Communication device, control method, and storage medium

Abstract

A communication apparatus, a control method, and a storage medium are provided. A communication apparatus compliant with IEEE 802.11 series standards is capable of multi-link communication with a plurality of other communication apparatuses using a plurality of links having different frequency channels. The communication apparatus generates, for each of the plurality of links, a key for encrypting a frame to be communicated, receives, from a first communication apparatus among the plurality of other communication apparatuses, a notification indicating disconnection or suspension of one or more of the plurality of links, confirms, in a case where the notification is received, a communication state between the plurality of other communication apparatuses and the communication apparatus via the plurality of links, and determines, based on a result of the confirmation, whether to regenerate the key for each of the plurality of links.

Description

Technical Field

[0001] This invention generally relates to communication devices, control methods, and storage media, and more particularly to wireless communication technology. Background Technology

[0002] With the increasing volume of data communication in recent years, the development of wireless local area network (LAN) communication technology has also been ongoing. The IEEE 802.11 series of standards is known as the main standard for wireless LANs. The IEEE 802.11 series of standards includes standards such as IEEE 802.11a / b / g / n / ac / ax. For example, IEEE 802.11ax is a standard for a technology that uses Orthogonal Frequency Division Multiple Access (OFDMA) to improve communication speed under congested conditions while achieving a peak throughput of up to 9.6 gigabits per second (Gbps) (Japanese Patent Application Publication No. 2018-50133).

[0003] A task force was created to study IEEE 802.11be (its successor standard) with the aim of further improving throughput, frequency utilization, and communication latency. One issue being investigated in IEEE 802.11be is the establishment of multiple links between an access point (AP) and a station (STA) in a frequency band such as 2.4 GHz, enabling multi-link communication, i.e., simultaneous communication. Another issue involves the possibility that, due to hardware limitations of wireless communication equipment, an AP or STA, while transmitting on a predetermined link, cannot receive on other links.

[0004] Wireless LAN data frames are typically transmitted in an encrypted state. For encryption, a pairwise ephemeral key (PTK) is used when data is transmitted one-to-one, while a group ephemeral key (GTK) or a group key is used when data is transmitted via multicast. These keys are managed differently. A PTK is managed on a per-communication-device basis and is shared only by the device performing the one-to-one communication. For a GTK, a GTK is generated for each link. Furthermore, due to this characteristic, the GTK is shared by all devices joining the network formed via these links. Moreover, the GTK can be updated by the access point (AP).

[0005] Next, consider the following scenario: a STA leaves a network established by an AP, while the AP maintains the network. In this case, if the AP does not update the GTK, the STA that left the network can still read multicast frames sent by the AP, even though it will not rejoin the network. Therefore, for the current standard, it is recommended that the AP update the GTK only after confirming that the STA has left the network.

[0006] This method of updating GTK can be applied to multi-link communication and can maintain the confidentiality of data frame transmission in multi-link communication.

[0007] On the other hand, in multi-link communication, there may be situations where only one or more links disconnect while others remain connected. Additionally, depending on the communication environment, frequent link switching may be expected. In this case, it's conceivable that devices whose links remain connected or switched, despite no change in their physical state, would require frequent GTK updates. However, for devices connected via multiple links, it's conceivable that when communication with one or more links is interrupted, the device can maintain its connection to the AP via other links, meaning there's no need to update the GTK. Summary of the Invention

[0008] The present invention aims to provide a technique for preventing unnecessary group key updates in multi-link communication.

[0009] According to one aspect of the present invention, a communication device conforming to the IEEE 802.11 series of standards is provided, the communication device being capable of multi-link communication with multiple other communication devices using multiple links with different frequency channels, the communication device comprising: a key control unit for generating a key for encrypting frames to be communicated for each of the multiple links; a receiving unit for receiving from a first communication device among the multiple other communication devices a notification indicating the disconnection or suspension of one or more of the multiple links; a confirmation unit for performing confirmation of the communication status between the multiple other communication devices and the communication device via the multiple links upon receiving the notification; and a determining unit for determining, based on the result of the confirmation, whether to regenerate the key for each of the multiple links.

[0010] According to another aspect of the present invention, a control method for a communication device conforming to the IEEE 802.11 series of standards is provided, the communication device being capable of multi-link communication with multiple other communication devices using multiple links with different frequency channels, the control method comprising: generating, for each of the multiple links, a key for encrypting frames to be communicated; receiving, from a first communication device among the multiple other communication devices, a notification indicating that one or more of the multiple links are disconnected or suspended; upon receiving the notification, performing an acknowledgment of the communication status between the multiple other communication devices and the communication device via the multiple links; and, based on the result of the acknowledgment, determining whether to regenerate the key for each of the multiple links.

[0011] Other features of the invention will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0012] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the invention and, together with the textual description, serve to explain the principles of the invention.

