WO2019131259A1

WO2019131259A1 - Communication system control method and communication system

Info

Publication number: WO2019131259A1
Application number: PCT/JP2018/046265
Authority: WO
Inventors: 亘北村; 桑原　哲也; 忠與香川
Original assignee: 村田機械株式会社; サイレックス・テクノロジー株式会社
Priority date: 2017-12-26
Filing date: 2018-12-17
Publication date: 2019-07-04
Also published as: TW201929504A

Abstract

This control method of a communication system (2) includes: a step for acquiring a first radio wave intensity from a first access point (20); a step for acquiring a second radio wave intensity from a second access point (22); a step for determining whether to change a wireless access destination of a specific communication device from the first access point (20) to the second access point (22) on the basis of the first radio wave intensity and the second radio wave intensity; a step for cutting off wireless connection between the specific communication device and the first access point (20), and establishing wireless connection between the specific communication device and the second access point (22), when it is determined that the wireless connection destination of the specific communication device is to be changed; and a step for updating corresponding information stored in a storage unit (34) when the wireless connection is established between the specific communication device and the second access point (22).

Description

Control method of communication system and communication system

The present invention relates to a control method and communication system of a communication system which performs communication using a wireless network.

A communication system is known that performs communication using a wireless network. The communication system disclosed in Patent Document 1 includes a master station, a plurality of base stations connected to the master station, and a mobile station that communicates with the master station via a wireless connection with any of the plurality of base stations. ing.

In this communication system, a so-called area identification system is adopted as a system for determining the radio connection destination of the mobile station. In this area identification method, the master station acquires position information indicating the current position of the mobile station from the mobile station via the base station. The parent station determines a specific base station that has jurisdiction over the area in which the mobile station is located among a plurality of base stations as a wireless connection destination of the mobile station based on the acquired position information.

Patent No. 3085154

However, in the above-described area identification method, for example, when a specific base station is determined as a wireless connection destination of a mobile station, when an obstacle is present in the vicinity of the specific base station, the specific area Communication may not be possible between the base station and the mobile station.

The present invention has been made in view of such problems, and its object is to control a communication system capable of reliably executing communication between a base station and a mobile station (access point and communication apparatus). A method and communication system is provided.

In order to achieve the above object, in a control method of a communication system according to an aspect of the present invention, a management apparatus, a plurality of access points connected to the management apparatus, and any one of the plurality of access points A control method of a communication system, comprising: at least one communication device communicating with the management device via a wireless connection, wherein the management device comprises any one of the plurality of access points and the one or more communication devices. A storage unit for storing correspondence information indicating that the connection is wirelessly connected, the control method comprising: (a) the management apparatus, a specific communication apparatus among the one or more communication apparatuses, and the plurality of communication apparatuses Acquiring from the first access point a first radio wave intensity between the access point and a first access point wirelessly connected to the specific communication device; And (b) the management apparatus is configured to transmit a second radio wave intensity between the specific communication apparatus and a second access point different from the first access point among the plurality of access points. (C) acquiring, from the second access point, the wireless connection destination of the specific communication device based on the first radio wave intensity and the second radio wave intensity; Determining whether to change the access point to the second access point, and (d) the management apparatus determines the wireless connection destination of the specific communication apparatus from the first access point to the second access point Disconnecting the wireless connection between the specific communication device and the first access point when it is determined that the access point should be changed to an access point of Establishing a wireless connection with two access points; and (e) when the wireless connection between the specific communication device and the second access point is established, The contents of the correspondence information stored in the storage unit indicate that the particular communication apparatus and the first access point are wirelessly connected, and the particular communication apparatus and the second access point Updating to a content indicating that the wireless connection is established.

According to this aspect, for example, when an obstacle is present in the vicinity of the first access point, the first radio wave strength between the first access point and the specific communication device is reduced. At this time, the communication system changes the wireless connection destination of the specific communication device from the first access point to the second access point based on the first radio wave strength and the second radio wave strength. Communication between the access point and a particular communication device can be performed reliably. Further, when the wireless connection between the specific communication device and the second access point is established, the correspondence information stored in the storage unit is updated, so that the management device performs wireless connection of the specific communication device. It is possible to accurately grasp the future. Note that among the steps (a) to (e) described above, the order in which the steps are performed is not particularly limited for the steps whose order is not specified. The same applies to each step described later.

For example, in (c), when the first radio wave intensity is smaller than the second radio wave intensity, the management device is configured to wirelessly connect the specific communication device from the first access point. It may be configured to determine that the access point should be changed to the second access point.

According to this aspect, the management apparatus can change the wireless connection destination of the specific communication apparatus from the first access point to a second access point in a better communication state.

For example, in (b), when the first radio wave intensity is less than a predetermined threshold, the management apparatus is configured to acquire the second radio wave intensity from the second access point. It is also good.

According to this aspect, the management device acquires the second radio wave intensity from the second access point after the communication state of the first access point is not good. Therefore, when the communication state of the first access point is good, the management apparatus can omit the process of acquiring the second radio wave intensity.

