JP2012003354A - Base station device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique to estimate occurrence of congestion in a short term utilizing an intelligent transportation system (ITS).SOLUTION: A processing part 26 receives at least one signal sent from a terminal mounted on a vehicle and including identification numbers to identify roads passed, a period of time that was required for passage of the roads, and information on a time of day at which the period was measured. An estimation part 44 estimates occurrence of congestion for each road corresponding to each of the identification numbers by classifying a period of time and a time of day according to identification number based on the received signal. A generation part 46 broadcasts a signal including information on the estimated occurrence of congestion.

Description

  The present invention relates to communication technology, and more particularly to a base station apparatus that transmits and receives a signal including predetermined information.

  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, if it is the form which communicates information between vehicle-to-vehicle communication, ie, vehicle 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), etc., and the position information is exchanged between the vehicle-mounted devices so that the own vehicle and the other vehicle enter the intersection respectively. (See, for example, Patent Document 1).

JP 2005-202913 A

  In a wireless LAN (Local Area Network) compliant with a standard such as IEEE 802.11, an access control function called CSMA / CA (Carrier Sense Multiple Access Collision Aviation) is used. Therefore, in the wireless LAN, the same wireless channel is shared by a plurality of terminal devices. In such CSMA / CA, a packet signal is transmitted after confirming that no other packet signal is transmitted by carrier sense. When the wireless LAN is applied to inter-vehicle communication such as ITS (Intelligent Transport Systems), it is necessary to transmit information to an unspecified number of terminal devices, and thus it is desirable that the signal be transmitted by broadcast. Furthermore, if the road-to-vehicle communication is executed in addition to the vehicle-to-vehicle communication, the communication forms are various.

  By using ITS, reduction of vehicle collision accidents is desired, and early grasping of traffic jam information is desired. Since the traffic jam occurs over a certain distance, the traffic jam information is generally generated by a server capable of collecting information on a wide area. Since the server processes information in a wide area, a delay occurs until the occurrence of a traffic jam is recognized. On the other hand, information on whether one intersection is congested is related to a local area, and can be generated without a server. Therefore, it is desired to shorten the period until the occurrence of traffic jam is recognized.

  This invention is made | formed in view of such a condition, The objective is to provide the technique which estimates congestion occurrence in a short time by using ITS.

  In order to solve the above problems, a base station apparatus according to an aspect of the present invention is a signal from a terminal apparatus mounted on a vehicle, and an identification number for identifying a road that has passed, By categorizing the period and time for each identification number based on the signal received at the reception unit that receives at least one signal containing information on the time when the period was measured, and the time when the period was measured, An estimation unit that estimates the occurrence of traffic jam for each road corresponding to the identification number, and a notification unit that reports a signal including information related to the occurrence of traffic jam estimated by the estimation unit.

  Another aspect of the present invention is also a base station apparatus. This device is a signal from a terminal device mounted on a vehicle and receives at least one signal including position information of the vehicle, and the occurrence of traffic congestion based on the signal received at the receiving unit. Including an estimation unit for estimating the traffic light, an instruction unit for adjusting the lighting period of each color based on the occurrence of traffic jam estimated by the estimation unit, and information on the lighting period of each color adjusted by the instruction unit A notification unit for reporting the received signal.

  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, the occurrence of traffic jam can be estimated in a short time by using ITS.

It is a figure which shows the structure of the communication system which concerns on the Example of this invention. It is a figure which shows the structure of the base station apparatus of FIG. FIGS. 3A to 3D are diagrams showing frame formats defined in the communication system of FIG. FIGS. 4A to 4B are diagrams illustrating the configuration of the subframes of FIGS. 3A to 3D. FIGS. 5A and 5B are diagrams showing a format of a MAC frame stored in a packet signal defined in the communication system of FIG. It is a figure which shows the information contained in the data payload of Fig.5 (a). It is a figure which shows the structure of the terminal device mounted in the vehicle of FIG. It is a figure which shows the screen displayed in the notification part of FIG. It is a sequence diagram which shows the notification procedure in the communication system of FIG. It is a figure which shows the structure of the base station apparatus which concerns on the modification of this invention. It is a sequence diagram which shows the change procedure in the communication system which concerns on the modification of this invention.

