JP2019161372A - Communication path switching method, wireless communication system, and communication management terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable transmission of content data to more wireless communication terminals in a wireless communication system in which content data is simultaneously transmitted from a transmission source wireless communication terminal to another wireless communication terminal by multi-hop communication. SOLUTION: A method of switching a communication path includes a search step in which a first wireless communication terminal that has detected deterioration or disconnection of communication quality of wireless communication searches for another wireless communication terminal that can be connected by wireless communication. The second wireless communication terminal is connected to another wireless communication terminal that can be connected by wireless communication. The communication path is connected to the first terminal group to which the communication path is connected to the wireless communication terminal of the transmission source. A classification step for classifying into a second terminal group that does not exist, and a terminal group to which the first wireless communication terminal belongs among the classified first terminal group and the second terminal group to which the first wireless communication terminal belongs. A connection step of connecting to one wireless communication terminal included in a different terminal group by wireless communication is executed. [Selection diagram] FIG. 14

Description

  The present invention relates to a communication path switching method, a wireless communication system, and a communication management terminal.

  In a wireless communication system including a plurality of wireless communication terminals, a technique is known in which content data is transmitted simultaneously (for example, by broadcast transmission) from a transmission source wireless communication terminal to another wireless communication terminal by multi-hop communication.

  In a wireless communication system that performs multi-hop communication, a technique is known in which a node station groups other node stations into a plurality of groups based on the strength of received radio waves, and generates a routing table for each group ( For example, see Patent Document 1).

  In a wireless communication system that transmits content data from a transmission source wireless communication terminal to other wireless communication terminals all at once by multi-hop communication, it is not always guaranteed that content data is transmitted to all wireless communication terminals. .

  This is because, for example, when a wireless communication terminal whose wireless communication is disconnected when changing the communication path of multi-hop communication or the like selects a new connection destination, content data can be transmitted to more wireless communication terminals. This is because it is not considered whether or not.

  Thus, in the conventional technology, in a wireless communication system that transmits content data simultaneously from a transmission source wireless communication terminal by multi-hop communication, it is difficult to transmit content data to more wireless communication terminals. It was.

  Embodiments of the present invention have been made in view of the above problems, and in a wireless communication system that simultaneously transmits content data from a transmission source wireless communication terminal to other wireless communication terminals by multi-hop communication. The content data can be transmitted to more wireless communication terminals.

  In order to solve the above-described problem, a communication path switching method according to an embodiment of the present invention is a communication in a wireless communication system that transmits data from a transmission source wireless communication terminal to other wireless communication terminals all at once by multi-hop communication. A search method for switching a route, wherein a first wireless communication terminal that detects deterioration or disconnection of communication quality of wireless communication performing multi-hop communication searches for another wireless communication terminal connectable by the wireless communication And the second wireless communication terminal, based on the search result of the search step, the other wireless communication terminal connectable by the wireless communication is connected to the transmission source wireless communication terminal. A classification step for classifying the first terminal group into a second terminal group in which a communication path is not connected to the transmission source terminal, and the first wireless communication terminal is classified in the classification step. A connection for connecting to one wireless communication terminal included in a terminal group different from the terminal group to which the first wireless communication terminal belongs out of the first terminal group and the second terminal group by the wireless communication And step.

  According to an embodiment of the present invention, in a wireless communication system that transmits content data simultaneously from a transmission source wireless communication terminal to other wireless communication terminals by multi-hop communication, the content data is transmitted to more wireless communication terminals. It can be sent.

It is a figure (1) for demonstrating the millimeter wave radio | wireless communications system which concerns on one Embodiment. It is FIG. (2) for demonstrating the millimeter wave radio | wireless communications system which concerns on one Embodiment. It is a figure for demonstrating the example of the beam forming which concerns on one Embodiment. It is a figure which shows the structural example of the communication system which concerns on one Embodiment. It is a figure which shows the example of the hardware constitutions of the hopping node which concerns on one Embodiment, and an edge node. It is a figure which shows the example of the hardware constitutions of the communication management apparatus which concerns on one Embodiment. It is a figure which shows the example of a function structure of the hopping node which concerns on one Embodiment. It is a figure which shows the example of a function structure of the edge node which concerns on one Embodiment. It is a figure which shows the example of a function structure of the communication management apparatus which concerns on one Embodiment. It is a sequence diagram which shows the example of the registration process of the hopping node which concerns on 1st Embodiment. It is a figure for demonstrating the cutting | disconnection determination which concerns on 1st Embodiment. It is a flowchart which shows the example of a process of the hopping node which concerns on 1st Embodiment. It is a figure which shows the example of the network structure at the time of the cutting | disconnection generation | occurrence | production concerning 1st Embodiment. It is a flowchart which shows the example of the notification process of the connection destination which concerns on 1st Embodiment. It is a figure (1) which shows the image of the information which the communication system concerning a 1st embodiment manages. It is FIG. (2) which shows the image of the information which the communication system which concerns on 1st Embodiment manages. It is a figure which shows the example of the network structure after the path | route switching which concerns on 1st Embodiment. It is a sequence diagram which shows the example of a process of the communication system which concerns on 1st Embodiment. It is a flowchart which shows the example of the notification process of the connection destination which concerns on 2nd Embodiment. It is a figure which shows the example of the updated communication path | route table which concerns on 2nd Embodiment. It is a figure which shows the example of the network structure after the path | route switching which concerns on 2nd Embodiment. It is a sequence diagram which shows the example of a process of the communication system which concerns on 2nd Embodiment. It is a sequence diagram which shows the example of the process of the communication system which concerns on 3rd Embodiment. It is a sequence diagram which shows the example of the starting process of the hopping node which concerns on one Embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Outline of millimeter-wave wireless communication system>
Before describing embodiments of the present invention, an outline of a millimeter wave radio communication system related to each embodiment of the present invention will be described.

  The millimeter-wave wireless communication system is a wireless communication system that performs high-speed data transmission using a millimeter-wave (60 GHz) band that has high radio wave straightness and a relatively narrow communication range. Here, the following description will be given on the assumption that the millimeter-wave wireless communication system is a wireless communication system compliant with IEEE (Institute of Electrical and Electronics Engineers) 802.11ad. IEEE802.11ad is an example of a millimeter wave radio communication system according to the present embodiment.

(Network configuration)
A millimeter-wave wireless communication system compliant with IEEE802.11ad performs communication using a millimeter-wave (60 GHz) band with high straightness of radio waves and a relatively narrow communication range, and uses a wide band of 2.16 GHz per channel. As a result, high-speed data communication is realized.

  Further, since the propagation loss of radio waves increases in the millimeter wave band, in the millimeter wave radio communication system, in order to increase the antenna gain, a beam forming technique for transmitting / receiving radio waves while narrowing the beam direction of radio waves is used. Therefore, basically, it is difficult for the communication unit of the millimeter wave wireless communication system to communicate simultaneously with a plurality of communication devices.

  Therefore, in the millimeter wave wireless communication system, a TDMA (Time Division Multiple Access) communication protocol is used as a wireless multiplexing method instead of the CSMA / CA method used in the conventional wireless LAN (Local Area Network) system. It is done.

  In a millimeter wave radio communication system, a coordinator device called AP (Access Point) forms a network cell called BSS (Basic Service Set), and manages time slots in the TDMA protocol.

  1 and 2 are diagrams for explaining a millimeter-wave wireless communication system according to an embodiment. FIG. 1A illustrates an example of a one-to-one network configuration in which an AP 110 that forms a BSS 100 that is a network cell of a millimeter-wave wireless communication system and a STA (Station) 120 communicate with each other using millimeter-wave wireless communication 130. Show. In the example of FIG. 1A, the AP 110 manages time slots in the TDMA protocol, and transmits beacon frames at predetermined time intervals, for example.

  FIG. 1B shows an example of a star-type network configuration in which the AP 110 forming the BSS 100 and the plurality of STAs 120-1 to 120-3 communicate with each other by the millimeter wave wireless communication 130. Also in the example of FIG. 1B, the AP 110 manages time slots in the TDMA protocol, and transmits beacon frames at predetermined time intervals, for example.

  In IEEE802.11ad, in addition to the network configuration shown in FIGS. 1A and 1B, as shown in FIG. 2A, a PBSS (Personal Basic Service Set) 200 formed by a coordinator device called PCP is used. A network configuration called is defined. In the PBSS 200, the STAs 120-1 to 120-3 can communicate with other STAs via the PCP 201, or can communicate with other STAs without via the PCP 201.

(Time slot configuration)
FIG. 2B is a diagram illustrating an example of a time slot according to an embodiment. FIG. 2B shows time slot allocation in the TDMA protocol managed by the AP 110. The time slot of the TDMA protocol managed by the AP 110 includes a BHI (Beacon Header Interval) and a DTI (Data Transfer Interval) as shown in FIG.

  The BHI includes BTI (Beacon Transmission Interval), A-BFT (Association Beamforming Training), and ATI (Announcement Transmission Interval).

  BTI is a period during which AP 110 transmits a beacon frame. A-BFT is a training period for beamforming. ATI is a period for transmitting and receiving management information, control information, and the like between the AP 110 and the STAs 120-1 to 120-3.

  The DTI includes CBAP (Contention Based Access Period) and SP (Service Period).

  The CBAP is a contention period that is assigned for the AP 110 and a plurality of STAs 120 to compete and perform communication. The SP is a dedicated period allocated for communication between the AP 110 and one STA 120.

