Communication device, control method, and program

Abstract

To provide a mechanism that prevents interference in communication when performing roaming while maintaining multi-link communication.SOLUTION: A communication device performs, with another communication device, multi-link communication using a plurality of links using different frequency channels from each other. The communication device makes a change from a first state where it performs the multi-link communication with another first communication device to a second state where it performs the multi-link communication with another second communication device. When making the change from the first state to the second state, the communication device performs control to enter a third state where it can communicate with the another first communication device via a first link and it can communicate with the another second communication device via a second link, and performs control so that the frequency channel of the first link and the frequency channel of the second link do not interfere with each other in the third state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a communication device, a control method, and a program. [Background technology]

[0002] With the recent increase in the amount of data being communicated, development of communication technologies such as wireless local area networks (LANs) is progressing. The IEEE (Institute of Electrical and Electronics Engineers) 802.11 series of standards is known as a major communication standard for wireless LANs. The IEEE 802.11 series of standards includes standards such as IEEE 802.11a / b / g / n / ac / ax / be (see Patent Document 1). To further improve communication reliability, the IEEE 802.11bn standard is being developed as a successor to the IEEE 802.11be standard. The IEEE 802.11 Working Group (WG), which formulates the IEEE 802.11bn standard, will define the goals and scope of the standard in the UHR SG, and will specify detailed technical content to be included in the standard in TGbn. Note that UHR SG is an abbreviation for Ultra High Reliability Study Group. TGbn is also an abbreviation for Task Group bn.

[0003] The IEEE802.11be standard and its successor, the IEEE802.11bn standard, consider multi-link communication, in which one access point (AP) establishes multiple wireless links with one station (STA / non-AP STA) for communication. In multi-link communication, for example, an AP establishes a connection with a STA using multiple frequency channels in the 2.4 GHz, 5 GHz, or 6 GHz frequency band, and communicates in parallel on each frequency channel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-050133 Summary of the Invention [Problem to be solved by the invention]

[0005] Roaming technology is known for wireless communications that comply with the IEEE802.11 standard. Roaming refers to a situation in which a station connected to a certain access point (AP) switches its connection to another AP. For example, if a station becomes far from the AP it is currently connected to, it can switch its connection to another AP that is located closer to it.

[0006] However, when roaming while maintaining multi-link communication, frequency channel collisions may occur between the link communication with the roaming source AP and the link communication with the roaming destination AP. For example, consider a case where a roaming source AP1 is connected at 2.4 GHz and 5 GHz, and a roaming destination AP2 is connected at 2.4 GHz and 5 GHz. In this case, if the 5 GHz connection of AP1 is first connected to the 2.4 GHz connection of AP2, a collision may occur between the 2.4 GHz frequency channel of AP1 and the 2.4 GHz frequency channel of AP2.

[0007] The present invention has been made in consideration of at least one of the above-mentioned problems, and an object of one aspect of the present invention is to provide a mechanism for preventing communication interference when roaming while maintaining multi-link communication. [Means for solving the problem]

[0008] A communication device according to one aspect of the present invention comprises: communication means capable of multi-link communication with other communication devices using multiple links, each using a different frequency channel; roaming means for switching from a first state in which multi-link communication is performed with a first other communication device to a second state in which multi-link communication is performed with a second other communication device; and control means for controlling, when switching from the first state to the second state, to pass through a third state in which communication with the first other communication device is possible via a first link and communication with the second other communication device via a second link, wherein the control means controls so that the frequency channel of the first link and the frequency channel of the second link do not interfere with each other in the third state. [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to provide a mechanism for preventing communication interference when roaming while maintaining multi-link communication. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates an example of a network configuration. [Figure 2] FIG. 2 illustrates an example of a hardware configuration of a communication device. [Figure 3] FIG. 2 illustrates an example of a functional configuration of a communication device. [Figure 4] FIG. 1 is a diagram outlining multi-link communication and roaming. [Figure 5] FIG. 10 is a flowchart illustrating an example of processing performed by a communication device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] (Network configuration) 1 shows an example of the configuration of a network 101 according to this embodiment. This network 101 is configured to include a plurality of communication devices. Each of the plurality of communication devices is capable of communication via a wireless local area network (LAN) that complies with the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series standard.

[0013] All of the communication devices of this embodiment are compatible with the IEEE802.11be (EHT (Extremely / Extreme High Throughput)) standard and can perform wireless communication in accordance with this standard. Note that each communication device may also be capable of operating in accordance with other IEEE802.11 standards (for example, at least one of the IEEE802.11a / b / g / n / ac / ax / be standards).

[0014] Each communication device is configured to be able to perform communication according to the IEEE 802.11 series standard in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. Note that the frequency bands that each communication device can use are not limited to these, and a different frequency band such as the 60 GHz band may also be used.

