Control device, access point device, control method, and program

Abstract

To improve communication quality at a station in a wireless LAN network including multiple access points.SOLUTION: A control device obtains information on transmission power in communication with a connected station at a first access point, and controls the first access point and the second access point to change the connection destination of the station from the first access point to the second access point on the basis of the transmission power being greater than a first predetermined value.SELECTED DRAWING: Figure 3

Description

Technical Field

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[0001] The present invention relates to a connection control technology for a wireless LAN.

Background Art

[0002] In the Wi-Fi (registered trademark) Alliance, the Wi-Fi EasyMesh standard for a multi-AP network composed of a plurality (one or more) of access points (APs) has been established. In the Wi-Fi EasyMesh standard, various controls in a multi-AP network are defined, and a control message when a station (STA) connected to the multi-AP network changes the connected wireless network is defined. In a multi-AP network, a STA connected to any AP can provide a seamless communication service to the STA by switching the connected AP. Patent Document 1 describes a technique for switching the connection destination of a STA connected to one AP to another AP in response to a decrease in communication quality below a predetermined value in a multi-AP network. Further, Patent Document 2 describes a technique for switching the connection destination of a STA to an AP that provides a better communication environment when there is an AP that provides a better communication environment than the AP to which the STA is connected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technologies described in Patent Documents 1 and 2, the condition for switching the connection destination is that the wireless environment between the STA and the AP it is connected to is lower than when connecting to surrounding APs. Therefore, it is anticipated that during the period when switching the connection destination occurs, the communication environment at the STA will be insufficient, making it impossible to provide wireless communication services of sufficient quality to that STA.

[0005] This invention provides a technology for improving communication quality at stations in a wireless LAN network that includes multiple access points. [Means for solving the problem]

[0006] A control device according to one aspect of the present invention is A first access point different from the control device, It performs communication compliant with the IEEE 802.11 standard. The aforementioned An acquisition means for acquiring information on the transmission power in communication with a station currently connected at a first access point, and a means for determining when the transmission power is greater than a first predetermined value. or not Based on this, the connection destination of the station is changed from the first access point. A determination means for determining whether or not to make a change, and based on the determination that the connection destination of the station should be changed from the first access point, the determination means for changing the connection destination of the station from the first access point The system includes control means that executes control processing to control the first access point and the second access point so that they are changed to a second access point that performs communication compliant with the IEEE 802.11 standard. [Effects of the Invention]

[0007] According to the present invention, communication quality at stations in a wireless LAN network including multiple access points can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing an example configuration of a wireless communication system. [Figure 2] This is a diagram showing an example of a communication device configuration. [Figure 3]This figure shows an example of the processing flow performed by a controller in a multi-AP network. [Figure 4] This figure shows an example of a format used by agents in a multi-AP network to notify transmitted power information. [Figure 5] This diagram shows an example of the processing flow that takes place between the AP and STA before the connection destination is changed. [Figure 6] This figure shows an example of AP transmission power for multiple STAs. [Figure 7] This diagram shows an example of the processing flow that will be executed between the AP and STA of the new connection destination. [Modes for carrying out the invention]

[0009] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] (System Configuration) Figure 1 shows an example configuration of a wireless communication system according to this embodiment. This wireless communication system is composed of communication devices that can perform communication compliant with the Wi-Fi EasyMesh standard, including access points (AP101, AP102, and AP105) and stations (STA103 and STA104). Here, AP101, AP102, and AP105 are assumed to be forming a multi-access point network (multi-AP network 110) compliant with the Wi-Fi EasyMesh standard. STA103 and STA104 are assumed to be connected to the multi-AP network 110. AP101 is connected to a wide-area network (WAN106) and can, for example, relay communication between AP102, AP105, STA103, and STA104, thereby establishing a connection between these communication devices and the WAN106.

[0011] In this embodiment, we will describe the case where a wireless communication system based on the Wi-Fi EasyMesh standard is used, but the invention is not intended to be limited to the Wi-Fi EasyMesh standard. For example, the following discussion can be applied to a wireless communication system using the IEEE 802.11s standard, which is part of the IEEE 802.11 series of standards and relates to wireless LAN mesh networks.

[0012] AP101 operates as a controller (controller) that has the function of controlling the entire multi-AP network 110 by controlling other APs. Other APs controlled by controllers such as AP101 operate as agents that have the function of reporting network information to the controller under the controller's management. The controller controls the connection channel and transmission power of agents by sending predetermined control messages, for example. The controller can also control the Basic Service Set (BSS) to which an agent is connected, and the BSS to which the STA is connected, etc. The controller also performs other controls such as controlling data traffic and diagnosing the network. Agents report network information to the controller, such as the agent's own capability information and the capability information of the STA and other APs connected to them. Other APs can connect to agents using the STA function of a multi-AP device called a backhaul STA. A multi-AP device refers to a device that functions as a controller or agent of a multi-AP network. Furthermore, capability information may include, for example, HT (High Throughput) Capability and VHT (Very High Throughput) Capability as defined in the IEEE 802.11 standard. Network information may also include wireless LAN connection channel information, information on radio interference, notifications of STA connection and disconnection, information notifying topology changes, and Beacon frame metrics information.