For example, the storage unit further stores position information indicating a position of each of the plurality of access points, and the control method further includes: (f) the management apparatus performs the plurality of operations based on the position information Identifying the second access point located at a position closest to the first access point among the access points of the network, and in the (b), the management apparatus determines the second access point The second radio wave intensity may be acquired from the second access point when the

According to this aspect, the management apparatus is a candidate of the change destination of the wireless connection destination of the specific communication apparatus for the second access point arranged at a position closest to the first access point among the plurality of access points. Can be identified as

For example, the control method may further include the steps of: (g) the management apparatus determining whether or not a predetermined number or more of the communication apparatuses are wirelessly connected to the second access point; (h) the management When a device determines that the predetermined number or more of communication devices are wirelessly connected to the second access point, the wireless connection between the specific communication device and the second access point is disconnected Establishing a wireless connection between the particular communication device and a third access point different from the second access point of the plurality of access points; (i) the particular communication When the wireless connection between the device and the third access point is established, the management device determines the correspondence information stored in the storage unit as the specific communication device and the specific communication device. Updating the content to indicate that the specific communication device and the third access point are wirelessly connected from the content indicating that the wireless access point is wirelessly connected to You may

According to this aspect, the management device can suppress wireless connection of a predetermined number or more of communication devices to the second access point.

For example, the predetermined number may be configured to be smaller than the maximum number of connections that the second access point can wirelessly connect.

According to this aspect, the number of communication devices wirelessly connected to the second access point can be suppressed to less than the maximum number of connections that the second access point can wirelessly connect. This allows, for example, the second access point to leave a surplus for transmitting a polling signal for searching for a communication apparatus to be a wireless connection destination.

Further, a communication system according to an aspect of the present invention is a management apparatus, a plurality of access points connected to the management apparatus, and the management apparatus through wireless connection with any of the plurality of access points. A storage unit including: at least one communication device for communicating, wherein the management device stores correspondence information indicating that any one of the plurality of access points is wirelessly connected to the one or more communication devices. And a first radio wave intensity between a specific communication device of the one or more communication devices and a first access point wirelessly connected to the specific communication device of the plurality of access points. The first acquisition unit acquired from the first access point, the specific communication device, and the first access point among the plurality of access points are different. A second acquisition unit for acquiring a second radio wave intensity between the second access point and the second access point, and the specific one based on the first radio wave intensity and the second radio wave intensity; A determination unit that determines whether the wireless connection destination of the communication device should be changed from the first access point to the second access point, and the wireless connection destination of the specific communication device is the first access point Disconnecting the wireless connection between the specific communication device and the first access point when it is determined that the second access point should be changed to the second access point, and Stored in the storage unit when a switching unit for establishing a wireless connection with two access points and a wireless connection between the specific communication device and the second access point are established The specific communication device and the second access point are wirelessly connected based on the content indicating that the specific communication device and the first access point are wirelessly connected with the correspondence information. And an update unit that updates the content to indicate the content.

According to this aspect, for example, when an obstacle is present in the vicinity of the first access point, the first radio wave strength between the first access point and the specific communication device is reduced. At this time, the management apparatus changes the wireless connection destination of the specific communication apparatus from the first access point to the second access point based on the first radio wave strength and the second radio wave strength. Communication between the access point and a particular communication device can be performed reliably. Further, when the wireless connection between the specific communication device and the second access point is established, the correspondence information stored in the storage unit is updated, so that the management device performs wireless connection of the specific communication device. It is possible to accurately grasp the future.

According to the control method and the like of the communication system according to an aspect of the present invention, communication between the access point and the communication device can be reliably executed.

FIG. 1 is a diagram schematically showing the configuration of a carrier system which is an application example of the communication system according to the first embodiment. FIG. 2 is a block diagram showing the configuration of the communication system according to the first embodiment. FIG. 3 is a conceptual diagram showing the configuration of the communication system according to the first embodiment. FIG. 4 is a diagram showing an example of a management table according to the first embodiment. FIG. 5 is a conceptual diagram showing the configuration of the communication system according to Embodiment 1 in the case where an obstacle is present in the vicinity of the first access point. FIG. 6A is a sequence diagram showing an operation of the communication system according to the first embodiment. FIG. 6B is a sequence diagram showing an operation of the communication system according to Embodiment 1. FIG. 7 is a diagram showing an example of the management table after update according to the first embodiment. FIG. 8 is a conceptual diagram showing the configuration of the communication system according to the second embodiment. FIG. 9 is a diagram showing an example of a management table according to the second embodiment. FIG. 10 is a sequence diagram showing an operation of the communication system according to the second embodiment. FIG. 11 is a diagram showing an example of the management table after update according to the second embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that all the embodiments described below show general or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. Moreover, among the components in the following embodiments, components not described in the independent claims are described as optional components.

Embodiment 1
[1-1. Configuration of Carrier System]
First, the configuration of a carrier system 4 which is an application example of the communication system 2 according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram schematically showing the configuration of a carrier system 4 which is an application example of the communication system 2 according to the first embodiment.

As shown in FIG. 1, for example, in a semiconductor manufacturing plant, the carrier system 4 is for carrying a front opening unified pod (FOUP) in which wafers are stored by the first carrier 6 and the second carrier 8. It is a system. Each of the first carrier 6 and the second carrier 8 is, for example, a so-called OHT (Overhead Hoist Transfer) that travels unmanned along a rail 10 installed on a ceiling of a semiconductor manufacturing plant.

Each of the first transport vehicle 6 and the second transport vehicle 8 receives the power supplied from the power supply device 12 in a contactless manner by the electromagnetic induction phenomenon through the feed path 14 laid along the rail 10 be able to. Thus, each of the first carrier 6 and the second carrier 8 can travel along the rail 10 while receiving the supply of power from the feed path 14.

