Patent Description:
There is a technique for comprehensively handling networks constructed by a respective plurality of access points (APs) operating as network-constructing base stations as a single network. Such a comprehensive network of networks constructed by a plurality of APs is referred to as a multi-AP (MAP) network. A MAP network includes a control apparatus controlling the entire MAP network. Such a control apparatus is referred to as a MAP controller (or controller). APs that belong to the MAP network and are controlled by the controller are referred to as MAP agents (or agents).

The controller and an agent, and an agent and another agent, establish a communication link called backhaul link and perform backhaul communication. The controller can implement efficient network control between the plurality of agents belonging to the MAP network by using information obtained from the agents belonging to the MAP network via backhaul communication.

International Publication No.<CIT> discusses control of a network including a plurality of agents connected via backhaul communication.

Some APs operating as agents in a MAP network can have a plurality of wireless interfaces (I/Fs) and simultaneously construct wireless networks in a plurality of frequency bands. An AP that can simultaneously construct a plurality of wireless networks in a plurality of frequency bands can sometimes establish a plurality of backhaul links for backhaul communication to another AP. In such a case, the controller of the MAP network can control the establishment of the backhaul links in the MAP network since the controller is the apparatus controlling the entire MAP network. A communication apparatus according to the preamble of claim <NUM> is also known from <CIT>.

The present invention is directed to enabling a communication apparatus controlling a network including a plurality of base stations to control establishment of a plurality of links when the base stations establish the links therebetween.

The present invention in its first aspect provides a communication apparatus as specified in claims <NUM> to <NUM>.

The present invention in its second aspect provides a control method as specified in claim <NUM>.

The present invention in its third aspect provides a computer program product as specified in claim <NUM>.

Embodiments will be described in detail below with reference to the accompanying drawings. Configurations described in the following embodiments are just examples, and the present invention is not limited to the illustrated configurations.

<FIG> illustrates a configuration of a network an access point (AP) <NUM> according to an embodiment joins. The AP <NUM>, an AP <NUM>, and an AP <NUM> are APs each having a function of constructing a network (basic service set (BSS)). The AP <NUM> constructs a network <NUM>, the AP <NUM> constructs networks <NUM> and <NUM>, and the AP <NUM> constructs a network <NUM>. Stations (STAs) <NUM> and <NUM> have a function of joining a network. The STA <NUM> joins the network <NUM>, and the STA <NUM> joins the network <NUM>. The AP <NUM> is connected to a wide area network (WAN) <NUM> and can communicate with external networks such as the Internet.

In the present embodiment, the networks <NUM>, <NUM>, <NUM>, and <NUM> are wireless local area networks (WLANs) compliant with the Institute of Electrical and Electronics Engineers (IEEE) <NUM> series standards. Specifically, each network supports at least any one of the IEEE <NUM>. 11a/b/g/n/ac/ax/be standards.

Each network may support other communication standards in addition to the IEEE <NUM> series standards. Examples include Bluetooth (registered trademark), near field communication (NFC), ultra wideband (UWB), ZigBee, and Multi Band Orthogonal frequency-division multiplexing (OFDM) Alliance (MBOA). UWB includes wireless Universal Serial Bus (USB), wireless <NUM>, and WiNET. Each network may also support the Wi-Fi Direct standard formulated by Wi-Fi Alliance in addition to the IEEE <NUM> series standards. Communication standards for wired communication such as a wired LAN may also be supported.

In the present embodiment, the AP <NUM> includes a plurality of wireless interfaces and can simultaneously construct a plurality of networks (networks <NUM> and <NUM>). In such a case, the networks <NUM> and <NUM> use different frequency bands. For example, the network <NUM> uses a <NUM>-GHz band, and the network <NUM> a <NUM>-GHz band. Alternatively, the networks <NUM> and <NUM> can use less-interfering channels in the same frequency band. For example, if the network <NUM> uses channels belonging to W52 in the <NUM>-GHz band, the network <NUM> can use channels belonging to W53. In such a manner, the AP <NUM> can simultaneously maintain a plurality of networks.

In the present embodiment, the APs <NUM>, <NUM>, and <NUM> support the Wi-Fi EasyMesh standard. In such a case, a comprehensive network of the networks <NUM>, <NUM>, <NUM>, and <NUM> will be referred to as a multi-AP (MAP) network <NUM>. The MAP network <NUM> is a network including the APs <NUM>, <NUM>, and <NUM>. The AP <NUM> operates as a MAP controller (controller) playing the role of controlling the entire MAP network <NUM>. The APs <NUM> and <NUM> operate as MAP agents (agents) playing the role of operating in the MAP network <NUM> based on control instructions from the controller. The AP <NUM> may have not only a controller function but also an agent function. In such a case, control processing between the controller and agent of the AP <NUM> is performed by internal data exchange. In the present embodiment, the controller of the MAP network <NUM> will be described to have an AP function as well. However, this is not restrictive, and the controller can be without the AP function.

The AP <NUM> which is the controller and the APs <NUM> and <NUM> which are agents can communicate via the MAP network <NUM>. Specifically, the AP <NUM> which is an agent has a backhaul STA function for joining, as an STA, a network <NUM> constructed by the AP <NUM> which is the controller. The AP <NUM> which is the controller and the AP <NUM> which is an agent can communicate by the AP <NUM> joining the network <NUM> constructed by the AP <NUM> by using the backhaul STA function. A function by which the AP <NUM> serving as an AP connects to an STA is referred to as a fronthaul AP function. The AP <NUM> can communicate with the AP <NUM> via the AP <NUM> by the AP <NUM> joining, as an STA, the network <NUM> constructed by the AP <NUM>. In such a manner, the APs <NUM> and <NUM> which are agents can join the MAP network <NUM> by constructing a network as an AP while joining, as an STA, a network constructed by another AP. The network constructed by another AP for the AP <NUM> or <NUM> which is an agent to join as an STA is referred to, when seen from the AP <NUM> or <NUM>, as a backhaul BSS. In contrast, the network that the AP <NUM> or <NUM> serving as an AP invites an STA or another AP is referred to, when seen from the AP <NUM> or <NUM>, as a fronthaul BSS. In other words, the same network is referred to as a fronthaul BSS when seen from the AP constructing the network, and a backhaul BSS when seen from the AP joining the network.

A link that an AP serving as an agent establishes in joining a network constructed by another AP and which is used for communication with the latter AP is referred to as a backhaul link. From the viewpoint of the AP that establishes the backhaul link with the AP joining the network constructed by the AP establishing the backhaul link, the backhaul link is established via a fronthaul BSS. In contrast, from the viewpoint of the AP that joins the network constructed by another AP and establishes the backhaul link to the latter AP, the backhaul link is established via a backhaul BSS.

The controller and an agent may distinguish a network that ordinary STAs join from a network that the agent joins, or regard the networks as one and the same.

A link that an agent or the controller establishes to an STA is referred to as a fronthaul link.

The AP <NUM>, which is the controller, manages and controls the agents and STAs in the MAP network <NUM>. For example, the AP <NUM>, which is the controller, can control frequency channels and transmission power of the networks established by the APs <NUM> and <NUM>, which are agents, by transmitting predetermined control messages via the backhaul links. In addition or instead, the AP <NUM>, which is the controller, can make the AP <NUM> or <NUM>, which is an agent, migrate to a different network. In addition or instead, the AP <NUM> can control STA steering. For example, the AP <NUM> can perform roaming to change the connection destination of the STA <NUM> belonging to the network <NUM> constructed by the AP <NUM> belonging to the MAP network <NUM> to the network <NUM> constructed by the AP <NUM>. In addition or instead, the AP <NUM> can control AP-to-STA or AP-to-AP data traffic and diagnose each network. In addition or instead, the AP <NUM> can obtain network-related information from the APs <NUM> and <NUM> which are agents via the backhaul links.

