Communication device, control method, and program

Abstract

To provide a technique for enhancing performance obtained by utilizing multi-link communication in a system in which multi-link communication is performed.SOLUTION: A communication device can perform multi-link communication with another communication device using a plurality of links respectively corresponding to a plurality of frequencies, in compliance with the IEEE802.11 series standards. The communication device includes selection means for selecting a frequency to be associated with an additional link based on predetermined conditions from a plurality of candidate frequencies when increasing the number of links used in parallel in multi-link communication, and notification means for notifying the other communication device of the frequency selected by the selection means.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to frequency selection technology in a communication device capable of using a plurality of links in parallel.

Background Art

[0002] With the recent increase in the amount of data to be communicated, the development of communication technologies such as wireless LAN (Local Area Network) has been promoted. As the main communication standards for wireless LAN, the IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard series is known. The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax / be.

[0003] For example, in the IEEE 802.11be standard, a multi-link communication is established in which one access point (AP) establishes a plurality of links with one station (STA) using a plurality of different frequencies and uses them in combination for communication. Each of the plurality of links can be established using frequencies belonging to the same frequency band, for example, any of the 2.4 GHz band, 3.6 GHz band, 4.9 and 5 GHz bands, and 6 GHz band. Also, each of the plurality of links can be established using frequencies belonging to different frequency bands. An AP or STA corresponding to multi-link communication is called an AP MLD (Multi-Link Device) or STA MLD. Patent Document 1 describes a technique for improving the utilization efficiency of radio resources in multi-link communication.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention provides a frequency selection technique for enhancing the performance obtained by using multi-link communication when adding or deleting links in a system where multi-link communication is performed.

Means for Solving the Problem

[0006] A communication device according to an aspect of the present invention is a communication device capable of performing multi-link communication using a plurality of links corresponding to each of a plurality of frequencies compliant with the IEEE802.11 series standards with another communication device, and when increasing the number of links used in parallel in the multi-link communication, selection means for selecting a frequency associated with an additional link based on a predetermined condition from among a plurality of candidate frequencies, and notification means for notifying the other communication device of the frequency selected by the selection means.

Effect of the Invention

[0007] In a system where multi-link communication is performed, the performance obtained by using multi-link communication can be enhanced when adding or deleting links.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] (System Configuration) FIG. 1 shows a configuration example of a wireless communication system according to this embodiment. This wireless communication system includes, for example, an access point (AP) 101 and a station (STA) 102. The AP 101 constitutes a wireless network 110. Also, the STA participates in the wireless network 110. That is, the wireless network 110 indicates the range (communication range) within which the AP 101 can perform wireless communication with other communication devices. In this embodiment, the STA 102 is located within the communication range of the AP 101. The AP 101 and the STA 102 may be collectively referred to as a communication device 100 without distinction. The AP 101 may include, but is not limited to, a wireless LAN router, a personal computer (PC), etc. Also, the STA 102 may include, but is not limited to, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, etc. Note that the AP 101 and the STA 102 may be information processing devices such as wireless chips that can perform wireless communication compliant with the IEEE802.11be standard. Also, although the wireless network in FIG. 1 is configured by one AP 101 and one STA 102, the number and arrangement of the AP 101 and the STA 102 are not limited to this. For example, two or more STAs 102 may be connected to the AP 101, or there may be two or more APs 101.

[0011] AP101 and STA102 are wireless communication devices capable of performing wireless communication compliant with the IEEE802.11 series of standards. The IEEE802.11 series of standards may include the IEEE802.11a / b / g / n / ac / ax / be / bn standards. That is, AP101 and STA102 may correspond to at least any one of these standards including the IEEE802.11be standard. Note that IEEE is an abbreviation for Institute of Electrical and Electronics Engineers. In addition to the IEEE802.11 series of standards, AP101 and STA102 may also correspond to other communication standards such as Bluetooth (registered trademark), NFC, UWB, ZigBee, MBOA, etc. Note that UWB is an abbreviation for Ultra Wide Band, and MBOA is an abbreviation for Multi Band OFDM Alliance. Also, NFC is an abbreviation for Near Field Communication. UWB includes wireless USB, wireless 1394, WiNET, etc. In addition, AP101 and STA102 may correspond to the communication standards of wired communication such as wired LAN.

[0012] AP101 and STA102 can communicate using frequencies in the 2.4Hz band, 3.6GHz band, 5GHz band, 6GHz band, and the 45GHz band and 60GHz band called millimeter waves. The frequency bands used by AP101 and STA102 are not limited to these, and different frequency bands such as the Sub1GHz band may be used, for example. Also, AP101 and STA102 can communicate using bandwidths of 20MHz, 40MHz, 80MHz, 160MHz, 320MHz, 540MHz, 640MHz, 1080MHz, and 2160MHz. The bandwidths used by AP101 and STA102 are not limited to these, and different bandwidths such as 240MHz or 4MHz may be used, for example.

[0013] AP101 and STA102 can implement multi-user communication that multiplexes the signals of multiple users by performing OFDMA communication compliant with the IEEE802.11be standard. Multi-user communication can also be called MU communication. OFDMA is an abbreviation for Orthogonal Frequency Division Multiple Access. In OFDMA communication, the available frequency band is divided into multiple RUs (Resource Units) and allocated for communication between AP101 and each STA102. Since each RU is allocated so as not to overlap with each other, AP101 can communicate with multiple STA102 in parallel in the available frequency band. Also, AP101 and STA102 can perform MIMO (Multiple-Input And Multiple-Output) communication. In this case, AP101 and STA102 each have multiple antennas, and one can send signals of multiple different streams from each antenna using the same frequency channel. The receiving side simultaneously receives the signals of multiple streams using multiple antennas, separates and decodes the signals of each stream. In this way, by performing MIMO communication, AP101 and STA102 can communicate more data in the same time compared to the case where MIMO communication is not performed.

[0014] Multi-Link communication can be performed between AP101 and STA102 by establishing multiple links using different frequencies for each. For example, STA102 can establish three links, Link 121 to Link 123, with AP101. Note that the number of multi-links established between AP101 and STA102 can be two, or four or more. For example, in addition to Links 121 to 123 between AP101 and STA102, a fourth link may be further established. For example, when Links 121 to 123 are established between AP101 and STA102, one or more of the links may be disconnected, and multi-link communication may be continued using the remaining one or more links. AP101 can notify the STA102 connected to itself of the number of links that can be used in parallel in multi-link communication with itself. Also, AP101 can notify STA102 of the frequencies that can be used in multi-link communication with itself. That is, AP101 and STA102 can perform multi-link communication using any of the frequencies notified by AP101 within the range of the number of links that can be used in parallel notified by AP101. The frequencies used in Links 121 to 123 can be frequencies belonging to the 5 GHz band, 6 GHz band, and 2.4 GHz band, respectively. Also, the frequencies used in these links may be frequencies belonging to other frequency bands. For example, two or three of Links 121 to 123 may use a plurality of different frequencies included in the same frequency band. In this case, for example, Link 121 may be set to Channel 36 in the 5 GHz band, and Link 122 may be set to Channel 161 in the 5 GHz band to establish a multi-link. Note that in this embodiment, "ch" is identification information used to identify a specific frequency channel. Note that between AP101 and STA102, a plurality of links using frequencies in the same frequency band and a link using a frequency in a different frequency band from these links may be mixed. For example, STA102 may establish Link 121 using Channel 5 in the 6 GHz band and Link 122 using Channel 213 in the 6 GHz band with AP101, and may further establish Link 123 using Channel 6 in the 2.4 GHz band.Also, the frequencies used for each link may be frequencies belonging to frequency bands other than the above. By establishing a plurality of links with different frequencies between AP101 and STA102, even when one link is congested, AP101 can communicate with STA102 via the other link. Thereby, AP101 can prevent significant throughput degradation and delay in communication with STA102.

[0015] A Link ID is assigned to each link as an identifier for identifying each link. Each link may constitute a different network from each other. In this case, in the network 110 configured by AP101, a network may exist for each link. For example, when STA102 participates in each of the 5GHz band, 6GHz band, and 2.4GHz band networks respectively constituted by links 121 to 123, Link ID = 1, 2, and 3 may be assigned to each link respectively. In this case, the Link ID may have both a function of identifying a link and a function of identifying a network. Note that these values of Link ID are just examples, and other values other than 1, 2, and 3 may be assigned respectively. Also, different Link IDs may be assigned to each of the plurality of STA102s using the same frequency.

[0016] When performing multi-link communication between AP101 and STA102, they may be affected by interference with each other depending on the combination of frequencies used for each link. For example, when the frequencies used for each link are adjacent to each other, the transmission signal in one link may leak into the other link as interference, which may cause the reception in the other link to fail. To avoid such problems, the IEEE802.11be standard defines the STR operation and the NSTR operation. STR and NSTR are abbreviations for Simultaneous Transmit and Receive and Nonsimultaneous Transmit and Receive, respectively. And the combination of each link constituting the multi-link communication is distinguished into a combination of links capable of the STR operation (STR link pair) and a combination of links incapable of the STR operation (NSTR link pair). In two links that are an STR link pair, transmission and reception, etc. can be performed independently of the operations in the other link. On the other hand, in two links that are an NSTR link pair, channel access control can be performed in consideration of the occurrence of interference with the other link. For example, even when the right to transmit is acquired in one link, the processing can be executed according to the operating status of the other link without immediately starting the transmission. As an example, even when the right to transmit is acquired in one link, an operation of delaying the transmission process until the right to transmit in the other link is acquired can be executed. Also, in order to avoid interference occurring between NSTR link pairs, control such as aligning the timing of starting transmission and the timing of ending transmission in each link can be executed. Thus, there are certain restrictions on the operations of each of the links constituting the NSTR link pair. Note that when the NSTR link pair is included in the link used for multi-link communication, AP101 and STA102 can notify the target link to the communication device on the other side using a frame including the NSTR Indication Bitmap subfield.Note that AP101 and STA102 can notify information on the STR operation of the other party using the Frequency Separation For STR / AP MLD Type Indication subfield. In the Frequency Separation For STR / AP MLD Type Indication subfield, for example, the frequency interval at which the STR operation is possible can be expressed as (N - 1) × 80 MHz. That is, when the value of N in this subfield is 2, the frequency interval at which the STR operation is possible is 80 MHz. In this way, the frequency interval at which the STR operation is possible can be notified by the Frequency Separation For STR / AP MLD Type Indication subfield.

