Communication system, wide-area monitoring and control system, first communication device, second communication device, communication method, and communication program

Abstract

To provide a communication system capable of improving fault tolerance when multiple faults occur in a ring-shaped wired communication path to which multiple communication devices are connected.SOLUTION: A communication system 8 having a wired communication network 2 and a wireless communication network 3 includes multiple first communication devices for transmitting data acquired from connected devices and a second communication device to which a device that collects data is connected. The multiple first communication devices and the second communication device are connected by a ring-shaped wired communication path. When breakage of the wired communication path is detected between the first communication device and the second communication device, the first communication device whose wired communication path has been broken with the second communication device or the second communication device determines a representative communication device that transmits data to the second communication device by wireless communication, among from a first communication device group to which the first communication device whose wired communication path has been broken with the second communication device is connected by wire.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a communication system including a plurality of communication devices, a wide area monitoring and control system, a communication device, a communication method, and a communication program.

Background Art

[0002] Conventionally, in a wide area monitoring and control system for monitoring and controlling rivers, roads, railways, etc., in order to achieve efficient monitoring, high reliability, real-time performance, etc., a communication system in which a plurality of communication devices are connected by a ring-type optical communication path is used. In such a communication system, a certain communication device A can communicate with a communication device B as a communication partner through two paths, clockwise and counterclockwise, of the ring-type optical communication path. Therefore, even if a communication failure occurs in one path of the ring-type optical communication path, the communication device A can continue communication with the communication device B by using the other path. However, if a multiple failure occurs in the ring-type optical communication path and a communication failure also occurs in the other path, resulting in the path being disconnected, the communication device A will not be able to continue communication with the communication device B.

[0003] Regarding such a problem, Patent Document 1 discloses a technique in which, in a communication system in which a plurality of communication devices are connected by a ring-type optical communication path, when a communication device detects a disconnection of the optical communication path due to a multiple failure, it continues communication by performing wireless communication with other communication devices.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the conventional technology described above, it is assumed that in a situation where many of the communication devices among several devices are unable to operate due to power supply failure, and only a few communication devices are operational, the operational communication devices will communicate wirelessly with each other. However, if multiple failures occur in a ring-shaped optical communication path, but most of the communication devices are operational, there is a possibility that many communication devices will attempt to communicate wirelessly. Therefore, depending on the wireless communication system used, congestion may occur, potentially leading to unstable wireless communication.

[0006] This disclosure is made in view of the above, and aims to provide a communication system that can improve fault tolerance when multiple failures occur in a ring-shaped wired communication path to which multiple communication devices are connected. [Means for solving the problem]

[0007] To solve the above-mentioned problems and achieve the objectives, this disclosure provides a communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path. The communication system comprises a plurality of first communication devices, which are communication devices that transmit data acquired from connected devices, and a second communication device, which is a communication device to which a data collection device is connected. The plurality of first and second communication devices are connected by a ring-shaped wired communication path, and if a disconnection of the wired communication path is detected between the first and second communication devices, the first communication device whose wired communication path is disconnected from the second communication device... and A group of first communication devices, in which the second communication device and the first communication device, whose wired communication path is separated, are connected by a wired communication path. This is the first group of communication devices. From there, a representative transmits data to the second communication device via wireless communication over a wireless communication network. First Determine the communication device. At that time, the communication quality of the wireless communication between the first and second communication devices is measured, and based on the communication quality of the first group of communication devices, a representative first communication device that directly transmits data wirelessly to the second communication device is determined. It is characterized by the following: [Effects of the Invention]

[0008] According to this disclosure, the communication system has the effect of improving fault tolerance when multiple failures occur in a ring-shaped wired communication path to which multiple communication devices are connected. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example configuration of a wide-area monitoring and control system equipped with a communication system according to Embodiment 1. [Figure 2] A diagram showing an example configuration of a communication device according to Embodiment 1. [Figure 3] This figure shows an example of a method for resolving ring disruption via wireless communication when multiple faults occur in the wired communication network in the communication system according to Embodiment 1. [Figure 4] This figure shows an example of measurement results for the communication quality of wireless communication shared by a first group of communication devices that are separated into rings, in the communication system according to Embodiment 1. [Figure 5] Flowchart showing the operation of the communication device according to Embodiment 1 [Figure 6] This figure shows an example of the configuration of a processing circuit when the processing circuit for realizing the communication device according to Embodiment 1 is implemented using a processor and memory. [Figure 7] This figure shows an example of the configuration of a processing circuit when the processing circuit for realizing the communication device according to Embodiment 1 is implemented using dedicated hardware. [Figure 8] This figure shows an example of a method for resolving ring disruption via wireless communication when multiple faults occur in the wired communication network in the communication system according to Embodiment 2. [Figure 9] Flowchart showing the operation of the communication device according to Embodiment 2 [Figure 10] This figure shows an example of a method for resolving ring disruption via wireless communication when multiple faults occur in the wired communication network in the communication system according to Embodiment 3. [Figure 11] This figure shows an example of a method for resolving ring disruption by wireless communication when multiple faults occur in the wired communication network in the communication system according to Embodiment 4. [Figure 12]This figure shows an example of slice mapping information set in the communication device according to Embodiment 4. [Modes for carrying out the invention]

[0010] The following describes in detail, with reference to the drawings, the communication system, wide-area monitoring and control system, communication device, communication method, and communication program according to the embodiments of this disclosure.

[0011] Embodiment 1. Figure 1 shows an example configuration of a wide-area monitoring and control system 9 equipped with a communication system 8 according to Embodiment 1. The communication system 8 has a wired communication network 2 with a ring-shaped wired communication path to which multiple communication devices 1-1 to 1-16 are connected, and a wireless communication network 3. In other words, the communication system 8 is a system in which the wired communication network 2 and the wireless communication network 3 are co-located. The communication system 8 is also a system equipped with communication devices 1-1 to 1-16. In the following description, communication devices 1-1 to 1-16 may be referred to as communication device 1 when not distinguished. The wide-area monitoring and control system 9 is a system equipped with the communication system 8, in which equipment such as a display control panel 4, a camera 6, and a controller 7 are connected to one of the communication devices 1. In the example of the wide-area monitoring and control system 9 shown in Figure 1, the display control panel 4 is connected to communication device 1-1, the camera 6 is connected to communication device 1-11, and the controller 7 is connected to communication device 1-12.

[0012] In the wide-area monitoring and control system 9, the communication device 1-1 and the display control panel 4 constitute the center 5. The center 5 performs centralized monitoring in the wide-area monitoring and control system 9 using the data acquired from devices such as the camera 6 and the controller 7. Therefore, in the center 5, the communication device 1-1 collects data on the monitoring results indicating the state of the monitoring target, etc. from devices such as the camera 6 and the controller 7 connected to other communication devices 1, and outputs it to the display control panel 4. The display control panel 4 displays the image, which is the data obtained by the camera 6, the control state by the controller 7, etc. to the monitor who monitors the state of the monitoring target in the center 5, and accepts the shooting direction of the camera 6, the control information for the controller 7, etc. from the monitor. Note that the display control panel 4 may be composed of a plurality of devices such as a display panel and a control panel.

