COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM

Abstract

To prevent unnecessary group key updates in Multi-Link communication.SOLUTION: A communication apparatus compliant with an IEEE 802.11 series standard is capable of performing Multi-Link communication with a plurality of other communication apparatuses using a plurality of links with different frequency channels. The communication apparatus generates a key for encrypting a frame to be communicated for each one of the plurality of links, receives, from a first communication apparatus from among the plurality of other communication apparatuses, a notification indicating disconnection or suspension of one or more links of the plurality of links, confirms a state of communication via the plurality of links between the plurality of other communication apparatuses and the communication apparatus in a case where the notification is received, and determines whether or not to re-generate the key for each one of the plurality of links on the basis of a result of the confirmation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to wireless communication technology. [Background technology]

[0002] With the increase in the amount of data being communicated in recent years, the development of communication technologies such as wireless LANs (Local Area Networks) is progressing. The IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard series is known as a major communication standard for wireless LANs. The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax. For example, IEEE 802.11ax standardizes a technology that uses OFDMA (Orthogonal Frequency Division Multiple Access) to achieve a high peak throughput of up to 9.6 gigabits per second (Gbps) as well as improve communication speeds under congested conditions (Patent Document 1).

[0003] A task group called IEEE802.11be was launched as a successor standard aiming to further improve throughput, frequency efficiency, and communication latency. IEEE802.11be considers multi-link communication, in which one AP (access point) and one STA (station) establish multiple links in frequency bands such as the 2.4GHz band and communicate simultaneously. In addition, due to hardware restrictions of wireless communication devices, APs and STAs that cannot receive on a given link while transmitting on another link in multi-link communication are being considered.

[0004] It is common for data frames in wireless LANs to be sent in an encrypted state. When sending data one-to-one, a Pairwise Transient Key (PTK) is used, and when sending data by multicast, a Group Transient Key (GTK), which is a group key, is used for encryption. These keys are managed differently. PTKs are managed on a per-communication device basis, and are shared only between devices that communicate one-to-one. On the other hand, one GTK is generated per link. Due to this nature, GTKs are shared by all devices that join a network built on a certain link. GTKs can also be updated by the AP. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-50133 A Summary of the Invention [Problem to be solved by the invention]

[0006] Now consider the case where one STA leaves a network formed by an AP, and the AP keeps the network itself alive. In this case, if the AP does not update the GTK, the STA that left the network will be able to read multicast frames sent by the AP, even though it is not participating in the network. Therefore, the current standard recommends that the AP update the GTK after confirming that the STA has left the network.

[0007] Such GTK updating can also be applied to multi-link communications, and confidentiality in data frame transmission can be maintained even in multi-link communications.

[0008] On the other hand, in multi-link communication, it is possible that only some links will be disconnected while other links will continue to be connected. Also, depending on the communication environment, it is expected that link switching will occur frequently. In such cases, devices that do not disconnect / switch links may end up in a situation where the GTK is updated frequently even though the situation has not changed. On the other hand, devices that connect via multi-link may not need to update the GTK even if communication on some links is interrupted, because connections to the AP will remain maintained on other links.

[0009] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique for preventing unnecessary updates of a group key in multi-link communication. [Means for solving the problem]

[0010] As one means for achieving the above object, the communication device of the present invention has the following configuration. 1st rule case series between multiple other communication devices in accordance with each Multiple links with different frequency channels Establish a communication device for encrypting a frame to be communicated for each of the plurality of links, Group Transient Key (GTK) a key control means for generating a key for a first one of the plurality of other communication devices; other From the communication device, part Indicates a broken or interrupted link 1. notification or a second notice indicating the disconnection or interruption of all of the links of said plurality of links. A receiving means for receiving the wherein, when the communication device is connected to the first other communication device and a second other communication device among the plurality of other communication devices via a first link and a second link, the key control means updates the GTK for the first link and the second link in response to receiving the second notification from the first other communication device indicating disconnection or interruption of the first link and the second link, and does not update the GTK for the first link and the second link in response to receiving the first notification from the first other communication device indicating disconnection or interruption of the first link. . Effect of the Invention

[0011] According to the present invention, it is possible to prevent unnecessary updates of a group key in multi-link communication. [Brief description of the drawings]

[0012] [Figure 1]FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 2 illustrates an example of a hardware configuration of a communication device. [Diagram 3] FIG. 2 illustrates an example of a functional configuration of a communication device. [Figure 4] 13 is a flowchart of a process executed by AP MLD. [Diagram 5] 13 shows an example of a frame indicating switching to another link after disconnecting some links in multi-link communication. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0014] In the following description, a STA device capable of performing multi-link communication is referred to as a STA MLD (Station Multi-Link Device), and an AP device capable of performing multi-link communication is referred to as an AP MLD (Access Point Multi-Link Device).

