JP2020198518A - Wireless relay device and wireless lan system using the same and wireless relay method - Google Patents

Abstract

To suppress packet interruptions due to DFS control in a wireless relay device.SOLUTION: Wireless relay master units 1 and 2 are operated as a pair, and communicate with each other, and in normal times, for traffic distribution etc., wireless relay slave units 3A to 3D are distributed and subordinated as shown in (a). As shown by the reference code F1 in (b), when one of the wireless relay master units 1 needs to detect the radar wave and perform CAC under DFS control, the MAC address of the pair of wireless relay master units 2 registered in advance and channel information used are transmitted to the subordinate wireless relay slave units 3A and 3B as shown by the reference code F2, and the connection destination is switched. When the CAC is completed, the wireless relay master unit 1 transmits the transition completion as shown by the reference code F3, and the wireless relay master unit 2 that has received the transition completion causes the wireless relay master unit 1 to switch the connection destination of the migrated wireless relay slave unit again. Therefore, it is possible to suppress the interruption of communication between CACs due to DFS control.SELECTED DRAWING: Figure 2

Description

The present invention relates to a wireless relay device, a wireless LAN system using the wireless relay device, and a wireless relay method. In particular, the wireless LAN system serves as a wireless relay master unit, and the above-mentioned wireless relay device in which a plurality of devices are integrally operated and the wireless relay. The present invention relates to a wireless LAN system including one or a plurality of wireless relay slave units wirelessly connected to a master unit, and preferably a large number of wired or wireless communication terminals connected to the wireless relay slave unit.

The frequency used in the wireless LAN system is 5 GHz in addition to the initial 2.4 GHz band in order to avoid congestion and enable faster data transfer. .. However, the 5 GHz band has traditionally been used in other applications such as weather radar.

Therefore, for example, in the IEEE802.11a standard for wireless LAN, when a frequency band (channel) called W53 or W56 is used, DFS (Dynamic Frequency Selection) is used to prevent interference with other uses such as the weather radar. Control called is performed. When the DFS control detects a radio wave for the other purpose, the channel shifts to avoid interference, and further, whether or not the radio wave for the other use is detected even on the transition destination channel. A CAC (Channel Availability Check) that monitors and determines for a predetermined period is also performed. Therefore, during these times, wireless LAN communication becomes impossible. Further, when the radio wave for the other purpose is detected again when the CAC is performed, the work of searching for another channel is repeated, and communication cannot be continued during that time.

Therefore, in Patent Document 1, a wireless LAN access point is provided with a plurality of wireless interfaces having different SSIDs, and when a weather radar makes it impossible to use the channel used by one wireless interface, another wireless interface is used. A wireless LAN access point that prevents the sessions of subordinate communication terminals from being interrupted by providing the SSID of the wireless interface that can no longer be used by the multi-SSID function that can handle multiple SSIDs with one wireless interface is proposed. Has been done.

JP-A-2009-100210

However, in the above-mentioned conventional technique, although the connection destination of the communication terminal is the same SSID, there is a problem that it is necessary to scan the frequency in order to search for the same SSID, and it takes time to reconnect.

An object of the present invention is to use a wireless relay device as a wireless relay master unit, and when a wireless relay slave unit is connected to the wireless relay master unit, the channel currently used by the wireless relay master unit by DFS and CAC is used. It is an object of the present invention to provide a wireless relay device capable of communicating with a communication terminal on the wireless relay slave unit side, a wireless LAN system using the wireless relay device, and a wireless relay method even if the wireless LAN communication becomes impossible.

The wireless relay device of the present invention includes a wireless relay master unit in which a plurality of units are integrally operated so that information can be communicated with each other, and one or a plurality of wireless relay slave units wirelessly connected to the wireless relay master unit. A wireless relay device used as the wireless relay master unit in a wireless LAN system configured to include the above, and a determination unit that determines channel transition according to radio wave conditions, and the determination unit determines the channel transition. Then, it is characterized by including a switching unit that gives information of the other wireless relay device operated integrally to the wireless relay slave unit to switch the connection destination of the wireless relay slave unit.