[0013] In the present embodiment, when the monitoring target of the wide-area monitoring and control system 9 is a railway, the camera 6 monitors the facilities along the railway, etc., and the controller 7 performs control of the facilities along the line, etc. Note that the monitoring target of the wide-area monitoring and control system 9 is not limited to a railway, and may be a road, a river, etc. Also, the monitoring devices connected to the communication device 1 are not limited to the camera 6 and the controller 7, and may be other devices. The monitoring devices connected to the communication device 1 may be, for example, a wind speed meter, a rain gauge, a seismometer, etc. Devices corresponding to the monitoring target of the wide-area monitoring and control system 9 are connected to the communication device 1. Hereinafter, the case where the monitoring target of the wide-area monitoring and control system 9 is a railway will be assumed and described.

[0014] Although the description is simplified in the example of FIG. 1, in reality, devices such as cameras 6 and controllers 7 are also connected to communication devices 1-2 to 1-10, 1-13 to 1-16. Also, in the example of FIG. 1, the number of devices connected to one communication device 1 is one, but it is not limited to this. The communication device 1 can connect a plurality of devices. In the following description, communication devices 1-2 to 1-16 to which devices such as cameras 6 and controllers 7 are connected and which transmit data obtained from the devices to the communication device 1-1 of the center 5 are referred to as the first communication devices, and the communication device 1-1 that collects data from other communication devices 1-2 to 1-16 for the display control panel 4 in the center 5 may be referred to as the second communication device. That is, among the plurality of communication devices 1-1 to 1-16, communication devices 1-2 to 1-16 other than the communication device 1-1 which is the second communication device are the first communication devices. The first communication device is the communication device 1 that transmits data acquired from the connected devices. The second communication device is the communication device 1 to which the device for collecting data is connected.

[0015] The wired communication network 2 is a network by a ring-shaped wired communication path to which a plurality of communication devices 1-1 to 1-16 are connected. In the present embodiment, the wired communication network 2 assumes an optical communication network, and the wired communication path assumes an optical cable that transmits an optical signal, but it is not limited to this. The wired communication network 2 is a network that transmits an electrical signal, and the wired communication path may be a cable that transmits an electrical signal. In the wired communication network 2, the number of communication devices 1 connected by the ring-shaped wired communication path is not limited to 16, and may be 15 or less, or may be 17 or more.

[0016] The wireless communication network 3 is a network in which communication devices 1 can communicate with each other by wireless communication. The wireless communication network 3 is, for example, the fifth-generation mobile communication system or the like, but is not limited to this. The wireless communication network 3 may be an existing system other than the fifth-generation mobile communication system or may not be an existing system as long as it is a system capable of high speed, low latency, and a large number of simultaneous connections.

[0017] Communication devices 1-1 to 1-16 are communication devices capable of wired communication via the wired communication network 2 and wireless communication via the wireless communication network 3. Communication devices 1-1 to 1-16 are, for example, L2 switches. Each communication device 1 to 1-16 is assigned unique identification information that can identify each communication device 1. The identification information for each communication device 1 can be set, for example, by a DIP (Dual In-line Package) switch provided on each communication device 1, but is not limited to this method. Communication devices 1-2 to 1-16 are configured, for example, via a CLI (Command Line Interface), to identify communication device 1-1 as communication device 1 of the center 5. Normally, communication devices 1-1 to 1-16 send and receive data on the wired communication network 2, which is redundant in a ring topology. Even if a failure occurs at one point in the wired communication network 2, and wired communication becomes impossible at the point of failure, communication devices 1-1 to 1-16 can continue wired communication by using a route that bypasses the point of failure. However, if a failure occurs in two or more locations in the wired communication network 2, i.e., if multiple failures occur, some of the communication devices 1-2 to 1-16 will be unable to transmit data to the communication device 1-1 in the center 5 via wired communication.

[0018] For example, in the example in Figure 1, if a communication failure occurs between communication devices 1-6 and 1-7, and between communication devices 1-11 and 1-12, communication devices 1-7 to 1-11 will be unable to transmit data to communication device 1-1 in center 5 via wired communication. In this case, it is possible for all communication devices 1-7 to 1-11 to transmit data to communication device 1-1 in center 5 via wireless communication through the wireless communication network 3, but the more communication devices 1 whose wired communication with communication device 1-1 in center 5 is disrupted, the greater the traffic for data transmission in the wireless communication network 3. Also, if the wireless communication network 3 is a metered network, the more communication devices 1 that use the wireless communication network 3 for wireless communication, the greater the billing cost.

[0019] Therefore, in this embodiment, if multiple communication devices 1 become unable to transmit data to the communication device 1-1 of the center 5 via wired communication due to multiple failures in the wired communication network 2, and if the communication devices 1 that are unable to transmit data to the communication device 1-1 of the center 5 via wired communication are able to communicate with each other via wired communication, the communication device 1 is determined to transmit data to the communication device 1-1 of the center 5 via wireless communication on behalf of the others. As a result, even if multiple failures occur in the wired communication network 2, the communication system 8 can minimize the number of communication devices 1 that transmit data wirelessly to the communication device 1-1 of the center 5, thereby suppressing an increase in traffic on the wireless communication network 3, and also suppressing billing costs if the wireless communication network 3 is metered.

[0020] Next, the configuration and operation of communication device 1 will be described. Note that communication devices 1-1 to 1-16 have the same configuration. Figure 2 is a diagram showing an example of the configuration of communication device 1 according to Embodiment 1. Communication device 1 comprises wired communication units 11 and 12, a wired communication control unit 13, a wireless communication unit 14, a device connection unit 15, a transfer processing unit 16, and a switching control unit 17.

[0021] The wired communication units 11 and 12 are wired communication interfaces that perform wired communication with adjacent communication devices 1 via the wired communication network 2. The wired communication units 11 and 12 perform wired communication with adjacent communication devices 1 via the wired communication path. For example, if the communication device 1 shown in Figure 2 is communication device 1-11, then one of the wired communication units 11 and 12 performs wired communication with communication device 1-10, and the other performs wired communication with communication device 1-12.

[0022] The wired communication control unit 13 controls wired communication based on the wired communication path. The wired communication control unit 13 performs control based on the RPR (Resilient Protection Ring) protocol, a ring control protocol standardized by IEEE (Institute of Electrical and Electronics Engineers) 802.17. For example, in the event of a single failure in the wired communication network 2, the wired communication control unit 13 performs wired communication via a detour path in 50 msec or less. The wired communication control unit 13 also performs topology detection within the ring using a topology discovery function. The wired communication control unit 13 can determine, using its own communication device as a reference, how many hops away each communication device 1 is connected in a clockwise direction on the wired communication network 2, and how many hops away each communication device 1 is connected in a counterclockwise direction on the wired communication network 2. The wired communication control unit 13 can recognize the location of a failure in the wired communication network 2 if a failure occurs on the wired communication network 2.

[0023] The wireless communication unit 14 communicates wirelessly with other communication devices 1 via the wireless communication network 3. However, if there is no failure in the wired communication network 2 and the wired communication units 11 and 12 are transmitting and receiving data, the wireless communication unit 14 may be turned OFF. This allows the communication device 1 to reduce the power consumption of the wireless communication unit 14 when there is no failure in the wired communication network 2.

[0024] The device connection unit 15 is an interface that can be connected to devices such as the display control panel 4, camera 6, and controller 7. The device connection unit 15 can, for example, be connected to these devices via a LAN (Local Area Network). The device connection unit 15 transfers data transmitted and received via wired or wireless communication to and from the connected devices.

