Relay device, relay method, communication device and communication method

Abstract

To provide a relay device and the like capable of suppressing the occurrence of congestion even when a plurality of communication nodes are connected to a network.SOLUTION: A relay device functions as a relay node NR that relays communication of a first network and communication of a second network. The relay node NR acquires contention-related information related to changes in a contention state of communication by a plurality of communication nodes Nd connected to the first network, and transmits a state change notification based on the contention-related information to at least one communication node Nd.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The disclosure of this specification relates to a relay device, a relay method, a communication device, and a communication method. [Background technology]

[0002] Patent Document 1 discloses an image transmission system in which video signals from multiple cameras are encoded by an encoder and transmitted over a network. In the image transmission system of Patent Document 1, when congestion occurs in the network, the encoder changes the image encoding rate of the video signals to a lower rate based on congestion information sent from the network. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-304572 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, after congestion occurs in a network, the image coding rate is changed based on congestion information. Therefore, even if it is possible to continue transmission after the congestion occurs, it is difficult to suppress the occurrence of congestion itself.

[0005] An object of the present disclosure is to provide a relay device, a relay method, a communication device, and a communication method that are capable of suppressing the occurrence of congestion. [Means for solving the problem]

[0006] In order to achieve the above object, one disclosed embodiment is a relay device that relays communication of a first network (NW1) and communication of a second network (NW2), and detects a change in a contention state of communication by a plurality of communication nodes (Nd) connected to the first network. The information includes information indicating at least one of an increase or decrease in the number of communication nodes in a competing state and a change in the communication quality required by the communication nodes in a competing state. An information acquisition unit (11, 12) for acquiring competition-related information; Sending an acceptance notification to a requesting node as a communication node that is a requesting source of a request related to a change in a conflict state, the acceptance notification including information of a competing node as another communication node that is in conflict; At least one state change notification based on contention-related information Competitors a notification sending unit (13) for sending the notification to the node; ,of Preparation Based on the acceptance notification and the status change notification, data communication is performed between the requesting node and the competing node to share the communication capacity of the bottleneck link that determines the upper limit of the communication speed, and an information acquisition unit acquires priority information indicating a priority set for the communication of the requesting node, and a notification transmission unit transmits a status change notification including the priority information of the requesting node to the competing node. It is considered to be a relay device. One disclosed embodiment is a relay device that relays communication of a first network (NW1) and communication of a second network (NW2), comprising: an information acquisition unit (11, 12) that acquires contention-related information including information indicating at least one of an increase or decrease in the number of communication nodes in a contention state and a change in communication quality requested by the communication nodes in a contention state as a change in a contention state of communication by a plurality of communication nodes (Nd) connected to the first network; and an information acquisition unit (11, 12) that transmits an acceptance notice including information of a competing node, which is another communication node in a contention state, to a request source node as a communication node that is a request source of a request related to the change in the contention state, and and a notification sending unit (13) that sends a status change notification based on the acceptance notification and the status change notification to at least one competing node, wherein data communication for sharing the communication capacity of the bottleneck link that determines the upper limit of the communication speed is carried out between the requesting node and the competing node based on the acceptance notification and the status change notification, the information acquiring unit further acquires requested quality information indicating the communication quality requested by the requesting node, and the notification sending unit transmits a status change notification based on the requested quality information of the requesting node to the competing node, and adjusts the communication quality requested by the competing node to a lower level so that the communication capacity of the bottleneck link is shared with the requesting node.

[0007] Also, one disclosed aspect is a relay method for relaying communication of a first network (NW1) and communication of a second network (NW2), comprising: The information includes information indicating at least one of an increase or decrease in the number of communication nodes in a competing state and a change in the communication quality required by the communication nodes in a competing state. Obtain competitive information (S4, S11), Sending an acceptance notification to a requesting node as a communication node that is a requesting source of a request related to a change in a conflict state, the acceptance notification including information of a competing node as another communication node that is in conflict; At least one state change notification based on contention-related information Competitors Send to Node ( S5, S6, S15 ,S17 ) ,and This step includes Based on the acceptance notification and the state change notification, the requesting node and the competing node are caused to carry out data communication in which the communication capacity of the bottleneck link that determines the upper limit of the communication speed is shared. In the step of acquiring contention-related information, priority information indicating a priority set for communication between the communication nodes is further acquired. In the step of transmitting the state change notification, the state change notification including the priority information of the requesting node is transmitted to the competing node. This is considered a relay method. Also, one disclosed aspect is a relay method for relaying communication of a first network (NW1) and communication of a second network (NW2), which acquires contention-related information including information indicating at least one of an increase or decrease in the number of communication nodes in a conflicting state and a change in communication quality requested by the communication nodes in the conflicting state as a change in a conflicting state of communication by a plurality of communication nodes (Nd) connected to the first network (S4, S11), transmits an acceptance notification including information of a competing node, which is another communication node in the conflicting state, to a requesting node as a communication node that is a requesting source of a request related to the change in the conflicting state, and transmits at least one state change notification based on the contention-related information. The method includes the steps of: transmitting a status change notification to the competing node based on the acceptance notification and the status change notification (S5, S6, S15, S17); causing the requesting node and the competing node to carry out data communication for sharing the communication capacity of the bottleneck link that determines the upper limit of the communication speed based on the acceptance notification and the status change notification; in the step of acquiring contention-related information, requested quality information indicating the communication quality requested by the requesting node is further acquired; and in the step of transmitting the status change notification, a status change notification based on the requested quality information of the requesting node is transmitted to the competing node, and the communication quality requested by the competing node is adjusted downward so that the communication capacity of the bottleneck link is shared with the requesting node.

[0008] Another disclosed aspect is a communication device connected to a first network (NW1) in which communication to a second network (NW2) is relayed by a relay node (NR), the communication device including a data transmission unit (33) that transmits data (TD1) to be relayed to the second network toward the relay node, and a state change notification unit (34) that notifies the communication device of a change in a contention state of communication by a plurality of communication nodes (Nd) connected to the first network. The state change notification includes at least priority information indicating the priority of communication of a competing node, which is another communication node in a conflicting state with the own node (NS1). from a relay node; The data transmission unit changes the communication quality that the node requests of the relay node to the same communication quality as that requested by the competing node when the priority of the competing node indicated by the priority information is the same as that of the node. It is considered to be a communication device.

