Communication device, control method, and program

Abstract

This communication device performs multi-link communication with another communication device, the multi-link communication using a plurality of links respectively using different frequency channels. The communication device switches from a first state in which the multi-link communication is performed with a first other communication device to a second state in which the multi-link communication is performed with a second other communication device. When switching from the first state to the second state, the communication device performs control so as to go through a third state in which communication can be performed with the first other communication device via a first link and communication can be performed with the second other communication device via a second link, and performs control such 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.

Description

Communication device, control method, and program

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

[0002] With the recent increase in the amount of data being communicated, development of communication technologies such as wireless LANs (Local Area Networks) is progressing. The Institute of Electrical and Electronics Engineers (IEEE) 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. In the IEEE 802.11 Working Group (WG), which formulates the IEEE 802.11bn standard, the UHR SG will determine the goals and scope of the standard, and the TGbn will specify the detailed technical content to be included in the standard. UHR SG is an abbreviation for Ultra High Reliability Study Group. TGbn is an abbreviation for Task Group bn.

[0003] The IEEE 802.11be standard and its successor, the IEEE 802.11bn standard, consider multi-link communication in which one access point (AP) establishes multiple wireless links with one station (STA / non-AP STA) to communicate with them. In multi-link communication, for example, the AP establishes a connection with the STA using multiple frequency channels in the 2.4 GHz, 5 GHz, or 6 GHz frequency band, and communicates in parallel using each frequency channel.

[0004] JP 2018-050133 A

[0005] Roaming technology is known for wireless communication conforming to the IEEE 802.11 standard. Roaming refers to a process in which a station connected to an access point (AP) switches its connection to another access point (AP). For example, if a station becomes far from the AP to which it is currently connected, it can switch its connection to another AP that is located closer.

[0006] However, when roaming while maintaining multi-link communication, frequency channel collisions may occur between link communication with the roaming source AP and 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 the present invention is to provide a mechanism for preventing communication interference when roaming while maintaining multi-link communication.

[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 a plurality of 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.

[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.

[0010] It is a diagram showing an example of a network configuration. It is a diagram showing an example of a hardware configuration of a communication device. It is a diagram showing an example of a functional configuration of a communication device. It is a diagram outlining multi-link communication and roaming. It is a flowchart showing an example of processing of a communication device according to an embodiment.

[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] 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 IEEE 802.11be (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 IEEE 802.11 standards (for example, at least one of the IEEE 802.11a / 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 available to each communication device 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 that comply with the standards can perform wireless communication using these frequency channels.

[0017] The IEEE 802.11 series of standards defines multiple frequency channels in each frequency band, such as the 2.4 GHz band, the 5 GHz band, and the 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, a single frequency channel can utilize a bandwidth of 40 MHz or more. In the 60 GHz band, the bandwidth of the frequency channel is defined as 2.16 GHz.

[0018] 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.

[0019] In this embodiment, it is assumed that the AP MLD 102 as a roaming source constructs the network 101, establishes a link 104 and a link 105 with the non-AP MLD 103, and executes multi-link communication.

[0020] Also, it is assumed that the AP MLD 107 as a roaming destination constructs a network 106, and establishes a link 108 and a link 109 with the non-AP MLD 103 to perform multi-link communication.

[0021] In this embodiment, when there is no need to particularly distinguish between 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 status and communication status of the Non-AP MLD 103.

[0022] 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 a link 104 using a first frequency channel in the 2.4 GHz band and a 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 the link 104 and the link 105 in parallel.

[0023] 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. While the above example shows two links being established, three or more links may be established in parallel. For example, in addition to the 2.4 GHz band link 104 and the 5 GHz band link 105, an additional 6 GHz band link (not shown) may be established between the AP MLD 102 and the non-AP MLD 103.

[0024] 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.

[0025] 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. 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.

[0026] 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.

[0027] 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 allows for communication of 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.

[0028] In addition to the IEEE 802.11 series standard, the AP MLD 102 and the Non-AP MLD 103 may be compliant 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 be compatible with a wired communication standard such as a wired LAN.