[0017] As described above, by performing multi-link communication between AP101 and STA102, an improvement in throughput and delay is expected. On the other hand, in order to perform multi-link communication, it is necessary to operate a plurality of wireless interfaces, so the power consumption may increase in each communication device 100. In order to suppress the increase in power consumption, it is conceivable to control the number of links that can be used according to the communication environment. However, the performance of multi-link communication may be impaired by the selection of the frequency associated with the link to be added when increasing the number of links to be used in parallel, or the selection of the link to be deleted when reducing the number of links. For example, depending on the frequency associated with the link to be added, interference or restrictions may occur in the communication on the existing link. In this case, the throughput in multi-link communication may not be improved by adding the link, but may rather decrease. On the other hand, depending on the frequency associated with the link to be deleted, the interference or restrictions that have occurred on the existing link may be eliminated, and it may also have a great impact on the performance of multi-link communication such as communication capacity.

[0018] In view of such circumstances, in this embodiment, when the communication device 100 increases the number of links to be used in parallel in multi-link communication, it selects, based on a predetermined condition, a frequency associated with the link to be added from among a plurality of candidate frequencies. For example, the AP 101 can increase or decrease the number of links to be used in parallel in multi-link communication within the range of the number of communication interfaces the own device has. When the AP 101 increases the number of links to be used in parallel in multi-link communication, it determines a frequency to be added corresponding to the increase in the number of links based on a predetermined condition and notifies the STA 102 of the frequency. On the other hand, the STA 102 can increase or decrease the number of links to be used in parallel in multi-link communication within the range of the number of communication interfaces the own device has or within the range of the number of links that the AP 101 to which the own device is connected uses in parallel in multi-link communication. When the STA 102 increases the number of links to be used in parallel in multi-link communication, it determines a frequency to be used for the link to be added based on a predetermined condition from among the available frequencies notified by the AP 101 and requests the AP 101 to add the link using that frequency. Further, when the communication device 100 decreases the number of links in multi-link communication, it selects, based on a predetermined condition, a frequency to stop using from among the frequencies used in multi-link communication. For example, the AP 101 selects a link that satisfies a predetermined condition as a frequency to stop using and notifies the STA 102 of the frequency and the deletion of the link using that frequency. Also, the STA 102 selects a link that satisfies a predetermined condition as a frequency to stop using and requests the AP 101 to delete the link using that frequency. Then, the AP 101 and the STA 102 perform multi-link communication using the updated plurality of links. The predetermined condition for selecting the frequency of the link to be added or stopped using will be described later. For example, it can be set based on the number of devices using that frequency, the availability of the STR operation in multi-link communication, the available frequency bandwidth, the frequency band to which that frequency belongs, and the like. Note that the predetermined conditions may be used individually or in combination.In this way, when increasing or decreasing the number of links used in parallel in multi-link communication, by selecting the frequency associated with the link to be increased or decreased based on a predetermined condition, it becomes possible to enhance the performance obtained by utilizing multi-link communication.

[0019] (Hardware Configuration of Communication Device) FIG. 2 shows an example of the hardware configuration of the communication device 100 (AP101 and STA102) in the present embodiment. The communication device 100 includes a storage unit 201, a control unit 202, a functional unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207. The storage unit 201 is composed of one or more memories such as a ROM and a RAM, and stores computer programs for performing various operations described later, and various information such as communication parameters for wireless communication. ROM and RAM are abbreviations for Read Only Memory and Random Access Memory, respectively. Note that, as the storage unit 201, in addition to memories such as ROM and RAM, storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs may be used. Also, the storage unit 201 may include a plurality of memories and the like.

[0020] The control unit 202 is composed of one or more processors such as a CPU or an MPU, for example, and controls the entire communication device 100 by executing the computer program stored in the storage unit 201. Note that the control unit 202 may control the entire communication device 100 in cooperation with the computer program stored in the storage unit 201 and an OS (Operating System). Also, the control unit 202 generates data and signals (wireless frames) to be transmitted in communication with other communication devices. Note that CPU and MPU are abbreviations for Central Processing Unit and Micro Processing Unit, respectively. Also, the control unit 202 may include a plurality of processors such as a multi-core, and control the entire communication device 100 by the plurality of processors.

[0021] In addition, the control unit 202 controls the functional unit 203 to execute predetermined processes such as wireless communication, imaging, printing, projection, etc. The functional unit 203 is the hardware for the communication device 100 to execute predetermined processes. If the functional unit is a printer, it prints the image data acquired via the communication unit 206. If the functional unit is a scanner, it transmits the image data generated by scanning with the scanner to an external device via the communication unit 206. Further, if the functional unit is a camera, it transmits the image data captured by the camera to an external device via the communication unit 206.

[0022] The input unit 204 receives various operations from the user. For example, it is composed of a touch panel, hard keys, buttons, etc. The output unit 205 performs various outputs to the user via a monitor screen or a speaker. Here, the output by the output unit 205 may be display on the monitor screen, audio output by the speaker, vibration output, etc. Note that both the input unit 204 and the output unit 205 may be realized by one module such as a touch panel. Also, the input unit 204 and the output unit 205 may be integrated with the communication device 100 or may be separate.

[0023] The communication unit 206 controls wireless communication compliant with the IEEE 802.11be standard. In addition to the IEEE 802.11be standard, the communication unit 206 may also control wireless communication compliant with other IEEE 802.11 series standards or wired communication such as wired LAN. The communication unit 206 controls the antenna 207 to transmit and receive signals for wireless communication generated by the control unit 202. If the communication device 100 is compatible with standards such as the NFC standard and the Bluetooth standard in addition to the IEEE 802.11 series standards, it may control wireless communication compliant with these communication standards. Also, if the communication device 100 can execute wireless communication compliant with multiple communication standards, it may be configured to have a communication unit 206 and an antenna 207 corresponding to each communication standard individually. The AP 101 communicates data such as image data, document data, and video data with the STA 102 via the communication unit 206. Note that the antenna 207 may be configured as a separate entity from the communication unit 206 or may be configured as one module together with the communication unit 206.

[0024] The antenna 207 is an antenna capable of communication in bands such as 2.4 GHz, 5 GHz, and 6 GHz. FIG. 2 shows an example where the communication device 100 has one antenna, but the communication device 100 may have two or more antennas. Or it may have different antennas for each frequency band. Also, if the communication device 100 has a plurality of antennas, it may have a communication unit 206 corresponding to each antenna.

[0025] (Functional Configuration of Communication Device) FIG. 3 shows a block diagram of the functional configuration of the communication device 100 (AP101 and STA102) in the present embodiment. This functional configuration can be realized, for example, by one or more processors in the control unit 202 executing a program stored in one or more memories of the storage unit 201. The communication device 100 may include a link number control unit 301, a data frame processing unit 302, and a communication frame transmission / reception unit 303. The link number control unit 301 controls the number of links to be used in parallel in the multi-link communication between the AP101 and the STA102. For example, the link number control unit 301 identifies the number of links to be used in parallel based on information such as the presence, amount, and frequency of data frames generated between the AP101 and the STA102. These information can be measured from statistical quantities generated by the processing of the data frame processing unit 302. When increasing the number of links, the link number control unit 301 selects the frequency corresponding to the additional link and notifies the other communication device via the communication frame transmission / reception unit 303. Also, when decreasing the number of links, the link number control unit 301 selects the frequency to stop using and notifies the other communication device via the communication frame transmission / reception unit 303. The link number control unit 301 selects the frequency that can be used for multi-link communication and the frequency to stop using based on a predetermined condition. The determination as to whether a candidate frequency satisfies the predetermined condition can be executed based on, for example, information acquired by the data frame processing unit 302 or the communication frame transmission / reception unit 303 from the other communication device, or statistical quantities generated by their processing. The STA data frame processing unit 302 generates the data frame to be transmitted and processes the received data frame. When the communication device 100 is the data source, the data frame processing unit 302 generates a data frame. When the communication device 100 is the data destination, the data frame processing unit 302 processes the received data frame. The communication frame transmission / reception unit 303 transmits and receives frames to and from the other communication device. For example, the communication frame transmission / reception unit 303 can execute the transmission and reception of data frames, management frames, control frames, etc. using each of a plurality of links corresponding to a plurality of frequencies.As an example, the communication frame transceiver unit 303 transmits and receives control frames such as Trigger frames, RTS (Request To Send) frames, and CTS (Clear To Send) frames. Also, the communication frame transceiver unit 303 transmits and receives management frames such as Beacon frames, Association frames, Action frames, and BA (Block ACK) frames. Note that the communication frame transceiver unit detects interference from other devices at the frequency used for communication and generates statistical information.

[0026] (Flow of processing) The operation flows of the above-described AP101 and STA102 and the sequence between the AP101 and the STA102 will be described using several embodiments.

[0027] (Embodiment 1) In this embodiment, an operation example when the AP101 increases the number of links used in parallel in multi-link communication will be described. First, it is assumed that the AP101 has set three frequencies as frequencies available for multi-link communication in the network 110 configured by the own device. In this embodiment, these frequencies are referred to as existing available frequencies. That is, when establishing a link with the STA102, the AP101 selects one or more of these three frequencies and establishes a link using that frequency. In this case, the upper limit of the number of links that the AP101 can use for multi-link communication can be 3. Then, in addition to those three existing available frequencies, the AP101 selects a fourth frequency as a frequency available for multi-link communication with the own device. At this time, the AP101 selects the fourth frequency based on a predetermined condition. An example of the predetermined condition for the AP101 to select the fourth frequency will be described below.