[0025] The transfer processing unit 16 performs the transfer processing of frames containing data. For example, the transfer processing unit 16 of the first communication devices, communication devices 1-2 to 1-16, transfers frames acquired from devices connected to the device connection unit 15 to the wired communication control unit 13 or the wireless communication unit 14. Also, the transfer processing unit 16 of the second communication device, communication device 1-1 of center 5, transfers frames received by the wired communication control unit 13 or the wireless communication unit 14 to the display control panel 4 via the device connection unit 15. The transfer processing unit 16 handles the exchange of data between the wired communication control unit 13 or the wireless communication unit 14 and the device connection unit 15.

[0026] The switching control unit 17 controls whether to transmit data via wired communication or wireless communication. Specifically, the switching control unit 17 controls the measurement of wireless communication quality by the wireless communication unit 14, the determination of which communication device 1 will transmit data wirelessly on behalf of the communication device 1-1 of the center 5 in the event of multiple failures in the wired communication network 2, switching from wired communication to wireless communication when transmitting and receiving data by communication device 1, and switching from wireless communication to wired communication when transmitting and receiving data by communication device 1. Note that the measurement of wireless communication quality is performed by the wireless communication unit 14, and the switching control unit 17 may obtain the measurement results of the wireless communication quality from the wireless communication unit 14.

[0027] Next, the operation of communication device 1 when a multiple fault occurs in the wired communication network 2 will be described. In this embodiment, among the communication devices 1 that detect a ring split in wired communication with communication device 1-1 of the center 5, the communication device 1 with the best wireless communication quality with communication device 1-1 of the center 5 will perform wireless communication with communication device 1-1 of the center 5 as a representative to resolve the ring split. Figure 3 is a diagram showing an example of a method for resolving a ring split by wireless communication when a multiple fault occurs in the wired communication network 2 in the communication system 8 according to Embodiment 1. Figure 3 shows an example in which a fault occurs between communication devices 1-6, 1-7 and between communication devices 1-11, 1-12 of the wired communication network 2, i.e., a multiple fault occurs. Note that some descriptions in Figure 3 are simplified compared to Figure 1.

[0028] If a multiple fault occurs in the wired communication network 2 as shown in Figure 3, communication devices 1-7 to 1-11 detect, through topology discovery by the wired communication control unit 13, that wired communication via the wired communication network 2 is impossible between the first group of communication devices, which are divided into rings, and communication device 1-1 at the center 5. If the wireless communication unit 14 is OFF, communication devices 1-7 to 1-11 turn it ON, establish a wireless communication path with communication device 1-1 at the center 5, and measure at least one of the following as the communication quality of the wireless communication with communication device 1-1: RSSI (Received Signal Strength Indicator), SINR (Signal to Interference and Noise Ratio), frame error rate, and throughput. Communication devices 1-7 to 1-11 share the measurement results of the wireless communication quality among themselves by sending and receiving the measurement results of the wireless communication quality using control frames. Based on the measurement results of the wireless communication quality of communication devices 1-7 to 1-11, the communication device 1 with the best wireless communication quality is determined to be the representative communication device 1.

[0029] Figure 4 shows an example of measurement results for the communication quality of wireless communication shared by communication devices 1-7 to 1-11, which are a first group of communication devices divided into a ring, in the communication system 8 according to Embodiment 1. In Figure 4, RSSI, SINR, frame error rate, and throughput are shown as measurement results for the communication quality of wireless communication at communication devices 1-7 to 1-11. For example, communication devices 1-7 to 1-11 evaluate whether the RSSI and SINR are above a specified threshold, and whether the frame error rate is below a specified threshold. Communication devices 1-7 to 1-11 determine the communication device 1 with the highest throughput among the communication devices 1 that meet the requirements for each threshold as representative communication device 1. In the example in Figures 3 and 4, communication devices 1-7 to 1-11 determine communication device 1-9 as representative communication device 1. Based on this result, communication devices 1-7 to 1-8, 1-10 to 1-11 terminate the wireless communication path that they had established with communication device 1-1 of the center 5 for measuring the communication quality of wireless communication. Communication system 8 resolves ring disruption due to multiple failures with the minimum necessary wireless communication paths by bypassing communications such as monitoring and control between communication devices 1-7 to 1-11 through the wireless communication path of the representative communication device 1-9.

[0030] The operation of communication device 1 will be explained using a flowchart. Figure 5 is a flowchart showing the operation of communication device 1 according to Embodiment 1. In communication device 1, if the wired communication control unit 13 does not detect that wired communication is impossible with communication device 1-1 of the center 5, which is the second communication device, due to ring division (step S101: No), it continues to monitor the status of wired communication. If it detects that wired communication is impossible with communication device 1-1, which is the second communication device, due to ring division (step S101: Yes), the switching control unit 17 turns on the wireless communication unit 14 (step S102). The switching control unit 17 measures the communication quality of the wireless communication between the center 5 and communication device 1-1 in the wireless communication unit 14 (step S103). Note that in the example in Figure 3, communication device 1-1 of the center 5 has detected that wired communication is impossible with communication devices 1-7 to 1-11 due to ring division, so it may turn on the wireless communication unit 14 after detection, or it may keep the wireless communication unit 14 ON at all times in preparation for unforeseen circumstances. The switching control unit 17 notifies other communication devices 1 of the measurement results of the wireless communication quality via the wired communication control unit 13 and wired communication units 11 and 12 (step S104). Communication devices 1-7 to 1-11 can send and receive the measurement results of the wireless communication quality using control frames.

[0031] The switching control unit 17 waits if the measurement of the communication quality of the wireless communication of the other communication device 1 is not yet complete (step S105: No). The switching control unit 17 can determine whether the measurement is complete or not based on whether or not it has received notification of the measurement results of the wireless communication quality from the other communication device 1. If the measurement of the communication quality of the wireless communication of the other communication device 1 is complete (step S105: Yes), the switching control unit 17 determines the representative communication device 1 to perform wireless communication (step S106). If the switching control unit 17 is the representative communication device 1 (step S107: Yes), it controls the wireless communication unit 14 to transmit data wirelessly, and the wireless communication unit 14 transmits data wirelessly (step S108). If the switching control unit 17 is not the representative communication device 1 (step S107: No), it turns off the wireless communication unit 14 (step S109).

[0032] In this embodiment, when multiple failures occur in the wired communication network 2 as shown in Figure 3, communication devices 1-7 to 1-11 determine a representative communication device 1 to communicate wirelessly with communication device 1-1 of center 5, but this is not limited to this. When communication devices 1-7 to 1-11 measure the communication quality of wireless communication between their own communication device and communication device 1-1 of center 5, communication device 1-1 of center 5 can also measure the communication quality of wireless communication between communication device 1-1 of center 5 and communication devices 1-7 to 1-11. Therefore, communication device 1-1 of center 5 may determine a representative communication device 1 from communication devices 1-7 to 1-11 based on the communication quality of wireless communication between communication device 1-1 of center 5 and communication devices 1-7 to 1-11, and notify communication devices 1-7 to 1-11 of the determined representative communication device 1.