The APs <NUM> and <NUM>, which are agents, can notify the AP <NUM>, which is the controller, of network-related information (network information) via the backhaul links. Examples of the network information notified by the APs <NUM> and <NUM> include capability information (such as HT capability and VHT capability) about the agents themselves and capability information about STAs and APs connected to the agents. Alternatively, the APs <NUM> and <NUM> may notify the controller of information about the agents' own wireless interfaces (I/Fs) as the capability information about the agents. Examples of the information about the wireless I/Fs include the Media Access Control (MAC) addresses of the wireless I/Fs included in the agents, and wireless LAN communication (WLAN) methods supported by the agents. If an agent includes a plurality of wireless I/Fs, the agent may notify the controller of information about each of the wireless I/Fs, or only information about some of the wireless I/Fs. If an agent includes not only a wireless I/F or I/Fs but a wired I/F as well, capability information about the wired I/F may be included. Examples of the capability information about a wired I/F include the MAC address of the wired I/F and information about a physical link rate of wired communication.

Control instructions from the AP <NUM>, which is the controller, are transmitted to and received by the agents (APs <NUM> and <NUM>) via the backhaul links. In the present embodiment, backhaul links are established and used for communication between the APs <NUM> and <NUM> and between the APs <NUM> and <NUM>. Specifically, the AP <NUM> can connect, as a backhaul STA, to the network <NUM> constructed by the AP <NUM> while constructing the networks <NUM> and <NUM>. In such a case, the network <NUM> seen from the AP <NUM> is called a fronthaul BSS, and the network <NUM> seen from the AP <NUM> a backhaul BSS. A backhaul link is established between the APs <NUM> and <NUM> via the network <NUM>. Similarly, the AP <NUM> can connect, as a backhaul STA, to at least either one of the networks <NUM> and <NUM> constructed by the AP <NUM> while constructing the network <NUM>. In such a case, the networks <NUM> and <NUM> seen from the AP <NUM> are called fronthaul BSSs, and the networks <NUM> and <NUM> seen from the AP <NUM> backhaul BSSs. A backhaul link is thereby established between the APs <NUM> and <NUM>. In the present embodiment, backhaul links via the respective networks <NUM> and <NUM> may be established between the APs <NUM> and <NUM>. That is, a plurality of backhaul links may be established between the APs <NUM> and <NUM>. In such a case, the networks <NUM> and <NUM> use less-interfering frequency bands. For example, either one of the networks <NUM> and <NUM> uses a <NUM>-GHz frequency band, and the other a <NUM>-GHz frequency band.

In the present embodiment, an AP is described as an example of the apparatus having the controller function. However, this is not restrictive, and communication apparatuses such as a personal computer (PC), a tablet, a smartphone, a mobile phone, and a television set may be used. The same applies to the apparatuses having the agent function. None of such apparatuses is restrictive, as long as a hardware configuration illustrated in <FIG> is satisfied.

<FIG> illustrates a hardware configuration of the AP <NUM>. The AP <NUM> includes a power supply unit <NUM>, an input unit <NUM>, an output unit <NUM>, a communication unit <NUM>, an antenna <NUM>, a storage unit <NUM>, and a control unit <NUM>.

The power supply unit <NUM> is a power supply unit that supplies power to various pieces of hardware to be described below. The power supply unit <NUM> obtains power from an alternating-current (AC) power source or a battery, for example.

The input unit <NUM> accepts various operations from a user. For example, the input unit <NUM> includes modules such as a button and a keyboard. The output unit <NUM> makes various outputs to the user. Examples of the outputs made by the output unit <NUM> include at least one of the following: a light-emitting diode (LED) indication, a screen display, an audio output from a speaker, and a vibration output. Both the input unit <NUM> and the output unit <NUM> may be implemented by one module, such as a touch panel. The input unit <NUM> and the output unit <NUM> each may be integrated with or separate from the AP <NUM>.

The communication unit <NUM> controls wireless communication compliant with the IEEE <NUM> series standards. In addition or instead, the communication unit <NUM> may control wired communication such as a wired LAN communication compliant with and defined by the IEEE <NUM>, and/or Internet Protocol (IP) communication. The communication unit <NUM> transmits and receives wireless signals via the antenna <NUM>. If the AP <NUM> can simultaneously construct a plurality of networks, the AP <NUM> may include a plurality of communication units <NUM> and antennas <NUM>.

The communication unit <NUM> includes a wireless I/F. The wireless I/F includes a radio frequency (RF) circuit and a wireless LAN chip. The communication unit <NUM> may include a plurality of wireless I/Fs. For example, the communication unit <NUM> may include a wireless I/F corresponding to a <NUM>-GHz band and a wireless I/F corresponding to a <NUM>-GHz band. In the present embodiment, the AP <NUM> includes one wireless I/F, and the APs <NUM> and <NUM> include two wireless I/Fs each.

The storage unit <NUM> includes one or more memories such as a read-only memory (ROM) and a random access memory (RAM), and stores computer programs for performing various operations to be described below and various types of information such as communication parameters for wireless communication. Aside from a ROM and a RAM, a storage medium such as a flexible disk, a hard disk, an optical disc, a magneto-optical disc, a compact disc read-only memory (CD-ROM), a compact disc recordable (CD-R), a magnetic tape, a nonvolatile memory card, and a digital versatile disc (DVD) may be used as the storage unit <NUM>. The storage unit <NUM> includes a plurality of memories and storage media.

The control unit <NUM> includes one or more processors such as a central processing unit (CPU) and a microprocessing unit (MPU), and controls the entire AP <NUM> by executing the computer programs stored in the storage unit <NUM>. The control unit <NUM> may be configured to control the entire AP <NUM> by cooperation of the computer programs and an operating system (OS) stored in the storage unit <NUM>. The control unit <NUM> generates data and signals to be transmitted during communication with other communication apparatuses. The control unit <NUM> may include a plurality of processors such as a multicore processor, and control the entire AP <NUM> by the plurality of processors.

The control unit <NUM> executes a program, which is stored in the storage unit <NUM>, for causing the control unit <NUM> to function as a MAP controller module <NUM> and a MAP agent module <NUM>. The MAP controller module <NUM> is a program for causing the AP <NUM> to operate as the controller of the MAP network <NUM>. The MAP agent module <NUM> is a program for causing the AP <NUM> to operate as an agent in the MAP network <NUM>. If the AP <NUM> plays both the roles of the controller and an agent, the functions of both the MAP controller module <NUM> and the MAP agent module <NUM> are executed. If the AP <NUM> plays only the role of the controller, i.e., does not play the role of an agent, only the function of the MAP controller module <NUM> is executed. In such a case, the function of the MAP agent module <NUM> may be deactivated. Similarly, if the AP <NUM> plays only the role of an agent, i.e., does not play the role of the controller, only the function of the MAP agent module <NUM> is executed. In such a case, the function of the MAP controller module <NUM> may be deactivated.

By executing a program stored in the storage unit <NUM>, the control unit <NUM> performs processing for setting wireless LAN (WLAN) parameters compliant with Wi-Fi Protected Setup (WPS) to establish a backhaul link. WPS is a standard formulated by Wi-Fi Alliance. The AP <NUM> can share communication parameters for establishing a backhaul link with another AP by performing parameter setting processing compliant with WPS. The communication parameters include at least any one of the following: a service set identifier (SSID), an encryption method, an encryption key, an authentication method, and an authentication key. Information about the frequency band to be used may be included in addition to the communication parameters. By executing a program stored in the storage unit <NUM>, the control unit <NUM> can also perform communication parameter setting processing compliant with Device Provisioning Protocol (DPP) of higher security in addition to or instead of WPS. DPP is a standard formulated by Wi-Fi Alliance.

The APs <NUM> and <NUM> also have a hardware configuration similar to that of the AP <NUM>. The APs <NUM> and <NUM> do not need to have the controller function. In such a case, the control unit <NUM> does not need to include the function of the MAP controller module <NUM>.

<FIG> is a sequence diagram illustrating an example of processing performed in a case where the APs <NUM> and <NUM> establish a plurality of backhaul links.

In the present embodiment, the AP <NUM> initially connects, as a backhaul STA, to the network <NUM> constructed by the AP <NUM>, establishes a backhaul link, and is registered as an agent in the AP <NUM>. A MAP network <NUM> including the APs <NUM> and <NUM> is thereby constructed. Next, to join the MAP network <NUM>, the AP <NUM> connects to the network <NUM> constructed by the AP <NUM> and establishes a backhaul link to the AP <NUM>. With the backhaul link to the AP <NUM> established, the AP <NUM> is registered as an agent in the AP <NUM> via the AP <NUM>. A second backhaul link is then established between the APs <NUM> and <NUM> via the network <NUM> by control of the AP <NUM> which is the controller. Such a sequence will be described with reference to the sequence diagram illustrated in <FIG>.

