JP2013062576A - Communication system, communication node, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence by noise in communication between communication nodes.SOLUTION: A communication system includes a first communication node and a plurality of second communication nodes for performing communication via the first communication node. The first communication node includes: a plurality of communication modules for modulating by different modulation schemes; a modulation scheme determination unit for determining a modulation scheme set to a destination second communication node on the basis of a message from a second communication node; and a modulation scheme switching unit for switching so that the communication module loaded with the modulation scheme determined by the modulation scheme determination unit among the communication modules transmits the message from the second communication node.

Description

  The present invention relates to a communication system mounted on a vehicle, for example.

  In many cases, a vehicle-mounted network is configured in a vehicle to perform various controls in the vehicle. The in-vehicle network is realized by connecting many electronic control units (ECUs), sensors, actuators, and the like to the LAN. Hereinafter, electronic control units, sensors, actuators, and the like connected to the in-vehicle network are referred to as communication nodes. The communication node is installed at various positions in the vehicle. Communication nodes are connected by communication lines or electric wires.

  With respect to an in-vehicle network system, a gateway device that transmits a band signal related to a communicable frequency band to an information network based on a band signal related to an operating state from each electric device included in the control network is known ( For example, see Patent Document 1).

  The in-vehicle device that has received the band signal from the gateway device modulates and transmits the signal to be transmitted based on the frequency band of the band signal.

JP 2004-266664 A

  In Patent Document 1, the frequency band of noise generated by the operation of an electric device included in the in-vehicle network system is specified by experiment or simulation. Information representing the frequency band of the noise is transmitted to the in-vehicle device on the transmission side. The in-vehicle device on the transmission side modulates and transmits a signal to be transmitted based on information representing the frequency band of the noise. In this way, communication that is not affected by noise is realized.

  However, in the in-vehicle device on the transmission side, noise other than the noise is generated in addition to the noise generated by the in-vehicle device. There is also a situation where communication between in-vehicle devices cannot be performed due to the influence of noise other than the noise.

  The present invention has been made in view of the above points, and an object thereof is to reduce the influence of noise in communication between communication nodes.

This communication system
A communication system having a first communication node and a plurality of second communication nodes that communicate via the first communication node,
The first communication node is
A plurality of communication modules that perform modulation using different modulation schemes;
A modulation scheme identifying unit that identifies a modulation scheme set in the second communication node of the destination based on a message from the second communication node;
A modulation scheme switching unit that switches so as to transmit a message from the second communication node from a communication module in which the modulation scheme identified by the modulation scheme identification unit is mounted among the plurality of communication modules.

This communication node
A communication node that relays messages,
A plurality of communication modules that perform modulation using different modulation schemes;
A modulation scheme identifying unit that identifies the modulation scheme set in the destination communication node based on a message from another communication node;
A modulation scheme switching unit configured to switch the communication module mounted with the modulation scheme identified by the modulation scheme identification unit among the plurality of communication modules to transmit a message from the other communication node.

This communication method is
A communication method in a communication system having a first communication node and a plurality of second communication nodes that perform communication via the first communication node,
The first communication node is
It has multiple communication modules that modulate using different modulation methods,
The first communication node is
A modulation scheme identifying step for identifying a modulation scheme set in the destination second communication node based on a message from the second communication node;
A modulation method switching step for switching so that a message from the second communication node is transmitted from a communication module in which the modulation method specified in the modulation method specifying step is mounted among the plurality of communication modules.

  According to the disclosed embodiment, it is possible to reduce the influence of noise in communication between communication nodes.

It is a figure which shows one Example of a communication system. It is a figure which shows one Example of a communication system. It is a figure which shows one Example of a communication node. It is a figure which shows one Example of a modulation system correspondence table. It is a functional block diagram which shows one Example of a communication node. It is a figure which shows one Example of a communication node. It is a functional block diagram which shows one Example of a communication node. It is a flowchart which shows one Example of operation | movement of a communication node. It is a figure which shows one Example of a modulation system correspondence table. It is a flowchart which shows one Example of operation | movement of a communication node. It is a figure which shows one Example of the message transmitted by the communication node.

Next, the form for implementing this invention is demonstrated, referring drawings based on the following Examples.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

<Example>
<Communication system>
FIG. 1 shows an embodiment of a communication system.

The communication system has a plurality of communication nodes. The plurality of communication nodes include a first communication node 100 and a second communication node 200 _n (n is an integer where n> 0). FIG. 1 shows a case where n = 4 as an example. The value of n can be changed as appropriate. The communication system may include a plurality of first communication nodes. When a plurality of first communication nodes are included, the second communication node 200 _n is preferably connected to the first communication node arranged at the closest position among the plurality of first communication nodes.

