determination unit 90 controls transfer of the RSU control header. The extraction unit 66 extracts an RSU control header from a packet signal for which the base station device 10 is an information source. As described above, when the packet signal is directly transmitted from the base station apparatus 10, the number of transfers is set to “0”, but when the packet signal is transmitted from another terminal apparatus 14. The number of transfers is set to a value of “1 or more”. Here, since the used subframe number is not changed when transferred by the terminal apparatus 14, the subframe used in the base station apparatus 10 serving as the information source is specified by referring to the used subframe number. The

  The transfer determination unit 90 acquires information on the number of transfers for each base station apparatus 10 that is an information source. More specifically, the transfer determining unit 90 sequentially acquires the number of transfers corresponding to the subframe number “1”, and then executes the same processing for the number of transfers corresponding to other subframe numbers. . Further, the transfer determination unit 90 acquires, for each base station device 10 serving as an information source, the smaller transfer number, for example, the value of the minimum transfer number, from the information related to the transfer number related to the base station device 10. To do. That is, the transfer count acquisition unit 110 acquires the minimum transfer count corresponding to the subframe number “1”, the minimum transfer count corresponding to the subframe number “2”, and the like.

  The transfer determination unit 90 measures the RSU control header, that is, the number of extractions of control information, for each base station apparatus 10 that is an information source. Moreover, the transfer determination part 90 selects the frequency | count of extraction of the control information containing the value of the frequency | count of transfer acquired in the transfer determination part 90 for every base station apparatus 10 used as an information source. More specifically, the transfer determination unit 90 measures the number of times control information is extracted for each transfer number for one subframe number. As a result, for example, for the subframe number “1”, the number of times control information is extracted is “0”, and the number of times control information is extracted is “4”. ", And the number of times control information is extracted is" 6 "times. If the acquired transfer count is “1”, the transfer determination unit 90 selects the control information extraction count “4” including the transfer count.

  The transfer determination unit 90 stores the subframe number, the transfer count, and the extraction count in association with each other. In addition, the transfer determination unit 90 updates the stored content when the number of transfers and the number of extractions are updated. The transfer determination unit 90 acquires the number of transfers and the number of extractions for each base station device 10. The transfer determination unit 90 selects control information corresponding to at least one base station apparatus 10 as control information to be transferred based on the number of transfers and the number of extractions. More specifically, the transfer determination unit 90 compares the number of transfers with the plurality of base station devices 10 and then compares the number of extractions. That is, after selecting the control information with the smaller number of transfers, for example, the control information with the minimum number of transfers, the control information with the larger number of extractions and the maximum number of extractions are selected from the selected control information. Selected control information is selected.

  In this way, control information having the minimum number of transfers and control information having the maximum number of extractions corresponding to the number of transfers is selected by the transfer determination unit 90. It can be said that control information is received near the base station apparatus 10 which becomes an information source, so that the frequency | count of transfer is small. In addition, it can be said that the control information is received in a situation where the variation in the wireless environment is smaller as the number of extractions is larger. Therefore, it can be said that the terminal device 14 has selected the control information from the base station apparatus 10 installed as close as possible by selecting the control information that satisfies the above-described situation.

  The transfer determination unit 90 instructs the generation unit 64 to generate an RSU control header based on the selected control information. The transfer determination unit 90 increases the number of transfers in the information related to the number of transfers when storing the control information in the RSU control header. In response to such an instruction, the generation unit 64 generates an RSU control header based on the control information selected by the transfer determination unit 90 and increases the number of transfers at that time.

  The storage unit 74 stores position information of the base station apparatus 10 that can broadcast a packet signal to be received by the RF unit 52, the modem unit 54, and the processing unit 56. Since a plurality of base station devices 10 are installed, the storage unit 74 stores a plurality of pieces of position information. The position information is indicated by latitude and longitude so as to be associated with the road map. Further, since the position information is shown as digital data, the storage unit 74 is configured as a storage medium such as a hard disk capable of storing digital data. Here, in order to simplify the description, it is assumed that the position information is stored in the storage unit 74 in advance. For example, it is preset when the terminal device 14 is purchased.