Further, the wireless relay method of the present invention includes a wireless relay master unit in which a plurality of units are integrally operated so that information can be communicated with each other, and one or a plurality of wireless relays wirelessly connected to the wireless relay master unit. A determination step for determining channel transition according to radio wave conditions, which is a wireless relay method in a wireless relay device used as the wireless relay master unit in a wireless LAN system including a slave unit, and the determination step. When the channel shift is determined, the information of the other wireless relay device operated integrally is given to the wireless relay slave unit to switch the connection destination of the wireless relay slave unit. It is characterized by.

According to the above configuration, a wireless relay master unit, one or more wireless relay slave units wirelessly connected to the wireless relay master unit, and preferably a large number of communication terminals connected to the wireless relay slave unit. In the wireless LAN system configured with the above, in the wireless relay device used as the wireless relay master unit and the wireless relay method thereof, for example, the frequency bands (channels) of W53 and W56 in the IEEE802.11a standard of the wireless LAN are used. , When DFS (Dynamic Frequency Selection) control is performed to prevent interference with the weather radar, when the wireless relay master unit tries to shift channels according to the radio wave condition, the wireless relay slave unit or the wireless relay The communication terminal under the slave unit cannot communicate during the CAC (Channel Availability Check) that determines whether or not radio waves for other purposes are detected on the channel. Further, when the radio wave for another purpose is detected again when the CAC is performed, the work of searching for another channel is repeated, and communication becomes impossible during that time.

Therefore, in the present invention, a plurality of wireless relay master units are operated integrally and are configured to be able to communicate information with each other. Normally, in order to avoid interference, channels that are as far apart from each other as possible are selected. It is adjusted so that. Preferably, the wireless relay master units operated integrally exchange the traffic amount, radio wave strength, communication error status, etc. of each other's communication terminals without a special controller, autonomously distribute the load, and communicate the communication state. Can be optimized.

Then, in the determination step, when the determination unit determines the channel shift according to the radio wave condition, the wireless relay slave unit usually searches for the wireless relay master unit to be the master station by scanning. In the switching step, the switching unit gives the information of the other wireless relay master unit operated integrally to the wireless relay slave unit, that is, introduces the wireless relay slave unit to which the wireless relay slave unit is connected. Switch (roaming).

Therefore, even if the wireless relay master unit cannot perform wireless LAN communication with the wireless relay slave unit due to DFS and CAC, the wireless relay slave unit can be connected to another wireless relay master unit without searching. , You and many of your subordinate communication terminals will be able to connect to the network continuously (without interruption).

Furthermore, in the wireless relay device of the present invention, when the channel transition is completed, a completion transmitter that transmits the transition completion to the other wireless relay device that is operated integrally receives a notification of the channel transition completion. Then, the switching unit causes the wireless relay slave unit to provide information on the original wireless relay device that is operated integrally, so that the connection destination of the wireless relay slave unit is again connected to the original wireless relay device. It is characterized by further including a completion receiving unit for switching.

Further, in the wireless relay method of the present invention, when the channel transition is completed, the completion transmission step of transmitting the transition completion to the other wireless relay device operated integrally and the notification of the channel transition completion are received. By giving the wireless relay slave unit the information of the original wireless relay device operated integrally, the completion reception step of switching the connection destination of the wireless relay slave unit to the original wireless relay device again is performed. , Further prepared.

According to the above configuration, when the channel transition of the original wireless relay master unit is completed, the completion transmitter transmits the transition completion to the other wireless relay master unit in the completion transmission step, and the communication is transmitted to the other wireless relay master unit. When the completion receiving unit of the device receives the information, in the completion receiving step, the switching unit causes the wireless relay slave unit to give information on the original wireless relay master unit, and the wireless relay master to which the wireless relay slave unit is connected is connected. Switch the unit back to the original wireless relay master unit.

Therefore, even if the connection destination is once transferred to another wireless relay master unit, once the original wireless relay master unit can be relayed, the wireless relay slave unit is prompted to connect to the original wireless relay master unit, so-called. By performing the switchback operation, there is no problem that the traffic of the other wireless relay master unit remains excessive.

Further, the wireless relay device of the present invention is characterized in that the wireless relay master unit and the wireless relay slave unit form an inter-building communication unit.

According to the above configuration, since the inter-building communication unit constitutes an in-house network or the like, it is effective and preferable to prevent a connection failure.

Furthermore, the wireless LAN system of the present invention uses the wireless relay device as the wireless relay master unit, and the wireless relay slave unit uses the wireless relay master of the connection destination according to the information of the other wireless relay device. It is characterized by including a connection master unit determination control unit for switching machines.

