JP2018195879A - Radio communication system for vehicle - Google Patents

Abstract

To restrain cost increase, while circumventing increase of communication delay time and traffic.SOLUTION: A radio communication network is constituted of multiple radio communication terminals distributed in the vehicle structure. A network is constituted by combining a basic node which can change over a range capable of radiocommunication between a narrow range of vehicle structure, and the range of the whole vehicle structure, and an auxiliary node capable of only radiocommunication in a narrow range. The basic node selects a narrow range in normal communication, and when transmission delay of signal may exceed an acceptable range, changes over to a broad range. Configuration and function can be optimized by combination of multiple basic nodes and multiple auxiliary nodes. In a region where multiple cells adjoining each other overlap, one or more basic node is arranged.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a vehicle radio communication system.

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

  Further, when configuring a mesh network, a communication path can be secured by selectively using various paths from one source node to another destination node. Therefore, even if a route that cannot be used due to a failure or the like occurs, it can be continuously connected by switching to another route. For example, as shown in Patent Document 1, if dynamic routing is used, a route used for communication can be changed on a mesh network each time, so that it is affected by a failure or the like. It becomes difficult.

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

  Patent Document 2 discloses a technique for quickly transmitting data to a target node in a communication system including a plurality of nodes.

JP 2010-147848 A JP 2014-225859 A

  For example, a case where a large number of wireless communication terminals having a relatively narrow communication range are arranged in various positions and the mesh wireless communication network is simply configured by using these wireless communication terminals. Suppose. In such a case, when data is transmitted from a wireless communication terminal of one transmission source node to a wireless communication terminal of another destination node, communication is performed sequentially or in parallel between various terminals. However, it is necessary to perform communication processing for searching for a path that can be used for communication from the transmission source to the transmission destination. Furthermore, even after a route that can be used for communication is determined, this data passes through various relay points before the data arrives from the transmission source to the transmission destination. Therefore, the traffic passing on this wireless communication network increases. In addition, as the number of data relays from the transmission source to the transmission destination increases, the communication delay time also increases.

  The above problems of increased traffic and increased communication delay time become more prominent as the number of communicable counterparts of each wireless communication terminal increases. That is, when the range in which each wireless communication terminal can communicate is narrowed and the number of wireless communication terminals arranged in a narrow area is increased, the efficiency of the entire communication system is lowered.

  Accordingly, in such a case, a clustering method is generally used. That is, a large number of terminals are divided into a plurality of groups (clusters), and the network is configured such that the plurality of groups are connected to each other. Thereby, the traffic generated when searching for a communicable route can be reduced. However, if each terminal does not grasp the information about the network outside the group to which the terminal belongs, the traffic cannot be reduced efficiently. In addition, the problem of communication delay time cannot be solved.

  Therefore, for example, it is conceivable to use a technique as disclosed in Patent Document 1. That is, by switching the wireless communication range of each terminal from a narrow area to a wide area, it is possible to reduce the number of communications associated with the route search and the number of relays of data to be transmitted. As a result, communication delay time can be reduced, and traffic can be reduced. However, in order to employ the technology of Patent Document 1, it is necessary for all wireless communication terminals to have both narrow-area wireless communication and wide-area wireless communication functions, which greatly increases the cost of the entire system. Unavoidable. In addition, a device for managing the operation of the entire system is required.

  Further, in the case of a wireless communication system configured by applying the above clustering, traffic of the entire system increases. In addition, since the load of communication processing of each terminal and the load of the wireless communication line increase with the increase of traffic, the delay time of communication increases.

  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 are arranged at various locations in a limited narrow space on the vehicle. there is a possibility. Furthermore, it is necessary to consider beforehand that radio waves of wireless communication performed on the host vehicle do not affect wireless communication in other vehicles or various wireless communication other than the vehicle. Therefore, it is desirable to suppress the output power of the radio wave transmitted by each wireless communication terminal on the vehicle and perform narrow area wireless communication in a very narrow range. However, when the communicable range of each wireless communication terminal is limited to a very narrow range, as described above, an increase in traffic and an increase in communication delay time become major problems. Furthermore, it is necessary to suppress an increase in the cost of the communication system.

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

In order to achieve the above-described object, the vehicle wireless communication system according to the present invention is characterized by the following (1) to (5).
(1) It is composed of a plurality of communication nodes having a wireless communication function,
As the plurality of communication nodes, a first communication node and a second communication node are provided,
The first communication node includes a first wireless communication unit capable of switching a wireless communicable range to at least one of a narrow area and a wide area wider than the narrow area,
The second communication node includes a second wireless communication unit whose wireless communication range is limited to the narrow area;
A switching control unit that switches the wireless communication range in the first wireless communication unit of the first communication node to the narrow area or the wide area according to a predetermined condition;
A vehicular wireless communication system.

(2) The switching control unit switches the wireless communication range of the first communication node to the narrow area or the wide area according to the size of the transmission delay time of the transmission target signal.
The vehicle radio communication system according to (1) above, wherein

(3) The switching control unit is configured to reflect at least one of the priority assigned to each signal to be transmitted and the priority assigned to the transmission source of the signal to be transmitted. Switch wireless communication range to the narrow area or the wide area,
The vehicle radio communication system according to (1) above, wherein

(4) The plurality of communication nodes include two or more first communication nodes and two or more second communication nodes.
The vehicle radio communication system according to (1) above, wherein

(5) Each of the plurality of communication nodes is disposed in a vehicle structure or a space adjacent thereto,
The wide area is an area corresponding to the range of the vehicle structure.
The vehicle radio communication system according to any one of the above (1) to (4).