[0029] The AP MLD 102 may be, for example, but is not limited to, a wireless LAN router or a personal computer (PC). The non-AP MLD 103 may be, for example, but is not limited to, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, a headset, etc. The AP MLD 102 and the non-AP MLD 103 may be information processing devices such as wireless chips capable of performing wireless communication compliant with the IEEE 802.11bn standard.

[0030] The above explanations of the AP MLD 102 and the non-AP MLD 103 and the links 104 and 105 also apply to the AP MLD 107 and the non-AP MLD 103 and the links 108 and 109 .

[0031] 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.

[0032] When the Non-AP MLD 103 according to this embodiment roams during multi-link communication, it establishes a wireless link with the AP MLD 107 at the roaming destination while maintaining a wireless link with the AP MLD 102 at the roaming source. 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 AP MLD 107 at the roaming destination while maintaining a wireless link with the AP MLD 102 at the roaming source will be described with reference to FIG. 1, but the present invention is not limited to this.

[0033] 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 the link 104 and then establishes a link 108 with the AP MLD 107. In this state, the link 105 with the AP MLD 102 remains maintained.

[0034] 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.

[0035] In the above description, the procedure is such that the link with the AP MLD 102 of the roaming source is disconnected and then the link with the AP MLD 107 of the roaming destination is established, but the present invention is not limited to this.

[0036] Alternatively, the procedure may be such that the link with the AP MLD 102 of the roaming source is disconnected after the link with the AP MLD 107 of the roaming destination is established, or the disconnection and connection may be performed simultaneously.

[0037] 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 establish communication on the same frequency channel. In this case, the communications of the link 105 and the link 108 may interfere with each other.

[0038] 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 communications 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 communications with the roaming source from among the frequency channels of communication links that can be established. A conceivable 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 device capability information. Possible methods for this include, but are not limited to, a beacon frame, a FILS (Fast Initial Link Setup) Discovery frame, and a Probe Response frame. Another conceivable method is to receive notification of the capabilities of the roaming destination AP MLD 107 from the roaming source AP MLD 102. In this case, a BSS Transition Management (BTM) Request frame may be considered, but is not limited to this.

[0039] (Configuration of communication device) An example of the hardware configuration of the communication device (AP MLDs 102, 107 and Non-AP MLD 103) according to this embodiment will be described using Fig. 2. The communication device includes, as its hardware configuration, for example, a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207.

[0040] 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.

[0041] 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 such as generating data and signals to be transmitted in communication with other communication devices, in addition to controlling the entire communication device. The control unit 202 may be configured to execute processes such as 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 execute processes such as 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.

[0042] The control unit 202 also 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.

[0043] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user. The output from the output unit 205 includes, for example, at least one of a display on a screen, an audio output from a speaker, and a vibration output. Note that both the input unit 204 and the output unit 205 may be implemented by a single module, such as a touch panel.

[0044] Furthermore, the input unit 204 and the output unit 205 may each be built into the communication device, or may be configured as an external device connected to the communication device.

[0045] 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. The communication unit 206 may also 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 the control unit 202, for example. The communication device may have multiple communication units 206. When 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. 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 a single 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 NFC and Bluetooth (registered trademark) in addition to the IEEE 802.11bn standard, the communication device may control wireless communication in accordance with these communication standards. Furthermore, if the communication device is capable of executing wireless communication in accordance with multiple communication standards, the communication device may have separate communication units and antennas corresponding to 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.

[0046] Antenna 207 is an antenna that enables communication in various frequency bands, such as the sub-GHz band, 2.4 GHz band, 5 GHz band, 6 GHz band, and 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, each corresponding to a different frequency band. If the communication device has multiple antennas, it may have one communication unit 206 for each of the multiple antennas, or multiple communication units 206 corresponding to each of the multiple antennas. 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 capable of performing communication using, for example, MIMO (Multi-Input and Multi-Output).

[0047] Next, an example of the functional configuration of the communication device of this embodiment will be described using 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. Furthermore, multiple identical functional units may be provided. For example, multiple wireless LAN control units 301 may exist.

