JP7328007B2 - Wireless communication node and wireless communication system - Google Patents

Description

The present invention provides a wireless communication node capable of controlling the transmission timing of a wireless communication node generating communication data, in order to efficiently aggregate a plurality of communication data for which wireless communication has failed and perform proxy communication. It relates to wireless communication systems.

In a mesh network including multiple wireless communication nodes, it is preferable to reduce the amount of communication by collecting multiple pieces of communication data held by relay nodes (hereinafter also referred to as proxy communication nodes). In addition, it is preferable that the communication data generation node controls the communication timing so that the communication data can be collected easily at the relay node, and the effect of collecting the communication data can be obtained. In particular, it is preferable that the communication data transmission node reliably and quickly transmits the communication data in order to aggregate the communication data at the relay node.

For example, Patent Literature 1 and Patent Literature 2 disclose a configuration of a wireless communication node that periodically acquires required data from an interface and wirelessly transmits the data to the same destination as communication data. Since communication data to be wirelessly transmitted also occurs at other nodes in the network, arrangements have been disclosed to aggregate these communication data at relay nodes in order to reduce overall network traffic. Then, in order to make it easier for communication data to gather at a relay node, a configuration is disclosed in which the transmission timing of the next node is changed based on the success or failure of the wireless communication of the previous transmission node.

A conventional configuration based on Patent Document 1 will be described with reference to FIGS. 6 and 7. FIG. The transmission order of the nodes is defined in advance, and if the communication of the node immediately before the transmission order fails, the node next in the transmission order performs wireless communication immediately after the communication failure.

In the example of FIG. 6, the aggregation number (the number of aggregates) is 3, and the node N'1 transmits communication data to the node N'5. Node N'2, Node N'3, and Node N'4 are overhearing (intercepting) this communication, and when it is confirmed that Node N'5 cannot receive the communication data of Node N'1, Node N'4 queues communication data from node N'1.

Since the node N'2 can detect that the communication with the node N'1 has failed, it transmits its own communication data to the node N'5 immediately after the communication with the node N'1. Node N'3 and node N'4 overhear the communication of node N'2.

If the communication data of the node N'2 does not reach the node N'5 and the communication fails, the node N'4 queues the communication data of the node N'2 and After checking the communication data from N'1 and confirming that the destination is the same, the two communication data are aggregated.

Since the communication with the node N'2 has failed, the node N'3 transmits its own communication data to the node N'5 immediately after the communication with the node N'2. The communication of node N'3 is overheard by node N'4.

If the communication data of the node N'3 does not reach the node N'5 and the communication fails, the node N'4 queues the communication data of the node N'3. When the communication data of '1, node N' and 2 are confirmed and confirmed to be the same destination, the three communication data are aggregated.

At the node N'4, since the three communication data are aggregated, the condition for the number of aggregations is satisfied, and proxy communication (Patent Document 3) is performed toward the node N'5. Patent Document 3 is a prior art document that describes proxy communication.

Japanese Patent Application No. 2018-010542 Japanese Patent Application No. 2018-131648 JP 2014-225859 A

However, according to the configurations of Patent Literatures 1 and 2, if some of the data generating nodes succeed in communication, there is a problem that changing the communication timing for aggregating the communication data may not function after the communication succeeds. be.

Specifically, in FIG. 7, when the communication from the node N'1 to the node N'5 fails, the node N'2 which has changed the communication timing immediately transmits its own communication data to the node N'5. When communication from node N'2 to node N'5 succeeds, node N'3 does not change the communication timing, so node N'4 waits for a certain period of time and then performs proxy communication. may occur. In this case, since the node N'3 starts communication after the communication of the node N'4, aggregation of the communication data does not occur at the node N'4.
Accordingly, an object of the present invention is to provide means for solving such problems.