The first communication node 100 may be realized by an electronic control unit or the like. The second communication node 200 _n may be realized by an electronic control unit, or may be realized by a sensor, an actuator, or the like.

  Specifically, an in-vehicle network is configured by connecting a plurality of communication nodes to the data bus. The in-vehicle network includes a CAN (Controller Area Network). For CAN, hardware specifications and software specifications are defined by ISO15118. However, recently, in order to improve noise immunity, the hardware specification does not conform to ISO15118, and a noise-resistant modulation scheme may be used. When a noise-resistant modulation scheme is used, a plurality of communications may be converted to another modulation scheme. There may be a case where a plurality of communications converted into different modulation schemes are performed by one communication line. By using one communication line, communication lines can be reduced. The in-vehicle network may include a LIN (Local Interconnect Network). Further, the in-vehicle network may include one that performs communication according to FlexRay (registered trademark).

The first communication node 100 and the second communication nodes 200 ₁ and 200 ₂ are connected by a data bus 150 ₁ . The first communication node 100, the second communication node ₂₀₀ 3, 200 ₄ are connected by a data bus 150 _2.

The first communication node 100 and the second communication node 200 _n are mounted on a moving body such as a vehicle, for example. In this embodiment, as an example, a case where it is mounted on a vehicle will be described.

  FIG. 2 shows an embodiment of a communication system mounted on a vehicle. FIG. 2 shows an example in which the communication system shown in FIG. 1 is mounted on a vehicle.

  Noise generated in the vehicle includes noise generated by the communication node, noise generated by the vehicle-mounted device, noise generated between the wired wire and the communication node, and the wired wire and the vehicle-mounted The noise etc. which generate | occur | produce when the electric wire to a machine runs together are included. The communication node is affected by the noise described above in addition to the noise generated by the in-vehicle device.

  In one embodiment of the communication system, a modulation scheme used for data communication between the communication nodes is selected according to the magnitude of noise assumed to be received by the communication nodes. Specifically, a modulation scheme that is resistant to noise and a modulation scheme that is not so strong against noise but easy to use are included. Here, being easy to use includes low cost.

  In this embodiment, Orthogonal Frequency Division Multiplexing (OFDM) is used as a noise-resistant modulation method, and an amplitude shift keying method (ASK) is used as a modulation method that is not so strong but easy to use. A case where Amplitude Shift Keying) is used will be described. As a modulation method, a modulation method other than OFDM or ASK may be used. Specifically, a phase shift keying method (Phase-Shift Keying), a frequency shift keying (Frequency Shift Keying), etc. may be used. Three or more types of modulation schemes may be used.

In the example shown in FIG. 2, the first communication node 100 is a gateway electronic control unit that functions as a gateway. Second communication _node 2001 is a brake electronic control unit for controlling the brake. Second communication _node 2002 is an engine electronic control unit for controlling the engine. The second communication node 200 ₃ is a meter electronic control unit for controlling the meter. Second communication node 200 ₄ is a door electronic control unit for controlling the opening and closing of the door. An electronic control unit that functions as a gateway, an electronic control unit that has a function of controlling a brake, an electronic control unit that has a function of controlling an engine, an electronic control unit that has a function of controlling a meter, and a function that controls opening and closing of a door A control unit other than the electronic control unit may be included.

The first communication node 100, the second communication node 200 _3, the second communication node 200 ₄ is mounted on the room. It is assumed that communication nodes mounted indoors are less affected by noise. Therefore, data modulated by the ASK method is transmitted and received between the first communication node 100 and the second communication nodes 200 ₃ and 200 ₄ . In other words, the data bus 150 ₂ transmits the data modulated by ASK method.

A second communication node 200 _1, the second communication node 200 ₂ is mounted in the engine room. It is assumed that the communication node mounted in the engine room is greatly affected by noise. Accordingly, the first communication node 100, between the second communication node 200 ₁ and 200 _2, modulated data is transmitted and received by the OFDM scheme. That is, the data bus ₁₅₀ 1 transmits the modulated data by the OFDM scheme.

The positions where the first communication node 100 and the second communication node 200 _n shown in FIG. 2 are mounted are examples, and may differ depending on the vehicle type. For example, sometimes the second communication node 200 ₂ is mounted on the room. If the second communication node 200 ₂ is mounted on the chamber, the first communication node 100, the second communication node 200 _2, between the second communication node 200 ₃ and 200 ₄ are modulated by ASK method Transmitted data is transmitted and received.

<First communication node 100>
The first communication node 100 relays data transmitted and received between the second communication node ₂₀₀ 1 -200 ₄ which is connected to the first communication node 100. The first communication node 100 can communicate with a plurality of modulation schemes.