[0028] AP101 can use conditions associated with the STR operation as predetermined conditions. For example, AP101 can select a link using each of the existing available frequencies and a frequency on which the STR operation can be executed. As described above, certain restrictions may occur in the operation of each link constituting the NSTR link pair. For example, assume that a combination of a link using the fourth frequency and a link using any of the existing available frequencies is an NSTR link pair that cannot perform the STR operation. In this case, one of the links becomes the Primary Link as the representative link, and a restriction may occur such that data transmission can be performed only when the Primary Link is in a transmissible state. Thus, when the STR operation cannot be performed, data transmission using the Non-primary Link is restricted, resulting in effects such as a delay in data transmission and no improvement in throughput. By adding a fourth frequency on which the STR operation can be performed to a link using an existing available frequency, AP101 enables data transmission and reception with STA102 without any restrictions between the respective links. Thereby, effects such as reduction of data transmission delay and improvement in throughput commensurate with the addition of the link can be obtained. For example, AP101 measures in advance the interference power between each of the frequencies that each communication interface of the own device can use, and stores a combination of frequencies for which the measured interference power is below a predetermined threshold (the STR operation is possible). Then, based on this combination, when adding a frequency, AP101 identifies a link using each of the existing available frequencies and a frequency on which the STR operation can be executed. The interference power between each frequency can be measured by the received power of the signal received at the other frequency when a transmission signal is output at one frequency. Also, generally, the interference power between each frequency decreases as the frequency interval increases. Therefore, when a frequency for which the interference power is below a predetermined threshold is identified for a frequency used in a certain existing link, a frequency with a larger frequency interval than that frequency can be a frequency on which the STR operation can be performed with the existing link.When AP101 uses conditions associated with the STR operation as predetermined conditions, they may be conditions associated with the STR operation in AP101, or may be conditions associated with the STR operation in STA102 connected to the own device. Also, when a plurality of STA102 are connected to AP101, a frequency that satisfies the predetermined conditions for all STA102 may be selected, or a frequency that satisfies the predetermined conditions for some STA102 may be selected. For example, when there is no frequency at which the STR operation is possible for all STA102, a frequency at which the STR operation is possible for more STA102 may be selected. The predetermined conditions associated with the STR operation may be used in combination with other conditions, and when there are a plurality of candidate frequencies, a frequency that satisfies the predetermined conditions associated with the STR operation may be preferentially selected.

[0029] In addition, AP101 can select the frequency to be added so that the number of STR link pairs in STA102 increases. For example, AP101 can select a frequency so that the NSTR link pairs in STA102 are resolved. AP101 can obtain information on the NSTR link pairs in STA102 by receiving a frame including the NSTR Indication Bitmap field from STA102. When there are NSTR link pairs in STA102, AP101 can select a frequency whose frequency interval from the frequencies used in these links exceeds a predetermined threshold. For example, the predetermined threshold can be the frequency interval required for STA102 to perform the STR operation. For example, AP101 adds a frequency with a frequency interval exceeding the predetermined threshold from any of the NSTR link pairs as the fourth frequency. Then, STA102 adds a link using this fourth frequency and deletes any of the links included in the NSTR link pairs. As a result, the NSTR link pairs in STA102 are resolved and the number of STR link pairs increases. Also, based on the information on the NSTR link pairs obtained from STA102, AP101 can recognize the conditions under which NSTR link pairs occur in STA102. For example, AP101 can estimate the frequency interval in which NSTR link pairs occur based on the frequency interval of the frequencies used in the NSTR link pairs. For example, AP101 stores the frequency interval in the NSTR link pairs obtained from STA102, and when adding a new frequency, can select a frequency whose frequency interval from the existing available frequencies is equal to or greater than this frequency interval. The frequency interval specified in this way can be used under other predetermined conditions. Note that AP101 can obtain the frequency interval in which the STR operation is possible using the Frequency Separation For STR / AP MLD Type Indication subfield. When adding a new frequency, AP101 can select a frequency whose frequency interval from the existing available frequencies is equal to or greater than this frequency interval.The NSTR Indication Bitmap field and the Frequency Separation For STR / AP MLD Type Indication subfield may be used in combination.

[0030] As a predetermined condition, AP101 can use a condition associated with the available frequency bandwidth at a candidate frequency. For example, by selecting a frequency with a wide available bandwidth for communication, AP101 can increase the relative amount of traffic that can be transmitted and received, thereby enhancing the effect of increasing the number of links used in parallel for multi-link communication. For example, assume that the candidate frequencies that can be added as the fourth frequency are Channel 36 in the 5 GHz band and Channel 5 in the 6 GHz band, and the available bandwidths are 80 MHz and 320 MHz respectively. In this case, AP101 can select Channel 5 in the 6 GHz band with a wider available bandwidth of 320 MHz by comparing the available bandwidths at each frequency. As an example, AP101 stores a table associating the frequencies that each communication interface of the device can use with the available bandwidths at each frequency. Then, when there are multiple candidate frequencies, AP101 can select a frequency with a wide available bandwidth by referring to this table. Note that AP101 can select a frequency after adding additional information according to the operation status of the network to the pre-created table. For example, the additional information can be that some frequencies are unavailable due to detecting a radar or the like. Also, the additional information can be a frequency that partially overlaps with the frequency used in the existing link that AP101 is using. When there are multiple candidate frequencies, AP101 can select the frequency with the widest available frequency bandwidth among them. Also, when there are multiple frequencies with the widest available frequency bandwidth, AP101 can select one frequency based on a random number or the like from among them. Also, AP101 can select a predetermined number of frequencies in order from the frequencies with the widest available frequency bandwidth, and then select one frequency using a random number or other conditions from among them. Also, AP101 can set a predetermined threshold value regarding the available frequency bandwidth and select one frequency from among the frequencies with an available frequency bandwidth equal to or greater than the threshold value.

[0031] AP101 can use conditions associated with the frequency band to which the candidate frequency belongs as predetermined conditions. For example, AP101 can select a frequency belonging to a specific frequency band. As an example, when there are multiple candidate frequencies, each belonging to a different frequency band, AP101 can select one frequency from among the frequencies belonging to the 6 GHz band. Generally, by using a frequency belonging to the 6 GHz band, there is a high possibility of communicating at a high communication speed compared to frequencies belonging to other frequency bands. Also, when the models and standards (such as IEEE802.11ax) corresponding to the 6 GHz band are limited, the number of communication devices using the same frequency decreases, so there is a high possibility of achieving higher throughput and lower latency. Furthermore, when communication devices implementing existing standards cannot use 6 GHz, only MCS (Modulation and Coding Scheme) that can achieve a high frame rate will be used. As a result, the time for each communication device to occupy a frequency becomes shorter and traffic congestion is suppressed. Therefore, in the communication between AP101 and STA102, it becomes easier to acquire the right to transmit and the delay can be reduced. On the other hand, when there are multiple candidate frequencies, AP101 can select a frequency from among the frequencies belonging to the 2.4 GHz band. The 2.4 GHz band has a larger number of corresponding communication terminals and higher interconnectivity compared to other frequency bands. Therefore, by selecting a frequency belonging to the 2.4 GHz band, AP101 can accommodate more communication terminals. Also, since the radio wave reach range of the 2.4 GHz band is wider compared to other frequency bands, the network 110 configured by AP101 can cover a wider range. On the other hand, when there are multiple candidate frequencies, AP101 can select a frequency from among the frequencies belonging to the 5 GHz band. The 5 GHz band has less interference compared to the 2.4 GHz band which is also used in general household appliances and devices implementing Bluetooth, and has a larger number of corresponding communication terminals compared to the 6 GHz band. Therefore, it is a frequency band that combines the advantages of the 2.4 GHz band and the 6 GHz band. Therefore, by selecting a frequency belonging to the 5 GHz band, it is possible to accommodate a large number of communication devices and perform communication with good communication quality.AP101 sets priorities for the frequency bands available for the communication interface of the device itself, and can make selections based on the frequency bands to which each of the candidate frequencies belongs according to those priorities. For example, if there is a frequency belonging to the highest-priority frequency band among the candidate frequencies, AP101 can select one frequency from among them. Note that if there are multiple frequencies belonging to a high-priority frequency band, AP101 can select one frequency based on a random number or the like. Also, AP101 can select a predetermined number of frequencies in order from the frequencies belonging to the high-priority frequency band, and for example, select one frequency from among them using a random number or other conditions.

[0032] As a predetermined condition, AP101 can use conditions associated with combinations with existing available frequencies. For example, AP101 can select a frequency belonging to a frequency band different from the frequency bands to which each of the existing available frequencies belongs. For example, if the existing available frequencies are two frequencies belonging to the 5 GHz band and one frequency belonging to the 6 GHz band, AP101 can select a frequency belonging to the 2.4 GHz band. Also, when there are a plurality of candidate frequencies in the same frequency band as the frequency band to which the existing available frequencies belong, AP101 can select the frequency with the largest frequency interval from the existing available frequencies. For example, in an existing link of AP101, assume that one frequency each belonging to the 2.4 GHz band, 5 GHz band, and 6 GHz band is used, and any of the candidate frequencies is a frequency belonging to any of these frequency bands. In this case, AP101 can select the frequency with the largest frequency interval between each of the existing available frequencies and the candidate frequencies. By selecting a frequency far from the existing available frequencies, the interference power generated between links can be suppressed. Note that when there are a plurality of candidate frequencies, AP101 can select one frequency from among the frequencies with a frequency interval larger than a predetermined threshold from each of the existing available frequencies. For example, AP101 may select one frequency based on a random number or the like from among them. Also, AP101 can select a predetermined number of frequencies in order from the frequency with the largest frequency interval from each of the existing available frequencies, and select one frequency based on a random number or the like from among them. On the other hand, AP101 may select the same frequency as the frequency used by another AP. For example, when AP101 is capable of performing coordinated transmission or the like, AP101 can select the frequency used by the AP that is the cooperation partner for the coordinated transmission. Coordinated transmission is a transmission method in which a plurality of APs cooperate to perform transmission. For example, it may include a plurality of APs transmitting the same signal to one STA, a plurality of APs performing beamforming so as to reduce interference with each other, and the like. By AP101 selecting the frequency used by another AP, coordinated transmission becomes possible, and the communication quality and throughput between AP101 and STA102 can be improved.

