JPWO2011152022A1 - Terminal device - Google Patents

Abstract

The map data storage unit 134 holds map data in which a point ID as identification information is allocated to a point that matches a predetermined condition for determining a place where traffic congestion is likely to occur. The vehicle speed calculation unit 114 obtains the traveling speed of the vehicle. The position acquisition unit 136 acquires the current position of the vehicle. The transmission data creation unit 116 creates the vehicle data of the host vehicle including the spot ID of the point where the host vehicle last passed, the spot ID of the next pass point, the traveling speed, and the vehicle ID assigned to each vehicle. A transmission frame is formed together with vehicle data received from another vehicle. The transmission unit 118 broadcasts a packet including a transmission frame. When the traveling speed included in the vehicle data received from the other vehicle is equal to or lower than a predetermined speed, the traffic congestion determination unit 120 determines that the road between the two point IDs included in the vehicle data is congested.

Description

  The present invention relates to a technique for determining the presence or absence of a traffic jam in a terminal device of a vehicle.

  Road-to-vehicle communication is being studied to prevent collisions at intersections. In the road-to-vehicle communication, information on the situation of the intersection is communicated between the roadside device and the vehicle-mounted device. Road-to-vehicle communication requires the installation of roadside equipment, which increases labor and cost. On the other hand, a system for predicting traffic congestion by inter-vehicle communication, such as ITS (Intelligent Transport Systems), is being constructed. If it is a form which communicates information between vehicle-to-vehicle communication, ie, onboard equipment, installation of a roadside machine will become unnecessary. In that case, for example, the current position information is detected in real time by GPS (Global Positioning System) or the like, and the position information is exchanged between the vehicle-mounted devices so that the own vehicle and other vehicles enter the intersection respectively. (See, for example, Patent Document 1).

JP 2005-202913 A

  In conventional VICS (Vehicle Information and Communication System) and other systems, the road from one roadside machine installation location to another roadside machine installation location is treated as one section, and traffic congestion information for each section is used for user navigation. It was displayed on the system screen. However, in such a system, it is not possible to determine whether there is a traffic jam on a road where no roadside machine exists. Moreover, since the place where the roadside machine is installed is limited, there is a problem that the road section in which the traffic information is displayed becomes a relatively long distance.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for determining the presence or absence of traffic congestion based on inter-vehicle communication.

  In order to solve the above-described problems, a terminal device according to an aspect of the present invention is a terminal device mounted on a vehicle for performing inter-vehicle communication, and includes at least vehicle data including information related to the speed and position of the vehicle. And a transmission data creating unit that configures a transmission frame together with the vehicle data of the host vehicle, and a transmission unit that broadcasts a packet including the transmission frame.

  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.

  According to the present invention, it is possible to determine the presence or absence of traffic jam based on inter-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 an example of the location where point ID is allocated. It is a figure which shows the structure of the terminal device which concerns on this embodiment. It is a figure which shows the structural example of the flame | frame transmitted / received by vehicle-to-vehicle communication. It is a figure which shows an example of the display mode of the map data to which point ID was allocated. It is a figure which shows an example of the display mode of the map data to which point ID was allocated. It is a figure which shows an example of the display mode of the map data to which point ID was allocated. It is a flowchart of the traffic congestion display process based on the vehicle-to-vehicle communication which concerns on this embodiment. It is a flowchart of the traffic judgment process in a traffic judgment part. It is a figure for demonstrating the traffic judgment process when the vehicle is running smoothly on each road and there is no traffic jam. It is a figure for demonstrating the traffic jam judgment process when the traffic jam has generate | occur | produced in the intersection.

  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”). And 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, since a baseband packet signal is formed by an in-phase component and a quadrature component, two signal lines should be shown, but here only one signal line is shown for the sake of 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 time information, 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 the 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 randomly selects one subframe. 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. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware alone or a combination of hardware and software.

  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.

  Then, the congestion judgment technique by the vehicle-to-vehicle communication which concerns on one Embodiment of this invention is demonstrated. In this embodiment, the presence or absence of traffic jam can be determined by the terminal device of each vehicle based only on inter-vehicle communication. Therefore, it is possible to predict traffic congestion even in a place where a base station device is not installed. Furthermore, in this embodiment, by including a “point ID” described later in the map data in advance, it is possible to perform traffic jam prediction in a section that is finer than the conventional technique.