The first communication node 100 receives the message from the second communication node ₂₀₀ 1 -200 ₄ which is connected to the first communication node 100. The second communication node 200 ₁ -200 ₄ transmits the modulated message in accordance with a modulation method set in the second communication node.

The first communication node 100, based on the message from the second communication node ₂₀₀ 1 -200 _4, detects a modulation scheme that is set to each communication node.

The first communication node 100, the modulation scheme used in accordance with the detected modulation scheme based on the message from the second communication node 200 ₁ -200 _4, communicates with the second communication node Set.

  A message modulated by the modulation method set in the second communication node is transmitted from the second communication node. When the first communication node 100 receives a message from the second communication node, the first communication node 100 demodulates the message according to a modulation scheme set in the second communication node. The first communication node 100 analyzes the demodulated message, for example, by decoding it according to a predetermined protocol, and specifies the second communication node that is the transmission destination of the message. The first communication node 100 modulates and transmits the message by the modulation method set in the second communication node as the transmission destination.

FIG. 3 shows an embodiment of the first communication node 100. FIG. 3 mainly shows the hardware configuration. In the example illustrated in FIG. 3, the first communication node 100 can modulate and demodulate using two types of modulation schemes. Specifically, the communication modules 104 ₁ and 104 ₂ can perform modulation processing and demodulation processing using different modulation schemes. The first communication node 100 may be capable of modulation and demodulation using three or more types of modulation schemes.

  The first communication node 100 includes a microprocessor (MPU: Micro-Processing Unit) 102. The MPU 102 controls the entire first communication node 100.

The first communication node 100 includes communication modules 104 ₁ and 104 ₂ . The communication modules 104 ₁ and 104 ₂ communicate with the communication module of the second communication node 200 _n . For example, communication is performed according to a predetermined communication protocol. The communication modules 104 ₁ and 104 ₂ have different modulation schemes used when transmitting messages to the second communication node 200 _n . More specifically, the communication module 104 ₁ performs modulation by the ASK method, the communication module 104 ₂ performs modulation by OFDM method. The communication module 104 ₁ demodulates the signal modulated processed by ASK method, the communication module 104 ₂ demodulates the modulated processed signals by OFDM method. That is, the communication modules 104 ₁ and 104 ₂ are included in the physical layer of the first communication node 100.

The first communication node 100 includes a storage unit 106. The storage unit 106 stores a program for causing the MPU 102 to function as the first communication node 100. Further, the storage unit 106 stores a modulation scheme correspondence table for storing information indicating the modulation scheme set in the second communication node 200 _n connected to the first communication node 100.

  FIG. 4 shows an example of the modulation scheme correspondence table.

In the modulation scheme correspondence table, information indicating the second communication node 200 _n connected to the first communication node 100, information indicating the modulation scheme set in the second communication node 200 _n , and Are stored in association with each other.

In the example shown in FIG. 4, the first communication node 100 is in a state of waiting to receive a message from the second communication node 200 _n . Therefore, the modulation scheme corresponding to each second communication node 200 _n is not associated.

A MPU 102, a communication module 104 ₁ and 104 _2, between the storage unit 106 are connected to each other by a bus 50.

<Function of First Communication Module 100>
FIG. 5 shows functions of the first communication node 100. FIG. 5 mainly shows functions executed by the MPU 102. That is, when the MPU 102 functions according to software (program) stored in the storage unit 106, the function shown in FIG. 5 is executed.

The first communication node 100 includes a modulation scheme determination unit 1022. The modulation scheme determination unit 1022 is connected to the communication modules 104 ₁ and 104 ₂ . The modulation scheme determining unit 1022 determines a modulation scheme to be used when performing communication with the second communication node 200 _n connected to the first communication node 100. Specifically, the modulation scheme determining unit 1022 receives a signal modulated by the ASK scheme when determining a modulation scheme to be used when communicating with the second communication node 200 _n. 104 ₁ together to function, to function communication module 104 ₂ for receiving a signal modulated by OFDM method. That is, the modulation scheme determining unit 1022 transmits a message from the second communication node 200 _n at both the communication modules 104 ₁ and 104 _{2 at} a predetermined transmission timing to be assigned to each second communication node 200 _n. Control to receive. The message from the second communication node 200 _n may include information indicating the second communication node and predetermined known information set in advance.