  According to the vehicular radio communication system having the configuration (1), by using the first communication node, two types of a relatively wide range and a narrow range can be properly used according to the situation as the radio communicable region. Is possible. In addition, since the second communication node, which is limited to only a narrow range where wireless communication is possible, and the first communication node are used in combination, an increase in the cost of the entire system can be suppressed. When the first communication node selects a relatively wide range as a wireless communicable area, communication when searching for a route from the data transmission source to the transmission destination, and data transfer from the transmission source to the transmission destination The total traffic generated by the communication can be reduced, and the communication delay time can be shortened.

  According to the vehicular radio communication system having the configuration (2), for example, when the actual transmission delay time of the signal to be transmitted exceeds a predetermined threshold, the radio communication range of the first communication node is increased. It is possible to switch to a wide area. By this switching, the transmission delay time can be shortened so as to be within the threshold.

  According to the vehicular radio communication system having the configuration (3) above, for example, when transmitting a high priority signal or transmitting a signal transmitted from a high priority transmission source, the radio of the first communication node The communicable range can be switched to the wide area. By this switching, the signal transmission delay time can be shortened. That is, a signal having a high priority and a signal having a high priority can be handled with priority so that the transmission delay time does not increase.

  According to the vehicular wireless communication system having the configuration (4), transmission and reception can be performed between the plurality of first communication nodes. Therefore, even when communicating in a wide range. High reliability can be ensured. In addition, a second communication node is connected to each of the plurality of first communication nodes, and wireless communication limited to a relatively narrow range can be performed between the first communication node and the second communication node.

  According to the vehicular radio communication system having the configuration (5) above, even when the first communication node performs radio communication in the wide area, the radio wave leaking to the space outside the own vehicle is another radio communication. Can be controlled.

  According to the vehicular 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, by using the first communication node, it is possible to use two types of areas that can be wirelessly communicated, that is, a relatively wide range and a narrow range, according to the situation. In addition, since the second communication node, which is limited to only a narrow range where wireless communication is possible, and the first communication node are used in combination, an increase in the cost of the entire system can be suppressed. When the first communication node selects a relatively wide range as a wireless communicable area, communication when searching for a route from the data transmission source to the transmission destination, and data transfer from the transmission source to the transmission destination The total traffic generated by the communication can be reduced, and the communication delay time can be shortened.

  The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

FIG. 1 is a plan view showing a specific example regarding the arrangement of a plurality of wireless communication terminals and the configuration of a wireless communication line included in a vehicle wireless communication system according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a configuration example of a network in the vehicle radio communication system according to the embodiment of the present invention. FIG. 3 is a block diagram illustrating 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 illustrating an example of transmission processing in the wireless communication terminal at each node position. FIG. 5 is a flowchart illustrating an example of reception processing in the wireless communication terminal at each node position. FIG. 6 is a flowchart showing a modification of the reception process in the wireless communication terminal at each node position. FIG. 7 is a schematic diagram illustrating a configuration example of a communication network including a plurality of nodes performing wireless communication.

  Specific embodiments relating to the present invention will be described below with reference to the drawings.

<Specific examples of the arrangement of terminals and the configuration of wireless communication lines>
A specific example of the arrangement of a plurality of wireless communication terminals and the configuration of a wireless communication line included in the vehicular wireless communication system according to the embodiment of the present invention is shown in FIG.

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

  In the example shown in FIG. 1, a large number of wireless communication terminals 10-1, 10-3,. Is installed. The position and total number of each of these wireless communication terminals 10-1 to 10-17 are changed as necessary. Moreover, you may install in the structure added separately to a vehicle structure.

  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, various loads, etc. Is provided in order to enable transmission / reception of signals by wireless communication.

  In the example shown in FIG. 1, by using the wireless communication functions of the wireless communication terminals 10-1 to 10-17, wireless communication paths C01, C03, C04,. can do. In the example shown in FIG. 1, a plurality of small cell areas ARS1, ARS2, and ARS3 that are sufficiently smaller than that are formed in the space inside the entire area ARL.

  In addition, the small cell regions ARS1 and ARS2 adjacent to each other are formed in a state where the portions overlap each other. Further, the small cell regions ARS2 and ARS3 adjacent to each other are also formed in a state where the portions overlap each other. Radio communication terminals 10-3, 10-4, and 10-8 are arranged inside the small cell area ARS1. Inside the small cell area ARS2, radio communication terminals 10-8 and 10-11 are arranged. Inside the small cell area ARS3, wireless communication terminals 10-12, 10-13, and 10-15 are arranged.

  Although not shown in FIG. 1, there are at least two types of radio communication terminals 10-1 to 10-17. That is, there are a wireless communication terminal 10 configured as a basic node NB and a wireless communication terminal 10 configured as an auxiliary node NA. The basic node NB is a terminal that supports both wide-area wireless communication and narrow-area wireless communication, and the auxiliary node NA is a terminal that supports only narrow-area wireless communication. Details of this will be described later.