[0013] Figure 1 This is a diagram illustrating an example construction of a wireless communication system.

[0014] Figure 2 This is a diagram illustrating an example of the hardware construction of a communication device.

[0015] Figure 3 This is a diagram illustrating an example of the functional structure of a communication device.

[0016] Figure 4A and Figure 4B A flowchart of the process performed by AP MLD is shown.

[0017] Figure 5 This is a diagram illustrating an example of a frame indicating a switch to another link after one or more links are disconnected in multi-link communication. Detailed Implementation

[0018] The embodiments will be described in detail below with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the invention. Several features are described in the embodiments, but the invention is not limited to all of these features; rather, these features can be appropriately combined. Furthermore, in the drawings, the same or similar parts are given the same reference numerals, and redundant descriptions thereof are omitted.

[0019] In the following text, STA devices capable of multi-link communication are referred to as Station Multi-Link Devices (STA MLD), while AP devices capable of multi-link communication are referred to as Access Point Multi-Link Devices (AP MLD).

[0020] Construction of wireless communication system

[0021] Figure 1 An example configuration of a wireless communication system according to this embodiment is shown. The system 100 includes communication devices 101, 102, and 103. Communication devices 102 and 103 (hereinafter referred to as station / terminal devices (STA) 102 and STA 103) are STA MLDs with network joining capabilities. Communication device 101 (hereinafter referred to as access point (AP)) 101 is an AP MLD with network forming capabilities. AP 101 is capable of communicating with STA 102 and STA 103.

[0022] AP 101, STA 102, and STA 103 are each capable of wireless communication compliant with the IEEE 802.11be (Extreme High Throughput (EHT)) standard. AP 101, STA 102, and STA 103 can communicate at frequencies including 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. The frequency bands used by the communication devices are not limited to these, and different frequency bands can be used, for example. Furthermore, AP 101, STA 102, and STA 103 can use bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz. The bandwidths used by the communication devices are not limited to these, and different bandwidths, such as 240 MHz and 4 MHz, can be used, for example.

[0023] The AP 101 enables multi-user (MU) communication, where signals from multiple users are multiplexed via OFDMA communication conforming to the IEEE 802.11be standard. In OFDMA communication, a portion of the allocated frequency band (Resource Unit (RU)) is allocated to each STA / STA MLD in a non-overlapping manner, and the carriers for each STA / STA MLD are orthogonal to each other. Therefore, the AP MLD can communicate in parallel with the STA / STA MLD within a specified bandwidth.

[0024] Note that in this example, AP 101, STA 102, and STA 103 are compatible with the IEEE 802.11be standard, but are also compatible with standards prior to IEEE 802.11be. Specifically, AP 101, STA 102, and STA 103 are compatible with at least one of the IEEE 802.11a / b / g / n / ac / ax standards. In addition to the IEEE 802.11 family of standards, AP 101, STA 102, and STA 103 are also compatible with other standards such as Bluetooth (registered trademark), Near Field Communication (NFC), Ultra Wideband (UWB), Purple Bee, Multi-Band OFMA Alliance (MBOA), etc. UWB includes Wireless USB, Wireless 1394, WiNET, etc. Furthermore, AP 101, STA 102, and STA 103 are compatible with wired communication standards such as wired LAN.

[0025] Specific examples of AP 101 include, but are not limited to, wireless LAN routers, personal computers (PCs), etc. Furthermore, AP 101 can be an information processing device, such as a radio frequency chip capable of wireless communication compliant with the IEEE 802.11be standard. Similarly, specific examples of STA 102 and STA 103 include, but are not limited to, cameras, tablets, smartphones, PCs, mobile phones, camcorders, headsets, etc. Moreover, STA 102 and STA 103 can be information processing devices, such as radio frequency chips capable of wireless communication compliant with the IEEE 802.11be standard.

[0026] AP 101 communicates with STA 102 and STA 103 via multi-link communication (e.g., simultaneous communication via multiple links) through links established via multiple frequency channels. In the IEEE 802.11 series of standards, the bandwidth of each frequency channel is defined as 20MHz. Here, the frequency channel is defined by the IEEE 802.11 series of standards, which define multiple frequency channels in various frequency bands including 2.4GHz, 5GHz, 6GHz, and 60GHz. Note that in the case of a single frequency channel, bandwidths exceeding 40MHz can be used via channel bonding of adjacent frequency channels.

[0027] In this embodiment, for example, AP 101 can establish link 104a via a first frequency channel in the 2.4 GHz band and communicate with STA 102. Simultaneously, STA 102 can establish link 104b via a second frequency channel in the 5 GHz band and communicate with AP 101. In this case, STA 102 performs multi-link communication, where link 104b and link 104a remain parallel. In this way, by AP 101 using multiple frequency channels to establish multiple links with STA 102 (multi-link), the communication throughput with STA 102 can be improved. Similarly, by STA 103 forming links 105a and 105b with AP 101, communication quality can be improved.