  “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.

  The “point ID” in the present embodiment is a point on the road in the given map data, where a predetermined number of vehicles or more likely to stop starting from that point, that is, traffic congestion is likely to occur. Set to a possible location. 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 location is not necessarily a location where traffic jams are likely to occur, but when a long-distance traffic jam occurs due to an unexpected situation such as an accident, many 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.

  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. Recorded in the terminal device as a database.

  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.

  FIG. 7 shows an example of a location where a location ID is allocated. FIG. 7 shows a map of a predetermined range around the host vehicle displayed on the display of the car navigation system, and seven point IDs P1 to P7 represented by serial numbers are allocated within this range.

  The spot IDs P1 and P3 are spot 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.

  By using the map data in which the point IDs are set as shown in FIG. 7, it is possible to predict traffic jams in a more detailed section than before and provide information to the driver.

  FIG. 8 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 alone or a combination of hardware and software.

  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 the presence or absence of traffic jam on the screen of the display 140 based on the data received from other vehicles and the data of the host vehicle. The traffic jam display processing unit 160 includes a direction determination unit 112, a vehicle speed calculation unit 114, a transmission data creation unit 116, a transmission unit 118, a traffic jam determination unit 120, and a navigation unit 130.

  The vehicle speed calculation unit 114 obtains the traveling speed of a vehicle (not shown) on which the terminal device 150 is mounted. The traveling speed may be obtained using information from a known vehicle speed sensor attached to the vehicle, or the vehicle speed is calculated from the distance that the host vehicle position acquired from the GPS moves within a predetermined period. Also good.

  The transmission data creation unit 116 creates vehicle data for transmission to other vehicles traveling around the host vehicle. In the present embodiment, the terminal device 150 of each vehicle includes: 1. ID of the point where the vehicle last passed (hereinafter referred to as “passed point ID” as appropriate); 2. A point ID at which the vehicle is predicted to pass next (hereinafter referred to as “next pass point ID” as appropriate); 3. Vehicle traveling speed between the two point IDs; Vehicle data of the own vehicle including a vehicle ID assigned in advance for each vehicle (hereinafter referred to as “own vehicle data”) is created. The next passing point ID can be predicted from the map data and the current position information of the host vehicle.

  The direction determination unit 112 is opposite to the host vehicle from the position relationship between two point IDs included in the vehicle data received from the other vehicle (hereinafter referred to as “other vehicle data”), that is, the already-passed point ID and the next-passed point ID. The vehicle ID of the vehicle traveling in the direction is specified.

  The transmission data creating unit 116 creates a transmission frame including the received other vehicle data in addition to the own vehicle data. At this time, the other vehicle data of the vehicle running backward from the host vehicle specified by the direction determination unit 112 is not included in the transmission frame. That is, the transmission data creation unit 116 includes other vehicle data of all vehicles that are traveling ahead of the passing point ID of the own vehicle, other vehicle data of all vehicles that are traveling left of the passing point ID of the own vehicle, And the transmission frame including the other vehicle data of all the vehicles that are traveling to the right of the passing point ID of the host vehicle is created.

  The transmission unit 118 broadcast-transmits a packet including the frame created by the transmission data creation unit 116 to terminal devices of an unspecified number of vehicles by a well-known wireless LAN (Local Area Network).

  As described above, the travel information between the two spot IDs is received from the other vehicle, and after the information is selected by the terminal device of each vehicle, the vehicle data is broadcasted to the other vehicle. Since the vehicle data is transmitted by a multi-hop method, the vehicle data can be transmitted to a vehicle that exists at a position beyond the transmission range of one terminal device. At this time, if the upper limit number of hops is set, the amount of vehicle data for inter-vehicle communication will not continue to increase.

  The traffic jam determination unit 120 determines whether there is traffic on the road ahead of the host vehicle or on the surrounding roads based on the host vehicle data and other vehicle data received in the inter-vehicle communication. The traffic jam judgment unit 120 basically judges that the road between two point IDs where the vehicle is traveling is congested when the traveling speed of the other vehicle is equal to or less than a predetermined value. The predetermined speed may be changed according to the type of road (for example, 20 km / h for general roads, 40 km / h for highways, etc.). A specific determination procedure of the traffic jam determination unit 120 will be described later with reference to FIG.