The modulation scheme determining section 1022, the data demodulated and decoded by the communication module 104 _1, the data demodulated and decoded by the communication module 104 ₂ is inputted. Modulation scheme determining section 1022, based on the data demodulated and decoded by identifying the modulation scheme is set to the second communication node 200 _n, used between the communication node 200 _n of the second Determine the modulation method to be used. Specifically, modulation scheme determining section 1022, if it can be identified based on the demodulation and decoding data from the communication module 104 _1, the information representative of the second communication node, and a predetermined known information, the It decides to use ASK with the second communication node. Further, when the modulation scheme determining unit 1022 can identify information representing the second communication node and predetermined known information based on the demodulated / decoded data from the communication module 1042, the _second method It decides to use OFDM with the communication node.

The modulation scheme determination unit 1022 inputs information representing the modulation scheme determined for each second communication node 200 _n to the modulation scheme setting unit 1024.

The modulation scheme setting unit 1024 is connected to the modulation scheme determination unit 1022 and the storage unit 106. The modulation scheme setting unit 1024 stores information representing the modulation scheme determined for each second communication node 200 _n to be input from the modulation scheme determination unit 1022 in the storage unit 106. Specifically, the modulation scheme setting unit 1024 stores information indicating the modulation scheme determined for each second communication node 200 _n from the modulation scheme determination unit 1022 in the modulation scheme correspondence table stored in the storage unit 106. reflect.

The modulation scheme switching unit 1028 is connected to the communication modules 104 ₁ and 104 ₂ and the storage unit 106. The modulation scheme switching unit 1028, with the second communication node 200 _n, when transmitting and receiving data, switches the communication module 104 _1, the communication module to be used with the communication module 104 _2. The modulation method can be switched by switching the communication module to be used.

  Specifically, modulation scheme switching section 1028 switches the modulation scheme based on the modulation scheme correspondence table stored in storage section 106. Also, modulation scheme switching section 1028 switches the modulation scheme according to the modulation scheme specified by transmission destination modulation scheme specifying section 1026. When the modulation method is switched by the modulation method switching unit 1028, the message from the second communication node is received by the communication module in which the modulation method used by the second communication node is set. The message from the second communication node is transmitted by the communication module in which the modulation method used by the second communication node that is the transmission destination of the second communication node is set.

Destination modulation scheme specifying unit 1026, a modulation method switching section 1028 are connected to the communication module 104 ₁ and 104 _2, a storage unit 106. The transmission destination modulation method specifying unit 1026 specifies the transmission destination of the data based on the data from the communication module switched by the modulation method switching unit 1028 among the communication modules 104 ₁ and 104 ₂ . Specifically, transmission destination modulation scheme specifying unit 1026 specifies a transmission destination based on information representing the second communication node of the transmission destination included in the data from the second communication node. The transmission destination modulation scheme identifying unit 1026 refers to the modulation scheme correspondence table stored in the storage unit 106 and identifies the modulation scheme used by the second communication node of the transmission destination. The transmission destination modulation scheme specifying unit 1026 inputs information representing the modulation scheme used by the second communication node of the transmission destination to the modulation scheme switching unit 1028.

  The modulation scheme switching unit 1028 switches the communication module to be used according to the information indicating the modulation scheme used by the second communication node of the transmission destination from the transmission destination modulation scheme identification unit 1026.

<Second communication node 200 _n >
The second communication node 200 _n transmits and receives messages to and from other second communication nodes connected to the second communication node 200 _n . Messages may be transmitted / received between the second communication node 200 _n and another second communication node via the first communication node 100.

The second communication node 200 _n transmits a message modulated according to the modulation scheme mounted on the second communication node 200 _n .

The second communication node 200 _n receives the message modulated according to the modulation scheme mounted on the second communication node 200 _n .

Figure 6 shows a second communication node 200 _n. FIG. 6 mainly shows a hardware configuration.

The second communication node 200 _n has a microprocessor (MPU: Micro-Processing Unit) 202. MPU202 performs the second communication node 200 _n overall control.

The second communication node 200 _n has a communication module 204. The communication module 204 communicates with the communication module 104 ₁ or 104 _{2 of} the first communication node 100. For example, communication is performed according to a predetermined communication protocol. Communication module 204, in accordance with the second mounting modulation scheme to the communication node 200 _n, performs modulation. In one embodiment of the second communication node 200 _n , modulation is performed by the ASK method or the OFDM method. Specifically, the OFDM method is set for the second communication nodes 200 ₁ and 200 ₂ , and the ASK method is set for the second communication nodes 200 ₃ and 200 ₄ .

  That is, a second communication node equipped with the ASK method and a second communication node equipped with the OFDM method are prepared. Which modulation system is used for the second communication node is different depending on the position where the second communication node is mounted. A second communication node equipped with a modulation scheme that is resistant to noise, for example, the OFDM scheme, is mounted in a place with large noise. In a place where noise is small, a second communication node equipped with a modulation scheme that is not so strong against noise but can be easily used, for example, the ASK scheme, is mounted. Since the second communication node to be mounted can be selected according to the influence of noise, it is possible to improve noise tolerance and cope with the minimum change of the second communication node.

