JP2019213194A - Communication system, communication method, and communication program - Google Patents

Abstract

To provide a communication system or the like with improved convenience and performance.SOLUTION: A road side communication device 5 and an on-vehicle communication device 4 that are capable of performing communication by a first radio communication system and a second radio communication system where a radio wave arrival distance is shorter than that of the first radio communication system are adopted as communication nodes in a communication system 1. The first communication node and the second communication node mutually exchange connection information related to the second radio communication system by radio communication related to the first radio communication system, perform connection establishment processing of the second radio communication system on the basis of connection information, and exchange real data by radio communication related to the second radio communication system.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a communication system using a roadside communication device and an in-vehicle communication device as a communication node.

  Conventionally, the present inventor has developed road-to-vehicle communication technology, vehicle-to-vehicle communication technology, cloudlet technology, etc., in order to provide road conditions to vehicles in real time or to secure a communication environment at the time of a large-scale disaster. It is carried out. Patent Documents 1 to 3 disclose roadside communication devices, in-vehicle communication devices, and in-vehicle cloudlets that can realize efficient data transfer.

Japanese Patent Application No. 2017-066643 Japanese Patent Application No. 2017-066474 Japanese Patent Application No. 2017-066645

  It is an object of the present invention to further improve convenience and performance of a communication system using a roadside communication device and an in-vehicle communication device as a communication node. As a concrete problem, in the past demonstration experiments, it is necessary to fix to the infrastructure mode when performing road-to-vehicle communication, and to the ad hoc mode when performing vehicle-to-vehicle communication. Could not communicate in both modes. In addition, it takes time to establish connection for road-to-vehicle communication and vehicle-to-vehicle communication, and radio wave reception intensity decreases due to the physical positional relationship of antennas used for road-to-vehicle communication and vehicle-to-vehicle communication. The actual data transfer capacity could not be secured.

  An object of the present invention is to solve the above-described problems and provide a communication system and the like with improved convenience and performance.

  A first invention for achieving the above-mentioned object is a roadside communication apparatus capable of communicating by a first wireless communication method and a second wireless communication method having a shorter radio wave reach than the first wireless communication method, and A communication system in which an in-vehicle communication device serves as a communication node, wherein the first communication node broadcasts its presence by wireless communication according to the first wireless communication method, and the first communication A second communication node different from the node transmits broadcast response means for responding to the broadcast by wireless communication according to the first wireless communication method, and the first communication node and the second communication node include the first communication node. Connection information transmission / reception means for transmitting / receiving connection information according to the second wireless communication method by wireless communication according to the first wireless communication method; A connection establishment means for causing the first communication node and the second communication node to perform connection establishment processing of the second wireless communication system based on the connection information by wireless communication according to the first wireless communication system; The first communication node and the second communication node comprise actual data transmitting / receiving means for transmitting / receiving actual data by wireless communication according to the second wireless communication system. It is. According to the first invention, the time for performing connection establishment processing in the wireless communication according to the second wireless communication method can be used for the transfer time of the actual data, and the transfer capacity of the actual data can be sufficiently secured.

  The connection information in the first invention includes communication mode information indicating which communication mode of an infrastructure mode or an ad hoc mode is used in wireless communication according to the second wireless communication method, and the connection establishment means includes: The communication mode of the second wireless communication method may be set based on the communication mode information. Thereby, it is not necessary to fix the communication mode in advance, and the same in-vehicle communication device and roadside communication device can communicate in both the infrastructure mode and the ad hoc mode.

  In a first aspect of the present invention, in a road capable of reciprocal traffic, a plurality of the roadside communication devices are installed on both sides of the road, and the vehicle equipped with the in-vehicle communication device is equipped with the second wireless communication device. When the plurality of antennas used for the communication method are respectively installed on both sides of the vehicle, and the connection information transmission / reception means is the roadside communication device as the first communication node, Installation location information indicating where it is installed is included in the connection information and transmitted to the second communication node, and the first communication node and the second communication node are based on the installation location information. An antenna determining means for determining the antenna used for the second wireless communication method may be further provided. As a result, when the first communication node is a roadside communication device, it is possible to suppress a decrease in radio wave reception intensity due to the physical positional relationship of the antennas used in the second wireless communication method. It is possible to secure a sufficient transfer capacity.

  Further, the connection information transmitting / receiving means in the first invention, when the first communication node is the in-vehicle communication device, further includes traveling information included in the connection information to transmit to the second communication node, The antenna determining means may determine the antenna used for the second wireless communication system based on the travel information. As a result, when the first communication node is an in-vehicle communication device, it is possible to suppress a decrease in radio wave reception intensity due to the physical positional relationship of the antennas used in the second wireless communication method. It is possible to secure a sufficient transfer capacity.

  In the first invention, the first communication node and the second communication node periodically transmit and receive the radio wave reception strength of the wireless communication according to the first wireless communication method transmitted from the other party. In addition, parameter adjusting means for adjusting a parameter of wireless communication according to the first wireless communication method according to the reception strength may be further provided. As a result, the communication distance can be increased while keeping the data error rate below a certain level.

  In addition, the first invention includes an antenna direction adjusting unit in which the first communication node and the second communication node transmit and receive the traveling information to each other and adjust the direction of the antenna based on the traveling information. You may make it provide further. Thus, beam forming can be performed while following the communication partner, and the communication speed can be increased. In addition, it is possible to secure a sufficient transfer capacity for actual data.

  In the second invention, the roadside communication device and the in-vehicle communication device capable of communication by the first wireless communication method and the second wireless communication method having a shorter radio wave reach than the first wireless communication method are communication nodes. A communication method, wherein a first communication node broadcasts its presence by wireless communication according to the first wireless communication method, and a second communication node different from the first communication node A broadcast response step for responding to the broadcast by wireless communication according to the first wireless communication method, and the first communication node and the second communication node are connected to the wireless device according to the first wireless communication method. A connection information transmission / reception step for transmitting and receiving connection information according to the second wireless communication method to each other by communication; and the first communication node and A connection establishment step in which the second communication node performs a connection establishment process of the second wireless communication method based on the connection information by wireless communication according to the first wireless communication method; and the first communication The node and the second communication node execute an actual data transmission / reception step of transmitting / receiving actual data by wireless communication according to the second wireless communication method. According to the second invention, the time for performing the connection establishment process in the wireless communication according to the second wireless communication method can be used for the transfer time of the actual data, and the transfer capacity of the actual data can be sufficiently secured.