This sequence is started in a state where the AP <NUM> belongs, as a backhaul STA, to the network <NUM> constructed by the AP <NUM>. In step F301, the AP <NUM> having joined the network <NUM> multicasts an IEEE <NUM> AP-Autoconfiguration Search message as a search signal for searching for a controller.

In step F302, if the AP <NUM> receiving the search signal transmitted from the AP <NUM> is operating as a controller, the AP <NUM> transmits an AP-Autoconfiguration Response message to the AP <NUM> as a response signal.

In step F303, the AP <NUM> receiving the response signal transmits an AP-Autoconfiguration WSC message to the AP <NUM> as a registration request signal for registering the AP <NUM> in the AP <NUM> which is the controller. This message includes a message corresponding to an M1 message compliant with the Wi-Fi Simple Configuration (WSC) standard. Specifically, the message includes information such as the MAC address and device name of the AP <NUM>. In addition, the registration request signal includes capability information about wireless communication of the AP <NUM>. Specifically, information about a usable frequency band or bands of the AP <NUM> (at least either one of <NUM>- and <NUM>-GHz bands) and information about usable frequency channels are included as the capability information about wireless communication. In addition to or instead of such information, an identifier for uniquely identifying the network <NUM> the AP <NUM> belongs to in the MAP network <NUM> may be included.

The registration request signal may be extended to include information about the wireless I/F that can operate as a backhaul STA in the AP <NUM>. A specific example of the information about the wireless I/F is the MAC address of the wireless I/F. The registration request signal may also be extended to include information about a BSS other APs can join among fronthaul BSSs that can be constructed by the AP <NUM>. A specific example of the information about the BSS is a basic service set identifier (BSSID) of the BSS. Information indicating whether the BSS other APs can join is already constructed may be included as the information about the BSS. The registration request signal may be further extended to include capability information about whether the AP <NUM> can simultaneously establish a plurality of backhaul links.

In step F304, the AP <NUM> receiving the registration request signal transmits an AP-Autoconfiguration WSC message to the AP <NUM> as a registration response signal. If the AP <NUM> succeeds in registering the AP <NUM> as an agent, a message corresponding to a WSC M2 message is included in the registration response signal. In such a case, the registration response signal includes the device name of the AP <NUM> and information indicating the absence of an error. The registration response signal also includes an identifier for uniquely identifying the network <NUM> in the MAP network <NUM>. The identifier included in the registration response signal may be the same as that included in the registration request signal. If any error occurs and the AP <NUM> fails to register the AP <NUM>, a registration response signal indicating the occurrence of the error is transmitted.

The AP <NUM> may give the user a notification corresponding to the registration response signal received from the AP <NUM> in step F304. For example, if a registration response signal including information indicating the absence of an error is received, the AP <NUM> notifies the user of the successful registration. Alternatively, the AP <NUM> may notify the user of having joined the MAP network <NUM>. On the other hand, if a registration response signal including information indicating the occurrence of an error is received, the AP <NUM> notifies the user of the registration failure. Alternatively, the AP <NUM> may notify the user of the failure to join the MAP network <NUM>. If the registration response signal includes information indicating the cause of the error, the AP <NUM> may notify the user of the cause of the error.

In the present embodiment, the information about the wireless I/F of the AP <NUM> and the information about the BSS other APs can join are described to be included in the registration request signal transmitted from the AP <NUM>. However, this is not restrictive. The AP <NUM> may obtain such information from the AP <NUM> by transmitting a query message for inquiring such information of the AP <NUM> after the completion of the processing up to step F304, and receiving a corresponding response message. Similarly, the AP <NUM> may also obtain the capability information about whether the AP <NUM> can simultaneously establish a plurality of backhaul links by transmitting a query message and receiving a corresponding response message.

If there is a version or versions capable of establishing a plurality of backhaul links among a plurality of versions of the Wi-Fi EasyMesh standard, the AP <NUM> may inquire the version of the standard supported by the AP <NUM>. In such a case, the AP <NUM> can determine whether the AP <NUM> can establish a plurality of backhaul links based on the information about the version of the Wi-Fi EasyMesh standard supported by the AP <NUM>.

By the processing described above, the AP <NUM> is registered in the AP <NUM>, which is the controller, as an agent of the MAP network <NUM>. In addition, the AP <NUM> can obtain the information about the wireless I/F of the AP <NUM> and the BSS other APs can join, and the capability information about the establishment of a plurality of backhaul links by the AP <NUM>.

Next, the APs <NUM> and <NUM> establish a backhaul link therebetween. Here, processing for establishing a link between agents at Layer <NUM> (data link layer) of the Open Systems Interconnection (OSI) model is referred to as an on-boarding process. The AP <NUM> can be added to the MAP network <NUM> by performing an on-boarding process between the APs <NUM> and <NUM>. In the sequence illustrated in <FIG>, the on-boarding process is performed by a method compliant with the WPS standard.

To start the on-boarding process between the APs <NUM> and <NUM>, the user initially presses buttons on the respective APs <NUM> and <NUM>. The buttons can also be used for communication parameter setting processing using a push button configuration (PBC) method compliant with the WPS standard.

When the buttons are pressed, the APs <NUM> and <NUM> start the on-boarding process using a method compliant with the WPS standard. The AP <NUM> initially transmits a beacon including information indicating that a WPS process is started. The AP <NUM> detects the AP <NUM> as an AP performing WPS by receiving the beacon transmitted from the AP <NUM>. Alternatively, the AP <NUM> may detect the AP <NUM> by transmitting a Probe Request and receiving a corresponding Probe Response from the AP <NUM>.

In step F305, the AP <NUM> detecting the AP <NUM> as an AP performing WPS transmits an Association Request to the AP <NUM>. The AP <NUM> here transmits an Association Request accompanied by a MAP information element (MAP IE). The MAP IE is an information element compliant with the Wi-Fi EasyMesh standard, and includes information indicating that the AP <NUM> is transmitting the Association Request as a backhaul STA.

In step F306, the AP <NUM> receiving the Association Request transmits an Association Response to the AP <NUM> as a response. The Association Response also includes a MAP IE. The MAP IE transmitted from the AP <NUM> includes information indicating that the connected network <NUM> is a BSS to which other APs can connect.

The APs <NUM> and <NUM> may respectively transmit an Association Request and an Association Response including information indicating whether the same apparatus can establish a plurality of backhaul links.

In step F307, the AP <NUM> receiving the Association Response performs a WPS process with the AP <NUM> to share the communication parameters of a fronthaul BSS of the AP <NUM> that the AP <NUM> can join. In the present embodiment, the AP <NUM> here provides the AP <NUM> with the communication parameters of the network <NUM> as the communication parameters of the fronthaul BSS of the AP <NUM> that the AP <NUM> can join. The wireless LAN frames transmitted and received in the WPS process includes a MAP IE. When seen from the AP <NUM>, the network <NUM> is called a backhaul BSS.

When the AP <NUM> shares the communication parameters with the AP <NUM> by the WPS process, the communication link between the APs <NUM> and <NUM> is disconnected afterwards. In step F308, the AP <NUM> transmits an Association Request to the AP <NUM> by using the communication parameters of the fronthaul BSS of the AP <NUM> obtained by the WPS process.

In step F309, the AP <NUM> receiving the Association Request transmits an Association Response to the AP <NUM> as a response. The Association Request and Association Response transmitted are each accompanied by the MAP IE. By such processing, a backhaul link is established between the APs <NUM> and <NUM>. The backhaul link then can be encrypted by a <NUM>-way handshake as appropriate.

Next, the agent AP <NUM> is registered in the AP <NUM> which is the controller. Specifically, the AP <NUM> searches for the controller and transmits a registration request. The processing of steps F310 to F313 is similar to that of the foregoing steps F301 to F304. A description thereof will thus be omitted. Like the AP <NUM>, the AP <NUM> obtains the information about the wireless I/F of the AP <NUM> and a BSS other APs can join, and the capability information about the establishment of a plurality of backhaul links by the AP <NUM>.