In order to solve the above problems, the present invention employs the following configuration.
That is, the invention of the wireless communication node according to claim 1 is
A wireless communication node that stores transmission order information whose transmission order is predetermined and functions as a transmission node, a proxy communication node, and a reception node,
a wireless receiving unit that receives communication data not addressed to the node itself from another wireless communication node;
a communication success/failure determination unit that determines success/failure of communication of the communication data received from the other wireless communication node that is not addressed to the own node and generates communication success/failure information;
an overheard communication data storage unit that associates and stores a plurality of the communication data received from the other wireless communication node and not addressed to the own node and the communication success/failure information of the plurality of communication data;
A communication timing management unit for calculating transmission timing based on the transmission node information and the communication success/failure information of the plurality of communication data stored in the overheard communication data storage unit, and the transmission order information. and

According to the above configuration, even when some of the data generating nodes have succeeded in communication, it is possible to properly operate the function of changing communication timing for collecting communication data after successful communication.

In order to solve the above-mentioned problems, the invention according to claim 2 is the wireless communication node according to claim 1, wherein the communication timing management unit is configured to control that the wireless communication of the wireless communication node whose transmission order is immediately before the own node is In case of failure, change the transmission timing so that the communication data is transmitted immediately after the failed wireless communication, and if the failed wireless communication is not the wireless communication of the wireless communication node whose transmission order is immediately before, Changing the transmission timing of a wireless communication node so as to transmit communication data immediately after a failed wireless communication, and changing the transmission timing of the own node so that communication frames are adjacent to each other from the changed transmission timing. characterized by

According to the above configuration, if the immediately preceding node fails in communication, the next node transmits the communication data immediately after the failed communication, and if the previous node fails in communication, the failure occurs. Since the timing can be changed so that the communication frames immediately after the transmission are adjacent to each other, the transmission timing can be changed so that the communication data can be aggregated efficiently based on the communication history information.

In order to solve the above problems, the invention according to claim 3 is the wireless communication node according to claim 1 or 2, wherein the communication timing management unit, even if there is communication data that could not be overheard, Assuming that communication data is transmitted with a predetermined communication frame length, the transmission timing of the own node is calculated.

According to the above configuration, even if there is communication data that could not be overheard, the timing at which the own node should transmit the communication data is determined based on the past communication data and the transmission order information stored in the overhear communication data storage unit. Appropriate calculation becomes possible.

In order to solve the above problems, the invention according to claim 4 is the wireless communication node according to any one of claims 1 to 3,
a proxy communication data storage unit that stores communication data that is not addressed to the self node and for which communication fails when there is no data to be transmitted to the self node;
and a communication data synthesizing unit that aggregates communication data having the same destination information to form one communication data when there is a plurality of communication data stored in the proxy communication data storage unit.

According to the above configuration, the wireless communication node can function as a proxy communication node when there is no data to be transmitted to the own node. In this way, the wireless communication node functions as a transmission node when there is data to be transmitted to the node itself, and functions as a proxy communication node when there is no data to be transmitted to the node itself.

In order to solve the above-mentioned problems, the invention according to claim 5 is the wireless communication node according to claim 4, wherein the communication timing management unit stores data stored in the proxy communication data storage unit when an aggregation condition is satisfied. The communication data is transmitted from the wireless transmission unit, and the aggregation condition is the aggregation number of communication data not addressed to the own node for which communication failed, or the communication data not addressed to the self node for which communication failed is aggregated. It is characterized by being an aggregation time.

According to the above configuration, when the wireless communication node functions as a proxy communication node, after efficiently aggregating communication data for which communication failed before the aggregation condition is satisfied, proxy communication is performed immediately after the aggregation condition is satisfied. can be executed.

In order to solve the above problems, the invention of a radio communication system according to claim 6 is:
a plurality of wireless communication nodes having a transmission function according to any one of claims 1 to 3;
at least one wireless communication node having a proxy communication function according to claim 5;
characterized by comprising

According to the above configuration, even when some of the data generating nodes have succeeded in communication, it is possible to properly operate the function of changing communication timing for collecting communication data after successful communication.

In order to solve the above problems, the invention according to claim 7 is the radio communication system according to claim 6, wherein the radio communication system does not have a controller that centrally manages the operation timing of the radio communication nodes, Each wireless communication node is characterized in that it transmits communication data based on the communication timing management section of its own wireless communication node.

According to the above configuration, in a simple wireless communication system that does not have a controller that centrally manages the operation timing of wireless communication nodes, a protocol such as CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) is adopted for a simple configuration. It is possible to build an efficient system with

In order to solve the above problems, the invention according to claim 8 is the wireless communication system according to claim 6 or 7, wherein the wireless communication system is mounted on a vehicle, and the communication data is an electronic device provided on the vehicle. It is characterized by being data output from.