  According to a third aspect of the present invention, a roadside communication device and an in-vehicle communication device capable of communication by the first wireless communication method and the second wireless communication method having a shorter radio wave reach than the first wireless communication method are communication nodes. A communication program, wherein a first communication node broadcasts its presence by wireless communication according to the first wireless communication method, and a second communication node different from the first communication node A broadcast response step for responding to the broadcast by wireless communication according to the first wireless communication method, and the first communication node and the second communication node are connected to the wireless device according to the first wireless communication method. A connection information transmission / reception step for transmitting and receiving connection information according to the second wireless communication method to each other by communication; and the first communication node. A connection establishing step in which the second communication node and the second communication node perform connection establishment processing of the second wireless communication system based on the connection information by wireless communication according to the first wireless communication system; A communication program for executing the actual data transmission / reception step in which the communication node and the second communication node transmit / receive actual data by wireless communication according to the second wireless communication method. The communication system of the first invention can be obtained by installing the communication program of the third invention on a general-purpose computer.

  The present invention can provide a communication system and the like with improved convenience and performance.

Diagram showing an overview of a communication system Diagram showing configuration of in-vehicle communication device Diagram showing the configuration of the roadside communication device The flowchart which shows the flow of the process in the communication system which concerns on 1st Embodiment. The flowchart which shows the flow of a setting process of a 2nd wireless communication system The figure explaining the setting process of the 2nd wireless communication system in case the 1st communication node is a roadside communication apparatus. The figure explaining the setting process of the 2nd radio | wireless communication system in case the 1st communication node is a vehicle-mounted communication apparatus. The flowchart which shows the flow of a process in the communication system which concerns on 2nd Embodiment. The flowchart which shows the flow of the connection process of a 1st radio | wireless communication system. The flowchart which shows the flow of the adjustment process of a 1st wireless communication system Flow chart showing the flow of sensor data transmission / reception processing

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of a communication system. As shown in FIG. 1, in the communication system 1, an in-vehicle communication device 4 mounted on a vehicle 3 and a roadside communication device 5 installed beside a road serve as communication nodes. Here, the communication node is a general term for a wireless communication transmission side device and reception side device in the communication system 1.

  The communication system 1 further includes a cloud server 2 connected to the roadside communication device 5 via the network 6. The cloud server 2 may be connected to the in-vehicle communication device 4 via the network 6. The network 6 is the Internet, for example. The cloud server 2 is, for example, a server computer arranged in a data center, and may be realized by a single casing or may be realized by a plurality of casings.

  The in-vehicle communication device 4 and the roadside communication device 5 can communicate with each other by the first wireless communication method and the second wireless communication method that has a shorter radio wave reach than the first wireless communication method. The first wireless communication method is, for example, a wireless communication method using a 920 MHz band with a sightline radio wave arrival distance of about 1 km. Wireless communication systems using the 920 MHz band include LANs conforming to the IEEE 802.11ah standard, LPWA (Low Power Wide Area) -based LoRa (registered trademark), sigfox (registered trademark), etc. conforming to the IEEE 802.15.4k standard, etc. Is mentioned. The second wireless communication method is a wireless communication method using a 2.4 GHz band with a line-of-sight reaching distance of about 100 m, for example. Examples of the wireless communication system using the 2.4 GHz band include ZigBee (registered trademark) compliant with the IEEE 802.15.4 standard and WiFi (registered trademark) compliant with the IEEE 802.11 series standard.

  The in-vehicle communication device 4 performs wireless communication with other peripheral in-vehicle communication devices 4 and roadside communication devices 5. In the embodiment of the present invention, the in-vehicle communication device 4 acquires surrounding environment information by a sensor and transmits it to the other in-vehicle communication device 4 or the roadside communication device 5, or other in-vehicle communication device 4 or roadside communication. Environmental information is acquired from the device 5. The in-vehicle communication device 4 may upload environment information to the cloud server 2 via the network 6.

  The roadside communication device 5 performs wireless communication with the in-vehicle communication device 4 and other roadside communication devices 5 in the vicinity. In the embodiment of the present invention, the roadside communication device 5 acquires surrounding environment information by a sensor and transmits it to the in-vehicle communication device 4 and other roadside communication devices 5, or the in-vehicle communication device 4 and other roadside communication. Environmental information is acquired from the device 5. The roadside communication device 5 may upload environmental information to the cloud server 2 via the network 6.

  Environmental information includes, for example, ambient temperature, road surface temperature, humidity, fog level, atmospheric pressure, road surface frozen state, ambient image, ultraviolet light amount, CO2 amount, PM2.5 amount, precipitation amount, snowfall amount, whiteout state amount, traffic volume , Shelter installation information, closed road information, disaster information, tourism information, etc.

  In general, wireless communication between the in-vehicle communication device 4 and the roadside communication device 5 is called road-to-vehicle communication, wireless communication between the in-vehicle communication device 4 is called vehicle-to-vehicle communication, and wireless communication between the roadside communication devices 5 is called road-to-road communication. Hereinafter, wireless communication is a general term for road-to-vehicle communication, vehicle-to-vehicle communication, and road-to-road communication.

  The cloud server 2 includes a CPU (abbreviation of “Central Processing Unit”) as a control unit, a memory as a main storage unit, an HDD (abbreviation of “Hard Disk Drive”), a flash memory, a communication device, and the like as an auxiliary storage unit. Have. The auxiliary storage unit stores an OS (abbreviation of “Operating System”), application programs, data necessary for processing, and the like. The control unit reads the OS and application programs from the auxiliary storage unit, stores them in the main storage unit, controls other devices while executing access to the main storage unit, and executes predetermined processing.

  FIG. 2 is a diagram illustrating a configuration of the in-vehicle communication device. As shown in FIG. 2, the in-vehicle communication device 4 includes a control device 40 that controls each device, and a communication device group 7 that performs wireless communication by a plurality of wireless methods, and acquires a surrounding environment information. Connected to group 8.