  Before describing the present invention in detail, an outline will be described. Embodiments of the present invention relate to a communication system that performs vehicle-to-vehicle communication between terminal devices mounted on a vehicle, and also executes road-to-vehicle communication from a base station device installed at an intersection or the like to a terminal device. As inter-vehicle communication, the terminal device broadcasts and transmits 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. Here, the base station apparatus repeatedly defines a frame including a plurality of subframes. The base station apparatus selects any of a plurality of subframes for road-to-vehicle communication, and broadcasts a packet signal in which control information and the like are stored during 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. Here, the terminal device transmits a packet signal by the CSMA method in a period for performing vehicle-to-vehicle communication other than the road-vehicle transmission period (hereinafter referred to as “vehicle transmission period”).

  There is a demand to quickly recognize the occurrence of traffic jams even in a local area. In order to realize this, it is desirable to estimate the occurrence of traffic congestion in each base station device, not a server connected to a plurality of base station devices via a network. In order to cope with this, the terminal apparatus according to the present embodiment reports information on the time required for traveling on the road to the base station apparatus. The base station device accepts information from a plurality of terminal devices and organizes the information for each road, thereby estimating the occurrence of a traffic jam. The base station apparatus notifies the estimation result to the terminal apparatus. Further, the terminal apparatus may notify the received estimation result to another base station apparatus. As a result, it becomes possible to notify the occurrence of traffic congestion in a wide area. In the following description, for example, a base station device corresponds to a roadside device, and a terminal device corresponds to a vehicle-mounted device.

  FIG. 1 shows a configuration of a communication system 100 according to an embodiment of the present invention. 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. , An eighth vehicle 12h, a first traffic light 16a, a second traffic light 16b, a third traffic light 16c, a traffic light 16 collectively referred to as a fourth traffic light 16d, and a network 202. Each vehicle 12 is equipped with a terminal device (not shown). The area 212 is formed around the base station apparatus 10, and the outside area 214 is formed outside the area 212.

  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. A first traffic light 16a is installed for the vehicle 12 traveling from left to right, a second traffic signal 16b is installed for the vehicle 12 traveling from right to left, and a second traffic signal 16b is installed for the vehicle 12 traveling from top to bottom. A third traffic light 16c is installed, and a fourth traffic light 16d is installed for the vehicle 12 moving from the bottom to the top. Base station apparatus 10 is arranged in association with traffic light 16.

  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 notifies the packet signal in the set road and vehicle transmission period. A plurality of types of data are assumed as data to be included in the packet signal. For example, data such as traffic jam information and construction information. The base station apparatus 10 notifies the RSU packet signal as a packet signal including these data during the road and vehicle transmission period.

  The packet signal from the base station apparatus 10 also includes information related to the set road and vehicle transmission period, and this information corresponds to control information. 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. Moreover, a terminal device alert | reports a packet signal by carrier sense in a vehicle transmission period. 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, a terminal device that cannot receive a packet signal from the base station device 10, that is, a terminal device existing outside the area 214 broadcasts the packet signal by executing CSMA / CA regardless of the frame configuration. Furthermore, the terminal device notifies the driver of the approach of the vehicle on which the other terminal device is mounted by receiving a packet signal from the other terminal device. Here, identification information for identifying each road is defined in advance. For example, one traveling direction is defined as one road between adjacent intersections. Therefore, even in the same section, if the traveling direction is different, it is defined as another road.

  The terminal apparatus measures a required period when traveling on one road, and includes the combination of the period and the identification number in the packet signal and transmits the packet signal to the base station apparatus. Since the base station apparatus can specify the road from the identification number, the speed is calculated from the combination of the period and the identification number. Furthermore, the base station apparatus estimates the occurrence of traffic congestion for each identification number by classifying the speed for each identification number. The base station apparatus broadcasts and transmits a packet signal including information related to the occurrence of traffic congestion (hereinafter referred to as “congestion information”). The terminal device notifies the driver of the occurrence of traffic jam.