The second communication node 200 _n has a storage unit 206. The storage unit 206 stores a program for causing the MPU 202 to function as the second communication node 200 _n .

  The MPU 202, the communication module 204, and the storage unit 206 are connected to each other by a bus 250.

<Second communication node 200 _n functions>
FIG. 7 shows the functions of the second communication node 200 _n . FIG. 7 mainly shows functions executed by the MPU 202.

The second communication node 200 _n includes a message transmission control unit 2022. When the first communication node 100 connected to the second communication node 200 _n performs processing for detecting the modulation scheme used by the second communication node 200 _n , the message transmission control unit 2022 In addition, control for transmitting a predetermined message is performed.

  For example, when the power of the vehicle is turned on from off, the message transmission control unit 2022 acquires a predetermined message from the message stored in the storage unit 206, and the first communication node via the communication module 204 To 100. The predetermined message may include information indicating the second communication node and predetermined known information set in advance.

<Operation of communication system (1)>
FIG. 8 shows an embodiment of the operation of the communication system.

  FIG. 8 mainly shows operations performed by the first communication node 100.

  The vehicle equipped with the communication system is turned on (step S802). For example, turning on the power to the vehicle may be performed by turning the ignition from off to on. Further, the power supply to the vehicle may be performed by changing the battery from the unconnected state to the connected state. As shown in FIG. 4, the modulation method correspondence table when the vehicle power is turned on is set to the second communication node, although the second communication node included in the communication system is known. I don't know the modulation method. That is, the position where each second communication node is mounted is not known. Here, among all the second communication nodes, there may be one for which a modulation scheme is set. When the second communication node for which the modulation scheme is set is included, information indicating the set modulation scheme is set.

The first communication node 100 permits reception of a signal modulated by the OFDM scheme and a signal modulated by the ASK scheme (step S804). That is, the modulation scheme determining unit 1022 operates the communication modules 104 ₁ and 104 ₂ . Here, the first communication node 100 does not transmit a signal.

When the vehicle is powered on, the second communication node 200 _n transmits a predetermined message in accordance with the modulation scheme set in the second communication node 200 _n . The predetermined message may include an identifier of the second communication node 200 _n that transmits the predetermined message and information that is known between the first communication node 100 and the second communication node. Good. The predetermined message may be a newly created message for causing the first communication node 100 to detect the modulation scheme set in the second communication node, or may be an existing message. May be.

The first communication node 100 waits to receive a message from the second communication node 200 _n .

The first communication node 100 receives the message from the second communication node 200 _n (step S806). That is, the message from the second communication node 200 _n is demodulated and decoded by the communication modules 104 ₁ and 104 ₂ .

The first communication node 100 sets an argument k (k is an integer of 0 <k ≦ n) to 1 to represent the second communication node 200 _n (step S808). That is, modulation scheme determining section 1022 sets k = 1.

The first communication node 100, the modulation method of the second communication node 200 _k determines whether the ASK method (step S810). That is, the modulation scheme determining section 1022, depending on whether or not the demodulated and decoded by the communication module 104 _1, the modulation method of the second communication node 200 _k determines whether the ASK method. If that could demodulated and decoded by the communication module 104 _1, the identifier included in the demodulation and decoding messages, the second communication node 200 _k are identified. The modulation scheme of the second communication node 200 _k is determined is ASK scheme.

When the modulation scheme of the second communication node 200 _k is determined to be ASK method (step S810: YES). The first communication node 100 determines the modulation scheme of the second communication node 200 _k to the ASK method (step S812). That is, the modulation scheme determining section 1022, modulation method of the second communication node 200 _k is determined to be ASK method.

When the modulation scheme of the second communication node 200 _k is determined not to ASK method (step S810: NO). The first communication node 100 determines the modulation scheme of the second communication node 200 _k in OFDM scheme (step S814). That is, the modulation scheme determining unit 1022 determines that the modulation scheme of the second communication node 200 _k is the OFDM scheme.

  After the processes of steps S812 and S814 are completed, the first communication node 100 determines whether k and n are equal (step S816). That is to say, the modulation scheme determining unit 1022 determines whether k = n, so that the second communication node that needs to determine the modulation scheme among all the second communication nodes included in the communication system. Whether or not the modulation method has been determined is determined.

When it is determined that k and n are not equal (step S816: NO), the first communication node 100 increases k by 1 (step S818). After increasing k by 1, the process proceeds to step S810. That is, the modulation scheme determining section 1022, if judged not to be k = n, and k = k + 1, and proceeds to step S810, sets the modulation method of the next second communication node 200 _k.