[0033] In this way, the wired communication control unit 13 of the communication device 1 detects a disconnection in the wired communication path of the wired communication network 2 between the first communication device, which is a communication device 1 that transmits data, and the second communication device, which is a communication device 1 to which a data collection device is connected. In this case, the switching control unit 17 of the first or second communication device whose wired communication path with the second communication device has been disconnected determines a representative communication device 1 from the group of first communication devices to which the first communication device whose wired communication path with the second communication device has been disconnected is wired via a wired communication path, to transmit data to the second communication device wirelessly. Specifically, the switching control unit 17 of the group of first communication devices measures the communication quality of the wireless communication with the second communication device and, based on the communication quality of the group of first communication devices, determines a representative communication device 1 to directly transmit data to the second communication device wirelessly. Alternatively, the switching control unit 17 of the second communication device measures the communication quality of the wireless communication with the first group of communication devices, and based on the communication quality, determines a representative communication device 1 to directly transmit data wirelessly to the second communication device.

[0034] Next, the hardware configuration of the communication device 1 according to Embodiment 1 will be described. In the communication device 1, the wired communication units 11 and 12 are interfaces for performing wired communication such as optical communication. The wireless communication unit 14 is an interface for performing wireless communication. The device connection unit 15 is an interface for connecting to devices via LAN connection or the like. The wired communication control unit 13, the transfer processing unit 16, and the switching control unit 17 are implemented by processing circuits. The processing circuit may be a memory for storing programs and a processor for executing the programs stored in the memory, or it may be dedicated hardware. The processing circuit is also called a control circuit.

[0035] Figure 6 shows an example of the configuration of a processing circuit 90 when the processing circuit for realizing the communication device 1 according to Embodiment 1 is realized by a processor 91 and a memory 92. The processing circuit 90 shown in Figure 6 is a control circuit and comprises a processor 91 and a memory 92. When the processing circuit 90 is composed of a processor 91 and a memory 92, each function of the processing circuit 90 is realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 92. In the processing circuit 90, each function is realized by the processor 91 reading and executing the program stored in the memory 92. In other words, the processing circuit 90 includes a memory 92 for storing a program that will ultimately be executed as processing for the communication device 1. This program can also be said to be a program that causes the communication device 1 to execute each function realized by the processing circuit 90. This program may be provided by a storage medium on which the program is stored, or by other means such as a communication medium.

[0036] The above program includes a wired communication step that performs wired communication with an adjacent communication device 1 via a wired communication path, a wired communication control step that controls wired communication via the wired communication path, a wireless communication step that performs wireless communication with other communication devices 1, and a switching control step that controls whether to transmit data via wired communication or wireless communication. In the wired communication control step, if a disconnection of the wired communication path is detected between a first communication device, which is a communication device that transmits data, and a second communication device, which is a communication device to which a data collection device is connected, the switching control step can be described as a program that causes the communication device 1 to perform the following actions: the first communication device or the second communication device whose wired communication path has been disconnected from the second communication device, to determine a representative communication device 1 from the group of first communication devices to which the first communication device whose wired communication path has been disconnected from the second communication device is wired via a wired communication path, which device will transmit data wirelessly to the second communication device.

[0037] Here, the processor 91 is, for example, a CPU (Central Processing Unit), processing unit, arithmetic unit, microprocessor, microcomputer, or DSP (Digital Signal Processor). The memory 92 is, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (Registered Trademark) (Electrically EPROM), magnetic disks, flexible disks, optical disks, compact disks, minidiscs, or DVDs (Digital Versatile Discs).

[0038] Figure 7 shows an example of the configuration of a processing circuit 93 when the processing circuit for realizing the communication device 1 according to Embodiment 1 is implemented using dedicated hardware. The processing circuit 93 shown in Figure 7 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The processing circuit 93 may be partially implemented with dedicated hardware and partially implemented with software or firmware. In this way, the processing circuit 93 can realize each of the above-mentioned functions using dedicated hardware, software, firmware, or a combination thereof.

[0039] As described above, according to this embodiment, if multiple communication devices 1 become unable to transmit data via wired communication to the communication device 1-1 of the center 5 due to multiple failures in the wired communication network 2, and if the communication devices 1 that are unable to transmit data via wired communication to the communication device 1-1 of the center 5 are able to communicate with each other via wired communication, the communication system 8 determines which communication device 1 will transmit data wirelessly on behalf of the others to the communication device 1-1 of the center 5. In this embodiment, the communication device 1 with good wireless communication quality with the communication device 1-1 of the center 5 becomes the representative communication device 1. As a result, even if multiple failures occur in the wired communication network 2, the communication system 8 can minimize the number of communication devices 1 that perform wireless communication to the communication device 1-1 of the center 5, thereby suppressing an increase in traffic on the wireless communication network 3, and if the wireless communication network 3 is metered, it can suppress billing costs. In this way, the communication system 8 can improve fault tolerance when multiple failures occur in the wired communication network 2 of a ring-shaped wired communication path to which multiple communication devices 1 are connected.

[0040] Furthermore, the wide-area monitoring and control system 9, equipped with such a communication system 8, can continue monitoring at the center 5 even if multiple failures occur in the communication device 1, wired communication network 2, etc. The wide-area monitoring and control system 9 can also remotely monitor failures occurring in the communication device 1, wired communication network 2, etc., from the center 5. In addition, the wide-area monitoring and control system 9 can be operated for a long period of time by taking measures such as repairing or replacing the faulty communication device 1, etc., as needed.

[0041] Embodiment 2. In Embodiment 1, the communication device 1 that directly communicates wirelessly with the communication device 1-1 of Center 5 was determined from among the communication devices 1-7 to 1-11 whose wired communication via the wired communication network 2 was disrupted. However, depending on the installation locations of the communication devices 1-7 to 1-11, the distance between the communication devices 1-7 to 1-11 and the communication device 1-1 of Center 5 may be large, and the desired wireless communication quality may not be obtained. Embodiment 2 describes a case in which, at the endpoint communication device 1 of the first group of communication devices that detected the ring disruption of wired communication with the communication device 1-1 of Center 5, the communication quality of wireless communication between the communication device 1 and the communication device 1 near the ring is measured, and the endpoint communication device 1 with better communication quality constructs a bypass route via wireless communication, thereby resolving the ring disruption due to multiple faults.

[0042] In Embodiment 2, the configuration of the wide-area monitoring and control system 9 equipped with the communication system 8 is the same as the configuration of the wide-area monitoring and control system 9 equipped with the communication system 8 in Embodiment 1 shown in Figure 1. Also, in Embodiment 2, the configuration of the communication device 1 is the same as the configuration of the communication device 1 in Embodiment 1 shown in Figure 2. Figure 8 is a diagram showing an example of a method for resolving ring division by wireless communication when multiple faults occur in the wired communication network 2 in the communication system 8 according to Embodiment 2. In Figure 8, as in the case of Figure 3, an example is shown in which faults occur between communication devices 1-6, 1-7 and between communication devices 1-11, 1-12 of the wired communication network 2, i.e., multiple faults occur. Note that in Figure 8, some descriptions are simplified compared to Figure 1.

[0043] If a multiple fault occurs in the wired communication network 2 as shown in Figure 8, communication devices 1-7 and 1-11 detect, through topology discovery by the wired communication control unit 13, that wired communication via the wired communication network 2 is impossible between the first group of communication devices, which are divided into rings, communication devices 1-7 to 1-11, and communication device 1-1 at the center 5, and detect that their own communication devices are communication devices 1 at both ends of communication devices 1-7 to 1-11. Communication device 1-7 turns on the wireless communication unit 14 if it is OFF, establishes a wireless communication path with the nearby communication device 1-6, and measures at least one of RSSI, SINR, frame error rate, and throughput as the communication quality of the wireless communication with communication device 1-1. Similarly, communication device 1-11 turns on the wireless communication unit 14 if it is OFF, establishes a wireless communication path with the nearby communication device 1-12, and measures at least one of RSSI, SINR, frame error rate, and throughput as the communication quality of the wireless communication with communication device 1-1.