According to the above configuration, in a vehicle, a large number of sensors, ECUs (Electronic Control Units), etc. are arranged, and a large amount of data is generated, and there is concern about an increase in network traffic. By using , it is possible to suppress the increase of traffic in the network and suppress the delay of communication.

According to the present invention, even when some of the data generating nodes have succeeded in communication, it is possible to appropriately operate the communication timing changing function for collecting communication data after successful communication.

1 is a schematic diagram showing an example of a configuration of a wireless network forming a wireless communication system; FIG. 1 is a block diagram showing an example of main components of each node that constitutes a wireless network; FIG. FIG. 4 is a schematic diagram for explaining an example of storage elements of an overheard communication data storage unit included in a node; FIG. 4 is a schematic diagram for explaining an example of storage elements of a proxy communication data storage unit included in a node; 3 is a flow chart showing an operation example of the node shown in FIG. 2; 1 is a schematic diagram showing an example of a configuration of a wireless network that constitutes a wireless communication system according to conventional technology; FIG. 7 is a time chart showing an operation example of each node that configures the wireless network of FIG. 6;

(Overview of wireless communication system)
In this embodiment, the wireless communication system includes a plurality of wireless communication nodes, and each wireless communication node can function as a transmitting node, relay node (hereinafter also referred to as proxy communication node), and receiving node. That is, each wireless communication node functions as a receiving node when the received communication data is addressed to its own node, and when it is not addressed to its own node and does not have communication data to be transmitted, Functions as a proxy communication node. Also, each wireless communication node functions as a transmission node when received communication data is not addressed to itself and when it has communication data to be transmitted. Transmission order information is stored in each wireless communication node, and the transmission order of the own node can be determined.

When functioning as a sending node, it does not function to aggregate received communication data not addressed to itself. That is, when functioning as a transmission node, received communication data not addressed to the node itself is not stored in proxy communication data storage section 206, which will be described later. However, received communication data that is not addressed to its own node is sent together with transmission node information included in the communication data and communication success/failure information indicating whether the communication of the communication data has succeeded or failed, together with overheard communication data described later. It is stored in the storage unit 209 .

Therefore, when functioning as a transmission node, the transmission timing of its own node is calculated based on the transmission order information, the transmission node information, and the communication success/failure information. When communication failure information is included in the communication success/failure information, the transmission timing of the own node is changed. If communication failure information is not included in the communication success/failure information, the transmission timing of the own node does not change because the communication frame for transmitting/receiving communication data has a fixed length. Note that if the communication of the previous communication data has failed, the communication data of the next node is transmitted immediately after it is determined to have failed. As a result, when communication failure information is included in the communication success/failure information, the subsequent transmission timing is changed to be earlier according to the number of failures.

In the prior art, the transmission timing of the next transmission node is changed immediately after communication failure only when communication with the previous transmission node fails. In some cases, the subsequent transmission timings of the nodes may be delayed or have gaps. However, according to the present embodiment described above, the transmission timings of subsequent nodes are set adjacently based on a plurality of transmission histories. more likely to work well.

Also, when functioning as a proxy communication node, it functions to aggregate received communication data. That is, when functioning as a proxy communication node, the received communication data is stored in the proxy communication data storage unit 206, which will be described later, and the communication data with the same destination are aggregated. to run. The aggregation condition is either the number of aggregations or the time of aggregation, and the number of aggregations and the time of aggregation can be set to arbitrary values by the wireless communication system. Aggregation time may also be a variable value during operation of the wireless communication system.

The wireless communication system according to the present embodiment described above can be mounted on a moving object such as a vehicle. In this case, the communication data transmitted by the transmitting node may be information such as sensor information for detecting the status of the mobile object, information for controlling the mobile object, and information on electronic equipment mounted on the mobile object. .

Note that the wireless communication system according to the present embodiment does not have a controller for controlling transmission/reception timing of each node, and employs a protocol such as CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance).

(Operation example of wireless communication system)
An operation example of the wireless communication system will be described with reference to FIG.