According to the above configuration, in a wireless LAN system, it is possible to realize a system capable of seamlessly transferring packets in response to switching of the connection destination of the wireless relay slave unit due to channel switching of the wireless relay master unit by DFS and CAC. it can.

As described above, the wireless relay device and the wireless relay method of the present invention are the wireless relay device serving as the wireless relay master unit, which is operated integrally with the wireless relay device when the channel is changed according to the radio wave condition. Information is given to the wireless relay slave unit, and the connection destination is switched without causing the wireless relay slave unit to be searched.

Therefore, the wireless relay slave unit itself and the communication terminals under it can be continuously (continuously) connected to the network.

It is a block diagram which shows the structure of the wireless LAN system which uses the wireless relay master unit which is the wireless relay device which concerns on one Embodiment of this invention. It is a figure for demonstrating the switching operation of the wireless relay slave unit by the wireless relay master unit. It is a flowchart of FIG. It is a flowchart for demonstrating the master unit switching operation of a wireless relay slave unit by DFS control of a wireless relay master unit, and shows the conventional operation. It is a flowchart for demonstrating the master unit switching operation of a wireless relay slave unit by DFS control of a wireless relay master unit, and shows the operation of this Embodiment.

FIG. 1 is a block diagram of a wireless LAN system 10 according to an embodiment of the present invention. The wireless LAN system 10 includes wireless relay master units 1 and 2, which are wireless relay devices according to the embodiment of the present invention, and wireless relay slave units 3. The wireless LAN system 10 is suitably used for constructing an in-house LAN or the like by wirelessly communicating between buildings, for example.

The wireless relay master units 1 and 2 are configured to be able to communicate with each other via the wired LAN 6, and are connected to the external network 7 from the wired LAN 6. The wireless relay master unit 2 has the same configuration as the wireless relay master unit 1, and they are installed so that the wireless communication areas overlap each other to form a redundant configuration, and are operated integrally and have the same area. Three or more units may be installed in the.

Although omitted in FIG. 1 for the sake of simplification of the drawings, the number of wireless relay slave units 3 under the wireless relay master units 1 and 2 is one or more, and the wireless relay slave unit 3 has 1 Alternatively, a wired or wireless network 8 is connected via a plurality of stages of switching hubs 5. A large number of communication terminals (not shown) are connected to the network 8. The wireless relay slave unit 3 may have the same configuration as the wireless relay master units 1 and 2, and in that case, it is possible to switch between the master unit and the slave unit depending on the setting.

Therefore, the communication terminal connected to the network 8 is connected to the network 7 from the switching hub 5 and the wireless relay slave unit 3 via the wireless relay master unit 1 or 2, and can transmit and receive packets. The wireless relay slave unit 3 and the wireless relay master units 1 and 2 are connected by a wireless LAN such as the IEEE802.11 standard. Further, the network 8 and the communication terminal may be connected by a wireless LAN such as the IEEE802.11 standard or a wired LAN.

Hereinafter, the wireless relay master unit 1 will be described, and the wireless relay master unit 2 is similarly configured. In the wireless relay master unit 1, data is transferred between the wired LAN communication unit 11 on the wired LAN 6 side and the wireless communication unit 12 on the wireless relay slave unit 3, and the wired LAN 6 and the wireless relay slave unit 3 It is possible to send and receive packets in both directions. The wireless relay master units 1 and 2 are operated as a pair, and the pair master unit communication unit 13 is configured to be able to communicate information with each other from the wired LAN communication unit 11 via the wired LAN 6. As a result, the paired wireless relay master units 1 and 2 are adjusted so as to select channels as far apart as possible from each other, usually to avoid interference, without a special controller, and to each other. It is possible to exchange the traffic amount, radio field strength, communication error status, etc. of the communication terminal of the communication terminal, autonomously distribute the load, and optimize the communication state.

The 2.45 GHz band and the 5 GHz band may be used for the communication of the wireless communication unit 12, and the radio wave condition of the wireless communication unit 12 is monitored by the radar detection unit 15. When the radar detection unit 15 detects a weather radar wave when using the frequency bands (channels) of W53 and W56 in the IEEE802.11a standard, the master unit channel determination control unit 16 performs DFS control to prevent interference. To achieve this, perform channel migration.