[0015] Furthermore, each communication device can communicate using frequency bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz. Note that this is just an example, and other frequency bandwidths, such as 240 MHz or 4 MHz, may also be configured to be usable by the communication device. Note that when a new usable frequency bandwidth is defined in the IEEE 802.11 series standards, the communication device may be configured to be able to use that frequency bandwidth.

[0016] The IEEE 802.11 series of standards defines "frequency channels," and communication devices compliant with the standards can use these frequency channels to perform wireless communications. The IEEE 802.11 series of standards defines multiple frequency channels in each frequency band, such as the 2.4 GHz band, 5 GHz band, and 6 GHz band. The IEEE 802.11 series of standards also defines the bandwidth of each frequency channel as 20 MHz, except for the 60 GHz band. However, by bonding adjacent frequency channels, it is possible to use a bandwidth of 40 MHz or more in a single frequency channel. In the 60 GHz band, the bandwidth of the frequency channel is defined as 2.16 GHz.

[0017] The communication devices according to this embodiment are configured to be capable of performing multi-link communication in which one AP establishes multiple wireless links with one STA. A communication device capable of performing such multi-link communication is called an MLD (Multi-Link Device). In particular, an MLD that functions as an AP and operates in a role of building a network is called an AP MLD, and an MLD that functions as an STA and operates in a role of joining the built network is called a Non-AP MLD.

[0018] In this embodiment, it is assumed that the AP MLD 102 as the roaming source constructs the network 101, establishes the link 104 and the link 105 with the non-AP MLD 103, and executes multi-link communication.

[0019] Also, it is assumed that the AP MLD 107 as a roaming destination constructs a network 106, establishes a link 108 and a link 109 with the non-AP MLD 103, and executes multi-link communication.

[0020] In this embodiment, when there is no need to particularly distinguish between the communication devices, the AP MLDs 102 and 107 and the non-AP MLD 103 are collectively referred to as communication devices. There may also be a Wireless Lan Controller (not shown) that is connected to the AP MLDs 102 and 107 and manages the connection state and communication status of the non-AP MLD 103.

[0021] The multiple wireless links established in multi-link communication may use frequency channels in different frequency bands. For example, the AP MLD 102 and the non-AP MLD 103 may establish link 104 using a first frequency channel in the 2.4 GHz band and link 105 using a second frequency channel in the 5 GHz band, and communicate through both links. In this case, the AP MLD 102 maintains link 104 and link 105 in parallel.

[0022] Establishing multiple links between the AP MLD 102 and the non-AP MLD 103 using multiple frequency channels can improve the throughput of communication between these communication devices. Note that, although the above example shows an example in which two links are established, three or more links may be established in parallel. For example, in addition to the link 104 in the 2.4 GHz band and the link 105 in the 5 GHz band, an additional link (not shown) in the 6 GHz band may be established between the AP MLD 102 and the non-AP MLD 103.

[0023] Furthermore, the AP MLD 102 and the Non-AP MLD 103 may establish multiple links for multi-link communication using multiple different frequency bands as described above, or may establish the links using different frequency channels in the same frequency band.

[0024] The multiple frequency channels used in the multiple links established between the AP MLD 102 and the non-AP MLD 103 may be selected from channels spaced at least 20 MHz apart from each other. In one example, the link 104 and the link 105 may be established between the AP MLD 102 and the non-AP MLD 103 using channels 1 and 11 in the 2.4 GHz band.

[0025] Alternatively, two or more of the multiple links may be established using different frequency channels in the same frequency band, with the remaining links being established using a different frequency band. For example, two links may be established between the AP MLD 102 and the non-AP MLD 103 using channels 1 and 11 in the 2.4 GHz band, and an additional link may be established using channel 36 in the 5 GHz band. By establishing multiple links using different frequency bands between the AP MLD 102 and the non-AP MLD 103, even if the communication rate in one frequency band drops due to a high load, a constant communication rate can be ensured by communication in another frequency band. This makes it possible to suppress a decrease in throughput in communication between these communication devices.

[0026] Furthermore, the AP MLD 102 and the non-AP MLD 103 may be capable of performing communication using, for example, MIMO (Multiple-Input Multiple-Output). In this case, the AP MLD 102 and the non-AP MLD 103 have multiple antennas, and the transmitting communication device transmits different signals in parallel from each antenna using the same frequency channel. The receiving communication device receives all signals arriving from multiple streams in parallel using multiple antennas, and separates and decodes the signals of each stream. This makes it possible to communicate a large amount of data in a short period of time. When performing multi-link communication, the AP MLD 102 and the non-AP MLD 103 may perform MIMO communication on some links.