FIG. 1 shows a wireless communication system including node N1, node N2, node N3, node N4 and node N5. In the following description of the operation example, the nodes N1, N2, and N3 have communication data to be transmitted and therefore become transmission nodes, and the node N4 does not have communication data to be transmitted and therefore become relay nodes. . Also, the nodes N1, N2, and N3 are trying to transmit the communication data with the node N5 as the destination. The transmission order is determined in advance as transmission order information, and the node N1, node N2, node N3, node N4, and node N5 store the transmission order information. The transmission order information in this embodiment is in the order of node N1→node N2→node N3→node N4→node N5.

First, in FIG. 1, the node N1 transmits communication data with the node N5 as the destination. The communication data transmitted by node N1 is overheard by nodes N2, N3 and N4.

When the nodes N2, N3 and N4 confirm that the node N5 has not successfully received the communication data from the node N1, the node N4 queues the communication data. That is, the node N4 stores the communication data from the node N1 and the destination information of the communication data in the proxy communication data storage unit 206. FIG. The destination information in this case is the identification information of the node N5. Note that the node N1 may set a resend flag for resending communication data for which communication failed.

Since the node N3 is the node to communicate with after the node N2, the overheard communication data storage unit 209 stores the communication data of the node N1, the transmission node information of the communication data, and the information that the communication of the communication data has failed. The communication success/failure information is stored so as to indicate the information. The communication data of the node N1 is stored in the (N-2) part of FIG. 3 (N is the communication order of the own node). Next, the node N3 calculates the transmission timing of its own node. In this case, the communication of the node N2 should follow the communication of the node N1, so immediately after the communication of the node N1 fails, one communication frame is provided for the node N2 to communicate the communication timing of the node N3. The timing management unit 208 decides. One communication frame has a fixed length, and the wireless communication system can set the fixed length to any length.

Since the node N2 is the next node to communicate with after the node N1, the communication data held by the node N2 is transmitted with the node N5 as the destination immediately after the communication failure of the node N1.

Nodes N3 and N4 also overhear the communication data of node N2.

If the communication data of node N2 is successfully received by node N5 and the acknowledgment (ACK (ACKnowledgement)) from node N5 is overheard by nodes N3 and N4, node N4 receives the communication data of node N2. Discard.

Since the node N3 is a node to communicate with after the node N2, the overheard communication data storage unit 209 stores the communication data of the node N2, the transmission node information of the communication data, and the information that the communication of the communication data was successful. Communication success/failure information indicating information is stored. The communication data of the node N2 is stored in the (N-1) part of FIG. 3 (N is the communication order of the own node). Next, the node N3 calculates the transmission timing of its own node. The transmission timing of the communication data of the node N3 is set immediately after the communication of the node N2.

The node N4 also overhears the communication data of the node N3.

When the node N4 confirms that the node N5 has not successfully received the communication data from the node N3, the node N4 queues the communication data. That is, the node N4 stores the communication data from the node N3 and the destination information of the communication data in the proxy communication data storage unit 206. FIG. The destination information in this case is the identification information of the node N5. The node N4 confirms the previously queued communication data of the node N1, and when confirming that the destination is the same (in this case, the node N5), the node N4 aggregates the communication data of the node N1 and the communication data of the node N3. , one communication data as one packet.

At the node N4, the number of aggregations of communication data is 2. However, if an aggregation waiting time, which is a predetermined time, has passed after queuing the communication data of the node N1, the aggregation is performed with the node N5 as the destination. immediately send the received packet to node N5.

(Configuration example of wireless communication node)
Main functions of the wireless communication node 200 (hereinafter sometimes simply referred to as a node) for realizing the functions described above will be described with reference to the block diagram of FIG.

The node includes an antenna ANT, a radio reception unit 202, a radio transmission unit 203, a destination determination unit 204, a communication success/failure determination unit 205, a proxy communication data storage unit 206, a communication data synthesis unit 207, a communication timing management unit 208, an overheard communication data It includes a storage unit 209 and I/F units 210 and 211 . Note that the node may include the transmission/reception switching unit 201 in some cases.

The radio reception unit 202 has a function of receiving communication data transmitted from other nodes. The communication data may or may not be addressed to the node itself. Receiving communication data not destined for itself is called overhearing.