[0015] (Configuration of wireless communication system) 1 shows an example of the configuration of a wireless communication system according to this embodiment. This system 100 is configured to include communication devices 101, 102, and 103. The communication devices 102 and 103 (hereinafter, STAs (station / terminal devices) 102 and STA103) are STA MLDs that have a role of participating in a network. The communication device 101 (hereinafter, AP (access point) 101) is an AP MLD that has a role of constructing a network. The AP 101 is capable of communicating with the STAs 102 and 103.

[0016] Each of the AP101, STA102, and STA103 can perform wireless communication conforming to the IEEE802.11be (EHT (Extreme / Extremely High Throughput)) standard. The AP101, STA102, and STA103 can communicate at frequencies such as 2.4 Hz band, 5 GHz band, 6 GHz band, and 60 GHz band. The frequency band used by each communication device is not limited to this, and a different frequency band such as the 60 GHz band may be used. In addition, the AP101, STA102, and STA103 can communicate using bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz. The bandwidth used by each communication device is not limited to this, and a different bandwidth such as 240 MHz and 4 MHz may be used.

[0017] The AP 101 can realize multi-user (MU) communication by multiplexing signals from multiple users by performing OFDMA communication compliant with the IEEE802.11be standard. In OFDMA communication, a part of the divided frequency band (Resource Unit (RU)) is assigned to each STA / STA MLD so that they do not overlap, and the carrier waves for each STA / STA MLD are orthogonal. Therefore, the AP MLD can communicate in parallel with multiple STA / STA MLDs within the specified bandwidth.

[0018] In addition, the AP 101, the STA 102, and the STA 103 are described as being compatible with the IEEE 802.11be standard, but may also be compatible with a legacy standard that is a standard that precedes the IEEE 802.11be standard. Specifically, the AP 101, the STA 102, and the STA 103 may be compatible with at least one of the IEEE 802.11a / b / g / n / ac / ax standards. In addition to the IEEE 802.11 series standards, the AP 101, the STA 102, and the STA 103 may also be compatible with other communication standards such as Bluetooth (registered trademark), Near Field Communication (NFC), Ultra Wide Band (UWB), ZigBee, and Multi Band OFMA Alliance (MBOA). UWB includes wireless USB, wireless 1394, WiNET, and the like. The AP 101, the STA 102, and the STA 103 may also be compatible with a communication standard for wired communication such as wired LAN.

[0019] Specific examples of the AP 101 include, but are not limited to, a wireless LAN router and a personal computer (PC). The AP 101 may also be an information processing device such as a wireless chip capable of performing wireless communication conforming to the IEEE802.11be standard. Specific examples of the STAs 102 and 103 include, but are not limited to, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, and a headset. The STAs 102 and 103 may also be information processing devices such as a wireless chip capable of performing wireless communication conforming to the IEEE802.11be standard.

[0020] The AP 101, the STA 102, and the STA 103 perform multi-link communication by establishing links via multiple frequency channels. In the IEEE 802.11 series standard, the bandwidth of each frequency channel is defined as 20 MHz. Here, the frequency channel is a frequency channel defined in the IEEE 802.11 series standard, and in this standard, multiple frequency channels are defined in each of the 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz frequency bands. Note that a bandwidth of 40 MHz or more may be used in one frequency channel by bonding with adjacent frequency channels.

[0021] In this embodiment, for example, the AP 101 can establish a link 104a via a first frequency channel in the 2.4 GHz band with the STA 102 and communicate with it. In parallel with this, the STA 102 can establish a link 104b via a second frequency channel in the 5 GHz band with the AP 101 and communicate with it. In this case, the STA 102 executes multi-link communication to maintain the link 104b in parallel with the link 104a. In this way, the AP 101 can improve the throughput in the communication with the STA 102 by establishing multiple links (multi-links) using multiple frequency channels with the STA 102. Similarly, the STA 103 can improve the communication quality by establishing the link 105a and the link 105b with the AP 101.