As shown in FIG. 1, for example, in a semiconductor manufacturing plant, a plurality of semiconductor processing apparatuses 16 are arranged side by side directly below the rails 10. Each of the plurality of semiconductor processing apparatuses 16 has a mounting port (not shown) for mounting the FOUP. The loading port is for transferring the FOUP to / from each of the first carrier 6 and the second carrier 8. Although only three semiconductor processing devices 16 are illustrated in FIG. 1 for convenience of explanation, four or more semiconductor processing devices 16 may be disposed.

[1-2. Configuration of communication system]
Next, the configuration of the communication system 2 according to Embodiment 1 will be described with reference to FIGS. 1 to 4. FIG. 2 is a block diagram showing the configuration of the communication system 2 according to the first embodiment. FIG. 3 is a conceptual diagram showing the configuration of the communication system 2 according to the first embodiment. FIG. 4 is a diagram showing an example of a management table according to the first embodiment.

As shown in FIGS. 1 to 3, the communication system 2 includes a management device 18, a first access point 20 (hereinafter also referred to as "AP1"), and a second access point 22 (hereinafter referred to as "AP2"). , The first processing unit 24 (hereinafter also referred to as “EQ1”), the second processing unit 26 (hereinafter also referred to as “EQ2”), and the third processing unit 28 (hereinafter “EQ3”) And a first carrier 6 (hereinafter also referred to as "OHT1") and a second carrier 8 (hereinafter also referred to as "OHT2").

As shown in FIG. 2, the first access point 20, the second access point 22, the first processing unit 24, the second processing unit 26, the third processing unit 28, the first carrier 6 and the first Each of the two carriers 8 is connected by, for example, a wireless network 30 conforming to the IEEE 802.11 series. The wireless network 30 is constructed of, for example, WiFi (registered trademark) in the 2.4 GHz band or 5 GHz band. Also, the management device 18 and each of the first access point 20 and the second access point 22 are connected to a wired network established by a wired LAN (Local Area Network) using, for example, a cable.

In the example illustrated in FIG. 3, the first access point 20 is wirelessly connected to each of the first processor 24, the second processor 26, and the first carrier 6 (an example of a communication device). The second access point 22 is wirelessly connected to each of the third processing device 28 and the second carrier 8 (an example of a communication device). In FIG. 3, circles indicated by two broken lines respectively represent the communicable areas of the first access point 20 and the second access point 22. The first processing device 24 is arranged in an area where the communicable area of the first access point 20 and the communicable area of the second access point 22 overlap.

In order to suppress radio interference, the first access point 20 and the second access point 22 use different wireless communication channels, for example,

channels

1 and 6 of IEEE 802.11g, for example. Each of the first carrier 6 and the second carrier 8 determines a wireless communication channel to be used based on its position.

Each of the first carrier 6 and the second carrier 8 functions as a station (a slave station) in the wireless LAN.

The management device 18 includes a first access point 20, a second access point 22, a first processor 24, a second processor 26, a third processor 28, a first carrier 6, and a second It is a computer for managing the carrier 8. As shown in FIG. 2, the management device 18 includes a communication unit 32, a storage unit 34, and a control unit 36.

The communication unit 32 performs wired communication with each of the first access point 20 and the second access point 22.

The storage unit 34 is a memory for storing a management table for managing each of the first access point 20 and the second access point 22. The management table is, for example, a data table as shown in FIG.

In the example illustrated in FIG. 4, data regarding the first access point 20 is stored in the first row of the management table. Specifically, in the first line of the management table, a) position information "0001" indicating the position of the first access point 20, and b) correspondence information indicating the wireless connection destination of the first access point 20. “EQ1, EQ2, OHT1” is stored. The position information “0001” is a number assigned to the area in which the first access point 20 is located. The correspondence information “EQ1, EQ2, OHT1” indicates that each of the first processing device 24, the second processing device 26, and the first transport vehicle 6 is wirelessly connected to the first access point 20. It is.

The second line of the management table stores data related to the second access point 22. Specifically, on the second line of the management table, a) position information "0002" indicating the position of the second access point 22, and b) correspondence information indicating the wireless connection destination of the second access point 22. "EQ3, OHT2" is stored. Position information “0002” is a number assigned to the area in which the second access point 22 is located. The correspondence information “EQ3, OHT2” is information indicating that each of the third processing device 28 and the second carrier 8 is wirelessly connected to the second access point 22.

Although FIG. 4 illustrates the case where the management table includes data related to two access points (first access point 20 and second access point 22) for convenience of explanation, three or more communication systems 2 are provided. When the access point is provided, the management table may include data on three or more access points.

The control unit 36 generates various command data to be transmitted to each of the first access point 20 and the second access point 22 based on the management table stored in the storage unit 34. Furthermore, the control unit 36 has a plurality of functions as described below.

That is, for example, in the description of the embodiment of the present invention, the control unit 36 determines the first radio wave intensity between the first processing device 24 (an example of the specific communication device) and the first access point 20. And a function as a first acquisition unit that acquires from the first access point 20), which will be described as the intensity of radio waves transmitted from the access point and received by the processing device. In addition, the control unit 36 has a function as a second acquisition unit that acquires, for example, the second radio wave intensity between the first processing device 24 and the second access point 22 from the second access point 22. Have.