The wireless transmission section 203 has a function of transmitting communication data from the node. The communication data may be data generated in the own node, or communication data which is not addressed to the own node and which has been overheard and failed in communication, and which is to be communicated by proxy.

The destination determination unit 204 has a function of referring to the destination information of the communication data received by the wireless reception unit 202 and distinguishing between communication data addressed to the own node and communication data addressed to other nodes. As an example, the destination information is node identification information that can be referred to as information included in the header.

The communication success/failure determination unit 205 has a function of determining whether or not the communication of the communication data destined for the other node has succeeded when the communication data destined for the other node is overheard. For example, when an acknowledgment (ACK) for communication data destined for another node can be overheard, the communication success/failure determination unit 205 can determine that the communication of the communication data has succeeded. Further, for example, when a negative acknowledgment (NACK (Negative ACKnowledgement)) to communication data addressed to another node can be overheard, or when a positive acknowledgment (ACK) and a negative acknowledgment (NACK) cannot be overheard, the communication The success/failure determination unit 205 can determine that the communication of the communication data has failed. Success or failure of communication is stored as communication success or failure information in an overheard communication data storage unit 209, which will be described later.

The proxy communication data storage unit 206 has a function of temporarily storing communication data destined for another node that has overheard and for which communication has failed. It also stores destination information indicating the destination node of the communication data included in the communication data. For example, if the communication of the node in the communication order (N-2) fails, the communication data in the communication order (N-2) and the node to which the communication data in the communication order (N-2) should be transmitted Destination information is stored as identification information (for example, node X) (see FIG. 4, N is the communication order of the own node). Furthermore, in FIG. 4, when the communication of the node in the communication order (Nn) fails, the communication data in the communication order (Nn) and the communication data in the communication order (Nn) are transmitted. It also shows that destination information is stored as identification information of a node (for example, node X) (n is the number of aggregations).

The communication data synthesizing unit 207 synthesizes (aggregates) a plurality of communication data with the same destination when the proxy communication data storage unit 206 contains a plurality of pieces of communication data for which communication has failed due to wireless communication overhear. ) and combine them into one packet. That is, it is possible to reduce the total number of packets transmitted by combining.

The communication timing management unit 208 has a function of determining the communication timing of communication by the own node from the communication data stored in the overheard communication data storage unit 209 . Each node transmits communication data in fixed-length communication frames in order, but if the communication of the previous node fails, the next node immediately transmits the communication data. Since the overheard communication data storage unit 209 stores a history of communication success/failure information indicating that communication has failed or succeeded, each node can adjust its own communication timing based on the communication success/failure information. become.

More specifically, the communication timing management unit 208 determines the transmission timing based on the transmission node information, the communication success/failure information, and the transmission order information of the plurality of communication data stored in the overheard communication data storage unit 209. Calculate. The transmission node information is information included in communication data. The transmission order information is information stored in each node, and is information in which node identification information is stored corresponding to the transmission order.

Specifically, when the wireless communication of the wireless communication node whose transmission order is immediately before the own node fails, the communication timing management unit 208 adjusts the transmission timing so that the communication data is transmitted immediately after the failed wireless communication. If the failed wireless communication is not the wireless communication of the wireless communication node whose transmission order is immediately before, the transmission timing of the wireless communication node is changed so that the communication data is transmitted immediately after the failed wireless communication. and change the transmission timing of the own node so that the communication frame is adjacent to the changed transmission timing.

The overheard communication data storage unit 209 stores communication data acquired from another node due to wireless communication overhear and not destined for its own node, but for which communication has failed, and communication indicating the success or failure of the communication of the communication data. It has a function of correlating and storing success/failure information and transmission node information indicating the transmission node of the communication data. Details of the overheard communication data storage unit 209 are shown in FIG.

An interface (I/F) unit 210 has a function of outputting received communication data addressed to its own node to an electronic device such as an in-vehicle electronic device (ECU (Electronic Control Unit), etc.) connected to its own node. have Electronic devices are not limited to electronic devices mounted on vehicles.

An I/F (interface: Interface) unit 211 receives data information output from electronic devices such as in-vehicle devices (for example, switches and sensors) connected to its own node, generates communication data, and controls communication timing. 208. As an example, the sensor may be a sensor that detects the traveling speed of the vehicle or a sensor that detects the rotation speed of the engine. However, as described above, electronic devices are not limited to electronic devices mounted on vehicles.