  The estimation unit 72 sequentially receives the positioning presence positions from the positioning unit 76. The estimation unit 72 assumes a circular area having a predetermined radius with the position information stored in the storage unit 74 as the center. Such a region corresponds to, for example, the first area 210 and the second area 212 in FIG. 1, but here corresponds to the second area. A circular area is assumed for each of the plurality of base station apparatuses 10. The estimation unit 72 is present in the vicinity of the base station apparatus 10 installed at the center of the circular area by detecting that the consecutively received existence positions have entered from the outside to the inside of the circular area. Detect that. Moreover, the estimation part 72 detects whether the packet signal from the base station apparatus 10 is received while existing in the circular area. When the packet signal is received, the estimation unit 72 estimates that the base station apparatus 10 is operating normally. On the other hand, when the packet signal is not received, the estimation unit 72 estimates a failure of the base station device 10. When the estimation unit 72 estimates a failure, the estimation unit 72 outputs the fact to the generation unit 64 and the notification unit 70.

  When the generation unit 64 receives a failure estimation result from the estimation unit 72, the generation unit 64 stores the failure estimation result in the application data. As a result, the failure estimation result is notified during the vehicle transmission period. The notification unit 70 acquires a packet signal from the base station device 10 (not shown) in the road and vehicle transmission period, and acquires a packet signal from another terminal device 14 (not shown) in the vehicle and vehicle transmission period. The notification unit 70 notifies the driver of the approach of another vehicle 12 (not shown) to the driver via a monitor or a speaker in accordance with the content of data stored in the packet signal. Furthermore, when the notification unit 70 receives the estimation result of the failure from the estimation unit 72, the notification unit 70 also notifies the driver of the estimation result. When the notification is made via the monitor, the notification unit 70 displays the display color of the part where the base station apparatus 10 that has failed is installed in red. Moreover, the notification part 70 may output that the base station apparatus 10 is out of order from a speaker. The control unit 58 controls the operation of the entire terminal device 14.

  Subsequently, a vehicle-to-vehicle communication technology according to an embodiment of the present invention will be described. In the present embodiment, traveling data to be transferred by each in-vehicle terminal device is selected based on both the traffic jam area information acquired by road-to-vehicle communication and the traveling area information acquired by vehicle-to-vehicle communication.

  “Congestion” in the following description refers to a state in which a predetermined number or more of vehicles have stopped for a relatively long time and are traveling at a low speed, and are not necessarily the Metropolitan Police Department or road managers. It does not have to be the same as the definition of traffic jams.

  FIG. 7 shows a configuration of the terminal device 150 according to the present embodiment. Also in this configuration, each functional block can be realized in various forms by hardware only, software only, or a combination thereof.

  The RF unit 102 and the modem unit 104 have the same functions as those described for the terminal device 14 described above.

  The traffic jam display processing unit 160 displays traffic jam information obtained by road-to-vehicle communication and vehicle-to-vehicle communication on the screen of the display 140. The traffic jam display processing unit 160 includes a road-to-vehicle reception unit 118, a vehicle-to-vehicle reception unit 120, a priority determination unit 122, another vehicle data selection unit 124, a frame creation unit 126, a vehicle-to-vehicle transmission unit 128, and a navigation unit 130.

  The road-to-vehicle receiving unit 118 receives communication contents including traffic jam area information transmitted from a roadside machine (not shown). The roadside machine is installed at, for example, an intersection, and basically has the same configuration as the base station apparatus 10 shown in FIG. The roadside device receives information on an area where traffic congestion is occurring or an area where traffic congestion is likely to occur (hereinafter, both are collectively referred to as “traffic congestion area”) from a management center connected via a network (not shown) Communicate between cars. For example, a traffic jam area is actually notified by a road section where traffic is regulated, a road point where an obstacle is detected on the road by a sensor installed on the road side, VICS (Vehicle Information and Communication System), etc. Includes road sections where traffic congestion is occurring.