  In the BTI, the AP 110 transmits beacon frames by the number of antenna sectors that are a plurality of beam patterns formed by the AP 110. On the other hand, the STAs 120-1 to 120-3 receive all beacon frames transmitted from the AP with the omnidirectional antenna or quasi-omnidirectional antenna set, and send information indicating the antenna sector having the best reception quality to the AP 110. provide feedback. Thereby, AP110 can grasp | ascertain whether it should communicate with each STA120-1-120-3 using an antenna sector.

(Beam forming)
Here, only an outline of SLS (Sector Level Sweep) will be described as an example of the beamforming technique.

  There are two types of SLS: TXSS (Tx Sector Sweep) and RXSS (Rx Sector Sweep). TXSS is beam forming training for determining an antenna sector to be used at the time of transmission, and RXSS is beam forming training for determining an antenna sector to be used at the time of reception.

  FIG. 3 is a diagram for describing an example of beamforming according to an embodiment. In the example of FIG. 3, for ease of explanation, only four antenna sectors of sectors 1 to 4 are shown among the antenna sectors that are a plurality of beam patterns formed by the AP 110.

  In TXSS, the AP 110 forms a BSS 300 by switching each sector (sectors 1 to 4) of the plurality of beam patterns 303 from the antenna 301 and sequentially transmitting predetermined packets. On the other hand, the STA 120 sets the antenna 302 to an omnidirectional antenna or a quasi-omnidirectional antenna, receives a packet transmitted from the AP 110, and feeds back information indicating an antenna sector having the best reception quality to the AP 110.

  In RXSS, a beamforming training sequence in the reverse direction to that of TXSS is executed, and when TXSS and RXSS are completed, radio waves can be transmitted and received between AP 110 and STA 120 by millimeter-wave wireless communication.

<System configuration>
Next, the configuration of the communication system according to the present embodiment will be described.

  FIG. 4 is a diagram illustrating a configuration example of a communication system according to an embodiment. The communication system (wireless communication system) 400 includes, for example, a plurality of hopping nodes 401-1 to 401-5, one or more edge nodes 402-1 to 402-7, and a communication management device 403. In the following description, “hopping node 401” is used to indicate an arbitrary hopping node among the plurality of hopping nodes 401-1 to 401-5. In addition, “edge node 402” is used to indicate an arbitrary edge node among the one or more edge nodes 402-1 to 402-7.

  A hopping node (hopping terminal) 401 includes a first communication unit that functions as an AP for millimeter wave wireless communication, a second communication unit that functions as an STA for millimeter wave wireless communication, and a third communication unit that performs wireless LAN communication. A communication device. Note that millimeter wave wireless communication is an example of wireless communication that performs multi-hop communication using radio waves having directivity. The wireless LAN communication is an example of second wireless communication having a wider communication range than the first wireless communication. Further, the hopping node 401 is an example of a wireless communication terminal.

  The plurality of hopping nodes 401-1 to 401-5 form different network cells (BSS) by millimeter wave wireless communication using the first communication unit. For example, in FIG. 4, the hopping node 401-1 forms a network cell 406-1 and the hopping node 401-2 forms a network cell 406-2. In addition, it is assumed that the hopping node 401-3 forms a network cell 406-3, and other hopping nodes also form network cells in the same manner.

  The hopping node 401 can be connected to a network cell formed by another hopping node using the second communication unit. In the example of FIG. 4, the hopping node 401-2 uses the second communication unit (STA) to connect the network cell 406-1 formed by the first communication unit (AP) of the hopping node 401-1 to the millimeter. It can be connected by radio wave communication. The hopping node 401-1 is connected by the second communication unit (STA) to the network cell 406-3 formed by the first communication unit (AP) of the hopping node 401-3 by millimeter wave wireless communication. be able to. Similarly, the hopping node 401-3 is connected by the second communication unit (STA) to the network cell formed by the first communication unit (AP) of the hopping node 401-4 by millimeter wave wireless communication. Can do.

  Furthermore, the plurality of hopping nodes 401-1 to 401-5 are included in the same wireless LAN network 407 as the communication management device 403 and can perform wireless LAN communication with the communication management device 403 using the third communication unit. it can. Note that the access point for wireless LAN communication may be the communication management apparatus 403 or may use another access point.

The edge node (edge terminal) 402 includes a fourth communication unit that functions as an STA for millimeter wave wireless communication, and is a communication device that connects to one network cell among a plurality of network cells formed by the edge node 402. .
In the example of FIG. 4, the edge nodes 402-1 to 402-3 use the fourth communication unit (STA) to form the network cell 406- formed by the first communication unit (AP) of the hopping node 401-1. 1 is connected.

  Although not essential, the edge node 402 may further include a communication unit that performs wireless LAN communication. For example, a broken line 404 in FIG. 4 indicates a connection relationship between apparatuses by wireless LAN communication, and the edge node 402-6 can be communicated with the communication management apparatus 403 by wireless LAN communication. . Similarly, it is indicated that the plurality of hopping nodes 401-1 to 401-5 can communicate with the communication management apparatus 403 by wireless LAN communication.

  In the above configuration, each hopping node 401 uses the second communication unit (STA) to collect information on peripheral communication devices by millimeter-wave wireless communication, and the collected information is communicated to a communication management device by wireless LAN communication. To 403.

  The communication management apparatus (communication management terminal) 403 uses information received from each hopping node 401 by wireless LAN communication, for example, a connection relationship between apparatuses by millimeter wave wireless communication as indicated by a solid line 405 in FIG. Manage. In addition, when multi-hop communication by millimeter wave wireless communication is performed, the communication management device 403 determines a data communication path based on the identified connection relationship, and instructs the hopping node 401 in the communication path to provide an instruction regarding the communication path. Transmit by wireless LAN communication.

  The hopping node 401 receives the data received by one of the first communication unit and the second communication unit based on the instruction regarding the communication path notified by the wireless LAN communication from the communication management device 403. The other communication unit transfers the data to another communication device.

  Thus, in the present embodiment, the hopping node 401 has two millimeter wave communication units, and the data received by one communication unit can be transferred to another communication device by the other communication unit. Video data, audio data, and the like can be easily stream-transferred.

<Hardware configuration>
(Hardware configuration of hopping node)
FIG. 5A shows an example of the hardware configuration of the hopping node 401. The hopping node 401 includes, for example, a central processing unit (CPU) 511, a read only memory (RAM) 512, a read only memory (ROM) 513, a storage unit 514, a wireless LAN communication device 515, a millimeter wave wireless communication device 516-1, 516-2, a lamp 517, a bus 518, and the like.

  The CPU 511 is an arithmetic device that implements each function of the hopping node 401 by reading a program or data stored in the ROM 513, the storage unit 514, or the like onto the RAM 512 and executing processing. The RAM 512 is a volatile memory used as a work area for the CPU 511 or the like. The ROM 513 is a nonvolatile memory that can retain programs and data even when the power is turned off.

  The storage unit 514 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a flash ROM, and stores an OS (Operating System), application programs, various data, and the like.

  The wireless LAN communication device 515 is a wireless communication device for performing wireless LAN communication conforming to a standard such as IEEE802.11a / b / g / n / ac, for example, an antenna, a wireless unit, a MAC (Media Access), and the like. Control) section, communication control section, and the like.

  The millimeter-wave wireless communication devices 516-1 and 516-2 are wireless communication devices for performing millimeter-wave wireless communication conforming to standards such as IEEE 802.11ad, for example, an antenna, a wireless unit, a MAC unit, and a communication Includes a control unit and the like.

  The lamp 517 is a light emitting element for displaying, for example, the operating state of the hopping node 401 by color change, lighting / flashing, or the like. A bus 518 is connected to each of the above components, and transmits an address signal, a data signal, various control signals, and the like.

(Hardware configuration of edge node)
FIG. 5B shows an example of the hardware configuration of the edge node 402. The edge node 402 includes, for example, a CPU 521, a RAM 522, a ROM 523, a storage unit 524, a wireless LAN communication device 525, a millimeter wave wireless communication device 526, a display device 527, an input device 528, a bus 529, and the like. Among these, the configuration of the CPU 521, RAM 522, ROM 523, storage unit 524, wireless LAN communication device 525, millimeter wave wireless communication device 526, bus 529, etc. is the same as the configuration of each unit described in the hopping node 401. Omitted.

  The display device 527 is a display device such as a liquid crystal display that displays a display screen. The input device 528 is an input device such as a touch panel or a keyboard that accepts user input operations.

  Note that the configuration of the edge node 402 illustrated in FIG. 5 is an example, and the edge node 402 may not include the wireless LAN communication device 525.

(Hardware configuration of communication management device)
FIG. 6 is a diagram illustrating an example of a hardware configuration of a communication management apparatus according to an embodiment. The communication management device 403 includes, for example, a CPU 601, a RAM 602, a flash ROM 603, a wireless LAN communication device 604, a bus 605, and the like.

  The CPU 601 is an arithmetic device that implements each function of the communication management device 403 by executing a program stored in the flash ROM 603 or the like. A RAM 602 is a volatile memory used as a work area for the CPU 511. The flash ROM 603 is a rewritable nonvolatile memory that can retain programs and data even when the power is turned off.

  The wireless LAN communication device 604 is a wireless communication device for performing wireless LAN communication. A bus 605 is connected to each of the above components, and transmits an address signal, a data signal, various control signals, and the like.

<Functional configuration>
Next, the functional configuration of each device will be described.

