JP6904782B2 - Wireless communication system for vehicles - Google Patents

Description

The present invention relates to a wireless communication system for vehicles.

For example, by connecting various devices on a vehicle via a mesh-like network by wire or wireless, it is possible to communicate with each other by using various routes as needed. Further, when wireless communication is used, the structure of the wire harness can be simplified by the amount of the route, and the burden of the wire harness wiring work can be reduced.

Further, when a mesh network is configured, various routes can be selectively used between a certain source node to another destination node to secure a communication route. Therefore, even if a route that cannot be used due to a failure or the like occurs, it is possible to switch to another route and continuously connect. For example, if dynamic routing is used as shown in Patent Document 1, the route used for communication can be changed each time on a mesh-like network, so that it is affected by a failure or the like. It becomes difficult.

Further, in Patent Document 1, when a mobile communication system is configured, a wide area base station that covers a relatively wide area (macrocell) and a narrow area that covers a relatively narrow area (microcell). Using a base station, terminals at various positions form areas that can be used for wireless communication. Further, in Patent Document 1, when wireless communication is performed using a microcell and it is confirmed that the communication delay has increased, the wireless communication between the terminal and the base station is switched to the macrocell to reduce the communication delay. Is shown.

Further, Patent Document 2 shows a technique for relaying a packet received by each terminal on the receiving side in a multi-hop wireless communication network including a plurality of wireless communication terminals. Specifically, the source terminal generates and transmits a packet including the destination position information and the source position information. Each terminal on the receiving side calculates the transmission distance between the position of the wireless communication terminal of the source of the received packet and the position of the destination, and the relay distance between its own position and the position of the destination. Then, when the transmission distance exceeds the relay distance, the packet is relayed.

Further, Patent Document 3 shows a technique for quickly transmitting data to a target node in a communication system composed of a plurality of nodes.

Japanese Unexamined Patent Publication No. 2010-147748 Japanese Unexamined Patent Publication No. 2009-33516 Japanese Unexamined Patent Publication No. 2014-225859

For example, a case where a large number of wireless communication terminals having a relatively narrow communicable range are arranged in various positions in a dispersed state and a mesh-like wireless communication network is simply configured by using these wireless communication terminals. Suppose. In this case, when data is transmitted from the wireless communication terminal of one source node to the wireless communication terminal of another destination node, the data is transmitted while communicating sequentially or in parallel between various terminals. It is necessary to perform communication processing to search for a route that can be used for communication from the source to the destination. Further, even after the route that can be used for communication is determined, this data passes through a large number of relay points before the data arrives at the destination from the source. Therefore, the traffic passing over this wireless communication network increases. In addition, as the number of data relays between the source and the destination increases, the communication delay time also increases.

When the technique of Patent Document 2 is adopted, each terminal on the receiving side calculates the transmission distance between the source and the destination and the relay distance between its own position and the position of the destination, and uses these distances. Since relay control is performed based on this, it is not necessary for each terminal to store route information. In addition, it is possible to avoid lengthening the communication path. However, for example, in a situation where a large number of terminals are arranged in a narrow space, the number of relays from the source terminal to the destination terminal increases, so that the communication delay time inevitably increases. ..

Therefore, for example, as shown in Patent Document 1, it is conceivable to switch the range of wireless communication of each terminal from a narrow range to a wide range to reduce the number of communications associated with route search and the number of relays of data to be transmitted. Be done. As a result, the delay time of communication can be reduced and the traffic is also reduced. However, in order to adopt the technique of Patent Document 1, all wireless communication terminals are provided with both narrow-range wireless communication and wide-area wireless communication functions, and further, in order to detect a communication delay time. Control is required to measure the reception timing and switch the communication range based on the result. Therefore, it is inevitable that the cost of the entire system will increase significantly. In addition, a device for managing the operation of the entire system is also required.

Further, in the case of a wireless communication system used on a vehicle, a large number of wireless communication terminals used for controlling various types of electrical components may be arranged in a limited narrow space on the vehicle. .. Furthermore, consideration must be given in advance so that the radio waves of the wireless communication performed on the own vehicle do not affect the wireless communication inside the other vehicle or the wireless communication outside the vehicle. Therefore, it is desirable to suppress the output power of the radio waves transmitted by each wireless communication terminal on the vehicle and perform narrow-range wireless communication in a very narrow range. However, when the communicable range of each wireless communication terminal is limited to a very narrow range, an increase in traffic and an increase in communication delay time become major problems as described above. Furthermore, it is necessary to suppress the increase in the cost of the communication system.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wireless communication system for vehicles capable of suppressing an increase in cost and avoiding an increase in communication delay time and an increase in traffic. To provide.

In order to achieve the above-mentioned object, the vehicle wireless communication system according to the present invention is characterized by the following (1) to (4).
(1) A plurality of wireless communication terminals having a narrow band wireless communication function and a wide band wireless communication function, which have different frequency bands to be used, are provided.
As the range of wireless communication, an entire area and a plurality of cell areas smaller than the total area and included in the total area are formed.
Each said cell area contains at least one said wireless communication terminal.
Each wireless communication terminal, as the range of the wireless communication, selecting said whole region, one of the cell region to which it belongs,
When each wireless communication terminal selects the entire area for wireless communication, the narrowband wireless communication function is used.
When each wireless communication terminal selects the cell area to which it belongs and performs wireless communication, the wideband wireless communication function is used.
When the respective radio communication terminal transmits data, status for the destination of the data is the entire region preferentially selected in case a predetermined condition is satisfied, the row physician wireless communication by the narrow-band radio communication function ,
Each of the wireless communication terminals has a function of acquiring information regarding the position or distance of each of the other wireless communication terminals.
When each wireless communication terminal transmits data,
If the destination terminal of the data does not exist in the same cell area as the own terminal, or if the distance to the destination terminal is greater than or equal to a predetermined value, the entire area is selected and wireless communication is performed by the narrow band wireless communication function. To start,
When the destination terminal of the data exists in the same cell area as the own terminal, or when the distance to the destination terminal is less than the predetermined value, the cell area to which the data destination belongs is selected and the wideband wireless communication function is performed. To start wireless communication,
A wireless communication system for vehicles characterized by this.

( 2 ) A plurality of wireless communication terminals having a narrow band wireless communication function and a wide band wireless communication function, which have different frequency bands to be used, are provided.
Each wireless communication terminal selects either an entire area or a plurality of cell areas smaller than the overall area and included in the entire area as the range of wireless communication.
When each wireless communication terminal selects the entire area for wireless communication, the narrowband wireless communication function is used.
When each wireless communication terminal selects the cell area for wireless communication, the wideband wireless communication function is used.
When each of the wireless communication terminals transmits data, if the situation regarding the destination of the data satisfies a predetermined condition, the entire area is preferentially selected, and wireless communication is performed by the narrow band wireless communication function.
Priorities are set for each of the wireless communication terminals.
When the wireless communication terminal other than the destination receives the wireless signal transmitted by the narrow band wireless communication function, the wireless communication terminal having a high priority receives the data of the received wireless signal to the destination wireless communication. Sending to the terminal by the wideband wireless communication function or the narrowband wireless communication function.
Car dual wireless communication system, characterized in that.