  The control device 40 includes a CPU as a control unit, a memory as a main storage unit, an HDD and a flash memory as auxiliary storage units, and the like. The auxiliary storage unit stores an OS, application programs, data necessary for processing, and the like. The control unit reads the OS and application program from the auxiliary storage unit, stores them in the main storage unit, controls other devices while accessing the main storage unit, and executes processing to be described later.

  The control device 40 performs routing between the SDN control module 41 and the SDN communication module 42 that control the communication device group 7 and the like by the SDN (Software Defined Network) technology and the communication nodes by storage and transfer communication, and exchanges data asynchronously. A DTN (Delay, Disruption, Disconnection Tolerant Networking) module 43, a cloudlet module 44 that executes part or all of the processing of the cloud server 2, and a sensor database 45 that stores environment information acquired by the sensor. In addition, a CAN module 46 that communicates with an ECU (Electronic Control Unit) mounted on the vehicle 3 and the sensor group 8 via a CAN (Controller Area Network) is installed.

  The SDN technology is a technology for dynamically controlling the communication device group 7 by software, and is characterized by adopting an architecture in which functions of path control and data transfer are separated. Further, the SDN technology makes it possible to handle cross layer information in a network definition. For example, use the MAC address, IP address, and TCP / UDP port number for network definition, edit the route information directly from the user interface installed on the browser, or select the optimal network from the information stored in the external database. Definitions can be derived. In the embodiment of the present invention, the SDN control module 41 is a program for realizing functions such as path control, connection establishment, and communication guarantee, and the SDN communication module 42 is a program for realizing functions such as data transfer. is there.

  The DTN is a mechanism for storing data in a relay node in an environment where communication is impossible, and transferring data when communication is possible due to movement of the relay node or the like. Data transfer can be realized by DTN even in a poor communication environment. The DTN technology is operated as an overlay network and uses a UUID (Universally Unique Identifier), which is an identifier for uniquely identifying an object on software, as identification information. In the embodiment of the present invention, the DTN module 43 is a program for transmitting and receiving connection information of a wireless communication method.

  The cloudlet means a small server that is distributed and arranged at a position close to a terminal receiving a cloud service in a technology such as edge computing or fog computing. In the embodiment of the present invention, the cloudlet module 44 periodically samples data from the sensor group 8, receives data from other in-vehicle communication devices 4 and roadside communication devices 5, and stores them in the sensor database 45. This is a program for causing the control device 40 to function as service providing means for providing various services to the vehicle 3 based on the data in the sensor database 45. Examples of the various services include provision of road conditions and disaster information.

  The sensor database 45 stores information such as sensor type, time, transmission source identification number, location, sensor measurement value, and the like. The sensor database 45 is flexible enough to store even unknown sensor data, for example, using a technology that applies Plug and Play described in Japanese Patent Application Laid-Open No. 2015-170311. . By the sensor database 45, it is possible to uniformly manage when and who collected what data.

  The communication device group 7 is an aggregate of a plurality of communication devices corresponding to a plurality of wireless communication methods. As a wireless communication system, for example, a LAN conforming to the IEEE802.11ah standard using the 920 MHz band, an LPWA (Low Power Wide Area) -based LoRa (registered trademark) or sigfox (registered trademark) conforming to the IEEE802.15.4k standard. Trademark) ZigBee (registered trademark) compliant with IEEE 802.15.4 standard using 2.4 GHz band, WiFi (registered trademark) compliant with IEEE 802.11 series standard using 2.4 GHz band and 5 GHz band, satellite Lines, mobile phone lines (3G / LTE / 5G), and the like.

  In the embodiment of the present invention, the road-to-vehicle communication, the vehicle-to-vehicle communication, and the road-to-road communication are defined in a wireless communication system of a frequency band of 920 MHz band and 2.4 GHz band. In communication between the cloud server 2 and the in-vehicle communication device 4 or the roadside communication device 5, a satellite communication, a mobile phone line (3G / LTE / 5G), or a wired communication such as a LAN cable can be used.

  In the embodiment of the present invention, a cognitive radio technology may be used in order to dynamically switch a plurality of radio communication schemes for communication. The cognitive radio technology is a technology in which a terminal, a base station, or the like checks a surrounding radio wave condition and communicates by changing a radio communication method without making the user aware of the situation. In the embodiment of the present invention, in particular, a heterogeneous cognitive radio technology that senses and automatically switches a use communication environment of an existing available wireless communication method may be used.

  The sensor group 8 is a collection of sensors that acquire surrounding environmental information. Examples of the sensor include an infrared temperature sensor, a rainfall sensor, an atmospheric pressure sensor, a humidity sensor, an image sensor, a GPS sensor, and a road surface condition monitoring sensor.

  FIG. 3 is a diagram illustrating a configuration of the roadside communication device. As illustrated in FIG. 3, the roadside communication device 5 according to the embodiment of the present invention performs wireless communication using a plurality of wireless systems, a control device 40 that controls each device, a power supply unit 50 that supplies power to each device, and the like. The communication device group 7 and a sensor group 8 that acquires surrounding environmental information are configured.

  The control device 40 is the same as the control device 40 of the in-vehicle communication device 4 except that the CAN module 46 is not provided. The SDN control module 41, the SDN communication module 42, the DTN module 43, the cloudlet module 44, the sensor database 45, the communication device group 7, and the sensor group 8 are the same as the in-vehicle communication device 4.

  The power supply unit 50 includes a wind power generation device 51, a solar power generation device 52, a power control device 53, a battery 54, and the like, and functions as an independent power source that can supply power independently of a commercial power source.

  Next, the first embodiment will be described with reference to FIGS. FIG. 4 is a flowchart showing the flow of processing in the communication system according to the first embodiment. In the communication process shown in FIG. 4, the first communication node N1 and the second communication node N2 are different from each other, and the device (= in-vehicle communication device 4 or roadside communication device 5) that transmits the sensor data performs the first communication. The device (= in-vehicle communication device 4 or roadside communication device 5) that is the node N1 and receives sensor data is the second communication node N2.