(Functional configuration of hopping node)
FIG. 7 is a diagram illustrating an example of a functional configuration of a hopping node according to an embodiment. The hopping node (hopping terminal) 401 includes a wireless LAN communication unit 701, a millimeter wave wireless communication unit (AP) 702, a millimeter wave wireless communication unit (STA) 703, a storage unit 704, and the like. The hopping node 401 includes a communication link state measurement unit 711, an information collection unit 712, a data transfer unit 713, a disconnection determination unit 714, an edge node management unit 715, an information transfer unit 716, a connection control unit 717, and the like. Further, the hopping node 401 includes an information transmission unit 721, an information reception unit 722, a registration request unit 723, and the like.

  The wireless LAN communication unit (third communication unit) 701 is realized by, for example, a program executed by the wireless LAN communication device 515 in FIG. 5A and the CPU 511 in FIG. The wireless LAN communication unit 701 connects the hopping node 401 to the wireless LAN network 407 and performs wireless LAN communication with the communication management apparatus 403.

  The millimeter wave wireless communication unit (AP) 702 is realized by, for example, a program executed by the millimeter wave wireless communication apparatus 516-1 in FIG. 5A and the CPU 511 in FIG. The millimeter wave wireless communication unit (AP) 702 functions as an AP (access point) for millimeter wave wireless communication and forms a network cell for millimeter wave wireless communication. In addition, the millimeter wave wireless communication unit (AP) 702 transmits / receives data to / from the STA of millimeter wave wireless communication connected to the formed network cell by millimeter wave wireless communication. The millimeter wave wireless communication unit (AP) 702 is an example of a first communication unit.

  The millimeter wave wireless communication unit (STA) 703 is realized by, for example, a program executed by the millimeter wave wireless communication apparatus 516-2 in FIG. 5A and the CPU 511 in FIG. The millimeter wave wireless communication unit (STA) 703 functions as a STA (station) for millimeter wave wireless communication, and is connected to a network cell for millimeter wave wireless communication formed by another hopping node. In addition, the millimeter wave wireless communication unit (STA) 703 transmits and receives data to and from other hopping nodes forming the network cell by millimeter wave wireless communication. The millimeter wave wireless communication unit (STA) 703 is an example of a second communication unit.

  The storage unit 704 is realized by, for example, a program executed by the RAM 512 in FIG. 5A, the storage unit 514, and the CPU 511 in FIG. 5A. For example, the data received by the millimeter-wave wireless communication is temporarily stored in the storage unit 704. Functions as a buffer to store. The storage unit 704 stores various information such as access point information notified from the communication management device 403 and information on the edge node 402 connected to the network cell formed by the millimeter wave wireless communication unit (AP) 702. .

  The communication link state measurement unit 711 is realized by, for example, a program executed by the CPU 511 in FIG. The communication link state measurement unit 711 measures the communication link state of the hopping node 401 and the edge node 402 that can communicate with the millimeter wave wireless communication unit (AP) 702 and the millimeter wave wireless communication unit (STA) 703, for example. The communication link state includes information such as received signal strength, throughput value, packet loss rate, and the like. In the following description, the communication link state may be referred to as “communication quality”.

  The information collection unit 712 is realized by, for example, a program executed by the CPU 511 in FIG. 5A, and scans (searches) other wireless communication terminals (hopping node 401, edge node 402) in the vicinity by millimeter wave wireless communication. To collect information.

  For example, the information collection unit 712 uses the communication link state measurement unit 711 to acquire identification information (such as a hopping node number) of other hopping nodes around the hopping node 401 and information such as a communication link state. Further, the information collection unit 712 uses the communication link state measurement unit 711 to acquire identification information (edge node numbers and the like) of edge nodes around the hopping node 401 and information such as the communication link state.

  Note that the information collected by the information collection unit 712 is transmitted to the communication management apparatus 403 by wireless LAN communication by the information transmission unit 721, for example.

  The data transfer unit 713 is realized by, for example, a program executed by the CPU 511 in FIG. The data transfer unit 713 receives data received by one of the millimeter wave wireless communication units from the two millimeter wave wireless communication units based on an instruction regarding a communication path notified from the communication management device 403 by wireless LAN communication. Are transferred to other wireless communication terminals by the millimeter wave wireless communication unit. For example, the data transfer unit 713 uses the millimeter wave wireless communication unit (STA) 703 to notify the data received by the millimeter wave wireless communication unit (AP) 702 from the communication management device 403 by wireless LAN communication. To the transfer destination wireless communication terminal included in the instruction.

  The disconnection determination unit 714 is realized by, for example, a program executed by the CPU 511 in FIG. 5A, and determines disconnection of the millimeter wave wireless communication based on the communication link state measured by the communication link state measurement unit 711.

  The edge node management unit (device management unit) 715 is realized by, for example, a program executed by the CPU 511 in FIG. 5A, and is connected to a network cell formed by the millimeter wave wireless communication unit (AP) 702. Manage. For example, the edge node management unit 715 registers the edge node 402 connected to the network cell formed by the millimeter wave wireless communication unit (AP) 702 with the hopping node 401 and notifies the registered edge node 402 of the IP address and the like. .

  The information transfer unit 716 is realized by, for example, a program executed by the CPU 511 in FIG. 5A, and relays information transmitted and received between the edge node 402 and the communication management apparatus 403. For example, in response to a request from the edge node 402, the information transfer unit 716 transfers information received from the edge node 402 by millimeter wave wireless communication to the communication management apparatus 403 by wireless LAN communication. Further, the information transfer unit 716 transfers information received from the communication management apparatus 403 through wireless LAN communication to the edge node 402 through millimeter wave wireless communication in response to a request from the communication management apparatus 403.

  After the communication with the other hopping node 401 by the millimeter wave wireless communication unit (STA) 703 is disconnected, the connection control unit 717 sends the millimeter wave wireless communication unit to the other hopping node 401 notified from the communication management device 403. (STA) 703 is connected by millimeter wave wireless communication.

  The connection control unit 717 may be included in the communication management device 403. In this case, the millimeter wave wireless communication unit (STA) 703 connects to another hopping node 401 notified from the connection control unit 717 included in the communication management device 403 by millimeter wave wireless communication.

  The information transmission unit 721 is realized by, for example, a program executed by the CPU 511 in FIG. 5A, and transmits information to the communication management apparatus 403 using the wireless LAN communication unit 701. For example, the information transmission unit 721 transmits information about peripheral wireless communication terminals collected by the information collection unit 712, a disconnection notification indicating that the millimeter-wave wireless communication is disconnected, and the like to the communication management apparatus 403 by wireless LAN communication. .

  The information receiving unit 722 is realized by, for example, a program executed by the CPU 511 in FIG. 5A, and receives information transmitted from the communication management apparatus 403 using the wireless LAN communication unit 701. For example, the information receiving unit 722 receives control information such as an instruction regarding a communication path notified from the communication management apparatus 403 through wireless LAN communication.

  The registration request unit 723 is realized, for example, by a program executed by the CPU 511 in FIG. The registration request unit 723 transmits a registration request to the communication system 400 including information on peripheral wireless communication terminals collected by the information collection unit 712 by wireless LAN communication, for example, at startup.

(Functional configuration of edge node)
FIG. 8 is a diagram illustrating an example of a functional configuration of the edge node according to the embodiment. The edge node 402 includes a millimeter wave wireless communication unit (STA) 801, a data transmission unit 802, a data reception unit 803, a display control unit 804, an operation reception unit 805, a storage unit 806, and the like.

  Preferably, the edge node 402 includes a wireless LAN communication unit 811, an information transmission unit 812, an information reception unit 813, and the like.

  The millimeter-wave wireless communication unit (STA) 801 is realized by, for example, a program executed by the millimeter-wave wireless communication device 526 in FIG. 5B and the CPU 521 in FIG. Connected to a network cell for millimeter wave wireless communication. The millimeter wave wireless communication unit (STA) 801 is an example of a fourth communication unit that performs millimeter wave wireless communication (first wireless communication).

  The data transmission unit 802 is realized by, for example, a program executed by the CPU 521 in FIG. 5B, and content data such as video data, audio data, and files is transmitted using the millimeter wave wireless communication unit (STA) 801. Send by millimeter wave wireless communication.

  The data receiving unit 803 is realized by, for example, a program executed by the CPU 521 in FIG. 5B, and uses the millimeter wave wireless communication unit (STA) 801 to perform video data, audio data, and file by millimeter wave wireless communication. Etc. are received.

The display control unit 804 is realized by, for example, a program executed by the CPU 521 in FIG. 5B, and an operation screen or a data reception unit 803 is added to the display device 527 in FIG.
The received video data is displayed.

  The operation accepting unit 805 is realized by, for example, a program executed by the CPU 521 in FIG. 5B, and accepts a user input operation or the like with respect to the input device 528 in FIG.

  The storage unit 806 stores content data such as video data, audio data, and files received by the data receiving unit 803, for example.

  The wireless LAN communication unit 811 is realized by, for example, a program executed by the wireless LAN communication device 525 of FIG. 5B and the CPU 521 of FIG. 5B, and communicates with the communication management device 403 and the like by wireless LAN communication. I do.

  The information transmission unit 812 is realized by, for example, a program executed by the CPU 521 in FIG. 5B, and transmits information to the communication management device 403 or the like by wireless LAN communication using the wireless LAN communication unit 811. For example, the edge node 402 transmits request information for requesting data transmission by multi-hop communication to the communication management apparatus 403 using the information transmission unit 812.