( 3 ) A plurality of wireless communication terminals having a narrow band wireless communication function and a wide band wireless communication function, which have different frequency bands to be used, are provided.
Each wireless communication terminal selects either an entire area or a plurality of cell areas smaller than the overall area and included in the entire area as the range of wireless communication.
When each wireless communication terminal selects the entire area for wireless communication, the narrowband wireless communication function is used.
When each wireless communication terminal selects the cell area for wireless communication, the wideband wireless communication function is used.
When each of the wireless communication terminals transmits data, if the situation regarding the destination of the data satisfies a predetermined condition, the entire area is preferentially selected, and wireless communication is performed by the narrow band wireless communication function.
When a plurality of wireless communication terminals other than the destination receive the wireless signal transmitted by the narrow band wireless communication function, only the wireless communication terminal that has started transmission first receives the data of the received wireless signal. Sending data to the corresponding destination wireless communication terminal by the wideband wireless communication function or the narrowband wireless communication function.
Car dual wireless communication system, characterized in that.

( 4 ) Each of the plurality of wireless communication terminals is arranged in a vehicle structure or a space adjacent thereto.
The entire area is an area corresponding to the range of the vehicle structure.
The vehicle wireless communication system according to any one of (1) to ( 3) above.

According to the vehicle wireless communication system having the configuration of (1) above, the communication delay time can be shortened by appropriately using the narrow band wireless communication function and the wide band wireless communication function. That is, when the narrow band wireless communication function is used, the entire area is within the communicable range, so that the number of relays when the distance from the source to the destination is large can be reduced, and the delay time can be shortened. In addition, even if the source terminal and the destination terminal cannot directly communicate with each other due to the use of the narrow band wireless communication function, other terminals can relay using the wide band wireless communication function or the narrow band wireless communication function. By performing the above, data can be transferred to the destination terminal by an appropriate route. In addition, the narrowband wireless communication function can perform high-speed wireless communication even when the distance is relatively large. Since the wideband wireless communication function is not easily affected by jamming radio waves, efficient communication can be performed even in an environment where many terminals are arranged in a narrow space.

Further, according to the vehicle wireless communication system having the configuration of ( 1 ) above, the range of communication is set in a situation where the number of relays between the source terminal and the destination terminal is expected to increase and the communication delay time is expected to increase. The entire area is preferentially selected. Therefore, the number of relays between the source terminal and the destination terminal can be reduced, and the communication delay time can be shortened.

According to the vehicle wireless communication system having the configuration of ( 2 ) above, for example, in a situation where a large number of terminals are arranged in a narrow space, terminals having a high priority relay data, so that an efficient communication path is used. Will be available. For example, when the destination terminal cannot directly receive the radio wave from the source terminal, another terminal closest to the destination terminal, the terminal at the position where the number of relays is the least, the terminal on the main route, etc. By preferentially relaying, the communication delay time can be shortened.

According to the vehicle wireless communication system having the configuration of (3 ) above, in a situation where many terminals are arranged in a narrow space, for example, a plurality of terminals receive the same radio wave from the source terminal at almost the same time. Even in such a situation, it is possible to prevent the radio waves transmitted by these plurality of terminals from competing with each other and causing interference.

According to the vehicle wireless communication system having the configuration of (4 ) above, if each wireless communication terminal uses the narrow band wireless communication function, the reception area can be anywhere within the range of the vehicle structure.

According to the vehicle wireless communication system of the present invention, it is possible to suppress an increase in cost and avoid an increase in communication delay time and an increase in traffic. That is, when the narrow band wireless communication function is used, the entire area is within the communicable range, so that the number of relays when the distance from the source to the destination is large can be reduced, and the delay time can be shortened. In addition, even if the source terminal and the destination terminal cannot directly communicate with each other due to the use of the narrow band wireless communication function, it is appropriate to perform a relay operation by another terminal using the wide band wireless communication function. Data can be transferred to the destination terminal by any route.

The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through the embodiments described below (hereinafter referred to as "embodiments") with reference to the accompanying drawings. ..

FIG. 1 is a plan view showing a specific example of the arrangement of a plurality of wireless communication terminals and the configuration of a wireless communication line included in the vehicle wireless communication system of the embodiment of the present invention. FIG. 2 is a schematic diagram showing a configuration example of a network in the vehicle wireless communication system according to the embodiment of the present invention. FIG. 3 is a block diagram showing a configuration example of one wireless communication terminal used by the vehicle wireless communication system according to the embodiment of the present invention. FIG. 4 is a flowchart showing an outline of transmission processing in the wireless communication terminal at each node position. FIG. 5 is a flowchart showing an outline of reception processing in the wireless communication terminal at each node position. FIG. 6 is a flowchart showing a modified example of reception processing in the wireless communication terminal at each node position. FIG. 7 is a schematic diagram showing a configuration example of a communication network composed of a plurality of nodes that perform wireless communication.

Specific embodiments of the present invention will be described below with reference to the respective figures.

<Specific examples of arrangement of each terminal and configuration of wireless communication line>
FIG. 1 shows a specific example of the arrangement of a plurality of wireless communication terminals and the configuration of a wireless communication line included in the vehicle wireless communication system of the embodiment of the present invention.

The rectangular-shaped overall area ARL shown in FIG. 1 corresponds to the area of the vehicle structure of a general automobile. FIG. 1 shows an arrangement state of each element in a plane when the vehicle structure is viewed from above. The left end side of FIG. 1 represents the front side of the vehicle, and the right end side of FIG. 1 represents the rear side of the vehicle.

In the example shown in FIG. 1, a large number of wireless communication terminals 10-1, 10-3, ..., 10-17 are installed in each part of the entire area ARL, that is, the vehicle structure and the area adjacent thereto. The position and total number of each of these wireless communication terminals 10-1 to 10-17 are changed as necessary.

Each of these wireless communication terminals 10-1 to 10-17 requires various electrical components mounted on each part of the automobile, such as an electronic control unit (ECU), various sensors, various switches, and various loads. It is provided to enable the transmission and reception of the signal.

In the example shown in FIG. 1, by using the wireless communication function of the wireless communication terminals 10-1 to 10-17, wireless communication paths C01, C03, C04, ..., C16 connecting between them are formed. can do. Further, in the example shown in FIG. 1, a plurality of small cell regions ARS1, ARS2, and ARS3 that are sufficiently smaller than the entire region ARL are formed in the space inside the entire region ARL. Of course, each wireless communication path, the number, size, position, etc. of each small cell area are changed as necessary.

Further, the small cell regions ARS1 and ARS2 adjacent to each other are formed in a state in which a part thereof overlaps with each other. Further, the small cell regions ARS2 and ARS3 adjacent to each other are also formed in a state in which a part thereof overlaps with each other. Wireless communication terminals 10-3, 10-4, 10-8 are arranged inside the small cell area ARS1. Wireless communication terminals 10-8 and 10-11 are arranged inside the small cell area ARS2. Wireless communication terminals 10-12, 10-13, and 10-15 are arranged inside the small cell area ARS3.

It should be noted that each of the wireless communication terminals 10-1 to 10-17 shown in FIG. 1 is within a relatively small area such as within any of the small cell areas ARS1, ARS2, and ARS3 shown in FIG. It supports both narrow-range wireless communication and relatively large wide-area wireless communication within the range corresponding to the entire area ARL. Further, as will be described in detail later, each of the wireless communication terminals 10-1 to 10-17 uses a narrow band wireless communication function when performing wide area wireless communication, and when performing narrow range wireless communication. Uses a wideband wireless communication function.