[0033] As a predetermined condition, AP101 can use conditions associated with specific frequencies. For example, AP101 may select frequencies other than a specific frequency. Generally, in the 5 GHz band, it is a frequency band where radio waves such as weather radar and military radar can be transmitted. Therefore, a communication device using the 5 GHz band needs to implement a DFS (Dynamic Frequency Selection) function to change to other frequencies when detecting a radar or the like. In view of this, AP101 can select frequencies other than those for which the DFS function is required. Thereby, it is not necessary to execute the DFS function at the added frequencies, and it is possible to avoid changing the frequency due to the detection of a radar or the like. Also, AP101 can select PSC (Preferred Scanning Channel) in the 6 GHz band or frequencies other than channel 6 in the 2.4 GHz band. PSC in the 6 GHz band and channel 6 in the 2.4 GHz band are channels that are preferentially selected when an STA searches for an AP. Therefore, it is highly likely that more communication terminals are communicating compared to other frequencies. By AP101 selecting a frequency other than PSC, it becomes possible to add a frequency where it is easy to obtain a transmission opportunity. On the other hand, AP101 may select a specific frequency as the frequency to be added. For example, AP101 can select a frequency for which the DFS function is required. When other APs select other frequencies to avoid executing the DFS function, the frequency for which the DFS function is required can be a frequency with relatively few communication terminals. Thereby, AP101 can add a link where it is easy to obtain a transmission opportunity. Also, AP101 can select frequencies included in PSC in the 6 GHz band or channel 6 in the 2.4 GHz band. By selecting these frequencies, AP101 is more likely to be found by STA102, resulting in an effect of enhancing connectivity. As a result of selecting frequencies using other conditions, if multiple candidate frequencies remain, AP101 can select a specific frequency or a frequency other than a specific frequency from among them. Also, AP101 can select one frequency using other conditions from among a specific frequency or a frequency other than a specific frequency.

[0034] AP101 can use conditions associated with interference as predetermined conditions. For example, AP101 can select a frequency with less interference from among the candidate frequencies. By selecting a frequency with less interference amount as the frequency to be used for the additional link, the possibility for AP101 and STA102 to acquire the transmission right increases, so it becomes possible to add a link that can actually obtain a high throughput. For example, AP101 can perform a scan of each frequency using the antennas it has and select a frequency with less interference. Less interference can be, for example, the ratio of the time of receiving radio waves with a received power exceeding a predetermined threshold at the antenna of AP101 per unit time. For example, AP101 can measure the number of Beacon frames, FILS Discovery frames, etc. received per unit time and select the channel with the least number of received frames. Also, AP101 may select the channel with the smallest total number of all frames received per unit time or the total of the NAV (Network Allocation Vector) set for the frequency. Also, AP101 may use only those received frames whose received intensity exceeds a predetermined threshold as the measurement target. Note that AP101 can acquire related information from STA102 to grasp the interference. For example, AP101 can cause STA102 to execute a scan of each frequency and report the received information to AP101. As an example, AP101 can transmit a Beacon Report Request to STA102 and receive a Beacon Report as this response. The Beacon Report may include information of other APs received at each frequency where STA102 executed the scan. Thereby, AP101 can select the frequency to be added after grasping the congestion situation of each frequency around AP101 and STA102. Also, AP101 can select a frequency based on the number of other APs using the scanned frequency or the number of other APs using the neighboring frequencies of that frequency. As an example, AP101 sets a weight coefficient for the number of APs per frequency. For example, a coefficient X is set for the number of APs using the same frequency as the target frequency.Also, a coefficient Y is set for the number of APs using a frequency different from the target frequency and within 20 MHz from the target frequency, and a coefficient Z is set for the number of APs using a frequency within 40 MHz and more than 20 MHz from the target frequency. For example, X = 4, Y = 2, and Z = 1 may be used. These numbers can be any values that satisfy the relationship X > Y > Z. Then, AP101 can calculate the sum of these and select one frequency from among the frequencies that are below a predetermined threshold. In this way, by selecting the frequency to be added based on the information acquired by the device itself and the information received from STA102, it becomes possible to add a frequency at which the performance of multi-link communication can be exhibited in consideration of the communication situation around AP101 and STA102. Note that when there are a plurality of candidate frequencies for which the amount of interference described above is below a predetermined threshold, AP101 may select one frequency based on a random number or the like from among them. Also, AP101 can select a predetermined number of frequencies in order from the frequency with the lowest amount or intensity of interference, and select one frequency from among them based on a random number, other conditions, or the like.

[0035] FIG. 4 shows an example of a flowchart when AP101 in the present embodiment increases the number of links used in parallel in multi-link communication with its own device and selects the frequencies used for additional links. In this flowchart, as described above, it is assumed that AP101 has set three frequencies as the frequencies available for multi-link communication with its own device. Then, AP101 determines whether to increase the number of links to be used (S401), and selects the frequencies to be used for those links. For example, AP101 may execute this determination when starting to operate as an AP, or may execute it periodically. AP101 may execute this determination when the amount of communication traffic handled by its own device has increased. For example, AP101 may determine to increase the number of links to be used when the communication frequency or communication volume between AP101 and STA102 exceeds a threshold (such as when the amount of data to be communicated or the number of data packets exceeds a predetermined threshold), or when the number of connected STAs exceeds a threshold. Also, AP101 may determine to increase the number of links to be used when receiving an instruction to increase the number of links to be used in the input of setting changes by the user. Further, AP101 may determine to increase the number of links to be used when its own device is connected to a power source or when the remaining battery level is equal to or higher than a predetermined threshold. Furthermore, AP101 may determine to increase the number of links to be used when communicating specific types of data such as print data or image (photo, video, etc.) data in the communication between AP101 and STA102, or when communicating data of a specific application. Note that AP101 may determine to increase the number of links to be used when detecting that traffic is congested at the frequencies used in multi-link communication. For example, AP101 may detect that traffic is congested based on the fact that the number of Beacons received from other APs or the ratio of the period during which the frequency is in a busy state exceeds a predetermined threshold at the frequencies used in multi-link communication.

[0036] When it is determined that the number of links to be used is to be increased (YES in S401), the AP101 determines whether there is a connected STA (S402). When there is no connected STA (NO in S402), the AP101 selects one frequency from the frequencies at which the own device can perform the STR operation for the existing available frequencies (S407). For example, the AP101 can select, as candidate frequencies, frequencies that are at least a predetermined frequency interval at which the STR operation is possible for each of the existing available frequencies. Then, the AP101 can select one frequency that satisfies the above conditions, such as a frequency with a wide bandwidth available for communication, a frequency belonging to a specific frequency band, or a frequency belonging to a frequency band different from or the same as the frequency band to which the existing available frequency belongs, from among the candidate frequencies.

[0037] On the one hand, when there is a connected STA (YES in S402), AP101 can select a frequency to add based on the information obtained from STA102. For example, when AP101 receives a frame including the NSTR Indication Bitmap field from STA102 (YES in S403), it can select a frequency so that the number of STR link pairs in STA102 increases (S408). Also, when AP101 does not receive a frame including the NSTR Indication Bitmap field from STA102 (NO in S403), it can request STA102 to measure the surrounding wireless environment (S404). For example, AP101 can send a Beacon Report Request to STA102. When AP101 receives a Beacon Report from STA102, it can select a better frequency including the results of scans of each frequency performed by its own device. For example, AP101 determines whether there are multiple frequencies at which its own device can perform the STR operation for the existing available frequencies (S405). When there are multiple frequencies at which the STR operation is possible (YES in S405), AP101 selects one of them (S406). For example, AP101 can select a frequency that is not congested (e.g., has less interference) from among the frequencies at which its own device can perform the STR operation. When there is only one frequency at which the STR operation is possible (NO in S405), AP101 selects that frequency (S407). Note that when there is no frequency at which the STR operation is possible, AP101 may proceed to S406. Note that the method by which AP101 selects a frequency when there are multiple candidate frequencies is not limited to the above method. For example, AP101 may select a frequency by combining the above-described methods. For example, AP101 can select a frequency using other methods without determining whether the existing available frequencies can perform the STR operation. Also, AP101 can select a frequency using other methods regardless of the presence or absence of connected STAs. That is, AP101 can select a frequency using any of the above-described predetermined conditions individually or in combination.

[0038] FIG. 5 shows an example of a sequence of communication with STA102 when AP101 in the present embodiment increases the number of links used in parallel in multi-link communication. In this example, AP101 increases the number of links during multi-link communication and notifies STA102. First, assume that links 121 to 123 are established between AP101 and STA102. Assume that the Link IDs assigned to each of links 121 to 123 are 1 to 3, respectively. AP101 notifies information on the links including the frequencies available for multi-link communication with its own device using a Beacon (F501). For example, AP101 uses the Multi-Link element included in the Beacon (or Probe Response) to notify that Link IDs = 1 to 3 can be used and the frequencies used in each link, etc. Then, between F501 and F502, AP101 selects the frequency to be used in the additional link and notifies the information on the added frequency (F502). For example, AP101 can notify the information on the added frequency using Link Reconfiguration Notify. Link Reconfiguration Notify can be an Action frame. That is, AP101 can notify STA102 using Link Reconfiguration Notify of the fact that the number of links available for multi-link communication has increased and the information specifying the added frequency. AP101 can transmit including the information on the added frequency in the subsequent Beacon (F503). For example, AP101 can transmit the information on the added frequency using the Multi-Link element included in the Beacon (or Probe Response). Note that this sequence is an example, and for example, Link Reconfiguration Notify may be omitted, or other frames may be included.

[0039] FIG. 6 shows a configuration example of a Beacon in this embodiment. The Beacon is configured to include a Frame Control field 601, a Duration field 602, a Multi-Link element 603, a Padding field 604, and an FCS 605. The Frame Control field 601 contains information related to frame control. For example, the Frame Control field 601 contains information such as the type and subtype of the frame. The Duration field 602 indicates, for example, an estimated value of the time required to transmit this frame and the time required for its response and frame interval. The Multi-Link element 603 contains information related to multi-link communication including information on the link of multi-link communication with the AP 101. The Padding field 604 contains padding data. The FCS 605 is a frame check sequence, and a CRC (Cyclic Redundancy Check) for verifying whether the frame is received normally is stored therein.

[0040] FIG. 7 shows a configuration example of the Multi-Link element 603. The Multi-Link element 603 includes an Element ID field 701, a Length field 702, and an Element ID Extension field 703. Further, the Multi-Link element 603 may include a Multi-Link Control field 704, a Common Info field 705, and a Link Information field 706. The Element ID field 701 and the Element ID Extension field 702 store values of 255 and 107 respectively, indicating that this element is a Multi-Link element.