[0022] In multi-link communication, multiple links of different frequency bands may be established. For example, the AP 101 and the STA 102 may establish another link in the 5 GHz band in addition to the link 104a in the 2.4 GHz band and the link 104b in the 6 GHz band. Alternatively, links may be established via multiple different channels included in the same frequency band. For example, the AP 101 and the STA 102 may establish a link of 6ch in the 2.4 GHz band as the link 104a, and in addition to this, a link of 1ch in the 2.4 GHz band as the link 104b.

[0023] Also, links with the same frequency band and links with different frequency bands may be mixed. For example, in addition to link 104a with 6ch in the 2.4GHz band, AP101 and STA102 may establish link 104b with 1ch in the 2.4GHz band and another link with 149ch in the 5GHz band. By establishing multiple connections with STA102 with different frequencies, even if one band is congested, AP101 can establish communication with STA102 with the other band, thereby preventing a decrease in throughput and communication delays in communication with STA102.

[0024] Each link is assigned identification information (hereinafter, Link ID) for each network that is constructed including the link. For example, consider a case where STA102 and STA103 join a 2.4 GHz network among the networks constructed by AP101. If the links that STA102 and STA103 have constructed with AP101 are respectively Link 104a and Link 105a, a common Link ID=1 is assigned to these links. Similarly, for example, if STA102 and STA103 join a 5 GHz network and the links constructed here are respectively Link 104b and Link 105b, a Link ID=2 is assigned to these links. This Link ID value is an example, and a different value may be assigned as the Link ID, or a Link ID may be assigned for each constructed link.

[0025] Although the system 100 in Fig. 1 is configured with one AP MLD and two STA MLDs, the number and arrangement of the AP MLD and STA MLD are not limited to this. For example, one STA MLD may be added to the configuration in Fig. 1. In this case, the frequency band of each link to be established, the number of links, and the frequency width are not important.

[0026] When performing multi-link communication, one piece of data may be divided and transmitted to a partner device via multiple links between AP101 and STA102 or between AP101 and STA103. AP101 and STA102, and AP101 and STA103 may be configured to perform MIMO (Multiple-Input and Multiple-Output) communication. In this case, AP101, STA102, and STA103 each have multiple antennas, and one transmits different signals from each antenna using the same frequency channel. The receiving side simultaneously receives all signals arriving from multiple streams using multiple antennas, and separates and decodes the signals of each stream. In this way, by performing MIMO communication, AP101, STA102, and STA103 can communicate more data in the same time compared to when not performing MIMO communication. AP101, STA102, and STA103 may also perform MIMO communication on some links when performing multi-link communication.

[0027] AP101 multicasts a group address frame to STA102 and STA103 that will join the constructed network. Group address frames include, for example, group addressed data frames, group addressed management frames, and beacon frames. AP101 transmits group address frames for each network. For example, if a network with Link ID=1 is constructed by links 104a and 105a, AP101 transmits a group address frame in that network with Link ID=1. Similarly, AP101 can transmit group address frames in networks to which other Link IDs are assigned. These group address frames may be the same or different.

[0028] (AP and STA configuration) 2 shows an example of the hardware configuration of the AP 101 in this embodiment. The AP 101 has, as an example of the hardware configuration, a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207. Note that there may be multiple antennas. Note that the STAs 102 and 103 may also have the same hardware configuration as the AP 101.

[0029] The storage unit 201 is configured with one or more memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and stores various information such as computer programs for performing various operations described below and communication parameters for wireless communication. Note that, in addition to memories such as ROM and RAM, storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs may be used as the storage unit 201. Furthermore, the storage unit 201 may include multiple memories.

[0030] The control unit 202 is configured with one or more processors, such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and controls the entire AP 101 by executing a computer program stored in the storage unit 201. The control unit 202 may control the entire AP 101 in cooperation with the computer program stored in the storage unit 201 and an OS (operating system). The control unit 202 also generates data and signals (wireless frames) to be transmitted in communication with other communication devices. The control unit 202 may also include multiple processors, such as multi-core processors, and control the entire AP 101 using the multiple processors.