The transmission/reception switching unit 201 as an option has a function of switching the connection between the antenna ANT and the radio reception unit 202 and the connection between the antenna ANT and the radio transmission unit 203 . That is, the transmission/reception switching unit 201 has a function of connecting the antenna ANT and the radio receiving unit 202 when receiving communication data, and connecting the antenna ANT and the radio transmitting unit 203 when transmitting communication data.

However, in the case of a node that does not have the transmission/reception switching unit 201 as an option, the antenna ANT1 (not shown) is fixedly connected to the radio reception unit 202, and the antenna ANT2 (not shown) is connected to the radio transmission unit 203. A fixed connection configuration is also possible. Also, the antennas ANT, ANT1, ANT2 can be placed inside or outside the node.

(Flowchart of operation example of wireless communication node)
A flowchart of an operation example of the wireless communication node 200 having the above configuration will be described with reference to FIG.

In step S501, the wireless reception unit 203 of the node checks whether communication data is received. If communication data is received (step S501: YES), the node proceeds to step S502, and if communication data is not received (step S501: NO), the node proceeds to step S517.

In step S502, the destination determining unit 204 of the node checks whether the received communication data is addressed to the node itself. If the received communication data is addressed to its own node (step S502: YES), the node proceeds to step S503, and if the received communication data is not addressed to itself (step S502: NO), , the node proceeds to step S504. If the node proceeds to step S503, the node functions as a receiving node.

In step S503, since the received communication data is addressed to the node itself, the node transmits an acknowledgment ACK indicating successful reception to the other node that transmitted the communication data, and terminates the process. However, if the communication data could not be received normally, a negative acknowledgment NACK is sent and the process ends.

In step S504, since the received (overheard) communication data is not addressed to the node itself, the node confirms whether or not there is communication data to be transmitted to the node itself. If there is communication data to be transmitted to the self node (step S504: YES), the node proceeds to step S505, and if there is no communication data to be transmitted to the self node (step S504: NO), the node proceeds to step Proceed to S512.

If the node proceeds to step S505, the node functions as a sending node. When functioning as a sending node, the communication data aggregation function does not work. If the node proceeds to step S512, the node functions as a proxy communication node. When functioning as a proxy communication node, the function of aggregating communication data works.

In step S<b>505 , the node stores the overheard communication data in the overheard communication data storage unit 209 . The node then proceeds to step S506.

In step S506, the node checks by overhearing whether or not the communication of the overheard communication data is successful. If the communication of the overheard communication data succeeds, the node can overhear the ACK of the communication data, and if the communication of the overheard communication data fails, the node can send the ACK of the communication data. cannot be overheard. If the communication of the overheard communication data is successful (step S506: YES), the node proceeds to step S507, and if the communication of the overheard communication data fails (step S506: NO), the node proceeds to step Proceed to S508.

In step S507, the node stores information indicating that the communication of the overheard communication data has succeeded in the overheard communication data storage unit 209, and terminates the process. Information indicating successful communication of the overheard communication data can be stored as a 1-bit pattern, for example. Specifically, as an example, information indicating successful communication is indicated by "1" or "0", information indicating unsuccessful communication is indicated by "0" or "1", and overheard information is indicated. is stored in the overheard communication data storage unit 209 in association with the communication data obtained. That is, for example, the communication success/failure information can be represented by 1 bit.

In step S508, the node stores information indicating that the communication of the overheard communication data has failed in the overheard communication data storage unit 209, and proceeds to step S509. As described above, the information indicating that the communication of the overheard communication data has failed can be stored in a 1-bit pattern, for example.

In step S509, the node confirms whether or not the overheard communication data is the communication data transmitted by the previous node, ie, the immediately preceding node. Each node stores the order of transmission by each node as transmission order information. If the overheard communication data is the communication data transmitted by the previous node (step S509: YES), the node proceeds to step S510. If the overheard communication data is not the communication data transmitted by the previous node (step S509: NO), the node proceeds to step S511.