[0013] Furthermore, an AP acting as a controller may also have agent functionality, and may operate as an agent in parallel with its role as a controller. In one example, AP101, AP102, and AP105 may all have both controller and agent functionality. The Wi-Fi EasyMesh standard specifies that there is one controller in a multi-AP network, and multiple agents are permitted. Therefore, in this embodiment, among AP101, AP102, and AP105, AP101 will operate as the controller, and AP102 and AP105 will operate as agents. Also, STA104 will establish a wireless connection with AP102, then gradually move away from AP102 and approach AP105. As STA104 moves, it will be controlled to change its connection destination from AP102 to AP105. On the other hand, STA103 will not move, and its connection destination will not be changed. In the following, the AP to which a connection is made may be referred to as the network to which the connection is made, or the BSS to which the connection is made. For example, changing the connection destination may be referred to as a BSS migration.

[0014] Furthermore, the connection between the controller AP101 and the agents AP102 or AP105 may be established via a wired connection instead of wirelessly. For example, AP101 may connect to the STA using wireless communication functionality while simultaneously connecting to AP102 or AP105 using wired communication functionality. Also, in one example, AP101 may be a wireless LAN access point, or a controller that does not have wireless LAN access point functionality, as long as it has the functionality of a controller that controls other APs.

[0015] Note that, in one example, AP101, AP102, and AP105 can be a wireless LAN router, a personal computer (PC), a tablet terminal, a smartphone, a TV, a printer, a copier, a projector, etc. However, these are only examples, and AP101, AP102, and AP105 can be any electronic device as long as it has the function as a communication device capable of executing the functions described later.

[0016] (Device Configuration) FIG. 2 shows an example of the hardware configuration of AP101 according to the present embodiment. Note that AP102 and AP105 may also have the same configuration. AP101 has, for example, a storage unit 201, a control unit 202, a functional unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207.

[0017] The storage unit 201 is configured to include one or more memories such as a Read Only Memory (ROM) and a Random Access Memory (RAM). The storage unit 201 stores a program for causing AP101 to perform various operations described later, and information such as communication parameters for wireless communication. Note that, as the storage unit 201, one or more storage media such as a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, a DVD, etc. may be used instead of or in addition to the above-described memory.

[0018] The control unit 202 can be configured to include one or more processors such as a Central Processing Unit (CPU) and a Micro Processing Unit (MPU). The control unit 202 controls the entire AP101 by, for example, executing the program stored in the storage unit 201. The control unit 202 can execute various controls in cooperation with the program stored in the storage unit 201 and an Operating System (OS). Also, the control unit 202 may have a plurality of processors such as a multi-core.

[0019] Furthermore, the control unit 202 executes at least one function from the programs that function as the multi-AP controller unit 208 and the multi-AP agent unit 209, which are stored in the storage unit 201, and which is determined by the settings and operation of AP101. When AP101 functions as both a controller and an agent, both functions of the multi-AP controller unit 208 and the multi-AP agent unit 209 are enabled. When AP101 functions as a controller but not as an agent, the functions of the multi-AP controller unit 208 are enabled and the functions of the multi-AP agent unit 209 are disabled (not enabled). Also, when AP101 functions as an agent but not as a controller, the functions of the multi-AP controller unit 208 are disabled (not enabled) and the functions of the multi-AP agent unit 209 are enabled. Note that AP101 does not need to have the multi-AP controller unit 208 if it never operates as a controller. Similarly, AP101 does not need to have the multi-AP agent unit 209 if it never operates as an agent.

[0020] The multi-AP controller unit 208 controls the multi-AP network 110 by outputting instructions to the agent based on the network topology information and discovery information received by AP 101 from the agent. The multi-AP agent unit 209 transmits the network topology information and discovery information to other communication devices that function as controllers, and performs communication control based on instructions from those communication devices. Network topology information is transmitted and received, for example, by 1905 Topology Notification messages and 1905 Topology Response messages based on the Wi-Fi EasyMesh specification. Discovery information is transmitted and received, for example, by 1905 AP-Autoconfiguration Search messages and 1905 AP-Autoconfiguration Response messages. These are messages based on the Wi-Fi EasyMesh standard. Based on this information, the controller sends a Client Association Control Request message, which is defined as a multi-AP control message in the Wi-Fi EasyMesh standard. This allows the controller to prohibit the STA from connecting to a first predetermined BSS in the multi-AP network and to explicitly connect the STA to a second predetermined BSS. Conventionally, the STA would identify an appropriate AP from among multiple APs based on received signal strength, communication quality, etc., and perform roaming (switching the connected AP) by switching the BSS. However, the criteria for deciding whether or not to roam depended on the STA's hardware and software. In contrast, in this embodiment, the controller controls the STA's roaming, so the AP to which the STA is connected can be changed in a way that does not depend on the STA's roaming function.

[0021] The functional unit 203 performs predetermined processes such as printing and projection under the control of the control unit 202. The functional unit 203 is, for example, hardware for AP101 to perform predetermined processes. For example, if AP101 is a printer, the functional unit 203 is the printing unit and performs printing. If AP101 is a projector, the functional unit 203 is the projection device and performs projection. If AP101 is a scanner, the functional unit 203 is the reading device and performs reading. The data processed by the functional unit 203 may be data stored in the storage unit 201, or data communicated with other communication devices via the communication unit 206, which will be described later.

[0022] The input unit 204 includes hardware that accepts various operations from the user via a pointing device such as a mouse, voice input, button operation, etc. The output unit 205 includes hardware that provides various outputs to the user. The output from the output unit 205 includes one or more outputs that can present information to the user, such as visual outputs such as displaying images on a liquid crystal display or lighting up lamps with light-emitting diodes, audio outputs from speakers, and vibration outputs. Note that both the input unit 204 and the output unit 205 may be implemented by a single module such as a touch panel display.