  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 stores the data of the spot IDs assigned in advance. As described above, the spot ID is stored in association with related information such as the spot type, latitude, and longitude information.

  Note that the point to which the data of the point ID should be allocated changes with the passage of time due to the establishment of a new road, the opening of a store, a company, a parking lot, an expansion, or the closing of business. Therefore, it is preferable that the point ID data is also updated when the map data is updated.

  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. Further, the display control unit 138 displays traffic jam information based on the information received from the traffic jam judgment unit 120 and the point ID data stored in the map data storage unit 134.

  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.

FIG. 9 shows a configuration example of a frame transmitted / received by inter-vehicle communication.
(A) shows the structure of the frame broadcast-transmitted from a certain vehicle. In addition to the host vehicle data created by the transmission data creation unit 116, this frame includes data of other vehicles existing around the host vehicle. Since a packet including this frame is transmitted between vehicles by a multi-hop method, vehicle data of a distant vehicle can be delivered to a vehicle outside the transmission range (for example, a vehicle traveling far behind the host vehicle).
(B) shows the data structure contained in the own vehicle data. As described above, the host vehicle data includes at least the past passage point ID, the next passage point ID, the vehicle speed, and the vehicle ID.

  The inter-vehicle communication may be executed within the vehicle transmission period described with reference to FIG. 3 at the place where the base station device 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.

  10-12 is a figure which shows an example of the display mode of the map data to which point ID was allocated.

  FIG. 10 is a display example when there is no traffic jam in the map display range of the display 140. As shown in the figure, the spot IDs P1 to P7 are displayed on the map as black dots, for example. Note that when there is no traffic jam, the point ID may not be displayed on the map, that is, the user may not know where the point ID is set.

  FIG. 11 is a display example when a traffic jam occurs within the map display range of the display 140. In this example, it is assumed that the traffic jam determining unit 120 determines that the traffic between the point IDs P2 and P3 is a traffic jam. At this time, the display control unit 138 displays the point IDs P2 and P3 in a color different from the black point, and displays an arrow A on the road between P2 and P3 that is a traffic jam section. The points P2, P3 and the arrow A are preferably conspicuous colors (for example, red). Further, the point and the arrow may be the same color or different colors. Instead of changing the color, a dynamic display mode such as blinking a point or an arrow may be used, or the shape of the point may be changed. These display modes are examples, and any display mode can be adopted as long as the driver can recognize that there is a traffic jam.

  FIG. 12 is a display example of the display 140 after the congestion shown in FIG. 11 is resolved. In this example, it is assumed that the traffic jam judgment unit 120 judges that the traffic jam between P2 and P3 shown in FIG. At this time, the display control unit 138 deletes the arrow A from the screen. On the other hand, the red dots at the points P2 and P3 are displayed as they are without returning to the black dots. As a result, the driver can easily recognize a point where the traffic jam has occurred in the past. Instead of maintaining the red dot, it may be changed to a color other than black and red.

  Once it is determined by the traffic jam judgment unit 120 that a traffic jam has occurred, the map data storage unit 134 sets a flag indicating that traffic jam has occurred in the past in association with the point ID (hereinafter referred to as “past traffic jam flag”). You may do it. By doing so, the display control unit 138 can change the color of the point where the traffic jam has occurred in the past by referring to the flag of the map data storage unit 134. This flag may be time-limited. That is, when a certain period has elapsed from the date and time when the last traffic jam occurred, the point ID display may be returned from the red dot to the black dot.

  In the above description, the past congestion flag is set for each terminal device. However, when the point ID is first recorded in the map data storage unit 134, the past congestion flag is set in advance for the point ID of the location where the congestion frequently occurs. You may make it set.

FIG. 13 is a flowchart of a traffic jam display process based on inter-vehicle communication according to the present embodiment.
First, the traffic jam judgment unit 120 judges whether or not there is traffic jam at a location where each point ID included in the map display range is allocated based on the other vehicle data and the own vehicle data (S12). When it is determined that the traffic jam is determined by the traffic jam judgment unit 120 (Y in S14), the display control unit 138 changes the location where the corresponding spot ID is allocated to a red dot and displays an arrow on the road between the two spot IDs. Displayed (S16). When the traffic jam judgment unit 120 judges that there is no traffic jam (N in S14), the display control unit 138 refers to the past traffic jam flag in the map data storage unit 134, etc. In some cases (Y in S18), the arrow is erased from the screen, but the red dot of the point ID is left as it is (S20). If it is a point that has not been congested before (N in S18), the arrow is deleted from the screen and the red point is returned to the black point (S22).