[0041] The Multi-Link Control field 704 includes a Type sub-field 707 and a Presence Bitmap field 708. The Type sub-field 707 indicates the type of the Multi-Link element. For example, in the case of a Basic-Multi-Link element, a value of 0 is stored in the Type sub-field 707. The Presence Bitmap sub-field 708 indicates the presence or absence of each field included in the Multi-Link element 603. The Presence Bitmap sub-field 708 may include an MLD Address Present sub-field 713 and an NSTR Link Pair Present sub-field 714. When the MLD Address Present sub-field 714 is 1, it indicates that the Common info field 705 includes the MLD Address field 709. When the MLD Address Present sub-field 713 is 0, the Common info field 705 does not include the MLD Address field 709. When the NSTR Link Pair Present sub-field 714 is 1, it indicates that the Link Information field 706 includes the NSTR Indication Bitmap sub-field 716. When the NSTR Link Pair Present sub-field 714 is 0, the Link Information field 706 does not include the NSTR Indication Bitmap sub-field 716. The Common Info field 705 includes the MLD Address field 709. The MLD Address field 709 stores the MAC Address assigned to the AP MLD.

[0042] The Multi-Link element 603 included in the Beacon or Probe Response can be called a Basic Multi-Link element. The Link Information field 706 in the Basic Multi-Link element contains information for each link that the AP 101 uses for multi-link communication. The Link Information field 706 contains a number of Per-STA Profile subelements 717 corresponding to the number of links that the AP 101 uses for multi-link communication. The Per-STA Profile subelement 717 includes a Subelement ID subfield 710, a STA Control subfield 711, and a STA Info subfield 712. The Subelement ID field 710 indicates the type of the Link Info field. For example, in the case of the Per-STA Profile subfield, a value of 0 is stored. The STA Control subfield 711 includes a Link ID subfield 715. The Link ID subfield 715 stores the Link ID of the link associated with this Per-STA Profile subelement 717. For example, values of 1 to 3 can be stored as the Link ID corresponding to each of links 121 to 123, respectively.

[0043] The STA Info subfield 712 includes the NSTR Indication Bitmap subfield 716. The NSTR Indication Bitmap subfield 716 indicates a combination of Links that are NSTRs (NSTR link pairs). For example, assume that Link 121 (Link ID = 1) and Link 122 (Link ID = 2) are an NSTR link pair. In this case, the second bit of the NSTR Indication Bitmap subfield 716 included in the Link Information field 706 whose Link ID subfield 714 value is 1 becomes 1. That is, by setting the second bit of the NSTR Indication Bitmap subfield 716 to 1, it is indicated that it becomes an NSTR link pair with Link ID = 2. On the other hand, the first bit of the NSTR Indication Bitmap subfield 716 included in the Link Information field 706 whose Link ID subfield 715 has a value of 2 becomes 1. That is, by setting the first bit of the NSTR Indication Bitmap subfield 716 to 1, it is indicated that it becomes an NSTR link pair with Link ID = 1. In this way, by indicating the link that becomes the partner of the NSTR link pair in the Per-STA Profile sub-element 717 indicated individually for each link, it is possible to indicate which combination of links cannot be transmitted and received simultaneously for the STA102.

[0044] FIG. 8(A) shows a configuration example of the Link Reconfiguration Notify frame 821 in this embodiment. The Link Reconfiguration Notify frame 821 includes a Category field 801, a Protected EHT Action field 802, and a Dialog Token field 803. The Link Reconfiguration Notify frame 821 may further include a Reconfiguration Multi-Link field 804. The Category field 801 indicates the type of this frame. For example, by storing the value 37 in the Category field 801, it is indicated that the type of this frame is a Protected EHT Action frame. The Protected EHT Action field 802 indicates the type of this frame in the Protected EHT Action frame. FIG. 9 is a table showing the correspondence between the values that can be included in the Protected EHT Action field 802 and their meanings. For example, when the value of the Protected EHT Action field 802 is 10, it is indicated that this frame is a Link Reconfiguration Notify frame. The Dialog Token 803 is an identifier for identifying requests and responses of a series of messages.

[0045] The Reconfiguration Multi-Link element 403 is a variant of the Basic Multi-Link element 603 shown in FIG. 7. The Reconfiguration Multi-Link element 403 does not have the NSTR Link Pair Present subfield 714 and the NSTR Indication Bitmap subfield 716. On the other hand, the Reconfiguration Multi-Link element includes an Operation Update type subfield in the STA Control subfield 711. The Operation Update type subfield stores a value related to the link state change. When the value of the Operation Update type subfield is 0, it indicates excluding the AP. Here, excluding the AP may correspond to each of the multiple links of the multi-link communication in the AP 101 and stopping one of the multiple AP functions that execute the operation as an AP in that link. When the value of the Operation Update type subfield is 1, it indicates that the link parameters have been updated. When the value of the Operation Update type subfield is 2, it indicates that a link has been added. Adding a link may mean, for example, that the number of links used by the AP 101 in multi-link communication has increased and the frequency corresponding to the added link has been added. When the value of the Operation Update type subfield is 3, it indicates that a link has been deleted. Deleting a link may mean, for example, that the number of links used by the AP 101 in multi-link communication has decreased and the use of the corresponding frequency has been stopped. In this embodiment, since the AP 101 increases the number of links used in multi-link communication and adds a fourth frequency, the value of the Operation Update type subfield is 2. An Action frame including the Reconfiguration Multi-Link element in which this Operation Update type subfield is stored is transmitted.

[0046] As described above, in this embodiment, AP101 increases the number of links used in parallel in multi-link communication, selects the frequencies corresponding to the additional links, and notifies STA102. The frequencies corresponding to the additional links can be selected based on, for example, the STR operation, the available frequency bandwidth, the frequency band, the combination with the existing available frequencies, specific frequencies, predetermined conditions associated with interference, etc. Thus, according to this embodiment, AP101 selects frequencies so that the performance of multi-link communication is enhanced as the frequencies used in the additional links. Thereby, in multi-link communication, it becomes possible to enhance the improvement in performance by increasing the number of links used in parallel.

[0047] (Embodiment 2) In this embodiment, an operation example when STA102 requests AP101 to add a link used in multi-link communication will be described. First, it is assumed that two links, link 121 and link 122, are established as the links used in multi-link communication between AP101 and STA102. In this embodiment, these links are referred to as existing links. Also, it is assumed that AP101 sets frequencies other than the frequencies used in link 121 and link 122 as the frequencies used by the own device in multi-link communication, and notifies STA102 of that information. Then, STA102 selects one frequency from the frequencies notified by AP101, and requests to add the link corresponding to this frequency to the multi-link communication between AP101 and STA102. At this time, STA102 selects a frequency based on predetermined conditions. Examples of the predetermined conditions for STA102 to select a frequency will be described below.

[0048] STA102 can use conditions related to communication quality as predetermined conditions. For example, STA102 can select a link with good communication quality as an additional link. As an example, STA102 can measure communication quality using Beacons received from AP101 at each frequency available for multi-link communication notified by AP101. As an example, the communication quality can be RSSI (Received Signal Strength Indicator), SNR (Signal to Noise Ratio), etc. Then, STA102 can calculate the difference in communication quality at each frequency, and if there is a frequency exceeding a predetermined threshold, it can select that frequency. That is, STA102 can select a link with higher communication quality compared to other links among the links using the frequencies available for multi-link communication. For example, by selecting a link with a high SNR, STA102 can communicate at a high MCS. As a result, high throughput and a low retransmission rate can be achieved. In this way, by adding a link with good communication quality, STA102 can enhance the effect of adding a link. Note that STA102 may select the link with the best communication quality among the frequencies available for multi-link communication notified by AP101. Also, STA102 can select a predetermined number of links in order from the link with the best communication quality and select a link from them using a random number or other conditions. Further, STA102 can set a predetermined threshold and select one link from among the links whose indicators indicating communication quality such as SNR and RSSI exceed the predetermined threshold using a random number or other conditions.

[0049] Note that STA102 can evaluate the communication quality of each link that can be used for multi-link communication with AP101 and select a link. For example, STA102 can establish each link that can perform multi-link communication with AP101, measure throughput, delay, the number of retransmissions, etc., and select the link with the best measurement results. Good measurement results can mean, for example, high throughput, low delay, and few retransmissions. STA102 can repeatedly establish links using frequencies other than those used in existing links in sequence, execute predetermined measurements, and release the links. Also, STA102 can establish all links simultaneously, execute measurements, and release all links except the additional link. By doing so, STA102 can reliably add a link based on the actually measured results. Note that STA102 can store the measured results and use them when adding or deleting a link next time. This can avoid procedures such as measurement of each link and establishment and release of links for measurement.

[0050] STA102 can use conditions associated with the STR operation as predetermined conditions. For example, STA102 can select a link on which the STR operation can be executed for each of the link to be added and the existing link. If the STR operation is possible using each of the added link and the existing link, data and the like can be transmitted and received without any restrictions in each link. Therefore, effects such as an improvement in throughput corresponding to the addition of the link can be obtained. Also, when the added link and the existing link are in the NSTR operation, if STA102 cannot obtain the transmission right in one link while the other link cannot obtain the transmission right, the transmission can be delayed. Since STA102 may have more difficulty obtaining the transmission right than AP101, the possibility of accessing the channel further decreases due to the inability to perform the STR operation. As a result, the delay in STA102 may increase. Thus, adding a link on which the STR operation is possible in STA102 does not cause problems such as an increase in delay in the existing link, and the performance due to the addition of the link is enhanced. The method for STA102 to determine a link on which the STR operation is possible is the same as the method for AP101 to select a frequency on which the STR operation is possible in Embodiment 1, and thus the description is omitted. The predetermined conditions associated with the STR operation may be used in combination with other conditions, and when there are a plurality of candidate frequencies, a frequency that satisfies the predetermined conditions associated with the STR operation may be preferentially selected.