[0028] Note that in multi-link communication, multiple links in different frequency bands can be established. For example, in addition to link 104a in the 2.4 GHz band and link 104b in the 6 GHz band, AP 101 and STA 102 can also establish other links in the 5 GHz band. Alternatively, links can be established via different channels included in the same frequency band. For example, AP 101 and STA 102 can establish a six-channel link in the 2.4 GHz band as link 104a, and a one-channel link in the 2.4 GHz band as link 104b.

[0029] Furthermore, links within the same frequency band and links in different frequency bands can coexist. For example, in addition to the six-channel link 104a in the 2.4GHz band, AP 101 and STA 102 can also establish one channel link 104b in the 2.4GHz band and 149 other channel links in the 5GHz band. By establishing multiple connections at different frequencies between AP 101 and STA 102, communication with STA 102 can be established on other frequency bands in the event of congestion in one band. This prevents reduced throughput and communication latency in communication with STA 102.

[0030] For each link, a link ID (hereinafter referred to as the link ID) is assigned to the network identifier formed by that link. For example, consider STA 102 and STA 103 joining the 2.4GHz network in a network formed by AP 101. If the links formed by STA 102 and STA 103 with AP 101 correspond to links 104a and 105a respectively, the common link ID assigned to these links is 1. Similarly, if STA 102 and STA 103 join the 5GHz network and the links formed here correspond to links 104b and 105b respectively, the link ID assigned to these links is 2. These link ID values ​​are examples, and different values ​​may be assigned in different cases, or link IDs may be assigned to each formed link.

[0031] Notice, Figure 1 System 100 is constructed with one AP MLD and two STA MLDs. However, the number and arrangement of AP MLDs and STA MLDs are not limited to this construction. For example, besides Figure 1 In addition to the existing configuration, other STA MLDs can also be provided. In this case, the frequency band, number of links, and frequency bandwidth of each established link can be arbitrarily configured.

[0032] In multi-link communication, a single data stream can be divided and transmitted to a partner device via multiple links between AP 101 and STA 102, or between AP 101 and STA 103. Furthermore, AP 101 and STA 102, and AP 101 and STA 103, can be configured for multiple-input multiple-output (MIMO) communication. In this case, AP 101, STA 102, and STA 103 include multiple antennas, transmitting different signals from the antennas using the same frequency channel. The receiving side uses antennas to simultaneously receive all signals arriving from multiple data streams, separates the signals from these data streams, and decodes these signals. In this way, compared to non-MIMO communication, AP 101, STA 102, and STA 103 can communicate a larger amount of data in the same amount of time. Moreover, in multi-link communication, AP 101, STA 102, and STA 103 can perform MIMO communication on one or more links.

[0033] AP 101 multicasts group addressing frames to STA 102 and STA 103, which have joined the formed network. Group addressing frames include, for example, group addressing data frames, group addressing management frames, beacon frames, etc. AP 101 sends group address frames for each network. For example, in the case where a network with link ID 1 is formed by links 104a and 105a, AP 101 uses the network with link ID 1 to send group addressing frames. Similarly, AP 101 can use networks with different link IDs to send group addressing frames. These group addressing frames can be the same or different.

[0034] AP and STA construction

[0035] Figure 2 This diagram illustrates an example of the hardware configuration of AP 101 according to this embodiment. As an example of the hardware configuration, AP 101 includes a storage unit 201, a control unit 202, a functional unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207. Note that multiple antennas may be present. Additionally, note that STA 102 and STA 103 may have hardware configurations similar to those of AP 101.

[0036] Storage unit 201 comprises one or more memories (such as read-only memory (ROM) or random access memory (RAM)) and stores computer programs for performing various operations, as well as various information such as communication parameters for wireless communication. Note that in addition to ROM, RAM, or other such memories, storage media such as floppy disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, DVDs, etc., can also be used as storage unit 201. Furthermore, storage unit 201 may be equipped with multiple memories.

[0037] The control unit 202 is composed of one or more processors (such as a central processing unit (CPU), a microprocessor unit (MPU), etc.) and completely controls the AP 101 by executing a computer program stored in the storage unit 201. Note that the control unit 202 can completely control the AP 101 through cooperation between the computer program stored in the storage unit 201 and the operating system (OS). Furthermore, the control unit 202 generates data and signals (radio frequency frames) for transmission via communication with other communication devices. Moreover, the control unit 202 may be equipped with multiple processors, such as multi-core processors, and completely control the AP 101 through multiple processors.