[0044] Here, the nearest communication device 1 is the communication device 1 that is connected to the wired communication network 2 under normal circumstances and has a low hop count in the direction of the path that has been divided due to the occurrence of multiple failures. For example, since communication device 1-7 was originally connected to communication device 1-6 by wired communication via the wired communication network 2, it can be expected that its installation location is closer to that of the other communication devices 1. As described above, communication device 1-7 attempts to establish a wireless communication path with communication device 1-6, but if it is unable to establish a wireless communication path, it attempts to establish a wireless communication path with communication device 1-5. Subsequently, communication device 1-7 attempts to establish a wireless communication path by changing communication device 1 until it is possible to establish a wireless communication path. The same applies to communication device 1-11. Communication devices 1-7 and 1-11 share the communication quality measurement results between them by sending and receiving the measurement results using control frames. Based on the measurement results of the communication quality of communication devices 1-7 and 1-11, communication device 1 with the best communication quality is determined to be the representative communication device 1.

[0045] In the example shown in Figure 8, communication devices 1-7 and 1-11 determine that communication device 1-7 has a throughput of 5.0 Gbps and communication device 1-11 has a throughput of 3.0 Gbps, so communication device 1-7 is designated as representative communication device 1. Based on this result, communication device 1-11 terminates the wireless communication path that it had established with communication device 1-12 for measuring the communication quality of wireless communication. Communication system 8 reroutes communications such as monitoring and control between communication devices 1-7 to 1-11 through the wireless communication path between representative communication device 1-7 and communication device 1-6, thereby eliminating ring disruption due to multiple faults with the minimum necessary wireless communication paths.

[0046] The operation of communication device 1 will be explained using a flowchart. Figure 9 is a flowchart showing the operation of communication device 1 according to Embodiment 2. In communication device 1, if the wired communication control unit 13 does not detect that wired communication with communication device 1-1, which is the second communication device, is impossible due to ring division (step S201: No), it continues to monitor the status of wired communication. If the wired communication control unit 13 detects that wired communication with communication device 1-1, which is the second communication device, is impossible due to ring division (step S201: Yes), it determines whether its own communication device is communication device 1 at the ring-divided endpoint (step S202). If the wired communication control unit 13 is not communication device 1 at the ring-divided endpoint (step S202: No), it terminates its operation. If the own communication device is communication device 1 at the ring-divided endpoint (step S202: Yes), the switching control unit 17 turns on the wireless communication unit 14 (step S203). The switching control unit 17 measures the communication quality of the wireless communication between the wireless communication unit 14 and the nearby communication device 1 (step S204).

[0047] In addition, communication devices 1-6 and 1-12 detect that wired communication is impossible between communication device 1-1 at center 5 and communication devices 1-7 to 1-11 due to ring division in the example in Figure 8, and turn on the wireless communication unit 14 after detection. Communication devices 1-4 and 1-5, which have fewer hops from communication device 1-7, and communication devices 1-13 and 1-14, which have fewer hops from communication device 1-11, may also have the wireless communication unit 14 turned on. The switching control unit 17 notifies the communication device 1 at the opposite endpoint of the measurement result of the wireless communication quality via the wired communication control unit 13 and the wired communication units 11 and 12 (step S205). Communication devices 1-7 and 1-11 can send and receive the measurement result of the wireless communication quality using control frames.

[0048] If the switching control unit 17 has not completed measuring the communication quality of the wireless communication of the communication device 1 at the reverse endpoint (step S206: No), it waits. The switching control unit 17 can determine whether the measurement is complete or not based on whether or not it has received notification of the measurement results of the wireless communication quality from the communication device 1 at the reverse endpoint. If the switching control unit 17 has completed measuring the communication quality of the wireless communication of the communication device 1 at the reverse endpoint (step S206: Yes), it determines the representative communication device 1 to perform wireless communication (step S207). If the switching control unit 17 is the representative communication device 1 (step S208: Yes), it controls the wireless communication unit 14 to transmit data wirelessly, and the wireless communication unit 14 transmits data wirelessly (step S209). If the switching control unit 17 is not the representative communication device 1 (step S208: No), it turns off the wireless communication unit 14 (step S210).

[0049] In this manner, the switching control unit 17 of the first communication device located at both ends of the first communication device group measures the communication quality of wireless communication between it and the adjacent first communication device whose wired communication via the wired communication path has been interrupted. Based on the communication quality of the first communication device located at both ends of the first communication device group, the switching control unit 17 of the first communication device located at both ends of the first communication device group determines a representative communication device 1 that will indirectly transmit data to the second communication device by transmitting data wirelessly to the adjacent first communication device whose wired communication via the wired communication path has been interrupted.

[0050] As described above, according to this embodiment, if multiple communication devices 1 become unable to transmit data to the communication device 1-1 of the center 5 via wired communication due to multiple failures in the wired communication network 2, and if the communication devices 1 that are unable to transmit data to the communication device 1-1 of the center 5 via wired communication are able to communicate with each other via wired communication, the communication system 8 determines which communication device 1 will transmit data to the communication device 1-1 of the center 5 via wireless communication on behalf of the others. In this embodiment, the communication device 1 with good wireless communication quality with a nearby communication device 1 becomes the representative communication device 1. Even in this case, the communication system 8 and the wide-area monitoring and control system 9 can obtain the same effects as in Embodiment 1.

[0051] Embodiment 3. Embodiment 3 describes a case where Embodiment 1 and Embodiment 2 are combined.

[0052] In Embodiment 3, the configuration of the wide-area monitoring and control system 9 equipped with the communication system 8 is the same as the configuration of the wide-area monitoring and control system 9 equipped with the communication system 8 in Embodiment 1 shown in Figure 1. Also, in Embodiment 3, the configuration of the communication device 1 is the same as the configuration of the communication device 1 in Embodiment 1 shown in Figure 2. Figure 10 is a diagram showing an example of a method for resolving ring division by wireless communication when multiple faults occur in the wired communication network 2 in the communication system 8 according to Embodiment 3. In Figure 10, as in the cases of Figures 3 and 8, an example is shown in which faults occur between communication devices 1-6, 1-7 and between communication devices 1-11, 1-12 of the wired communication network 2, i.e., multiple faults occur. Note that in Figure 10, some descriptions are simplified compared to Figure 1.

[0053] The operation of communication devices 1-7 to 1-11 is as described above. Based on the measurement results of the wireless communication quality between their own communication device and communication device 1-1 of Center 5, the measurement results of the wireless communication quality between communication device 1-7 and communication device 1-6, and the measurement results of the wireless communication quality between communication device 1-11 and communication device 1-12, communication devices 1-7 to 1-11 determine the communication device 1 with the best communication quality as the representative communication device 1.

