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]

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

[0002] The Wi-Fi (registered trademark) Alliance has formulated the Wi-Fi EasyMesh standard for a multi-AP network consisting of multiple (one or more) access points (APs). The Wi-Fi EasyMesh standard specifies various controls in a multi-AP network, and specifies a control message when a station (STA) connected to the multi-AP network changes the wireless network to which it is connected. In a multi-AP network, a STA connected to one of the APs can provide a seamless communication service to the STA by switching the AP to which it is connected. Patent Document 1 describes a technology for switching the connection destination of a STA to another AP in a multi-AP network when the communication quality of a STA connected to one AP drops below a predetermined value. Patent Document 2 describes a technology for switching the connection destination of a STA to an AP that provides a better communication environment than the AP to which the STA is connected, when there is an AP that provides a better communication environment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-145704 A [Patent Document 2] JP 2016-225939 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the techniques described in Patent Documents 1 and 2, the condition for switching the connection destination is that the wireless environment between the STA and the currently connected AP is worse than that when connecting to a surrounding AP. Therefore, it is expected that the communication environment of the STA will be insufficient during the period when the connection destination is switched, and wireless communication services of sufficient quality will not be provided to the STA.

[0005] The present invention provides a technique for improving communication quality at a station in a wireless LAN network including multiple access points. [Means for solving the problem]

[0006] A control device according to one embodiment of the present invention has an acquisition means for acquiring information on transmission power in communication with a station currently connected to a first access point, and a control means for controlling 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 based on the transmission power being greater than a first predetermined value. Effect of the Invention

[0007] According to the present invention, it is possible to improve communication quality in a station in a wireless LAN network including a plurality of access points. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 1 illustrates an example of the configuration of a communication device. [Diagram 3] FIG. 11 is a diagram illustrating an example of a process flow executed by a controller of a multi-AP network. [Figure 4] 11 is a diagram illustrating an example of a format used by an agent in a multi-AP network to notify transmission power information. [Diagram 5]11 is a diagram illustrating an example of the flow of processing executed between an AP and a STA before a connection destination is changed. [Figure 6] FIG. 13 is a diagram illustrating an example of the transmission power of an AP for multiple STAs. [Figure 7] 13 is a diagram illustrating an example of the flow of processing executed between an AP and a STA as a connection destination after a change. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] (System Configuration) 1 shows an example of the configuration of a wireless communication system according to this embodiment. This wireless communication system includes access points (AP101, AP102, and AP105) and stations (STA103 and STA104), which are communication devices capable of performing communication conforming to the Wi-Fi EasyMesh standard. Here, it is assumed that AP101, AP102, and AP105 form a multi-access point network (multi-AP network 110) conforming to the Wi-Fi EasyMesh standard. It is assumed that STA103 and STA104 are connected to the multi-AP network 110. Note that AP101 is connected to a wide area network (WAN106), and can, for example, relay communication between AP102, AP105, STA103, and STA104, and establish connections between these communication devices and the WAN106.

[0011] In this embodiment, a wireless communication system based on the Wi-Fi EasyMesh standard is described, but the invention is not limited to the Wi-Fi EasyMesh standard. For example, the following discussion is applicable to a wireless communication system using the IEEE802.11s standard related to wireless LAN mesh networks, which is one of the IEEE802.11 series standards.

[0012] The AP 101 operates in the role of a controller (control device) having a function of controlling other APs to control the entire multi-AP network 110. Other APs controlled by the controller such as the AP 101 operate in the role of an agent having a function of reporting network information to the controller under the management of the controller. The controller controls the connection channel and transmission power of the agent, for example, by transmitting a predetermined control message. The controller can also perform control such as changing the Basic Service Set (BSS) to which the agent is connected and changing the BSS to which the STA is connected. The controller also performs further other control such as data traffic control and network diagnosis. The agent reports to the controller, for example, its own capability information and capability information of the STA connected to it and other APs, as network information. The other APs can connect to the agent using the STA function of a multi-AP device called a backhaul STA. The multi-AP device refers to a device that functions as a controller or agent of a multi-AP network. The capability information may include, for example, HT (High Throughput) Capability and VHT (Very High Throughput) Capability defined in the IEEE 802.11 standard, etc. The network information may further include information on a connection channel of a wireless LAN, information on radio interference, notification of connection or disconnection of an STA, information notifying a change in topology, metric information of a Beacon frame, etc.

[0013] An AP that operates as a controller may have a function as an agent, or may operate as an agent in parallel with operating as a controller. In one example, AP101, AP102, and AP105 may have both a controller function and an agent function. In the Wi-Fi EasyMesh standard, one controller is specified in one multi-AP network, and multiple agents are allowed to exist. For this reason, among AP101, AP102, and AP105, in this embodiment, AP101 operates as a controller, and AP102 and AP105 operate as agents. In addition, after establishing a wireless connection with AP102, STA104 moves gradually away from AP102 and approaches AP105. Then, STA104 is controlled to change its connection destination from AP102 to AP105 as it moves. On the other hand, STA103 does not move, and does not change its connection destination. In the following description, the destination AP may be referred to as the destination network or destination BSS. For example, a change in destination may be referred to as a BSS transition.