[0031] Furthermore, the control unit 202 controls the function unit 203 to execute predetermined processes such as wireless communication, imaging, printing, projection, etc. The function unit 203 is hardware that enables the AP 101 to execute predetermined functions.

[0032] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user via a monitor screen or a speaker. Here, the output by the output unit 205 may be a display on a monitor screen, a voice output by a speaker, a vibration output, or the like. Note that both the input unit 204 and the output unit 205 may be realized by a single module, such as a touch panel. Also, the input unit 204 and the output unit 205 may be integrated with the STA 102, or may be separate from it.

[0033] The communication unit 206 controls wireless communication conforming to the IEEE802.11be standard. The communication unit 206 may also control wireless communication conforming to other IEEE802.11 series standards in addition to the IEEE802.11be standard, and control wired communication such as a wired LAN. The communication unit 206 controls the antenna 207 to transmit and receive signals generated by the control unit 202 for wireless communication.

[0034] If the AP 101 supports the NFC standard, Bluetooth standard, etc. in addition to the IEEE802.11be standard, the AP 101 may control wireless communication in accordance with these communication standards. If the AP 101 can perform wireless communication in accordance with multiple communication standards, the AP 101 may have a communication unit and an antenna that support each communication standard. The AP 101 communicates data such as image data, document data, and video data via the communication unit 206. The antenna 207 may be configured as a separate unit from the communication unit 206, or may be configured together with the communication unit 206 as a single module.

[0035] Antenna 207 is an antenna capable of communication in frequency bands such as 2.4 GHz band, 5 GHz band, and 6 GHz band. In this embodiment, AP 101 has one antenna, but may have multiple (e.g., three) antennas. Alternatively, AP 101 may have a different antenna for each frequency band. Furthermore, when AP 101 has multiple antennas, AP 101 may have a communication unit 206 corresponding to each antenna.

[0036] 3 shows an example of the functional configuration of the AP 101 in this embodiment. As an example of the functional configuration, the AP 101 has a wireless LAN control unit 301, a frame generation unit 302, a connection management unit 303, a GTK control unit 304, and a UI (User Interface) control unit 305. The STAs 102 and 103 can also have the same functional configuration as the AP 101.

[0037] The wireless LAN control unit 301 may be configured to include a program for controlling transmission and reception of wireless signals between other wireless LAN devices. The wireless LAN control unit 301 transmits and receives frames generated by the frame generation unit 302 via the communication unit 206 and the antenna 207 in accordance with the IEEE802.11 standard series, and executes wireless LAN communication control. The number of wireless LAN control units is not limited to one, and may be two, or three or more.

[0038] Frame generation unit 302 generates a wireless frame to be transmitted by wireless LAN control unit 301. The contents of the wireless frame generated by frame generation unit 302 may be restricted by settings stored in storage unit 201 (FIG. 2), or may be changed by user settings from UI control unit 305. Information on the generated frame is sent to wireless LAN control unit 301, and transmitted to the communication partner via communication unit 206 and antenna 207.

[0039] A connection management unit 303 checks and manages the connection state / communication state of each link to the other device as a result of frame exchange by the wireless LAN control unit 301 .

[0040] The GTK control unit 304 functions as a key control means for controlling GTK. For example, the GTK control unit 304 generates and manages the GTK to be used (applied) for each link. The GTK control unit 304 also decides whether or not to regenerate (update) the GTK based on the confirmation result (connection status / communication status for each link) obtained from the connection management unit 303. If it is decided to regenerate the GTK, 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.

[0041] The UI control unit 305 generates a control signal based on a user's operation (user setting) on ​​the input unit 204, and transmits it to each component. The UI control unit 305 also controls various outputs to the output unit 205.

[0042] (Processing flow by AP MLD) A flowchart of the process executed by AP MLD is shown in Fig. 4. Specifically, Fig. 4 shows the flow of the process executed by AP MLD to determine whether to update, generate, or discard the GTK.

[0043] The process in Fig. 4 starts when the STA MLD and AP MLD receive a notification to suspend or disconnect (suspend / disconnect) the connection in some or all links from the STA MLD after the STA MLD and AP MLD start multi-link communication (establish a connection in multi-link). Alternatively, the process may start when the AP transmits a notification to a specific STA MLD to suspend / disconnect the connection in some or all links. Fig. 4 shows the former case.