[0051] STA102 can use conditions associated with interference as predetermined conditions. For example, STA102 can select a frequency with less interference. As an example, STA102 can select a frequency with a small number of other STAs connected to AP101 to which the own device is connected. Since the number of STAs using the same frequency is small, it becomes easier for STA102 to acquire the right to transmit, and throughput and delay can be improved. For example, STA102 can obtain the number of STAs connected to AP101 at each frequency used by AP101 for multi-link communication and select the frequency with the smallest number of STAs. Also, STA102 can perform a scan of each frequency using the antenna of the own device and select a frequency with less interference. The method by which STA102 determines a frequency with less interference is the same as the method by which AP101 determines a frequency with less interference in Embodiment 1, so the description is omitted.

[0052] STA102 can use conditions associated with the available frequency bandwidth at candidate frequencies as predetermined conditions. For example, STA102 can select a frequency with a wide available bandwidth for communication. By STA102 selecting a frequency with a wide available bandwidth, the communication capacity increased by adding a link can be increased. When there are multiple candidate frequencies, STA102 can select the frequency with the widest available bandwidth among them. Also, when there are multiple frequencies with the widest available bandwidth, STA102 can select one frequency based on a random number or the like from among them. Also, AP101 can select a predetermined number of frequencies in order from the frequencies with the widest available bandwidth, and for example, select one frequency using a random number or other conditions from among them. Also, AP101 can set a predetermined threshold value regarding the available frequency bandwidth and select one frequency from among the frequencies with an available bandwidth equal to or greater than the threshold value.

[0053] STA102 can use conditions associated with the frequency band to which the candidate frequency belongs as a predetermined condition. For example, STA102 can select a frequency belonging to a specific frequency band. By selecting a frequency belonging to the 6 GHz band, for example, STA102 can select a frequency that can improve throughput and latency compared to other frequency bands because the proportion of communication devices using a high transmission rate MCS increases. By selecting a frequency belonging to the 2.4 GHz band, for example, STA102 can select a frequency that allows communication to continue even at a location far from AP101. By selecting a frequency using the frequency band belonging to the 5 GHz band, for example, STA102 can select a frequency that is less likely to become congested compared to using the 2.4 GHz band and is more likely to maintain a connection with AP101 compared to using the 6 GHz band. STA102 can set priorities for the frequency bands available for the communication interface of its own device and make selections based on the frequency bands to which each of the candidate frequencies belongs according to the priorities. For example, if there is a frequency belonging to the highest priority frequency band among the candidate frequencies, STA102 can select one frequency from among them. Note that if there are multiple frequencies belonging to a high-priority frequency band, STA102 can select one frequency based on a random number or the like. Also, AP101 can select a predetermined number of frequencies in order from the frequencies belonging to the high-priority frequency band and, for example, select one frequency from among them using a random number or other conditions.

[0054] STA102 can use conditions associated with combinations with existing links as predetermined conditions. For example, STA102 can select a frequency belonging to a frequency band different from the frequency band used in existing link 121 or link 122. Alternatively, STA102 can select a frequency belonging to the same frequency band as the frequency band used in existing link 121 or link 122 and away from the frequency used in the existing link. Thereby, the possibility of interference occurring between the links is reduced, and for example, the possibility of the STR operation being possible is increased. On the other hand, when AP101 performs cooperative transmission with another AP, STA102 can select the same frequency as the frequency used by the AP that is the partner of AP101. By adding a link in which STA102 uses the frequencies used by both of the two APs, it becomes easier to perform cooperative transmission between the APs.

[0055] STA102 can use conditions associated with a specific frequency as a predetermined condition. For example, STA102 can select a frequency other than a specific frequency. As an example, by selecting a frequency other than the frequency where the radar exists, STA102 can execute a DFS operation or avoid changing the frequency due to radar detection. Also, STA102 can select a PSC in the 6 GHz band or a frequency other than channel 6 in the 2.4 GHz band. By selecting a frequency other than these frequencies, there is a possibility of making it easier to acquire a transmission right. On the other hand, STA102 can select a frequency of a specific frequency. For example, since the frequency where the radar exists may not be used by other communication devices, STA102 can increase the possibility of acquiring a transmission right by selecting the frequency where the radar exists. Also, STA102 can select a PSC in the 6 GHz band or channel 6 in the 2.4 GHz band. By selecting these frequencies, it becomes easier to directly communicate with other STAs using the same frequency. If a plurality of candidate frequencies remain as a result of STA102 selecting a frequency using other conditions, STA102 can select a specific frequency or a frequency other than a specific frequency from among them. Also, STA102 can select one frequency using other conditions from among a specific frequency or a frequency other than a specific frequency.

[0056] FIG. 10 shows an example of a flowchart when STA102 requests the addition of a link to AP101 in the present embodiment to select a frequency to be used for the added link. In this flowchart, as described above, it is assumed that two links, link 121 and link 122, are established as links to be used for multi-link communication between AP101 and STA102. Then, STA102 determines whether to add a third link to these two existing links (S1001). For example, STA102 may execute this determination when the own device is connected to AP101, or may execute it periodically. STA102 may execute this determination when the amount of communication traffic handled by the own device has increased. For example, STA102 may determine to add a link when the communication frequency or communication volume with AP101 exceeds a threshold (such as when the amount of data to be communicated or the number of data packets exceeds a predetermined threshold). Also, STA102 may determine to add a link when the number of connections of other STAs in link 121 or link 122 exceeds the threshold, or when the number of connections of other STAs at other frequencies is below the threshold. Also, STA102 may determine to add a link when receiving an instruction to add a link in an input of a setting change by the user. Also, STA102 may determine to add a link when the own device is connected to a power source or when the remaining battery level is equal to or higher than a predetermined threshold. Further, STA102 may determine to add a link when communicating specific types of data such as print data or image (photo, video, etc.) data in communication with AP101, or when communicating data of a specific application. Note that STA102 may determine to add a link when detecting that traffic is congested in link 121 or link 122.

[0057] When STA102 determines to add a link (YES in S1001), it determines whether there is another frequency available for multi-link communication with AP101 other than the existing link (S1002). Note that if there is another AP that is physically different from AP101 and constitutes the same AP MLD as AP101, if there is a frequency available between this AP and STA102, it can be included as a frequency available for multi-link communication. If STA102 determines that there is no other frequency (NO in S1002), it ends the process. Also, when there is one other frequency (YES in S1002 and NO in S1003), STA102 determines that frequency as the frequency of the link to be added (S1009). On the other hand, when there are multiple other frequencies (YES in S1002 and S1003), STA102 selects a frequency from among those candidate frequencies. For example, if there is a frequency with better communication quality than other frequencies (YES in S1004), STA102 can select the frequency with the best communication quality among them (S1005). For example, STA102 compares the SNR of the frames received from AP101 at each candidate frequency. If there is one or more frequencies where the difference in SNR etc. from that at other frequencies is greater than a predetermined threshold, STA102 can select the frequency with the highest SNR among them. Note that STA102 may also make a determination based on the presence or absence of a frequency where an index (such as SNR) for specifying the communication quality at each candidate frequency exceeds a predetermined threshold. In this case, STA102 can select the frequency with the highest numerical value of the index from among one or more frequencies that exceed the predetermined threshold.

[0058] If the difference in communication quality between candidate frequencies is not significant (NO in S1004), STA102 determines whether there is a frequency at which the device can perform the STR operation with the existing links (Link 121 and Link 122) (S1006). If there is a frequency at which the STR operation is possible (YES in S1006), STA102 determines that frequency as the frequency of the link to be added (S1007). If there is no frequency at which the STR operation is possible (NO in S1006), STA102 may select, as the frequency of the link to be added, a frequency with a small number of connections to other STAs (S1008). Note that in S1007, if there are multiple frequencies at which the STR operation is possible, STA102 may select the frequency of the link to be added using the other methods described above. Also, in S1008, instead of the method of selecting, as the frequency of the link to be added, a frequency with a small number of connections to other STAs, STA102 may select the frequency of the link to be added using the other methods described above. Note that the method by which STA102 selects the frequency of the link to be added from among multiple candidate frequencies may be a combination of the multiple methods described above, and when combined, can be executed in any order. That is, STA102 can select a frequency using any of the predetermined conditions described above individually or in combination.

[0059] FIG. 11 shows a sequence example when STA102 requests AP101 to add a link in this embodiment. In this example, STA102 makes a request to AP101 to add a link during multi-link communication. First, it is assumed that link 121 and link 122 are established between AP101 and STA102. It is assumed that the Link IDs assigned to link 121 and link 122 are 1 and 2, respectively. On the other hand, AP101 has links that can be used for multi-link communication in addition to link 121 and link 122, and the Link IDs of the respective links are 3 to N. Here, N can be an integer of 3 or more. First, AP101 notifies information on links including frequencies available for multi-link communication with its own device using a Beacon (F1101). STA102 receives the Beacon (or Probe Response) transmitted by the AP and can recognize from the Multi-Link element included in the Beacon that Link IDs = 1 to N are available and the frequencies used for each link, etc. And between F1101 and F1102, STA102 selects the link to be added and requests AP101 to add the link (F1102). For example, STA102 can select the link to be added using the flowchart example shown in FIG. 10. Also, for example, STA102 can request AP101 to add a link using a Link Reconfiguration Request. The Link Reconfiguration Request can be an Action frame. When AP101 receives the Link Reconfiguration Request, it determines whether it can add the requested link and notifies STA102 of the determination result (F1103). For example, AP101 can use a Link Reconfiguration Response to request STA102 for a response to the link addition request. Then, AP101 and STA102 execute multi-link communication using a plurality of links including the added link.

[0060] FIG. 12 shows an example of a flowchart when AP101 determines whether to add a link based on a request from STA102 and sends a response. First, when AP101 receives a request to add a link from STA102, it determines whether the link can be added (S1201). If the link can be added (YES in S1201), AP101 sets the Status code to Success (S1202). If the link cannot be added (NO in S1201), AP101 indicates the reason for the failure in the Status code (S1204). For example, if the reason for the failure to add a link is that the number of connected STAs exceeds the regulation, a value of 17 can be set (DENIED_NO_MORE_STAS). These Status code notifications are performed for all the links requested by STA102, including the link to be added. AP101 notifies STA102 of the response including the Status code. For example, AP101 can notify STA102 of a Link Reconfiguration Response including the Status code.