[0014] Note that the connection between AP101, which is the controller, and AP102 or AP105, which is the agent, may be established by wire instead of wirelessly. For example, AP101 may connect to AP102 or AP105 by using a wired communication function while connecting to a STA by using a wireless communication function. In one example, AP101 may be a wireless LAN access point as long as it has a controller function for controlling other APs, or may be a controller without a wireless LAN access point function.

[0015] In addition, the AP101, AP102, and AP105 may be, for example, a wireless LAN router, a personal computer (PC), a tablet terminal, a smartphone, a television, a printer, a copier, a projector, etc. However, these are merely examples, and the AP101, AP102, and AP105 may be any electronic device as long as they have the function of a communication device capable of executing the functions described below.

[0016] (Device configuration) 2 shows an example of the hardware configuration of the AP 101 according to this embodiment. The AP 102 and the AP 105 may also have a similar configuration. The AP 101 includes, for example, a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207.

[0017] The storage unit 201 includes one or more memories such as a Read Only Memory (ROM) and a Random Access Memory (RAM). The storage unit 201 stores information such as programs for causing the AP 101 to perform various operations described below and communication parameters for wireless communication. Note that, instead of or in addition to the above-mentioned memories, the storage unit 201 may use 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.

[0018] The control unit 202 may be configured to include one or more processors, such as a Central Processing Unit (CPU) or a Micro Processing Unit (MPU). The control unit 202 controls the entire AP 101, for example, by executing a program stored in the storage unit 201. The control unit 202 may execute various controls in cooperation with the program stored in the storage unit 201 and an Operating System (OS). The control unit 202 may also have multiple processors, such as a multi-core processor.

[0019] Furthermore, the control unit 202 executes at least one function determined by the setting or operation of the AP 101 among the programs functioning as the multi-AP controller unit 208 and the multi-AP agent unit 209 stored in the storage unit 201. When the AP 101 functions as a controller and an agent at the same time, the functions of both the multi-AP controller unit 208 and the multi-AP agent unit 209 are enabled. When the AP 101 functions as a controller but does not function as an agent, the function of the multi-AP controller unit 208 is enabled, and the function of the multi-AP agent unit 209 is disabled (not enabled). When the AP 101 functions as an agent but does not function as a controller, the function of the multi-AP controller unit 208 is disabled (not enabled), and the function of the multi-AP agent unit 209 is enabled. Note that the AP 101 may not have the multi-AP controller unit 208 if it does not operate as a controller. Similarly, the AP 101 may not have the multi-AP agent unit 209 if it does not operate as an agent.

[0020] The multi-AP controller unit 208 outputs instructions to the agent based on the network topology information and discovery information received by the AP 101 from the agent, and controls the multi-AP network 110. The multi-AP agent unit 209 transmits the network topology information and discovery information to another communication device functioning as a controller, and executes communication control based on instructions from the communication device. The network topology information is transmitted and received, for example, by a 1905 Topology Notification message and a 1905 Topology Response message based on the Wi-Fi EasyMesh specifications. The discovery information is transmitted and received, for example, by a 1905 AP-Autoconfiguration Search message and a 1905 AP-Autoconfiguration Response message. These are messages based on the Wi-Fi EasyMesh standard. Based on these pieces of information, the controller transmits a Client Association Control Request message defined as a multi-AP control message in the Wi-Fi EasyMesh standard. The controller thereby prohibits the STA from connecting to a first predetermined BSS in the multi-AP network, and explicitly connects the STA to a second predetermined BSS. Conventionally, a STA identifies an appropriate AP from among multiple APs based on the received signal strength, communication quality, etc., and performs roaming (switching the AP to which the STA is connected) to switch the BSS. However, the criteria for determining whether or not to roam depend on the hardware and software of the STA. In contrast, in this embodiment, a controller controls the roaming of the STA, so that the AP to which the STA is connected can be changed in a manner that does not depend on the roaming function of the STA.

[0021] The functional unit 203 executes a predetermined process such as printing or projection under the control of the control unit 202. The functional unit 203 is, for example, hardware for the AP 101 to execute a predetermined process. For example, if the AP 101 is a printer, the functional unit 203 is a printing unit and executes a printing process. Also, if the AP 101 is a projector, the functional unit 203 is a projection device and executes a projection process. Also, if the AP 101 is a scanner, the functional unit 203 is a reading device and executes a reading process. The data processed by the functional unit 203 may be data stored in the storage unit 201, or may be data communicated with another communication device via the communication unit 206 described later.