In the present embodiment, suppose that the AP <NUM> successfully obtains the information about the wireless I/Fs of the APs <NUM> and <NUM> and BSSs other APs can join, and the capability information about the establishment of a plurality of backhaul links. In step F314, the AP <NUM> performs processing for determining whether to establish a plurality of backhaul links between the APs <NUM> and <NUM>. Details of the determination process (backhaul establishment determination process) performed by the AP <NUM> will be described below with reference to <FIG>. Suppose here that the AP <NUM> determines to establish a plurality of backhaul links between the APs <NUM> and <NUM>.

In step F315, the AP <NUM> transmits a backhaul establishment start message which is a start message (start request) intended to start establishing a plurality of backhaul links to the AP <NUM> based on the determination result. The backhaul establishment start message includes information indicating the network specified as a BSS to be used in establishing a backhaul link. Specifically, the backhaul establishment start message includes the BSS ID of the specified network. Alternatively, an identifier that can uniquely identify the specified network between the APs <NUM> and <NUM> may be included. In the present embodiment, the network <NUM> constructed by the AP <NUM> is specified as the network to be used in establishing a backhaul link. The network <NUM> is called a fronthaul BSS when seen from the AP <NUM>, and a backhaul BSS when seen from the AP <NUM>. In addition, information indicating the frequency band and frequency channels to be used by the specified network may also be included. If the establishment of a new backhaul link involves communication parameter setting processing between the APs <NUM> and <NUM>, the start request may include information specifying the method of the setting processing. A WPS method or DPP method is selected as the method of the communication parameter setting processing. If the network to be used to establish a new backhaul link is determined to be not constructed yet based on the information obtained from the AP <NUM>, the start request may include information for giving an instruction to construct the network.

The AP <NUM> receiving the start request from the AP <NUM> determines whether a backhaul link can be established via the specified network. In step F316, the AP <NUM> transmits a backhaul establishment start response message which is a start response message including information indicating the determination result to the AP <NUM>. An example of the case where the backhaul link is determined unable to be established via the specified network will now be described. If a communication parameter setting process using the WPS method is necessary for the establishment of the backhaul link and the AP <NUM> is already performing the communication parameter setting process using the WPS method with another apparatus, the backhaul link is determined unable to be established. Note that the case where the AP <NUM> determines that the backhaul link is unable to be established is not limited thereto.

If the backhaul establishment start response message received from the AP <NUM> includes information indicating that the AP <NUM> can establish the backhaul link, then in step F317, the AP <NUM> transmits a start message to the AP <NUM> as well. The start message transmitted to the AP <NUM> here is similar to that transmitted to the AP <NUM> in step F315. Instead of or in addition to the information included in the start message transmitted in step F315, information for specifying a wireless I/F to operate as a backhaul STA in the AP <NUM> may be included.

The AP <NUM> receives the backhaul establishment start message, and determines whether a backhaul link can be established like the AP <NUM>. In step F318, the AP <NUM> transmits a backhaul establishment start response message including the determination result to the AP <NUM>. Suppose here that the AP <NUM> transmits a backhaul establishment start response message indicating that a backhaul link can be established to the AP <NUM>.

If the start response message received from the AP <NUM> includes the information indicating that a backhaul link can be established, the AP <NUM> waits until a new backhaul link is established between the APs <NUM> and <NUM>. If the received start response message includes information indicating that the AP <NUM> is unable to establish the backhaul link, the AP <NUM> transmits a message for cancelling the establishment of the backhaul link to the AP <NUM>. In such a case, the processing for establishing the second backhaul link between the APs <NUM> and <NUM> is stopped. This is not restrictive, and the AP <NUM> may transmit a backhaul establishment start message to the AP <NUM> again after a lapse of a certain time.

In the present embodiment, the backhaul establishment start messages are successively transmitted to the APs <NUM> and <NUM> in steps F315 and F317. However, the order is not limited thereto. The backhaul establishment start messages may be simultaneously transmitted to the APs <NUM> and <NUM> or transmitted in reverse order. Alternatively, a backhaul establishment start message may be broadcast or multicast in the MAP network <NUM>.

Meanwhile, after the APs <NUM> and <NUM> transmit the start response messages indicating that a backhaul link can be established in steps F316 and F318, respectively, the APs <NUM> and <NUM> start processing for establishing the backhaul link. If the AP <NUM> has not constructed the specified network yet, the AP <NUM> initially constructs the network. In the present embodiment, the specified network is the network <NUM>. In steps F319 to F323, the APs <NUM> and <NUM> perform processing similar to the on-boarding process performed in the foregoing steps F305 to F309 on the network <NUM>.

If the APs <NUM> and <NUM> complete the on-boarding process and the second backhaul link is established between the APs <NUM> and <NUM>, then in step F324, the AP <NUM> transmits a backhaul establishment completion message to the AP <NUM>. In step F326, the AP <NUM> similarly transmits a backhaul establishment completion message to the AP <NUM>.

In steps F325 and F327, the AP <NUM> receiving the backhaul establishment completion messages transmits a backhaul establishment confirmation message to the APs <NUM> and <NUM>. The backhaul establishment confirmation message may include an identifier that can uniquely identify the established new backhaul link in the MAP network <NUM>. The AP <NUM> can subsequently instruct the agents to control the backhaul link by using the identifier.

If the backhaul link fails to be established, a backhaul establishment error message including information indicating the failure of the establishment of the backhaul link may be transmitted to the AP <NUM> instead of the backhaul establishment completion message. If the AP <NUM> receives the backhaul establishment error message from at least either one of the APs <NUM> and <NUM>, the AP <NUM> transmits a stop message for stopping the establishment of the backhaul link to the APs <NUM> and <NUM>.

While the backhaul establishment completion message and the backhaul establishment error message are described to be transmitted from both the APs <NUM> and <NUM> to the AP <NUM>, this is not restrictive and the messages may be transmitted from only either one of the APs <NUM> and <NUM>.

In the present embodiment, the messages communicated in steps F315 to F318 and F324 to F327 are transmitted in a format compliant with the IEEE <NUM> standard. However, this is not restrictive and the messages may be in other formats.

By the foregoing processing, a plurality of backhaul links can be established between the APs <NUM> and <NUM>. As described above, in establishing a plurality of backhaul links between agents, the controller can control the establishment of the plurality of backhaul links by the controller giving instructions to establish the backhaul links.

As illustrated in <FIG>, the establishment of the second backhaul link between the APs <NUM> and <NUM> is triggered by the backhaul establishment start messages transmitted from the AP <NUM>. This is convenient for the user since the user does not need to press the buttons on the APs <NUM> and <NUM> in establishing the second backhaul link between the APs <NUM> and <NUM>.

In <FIG>, the APs <NUM> and <NUM> perform a communication parameter sharing process using the WPS method each time a backhaul link is established. However, this is not restrictive. The APs <NUM> and <NUM> may share the communication parameters to be used in establishing another backhaul link during the initial sharing process (steps F305 to F309). In such a case, the APs <NUM> and <NUM> may omit the processing of step F321.

<FIG> is a flowchart illustrating processing performed when the AP <NUM> establishes a plurality of backhaul links between other APs. The processing is performed by the control unit <NUM> reading a computer program stored in the storage unit <NUM> and executing the computer program.

The AP <NUM> starts the processing of this flowchart when a new agent joins the MAP network <NUM> controlled by the AP <NUM>. Alternatively, the AP <NUM> may start the processing of this flowchart based on instructions from the user or based on detection of a topological change in the MAP network <NUM>. Alternatively, the AP <NUM> may start the processing of this flowchart based on a request made by an agent belonging to the MAP network <NUM> to establish a plurality of backhaul links.

In step S401, the AP <NUM> initially obtains information about the agents in the MAP network <NUM>. The agent information obtained here is the information notified by the AP-Autoconfiguration messages illustrated in <FIG> (steps F303 and F312). In addition or instead, the AP <NUM> may obtain network information notified from the agents via backhaul links. Alternatively, the AP <NUM> may transmit a query message to the agents and obtain information from the agents as responses thereto. For example, the AP <NUM> may transmit an AP Capability Query message defined as a query message for inquiring capability information about an AP by the Wi-Fi EasyMesh standard. In such a case, the AP <NUM> can obtain capability information about the AP <NUM> by receiving an AP Capacity Report message as a response from the AP <NUM>. This is not restrictive, and the AP <NUM> may obtain agent information by using other query messages as well. In the present embodiment, the AP <NUM> obtains agent information from all the agents joining the MAP network <NUM>. However, this is not restrictive. The AP <NUM> which is the controller may obtain information only about a given agent or agents.