[0038] Furthermore, the control unit 202 controls the function unit 203 and performs predetermined processes such as wireless communication, camera recording, printing, and projection. The function unit 203 is hardware that enables the AP 101 to perform predetermined functions.

[0039] Input unit 204 receives various operations from the user. Output unit 205 outputs to the user, for example, via a monitor screen or a speaker. In this example, the output via output unit 205 may correspond to displaying on a monitor screen, outputting audio via a speaker, outputting vibration, etc. Note that input unit 204 and output unit 205 may be implemented as a single module, for example, via a touch panel. Moreover, input unit 204 and output unit 205 may be integrally formed with each STA 102, or they may be formed separately.

[0040] Communication unit 206 performs control of wireless communication conforming to the IEEE 802.11be standard. In addition to the IEEE 802.11be standard, communication unit 206 can also perform control of wireless communication conforming to other IEEE 802.11 series standards, and can perform wired communication control using wired LAN or similar connections. Communication unit 206 controls antenna 207 and transmits and receives signals for wireless communication generated by control unit 202.

[0041] Note that if AP 101 is compatible with NFC, Bluetooth, and other standards in addition to the IEEE 802.11be standard, AP 101 can perform wireless communication control compliant with these standards. Furthermore, if AP 101 can perform wireless communication compliant with multiple standards, it can be configured such that a communication unit and antenna compatible with each communication standard are provided separately. AP 101 transmits data such as image data, document data, and video data via communication unit 206. Note that antenna 207 can be formed separately from communication unit 206, or it can be formed as a single module together with communication unit 206.

[0042] Antenna 207 is an antenna capable of communication in frequency bands including 2.4 GHz, 5 GHz, 6 GHz, etc. In this embodiment, AP 101 includes one antenna, but multiple (e.g., three) antennas can be provided. Moreover, different antennas can be provided for each frequency band. Furthermore, if AP 101 includes multiple antennas, a communication unit 206 can be provided corresponding to each antenna.

[0043] Figure 3 This diagram illustrates an example of the functional configuration of AP 101 according to this embodiment. As an example of functional configuration, AP 101 includes a wireless LAN control unit 301, a frame generation unit 302, a connection management unit 303, a GTK control unit 304, and a user interface (UI) control unit 305. Additionally, note that STA 102 and STA 103 may have functional configurations similar to those of AP 101.

[0044] The wireless LAN control unit 301 may include a program for performing control of sending (receiving) radio frequency signals to (from) other wireless LAN devices. The wireless LAN control unit 301 sends and receives frames generated by the frame generation unit 302 via a communication unit 206 and an antenna 207 conforming to the IEEE 802.11 series standards, and performs wireless LAN communication control. Note that the number of wireless LAN control units is not limited to one, but may be two, three, or more.

[0045] The frame generation unit 302 generates radio frequency frames that will be transmitted by the wireless LAN control unit 301. The content of the radio frequency frames generated by the frame generation unit 302 can be stored in the storage unit 201. Figure 2 The settings in the UI control unit 305 can be used to limit the behavior. Alternatively, the content can be changed via user settings. Information from the generated frame is sent to the wireless LAN control unit 301, and then transmitted to the communication partner device via the communication unit 206 and antenna 207.

[0046] As a result of frame switching performed by the wireless LAN control unit 301, the connection management unit 303 confirms / manages the connection status / communication status of each link with partner devices (e.g., other communication devices). In this example, the communication status / connection status, or the state of communication, represents the communication status between a communication device (e.g., AP 101) capable of multi-link communication with multiple other communication devices (or partner devices) via multiple links and those other communication devices. In other words, the communication status can correspond to one or more different communication states between the partner device and AP 101: such as whether the partner device and AP 101 are communicating via the same link (still connected) and / or communicating via a different link for the first time (new connection) and / or the link between the partner device and AP 101 will be disconnected or suspended (disconnected).

[0047] The GTK control unit 304 acts as a key controller to perform GTK-related controls. For example, the GTK control unit 304 generates and manages the GTK used (applications) on each link. Additionally, the GTK control unit 304 determines whether to regenerate (update) the GTK based on the confirmation results (connection status / communication status of each link) obtained from the connection management unit 303. If regeneration is determined, the GTK control unit 304 regenerates the GTK. The GTK control unit 304 exchanges the (re)generated GTK with other communication devices via the wireless LAN control unit 301.

[0048] The UI control unit 305 generates control signals based on user operations (user settings) on the input unit 204 and sends these signals to each component. Furthermore, the UI control unit 305 performs control over various outputs of the output unit 205.

[0049] AP MLD processing flow

[0050] Figure 4A and Figure 4B A flowchart illustrating the processes performed by the AP MLD is shown. Specifically, Figure 4A and Figure 4B The process flow executed by AP MLD to determine whether to update, generate, or discard GTK is shown.