  Note that “wide area” in the present embodiment means that wireless communication is possible for all areas within the entire area ARL, and wireless communication is not performed in a wider area. In other words, in the vehicular wireless communication system of the present embodiment, for example, transmission output is limited in advance so that radio waves reach only the vehicle structure including the vehicle body and side mirrors of the host vehicle. It should be noted that the area included in the “wide area” may be only the space in the passenger compartment or the space in the luggage room. For example, in FIG. 1, the “narrow area” in the present embodiment represents a range sufficiently smaller than the “wide area”, and corresponds to, for example, any of the small cell areas ARS1, ARS2, and ARS3 shown in FIG. It is the size to do.

  That is, it is assumed that the “wide area” in the present embodiment has a size of about 3 meters, for example, and the “narrow area” has a size of about 1 meter, for example. Thereby, it can suppress that the electromagnetic wave which the radio | wireless communication system for vehicles in the own vehicle has influenced the radio | wireless communication in another vehicle, and various other radio | wireless communications outside the own vehicle.

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

  In the network shown in FIG. 2, four different small cell areas AR-CA, AR-CB, AR-CC, and AR-CD are formed. Here, two small cell areas AR-CB and AR-CD adjacent to each other are partially overlapped. Similarly, two small cell areas AR-CB and AR-CA adjacent to each other are partially overlapped. Also, two small cell areas AR-CC and AR-CA adjacent to each other are in a partially overlapping state.

  A basic node NB-C is arranged in a region where two adjacent small cell regions AR-CC and AR-CA overlap. Further, the basic node NB-B is arranged in a region where two adjacent small cell regions AR-CB and AR-CA overlap. In addition, a basic node NB-D is arranged in an area where two adjacent small cell areas AR-CB and AR-CD overlap.

  In addition to the basic nodes NB-B and NB-C, auxiliary nodes NA-A1 and NA-A2 are arranged inside the small cell area AR-CA. In addition to the basic nodes NB-B and NB-D, an auxiliary node NA-B3 is arranged inside the small cell area AR-CB. In addition to the basic node NB-C, auxiliary nodes NA-C2, NA-C3, and NA-C4 are arranged inside the small cell area AR-CC. In addition to the basic node NB-D, auxiliary nodes NA-D2, NA-D3, and NA-D4 are arranged inside the small cell area AR-CD.

  That is, in each of the four small cell regions AR-CA, AR-CB, AR-CC, and AR-CD, at least one basic node NB is provided therein, and one or more additional ones are provided. An auxiliary node NA is provided. Further, each basic node NB-B, NB-C, and NB-D includes the same function as that of the auxiliary node NA, and therefore can perform the same operation as that of the auxiliary node NA depending on the situation.

  Therefore, the basic node NB-B can operate as the fourth auxiliary node NA (A4) in the small cell area AR-CA, or as the first auxiliary node NA (B1) in the small cell area AR-CB. It can also work. Similarly, the basic node NB-C can operate as the third auxiliary node NA (A3) in the small cell area AR-CA, or the first auxiliary node NA (C1) in the small cell area AR-CC. Can also operate as. The basic node NB-D can also operate as the second auxiliary node NA (B2) in the small cell area AR-CB and the first auxiliary node NA (D1) in the small cell area AR-CD.

  Inside the small cell area AR-CA shown in FIG. 2, between the first auxiliary node NA-A1 and the basic nodes NB-B, NB-C and auxiliary node NA-A2, wireless communication is performed. Connected by route. Further, inside the small cell area AR-CB, the basic node NB-B, the basic node NB-D, and the third auxiliary node NA-B3 are respectively connected by a wireless communication path. Further, inside the small cell area AR-CC, there is a wireless connection between the auxiliary node NA-C2, the basic node NB-C, the third auxiliary node NA-C3, and the fourth auxiliary node NA-C4. Connected via communication path. Further, inside the small cell area AR-CD, wireless communication is performed between the auxiliary node NA-D2 and the basic node NB-D, the third auxiliary node NA-D3, and the fourth auxiliary node NA-D4. It is connected by the route.

  Therefore, for example, when the auxiliary node NA-C3 shown in FIG. 2 communicates with the auxiliary node NA-C4 in the same small cell area AR-CC, the auxiliary node NA-C2 relays the communication. The communication path between the auxiliary nodes NA-C3 and NA-C4 can be secured.

  For example, even when the auxiliary node NA-C3 communicates with the auxiliary node NA-A1 in another small cell area AR-CA, the auxiliary node NA-C3 straddles the two small cell areas AR-CA and AR-CC. Since the basic node NB-C is arranged at the position, a communication path between the auxiliary nodes NA-C3 and NA-A1 can be secured by relaying communication at the basic node NB-C.

<Network design method>
When actually designing a communication network as shown in FIG. 2, for example, a large number of wireless communication terminals 10-1 to 10-17 shown in FIG. 1 are divided into a plurality of groups, For example, it corresponds to one of the small cell areas AR-CA, AR-CB, AR-CC, and AR-CD shown in FIG. And a network is comprised so that several small cell area | region AR-CA, AR-CB, AR-CC, and AR-CD adjacent to each other like the example shown in FIG. 2 may be connected. The connection relationship between a plurality of small cell areas is determined in advance. Further, a group is created so as to include one or more nodes straddling a plurality of small cell areas. Then, for each of the small cell areas AR-CA, AR-CB, AR-CC, and AR-CD, route design is performed only within the cell. The route design in the cell can be automatically processed by using, for example, a “dynamic routing” procedure.