[0009] Also, one disclosed aspect is a communication method for connecting to a first network (NW1) in which communication to a second network (NW2) is relayed by a relay node (NR), the method including transmitting (S3) data (TD1) to be relayed to the second network toward the relay node, and receiving a status change notification indicating a change in a contention state of communication by a plurality of communication nodes (Nd) connected to the first network. a state change notification including at least priority information indicating a priority of communication of a competing node, which is another communication node in a competing state; Obtained from relay node If the priority of the competing node indicated by the priority information is the same as that of the own node, the communication quality that the own node requests from the relay node is changed to the same as the communication quality requested by the competing node. (S5, S7,S101 ,S104 ), and

[0010] In these aspects, before congestion occurs in the second network, information related to a change in the contention state of communication can be grasped by the communication node or communication device through the state change notification. As a result, even when multiple communication nodes are connected to the first network, it is possible to suppress the occurrence of congestion.

[0011] Note that the reference numbers in parentheses above and in the claims are merely examples of corresponding relationships with specific configurations in the embodiments described below, and do not in any way limit the technical scope. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram showing an overall view of a communication relay system according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating a communication scene in which congestion occurs in a comparative example. [Diagram 3] FIG. 2 is a block diagram showing a configuration of a relay device. [Figure 4] FIG. 2 is a block diagram showing a configuration of a communication device. [Diagram 5] 11 is a diagram showing an example of a state change notification transmitted to a first transmitting node, etc. FIG. [Figure 6] 13 is a diagram showing an example of an acceptance notification transmitted to a second transmitting node, etc. [Figure 7] 13 is a flowchart showing details of a notification transmission process performed in a relay node. [Figure 8] 5 is a flowchart showing details of an operation control process performed by the communication device. [Figure 9] FIG. 11 is a sequence diagram showing details of a congestion control process for arbitrating communications by a plurality of communication nodes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A communication system 1 according to an embodiment of the present disclosure shown in Fig. 1 is a client-side system mounted on a moving object such as a vehicle. The communication system 1 transmits and receives data to and from a receiving node NJ that is present outside the moving object. The receiving node NJ is, for example, a server device 70 provided on a cloud. The communication system 1 is configured with a communication device 30, a relay device 100, and the like.

[0014] The communication device 30 is a communication node Nd connected to the first network NW1. The communication device 30 communicates with the relay device 100 via the first network NW1. A plurality of communication devices 30 are connected to the first network NW1. Each communication device 30 is an element that serves as a client with respect to the server device 70. Each communication device 30, as a communication node Nd, transmits and receives data to and from a receiving node NJ.

[0015] The first network NW1 is a wired network. At least a part of the first network NW1 may be a wireless network. That is, the first network NW1 may be a combination of a wired network and a wireless network. When the communication system 1 is an in-vehicle system, an in-vehicle LAN (Local Area Network) becomes the first network NW1. For the in-vehicle LAN, a communication standard such as CAN (Controller Area Network, registered trademark) or Ethernet (registered trademark) is adopted. In the first network NW1, communication is performed using private IP addresses.

[0016] The relay device 100 is connected to the server device 70 (receiving node NJ) via the second network NW2. The relay device 100 functions as a relay node NR that relays communication between the first network NW1 and the second network NW2. The relay device 100 may be capable of communicating with multiple receiving nodes NJ via the second network NW2.

[0017] The second network NW2 is a network equivalent to the WAN (Wide Area Network) side with respect to the first network NW1, which is a LAN side. The second network NW2 is a communication line network that can use the Internet. The second network NW2 includes at least a wireless network in part. In the second network NW2, communication is performed using a global IP address. When the communication system 1 is an in-vehicle system, the second network NW2 includes, for example, a section where cellular communication such as LTE, 5G, and 6G is performed, or a section where communication by wireless LAN (for example, Wi-Fi, a registered trademark) is performed. The function of the relay device 100 is implemented in, for example, an in-vehicle unit called a DCM (Data Communication Module).

[0018] The second network NW2 has lower communication performance than the first network NW1 because it includes a wireless network. Specifically, the communication of the second network NW2 is slower than that of the first network NW1, and the delay is likely to be large. Therefore, when data is transmitted and received between the communication node Nd and the receiving node NJ, a bottleneck link BnL occurs in the second network NW2. The bottleneck link BnL is a communication section that determines the upper limit of the communication speed between the communication node Nd and the receiving node NJ.

[0019] Here, when the communication node Nd communicates with the receiving node NJ, congestion may occur in the bottleneck link BnL of the second network NW2. Hereinafter, an example of a communication scene in which congestion occurs in the bottleneck link BnL will be described based on FIG. 2 and with reference to FIG. 1.

[0020] When a specific communication node Nd (hereinafter, the first transmitting node NS1) communicates with a receiving node NJ, it transmits a communication request to a relay node NR (see S1x communication [1] request). If there is no other communication node Nd that communicates with the receiving node NJ, the first transmitting node NS1 starts transmitting data TD1 to the receiving node NJ by exclusively using the bottleneck link BnL (S2x).

[0021] Furthermore, when a communication node Nd other than the first transmitting node NS1 (hereinafter, the second transmitting node NS2) communicates with the receiving node NJ, it also transmits a communication request to the relay node NR in the same manner as the first transmitting node NS1 (see S3x communication [2] request). If a communication request is made by the second transmitting node NS2 before the first transmitting node NS1 completes the transmission of the data TD1, the second transmitting node NS2 transmits the data TD2 in parallel with the transmission of the data TD1 by the first transmitting node NS1 (S4x). In this case, the first transmitting node NS1 and the second transmitting node NS2 become communication nodes Nd that compete with each other. If the total amount of transmission data of the data TD1 and TD2 exceeds the capacity of the bottleneck link BnL, the relay node NR cannot smoothly transmit the data TD1 and TD2 to the receiving node NJ. In this way, congestion occurs in the bottleneck link BnL. When congestion occurs, a decrease in communication speed, an increase in delay, and a disconnection are caused.

[0022] In order to avoid the occurrence of congestion as described above, a congestion control function is implemented in the communication system 1. Hereinafter, the details of the configurations of the relay device 100 and the communication device 30 and the congestion control function in the communication system 1 will be described with reference to Figs. 1, 3 and 4.