[0044] 4 will be described as an example of the processing by the above-described AP 101. The processing of the flowchart can be realized by the control unit 202 of the AP 101 executing a control program stored in the storage unit 201, and performing calculations and processing of information and control of each piece of hardware.

[0045] First, the wireless LAN control unit 301 of the AP 101 receives a frame (notification) indicating that the connection on some or all links will be interrupted / disconnected from the currently connected STA MLD (in this description, STA 102) (S401). This frame may be a Deauthentication frame or a Disassociation frame defined in IEEE802.11. Also, a frame that is an extension of these frames for multi-link communication may be used. Alternatively, it may be a frame for switching (transitioning) the connection to another link after disconnecting some links. As a frame for switching the connected link to another link, for example, a frame as shown in FIG. 5 may be used.

[0046] An example of a frame for indicating switching of a connected link to another link in multi-link communication is shown in Fig. 5. The frame shown in Fig. 5 is an extended version of the frame defined in IEEE802.11.

[0047] The fields / subfields in a frame 500 shown in Fig. 5 include, from the beginning, a Frame Control field 501, a Duration field 502, an A1 field 503, an A2 field 504, an A3 field 505, a Sequence Control field 506, an HT Control field 507, a Multi-Link Element field 508, and an FCS field 509. Note that this frame is described as a type of Management frame defined in IEEE802.11, but it may also be a type of Control frame. In that case, for example, the A3 field 505, the Sequence Control field 506, and the HT Control field 507 may not be included.

[0048] The Frame Control field 501 indicates the type of frame. The values ​​of the Type subfield and SubType subfield (not shown) included in the Frame Control field 501 can indicate whether the type of frame is a Deauthentication frame or a Disassociation frame. Either type of frame may be used as the frame used in S401. Alternatively, a new definition may be made that a frame indicating link switching occurs when the Type subfield value is 00 and the SubType subfield value is 1111. Alternatively, an Action frame with a Type subfield of 00 and a SubType subfield of 1101 may be used, and an element indicating channel switching or disconnection of some links may be provided inside the frame.

[0049] The Multi-Link Element field 508 shows an example of an element to be added to the frame (included in the frame). The Multi-Link Element field 508 includes an Element ID subfield 510, a Length subfield 511, an Element ID Extension subfield 512, a Multi-Link Control subfield 513, a Previous link ID subfield 514, and a Next link ID subfield 515. When the type of the frame is an Action frame, the Category subfield may be used instead of the Element ID subfield 510 and the Length subfield 511 to express the contents of the subfield. Furthermore, all the subfields in the Multi-Link Element field 508 are not essential. For example, only the Previous link ID subfield 514 or only the Next link ID subfield 515 may be included. Alternatively, the Multi-Link Element field 508 may be configured by a combination of the above subfields and some of the other subfields.

[0050] A specific value of the Element ID subfield 510 is, for example, 255, and the value of the Element ID Extension subfield 512 is, for example, 15. This makes it possible to indicate that the element added to the frame is a Multi-Link Element. The Multi-Link Control subfield 513 indicates which operation of the multi-link is instructed by the added Multi-Link Element. For example, the Multi-Link Control subfield 513 includes a Multi-Link Type subfield 516, and by setting the value to 0x4, it is possible to indicate a change in the connected link. Alternatively, by setting the value to 0x5, it may indicate a disconnection of the link.

[0051] The Prev link ID subfield 514 indicates the link ID of the link to be interrupted or disconnected. The Next link ID subfield 515 indicates the link ID of the link to be newly connected in place of the disconnected link. For example, when the STA 102 interrupts the connection on the link with Link ID=2 and wishes to establish a new connection with the network consisting of the link with Link ID=3, the value of the Prev link ID subfield 514 is 2 and the value of the Next link ID subfield 515 is 3. Also, when the STA 102 only wishes to disconnect the connection on the link with Link ID=2, the value of the Next link ID subfield 515 may be 0, or the Next link ID subfield 515 itself may not be assigned.

[0052] 4, the subsequent processes (processing after S402) are performed for each network, that is, for each Link ID, constructed by AP 101. When a frame indicating interruption / disconnection of a link connection is received from STA 102 in S401, connection management unit 303 of AP 101 determines whether the frame indicates interruption / disconnection of all links to which STA 102 is connected (S402).