<Example of basic communication operation on the network>
In the communication network shown in FIG. 2, an operation assumed when data is transmitted from the transmission source auxiliary node NA-A1 to the auxiliary node NA-D2 will be described below.

1. In the auxiliary node NA-A1, since the destination is the communication of the auxiliary node NA-D2, it is connected from the small cell area AR-CA which is the own cell to the small cell area AR-CD including the destination via the AR-CB. Check. Here, since the connection between the small cell areas AR-CA, AR-CB, AR-CC, and AR-CD is fixed and determined in advance, for example, 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-CD including the destination node, it is necessary to first send data to the small cell area AR-CB adjacent to the own cell. A communication path to the basic node NB-B existing at a position across the small cell areas AR-CA and AR-CB is created. Specifically, triggered by the operation of the auxiliary node NA-A1 as a transmission source, a procedure such as a technique of “dynamic routing” is executed in the small cell area AR-CA. The connection is confirmed and an appropriate route available for communication is automatically created.

3. Each node in the small cell area AR-CA transfers the transmission data output from the auxiliary node NA-A1 to the basic node NB-B according to the path created by the above processing.

4). In the small cell area AR-CB, the same operations as “2.” and “3.” are performed based on the transmission data received by the basic node NB-B by the operation of “3.”. As a result, a route from the basic node NB-B to the basic node NB-D is created in the small cell area AR-CB, and the transmission data of the basic node NB-B is transmitted to the basic node NB-D using this route. Is transferred.

5. In the small cell area AR-CD, the same operation as “4.” is performed based on the transmission data received by the basic node NB-D by the operation of “4.”. As a result, a route from the basic node NB-D to the auxiliary node NA-D2 is created in the small cell area AR-CD, and transmission data of the basic node NB-D is transmitted to the auxiliary node NA-D2 using this route. Is transferred.

  In addition, the process for creating the above-mentioned route in each cell can be performed in advance, and each node can hold information obtained as a result. In that case, when actual transmission data is transferred, the time required to create the above-mentioned route is greatly reduced.

  In a communication network such as that shown in FIG. 2, a large number of nodes can be used as needed, so a variety of paths are selectively used to secure a communication path from the data source to the destination (destination). Is possible. However, since the number of counterpart nodes that can communicate is large, the efficiency when searching for a route or actually transmitting data decreases. In other words, when conducting a route search in a state where the communication route is not fixed, it is necessary to transmit a signal such as a packet to a partner node on a route that cannot actually be used. If it increases, useless traffic increases, the load of communication processing on the network increases, and the signal transmission delay time increases. Even after the communication path is determined, the number of nodes relaying signals on the communication path increases, so that the signal transmission delay time increases.

  In order to suppress the decrease in the efficiency of the network as described above, in the communication network shown in FIG. 2, the entire system is configured by combining a plurality of basic nodes NB and a plurality of auxiliary nodes NA. In addition, special control is performed in this communication network. This will be described in detail later.

<Configuration example of wireless communication terminal>
FIG. 3 shows a configuration example of one wireless communication terminal 10 used by the vehicle wireless communication system according to the embodiment of the present invention. The wireless communication terminal 10 has a function that can be used as the basic node NB. Further, by omitting some functions in the wireless communication terminal 10 shown in FIG. 3, it is possible to change to a configuration corresponding to the auxiliary node NA described above.

  3 includes a wireless communication unit 11, interfaces (I / F) 12a and 12b, a time information generation function unit 13, a cell determination function unit 14, a time information update function unit 15, and a destination determination function unit. 16, a delay measurement unit 17, and a route detection function unit 18.

  The wireless communication unit 11 of the present embodiment includes a wide area communication module 11a and a narrow area communication module 11b. An antenna 19a is connected to the wide area communication module 11a, and an antenna 19b is connected to the narrow area communication module 11b.

  Each of the wide area communication module 11a and the narrow area communication module 11b has a function of transmitting and receiving a radio signal. A major difference between the wide area communication module 11a and the narrow area communication module 11b is, for example, a difference in output power of a radio signal to be transmitted. That is, the radio signal transmission output power in the wide area communication module 11a can be received anywhere in the range of the entire area ARL shown in FIG. Designed. Further, the transmission output power of the radio signal in the narrow area communication module 11b is a range in which radio waves can be received anywhere within any range of the small cell areas ARS1, ARS2, ARS3, etc. shown in FIG. It is designed not to reach radio waves until. Of course, instead of the output power of the radio signal, the communicable range may be adjusted using the difference in modulation method and the antenna directivity, or the communicable range may be adjusted by a combination of these. May be.

  For example, if a function for suppressing the transmission output power is added to the wide area communication module 11a, an operation equivalent to that of the narrow area communication module 11b becomes possible, so the narrow area communication module 11b is not necessarily indispensable. However, since a large number of electrical components are mounted in an automobile, when a large number of communication modules are also mounted, a wide area wireless module 11a and a narrow area communication module 11b are mounted, so that wireless communication over a wide area is possible. Communication and narrow-band wireless communication can be performed simultaneously, improving the communication performance of the entire network.

  It is assumed that the wide area communication module 11a and the narrow area communication module 11b are each configured as a wireless LAN module that conforms to a standard standard.

  The time information generation function unit 13 has a function of generating time information such as the current time. Then, when communication data to be transmitted is generated and this communication data is input from an external device to the time information generation function unit 13 via the interface 12a, the time information indicating the time is displayed as the time information generation function unit 13. Produces.