  When it is determined that k and n are equal (step S816: YES), the first communication node 100 reflects the modulation scheme in the modulation scheme correspondence table (step S820). That is, the modulation scheme setting unit 1024 reflects information representing the modulation scheme determined by the modulation scheme determination unit 1022 in the modulation scheme correspondence table.

  The processes in steps S804 and S808-S820 are executed by the MPU 102 included in the first communication node 100.

  A program for causing the MPU 102 to function as the first communication node 100 is provided in a state of being recorded on a recording medium such as a flexible disk, a CD-ROM, or a memory card. Further, the program may be downloaded via a communication network. When this recording medium is inserted into an auxiliary storage device of a computer, a program recorded on the recording medium is read. The MPU 102 writes the read program into the RAM or HDD and executes processing. The program causes the computer to execute steps S804 and S808-S820 of FIG. For example, the program may be configured to execute at least some steps.

FIG. 9 shows an example of setting the modulation scheme in the modulation scheme correspondence table. In the example shown in FIG. 9, the case where the second communication node _200n is arranged as shown in FIG. 2 is shown.

When the second communication node 200 _n is arranged as shown in FIG. 2, the OFDM method is set because the second communication node 200 ₁ is arranged in the brake. The second communication node 200 ₂ OFDM scheme for placement on the engine is set. The second communication node 200 ₃ is set ASK system for placement in the meter. Second communication node 200 ₄ ASK method for placement in the door is set.

In the flowchart shown in FIG. 8, each time the modulation scheme of the second communication node 200 _n is determined, it may be reflected to the modulation scheme correspondence table.

The information indicating the modulation method reflected in the modulation method correspondence table may be deleted or kept when the vehicle power is turned off. When information indicating a modulation method is held, it may be stored in a nonvolatile memory. When the information indicating the modulation method is stored in the nonvolatile memory, the first communication node 100 sends a message from the second communication node 200 _n when the power is turned on from the second time on. Therefore, communication can be started immediately when the power is turned on.

<Operation of communication system (2)>
FIG. 10 shows an embodiment of the operation of the communication system.

  FIG. 10 mainly shows operations performed by the first communication node 100.

The first communication node 100, the modulation method corresponding table shown in FIG. 9, the modulation method corresponding to the second communication node 200 _n is set.

In one embodiment of the operation of the communication system, the first communication node 100 receives the message from the second communication node 200 ₃ to the second communication node 200 _2.

The first communication node 100 receives the message from the second communication node 200 ₃ (step S1002). In other words, a message from the second communication node 200 ₃ is received by the communication module 104 _1.

The first communication node 100, in accordance with the provisions of the protocol, and analyzes the received message by the communication module 104 ₁ (step S1004). That, MPU 102 in accordance with the provisions of the protocol, and analyzes the received message by the communication module 104 _1.

The first communication node 100 specifies a message transmission destination (step S1006). That is, the transmission destination modulation scheme specifying unit 1026 specifies a transmission destination based on the analyzed message. Destination specifying unit 1026, as the destination of the message, identifying a second communication node 200 _2.

The first communication node 100 specifies the modulation scheme set for the specified transmission destination (step S1008). That is, the transmission destination modulation method specifying unit 1026 specifies the modulation method set in the _second communication node 2002 specified as the message transmission destination. The transmission destination modulation scheme specifying unit 1026 refers to the modulation scheme correspondence table and identifies the OFDM scheme as the modulation scheme set in the _second communication node 2002.

The first communication node 100 modulates the message by the modulation method set as the transmission destination, and transmits it to the communication line connected to the transmission destination (step S1010). That is, the modulation scheme switching unit 1028, the communication module 104 ₂ is configured to send a message. The modulated message by OFDM method is transmitted from the communication module 104 _2, the second to the communication node 200 _2.

  The processes in steps S1004 to S1008 are executed by the MPU 102 included in the first communication node 100.

  A program for causing the MPU 102 to function as the first communication node 100 is provided in a state of being recorded on a recording medium such as a flexible disk, a CD-ROM, or a memory card. Further, the program may be downloaded via a communication network. When this recording medium is inserted into an auxiliary storage device of a computer, a program recorded on the recording medium is read. The MPU 102 writes the read program into the RAM or HDD and executes processing. The program causes the computer to execute steps S1004 to S1008 in FIG. For example, the program may be configured to execute at least some steps.

  According to the present embodiment, the physical layer and the software are separated. A modulation method is adopted for the physical layer.