[0023] The communication unit 206 controls wireless LANs compliant with the IEEE 802.11 series standard, which is a data link layer protocol, and wired communications such as wired LANs based on the IEEE 802.3 standard. Furthermore, the communication unit 206 controls IP communications, which is a network layer communication protocol. In addition, the communication unit 206 can execute protocols compliant with the IEEE 1905.1 standard on a communication path established according to the IEEE 802.11 or IEEE 802.3 standard. As a result, AP101 can control at least one of the controller and agent compliant with the Wi-Fi EasyMesh standard. Note that the IEEE 1905.1 standard is a standard that defines protocols located in the layer between the data link layer and the network layer. Note that this is just one example, and this embodiment is also applicable to communication devices compliant with other wireless communication methods such as Bluetooth®, NFC, UWB, ZigBee, MBOA, and other wired communication methods. Here, NFC stands for Near Field Communication, and MBOA stands for Multi Band OFDM Alliance. UWB stands for Ultra Wideband, and includes wireless USB, wireless 1394, WiNET, etc. The communication unit 206 controls the antenna 207 to transmit and receive wireless signals for wireless communication.

[0024] (Process flow) Next, we will explain the processing flow performed in the wireless communication system. First, using Figure 3, we will explain an example of the processing flow performed by the controller of a multi-AP network. For example, when AP101 operates as the controller of the multi-AP network 110, the processing in Figure 3 is performed. Note that AP102 and AP105 can also perform the processing in Figure 3 when operating as controllers of the multi-AP network. Each processing step in Figure 3 is realized, for example, by the control unit 202 reading and executing a program stored in the memory unit 201. Furthermore, at least a part of the processing in Figure 3 may be realized by hardware. For example, a dedicated circuit automatically generated on an FPGA using a predetermined compiler from a program corresponding to at least some of the processing steps may be used as hardware corresponding to some of the processing steps. FPGA stands for Field Programmable Gate Array. Alternatively, hardware that realizes at least some of the processing steps may be configured by forming a Gate Array circuit in the same way as an FPGA. Furthermore, at least some of the processing steps may be realized by an application-specific integrated circuit (ASIC).

[0025] In this process, AP101 first configures a multi-AP network in response to user instructions via the multi-AP controller unit 208 (S301). AP101 can configure a multi-AP network using, for example, Wi-Fi Protected Setup (WPS) or Device Provisioning Protocol (DPP) in accordance with the Wi-Fi EasyMesh standard. WPS and DPP are standards for configuring wireless LANs developed by the Wi-Fi Alliance, enabling wireless LAN configuration and encryption without forcing users to perform complex configuration operations. AP101 may also configure a multi-AP network using methods other than these methods and protocols.

[0026] Furthermore, APs that make up a multi-AP network activate predetermined functions in accordance with the Wi-Fi EasyMesh standard in order to operate as a controller or agent. For example, an AP functioning as an agent activates the STA function of a multi-AP device called a backhaul STA to join the multi-AP network and starts the process of joining the multi-AP network. An AP functioning as an agent also activates the AP function of a multi-AP device called a fronthaul AP and waits for connections from surrounding STAs or backhaul STAs activated by other APs. On the other hand, an AP functioning as a controller activates only the fronthaul AP function and does not activate the backhaul STA function.

[0027] Next, AP101 obtains information on the transmit power (Tx Power) from the multi-AP agent via the multi-AP controller unit 208 (S302). The transmit power is the transmit power within a predetermined frequency bandwidth (for example, a channel or a resource unit, which is the smallest unit of resources obtained by dividing an existing channel width into smaller subchannels), and is the power of the signal supplied by the communication unit 206 to the antenna 207. The processing from S302 onward is performed for each STA connected to the multi-AP network 110.

[0028] AP101 may obtain transmit power information by, for example, sending a request message to the agent requesting information, or it may receive transmit power information reported by the agent without sending such a request message. AP101 can also obtain transmit power information at any time, for example, periodically at predetermined intervals, or as needed based on the STA joining a multi-AP network. In the Wi-Fi EasyMesh standard, when an STA joins or leaves a BSS of a multi-AP network, its agent sends a 1905 Topology Notification message to the controller. This notifies the controller of the change in network topology. Based on this message, the controller can detect that an STA has joined or left a multi-AP network and can request transmit power information from the agent accordingly.

[0029] Furthermore, when the controller requests transmit power information from the agent, it can use, for example, a control message in the format specified in the IEEE 1905.1 standard described above. Control messages used in multi-AP systems are defined in the Wi-Fi EasyMesh standard as being transmitted using the 1905 Control Message Data Unit (CMDU) format. The 1905 CMDU header includes a Message Type field to identify the type of message. To indicate that it is a multi-AP control message, a specific value in the reserved area that is not assigned to a particular message type at the time of this application may be assigned to this field. Similarly, for requests and responses to transmit power information, an unassigned (reserved) value at the time of this application may be assigned as the value stored in the Message Type field of the 1905 CMDU header. Similarly, when an agent reports transmit power information to the controller, it can also use a control message in the format specified in the IEEE 1905.1 standard. In this case, the TLV (type-length-value) format, as described later with reference to Figure 4, may be included in the control message.