It is assumed that the "wide area" in the present embodiment has a size of, for example, about 3 meters, and the "narrow area" has a size of, for example, about 1 meter. As a result, it is possible to suppress the radio waves transmitted by the vehicle wireless communication system in the own vehicle from affecting the wireless communication in another vehicle and various other wireless communications outside the own vehicle.

<Network configuration example>
FIG. 2 shows an example of a network configuration in the vehicle wireless communication system according to the embodiment of the present invention. That is, the wireless communication terminals 10-1 to 10-17 shown in FIG. 1 can be used to form a wireless communication network as shown in FIG.

In the network shown in FIG. 2, four small cell regions AR-A, AR-B, AR-C, and AR-D that are different from each other are formed. Here, the two small cell regions AR-A and AR-B that are adjacent to each other are partially overlapped. Similarly, the two small cell regions AR-B and AR-C that are adjacent to each other are also partially overlapped. Further, the two small cell regions AR-C and AR-D that are adjacent to each other are also in a partially overlapped state.

In the example of FIG. 2, the small cell region AR-A corresponding to the A group includes three nodes NA-1, NA-2, and NA-3. Further, the small cell region AR-B corresponding to the B group includes four nodes NB-1, NB-2, NB-3, and NB-4. Further, the small cell region AR-C corresponding to the C group includes four nodes NC-1, NC-2, NC-3, and NC-4. Further, the small cell region AR-D corresponding to the D group includes three nodes ND-1, ND-2, and ND-3.

Among the nodes shown in FIG. 2, the node NA-3 in the small cell area AR-A and the node NB-1 in the small cell area AR-B are common and are composed of one wireless communication terminal 10. NS. Similarly, the node NB-4 in the small cell area AR-B and the node NC-1 in the small cell area AR-C are common, and the node NC-4 in the small cell area AR-C and the small cell are also used. It is common to the node ND-1 in the area AR-D, and each is composed of one wireless communication terminal 10. Further, the other nodes NA-1, NA-2, NB-2, NB-3, NC-2, NC-3, ND-2, and ND-3 are each composed of one wireless communication terminal 10. ..

In the example of FIG. 2, the nodes NA-1 to NA-3 in the small cell area AR-A are arranged in a state where they can be connected to each other by a wireless communication line. Further, the nodes NB-1 to NB-4 in the small cell area AR-B are arranged in a state where they can be connected to each other by a wireless communication line. Further, the nodes NC-1 to NC-4 in the small cell area AR-C are arranged in a state where they can be connected to each other by a wireless communication line. Further, the nodes ND-1 to ND-3 in the small cell area AR-D are arranged in a state where they can be connected to each other by a wireless communication line.

Further, since the node NA-3 and the node NB-1 are common, a communication path can be established between the small cell areas AR-A and AR-B adjacent to each other by passing through this common node. Can be secured. Similarly, since the node NB-4 and the node NC-1 are common, a communication path can be secured between the small cell areas AR-B and AR-C that are adjacent to each other. Further, since the node NC-4 and the node ND-1 are common, a communication path can be secured between the small cell areas AR-C and AR-D that are adjacent to each other.

In the present embodiment, the wireless communication terminal 10 arranged at the position of each node has a wide range corresponding to the entire area ARL in addition to the wireless communication in a narrow range corresponding to each small cell area AR-A to AR-D. It also has a function to perform wireless communication within the range. Therefore, it is possible for all the nodes inside the entire area ARL to wirelessly communicate with each other without necessarily providing the above-mentioned common node.

<Network design method>
When actually designing a communication network as shown in FIG. 2, for example, the wireless communication terminals 10-1 to 10-17 shown in FIG. 1 are divided into a plurality of groups, and each group is divided into, for example, FIG. Corresponds to any of the small cell regions AR-A, AR-B, AR-C, and AR-D shown in 2. Then, a network is configured so as to connect a plurality of adjacent small cell regions AR-A, AR-B, AR-C, and AR-D to each other. The connection relationship between a plurality of small cell areas is determined in advance. In addition, it is desirable to create a group so as to include one or more nodes that straddle a plurality of small cell areas. Then, for each of the small cell regions AR-A, AR-B, AR-C, and AR-D, the route is designed only in the cell. The route design in the cell can be automatically processed by using, for example, the procedure of "dynamic routing".

<Example of general communication operation on the network>
In the communication network shown in FIG. 2, a general operation example assuming a case where data is transmitted from the source node NA-1 to the node ND-2 will be described below. However, in the case of the system of the present embodiment, a special operation different from the operation shown below can be performed. This will be explained later.

1. 1. In node NA-1, since the destination is the communication of node ND-2, the small cell area AR-A, which is the own cell, is connected to the small cell area AR-D including the destination via AR-B and AR-C. Make sure that. Here, since the connection between the small cell regions AR-A, AR-B, AR-C, and AR-D is fixed and predetermined, for example, the information held in a predetermined table is referred to. By doing so, you can check the connection.

2. In order to transfer data to the small cell area AR-D including the destination node, it is necessary to first send the data to the small cell area AR-B adjacent to the own cell, so two small cells are sent from node NA-1. A communication path to the node NA-3 existing at a position straddling the cell areas AR-A and AR-B is created. Specifically, triggered by the operation of the source node NA-1, the procedure of "dynamic routing" is executed in the small cell area AR-A, the connection of each node in this cell is confirmed, and communication is performed. The appropriate routes available are automatically created.

3. 3. According to the route created by the above processing, each node in the small cell area AR-A transfers the transmission data output by the node NA-1 to the node NA-3.

4. Here, since the node NA-3 is common to the node NB-1, the same as the above "2." and "3." in the small cell area AR-B based on the transmission data received by the node NB-1. Perform the operation of. As a result, a route from node NB-1 to node NB-4 is created in the small cell area AR-B, and the transmission data of node NB-1 is transferred to node NB-4 using this route. ..

5. Further, since the node NB-4 is common to the node NC-1, the same as the above "2." and "3." in the small cell area AR-C based on the transmission data received by the node NC-1. Do the action. As a result, a route from node NC-1 to node NC-4 is created in the small cell area AR-C, and the transmission data of node NC-1 is transferred to node NC-4.

6. Further, since the node NC-4 is common to the node ND-1, the procedure of "dynamic routing" is executed in the small cell area ARD based on the transmission data received by the node ND-1, and this cell is executed. The connection of each node within is confirmed, and the appropriate route available for communication is automatically created. Based on this route, the route from the node ND-1 to the destination node ND-2 is specified in the small cell area AR-D, and the transmission data of the node ND-1 is transferred to the node ND-2.

When the destination node returns data to the source node, the data is transmitted in the opposite direction using the same route as when the data is transmitted from the source to the destination. Further, it is also possible to perform a process for creating the above route in each cell in advance, and each node holds the information obtained as a result. In that case, when transferring the actual transmission data, the time required to create the above-mentioned route is significantly shortened.