In the transition, the CAC for determining whether or not the weather radar wave is detected must be performed for a predetermined time, for example, 1 minute even in the transition destination channel, and when the radar wave is detected again during the CAC. , The radar detection unit 15 to the master unit channel determination control unit 16 repeat the work of searching for another channel. Therefore, the wireless relay slave unit 3 itself and the communication terminals under it cannot communicate during that time.

Therefore, it should be noted that in the wireless relay master unit 1 of the present embodiment, the slave unit switching destination channel notification transmitting unit 17 constituting the switching unit together with the master unit channel determination control unit 16 is related to the wireless communication unit 12. It is provided. When a radar wave is detected in the determination step of the radar detection unit 15 serving as the determination unit, the master unit channel determination control unit 16 switches during a grace period until communication is stopped by DFS control, for example, 10 seconds. In the step, the information (MAC address and channel used) of the other wireless relay master unit 2 stored in advance in the pair master unit communication unit 13 is read out and given to the slave unit switching destination channel notification transmission unit 17 to wirelessly. Transmission is performed from the communication unit 12 to the wireless relay slave unit 3. That is, the wireless relay slave unit 3 is introduced to the destination to be connected next, and the connection destination is switched. As a result, the wireless relay slave unit 3 and the communication terminals under it can be continuously (continuously) connected to the network 7.

On the other hand, since the wireless relay slave unit 3 can also be the wireless relay master unit 1 and 2 depending on the settings as described above, the basic configuration is similar, and the switching hub 5 is connected to the network 8. It is configured to include a wired LAN communication unit 31, a wireless communication unit 32 on the wireless relay master units 1 and 2 side, and a channel notification receiving unit 37 that receives the connection destination notification described above.

Normally, as will be described in detail later, the scan control unit 35 in the wireless communication unit 32 scans the beacon signal from the wireless relay master unit at a predetermined cycle, and connects according to the scan result. The master unit determination control unit 36 determines a wireless relay master unit having a good radio wave condition as a connection destination. On the other hand, as described above, the channel notification receiving unit 37 receives information (MAC address and used channel) of the new wireless relay master unit 2 from the currently connected wireless relay master unit 1 via the wireless communication unit 32. Upon reception, the connection master unit determination control unit 36 switches the connection destination wireless relay master unit from reference numeral 1 to 2 according to the information.

The situation will be described with reference to FIGS. 2 and 3 in addition to FIG. FIG. 2 is a diagram for explaining a switching operation of the wireless relay slave unit 3 by the wireless relay master units 1 and 2, and FIG. 3 is a flowchart thereof. The wireless relay master units 1 and 2 are operated as a pair of two units, and the pair master unit communication unit 13 is configured to be able to communicate information with each other via a wired LAN 6. Therefore, when the paired wireless relay master units 1 and 2 start communication (relay) in step S11 without a special controller, normally, in order to avoid interference, as shown in FIG. 2A. , The master unit channel determination control unit 16 is adjusted to select channels as far apart as possible from each other, and at the same time, it autonomously exchanges the traffic amount, radio field strength, communication error status, etc. of each other's communication terminals. It is possible to distribute the load and optimize the communication status. In FIG. 2A, four wireless relay slave units 3A, 3B, 3C, and 3D are shown as the wireless relay slave units 3 (hereinafter, collectively referred to by the above-mentioned reference reference numeral 3), and wirelessly. The relay slave units 3A and 3B are under the control of the wireless relay master unit 1, and the wireless relay slave units 3C and 3D are under the control of the wireless relay master unit 2.

Then, in step S12, as shown by the reference reference numeral F1 in FIG. 2B, when the radar detection unit 15 detects the radar wave and the master unit channel determination control unit 16 determines the channel shift, it is usually under the control. A certain wireless relay slave units 3A and 3B lose communication, and scan to search for a wireless relay master unit 2 as a master station. On the other hand, in the present embodiment, as shown in step S13, the slave unit switching destination channel notification transmission unit 17 carries the information of another paired wireless relay master unit 2 from the wireless communication unit 12. The beacon signal is transmitted, and the wireless communication unit 32 of the wireless relay slave units 3A and 3B introduces the channel notification receiving unit 37. As a result, when the wireless relay slave units 3A and 3B receive the wireless relay slave units 3A and 3B in step S21, the wireless relay master unit to be used is switched from the reference code 1 to the reference code 2 in step S22 as indicated by the reference code F2. ..