[0030] Next, AP101, in the multi-AP controller unit 208, determines whether the value of the transmission power indicated by the transmission power information obtained from the agent exceeds a first predetermined value (S303). This determination is made in S306, described later, in order to identify the STA that will be targeted for migration of the connected BSS. AP102 and AP105 set the transmission power so that the received power of the radio waves at the connected STA is within a certain range. Therefore, the transmission power will be lower the smaller the transmission loss and the better the communication environment, and the transmission power will be higher the larger the transmission loss. For this reason, it can be evaluated that it may not be possible to provide communication services with sufficient communication quality to an STA whose transmission power is higher than the first predetermined value and which has a large transmission loss. For this reason, for each STA, it can be determined whether or not the connected AP (BSS) should be migrated based on whether or not the transmission power exceeds the first predetermined value. AP101 may also determine whether the latest transmission power exceeds the first predetermined value, or whether the acquired transmission power, including the latest transmission power, has exceeded the first predetermined value for a predetermined number of consecutive times. Furthermore, AP101 may determine whether the transmitted power has exceeded a first predetermined value over a predetermined period. Also, AP101 may determine whether statistical values ​​such as the average or median of the transmitted power over a predetermined period or a predetermined number of times have exceeded a first predetermined value.

[0031] If the transmission power to the STA does not exceed a first predetermined value (NO in S303), the communication environment at that STA is sufficiently good, and even if the communication quality deteriorates, it can be improved by increasing the transmission power. Therefore, AP101 terminates processing for that STA without changing the destination BSS. On the other hand, if the transmission power to the STA exceeds a first predetermined value (YES in S303), it is assumed that there is a large transmission loss between that STA and the connected AP. Therefore, it is determined that the STA is in a state where the BSS should be changed. Note that the first predetermined value may be set to a value lower than the maximum value of the transmission power. In other words, even if a deterioration in communication quality has not yet occurred at the STA, the transmission power to that STA may exceed the first predetermined value. This makes it possible to change the destination BS of the STA before a deterioration in communication quality actually occurs, and to continue providing high-quality communication service to that STA.

[0032] If the transmission power to the STA exceeds a first predetermined value (YES in S303), AP101 obtains communication quality information about the surrounding APs for that STA (S304). AP101 may obtain communication quality information about the surrounding APs of the connected STA by, for example, sending a message to an agent requesting communication quality information about the surrounding APs of the connected STA. AP101 may obtain communication quality information by, for example, using the Associated STA Link Metrics Query / Response message specified in the Wi-Fi EasyMesh standard. The Associated STA Link Metrics Query / Response message is a message used to query / respond to the link metrics of a connected STA. AP101 may also obtain communication quality information by using the Unassociated STA Link Metrics Query / Response message. The Unassociated STA Link Metrics Query / Response message is a message used to query / respond to the link metrics of an unconnected STA. Each message also includes information such as the MAC address of the STA, the signal strength on the receiving channel of the uplink (the link from the STA to the AP) for each STA, and the communication speed of the link.

[0033] In the multi-AP controller unit 208, AP101 determines, based on the communication quality information acquired in S304, whether there are APs in the vicinity with communication quality higher than a second predetermined value for an STA whose BSS to be connected to should be changed (S305). Here, communication quality refers to at least one of the received signal strength, signal-to-noise ratio (SNR), or carrier-to-noise ratio (CNR) at the STA. The second predetermined value can be a value such as received signal strength, SNR, or CNR that is generally considered to indicate good communication quality. If AP101 determines that there are no APs in the vicinity of the STA with communication quality higher than the second predetermined value (NO in S305), it terminates processing without changing the BSS to which the STA is connected, because there are no APs in the vicinity of that STA that can provide a good communication environment.

[0034] On the other hand, if the multi-AP controller unit 208 determines that there are APs in the vicinity of the STA whose communication quality is higher than the second predetermined value (YES in S305), AP101 decides to change the BSS to which the STA is connected. In this case, AP101 sends an instruction to the agent to change the connection destination of the STA (S306). AP101 may also obtain information from the agent that extracts APs in the vicinity of the STA connected to the agent whose communication quality with the STA is higher than the second predetermined value. That is, the agent may collect information on the communication quality between the connected STA and the APs in the vicinity of the STA, identify the APs whose communication quality is higher than the second predetermined value, and notify AP101. In this case, the processing in S305 may be omitted. If there are multiple APs whose communication quality is higher than the second predetermined value, AP101 may, for example, determine the AP with the best communication quality as the AP to which the connection will be changed. However, this is not limited to the above. For example, an AP to change the connection to may be selected randomly from among APs whose communication quality is higher than a second predetermined value, based on the MAC address value of each AP, based on the location of each AP, or based on the number of STAs currently connected to each AP. Alternatively, the AP to change the connection to may be determined by other criteria. When sending this instruction, a control message such as the Client Steering Request message specified in the Wi-Fi EasyMesh standard may be used. This message may include the MAC address of the STA whose BSS to connect to should be changed, as well as information about the BSS before and after the change. Here, the BSS information to which the STA is currently connected is set as the BSS information before the change, and the BSS information provided by the AP whose communication quality is higher than the second predetermined value in S305 is set as the BSS information after the change. This message may also include a reason code indicating the reason for requesting the BSS change. This reason code may be set to a value indicating signal quality or a value indicating transmit power, and may be used for purposes such as notifying the user of the reason for the BSS change or saving the BSS change history as log information.