[0061] FIG. 8(B) shows a configuration example of the Link Reconfiguration Request frame 822 in this embodiment. The Link Reconfiguration Request frame 822 includes a Category field 801, a Protected EHT Action field 802, and a Dialog Token field 803. The Link Reconfiguration Request frame 822 may also include a Reconfiguration Multi-Link field 804 and an OCI field 805. Since the Category field 801, the Protected EHT Action field 802, and the Dialog Token 803 are the same as those in the Link Reconfiguration Notify frame 821, the description thereof is omitted. Also, the Reconfiguration Multi-Link field 804 is the same as that in the Link Reconfiguration Notify frame 821. Note that the value 11 is stored in the Protected EHT Action field 802, indicating that this frame is a Link Reconfiguration Request frame. The OCI element 404 is optional and indicates the Operating Class and the Primary Channel Number. Thereby, the frequency used in the added link can be specified. Note that the added link may be indicated by the Link ID sub-element 715 included in the Per-STA Profile sub-element 717 in the Reconfiguration Multi-Link field 804.

[0062] Figure 8(C) shows a configuration example of the Link Reconfiguration Response frame 823 in this embodiment. The Link Reconfiguration Response frame 823 includes a Category field 801, a Protected EHT Action field 802, and a Dialog Token field 803. The Link Reconfiguration Response frame 823 may further include a Count field 806, a Reconfiguration Status List field 807, and a Group Key Data field 808. The Link Reconfiguration Response frame 823 may also include an OCI element 805 and a Basic Multi-Link element 809. Since the Category field 801, the Protected EHT Action field 802, and the Dialog Token 803 are the same as those in the Link Reconfiguration Notify frame 821, their descriptions are omitted. Note that the value 12 is stored in the Protected EHT Action field 802, indicating that this frame is a Link Reconfiguration Response frame. The Count field 806 indicates the number of links included in the subsequent Reconfiguration Status List field 807. The Reconfiguration Status List field 807 contains information about the links corresponding to the number indicated in the Count field 806. For example, the Reconfiguration Status List field includes a set of a Link ID Info subfield and a Status subfield corresponding to each link. The Link ID Info subfield includes a Link ID subfield that identifies which link the information corresponds to. The Status subfield stores the Status code corresponding to each link. This can indicate whether additional links requested by STA102 are available for each link.The Group Key Data field 808 is optional and describes the Group Key Data to be used in the additional link. This enables the transfer of the Group Key to be completed simultaneously with the addition of the link. The OCI element 805 is optional and may be included in the Link Reconfiguration Response frame 823 when the Group Key Data sub-field 808 is included. The OCI element 805 can be used to specify the frequency at which the Group Key operates. The Basic Multi-Link element 809 is optional and may store Per-STA Profile Information containing detailed information about the additional link.

[0063] As described above, in this embodiment, in order for the STA 102 to increase the number of links used in parallel in multi-link communication, it selects a frequency and requests the AP 101 to add a link using the selected frequency. The frequency corresponding to the link to be added can be selected based on predetermined conditions associated with communication quality, STR operation, interference, available frequency bandwidth, frequency band, combination with existing links, specific frequencies, etc. Thus, according to this embodiment, the STA 102 selects a frequency so that the performance of multi-link communication is enhanced as the frequency to be used in the additional link. This makes it possible to enhance the improvement in performance by adding a link in multi-link communication.

[0064] (Embodiment 3) In this embodiment, an operation example is described in which AP101 recommends adding a link to be used for multi-link communication to STA102, and STA102 requests the addition of a link to AP101 in response thereto. First, similar to Embodiment 2, it is assumed that two links, Link 121 and Link 122, are established as links to be used for multi-link communication between AP101 and STA102. In this embodiment, these links are referred to as existing links. Further, it is assumed that AP101 sets a frequency other than the frequencies used in Link 121 and Link 122 as the frequency to be used for multi-link communication by the own device, and notifies STA102 of the information. Then, AP101 selects a frequency other than the frequencies used in the existing links (Link 121 and Link 122), and recommends to STA102 adding a link using this frequency to the multi-link communication between AP101 and STA102. STA102 determines whether to add the link recommended by AP101. If it is determined to add the link, STA102 requests AP101 to add the link. Below, the sequence exchanged between AP101 and STA102 and the format of the frames used are described.

[0065] FIG. 13 shows an example of a sequence exchanged between AP101 and STA102 in this embodiment. In this example, AP101 recommends to STA102 the addition of a link during multi-link communication. Assume that the Link IDs assigned to each of link 121 and link 122 established between AP101 and STA102 are 1 and 2 respectively. And assume that the Link IDs of the links that AP101 can use for multi-link communication other than link 121 and link 122 are 3 to N. Here, N can be an integer of 3 or more. First, AP101 notifies information on links including frequencies available for multi-link communication with its own device using a Beacon (F1301). For example, STA102 receives a Beacon (or Probe Response) transmitted by the AP, and recognizes from the Multi-Link element included in the Beacon that Link IDs = 1 to N can be used, and the frequencies used for each link, etc. And between F1301 and F1302, AP101 selects the frequency to be used for the recommended link and recommends to STA102 the addition of a link (F1302). For example, AP101 can recommend to STA102 the addition of a link using Link Recommendation. Also, AP101 can recommend to STA102 the addition of a link using Link Reconfigurtion Notify. When STA102 receives a recommendation for link addition from the AP, it determines whether to add a link, and if it determines to add a link, it requests AP101 to add a link (F1303). For example, STA102 can request the addition of a link using Link Reconfiguration Request. Note that when recommending the addition of a link, AP101 may make a recommendation to STA102 including information specifying the frequency to be used for the link to be added. Also, STA102 may request the addition of a link using the frequency recommended by AP101, or may request the addition of a link using another frequency selected by its own device. When AP101 receives a request for link addition from STA102, it determines whether it can add the requested link, and notifies the determination result to STA102 (F1304).For example, AP101 can request STA102 to respond to a link addition request using a Link Reconfiguration Response.

[0066] FIG. 14 shows an example of a flowchart when AP101 selects a frequency to be used for a link recommended to STA102. In this flowchart, as described above, it is assumed that AP101 has established Link 121 and Link 122 with STA102 among the links (Link ID = 1 to N) available for multi-link communication. Then, AP101 determines whether to add a third link to these two existing links (S1401). For example, AP101 can execute this determination when connecting to STA102. AP101 can execute this determination periodically after connecting to STA102. Also, AP101 can determine that it recommends adding a link when the communication frequency or communication volume between AP101 and STA102 exceeds a threshold (when the amount of data to be communicated or the number of data packets exceeds the threshold), etc., or when the number of connected STAs using the same link exceeds the threshold. Further, AP101 can determine that it recommends adding a link when the number of connected STAs of other STAs is below the threshold at a frequency not used in the multi-link communication between AP101 and STA102. AP101 can determine that it recommends adding a link when it receives an instruction to add a link to STA102 in an input of a setting change by the user. Also, AP101 can determine that it recommends adding a link when its own device is connected to a power source and the remaining battery level is equal to or higher than a predetermined threshold. Furthermore, AP101 can determine that it recommends adding a link when communicating specific types of data such as print data or image (photo, video, etc.) data in the communication with STA102, or when communicating data of a specific application.

[0067] When the AP101 determines to recommend adding a link (YES in S1401), it determines whether there is a frequency available for multi-link communication with the STA102 other than the frequencies used in the existing links (S1402). If there is no other frequency (NO in S1402), the AP101 ends the process. Also, when there is one other frequency (YES in S1402 and NO in S1403), the AP101 selects it as the frequency to be used in the link to be added (S1407). On the other hand, when there are multiple other frequencies (YES in S1402 and S1403), the AP101 selects a frequency from among those candidate frequencies. For example, the AP101 determines whether there is a frequency at which the STA102 can perform the STR operation between the existing links (Link 121 and Link 122) (S1404). If there is a frequency at which the STR operation is possible (YES in S1404), the AP101 determines the frequency to be used in the link to be added from among those frequencies (S1405). If there is no link at which the STR operation is possible (NO in S1404), the AP101 selects, as the frequency of the link to be added, a frequency with a small number of connections to other STAs (S1406). Note that in S1405, when there are multiple frequencies at which the STR operation is possible, the AP101 can select the frequency of the link to be added using the other methods described above. Also, in S1406, instead of the method of selecting, as the frequency of the link to be added, a frequency with a small number of connections to other STAs, the AP101 can select the frequency of the link to be added using the other methods described in Embodiment 1 or Embodiment 2. Note that the method by which the AP101 selects the frequency of the link to be added from among multiple candidate frequencies may be a combination of the multiple methods described in Embodiment 1 or Embodiment 2, and when combined, they can be executed in any order. That is, the AP101 can select a frequency using any of the above-described predetermined conditions individually or in combination.

[0068] FIG. 8(D) shows a configuration example of the Link Recommendation frame 824 in the present embodiment. The Link Recommendation 824 includes a Category field 801 and a Protected EHT Action field 802. The Link Recommendation frame 824 may further include a Reason Code field 810, an AID Bitmap element 811, and a Multi-Link Traffic Indication element 812. Since the Category field 801 and the Protected EHT Action field 802 are the same as those in the Link Reconfiguration Notify frame 821, their descriptions are omitted. Note that a value of 7 is stored in the Protected EHT Action field 802, indicating that this frame is a Link Recommendation frame. The Reason Code field 810 indicates the reason why the AP 101 recommends adding a link. For example, when the value of the Reason Code field 810 is 72, it may indicate an increase in traffic. The Reason Code field 810 may indicate an increase in communication frequency, an increase in the number of STAs connected to the existing links (link 121, link 122), etc. Also, by setting the value of the Reason Code field 810 to 1, a specific reason may not be indicated (UNSPECIFIED_REASON). The AID Bitmap element 811 identifies the STAs for which link addition is recommended by the Link Recommendation frame 824. For example, each bit included in the AID Bitmap element 811 corresponds to an AID (Association Identifier) that uniquely identifies each STA, and the bit corresponding to the STA for which link addition is recommended may be set to 1. Note that by setting a plurality of bits included in the AID Bitmap element 811 to 1, it is possible to recommend adding links to multiple STAs at once. The Multi-Link Traffic Indication element 812 indicates information for identifying the recommended links.For example, the Multi-Link Traffic Indication element 812 can set 1 for the Link ID corresponding to the recommended link for each AID (i.e., STA) indicated by the AID Bitmap element 811. For example, when AP101 recommends adding a link to STA102, the bit corresponding to the AID of STA102 is set to 1 in the AID Bitmap element 811. Also, when AP101 recommends a link with Link ID = 3 to STA102, the bit corresponding to Link ID = 3 is set to 1 in the Multi-Link Traffic Indication element 812. STA102 can recognize whether a link addition is recommended for its own device by checking the AID Bitmap element 811 of the received Link Rcommendation frame 824. Also, similarly, STA102 can recognize the Link ID of the recommended link by checking the Multi-Link Traffic Indication element 812. Note that since the Link ID of each link and the frequency used in that link are associated one-to-one, STA102 can grasp the frequency of the recommended link. Note that instead of the Link Recommendation frame 824, AP101 can transmit a Beacon or the like including the Multi-Link Traffic Indication element 812. For example, the Beacon or the like can include a Probe Response, FILS Discovery, Link Reconfiguration Notify821, etc. Note that AP101 can recommend adding a link to a specific STA102 by transmitting a Link Reconfiguration Notify821 including a Reconfiguration Multi-Link element to that STA102.