  The information receiving unit 813 is realized by, for example, a program executed by the CPU 521 in FIG. 5B, and receives control information and the like notified from the communication management device 403 by wireless LAN communication using the wireless LAN communication unit 811. To do.

(Functional configuration of communication management device)
The communication management device 403 includes a wireless LAN communication unit 901, an information acquisition unit 902, a communication path management unit 903, a control information transmission unit 904, a hopping node management unit 905, an edge node management unit 906, a storage unit 907, a notification unit 908, and A classification unit 909 and the like are included.

  The wireless LAN communication unit (fifth communication unit) 901 is realized by, for example, a program executed by the wireless LAN communication device 604 in FIG. 6 and the CPU 601 in FIG. 6B. 401 communicates with the edge node 402 and the like.

  For example, the wireless LAN communication unit 901 can connect another hopping node that can be connected from one hopping node 401 when the communication state of the hopping node 401 with another hopping terminal transitions from a specified state. It functions as a receiving unit that receives search results obtained by searching for terminals.

  Note that “when the communication state transitions from a specified state” includes, for example, a case where the hopping node 401 detects deterioration (decrease) in communication quality of millimeter-wave wireless communication or a disconnection. It is. In the following description, a case where a hopping node 401 that detects degradation (decrease) or disconnection of millimeter-wave wireless communication and transmits a disconnection notification to the communication management device 403 is referred to as a “disconnected hopping node 401”. There is.

  The information acquisition unit (acquisition unit) 902 is realized by, for example, a program executed by the CPU 601 in FIG. 6B, and acquires information from a plurality of hopping nodes 401 through wireless LAN communication. For example, the information acquisition unit 902 transmits a scan request for requesting information acquisition to the plurality of hopping nodes 401 by wireless LAN communication at a predetermined time interval or the like (periodically), and is transmitted from the plurality of hopping nodes 401. The information of the surrounding wireless communication terminals is acquired.

  The communication path management unit 903 is realized by, for example, a program executed by the CPU 601 in FIG. 6B, and is a communication that transfers data by multi-hop communication based on information acquired by the information acquisition unit 902 by wireless LAN communication. Manage routes.

  For example, the communication path management unit 903 uses the information acquired by the information acquisition unit 902 to specify (or determine) the connection relationship between devices using millimeter-wave wireless communication as indicated by the solid line 405 in FIG. Based on the (or determined) connection relationship, a communication path for multi-hop communication is determined.

  The control information transmission unit 904 is realized by, for example, a program executed by the CPU 601 in FIG. 6B, and transmits control information to the hopping node 401 or the like through wireless LAN communication.

  The hopping node management unit 905 is realized by, for example, a program executed by the CPU 601 in FIG. 6B, and information on the hopping node 401 registered in the communication system 400 based on information acquired by the information acquisition unit 902. Manage.

  The edge node management unit 906 is realized by, for example, a program executed by the CPU 601 in FIG. 6B, and manages information on the edge node 402 included in the communication system 400 based on information acquired by the information acquisition unit 902. To do.

  The storage unit 907 is realized by, for example, a program executed by the CPU 601 in FIG. 6B, a flash ROM 603, a RAM 602, and the like. The storage unit 907 stores various information such as a communication path managed by the communication path management unit 903 and information acquired by the information acquisition unit 902, for example.

  When the classification unit 909 receives a disconnection notification including a scan result of another hopping node 401 from the hopping node 401 when transmitting data all at once in multi-hop communication, the classification unit 909 moves the other hopping node 401 to the first terminal group. And the second terminal group.

  Here, the first terminal group includes a hopping node 401 to which a transmission source terminal that transmits data all at once by multi-hop communication and a communication path of multi-hop communication are connected. On the other hand, in the second terminal group, hopping nodes 401 that are not connected to a transmission source terminal and a multi-hop communication path are classified.

  The notification unit 908 selects and disconnects connection destinations where data transmitted from the transmission source terminals all at once reach all hopping nodes 401 (or more hopping nodes 401) included in the communication system 400. Notify hopping node 401.

  For example, when the disconnected hopping node 401 is connected to the transmission source terminal, that is, the notification unit 908 belongs to the first terminal group, the notification unit 908 includes the hopping node 401 belonging to the second terminal group. The hopping node 401 of the connection destination is selected from the inside.

  On the other hand, when the disconnected hopping node 401 is not connected to the transmission source terminal, that is, the notification unit 908 belongs to the second terminal group, the notification unit 908 includes the hopping node 401 belonging to the first terminal group. The hopping node 401 of the connection destination is selected from the inside.

  For example, the notifying unit 908 transmits one or more hopping nodes 401 included in a terminal group different from the terminal group to which the disconnected hopping node 401 belongs, out of the first terminal group and the second terminal group. Hopping node 401 is selected.

  As an example, the notification unit 908 selects one hopping node 401 having the best communication quality from among one or more hopping nodes 401 included in a terminal group different from the terminal group to which the disconnected hopping node 401 belongs. Hopping node 401 is selected.

  Also, as another example, the notification unit 908 may include the number of hops between the transmission source terminal and one of the one or more hopping nodes 401 included in a terminal group different from the terminal group to which the disconnected hopping node 401 belongs. One hopping node 401 having the smallest (number of relays) may be selected.

  Furthermore, the notification unit 908 notifies the disconnected hopping node 401 of the selected connection destination hopping node 401 via the control information transmission unit 904.

  As a result, the connection control unit 717 of the disconnected hopping node 401 sets the one hopping node 401 included in a terminal group different from the terminal group to which the own terminal belongs, out of the first terminal group and the second terminal group. Connect the terminal with millimeter-wave wireless communication.

  Note that the notification unit 908 is an example of a transmission unit that transmits the classification result in the classification unit 909 to one hopping terminal whose communication state has transitioned from a specified state.

<Process flow>
Next, a processing flow in the communication path switching method according to the present embodiment will be described.

[First Embodiment]
(Hopping node registration process)
FIG. 10 is a sequence diagram illustrating an example of hopping node registration processing according to the first embodiment. This processing is an example of processing when the hopping node 401 is activated and registered as a hopping node in the communication management apparatus 403. Note that, in the following sequence diagrams, broken arrows represent communication by wireless LAN communication.

  In step S1001, when the hopping node 401a is activated by, for example, turning on the power or the activation operation by the user, the processing from step S1002 is executed.

  In step S1002, the hopping node 401a connects to the communication management apparatus 403 by wireless LAN communication. For example, the wireless LAN communication unit 701 searches for the communication management device 403 by broadcast (or multicast), and requests connection of the searched communication management device 403 by wireless LAN communication.

  In step S1003, when the hopping node 401a receives a response from the communication management apparatus 403, in step S1004, the hopping node 401a scans another wireless communication terminal by millimeter wave wireless communication. For example, the information collection unit 712 of the hopping node 401a uses the millimeter wave wireless communication unit (STA) 703 and the communication link state measurement unit 711 to provide information on other hopping nodes in the vicinity (for example, SSID, radio wave intensity, etc.). ).

  In step S1005, the hopping node 401a transmits a registration request for requesting registration in the communication management apparatus 403 by wireless LAN communication. This registration request includes a scan result (for example, SSID of other hopping nodes in the vicinity, radio wave intensity, etc.) by the information collection unit 712.

  In step S1006, upon receiving a registration request from the hopping node 401a, the communication management apparatus 403 executes processing for registering the hopping node 401a in the communication system 400. For example, the hopping node management unit 905 of the communication management apparatus 403 stores information on other hopping nodes included in the registration request received from the hopping node 401 in the storage unit 907. In addition, the hopping node management unit 905 determines access point information (AP information) to be notified to the hopping node 401. This access point information includes, for example, information such as an SSID (Service Set Identifier), encryption key, communication channel, and IP address used by the millimeter wave wireless communication unit (AP) 702 of the hopping node 401.

  In step S1007, the hopping node management unit 905 of the communication management device 403 selects the connection destination hopping node 401 to which the hopping node 401a is connected. For example, the hopping node management unit 905 connects from the hopping nodes 401 registered in the communication management device 403 based on the strength of the received radio wave included in the scan result, the number of connected wireless communication terminals, and the like. The previous hopping node 401 is selected.

  If the connection destination hopping node can be selected in step S1007, the communication management apparatus 403 executes the processing in steps S1008 to S1010. Here, the following description will be made assuming that the hopping node 401b is selected as the connection destination of the hopping node 401a.

  In step S1008, the hopping node management unit 905 of the communication management apparatus 403 transmits a registration completion notification indicating that the registration is completed to the requesting hopping node 401a by wireless LAN communication. This registration completion notification includes, for example, information on the connection destination hopping node (eg, hopping node 401b) selected in step S1007 and access point information (AP information) determined in step S1006.

  In step S1009, the millimeter wave wireless communication unit (STA) 703 of the hopping node 401a connects to the connection destination hopping node 401b included in the registration completion notification by millimeter wave wireless communication.

  In step S1010, the millimeter wave wireless communication unit (AP) 702 of the hopping node 401 uses the access point information included in the registration completion notification to connect the millimeter wave wireless communication access point and the DHCP (Dynamic Host Configuration Protocol) server. to start. For example, the millimeter wave wireless communication unit (AP) 702 forms a network cell (BSS) for millimeter wave wireless communication using the SSID, encryption key, communication channel, IP address, etc. included in the notified access point information. .

  On the other hand, if the connection destination hopping node cannot be selected in step S1007, the communication management apparatus 403 executes the process of step S1011.