  The first communication node N1 periodically samples data from each sensor and stores it in the sensor database 45 (step S1).

  Next, the first communication node N1 acquires sensor data from the sensor database 45 (step S2), and broadcasts its presence to other communication nodes in the vicinity by wireless communication according to the first wireless communication method. Perform (step S3). For example, the first communication node N1 broadcasts its own identification information.

  The second communication node N2 responds to the broadcast in step S3 by wireless communication according to the first wireless communication method (step S4). For example, the second communication node N2 transmits its own identification information to the first communication node N1 as a response to the broadcast.

  When there is no response from another communication node (No in step S5), the first communication node N1 caches the sensor data (step S6) and repeats the processing from step S3. When there is a response (Yes in Step S5), the first communication node N1 transmits connection information of the second wireless communication method by wireless communication according to the first wireless communication method (Step S7).

  The connection information of the second wireless communication method includes communication mode information indicating which communication mode of the infrastructure mode or the ad hoc mode is used in the wireless communication related to the second wireless communication method, and the SSID related to the communication mode, Encryption key etc. are included.

  The communication mode information may be a code indicating either the infrastructure mode or the ad hoc mode, or may be other information for determining either the infrastructure mode or the ad hoc mode. For example, the communication mode information may be road vehicle identification information indicating whether the first communication node N1 is the roadside communication device 5 or the in-vehicle communication device 4. In this case, the second communication node N2 determines the communication mode of the second wireless communication method as the infrastructure mode if the road-vehicle identification information indicates the road-side communication device 5, and the road-vehicle identification information is in-vehicle. If the communication device 4 is indicated, the ad hoc mode is determined. Similarly, the first communication node N1 can determine the communication mode of the second wireless communication method.

  The second communication node N2 receives connection information of the second wireless communication method by wireless communication according to the first wireless communication method (step S8), and performs setting processing of the second wireless communication method (step S8). S9).

  FIG. 5 is a flowchart showing a flow of setting processing of the second wireless communication method. As shown in FIG. 5, the second communication node N2 sets the communication mode of the second wireless communication system based on the communication mode information received in step S8 (step S21). If the communication mode information is information indicating the infrastructure mode, the second communication node N2 may set the communication mode of the second wireless communication method to the infrastructure mode and the communication mode information may be information indicating the ad hoc mode. For example, the communication mode of the second wireless communication method is set to the ad hoc mode.

  Next, the second communication node N2 confirms whether the first communication node N1 is the roadside communication device 5 or the in-vehicle communication device 4 (step S22). For example, when road and vehicle identification information is used as the communication mode information, the second communication node N2 can perform the determination process of step S22 using the road and vehicle identification information.

  When the first communication node N1 is the roadside communication device 5 (“roadside communication device” in step S22), the second communication node N2 proceeds to step S23. On the other hand, when the first communication node N1 is the in-vehicle communication device 4 (“in-vehicle communication device” in step S22), the second communication node N2 proceeds to step S24.

  FIG. 6 is a diagram for explaining the setting process of the second wireless communication method when the first communication node is a roadside communication device. As shown in FIG. 6, in the present embodiment, a plurality of roadside communication devices 5A and 5B are installed on both sides of the road on a road that can be reciprocated. In the example shown in FIG. 6, the roadside communication device 5 </ b> A is installed on the road side on the left side in the forward direction of the vehicle 3, and the roadside communication device 5 </ b> B is installed on the roadside on the right side in the forward direction of the vehicle 3. In the vehicle 3 on which the in-vehicle communication device 4 is mounted, an antenna 71 used for the first wireless communication method is installed on the top of the vehicle 3. In the example shown in FIG. 6, the antenna 71 is installed on the roof of the vehicle 3. Antennas 72 a and 72 b used for the second wireless communication method are respectively installed on both sides of the vehicle 3. In the example shown in FIG. 6, the antenna 72 a is installed on the door mirror on the left side in the forward direction of the vehicle 3, and the antenna 72 b is installed on the door mirror on the right side in the forward direction of the vehicle 3. By installing the antennas 72a and 72b on the left and right door mirrors and selecting an appropriate antenna in the processing of step S23 or S24 described later, the physical distance between the antennas performing wireless communication can be reduced.

  In the example shown in FIG. 6, the roadside communication devices 5A and 5B are devices on the side that transmits sensor data, that is, the first communication node N1, and the vehicle-mounted communication device 4 mounted on the vehicle 3 receives the sensor data. Device, that is, the second communication node N2. When the current position of the vehicle 3 is P1, the in-vehicle communication device 4 performs road-to-vehicle communication with the roadside communication device 5B. When the current position of the vehicle 3 is P2, the in-vehicle communication device 4 is between the roadside communication device 5A and the roadside vehicle. Communicate.

  Before the vehicle 3 approaches P1, the roadside communication device 5B that is the first communication node N1 includes, in step S7, installation location information that indicates which side of the roadside it is installed in the connection information. To the second communication node N2. In the example illustrated in FIG. 6, the installation location information of the roadside communication device 5 </ b> B indicates the roadside on the right side in the forward direction of the vehicle 3. On the other hand, the in-vehicle communication device 4 that is the second communication node N2 determines an antenna to be used for the second wireless communication method based on the installation location information of the first communication node N1 in step S23. In the example illustrated in FIG. 6, the in-vehicle communication device 4 that is the second communication node N <b> 2 determines the antenna 72 b close to the roadside on the right side in the forward direction of the vehicle 3 as an antenna used for the second wireless communication method.

  In addition, before the vehicle 3 leaves P1 and approaches P2, the roadside communication device 5A that is the first communication node N1 indicates in which position the roadside communication device 5A is installed on either side of the road on both sides in step S7. The information is included in the connection information and transmitted to the second communication node N2. In the example shown in FIG. 6, the installation location information of the roadside communication device 5 </ b> A indicates the roadside on the left side in the forward direction of the vehicle 3. On the other hand, the in-vehicle communication device 4 that is the second communication node N2 determines an antenna to be used for the second wireless communication method based on the installation location information of the first communication node N1 in step S23. In the example illustrated in FIG. 6, the in-vehicle communication device 4 that is the second communication node N <b> 2 determines the antenna 72 a close to the roadside on the left side in the forward direction of the vehicle 3 as the antenna used for the second wireless communication method.