[0022] The input unit 204 includes hardware that receives 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 performs various outputs to the user. The output by the output unit 205 includes one or more outputs capable of presenting information to the user, such as visual output such as displaying an image on a liquid crystal display or lighting a lamp using a light-emitting diode, audio output from a speaker, vibration output, etc. Note that both the input unit 204 and the output unit 205 may be realized by a single module such as a touch panel display.

[0023] The communication unit 206 controls wireless LANs conforming to the IEEE802.11 series standards, which are data link layer protocols, and wired communication such as wired LANs conforming to the IEEE802.3 standards. The communication unit 206 further controls IP communication, which is a network layer communication protocol. The communication unit 206 can execute a protocol conforming to the IEEE1905.1 standard on a communication path established according to the IEEE802.11 standard or the IEEE802.3 standard. This allows the AP 101 to control at least one of a controller and an agent conforming to the Wi-Fi EasyMesh standard. The IEEE1905.1 standard is a standard that specifies a protocol located in a layer between the data link layer and the network layer. This is merely an example, and the present embodiment can also be applied to communication devices conforming to other wireless communication methods such as Bluetooth (registered trademark), NFC, UWB, ZigBee, MBOA, and other wired communication methods. Here, NFC is an abbreviation for Near Field Communication, MBOA is an abbreviation for Multi Band OFDM Alliance, and UWB is an abbreviation for Ultra WideBand, which 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] (Processing flow) Next, a flow of processing executed in the wireless communication system will be described. First, an example of a flow of processing executed by a controller of a multi-AP network will be described with reference to FIG. 3. For example, when the AP 101 operates as a controller of the multi-AP network 110, the processing of FIG. 3 is executed. Note that the AP 102 and the AP 105 may also execute the processing of FIG. 3 when they operate as controllers of the multi-AP network. Each processing step of FIG. 3 is realized, for example, by the control unit 202 reading and executing a program stored in the storage unit 201. Also, at least a part of the processing of FIG. 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 a part of the processing steps may be used as hardware corresponding to a part of the processing steps. Note that FPGA is an abbreviation for Field Programmable Gate Array. Also, hardware that realizes at least a part of the processing steps may be configured by forming a gate array circuit in the same manner as the FPGA. Also, at least a part of the processing steps may be realized by an application specific integrated circuit (ASIC).

[0025] In this process, first, the AP 101 configures a multi-AP network by the multi-AP controller unit 208 in response to an instruction from a user (S301). The AP 101 can configure the multi-AP network by 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 setting up a wireless LAN established by the Wi-Fi Alliance, and are standards that enable wireless LAN settings and encryption without forcing the user to perform complicated setting operations. Note that the AP 101 may configure the multi-AP network by a method other than these methods and protocols.

[0026] Moreover, the APs constituting the multi-AP network start up a predetermined function according to the Wi-Fi EasyMesh standard in order to operate as a controller or an agent. For example, an AP functioning as an agent starts up an STA function of a multi-AP device called a backhaul STA in order to join the multi-AP network, and starts a process of joining the multi-AP network. Also, an AP functioning as an agent starts up an AP function of a multi-AP device called a fronthaul AP, and waits for connections from surrounding STAs and backhaul STAs started in other APs. On the other hand, an AP functioning as a controller starts up only the fronthaul AP function without starting up the backhaul STA function.

[0027] Next, the AP 101 acquires information on transmission power (Tx Power) from the multi-AP agent by the multi-AP controller unit 208 (S302). The transmission power is the transmission power in a predetermined frequency bandwidth (e.g., a channel or a resource unit that is the smallest unit of resources obtained by dividing an existing channel width into smaller subchannels), and is the power of a signal that the communication unit 206 supplies to the antenna 207. Note that the processing from S302 onwards is executed for each STA connected to the multi-AP network 110.

[0028] For example, the AP 101 may obtain the transmission power information by transmitting a request message requesting information to the agent, or may receive the transmission power information reported from the agent without transmitting such a request message. The AP 101 may obtain the transmission power information at any timing, for example, periodically at a predetermined cycle, or may obtain the transmission power information at any time based on the STA's participation in the multi-AP network. In addition, in the Wi-Fi EasyMesh standard, when the STA joins the BSS of the multi-AP network or leaves the BSS, the agent transmits a 1905 Topology Notification message to the controller. This allows the agent to notify the controller of a change in the network topology. Based on this message, the controller can detect that the STA has joined or left the multi-AP network, and can request the agent for transmission power information accordingly.