  The cell discrimination function unit 14 obtains a cell including a corresponding destination node, that is, a destination cell, based on destination information included in communication data to be transmitted. Here, since the nodes included in the group corresponding to each cell are determined in advance, information representing the correspondence between the cells and the nodes can be held as a table, for example. By referring to this table, the cell discrimination function unit 14 can identify the destination cell from the destination information.

The time information update function unit 15 updates the time information indicating the elapsed time from the time of data generation for the communication data received by the wireless communication unit 11 from another node.
The destination discriminating function unit 16 discriminates whether or not the destination cell is the same as its own cell for the communication data received by the wireless communication unit 11 from another node. If the destination cell is the same as the own cell, it is also determined whether or not the destination node and the own node are the same.

  The delay measurement unit 17 measures a communication delay time for communication data received by the wireless communication unit 11 from another node. Actually, the information on the time when the communication data is generated is generated by the time information generation function unit 13 in another node and added to the communication data. The elapsed time until the communication data arrives at the own node can be specified based on information updated by the time information update function unit 15 in the own node. In addition to such elapsed time, the delay measurement unit 17 also calculates a delay time that is expected to occur in the own cell.

  The route detection function unit 18 constructs a communication route in the own cell by, for example, executing a “dynamic routing” procedure, and holds information on the constructed route. When the destination cell receives communication data different from the own cell, the route to the basic node NB in the next cell is calculated for this communication data.

  Note that the time information generation function unit 13, the cell determination function unit 14, the time information update function unit 15, the destination determination function unit 16, the delay measurement unit 17, and the route detection function unit 18 in the wireless communication terminal 10 illustrated in FIG. These functions may be realized by processing of a microcomputer (not shown) built in the wireless communication terminal 10 or may be realized by using dedicated hardware.

  In the case of the wireless communication terminal 10 used as the auxiliary node NA described above, the wide area communication module 11a in the wireless communication unit 11 shown in FIG. 3 is not necessary, and only the narrow area communication module 11b is used. The antenna 19a is also unnecessary.

<Specific example of transmission processing>
FIG. 4 shows an example of transmission processing (Send) of the wireless communication terminal 10 arranged at each node position in the communication network as shown in FIG. The transmission process in FIG. 4 will be described below.

  When communication data is input from a communication data transmission source device (not shown) to the wireless communication terminal 10 of its own node via the interface 12a, the wireless communication terminal 10 recognizes this communication data as new data. (S11). And the time information generation function part 13 produces | generates the information of data generation time with respect to this communication data (S12). The generated data generation time information is added to the corresponding communication data (packet). In the case of communication data transferred from another node, the data generation time information is not changed.

  For new data input via the interface 12a or communication data received from another node, the cell discrimination function unit 14 compares the destination cell with its own cell based on the destination information included in the data (S13). ).

  When the destination cell of the communication data to be processed is another cell different from the own cell, the route detection function unit 18 generates a communication path in the own cell for the communication data (S14). Then, according to this communication path, the communication data is transmitted using the narrow area communication module 11b and transferred to the basic node NB in the own cell (S15).

When the wireless communication terminal 10 of the basic node NB processes communication data addressed to another cell, the communication data is transmitted using the wide area communication module 11a (S16).
On the other hand, when the destination node of the communication data is in the own cell, the route detection function unit 18 generates a communication path in the own cell for the communication data (S17). Then, according to this communication path, the communication data is transmitted using the narrow area communication module 11b (S18). The communication data transmitted here reaches, for example, the wireless communication terminal 10 of the destination node through a route passing through another node in the same cell.

  That is, when the wireless communication terminal 10 of each node performs the transmission process shown in FIG. 4, the narrow area communication module 11b is used when transferring communication data within the same cell as the transmission source (S15, S18). . When the communication data is transferred to a destination node of a cell different from the transmission source, the wide area communication module 11a is used when the basic node NB performs communication across a plurality of cells (S16).

  Here, for example, in the communication network shown in FIG. 2, the transmission source of the new communication data is the auxiliary node NA-A1 in the small cell area AR-CA, and the destination is the auxiliary node NA in the small cell area AR-CD. Suppose that -D2. In this case, when the transmission process of FIG. 4 is executed, the basic node NB-B across multiple nodes uses the wide area communication module 11a when transferring data, so the small cell that is the destination cell from the small cell area AR-CA. It can be transmitted directly to the cell area AR-CD. Therefore, communication in the small cell area AR-CB between the transmission source node and the destination node can be omitted. Therefore, the number of relays of communication data can be reduced for the route from the auxiliary node NA-A1 to the auxiliary node NA-D2, and the communication delay time from the transmission source node to the destination node can be reduced. Moreover, the traffic of the whole network can also be reduced.

  On the other hand, if the source node and the destination node are in the same cell, each node communicates only within the cell and uses only the narrow area communication module 11b (S18), so that extra traffic is not available. Will not be transmitted to the next cell. Therefore, the traffic of the entire network can be reduced.

  In practice, the wide area communication module 11a can be used to deliver radio waves from the position of each basic node NB anywhere in the entire area ARL shown in FIG. 1, that is, the entire vehicle structure of the host vehicle. Therefore, the communication delay time can be shortened.