[0023] [Repeater] The relay device 100 includes a first communication unit 21, a second communication unit 22, a storage unit 23, and a control unit 10 (see FIG. 3). The first communication unit 21 is a wired communication interface that communicates with a plurality of communication nodes Nd (communication devices 30) via a first network NW1. The second communication unit 22 is a wireless communication interface that communicates with at least one receiving node NJ (server device 70) via a second network NW2. The storage unit 23 is a non-volatile memory such as a flash memory. The storage unit 23 stores a program (relay program) executed by the control unit 10 and data for relay processing.

[0024] The control unit 10 has a first acquisition unit 11, a second acquisition unit 12, a first transmission unit 13, a second transmission unit 14, and a relay processing unit 15 (see FIG. 3). These elements may be provided as hardware, or may be functional units constructed by software (relay program).

[0025] The first acquisition unit 11 cooperates with the first communication unit 21 to grasp the communication state of the first network NW1 and acquire information from the first network NW1. The first acquisition unit 11 acquires a communication request requesting data relay to the second network NW2 and transmission data to be relayed to the second network NW2 from a communication node Nd connected to the first network NW1. In addition, the first acquisition unit 11 acquires contention-related information and priority information.

[0026] The contention-related information is information related to a change in a contention state of communication by a plurality of communication nodes Nd connected to the first network NW1. A contention state of communication is a state in which a plurality of communication nodes Nd transmit transmission data relayed to the second network NW2 in parallel. A change in a contention state includes an increase or decrease (appearance or disappearance) of the communication nodes Nd in a contention state, and a change in the communication quality required by the communication nodes Nd in a contention state. Therefore, the contention-related information includes change detection information that detects the occurrence of an increase or decrease in the communication nodes Nd in a contention state or a change in the required communication quality, and change prediction information that predicts the occurrence of an increase or decrease in the communication nodes Nd in a contention state or a change in the required communication quality.

[0027] As described above, the change detection information is information for detecting a change in a competitive state. The change detection information includes a notification of a communication request requesting the start of communication with the receiving node NJ, a notification of communication end indicating the completion of communication with the receiving node NJ, and the like. In addition, the change detection information includes requested quality information. The requested quality information is information indicating the communication quality requested by the communication node Nd to the relay node NR. Furthermore, when the communication quality requested for communication is changed in the communication node Nd, new requested quality information indicating the changed communication quality is acquired by the first acquisition unit 11 as change detection information. As an example, when the requested bandwidth is changed from 5 Mbps to 10 Mbps, the updated requested quality information is notified to the first acquisition unit 11.

[0028] As described above, the change prediction information is information for predicting a change in a conflict state. The change prediction information includes an occurrence notification of an event that leads to the occurrence of communication with the second network NW2. The first acquisition unit 11 acquires a preset event occurrence notification as the change prediction information. The node that is the source of the event occurrence notification does not have to be the communication node Nd that transmits data to the receiving node NJ, that is, the communication node Nd that causes the conflict. When the communication system 1 is an in-vehicle system, for example, an airbag deployment notification and an SOS call switch ON operation notification are preset as event occurrence notifications corresponding to the change prediction information. After the occurrence of these events, a call is made to a call center as a high-priority external communication.

[0029] The priority information is information indicating a priority set for communication. The priority is a relative index defined in advance in the communication system 1, and is not changed in principle. In the relay node NR, when a contention occurs between a plurality of communication nodes Nd, data associated with a high priority is preferentially relayed to the second network NW2. The priority may be set for each communication node Nd, or may be set for each application running in the communication node Nd. Furthermore, the priority may be set in a manner associated with an individual communication. The priority information may be provided from the communication node Nd to the first acquisition unit 11, or may be acquired by a process of reading a priority according to a request source of the communication from a table prepared in advance. In the communication system 1 in which the priority defined for each communication node Nd or each application is changeable, the priority information may be treated as information included in the contention-related information.

[0030] The second acquisition unit 12 cooperates with the second communication unit 22 to grasp the communication state of the second network NW2 and acquire information from the second network NW2. The second acquisition unit 12 acquires transmission data transmitted from a node connected to the second network NW2 to a communication node Nd of the first network NW1. In addition, the second acquisition unit 12 acquires communication state information indicating the communication state of the second network NW2. For example, when a communication speed of the second network NW2 (bottleneck link BnL) decreases in a state in which a plurality of communication nodes Nd transmit data to a receiving node NJ, the contention state may change. Therefore, the communication state information is acquired as contention-related information.

[0031] The communication state information includes information indicating the type of the bottleneck link BnL, and information indicating the communication speed and delay time of the bottleneck link BnL (second network NW2). In addition, information indicating jitter and packet loss occurring in the second network NW2 may be acquired as the communication state information. Furthermore, by combining position information of the vehicle equipped with the communication system 1 with a radio wave map prepared in advance, information predicting a change in the communication state may be acquired as the communication state information.

[0032] The first transmission unit 13 cooperates with the first communication unit 21 to output information to the first network NW1. The first transmission unit 13 transmits the transmission data received by the second acquisition unit 12 to the communication node Nd of the first network NW1. The first transmission unit 13 cooperates with the second acquisition unit 12 to relay data from the second network NW2 to the first network NW1. In addition, the first transmission unit 13 transmits an acceptance notification and a status change notification to the communication node Nd.

[0033] The acceptance notification is transmitted to the communication node Nd that is the request source of the communication request as a reply to the communication request. The acceptance notification is a notification that permits the start of data transmission to the receiving node NJ. If there is no competing communication node Nd, an acceptance notification notifying that there is no competition is transmitted to the requesting communication node Nd. On the other hand, if there is a competing communication node Nd, an acceptance notification (see FIG. 5) including information on the existing competition is transmitted to the requesting communication node Nd.

[0034] The state change notification (see FIG. 6) is transmitted to at least one communication node Nd in a conflict state based on the conflict-related information acquired by the first acquisition unit 11 or the second acquisition unit 12. The state change notification is for notifying the existing communication nodes Nd of an increase or decrease (addition or deletion) of the conflicting communication nodes Nd, a change in the communication quality requested by the conflicting communication nodes Nd, and the occurrence or release of a conflict state caused by a state change of the second network NW2.