[0054] In the example shown in Figure 10, communication device 1-7 is determined as representative communication device 1. Based on this result, communication devices 1-7 to 1-11 terminate the wireless communication path they had established with communication device 1-1 of Center 5 for measuring wireless communication quality. Similarly, communication device 1-11 terminates the wireless communication path it had established with communication device 1-12 for measuring wireless communication quality. The communication system 8 reroutes communications such as monitoring and control between communication devices 1-7 to 1-11 through the wireless communication path between representative communication device 1-7 and communication device 1-6, thereby eliminating ring disruption due to multiple faults with the minimum necessary wireless communication paths.

[0055] Although the case of using both the method of Embodiment 1 and the method of Embodiment 2 in combination has been described, the invention is not limited to this. For example, the communication device 1 may first implement the method of Embodiment 1, and if it fails to obtain wireless communication quality that satisfies the threshold shown in Figure 4, it may then implement the method of Embodiment 2.

[0056] In this manner, the switching control unit 17 of the first group of communication devices measures the communication quality of wireless communication with the second communication device. The switching control unit 17 of the first communication devices located at both ends of the first group of communication devices measures the communication quality of wireless communication with an adjacent first communication device whose wired communication via a wired communication path has been interrupted. Based on the communication quality of the first group of communication devices and the communication quality of the first communication devices located at both ends of the first group of communication devices, the switching control unit 17 of the first group of communication devices determines a representative communication device 1 that directly transmits data to the second communication device via wireless communication, or a representative communication device 1 that indirectly transmits data to the second communication device by transmitting data via wireless communication to an adjacent first communication device whose wired communication via a wired communication path has been interrupted.

[0057] As described above, according to this embodiment, if multiple communication devices 1 become unable to transmit data to the communication device 1-1 of the center 5 via wired communication due to multiple failures in the wired communication network 2, and the communication devices 1 that are unable to transmit data to the communication device 1-1 of the center 5 via wired communication are able to communicate with each other via wired communication, the communication system 8 determines which communication device 1 will transmit data wirelessly on behalf of the communication device 1-1 of the center 5. In this embodiment, the representative communication device 1 is determined by using a combination of Embodiment 1 and Embodiment 2. Even in this case, the communication system 8 and the wide-area monitoring and control system 9 can obtain the same effects as in Embodiment 1.

[0058] Embodiment 4. Embodiment 4 describes a case in which priority control using network slicing technology is performed on the wireless communication line between the representative communication device 1 and the communication device 1-1 of the center 5 in the communication system 8.

[0059] Figure 11 shows an example of a method for resolving ring disruption by wireless communication when multiple faults occur in the wired communication network 2 in the communication system 8 according to Embodiment 4. Although the number of communication devices 1 is reduced, the configuration of the wide-area monitoring and control system 9 equipped with the communication system 8 in Embodiment 4 is the same as the configuration of the wide-area monitoring and control system 9 equipped with the communication system 8 in Embodiment 1 shown in Figure 1. Also, the configuration of the communication device 1 in Embodiment 4 is the same as the configuration of the communication device 1 in Embodiment 1 shown in Figure 2. Figure 11 shows an example where faults occur between communication devices 1-3, 1-4 and between communication devices 1-7, 1-8 in the wired communication network 2, i.e., multiple faults occur. Note that in Figure 11, some descriptions of communication devices 1 and others have been simplified.

[0060] In Embodiment 4, the communication device 1 holds slice mapping information, which includes traffic requirements, traffic classification, the corresponding network slice number, and the communication device 1 that transmits and receives data on that network slice. Figure 12 shows an example of slice mapping information set in the communication device 1 according to Embodiment 4. The slice mapping information is common to all communication devices 1 in the ring and is set in advance for each communication device 1. In the example of slice mapping information shown in Figure 12, the traffic of camera 6, which requires high bandwidth, is assigned to slice #1, and the traffic of controller 7, which requires low latency, is assigned to slice #2.

[0061] If a multiple fault occurs in the wired communication network 2 as shown in Figure 11, communication devices 1-4 to 1-7 detect, through topology discovery by the wired communication control unit 13, that wired communication via the wired communication network 2 is impossible between the first group of communication devices, which are ring-divided, communication devices 1-4 to 1-7 and communication device 1-1. Communication devices 1-4 to 1-7 refer to the slice mapping information and find that there is a communication device 1 with a network slice set within the first group of communication devices, which are ring-divided communication devices 1-4 to 1-7. Therefore, for the traffic of controller 7 connected to communication device 1-5, communication device 1-7, as representative communication device 1, transmits it to communication device 1-1 via low-latency slice #2 from the wireless communication unit 14. Similarly, for the traffic of camera 6 connected to communication device 1-4, communication device 1-6, as representative communication device 1, transmits it to communication device 1-1 via wideband slice #1 from the wireless communication unit 14. In this way, the communication system 8 performs traffic priority control on the wireless communication network 3 based on slice mapping information.

[0062] Furthermore, if there is no communication device 1 with a network slice set in the first group of communication devices 1-4 to 1-7 shown in Figure 11, or if there is no communication device 1 with a network slice set for a certain traffic in the first group of communication devices 1-4 to 1-7 shown in Figure 11, the communication system 8 will determine a representative communication device 1 using one of the methods from Embodiment 1 to Embodiment 3.

[0063] Thus, the switching control unit 17 of the communication device 1 determines, if there is a first communication device in the first group of communication devices for which a dedicated virtual network is set up with a second communication device in the wireless communication network 3 for sending and receiving specified data, to be the representative communication device 1 that directly transmits data corresponding to the dedicated virtual network to the second communication device.

[0064] As described above, according to this embodiment, if there is a communication device 1 with a network slice set in the first group of communication devices, the communication system 8 determines a representative communication device 1 according to the slice mapping information. As a result, the communication system 8 can perform priority control in the wireless communication network 3 even if multiple failures occur in the wired communication network 2.

[0065] The configurations shown in the above embodiments are merely examples, and it is possible to combine them with other known technologies, combine different embodiments, and omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of Symbols]

[0066] 1, 1-1 to 1-16 Communication equipment, 2 Wired communication network, 3 Wireless communication network, 4 Display control panel, 5 Center, 6 Camera, 7 Controller, 8 Communication system, 9 Wide-area monitoring and control system, 11, 12 Wired communication unit, 13 Wired communication control unit, 14 Wireless communication unit, 15 Equipment connection unit, 16 Transfer processing unit, 17 Switching control unit.

Claims

1. A communication system having a wired communication network and a wireless communication network using a ring-shaped wired communication path, Multiple first communication devices, which are communication devices that transmit data acquired from connected devices, A second communication device, which is the communication device to which the device for collecting the aforementioned data is connected, Equipped with, Multiple first communication devices and second communication devices are connected by the ring-shaped wired communication path. If a disconnection of the wired communication path is detected between the first communication device and the second communication device, A group of first communication devices, the first communication device whose wired communication path is separated from the second communication device and the first communication device whose wired communication path is separated from the second communication device and the first communication device whose wired communication path is separated from the second communication device, when determining a representative first communication device from the group of first communication devices to transmit the data to the second communication device via wireless communication over the wireless communication network, measures the communication quality of the wireless communication with the second communication device and, based on the communication quality of the group of first communication devices, determines the representative first communication device to directly transmit the data to the second communication device via wireless communication. A communication system characterized by the following features.