In a communication network as shown in FIG. 2, since a large number of nodes can be used as needed, various routes are selectively used to secure a communication route from a data source to a destination (destination). It is possible to do. However, since the number of communication partner nodes is large, the efficiency when searching for a route or when actually transmitting data is lowered. That is, when the route search is performed when the communication route is not determined, it is necessary to transmit signals such as packets to the other node of the route that cannot be actually used, so that the number of the other nodes is increased. As the number increases, useless traffic increases, the load of communication processing on the network increases, and the signal transmission delay time increases. Further, even after the communication path is determined, the number of nodes that relay signals on this communication path increases, so that the signal transmission delay time increases.

However, in the system of the present embodiment, in addition to the function of each wireless communication terminal 10 wirelessly communicating within the range of each small cell area AR-A to AR-D, there is also a function of wirelessly communicating within the range of the entire area ARL. I have. Therefore, for example, when the node NA-1 in the small cell area AR-A transmits data to the node ND-2 in the small cell area AR-D as a destination, the small cell area from within the small cell area AR-A is transmitted. It is also possible to directly wirelessly transmit to and from each node in AR-D. If the communication route is appropriately changed by using this function, the number of relays on the route between the source and the destination is reduced, and the delay time of the transmitted data is shortened. Also, the traffic generated on the network can be reduced.

<Configuration example of wireless communication terminal>
<Overview of overall configuration>
FIG. 3 shows a configuration example of one wireless communication terminal 10 used by the vehicle wireless communication system of the embodiment of the present invention.

The wireless communication terminal 10 includes a receiving function unit 20 and a transmitting function unit 30. Further, the antennas 29a and 29b are connected to the receiving function unit 20, and the antennas 37a and 37b are connected to the transmitting function unit 30.

The transmission function unit 30 has a function for transmitting a radio signal (radio wave) including transmission data when the own terminal transmits data as a transmission source. The reception function unit 20 has a function of receiving data transmitted as a wireless signal by another terminal and a function of retransmitting the received data as a wireless signal when performing a relay operation.

<Structure of reception function unit 20>
The receiving function unit 20 includes a wireless communication unit 21, a wireless band switching function unit 22, a cell discriminating function unit 23, a relay data generation function unit 24, a destination discriminating function unit 25, a received data output function unit 26, and a communication success discriminating function unit 27. , And an interface (I / F) 28. Further, the wireless communication unit 21 includes a narrow band wireless communication unit 21a and a wide band wireless communication unit 21b.

The broadband wireless communication unit 21b has a function for transmitting and receiving a wireless signal by a wireless communication function having a very wide frequency bandwidth per communication channel (for example, 500 MHz or more) of the wireless signal. Specifically, wideband radio has a function to perform special wireless communication such as UWB (Ultra Wide Band) for which a standard is being formulated and Impulse UWB shown in Japanese Patent Application Laid-Open No. 2014-220745. The communication unit 21b has.

Generally, UWB has the following characteristics.
1. 1. It is a wireless technology capable of short-range high-speed communication, and also has position measurement and radar functions.
2. Low power consumption.
3. 3. Strong against disturbing radio waves.
4. High-speed communication is possible, but the speed drops extremely as the distance increases.
5. The accuracy of position detection is high, and the error is about several centimeters.
6. Communication is performed by spreading over a wider frequency band than before.

Therefore, the UWB can exhibit higher communication performance than a general communication method in a situation where a large number of wireless communication terminals 10 are arranged in a space on a narrow vehicle shown in FIG. 1, for example. can.

In the present embodiment, the wideband wireless communication unit 21b is relatively within the range of the small cell regions ARS1 to ARS3 shown in FIG. 1 and the small cell regions AR-A to AR-D shown in FIG. It is used only when performing wireless communication in a small range. Therefore, the transmission output power of the radio signal in the broadband wireless communication unit 21b is limited in advance so that it reaches only within the narrow cell range.

On the other hand, the narrowband wireless communication unit 21a transmits and receives the wireless signal by a general wireless communication function (other than UWB) in which the frequency bandwidth per communication channel of the wireless signal is narrower than that of the wideband wireless communication unit 21b. It has a function for.

In the present embodiment, the narrowband wireless communication unit 21a is used only when wireless communication is performed in a relatively wide range as in the overall area ARL shown in FIGS. 1 and 2. Therefore, the transmission output power of the radio signal in the narrow band wireless communication unit 21a can be received anywhere within the range of the entire area ARL.

When the wireless communication unit 21 performs wireless communication, the wireless band switching function unit 22 determines either the narrowband wireless communication unit 21a or the wideband wireless communication unit 21b in the wireless communication unit 21 under predetermined conditions and at that time. It has a function to automatically select according to the situation.

The cell determination function unit 23 has a function for determining whether or not the cell to which the node of the own terminal belongs and the cell to which the node of the terminal to be the destination of the relay communication data belongs are the same. There is. The cell discrimination function unit 23 represents the relationship between each of the small cell areas AR-A to AR-D included in the entire network as shown in FIG. 2 and each node belonging to each of these cells. Since the information is grasped in advance, the above determination can be easily performed.

The relay data generation function unit 24 inputs communication data received as radio signals from other nodes by each of the narrowband wireless communication unit 21a and the wideband wireless communication unit 21b via the destination determination function unit 25. Then, the relay data generation function unit 24 has a function of extracting only the received data whose destination is other than the own terminal to be relayed from the communication data and outputting it as the relay data.

The destination determination function unit 25 inputs communication data received as wireless signals from other nodes by each of the narrowband wireless communication unit 21a and the wideband wireless communication unit 21b via the communication success determination function unit 27. Then, the destination determination function unit 25 has a function of identifying whether or not the destination of the communication data is the own terminal.

The reception data output function unit 26 inputs communication data received as radio signals from other nodes by each of the narrowband wireless communication unit 21a and the wideband wireless communication unit 21b via the destination determination function unit 25. Then, the reception data output function unit 26 has a function of extracting only the reception data of the own terminal from the communication data and outputting it to the interface 28.

The communication success determination function unit 27 has a function of determining whether or not each of the narrowband wireless communication unit 21a and the wideband wireless communication unit 21b has succeeded in communicating with respect to the communication data received as a wireless signal from another node. Have. It also has a function to monitor whether or not the terminal of the destination of the corresponding communication data has sent ACK (acknowledgement), which is a response to confirmation of receipt of the communication data, when the local terminal is not the destination. ..

The interface 28 is connected to signal inputs of various electrical components on the vehicle. When the own terminal receives communication data addressed to the own terminal, the received data is output to various electrical components via the received data output function unit 26 and the interface 28.

When the own terminal receives communication data addressed to another terminal, the relay data generation function unit 24 generates relay data for relaying the communication data. This relay data is converted into a radio signal by the narrow band wireless communication unit 21a or the wideband wireless communication unit 21b via the cell discrimination function unit 23 and the radio band switching function unit 22, and is transmitted as a radio wave from the antenna 29a or 29b. NS. Which of the narrowband wireless communication unit 21a and the wideband wireless communication unit 21b is used for transmission for relay changes depending on the situation at that time.

<Structure of transmission function unit 30>
On the other hand, the transmission function unit 30 includes a wireless communication unit 31, a wireless band switching function unit 32, a cell determination function unit 33, a destination determination function unit 34, a communication data creation function unit 35, and an interface 36. Further, the wireless communication unit 31 includes a narrow band wireless communication unit 31a and a wide band wireless communication unit 31b.