[0029] When the controller requests the agent for transmission power information, the controller can use, for example, a control message in a format defined in the above-mentioned IEEE 1905.1 standard. The Wi-Fi EasyMesh standard defines that the control message used in multi-AP should be transmitted using the 1905 Control Message Data Unit (CMDU) format. The 1905 CMDU header includes a Message Type field for identifying the type of message. To indicate that the message is a multi-AP control message, a specific value in a reserved area that is not assigned to a specific message type at the time of this application may be assigned to this field. In addition, a value that is not assigned (reserved) at the time of this application may also be assigned as a value to be stored in the Message Type field of the 1905 CMDU header for the request and response of the transmission power information here. In addition, when the agent reports transmission power information to the controller, the controller can use a control message in a format defined in the IEEE 1905.1 standard. In this case, a type-length-value (TLV) format, which will be described later with reference to FIG. 4, may be included in the control message.

[0030] Next, the AP101 determines in the multi-AP controller unit 208 whether or not the value of the transmission power indicated by the transmission power information acquired from the agent exceeds a first predetermined value (S303). This determination is made in order to identify the STA to which the BSS to which the connection is to be transferred is to be transferred in S306 described later. The AP102 and the AP105 set the transmission power so that the reception power of radio waves in the connected STA is within a certain value range. Therefore, the smaller the transmission loss and the better the communication environment, the lower the transmission power, and the larger the transmission loss, the higher the transmission power. Therefore, it can be evaluated that there is a possibility that a communication service with sufficient communication quality cannot be provided to a STA whose transmission power is higher than the first predetermined value and whose transmission loss is large. Therefore, it is possible to determine whether or not the AP (BSS) to which the connection is to be transferred should be transferred for each STA depending on whether or not the transmission power exceeds the first predetermined value. The AP101 may determine whether or not the latest transmission power exceeds the first predetermined value, or may determine whether or not the acquired transmission power exceeds the first predetermined value a predetermined number of times in succession, including the latest transmission power. The AP 101 may also determine whether the transmission power has exceeded a first predetermined value for a predetermined period of time. The AP 101 may also determine whether a statistical value, such as an average value or a median value, of the transmission power for a predetermined period of time or a predetermined number of times has exceeded a first predetermined value.

[0031] If the transmission power for the STA does not exceed the first predetermined value (NO in S303), the communication environment in the STA is sufficiently good, and even if the communication quality is degraded, the communication quality can be improved by increasing the transmission power. Therefore, the AP 101 ends the process without shifting the BSS to which the STA is connected. On the other hand, if the transmission power for the STA exceeds the first predetermined value (YES in S303), it is assumed that the transmission loss between the STA and the AP to which the STA is connected is large. Therefore, the STA is determined to be in a state in which 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. That is, even if the communication quality of the STA has not yet degraded, the transmission power for the STA may exceed the first predetermined value. This makes it possible to change the BS to which the STA is connected before the communication quality actually degrades, and to continuously provide the STA with high-quality communication services.

[0032] When the transmission power for the STA exceeds the first predetermined value (YES in S303), the AP 101 acquires communication quality information on the neighboring APs for the STA (S304). The AP 101 may acquire communication quality information on the neighboring APs of the STA, for example, by transmitting a message to the agent requesting communication quality information on the neighboring APs of the connected STA. The AP 101 may acquire communication quality information, for example, by using an Associated STA Link Metrics Query / Response message defined in the Wi-Fi EasyMesh standard. The Associated STA Link Metrics Query / Response message is a message used for querying / responding to link metrics of the connected STA. The AP 101 may also acquire communication quality information by using an Unassociated STA Link Metrics Query / Response message. The Unassociated STA Link Metrics Query / Response message is a message used for querying / responding to link metrics of an unconnected STA. Each message also includes the MAC address of the STA, the signal strength in the receiving channel of the uplink (the link from the STA to the AP) for each STA, and information regarding the communication speed of the link.

[0033] The AP101, in the multi-AP controller unit 208, determines whether or not there is an AP with a communication quality higher than a second predetermined value in the vicinity of the STA that should change the BSS of the connection destination from the communication quality information acquired in S304 (S305). The communication quality here is, for example, at least one of the received radio wave strength, the signal-to-noise ratio (SNR), and the carrier-to-noise ratio (CNR) at the STA. In addition, the second predetermined value can be a value such as the received radio wave strength, the SNR, or the CNR that is generally considered to have good communication quality. If the AP101 determines that there is no AP with a communication quality higher than the second predetermined value in the vicinity of the STA (NO in S305), there is no AP that can provide a good communication environment in the vicinity of the STA, and therefore the process ends without changing the BSS of the connection destination of the STA.