[0027] In addition to the IEEE802.11 series standards, the AP MLD 102 and the Non-AP MLD 103 may also comply with other communication standards such as Bluetooth (registered trademark), NFC, UWB, ZigBee (registered trademark), and MBOA. NFC stands for Near Field Communication, UWB stands for Ultra Wide Band, and MBOA stands for Multi Band OFDM Alliance. UWB also includes wireless USB, wireless 1394, WiNET, and the like. Each communication device may also comply with a communication standard for wired communication such as a wired LAN.

[0028] The AP MLD 102 may be, for example, a wireless LAN router or a personal computer (PC), but is not limited to these. The non-AP MLD 103 may be, for example, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, a headset, but is not limited to these. The AP MLD 102 and the non-AP MLD 103 may be information processing devices such as wireless chips that can perform wireless communication in accordance with the IEEE802.11bn standard.

[0029] The above-mentioned explanations of the AP MLD 102 and the non-AP MLD 103 and the link 104 and the link 105 also apply to the AP MLD 107 and the non-AP MLD 103 and the link 108 and the link 109.

[0030] Furthermore, although the wireless network of Figure 1 has two AP MLDs and one non-AP MLD, the number and arrangement of AP MLDs and non-AP MLDs are not limited to this. For example, the wireless network of Figure 1 may have more AP MLDs or non-AP MLDs. In this case, the frequency bands of each established link, the number of links, and the frequency bandwidth are not particularly limited.

[0031] When roaming during multi-link communication, the non-AP MLD 103 according to this embodiment establishes a wireless link with the roaming destination AP MLD 107 while maintaining a wireless link with the roaming source AP MLD 102. This allows the non-AP MLD 103 to always maintain an established wireless link with the AP MLD (102 or 107). A possible method for establishing a wireless link with the roaming destination AP MLD 107 while maintaining a wireless link with the roaming source AP MLD 102 will be described using FIG. 1, but the present invention is not limited to this.

[0032] The non-AP MLD 103 establishes links 104 and 105 with the AP MLD 102 to establish multi-link communication. Thereafter, to perform roaming to the AP MLD 107, the non-AP MLD 103 first disconnects link 104 and then establishes link 108 with the AP MLD 107. In this state, the link 105 with the AP MLD 102 remains maintained.

[0033] Next, after establishing link 108 with AP MLD 107, link 105 with AP MLD 102 is disconnected, and link 109 with AP MLD 107 is established. In this way, non-AP MLD 103 can always maintain a state in which a wireless link with the AP MLD (102 or 107) is established.

[0034] In the above description, the procedure is to disconnect the link with the AP MLD 102 of the roaming source and then establish a link with the AP MLD 107 of the roaming destination, but this is not limiting. Alternatively, the procedure may be to establish a link with the AP MLD 107 of the roaming destination and then disconnect the link with the AP MLD 102 of the roaming source, or disconnect and connect may be performed simultaneously.

[0035] However, in the above procedure, it is possible that the link 105 with the AP MLD 102 and the link 108 with the AP MLD 107 may be established for communication on the same frequency channel. In this case, the communications of the link 105 and the link 108 may interfere with each other.

[0036] In this embodiment, during roaming, a frequency channel for connecting with the roaming destination AP MLD 107 is selected so as not to interfere with communication performed by the non-AP MLD 103. Specifically, the non-AP MLD 103 collects information about the roaming destination AP MLD 107 in advance and selects a frequency channel that will not interfere with communication with the roaming source from among the frequency channels of communication links that can be established. A possible method for collecting information about the roaming destination AP MLD 107 is to receive a frame transmitted by the roaming destination AP MLD 107 to notify its own capability information. In this case, a beacon frame, a FILS (Fast Initial Link Setup) Discovery frame, or a probe response frame can be considered, but is not limited to these. Another possible method is to receive notification of the capability of the roaming destination AP MLD 107 from the roaming source AP MLD 102. In this case, a BSS Transition Management (BTM) Request frame can be considered, but is not limited to these.

[0037] (Configuration of communication device) An example of the hardware configuration of a communication device (AP MLDs 102, 107 and Non-AP MLD 103) according to this embodiment will be described with reference to Fig. 2. The communication device includes, as its 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, for example.

[0038] The storage unit 201 is configured to include one or more memories such as ROM and RAM, and stores various information such as computer programs for performing various operations described below and communication parameters for wireless communication. ROM stands for Read Only Memory, and RAM stands for Random Access Memory. The storage unit 201 may include storage media such as a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, a DVD, etc., in addition to or instead of memories such as ROM and RAM. The storage unit 201 may also include multiple memories.

[0039] The control unit 202 is configured with one or more processors, such as a CPU or an MPU, and controls the entire communication device by executing a computer program stored in the storage unit 201, for example. The CPU stands for Central Processing Unit, and the MPU stands for Micro Processing Unit. The control unit 202 may be configured to perform processes for generating data and signals to be transmitted in communication with other communication devices, in addition to the overall control of the communication device. The control unit 202 may be configured to perform processes such as the overall control of the communication device in cooperation with a computer program stored in the storage unit 201 and an OS (Operating System). The control unit 202 may also include multiple processors, such as a multi-core processor, and may perform processes such as the overall control of the communication device using the multiple processors. The control unit 202 may also be configured with an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or the like.