  The inter-vehicle receiver 120 receives a packet transmitted from the terminal device 150 mounted on the surrounding vehicle. As will be described later with reference to FIG. 10, this packet includes the driving data transfer priority in addition to the driving data of each vehicle. In this embodiment, two “High” and “Low” are prepared as transfer priorities.

  The priority determination unit 122 acquires traffic jam area information from the road-to-vehicle data received by the road-to-vehicle reception unit 118. The priority determination unit 122 acquires travel area information from the travel data of other vehicles received by the inter-vehicle reception unit 120 and also acquires travel area information of the host vehicle from a position acquisition unit 136 described later.

  Note that the traffic congestion area and the travel area are preferably specified using a “road ID” or a “point ID” described later. Alternatively, the map may be divided into squares at predetermined intervals, and the traffic congestion area and the traveling area may be specified by the numbers assigned to the squares.

  The priority determination unit 122 determines the transfer priority for each of the travel data of the other vehicle and the travel data of the host vehicle. Specifically, when the traveling area of the own vehicle or other vehicle coincides with the traffic congestion area, the transfer priority of the corresponding traveling data of the own vehicle or other vehicle is set to “high”. When the traveling area of the own vehicle or other vehicle does not coincide with the traffic jam area or when no traffic jam area information is received from the roadside machine, the transfer priority of the own vehicle or other vehicle traveling data is set to “low”.

  The other vehicle data selection unit 124 determines which of the traveling data of the other vehicle is transferred according to the transfer priority set by the priority determination unit 122. In other words, the other vehicle data selection unit 124 selects, as the transfer target, the traveling data of the other vehicle having the transfer priority “high”. When there is no travel data of other vehicles having a transfer priority of “high”, or when the travel data of other vehicles having a transfer priority of “high” is greater than a predetermined upper limit number (for example, “1”), The other vehicle data selection unit 124 selects, for example, traveling data of another vehicle that travels at a position farther from the host vehicle as a transfer target, or selects traveling data of another vehicle having a new data creation time. The other vehicle data selection unit 124 may select travel data of another vehicle having a new data creation time when there are a plurality of other vehicles having the same distance from the host vehicle.

  The frame creation unit 126 includes the travel data of the other vehicle selected as the transfer target by the other vehicle data selection unit 124, the travel data of the host vehicle, and the transfer priority of each travel data set by the priority determination unit 122. Create a vehicle-to-vehicle communication frame that includes The travel data of the host vehicle may include a travel speed detected by a vehicle speed sensor (not shown), a travel area of the host vehicle acquired by the position acquisition unit 136, a travel data creation time, and the like.

  The inter-vehicle transmission unit 128 broadcast-transmits a packet signal including the frame created by the frame creation unit 126 to terminal devices of an unspecified number of vehicles by a well-known wireless LAN (Local Area Network).

  The navigation unit 130 displays a navigation screen on the display 140. The navigation unit 130 includes a map data storage unit 134, a position acquisition unit 136, and a display control unit 138.

  The map data storage unit 134 stores map data used for navigation display and traffic jam information display. The map data may be pushed and updated by an external server connected via a wireless LAN. Furthermore, the map data storage unit 134 also stores data relating to road IDs or point IDs that are allocated in advance.

  The position acquisition unit 136 is a GPS (Global Positioning System), for example, and acquires the current position of the host vehicle. Since GPS is a well-known technique, detailed description is omitted. Note that the current position may be acquired using another existing technique such as specifying the position based on wireless communication instead of the GPS.

  The display control unit 138 displays a map image of a predetermined range around the host vehicle on the display 140 based on the map data. Furthermore, the display control unit 138 displays the traffic jam situation acquired by road-to-vehicle communication and vehicle-to-vehicle communication in a superimposed manner on the map image. For example, a sign indicating that there is a traffic jam may be given to a road or a point that is determined to be a traffic jam area based on information from the roadside machine. This sign may be a road with a traffic jam, such as “X” and other roads with “O”, or a red line or arrow extending over the entire section corresponding to the road ID. Also good.