2. A communication system having a wired communication network and a wireless communication network with a ring-shaped wired communication path, Multiple first communication devices, which are communication devices that transmit data acquired from connected devices, A second communication device, which is the communication device to which the device for collecting the aforementioned data is connected, Equipped with, Multiple first communication devices and second communication devices are connected by the ring-shaped wired communication path. If a disconnection of the wired communication path is detected between the first communication device and the second communication device, The second communication device, when determining a representative first communication device to transmit the data to the second communication device via wireless communication over the wireless communication network from a group of first communication devices to which the first communication device, whose wired communication path is separated from the second communication device, is wiredly connected via the wired communication path, measures the communication quality of the wireless communication between the second communication device and the group of first communication devices, and, based on the communication quality, determines the representative first communication device to directly transmit the data to the second communication device via wireless communication. A communication system characterized by the following features.

3. A communication system having a wired communication network and a wireless communication network with a ring-shaped wired communication path, Multiple first communication devices, which are communication devices that transmit data acquired from connected devices, A second communication device, which is the communication device to which the device for collecting the aforementioned data is connected, Equipped with, Multiple first communication devices and second communication devices are connected by the ring-shaped wired communication path. If a disconnection of the wired communication path is detected between the first communication device and the second communication device, The first communication device, which has a wired communication path separated from the second communication device, and which is wiredly connected to the second communication device by the wired communication path, is located at both ends of the first communication device group. When determining a representative first communication device from the first communication device group to transmit the data to the second communication device via wireless communication over the wireless communication network, the first communication device measures the communication quality of the wireless communication between it and an adjacent first communication device whose wired communication via the wired communication path has been interrupted, and based on the communication quality of the first communication device located at both ends of the first communication device group, it determines a representative first communication device that indirectly transmits the data to the second communication device by transmitting the data via wireless communication to an adjacent first communication device whose wired communication via the wired communication path has been interrupted. A communication system characterized by the following features.

4. A communication system having a wired communication network and a wireless communication network with a ring-shaped wired communication path, Multiple first communication devices, which are communication devices that transmit data acquired from connected devices, A second communication device, which is the communication device to which the device for collecting the aforementioned data is connected, Equipped with, Multiple first communication devices and second communication devices are connected by the ring-shaped wired communication path. If a disconnection of the wired communication path is detected between the first communication device and the second communication device, A group of first communication devices, the first communication device whose wired communication path is separated from the second communication device and the first communication device whose wired communication path is separated from the second communication device and the first communication device whose wired communication path is separated from the second communication device, when determining a representative first communication device from the group of first communication devices to transmit the data to the second communication device via wireless communication over the wireless communication network, measures the communication quality of the wireless communication between the first communication device and the second communication device. The first communication device located at both ends of the first group of communication devices measures the communication quality of the wireless communication between it and an adjacent first communication device whose wired communication via the wired communication path has been interrupted. The first group of communication devices determines, based on the communication quality of the first group of communication devices and the communication quality of the first communication devices located at both ends of the first group of communication devices, which is the representative first communication device that directly transmits the data to the second communication device via wireless communication, or which is the representative first communication device that indirectly transmits the data to the second communication device by transmitting the data via wireless communication to an adjacent first communication device whose wired communication via the wired communication path has been interrupted. A communication system characterized by the following features.

5. A communication system having a wired communication network and a wireless communication network with a ring-shaped wired communication path, Multiple first communication devices, which are communication devices that transmit data acquired from connected devices, A second communication device, which is the communication device to which the device for collecting the aforementioned data is connected, Equipped with, Multiple first communication devices and second communication devices are connected by the ring-shaped wired communication path. If a disconnection of the wired communication path is detected between the first communication device and the second communication device, When determining a representative first communication device to transmit the data to the second communication device via wireless communication over the wireless communication network from a group of first communication devices to which the first communication device and the second communication device whose wired communication path is separated by the wired communication path are wired together via the wired communication path, if there is a first communication device in the group of first communication devices to which a dedicated virtual network is set up in the wireless communication network for the transmission and reception of the defined data, the first communication device to which the dedicated virtual network is set up is determined as the representative first communication device to directly transmit the data corresponding to the dedicated virtual network to the second communication device. A communication system according to any one of claims 1 to 4.

6. A communication system comprising any one of claims 1 to 5, A wide-area monitoring and control system characterized by the following features.

7. In a communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which multiple communication devices are connected, the first communication device is one of the first communication devices and the second communication device, A wired communication unit that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control unit that controls the wired communication via the wired communication path, A wireless communication unit that performs wireless communication with other communication devices, A switching control unit that controls whether to transmit data via wired communication or wireless communication, Equipped with, When the wired communication control unit detects a disconnection in the wired communication path between the first communication device that transmits the data and the second communication device to which the device that collects the data is connected, The switching control unit of a first group of communication devices, in which the wired communication path between the first communication device and the second communication device is separated, and the first communication device and the second communication device are wired together via the wired communication path, determines from the first group of communication devices a representative first communication device to transmit the data to the second communication device via wireless communication, measures the communication quality of the wireless communication between the first communication device and the second communication device, and determines the representative first communication device to directly transmit the data to the second communication device via wireless communication based on the communication quality of the first group of communication devices. A first communication device characterized by the following:

8. A communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which a plurality of communication devices are connected, wherein the first communication device is one of the first communication device and the second communication device is one of the communication devices, A wired communication unit that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control unit that controls the wired communication via the wired communication path, A wireless communication unit that performs wireless communication with other communication devices, A switching control unit that controls whether to transmit data via wired communication or wireless communication, Equipped with, When the wired communication control unit detects a disconnection in the wired communication path between the first communication device that transmits the data and the second communication device to which the device that collects the data is connected, The switching control unit of a first communication device located at both ends of a first communication device group, which is a first communication device whose wired communication path is interrupted from the second communication device and is wiredly connected to the second communication device via the wired communication path, determines from the first communication device group a representative first communication device to transmit the data to the second communication device via wireless communication, measures the communication quality of the wireless communication between the first communication device and an adjacent first communication device whose wired communication via the wired communication path has been interrupted, and determines the representative first communication device to indirectly transmit the data to the second communication device by transmitting the data via wireless communication to an adjacent first communication device whose wired communication via the wired communication path has been interrupted, based on the communication quality of the first communication devices located at both ends of the first communication device group. A first communication device characterized by the following:

9. A communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which a plurality of communication devices are connected, wherein the first communication device is one of the first communication device and the second communication device is one of the communication devices, A wired communication unit that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control unit that controls the wired communication via the wired communication path, A wireless communication unit that performs wireless communication with other communication devices, A switching control unit that controls whether to transmit data via wired communication or wireless communication, Equipped with, When the wired communication control unit detects a disconnection in the wired communication path between the first communication device that transmits the data and the second communication device to which the device that collects the data is connected, The switching control unit of a first group of communication devices, in which the wired communication path between the first communication device and the second communication device is separated, and the first communication device and the second communication device are wired together via the wired communication path, determines from the first group of communication devices which first communication device will transmit the data to the second communication device via wireless communication, and measures the communication quality of the wireless communication between the first communication device and the second communication device. The switching control unit of the first communication device located at both ends of the first group of communication devices measures the communication quality of the wireless communication between it and an adjacent first communication device whose wired communication via the wired communication path has been interrupted. The switching control unit of the first group of communication devices determines, based on the communication quality of the first group of communication devices and the communication quality of the first communication devices located at both ends of the first group of communication devices, which is the representative first communication device that directly transmits the data to the second communication device via wireless communication, or which is the representative first communication device that indirectly transmits the data to the second communication device by transmitting the data via wireless communication to an adjacent first communication device whose wired communication via the wired communication path has been interrupted. A first communication device characterized by the following:

10. The switching control unit, if a first communication device in the group of first communication devices has a dedicated virtual network established between it and the second communication device in the wireless communication network for the transmission and reception of the defined data, determines the first communication device with the dedicated virtual network established as the representative first communication device that directly transmits the data corresponding to the dedicated virtual network to the second communication device. The first communication device according to any one of claims 7 to 9.