[0035] Through the process described above, AP101, which operates as the controller of the multi-AP network 110, can change the BSS of the STA's connection destination when the transmission power to the STA exceeds a first predetermined value. In this process, the BSS of the connection destination is changed in response to the transmission power to the STA exceeding the first predetermined value, without waiting for the actual communication quality obtained at the STA to deteriorate. Therefore, it is possible to provide the STA with a communication service that maintains good communication quality on a continuous basis.

[0036] Here, Figure 4 shows an example of the message format (Transmit Power Level TLV format) used by agents in a multi-AP network to report transmitted power information in this embodiment. The Transmit Power Level TLV format consists of three fields: tlvType, tlvLength, and tlvValue. In the example in Figure 4, the length of the tlvType field is 1 octet and the length of the tlvLength field is 2 octets, but the format is not limited to these fields and field lengths.

[0037] The tlvType field in a message is set to a predetermined value indicating that the message is a Transmit Power Level TLV. The value of the tlvType field is a format-specific value defined to identify the type of multi-AP TLV format. In this embodiment, the tlvType field is set to one of the values ​​not defined in the Wi-Fi EasyMesh standard at the time of this application. The tlvLength field in a message stores a value indicating the size of the message, particularly the size of the fields following it (e.g., the number of octets). The message size varies depending on the number of STAs connected to the agent in the multi-AP network. The tlvValue field in a message includes the number of connected STAs (1 octet), the MAC address of each STA (6 octets each), and the transmit power level for each STA (1 octet each). The MAC address of the STA and the transmit power level for each STA are repeated for each connected STA.

[0038] Furthermore, if the configuration allows for notification of the transmission power level to the STA, the values ​​of each field in the Transmit Power Level TLV format are not limited to the values ​​mentioned above, and any values ​​can be set. Also, the notification method is not limited to notification methods using various control messages specified in the IEEE 1905.1 standard, and any notification method may be used.

[0039] Next, using Figure 5, we will explain an example of the process that takes place between AP102 and STA104 when AP102 is an AP acting as an agent in a multi-AP network that provides the BSS from which STA104's connection is modified.

[0040] First, AP102 configures a multi-AP network as a multi-AP agent in the multi-AP agent unit 209 (S501). The method for configuring the multi-AP network is as described in relation to S301 in Figure 3 above, so the explanation is omitted here. Then, AP102 waits for connections from STAs (e.g., STA103 and STA104) using the fronthaul AP function in the multi-AP agent unit 209 (S502). STA104 also searches for surrounding APs and establishes a connection to the BSS provided by AP102 that it found (S508). For example, AP102 and STA104 establish a connection using, for example, a Management frame from the IEEE 802.11 series standard. The Management frame includes, for example, frames such as Beacon, Probe Request / Response, Authentication Request / Response, and Association Request / Response.

[0041] After establishing a connection, AP102 transmits a signal while controlling the transmission power so that the received signal strength at the connected STA104 remains approximately constant (S503). Then, STA104 receives the signal transmitted from AP102 (S509). Normally, for example, if AP102 outputs radio waves at a constant power, the received signal strength at an STA located farther away from AP102 will be lower than that at an STA located closer to AP102. Therefore, AP102 increases the transmission power for STAs located farther away from itself and controls the transmission power so that the received signal strength at each STA reaches the target value. The target value for the received signal strength may be the same for each of the multiple STAs, or it may be different depending on the communication category at each STA. Furthermore, in this transmission power control, the power level is controlled within the range of the maximum allowable power stipulated by the radio wave laws of each country.

[0042] Here, using Figure 6, an example of the transmission power of AP102 to STA103 and STA104 will be explained. Here, AP102 can communicate simultaneously with STA103 and STA104 using the orthogonal frequency division multiple access (OFDMA) function adopted in the IEEE 802.11ax standard, for example. The IEEE 802.11ax standard specifies a power boost function that sets the transmission power for each resource unit and transmits signals. AP102 can use this power boost function to simultaneously transmit downlink signals to STA103 and STA104 with different transmission powers. Here, as explained in relation to Figure 1, STA103 does not move in position, and the distance to AP102 is sufficiently close and constant. Therefore, when the transmission power of AP102 is constant, the received power of STA103 is also constant. Accordingly, AP102 controls the transmission power to STA103 to maintain it without changing it so that the received power of STA103 remains approximately constant. Meanwhile, STA104 moves away from AP102, and the distance between AP102 and STA104 gradually increases. Therefore, AP102 increases the transmission power to STA104 in response to this movement of STA104, controlling it so that the received power at STA104 remains approximately constant. In this embodiment, an example of simultaneously transmitting signals to multiple STAs using OFDMA has been described, but it is not limited to this. For example, AP may communicate with one STA at a time, for example, by communicating with one STA within one time slot using time division multiplexing, and may control the transmission power so that the received signal strength on the STA side does not fall below a predetermined threshold.

[0043] Returning to Figure 5, AP102 reports the transmission power information set in the communication of S503 to the controller (S504) in the multi-AP agent unit 209. AP102 may, for example, notify the controller of the transmission power information in response to a request from the controller. AP102 may also notify the controller of the transmission power information periodically at predetermined intervals, regardless of a request from the controller. Furthermore, AP102 may notify the controller of the transmission power information at other times, such as when the transmission power to the STA is changed or when the STA joins the multi-AP network 110. Note that when the STA joins the multi-AP network 110, it can be said that the STA changes from a state where it is not connected to the multi-AP network 110 to a state where it is connected to AP102.