  Note that the terminal device 150 according to the present embodiment may be configured integrally with the terminal device 14 described with reference to FIG. 6 by sharing the RF unit, the modulation / demodulation unit, or the like, or may be configured separately. May be.

  In this embodiment, in order to determine whether or not each vehicle is traveling in a traffic jam area, the “road ID” or “point ID” given to the map data is used. In the present specification, the road ID and the spot ID may be collectively referred to as “traveling area information”.

  FIG. 8 shows an example of a map image to which a road ID is assigned. FIG. 8 shows a map of a predetermined range around the host vehicle displayed on the display of the car navigation system. The arrow in the figure represents the traveling direction of the vehicle.

  Road ID R100, R101 for each direction of travel on the road extending upward in the figure with the intersection P as a dividing point, and road IDs R102, R103 for each direction of travel on the road extending downward are roads extending to the right. Are assigned road IDs R104 and R105 for each traveling direction. Such road ID is memorize | stored with map data in the vehicle-mounted terminal device.

  For example, one road ID is assigned for each section delimited by an intersection or for each section delimited by a predetermined distance. The size of the intersection serving as a division point may be a large-scale intersection where main roads such as national roads and prefectural roads intersect, or a smaller-scale intersection. In addition to the intersection, the division point of the section to which the road ID is assigned is a point where a predetermined number or more vehicles are likely to stop from that point, that is, a point where traffic congestion is likely to occur. It may be set. For example, it may be set at the entrance of a parking lot of a store or business having a capacity greater than or equal to a predetermined value. Moreover, road ID does not need to be given with respect to all the roads in map data. For example, the road ID may be given only to roads having a predetermined width or more, or roads having a predetermined number of passing units per unit time or more.

  In the present embodiment, as shown in FIG. 8, it is desirable that the road ID is given to be different for each traveling direction of the road. That is, it is desirable that two road IDs are given to the roads in a certain section for each traveling direction. Thereby, for example, even when the opposite lane is congested, but the own lane is smooth, it is possible to determine the traffic jam for each traveling direction.

  The section to which the road ID is assigned may be determined manually, or may be set automatically on given map data by setting specific conditions. The length of the section to which the road ID is given is preferably determined based on experience, experiments, traffic engineering, or the like so that detailed traffic jam information is communicated to the driver and the section is not unnecessarily subdivided.

  The symbol of the road ID may be a serial number, for example, or may be a combination of a map number in a specific range and a serial number within that range. The road ID is not limited to these as long as it is a symbol string according to some form. The road ID may or may not be displayed on the map.

  FIG. 9 shows an example of a map image to which a point ID is assigned. FIG. 9 shows a map of a predetermined range around the host vehicle displayed on the display of the car navigation system.

  The point ID is set on a road in a given map data at a place where a predetermined number or more vehicles are likely to stop starting from that place, that is, a place where traffic congestion is likely to occur. The Specific locations to which point IDs are assigned are as follows, but are not limited to these.

1. Main intersection. For example, an intersection where an intersection name is given in map data mounted on a commercially available navigation system, an intersection where main roads such as national roads and prefectural roads intersect, and the like can be mentioned.

2. A small intersection other than the main intersection. For example, an intersection where no intersection name is given in the map data, an intersection where roads other than main roads intersect, or an entrance to an expressway or a toll road can be cited.

3. A point where congestion is likely to occur among points where alleys with a width greater than or equal to a predetermined value intersect the road. An example is an alley that goes from a residential area to a main road with heavy traffic.

4). Entrance to the parking lot. However, it is preferable to add some conditions because traffic jams do not occur near every parking lot. For example, it may be defined as a parking lot of a store or office having a capacity greater than or equal to a predetermined value, or it may be defined as a parking lot with a high frequency of entering and exiting a vehicle such as a convenience store even if the number of accommodation is small. Good.