  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, an IF unit 32, and a network communication unit 80. The processing unit 26 includes a frame definition unit 40, a selection unit 42, an estimation unit 44, a generation unit 46, and a storage unit 48. 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 frame defining unit 40 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 frame defining unit 40 generates a plurality of frames based on the time information. For example, the frame defining unit 40 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 frame defining unit 40 may detect the control information from the demodulation result and generate a frame based on the detected control information. Such processing corresponds to generating a frame synchronized with the timing of the frame formed by another base station apparatus 10. 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 8, a subframe having a length of 12.5 msec is defined. The description of FIGS. 3B to 3D will be described later and returns to FIG.

  The selection part 42 selects the sub-frame which should set a road and vehicle transmission period among several sub-frames contained in the flame | frame. More specifically, the selection unit 42 receives a frame defined by the frame defining unit 40. The selection unit 42 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. The selection unit 42 extracts a demodulation result from another base station apparatus 10 from the input demodulation results. The extraction method will be described later. The selection unit 42 identifies the subframe that has not received the demodulation result by specifying the subframe that has received the demodulation result. This corresponds to specifying a subframe in which the road and vehicle transmission period is not set by another base station apparatus 10, that is, an unused subframe. When there are a plurality of unused subframes, the selection unit 42 selects one subframe at random. When there are no unused subframes, that is, when each of a plurality of subframes is used, the selection unit 42 acquires reception power corresponding to the demodulation result, and gives priority to subframes with low reception power. Select

  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. Returning to FIG. The selection unit 42 outputs the selected subframe number to the generation unit 46.

  The generation unit 46 sets a road and vehicle transmission period in the subframe of the subframe number received from the selection unit 42, and generates an RSU packet signal to be notified during the road and vehicle transmission period. FIGS. 4A to 4B show subframe configurations. FIG. 4A shows a subframe in which a road and vehicle transmission period is set. As illustrated, one subframe is configured in the order of a road and vehicle transmission period and a vehicle and vehicle transmission period. FIG. 4B shows the arrangement of packet signals during the road and vehicle transmission period. As illustrated, a plurality of RSU packet signals are arranged in the road and vehicle transmission period. Here, the front and rear packet signals are separated by SIFS (Short Interframe Space).

  Here, the configuration of the RSU packet signal will be described. 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”, “LLC header”, “message header”, “data payload”, and “FCS” are arranged in order from the top. Information included in the data payload will be described later. FIG. 5B is a diagram illustrating a configuration of a message header generated by the generation unit 46. The message header includes a basic part. The basic part includes “protocol version”, “transmission node type”, “number of reuses”, “TSF timer”, and “RSU transmission period length”. The protocol version indicates the version of the corresponding protocol. The transmission node type indicates the transmission source of the packet signal including the MAC frame. For example, “0” indicates a terminal device, and “1” indicates the base station device 10. When the selection unit 42 extracts a demodulation result from another base station apparatus 10 from among the input demodulation results, the selection unit 42 uses the value of the transmission node type. The reuse count indicates an index of validity when the message header is transferred by the terminal device, and the TSF timer indicates the transmission time. The RSU transmission period length indicates the length of the road and vehicle transmission period, and can be said to be information relating to the road and vehicle transmission period. Returning to FIG.

  The network communication unit 80 is connected to a network 202 (not shown). The network communication unit 80 receives construction information, regulation information, and the like from the network 202. The storage unit 48 stores accepted construction information, regulation information, and the like. The IF unit 32 is connected to a traffic light 16 (not shown). The IF unit 32 receives traffic signal information from the traffic signal 16. The storage unit 48 stores the received traffic signal information. The traffic signal information includes intersection information, signal information for each route, and the like. The intersection information is information regarding the intersection where the traffic light 16 is installed, and indicates the latitude, longitude, and number of routes of the intersection.