[0048] 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 standard 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 obtain 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 a wireless frame from another communication device may be restricted by settings stored in the storage unit 201. Furthermore, this control information may be changed by a user setting from the UI control unit 304. The roaming control unit 303 controls roaming according to this embodiment. Specifically, it determines the frequency channel to use for roaming and the link to use for roaming.

[0049] 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 stores programs and data for operating the communication device in the storage unit 201 and controls the reading of these programs and data from the storage unit 201.

[0050] (Outline of Multi-Link Communication) Next, an overview of multi-link communication and roaming will be given using 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.

[0051] 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 to third frequency channels are, for example, any of the frequency channels in the sub-GHz band, 2.4 GHz band, 3.6 GHz band, 4.9 and 5 GHz bands, 6 GHz band, and 60 GHz band. Hereinafter, 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.

[0052] Furthermore, the first AP 410 to the third AP 412 of the AP MLD 107 have the same functions as 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.

[0053] When roaming from AP MLD 102 to AP MLD 107 in response to a change in the communication environment due to, 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 occur simultaneously.

[0054] 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 a part of the processing shown below may be executed by dedicated hardware provided in the Non-AP MLD 103.

[0055] 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 AP MLD 102 issues a roaming instruction to the Non-AP MLD 103, or when some other trigger occurs.

[0056] In the explanation of this process, it is assumed that the Non-AP MLD 103 and the AP MLD 102 have established a 2.4 GHz link 1 and a 5 GHz link 2, and that the AP MLD 107 has the capability to establish a 2.4 GHz link 4 and a 5 GHz link 5.

[0057] 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 these.

[0058] 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 channels on which the AP can communicate (S502). Here, it is assumed that it has been confirmed that the AP has the capability to establish a 2.4 GHz link 4 and a 5 GHz link 5.

[0059] Next, the non-AP MLD 103 determines the roaming order of the links established with the AP MLD 102 (S503). The process 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 speed.

[0060] In this process, the order is determined based on communication quality, and the communication quality is determined by a Received Signal Strength Indicator (RSSI). In addition to RSSI, the communication quality can be determined by a Signal-to-Noise Ratio (SNR), the number of APs present in a frequency channel, a Receive Channel Power Indicator (RCPI), or the like, but is not limited thereto.

[0061] 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, link 1, then link 2.

[0062] 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).

[0063] Note that the number of "links other than the roaming link" in S504 decreases each time the roaming link is updated (S508) after the processing of S505 or S506. For example, if the roaming order is link 1, link 2, and link 3, when link 1 is the roaming link, the links other than the roaming link are link 2 and link 3. Next, when link 2 is the roaming link, the link other than the roaming link is link 3. Finally, when link 3 is the roaming link, there are no links other than the roaming link. Therefore, if the last link in the roaming order is the roaming 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 link), the determination in S504 may be automatically positive.

[0064] 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).

[0065] 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).

[0066] In this case, since the 2.4 GHz link 1 is the first in the roaming order and is the link to be roamed, it is determined whether it is possible to select a frequency channel at the roaming destination that does not interfere with the 5 GHz link 2. Since the AP MLD 107 at the roaming destination has the ability to establish the 2.4 GHz link 4 and the 5 GHz link 5, it is possible to select the 2.4 GHz link 4 that does not interfere with the 5 GHz link 2.

[0067] The following cases may occur 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 frequency channel at the roaming destination 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 is unable to select a frequency channel at the roaming destination 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."

[0068] 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. Note that 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 an 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 STR operation is possible in the link between the Non-AP MLD 102, which is the roaming source, and the link between the Non-AP MLD 102 and the AP MLD 107, which is the roaming destination.

[0069] After the roaming destinations of the roaming link 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.

[0070] 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.

[0071] Here, since only the roaming destination frequency channel of link 1 of 2.4 GHz has been determined, the roaming link is updated to link 2 of 5 GHz.

[0072] Next, since the 5 GHz link 2 is the roaming link, it is determined whether a frequency channel of the roaming destination that does not interfere with the 2.4 GHz link 1 can be selected (S504).