11. A communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which a plurality of communication devices are connected, wherein the second communication device is one of the first and second communication devices that are communication devices, A wired communication unit that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control unit that controls the wired communication via the wired communication path, A wireless communication unit that performs wireless communication with other communication devices, A switching control unit that controls whether to transmit data via wired communication or wireless communication, Equipped with, When the wired communication control unit detects a disconnection in the wired communication path between the first communication device that transmits the data and the second communication device to which the device that collects the data is connected, The switching control unit of the second communication device, when determining a representative first communication device to transmit the data to the second communication device via wireless communication from a group of first communication devices to which the first communication device, whose wired communication path is separated from the second communication device, is wiredly connected via the wired communication path, measures the communication quality of the wireless communication between the first communication device group and the first communication device group, and, based on the communication quality, determines the representative first communication device to directly transmit the data to the second communication device via wireless communication. A second communication device characterized by the following:

12. The switching control unit determines, if the first communication device in the group of first communication devices has a dedicated virtual network set up between it and the second communication device in the wireless communication network for the transmission and reception of the defined data, the first communication device with the dedicated virtual network set up is the representative first communication device that directly transmits the data corresponding to the dedicated virtual network to the second communication device. The second communication device according to feature 11.

13. A communication method for a communication device in a communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which multiple communication devices are connected, A wired communication step that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control step that controls the wired communication via the wired communication path, A wireless communication step that performs wireless communication with other communication devices, A switching control step that controls whether to transmit data via wired communication or wireless communication, Includes, In the wired communication control step, if a disconnection of the wired communication path is detected between the first communication device, which is the communication device that transmits the data, and the second communication device, which is the communication device to which the device that collects the data is connected, In the switching control step, the first group of communication devices, which has a wired communication path separated from the second communication device and is wiredly connected to the second communication device by the wired communication path, determines from the first group of communication devices a representative first communication device to transmit the data to the second communication device via wireless communication, measures the communication quality of the wireless communication with the second communication device, and determines the representative first communication device to directly transmit the data to the second communication device via wireless communication based on the communication quality of the first group of communication devices. A communication method characterized by the following features.

14. A communication method for a communication device in a communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which a plurality of communication devices are connected, A wired communication step that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control step that controls the wired communication via the wired communication path, A wireless communication step that performs wireless communication with other communication devices, A switching control step that controls whether to transmit data via wired communication or wireless communication, Includes, In the wired communication control step, if a disconnection of the wired communication path is detected between the first communication device, which is the communication device that transmits the data, and the second communication device, which is the communication device to which the device that collects the data is connected, In the switching control step, the second communication device, when determining a representative first communication device to transmit the data to the second communication device via wireless communication over the wireless communication network from a group of first communication devices to which the first communication device, whose wired communication path is separated from the second communication device, is wiredly connected via the wired communication path, measures the communication quality of the wireless communication between the second communication device and the group of first communication devices, and determines the representative first communication device to directly transmit the data to the second communication device via wireless communication based on the communication quality. A communication method characterized by the following features.

15. A communication method for a communication device in a communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which a plurality of communication devices are connected, A wired communication step that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control step that controls the wired communication via the wired communication path, A wireless communication step that performs wireless communication with other communication devices, A switching control step that controls whether to transmit data via wired communication or wireless communication, Includes, In the wired communication control step, if a disconnection of the wired communication path is detected between the first communication device, which is the communication device that transmits the data, and the second communication device, which is the communication device to which the device that collects the data is connected, In the switching control step, the first communication device located at both ends of the first communication device group, which is connected by a wired connection between the first communication device and the second communication device, and whose wired communication path is severed from the first communication device, determines from the first communication device group a representative first communication device to transmit the data to the second communication device by wireless communication, measures the communication quality of the wireless communication between the first communication device and the adjacent first communication device whose wired communication via the wired communication path has been interrupted, and determines the representative first communication device to indirectly transmit the data to the second communication device by transmitting the data by wireless communication to the adjacent first communication device whose wired communication via the wired communication path has been interrupted, based on the communication quality of the first communication device located at both ends of the first communication device group. A communication method characterized by the following features.

16. A communication method for a communication device in a communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which a plurality of communication devices are connected, A wired communication step that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control step that controls the wired communication via the wired communication path, A wireless communication step that performs wireless communication with other communication devices, A switching control step that controls whether to transmit data via wired communication or wireless communication, Includes, In the wired communication control step, if a disconnection of the wired communication path is detected between the first communication device, which is the communication device that transmits the data, and the second communication device, which is the communication device to which the device that collects the data is connected, In the switching control step, A group of first communication devices, the first communication device whose wired communication path is separated from the second communication device and the first communication device whose wired communication path is separated from the second communication device and the first communication device whose wired communication path is separated from the first communication device, when determining a representative first communication device from the group of first communication devices to transmit the data to the second communication device via wireless communication, measures the communication quality of the wireless communication between the first communication device and the second communication device. The first communication device located at both ends of the first group of communication devices measures the communication quality of the wireless communication between it and an adjacent first communication device whose wired communication via the wired communication path has been interrupted. The first group of communication devices determines, based on the communication quality of the first group of communication devices and the communication quality of the first communication devices located at both ends of the first group of communication devices, which is the representative first communication device that directly transmits the data to the second communication device via wireless communication, or which is the representative first communication device that indirectly transmits the data to the second communication device by transmitting the data via wireless communication to an adjacent first communication device whose wired communication via the wired communication path has been interrupted. A communication method characterized by the following features.

17. In the switching control step, if there is a first communication device in the group of first communication devices for which a dedicated virtual network is set up with the second communication device in the wireless communication network for the transmission and reception of the defined data, the first communication device for which the dedicated virtual network is set up is determined to be the representative first communication device that directly transmits the data corresponding to the dedicated virtual network to the second communication device. The communication method according to any one of claims 13 to 16.

18. A communication program for a communication device in a communication system having a wired communication network and a wireless communication network via a ring-shaped wired communication path to which multiple communication devices are connected, A wired communication step that performs wired communication with an adjacent communication device via the aforementioned wired communication path, A wired communication control step that controls the wired communication via the wired communication path, A wireless communication step that performs wireless communication with other communication devices, A switching control step that controls whether to transmit data via wired communication or wireless communication, Includes, In the wired communication control step, if a disconnection of the wired communication path is detected between the first communication device, which is the communication device that transmits the data, and the second communication device, which is the communication device to which the device that collects the data is connected, In the switching control step, the first group of communication devices, which has a wired communication path separated from the second communication device and is wiredly connected to the second communication device by the wired communication path, determines from the first group of communication devices a representative first communication device to transmit the data to the second communication device via wireless communication, measures the communication quality of the wireless communication with the second communication device, and determines the representative first communication device to directly transmit the data to the second communication device via wireless communication based on the communication quality of the first group of communication devices. A communication program characterized by having a computer perform a certain action.

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