[0040] Furthermore, the control unit 202 controls the functional unit 203 to perform predetermined processing such as capturing images, printing, and projection. The functional unit 203 is, for example, hardware that enables the communication device to perform predetermined processing. For example, if the communication device is a camera, the functional unit 203 is an imaging unit that performs imaging processing. For example, if the communication device is a printer, the functional unit 203 is a printing unit that performs printing processing. For example, if the communication device is a projector, the functional unit 203 is a projection unit that performs projection processing. The data processed by the functional unit 203 may be data stored in the storage unit 201, or may be data communicated with another communication device via the communication unit 206, which will be described later.

[0041] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user. Here, the output by the output unit 205 includes, for example, at least one of a display on a screen, an audio output by a speaker, a vibration output, and the like. Note that both the input unit 204 and the output unit 205 may be implemented by a single module, such as a touch panel. Furthermore, the input unit 204 and the output unit 205 may each be built into a communication device, or may be configured as an external device connected to the communication device.

[0042] The communication unit 206 controls wireless communication compliant with the IEEE 802.11 series standards and IP communication. In this embodiment, the communication unit 206 is configured to control wireless communication compliant with the IEEE 802.11bn standard in particular. Note that the communication unit 206 may control wireless communication compliant with other IEEE 802.11 series standards in addition to the IEEE 802.11bn standard, or wired communication such as a wired LAN. The communication unit 206 controls the antenna 207 to transmit and receive signals for wireless communication generated by, for example, the control unit 202. The communication device may have multiple communication units 206. If the communication device has multiple communication units 206, one link may be established by one communication unit 206 when establishing multiple links in multi-link communication. Note that the communication device may establish one link for each of some communication units 206, and establish multiple links for other communication units 206. Furthermore, when multiple links are established using one communication unit 206, the communication unit 206 may execute communication via the multiple links by, for example, switching the operating frequency channel in a time-division manner. If the communication device supports standards such as the NFC standard and Bluetooth (registered trademark) in addition to the IEEE 802.11bn standard, it may control wireless communication in accordance with these communication standards. If the communication device is capable of executing wireless communication in accordance with multiple communication standards, it may have separate communication units and antennas compatible with each communication standard. The communication device communicates data such as image data, document data, and video data with other communication devices via the communication unit 206. The antenna 207 may be provided separately from the communication unit 206, or may be configured as a single module together with the communication unit 206.

[0043] Antenna 207 is an antenna that enables communication in various frequency bands, such as the sub-GHz band, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the 60 GHz band. The communication device may have a single antenna, such as a multi-band antenna, as antenna 207, or may have multiple antennas corresponding to, for example, multiple frequency bands. When the communication device has multiple antennas, it may have one communication unit 206 for the multiple antennas, or multiple communication units 206 corresponding to the multiple antennas, respectively. Antenna 207 may be a single antenna or an antenna array. That is, antenna 207 may have multiple antenna elements and be configured to be able to perform communication using, for example, MIMO (Multi-Input and Multi-Output).

[0044] Next, an example of the functional configuration of the communication device of this embodiment will be described with reference to Fig. 3. The communication device (AP MLD 102 and Non-AP MLD 103) is configured to include, for example, a wireless LAN control unit 301, a frame processing unit 302, a roaming control unit 303, a UI control unit 304, and a storage control unit 305. Note that these are just examples, and some or all of these functional units may be replaced with other configurations, multiple functional units may be integrated to form one functional unit, or one functional unit may be divided into multiple functional units. Also, multiple identical functional units may be provided. For example, multiple wireless LAN control units 301 may exist.

[0045] The wireless LAN control unit 301 controls the antenna 207 and a communication circuit (e.g., the communication unit 206) to transmit and receive wireless signals to and from other wireless LAN communication devices. The frame processing unit 302 processes wireless frames transmitted and received by the wireless LAN control unit 301. The frame processing unit 302 generates wireless frames including control information and content data in accordance with the IEEE 802.11 series standards and transfers them to the wireless LAN control unit 301. The wireless LAN control unit 301 then performs predetermined wireless processing, such as frequency conversion, on the generated wireless frames and transmits them to other communication devices. The wireless LAN control unit 301 also receives wireless frames transmitted by other communication devices via the antenna, performs predetermined wireless processing on the wireless frames, and transfers them to the frame processing unit 302. The frame processing unit 302 then analyzes the contents of the received wireless frames to acquire the control information and content data. The control information generated by the frame processing unit 302 and the control information acquired by the frame processing unit 302 based on wireless frames from other communication devices may be restricted by settings stored in the storage unit 201. This control information may be changed by user settings from the UI control unit 304. The roaming control unit 303 controls roaming according to this embodiment. Specifically, it determines the frequency channel and link for roaming.