Further, the control unit 36 should change the wireless connection destination of the first processing device 24 from the first access point 20 to the second access point 22 based on the first radio wave intensity and the second radio wave intensity. It has a function as a determination unit that determines whether or not it is. In addition, when it is determined that the wireless connection destination of the first processing device 24 should be changed from the first access point 20 to the second access point 22, the control unit 36 determines that the first processing device 24 is wirelessly connected. It has a function as a switching unit that switches the connection destination from the first access point 20 to the second access point 22. Further, the control unit 36 has a function as an updating unit that updates the correspondence information of the management table stored in the storage unit 34. The control unit 36 is realized, for example, by a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

The first access point 20 functions as an access point in a wireless LAN. As shown in FIG. 2, the first access point 20 includes a communication unit 38, a storage unit 40, and a control unit 42. The communication unit 38 performs wired communication with the management device 18 and performs wireless communication with each of the first processing device 24, the second processing device 26, and the first carrier 6. The storage unit 40 stores the radio wave intensity and the like acquired from each of the first processing device 24, the second processing device 26, and the first carrier 6. The control unit 42 is configured to transmit various command data to be transmitted to each of the first processing device 24, the second processing device 26, and the first transport vehicle 6, and various response data to be transmitted to the management device 18. Generate

Similar to the first access point 20, the second access point 22 functions as an access point in a wireless LAN. As shown in FIG. 2, the second access point 22 includes a communication unit 44, a storage unit 46, and a control unit 48. The communication unit 44 performs wired communication with the management device 18 and wireless communication with each of the third processing device 28 and the second transport vehicle 8. The storage unit 46 stores the radio wave intensity and the like acquired from each of the third processing device 28 and the second transport vehicle 8. The control unit 48 generates various command data to be transmitted to each of the third processing device 28 and the second transport vehicle 8, various response data to be transmitted to the management device 18, and the like. Note that the first access point 20 and the second access point 22 have a common configuration, and the first processing unit 24, the second processing unit 26, the third processing unit 28, the first transport Whether it can communicate with each of the car 6 and the second carrier 8 depends on their layout.

The first processing unit 24 functions as a station (child station) in the wireless LAN. Specifically, the first processing unit 24 is the semiconductor processing unit 16 in the carrier system 4 shown in FIG. As shown in FIG. 2, the first processing device 24 includes a communication unit 50, a storage unit 52, and a control unit 54. The communication unit 50 wirelessly communicates with the first access point 20 (or the second access point 22). The storage unit 52 stores the radio wave intensity and the like with the first access point 20 (or the second access point 22) measured by the first processing device 24. The control unit 54 generates various response data and the like to be transmitted to the first access point 20 (or the second access point 22).

Each of the second processing unit 26 and the third processing unit 28 functions as a station (a slave station) in the wireless LAN like the first processing unit 24. The semiconductor processing in the carrier system 4 shown in FIG. It is an apparatus 16. The configuration of each of the second processing unit 26 and the third processing unit 28 is the same as the configuration of the first processing unit 24, and thus the description and illustration thereof will be omitted.

[1-3. Operation of communication system]
Next, the operation of the communication system 2 according to the first embodiment will be described with reference to FIGS. 5 to 7. FIG. 5 is a conceptual diagram showing the configuration of the communication system 2 according to the first embodiment when an obstacle 56 exists in the vicinity of the first access point 20. As shown in FIG. 6A and 6B are sequence diagrams showing an operation of the communication system 2 according to the first embodiment. FIG. 7 is a diagram showing an example of the management table after update according to the first embodiment.

As shown in FIG. 5, for example, when an obstacle 56 is present between the first access point 20 and the first processing device 24, the obstacle 56 makes it possible to use the first access point 20. Distribution of radio wave intensity changes. Therefore, communication may not be reliably performed between the first access point 20 and the first processing device 24. Therefore, in the communication system 2 according to the first embodiment, the wireless connection destination of the first processing device 24 can be changed from the first access point 20 to the second access point 22 as described below. .

As shown in FIG. 6A, the communication unit 32 of the management device 18 transmits the command data CD1 generated by the control unit 36 to the first access point 20 (S101). The command data CD1 is data for requesting the first processing device 24 to transmit the first radio wave intensity between the first processing device 24 and the first access point 20. The command data CD1 includes, for example, an IP address of the first processing device 24 as a transmission destination IP (Internet Protocol) address of the command data CD1.

The communication unit 38 of the first access point 20 receives the command data CD1 transmitted from the management device 18 (S102). The communication unit 38 of the first access point 20 transmits the received command data CD1 to the first processing device 24 (S103).

The communication unit 50 of the first processing device 24 receives the command data CD1 transmitted from the first access point 20 (S104). The control unit 54 of the first processing device 24 generates response data RD1 based on the received command data CD1. The response data RD1 is data for replying the first radio wave intensity between the first processing device 24 and the first access point 20 to the first access point 20. The response data RD1 includes the first radio wave intensity (for example, -70 dbm) between the first processing device 24 and the first access point 20, and the like. The first radio wave intensity is the radio wave intensity when the command data CD1 is received, and is measured by the control unit 54 of the first processing device 24.

The communication unit 50 of the first processing device 24 transmits the response data RD1 to the first access point 20 (S105). The communication unit 38 of the first access point 20 receives the response data RD1 transmitted from the first processing device 24 (S106).

The communication unit 38 of the first access point 20 transmits the received response data RD1 to the management device 18 (S107). The communication unit 32 of the management device 18 receives the response data RD1 transmitted from the first access point 20 (S108). Thereby, the control unit 36 of the management device 18 acquires the first radio wave intensity from the received response data RD1, and compares the first radio wave intensity with a predetermined threshold (for example, -60 dbm).

At this time, as described above, since the obstacle 56 exists between the first access point 20 and the first processing device 24, the first radio wave intensity is significantly reduced. When the control unit 36 of the management device 18 determines that the first radio wave intensity is less than the predetermined threshold (YES in S109), the communication unit 32 of the management device 18 generates a command generated by the control unit 36. The data CD2 is transmitted to the first access point 20 (S110). The command data CD2 is data for requesting the first processing device 24 to disconnect the wireless connection with the first access point 20.