  In addition to the above 1 to 4, when the interval between the point IDs is more than a predetermined distance (for example, 500 m), a point ID is further allocated to a part that is equally divided between the two points or at a constant interval It is preferable. For example, a suburban road. Such a place is not necessarily a place where traffic jams are likely to occur, but when a long-distance traffic jam occurs due to an unexpected situation such as an accident, a large number of vehicles may stop at such locations. For this reason, there is an advantage in assigning point IDs at regular intervals for the purpose of conveying traffic jam information to the driver in detailed sections.

  In FIG. 9, point IDs P1 and P3 are point IDs set at main intersections. The point ID P2 is a point ID set for each predetermined interval D because P1 and P3 are separated from each other. The spot ID P4 is a spot ID that is set at a place that goes from the alley to the main road. The spot IDs P5 and P6 are spot IDs set at the parking lot and the store entrance, respectively. The point ID P7 is a point ID set at a small intersection.

  The point ID is associated with the type information (large-scale intersection, small-scale intersection, alley, parking lot, etc.) that corresponds to which of the above conditions, and the latitude information and longitude information of the location. It is preferably recorded as a database in the terminal device.

  The place where the point ID is set may be determined manually, or a specific condition may be set to search for a place where the point ID should be set on given map data. In general, the map data used in the navigation system includes position information such as intersections, stores, companies, and parking lots, so that the latter type of automatic detection is possible.

  The symbol of the point ID may be a serial number, for example, or may be a combination of a map number in a specific range and a serial number within that range. Or you may utilize the latitude and longitude information of each point. The point ID is not limited to the above as long as it is a symbol string according to some form.

  The traffic congestion area and the travel area are specified using either the road ID or the point ID described above. When the road ID is used, it is possible to determine whether the vehicle is in the traffic jam area for each traveling direction of the vehicle by giving two road IDs for each traveling direction. When using point ID, it is preferable to specify a traffic jam area and a traveling area by two point IDs and their order. In this way, the traveling direction of the vehicle can be distinguished from the direction of the vector connecting the two point IDs. Thereby, for example, even when the opposite lane is congested, but the own lane is smooth, it is possible to determine the traffic jam for each traveling direction.

  The road ID or the spot ID as the traveling area of each vehicle can be obtained by superimposing the position of the own vehicle acquired by the position acquisition unit 136 on the map data stored in the map data storage unit 134. .

  Next, the operation of the traffic jam display processing unit 160 will be described. The road-to-vehicle receiver 118 receives the traffic jam area information from the roadside machine. The inter-vehicle receiver 120 receives a packet including travel data and transfer priority from the terminal device 150 of another vehicle. The priority determination unit 122 acquires the congestion area information and the traveling area information of the own vehicle and the other vehicle, and when the own vehicle and the other vehicle exist in the congestion area, the transfer priority of the corresponding traveling data is set to “high”. Set to. The other vehicle data selection unit 124 selects the travel data of the other vehicle having the transfer priority “high”. The frame creation unit 126 creates a frame that includes the travel data of the selected other vehicle and the travel data of the host vehicle. The inter-vehicle transmission unit 128 transmits a packet signal including the created frame between the vehicles.

  Thus, in the terminal device of each vehicle, it is determined whether or not the own vehicle or another vehicle is in the traffic jam area, and the travel data of the other vehicle in the traffic jam area is transmitted with priority. Therefore, vehicle-to-vehicle communication can be performed efficiently.

  FIG. 10 shows a configuration of a frame 170 that is transmitted and received by inter-vehicle communication. As shown in the figure, the frame 170 includes host vehicle travel data 172 and its transfer priority 174, other vehicle travel data 176 and its transfer priority 178. The own vehicle travel data and the other vehicle travel data include at least travel area (for example, road ID or section ID) information of each vehicle. The own vehicle traveling data and the other vehicle traveling data may further include information such as the traveling speed of each vehicle, the traveling direction, the date of data creation or the date of transmission / reception. In FIG. 10, the frame 170 is shown to include only one set of other vehicle travel data 176 and its transfer priority 178, but so that it includes two or more sets of other vehicle travel data 176 and its transfer priority 178. Alternatively, the frame 170 may be configured.