  The number of roads is the number of roads extending from the intersection. In the case of FIG. 1, the number of roads is “4”, which is a road heading north, a road heading south, a road heading east, and a road heading west. In addition, signal information is defined for each road. The signal information includes signal lamp color information. The signal light color information indicates the light color of the traffic light. However, since the light color of the traffic light changes periodically, it is shown here in the form of a schedule. For example, it is shown that “from 12:00:00 to 12:02:59” is “red” and from 12:03:00 to 12:05:59 is “blue”. Moreover, the identification number for identifying each road may be provided. Here, one road is defined in units of adjacent intersections. One road corresponds to one traveling direction.

  The generation unit 46 extracts construction information, regulation information, etc. and traffic signal information stored in the storage unit 48 and stores them in the data payload. In particular, since the change of the content of the traffic signal information has a shorter cycle than the change of the content of the traffic jam information, the construction information, etc., the generation unit 46 extracts the traffic signal information more frequently than the traffic jam information, the construction information, etc. FIG. 6 shows information included in the data payload. Here, a case where signal information is included is shown. The data payload includes intersection information and route M signal information. The intersection information is as described above. The route M signal information is signal information for the Mth route. As described above, each road is given an identification number, and the direction of the road corresponding to each identification number is also known. Therefore, signal information corresponding to any of the first traffic light 16a to the fourth traffic light 16d in FIG. Can be specified. Returning to FIG. 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.

  The processing unit 26 receives a packet signal from at least one terminal device via the modem unit 24. The packet signal relates to an identification number for identifying a road on which the vehicle 12 equipped with the terminal device has passed, a period required for passing the road (hereinafter referred to as “passing period”), and a time at which the passing period is measured. Contains information. The processing unit 26 outputs these pieces of information to the estimation unit 44.

  The estimation unit 44 receives information from the processing unit 26. The estimation unit 44 classifies the passage period and time for each identification number. Next, the estimation unit 44 derives an average passage period by thinning out extremely short passage periods or extremely long passage periods and averaging the remaining passage periods. In order to specify an extremely short passage period or an extremely long passage period, the estimation unit 44 determines a threshold value in advance. Note that a passing period whose measured time is older than a certain period is also excluded from the averaging process. Further, the estimation unit 44 acquires the road distance corresponding to the identification number by accessing the storage unit 48.

  Here, the storage unit 48 stores in advance the correspondence between the identification number and the road distance. The estimation unit 44 derives the average speed by dividing the distance by the average passage period. When the average speed is lower than a certain value, the estimation unit 44 estimates that traffic congestion has occurred on the road. That is, the estimation unit 44 estimates the occurrence of traffic jam for each road corresponding to the identification number. The estimation unit 44 outputs the estimation result to the generation unit 46 as traffic jam information. The generation unit 46 generates a packet signal storing the traffic jam information from the estimation unit 44, and broadcasts the packet signal via the modem unit 24 and the like.

  A terminal device that has received a packet signal broadcast-transmitted from the base station device 10 and includes traffic jam information updates the traffic jam information, and broadcasts the packet signal including the updated traffic jam information May be. 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. 7 shows a 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 acquisition unit 72, and a storage unit 74. The timing specifying unit 60 includes an extraction unit 66 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, the modem unit 54 and the processing unit 56 receive the packet signal from the base station apparatus 10 during the road and vehicle transmission period. As described above, the modem unit 54 and the processing unit 56 receive packet signals from other terminal devices 14 during the vehicle transmission 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. At that time, the extraction unit 66 estimates that it exists in the area 212 of FIG. The extraction unit 66 generates a frame based on the timing of the subframe and the content of the message header of the packet signal, specifically, the content of the RSU transmission period length. Note that the generation of the frame only needs to be performed in the same manner as the frame defining unit 40 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.