In step S402, the AP <NUM> determines whether a plurality of backhaul links can be established between two given agents in the MAP network <NUM>. Whether an agent has the capability to establish a plurality of backhaul links is determined based on the information obtained from the agent in step S401. In the present embodiment, the AP <NUM> determines whether a plurality of backhaul links can be established between the APs <NUM> and <NUM>. The AP <NUM> makes the determination based on the information about the usable frequency bands of each of the APs <NUM> and <NUM>, obtained from the APs <NUM> and <NUM> in step S401. Specifically, if both the APs <NUM> and <NUM> can use both <NUM>- and <NUM>-GHz bands, the AP <NUM> makes a determination of YES in this step. On the other hand, if at least either one of the APs <NUM> and <NUM> can only use either one of the <NUM>- and <NUM>-GHz frequency bands, the AP <NUM> makes a determination of NO in this step. Instead or in addition, if the AP <NUM> obtains information about wireless I/Fs that can operate as backhaul STAs from the APs <NUM> and <NUM> in step S401, the AP <NUM> may make the determination in this step based on the information. Specifically, if both the APs <NUM> and <NUM> notify the AP <NUM> of wireless I/Fs other than the ones already in use as wireless I/Fs that can operate as backhaul STAs, the AP <NUM> makes a determination of YES in this step. On the other hand, if at least either one of the APs <NUM> and <NUM> notifies the AP <NUM> of only the wireless I/F already in use as a wireless I/F that can operate as a backhaul STA, or of no wireless I/F, the AP <NUM> makes a determination of NO in this step. Instead or in addition, if the AP <NUM> obtains capability information about whether a plurality of backhaul links can simultaneously be established from the APs <NUM> and <NUM> in step S401, the AP <NUM> may make the determination in this step based on the capability information. Specifically, if both the APs <NUM> and <NUM> can simultaneously establish a plurality of backhaul links, the AP <NUM> makes a determination of YES in this step. On the other hand, if at least either one of the APs <NUM> and <NUM> is unable to simultaneously establish a plurality of backhaul links, the AP <NUM> makes a determination of NO in this step. If the determination in this step is YES (YES in step S402), the processing proceeds to step S403. On the other hand, if the determination in this step is NO (NO in step S402), the processing ends.

In this step, the AP <NUM> may make the determination only on two specific agents in the MAP network <NUM>. Alternatively, the AP <NUM> may make the determination on all combinations of agents having established backhaul links in the MAP network <NUM>. If the AP <NUM> makes the determination on all the combinations of agents having established backhaul links, the AP <NUM> performs the processing of step S403 and the subsequent steps on each combination.

In step S403, the AP <NUM> determines whether to establish a plurality of backhaul links. In this step, the AP <NUM> may determine whether establishment of a plurality of backhaul links is necessary between the agents on which the determination made in step S402 is YES. <FIG> illustrates an example of the processing in this step.

In step S501, the AP <NUM> obtains a communication status of the backhaul link between the two target agents. In the present embodiment, the AP <NUM> obtains the communication status of the backhaul link already established between the APs <NUM> and <NUM>. The AP <NUM> obtains the communication status of the backhaul link by being notified of information about the communication status from the agents. Alternatively, the AP <NUM> may transmit a query message for inquiring the communication status of the backhaul link to at least either one of the APs <NUM> and <NUM> and obtain the communication status as a response message. For example, the AP <NUM> may obtain the communication status by transmitting a query message for inquiring link metrics information about the backhaul link and obtaining the link metrics information included in a response message. Link metrics are expressed, for example, by capability information about the throughput of at least either one of the APs <NUM> and <NUM> or information about the physical rate or traffic volume of the target backhaul link. In the present embodiment, the link metrics are expressed by a link usage rate that is information about the traffic volume of the backhaul link. In this step, the AP <NUM> may also obtain a radio wave condition indicated by the received signal strength indicator (RSSI) of at least either one of the APs <NUM> and <NUM> or the state of the frequency channels.

In step S502, the AP <NUM> determines whether the traffic volume (link usage rate) of the target backhaul link is greater than or equal to a predetermined threshold. In this step, the AP <NUM> determines whether to establish a plurality of backhaul links based on the communication status between the agents, obtained in step S501. In the present embodiment, since the traffic volume (link usage rate) of the backhaul link between the APs <NUM> and <NUM> is obtained as the communication status, the AP <NUM> makes the determination in this step based on the traffic volume (link usage rate). If the traffic volume (link usage rate) obtained in step S501 is greater than or equal to the predetermined threshold, the AP <NUM> makes a determination of YES in this step (YES in step S502) and the processing proceeds to step S503. On the other hand, if the traffic volume (link usage rate) obtained in step S501 is less than the predetermined threshold, the AP <NUM> makes a determination of NO in this step (NO in step S502) and the processing proceeds to step S506. The threshold used in making the determination may be set by the AP <NUM> in advance, or calculated by the AP <NUM> from the link metrics of the entire MAP network <NUM>. The threshold may be set by the user.

In the present embodiment, the AP <NUM> makes the determination in this step based on the traffic volume. However, this is not restrictive. If the AP <NUM> obtains the physical rate of the target backhaul link as the communication status in step S501, the AP <NUM> may make the determination in step S502 based on the physical rate. In such a case, the AP <NUM> determines in this step whether the physical rate is lower than or equal to a predetermined threshold. Alternatively, if the AP <NUM> obtains capability information about the throughput of at least either one of the APs <NUM> and <NUM> as the communication status in step S501, the AP <NUM> may make the determination in step S502 based on the throughput. In such a case, the AP <NUM> determines in step S502 whether the throughput is lower than or equal to a predetermined threshold.

In step S503, the AP <NUM> obtains the communication status of the entire MAP network <NUM>. In this step, the AP <NUM> obtains a communication status such as the link metrics of constructed networks from all the agents in the MAP network <NUM>. Specifically, the AP <NUM> obtains the traffic volumes, physical rates, or throughput of the networks constructed by all the agents in the MAP network <NUM>. Like step S501, the AP <NUM> may transmit query messages for obtaining information about the link metrics and obtain the communication status from response messages. If the AP <NUM> has not found out the frequency channels of the networks constructed by the agents, the AP <NUM> may obtain information about the frequency channels in this step.

In step S504, the AP <NUM> determines whether the establishment of a plurality of backhaul links between the target agents affects other communications in the MAP network <NUM> based on the communication status of the entire MAP network <NUM>, obtained in step S503. For example, if a new network <NUM> is constructed to establish a new backhaul link, wireless frames such as a beacon and data communication between backhaul links are transmitted on the same frequency channel as that of the network <NUM>. The establishment of a new backhaul link can thus interfere with existing communications and cause adverse effects such as a drop in the data communication speed of the existing communications and a packet loss. Making the determination can prevent a new backhaul link from interfering with communications via other links already established in the MAP network <NUM>.

Specifically, in this step, the AP <NUM> determines whether there is another link on the same frequency channel as that of the new backhaul link to be established. If there is another link, the AP <NUM> makes a determination of YES in this step (YES in step S504) and the processing proceeds to step S506. On the other hand, if there is no other link, the AP <NUM> makes a determination of NO in this step (NO in step S504) and the processing proceeds to step S505. If the determination in this step is YES, the AP <NUM> may further make a determination based on the communication status of another link on the same frequency channel. Specifically, if the traffic volume (link usage rate) of another link is less than or equal to a predetermined threshold, the AP <NUM> determines that the new backhaul link to be established will not affect the existing link, and the processing proceeds to step S505. On the other hand, if the traffic volume (link usage rate) of another link is greater than a predetermined threshold, the AP <NUM> determines that the new backhaul link to be established can affect the existing link, and the processing proceeds to step S506.