  In step S1011, the hopping node management unit 905 of the communication management apparatus 403 transmits a registration completion notification indicating that the registration is completed to the requesting hopping node 401a by wireless LAN communication. In this case, for example, the hopping node 401a starts again from the process of scanning another communication terminal by millimeter wave wireless communication.

  The hopping node 401a may notify the fact by a lamp or the like while the other hopping node 401 of the connection destination is not found. Thereby, an administrator, an installer, etc. can recognize that it is necessary to install another hopping node 401 around the hopping node 401a.

  In this way, the hopping node 401 connects to another hopping node 401 as soon as it is activated. Thereby, basically, a network is formed so that data can be transmitted simultaneously to all wireless communication terminals by multi-hop communication by millimeter wave wireless communication.

  However, if there is a hopping node 401 in which the situation is not improved and another hopping node 401 that can be connected by millimeter wave wireless communication is not found, the communication management device 403 excludes the hopping node 401 from the communication path, and the wireless LAN Send data via communication.

(About communication path disconnection determination)
FIG. 11 is a diagram for explaining cutting determination according to the first embodiment. For example, as shown in FIG. 11, a hopping node B that is performing millimeter-wave wireless communication with hopping node A continuously monitors the communication link state of millimeter-wave wireless communication of hopping node A, and performs millimeter-wave wireless communication. Determine disconnection (route switching).

At this time, there are a plurality of determination conditions for the hopping node 401 to determine the disconnection of the millimeter wave wireless communication. For example,
1) When the millimeter-wave radio is disconnected or when a reconnection request is made after disconnection 2) The signal strength and throughput value of the millimeter-wave radio is below the threshold, or the packet error rate is above the threshold 3) Video In the case of audio stream transfer, the loss rate of video data packets in the transport / application layer is equal to or greater than the threshold value 4) In the case of video / audio stream transfer, the sequence number included in the packet header in the transport / application layer This is the case when the next sequence number cannot be received for a certain period.

  In the case of the condition 1), it is also assumed that the hopping node B makes one or more reconnection requests. Such a process is effective, for example, when an obstacle exists between the hopping node A and the hopping node B for a short period of time.

  Regarding the condition 2), as shown in FIG. 11, threshold determination is performed by combining one or more parameters (signal strength, throughput value, error rate, etc.) indicating communication quality. At this time, a moving average value may be used.

  Regarding the condition 3), for example, when transferring a video stream, the threshold of the packet loss rate varies depending on the video quality and quality required by the application.

  The same applies to the condition 4), which depends on, for example, the frame rate and resolution of the video data.

  Especially in the case of video stream transfer, switching determination is difficult only with the condition of 1) (millimeter wave wireless communication parameter). When the condition of 1) is satisfied, the secondary determination is performed under the conditions of 3) and 4). It is desirable to perform the path switching process when this condition is also satisfied.

(Hopping node processing)
FIG. 12 is a flowchart illustrating an example of processing of the hopping node according to the first embodiment. This processing is an example of processing that is executed when the millimeter-wave wireless communication is disconnected when the hopping node 401 changes the communication path of multi-hop communication.

  In step S <b> 1201, the information reception unit 722 of the hopping node 401 receives a start notification indicating that multihop communication is started through wireless LAN communication from the communication management device 403.

  In step S1202, the communication link state measurement unit 711 of the hopping node 401 starts monitoring the communication quality of millimeter wave wireless communication.

  For example, in step S1203, the communication link state measurement unit 711 of the hopping node 401 determines the communication quality such as the throughput value and error rate of the millimeter wave wireless communication of the hopping node 401 to which the millimeter wave wireless communication unit (STA) 703 is connected. Measure.

  In step S1204, the disconnection determination unit 714 of the hopping node 401 determines whether the measured communication quality is equal to or higher than a threshold value. If the measured communication quality is equal to or higher than the threshold, the disconnection determination unit 714 returns the process to step S1203, and the communication link state measurement unit 711 continues to measure the communication quality. On the other hand, when the measured communication quality is not equal to or higher than the threshold value, the disconnection determination unit 714 causes the process to proceed to step S1207.

  In step S1205, the communication link state measurement unit 711 of the hopping node 401 performs the millimeter wave wireless communication of the hopping node 401 connected to the millimeter wave wireless communication unit (STA) 703 in parallel with the processing of step S1203. Measure the received signal strength.

  In step S1206, the disconnection determination unit 714 of the hopping node 401 determines whether or not the measured received radio wave intensity is greater than or equal to a threshold value. If the measured intensity of the received radio wave is equal to or greater than the threshold, the disconnection determination unit 714 returns the process to step S1205, and the communication link state measurement unit 711 continues to measure the intensity of the received radio wave. On the other hand, if the measured intensity of the received radio wave is not equal to or greater than the threshold value, the disconnection determination unit 714 causes the process to proceed to step S1207. The intensity of the received radio wave of millimeter wave wireless communication is another example of the communication quality of millimeter wave wireless communication.

  In step S1207, the information collection unit 712 of the hopping node 401 uses the millimeter wave wireless communication unit (STA) 703 to scan other wireless communication terminals (hopping node 401) that can be connected by millimeter wave wireless communication ( Search for.

  In step S1208, the information transmission unit 721 of the hopping node 401 notifies the communication management apparatus 403 of a disconnection notification including the scan result (search result) by wireless LAN communication.

  In step S1209, upon receiving the connection destination information notified from the communication management apparatus 403, the connection control unit 717 of the hopping node 401 connects the millimeter wave wireless communication unit (STA) 703 to the notified connection destination.

(Destination notification process)
FIG. 13 is a diagram illustrating an example of a network configuration when a disconnection occurs in the first embodiment. In FIG. 13, content data is transmitted simultaneously (for example, by broadcast transmission) from an edge node (transmission source) 402a which is a wireless communication terminal of the transmission source to other hopping nodes 401a to 401d and edge nodes 402b to 401e. And

  At this time, it is assumed that the content data transmitted from the edge node (transmission source) 402a is sequentially multi-hop-transferred in the direction of the “data transmission direction” arrow in the figure and reaches each wireless communication terminal.

  Here, for example, it is assumed that the hopping node 401b detects deterioration in communication quality of millimeter-wave wireless communication with the hopping node 401c by the process shown in FIG. 12, and transmits a disconnection notification to the communication management apparatus 403. At this time, the communication management apparatus 403 executes connection destination notification processing as shown in FIGS. 14A and 14B, for example.

  FIG. 14 is a flowchart illustrating an example of connection destination notification processing according to the first embodiment.

(Connection destination notification process 1)
FIG. 14A shows an example of a connection destination notification process executed by the communication management apparatus 403.

  In step S1411, when the information reception unit 813 receives the disconnection notification transmitted from the hopping node 401 in step S1411, the communication management apparatus 403 executes processing in step S1412 and subsequent steps. Note that the disconnection notification transmitted from the hopping node 401 includes the scan result of another hopping node 401 connectable from the hopping node 401 scanned by the hopping node 401.

  FIG. 15A shows an example of a scan result by the hopping node 401b shown in FIG. In the example of FIG. 15A, the scan result includes information such as “hopping node”, “SSID”, and “radio wave intensity”. The edge node 402 is not included in the scan result because it is not connectable from the millimeter wave wireless communication unit (STA) 703 of the hopping node 402.

  The “hopping node” information is information (for example, terminal name, terminal ID, node number, etc.) of the hopping node 401b that has performed the scan. The “SSID” information is information such as an SSID for identifying another hopping node 401 searched by the hopping node 401b. The “radio wave intensity” information is information indicating the intensity of radio waves received from other hopping nodes 401.

  In step S1412, the communication path management unit 903 of the communication management apparatus 403 determines whether the content data transmitted by the edge node (transmission source) 402a that is the transmission source terminal reaches all hopping nodes 401.

  As described above, the communication path management unit 903 manages a communication path for transferring data by multi-hop communication based on information acquired by the information acquisition unit 902 by wireless LAN communication. For example, the communication path management unit 903 uses the information acquired by the information acquisition unit 902 to manage the connection relationship between terminals by millimeter wave wireless communication and the communication path of multi-hop communication as shown by a solid line in FIG. is doing.

  In the example of FIG. 13, the communication path management unit 903 determines that content data does not reach the hopping nodes 401c and 401d by disconnecting the millimeter-wave wireless communication between the hopping node 401b and the hopping node 401c. it can.

  In step S <b> 1413, the communication management apparatus 403 selects a hopping node 401 whose content data reaches all the hopping nodes 401 as the hopping node 401 b is connected as a connection destination hopping node.

  For example, in the example of FIG. 13, the hopping node 401b connects to the hopping node 401c or the hopping node 401d, so that the content data transmitted by the transmission source terminal reaches all the hopping nodes 401.

  Preferably, the communication path management unit 903 uses the hopping node 401 having the best communication quality as the connection destination among the hopping nodes 401c and 401d in which the content data transmitted by the transmission source terminal reaches all the hopping nodes 401. select.

  For example, in the example of FIG. 15A, the intensity of the received radio wave of the hopping node 401d is the hopping node 401d among the hopping nodes 401c and 401d in which the content data transmitted by the transmission source terminal reaches all the hopping nodes 401. Large (communication quality is good). Accordingly, the communication path management unit 903 selects the hopping node 401d as the connection destination of the disconnected hopping node 401b. The intensity of the received radio wave is an example of information related to communication quality, and other information related to communication quality (for example, throughput value, error rate, etc.) may be used.