After that, in the original wireless relay master unit 1, the channel transition (DFS) is performed by the master unit channel determination control unit 16 in step S14, and the free channel determination (CAC) is performed by the radar detection unit 15 in step S15. When the process is completed and the channel transfer by the master unit channel determination control unit 16 is completed, in step S16, the pair master unit communication unit 13 serving as the completion transmission unit is wired from the wired LAN communication unit 11 as indicated by the reference code F3. The transition completion is transmitted to another pair of wireless relay master units 2 via the LAN 6.

When the communication is received by the pair master unit communication unit 13 which is the completion reception unit from the wired LAN 6 via the wired LAN communication unit 11 in the other wireless relay master unit 2, the master unit channel determination control is performed in step S31. The unit 16 gives information on the original wireless relay master unit 1 to be paired to each of the previously switched wireless relay slave units 3A and 3B via the wireless communication unit 12, and in step S23, the reference reference numeral F4 As shown in FIG. 2, the connection destination used by those wireless relay slave units 3A and 3B is switched to the original wireless relay master unit 1 again, and the state of FIG. 2A is returned.

In this way, a large number of communication terminals under each of the wireless relay slave units 3A, 3B, 3C, and 3D can be continuously (continuously) connected to the external network 7. Further, even if the connection destination is once transferred to another wireless relay master unit (2 in the above example), once the original wireless relay master unit (1 in the above example) can be relayed, the wireless relay slave unit By prompting (3A, 3B in the above example) to connect to the original wireless relay master unit (1 in the above example) and performing a so-called switchback operation, another wireless relay master unit (described above). In the example of, there is no problem that the traffic of 2) remains excessive as shown in FIG. 2 (b).

Here, with reference to FIGS. 4 and 5, the operation of switching the master unit of the wireless relay slave unit 3 by DFS control of the wireless relay master units 1 and 2 of FIG. 2 is compared. In the conventional switching operation shown in FIG. 4, in step S51, when the wireless relay slave unit 3 is connected to the wireless relay master unit 1 due to radar detection, the channel shifts and the connection to the external network 7 is interrupted. When scanning of the beacon signal from the other wireless relay master unit is started, the channel is moved in step S52, and the beacon signal is received on that channel in step S53, a probe request requesting connection is transmitted in step S54. .. In step S55, a probe response in response to the probe response is received from the other wireless relay master unit, and in step S56, it is determined whether or not scanning has been completed for all channels other than the channel of the original wireless relay master unit 1. If it is not finished, the process returns to step S52 to continue scanning.

In step S56, when the scanning of all channels is completed, the process proceeds to step S57, and among the channels that received the probe response, the wireless relay master unit having the best conditions such as radio field strength and traffic is selected, and in step S58. , Connect to the wireless relay master unit. If the beacon signal is not received in step S53, it is determined in step S59 whether or not it is within a predetermined time from the channel movement in step S52. If it is within a predetermined time, the process returns to step S53 to continue reception, and if it is timed out. , The completion determination of all channels in step S56 is performed.

On the other hand, in the switching operation of the present embodiment shown in FIG. 5, the wireless relay slave unit 3 has information on the wireless relay master unit 2 to be switched in in step S61 before the wireless relay master unit 1 shifts to the channel by DFS control. Is received, and in step S62, the channel is moved according to the information. In steps S63 and S69, as in steps S53 and S59, the channel waits until the beacon signal is received, and when the beacon signal is received, the connection to the wireless relay master unit 2 is started as it is in step S64. On the other hand, when the time-out occurs in step S59, it is determined that the connection to the wireless relay master unit 2 has failed, and the normal connection procedure of steps S51 to S59 of FIG. 4 is performed.

Therefore, comparing FIG. 4 and FIG. 5, in the conventional switching operation, it is necessary to scan the beacon signals of all channels other than the channel used by the wireless relay master unit 1 in which communication is interrupted. Therefore, in the switching operation of the present embodiment, it is sufficient to receive the beacon signal of only the channel that received the information, and the time during which the communication is interrupted can be extremely reduced.