[0035] Specifically, the acceptance notice and the status change notice including the information on the existing conflict include information on the reason for the notification, the competitor, the competing application, the priority, the requested bandwidth, and the QoS (Quality of Service) class. In the case of the acceptance notice (see FIG. 5), the reason for the notification describes "there is an existing conflict". The competitor and the competing application describe information for identifying the communication node Nd and the application that are already transmitting data to the receiving node NJ. The priority describes a value (priority information) indicating a priority previously set for the competitor or the competing application. The requested bandwidth and the QoS class describe information (required quality information) indicating the communication quality required by the competitor or the competing application. When there are multiple existing conflicts, information on all the existing conflicts is provided by the acceptance notice.

[0036] On the other hand, in the case of a status change notification (see FIG. 6), the notification reason describes content based on the contention-related information, such as "contention added" and "decrease in communication speed of the second network." The competitor and competing application describe information identifying the communication node Nd or application (source of change) that has been added or whose required communication quality has been changed. The priority describes a value indicating a priority previously set for the competitor or competing application that has been added or whose required quality has been changed. The requested bandwidth and QoS class describe information indicating the latest communication quality required by the competitor or competing application. In the case of a status change notification based on communication status information of the second network NW2, information such as the competitor, competing application, priority, requested bandwidth, and QoS class, except for the notification reason, overlaps with information that has already been notified, and therefore does not need to be notified anew.

[0037] The second transmission unit 14 cooperates with the second communication unit 22 to output information to the second network NW2. The second transmission unit 14 transmits the transmission data received by the first acquisition unit 11 to the receiving node NJ of the second network NW2. The second transmission unit 14 cooperates with the first acquisition unit 11 to relay data from the first network NW1 to the second network NW2.

[0038] The relay processing unit 15 performs data relay processing between the first network NW1 and the second network NW2. The relay processing unit 15 controls data transmission and reception so as to satisfy the communication quality required for the data to be relayed based on the required quality information. In addition, the relay processing unit 15 generates an acceptance notice and a status change notice based on contention-related information and the like. The relay processing unit 15 has a determination unit 16 and a selection unit 17 as functional units related to the transmission of the acceptance notice and the status change notice.

[0039] The determination unit 16 determines whether or not the conflict state will change based on the conflict-related information acquired by the first acquisition unit 11 and the second acquisition unit 12. Specifically, the determination unit 16 uses the above-mentioned change detection information, change prediction information, communication state information, and the like to determine whether or not the conflict state will change.

[0040] The selection unit 17 sets a communication node Nd (notification target node) to which the acceptance notification and the state change notification are to be sent. For example, when a communication node Nd (additional node) that performs data transmission to the receiving node NJ is added, the selection unit 17 selects a notification target node from among other communication nodes Nd that are performing data transmission to the receiving node NJ. Specifically, the selection unit 17 selects a communication node Nd having the same communication priority as the added node and a communication node Nd having a lower communication priority than the added node as notification target nodes.

[0041] The relay device 100 described above successively transmits the acceptance notification and the state change notification by executing the notification transmission process (see FIG. 7) in the control unit 10. The notification transmission process is started based on the reception of contention-related information including a notification of a communication request during the period in which the relay device 100 functions as a relay node NR.

[0042] In S11 of the notification transmission process, the contention-related information that triggered the start of the notification transmission process is obtained, and the process proceeds to S12. In S12, the determination unit 16 determines whether a contention state occurs. Specifically, in S12, in addition to determining whether a new contention state occurs, it also determines whether an existing contention state will change. If a new communication request is obtained in S11 and it is determined in S12 that no contention state has occurred, the process proceeds to S13. In S13, an acceptance notification is transmitted to the communication node Nd that is the source of the communication request, notifying that no contention exists, and the current notification transmission process is terminated.

[0043] On the other hand, if it is determined in S12 that a new conflict state will occur or that a change will occur in the conflict state, the process proceeds to S14. In S14, the selection unit 17 selects the conflicting communication node Nd (conflict destination) as a notification target node based on the priority information, and the process proceeds to S15. In S15, a state change notification (see FIG. 6) based on the conflict-related information acquired in S11 is transmitted to the notification target node (conflict destination communication node Nd) selected in S14, and the process proceeds to S16.

[0044] In S16, it is determined whether or not the contention-related information has been transmitted to all nodes to be notified selected in S14. If multiple nodes to be notified are selected, the contention-related information is transmitted to all nodes to be notified by repeating S15 and S16. Then, if it is determined in S16 that the information has been transmitted to all nodes to be notified, the process proceeds to S17. If a new communication request has been acquired in S11, an acceptance notification (see FIG. 5) including information on the existing contention is transmitted to the communication node Nd that is the request source of the communication request, and the notification transmission process is terminated this time. Note that, if a change in the contention state occurs that does not involve the addition of a competing communication node Nd, the notification in S17 may be omitted.

[0045] [Communication Device] The communication device 30 includes a communication unit 36, a storage unit 37, and a communication control unit 30a (see FIG. 4). The communication unit 36 ​​is a wired communication interface that communicates with the relay node NR and other communication nodes Nd via the first network NW1. The storage unit 37 is a non-volatile memory such as a flash memory. The storage unit 37 stores a program (communication program) executed by the communication control unit 30a and data for communication processing.

[0046] The communication control unit 30a has an application execution unit 31, a reception control unit 32, and a transmission control unit 33 (see FIG. 4). These elements may be provided as hardware, or may be functional units constructed by software (communication programs).

[0047] The application executor 31 executes an application program to cause the communication device 30 to function as a predetermined in-vehicle device. The application executor 31 determines whether to transmit data to the receiving node NJ as necessary. The application executor 31 determines the communication quality required of the relay node NR when transmitting data to the receiving node NJ, specifically, the communication speed to be secured and the allowable delay time, etc. The application executor 31 defines the required bandwidth and QoS class, etc., so that the communication speed and delay time are secured. The application executor 31 can improve the communication speed and delay time of the relay process by the relay node NR by changing the settings of the required bandwidth and QoS class to be increased. The application executor 31 defines at least the desired communication quality and the minimum communication quality that needs to be secured according to the type of data to be transmitted.

[0048] The reception control unit 32 cooperates with the communication unit 36 ​​to acquire information from the first network NW1. The reception control unit 32 receives an acceptance notice and a status change notice from the relay node NR. Based on the acceptance notice, the reception control unit 32 determines whether there is an existing competing communication node Nd. Based on the status change notice, the reception control unit 32 determines a change in the competing status of the first network NW1. As described above, the status change notice includes priority information indicating the priority of communication of another communication node Nd competing with the communication device 30 (its own node), required quality information, and the like (see FIG. 6).