  In step S1414, the notification unit 908 of the communication management apparatus 403 notifies the information of the selected connection destination (for example, the hopping node 401d) to the hopping node 401b that has transmitted the disconnection notification by wireless LAN communication.

(Connection destination notification process 2)
FIG. 14B shows another example of connection destination notification processing executed by the communication management apparatus 403. The process shown in steps S1422 to S1426 in FIG. 14B is a specific example of the process shown in step S1413 in FIG.

  In step S1421, when the information reception unit 813 receives the disconnection notification transmitted from the hopping node 401 in step S1421, the communication management apparatus 403 executes processing in step S1422 and subsequent steps.

  In step S <b> 1422, the classification unit 909 of the communication management apparatus 403 acquires the scan result of another hopping node 401 that can be connected from the hopping node 401, included in the disconnection notification received by the information reception unit 813.

  In step S <b> 1423, the classification unit 909 selects another connectable hopping node 401 based on the acquired scan result, the first terminal group in which the communication path is connected to the transmission source terminal, and the transmission source terminal. And the second terminal group to which the communication path is not connected.

  As described above, the communication path management unit 903 manages information on communication paths for multihop communication indicated by solid lines in the network configuration illustrated in FIG. 13, for example.

  FIG. 15B shows an image of an example of a communication path table for managing information on communication paths of multi-hop communication managed by the communication path management unit 903. In the example of FIG. 15B, the communication path table includes information such as “hopping node”, “connection destination hopping node (AP)”, and “connection to the transmission source terminal”.

  The “hopping node” information is information (for example, a terminal name, a terminal ID, a terminal number, etc.) of the hopping node 401 registered in the communication management apparatus 403.

  The information of “connection destination hopping node (AP)” is information (for example, terminal name, terminal ID, terminal number) of other hopping nodes 401 to which the millimeter wave wireless communication unit (STA) 703 of each hopping node 401 is connected. Etc.). For example, in the example of FIG. 15B, the millimeter wave wireless communication unit (STA) 703 of the hopping node 401a is connected to the millimeter wave wireless communication unit (AP) 702 of the hopping node 401b by millimeter wave wireless communication. It is shown. Also, it is shown that the millimeter wave wireless communication unit (STA) 703 of the hopping node 401d is not connected to the access point of another hopping node 401 by millimeter wave wireless communication.

  In the information of “connection to the transmission source terminal”, the hopping node 401a to which the edge node (transmission source) 402a that is the content data transmission source terminal is directly connected is indicated by, for example, “O”. Yes.

  The classification unit 909 uses, for example, a communication path table as illustrated in FIG. 15B, and when the millimeter-wave wireless communication of the hopping node 401b is disconnected, the communication path from each hopping node 401 to the transmission source terminal It is determined whether or not is connected.

  FIG. 15C shows an image of the determination result of the communication path to the transmission source terminal in each hopping node 401.

  For example, in FIG. 15B, since the hopping node 401a is directly connected to the transmission source terminal, the “communication path to the transmission source terminal” in FIG.

  In FIG. 15B, the hopping node 401b can receive content data via the hopping node 401a because the hopping node 401a is connected to the AP of the hopping node 401b. Accordingly, in FIG. 15C, the “communication path to the transmission source terminal” of the hopping node 401b is “◯”.

  On the other hand, in FIG. 15B, the hopping nodes 401c and 401d do not have a communication path to the hopping node 401a that is directly connected to the transmission source terminal. "Communication path" is "x".

  The classification unit 909 can also obtain the number of hops (the number of relays) from each hopping node 401 to the transmission source terminal using the communication path table shown in FIG.

  The classification unit 909 uses, for example, the determination result as illustrated in FIG. 15C to convert the hopping nodes 401a, 401c, and 401d included in the scan result as illustrated in FIG. It classify | categorizes into a terminal group and a 2nd terminal group.

  For example, the hopping node 401a is classified into the first terminal group because the “communication path to the transmission source terminal” is “◯” based on the determination result shown in FIG. On the other hand, the hopping nodes 401c and 401d are classified into the second terminal group because the “communication path to the transmission source terminal” is “x” based on the determination result shown in FIG.

  Here, returning to FIG. 14B, the description of the flowchart is continued.

  In step S1424, the notification unit 908 of the communication management apparatus 403 determines whether the hopping node 401 that has transmitted the disconnection notification belongs to the first terminal group or the second terminal group. For example, in the example of FIG. 13, the hopping node 401 that transmitted the disconnection notification is the hopping node 401b, and therefore the notification unit 908 refers to the determination result illustrated in FIG. 15C, and the hopping node 401b is the first terminal. Judge as belonging to a group.

  When the hopping node 401 that has transmitted the disconnection notification belongs to the first terminal group, the notification unit 908 shifts the processing to step S1425. On the other hand, when the hopping node 401 that transmitted the disconnection notification belongs to the second terminal group, the notification unit 908 shifts the processing to step S1426.

  In step S1425, the notification unit 908 of the communication management apparatus 403 selects a connection destination hopping node 401 from the other hopping nodes 401 classified in the second terminal group in step S1423.

  As an example, the notification unit 908 uses the scan result shown in FIG. 15A to have a higher radio field strength value (good communication quality) from among the hopping nodes 401 classified into the second terminal group. One hopping node (for example, hopping node 401d) is selected.

  As another example, the notification unit 908 may select one or more hopping nodes 401 from other hopping nodes 401 classified into the second terminal group. In this case, the hopping node 401 that has transmitted the disconnection notification may be selectively connected to the hopping node 401 having the best communication quality among the one or more hopping nodes 401 notified from the communication management device 403.

  In this case, each hopping node 401 may store the communication quality measurement history in the past millimeter-wave wireless communication in the storage unit 704 as shown in FIG. Accordingly, each hopping node 401 can select the hopping node 401 having the best communication quality from one or more hopping nodes 401 notified from the communication management device 403.

  In the example of FIG. 16A, an image of the communication quality measurement history stored in the storage unit 704 of the hopping node 401b is shown, and the hopping node 401d has a higher average throughput than the hopping node 401c. It is shown. Accordingly, the connection control unit 717 of the hopping node 401b connects to the hopping node 401d having a higher average throughput when the hopping nodes 401c and 401d are notified from the communication management apparatus 403 as connection destinations.

  Here, it returns to FIG.14 (b) again and description of a flowchart is further continued.

  When the process proceeds from step S1424 to step S1426, the notification unit 908 of the communication management apparatus 403 selects a connection destination hopping node 401 from the other hopping nodes 401 classified in the first terminal group in step S1423.

  As an example, the notification unit 908 uses the scan result as illustrated in FIG. 15A to determine the radio wave intensity of the other hopping nodes 401 from among the other hopping nodes 401 classified into the first terminal group. One hopping node 401 having a large value is selected.

  As another example, the notification unit 908 selects one or more hopping nodes 401 from the other hopping nodes 401 classified in the first terminal group, as described in step S1425. Also good.

  In step S1427, the notification unit 908 of the communication management apparatus 403 notifies the hopping node 401 that has transmitted the disconnection notification, using the selected hopping node as a connection destination.

  Upon receiving this notification, the hopping node 401 connects to the notified connection destination by millimeter-wave wireless communication, for example, by the process shown in step S1209 of FIG.

  At this time, for example, the communication path management unit 903 of the communication management apparatus 403 updates the communication path table as illustrated in FIG. 15B to the updated communication path table as illustrated in FIG. To do. In the example of FIG. 16B, the connection destination of the hopping node 401b is changed to the hopping node 401d.

  FIG. 17 is a diagram illustrating an example of a network configuration after path switching according to the first embodiment. This figure shows an example of the network configuration after the communication path is switched in the processing shown in FIGS. 12 and 14 from the network configuration at the time of disconnection shown in FIG. In the example of FIG. 17, the hopping node 401b in which the millimeter-wave wireless communication with the hopping node 401c is disconnected is connected to the hopping node 401d. As a result, the content data transmitted all at once from the edge node (transmission source) 402a reaches again all the wireless communication terminals (hopping node 401 and edge node 402).

(Communication system processing)
FIG. 18 is a sequence diagram illustrating an example of processing of the communication system according to the first embodiment. This processing is an example of processing of the entire communication system 400 corresponding to the processing shown in FIGS.

  In steps S1801 and S1802, for example, as shown in FIG. 13, the hopping node 401b determines that the millimeter-wave wireless communication with the hopping node 401c is disconnected while data is being transmitted to the hopping node 401c. The hopping node 401b is an example of a first wireless communication terminal.

  In step S1803, the information collection unit 712 of the hopping node 401b scans (searches) other connectable wireless communication terminals by the millimeter wave wireless communication unit (STA) 703.

  In step S1804, the information transmission unit 721 of the hopping node 401 notifies the communication management apparatus 403 of a disconnection notification including the scan result by wireless LAN communication.

  In step S1805, the communication management apparatus 403 executes connection destination notification processing as shown in steps S1411 to S1413 in FIG. 14A or steps S1421 to S1426 in FIG. The communication management device 403 is an example of a second wireless communication terminal.

  In step S1806, the notification unit 908 of the communication management apparatus 403 notifies the hopping node 401b of the connection destination (for example, hopping node 401d) selected in step S1805 by wireless LAN communication.

  In step S1807, upon receiving the connection destination information notified from the communication management device 403, the connection control unit 717 of the hopping node 401b connects to the notified connection destination (for example, the hopping node 401d) by millimeter wave wireless communication. .

  In step S1808, the hopping node 401b and the hopping node 401d connected by millimeter wave wireless communication mutually confirm the data reception status (or transmission status).