  Since the packet including the frame 170 is transmitted between the vehicles by the multi-hop method, the traveling data of the host vehicle can be delivered to a vehicle outside the transmission range (for example, a vehicle traveling far behind the host vehicle). This inter-vehicle communication may be executed within the vehicle transmission period described with reference to FIG. 3 at the place where the base station apparatus 10 is installed. In locations where the base station apparatus 10 is not installed, an access control function called CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) is used in a wireless local area network (LAN) compliant with standards such as IEEE 802.11. May be executed.

FIG. 11 is a flowchart of a vehicle-to-vehicle communication process performed between the terminal devices 150 according to the present embodiment.
First, the road-to-vehicle reception unit 118 receives road-to-vehicle communication data including traffic jam information from the roadside device, and the vehicle-to-vehicle reception unit 120 receives vehicle-to-vehicle communication data transmitted from another vehicle (S10). The priority determination unit 122 determines whether or not traffic jam area information has been received from the roadside machine (S12). When the own vehicle does not exist within the communicable range with the roadside machine, or when the traffic jam area information is not included in the road-to-vehicle communication data (N in S12), the process proceeds to S20.

  When the traffic jam area information is received from the roadside machine (Y in S12), the priority determination unit 122 extracts the travel area information of the other vehicle from the travel data in the received inter-vehicle communication data, and automatically receives the travel area information from the position acquisition unit 136. Vehicle travel area information is acquired (S14). And the priority determination part 122 matches traffic area information with the traveling area information of the own vehicle or another vehicle, and determines whether the own vehicle or another vehicle exists in a traffic congestion area (S16). If neither the host vehicle nor the other vehicle is in the traffic jam area (N in S16), the process proceeds to S20. When the own vehicle or another vehicle is in the traffic jam area (Y in S16), the transfer priority of the traveling data of the vehicle is set to “high” (S18).

  The other vehicle data selection unit 124 selects the travel data having the transfer priority of “high” when the other vehicle travel data more than the upper limit number of transfer (for example, “1”) is included in the inter-vehicle communication frame. (S20).

  The frame creation unit 126 creates a frame that includes at least the travel data and transfer priority of the other vehicle selected by the other vehicle data selection unit 124, and the travel data and transfer priority of the host vehicle (S22). The unit 128 broadcasts a packet including this frame (S24).

  As a result of the above processing, traveling data of other vehicles having a high priority is preferentially transferred. As a result, travel data useful for determining traffic congestion is preferentially transferred, so that communication between vehicles can be performed efficiently.

  12 and 13 show a state in which vehicle-to-vehicle communication according to the present embodiment is performed between vehicles that are traveling in the vicinity of an intersection where the roadside machine K is installed. In each figure, it is assumed that communication is performed between vehicles A, B, and C equipped with terminal devices, and a point R in front of vehicle A is reported as a traffic jam area due to accidents, construction, traffic restrictions, etc. And An ellipse Z in the figure indicates a range in which communication is possible between the roadside machine K and the vehicle-mounted terminal device. Further, in the format in which vehicle-to-vehicle communication is performed, it is assumed that only one vehicle's travel data is included.

  FIG. 12 shows an example in which the terminal device that transmits the host vehicle travel data determines the transfer priority of the host vehicle travel data. In this example, the vehicles A and B are within the communicable range Z of the roadside machine K, but the vehicle C is outside the communicable range Z.

  The terminal device of the vehicle A determines that the host vehicle A is in the traffic jam area by matching the traffic jam area received from the roadside machine K with the travel area of the host vehicle. Therefore, the terminal device of the vehicle A transmits the frame 252 in which the transfer priority of the host vehicle traveling data is set to “high”. In this example, since the terminal device of the vehicle A has not received the travel data of the other vehicle, the host vehicle travel data and the transfer priority are also transmitted in the other vehicle travel data area.