The wideband wireless communication unit 31b, like the wideband wireless communication unit 21b, has a function for transmitting a wireless signal by a special wireless communication function having a very wide frequency bandwidth per communication channel of the wireless signal. There is. That is, the wideband wireless communication unit 31b has a function of performing wireless communication such as the UWB whose standard is being formulated and the impulse UWB disclosed in Japanese Patent Application Laid-Open No. 2014-220745.

In the present embodiment, the broadband wireless communication unit 31b is relatively within the range of the small cell regions ARS1 to ARS3 shown in FIG. 1 and the small cell regions AR-A to AR-D shown in FIG. It is used only when performing wireless communication in a small range. Therefore, the transmission output power of the radio signal in the broadband wireless communication unit 31b is limited in advance so that it reaches only within the narrow cell range.

On the other hand, the narrowband wireless communication unit 31a transmits the wireless signal by a general wireless communication function (other than UWB) in which the frequency bandwidth per communication channel of the wireless signal is narrower than that of the wideband wireless communication unit 31b. It has a function.

In the present embodiment, the narrowband wireless communication unit 31a is used only when wireless communication is performed in a relatively wide range as in the entire area ARL shown in FIGS. 1 and 2. Therefore, the transmission output power of the radio signal in the narrow band wireless communication unit 31a can be received anywhere within the range of the entire area ARL.

When the wireless communication unit 31 performs wireless communication, the wireless band switching function unit 32 determines either the narrowband wireless communication unit 31a or the wideband wireless communication unit 31b in the wireless communication unit 31 under predetermined conditions and at that time. It has a function to automatically select according to the situation.

The interface 36 is connected to the signal outputs of various electrical components on the vehicle. That is, when the electrical component requests data transmission, the communication data is input to the own terminal via the interface 36.

The communication data creation function unit 35 has a function of creating predetermined communication data necessary for wireless communication of the data based on the data input from the interface 36. For example, a packet including information representing a destination terminal or node, information representing a source terminal or node, and the like is created as communication data.

The destination determination function unit 34 has a function for determining a communication route that can be used to deliver the communication data created by the communication data creation function unit 35 to the destination. The routes that can be used in the small cell to which the node of the own terminal belongs can be determined in advance, or can be automatically determined by "dynamic routing". Further, since it is possible to accurately measure the position and distance of each terminal by using UWB, the position and distance of each terminal can be easily grasped if the measurement is performed in advance.

The cell determination function unit 33 has a function of determining whether or not the cell including the destination node and the cell of the own node are the same for the communication data input via the destination determination function unit 34. ing. The cell discrimination function unit 33 represents the relationship between each of the small cell areas AR-A to AR-D included in the entire network as shown in FIG. 2 and each node belonging to each of these cells. Since the information is grasped in advance, the above determination can be easily performed.

When the wireless communication terminal 10 does not need to perform the transmission operation and the reception operation at the same time, for example, it is not necessary to separately prepare the two wireless communication units 21 and 31 shown in FIG. And it can also be composed of only a single unit common to reception. Further, each function in the reception function unit 20 and each function in the transmission function unit 30 shown in FIG. 3 are a part of the processing executed by the software by the microcomputer (not shown) that controls the wireless communication terminal 10. However, it can also be configured with dedicated hardware.

<Explanation of characteristic operation of wireless communication terminal 10>
<Outline of transmission process>
FIG. 4 shows an outline of the transmission process in the wireless communication terminal 10 at each node position. That is, when each wireless communication terminal 10 transmits the data input to the interface 36 as a wireless signal to another terminal in accordance with the transmission request input from the interface 36, the transmission process shown in FIG. 4 (Send) is executed.

In step S11, the cell discrimination function unit 33 identifies whether or not the node of the destination of the communication data to be transmitted exists in a cell different from the node of the own terminal. Further, the distance from the position of the node of the own terminal to the destination node is specified, and the cell discrimination function unit 33 identifies whether or not this distance is larger than the threshold value. It is assumed that the threshold value used in this comparison is set to the same degree as the radius of each small cell region AR-A to AR-D shown in FIG. 2, for example. Information on the distance between each node is stored in a non-volatile memory (not shown), for example, a value obtained by measuring in advance.

If the destination node exists in a cell different from the node of the own terminal, or if the distance from the node of the own terminal to the destination node is large, the process proceeds from S11 to S12. In other cases, the process proceeds from S11 to S13.

In step S12, the wireless band switching function unit 32 selects the narrow band wireless communication unit 31a in the wireless communication unit 31. That is, the wireless band switching function unit 32 gives the communication data to be transmitted to the narrow band wireless communication unit 31a, and transmits the data by the narrow band wireless communication. Further, since the transmission output power of the narrow band wireless communication unit 31a is relatively large, the range of wireless communication in this case is the entire area ARL.

When the narrowband wireless communication unit 31a starts transmitting data by narrowband wireless communication, for example, CSMA / CA (Carrier Sense Multiple) is used to avoid collision of wireless signals from a plurality of sources. Access / Collision Avoidance: Carrier detection multiple access / collision avoidance method) communication protocol is used. That is, it is processed as follows.

1. 1. Before starting communication, each wireless terminal executes "Carrier Sense" to check whether or not there is another wireless terminal currently communicating.
2. If multiple wireless terminals share the same wireless line and other terminals are not communicating, their own communication is started (Multiple Access).
3. 3. If another wireless terminal exists during "carrier detection", a waiting time of a random length is set after detecting the end of transmission of the other wireless terminal, and after this waiting time, one's own communication is provided. (Collision Avoidance).

On the other hand, in step S13, the information of the communication route in the own cell generated by the destination determination function unit 34 is used as the transmission route of the corresponding communication data. Further, in the next step S14, the wireless band switching function unit 32 selects the wideband wireless communication unit 31b in the wireless communication unit 31. That is, the wireless band switching function unit 32 gives the communication data to be transmitted to the wideband wireless communication unit 31b, and transmits the data by the wideband wireless communication. Further, since the transmission output power of the wideband wireless communication unit 31b is relatively small, the range of wireless communication in this case is limited to the own cell.

That is, when each wireless communication terminal 10 executes the transmission process shown in FIG. 4, the destination node exists in a cell different from the node of the own terminal, or the destination node exists at a relatively distant position. In this case, the narrow band wireless communication is automatically selected, and at the same time, the entire area ARL is selected as the range of the wireless communication.

Therefore, in the case of the communication network shown in FIG. 2, if the source terminal is located at the node NA-1 and the data destination terminal is located at the node ND-2, transmission is performed. Since the source and destination cells are different and the distance is large, the wireless communication terminal 10 at the position of the node NA-1 selects narrow-band wireless communication that covers the entire area ARL as the range of wireless communication.

Therefore, it is possible to transmit data from the source node NA-1 to the destination node ND-2 by one wireless communication. Further, even if the destination node ND-2 cannot directly receive the data transmitted by this wireless communication, if another node located near the node ND-2 receives the data and relays the data, Data can be delivered to the destination node ND-2 with a small number of relays. Therefore, when the distance between the source and the destination is large, the communication delay time when transmitting data on this network can be shortened.