[0046] The UI control unit 304 controls hardware related to the user interface, such as a touch panel and buttons for accepting operations by a user (not shown) of the communication device. The UI control unit 304 also controls the display of images and the like, or the presentation of information such as audio output to the user. The storage control unit 305 controls the storage unit 201 to store programs and data for operating the communication device, and the like, and controls the reading of these programs and data from the storage unit 201.

[0047] (Overview of multi-link communication) Next, multi-link communication and roaming will be outlined with reference to Fig. 4. The AP MLDs 102 and 107 and the Non-AP MLD 103 each have a plurality of (physical or logical) APs and STAs associated with a plurality of links.

[0048] 4, for example, the AP MLD 102 includes a first AP 401 to a third AP 403, the AP MLD 107 includes a first AP 410 to a third AP 412, and the non-AP MLD 103 includes a first STA 404 to a third STA 406. The first AP 401 and the first STA 404 establish a first link 407 using a first frequency channel. Similarly, the second AP 402 and the second STA 405 establish a second link 408 using a second frequency channel, and the third AP 403 and the third STA 406 establish a third link 409 using a third frequency channel. The first frequency channel to the third frequency channel are, for example, any of the frequency channels in the sub-GHz band, the 2.4 GHz band, the 3.6 GHz band, the 4.9 and 5 GHz bands, the 6 GHz band, and the 60 GHz band. In the following, the first link 407, the second link 408, and the third link 409 will be referred to as link 1, link 2, and link 3, respectively.

[0049] Furthermore, the first AP 410 to the third AP 412 of the AP MLD 107 have functions equivalent to those of the first AP 401 to the third AP 403 of the AP MLD 102. Hereinafter, the first link 413, the second link 414, and the third link 415 between the AP MLD 107 and the non-AP MLD 103 will be referred to as link 4, link 5, and link 6, respectively.

[0050] When roaming from AP MLD 102 to AP MLD 107 due to a change in the communication environment caused by, for example, movement of Non-AP MLD 103, the links are moved in an orderly manner to always maintain the link establishment. That is, first, link 1 is disconnected and link 4 is established. Then, link 2 is disconnected and link 5 is established. Finally, link 3 is disconnected and link 6 is established. In this way, it is possible to always maintain the state in which the link with AP MLD 102 or AP MLD 107 is established. Note that the order of link disconnection and establishment may be reversed, with disconnection occurring after establishment, or they may be performed simultaneously.

[0051] (Non-AP MLD103 processing) 5 shows an example of the flow of processing executed by the non-AP MLD 103. This processing can be realized, for example, by the control unit 202 of the non-AP MLD 103 executing a program stored in the storage unit 201. Note that at least part of the processing shown below may be executed by dedicated hardware provided in the non-AP MLD 103.

[0052] This process may be executed when the non-AP MLD 103 starts roaming in a state in which the non-AP MLD 103 has established two or more links with the AP MLD 102. Furthermore, this process may be executed when the non-AP MLD 103 receives a roaming instruction from the AP MLD 102, or may be executed by some other trigger.

[0053] In the explanation of this process, it is assumed that Non-AP MLD 103 and AP MLD 102 have established Link 1 at 2.4 GHz and Link 2 at 5 GHz, and that AP MLD 107 has the capability to establish Link 4 at 2.4 GHz and Link 5 at 5 GHz.

[0054] First, the non-AP MLD 103 checks the status of surrounding APs to determine the AP MLD of the roaming destination (S501). If the non-AP MLD 103 is the trigger, the process of S501 may be performed based on the Beacon frame, FilS Discovery frame, or Probe Response frame transmitted by the surrounding AP MLD, as described above. If the AP MLD 102 is the trigger, the process may be performed based on the BTM Request frame, as described above, but is not limited to this.

[0055] In the process of S501, when the non-AP MLD 103 confirms the AP MLD 107, which is the AP of the roaming destination, it checks the frequency channel on which that AP can communicate (S502). Here, it is assumed that it has been confirmed that the AP has the ability to establish Link 4 at 2.4 GHz and Link 5 at 5 GHz.

[0056] Next, the non-AP MLD 103 determines the roaming order of the links established with the AP MLD 102 (S503). The processing of S503 may take into account, but is not limited to, the communication quality of each link, the order of frequency channels predetermined for each device, and communication speeds.

[0057] In this process, the order is determined based on communication quality, which is determined by the Received Signal Strength Indicator (RSSI).In addition to RSSI, communication quality can be determined by other factors such as the Signal to Noise Ratio (SNR), the number of APs present on a frequency channel, and the Receive Channel Power Indicator (RCPI), but is not limited to these.