The communication unit 38 of the first access point 20 receives the command data CD2 transmitted from the management device 18 (S111). The communication unit 38 of the first access point 20 transmits the received command data CD2 to the first processing device 24 (S112).

The communication unit 50 of the first processing device 24 receives the command data CD2 transmitted from the first access point 20 (S113). The control unit 54 of the first processing device 24 disconnects the wireless connection with the first access point 20 based on the received command data CD2 (S114).

On the other hand, when it is determined in step S109 that the first radio wave intensity is equal to or higher than the predetermined threshold (NO in S109), the control unit 36 of the management device 18 does not execute each process after step S110. In this case, the control unit 36 of the management device 18 does not acquire response data RD2 described later.

When the first access point 20 can not receive the response data RD1 in step S106, the first access point 20 does not transmit the response data RD1 to the management device 18 in step S107. In this case, since the control unit 36 of the management apparatus 18 does not receive the response data RD1, the control unit 36 of the management apparatus 18 starts step S110 without performing the determination of step S109. A process of switching from the access point 20 to the second access point 22 is performed. Here, when the wireless connection between the first access point 20 and the first processing device 24 has already been disconnected at the time when step S109 ends, the respective processes of steps S110 to S114 are omitted.

The control unit 36 of the management device 18 specifies the second access point 22 disposed at the position closest to the first access point 20 based on the position information of the management table stored in the storage unit 34 (S115 ).

The communication unit 32 of the management device 18 transmits the command data CD3 generated by the control unit 36 to the second access point 22 (S116). The command data CD3 is data for requesting the second access point 22 to temporarily establish a wireless connection with the first processing device 24.

The communication unit 44 of the second access point 22 receives the command data CD3 transmitted from the management device 18 (S117). The communication unit 44 of the second access point 22 transmits a polling signal to the first processing device 24 based on the received command data CD3 (S118).

The communication unit 50 of the first processing device 24 receives the polling signal transmitted from the second access point 22 (S119). The control unit 54 of the first processing device 24 establishes a wireless connection with the second access point 22 based on the received polling signal (S120).

Moving from FIG. 6A to FIG. 6B, as shown in FIG. 6B, the communication unit 32 of the management device 18 transmits the command data CD4 generated by the control unit 36 to the second access point 22 (S121). The command data CD4 is data for requesting the first processing device 24 to transmit the second radio field strength between the first processing device 24 and the second access point 22. The command data CD4 includes, for example, an IP address of the first processing device 24 as a transmission destination IP address of the command data CD4.

The communication unit 44 of the second access point 22 receives the command data CD4 transmitted from the management device 18 (S122). The communication unit 44 of the second access point 22 transmits the received command data CD4 to the first processing device 24 (S123).

The communication unit 50 of the first processing device 24 receives the command data CD4 transmitted from the second access point 22 (S124). The control unit 54 of the first processing device 24 generates response data RD2 based on the received command data CD4. The response data RD2 is data for replying the second radio wave intensity between the first processing device 24 and the second access point 22 to the second access point 22. The response data RD2 includes the second radio wave intensity (for example, -40 dbm) between the first processing device 24 and the second access point 22, and the like. The second radio wave intensity is the radio wave intensity when the command data CD4 is received, and is measured by the control unit 54 of the first processing device 24.

The communication unit 50 of the first processing device 24 transmits the response data RD2 to the second access point 22 (S125). The communication unit 44 of the second access point 22 receives the response data RD2 transmitted from the first processing device 24 (S126).

The communication unit 44 of the second access point 22 transmits the received response data RD2 to the management device 18 (S127). The communication unit 32 of the management device 18 receives the response data RD2 transmitted from the second access point 22 (S128). Thereby, the control unit 36 of the management device 18 acquires the second radio wave intensity from the received response data RD2.

The communication unit 32 of the management device 18 transmits the command data CD5 generated by the control unit 36 to the second access point 22 (S129). The command data CD5 is data for requesting the first processing device 24 to disconnect the wireless connection with the second access point 22.

The communication unit 44 of the second access point 22 receives the command data CD5 transmitted from the management device 18 (S130). The communication unit 44 of the second access point 22 transmits the received command data CD5 to the first processing device 24 (S131).

The communication unit 50 of the first processing device 24 receives the command data CD5 transmitted from the second access point 22 (S132). The control unit 54 of the first processing device 24 disconnects the wireless connection with the second access point 22 based on the received command data CD5 (S133). The wireless connection established between steps S120 to S132 is a temporary connection for the management apparatus 18 to acquire the second radio wave intensity.

The control unit 36 of the management device 18 compares the first radio wave strength and the second radio wave strength (S134), and when the first radio wave strength is smaller than the second radio wave strength, the first processing device It is determined that the 24 wireless connection destinations should be changed from the first access point 20 to the second access point 22 (YES in S135). On the other hand, when the first radio wave intensity is larger than the second radio wave intensity, the control unit 36 of the management device 18 sets the wireless connection destination of the first processing device 24 from the first access point 20 to the second access point 20. It is determined that the access point 22 should not be changed (NO in S135). In this case, although illustration is omitted, processing equivalent to each processing of step S 136 to step S 140 is executed among the management device 18, the first access point 20 and the first processing device 24. As a result, the first processing device 24 reestablishes a wireless connection with the first access point 20. In this case, the management device 18 does not update the management table.