[0049] The transmission control unit 33 cooperates with the communication unit 36 ​​to output information to the first network NW1. The transmission control unit 33 transmits a notification of a communication request to the relay node NR. In addition, the transmission control unit 33 transmits, to the relay node NR, identification information for identifying an application being executed in the own node, requested quality information indicating the communication quality requested by the own node, and the like. The transmission control unit 33 may further transmit priority information of the own node or the application.

[0050] In the communication device 30 described above, when the reception control unit 32 receives a state change notification during data transmission to the receiving node NJ, the communication control unit 30a performs an operation control process (see FIG. 8) to change the data transmission operation. The operation control process will be described in detail below.

[0051] In S101 of the operation control process, the reception control unit 32 acquires a state change notification. In S101, the priority information of the communication node Nd (competitor) described in the acquired state change notification and the required quality information of the competitor are grasped, and the process proceeds to S102. In S102, the transmission control unit 33 compares the priority of the communication of the own node with the priority of the communication of the competitor. The transmission control unit 33 changes the data transmission operation in steps S104 to S106 according to the relationship between the two priorities.

[0052] If it is determined in S102 that the priority of the competitor is the same as that of the own node, the process proceeds to S104. In S104, the transmission control unit 33 decides to perform data transmission through cooperative operation. In this case, in S107, the transmission control unit 33 changes the communication quality required by the own node to the same level as the communication quality required by the competitor based on the status change notification. The transmission control unit 33 changes the required bandwidth to deal with delays, changes the QoS class (policy), etc. Then, it transmits requested quality information indicating the updated communication quality to the relay node NR. As a result, the communication capacity of the bottleneck link BnL is shared equally between the own node and the competitor.

[0053] The transmission control unit 33 may change the communication quality required by the node itself to be lower than that of the competitor. In this case, the updated required quality information is notified to the competitor, and the required communication quality of the competitor is adjusted to the same level as that of the node itself. As a result, the communication capacity of the bottleneck link BnL may be shared equally between the node itself and the competitor.

[0054] On the other hand, if it is determined in S102 that the priority of the competitor is higher than the own node, the process proceeds to S103. In S103, the transmission control unit 33 determines whether or not it is possible to continue data transmission by cooperative operation. For example, if the priority of the competitor is significantly higher than the priority of the own node, or if the communication quality of the bottleneck link BnL is extremely degraded, it is determined in S103 that cooperative operation is not possible, and the process proceeds to S106.

[0055] In S106, the transmission control unit 33 decides to perform a standby operation. In this case, data transmission to the receiving node NJ is temporarily stopped. When a state change notification indicating the disappearance of a competing node is acquired, the transmission control unit 33 ends the standby operation and resumes data transmission to the receiving node NJ.

[0056] On the other hand, if it is determined in S103 that cooperative operation is possible, the process proceeds to S105. In S105, the transmission control unit 33 decides to perform data transmission through cooperative operation with priority given to the competitor. In this case, in S107, the transmission control unit 33 changes the required communication quality of the own node to a value lower than the required communication quality of the competitor, and transmits the updated required quality information toward the relay node NR. As a result, the communication capacity of the bottleneck link BnL is shared between the competitor and the own node, with priority given to the competitor.

[0057] Note that even if it is decided to perform the cooperative operation in S104 or S105, if the minimum required communication quality defined by the application executing unit 31 cannot be ensured, the transmission control unit 33 can switch to a standby operation.

[0058] [Congestion control processing] Next, in the communication system 1 described above, a series of congestion control processes for arbitrating data communications will be described in detail with reference to Fig. 9, taking as an example a communication scene in which two communication nodes Nd sequentially start transmitting data to a receiving node NJ. In the following description, as in the comparative example, the communication node Nd that starts data transmission first is referred to as the "first transmitting node NS1", and another communication node Nd that starts data transmission after the first transmitting node NS1 is referred to as the "second transmitting node NS2". The second transmitting node NS2 corresponds to the above-mentioned additional node.

[0059] The first transmitting node NS1 transmits a communication request to the relay node NR (see S1 Communication [1] Request). In addition to the communication request, the first transmitting node NS1 transmits requested quality information indicating a desired communication quality determined by the application executing unit 31 to the relay node NR. If there is no other communication node Nd that communicates with the receiving node NJ, the relay node NR transmits an acceptance notification to the first transmitting node NS1 notifying that no contention exists (S2).

[0060] Based on receiving the acceptance notification from the relay node NR, the first transmitting node NS1 starts transmitting the data TD1 to be relayed to the second network NW2 to the relay node NR (S3). The relay node NR transmits the data TD1 received from the first transmitting node NS1 to the receiving node NJ at a communication speed and delay time that satisfy the communication quality requested by the first transmitting node NS1.

[0061] After the first transmitting node NS1 starts data transmission, the second transmitting node NS2 transmits a communication request to the relay node NR (see S4 Communication [2] Request). Like the first transmitting node NS1, the second transmitting node NS2 also transmits required quality information indicating the desired communication quality determined by the application executor 31 to the relay node NR together with a notification of the communication request.

[0062] The relay node NR compares the priority of communication of the first transmitting node NS1 with the priority of communication of the second transmitting node NS2. If the priority of the second transmitting node NS2 to be added is equal to or higher than the priority of the first transmitting node NS1, the relay node NR transmits a state change notification to the first transmitting node NS1 (S5).

[0063] Based on the state change notification, the first transmitting node NS1 changes the communication quality requested to the communication node Nd. Specifically, based on the above-mentioned operation control process, the first transmitting node NS1 grasps the communication priority of the competing second transmitting node NS2 from the priority information attached to the state change notification. The first transmitting node NS1 changes the transmission operation to a standby operation, a cooperative operation, or the like, depending on the relationship between the communication priority of the node itself and the communication priority of the second transmitting node NS2 (see S104 to S106 in FIG. 8). As a result, the first transmitting node NS1 can continue the transmission of the data TD1, for example, with the requested communication quality appropriately lowered (S7). At this time, the first transmitting node NS1 may notify the relay node NR of the requested quality information after the change (see S107 in FIG. 8).