  The terminal device of the vehicle B receives the frame 252 from the terminal device of the vehicle A. Then, the own vehicle travel data and the transfer priority thereof are rewritten with those of the vehicle B. In this case, the terminal device of the vehicle B determines that the host vehicle B is in the traffic jam area by matching the traffic jam area received from the roadside machine K with the travel area of the host vehicle. Therefore, the terminal device of the vehicle B transmits the frame 254 in which the transfer priority of the own vehicle data is set to “high”.

  The terminal device of the vehicle C receives the frame 254 from the terminal device of the vehicle B, and rewrites the own vehicle traveling data and its transfer priority with those of the vehicle C. In this case, since the terminal device of the vehicle C cannot receive the traffic jam area information from the roadside machine K, the transfer priority of the host vehicle data is set to “low”. Furthermore, in the received frame 254, the terminal device of the vehicle C determines which of the traveling data of the vehicle A and the traveling data of the vehicle B should be further transferred. Basically, the terminal device operates so as to give priority to transfer with a transfer priority of “high”. In this example, the transfer priorities of the vehicles A and B are both “high”. Therefore, for example, the terminal device selects travel data of the vehicle A located farther from the host vehicle. Which is located far from the own vehicle can be determined by comparing the traveling areas of the vehicles A and B and the traveling area of the own vehicle C. As a result, the terminal device of the vehicle C transfers the frame 256 including the traveling data of the vehicle C, the traveling data of the vehicle A, and their transfer priorities. Alternatively, the terminal device may select the traveling data with the newer data creation time when the transfer priority of both the vehicle A and the vehicle B is “high”.

  FIG. 13 illustrates an example in which the terminal device that has received the other vehicle travel data determines the transfer priority of the other vehicle travel data. In this example, only the vehicle B is within the communicable range Z of the roadside machine K, and the vehicles A and C are outside the communicable range Z.

  Since the terminal device of the vehicle A cannot receive the traffic jam information from the roadside machine K, the terminal device of the vehicle A transmits the frame 262 in which the transfer priority of the own vehicle data is set to “low”. In this example, since the terminal device of the vehicle A has not received the other vehicle travel data, the host vehicle travel data and the transfer priority are also transmitted in the other vehicle travel data area.

  The terminal device of the vehicle B receives the frame 262 from the terminal device of the vehicle A. First, the terminal device of the vehicle B acquires the travel area of the other vehicle from the other vehicle travel data in the frame 262. Furthermore, the traffic jam area information is received from the roadside machine K. The terminal device of the vehicle B knows that the vehicle A is in the traffic jam area by matching the traffic jam area received from the roadside machine K with the travel area of the vehicle A. Therefore, the terminal device of the vehicle B sets the transfer priority of the traveling data of the vehicle A to “high”. Subsequently, the terminal device of the vehicle B recognizes that the vehicle B is not in the traffic jam area by matching the traffic jam area received from the roadside machine with the travel area of the vehicle B. Therefore, the transfer priority of the traveling data of the vehicle B is set to “low”. The terminal device of the vehicle B creates and transfers a frame 264 including the traveling data of the vehicles A and B and their transfer priorities.

  The terminal device of the vehicle C receives the frame 264 from the terminal device of the vehicle B, and rewrites the own vehicle traveling data and its transfer priority with those of the vehicle C. In this case, since the terminal device of the vehicle C cannot receive the traffic jam area information from the roadside machine K, the transfer priority of the host vehicle data is set to “low”. Further, the terminal device of the vehicle C determines which of the traveling data of the vehicle A and the traveling data of the vehicle B should be further transferred in the received frame 264. In this example, the transfer priority of the travel data of the vehicle A is “high”, whereas the transfer priority of the travel data of the vehicle B is “low”, so the travel data of the vehicle A is selected. As a result, the terminal device of the vehicle C transfers the frame 266 including the traveling data of the vehicle C, the traveling data of the vehicle A, and the transfer hot water degree thereof.