  On the other hand, when the extraction unit 66 has not received the RSU packet signal, the extraction unit 66 estimates that the extraction unit 66 exists outside the area 214 in FIG. When it is estimated that the extraction unit 66 exists in the area 212, the extraction unit 66 selects the vehicle transmission period. When it is estimated that the extraction unit 66 exists outside the area 214, the extraction unit 66 selects a timing unrelated to the frame configuration. When the vehicle transmission 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 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 during the vehicle transmission period. Moreover, the carrier sense part 94 determines the transmission timing in a vehicle transmission period based on 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 acquisition unit 72 includes a GPS receiver (not shown), a gyroscope, a vehicle speed sensor, and the like. Based on data supplied from these, the location of the vehicle 12 (not shown), that is, the position of the vehicle 12 on which the terminal device 14 is mounted, the progress The direction, the moving speed, etc. (hereinafter collectively referred to as “position information”) are acquired. 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 acquisition unit 72 outputs the position information to the generation unit 64.

  The transfer determining unit 90 controls message header transfer. The transfer determining unit 90 extracts a message header from the packet signal. When the packet signal is directly transmitted from the base station apparatus 10, the reuse count is set to “0”. However, when the packet signal is transmitted from another terminal apparatus 14, the reuse is performed. The number of times is set to a value of “1 or more”. The transfer determining unit 90 selects a message header to be transferred from the extracted message header. Here, for example, the message header with the smallest number of reuses is selected. Further, the transfer determination unit 90 may generate a new message header by combining the contents included in the plurality of message headers. The transfer determination unit 90 outputs the message header to be selected to the generation unit 64. At that time, the transfer determining unit 90 increases the number of reuses by “1”.

  The generation unit 64 receives position information from the acquisition unit 72 and receives a message header from the transfer determination unit 90. The generation unit 64 stores the position information in the data payload using the MAC frame shown in FIGS. The generation unit 64 generates a packet signal including a MAC frame, and broadcasts the generated packet signal via the modem unit 54, the RF unit 52, and the antenna 50 at the transmission timing determined by the carrier sense unit 94. Send. The transmission timing is included in 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. As a process for the acquired packet signal, the notification unit 70 notifies the driver of the approach of another vehicle 12 (not shown) or the like via a monitor or a speaker in accordance with the content of data stored in the packet signal. When the packet signal from the base station apparatus 10 (not shown) includes traffic jam information, the notification unit 70 notifies the traffic jam information. FIG. 8 shows a screen displayed on the notification unit 70. As shown, the occurrence of traffic jams is shown. Returning to FIG.

  The storage unit 74 stores information on road routes for each road identification number. The road route is position information of the start point of the road and position information of the end point of the road. In addition, the position information of the intermediate point of the road may be included. The acquisition unit 72 refers to the storage unit 74 based on the position information received from the acquisition unit 72 and identifies the road that is currently running. Moreover, the acquisition part 72 measures the passage period with respect to the specified road. The generation unit 64 generates a packet signal indicating the identification information, passage period, and time, and broadcasts the packet signal from the modem unit 54 and the like. When the storage unit 74 stores the traffic jam information, when the storage unit 74 receives the new traffic jam information, the memory unit 74 may update the traffic jam information by storing the new traffic jam information. This corresponds to synchronization with traffic jam information in the base station apparatus 10. The control unit 58 controls the operation of the entire terminal device 14.

  The operation of the communication system 100 configured as above will be described. FIG. 9 is a sequence diagram illustrating a notification procedure in the communication system 100. The terminal device 14 generates information on the road that has passed (S10). The terminal device 14 transmits a packet signal including information (S12). The base station apparatus 10 estimates the occurrence of a traffic jam (S14). The base station apparatus 10 broadcasts a packet signal indicating the occurrence of traffic jam (S16). The terminal device 14 notifies the occurrence of a traffic jam (S18).