  FIG. 7 is a diagram illustrating the setting process of the second wireless communication method when the first communication node is an in-vehicle communication device. As shown in FIG. 7, in the present embodiment, a plurality of vehicles 3A, 3B on which the in-vehicle communication devices 4A, 4B are mounted travel on a road that allows reciprocal traffic. In the example shown in FIG. 7, the vehicle 3A on which the in-vehicle communication device 4A is mounted travels from the left side to the right side in the drawing, and the vehicle 3B on which the in-vehicle communication device 4B is mounted runs from the right side to the left side in the drawing. Similar to the example shown in FIG. 6, in the vehicles 3A and 3B, the antenna 71 is installed on the roof of the vehicles 3A and 3B, the antenna 72a is installed on the door mirror on the left side in the forward direction of the vehicles 3A and 3B, and the antenna 72b is installed in the vehicle. It is installed on the door mirror on the right side in the forward direction of 3A and 3B.

  In the example shown in FIG. 7, the in-vehicle communication device 4A is a device that transmits sensor data, that is, the first communication node N1, and the in-vehicle communication device 4B is a device that receives sensor data, that is, the second communication. Node N2. And vehicle-mounted communication apparatus 4A, 4B mutually communicates between vehicles.

  Before the vehicles 3A and 3B approach each other, the in-vehicle communication device 4A, which is the first communication node N1, includes the travel information including its current position and travel direction in the connection information in the second communication node in step S7. Send to N2. In the example illustrated in FIG. 7, the traveling information of the in-vehicle communication device 4A indicates that the vehicle 3 is traveling from the left side to the right side in the drawing. On the other hand, the in-vehicle communication device 4B that is the second communication node N2 determines an antenna to be used for the second wireless communication method based on the travel information of the first communication node N1 in step S23. In the example illustrated in FIG. 7, the in-vehicle communication device 4 </ b> B that is the second communication node N <b> 2 determines the antenna 72 b close to the vehicle 3 </ b> A as an antenna used for the second wireless communication method. Similarly, the in-vehicle communication device 4A which is the first communication node N1 can determine the antenna used for the second wireless communication method.

  Returning to the description of FIG. The first communication node N1 and the second communication node N2 perform connection establishment processing of the second wireless communication method with each other by wireless communication according to the first wireless communication method (step S10). For example, the first communication node N1 and the second communication node N2 are authenticated by the second communication node N2 that exchanges authentication information with each other through wireless communication according to the first wireless communication method. An association request for making a connection request to the first communication node N1, an association response for making a connection permission response from the first communication node N1 to the second communication node N2, and a secret key An authentication procedure (4-way handshake) for exchanging is executed to establish a connection by the second wireless communication method.

  Next, the first communication node N1 confirms whether or not communication with the second communication node N2 is possible through wireless communication according to the second wireless communication method (step S11). For example, the first communication node N1 confirms continuity by ping to the second communication node N2 by wireless communication according to the second wireless communication method, and the second communication node N2 exists in the communicable range. Confirm whether or not to do.

  When communication with the second communication node N2 is not possible (No at Step S11), the first communication node N1 repeats the process at Step S11. When communication with the second communication node N2 is possible (Yes in step S11), the first communication node N1 transmits sensor data to the second communication node N2 by wireless communication according to the second wireless communication method. (Step S12), the second communication node N2 receives sensor data from the first communication node N1 by wireless communication according to the second wireless communication method (Step S13). That is, the first communication node N1 and the second communication node N2 transmit and receive actual data to and from each other through wireless communication according to the second wireless communication method.

  As described above, the communication system 1 according to the first embodiment has improved convenience and performance. As one of the measures for improving the performance, the first communication node N1 and the second communication node N2 perform the connection establishment process of the second wireless communication method with each other by the wireless communication according to the first wireless communication method. The time for performing the connection establishment process in the wireless communication according to the second wireless communication method can be used as the actual data transfer time, and the actual data transfer capacity can be sufficiently secured.

  Further, as one of the measures for improving the convenience, when the connection establishment process of the second wireless communication method is performed before transmitting / receiving actual data, the first communication node N1 is in either the infrastructure mode or the ad hoc mode. Since communication mode information indicating whether to use the communication mode is transmitted and the second communication node N2 sets the communication mode of the second wireless communication method based on the communication mode information, the communication mode is fixed in advance. The same in-vehicle communication device 4 and roadside communication device 5 can communicate in both modes. That is, when the device on the side that receives the actual data is the in-vehicle communication device 4, if the communication partner is the road-side communication device 5, road-vehicle communication is performed in the infrastructure mode, and if the communication partner is the in-vehicle communication device 4, It is possible to perform vehicle-to-vehicle communication in the ad hoc mode. Similarly, when the device that receives the actual data is the roadside communication device 5, if the communication partner is the roadside communication device 5, the road communication is performed in the infrastructure mode, and the communication partner is the in-vehicle communication device 4. It is possible to perform road and vehicle communication in the ad hoc mode.

  Further, as one of the measures for improving the performance, when the first communication node N1 is the roadside communication device 5, the first communication node N1 is installed on either side of the road on both sides. The information is included in the connection information and transmitted to the second communication node N2, and the second communication node N2 uses the antenna used for the second wireless communication system based on the installation location information of the first communication node N1. To decide. When the first communication node N1 is the in-vehicle communication device 4, the first communication node N1 includes the travel information in the connection information and transmits the connection information to the second communication node N2, and the second communication node N2 Based on the travel information of the first communication node N1, the antenna used for the second wireless communication method is determined. As a result, it is possible to suppress a decrease in radio wave reception intensity due to the physical positional relationship of the antennas used in the second wireless communication method, and to ensure a sufficient transfer capacity of actual data.

  Next, a second embodiment will be described with reference to FIGS. In the processes shown in FIGS. 8 to 11, the first communication node N1 and the second communication node N2 are different from each other, and the device (= in-vehicle communication device 4 or roadside communication device 5) that transmits the sensor data is the first. The communication node N1 and the device (= in-vehicle communication device 4 or roadside communication device 5) that receives the sensor data are the second communication node N2.