[0073] Since the roaming destination AP MLD 107 has the capability to establish 2.4 GHz link 4 and 5 GHz link 5, it can select 5 GHz link 5, which does not interfere with 2.4 GHz link 1. Therefore, it determines 5 GHz link 5 as the frequency channel for the roaming execution link (YES in S504, S505).

[0074] It is determined again whether the roaming destinations for all links have been determined (S507). In this case, 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).

[0075] In the above example, roaming is performed after the roaming destinations of all links are determined in S509, but this is not limited to this. For example, roaming may be performed at the timing when the roaming destinations of the links are determined. Also, the roaming order of each link is determined in S503, and then the roaming destinations are determined in S504, S505, and S506, but this is not limited to this.

[0076] 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.

[0077] 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.

[0078] Furthermore, in the example shown in FIG. 5 , a case is assumed in which there is only one AP MLD 107 as the roaming destination AP, but this is not limited to this. 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 final roaming destination AP MLD. Alternatively, an AP MLD among the multiple AP MLDs for which the largest number of links are determined as the roaming destination in S505 may be determined as the final roaming destination AP MLD. 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.

[0079] Furthermore, the example shown in FIG. 5 assumes 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 will not be 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.

[0080] The present invention can also be realized by supplying a program that realizes one or more of the 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.The present invention can also be realized by a circuit (e.g., an ASIC) that realizes one or more of the functions.

[0081] 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.

[0082] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0083] This application claims priority based on Japanese Patent Application No. 2024-090972, filed on June 4, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A communications device comprising: communications means capable of multi-link communications with other communications devices using multiple links, each using a different frequency channel; roaming means for switching from a first state in which multi-link communications are performed with a first other communications device to a second state in which multi-link communications are performed with a second other communications device; and control means for controlling, when switching from the first state to the second state, to pass through a third state in which communications with the first other communications device are possible via a first link and communications with the second other communications device are possible via a second link, wherein the control means controls so that, in the third state, interference does not occur between the frequency channel of the first link and the frequency channel of the second link.

2. The communication device according to claim 1, wherein said control means controls the frequency channel of said first link and the frequency channel of said second link so that there is an interval of at least a predetermined frequency.

3. The communication device according to claim 2, wherein the predetermined frequency is a frequency separation.

4. A communication device according to any one of claims 1 to 3, characterized in that the control means controls the first link and the second link so that STR (Simultaneous Transmit and Receive) operation is possible.

5. A communication device as described in any one of claims 1 to 4, characterized in that when switching from the first state to the third state, the control means controls so that the third link with the first other communication device is disconnected and then the second link with the second other communication device is established.

6. The communication device according to claim 5, wherein the frequency channel of the third link and the frequency channel of the second link are frequency channels in the same frequency band.

7. A communication device according to claim 5 or 6, characterized in that the frequency channel of the third link and the frequency channel of the second link are the same frequency channel.

8. A communication device as described in any one of claims 5 to 7, further comprising an acquisition means for acquiring information indicating the communication quality of each link used between the first other communication device, and the control means selecting 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.

9. A communication device as described in any one of claims 1 to 8, characterized in that the first state is a state in which multi-link communication is being carried out with the first other communication device using only two links, and the third state is a state in which multi-link communication is being carried out with the second other communication device using only two links.

10. A communication device as described in any one of claims 1 to 9, characterized in that when switching from the third state to the second state, the control means controls so that the first link with the first other communication device is disconnected and then a fourth link with the second other communication device is established.

11. A communication device as described in any one of claims 1 to 10, characterized in that when there are multiple communication device candidates that can become the second other communication device, the second other communication device is selected from among the multiple communication device candidates based on information on the frequency channel related to each communication device candidate.

12. A communication device according to any one of claims 1 to 11, further comprising a determination means for determining the frequency channel of the second link based on the frequency channel of the first link when switching from the first state to the third state.

13. The communication device according to any one of claims 1 to 12, characterized in that the communication device is capable of performing communication in accordance with the IEEE 802.11 series standards.

14. A control method for a communication device, comprising: a communication step of executing multi-link communication using multiple links, each using a different frequency channel, with another communication device; 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; and 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, wherein 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.

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

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