[0051] When multi-link communication (multi-link connection established) is initiated between the STA MLD and AP MLD, and a notification is received from the STA MLD to suspend or disconnect (suspend / disconnect) one or more or all links, the multi-link communication begins. Figure 4A and Figure 4B Processing. Alternatively, processing can begin when a notification is sent from the AP to a specific STA MLD to suspend or disconnect one or more or all links. Figure 4A and Figure 4B The former is shown in the image.

[0052] here, Figure 4A and Figure 4B The flowchart will be described using the above example of processing performed by AP 101. The control program stored in storage unit 201 can be executed by the control unit 202 of AP 101 to perform calculations on information and process and control various hardware components, thereby realizing the processing of the flowchart.

[0053] The wireless LAN control unit 301 of AP 101 first receives a frame (notification) from the currently connected STA MLD (STA 102 in this specification) instructing the suspension or disconnection of connections with one or more or all links (step S401). This frame can be a deauthentication frame or a deassociation frame as defined in IEEE 802.11. Alternatively, these frames can be used as frames for multi-link communication extensions. Alternatively, the frame can be a frame used to switch (transition) to connections with other links after disconnection from one or more links. Such as Figure 5 The frames shown can be used to switch the connection link to another link.

[0054] Figure 5 This is a diagram illustrating an example of a frame that indicates a switch to another link in multi-link communication. Figure 5 The frames shown are frames extended from those defined in IEEE 802.11.

[0055] Figure 5 The fields and subfields in frame 500 shown, from first to last, include frame control field 501, duration field 502, A1 field 503, A2 field 504, A3 field 505, sequence control field 506, HT control field 507, multilink element field 508, and FCS field 509. Note that this frame is described as a management frame type as defined in IEEE 802.11, but it could be a control frame type. In this case, for example, A3 field 505, sequence control field 506, and HT control field 507 may be omitted.

[0056] Frame control field 501 indicates the type of frame. Whether the frame type is a deauthentication frame or a deassociation frame can be indicated by the value (not shown) of the type subfield or subtype subfield included in frame control field 501. Any type of frame can be used as the frame used in step S401. Alternatively, the frame can be redefined as a frame indicating a link switch when the value of the type subfield is 00 and the value of the subtype subfield is 1111. Furthermore, the frame can be used as an action frame with a type subfield of 00 and a subtype subfield of 1101, and elements indicating channel switching or disconnection of one or more links can be prepared within this frame.

[0057] The multilink element field 508 indicates an example of an element assigned to the frame (including within the frame). The multilink element field 508 includes an element ID subfield 510, a length subfield 511, an element ID extension subfield 512, a multilink control subfield 513, a previous link ID subfield 514, and a next link ID subfield 515. Note that when the frame type is an action frame, a type subfield can be used instead of the element ID subfield 510 and length subfield 511 to represent the content of the subfield. Furthermore, not all subfields of the multilink element field 508 are required. For example, only the previous link ID subfield 514 or only the next link ID subfield 515 may be included. Alternatively, the multilink element field 508 can be constructed by combining the above subfields with one or more other subfields.

[0058] The specific value of the element ID subfield 510 is, for example, 255, and the value of the element ID extended subfield 512 is, for example, 15. This indicates that the element assigned to the frame is a multilink element. The multilink control subfield 513 indicates which operation among the multilink-related operations is being performed by the assigned multilink element. For example, the multilink control subfield 513 includes a multilink type subfield 516, and can indicate a change in the connection link by setting the value to 0x4. Alternatively, setting the value to 0x5 can indicate a link disconnection.

[0059] The Previous Link ID subfield 514 indicates the link ID of the link to which the connection was suspended or disconnected. The Next Link ID subfield 515 indicates the link ID of the new link that replaces the disconnected link. For example, when STA 102 suspends the connection with the link with link ID 2 and establishes a new connection with the network consisting of the link with link ID 3, the value of the Previous Link ID subfield 514 is 2, and the value of the Next Link ID subfield 515 is 3. Alternatively, when STA 102 only disconnects the connection with the link with link ID 2, the value of the Next Link ID subfield 515 can be 0 or no Next Link ID subfield 515 can be assigned.

[0060] Back Figure 4A and Figure 4B The following processing (starting from step S402) is performed for each network (i.e., link ID) formed by AP 101. When a frame indicating a suspension or disconnection of the link is received from STA 102 in step S401, the connection management unit 303 of AP 101 determines whether the frame indicates a suspension / disconnection of the connection to all links connected to STA 102 (step S402).