In this way, the wireless LAN system 10 of the present embodiment uses the above-mentioned wireless relay master units 1 and 2 as the wireless relay device, and wirelessly accompanies channel switching of the wireless relay master units 1 and 2 by DFS or the like. The packet to the communication terminal can be continuously transferred in response to the switching of the connection destination of the relay slave unit 3. That is, the above-mentioned wireless LAN system 10 uses the wireless relay master units 1 and 2 operated in pairs as the connection destination of the wireless relay slave unit 3, for example, one is used regularly and the other is used as an emergency. Such a redundant configuration can be realized. For example, when increasing redundancy, three or more wireless relay master units may be operated integrally.

Alternatively, the wireless relay master units 1 and 2 may be operated by the two units, and the load (communication terminal) may be distributed at all times. As a result, it is possible to realize a system in which communication is not interrupted in an emergency while responding to an increase in load (communication terminal).

Further, the wireless relay devices 1 and 2 may be wireless relay devices installed indoors such as a wireless LAN access point, and particularly when two devices are operated as a pair as described above, inter-building communication is performed. Therefore, it may be a wireless relay device installed outdoors.

Although the present invention has been described based on examples, the present invention is not limited to these examples, and can be implemented in various forms without departing from the gist thereof. For example, in the embodiment, the wireless relay device is used as the wireless relay master unit 1 and 2, and the wireless relay slave unit 3 which is the wireless relay device is connected to the communication terminal in a multi-stage configuration. The terminal may be wirelessly connected. In that case, at the time of DFS control, the wireless relay device gives information of another wireless relay device to the communication terminal, and the communication terminal that receives the information performs an operation of switching the connection like the above-mentioned wireless relay slave unit 3. It will be.

1,2 Wireless relay master unit (wireless relay device)
10 Wireless LAN system 11 Wired LAN communication unit 12 Wireless communication unit 13 Pair master unit communication unit 15 Radar detection unit 16 Master unit channel determination control unit 17 Slave unit switching destination channel notification transmission unit 3 Wireless relay slave unit 31 Wired LAN communication unit 32 Wireless communication unit 35 Scan control unit 36 Connection master unit determination control unit 37 Channel notification receiver 5 Switching hub 6 Wired LAN
7 External network 8 Network

Claims (6)

A wireless configuration including a wireless relay master unit in which a plurality of units are operated integrally and can communicate information with each other, and one or a plurality of wireless relay slave units wirelessly connected to the wireless relay master unit. A wireless relay device used as the wireless relay master unit in a LAN system.
Judgment unit that determines channel transition according to radio wave conditions,
When the determination unit determines the channel shift, the switching unit and the switching unit that give the information of the other wireless relay device operated integrally to the wireless relay slave unit to switch the connection destination of the wireless relay slave unit. A wireless relay device characterized by including. When the channel transition is completed, a completion transmitter that transmits the transition completion to the other wireless relay device operated integrally, and
Upon receiving the notification of the completion of the transition of the channel, the switching unit causes the wireless relay slave unit to receive information on the original wireless relay device operated integrally, so that the connection destination of the wireless relay slave unit is The wireless relay device according to claim 1, further comprising a completion receiving unit that switches the device back to the original wireless relay device. The wireless relay device according to any one of claims 1 to 3, wherein the wireless relay master unit and the wireless relay slave unit constitute an inter-building communication unit. The wireless relay device according to any one of claims 1 to 3 is used as the wireless relay master unit.
The wireless LAN system is characterized in that the wireless relay slave unit includes a connection master unit determination control unit that switches a connection destination wireless relay master unit according to information of the other wireless relay device. A wireless configuration including a wireless relay master unit in which a plurality of units are operated integrally and can communicate information with each other, and one or a plurality of wireless relay slave units wirelessly connected to the wireless relay master unit. A wireless relay method in a wireless relay device used as the wireless relay master unit in a LAN system.
Judgment step to judge channel transition according to radio wave condition,
When the channel shift is determined in the determination step, information on the other wireless relay device operated integrally is given to the wireless relay slave unit to switch the connection destination of the wireless relay slave unit. A wireless relay method comprising. When the channel transition is completed, a completion transmission step of transmitting the transition completion to the other wireless relay device operated integrally, and
Upon receiving the notification of the completion of the transition of the channel, the wireless relay slave unit is given the information of the original wireless relay device operated integrally, so that the connection destination of the wireless relay slave unit is the original wireless relay. The wireless relay method according to claim 5, further comprising a completion reception step of switching the device again.

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