Steps S503 and S504 may be omitted. In such a case, if the determination in step S502 is YES, the processing proceeds to step S505.

In step S505, the AP <NUM> determines that to establish a plurality of backhaul links. Specifically, the AP <NUM> may store information indicating the determination that a plurality of backhaul links between the target agents is needed. In contrast, in step S506, the AP <NUM> determines to not establish a plurality of backhaul links. Specifically, the AP <NUM> may store information indicating the determination that a plurality of backhaul links between the target agents is not needed. After step S505 or S506, the processing ends.

The determination process illustrated in <FIG> is just an example and not restrictive. In the present embodiment, the determination is made based on the communication status between the target agents and the communication status of the entire MAP network <NUM>. However, this is not restrictive, and whether to establish a plurality of backhaul links may be determined based on the user's selection. In such a case, the processing of steps S501 to S504 may be omitted. For example, if the establishment of a plurality of backhaul links in the MAP network <NUM> is enabled by the user's setting, the AP <NUM> performs the processing of step S505. On the other hand, if the establishment of a plurality of backhaul links in the MAP network <NUM> is disabled by the user's setting, the AP <NUM> performs the processing of step S506. Alternatively, whether to enable the establishment of a plurality of backhaul links between specific agents may be set by the user. The user can make the setting via an STA connected to the AP <NUM> by a wired or wireless LAN or via the input unit <NUM> of the AP <NUM>. The user can make the setting via another device connected over an external network to which the AP <NUM> is connected, or via an STA belonging to a network in the MAP network <NUM>.

Alternatively, the AP <NUM> may make the determination of <FIG> based on the radio wave condition of the existing backhaul link. Specifically, if at least either one of the RSSIs of the APs <NUM> and <NUM> is lower than a predetermined threshold, the AP <NUM> performs the processing of step S505 to establish a plurality of backhaul links between the APs <NUM> and <NUM>. If the RSSIs are higher than or equal to the predetermined threshold, the AP <NUM> performs the processing of step S506. In such a manner, if an RSSI related to the existing backhaul link between the APs <NUM> and <NUM> is low, a backup backhaul link can be established by establishing a plurality of backhaul links.

Referring back to <FIG>, in step S404, the AP <NUM> determines whether to establish a plurality of backhaul links between the agents. The AP <NUM> makes this determination based on the determination result of step S403. Specifically, if the processing of step S505 in <FIG> is performed, the AP <NUM> makes a determination of YES. If the processing of step S506 in <FIG> is performed, the AP <NUM> makes a determination of NO. If the determination in this step is NO (NO in step S404), the processing returns to step S403. The AP <NUM> may include a timer, and if a determination of YES is not made in step S404 before a lapse of a predetermined time from when a determination of NO is made in step S404 for the first time, may end the processing of this flowchart. Alternatively, the AP <NUM> may end the processing of this flowchart if a determination of NO is made in step S404 a predetermined number of times in succession. If the determination in step S404 is YES (YES in step S404), the processing proceeds to step S405.

In step S405, the AP <NUM> transmits a backhaul establishment start message to the target agents (at least either one of the APs <NUM> and <NUM>). The backhaul establishment start message transmitted here corresponds to those described in steps F315 and F317 of <FIG>.

In step S406, the AP <NUM> determines whether backhaul establishment start response messages are received from the target agents (at least either one of the APs <NUM> and <NUM>). The backhaul establishment start response messages to be received here correspond to those described in steps F316 and F318 of <FIG>. In this step, the AP <NUM> waits for the reception of backhaul establishment start response messages from the agents to which the backhaul establishment start message is transmitted in step S406. If the backhaul establishment start response messages are not received (NO in step S406), the processing returns to step S406. If the backhaul establishment start response message are not received before a lapse of a predetermined time from the transmission of the backhaul establishment start message in step S405, the AP <NUM> may end the processing of this flowchart. If the backhaul establishment start response messages are received (YES in step S406), the processing proceeds to step S407.

In step S407, the AP <NUM> determines whether a new backhaul link can be established between the target agents (between the APs <NUM> and <NUM>). Specifically, the AP <NUM> determines whether the backhaul establishment start response messages received in step S406 include information indicating that a new backhaul link can be established. If the backhaul establishment start response messages received from both the APs <NUM> and <NUM> include the information indicating that a new backhaul link can be established, the AP <NUM> makes a determination of YES in this step (YES in step S407) and the processing proceeds to step S408. On the other hand, if the backhaul establishment start response message(s) received from at least either one of the APs <NUM> and <NUM> includes information indicating that a new backhaul link is unable to be established, the AP <NUM> makes a determination of NO in this step (NO in step S407) and the processing proceeds to step S409.

If a new backhaul link is unable to be established, then in step S409, the AP <NUM> performs processing for cancelling the establishment of a new backhaul link. Specifically, the AP <NUM> transmits a stop message to stop the processing for establishing the backhaul link to at least either one of the APs <NUM> and <NUM>. The AP <NUM> may transmit the stop message to only the agent, if any, from which the backhaul establishment start response message including the information indicating that a new backhaul link can be established is transmitted. If the AP <NUM> has instructed the AP <NUM> to construct the network <NUM> to establish a new backhaul link, the AP <NUM> may instruct the AP <NUM> to stop the network <NUM>. After the execution of step S409, the processing ends.

On the other hand, if a new backhaul link can be established, then in step S408, the AP <NUM> determines whether a backhaul establishment completion message is received from the target agents. The backhaul establishment completion message to be received here corresponds to those described in steps F324 and F326 of <FIG>. The AP <NUM> may just receive the message from at least either one of the APs <NUM> and <NUM>.

In the present embodiment, the AP <NUM> is described to receive the backhaul establishment start response messages. However, this is not restrictive. The AP <NUM> may start a timer after the transmission of a backhaul establishment start message, and determine whether a backhaul establishment completion message is received before a lapse of a predetermined time. In other words, after the execution of step S405, the AP <NUM> may skip the processing of steps S406 and S407 and execute the processing of step S408. In such a case, if a backhaul establishment completion message is not received before a lapse of a predetermined time, the processing proceeds to step S409. If a backhaul establishment completion message is received before a lapse of a predetermined time, the processing proceeds to step S410.

In step S410, the AP <NUM> transmits a backhaul establishment confirmation message to the target agents (at least either one of the APs <NUM> and <NUM>). The backhaul establishment confirmation message transmitted in this step corresponds to those described in steps F325 and F327 of <FIG>. This step may be omitted. After the execution of this step, the processing ends.

As illustrated in <FIG>, the controller controls whether to establish a plurality of backhaul links between the agents, whereby backhaul links can be established while taking into account the effect on other communications in the MAP network <NUM>.

<FIG> is a flowchart illustrating processing performed when the AP <NUM> establishes a plurality of backhaul links with the AP <NUM>. The processing is performed by the control unit <NUM> reading a computer program stored in the storage unit <NUM> and executing the computer program.

The AP <NUM> starts the processing of this flowchart when a new backhaul link is established with another agent controlled by the AP <NUM>. Alternatively, the AP <NUM> may start the processing of this flowchart based on instructions from the user.

In step S601, the AP <NUM> determines whether a backhaul establishment start message is received from the AP <NUM> which is the controller. The backhaul establishment start message to be received here corresponds to that described in step F315 of <FIG>. If no backhaul establishment start message is received (NO in step S601), the processing returns to step S601. If no backhaul establishment start message is received before a lapse of a predetermined time from the start of the processing of this flowchart, the processing ends. On the other hand, if a backhaul establishment start message is received (YES in step S601), the processing proceeds to step S602.

In step S602, the AP <NUM> determines whether the AP <NUM> can establish a new backhaul link. Since details of the determination process have been described in conjunction with step F316 of <FIG>, a description thereof will be omitted. If a new backhaul link can be established (YES in step S602), the processing proceeds to step S603. On the other hand, if a new backhaul link is unable to be established (NO in step S602), the processing proceeds to step S604.

If the AP <NUM> is unable to establish a new backhaul link, then in step S604, the AP <NUM> transmits a backhaul establishment start response message including information indicating that a backhaul link is unable to be established to the AP <NUM> which is the controller. After the processing of step S604, the processing ends.