  Also, the modulation method is selectively used depending on whether or not the environment is greatly affected by noise. That is, a second communication node equipped with a different modulation method is prepared, and one of them is installed. A second communication node mounted in an environment that is greatly affected by noise is mounted with a modulation scheme that is resistant to noise. The second communication node mounted in an environment that is not greatly affected by noise is mounted with a modulation method that is not very resistant to noise.

  The first communication nodes that communicate with both the second communication node mounted in an environment that is greatly affected by noise and the second communication node that is mounted in an environment that is not significantly affected by noise are each second communication node. Communication module corresponding to the modulation method mounted on the communication node. The first communication node specifies a second communication node as a transmission destination based on a message from the second communication node, and specifies a modulation scheme mounted on the two communication nodes as the transmission destination. The process of specifying the modulation method mounted on the two communication nodes of the transmission destination is realized by the MPU 102 mounted on the first communication node 100 functioning according to software.

  Since the first communication node has a communication module corresponding to the modulation scheme mounted on each second communication node, it is not necessary to change hardware for each modulation scheme mounted on the second communication node. For this reason, the number of parts to be mounted on the vehicle can be reduced. Further, the first communication node can be shared regardless of the vehicle. In addition, since a communication module corresponding to the modulation method mounted on each second communication node is mounted in advance, even if the number of second communication nodes increases or decreases, the modulation method can be changed in the state mounted on the vehicle. Can change.

<Modification (Part 1)>
When the vehicle is shipped, the modulation scheme set in the second communication node may be set in the modulation scheme correspondence table. The first communication node 100 waits for a message from the second communication node when the power is turned on by setting the modulation method set in the second communication node when the vehicle is shipped. Without being able to work. For this reason, it is possible to shorten the time from when the vehicle is turned on until the communication system operates.

<Modification (Part 2)>
In addition to the data buses 150 ₁ and 150 ₂ , a communication line for transmitting information indicating a modulation scheme mounted on the second communication node 200 _n may be prepared.

Further, the electric wire, the first communication node 100, may be connected between the second communication node 200 _n. When the first communication node 100 and the second communication node 200 _n are connected by the electric wire, the second communication node 200 connected for each electric wire on the first communication node 100 side. _n is specified. Specifically, the connector of the first communication node 100 is associated with the second communication node 200 _n connected to the connector. In this case, the second communication node 200 _n transmits the modulation scheme mounted on the first communication node 100 by the voltage applied to the electric wire. Specifically, 2 V may be applied to the second communication node 200 _n on which the ASK system is mounted, and 4 V may be applied to the second communication node 200 _n on which the OFDM system is mounted. 2V and 4V are examples and can be appropriately changed.

<Modification (Part 3)>
When the vehicle is powered on, the first communication node 100 transmits a message (hereinafter referred to as “confirmation message”) for confirming the corresponding modulation method to the second communication node 200 _n. To do. The confirmation message is modulated by one of the modulation schemes mounted on the second communication node 200 _n and transmitted. The confirmation message includes information indicating the modulation scheme recognized by the first communication node 100.

  FIG. 11 shows an example of the confirmation message.

  In the example shown in FIG. 11, the confirmation message includes a header, data 1, data 2,. Data 1 and data 2 may be repeated according to the number of second communication nodes included in the communication system. In the example shown in FIG. 11, the second communication node is represented by “ECU”. Specifically, the data 1 includes an ECU number, specifically, an identifier of the second communication node. Data 2 includes information indicating a modulation method.

  According to one embodiment of the confirmation message, the data 1 includes “01” representing the identifier of the second communication node mounted on the engine, and the data 2 includes “01” representing the ASK method. It is. Further, the data 1 includes “02” representing the identifier of the second communication node mounted on the brake, and the data 2 includes “02” representing the OFDM scheme.

The second communication node 200 _n demodulates and decodes the message from the first communication node 100, and when the modulation scheme included in the message is mounted, the second communication node 200n sends the modulation to the first communication node 100. Information indicating that communication can be performed using a method is transmitted. Specifically, the second communication node 200 _n may transmit information indicating “OK”.

Further, the second communication node 200 _n demodulates and decodes the message from the first communication node 100, and when the modulation method included in the message is not mounted, Information indicating that communication cannot be performed using the modulation method is transmitted. Specifically, the second communication node 200 _n may transmit information representing “NG”. This is because the modulation scheme used for modulation of the confirmation message may differ from information indicating the modulation scheme included in the confirmation message.

If the second communication node 200 _n cannot demodulate the message from the first communication node 100, the second communication node 200 _n cannot recognize the message and therefore cannot respond to the first communication node 100. In this case, the second communication node 200 _n starts communication using the modulation scheme mounted on the second communication node 200 _n . The first communication node 100 changes the recognized modulation method according to the message from the second communication node 200 _n .