[0064] Based on the quality requirement information of the competing second transmitting node NS2, the first transmitting node NS1 may change to a higher QoS class to prevent delays, or may change to a cheaper QoS class to avoid a worsening of the performance-cost ratio. If the priority of the second transmitting node NS2 is lower than the priority of the first transmitting node NS1, the first transmitting node NS1 does not transmit a state change notification. In this case, the first transmitting node NS1 continues transmitting the data TD1 without changing the transmission operation.

[0065] After transmitting the status change notification to the first transmitting node NS1, the relay node NR transmits an acceptance notification (see FIG. 5) including information on the existing contention (first transmitting node NS1) to the second transmitting node NS2 (S6). The relay node NR may include the original requested quality information of the first transmitting node NS1 in the acceptance notification, or may include the requested quality information updated based on the status change notification in the acceptance notification.

[0066] The second transmitting node NS2 grasps the priority of the first transmitting node NS1 attached to the acceptance notification, and determines the transmission operation according to the relationship between the communication priority of its own node and the communication priority of the first transmitting node NS1. When the second transmitting node NS2 determines to perform a cooperative operation, it refers to the required quality information of the first transmitting node NS1 and changes the communication quality requested by its own node. As a result, the second transmitting node NS2 starts transmitting the data TD2 with the requested communication quality lowered from the desired communication quality (S8). The second transmitting node NS2 may notify the relay node NR of the changed required quality information. At this time, the relay node NR may transmit the updated required quality information of the second transmitting node NS2 to the first transmitting node NS1.

[0067] [Summary of this embodiment] According to the present embodiment described above, information related to a change in the contention state of communication can be grasped by the communication node Nd through the state change notification before congestion occurs in the second network NW2. As a result, even when multiple communication nodes Nd are connected to the first network NW1, it is possible to suppress the occurrence of congestion.

[0068] Specifically, according to the above congestion control process (see FIG. 9), the first transmitting node NS1 and the second transmitting node NS2, which are in a conflicting state, become aware of each other's presence through the conflict state notification and the acceptance notification, and then transmit the data TD1 and TD2 to the receiving node NJ. As a result, the first transmitting node NS1 and the second transmitting node NS2 can transmit data in a manner that does not cause congestion in the bottleneck link BnL, and therefore can appropriately share the communication capacity of the bottleneck link BnL. As a result, the occurrence of congestion can be suppressed.

[0069] Additionally, in this embodiment, communication state information indicating the state of communication in the second network NW2 is used to determine whether or not the contention state changes in the determination unit 16. Therefore, even in a form in which the communication state of the second network NW2 changes due to, for example, the communication system 1 being mounted on a mobile body, arbitration of communication between the multiple communication nodes Nd functions, making it possible to avoid the occurrence of congestion.

[0070] In this embodiment, priority information indicating the priority set for the communication of the second transmitting node NS2 is acquired by the relay node NR. Then, a state change notification including the priority information of the second transmitting node NS2 is transmitted from the relay node NR to the first transmitting node NS1. Therefore, even if the congestion control function is distributed from the relay node NR to each communication node Nd, the first transmitting node NS1 can grasp the importance of the data transmitted by the second transmitting node NS2 and appropriately change the transmission operation of the own node. As a result, data transmission that effectively utilizes the capacity of the bottleneck link BnL while suppressing the occurrence of congestion can be realized.

[0071] Furthermore, in this embodiment, among the multiple communication nodes Nd, a communication node Nd having the same or lower communication priority as a specific communication node Nd is selected as a notification target node. Then, the first transmission unit 13 transmits a state change notification including priority information to the selected notification target node. As described above, if the transmission target of the state change notification is determined based on the priority, the adjustment of the transmission operation for congestion avoidance is performed only for the communication node Nd related to the contention. Therefore, even if the congestion control function is distributed to each communication node Nd, the arbitration of data transmission can be smoothly performed without increasing the processing load of the communication node Nd that transmits data of high importance.

[0072] Additionally, in this embodiment, the relay node NR acquires requested quality information indicating the communication quality required by the communication node Nd as contention-related information. Then, for example, in a communication scene in which the second transmitting node NS2 is added, the first transmitting unit 13 transmits a state change notification based on the requested quality information of the second transmitting node NS2 to the first transmitting node NS1, which is the existing communication node Nd. Therefore, the first transmitting node NS1 can timely and appropriately change the communication quality required by itself in accordance with the change in the contention state based on the contents of the state change notification. As a result, the first transmitting node NS1 and the second transmitting node NS2 can appropriately share the capacity of the bottleneck link BnL while avoiding the occurrence of congestion by changing their respective transmission operations.

[0073] In this embodiment, when the required quality information of a communication node Nd is changed, the relay node NR transmits a state change notification based on the changed required quality information to a communication node Nd other than the communication node Nd whose required quality information is changed. For example, when the required quality information of the first transmitting node NS1 is changed, the relay node NR transmits a state change notification based on the changed required quality information to the second transmitting node NS2. As a result, the first transmitting node NS1 and the second transmitting node NS2 can grasp each other's required communication quality and appropriately adjust the transmission operation of their own nodes. As a result, the first transmitting node NS1 and the second transmitting node NS2 can perform efficient data transmission while avoiding the occurrence of congestion in the bottleneck link BnL.

[0074] Furthermore, in this embodiment, change prediction information for predicting a change in the conflict state is acquired as conflict-related information. Then, a state change notification based on the change prediction information is transmitted to the communication node Nd connected to the first network NW1. According to the above, for example, in a communication scene in which a communication node Nd is added, a change in transmission operation by the existing communication node Nd can be implemented before new traffic occurs. As a result, it becomes possible to smoothly start transmission of data of high importance, such as communication related to an SOS call.

[0075] In addition, in the communication node Nd of this embodiment, the communication quality required of the relay node NR is changed based on the state change notification. Therefore, even if the congestion control function is distributed from the relay node NR to each communication node Nd, the amount of data transmitted from each communication node Nd can be appropriately suppressed. As a result, the capacity of the bottleneck link BnL is appropriately shared by multiple communication nodes Nd while avoiding the occurrence of congestion.