On the other hand, if the AP <NUM> can establish a new backhaul link, then in step S603, the AP <NUM> transmits a backhaul establishment start response message including information indicating that a backhaul link can be established to the AP <NUM> which is the controller. The backhaul establishment start response message transmitted here corresponds to that described in step F316 of <FIG>.

In step S605, the AP <NUM> performs processing for establishing a new backhaul link with the AP <NUM>. In the present embodiment, the AP <NUM> performs the establishment process using the WPS method, described in steps F319 to F323 of <FIG>, with the AP <NUM>.

In step S606, the AP <NUM> determines whether a new backhaul link is successfully established. If the AP <NUM> succeeds in establishing a new backhaul link with the AP <NUM> (YES in step S606), the processing proceeds to step S608. On the other hand, if the AP <NUM> fails in establishing a new backhaul link with the AP <NUM> (NO in step S606), the processing proceeds to step S607.

If a new backhaul link with the AP <NUM> fails to be established, then in step S607, the AP <NUM> transmits a backhaul establishment failure message to the AP <NUM> which is the controller. After the processing of step S607, the processing ends.

On the other hand, if a new backhaul link with the AP <NUM> is successfully established, then in step S608, the AP <NUM> transmits a backhaul establishment completion message to the AP <NUM> which is the controller. The backhaul establishment completion message transmitted here corresponds to that described in step F324 of <FIG>.

In step S609, the AP <NUM> determines whether a backhaul establishment confirmation message is received from the AP <NUM> which is the controller. As described above, a backhaul establishment confirmation message may not be transmitted from the AP <NUM>, in which case this step is omitted. The backhaul establishment confirmation message to be received here corresponds to that described in step F325 of <FIG>. If no backhaul establishment confirmation message is received from the AP <NUM> (NO in step S609), the processing returns to step S609. On the other hand, if a backhaul establishment confirmation message is received from the AP <NUM> which is the controller (YES in step S609), the processing ends.

As described above, <FIG> illustrates the processing performed when the AP <NUM> establishes a plurality of backhaul links with the AP <NUM>. By this processing, a plurality of backhaul links can be established between the agents based on instructions from the controller.

<FIG> is a flowchart illustrating processing performed when the AP <NUM> stops a backhaul link between the APs <NUM> and <NUM>. The processing is performed by the control unit <NUM> reading a computer program stored in the storage unit <NUM> and executing the computer program. If a plurality of backhaul links is established between the APs <NUM> and <NUM> and then no longer used by the target agents, the controller stops either one of the backhaul links.

The AP <NUM> starts the processing of this flowchart when a plurality of backhaul links is established between the APs <NUM> and <NUM>. Alternatively, the AP <NUM> may start the processing of this flowchart based on instructions from the user.

In step S701, the AP <NUM> initially determines whether to use a plurality of backhaul links between predetermined agents. In this step, processing similar to that of the flowchart illustrated in <FIG> is performed. Specifically, the AP <NUM> determines whether the traffic volume (link usage rate) of each of the plurality of backhaul links established between the APs <NUM> and <NUM> is less than or equal to a predetermined threshold. The threshold in this step is less than that in step S502. If the traffic volume (link usage rate) of either one of the backhaul links is less than or equal to the predetermined threshold, the AP <NUM> may determine that a plurality of backhaul links between the APs <NUM> and <NUM> is not needed. On the other hand, if the traffic volumes (link usage rates) of both the backhaul links are greater than the predetermined threshold, the AP <NUM> may determine that a plurality of backhaul links between the APs <NUM> and <NUM> is needed. Instead or in addition, the AP <NUM> may make the determination based on the communication status in the MAP network <NUM>. Specifically, the AP <NUM> makes the determination based on the traffic volume (link usage rate) of another link in the MAP network <NUM> using the same frequency channel as that of either one of the plurality of backhaul links established between the APs <NUM> and <NUM>. If the traffic volume (link usage rate) of another link is greater than or equal to a predetermined threshold, the AP <NUM> determines to not use a plurality of backhaul links between the APs <NUM> and <NUM>. On the other hand, if the traffic volume (link usage rate) of another link is less than the predetermined threshold, the AP <NUM> determines to use a plurality of backhaul links between the APs <NUM> and <NUM>. Alternatively, the AP <NUM> may make the determination based on instructions from the user. Specifically, if execution of a plurality of backhaul links in the MAP network <NUM> is disabled by the user's setting, the AP <NUM> determines to not use a plurality of backhaul links between the APs <NUM> and <NUM>. The AP <NUM> makes a similar determination if the user gives an instruction to end a plurality of backhaul links between the APs <NUM> and <NUM>.

Alternatively, if there is a plurality of backhaul links established to provide a backup for a backhaul link between the agents, the AP <NUM> may make the determination based on the radio wave condition of the backhaul link for main use. Specifically, if the RSSI of the backhaul link for main use is greater than or equal to a predetermined threshold, the AP <NUM> determines to not use a plurality of backhaul links between the APs <NUM> and <NUM>. On the other hand, if the RSSI of the backhaul link for main use is less than the predetermined threshold, the AP <NUM> determines to use a plurality of backhaul links between the APs <NUM> and <NUM>.

In step S702, the AP <NUM> determines whether to use a plurality of backhaul links between the predetermined agents based on the result of the determination made in step S701. If, in step S701, a plurality of backhaul links is determined to be used between the APs <NUM> and <NUM>, the AP <NUM> makes a determination of YES in this step (YES in step S702) and the processing ends. The plurality of backhaul links between the APs <NUM> and <NUM> is thereby maintained. On the other hand, if, in step S701, a plurality of backhaul links is determined to not be used, the AP <NUM> makes a determination of NO in this step (NO in step S702) and the processing proceeds to step S703.

In step S703, the AP <NUM> transmits a stop message for giving an instruction to stop a target backhaul link to the predetermined agents (at least either one of the APs <NUM> and <NUM>). The backhaul link to be stopped here is that the traffic volume (link usage rate) of which is determined to be less than or equal to the predetermined threshold in step S701. Which backhaul link to stop in a case where the traffic volumes (link usage rates) of both the backhaul links are less than or equal to the predetermined threshold may be set in the AP <NUM> in advance. In such a case, the AP <NUM> may determine which backhaul link to stop based on the frequency bands (<NUM>- or <NUM>-GHz) where the backhaul links are established. The AP <NUM> may determine to maintain a backhaul link of greater traffic volume (higher link usage rate). Alternatively, which backhaul link to maintain may be selected by the user. The stop message is transmitted via the backhaul link other than the one to be stopped. After the execution of the processing of step S703, the processing ends.

At least either one of the APs <NUM> and <NUM> receives the stop message from the AP <NUM> and stops the corresponding backhaul link. The AP <NUM> constructing the network <NUM> where the backhaul link is established may stop the network <NUM> if no other communication is performed on the network <NUM>. The AP <NUM> may autonomously stop the network <NUM>. The AP <NUM> may instruct the AP <NUM> to stop the network <NUM>.

As described above, <FIG> illustrates a method for stopping one of a plurality of backhaul links by the control of the controller if the plurality of backhaul links is no longer used between the agents. The controller can control the plurality of backhaul links between the agents based on a change in the traffic volumes of the backhaul links and a change in the communication status in the MAP network <NUM>.

In the present embodiment, the WPS method is described to be used in establishing a backhaul link. However, this is not restrictive, and the DPP method may be used. In the DPP method, the communication parameters are shared by a method compliant with the Wi-Fi DPP standard. In the communication parameter sharing process compliant with the Wi-Fi DPP standard, an apparatus playing the role of providing communication parameters is referred to as a configurator, and an apparatus playing the role of obtaining the communication parameters is referred to as an enrollee. The enrollee can join a network by using communication parameters obtained from the configurator. The configurator can provide communication parameters not only to an STA but also to an AP so that the AP constructs a network using the provided communication parameters.

<FIG> is a sequence diagram illustrating an example of processing performed when the APs <NUM> and <NUM> establish a plurality of backhaul links by using the DPP method. In the present embodiment, the AP <NUM> operates as a configurator, and the APs <NUM> and <NUM> as enrollees. At the start of the sequence of <FIG>, the AP <NUM> has already shared communication parameters with the AP <NUM> by using the DPP method, and the AP <NUM> has joined the network <NUM> constructed by the AP <NUM>.