  As described above, when the terminal device of each vehicle can receive the traffic jam area information from the roadside machine, the transfer priority of the traveling data of the own vehicle is set to either “high” or “low” and the received other The transfer priority is set to either “high” or “low” for the vehicle travel data. When the traffic jam area information cannot be received from the roadside machine, the priority of the traveling data of the host vehicle is set to “low”. Further, the terminal device of each vehicle selects and transfers the one having the high transfer priority among the received traveling data of the other vehicles. By doing so, it is possible to determine whether or not a vehicle in a position where information is not received from the roadside machine is in a traffic jam area with the terminal device of the vehicle within the communication range of the roadside machine. Further, since the traveling data of the vehicle having the transfer priority “high” is transferred, the transfer traffic can be reduced.

  As described above, in this embodiment, the transfer priority of the travel data of each vehicle is set based on the traffic jam area information transmitted by road-to-vehicle communication. This makes it possible to preferentially transfer travel data of vehicles traveling in a traffic jam area to terminal devices of surrounding vehicles.

  Moreover, in this embodiment, since the driving | running | working data of a vehicle are transferred between vehicles by a multihop system, the driving | running | working data of the other vehicle which exists far from the own vehicle can also be received. This makes it possible to determine traffic jams over a wide range.

  In addition, since the travel data with a low transfer priority, that is, the travel data of the vehicle traveling outside the traffic jam area is not transferred in the terminal device of each vehicle, the amount of transmission data between the vehicles can be compressed, and the communication traffic can be reduced. It is reduced.

  The present invention has been described based on some embodiments. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to combinations of the respective components and processing processes, and such modifications are within the scope of the present invention. is there.

  In the embodiment, the transfer priority is set to “high” and “low”. However, the transfer priority may be expressed by flag on / off (for example, “high” when the flag is on). Or it may be expressed by a number (for example, the lower the number, the higher the priority).

  In the embodiment, it has been described that only the traveling data of one vehicle is included in a frame communicated between vehicles. However, the terminal device may be configured such that traveling data of two or more vehicles can be included in the frame. In this case, the transfer priority may be set not in two stages of “high” and “low” but in three stages (for example, “high”, “medium”, and “low”) or more. The terminal device of each vehicle may select and transmit a predetermined number of other vehicle travel data from the higher priority.

  102 RF unit, 104 modulation / demodulation unit, 118 road-to-vehicle reception unit, 120 vehicle-to-vehicle reception unit, 122 priority determination unit, 124 other vehicle data selection unit, 126 frame creation unit, 128 vehicle-to-vehicle transmission unit, 130 navigation unit, 134 map Data storage unit, 136 position acquisition unit, 138 display control unit, 140 display, 150 terminal device, 160 traffic jam display processing unit, AC vehicle, K roadside machine, R traffic jam point, Z communicable range, 252, 254, 256 , 262, 264, 266 frames.

Claims (5)

A terminal device mounted on a vehicle to perform inter-vehicle communication,
A transmission unit configured to transmit a frame including the traveling data of the other vehicle and the traveling data of the own vehicle received from the terminal device of the other vehicle;
The travel data includes at least travel area information indicating a place where each vehicle is traveling,
The terminal device according to claim 1, wherein the frame includes a transfer priority for determining which of the traveling data of other vehicles is preferentially transmitted. A receiver that receives information on the traffic jam area from outside,
A priority determination unit that sets the transfer priority of the corresponding vehicle's driving data higher than the transfer priority of the driving data of the other vehicle when the traffic jam area and the driving area of the host vehicle or the other vehicle match;
The terminal device according to claim 1, further comprising:   The terminal device according to claim 2, further comprising: an other vehicle data selection unit that includes a predetermined number of traveling data in the frame among the other vehicle traveling data set with a high transfer priority. A map data storage unit that holds map data in which a point ID as identification information is assigned to a point that matches a predetermined condition for determining a place where traffic congestion is likely to occur on the road in the map data Further comprising
The terminal device according to claim 1, wherein the congestion area and the traveling area are specified using the point ID. A map data storage unit that holds map data in which road IDs as identification information are assigned to at least some roads set in advance for each section;
The terminal device according to claim 1, wherein the traffic congestion area and the traveling area are specified using the road ID.

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