[0058] Here, we compare 2.4 GHz Link 1 and 5 GHz Link 2, and assume that 5 GHz Link 2 has a better RSSI value, and that roaming is performed in the order of worst-case communication quality, from Link 1 to Link 2.

[0059] After the roaming order is determined in S503, the first link in the roaming order is set as the roaming link, and it is determined whether a frequency channel at the roaming destination that does not interfere with links other than the roaming link can be selected (S504).

[0060] Note that the number of "links other than the roaming implementation link" in S504 decreases each time the roaming implementation link is updated (S508) after undergoing the processing of S505 or S506. For example, if the roaming order is link 1, link 2, and link 3, and link 1 is the roaming implementation link, the links other than the roaming implementation link are link 2 and link 3. Next, when link 2 is the roaming implementation link, the link other than the roaming implementation link is link 3. And, finally, when link 3 is the roaming implementation link, there are no links other than the roaming implementation link. Therefore, if the last link in the roaming order is the roaming implementation link, the determination in S504 may be automatically positive. That is, in such a case, if a roaming destination link remains (i.e., if there is still a link in the roaming order that is not a roaming destination for the previous roaming implementation link), the determination in S504 may be automatically positive.

[0061] If a frequency channel of the roaming destination that does not interfere with links other than the roaming link can be selected, that frequency channel is determined as the roaming destination of the roaming link (YES in S504, S505).

[0062] If it is not possible to select a frequency channel of the roaming destination that does not interfere with links other than the roaming link, the roaming destination of the roaming link is determined to be "none" (NO in S504, S506).

[0063] In this case, since 2.4 GHz Link 1 is the first in the roaming order and will be the link to be roamed, a determination is made as to whether it is possible to select a frequency channel at the roaming destination that does not interfere with 5 GHz Link 2. Since the roaming destination AP MLD 107 has the ability to establish 2.4 GHz Link 4 and 5 GHz Link 5, it is possible to select 2.4 GHz Link 4, which does not interfere with 5 GHz Link 2.

[0064] The following cases are possible as cases where S506 is reached when 2.4 GHz Link 1, 5 GHz Link 2, and 6 GHz Link 3 have been established with the roaming source AP MLD 102. That is, the roaming destination AP MLD 107 may have the capability to establish 2.4 GHz Link 4 and 5 GHz Link 5. In this case, if 6 GHz Link 3 is set as the roaming execution link, it is determined whether a roaming destination frequency channel that does not interfere with 2.4 GHz Link 1 and 5 GHz Link 2 can be selected. Because the roaming destination AP MLD 107 has the capability to establish 2.4 GHz Link 4 and 5 GHz Link 5, it cannot select a roaming destination frequency channel that does not interfere with 2.4 GHz Link 1 and 5 GHz Link 2. Therefore, the roaming destination for the roaming execution link is determined to be "none."

[0065] Furthermore, for example, the frequency channel of the roaming destination of the roaming execution link in S504 may be determined based on the frequency gap between the frequency channel of the link with the AP MLD 102 and the frequency channel of the link with the AP MLD 107. For example, the non-AP MLD 103 may determine the frequency channel of the roaming destination based on whether a frequency gap recommended for performing STR operation can be secured between the link with the AP MLD 102 and the link with the AP MLD 107. STR stands for Simultaneous Transmit and Receive. For example, the non-AP MLD 103 may be configured to set a value called Frequency Separation (FS) as the frequency gap recommended for performing STR operation between multiple links and notify the opposing AP of this information. When the non-AP MLD 103 sets FS in this way, the frequency channel of the roaming destination may be determined based on whether the frequency gap indicated by the FS can be secured. In this way, the non-AP MLD 10 may control roaming so that the STR operation is possible in the link with the AP MLD 102 of the roaming source and the link with the AP MLD 107 of the roaming destination.

[0066] After the roaming destinations of the roaming execution links are determined by the processes of S505 and S506, it is determined whether the roaming destinations of all the links have been determined (S507). If the roaming destinations of all the links have been determined, roaming is performed in accordance with the determined roaming order and the frequency channel of the roaming destination (YES in S507, S509). Note that roaming may be performed by disconnecting the connection with the roaming source, deleting the link, establishing a connection with the roaming destination, adding a link, etc.

[0067] If the roaming destinations for all links have not been determined, the roaming execution links are updated in accordance with the roaming order determined in S503 (NO in S507, S508), and the process returns to S504.

[0068] Here, since only the roaming destination frequency channel for Link 1 of 2.4 GHz has been determined, the roaming execution link is updated to Link 2 of 5 GHz.