On the other hand, if the destination node is in the same cell as the node of the local terminal, or if the destination node is relatively close to the source, wideband wireless communication is selected and the range of wireless communication is limited. Limited to own cell.

Therefore, in the case of the communication network shown in FIG. 2, if the source terminal exists at the position of the node NB-1 and the terminal of the data destination exists at the position of the node NB-3, transmission is performed. Since the source and destination cells are the same and the distance is small, the wireless communication terminal 10 at the position of the node NB-1 selects wideband wireless communication in which the wireless communication range is the small cell area AR-B.

Here, when UWB is used as wideband wireless communication, the distance between terminals is short, high-speed data communication is possible, and it is strong against interfering radio waves. Therefore, for example, in a narrow cell as shown in FIG. Even in an environment where a plurality of terminals are arranged, it is possible for a plurality of terminals located close to each other to communicate at almost the same time. Further, since the range of wireless communication is limited to the same cell, extra traffic does not occur in other cells with one data transmission.

<Overview of reception processing>
FIG. 5 shows an outline of reception processing in the wireless communication terminal 10 at each node position. That is, when the wireless communication terminal 10 at each node position receives a wireless signal including communication data transmitted from the wireless communication terminal at another node position by the antenna 29a or 29b, the reception process (Recv) shown in FIG. ) Is executed.

When the wireless communication terminal 10 of the own node receives a wireless signal transmitted from a terminal of another node by narrow-band wireless communication, the radio wave of this wireless signal is received by the antenna 29a, and the narrow-band wireless communication unit 21a Is received and processed and output as communication data. When the wireless communication terminal 10 of the own node receives a wireless signal transmitted from a terminal of another node by wideband wireless communication, the radio wave of this wireless signal is received by the antenna 29b, and the wideband wireless communication unit 21b Is received and processed and output as communication data. The communication data output from either the narrowband wireless communication unit 21a or the wideband wireless communication unit 21b is input to the destination determination function unit 25 via the communication success determination function unit 27.

In step S21 of FIG. 5, the destination determination function unit 25 determines whether or not the destination of the received communication data is the local node. That is, since the packet header of the communication data contains information indicating the destination, by comparing this with the information such as the ID assigned to the own node, the communication data addressed to the own node and the communication addressed to the other node can be compared. Distinguish from data.

When the communication data addressed to the own node is received, the reception data output function unit 26 processes the communication data and outputs the received data to the interface 28 (S22). Further, when the communication data addressed to another node is received, the operation of the relay function PR1 shown in FIG. 5 is executed.

In step S23, the cell determination function unit 23 identifies whether or not the destination node of the relay data exists in a cell different from the node of the own terminal. Further, the distance from the position of the node of the own terminal to the destination node is specified, and the cell discrimination function unit 23 identifies whether or not this distance is larger than the threshold value. The threshold value used in this comparison is, for example, about the same as the radius of each small cell region AR-A to AR-D shown in FIG. The relay data generated by the relay data generation function unit 24 is created by adding, for example, the information of the relayed own node to the communication data received by the own node.

If the destination node exists in a cell different from the node of the own terminal, or if the distance from the node of the own terminal to the destination node is large, the process proceeds from S23 to S24. In other cases, the process proceeds to S25.

In step S24, the wireless band switching function unit 22 selects the narrow band wireless communication unit 21a in the wireless communication unit 21. That is, the radio band switching function unit 22 gives the relay data to be transmitted to the narrow band wireless communication unit 21a, and transmits the relay data by the narrow band wireless communication. Further, since the transmission output power of the narrow band wireless communication unit 21a is relatively large, the range of wireless communication in this case is the entire area ARL.

When the narrowband wireless communication unit 21a starts transmitting data by narrowband wireless communication in S24, in order to avoid collision of radio signals from a plurality of sources, the same as in S12 described above. For example, the CSMA / CA communication protocol is used.

In step S25, the information of the communication route in the own cell generated by the destination determination function unit 25 is used as the transmission route of the corresponding relay data. Further, in the next step S26, the wireless band switching function unit 22 selects the wideband wireless communication unit 21b in the wireless communication unit 21. That is, the wireless band switching function unit 22 gives the relay data to be transmitted to the wideband wireless communication unit 21b, and transmits the data by the wideband wireless communication. Further, since the transmission output power of the wideband wireless communication unit 21b is relatively small, the range of wireless communication in this case is limited to the own cell.

When the terminal of the destination of the communication data succeeds in receiving the transmitted data, it returns the reception confirmation response ACK to the transmission source by the same wireless signal. Therefore, each terminal other than the destination that relays the data can grasp whether or not the destination terminal has received each communication data by monitoring the presence or absence of ACK transmission from the destination terminal. When the ACK transmission from the destination terminal is detected, the operation of the relay function PR1 shown in FIG. 5 is not started or stopped because the operation of the relay function PR1 shown in FIG. 5 is already unnecessary in the other terminal that has received the same communication data.

Therefore, when each wireless communication terminal 10 executes the reception process shown in FIG. 5, the corresponding communication data is received even in a situation where the destination node cannot directly receive the communication data transmitted as a wireless signal. When the created other terminal executes the relay function PR1 of FIG. 5, the relayed communication data can be delivered to the destination node.

<Modification example of reception processing>
FIG. 6 shows a modified example of the reception process in the wireless communication terminal 10 at each node position. That is, when the wireless communication terminal 10 at each node position receives a wireless signal including communication data transmitted from the wireless communication terminal at another node position by the antenna 29a or 29b, the reception process (Recv_2) shown in FIG. ) Is executed. In each step S21 and S22 of FIG. 6, the same processing as S21 and S22 shown in FIG. 5 is executed. The operation shown in FIG. 6 will be described below.

When the wireless communication terminal 10 at each node position receives communication data that is not addressed to its own node, it monitors whether or not ACK transmission from the destination terminal for this communication data is not detected (S31). Then, if the ACK transmission is not detected, the currently selected priority mode is identified (S32). This priority mode can be changed as needed by, for example, switching the switch. In the present embodiment, it is assumed that there are three types of values representing the priority mode, "1", "2", and "3".

When the value of the priority mode is "1", among the terminals that have received the communication data, the terminal having a closer distance to the target destination terminal is preferentially selected (S34). When the value of the priority mode is "2", among the terminals that have received the communication data, the terminal with the smaller number of relays on the route to the target destination terminal is preferentially selected (S36).

For example, when a node at a position adjacent to the destination node receives communication data, the distance from the local terminal to the destination is short and the expected number of relays is only once, so the priority mode value is "1" or In the case of "2", the priority of the own terminal is the highest. On the other hand, in the case of a terminal existing in a cell different from the destination node, the distance from the own terminal to the destination is long and the expected number of relays increases, so the priority mode value is "1" or "2". In that case, the priority of the own terminal is lowered.

When the value of the priority mode is "3", the terminal having a high priority determined in advance is preferentially selected from the terminals that have received the communication data (S37). For example, a terminal located near the center of each cell or in a main position, a terminal placed in a position where wireless communication with other terminals is easy, or a terminal placed in a main cell. If the priority of is set high in advance, the number of relays can be reduced and efficient communication can be performed.