<Specific example of reception processing>
FIG. 5 shows an example of reception processing (Recv) of the wireless communication terminal 10 arranged at each node position in the communication network as shown in FIG. That is, when the wireless communication unit 11 (wide area communication module 11a or narrow area communication module 11b) in each wireless communication terminal 10 receives wireless signal communication data from another node, the process of FIG. 5 is executed. The reception process in FIG. 5 will be described below.

  The time information update function unit 15 performs time information update processing on the communication data received by the wireless communication unit 11 from another node (S21). That is, the elapsed time from the time when the communication data is generated is specified based on the received time, and this time information is added to the communication data.

  The destination discriminating function unit 16 acquires the destination information from the communication data received by the wireless communication unit 11 from another node, and compares the destination with its own node (S22). If the result of the comparison is that the node matches the destination, the destination discrimination function unit 16 outputs the received communication data to an external device (not shown) via the interface 12b (S23). End the process.

As a result of the comparison, if the destination of the received data is not the own node, the delay measurement unit 17 calculates the delay time of this communication data (S24). For example, the delay time Tdx is calculated by the following equation.
Tdx = Tp + 2 × Tc + Tα (1)
Tp: Elapsed time from data generation to present Tc: Delay time corresponding to communication in one section in cell Tα: Constant corresponding to time required for processing such as switching other than communication and margin

  The elapsed time Tp can be acquired from the communication data as the time information updated by the time information update function unit 15 in S21. Further, when the destination node is other than the own cell, at least one more communication is required in the own cell. Therefore, in the above equation (1), a time twice as long as the delay time Tc is considered. The required time Tα includes the time required for switching the selection of the wide area communication module 11a and the narrow area communication module 11b. Appropriate path control becomes possible by considering in advance the influence of the delay time (Tc × 2) that is expected to occur in the same cell in addition to the elapsed time Tp as shown in the above equation (1). . For example, it is possible to prevent switching to wide area communication by returning to the position of the basic node NB after passing a useless relay route in the same cell.

  The delay measurement unit 17 compares the delay time Tdx calculated by the above equation (1) with a predetermined threshold Tdr of allowable delay time (S25). Here, as a representative example of the threshold value Tdr of the allowable delay time, it is assumed that a time of about 20 to 50 [msec] is adopted.

  As a result of the comparison, when the delay time Tdx satisfies the condition within the allowable delay time, the narrow area communication module 11b is selected as a communication condition when the communication data currently processed by the terminal is transferred to the next node. Select (S26).

  As a result of the comparison, when the delay time Tdx exceeds the allowable delay time, the cell determination function unit 14 determines whether or not the destination node of the communication data is in its own cell (S27). If the destination node is within the own cell, the narrow area communication module 11b is selected as a communication condition when the communication data currently being processed by the own terminal is transferred to the next node (S28).

  On the other hand, if the destination node is not within the own cell, the cell discrimination function unit 14 identifies whether or not the own terminal is the basic node NB (S29). When the own terminal is the basic node NB, the cell discrimination function unit 14 identifies the cell to which the destination node belongs as the destination cell (S30). Then, the wide area communication module 11a is selected as a communication condition when the communication data currently being processed by the terminal is transferred to the next node (S31).

  If the own terminal is not the basic node NB, the route detection function unit 18 identifies whether route information to the basic node NB in the own cell exists (S32). If the route information exists, the communication data being processed by the own terminal is transferred to the basic node NB in the own cell according to the route information. At the time of this transfer, the narrow area communication module 11b is used (S33).

  In addition, when there is no route information to the basic node NB in the own cell, the route detection function unit 18 executes a procedure of “dynamic routing”, for example, thereby performing a route to the basic node NB in the own cell. Information is generated (S34). Then, according to this route information, the communication data currently being processed by the own terminal is transferred to the basic node NB in the own cell. At the time of this transfer, the narrow area communication module 11b is used (S35).

  When the wireless communication terminal 10 corresponding to each node in the communication network executes the reception process (Recv) shown in FIG. 5, the delay time of the communication data to be processed is expected to exceed the allowable time Special control is performed (“NO” in S25). That is, the basic node NB arranged at a position across a plurality of cells selects the wide area communication module 11a and switches the communication range from the narrow area to the wide area (S31). By this switching, the number of relays from the transmission source to the destination of communication data can be reduced, and the traffic of the entire network can also be reduced. Further, by limiting the conditions for using wide-area communication to only a specific situation, it is possible to minimize the influence of the radio wave transmitted by the basic node NB on the wireless communication outside the host vehicle.

<Modification of reception processing>
FIG. 6 shows a modification (Recv_2) of the reception process of the radio communication terminal 10 arranged at each node position in the communication network as shown in FIG. That is, when the wireless communication unit 11 (wide-area communication module 11a or narrow-area communication module 11b) in each wireless communication terminal 10 receives wireless signal communication data from another node, the processing in FIG. 6 is executed. The reception process in FIG. 6 will be described below.

  In this modification, in communication data transmitted by the wireless communication terminal 10, priority information indicating high / low priority of the transmission source, priority information indicating high / low priority for each data, It is assumed that the situation can be included.

  When the wireless communication unit 11 receives communication data from another node as a wireless signal, the time information update function unit 15 updates the time information of the communication data as in S21 of FIG. 5 (S41).

  If the destination of the received communication data is not the own node and the destination node cell is different from the own cell, the cell discrimination function unit 14 determines whether the own node is the basic node NB (S44). If the own node is the basic node NB, whether or not the priority of the transmission source is “high” is identified in S45, and whether or not the priority of the transmission data is “high” is identified in S46.