The communication unit 32 of the management device 18 transmits the command data CD6 generated by the control unit 36 to the second access point 22 (S136). The command data CD6 is data for requesting the second access point 22 to establish a wireless connection with the first processing device 24.

The communication unit 44 of the second access point 22 receives the command data CD6 transmitted from the management device 18 (S137). The communication unit 44 of the second access point 22 transmits a polling signal to the first processing device 24 based on the received command data CD6 (S138).

The communication unit 50 of the first processing device 24 receives the polling signal transmitted from the second access point 22 (S139). The control unit 54 of the first processing device 24 establishes a wireless connection with the second access point 22 based on the received polling signal (S140).

As a modification, each process of steps S129 to S133 may be omitted. In this modification, since the wireless connection between the first processing device 24 and the second access point 22 is maintained, each process of steps S136 to S140 is performed when YES is determined in step S135. Is omitted. On the other hand, in the modification, when it is determined NO in step S135, after the respective processes of steps S129 to S133 are executed, the processes equivalent to the respective processes of steps S136 to S140 are the management device 18, the It is executed between one access point 20 and the first processing device 24.

After that, the control unit 36 of the management device 18 indicates that the first processing device 24 and the first access point 20 are wirelessly connected to the correspondence information of the management table stored in the storage unit 34. Then, the content is updated to the content indicating that the first processing device 24 and the second access point 22 are wirelessly connected (S141). In the example illustrated in FIG. 7, the control unit 36 of the management device 18 deletes “EQ1” from the correspondence information indicating the wireless connection destination of the first access point 20, and the wireless connection destination of the second access point 22. "EQ1" is added to the corresponding information indicating (see FIG. 4).

[1-4. effect]
Next, the effects obtained by the communication system 2 according to the present embodiment will be described. For example, when an obstacle 56 exists between the first access point 20 and the first processing device 24, the first radio wave strength between the first access point 20 and the first processing device 24 is It drops significantly. At this time, when the second radio wave intensity between the second access point 22 and the first processing device 24 is larger than the first radio wave intensity, the communication system 2 wirelessly transmits the first processing device 24 wirelessly. The connection destination is changed from the first access point 20 to the second access point 22. Thus, the communication system 2 can reliably perform communication between the second access point 22 and the first processing device 24.

Further, when the wireless connection between the first processing device 24 and the second access point 22 is established, the correspondence information stored in the storage unit 34 of the management device 18 is updated. The wireless connection destination of the first processing device 24 can be accurately grasped.

Second Embodiment
[2-1. Configuration of communication system]
Next, the configuration of the communication system 2A according to the second embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a conceptual diagram showing the configuration of the communication system 2A according to the second embodiment. FIG. 9 is a diagram showing an example of a management table according to the second embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 8, the communication system 2A according to the second embodiment includes a third access point 58 (hereinafter also referred to as “AP3”) in addition to the components described in the first embodiment. And four processing devices 60 (hereinafter, also referred to as “EQ 4”). Each of the third access point 58 and the fourth processing unit 60 is connected to the wireless network 30 (see FIG. 2). Although not shown, the configuration of the third access point 58 is the same as the configuration of the first access point 20, and the configuration of the fourth processing device 60 is the same as the configuration of the first processing device 24.

In the example shown in FIG. 8, the third access point 58 is wirelessly connected to the fourth processing device 60. The first processing device 24 is disposed in an area where the communicable area of the second access point 22 and the communicable area of the third access point 58 overlap.

As shown in FIG. 9, in the third line of the management table stored in the storage unit 34 (see FIG. 2) of the management device 18, data related to the third access point 58 is stored. Specifically, on the third line of the management table, a) location information "0003" indicating the location of the third access point 58, and b) correspondence information indicating the wireless connection destination of the third access point 58 "EQ4, ..." is stored. The correspondence information “EQ4,...” Is information indicating that the fourth processing device 60 or the like is wirelessly connected to the third access point 58.

In the example shown in FIG. 9, the first access point 20 is wirelessly connected to a total of 15 communication devices including the second processing device 26 and the first transport vehicle 6. The second access point 22 is wirelessly connected to a total of 41 communication devices including the first processor 24, the third processor 28, and the second carrier 8. Also, the third access point 58 is wirelessly connected to a total of 10 communication devices including the fourth processing device 60.

[2-2. Operation of communication system]
Next, the operation of the communication system 2A according to the second embodiment will be described with reference to FIGS. 10 and 11. FIG. FIG. 10 is a sequence diagram showing an operation of the communication system 2A according to the second embodiment. FIG. 11 is a diagram showing an example of the management table after update according to the second embodiment.

In the present embodiment, as described in the first embodiment, the wireless connection destination of the first processing device 24 is changed from the first access point 20 to the second access point 22, and storage of the management device 18 is performed. On the premise that the correspondence information of the management table stored in the unit 34 has been updated, the operation of the communication system 2A after that will be described. The second radio wave intensity is the radio wave intensity when the command data CD4 shown in FIG. 6B is received, and the information measured by the control unit 54 of the first processing device 24 is stored in the management device 18 It is assumed that it is stored in the unit 34.

As shown in FIG. 10, the control unit 36 (see FIG. 2) of the management device 18 updates the correspondence information of the management table stored in the storage unit 34 (S201). At this time, the control unit 36 of the management device 18 determines whether the second access point 22 is wirelessly connected to a predetermined number (for example, 40) or more of communication devices based on the correspondence information in the management table. . In the present embodiment, as shown in FIG. 9, the number of connected second access points 22 is 41, which is in a state of exceeding the predetermined number. The predetermined number is smaller than the maximum number of connections (for example, 50) that the second access point 22 can wirelessly connect.