[0034] On the other hand, when the multi-AP controller unit 208 determines that an AP with a communication quality higher than the second predetermined value exists in the vicinity of the STA (YES in S305), the AP 101 decides to change the BSS to which the STA is connected. In this case, the AP 101 transmits an instruction to the agent to change the connection destination of the STA (S306). The AP 101 may obtain information from the agent that extracts APs with a communication quality higher than the second predetermined value from among APs in the vicinity of the STA connected to the agent. That is, the agent may collect information on the communication quality between the currently connected STA and APs in the vicinity of the STA, identify APs with a communication quality higher than the second predetermined value, and notify the AP 101. In this case, the process of S305 may be omitted. When there are multiple APs with a communication quality higher than the second predetermined value, the AP 101 may determine, for example, the AP with the best communication quality as the AP to which the connection is changed. However, this is not limited to the above, and for example, the AP to which the connection is changed may be selected randomly from among APs whose communication quality is higher than the second predetermined value, based on the value of the MAC address of each AP, based on the location of each AP, and based on the number of STAs connected to each AP. The AP to which the connection is changed may also be determined based on other criteria. Note that, as a control message for transmitting this instruction, for example, a Client Steering Request message defined in the Wi-Fi EasyMesh standard may be used. This message may include the MAC address of the STA whose BSS to which the connection destination should be changed, and information on the BSS before and after the change. Here, information on the BSS to which the STA is currently connected is set as the information on the BSS before the change, and information on the BSS provided by the AP whose communication quality is higher than the second predetermined value in S305 is set as the information on the BSS after the change. Also, this message may include a reason code indicating the reason for requesting the change of the BSS. For example, a value indicating the signal quality or a value indicating the transmission power is set as this reason code, and it may be used for purposes such as notifying the user of the reason for the BSS change and storing the history of the BSS change as log information.

[0035] By the above-mentioned process, the AP 101 acting as the controller of the multi-AP network 110 can change the BSS to which the STA is connected when the transmission power to the STA exceeds the first predetermined value. In this process, the BSS to which the STA is connected is changed when the transmission power to the STA exceeds the first predetermined value, without waiting for the communication quality actually obtained by the STA to deteriorate. Therefore, it is possible to provide the STA with a communication service with good communication quality continuously.

[0036] Here, Fig. 4 shows an example of a message format (Transmit Power Level TLV format) used when an agent of a multi-AP network reports transmission power information in this embodiment. The Transmit Power Level TLV format is composed of three fields: tlvType, tlvLength, and tlvValue. In the example of Fig. 4, an example is shown in which 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 the 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 value unique to each format defined to identify the type of the multi-AP TLV format. In this embodiment, the tlvType field is set to any value that is not defined in the Wi-Fi EasyMesh standard at the time of this application. The tlvLength field in the message stores a value indicating the size of the message, particularly the size of the field following this field (e.g., the number of octets). The size of the message varies depending on the number of STAs connected to the agent of the multi-AP network. The tlvValue field in the 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 fields of the MAC address of the STA and the transmit power level for the STA are set repeatedly for the number of connected STAs.

[0038] In addition, as long as the configuration allows the transmission power level to be notified to the STA, the values ​​of each field of the Transmit Power Level TLV format are not limited to the above values, and any value may be set. In addition, the notification method is not limited to the notification method using various control messages specified in the IEEE1905.1 standard, and any notification method may be used.

[0039] Next, with reference to FIG. 5, an example of processing executed between the AP 102 and the STA 104 when the AP 102 is an AP that operates as an agent of a multi-AP network that provides the source BSS to which the STA 104 has changed its connection will be described.

[0040] First, the AP 102 configures a multi-AP network as a multi-AP agent in the multi-AP agent unit 209 (S501). The method of configuring the multi-AP network is as described above with respect to S301 in FIG. 3, and therefore the description will be omitted here. Then, the AP 102 waits for a connection from an STA (e.g., STA 103 and STA 104) using the fronthaul AP function in the multi-AP agent unit 209 (S502). Also, the STA 104 searches for surrounding APs and establishes a connection to the BSS provided by the AP 102 found in the search (S508). For example, the AP 102 and the STA 104 establish a connection using, for example, a Management frame of the IEEE 802.11 series standard. The Management frame includes, for example, a Beacon, a Probe Request / Response, an Authentication Request / Response, an Association Request / Response, and the like.

[0041] After the connection is established, the AP 102 transmits a signal while controlling the transmission power so that the received radio wave strength at the connected STA 104 is approximately constant (S503). Then, the STA 104 receives the signal transmitted from the AP 102 (S509). Normally, for example, when radio waves are output from the AP 102 at a constant power, the received radio wave strength at a STA located far from the AP 102 is smaller than the received radio wave strength at a STA located close to the AP 102. For this reason, the AP 102 increases the transmission power for the STA located far from itself, and controls the transmission power so that the received radio wave strength at each STA becomes a target value. Note that the target value of the received radio wave strength may be the same value for each of the multiple STAs, or may be a different value depending on the communication category of each STA. In addition, in the transmission power control here, the power level is controlled within the range of the maximum allowable power defined by the Radio Law of each country.