  When the priority of the transmission source is “high” or the priority of the transmission data is “high”, the process proceeds to S47. In other cases, the delay time is calculated in the same manner as S24 and S25 in FIG. 5, and it is identified whether or not this delay time is within the allowable time. If the delay time is within the allowable time, the use of the narrow area communication module 11b is selected in S51.

  Further, when the priority of the transmission source is “high”, the priority of the transmission data is “high”, or when the delay time exceeds the allowable time, as in S30 and S31 of FIG. The destination cell is determined and the use of the wide area communication module 11a is selected.

  That is, when the reception process shown in FIG. 6 is executed, not only when the delay time exceeds the allowable time, but also data transmitted by a special transmission source assigned with a high priority, or a high priority is assigned. The basic node NB also automatically selects wide area wireless communication when transmitting the special data.

  Various types of electrical components are mounted on the vehicle, and there are various types of signals transmitted by communication on the vehicle. Therefore, signal transmission delays and control delays may have a significant effect, and even if the delay time increases, there may be no significant effect. When the reception process shown in FIG. 6 is executed, the delay time does not exceed the allowable time for specific electrical equipment having a large influence of the delay time or specific data having a large influence of the delay time. However, the delay time can be further reduced. Therefore, for example, it is possible to make the allowable time relatively large in accordance with the electrical component in which the influence of the delay time is relatively small.

<Description of "Dynamic Routing">
FIG. 7 shows a configuration example of a communication network including a plurality of nodes that perform wireless communication. In FIG. 7, it is assumed that there are nodes NA, NB, NS, NC, and ND that perform wireless communication in one cell.

  The nodes N-A and N-B adjacent to each other are connected by one wireless communication, the nodes N-B and NS are connected by one wireless communication, and the nodes NS and N-C are one The nodes N-C and N-D are connected by one wireless communication. However, in an initial state, each node does not grasp a path that can be used for communication with other adjacent nodes.

  Here, assuming a situation where data is transmitted with the node NS shown in FIG. 7 as the communication source and the node ND as the destination, a typical procedure when “dynamic routing” is executed will be described below. To do.

1. First, as “communication source node NS, destination node ND, no relay node information”, the communication source node NS broadcasts (Broad Cast: BC) a route request packet (Route-Request packet: RREQ). ) Send information as a radio signal. This information is received by each of the nodes N-B and N-C at adjacent positions where wireless communication is possible with the communication source node NS. The radio waves do not reach other nodes due to distance.

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

3. Since the destination of the RREQ information received from the node NB is not the own node, the node NA stores the information on the own node in the relay node information and transmits the RREQ information by broadcast. Further, since the destination of the RREQ information received from the node NC is the node ND, the node ND is based on the information of the communication source node and the relay node information, and thus the nodes NS, NC, N -It understands that it communicates by the path | route which goes through D in order.

4). The node NB receives the RREQ information from the node NA, but ignores the RREQ information because the node information is included in the relay node information of the RREQ information.

5. The node ND returns a route reply packet (Route-Reply packet: RREP) information including the route information based on the route information determined by the content of the received RREQ information. This reply is transmitted toward the adjacent node NC.

6). The node N-C receives the RREP information from the node ND, and transmits the RREP information to the node NS using the information included therein.
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, along this route, the data with the destination ND is transmitted toward the adjacent node NC.
8). The node N-C relays the data received from the node NS and transfers it to the destination node N-D.

  Through 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, a necessary route can be ensured by performing the above procedure again from the beginning.

<Possibility of system modification>
In the example shown in FIG. 1, it is assumed that the wide communication range in each basic node NB is the entire area ARL substantially corresponding to the vehicle structure of the automobile. The region may be formed so as to include only the indoor space or the luggage room space. Moreover, in order to adjust each range of a wide area and a narrow area, you may utilize a directional antenna, for example.

  In the reception process shown in FIG. 5, the delay time is calculated in S24 and then the wide area communication module 11a is selected in S31. However, as necessary, immediately when a communication request is generated. Communication of the wide area communication module 11a may be activated. In that case, if the threshold value Tdr of the allowable delay time to be compared in step S25 is set to “0”, the delay time always exceeds the allowable time regardless of the result of step S24. Can be switched.

  In the above-described embodiment, it is assumed that “dynamic routing”, which is a general technique, is employed when determining a communication path within a cell, but other methods may be used. For example, it is conceivable to apply the communication method disclosed in Patent Document 2.

  In the above-described embodiment, the case where the transmission target data is a single data has been described. However, various situations are assumed in an actual communication system. For example, a plurality of communication requests may occur almost simultaneously in the same cell. In such a case, if the destination cells are the same, the communication efficiency can be improved by collectively processing a plurality of communication requests.

  For example, in the communication network shown in FIG. 2, the communication request and communication of the auxiliary node NA-D3 in the small cell area AR-CA, the communication source is the auxiliary node NA-A2, and the destination is the small cell area AR-CD. A case is assumed where a communication request of the auxiliary node NA-A1 at the origin and the auxiliary node NA-D4 in the small cell area AR-CD is generated. In this case, it is conceivable that data of two communication requests are combined into one set and transmitted from the basic node NB-B of the communication source cell to the basic node NB-D of the destination cell. In this case, when data received by the basic node NB-D is transferred to each of the auxiliary nodes NA-D2 and NA-D3 in the destination cell, narrow-area communication is performed using the narrow-area communication module 11b.