[0061] If the received frame indicates that the connection to all links connected to STA 102 is suspended / disconnected ("Yes" in step S402), the process proceeds to step S403. In step S403, the connection management unit 303 of AP 101 then determines whether there are other STA MLDs, other than STA 102, communicating with the network (NW) formed by the target link (the link with link ID x) (step S403). In this step, it can be determined whether other STA MLDs are using links other than the link that STA 102 requested to be suspended / disconnected to communicate with AP 101. If there are no other STA MLDs communicating with the network formed by the link with link ID x (using the link with link ID x) ("No" in step S403), the GTK control unit 304 discards the group key of that link (step S407). If there are other STA MLDs communicating with the network formed by the link with link ID x ("Yes" in step S403), the process proceeds to step S404. In step S404, the connection management unit 303 then determines whether the network formed by the link with link ID x is the network that STA 102 (STA MLD that issued the notification in step S401) is communicating with (joining). In other words, the connection management unit 303 determines whether the link with link ID x is the link that STA 102 requested to be suspended / disconnected in step S401 (the suspended / disconnected link).

[0062] When STA 102 is communicating with the network formed by the link with link ID x ("Yes" in step S404), the GTK control unit 304 of AP 101 regenerates (updates) the group key for the link with link ID x (step S405). Furthermore, the wireless LAN control unit 301 of AP 101 performs a group key exchange to send the updated and newly generated group key (step S406).

[0063] If STA 102 does not communicate with the network formed by the link with link ID x (No in step S404), the process proceeds to step S408. In step S408, the connection management unit 303 of AP 101 then determines whether the network formed by the link with link ID x is a network that STA 102 (the STA MLD that issued the notification in step S401) previously communicated with (joined) in the past. If STA 102 has not previously communicated with the network formed by the link with link ID x (No in step S408), the GTK control unit 304 of AP 101 maintains the group key for the link with link ID x without updating the group key (step S415).

[0064] If STA 102 previously communicated with the network formed by the link with link ID x ("Yes" in step S408), the connection management unit 303 of AP 101 determines whether the group key has been updated for that link after STA 102 leaves the network (step S409). If the group key has been updated ("Yes" in step S409), the GTK control unit 304 of AP 101 maintains the group key for the link with link ID x without updating it (step S415). If the group key has not been updated ("No" in step S409), the GTK control unit 304 of AP 101 updates the group key for the link with link ID x (step S405), and the wireless LAN control unit 301 performs a group key exchange (step S406).

[0065] Note that AP 101 can perform steps S408 and S409 together. In other words, the connection management unit 303 can confirm whether STA 102 has joined the network formed by the link with link ID x since the last update of the group key. If STA 102 has not joined, GTK control unit 304 can maintain the group key. If STA 102 has joined, GTK control unit 304 can update the group key.

[0066] Next, the processing will be described in the case where, after determination via step S402, the received frame indicates that the connection to all links to which STA 102 is connected is not suspended or disconnected ("No" in step S402). For example, this situation corresponds to situations such as STA 102 suspending or disconnecting its connection to a link and reconnecting to other links, and situations such as STA 102 suspending or disconnecting its connection to a link and continuing its connection to other links, and in this case, the processing proceeds to step S410. AP 101's connection management unit 303 confirms whether the STA (or STA MLD) is newly connected to the network (NW) formed by the target link (the link with link ID x) for the first time (step S410).

[0067] If no new STA connection is established ("No" in step S410), the GTK control unit 304 maintains the group key for the link with link ID x (step S416). If a new STA connection is established ("Yes" in step S410), the connection management unit 303 of AP 101 then confirms whether the newly connected STA is the first STA to connect to the network (step S411). That is, it confirms whether other STAs have already connected to the network formed by the link with link ID x. If the newly connected STA is not the first STA to connect to the network ("No" in step S411), the wireless LAN control unit 301 of AP 101 exchanges the pre-generated group key (step S414). If the newly connected STA is the first STA to connect to the network ("Yes" in step S411), the GTK control unit 304 of AP 101 generates a group key for the link with link ID x (step S412), and the wireless LAN control unit 301 performs a group key exchange (step S413).

[0068] AP 101 performs the above processing for each network formed (i.e., for each link ID). The processing ends when the processing for all link IDs has been completed ("Yes" in step S417). Note that in the above flowchart, the processing in step S404 can be omitted. For example, if STA 102 uses a link to connect to AP 101 and requests to pause or disconnect the connection to that link ("Yes" in step S402), and other STA MLDs are communicating with the network formed by that link ("Yes" in step S403), the processing can proceed to step S405 and AP 101 can regenerate the group key.

[0069] Next, we will describe based on Figure 4A and Figure 4B An example of processing. The following will refer to... Figure 1 The communication system shown in the figure.

[0070] Example 1

[0071] In Example 1, AP 101 forms a network with six channels in the 2.4 GHz band and link ID 1, a network with 36 channels in the 5 GHz band and link ID 2, and a network with 5.955 GHz in the 6 GHz band and link ID 3. STA 102 joins the network with link ID 1 via link 104a and joins the network with link ID 2 via link 104b. STA 103 joins the network with link ID 1 via link 105a and joins the network with link ID 3 via link 105b.