In step S510, since it is the turn of the own node to transmit, the corresponding node transmits the data to be transmitted as communication data from the wireless communication unit 204 via the transmission/reception switching unit 202 and the antenna 201, and ends the process. do. In this way, when the overheard communication data is the communication data transmitted by the immediately preceding node and the communication fails, the next node in the transmission order communicates immediately after the failed communication. can be started.

In step S511, the node refers to the history of communication data stored in the overheard communication data storage unit 209 because the overheard communication data is not the communication data transmitted by the previous node, i.e., the immediately preceding node. Then, the transmission timing is calculated. Since the method of calculating the transmission timing has been described above, the explanation is omitted here.

In step S512, since the node functions as a proxy communication node, the node stores the overheard communication data in the proxy communication data storage unit 206. FIG. That is, if the overheard communication data is not communication data addressed to the own node and there is no communication data to be transmitted to the own node, the overheard communication data is stored in the proxy communication data storage unit 206 . The node then proceeds to step S519.

In step S519, the node checks by overhearing whether the communication of the overheard communication data was successful. If the communication of the overheard communication data succeeds, the node can overhear the ACK of the communication data, and if the communication of the overheard communication data fails, the node can send the ACK of the communication data. cannot be overheard. If the communication of the overheard communication data is successful (step S519: YES), the node proceeds to step S520, and if the communication of the overheard communication data fails (step S519: NO), the node proceeds to step Proceed to S513.

In step S519, since the communication of the overheard communication data was successful, the node discards the communication data stored in the proxy communication data storage unit 206. FIG. That is, the node deletes the communication data from proxy communication data storage unit 206 . This is because there is no need for proxy communication of communication data for which communication has succeeded. The node then proceeds to step S513.

In step S513, the node updates the aggregation wait timer. For example, the aggregation waiting timer is counted up when the overheard communication data is not the communication data addressed to the self node and there is no communication data to be transmitted to the self node. In this case, the aggregation wait timer functions as a counter. That is, when the node functions as a proxy communication node, the aggregation wait timer is incremented every time communication data is received. The node then proceeds to step S514.

In step S514, the communication data synthesizing unit 207 of the node aggregates the communication data having the same destination among the communication data stored in the proxy communication data storage unit 206, and makes one communication data. The node then proceeds to step S515.

In step S515, the node checks whether or not the aggregation condition for proxy communication of the aggregated communication data is satisfied. Aggregation conditions are conditions defined by the number of aggregations and an aggregation waiting timer, and the node confirms whether any of the conditions are met. If the aggregation condition is satisfied (step S515: YES), the node proceeds to step S516, and if the aggregation condition is not satisfied (step S515: NO), the node terminates the process. The number of aggregations is a number indicating how many pieces of communication data stored in proxy communication data storage unit 206 have been aggregated.

In step S516, the node carries out proxy communication of the communication data stored in the proxy communication data storage unit 206, or transmits the communication data generated in the own node, and the process ends.

In step S517, the communication timing management unit 208 of the node determines whether or not the transmission timing of its own node has arrived. If it is the transmission timing of the own node (step S517: YES), the node proceeds to step S516, and if it is not the transmission timing of the own node (step S517: NO), the node proceeds to step S521.

In step S521, the node checks whether or not there is communication data to be transmitted to the node itself. That is, a node that has communication data to be transmitted functions as a transmission node, and a node that does not have communication data to be transmitted functions as a proxy communication node. If there is communication data to be transmitted to the own node (step S521: YES), the node ends processing as a communication node, and if there is no communication data to be transmitted to the self node (step S521: NO) , the node proceeds to step S518 as a proxy communication node.

In step S518, the node updates the aggregation wait timer.

(Modification 1 of node operation)
In the above description of the embodiment, a case has been described in which node N1 fails in communication and node N2 succeeds in communication. Become.

Specifically, the communication data of the node N1 is stored in the overheard communication data storage unit 209 in the node N3. Since the node N1 has successfully communicated, the node N3 does not perform calculations to change the communication timing. Then, communication of node N2 occurs, node N3 overhears the communication data of node N2, and stores the communication data in the overhear communication data storage unit 209. FIG. Since the communication of the node N2 is the communication immediately before the node N3, the node N3 changes the communication timing and transmits its own communication data to the node N5 immediately after the communication failure of the node N2. However, the communication of node N3 fails as described above.