[0053] If the received frame indicates that all the links to which the STA102 is connected are to be interrupted / disconnected (Yes in S402), the process proceeds to S403. In S403, the connection management unit 303 of the AP101 further determines whether or not there is another STA MLD other than the STA102 communicating in the network (NW) formed by the target link (assumed to be the link with Link ID=x) (S403). In this step, it can be determined whether another STA MLD is communicating with the AP101 in a link other than the link for which the STA102 requests interruption / disconnection. If there is no other STA MLD communicating (using the link with Link ID=x) in the network formed by the link with Link ID=x (No in S403), the GTK control unit 304 discards the group key for the link (S407). On the other hand, if there is another STA MLD communicating in the network formed by the link with Link ID=x (Yes in S403), the process proceeds to S404. In S404, the connection management unit 303 further judges whether or not the network configured by the link with Link ID=x is a network with which the STA 102 (the STA MLD that notified in S401) was communicating (participating in). In other words, the connection management unit 303 judges whether the link with Link ID=x is a link for which the STA 102 requested interruption / disconnection in S401 (a link to be interrupted / disconnected).

[0054] If the STA 102 is communicating in a network configured with a link with Link ID=x (Yes in S404), the GTK control unit 304 of the AP 101 regenerates (updates) the group key for the link with Link ID=x (S405). In addition, the wireless LAN control unit 301 of the AP 101 performs group key exchange to communicate the updated and newly generated group key (S406).

[0055] On the other hand, if STA102 has not communicated in the network configured with the link of Link ID=x (No in S404), the process proceeds to S408. In S408, the connection management unit 303 of AP101 further determines whether the network configured with the link of Link ID=x is a network with which STA102 (the STA MLD that notified in S401) has previously communicated. If STA102 has not previously communicated in the network configured with the link of Link ID=x (No in S408), the GTK control unit 304 of AP101 does not update the group key for the link of Link ID=x, and maintains the group key (S415).

[0056] If STA102 has previously communicated with the network configured with the link of Link ID=x (Yes in S408), the connection management unit 303 of AP101 further determines whether the group key for the link has been updated since STA102 left the network (S409). If it has been updated (Yes in S409), the GTK control unit 304 of AP101 does not update the group key for the link of Link ID=x, and maintains the group key (S415). If it has not been updated (No in S409), the GTK control unit 304 of AP101 updates the group key for the link of Link ID=x (S405), and the wireless LAN control unit 301 exchanges the group key (S406).

[0057] The AP 101 may perform the processes of S408 and S409 together. That is, the connection management unit 303 may check whether the STA 102 has joined the network configured with the link of Link ID=x since the group key was last updated, and the GTK control unit 304 may maintain the group key if the STA 102 has not joined the network, or update the group key if the STA 102 has joined the network.

[0058] Next, a process will be described when the determination in S402 indicates that the received frame does not mean to interrupt / disconnect all the links to which the STA 102 is connected (No in S402). This corresponds to, for example, a case where the STA 102 interrupts / disconnects a connection in a certain link and reconnects in another link, or a case where the STA 102 interrupts / disconnects a connection in a certain link but continues the connection in another link, and the process proceeds to S410. The connection management unit 303 of the AP 101 checks whether a new STA (which may be a STA MLD) is going to connect to the network (NW) configured by the target link (assuming the link with Link ID=x) (S410).

[0059] If there is no STA to newly connect (No in S410), the GTK control unit 304 maintains the group key for the link with Link ID=x (S416). If there is a STA to newly connect (Yes in S410), the connection management unit 303 of the AP101 further checks whether the newly connecting STA is the first STA in the network (S411). If the newly connecting STA is not the first STA in the network (No in S411), the wireless LAN control unit 301 of the AP101 exchanges the generated group key (S414). On the other hand, if the newly connecting STA is the first STA in the network (Yes in S411), the GTK control unit 304 of the AP101 generates a group key for the link with Link ID=x (S412), and the wireless LAN control unit 301 exchanges the group key (S413).

[0060] AP101 performs the above process for each network to be constructed, i.e., for each Link ID. When the process has been performed for all Link IDs (Yes in S417), this procedure is completed. Note that the above flowchart may be configured to omit the process of S404. For example, if STA102 is connected to AP101 using one link and requests interruption / disconnection of the link (Yes in S403), and another STA MLD is communicating with the network configured by that link (Yes in S403), the process proceeds to S405, and AP101 may regenerate the group key.