[0042] Here, an example of the transmission power for the STA103 and STA104 in the AP102 will be described with reference to FIG. 6. Here, the AP102 is assumed to be able to communicate with the STA103 and STA104 simultaneously by, for example, an orthogonal frequency division multiple access (OFDMA) function adopted in the IEEE802.11ax standard. The IEEE802.11ax standard specifies a power boost function that sets a transmission power for each resource unit and transmits a signal. The AP102 can transmit downlink signals to the STA103 and STA104 simultaneously with different transmission powers by using this power boost function. Here, as described in relation to FIG. 1, the position of the STA103 does not move, and the distance between the STA103 and the AP102 is sufficiently close and constant. Therefore, when the transmission power in the AP102 is constant, the reception power of the STA103 is also constant. Therefore, the AP102 performs control to keep the transmission power for the STA103 unchanged so that the reception power in the STA103 is approximately constant. On the other hand, the STA 104 moves away from the AP 102, and the distance between the AP 102 and the STA 104 gradually increases. Therefore, the AP 102 increases the transmission power to the STA 104 as the STA 104 moves, and controls the reception power at the STA 104 to be approximately constant. Note that, in this embodiment, an example of transmitting signals to multiple STAs simultaneously using OFDMA has been described, but this is not limited to this. For example, the AP may communicate with the STA one-to-one, for example, by communicating with one STA in one time slot by time division, and may control the transmission power so that the reception radio wave intensity at the STA does not fall below a predetermined threshold.

[0043] Returning to FIG. 5, the AP 102 reports the information of the transmission power set in the communication of S503 to the controller in the multi-AP agent unit 209 (S504). For example, when the AP 102 receives a request from the controller, the AP 102 may notify the controller of the transmission power information in response to the request. The AP 102 may also notify the controller of the transmission power information periodically at a predetermined period, regardless of the request from the controller. The AP 102 may also notify the controller of the transmission power information for the STA at other timings, such as when the AP 102 changes the transmission power for the STA 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 not connected to the multi-AP network 110 to a state connected to the AP 102.

[0044] On the other hand, the STAs (e.g., STAs 103 and 104) connected to the AP 102 perform, for example, measurement of the radio wave environment, identify APs other than the AP 102, and notify the AP 102 of the identification result (S510). The STAs connected to the AP 102 notify the AP 102 of surrounding AP information, for example, by using a method defined in the Wi-Fi Agile Multiband specifications. The AP 102 then acquires the surrounding AP information notified from the connected STA in the multi-AP agent unit 209 (S505). Note that in the 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 information exchange between the AP and the STA regarding the Wi-Fi environment, and specifies a mechanism for transmitting information on APs in the vicinity of the STA and the reception level of signals of each channel in the STA to the AP. Therefore, using this mechanism, the AP 102 can obtain, from a connected STA, information about other APs existing in the vicinity of that STA.

[0045] The AP 102 notifies the controller (AP 101) of the surrounding AP information collected from the STA in the multi-AP agent unit 209 (S506). For example, the AP 102 may notify the controller of the surrounding AP information by using a message defined in the Wi-Fi EasyMesh standard. Note that this information notification has been described in relation to S304 above, and therefore will not be described again here.

[0046] Finally, the AP 102 disconnects the connection with the STA 104 in the multi-AP agent unit 209 based on an instruction from the controller (AP 101) (S507). The instruction from the controller can be performed using a message defined in the Wi-Fi EasyMesh standard. Details of the instruction from the controller have been described above in relation to S306, and will not be described here. The AP 102 also transmits a disconnection notification such as DEAUTH or DISASSOCIATION to the STA 104, and the STA 104 disconnects the connection to the BSS provided by the AP 102 based on the disconnection notification (S511).

[0047] Next, an example of processing executed between the AP 105 and the STA 104 when the AP 105 is an AP that operates as an agent of a multi-AP network that provides a BSS to which the STA 104 should change its connection will be described with reference to FIG.

[0048] First, the AP 105 configures a multi-AP network as a multi-AP agent in the multi-AP agent unit 209 (S701). The method of configuring the multi-AP network is as described above with respect to S301 in FIG. 3, and therefore the description will be omitted here. Next, the AP 105 establishes a connection with the STA 104 based on an instruction from the controller (AP 101) in the multi-AP agent unit 209 (S702). The instruction from the controller is as described above with respect to S306 in FIG. 3, and therefore the description will be omitted here. In addition, the AP 105 can use a method defined in the IEEE802.11r standard when connecting with the STA 104. The IEEE802.11r standard defines a method for roaming in which a STA seamlessly switches a connection between an AP in a Wi-Fi network to a connection between another AP. In the IEEE802.11r standard, a function called FT (Fast Basic Service Set Transition) is used when the STA roams, allowing the STA to be authenticated at high speed. In this manner, the STA 104 establishes a connection to the BSS provided by the AP 105 (S703).