[0044] On the other hand, STAs connected to AP102 (e.g., STA103, STA104) perform, for example, a measurement of the radio wave environment, identify APs other than AP102 in the vicinity, and notify AP102 of the results of this identification (S510). STAs connected to AP102 notify AP102 of the surrounding AP information using, for example, a method specified in the Wi-Fi Agile Multiband specification. AP102 then acquires the surrounding AP information notified by the connected STA in the multi-AP agent unit 209 (S505). In Wi-Fi Agile Multiband, roaming control is performed based on the IEEE802.11k, IEEE802.11v, IEEE802.11u, and IEEE802.11r standards. For example, the IEEE802.11k standard supports the exchange of information about the Wi-Fi environment between APs and STAs, and specifies a mechanism for transmitting information about surrounding APs and the reception levels of signals for each channel on the STA to the AP. Therefore, AP102 can use this mechanism to obtain information about other APs located in the vicinity of the connected STA.

[0045] AP102, in its multi-AP agent unit 209, notifies the controller (AP101) of the surrounding AP information collected from the STA (S506). For example, AP102 may notify the controller of the surrounding AP information using messages defined in the Wi-Fi EasyMesh standard. Note that this notification of information was explained in relation to S304 above, so it will not be repeated here.

[0046] Finally, AP102 disconnects from STA104 in the multi-AP agent unit 209 based on instructions from the controller (AP101) (S507). These instructions from the controller may be given using messages defined in the Wi-Fi EasyMesh standard. Details of these instructions from the controller were described above in relation to S306, so they are omitted here. AP102 also sends a disconnection notification such as DEAUTH or DISASSOCIATION to STA104, and STA104 disconnects from the BSS provided by AP102 based on this disconnection notification (S511).

[0047] Next, using Figure 7, we will explain an example of the process that takes place between AP105 and STA104 when AP105 is an AP that acts as an agent in a multi-AP network providing the BSS to which STA104's connection is changed.

[0048] First, AP105 configures a multi-AP network as a multi-AP agent in the multi-AP agent unit 209 (S701). The method for configuring the multi-AP network is as explained in relation to S301 in Figure 3 above, so the explanation is omitted here. Next, AP105 establishes a connection with STA104 in the multi-AP agent unit 209 based on instructions from the controller (AP101) (S702). The instructions from the controller are as explained in relation to S306 in Figure 3 above, so the explanation is omitted here. In addition, AP105 can use the method specified in the IEEE802.11r standard when connecting with STA104. The IEEE802.11r standard specifies a roaming method that allows an STA to seamlessly switch from a connection with an AP within the Wi-Fi network to a connection with another AP. The IEEE802.11r standard enables high-speed authentication of the STA using a function called FT (Fast Basic Service Set Transition) when the STA is roaming. In this way, STA104 establishes a connection to the BSS provided by AP105 (S703).

[0049] As described above, AP102, acting as an agent of the multi-AP network 110, identifies the transmission power for each connected STA. Then, under the control of the controller, AP102 causes STA104 whose transmission power exceeds a first predetermined value to disconnect from the BSS provided by its device. Another AP105, also acting as an agent of the multi-AP network 110, can, under the control of the controller, establish a connection with STA104 as a new connection destination for STA104 based on the communication environment between AP105 and STA104. In this way, according to this embodiment, the AP to which the STA is connected can be smoothly switched without depending on the roaming function capabilities of the STA, and before the communication quality of the STA deteriorates. This makes it possible to continue providing high-quality communication, such as high-speed, real-time video communication, to a moving STA.

[0050] In the example described above, the process of changing the AP (BSS) to which the STA is connected was explained based on the transmission power of the downlink signal from the AP to the STA, when that transmission power exceeds a first predetermined value. However, this is not limited to this, and for example, the decision to change the AP (BSS) to which the STA is connected may be made based on the transmission power of the uplink signal from the STA to the AP, when that transmission power exceeds a third predetermined value. In this case, the STA may notify the connected AP of its transmission power, and that AP may notify the controller of the value of that transmission power. Furthermore, when measuring communication quality to detect APs around the STA, the AP may measure the received strength of the radio waves transmitted from each STA, and based on the measurement results, the APs present around each STA may be identified. In addition, by measuring the transmission quality of a signal transmitted at a constant power, the magnitude of the transmission path loss can be estimated, and APs that can provide sufficient communication quality to the STA can be identified. Alternatively, instead of the STA's transmission power, the magnitude of the transmission path loss may be estimated, and the decision to change the AP to which the STA is connected may be made when the transmission path loss exceeds a predetermined value. In this case, the predetermined value of the transmission path loss can be set to a level that allows sufficient communication quality to be obtained when the AP or STA transmits a signal at a transmission power lower than the maximum transmission power. That is, the predetermined value of the transmission path loss can be set to a level that provides a certain margin above the reference communication quality when the signal is transmitted at the maximum transmission power. With this, the STA can determine an AP to which it can change its connection destination that can obtain sufficient communication quality while maintaining the reference communication quality through transmission power control, and change the STA's connection destination to that AP.