  According to the present embodiment and the modification, it is possible to select a modulation scheme that is not easily disturbed by disturbances such as noise according to the arrangement position of the second communication node. In a vehicle room, the magnitude of disturbance received by a communication node varies depending on the arrangement of peripheral devices and the like. Since the magnitudes of disturbances are different, it may be possible to adopt a modulation scheme that is not easily disturbed by disturbances in all the second communication nodes, but this is not realistic. This is because the parts cost increases.

  By preparing a second communication node equipped with a different modulation method, selecting the second communication node according to the arrangement position in the vehicle, and further switching the modulation method at the first communication node, each second One communication system can support one modulation system. That is, the second communication node equipped with a modulation method that is not easily disturbed by disturbance can be arranged at a position that is susceptible to noise. In addition, a second communication node equipped with a modulation method that is not so strong against disturbance can be arranged at a position where the influence of noise is not large.

  Furthermore, although the arrangement of communication nodes varies depending on the vehicle type, the modulation method is switched at the first communication node, so the second communication node to be arranged can be selected according to the influence of disturbance. That is, it is not necessary to change the hardware of the first communication node for each vehicle.

  Although the present invention has been described above with reference to specific embodiments, each embodiment is merely an example, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. I will. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram, but such an apparatus may be realized by hardware, software, or a combination thereof. The present invention is not limited to the above-described embodiments, and various variations, modifications, alternatives, substitutions, and the like are included without departing from the spirit of the present invention.

100 First communication node 102 MPU
104 ₁ communication module 104 ₂ communication module 106 storage unit 150 ₁ , 150 ₂ data bus 200 _n (n is an integer of n> 0) second communication node 202 MPU
204 Communication Module 206 Storage Unit 1022 Modulation Method Determining Unit 1024 Modulation Method Setting Unit 1026 Destination Modulation Method Specifying Unit 1028 Modulation Method Switching Unit 2022 Message Transmission Control Unit

Claims (10)

A communication system having a first communication node and a plurality of second communication nodes that communicate via the first communication node,
The first communication node is
A plurality of communication modules that perform modulation using different modulation schemes;
A modulation scheme identifying unit that identifies a modulation scheme set in the second communication node of the destination based on a message from the second communication node;
A modulation scheme switching unit that switches so as to transmit a message from the second communication node from a communication module in which the modulation scheme identified by the modulation scheme identification unit is mounted among the plurality of communication modules; Communications system. The communication system according to claim 1,
The first communication node is
A communication system, comprising: a modulation scheme setting unit that sets a modulation scheme to be used for each second communication node. The communication system according to claim 2,
The first communication node is
A modulation scheme determining unit that identifies a modulation scheme mounted on the second communication node based on a result of processing a message from the second communication node by the plurality of communication modules;
The communication system is a communication system in which the modulation method setting unit sets the modulation method specified by the modulation method determination unit. The communication system according to claim 2,
The modulation scheme setting unit is specified based on voltages applied by the plurality of second communication nodes to electric wires respectively connecting the first communication node and the plurality of second communication nodes. A communication system for setting a modulation method. The communication system according to claim 2,
The first communication node is
A modulation scheme determination unit that identifies a modulation scheme mounted on the second communication node according to whether there is a response to a message modulated by a predetermined modulation scheme to be transmitted to the second communication node Have
The communication system is a communication system in which the modulation method setting unit sets the modulation method specified by the modulation method determination unit. The communication system according to any one of claims 1 to 5,
The second communication node is
A communication system for transmitting a message modulated in accordance with a modulation scheme to be mounted according to a position where the second communication node is arranged. The communication system according to claim 6,
A communication system in which a different modulation scheme is mounted on the second communication node according to the influence of noise. The communication system according to any one of claims 1 to 7,
A communication system in which the modulation system mounted on the plurality of communication modules includes an OFDM system, an ASK system, a PSK system, and an FSK system. A communication node that relays messages,
A plurality of communication modules that perform modulation using different modulation schemes;
A modulation scheme identifying unit that identifies the modulation scheme set in the destination communication node based on a message from another communication node;
A modulation method switching unit that switches so as to transmit a message from the other communication node from a communication module in which the modulation method specified by the modulation method specifying unit is mounted among the plurality of communication modules. node. A communication method in a communication system having a first communication node and a plurality of second communication nodes that perform communication via the first communication node,
The first communication node is
It has multiple communication modules that modulate using different modulation methods,
The first communication node is
A modulation scheme identifying step for identifying a modulation scheme set in the destination second communication node based on a message from the second communication node;
A modulation method switching step for switching so as to transmit a message from the second communication node from a communication module in which the modulation method specified in the modulation method specification step is mounted among the plurality of communication modules; Communication method.

Images