[0061] Next, an embodiment based on the process of Fig. 4 will be described. In the following description, reference will be made to the communication system shown in Fig. 1.

[0062] Example 1 In the first embodiment, AP101 configures a network with 6ch in the 2.4 GHz band at Link ID=1, 36ch in the 5 GHz band at Link ID=2, and 5.955 GHz in the 6 GHz band at Link ID=3. STA102 joins the network with Link ID=1 at link 104a, and joins the network with Link ID=2 at link 104b. Meanwhile, STA103 joins the network with Link ID=1 at link 105a, and joins the network with Link ID=3 at link 105b.

[0063] In this state, it is assumed that STA 102 leaves the network in which it participates with Link ID=1, and participates in the network with Link ID=3. In other words, it is assumed that STA 102 disconnects the link with Link ID=1, and connects to the link with Link ID=3 (No in S402 in FIG. 4). In this case, one participating STA MLD will leave the network in the network configured with the link with Link ID=1. However, since STA102 continues to connect to AP101 via another link (i.e., the link with Link ID=2), AP101 maintains the group key for the link with Link ID=1 (No in S410, S416). Furthermore, in the network configured with the link of Link ID=2, no new STA MLD connections or disconnections occur, so AP 101 maintains the group key for the link of Link ID=2 (No in S410, S416). Furthermore, STA 102 newly joins the network formed by the link with Link ID=3 (Yes in S410, No in S411). STA 103 is already participating in the network formed by the link with Link ID=3. Therefore, group key exchange is carried out between AP 101 and STA 102 (S414).

[0064] Example 2 In the second embodiment, AP101 configures a network with 6ch in the 2.4 GHz band at Link ID=1, 36ch in the 5 GHz band at Link ID=2, and 5.955 GHz in the 6 GHz band at Link ID=3. STA102 joins the network with Link ID=1 at link 104a, and joins the network with Link ID=2 at link 104b. STA103 joins the network with Link ID=1 at link 105a, and joins the network with Link ID=3 at link 105b.

[0065] In this state, it is assumed that the STA 102 will leave all networks it participates in. In other words, it is assumed that the STA 102 will disconnect the links with Link ID=1 and Link ID=2 (Yes in S402). In this case, in the network formed by the link with Link ID=1, one participating STA MLD will leave the network. Also, all connections between AP 101 and STA 102 will be cut off. Meanwhile, STA 103 is participating in the network formed by the link with Link ID=1 (Yes in S403, Yes in S404). Therefore, AP 101 updates (regenerates) the group key for the link with Link ID=1 (S405). AP 101 then exchanges the group key with STA 103 using the updated group key (S406). Furthermore, in the network configured with the link of Link ID=2, all participating STA MLDs leave the network (No in S403), so AP 101 discards the group key it had been holding for the link of Link ID=2 (S407). Also, no new STA MLD connections or disconnections occur in the network configured with the link of Link ID=3. Also, in this example, it is assumed that STA102 has not previously participated in the network configured with that link. Therefore, AP101 maintains the group key for the link of Link ID=3 (Yes in S403, No in S404, No in S408, S415).

[0066] Example 3 In the third embodiment, AP101 configures a network with 6ch in the 2.4 GHz band at Link ID=1, 36ch in the 5 GHz band at Link ID=2, and 5.955 GHz in the 6 GHz band at Link ID=3. STA102 joins the network with Link ID=1 at link 104a, and joins the network with Link ID=2 at link 104b. STA103 joins the network with Link ID=1 at link 105a, and joins the network with Link ID=2 at link 105b.

[0067] In this state, it is assumed that STA 102 leaves the network in which it participates with Link ID=2, and participates in the network with Link ID=3. In other words, it is assumed that STA 102 disconnects the link with Link ID=1, and connects to the link with Link ID=3 (No in S402 in FIG. 4). In this case, since no new STA MLD connections or disconnections occur in the network configured with the link with Link ID=1, AP 101 maintains the group key for the link with Link ID=1 (No in S410, S416). In addition, in a network configured with the link of Link ID=2, one participating STA MLD will leave the network. However, since STA102 continues to connect to AP101 via another link (i.e., the link of Link ID=2), AP101 maintains the group key for the link of Link ID=2 (No in S410, S416). Furthermore, in the network configured with the link of Link ID=3, a new STA MLD will participate in the network from a state in which no STA MLD is participating (Yes in S410, Yes in S411). Therefore, AP101 generates a new group key for the link of Link ID=3 (S412) and exchanges the group key with STA102 (S413).