[0076] Furthermore, in this embodiment, the state change notification provided to the first transmitting node NS1 includes priority information indicating the priority of the communication of the second transmitting node NS2 competing with the first transmitting node NS1. Then, the first transmitting node NS1 changes the transmission operation according to the relationship between the priority of the communication by the own node and the priority of the communication by the second transmitting node NS2. As a result, the first transmitting node NS1 can grasp the importance of the data transmitted by the second transmitting node NS2 and appropriately change the transmission operation of the own node. As a result, data transmission that effectively utilizes the capacity of the bottleneck link BnL while suppressing the occurrence of congestion can be realized.

[0077] In the above embodiment, the first acquisition unit 11 and the second acquisition unit 12 correspond to an "information acquisition unit", the first transmission unit 13 corresponds to a "notification transmission unit", the reception control unit 32 corresponds to a "notification acquisition unit", and the transmission control unit 33 corresponds to a "data transmission unit". In addition, the first transmission node NS1 corresponds to a "notification target node" and the "own node", and the second transmission node NS2 corresponds to a "specific communication node" and a "competing node".

[0078] (Other embodiments) Although one embodiment of the present disclosure has been described above, the present disclosure should not be construed as being limited to the above embodiment, and can be applied to various embodiments and combinations within the scope not departing from the gist of the present disclosure.

[0079] In the above embodiment, the relay node NR acquires the requested bandwidth and QoS class from a specific communication node Nd as contention-related information, incorporates this information into a state change notification, and provides it to other communication nodes Nd. However, the manner of the state change notification based on the contention-related information is not limited to the above. For example, the relay node NR may specify the communication quality of each communication node Nd and request adjustment to the specified communication quality in the state change notification.

[0080] More specifically, in the first modification of the above embodiment, the relay node NR refers to the requested bandwidth and QoS class acquired from a specific communication node Nd, and sets the requested bandwidth and QoS class to be proposed to the other communication nodes Nd. The relay node NR transmits a state change notification including the set requested bandwidth and QoS class to the other communication nodes Nd. The other communication nodes Nd refer to the received state change notification, and reflect the requested bandwidth and QoS class proposed by the relay node NR in data transmission by the own node.

[0081] In the second modification of the above embodiment, the relay node NR incorporates the requested bandwidth and QoS class acquired from a specific communication node Nd into the first state change notification to be transmitted to other communication nodes Nd, as in the above embodiment. If the arbitration between the communication nodes Nd is not successful and congestion occurs in the bottleneck link BnL, the relay node NR sets the requested bandwidth and QoS class to be proposed to the communication nodes Nd in the competing state, and requests each communication node Nd to change its data transmission operation.

[0082] Furthermore, the status change notification in the third modification of the above embodiment includes only the notification reason, the competitor, and the competing application. That is, the priority information and the required quality information of the competitor are omitted from the status change notification. Note that, if the priority of communication is defined not on an application basis but on a communication node Nd basis, the information on the competing application may also be deleted from the status change notification. Also, the communication quality of each communication may be defined by an index other than the required bandwidth and the QoS class.

[0083] In the above embodiment, when another traffic (see data TD2 in FIG. 9) occurs that has a priority equal to or higher than that of the existing communication node Nd, the change in the contention state is notified to the existing communication node Nd by a state change notification. However, the trigger for sending the state change notification may be changed as appropriate. For example, in the fourth modification of the above embodiment, the relay node NR sends a state change notification only when it is expected that the contention state will worsen.

[0084] In the fifth modification of the above embodiment, only a status change notification related to an increase or decrease in the number of communication nodes Nd is transmitted. That is, a status change notification related to a change in the required quality information and a status change notification related to a change in the communication status of the second network NW2 are not transmitted.

[0085] In the above embodiment, the relay node NR transmits a state change notification to communication nodes Nd having a priority equal to or lower than the priority of the communication node Nd to be added as a standard. However, the selection of notification target nodes based on priority may be omitted. For example, in the sixth modification of the above embodiment, the relay node NR transmits a state change notification to all communication nodes Nd that are transmitting data to the receiving node NJ, regardless of priority. According to the above, the processing load of the relay node NR can be further reduced.

[0086] In the above embodiment, the process of preventing congestion of data TD1, TD2 transmitted from multiple communication nodes Nd to the receiving node NJ has been described. However, the relay node NR may implement control to avoid congestion of data transmitted from the server device 70 to multiple communication nodes Nd. In this case, each communication node Nd changes the communication quality required for the received data based on the state change notification. As a result, for example, the bit rate of the received data of video content is adjusted to a lower value, thereby preventing a significant deterioration of the user experience.

[0087] In the seventh modification of the above embodiment, the second network NW2 is also a private network like the first network NW1. As in the seventh modification, the relay node NR may be an element that relays communication between different private networks. Furthermore, the communication system 1 is not limited to being mounted on a moving object, and may be used within a specific facility.

[0088] In the above embodiment, each function provided by the relay device 100 and the communication device 30 can be provided by software and hardware that executes the software, software alone, hardware alone, or a combination of these. Furthermore, when such a function is provided by an electronic circuit as hardware, each function can also be provided by a digital circuit including a large number of logic circuits, or an analog circuit.

[0089] Each of the control units 10, 30a in the above embodiment has a processing unit coupled to a RAM. The processing unit is hardware for arithmetic processing, and is the main component of a computer that executes a program to realize the relay method and the communication method according to the present disclosure. Such a processing unit includes at least one arithmetic core such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). The processing unit may further include an FPGA (Field-Programmable Gate Array), an NPU (Neural network Processing Unit), and an IP core having other dedicated functions. The processing unit may be individually mounted on a printed circuit board, or may be mounted on an ASIC (Application Specific Integrated Circuit) and an FPGA. Furthermore, each of the storage units 23, 37 is not limited to being provided on a circuit board, and may be provided in the form of a memory card or the like, inserted into a slot, and electrically connected to the processing circuit of each of the control units 10, 30a.