[0069] Next, since 5 GHz Link 2 will be the roaming execution link, it is determined whether a frequency channel of the roaming destination that does not interfere with 2.4 GHz Link 1 can be selected (S504). Since the roaming destination AP MLD 107 has the ability to establish 2.4 GHz Link 4 and 5 GHz Link 5, it is possible to select 5 GHz Link 5 that does not interfere with 2.4 GHz Link 1. Therefore, 5 GHz Link 5 is determined as the frequency channel of the roaming execution link (YES in S504, S505).

[0070] It is determined again whether the roaming destinations for all links have been determined (S507). Here, the roaming destination frequency channels for 2.4 GHz link 1 and 5 GHz link 2 have been determined, so the roaming destinations for all links have been determined. Therefore, roaming is performed in accordance with the roaming order and roaming destination frequency channels determined in S503 (YES in S507, S509).

[0071] In the above example, roaming is performed after the roaming destinations for all links are determined in S509, but this is not limiting. For example, roaming may be performed at the timing when the roaming destinations for the links are determined. Also, the roaming order for each link is determined in S503, and then the roaming destinations are determined in S504, S505, and S506, but this is not limiting.

[0072] For example, S504, S505, and S506 may be performed first, and the roaming destinations for all links may be determined before S503. Note that in S504, if the number of roaming destination links is greater than the number of roaming source links, two or more roaming destination frequency channels may be available as options. For example, consider a case where a 2.4 GHz link 1 and a 5 GHz link 2 are established with the roaming source AP 102, and the roaming destination AP MLD 107 has the capability to establish links at 2.4 GHz, 5 GHz, and 6 GHz. In this case, if 2.4 GHz link 1 is the roaming execution link, the roaming destination frequency channels that do not interfere with 5 GHz link 2 are 2.4 GHz and 6 GHz. Therefore, in S505, 2.4 GHz and 6 GHz may be compared, and the roaming destination frequency channel may be determined based on communication quality, a predetermined frequency channel order, and communication speed for each device, but this is not limiting.

[0073] In this way, when roaming is performed using multi-link communication, it is possible to select a frequency channel that does not cause communication interference based on the frequency channel of the link between the roaming source AP and the roaming destination AP.

[0074] Furthermore, in the example shown in FIG. 5, a case is assumed in which there is only one AP MLD 107 that is the roaming destination AP, but this is not limiting. That is, there may be a situation in which there are multiple AP MLDs that can be roaming destinations. In such a situation, an AP MLD among the multiple AP MLDs for which two or more links are determined as the roaming destination in S505 may be determined as the AP MLD of the final roaming destination. Alternatively, an AP MLD among the multiple AP MLDs for which the maximum number of links are determined as the roaming destination in S505 may be determined as the AP MLD of the final roaming destination. Alternatively, if, as a result of performing the process shown in FIG. 5 for one AP MLD among the multiple AP MLDs that can be roaming destinations, the number of roaming execution links for which the roaming destination is determined in S505 is one or less, another AP MLD may be considered. That is, the process shown in FIG. 5 may be performed for another AP MLD.

[0075] 5, it is assumed that at least two links are established with the AP MLD 107, which is the roaming destination AP. However, there may be cases where the determination in S506 is made for multiple roaming execution links and the determination in S505 is made for only one roaming execution link. That is, as a result of executing the process shown in FIG. 5, there may be cases where the number of roaming execution links for which the roaming destination is determined in S505 is one or less. In this case, multilink communication is not performed with the AP MLD 107, which is the roaming destination AP. However, in such cases, the above-mentioned communication interference may be exceptionally tolerated in order to prioritize multilink communication.