  Next, a modified example of the present invention will be described. When the occurrence of traffic congestion is estimated based on information from the terminal device, the base station apparatus according to the embodiment notifies the estimation result as traffic congestion information. When the base station apparatus according to the modified example also estimates the occurrence of a traffic jam, the base station device reports the estimation result as traffic jam information. Furthermore, the base station device stabilizes the traffic flow by extending the blue light period of the traffic light connected to the base station device when one of the intersections is congested with the other. Plan. In addition, the traffic light adjacent to the traffic light whose period of the blue light color is extended also extends the blue light color period of the traffic light. The communication system 100 according to the modification of the present invention is the same type as that shown in FIG. 1, and the terminal device 14 is the same type as that shown in FIG. Hereinafter, the difference will be mainly described.

  FIG. 10 shows the configuration of the base station apparatus 10 according to a modification of the present invention. In the base station apparatus 10, an instruction unit 28 is added to the base station apparatus 10 illustrated in FIG. The instruction unit 28 receives the estimation result from the estimation unit 44. Based on the estimation result from the estimation unit 44, the instruction unit 28 causes the traffic light 16 (not shown) to adjust the lighting period of each color via the IF unit 32. If it demonstrates concretely, the instruction | indication part 28 will identify the road where the traffic jam has occurred based on the estimation result, and will identify the traffic light 16 corresponding to the identified road. This is equivalent to specifying one of the first traffic light 16a to the fourth traffic light 16d shown in FIG.

  The instruction unit 28 instructs the traffic light 16 via the IF unit 32 to extend the period of the green light in the identified traffic light 16 and the traffic light 16 corresponding to the road in the traveling direction opposite to the identified road. For example, the green signal time is extended by about 10 seconds from the normal time. However, such extension is limited to about 15 to 30 minutes. On the other hand, the instruction unit 28 instructs the remaining traffic light 16 installed at the same intersection as the traffic light 16 with the extended green light period to shorten the period of the green light via the IF unit 32. When the lamp color period is changed in the traffic light 16, the IF unit 32 receives the traffic signal information from the traffic light 16 again. The storage unit 48 updates the traffic signal information with the received traffic signal information. Moreover, the production | generation part 46 carries out the broadcast transmission of the packet signal containing the updated signal information.

  The processing unit 26 is also a packet signal from another base station device 10 via the RF unit 22 and the modulation / demodulation unit 24, and also includes a packet signal including signal information adjusted by the other base station device 10. Accept. As described above, the traffic signal information includes information on the lighting period of each color. The estimation unit 44 also reflects the adjusted traffic signal information, and identifies the traffic signal 16 that should extend the period of the green light. For example, the estimation unit 44 identifies the traffic light 16 corresponding to the traffic light 16 extended in the period of the green light and directed to the traffic light 16 installed at another intersection. The instruction unit 28 causes the traffic light 16 (not shown) to adjust the lighting period of each color via the IF unit 32. That is, the instruction unit 28 instructs the traffic light 16 through the IF unit 32 so as to extend the period of the green signal in the traffic light 16 specified by the estimation unit 44. As a result, the green signal period is extended in conjunction with the traffic light 16 next to the traffic light 16 that has extended the green signal period.

  FIG. 11 is a sequence diagram showing a change procedure in the communication system 100 according to the modification of the present invention. The terminal device 14 generates information on the road that has passed (S30). The terminal device 14 transmits a packet signal including information (S32). The first base station apparatus 10a estimates the occurrence of a traffic jam (S34), and instructs the traffic light 16 to change the lighting cycle (S36). The first base station apparatus 10a broadcasts and transmits a packet signal indicating the lighting cycle (S38, S40). The second base station apparatus 10b instructs the traffic light 16 to change the lighting cycle (S42). The terminal device 14 notifies the occurrence of a traffic jam (S44).

  According to the embodiment of the present invention, since the average speed is derived by arranging the passage period and time for the identification number assigned to each road, it is possible to estimate the occurrence of traffic congestion for each road. Moreover, since the occurrence of the traffic jam is estimated in the base station apparatus, the traffic jam can be quickly estimated. In addition, when the average speed is derived, extremely high speed vehicles and extremely low speed vehicles are excluded, so that it is possible to improve the estimation accuracy of occurrence of traffic jams. In addition, since the occurrence of the traffic jam is notified to the terminal device, the driver can recognize the traffic jam in advance. Moreover, since the lighting cycle of the traffic light is changed according to the occurrence of traffic jam, the size of the traffic jam can be reduced. In addition, since the traffic signal information is updated and notified, the surrounding base station apparatus can be notified of the change in the lighting cycle. In addition, since the change of the lighting cycle is notified to surrounding base station apparatuses, the scale of the traffic jam can be reduced.