[0090] The control unit and the method described herein may be implemented by a special-purpose computer having a processor programmed to execute one or more functions embodied in a computer program. Alternatively, the device and the method described herein may be implemented by a special-purpose hardware logic circuit. Alternatively, the device and the method described herein may be implemented by one or more special-purpose computers configured by a combination of a processor that executes a computer program and one or more hardware logic circuits. The computer program may also be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by the computer. [Explanation of symbols]

[0091] 11 first acquisition unit (information acquisition unit), 12 second acquisition unit (information acquisition unit), 13 first transmission unit (notification transmission unit), 16 judgment unit, 17 selection unit, 30 communication device, 32 reception control unit (notification acquisition unit), 33 transmission control unit (data transmission unit), 100 relay device, Nd communication node, NR relay node, NS1 first transmission node (notification target node, own node), NS2 second transmission node (specific communication node, contention node), NW1 first network, NW2 second network, TD1 data

Claims

1. A relay device that relays communication between a first network (NW1) and a second network (NW2), an information acquisition unit (11, 12) that acquires contention-related information including information indicating at least one of an increase or decrease in the number of communication nodes in the contention state and a change in communication quality required by the communication nodes in the contention state as a change in a contention state of communication by a plurality of communication nodes (Nd) connected to the first network; a notification sending unit (13) that sends an acceptance notification including information of a competing node, which is another communication node in the competing state, to a request source node as the communication node that is a request source of a request related to a change in the competing state, and sends a state change notification based on the competition-related information to at least one of the competing nodes; data communication for sharing a communication capacity of a bottleneck link that determines an upper limit of a communication speed is performed between the requesting node and the competing node based on the acceptance notification and the state change notification; the information acquisition unit acquires priority information indicating a priority set for communication of the request source node; The notification transmission unit is a relay device that transmits the state change notification, which includes the priority information of the requesting node, to the competing node.

2. a selection unit (17) that selects, from among the competing nodes, a competing node having the same communication priority as the request source node or a lower communication priority than the request source node, as a notification target node (NS1); The relay device according to claim 1 , wherein the notification transmission unit transmits the state change notification including the priority information to the notification target node selected by the selection unit.

3. A relay device that relays communication between a first network (NW1) and a second network (NW2), an information acquisition unit (11, 12) that acquires contention-related information including information indicating at least one of an increase or decrease in the number of communication nodes in the contention state and a change in communication quality required by the communication nodes in the contention state as a change in a contention state of communication by a plurality of communication nodes (Nd) connected to the first network; a notification sending unit (13) that sends an acceptance notification including information of a competing node, which is another communication node in the competing state, to a request source node as the communication node that is a request source of a request related to a change in the competing state, and sends a state change notification based on the competition-related information to at least one of the competing nodes; data communication for sharing a communication capacity of a bottleneck link that determines an upper limit of a communication speed is performed between the requesting node and the competing node based on the acceptance notification and the state change notification; The information acquisition unit further acquires required quality information indicating a communication quality required by the request source node; The notification sending unit sends the status change notification based on the required quality information of the requesting node to the competing node, and adjusts the communication quality requested by the competing node to a lower level so as to share the communication capacity of the bottleneck link with the requesting node.

4. The relay device according to claim 3 , wherein the notification sending unit sends the state change notification based on the changed requested quality information to the requesting node when the requested quality information indicating the communication quality required by the competing node is changed.

5. A determination unit (16) for determining whether the conflict state changes, The information acquisition unit acquires communication status information indicating a communication status of the second network, The relay device according to claim 1 , wherein the determination unit uses the communication state information to determine whether the conflict state changes.

6. A relay method for relaying communication of a first network (NW1) and a second network (NW2), comprising: acquiring contention-related information including information indicating at least one of an increase or decrease in the number of communication nodes in the contention state and a change in communication quality required by the communication nodes in the contention state as a change in the contention state of communication by a plurality of communication nodes (Nd) connected to the first network (S4, S11); transmitting an acceptance notification including information of other competing nodes, which are the communication nodes in the competing state, to a requesting node, which is the communication node that is the requesting source of a request related to the change in the competing state, and transmitting a state change notification based on the competition-related information to at least one of the competing nodes (S5, S6, S15, S17); having the requesting node and the competing node carry out data communication to share a communication capacity of a bottleneck link that determines an upper limit of a communication speed, based on the acceptance notice and the state change notice; The step of acquiring the contention-related information further includes acquiring priority information indicating a priority to be set for communication of the communication node; In the step of transmitting the state change notification, the state change notification including the priority information of the requesting node is transmitted to the competing node.

7. A relay method for relaying communication of a first network (NW1) and a second network (NW2), comprising: acquiring contention-related information including information indicating at least one of an increase or decrease in the number of communication nodes in the contention state and a change in communication quality required by the communication nodes in the contention state as a change in the contention state of communication by a plurality of communication nodes (Nd) connected to the first network (S4, S11); transmitting an acceptance notification including information of other competing nodes, which are the communication nodes in the competing state, to a requesting node, which is the communication node that is the requesting source of a request related to the change in the competing state, and transmitting a state change notification based on the competition-related information to at least one of the competing nodes (S5, S6, S15, S17); having the requesting node and the competing node carry out data communication to share a communication capacity of a bottleneck link that determines an upper limit of a communication speed, based on the acceptance notice and the state change notice; The step of acquiring contention-related information further includes acquiring required quality information indicating a communication quality requested by the requesting node; In the step of sending the state change notification, the state change notification based on the required quality information of the requesting node is sent to the competing node, and the relay method adjusts the communication quality requested by the competing node to a lower level so as to share the communication capacity of the bottleneck link with the requesting node.

8. A communication device connected to a first network (NW1) in which communication to a second network (NW2) is relayed by a relay node (NR), a data transmission unit (33) that transmits data (TD1) to be relayed to the second network toward the relay node; a notification acquisition unit (32) that acquires from the relay node a state change notification related to a change in a contention state of communication by a plurality of communication nodes (Nd) connected to the first network, the state change notification including at least priority information indicating a priority of communication between the node (NS1) and a competing node that is the other communication node in the contention state; The data transmission unit is a communication device that, when the priority of the competing node indicated by the priority information is the same as that of the own node, changes the communication quality that the own node requests from the relay node to be the same as the communication quality requested by the competing node.

9. A communication method for connecting to a first network (NW1) in which communication to a second network (NW2) is relayed by a relay node (NR), comprising: Transmitting data (TD1) to be relayed to the second network to the relay node (S3); a state change notification indicating a change in a competitive state of communication by a plurality of communication nodes (Nd) connected to the first network is acquired from the relay node, the state change notification including at least priority information indicating the priority of communication of a competing node, which is the other communication node in the competitive state, and when the priority of the competing node indicated by the priority information is the same as that of the own node, the communication quality requested by the own node to the relay node is changed to be the same as the communication quality requested by the competing node (S5, S7, S101, S104); A communication method comprising the steps of:

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