  In the second embodiment, adjustment processing of each wireless communication is executed for the purpose of increasing the communication distance in the first wireless communication method and increasing the communication speed in the second wireless communication method. This makes it possible to achieve both maximization of radio communication reception sensitivity and improvement of communication throughput both when the communication nodes are at a long distance and at a short distance when they are passing each other.

  In the following description, the communication standard for the first wireless communication system is LoRa (registered trademark), and the communication standard for the second wireless communication system is 802.11ac Wave2. The communication mode of wireless communication according to the second wireless communication method will be described as an infrastructure mode. LoRa (registered trademark) is one of LPWA (Low Power, Wide Area), and can cover a wide area with low power consumption. 802.11ac Wave2 is a technology that can transmit a large amount of data at once by bundling multiple frequencies (= channel bonding), and a technology that speeds up communication using multiple antennas and transmits them simultaneously to multiple users (MU). -MIMO). With MU-MIMO, it is possible to transmit a plurality of signal waves by beam forming while shifting the phase so that radio wave interference does not occur.

  FIG. 8 is a flowchart showing the flow of processing in the communication system according to the second embodiment. The first communication node N1 executes sensor data acquisition processing (step S31). This process is the same as steps S1 and S2 in the first embodiment.

  Next, the first communication node N1 and the second communication node N2 execute connection processing of the first wireless communication method (step S32).

  FIG. 9 is a flowchart showing a flow of connection processing of the first wireless communication method. As shown in FIG. 9, the first communication node N1 performs carrier sense (step S41). Carrier sense is to detect whether there is another carrier (= carrier wave) by receiving the same frequency before transmitting itself.

  If there is a carrier (Yes in step S42), the first communication node N1 repeats from step S41 in order to transmit again after a predetermined time has elapsed. Alternatively, if the other received carrier is a beacon request, the first communication node N1 may execute processing described later as the receiving side, that is, the second communication node N2.

  When there is no carrier (No in step S42), the first communication node N1 periodically broadcasts a beacon request indicating its presence (step S43).

  The second communication node N2 determines whether or not a beacon request has been received (step S51). The second communication node N2 waits if no beacon request has been received (No in step S51), and transmits a beacon response to the first communication node N1 if received (Yes in step S51) (step S51). S52). When the first communication node N1 also acquires sensor data, the capacity of the sensor data stored by itself is included in the beacon response.

  The first communication node N1 determines whether or not a beacon response has been received (step S44). If the first communication node N1 has not received a beacon response (No in step S44), the process repeats from step S43, and if received (Yes in step S44), the process proceeds to step S45.

  In step S45, the first communication node N1 sets its own operation mode in the second wireless communication system to “access point” (step S45). The operation mode is a role of each communication node in the infrastructure mode, and has two roles of “access point” and “station”. In the infrastructure mode, each station goes to connect to the access point.

  Next, the first communication node N1 transmits an operation mode designation message to the partner second communication node N2 (step S46). The operation mode designation message includes the capacity of sensor data stored by itself in addition to an instruction for setting the operation mode of the second communication node N2 to “station”.

  The second communication node N2 determines whether or not an operation mode designation message has been received (step S53). If the first communication node N1 has not received the operation mode designation message (No in step S53), the first communication node N1 repeats from step S52, and if received (Yes in step S53), the first communication node N1 sets its operation mode to “station”. Set (step S54).

  Next, the second communication node N2 calculates the estimated communication time by the second wireless communication method for transmitting and receiving sensor data based on the sensor data capacity of the partner and the partner (step S55).

  Returning to the description of FIG. The first communication node N1 and the second communication node N2 execute connection preparation processing for the second wireless communication method (step S33). This process is the same as steps S7 to S9 in the first embodiment.

  In the first embodiment, the antenna used for the second wireless communication method is installed on each of the left and right door mirrors of the vehicle 3, and one antenna is selected from the two antennas in step S9. Is not limited to this. For example, antennas may be installed at four locations of the left and right door mirrors in front of the vehicle 3 and the rear roof at the rear, and one of the four antennas may be selected in step S9. In this case, the first communication node N1 and the second communication node N2 select one of the two front antennas while the first communication node N1 and the second communication node N2 are close to each other. After passing, select one of the two rear antennas.

  Next, the first communication node N1 and the second communication node N2 execute adjustment processing for the first wireless communication method (step S34). In wireless communication, there is a trade-off relationship between communication speed and communication distance, and LoRa (registered trademark) of the first wireless communication system adjusts the diffusion coefficient d, which is a set value, so that the communication speed and the communication distance can be adjusted. Balanced. When the diffusion coefficient d is large, the S / N ratio becomes high and the communication distance becomes long, but the data transfer rate decreases. Conversely, if the diffusion coefficient d is small, the S / N ratio is low and the communication distance is shortened, but the data transfer rate is increased. Since the S / N ratio and the reception intensity RSSI are correlated, the spreading coefficient d and the reception intensity RSSI are also correlated. Therefore, the first communication node and the second communication node are changed to the first wireless communication method transmitted from the other party in response to a change in noise disturbance due to the influence of trees in a mountainous area or a building in an urban area. The reception error RSSI of the radio communication radio wave is periodically transmitted and received, and the data error rate is kept constant by adjusting the diffusion coefficient d that is a parameter of the radio communication according to the first radio communication method according to the reception intensity RSSI. Can be kept below.

  FIG. 10 is a flowchart showing a flow of adjustment processing of the first wireless communication method. As shown in FIG. 10, the first communication node N1 and the second communication node N2 initialize variables (step S61, step S71). The variables are the received intensity RSSI and the spreading coefficient d. The initial value of the received intensity RSSI is an actually measured value at that time, and the initial value of the spreading coefficient d is the maximum value 12 of 7-12. In any case, there are variables on the transmission side (= first communication node N1) and reception side (= second communication node N2) of the sensor data, the reception intensity S_RSSI on the transmission side, the spreading coefficient S_d on the transmission side, and the reception side There are four variables: reception intensity R_RSSI and reception-side spreading coefficient R_d. The reception strength S_RSSI on the transmission side indicates the reception strength of the radio wave when the transmission side receives the radio wave transmitted from the reception side by the first wireless communication method, and the reception strength R_RSSI on the reception side is the first wireless communication method. Indicates the radio wave reception intensity when the reception side receives the radio wave transmitted from the transmission side.