If the control unit 36 of the management device 18 determines that the second access point 22 is wirelessly connected to a predetermined number or more of communication devices (YES in S202), the step in FIG. 6B of the first embodiment is performed. Step S203 is performed similarly to S129. That is, the command data CD7 is data for requesting the first processing device 24 to disconnect the wireless connection with the second access point 22. Thereafter, steps S204 to S207 are performed as in steps S130 to S133 of FIG. 6B. On the other hand, when the control unit 36 of the management device 18 determines that the second access point 22 is wirelessly connected to the communication devices less than the predetermined number (NO in S202), the control unit 36 executes the processing of step S203 and subsequent steps. do not do.

The control unit 36 of the management device 18 specifies the third access point 58 disposed at the position closest to the second access point 22 based on the position information of the management table stored in the storage unit 34 (S208 ).

The communication unit 32 (see FIG. 2) of the management device 18 transmits the command data CD8 generated by the control unit 36 to the third access point 58 (S209). The command data CD8 is data for requesting the third access point 58 to establish a wireless connection with the first processing device 24.

The communication unit (not shown) of the third access point 58 receives the command data CD8 transmitted from the management device 18 (S210). The communication unit of the third access point 58 transmits a polling signal to the first processing device 24 based on the received command data CD8 (S211).

The communication unit 50 (see FIG. 2) of the first processing device 24 receives the polling signal transmitted from the third access point 58 (S212). The control unit 54 (see FIG. 2) of the first processing device 24 establishes a wireless connection with the third access point 58 based on the received polling signal (S213).

The communication unit 32 of the management device 18 transmits the command data CD9 generated by the control unit 36 to the third access point 58 (S214). The command data CD9 is data for requesting the first processing device 24 to transmit the third radio field strength between the first processing device 24 and the third access point 58.

The communication unit of the third access point 58 receives the command data CD9 transmitted from the management device 18 (S215). The communication unit of the third access point 58 transmits the received command data CD9 to the first processing device 24 (S216).

The communication unit 50 of the first processing device 24 receives the command data CD9 transmitted from the third access point 58 (S217). The control unit 54 of the first processing device 24 generates response data RD3 based on the received command data CD9. The response data RD3 is data for replying the third radio wave intensity between the first processing device 24 and the third access point 58 to the third access point 58. The response data RD3 includes, for example, the third radio wave intensity (for example, -40 dbm) between the first processing device 24 and the third access point 58, and the like. The third radio wave intensity is the radio wave intensity when the command data CD 9 is received, and is measured by the control unit 54 of the first processing device 24.

The communication unit 50 of the first processing device 24 transmits response data RD3 to the third access point 58 (S218). The communication unit of the third access point 58 receives the response data RD3 transmitted from the first processing device 24 (S219).

The communication unit of the third access point 58 transmits the received response data RD3 to the management device 18 (S220). The communication unit 32 of the management device 18 receives the response data RD3 transmitted from the third access point 58 (S221). Thereby, the control unit 36 of the management device 18 acquires the third radio field strength from the received response data RD3.

The control unit 36 of the management device 18 compares the second radio wave strength with the third radio wave strength (S222), and the first processing device when the second radio wave strength is smaller than the third radio wave strength. It is determined that the 24 wireless connection destinations should be changed from the second access point 22 to the third access point 58 (YES in S223). The communication state in the case where the wireless connection destination of the first processing device 24 is the third access point 58 is the communication in the case where the wireless connection destination of the first processing device 24 is the second access point 22. It means that it is better than the state.

In this case, the control unit 36 of the management device 18 indicates that the first processing device 24 and the second access point 22 are wirelessly connected to the correspondence information of the management table stored in the storage unit 34. From the contents, the contents are updated to the contents indicating that the first processing device 24 and the third access point 58 are wirelessly connected (S224). In the example illustrated in FIG. 11, the control unit 36 of the management device 18 deletes “EQ1” from the correspondence information indicating the wireless connection destination of the second access point 22, and the wireless connection destination of the third access point 58 Add “EQ1” to the correspondence information indicating.

If the second radio wave intensity is equal to or higher than the third radio wave intensity, the control unit 36 of the management device 18 determines that the wireless connection destination of the first processing device 24 is the second access point 22 to the third access point 22. It is determined that the access point 58 should not be changed (NO in S223). In this case, although illustration is omitted, processing equivalent to each processing of step S203 to step S207 is executed among the management device 18, the third access point 58 and the first processing device 24. . Thereafter, processing equivalent to the processing in steps S209 to S213 is executed among the management device 18, the second access point 22 and the first processing device 24. As a result, the first processing unit 24 disconnects the wireless connection with the third access point 58 and establishes the wireless connection with the second access point 22 again. In this case, the control unit 36 of the management device 18 does not update the management table.

[2-3. effect]
In the present embodiment, the number of communication devices wirelessly connected to the second access point 22 can be suppressed to less than the maximum number of connections that the second access point 22 can wirelessly connect. This allows the second access point 22 to remain free to transmit a polling signal.

Although the third access point 58 is an access point different from the first access point 22 in the present embodiment, the third access point 58 may be the first access point 22. That is, although the wireless connection destination of the first processing device 24 is changed from the first access point 20 with weak radio wave intensity to the second access point 22, the second access point 22 is a communication device having a predetermined number or more. And the first processing unit 24 may be connected to the first access point 20 again.