In step F801, the AP <NUM> initially transmits an AP-Autoconfiguration Search message to search the MAP network <NUM> for a controller. This processing is similar to that of step F301 in <FIG>.

In step F802, the AP <NUM> operating as the controller receives the search signal from the AP <NUM>, and transmits an AP-Autoconfiguration Response message to the AP <NUM>. This processing is similar to that of step F302 in <FIG>.

In <FIG>, since the WPS method is used, the APs <NUM> and <NUM>, and the APs <NUM> and <NUM>, transmit and receive AP-Autoconfiguration WSC messages therebetween (steps F303, F304, F312, and F313 in <FIG>). In contrast, the use of the DPP method does not involve the transmission and reception of such messages. In this processing, messages including capability information about wireless communication of the APs <NUM> and <NUM> and information about wireless I/Fs or BSSs other APs can join are then transmitted instead of the WSC messages. Alternatively, such information may be included in the AP-Autoconfiguration Search messages transmitted from the APs <NUM> and <NUM>. Alternatively, the AP <NUM> may transmit a query message for requesting acquisition of such information, and the APs <NUM> and <NUM> may transmit the corresponding information as included in a response message to the query message.

In step F803, to establish a new backhaul link to the AP <NUM>, the AP <NUM> initially performs a DPP sharing process with the AP <NUM>. The DPP sharing process includes a bootstrapping process, an authentication process, and a configuration process.

The APs <NUM> and <NUM> initially perform the bootstrapping process. By the bootstrapping process, the configurator and the enrollee share public key information. Specifically, the configurator uses its camera function to capture and share public key information included in a Quick Response (QR) code (registered trademark) related to the enrollee. This is not restrictive, and the public key information may be shared by Bluetooth (registered trademark) communication or NFC communication. Alternatively, the configurator and the enrollee may share the public key information by a public key exchange (PKEX) method where the public key information is shared by using a common character string.

Next, the APs <NUM> and <NUM> performs the authentication process. The authentication process is performed between a configurator and an enrollee. In this process, the configurator and the enrollee exchange authentication request, authentication response, and authentication confirmation frames to authenticate each other's devices.

Next, the APs <NUM> and <NUM> perform the configuration process. In the configuration process, the configurator provides the enrollee with a connector that includes communication parameters. A connector includes various types of information used by an authentication protocol and a key exchange algorithm defined by the Wi-Fi DPP standard. In the present embodiment, the connector includes information for joining the network <NUM> constructed by the AP <NUM>. The information provided by the AP <NUM> in the configuration process may include information for identifying a connection destination using communication parameters, such as the SSID of the AP that is the connection destination.

In step F804, the AP <NUM> performs a DPP connection process by using the connector obtained from the AP <NUM>. Specifically, the AP <NUM> joins the network <NUM> constructed by the AP <NUM> and establishes a backhaul link by using the obtained connector.

In step F805, the AP <NUM> transmits an AP-Autoconfiguration Search message to the AP <NUM>. In step F806, the AP <NUM> transmits an AP-Autoconfiguration Response message to the AP <NUM> as a response thereto. Such processing is similar to that of steps F310 and F311 in <FIG>. Like the processing of steps F801 and F802, the capability information about the wireless communication of the AP <NUM> and the information about wireless I/Fs and BSSs other APs can join may be transmitted in step F805 or by using another message.

In step F807, the AP <NUM> determines whether to establish a plurality of backhaul links between the APs <NUM> and <NUM>. This processing is similar to that of step F314 in <FIG>. In the present embodiment, the AP <NUM> determines to establish a plurality of backhaul links between the APs <NUM> and <NUM>.

The processing of steps F808 to F811 in <FIG> is similar to that of steps F315 to F318 of <FIG>. In this processing, the backhaul establishment start messages (steps F808 and F810) include information for giving an instruction to establish a new backhaul link by the DPP method.

In step F812, the APs <NUM> and <NUM> perform a DPP sharing process to establish a new backhaul link. The processing performed here is similar to that of step F803. The connector provided by the AP <NUM> in step F812 includes communication parameters for joining the network <NUM> constructed by the AP <NUM>. Since the APs <NUM> and <NUM> have already performed the DPP sharing process in step F803, a dispensable process or processes may be omitted. Specifically, the bootstrapping process may be omitted. Alternatively, the bootstrapping process and the authentication process may be omitted to perform only the configuration process.

In step F813, the AP <NUM> performs a DPP connection process by using the connector obtained in step F812. The AP <NUM> can thereby join the network <NUM> of the AP <NUM> and establish a second backhaul link to the AP <NUM>.

The processing of steps F814 to F817 in <FIG> is similar to that of steps F324 to F327 in <FIG>.

As illustrated in <FIG>, the APs <NUM> and <NUM> can thus perform the on-boarding process using the DPP method. In <FIG>, the DPP sharing process (step F812) is performed again in establishing a plurality of backhaul links. However, this is not restrictive, and all the connectors used to establish the backhaul links may be provided by the first DPP sharing process (step F803). Specifically, in step F803, the AP <NUM> may provide the AP <NUM> with the connectors for joining both the networks <NUM> and <NUM> constructed by the AP <NUM>. In such a case, when transmitting the backhaul establishment start messages to the APs <NUM> and <NUM>, the AP <NUM> may include information for specifying which connectors to use to establish the backhaul links. In addition, the AP <NUM> skips the processing of step F812.

In the present embodiment, a plurality of APs is described to be connected via wireless networks and perform wireless communication.

However, this is not restrictive. At least some of the APs may be connected via a wired network or networks and perform wired communication. In establishing a plurality of backhaul links, one of the backhaul links may be established via wired communication and the other(s) via wireless communication.

The APs <NUM>, <NUM>, and <NUM> may select the DPP method of higher security if the other device to share communication parameters with supports both the WPS and DPP methods. Alternatively, which sharing process to perform may be determined by user selection. Alternatively, if the other apparatus supports only either one of the methods, that method is selected.

At least part or all of the flowcharts of the APs <NUM> and <NUM> illustrated in <FIG>, <FIG>, <FIG>, and <FIG> may be implemented by hardware. In the case of hardware implementation, for example, a predetermined compiler may be used to generate dedicated circuits on a field-programmable gate array (FPGA) from the computer programs for implementing the steps, and the generated dedicated circuits may be used. Like an FPGA, a gate array circuit may be formed for hardware implementation. An application specific integrated circuit (ASIC) may be used for implementation. The steps of the flowcharts illustrated in <FIG>, <FIG>, <FIG>, and <FIG> may be performed by a not-illustrated plurality of CPUs or apparatuses in a distributed manner. The same applies to the sequences of <FIG> and <FIG>.

The embodiment has been described in detail. However, an embodiment of the present invention can take various forms such as a system, an apparatus, a method, a program, and a recording medium (storage medium). Specifically, an embodiment of the present invention may be applied to a system including a plurality of devices (such as a host computer, an interface device, an imaging apparatus, and a web application), or to an apparatus including a single device.

According to an embodiment of the present invention, a communication apparatus controlling a network including a plurality of base stations can control establishment of a plurality of links when the base stations establish the links therebetween.

Claim 1:
A control apparatus (<NUM>) for controlling an inter-access-point network (<NUM>) including two or more access points, the apparatus comprising:
communication means (<NUM>) configured to communicate with the two or more access points including a first access point (<NUM>) and a second access point (<NUM>), wherein each of the two or more access points has a function of constructing a wireless local area network, WLAN, and wherein the second access point (<NUM>) is connected to a WLAN network constructed by the first access point;
control means (<NUM>) configured to control the inter-access-point network (<NUM>); and
the control apparatus (<NUM>) being characterised in that:
the control means (<NUM>) is configured to control at least either one of the first access point (<NUM>) and the second access point (<NUM>) to establish a plurality of WLAN links to be used for communication between the first access point (<NUM>) and the second access point (<NUM>), by transmitting a predetermined message to the at least either one of the first access point (<NUM>) and the second access point (<NUM>), and wherein a WLAN link in the plurality of WLAN links is associated with a first frequency band that is different from a second frequency band with which another WLAN link in the plurality of WLAN links is associated.