  Next, a method for determining traffic congestion based on vehicle-to-vehicle communication in the traffic congestion determination unit 120 will be described in detail.

FIG. 14 is a flowchart of the traffic jam determination process in the traffic jam determination unit 120.
The terminal device 150 of each vehicle receives vehicle data transmitted from another vehicle (S30). The direction determination unit 112 identifies the vehicle ID of another vehicle that is traveling in the opposite direction to the host vehicle from the positional relationship between the two point IDs, that is, the already-passed point ID and the next-passed point ID. The transmission data creation unit 116 creates a frame in which the host vehicle data is added to other vehicle data other than the vehicle running backward, and the transmission unit 118 broadcasts and transmits a packet including the frame (S32).

  Subsequently, the traffic jam determination unit 120 determines whether or not traveling information between the same spot IDs has been received from a plurality of vehicles (S34). If it is received from a plurality of vehicles (Y in S34), statistical processing of the traveling speed of all the vehicles is performed (S36). For example, an average speed is calculated or a median speed is selected. This step is performed in order to eliminate the influence on traffic jam judgment by data from other vehicles whose traveling speed is extremely slow or fast.

  When the traveling information between the same spot IDs is only one (N in S34), the traffic jam determining unit 120 determines whether the traveling speed of the vehicle is equal to or less than a predetermined value (S38). When the statistical process of S36 is performed, the traffic jam determination unit 120 determines whether or not the travel speed subjected to the statistical process is equal to or less than a predetermined value. If the traveling speed is greater than the predetermined value (N in S38), the traffic jam judging unit 120 judges that the road in the corresponding section is flowing smoothly (S52).

  If it is determined in S38 that the traveling speed is equal to or less than the predetermined value (Y in S38), it may be immediately determined that there is a traffic jam. However, in actual road conditions, even if the vehicle traveling speed is equal to or less than the predetermined value, the traffic jam occurs. There are cases where it cannot be said. Therefore, in this embodiment, exception processing as described below is executed.

  First, the traffic jam determination unit 120 determines whether or not the received other vehicle data is only for one vehicle (S40). In the case of only one vehicle (Y in S40), the traffic congestion judgment in the corresponding section is handled as reference information (S42). In the case of the reference information, for example, the display control unit 138 may change the display mode from normal, for example, the red arrow indicating the traffic jam on the map of the display 140 may be a dotted line, or the traffic jam may be displayed on the map. You may not make it display to the driver without displaying. The step of S40 is, for example, a situation where one vehicle is stopped due to a break or failure between two point IDs, or a situation where the vehicle is traveling at a low speed for some reason. It is for eliminating.

  When a plurality of vehicle data are received (N in S40), the traffic jam determination unit 120 refers to the map data storage unit 134 and determines whether or not the next passage point ID is “intersection” (S42). ). If it is not an intersection (N in S42), it is determined that the corresponding section is congested (S50).

  When the next passing point ID is an intersection (Y in S42), there is a possibility that the vehicle is stopped simply due to a red signal. Therefore, the traffic jam determination unit 120 determines whether or not the same data has been received from the same vehicle ID for a predetermined time (for example, the average duration of the red light) or more (S44), and further, the predetermined value or more. It is determined whether the same data is received from the number of vehicles (S46). If the determination is affirmative in S44 or S46 (Y in S44 or Y in S46), it is determined that there is a traffic jam. If both determinations in S44 and S46 are negative (N in S44 and N in S46), it is determined that the corresponding section is flowing smoothly (S52).

  Steps S44 and S46 take into account the case where the vehicle is stopped at a red light at an intersection. If similar data has been received for a relatively long time from a certain number of vehicles or more, some of the vehicles waiting for traffic lights at the intersection cannot pass through the intersection during the green light, causing congestion. It is because it is thought that it is.

  Next, referring to an example of a vehicle arrangement situation, a specific traffic jam determination state according to the flowchart of FIG. 14 will be described.