Then, in a situation reflecting the result of any one of S34, S36, and S37, it is identified in step S38 whether or not the wireless communication terminal 10 at the position of the own node is a terminal having a high priority. If the local node is a terminal with a high priority, the same processing as the relay function PR1 shown in FIG. 4 is performed in S39. If the local node is not a high-priority terminal, the communication data received by the local terminal is discarded in S40 after a lapse of a predetermined time.

When the plurality of wireless communication terminals 10 that have received the communication data each execute the relay function PR1 in S39, for example, when executing the CSMA / CA communication protocol in S24, the waiting of the terminal having a high priority By shortening the time, the difference in priority of each terminal can be reflected in the operation of the entire system.

<Explanation of "dynamic routing">
FIG. 7 shows a configuration example of a communication network composed of a plurality of nodes that perform wireless communication. In FIG. 7, it is assumed that the nodes NA, NB, NS, NC, and N-D that perform wireless communication exist in one cell. Further, in the embodiment of the present invention, in order to secure the communication path in the cell, the wireless communication terminal 10 at each node position selects wideband wireless communication, and the range of wireless communication is set in the cell (narrow area). limit.

In the example of FIG. 7, nodes NA and N-B adjacent to each other are connected by one wireless communication, nodes NB and NS are connected by one wireless communication, and nodes NS and N-S are connected. C is connected by one wireless communication, and nodes NC and N-D are connected by one wireless communication. However, in the initial state, each node does not know the route that can be used for communication with other nodes other than the adjacent nodes.

Here, assuming a situation in which data is transmitted with the node NS shown in FIG. 7 as the communication source and the node N-D as the destination, a typical procedure for executing "dynamic routing" will be described below. do.
1. 1. First of all, as "communication source node NS, destination node N-D, no relay node information", the communication source node NS broadcasts (Broad Cast: BC) to a route-request packet (RREQ). ) Send information as a radio signal. This information is received by the nodes NB and NC at adjacent positions capable of wireless communication with the communication source node NS. In addition, radio waves do not reach other nodes due to the distance.

2. In each of the nodes NB and NC, since the destination of the received information is not the own node, the information of the own node is stored in the relay node information, and the RRQ information is transmitted by broadcasting. In this case, the REQU information transmitted by the nodes NB by broadcasting is received by the nodes NA and NS. Further, the REQU information transmitted by the nodes NC by broadcasting is received by the nodes NS and ND.

3. 3. Since the destination of the RRQ information received from the nodes N-B is not the own node, the node NA stores the information of the own node in the relay node information and transmits the RRQ information by broadcasting. Further, since the destination of the REQU information received from the node NC is the own node, the node N-D has each node NS, NC, N based on the information of the communication source node and the relay node information. Understand that communication is performed by a route that goes through -D in order.

4. The node N-B receives the RRQ information from the node N-A, but ignores this RRQ information because the information of its own node is included in the relay node information of this REQU information.

5. The node N-D returns the route-reply packet (RREP) information including the route information based on the route information determined by the contents of the received REQU information. This reply is sent to the adjacent node NC.

6. The node NC receives the RREP information from the node N-D, and uses the information contained therein to transmit the RREP information to the node NS.

7. The node NS grasps the route to the destination node N-D based on the route information included in the RREP information received from the node NC. Then, according to this route, the data whose destination is ND is transmitted to the adjacent nodes NC.

8. Node NC relays the data received from node NS and transfers it to the destination node ND.

By the above procedure, communication between the communication source node NS and the destination node ND becomes possible. Further, for example, when a failure occurs in any of the nodes and the wireless communication line is interrupted, the necessary route can be secured by repeating the above procedure from the beginning.

<Possibility of system deformation>
In the example shown in FIG. 1, it is assumed that the wide area communication range when each wireless communication terminal 10 uses narrow band wireless communication is the entire area ARL substantially corresponding to the vehicle structure of the automobile. However, the area may be formed so that the entire area ARL includes only the space inside the vehicle interior or only the space of the luggage room. Further, for example, a directional antenna may be used to adjust each range of a wide range and a narrow range. Further, it is expected that the size of each small cell formed in the entire area ARL and the total number of cells will be changed as necessary.

Further, in the above-described embodiment, it is assumed that each wireless communication terminal 10 uses only one communication channel when performing narrowband wireless communication using the narrowband wireless communication unit 21a or 31a. , It may be controlled to switch the communication channel as needed.

In the above-described embodiment, it is assumed that all the wireless communication terminals 10 constituting the vehicle wireless communication system have both a narrow-band wireless communication function and a wide-band wireless communication function. Terminals having only one of the functions and the wideband wireless communication function may be added on the same network. Further, the system may be configured so that only some terminals on the network have the relay function PR1. However, it is desirable to arrange at least one terminal having the relay function PR1 in each small cell.

Further, in the above-described embodiment, it is assumed that the control is performed after defining the range of each of the plurality of small cells in advance, but the control is simply performed between the terminals without defining a special cell in advance. Whether to use the narrow band wireless communication function or the wide band wireless communication function may be determined only by the magnitude of the distance. In this case, for example, in step S11 of FIG. 4 and step S23 of FIG. 5, it is not determined whether the destination node is a cell different from the node of the own terminal, but only the magnitude of the distance is determined.

As described above, according to the vehicle wireless communication system according to the embodiment of the present invention, for example, each wireless communication terminal 10 performs the relay function PR1 during the transmission process shown in FIG. 4 and the reception process shown in FIG. When executing, when the destination node exists in a cell different from the own cell, or when the destination is far away, narrow band wireless communication is preferentially selected to perform wide area wireless communication. become. Therefore, the number of relays in the communication path from the source to the destination is reduced, and the communication delay time is shortened. In addition, this suppresses the increase in traffic generated on the network.

Further, even in a situation where the destination terminal cannot directly receive the radio wave of the source terminal, it is possible to deliver the communication data from the source to the destination by executing the relay function PR1 by another terminal. become. Further, as in steps S34, S36, and S37 shown in FIG. 6, the priority of the terminal that performs the relay operation is determined in consideration of the distance to the destination terminal, the number of relays, the priority determined in advance, and the like. As a result, efficient relay operation is possible for the entire system. That is, the communication delay time is shortened, and the increase in traffic generated on the network is suppressed.

For example, when each wireless communication terminal 10 executes the transmission process shown in FIG. 4 or the reception process shown in FIGS. 5 and 6, communication is performed to switch between narrow band wireless communication and wide band wireless communication. It is not necessary to frequently measure the delay time of, and the switching process becomes easy.

Here, the features of the above-described embodiments of the vehicle wireless communication system according to the present invention are briefly summarized and listed below in [1] to [6], respectively.
[1] A plurality of wireless communications having a narrow band wireless communication function (narrow band wireless communication units 21a, 31a) and a wide band wireless communication function (wide band wireless communication units 21b, 31b) having different frequency bands to be used. Equipped with a terminal (10)
Each wireless communication terminal has a total area (ARL) as a range of wireless communication, and a plurality of cell areas (small cell areas AR-A to AR-D, ARS1) smaller than the total area and included in the total area. Select one of ~ ARS3) and select
When each wireless communication terminal selects the entire area for wireless communication, the narrowband wireless communication function is used.
When each wireless communication terminal selects the cell area for wireless communication, the wideband wireless communication function is used.
When each of the wireless communication terminals transmits data, if the situation regarding the destination of the data satisfies a predetermined condition, the entire area is preferentially selected, and wireless communication is performed by the narrow band wireless communication function (the narrow band wireless communication function). S11, S12, S23, S24),
A wireless communication system for vehicles characterized by this.