[0049] In this manner, the AP 102 operating as an agent of the multi-AP network 110 identifies the transmission power for each of the connected STAs. Then, under the control of the controller, the AP 102 disconnects the STA 104 whose transmission power exceeds the first predetermined value from the BSS provided by the own device. Also, under the control of the controller, another AP 105 operating as an agent of the multi-AP network 110 can establish a connection with the STA 104 as a new connection destination of the STA 104 based on the communication environment between the STA 104 and the AP 105. In this manner, according to the present embodiment, the AP of the connection destination of the STA can be smoothly switched without depending on the capability of the roaming function on the STA side and before the communication quality on the STA side deteriorates. This makes it possible to continue providing communication that requires high communication quality, such as high-speed and real-time video communication, to a moving STA.

[0050] In the above example, the process of changing the AP (BSS) to which the STA is connected based on the transmission power of a downlink signal from the AP to the STA when the transmission power exceeds a first predetermined value has been described. However, the present invention is not limited to this. For example, the process may be determined to change the AP (BSS) to which the STA is connected based on the transmission power of an uplink signal from the STA to the AP when the transmission power exceeds a third predetermined value. In this case, the STA may notify the AP to which it is connected of its transmission power, and the AP may notify the controller of the value of the transmission power. In addition, when measuring the communication quality to detect APs around the STA, the AP may measure the reception strength of radio waves sent from each STA, and based on the measurement result, the APs around each STA may be specified. In addition, the communication quality measurement is performed by measuring a signal transmitted at a constant power, so that the magnitude of the transmission path loss can be estimated, and an AP that can provide sufficient communication quality to the STA can be specified. In addition, the magnitude of the transmission path loss, rather than the transmission power of the STA, may be estimated, and when the transmission path loss becomes equal to or greater than a predetermined value, it may be determined to change the AP to which the STA is connected. In this case, the predetermined value of the transmission path loss can be set to a value that can obtain sufficient communication quality when the AP or STA transmits a signal with a transmission power lower than the maximum transmission power. In other words, a transmission path loss that can obtain a certain margin beyond the reference communication quality when a signal is transmitted with the maximum transmission power can be used as the predetermined value of the transmission path loss. According to this, while maintaining the reference communication quality in the transmission power control, an AP to which the STA can change its connection and obtain sufficient communication quality can be determined, and the STA can be changed to that AP.

[0051] For example, the size of the area of ​​the BSS provided by each AP may be different. In one example, a first BSS that covers a wide area and can ensure a certain communication speed, and a second BSS that covers a narrow area and can provide high-speed communication may be provided. In this case, the controller may change the connection destination of a STA connected to the second BSS to the first BSS without relying on information about the surrounding APs, based on the fact that the transmission power exceeds a first predetermined value. In one example, when the area of ​​the BSS is wide, the number of STAs present in the area is large, and if these STAs connect to the BSS, sufficient communication speed may not be obtained. For this reason, an operation may be performed in which the STA is connected to another BSS with a narrow area while the other BSS is available, and the connection destination is changed to a BSS with a wide area when the transmission power of the other BSS exceeds a predetermined value. In other words, if it is known in advance that an AP that can ensure a certain communication quality (communication quality in the currently connected BSS) exists around the STA, the process of identifying the surrounding AP may be omitted. The relationship between the first BSS and the second BSS is not limited to the above. That is, the coverage area of ​​the first BSS and the second BSS may be approximately the same, or the first BSS may cover a narrower area. In one example, the AP providing the first BSS may be a communication device such as a smartphone having a communication function of a cellular communication system and owned by a user of the STA. In this case, the second BSS may be used while the second BSS is available, and may be used when the communication quality of the second BSS becomes insufficient (when the transmission power exceeds a first predetermined value). In this way, even if the surrounding AP of the STA is not specified by the communication quality, it is possible to keep the STA connected to the AP that can obtain sufficient communication quality.

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

[0053] (Item 1) An acquisition means for acquiring information on transmission power in communication with a station currently connected to the first access point; a control means for controlling the first access point and the second access point so as to change a connection destination of the station from the first access point to a second access point based on the transmission power being greater than a first predetermined value; A control device comprising:

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

[0055] (Item 3) The acquiring 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 a second predetermined value as the second access point. 3. The control device according to item 2,

[0056] (Item 4) The acquiring means further acquires information on the 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 a second predetermined value. 3. The control device according to item 2,

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

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

[0059] (Item 7) 7. The control device according to claim 1, wherein the acquisition means acquires information about the transmission power transmitted from the first access point at a predetermined interval.

[0060] (Item 8) 8. The control device according to claim 1, wherein the acquisition means acquires information about 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 claims 1 to 8, characterized in that the acquisition means acquires information about the transmission power notified by the first access point in response to the station joining a network controlled by the control device by connecting 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 a connection destination of the station from the first access point to a second access point when the latest transmission power is greater than the first predetermined value. 10. The control device according to any one of claims 1 to 9,

[0063] (Item 11) the control means controls the first access point and the second access point so as to change a 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 for a predetermined period of time; 10. The control device according to any one of claims 1 to 9,

[0064] (Item 12) 12. The control device according to claim 1, wherein the first predetermined value is a value lower than a maximum value of the transmission power.