  Next, the first communication node N1 and the second communication node N2 measure latitude, longitude, altitude, traveling direction, and vehicle speed as travel information (step S62, step S72). The travel information is used to confirm each other's current position.

  Next, the first communication node N1 transmits a position data request to the second communication node N2 (step S63). The position data request includes the current time, the travel information measured in step S62, the reception strength S_RSSI on the transmission side, and the spreading coefficient S_d on the transmission side.

  Next, the second communication node N2 determines whether or not a position data request has been received (step S73). If the second communication node N2 has not received the position data request (No in step S73), the second communication node N2 waits. If received (Yes in step S73), the second communication node N2 proceeds to step S74.

  In step S74, the second communication node N2 adjusts the spreading coefficient R_d on the reception side based on the reception strength S_RSSI on the transmission side. Specifically, assuming that the repetition index of the process is i (i = 1, 2,...), If S_RSSI (i) −S_RSSI (i−1) <0, R_d (i) = R_d If (i−1) +1 and S_RSSI (i) −S_RSSI (i−1)> 0, then R_d (i) = R_d (i−1) −1 and S_RSSI (i) −S_RSSI (i−1) ) = 0, R_d (i) = R_d (i−1).

  Here, since communication is not possible unless the spreading coefficient d of the first communication node N and the second communication node N2 is the same, if the transmission side spreading coefficient S_d is changed, the second communication node N2 Without performing the adjustment process described above, the spreading coefficient R_d on the reception side is changed to the value of the spreading coefficient S_d on the transmission side.

  Next, the second communication node N2 transmits a position data response to the first communication node N1 (step S75). The position data response includes the current time, the travel information measured in step S72, the reception strength R_RSSI on the reception side, and the diffusion coefficient R_d on the reception side. As described above, since communication is not possible unless the spread coefficient d of the first communication node N1 and the second communication node N2 is the same, even if the spread coefficient R_d is adjusted in step S75, the transmission side The position data response is transmitted using the same value as the spreading coefficient S_d, and after transmission, the setting value of the spreading coefficient d is changed to an adjusted value.

  Next, the first communication node N1 determines whether or not a position data response has been received (step S64). If the first communication node N1 has not received a position data response (No in step S64), the first communication node N1 waits. If received (Yes in step S64), the first communication node N1 proceeds to step S65.

  In step S65, the first communication node N1 adjusts the transmission-side spreading factor S_d based on the reception-side reception strength R_RSSI. Specifically, if R_RSSI (i) −R_RSSI (i−1) <0, S_d (i) = S_d (i−1) +1 and R_RSSI (i) −R_RSSI (i−1)> 0. If there is, S_d (i) = S_d (i-1) -1; if R_RSSI (i) -R_RSSI (i-1) = 0, then S_d (i) = S_d (i-1).

  Here, as described above, since communication is not possible unless the spreading coefficient d of the first communication node N1 and the second communication node N2 is the same, if the spreading coefficient R_d on the receiving side is changed, the first communication The node N1 does not perform the adjustment process described above, and changes the transmission-side spreading factor S_d to the value of the receiving-side spreading factor R_d.

  Next, the first communication node N1 and the second communication node N2 confirm whether or not the reception intensity of the second wireless communication method is equal to or higher than a threshold (step S66, step S76). If it is less than the threshold value (No in step S66, No in step S76), the first communication node N1 and the second communication node N2 repeat from steps S62 and S72, respectively, and if they are equal to or greater than the threshold value (Yes in step S66, step The processing is terminated.

  Returning to the description of FIG. The first communication node N1 and the second communication node N2 perform connection establishment processing of the second wireless communication method by wireless communication according to the first wireless communication method, based on the connection information transmitted and received in step S32. Execute (Step S35). This process is the same as step S10 in the first embodiment, but the connection procedure may be further simplified.

  Next, the first communication node N1 and the second communication node N2 perform transmission / reception of sensor data which is actual data by wireless communication according to the second wireless communication method (step S36). In 802.11ac Wave 2 of the second wireless communication system, radio waves can be transmitted and received in a specific direction by beam forming. Therefore, during the transmission / reception of sensor data, the first communication node N1 and the second communication node N2 regularly transmit / receive traveling information to / from each other, and adjust the direction of the antenna according to the traveling information. As a result, the communication speed can be increased.

  FIG. 11 is a flowchart showing a flow of sensor data transmission / reception processing. As shown in FIG. 11, the first communication node N1 and the second communication node N2 measure latitude, longitude, altitude, traveling direction, and vehicle speed as travel information (steps S81 and S91). The travel information is used to confirm each other's current position.

  Next, the first communication node N1 transmits the transmission side data to the second communication node N2 (step S82). The transmission side data includes the current time, travel information on the transmission side measured in step S81, reception intensity S_RSSI on the transmission side, and sensor data on the transmission side.

  Next, the second communication node N2 determines whether or not the transmission side data has been received (step S92). If the second communication node N2 has not received the transmission-side data even after a lapse of a certain period of time (No in step S92), the second communication node N2 ends the process, and if received (Yes in step S92), the process proceeds to step S93.

  In step S93, the second communication node N2 adjusts its antenna direction based on the other party's travel information and its own travel information measured in step S91. Since the travel information includes latitude, longitude, traveling direction, and vehicle speed, the second communication node N2 estimates the travel position after a predetermined time, and the current position of each other and the travel position after the predetermined time. Based on this, it is possible to adjust its own antenna direction.

  Next, the second communication node N2 transmits the reception side data to the first communication node N1 (step S94). The reception side data includes the current time, the reception side travel information measured in step S91, the reception side reception intensity R_RSSI, and the reception side sensor data.