  In step S1809, when there is unreceived (or untransmitted) data, the hopping node 401b and the hopping node 401d receive (or transmit) unreceived (or untransmitted) data.

  In step S1810, the hopping node 401d and the hopping node 401c mutually confirm the data reception status (or transmission status).

  In step S1811, if there is unreceived (or untransmitted) data, the hopping node 401d and the hopping node 401d receive (or transmit) unreceived (or untransmitted) data.

  If the content data being transmitted is real-time streaming data, the processing in steps S1808 to S1811 is not necessary.

  As described above, according to the present embodiment, content data can be transmitted to more wireless communication terminals in a wireless communication system in which content data is transmitted all at once from the transmission source wireless communication terminal by multi-hop communication.

[Second Embodiment]
In the first embodiment, an example of processing when the connection destination hopping node 401 can be selected from the scan result of the disconnected hopping node 401 has been described. However, actually, there may be a case where the connection destination hopping node 401 cannot be selected. For example, there may be a case where the radio wave from another hopping node 401 does not reach due to a temporary obstacle or the case where the radio wave does not reach the radio wave.

  Thus, in the second embodiment, for example, an example of a suitable process when the selection destination hopping node cannot be selected in step S1413 of FIG. 14A will be described.

(Destination notification process)
FIG. 19 is a flowchart illustrating an example of connection destination notification processing according to the second embodiment. Of the processes shown in FIG. 19, the processes in steps S <b> 1411 to S <b> 1414 are the same as those in the first embodiment shown in FIG. 14A, and here, the differences from the first embodiment are mainly described. I will explain.

  In step S1901, the communication management apparatus 403 determines whether the connection destination hopping node has been selected in step S1413. If the connection destination hopping node can be selected, the communication management apparatus 403 shifts the processing to step S1414. On the other hand, if the connection destination hopping node cannot be selected, the communication management apparatus 403 moves the process to step S1902.

  In step S1902, the communication management apparatus 403 requests a scan to all hopping nodes that do not receive data.

  As described above, the communication path management unit 903 of the communication management apparatus 403 manages a communication path table for managing communication paths for multi-hop communication as shown in FIG. 15B, for example. Therefore, for example, when a disconnection occurs between the hopping node 401b and the hopping node 401c, the communication management apparatus 403 identifies the hopping nodes 401c and 401d to which data does not reach as shown in FIG. can do.

  In step S1903, for example, the communication management apparatus 403 selects a hopping node in which data reaches all hopping nodes from the scan results received from the hopping nodes 401c and 401d to which data does not reach.

  For example, in the network configuration shown in FIG. 13, in the first embodiment, a hopping node in which data reaches all hopping nodes is selected from the hopping node 401 b where the disconnection has occurred. However, other than this, for example, if any of the hopping nodes 401c and 401d to which the data does not reach can be connected to any of the hopping nodes 401a, 401b and 401 to which the data arrives, the data will reach all the hopping nodes. Become.

  Therefore, in this embodiment, when the connection destination hopping node 401 cannot be selected from the hopping node 401b where the disconnection has occurred, the connection destination hopping node 401 is selected from the hopping nodes 401c and 401d to which data does not reach.

  For example, when selecting the connection destination hopping node 401 from the hopping node 401d, the communication management apparatus 403 selects the other hopping nodes 401 scanned by the hopping node 401d as the first terminal group and the second terminal group described above. Classify into: In addition, the communication management apparatus 403 selects a hopping node 401 as a connection destination from among the classified first terminal group and second terminal group, from a terminal group different from the terminal group to which the hopping node 401d belongs. To do.

  In step S1904, the communication management apparatus 403 notifies the hopping node 401 whose connection destination is changed of the information of the hopping node 401 that is the connection destination.

  For example, in the network configuration shown in FIG. 13, it is assumed that the hopping node 401a is selected as the connection destination of the hopping node 401d by the processing in step S1903. In this case, for example, the communication path table as shown in FIG. 15B is updated as shown in FIG.

  In the example of FIG. 20, the connection destination of the hopping node 401b is changed to “none”, and the connection destination of the hopping node 401d is changed to “hopping node 401a”. In this case, the communication management apparatus 403 notifies the hopping node 401b and the hopping node 401d of the changed connection destination.

  FIG. 21 is a diagram illustrating an example of a network configuration after path switching according to the second embodiment. As shown in FIG. 21, when the hopping node 401d connects to the hopping node 401a, the content data transmitted from the edge node (transmission source) 402a is transmitted to all other wireless communication terminals.

(Processing of communication system)
FIG. 22 is a sequence diagram illustrating an example of processing of the communication system according to the second embodiment. This processing is an example of processing of the entire communication system 400 corresponding to the processing shown in FIG. Of the processes shown in FIG. 22, the processes in steps S1801 to S1804 are the same as the processes according to the first embodiment shown in FIG. 18, and here, differences from the first embodiment will be mainly described. I do.

  In step S2001, the communication management apparatus 403 executes connection destination notification processing as shown in steps S1411 to S1413 in FIG. 14A or steps S1421 to S1426 in FIG. However, here, it is assumed that the connection destination hopping node 401 of the hopping node 401b cannot be selected.

  In step S2002, the notification unit 908 of the communication management apparatus 403 notifies the hopping node 401b that has transmitted the disconnection notification through wireless LAN communication that there is no connection destination hopping node 401.

  In steps S2003 and S2005, the communication management apparatus 403 requests a hopping node (for example, the hopping nodes 401c and 401d) that does not receive content data from the transmission source terminal to perform scanning by wireless LAN communication.

  In steps S2004 and S2006, the hopping nodes 401c and 401d transmit the scan results to the communication management apparatus 403 by wireless LAN communication, respectively.

  In step S2007, the communication management apparatus 403 selects a hopping node 401 for changing the connection destination and the hopping node of the connection destination so that the data reaches all hopping nodes 401 from the received scan result. This process corresponds to the process in step S1903 in FIG.

  In step S2008, the notification unit 908 of the communication management apparatus 403 notifies the hopping node (hopping node 401a) of the connection destination selected in step S2007 to the hopping node (hopping node 401a) of the connection destination. .

  In step S2009, the connection control unit 717 of the hopping node 401d connects to the connection destination (for example, the hopping node 401a) notified from the communication management device 403 by millimeter wave wireless communication.

  In step S2010, the hopping node 401d and the hopping node 401a connected by millimeter-wave wireless communication mutually confirm the data reception status (or transmission status).

  In step S2011, if there is unreceived (or untransmitted) data, the hopping node 401d and the hopping node 401a receive (or transmit) unreceived (or untransmitted) data.

  In step S2012, the hopping node 401d and the hopping node 401c mutually confirm the data reception status (or transmission status).

  In step S2013, if there is unreceived (or untransmitted) data, the hopping node 401d and the hopping node 401c receive (or transmit) unreceived (or untransmitted) data.

  As described above, according to the present embodiment, even when the disconnected hopping node 401b cannot be selected in the disconnected hopping node 401b, the content data can be transmitted to more wireless communication terminals.

[Third Embodiment]
In the first and second embodiments, for example, the communication management apparatus 403 connects the hopping node 401b based on the radio wave intensity received from another hopping node 401 included in the scan result as illustrated in FIG. The previous hopping node 401 was selected.

  In the third embodiment, an example of processing when the communication management apparatus 403 selects a connection destination hopping node 401 based on the throughput value of millimeter wave wireless communication with another hopping node 401 will be described. .

(Processing of communication system)
FIG. 23 is a sequence diagram illustrating an example of processing of the communication system according to the third embodiment. An example of processing when selecting a hopping node 401 as a connection destination based on the throughput value of another hopping node 401 is shown.

  Of the processes shown in FIG. 23, the processes shown in steps S1801 to S1804 and steps S1806 to S1809 are the same as the processes of the first embodiment shown in FIG. The difference will be mainly described.

  In step S2301, the communication management apparatus 403 uses the scan result included in the disconnection notification received from the hopping node 401b to select a candidate for the hopping node 401 that is the connection destination of the hopping node 401b.

  For example, when the disconnection notification including the scan result as shown in FIG. 15A is received, the hopping nodes 401c and 401d to which the hopping node 401b is not connected by the millimeter wave wireless communication are connected to the hopping node 401 to be connected. Select as a candidate.

  At this time, the hopping node 401c disconnected by the hopping node 401b has just been determined to be disconnected, and may be excluded from the candidates. Here, the following description will be given assuming that the hopping nodes 401c and 401d are candidates for the hopping node 401 that is the connection destination.

  In step S2302, the communication management apparatus 403 notifies the list of selected connection destination candidates to the hopping node 401b that has transmitted the disconnection notification by wireless LAN communication.

  In steps S2303 to S2308, the hopping node 401b sequentially connects millimeter wave wireless communication to each of the notified candidates of the hopping node 401, and the communication quality of the millimeter wave wireless communication (here, Measure the throughput value.

  For example, in step S2303, the connection control unit 717 of the hopping node 401b uses the millimeter wave wireless communication unit (STA) 703 to connect to the hopping node 401c by millimeter wave wireless communication.

  In step S2304, the communication link state measurement unit 711 of the hopping node 401b measures a throughput value in millimeter wave wireless communication with the hopping node 401c, for example, by transmitting / receiving measurement data.

  In steps S2305 and S2306, the connection control unit 717 of the hopping node 401b disconnects the millimeter wave wireless communication with the hopping node 401c, and connects to the hopping node 401d with the millimeter wave wireless communication.