[0065] (Item 13) 13. The control device according to any one of claims 1 to 12, wherein the transmission power is a transmission power in a predetermined frequency bandwidth.

[0066] (Item 14) The control device according to any one of claims 1 to 13, characterized in that the control device is a controller of 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) 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 a control device of information on transmission power in communication with a currently connected station; a disconnection means for disconnecting the connection with the station based on an instruction transmitted from the control device on the basis that the transmission power is greater than a predetermined value; 1. An access point comprising:

[0069] (Item 17) 17. The access point according to item 16, wherein the notification means further notifies the control device of information on communication quality between the station and another access point different from the access point.

[0070] (Item 18) 18. The access point according to item 17, wherein the communication quality is at least one of a received radio wave strength, a signal-to-noise ratio, and a 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 requesting information about the transmission power from the control device, the notification means includes the information about the transmission power in a response to the message and sends it to the control device.

[0072] (Item 20) 20. The access point according to any one of items 16 to 19, wherein the notification means notifies the control device of the information on the transmission power at a predetermined cycle.

[0073] (Item 21) 21. The access point according to any one of items 16 to 20, wherein the notification means notifies the control device of information about 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 information on the transmission power when the station joins a network controlled by the control device by connecting to the access point.

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

[0076] (Item 24) A control method executed by a control device, comprising: Obtaining information on transmission power in communication with a connected station at a first access point; controlling the first access point and the second access point to change a connection destination of the station from the first access point to a second access point based on the transmission power being greater than a first predetermined value; A control method comprising:

[0077] (Item 25) A control method performed by an access point, comprising: notifying the control device of information on transmission power in communication with the currently connected station; Disconnecting the station based on an instruction sent from the control device based on the transmission power being greater than a first predetermined value; A control method comprising:

[0078] (Item 26) A program for causing a computer to function as the control device according to any one of items 1 to 15.

[0079] (Item 27) 24. A program for causing a computer to function as the access point according to any one of items 16 to 23.

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

[0081] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

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

Claims

1. Acquisition means for acquiring information on transmission power in communication with a connected station in a first access point that performs communication conforming to the IEEE 802.11 standard, control means for executing a control process for controlling 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 conforming to the IEEE 802.11 standard based on the fact that the transmission power is greater than a first predetermined value; A control device characterized by comprising:

2. selection means for selecting the second access point that becomes the connection destination of the station from among the other access points based on the communication quality between the station and another access point that performs communication conforming to the IEEE 802.11 standard different from the first access point; The control device according to claim 1, further comprising:

3. The acquisition means further acquires information on the communication quality between the station and the other access point, The selection means selects, as the second access point that becomes the connection destination of the station, an access point having a communication quality higher than a second predetermined value from among the other access points. The control device according to claim 2, characterized in that:

4. The acquisition means further acquires information on the other access point having a communication quality between the station and the other access point higher than a second predetermined value, The selection means selects the second access point that becomes the connection destination of the station from among the other access points having a communication quality higher than a second predetermined value. The control device according to claim 2, characterized in that:

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

6. The control device transmits a message requesting information on the transmission power to the first access point, and the acquisition means acquires the information by receiving, from the first access point, a response to the message and including the information on the transmission power in the response. The control device according to claim 1, characterized in that:

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

8. 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 latest transmission power is greater than the first predetermined value. The control device according to claim 1, characterized in that.

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 continuously for a predetermined number of times or over a predetermined period. The control device according to claim 1, characterized in that.

10. The control device is a controller of a multi-access point network compliant with the Wi-Fi EasyMesh (registered trademark) standard, and the first access point and the second access point are agents of the multi-access point network. The control device according to claim 1, characterized in that.

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

12. An access point device that performs communication compliant with the IEEE802.11 standard, A notification means for notifying the control device of information on the transmission power in communication with the connected station; A disconnection means for disconnecting the connection with the station based on an instruction transmitted from the control device based on the fact that the transmission power is greater than a predetermined value. An access point device, characterized by comprising.

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

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

15. When the notification means receives a message requesting information on the transmission power from the control device, the notification means is a response to the message, and notifies the information on the transmission power by transmitting a response including the information on the transmission power to the control device. The access point device according to claim 12, characterized in that.

16. The access point device according to claim 12, wherein the notification means notifies the control device of the information on the transmission power at a predetermined cycle.

17. The access point device is an access point device that functions as an agent of the Wi-Fi EasyMesh (registered trademark) standard. The access point device according to claim 12, characterized in that.

18. A control method for controlling a connection destination of a station, comprising: An acquisition step of acquiring information on transmission power in communication with a station connected to a first access point that performs communication conforming to the IEEE 802.11 standard; A control step of executing a control process for controlling 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 conforming to the IEEE 802.11 standard based on the transmission power being greater than a first predetermined value; A control method characterized by including.

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

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