The node N4 overhears and queues the communication data of the nodes N2 and N3 with which communication has failed. That is, node N4 stores the communication data of node N2 and node N3 in proxy communication storage unit 206, aggregates the communication data, and transmits the aggregated communication data to node N5.

(Modified example 2 of node operation)
As another example, when communication is successful with both node N1 and node N2, node N3 stores these communication data in the overheard communication data storage unit 209. Since both communication are successful, Do not change the communication timing.

In addition, when the node N3 cannot overhear the communication of the node N2, if it can confirm that the communication of the node N1 has failed, it can transmit its own communication data at the timing calculated therefrom. It becomes possible.

Although the embodiments have been described in detail with reference to the drawings, the present invention is not limited by the contents described in the above embodiments. In addition, the components described above include components that can be easily assumed by those skilled in the art and components that are substantially the same. Furthermore, the configurations described above can be combined as appropriate. In addition, various omissions, substitutions, or changes in configuration can be made without departing from the gist of the present invention.

The present invention provides a wireless communication node capable of controlling the transmission timing of a wireless communication node generating communication data, in order to efficiently aggregate a plurality of communication data for which wireless communication has failed and perform proxy communication. It is extremely useful for use in wireless communication systems.

ANT antenna 200 wireless communication node 201 transmission/reception switching unit 202 wireless reception unit 203 wireless transmission unit 204 destination determination unit 205 communication success/failure determination unit 206. Proxy communication data storage unit 207 Data synthesizing unit 208 Communication timing management unit 209 Overheard communication data storage unit 210, 211 I/F unit

Claims (8)

A wireless communication node that stores transmission order information whose transmission order is predetermined and functions as a transmission node, a proxy communication node, and a reception node,
a wireless receiving unit that receives communication data not addressed to the node itself from another wireless communication node;
a communication success/failure determination unit that determines success or failure of communication of the communication data received from the other wireless communication node that is not addressed to the own node and generates communication success/failure information;
an overheard communication data storage unit that associates and stores a plurality of the communication data received from the other wireless communication node and not addressed to the own node and the communication success/failure information of the plurality of communication data;
A communication timing management unit for calculating transmission timing based on the transmission node information and the communication success/failure information of the plurality of communication data stored in the overheard communication data storage unit, and the transmission order information. wireless communication node. The communication timing management unit changes the transmission timing to transmit communication data immediately after the failed wireless communication when the wireless communication of the wireless communication node whose transmission order is immediately before the own node fails,
When the wireless communication node in the transmission order next to the wireless communication node in which the wireless communication has failed is the self node, the communication timing management unit changes the wireless communication node in the transmission order immediately before the self node. 2. The wireless communication node according to claim 1, wherein the transmission timing of the own node is changed so that the communication frames are adjacent to the changed transmission timing. The communication timing management unit calculates the transmission timing of the own node even if there is communication data that could not be overheard, assuming that the communication data is transmitted with a predetermined communication frame length. A wireless communication node according to claim 1 or 2. a proxy communication data storage unit that stores communication data that is not addressed to the self node and for which communication fails when there is no data to be transmitted to the self node;
and a communication data synthesizing unit that aggregates communication data having the same destination information into one communication data when there is a plurality of communication data stored in the proxy communication data storage unit. 4. A wireless communication node according to any one of claims 1 to 3. When the aggregation condition is satisfied, the communication timing management unit causes the wireless transmission unit to transmit the communication data stored in the proxy communication data storage unit,
wherein the aggregation condition is an aggregation number of communication data not addressed to the node but failed in communication, or an aggregation time during which communication data failed in communication not addressed to the node is aggregated. Item 5. The wireless communication node according to item 4. 4. The wireless communication node according to any one of claims 1 to 3, wherein a plurality of said wireless communication nodes having a transmission function;
The wireless communication node according to claim 5, wherein at least one said wireless communication node having a proxy communication function;
A wireless communication system comprising: The wireless communication system is characterized in that there is no controller that centrally manages the operation timing of wireless communication nodes, and each wireless communication node transmits communication data based on the communication timing management section of its own wireless communication node. 7. The radio communication system according to claim 6. 8. The wireless communication system according to claim 6, wherein said wireless communication system is mounted on a vehicle, and said communication data is data output from an electronic device provided on said vehicle.

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