[0051] Furthermore, for example, the area of ​​each AP's BSS may differ. In one example, a first BSS that covers a wide area and can ensure a certain communication speed may be provided, and a second BSS that covers a narrow area and can provide high-speed communication may be provided. In this case, the controller may, based on the transmission power of an STA connected to the second BSS exceeding a predetermined value, change the connection destination to the first BSS, regardless of information about surrounding APs. In one example, if the BSS area is wide, there may be many STAs in that area, and if all of those STAs connect to that BSS, a sufficient communication speed may not be obtained. For this reason, while other BSSs with smaller areas are available, STAs may be connected to other BSSs, and then, in response to the transmission power of those other BSSs exceeding a predetermined value, the connection destination may be changed to a BSS covering a wider area. In other words, if it is known in advance that there are APs around the STA that can ensure a certain level of communication quality (communication quality at the currently connected BSS), the process of identifying surrounding APs may be omitted. Furthermore, the relationship between the first BSS and the second BSS is not limited to the above. In other words, the coverage areas of the first BSS and the second BSS may be similar, or the first BSS may cover a narrower area. For example, the AP providing the first BSS may be a communication device such as a smartphone owned by the STA user, which has the communication function of a cellular communication system. In this case, the second BSS may be used as long as it is available, and the system may switch to using the second BSS when the communication quality of the second BSS becomes insufficient (when the transmission power exceeds the first predetermined value). In this way, even if the surrounding APs of the STA are not specified by communication quality, it is possible to keep the STA connected to an AP that can provide sufficient communication quality.

[0052] (Summary of the embodiments) At least some of the embodiments described above can be summarized as follows:

[0053] (Item 1) An acquisition means for acquiring information on the transmitted power in communication with a connected station at the first access point, Control means for controlling the first access point and the second access point to change the connection destination of the station from the first access point to the second access point based on the transmission power being greater than a first predetermined value, A control device characterized by having the following features.

[0054] (Item 2) The system further includes a determination means for determining the second access point from among the other access points based on the communication quality between the station and other access points different from the first access point. The control device according to item 1, characterized in that it is a control device.

[0055] (Item 3) The acquisition means further acquires information on the communication quality between the station and the other access point. The determination means determines the other access point whose communication quality is higher than the second predetermined value as the second access point. The control device according to item 2, characterized in that

[0056] (Item 4) The acquisition means further acquires information of other access points whose communication quality with the station is higher than a second predetermined value, The determination means determines the second access point from among the other access points whose communication quality is higher than the second predetermined value. The control device according to item 2, characterized in that

[0057] (Item 5) The control device according to any one of items 2 to 4, characterized in that the communication quality is at least one of the received radio wave intensity, signal-to-noise ratio, and carrier-to-noise ratio at the station.

[0058] (Item 6) The control device according to any one of items 1 to 5, characterized in that the acquisition means sends a message to the first access point requesting information on the transmission power, and acquires the information on the transmission power included in the response to the message.

[0059] (Item 7) The control device according to any one of items 1 to 6, characterized in that the acquisition means acquires information on the transmitted power transmitted from the first access point at a predetermined interval.

[0060] (Item 8) The control device according to any one of items 1 to 7, characterized in that the acquisition means acquires information on the transmission power notified by the first access point in response to a change in the transmission power.

[0061] (Item 9) The control device according to any one of items 1 to 8, characterized in that the acquisition means acquires information on the transmission power notified by the first access point in response to the station joining the network controlled by the control device by connecting the station to the first access point.

[0062] (Item 10) The control means controls the first access point and the second access point so as to change the station's connection destination from the first access point to the second access point when the latest transmission power is greater than the first predetermined value. A control device according to any one of items 1 to 9, characterized in that it is a control device.

[0063] (Item 11) The control means controls the first access point and the second access point so as to change the connection destination of the station from the first access point to the second access point when the transmission power is greater than the first predetermined value for a predetermined number of consecutive times or over a predetermined period of time. A control device according to any one of items 1 to 9, characterized in that it is a control device.

[0064] (Item 12) The control device according to any one of items 1 to 11, characterized in that the first predetermined value is a value lower than the maximum value of the transmitted power.

[0065] (Item 13) The control device according to any one of items 1 to 12, characterized in that the transmitted power is transmitted power in a predetermined frequency bandwidth.

[0066] (Item 14) The control device according to any one of items 1 to 13, characterized in that the control device is a controller for a multi-access point network compliant with the Wi-Fi EasyMesh standard, and the first access point and the second access point are agents of the multi-access point network.

[0067] (Item 15) The control device according to item 14, characterized in that the control device is an access point included in the multi-access point network.

[0068] (Item 16) A notification means for notifying the control device of information on the transmission power during communication with the connected station, A disconnection means for disconnecting the connection to the station based on an instruction transmitted from the control device based on the transmission power being greater than a predetermined value, An access point characterized by having the following features.

[0069] (Item 17) The access point according to item 16, further characterized in that the notification means notifies the control device of information regarding the communication quality between the station and other access points different from the access point.

[0070] (Item 18) The access point according to item 17, characterized in that the communication quality is at least one of the received radio wave intensity, signal-to-noise ratio, and carrier-to-noise ratio at the station.

[0071] (Item 19) The access point according to any one of items 16 to 18, characterized in that when the notification means receives a message from the control device requesting information on the transmission power, it includes the information on the transmission power in its response to the message and sends it to the control device.

[0072] (Item 20) The access point according to any one of items 16 to 19, characterized in that the notification means notifies the control device of the transmission power at a predetermined interval.

[0073] (Item 21) The access point according to any one of items 16 to 20, characterized in that the notification means notifies the control device of the transmission power when the transmission power is changed.