  In step S2307, the communication link state measurement unit 711 of the hopping node 401b measures the value of the millimeter-wave wireless communication throughput with the hopping node 401d.

  In step S2308, the connection control unit 717 of the hopping node 401b disconnects the millimeter wave wireless communication with the hopping node 401d.

  In step S2309, the information transmission unit 721 of the hopping node 401b transmits the measurement result of the throughput value measured with each hopping node 401 included in the list of connection destination candidates to the communication management apparatus 403 by wireless LAN communication. Send to.

  In step S2310, the communication management apparatus 403 selects the hopping node 401 to which the hopping node 401b is connected based on the measurement result of the throughput value received from the hopping node 401b. This process is basically the same as the connection destination notification process shown in FIG. 14 (a) or 14 (c). However, when the connection destination hopping node 401 is selected, the received radio wave intensity is increased. Instead, (or in addition), the difference is that the throughput value is used.

  For example, the classification unit 909 of the communication management device 403 converts the other hopping nodes 401 included in the scan result as illustrated in FIG. 15A into the first terminal group and the second terminal group described above. Classify.

  In addition, the notification unit 908 of the communication management device 403 includes a terminal group different from the terminal group to which the hopping node 401b that transmitted the disconnection notification belongs, out of the classified first terminal group and second terminal group. The hopping node 401 to be connected is selected.

  At this time, the notification unit 908 selects the hopping node 401 having the highest throughput value from hopping nodes (for example, hopping nodes 401c and 401d) included in a terminal group different from the terminal group to which the hopping node 401b belongs. .

  Here, for example, when the hopping node 401d is selected as the connection destination hopping node, the processes shown in steps S1806 to S1809 are executed.

  As described above, the communication quality value of the millimeter wave wireless communication used when the communication management apparatus 403 selects the connection destination hopping node 401 is not limited to the intensity of the received radio wave, and uses the value of the throughput. May be. Further, the communication quality value of the millimeter wave wireless communication used when the communication management apparatus 403 selects the connection destination hopping node 401 is, for example, another communication quality value such as a bit error rate or a frame error rate. It may be used.

(About communication management device)
In the above description, the communication management device 403 has been described as a dedicated device having a hardware configuration as shown in FIG. However, the present invention is not limited to this, and the communication management device 403 may be, for example, a wireless communication terminal having a hardware configuration of the hopping node 401 as shown in FIG.

  Thereby, for example, when there is no communication management device 403 in the vicinity, the hopping node 401 can be activated as the communication management device 403 to configure the communication system 400. Further, the communication management device 403 having the hardware configuration of the hopping node 401 can participate in multihop communication as one of the hopping nodes 401.

  FIG. 24 is a sequence diagram illustrating an example of a hopping node activation process according to an embodiment.

  In step S2401, when the hopping node A is activated, in step S2402, the hopping node A determines whether or not the communication management apparatus 403 has already been operated by inquiring about the presence or absence of the communication management apparatus 403 through wireless LAN communication. To do.

  In step S2403, if there is no response from the communication management device 403 within a predetermined time, the hopping node A starts as the communication management device 403. At this time, the hopping node A may realize only the functional configuration of the communication management apparatus 403 as shown in FIG. 9, or further realize the functional configuration of the hopping node 401 as shown in FIG. It may be.

  When the hopping node B is activated in step S2404, in step S2405, the hopping node B inquires about the presence / absence of the communication management device 403 through wireless LAN communication.

  In step S2406, hopping node A that has already been activated as communication management apparatus 403 responds to hopping node B with information indicating that it is operating as communication management apparatus 403 by wireless LAN communication.

  In step S2407, if there is a response from the communication management apparatus 403 within a predetermined time, the hopping node B starts as the hopping node 401, and executes, for example, the processing after step S1001 in FIG.

  With the above processing, even when there is no dedicated communication management apparatus 403, the hopping node 401 automatically functions as the communication management apparatus 403, and the communication system 400 can be configured.

400 communication system (wireless communication system)
401 Hopping node (hopping terminal, wireless communication terminal)
402 Edge node (edge terminal)
403 Communication management device (communication management terminal)
701 Wireless LAN communication unit (third communication unit)
702 Millimeter-wave wireless communication unit (AP) (first communication unit)
703 Millimeter-wave wireless communication unit (STA) (second communication unit)
704 Storage unit 801 Millimeter wave wireless communication unit (STA) (fourth communication unit)
901 Wireless LAN communication unit (fifth communication unit, receiving unit)
902 Information acquisition unit (acquisition unit)
908 Notification unit (transmission unit)
909 Classification part

JP 2009-094628 A

Claims (12)

A method for switching a communication path in a wireless communication system that transmits data simultaneously from a transmission source wireless communication terminal to another wireless communication terminal by multi-hop communication,
A search step in which the first wireless communication terminal that has detected deterioration or disconnection of communication quality of wireless communication performing the multi-hop communication searches for another wireless communication terminal that can be connected by the wireless communication;
Based on the search result of the search step, the second wireless communication terminal connects the other wireless communication terminal connectable by the wireless communication to the transmission source wireless communication terminal in a first communication path. A classification step for classifying into a terminal group and a second terminal group in which a communication path is not connected to the terminal of the transmission source;
The first wireless communication terminal is a terminal group different from the terminal group to which the first wireless communication terminal belongs out of the first terminal group and the second terminal group classified in the classification step. A connection step of connecting to the included wireless communication terminal by the wireless communication;
The communication path switching method is executed.   The communication path switching method according to claim 1, wherein the second wireless communication terminal is a communication management terminal that manages the communication path of the multi-hop communication. The second wireless communication terminal is
When the first wireless communication terminal is connected to the transmission source wireless communication terminal and the communication path, the first wireless communication terminal selects one or more wireless communication terminals included in the second terminal group, and To your wireless communication device,
When the communication path is not connected to the transmission source wireless communication terminal, the first wireless communication terminal selects one or more wireless communication terminals included in the first terminal group, and the first wireless communication terminal The communication path switching method according to claim 1, wherein a notification step of notifying the wireless communication terminal is executed.   The notifying step selects one wireless communication terminal having the best communication quality from wireless communication terminals included in the first terminal group or the second terminal group, and the first wireless communication terminal The communication path switching method according to claim 3, wherein the communication path is notified.   The communication path switching method according to claim 4, wherein the communication quality includes a received signal strength or a throughput value in the first wireless communication terminal.   The communication path switching method according to claim 4 or 5, wherein the communication quality includes a received signal strength or a throughput value in the one wireless communication terminal.   The notifying step selects one wireless communication terminal with the smallest number of relays to the transmission source terminal from among the wireless communication terminals included in the first terminal group or the second terminal group, The communication path switching method according to claim 3, wherein notification is made to the first wireless communication terminal. The first wireless communication terminal has a storage unit for temporarily storing the data,
The first wireless communication terminal transmits / receives the data not transmitted / received to / from the one wireless communication terminal after connecting to the one wireless communication terminal by the wireless communication in the connection step. The communication path switching method according to any one of 1 to 7. The wireless communication system includes:
A first communication unit and a second communication unit that perform first wireless communication that performs multi-hop communication using radio waves having directivity, and second wireless communication that has a wider communication range than the first wireless communication A third communication unit for performing hopping terminals that form different network cells using the first communication unit;
A fourth communication unit for performing the first wireless communication, a terminal connected to one of the network cells;
A communication management terminal comprising a fifth communication unit for performing the second wireless communication, and managing a communication path of multi-hop communication using the second wireless communication;
Including
The communication path switching method according to any one of claims 1 to 8, wherein the first wireless communication terminal is the hopping terminal. A wireless communication system for simultaneously transmitting data from a wireless communication terminal of a transmission source to other wireless communication terminals,
An acquisition unit that acquires information of other connectable wireless communication terminals from the first wireless communication terminal that has detected deterioration or disconnection of communication quality of wireless communication;
Based on the information on the other wireless communication terminal acquired by the acquisition unit, the other wireless communication terminal connectable by the wireless communication is connected to the transmission source wireless communication terminal in a first communication path. A classification unit that classifies the terminal group into a second terminal group that is not connected to the transmission source terminal and a communication path;
Among the first terminal group and the second terminal group classified by the classification unit, one wireless communication terminal included in a terminal group different from the terminal group to which the first wireless communication terminal belongs, A connection control unit for connecting the first wireless communication terminal by the wireless communication;
A wireless communication system. A communication management terminal that manages a communication path for transmitting data by multi-hop communication from a transmission source wireless communication terminal to another wireless communication terminal,
Among the plurality of hopping terminals constituting the communication path of the multi-hop communication, when the communication state transitions from a prescribed state between one hopping terminal and another hopping terminal, from the one hopping terminal, A receiving unit that receives search results of searching for other connectable hopping terminals;
Based on the search result, another wireless communication terminal that can be connected by wireless communication includes a first terminal group in which a communication path is connected to the transmission source wireless communication terminal, and a communication path to the transmission source terminal. A classification unit that classifies the second terminal group that is not connected;
A transmission unit for transmitting a classification result in the classification unit to the one hopping terminal;
A communication management terminal characterized by comprising: The one hopping terminal is
Based on the reception result, the wireless communication is performed to another hopping terminal included in a terminal group different from the terminal group to which the one hopping terminal belongs, out of the first terminal group and the second terminal group. The communication system comprising the communication management terminal according to claim 11, wherein the communication management terminal is connected by a communication method.

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