  Next, the first communication node N1 determines whether or not receiving side data has been received (step S83). If the first communication node N1 has not received the receiving side data even after a certain period of time (No in step S83), the process ends. If received (Yes in step S83), the first communication node N1 proceeds to step S84.

  In step S84, the first communication node N1 adjusts its antenna direction based on the other party's travel information and its own travel information measured in step S81. Since the travel information includes the latitude, longitude, traveling direction, and vehicle speed, the first communication node N1 estimates the travel position after a predetermined time and determines itself based on the travel position after the predetermined time. It is also possible to adjust the antenna direction.

  The process of FIG. 11 ends when the transmission / reception of the sensor data is completed, or when the reception strength RSSI of the second wireless communication method becomes less than the threshold value and wireless communication by the second wireless communication method cannot be performed.

  As described above, the performance of the communication system 1 in the second embodiment is further improved. As one of the measures for improving the performance, the first communication node N1 and the second communication node N2 periodically set the radio wave reception strength RSSI of the wireless communication according to the first wireless communication method transmitted from the other party. Since the spread coefficient d, which is a parameter of wireless communication according to the first wireless communication method, is adjusted according to the reception strength RSSI, the communication distance can be increased while keeping the data error rate below a certain level. .

  Further, as one of the measures for improving the performance, the first communication node N1 and the second communication node N2 regularly transmit / receive traveling information to each other and adjust the direction of the antenna according to the traveling information. Beamforming can be performed while following the other party, and the communication speed can be increased. In addition, it is possible to secure a sufficient transfer capacity for actual data.

  The preferred embodiments of the communication system and the like according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these naturally belong to the technical scope of the present invention. Understood.

DESCRIPTION OF SYMBOLS 1 ......... Communication system 2 ......... Cloud server 3, 3A, 3B ......... Vehicle 4, 4A, 4B ......... In-vehicle communication device 5, 5A, 5B ......... Roadside communication device 6 ......... Network 71 ... ... Antennas used for the first wireless communication system 72a, 72b ... Antennas used for the second wireless communication system

Claims (8)

A communication system in which a roadside communication device and an in-vehicle communication device capable of communication by a first wireless communication method and a second wireless communication method having a shorter radio wave reach than the first wireless communication method are communication nodes,
Broadcast means for broadcasting the presence of the first communication node by wireless communication according to the first wireless communication method;
Broadcast response means for responding to the broadcast by a second communication node different from the first communication node by wireless communication according to the first wireless communication method;
Connection information transmission / reception means for the first communication node and the second communication node to transmit / receive connection information according to the second wireless communication method to each other by wireless communication according to the first wireless communication method;
Connection establishment means for causing the first communication node and the second communication node to perform connection establishment processing of the second wireless communication system based on the connection information by wireless communication according to the first wireless communication system When,
Actual data transmitting and receiving means for transmitting and receiving actual data by wireless communication according to the second wireless communication method by the first communication node and the second communication node;
A communication system comprising: The connection information includes communication mode information indicating which communication mode of an infrastructure mode or an ad hoc mode is used in wireless communication according to the second wireless communication method,
The communication system according to claim 1, wherein the connection establishment unit sets a communication mode of the second wireless communication method based on the communication mode information. In a road that can be reciprocated, a plurality of the roadside communication devices are installed on both sides of the road,
In the vehicle on which the in-vehicle communication device is mounted, a plurality of antennas used for the second wireless communication method are respectively installed on both sides of the vehicle,
In the case where the first communication node is the roadside communication device, the connection information transmission / reception means further includes installation location information indicating whether the first communication node is installed on either side of the road in the connection information. To the two communication nodes,
The first communication node and the second communication node further include antenna determining means for determining the antenna used for the second wireless communication system based on the installation location information. The communication system according to claim 1 or 2. When the first communication node is the in-vehicle communication device, the connection information transmission / reception means further includes travel information in the connection information and transmits the connection information to the second communication node,
The communication system according to claim 3, wherein the antenna determination unit determines the antenna to be used for the second wireless communication system based on the travel information. The first communication node and the second communication node periodically transmit and receive radio wave reception intensity of the first radio communication method transmitted from the other party, and according to the reception intensity Parameter adjusting means for adjusting parameters of wireless communication according to the first wireless communication system;
The communication system according to any one of claims 1 to 3, further comprising: Antenna direction adjusting means for the first communication node and the second communication node to transmit and receive the travel information to each other and adjust the direction of the antenna based on the travel information;
The communication system according to claim 4, further comprising: A communication method in which a roadside communication device and an in-vehicle communication device capable of communication by a first wireless communication method and a second wireless communication method having a shorter radio wave reach than the first wireless communication method are communication nodes,
A broadcast step in which the first communication node broadcasts its presence by wireless communication according to the first wireless communication method;
A broadcast response step in which a second communication node different from the first communication node responds to the broadcast by wireless communication according to the first wireless communication method;
A connection information transmission / reception step in which the first communication node and the second communication node mutually transmit / receive connection information according to the second wireless communication method by wireless communication according to the first wireless communication method;
A connection establishment step in which the first communication node and the second communication node perform a connection establishment process of the second wireless communication method based on the connection information by wireless communication according to the first wireless communication method. When,
An actual data transmission / reception step in which the first communication node and the second communication node transmit / receive actual data by wireless communication according to the second wireless communication method;
The communication method characterized by performing. A communication program in which a roadside communication device and an in-vehicle communication device capable of communication by a first wireless communication method and a second wireless communication method having a shorter radio wave reach than the first wireless communication method are communication nodes,
A broadcast step in which the first communication node broadcasts its presence by wireless communication according to the first wireless communication method;
A broadcast response step in which a second communication node different from the first communication node responds to the broadcast by wireless communication according to the first wireless communication method;
A connection information transmission / reception step in which the first communication node and the second communication node mutually transmit and receive connection information according to the second wireless communication method by wireless communication according to the first wireless communication method;
A connection establishment step in which the first communication node and the second communication node perform connection establishment processing of the second wireless communication scheme based on the connection information by wireless communication according to the first wireless communication scheme. When,
An actual data transmission / reception step in which the first communication node and the second communication node transmit / receive actual data by wireless communication according to the second wireless communication method;
Communication program for executing.

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