  In the above-described embodiment, it is assumed that the nodes arranged in each cell are associated with a predetermined group and fixed, but may be changed as necessary. For example, at the time of starting the system, it is possible to automatically check the terminals in the cell possessed by each basic node and determine each auxiliary node belonging to the same cell. Specifically, each basic node transmits a predetermined signal by broadcast when the system is activated. Since the auxiliary node that has received the broadcast signal belongs to the same cell as the basic node of the transmission source, the auxiliary node replies about the reception of the broadcast to the basic node of the transmission source. The basic node aggregates information received from each auxiliary node and confirms terminals in its own network (in a cell). Thereafter, terminal information belonging to the cell of each basic node is exchanged between the plurality of basic nodes, and data indicating which cell each terminal belongs to is configured for the entire system.

  As described above, in the vehicular wireless communication system according to each embodiment of the present invention, when a communication delay exceeding the allowable range occurs, the communication range in the basic node NB is switched to a wide area to change the communication path. Since it can be changed, the delay time can be shortened and maintained within an allowable range. In addition, since the entire system is configured by combining the basic node NB capable of switching between a wide communication area and a narrow communication area and the auxiliary node NA capable of communication only in a narrow area, the total number of wireless terminals used is large. Even when the system is configured, an increase in cost can be suppressed. In addition, when communicating between a plurality of basic nodes NB, by collectively processing a plurality of communication requests of the same destination cell, the number of communication across a plurality of cells can be reduced, and an increase in traffic can be suppressed. .

Here, the features of the above-described embodiments of the vehicle wireless communication system according to the present invention are summarized and listed in the following [1] to [5], respectively.
[1] A plurality of communication nodes having a wireless communication function,
As the plurality of communication nodes, a first communication node and a second communication node are provided,
The first communication node (basic node NB) includes a first wireless communication unit (wireless communication unit 11) capable of switching a wireless communicable range to at least one of a narrow area and a wide area wider than the narrow area. Including
The second communication node (auxiliary node NA) includes a second wireless communication unit (narrow band communication module 11b) in which a range in which wireless communication is possible is limited to the narrow area,
A switching control unit (cell discriminating function unit 14, S13 to S16) that switches a radio communicable range in the first radio communication unit of the first communication node to the narrow area or the wide area according to a predetermined condition. , S29 to S31),
A vehicular wireless communication system.

[2] The switching control unit switches the wireless communication range of the first communication node to the narrow area or the wide area according to the transmission delay time of the transmission target signal (S24, S25, S31: See FIG. 5),
The vehicular radio communication system according to [1] above.

[3] The switching control unit is configured to reflect at least one of the priority assigned to each signal to be transmitted and the priority assigned to the transmission source of the signal to be transmitted. Switching the wireless communication range to the narrow area or the wide area (S45 to S51: see FIG. 6),
The vehicular radio communication system according to [1] above.

[4] The plurality of communication nodes include two or more first communication nodes and two or more second communication nodes (see FIG. 2).
The vehicular radio communication system according to [1] above.

[5] Each of the plurality of communication nodes is arranged in a vehicle structure or a space adjacent thereto,
The wide range is a region corresponding to the range of the vehicle structure (entire region ARL) (see FIG. 1).
The vehicle radio communication system according to any one of the above [1] to [4].

10, 10-1 to 10-17 Wireless communication terminal 11 Wireless communication unit 11a Wide area communication module 11b Narrow area communication module 12a, 12b Interface 13 Time information generation function section 14 Cell determination function section 15 Time information update function section 16 Destination determination function Unit 17 Delay measurement unit 18 Route detection function unit 19a, 19b Antenna AR-CA, AR-CB, AR-CC, AR-CD Small cell area ARL Whole 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 path NB-B, NB-C, NB-D Basic nodes NA-A1, NA-A2, NA-B3 Auxiliary Node NA-C2, NA-C3, NA -C4 auxiliary node NA-D2, NA-D3, NA-D4 auxiliary node

Claims (5)

Consists of a plurality of communication nodes having a wireless communication function,
As the plurality of communication nodes, a first communication node and a second communication node are provided,
The first communication node includes a first wireless communication unit capable of switching a wireless communicable range to at least one of a narrow area and a wide area wider than the narrow area,
The second communication node includes a second wireless communication unit whose wireless communication range is limited to the narrow area;
A switching control unit that switches the wireless communication range in the first wireless communication unit of the first communication node to the narrow area or the wide area according to a predetermined condition;
A vehicular wireless communication system. The switching control unit switches the wireless communication range of the first communication node to the narrow area or the wide area according to the size of the transmission delay time of the transmission target signal.
The vehicle wireless communication system according to claim 1. The switching control unit is capable of wireless communication of the first communication node so as to reflect at least one of a priority assigned to each signal to be transmitted and a priority assigned to a transmission source of the signal to be transmitted. Switching the range to the narrow area or the wide area,
The vehicle wireless communication system according to claim 1. Including the two or more first communication nodes and the two or more second communication nodes as the plurality of communication nodes;
The vehicle wireless communication system according to claim 1. Each of the plurality of communication nodes is disposed in a vehicle structure or a space adjacent thereto,
The wide area is an area corresponding to the range of the vehicle structure.
The vehicular radio communication system according to any one of claims 1 to 4, wherein the vehicular radio communication system is characterized.

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