  15 and 16 show a state where a map and a vehicle are displayed on the display 140. The map and point ID shown in the figure are the same as those shown in FIGS. In addition, FIG. 15 and FIG. 16 show five vehicles CAR1 to CAR5 and their traveling directions. Of these, CAR1 is the host vehicle, and CAR2 to CAR5 are other vehicles. Further, it is assumed that the host vehicle CAR1 is traveling at 40 km / h.

  FIG. 15 shows a display example of the display when the vehicle is running smoothly on each road and there is no traffic jam. At this time, the own vehicle CAR1 transmits the existing passing point ID: P1, the next passing point ID: P2, the traveling speed: 40 km / h, and the own vehicle ID: CAR1 as own vehicle data. The own vehicle CAR1 also performs multi-hop transmission on the other vehicle data received from the other vehicles CAR2 to CAR4. However, as for other vehicle data of CAR5, it can be seen that the vehicle is traveling in the opposite direction from the own vehicle CAR1 from the two point IDs (in this case, the existing passing point ID: P2 and the next passing point ID: P1). Exclude from multi-hop transmission.

  Here, assuming that the other vehicles CAR2 to CAR4 are traveling at a speed of 40 km / h or higher, the terminal device of the host vehicle CAR1 determines that the section in which each vehicle is traveling is not congested and is in good condition. To do. In addition, when the speed of CAR2 is 0 km / h, there is no information from vehicles other than CAR2 between P2 and P3, so whether it is stopped due to traffic jams, or just stopped due to a break, The terminal device of CAR1 cannot be distinguished. For this reason, the traffic jam judgment unit processes the traffic jam between P2 and P3 as reference information.

  FIG. 16 shows a display example of the display when a traffic jam occurs at the intersection corresponding to the spot ID: P3. In this example, the own vehicle CAR1 receives the other vehicle data of CAR2 to CAR5, and the traffic jam judgment unit knows that their speed is 0 km / h. However, since the traffic jam judgment unit knows that P3 is an intersection from the related information of the spot ID: P3, it has received the same data for more than a predetermined time from CAR2 to CAR5, and the same number of units more than the predetermined value. Only when data is received, it is determined that traffic between P2 and P3 is a traffic jam.

  As described above, according to the present embodiment, it is possible to determine a traffic jam only by inter-vehicle communication. Because multiple vehicle data is transferred between vehicles by multi-hop communication, it is possible to determine the presence or absence of traffic jams even in places where roadside units are not installed or where roadside units are not installed. .

  Conventionally, vehicle information is probed by a roadside machine such as VICS, a traffic jam is determined at the center to which the roadside machine is connected, and the result is returned to the vehicle. In this method, since it is possible to determine traffic jams only at intervals between roadside devices on the road, it is not possible to capture traffic jams that occur before parking, for example. In addition, it is not possible to detect a traffic jam on a road where no roadside machine is set.

  On the other hand, according to the present embodiment, it is possible to make a traffic jam determination without depending on the roadside machine by communicating between the vehicles even in a place where the roadside machine is not installed. Therefore, it is possible to reduce the installation cost of the roadside machine, to make the judgment of traffic jam in real time, and to judge the traffic jam in a narrow street where no roadside machine is installed.

  Further, according to the present embodiment, the point ID is set in the map data mounted on the vehicle navigation system or the like. This point ID is set at an interval shorter than the intersection information in the conventional map data. For example, assign a point ID to a point where traffic congestion is likely to occur due to vehicles staying at other than major intersections, such as small intersections, entrances to stores and parking lots, intersections between main roads and alleys, etc. In this way, it is possible to determine the presence or absence of traffic for each fine section between point IDs.

  In addition, traffic congestion information in a finer range than before can be provided to the driver by highlighting the traffic congestion for each point ID and for each section between the point IDs. In addition, even after it is determined that the traffic jam has been resolved, the points where traffic jams have occurred within the predetermined period in the past are maintained highlighted, unlike other points. Therefore, the driver can recognize a point where traffic congestion is likely to occur on the map.

  In addition, since the vehicle data is transferred between vehicles by the multi-hop method, it is possible to receive other vehicle data existing far away from the host vehicle. This makes it possible to determine traffic jams over a wide range.