[0074] (Item 22) The access point according to any one of items 16 to 21, characterized in that the notification means notifies the control device of the transmission power when the station joins the network controlled by the control device by connecting the station to the access point.

[0075] (Item 23) The access point according to any one of items 16 to 22, characterized in that the transmitted power is transmitted power in a predetermined frequency bandwidth.

[0076] (Item 24) A control method performed by a control device, To obtain information on the transmitted power during communication with the connected station at the first access point, Based on the transmission power being greater than a first predetermined value, the first access point and the second access point are controlled to change the connection destination of the station from the first access point to the second access point. A control method characterized by including

[0077] (Item 25) A control method performed by an access point, To notify the control unit of the transmission power information during communication with the connected station, Based on an instruction transmitted from the control device that the transmitted power is greater than a first predetermined value, the connection to the station is disconnected. A control method characterized by including

[0078] (Item 26) A program to cause a computer to function as a control device as described in any one of items 1 through 15.

[0079] (Item 27) A program that causes a computer to function as an access point as described in any one of items 16 through 23.

[0080] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0081] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0082] 101: Multi-AP network controller, 102, 105: Multi-AP network agents, 201: Memory unit, 202: Control unit, 208: Multi-AP controller unit, 209: Multi-AP agent unit

Claims

1. A control device, A first access point, different from the control device, which performs communication in accordance with the IEEE 802.11 standard, and an acquisition means for acquiring information on the transmitted power in communication with a station currently connected to the first access point, A determination means for determining whether to change the connection destination of the station from the first access point based on whether the transmission power is greater than a first predetermined value, A control means that performs control processing to control the first access point and the second access point so as to change the connection destination of the station from the first access point to a second access point that performs communication compliant with the IEEE 802.11 standard, based on the determination that the connection destination of the station is to be changed from the first access point, A control device characterized by having the following features.

2. The system further includes a selection means for selecting the second access point to be connected to the station from among the other access points, based on the communication quality between the station and another access point that communicates in accordance with the IEEE 802.11 standard, which is different from the first access point. The control device according to feature 1.

3. The acquisition means further acquires information on the communication quality between the station and the other access point. The selection means selects from among the other access points an access point whose communication quality is higher than a second predetermined value as the second access point to which the station will connect. The control device according to claim 2.

4. The acquisition means further acquires information of other access points whose communication quality with the station is higher than a second predetermined value, The selection means selects the second access point to be connected to the station from among the other access points whose communication quality is higher than the second predetermined value. The control device according to claim 2.

5. The control device according to claim 2, characterized in that the communication quality is at least one of the received radio wave intensity, signal-to-noise ratio, and carrier-to-noise ratio at the station.

6. The control device according to claim 1, wherein the control device sends a message to the first access point requesting information on the transmission power, and the acquisition means acquires the information by receiving a response from the first access point which is a response to the message and includes information on the transmission power.

7. The control device according to claim 1, characterized in that the information of the transmission power at the first access point is notified from the first access point at a predetermined interval, and the acquisition means acquires the information of the transmission power at the first access point by receiving the notification at the predetermined interval.

8. The control means controls the first access point and the second access point so as to change the station's connection destination from the first access point to the second access point when the latest transmission power is greater than the first predetermined value. The control device according to feature 1.

9. The control means controls the first access point and the second access point so as to change the connection destination of the station from the first access point to the second access point when the transmission power is greater than the first predetermined value for a predetermined number of consecutive times or over a predetermined period of time. The control device according to feature 1.

10. The control device according to claim 1, wherein the control device is a controller for a multi-access point network compliant with the Wi-Fi EasyMesh® standard, and the first access point and the second access point are agents of the multi-access point network.

11. The control device according to claim 10, characterized in that the control device also functions as an access point included in the multi-access point network.

12. An access point device that performs communication in accordance with the IEEE 802.11 standard, A notification means for notifying the control device of information on the transmission power during communication with the connected station, Receiving means for receiving instructions from the control device, A disconnection means for disconnecting the connection to the station when it receives an instruction to change the connection destination of the station based on the transmission power information transmitted from the control device, An access point device characterized by having the following features.

13. The access point device according to claim 12, further characterized in that the notification means notifies the control device of information regarding the communication quality between the station and another access point different from the access point device.

14. The access point device according to claim 13, characterized in that the communication quality is at least one of the received radio wave intensity, signal-to-noise ratio, and carrier-to-noise ratio at the station.

15. The access point device according to claim 12, characterized in that the notification means notifies the information of the transmission power by sending a response to the control device, which is a response to the message and includes the information of the transmission power, when it receives a message from the control device requesting the information of the transmission power.

16. The access point device according to claim 12, characterized in that the notification means notifies the control device of the transmission power at a predetermined interval.

17. The access point device according to claim 12, characterized in that the access point device functions as an agent for the Wi-Fi EasyMesh® standard.

18. A control method in which a control device controls the connection destination of a station, A first access point different from the control device, which performs communication in accordance with the IEEE 802.11 standard, and an acquisition step of acquiring information on the transmitted power in communication with a station currently connected to the first access point, A determination step of determining whether or not to change the connection destination of the station from the first access point based on whether or not the transmission power is greater than a first predetermined value, A control step is performed to control the first access point and the second access point so as to change the connection destination of the station from the first access point to a second access point that performs communication compliant with the IEEE 802.11 standard, based on the determination that the connection destination of the station is to be changed from the first access point. A control method characterized by including

19. A program for causing a computer to execute the control method described in claim 18.

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