[0076] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0077] Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0078] In addition, the following supplementary notes are disclosed regarding the above-described embodiment. [Appendix 1] A communication device, a communication means capable of multi-link communication using a plurality of links each using a different frequency channel with another communication device; roaming means for switching from a first state in which multi-link communication is being performed with a first other communication device to a second state in which multi-link communication is being performed with a second other communication device; a control means for controlling, when switching from the first state to the second state, to pass through a third state in which communication with the first other communication device is possible via a first link and communication with the second other communication device is possible via a second link; The control means controls the frequency channel of the first link so that the frequency channel of the second link does not interfere with each other in the third state. A communication device comprising: [Appendix 2] The control means controls the frequency channel of the first link and the frequency channel of the second link so that the frequency channel has an interval equal to or greater than a predetermined frequency. 2. The communication device according to claim 1, [Appendix 3] The predetermined frequency is the frequency separation. 3. The communication device according to claim 2, [Appendix 4] The control means controls the first link and the second link so that STR (Simultaneous Transmit and Receive) is possible. 4. The communication device according to claim 1, wherein: [Appendix 5] When switching from the first state to the third state, the control means performs control so as to disconnect the third link with the first other communication device and then establish the second link with the second other communication device. 5. The communication device according to claim 1, wherein: [Appendix 6] The frequency channel of the third link and the frequency channel of the second link are frequency channels in the same frequency band. 6. The communication device according to claim 5, [Appendix 7] The frequency channel of the third link and the frequency channel of the second link are the same frequency channel. 7. The communication device according to claim 5 or 6, [Appendix 8] further comprising an acquisition means for acquiring information indicating communication quality of each link used with the first other communication device; The control means selects the third link to be disconnected when switching from the first state to the third state based on the information acquired by the acquisition means. 8. The communication device according to claim 5, wherein: [Appendix 9] The first state is a state in which multi-link communication is being performed with the first other communication device using only two links, and the third state is a state in which multi-link communication is being performed with the second other communication device using only two links. 9. The communication device according to claim 1, wherein: [Appendix 10] When switching from the third state to the second state, the control means performs control so as to disconnect the first link with the first other communication device and then establish a fourth link with the second other communication device. 10. The communication device according to any one of Supplementary Note 1 to Supplementary Note 9, [Appendix 11] When there are a plurality of communication device candidates that can be the second other communication device, the second other communication device is selected from among the plurality of communication device candidates based on information on the frequency channel related to each of the communication device candidates. 11. The communication device according to claim 1, wherein: [Appendix 12] The wireless communication system further includes a determining unit that determines a frequency channel of the second link based on a frequency channel of the first link when switching from the first state to the third state. 12. The communication device according to claim 1, wherein: [Explanation of symbols]

[0079] 102, 107: AP MLD, 103: Non-AP MLD, 201: storage unit, 202: control unit, 206: communication unit, 301: wireless LAN control unit, 303: roaming control unit

Claims

1. A communication device, a communication means capable of multi-link communication using a plurality of links each using a different frequency channel with another communication device; roaming means for switching from a first state in which multi-link communication is being performed with a first other communication device to a second state in which multi-link communication is being performed with a second other communication device; a control means for controlling, when switching from the first state to the second state, to pass through a third state in which communication with the first other communication device is possible via a first link and communication with the second other communication device is possible via a second link; The control means controls the frequency channel of the first link so that the frequency channel of the second link does not interfere with each other in the third state. A communication device comprising:

2. The control means controls the frequency channel of the first link and the frequency channel of the second link so that the frequency channel has an interval equal to or greater than a predetermined frequency.

2. The communication device according to claim 1.

3. The predetermined frequency is the Frequency Separation.

3. The communication device according to claim 2.

4. The control means controls the first link and the second link so that STR (Simultaneous Transmit and Receive) operation is possible.

2. The communication device according to claim 1.

5. When switching from the first state to the third state, the control means controls so as to disconnect the third link with the first other communication device and then establish the second link with the second other communication device.

2. The communication device according to claim 1.

6. The frequency channel of the third link and the frequency channel of the second link are frequency channels in the same frequency band.

6. The communication device according to claim 5.

7. The frequency channel of the third link and the frequency channel of the second link are the same frequency channel.

6. The communication device according to claim 5.

8. further comprising an acquisition means for acquiring information indicating communication quality of each link used with the first other communication device; The control means selects the third link to be disconnected when switching from the first state to the third state based on the information acquired by the acquisition means.

6. The communication device according to claim 5.

9. The first state is a state in which multi-link communication using only two links is being performed with the first other communication device, and the third state is a state in which multi-link communication using only two links is being performed with the second other communication device.

2. The communication device according to claim 1.

10. When switching from the third state to the second state, the control means performs control so as to disconnect the first link with the first other communication device and then establish a fourth link with the second other communication device.

2. The communication device according to claim 1.

11. When there are a plurality of communication device candidates that can be the second other communication device, the second other communication device is selected from among the plurality of communication device candidates based on information on the frequency channel related to each of the communication device candidates.

2. The communication device according to claim 1.

12. The radio communication system further includes a determining unit that determines a frequency channel of the second link based on a frequency channel of the first link when switching from the first state to the third state.

12. The communication device according to claim 1, wherein the first and second communication units are connected to each other.

13. The communication device is a communication device capable of performing communication in accordance with the IEEE 802.11 series standard.

2. The communication device according to claim 1.

14. A method for controlling a communication device, comprising: a communication step of performing multi-link communication with another communication device using a plurality of links each using a different frequency channel; a roaming step of switching from a first state in which multi-link communication is being performed with a first other communication device to a second state in which multi-link communication is being performed with a second other communication device; a control step of controlling, when switching from the first state to the second state, to pass through a third state in which communication with the first other communication device is possible via a first link and communication with the second other communication device is possible via a second link; In the control step, control is performed so that the frequency channel of the first link and the frequency channel of the second link do not interfere with each other in the third state. A method for controlling a communication device.

15. A program for causing a computer to function as the communication device control method according to claim 14.

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