The following aspects are also included in the present invention.
Map data used for traffic jam prediction by inter-vehicle communication,
Map data characterized in that a point ID as identification information is allocated to a point that matches a predetermined condition for determining a place where traffic congestion is likely to occur on a road in the map data.
According to this aspect, it is possible to subdivide the road section in which the traffic information is displayed and provide the traffic information in the detailed section to the driver.

  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. Hereinafter, such modifications will be described.

  In the embodiment, it has been described that a traffic jam is determined using the speed of the vehicle. Instead of this, or in combination with this, the traffic jam may be determined based on the density of the vehicle. The traffic jam judgment unit can calculate the vehicle density of the road between the two point IDs when the traveling information between the same point IDs is received from a plurality of vehicles. Can be judged to be congested.

  For example, in the example shown in FIG. 16, since the distance between P2 and P3 is obtained from the map data, the vehicle density between P2 and P3 is calculated by counting the number of other vehicles having the same point ID. Can do. If the vehicle density is equal to or higher than a predetermined value, it is determined that the section is congested.

  In addition, when the terminal device according to the above-described embodiment is not sufficiently widespread, only the data of some vehicles are communicated between vehicles, and thus the vehicle density cannot be accurately calculated. Therefore, even if the terminal device is configured to be able to add traffic judgment based on speed to the default setting, and traffic congestion judgment based on vehicle density can be added by changing the settings or upgrading the software when the terminal device is widely used. Good.

  According to the present invention, it is possible to determine the presence or absence of traffic jam based on inter-vehicle communication.

  102 RF unit, 104 modulation / demodulation unit, 160 traffic jam display processing unit, 112 direction determination unit, 114 vehicle speed calculation unit, 116 transmission data creation unit, 120 traffic jam judgment 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.

Claims (8)

A terminal device mounted on a vehicle to perform inter-vehicle communication,
A transmission data creation unit configured to receive vehicle data including at least information related to the speed and position of the vehicle from another vehicle and configure a transmission frame together with the vehicle data of the host vehicle;
A transmitter that broadcast-transmits a packet including the transmission frame;
A terminal device comprising: A map data storage unit that holds map data in which a point ID as identification information is allocated to a point that matches a predetermined condition for determining a place where traffic congestion is likely to occur;
A vehicle speed calculation unit for determining the traveling speed of the vehicle;
A position acquisition unit for acquiring the current position of the vehicle;
A traffic jam judgment unit that judges the presence or absence of traffic jam based on vehicle data received from another vehicle,
The transmission data creation unit creates vehicle data including a point ID of a point where the host vehicle last passed, a point ID of a point that passes next, a traveling speed, and a vehicle ID assigned to each vehicle,
The traffic jam judging unit judges that a road between two point IDs included in the vehicle data is congested when the traveling speed included in the vehicle data received from another vehicle is equal to or lower than a predetermined speed. The terminal device according to claim 1.   When the density of vehicles existing between two point IDs included in the vehicle data received from another vehicle is equal to or higher than a predetermined value, the traffic jam judging unit is congested with a road between the two point IDs. The terminal device according to claim 2, wherein the terminal device is determined to be.   The traffic jam judging unit receives the same vehicle data from the same other vehicle for a predetermined time or more when the next passing point included in the vehicle data received from the other vehicle is an intersection, or predetermined The terminal device according to claim 2, wherein the terminal device is determined to be a traffic jam when the same vehicle data is received from more vehicles than the number of vehicles.   The said traffic congestion judgment part performs a different process from the case where the vehicle data is received from several other vehicles, when the vehicle data is received from one other vehicle. The terminal device described in 1.   In addition to the point IDs assigned according to the predetermined condition, the map data storage unit holds map data in which the point IDs are further assigned to places where the point IDs are divided at regular intervals or equally divided parts. The terminal device according to claim 2, wherein: A display control unit for displaying a map image of a predetermined range around the host vehicle on the display based on the map data;
When the traffic determination unit determines that the road between the two point IDs is congested, the display control unit determines that the two point IDs on the map image and the position of the road between them are congested. 5. The terminal device according to claim 2, wherein an identification display is displayed.   The map data storage unit sets a past traffic jam flag indicating that traffic jam has occurred in the past in association with the point ID when the traffic jam judgment unit determines that the road between the two site IDs is jammed. The display control unit refers to a past traffic jam flag stored in a map data storage unit and displays a color of a spot where traffic jam occurred in the past on the map image. Terminal equipment.

Images