[0072] Taking a state (e.g., a communication state) where STA 102 leaves the network with link ID 1 and joins the network with link ID 3 as an example. In other words, in this example, STA 102 disconnects from the link with link ID 1 and connects to the link with link ID 3. Figure 4A (No in step S402).

[0073] This means that, in this case, a STA MLD that joined the network formed by the link with link ID 1 leaves the network. However, because STA 102 continues to connect to AP 101 via a different link (i.e., the link with link ID 2), AP 101 maintains the group key for the link with link ID 1 ("No" in step S410, step S416).

[0074] Furthermore, since STA MLD has not newly connected to or disconnected from the network formed by the link with link ID 2, AP101 maintains the group key for the link with link ID 2 ("No" in step S410, step S416).

[0075] Furthermore, STA 102 joins the network formed by the link with link ID 3 ("Yes" in step S410, "No" in step S411). STA 103 joins the network formed by the link with link ID 3, and here, a group key exchange is performed between AP 101 and STA 102 (step S414).

[0076] Example 2

[0077] In Example 2, AP 101 forms a network with 6 channels in the 2.4 GHz band and link ID 1, a network with 36 channels in the 5 GHz band and link ID 2, and a network with 5.955 GHz in the 6 GHz band and link ID 3. STA 102 joins the network with link ID 1 via link 104a and joins the network with link ID 2 via link 104b. STA 103 joins the network with link ID 1 via link 105a and joins the network with link ID 3 via link 105b.

[0078] Take, for example, STA 102 leaving all the networks it has joined in this state. In other words, in this example, STA 102 disconnects from the link with link ID 1 and the link with link ID 2 ("Yes" in step S402).

[0079] This means that, in this situation, one STA MLD that joined the network formed by the link with link ID 1 leaves the network. Furthermore, all connections between AP 101 and STA 102 are severed. However, STA 103 joins the network formed by the link with link ID 1 ("Yes" in step S403, "Yes" in step S404). Therefore, AP 101 updates (regenerates) the group key for the link with link ID 1 (step S405). Then, AP 101 and STA 103 perform a group key exchange using the updated group key (step S406).

[0080] Furthermore, all STA MLDs that have joined the network formed by the link with link ID 2 leave the network (No in step S403). Therefore, AP 101 discards the stored group key for the link with link ID 2 (step S407).

[0081] Furthermore, STA MLD has not newly connected to or disconnected from the network formed by the link with link ID 3. Moreover, in this example, STA 102 has not previously joined the network formed by the link. Therefore, AP 101 maintains the group key for the link with link ID 3 ("Yes" in step S403, "No" in step S404, "No" in step S408, step S415).

[0082] Example 3

[0083] In Example 3, AP 101 forms a network with 6 channels in the 2.4 GHz band and link ID 1, a network with 36 channels in the 5 GHz band and link ID 2, and a network with 5.955 GHz in the 6 GHz band and link ID 3. STA 102 joins the network with link ID 1 via link 104a and joins the network with link ID 2 via link 104b. STA 103 joins the network with link ID 1 via link 105a and joins the network with link ID 2 via link 105b.

[0084] Taking STA 102 as an example, in this state, STA 102 leaves the network with link ID 2 and joins the network with link ID 3. In other words, in this example, STA 102 disconnects from the link with link ID 2 and connects to the link with link ID 3. Figure 4A (No in step S402).

[0085] In this case, because STA MLD has not newly connected to or disconnected from the network formed by the link with link ID 1, AP 101 requests the link maintenance group key for link ID 1 ("No" in step S410, step S416).

[0086] This means that, in this case, a STA MLD that joined the network formed by the link with link ID 2 leaves the network. However, because STA 102 continues to connect to AP 101 via a different link (i.e., the link with link ID 2), AP 101 maintains the group key for the link with link ID 2 ("No" in step S410, step S416).

[0087] Furthermore, at the network formed by the link with link ID 3, STA MLD joins the network from a state where STA MLD had not joined ("Yes" in step S410, "Yes" in step S411). Therefore, AP 101 generates a new group key for the link with link ID 3 (step S412) and performs a group key exchange with STA 102 (step S413).

[0088] Through these operations, AP 101 can reduce the number of times the group key is updated and maintain the state that STA MLDs that are not currently joined to the network do not know the group key.

[0089] Note that in the above embodiment, AP 101 forms three networks operating via multiple links. However, the number of networks is not limited to three. For example, there may be two, four, or more networks.