[2] Each of the wireless communication terminals has a function of acquiring information regarding the position or distance of each of the other wireless communication terminals.
When each wireless communication terminal transmits data, if the destination terminal of the data does not exist in the same cell area as the own terminal, or if the distance to the destination terminal is greater than or equal to a predetermined value, the entire area Is preferentially selected, and wireless communication is started by the narrow band wireless communication function (S11, S12, S23, S24).
The vehicle wireless communication system according to the above [1].

[3] Priorities are set for each of the wireless communication terminals.
When the wireless communication terminal other than the destination receives the wireless signal transmitted by the narrow band wireless communication function, the wireless communication terminal having a high priority receives the data of the received wireless signal to the destination wireless communication. It is transmitted to the terminal by the wideband wireless communication function or the narrowband wireless communication function (S32 to S39).
The vehicle wireless communication system according to the above [1] or [2].

[4] When a plurality of the wireless communication terminals other than the destination receive the wireless signal transmitted by the narrow band wireless communication function, only the wireless communication terminal that has started transmission first receives the wireless signal. Data is transmitted to the corresponding destination wireless communication terminal by the wideband wireless communication function or the narrowband wireless communication function (S12, S24: use of CSMA-CA, etc.).
The vehicle wireless communication system according to the above [1] or [2].

[5] Each of the plurality of communication nodes is arranged in the vehicle structure or a space adjacent thereto.
The entire area corresponds to the range of the vehicle structure (see FIG. 1).
The vehicle wireless communication system according to any one of the above [1] to [4].

[6] A plurality of wireless communications having a narrow band wireless communication function (narrow band wireless communication units 21a, 31a) and a wide band wireless communication function (wide band wireless communication units 21b, 31b) having different frequency bands to be used. Equipped with a terminal (10)
Each wireless communication terminal has a first region (ARL) and a second region narrower than the first region (small cell regions AR-A to AR-D, ARS1 to ARS3) as the range of wireless communication. Select one of
When each of the wireless communication terminals selects the first region for wireless communication, the narrow band wireless communication function is used.
When each wireless communication terminal selects the second region for wireless communication, the wideband wireless communication function is used.
When each of the wireless communication terminals transmits data, if the situation regarding the destination of the data satisfies a predetermined condition, the first region is preferentially selected and wireless communication is performed by the narrow band wireless communication function. (S11, S12, S23, S24),
A wireless communication system for vehicles characterized by this.

10 Wireless communication terminal 20 Reception function unit 21, 31 Wireless communication unit 21a, 31a Narrow band wireless communication unit 21b, 31b Wideband wireless communication unit 22, 32 Wireless band switching function unit 23, 33 Cell discrimination function unit 24 Relay data generation function unit 25, 34 Destination discrimination function unit 26 Received data output function unit 27 Communication success determination function unit 28, 36 Interface 29a, 29b, 37a, 37b Antenna 30 Transmission function unit 35 Communication data creation function unit AR-A, AR-B, AR -C, AR-D Small cell area ARL Overall area ARS1, ARS2, ARS3 Small cell area C01, C03, C04, C05, C07 Wireless communication path C08, C09, C11, C12, C13, C14 Wireless communication path C15, C16 Wireless Communication paths NA-1, NA-2, NA-3, NB-1, NB-2, NB-3, NB-4 nodes NC-1, NC-2, NC-3, NC-4, ND-1, ND-2, ND-3 node

Claims (4)

It is equipped with a plurality of wireless communication terminals having a narrow band wireless communication function and a wide band wireless communication function in which the frequency bands used are different from each other.
As the range of wireless communication, an entire area and a plurality of cell areas smaller than the total area and included in the total area are formed.
Each said cell area contains at least one said wireless communication terminal.
Each wireless communication terminal, as the range of the wireless communication, selecting said whole region, one of the cell region to which it belongs,
When each wireless communication terminal selects the entire area for wireless communication, the narrowband wireless communication function is used.
When each wireless communication terminal selects the cell area to which it belongs and performs wireless communication, the wideband wireless communication function is used.
When the respective radio communication terminal transmits data, status for the destination of the data is the entire region preferentially selected in case a predetermined condition is satisfied, the row physician wireless communication by the narrow-band radio communication function ,
Each of the wireless communication terminals has a function of acquiring information regarding the position or distance of each of the other wireless communication terminals.
When each wireless communication terminal transmits data,
If the destination terminal of the data does not exist in the same cell area as the own terminal, or if the distance to the destination terminal is greater than or equal to a predetermined value, the entire area is selected and wireless communication is performed by the narrow band wireless communication function. To start,
When the destination terminal of the data exists in the same cell area as the own terminal, or when the distance to the destination terminal is less than the predetermined value, the cell area to which the data destination belongs is selected and the wideband wireless communication function is performed. To start wireless communication,
A wireless communication system for vehicles characterized by this. It is equipped with a plurality of wireless communication terminals having a narrow band wireless communication function and a wide band wireless communication function in which the frequency bands used are different from each other.
Each wireless communication terminal selects either an entire area or a plurality of cell areas smaller than the overall area and included in the entire area as the range of wireless communication.
When each wireless communication terminal selects the entire area for wireless communication, the narrowband wireless communication function is used.
When each wireless communication terminal selects the cell area for wireless communication, the wideband wireless communication function is used.
When each of the wireless communication terminals transmits data, if the situation regarding the destination of the data satisfies a predetermined condition, the entire area is preferentially selected, and wireless communication is performed by the narrow band wireless communication function.
Priorities are set for each of the wireless communication terminals.
When the wireless communication terminal other than the destination receives the wireless signal transmitted by the narrow band wireless communication function, the wireless communication terminal having a high priority receives the data of the received wireless signal to the destination wireless communication. Sending to the terminal by the wideband wireless communication function or the narrowband wireless communication function.
Car dual wireless communication system, characterized in that. It is equipped with a plurality of wireless communication terminals having a narrow band wireless communication function and a wide band wireless communication function in which the frequency bands used are different from each other.
Each wireless communication terminal selects either an entire area or a plurality of cell areas smaller than the overall area and included in the entire area as the range of wireless communication.
When each wireless communication terminal selects the entire area for wireless communication, the narrowband wireless communication function is used.
When each wireless communication terminal selects the cell area for wireless communication, the wideband wireless communication function is used.
When each of the wireless communication terminals transmits data, if the situation regarding the destination of the data satisfies a predetermined condition, the entire area is preferentially selected, and wireless communication is performed by the narrow band wireless communication function.
When a plurality of wireless communication terminals other than the destination receive the wireless signal transmitted by the narrow band wireless communication function, only the wireless communication terminal that has started transmission first receives the data of the received wireless signal. Sending data to the corresponding destination wireless communication terminal by the wideband wireless communication function or the narrowband wireless communication function.
Car dual wireless communication system, characterized in that. Each of the plurality of wireless communication terminals is arranged in a vehicle structure or a space adjacent thereto.
The entire area is an area corresponding to the range of the vehicle structure.
The vehicle wireless communication system according to any one of claims 1 to 3.

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