[0068] By operating in this manner, AP 101 can suppress updates to the group key while keeping the group key unknown to STA MLDs that are not currently participating in the network.

[0069] In the embodiment described above, the AP 101 forms three networks operating in multi-link mode, but the number of networks is not limited to three. For example, the number of networks may be two, four or more.

[0070] In the above-described embodiment, the AP 101 has a function as an AP, but if it is a device that manages a group key, it does not have to have a function as an AP. For example, it may be considered as one of the STAs when connecting STAs. For example, it may be a device that operates as a GO (Group Owner) of Wi-Fi Direct.

[0071] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0072] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0073] 100 network, 101 communication device (AP MLD), 102 communication device (STA MLD), 103 communication device (STA MLD), 104a; 104b; 105a; 105b link

Claims

1. A communication device that is compliant with the IEEE 802.11 standard series and is capable of establishing a plurality of links with a plurality of other communication devices, each of which has a different frequency channel, a key control means for generating a Group Transient Key (GTK) for encrypting frames to be communicated for each of the plurality of links; receiving means for receiving, from a first other communication device of the plurality of other communication devices, a first notification indicating disconnection or interruption of some of the plurality of links, or a second notification indicating disconnection or interruption of all of the plurality of links; When the communication device is connected to the first other communication device and a second other communication device among the plurality of other communication devices via a first link and a second link, the key control means updating the GTKs for the first link and the second link in response to receiving the second notification indicating disconnection or interruption of the first link and the second link from the first other communication device; not updating the GTK for the first link and the second link in response to receiving the first notification indicating disconnection or interruption of the first link from the first other communication device; A communication device comprising:

2. The communication device as described in Claim 1, further characterized in that it further has a transmitting means for transmitting the updated GTK to the second other communication device connected via the first link and the second link when the GTK for the first link and the second link is updated by the key control means.

3. The communication device described in Claim 1 or 2, characterized in that the key control means does not update the GTK for the first link and the second link in response to receiving the second notification indicating disconnection or interruption of the first link and the second link from the first other communication device when the communication device is connected only to the first other communication device via the first link and the second link.

4. The communication device described in Claim 3, characterized in that the key control means, when the communication device is connected only to the first other communication device via the first link and the second link, discards the GTK for the first link and the second link in response to receiving the second notification indicating disconnection or interruption of the first link and the second link from the first other communication device.

5. The communication device of claim 4, characterized in that the first notification indicating a disconnection or interruption of the first link further indicates a connection on a third link.

6. The communication device according to claim 5, characterized in that the first notification indicating the disconnection or interruption of the first link includes a Multi-Link Element, and the Multi-Link Element includes information indicating a Link ID of the first link.

7. The communication device according to claim 1 , wherein the second notification is a Deauthentication frame or a Disassociation frame.

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

9. The communication device according to any one of claims 1 to 7, wherein the communication device is a communication device that operates as a Group Owner (GO) of Wi-Fi Direct.

10. A method for controlling a communication device that is compliant with the IEEE 802.11 standard series and is capable of establishing a plurality of links with a plurality of other communication devices, each of which has a different frequency channel, comprising the steps of: a key control step of generating a Group Transient Key (GTK) for encrypting frames to be communicated for each of the plurality of links; receiving, from a first other communication device of the plurality of other communication devices, a first notification indicating disconnection or interruption of some of the plurality of links, or a second notification indicating disconnection or interruption of all of the plurality of links; The key control step includes, when the communication device is connected to the first other communication device and a second other communication device among the plurality of other communication devices via a first link and a second link, updating the GTKs for the first link and the second link in response to receiving the second notification indicating disconnection or interruption of the first link and the second link from the first other communication device; not updating the GTK for the first link and the second link in response to receiving the first notification indicating disconnection or interruption of the first link from the first other communication device; A method for controlling a communication device comprising:

11. A program for causing a computer to function as the communication device according to any one of claims 1 to 9.

Images