[0090] Additionally, in the above embodiments, AP 101 is used as an AP. However, if AP 101 is a device used to manage group keys, AP 101 may not be used as an AP. For example, when multiple STAs are connected, AP 101 may be considered one of the STAs. For example, AP 101 may be a device operating as a Wi-Fi Direct Group Owner (GO).

[0091] Other embodiments

[0092] Embodiments of the invention can also be implemented by a computer that reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium (also more fully referred to as a "non-transitory computer-readable storage medium") to perform one or more functions in the above embodiments, and / or includes one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing one or more functions in the above embodiments. Furthermore, embodiments of the invention can be implemented using a method by which the computer of the system or device, for example, reads and executes the computer-executable instructions from the storage medium to perform one or more functions in the above embodiments, and / or controls the one or more circuits to perform one or more functions in the above embodiments. The computer may include one or more processors (e.g., central processing unit (CPU), microprocessor unit (MPU)) and may include separate computers or a network of separate processors to read and execute the computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, a hard disk, random access memory (RAM), read-only memory (ROM), the memory of a distributed computing system, or an optical disc (such as a compact disc (CD), a digital versatile optical disc (DVD), or a Blu-ray disc (BD)). TM One or more of the following: flash memory devices and memory cards.

[0093] The embodiments of the present invention can also be implemented by providing software (programs) that perform the functions of the above embodiments to a system or device via a network or various storage media, and the computer or central processing unit (CPU) or microprocessor unit (MPU) of the system or device reads out and executes the program.

[0094] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The appended claims should be interpreted in the broadest possible sense to encompass all such variations and equivalent structures and functions.

Claims

1. A communication device conforming to the IEEE 802.11 standard series, the communication device being capable of establishing multiple links with multiple other communication devices by using different frequency channels, the communication device comprising: A key control unit generates GTKs for each of the plurality of links to encrypt the frames to be communicated on each of the plurality of links; as well as The receiving unit receives from a first communication device among the plurality of other communication devices a first notification instructing the disconnection or suspension of a subset of the plurality of links, or a second notification instructing the disconnection or suspension of all links among the plurality of links. Wherein, when the communication device is connected to the first communication device and the second communication device using a first link and a second link, the key control unit updates the GTK for the first link and the GTK for the second link in response to receiving a second notification from the first communication device instructing the disconnection or suspension of the first link and the second link, and When the communication device is connected to the first communication device and the second communication device by using the first link and the second link, the key control unit does not update the GTK for the first link and the GTK for the second link in response to receiving a first notification from the first communication device indicating that the first link should be disconnected or suspended.

2. The communication device according to claim 1, further comprising: A transmitting unit is configured to send an updated GTK to a second communication device connected to the communication device via the first and second links when the key control unit updates the GTK for the first link and the GTK for the second link.

3. The communication device according to claim 2, wherein, When the communication device is connected to the first communication device only by using the first link and the second link, the key control unit does not update the GTK for the first link and the GTK for the second link in response to receiving a second notification from the first communication device instructing the disconnection or suspension of the first link and the second link.

4. The communication device according to claim 3, wherein, When the communication device is connected to the first communication device only by using the first link and the second link, the key control unit discards the first link and the GTK used for the second link in response to receiving a second notification from the first communication device instructing the disconnection or suspension of the first link and the second link.

5. The communication device according to claim 4, wherein, The first notification from the first communication device, indicating that the first link should be disconnected or suspended, also indicates that a connection should be established by using a third link.

6. The communication device according to claim 5, wherein, The first notification from the first communication device indicating that the first link is disconnected or suspended includes a multi-link element, and the multi-link element includes information indicating a link ID for the first link.

7. The communication device according to claim 1, wherein, The notification is a de-authentication frame or a de-association frame.

8. The communication device according to claim 1, wherein, The communication device is a communication device that operates as an access point.

9. The communication device according to claim 1, wherein, The communication device is a communication device that operates as a Wi-Fi Direct connected group owner.

10. A control method for a communication device conforming to the IEEE 802.11 standard series, the communication device being capable of establishing multiple links with multiple other communication devices by using different frequency channels, the control method comprising: For the multiple links, generate GTKs for encrypting the frames to be communicated on each of the multiple links; Receive a first notification from a first communication device among the plurality of other communication devices, instructing to disconnect or suspend a subset of the plurality of links, or a second notification instructing to disconnect or suspend all of the plurality of links; When the communication device is connected to the first communication device and the second communication device using a first link and a second link, in response to receiving a second notification from the first communication device indicating that the first link and the second link should be disconnected or suspended, the GTK for the first link and the GTK for the second link are updated, and When the communication device is connected to the first communication device and the second communication device by using the first link and the second link, the GTK for the first link and the GTK for the second link are not updated in response to receiving a first notification from the first communication device indicating that the first link is disconnected or suspended.

11. A computer-readable storage medium storing a program for causing a computer to perform the control method according to claim 10.

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