(Modification etc.)
As mentioned above, although the control method and communication system of the communication system of this invention were demonstrated based on embodiment, this invention is not limited to the said embodiment. The present invention also includes other embodiments realized by combining the above-described embodiments with modifications that those skilled in the art can think of, and other components realized by combining the components in the above-described embodiments.

In each of the above embodiments, the case of changing the wireless connection destination of the first processing device 24 has been described. However, any one of the second processing device 26, the third processing device 28, and the fourth processing device 60 has been described. The wireless connection destination may be changed. Alternatively, the wireless connection destination of either of the first carrier 6 and the second carrier 8 may be changed.

The communication system of the present invention can be applied to, for example, a carrier system for transporting an FOUP by a carrier traveling along a rail installed on a ceiling in a semiconductor manufacturing plant or the like.

2, 2A Communication System 4 Carrier System 6 First Carrier 8 Second Carrier 10 Rail 12 Power Supply Device 14 Power Supply Path 16 Semiconductor Processing Device 18 Management Device 20 First Access Point 22 Second Access Point 24 First processing unit 26 Second processing unit 28 Third processing unit 30

Wireless network

32, 38, 44, 50

Communication unit

34, 40, 46, 52

Storage unit

36, 42, 48, 54 Control unit 56 Obstacle 58 Third Access Point 60 Fourth Processing Unit

Claims

Communication system comprising a management device, a plurality of access points connected to the management device, and one or more communication devices communicating with the management device via a wireless connection with any of the plurality of access points Control method of
The management device includes a storage unit that stores correspondence information indicating that any one of the plurality of access points and the one or more communication devices are wirelessly connected.
The control method is
(A) The management device is between a specific communication device of the one or more communication devices and a first access point wirelessly connected to the specific communication device of the plurality of access points. Acquiring a first radio wave intensity from the first access point;
(B) the second radio wave intensity between the specific communication device and a second access point different from the first access point among the plurality of access points; Obtaining from the access point of
(C) The management apparatus changes the wireless connection destination of the specific communication apparatus from the first access point to the second access point based on the first radio wave strength and the second radio wave strength. Determining whether or not to
(D) when the management apparatus determines that the wireless connection destination of the specific communication apparatus should be changed from the first access point to the second access point, the specific communication apparatus and the first communication apparatus may Disconnecting the wireless connection with the second access point, and establishing a wireless connection between the particular communication device and the second access point;
(E) when the wireless connection between the specific communication device and the second access point is established, the management device uses the correspondence information stored in the storage unit as the specific communication device. Updating from the content indicating that the first access point is wirelessly connected to the content indicating that the specific communication device and the second access point are wirelessly connected Control method of communication system.
In the above (c), when the first radio wave strength is smaller than the second radio wave strength, the management apparatus determines the wireless connection destination of the specific communication apparatus from the first access point to the second access point. The control method of the communication system according to claim 1, wherein it is determined that the access point should be changed to the access point.
In the (b), when the first radio wave intensity is less than a predetermined threshold, the management apparatus acquires the second radio wave intensity from the second access point. Control method of communication system.
The storage unit further stores position information indicating the position of each of the plurality of access points,
The control method further includes: (f) the second access point in which the management apparatus is disposed at a position closest to the first access point among the plurality of access points based on the position information Including the step of identifying
The method according to any one of claims 1 to 3, wherein in (b), when the management apparatus specifies the second access point, the management apparatus acquires the second radio wave intensity from the second access point. The control method of the communication system as described.
The control method further includes
(G) determining whether the management apparatus wirelessly connects a predetermined number or more of the communication apparatuses to the second access point;
(H) When the management device determines that the predetermined number or more of communication devices are wirelessly connected to the second access point, the communication device may be located between the specific communication device and the second access point. Disconnecting a wireless connection and establishing a wireless connection between a third access point different from the particular communication device and the second access point of the plurality of access points;
(I) when the wireless connection between the specific communication device and the third access point is established, the management device determines the correspondence information stored in the storage unit as the specific communication device Updating from the content indicating that the second access point is wirelessly connected to the content indicating that the specific communication device and the third access point are wirelessly connected The control method of the communication system according to any one of claims 1 to 4, comprising:
The control method of the communication system according to claim 5, wherein the predetermined number is smaller than a maximum number of connections that the second access point can wirelessly connect.
A communication system,
A management device,
A plurality of access points connected to the management device;
One or more communication devices communicating with the management device via a wireless connection with any of the plurality of access points;
The management device is
A storage unit that stores correspondence information indicating that any one of the plurality of access points and the one or more communication devices are wirelessly connected;
The first radio wave intensity between a specific communication device of the one or more communication devices and a first access point wirelessly connected to the specific communication device of the plurality of access points is A first acquisition unit acquired from one access point,
A second radio wave intensity between the specific communication device and a second access point different from the first access point of the plurality of access points is acquired from the second access point And the acquisition department of
Based on the first radio wave intensity and the second radio wave intensity, it is determined whether the wireless connection destination of the specific communication device should be changed from the first access point to the second access point. A judgment unit,
When it is determined that the wireless connection destination of the specific communication device should be changed from the first access point to the second access point, the specific communication device and the first access point may be switched. A switching unit that disconnects a wireless connection and establishes a wireless connection between the specific communication device and the second access point;
When the wireless connection between the specific communication device and the second access point is established, the correspondence information stored in the storage unit corresponds to the specific communication device and the first access point. The communication system further includes an updating unit that updates the content indicating that the wireless communication is connected to the content indicating that the specific communication device and the second access point are wirelessly connected.