  Also, since the subframe used by the other base station apparatus is specified based on the packet signal received from the terminal apparatus as well as the packet signal directly received from the other base station apparatus, The frame identification accuracy can be improved. In addition, since the accuracy of identifying subframes in use is improved, the probability of collision between packet signals transmitted from the base station apparatus can be reduced. Moreover, since the collision probability between packet signals transmitted from the base station apparatus is reduced, the terminal apparatus can accurately recognize the control information. Further, since the control information is accurately recognized, the road and vehicle transmission period can be accurately recognized. Further, since the road and vehicle transmission period is accurately recognized, the collision probability of the packet signal can be reduced.

  In addition, since a subframe other than the currently used subframe is used preferentially, it is possible to reduce the possibility of transmitting a packet signal at a timing overlapping with packet signals from other base station apparatuses. Further, when any subframe is used by another base station apparatus, a subframe with low received power is selected, so that the influence of packet signal interference can be suppressed. Further, since the received power of the terminal device is used as the received power from another base station device that is the transmission source of the control information relayed by the terminal device, the received power estimation process can be simplified.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In the embodiment of the present invention, the frame defining unit 40 includes a road and vehicle transmission period and a vehicle and vehicle transmission period in the frame. However, the present invention is not limited to this. For example, the frame defining unit 40 may provide a period for the terminal apparatus 14 to transmit a packet signal to the base station apparatus 10 in addition to the road and vehicle transmission period and the vehicle transmission period. According to this modification, it is possible to reduce the collision probability between the packet signal from the base station device 10 to the terminal device 14, the packet signal for communication between the terminal devices 14, and the packet signal from the terminal device 14 to the base station device 10.

  10 base station device, 12 vehicle, 14 terminal device, 16 traffic signal, 20 antenna, 22 RF unit, 24 modulation / demodulation unit, 26 processing unit, 28 instruction unit, 30 control unit, 32 IF unit, 40 frame defining unit, 42 selection unit 44 estimation unit, 46 generation unit, 48 storage unit, 50 antenna, 52 RF unit, 54 modulation / demodulation unit, 56 processing unit, 58 control unit, 60 timing identification unit, 64 generation unit, 66 extraction unit, 70 notification unit, 72 An acquisition unit, 74 storage unit, 80 network communication unit, 90 transfer determination unit, 94 carrier sense unit, 100 communication system.

Claims (3)

At least one signal that is a signal from a terminal device mounted on a vehicle and that includes an identification number for identifying a road that has passed, a period required to pass through the road, and information about the time at which the period was measured A receiving unit for receiving;
Based on the signal received in the receiving unit, by classifying the period and time for each identification number, an estimation unit that estimates the occurrence of traffic jams for each road corresponding to the identification number;
An informing unit for informing a signal including information related to occurrence of traffic jam estimated in the estimating unit;
A base station apparatus comprising: A receiving unit that receives at least one signal that is a signal from a terminal device mounted on a vehicle and includes vehicle position information;
Based on the signal received by the receiver, an estimation unit that estimates the occurrence of traffic jams;
Based on the occurrence of traffic jam estimated in the estimation unit, for the traffic light, an instruction unit for adjusting the lighting period of each color;
An informing unit for informing a signal including information on the lighting period of each color adjusted by the instruction unit;
A base station apparatus comprising: The receiving unit is also a signal from another base station device, and also receives a signal including information on the lighting period of each color adjusted by the other base station device,
The said instruction | indication part reflects the information contained in the signal received from the other base station apparatus in the said receiving part, and makes a traffic light adjust the lighting period of each color, The said characteristic is characterized by the above-mentioned. Base station equipment.

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