[0069] Upon receiving the Multi-Link Traffic Indication element 812, STA102 can determine whether to request the addition of a link and whether to add the recommended link. Note that STA102 can request the addition of a link using another frequency without requesting the addition of the recommended link to AP101. In this case, STA102 can select the frequency of the link to be added according to the flow example in FIG. 10. Then, AP101 can determine whether to permit the addition of the link according to the flow example in FIG. 12.

[0070] As described above, in this embodiment, in order to recommend increasing the number of links used in parallel in the multi-link communication between AP101 and STA102, a frequency is selected, and STA102 is recommended to add a link using the selected frequency. The frequency corresponding to the link to be added can be selected based on predetermined conditions associated with the STR operation, interference, available frequency bandwidth, frequency band, combination with existing links, specific frequencies, etc. Thus, according to this embodiment, AP101 selects a frequency so that the performance of the multi-link communication is enhanced as the frequency used in the link to be added in the multi-link communication with STA102. Thereby, in the communication multi-link communication, it is possible to enhance the improvement in performance by adding a link.

[0071] (Embodiment 4) In this embodiment, an operation example when AP101 reduces the number of links used in parallel in multi-link communication will be described. First, assume that AP101 has set three frequencies as the frequencies available for multi-link communication in the network 110 configured by the own device. Then, AP101 stops using one of the three frequencies available for multi-link communication. At this time, AP101 selects the frequency to be stopped using based on predetermined conditions. Hereinafter, an example of the predetermined conditions for AP101 to select the frequency to be stopped using will be described.

[0072] AP101 can use conditions associated with the STR operation as predetermined conditions. For example, if among the frequencies (frequencies used for multi-link communication) that the own device has set as available for multi-link communication, there is a combination of frequencies where the STR operation cannot be performed, AP101 can select a frequency to stop using from among those frequencies. That is, if there is a combination of frequencies that form an NSTR link pair for the own device among the frequencies used for multi-link communication, AP101 can select a frequency to stop using from among those frequencies. Also, if among the frequencies used for multi-link communication, there is a combination of frequencies that form an NSTR link pair for STA102 connected to the own device, AP101 can select a frequency to stop using from among those frequencies. For example, if a combination of any two of the above three frequencies forms an NSTR link pair for the own device or STA102, AP101 can select any frequency in that combination. By selecting a frequency to stop using so that the NSTR link pair is resolved, the restrictions on data transmission between the links that have occurred until then can be resolved. As a result, effects such as an improvement in throughput and delay commensurate with multi-link communication can be obtained. If there are different NSTR link pairs for each of the own device and STA102 connected to the own device, AP101 can select a frequency included in any of the NSTR link pairs. For example, AP101 can select a frequency commonly included in a plurality of NSTR link pairs. By selecting a common frequency, the NSTR link pairs in both AP101 and STA102 can be resolved. Also, AP101 can preferentially select a frequency included in the NSTR link pair of the own device. Since AP101 may perform multi-link communication with a plurality of STA102s, by resolving the restrictions on the operation in AP101, the characteristics of the entire network can be improved. On the other hand, AP101 can preferentially select a frequency included in the NSTR link pair of STA102. Since STA102 may have difficulty accessing the channel compared to AP101, by resolving the restrictions on the operation in STA102, STA102 can more easily access the channel.Note that when there are multiple STAs 102 connected to the own device and different NSTR link pairs exist in each of them, AP101 can select the frequency included in any of the NSTR link pairs. For example, AP101 can select the frequency commonly included in more NSTR link pairs. Thereby, the operation restrictions in more STAs 102 can be eliminated. As a method for AP101 to identify the NSTR link pair in the own device or STA102, the method described above in Embodiment 1 or the like can be applied. Also, the predetermined conditions associated with the STR operation may be used in combination with other conditions. When there are multiple candidate frequencies, the frequency that satisfies the predetermined conditions associated with the STR operation may be preferentially selected. Note that AP101 can obtain the frequency interval in which the STR operation is possible using the Frequency Separation For STR / AP MLD Type Indication subfield. If there is a combination of frequencies used for multi-link communication that is smaller than the frequency interval indicated by this subfield, AP101 can select the frequency to stop using from the frequencies included in that combination.

[0073] AP101 can use, as a predetermined condition, a condition associated with the available frequency bandwidth at each of the frequencies used for multi-link communication. For example, AP101 can select, from among the frequencies used for multi-link communication, a frequency with a relatively narrow available frequency bandwidth as the frequency to stop using. For example, assume that among the frequencies used by AP101 for multi-link communication, channel 36 in the 5 GHz band and channel 5 in the 6 GHz band are included, and available bandwidths of 80 MHz and 320 MHz are available respectively. In this case, AP101 can select channel 36 in the 5 GHz band, which has a relatively narrow available bandwidth, as the frequency to stop using. Thereby, it is possible to reduce the impact on throughput and traffic by reducing the number of links used in parallel by AP101 in multi-link communication. On the other hand, AP101 can select, from among the frequencies used for multi-link communication, a frequency with a relatively wide available frequency bandwidth as the frequency to stop using. For example, assume that among the frequencies used by AP101 for multi-link communication, channel 36 in the 5 GHz band and channel 5 in the 6 GHz band are included, and available bandwidths of 80 MHz and 320 MHz are available respectively. In this case, AP101 can select channel 5 in the 6 GHz band, which has a relatively wide available bandwidth, as the frequency to stop using. For example, if the purpose of reducing the number of links used in parallel by AP101 in multi-link communication is power saving due to reduced traffic in the own device or reduction of interference to other communication devices, the effect can be enhanced by releasing a frequency that can use a wide bandwidth. That is, thereby, power consumption in the own device and STA102 can be suppressed, and it can become easier for surrounding communication devices to secure radio resources. As a method for AP101 to acquire the available frequency bandwidth at each frequency, the method described in Embodiment 1 and the like can be applied. Note that when there are a plurality of frequencies with the widest or narrowest available bandwidths at each of the frequencies used for multi-link communication, AP101 can select one frequency from among them based on a random number or other conditions. Also, AP101 can set a predetermined threshold value and select one frequency from among the frequencies with an available bandwidth wider or narrower than the threshold value based on a random number or other conditions.Note that the AP101 can select frequencies to be stopped from use among other frequencies, leaving the frequency with the widest available bandwidth and the frequency with the narrowest available bandwidth at each frequency used for multi-link communication. The AP101 can set a predetermined threshold value and select frequencies to be stopped from use among other frequencies, leaving frequencies with an available bandwidth wider or narrower than the threshold value.

[0074] As a predetermined condition, AP101 can use conditions associated with the frequency bands to which each of the frequencies used for multi-link communication belongs. For example, AP101 can select, as the frequencies to stop using, the frequencies belonging to a specific frequency band from among the frequencies used for multi-link communication. Or, AP101 can select, as the frequencies to stop using, the frequencies belonging to other frequency bands while leaving the frequencies belonging to a specific frequency band. For example, assume that the frequencies used by AP101 for multi-link communication are respectively frequencies belonging to the 2.4 GHz band, 5 GHz band, and 6 GHz band. In this case, AP101 can select, as the frequencies to leave, the frequencies belonging to the 6 GHz band, and select, as the frequencies to stop using, the frequencies from among the frequencies belonging to the 2.4 GHz band or 5 GHz band. By leaving the frequencies belonging to the 6 GHz band, relatively higher communication speeds may be achievable. Also, when the models and standards (such as IEEE802.11ax) corresponding to the 6 GHz band are limited, the number of communication devices using the same frequency decreases, so it becomes possible to obtain higher throughput in the communication between AP101 and STA102. Furthermore, when 6 GHz is not used in communication devices implementing existing standards, only the MCS (Modulation and Coding Scheme) that realizes a high frame rate will be used. As a result, the time for each communication device to occupy the frequency becomes shorter and traffic congestion is suppressed, so it becomes easier to acquire the right to transmit and the delay can be reduced even in the communication between AP101 and STA102. Also, AP101 can select, as the frequencies to leave, the frequencies belonging to the 2.4 GHz band, and select, as the frequencies to stop using, the frequencies from among the frequencies belonging to the 5 GHz band or 6 GHz band. Since the 2.4 GHz band has a larger number of corresponding communication terminals and higher interconnectivity compared to other frequency bands, by leaving the frequencies belonging to the 2.4 GHz band, AP101 can accommodate more communication terminals. Also, since the 2.4 GHz band has a wider radio wave reach compared to other frequency bands, it becomes possible to cover a wider range. Also, AP101 can select, as the frequencies to leave, the frequencies belonging to the 5 GHz band, and select, as the frequencies to stop using, the frequencies from among the frequencies belonging to the 2.4 GHz band or 6 GHz band.Since the 5 GHz band has less interference than the 2.4 GHz band and more corresponding communication terminals than the 6 GHz band, it is a frequency band that combines the advantages of the 2.4 GHz band and the 6 GHz band. Therefore, it is possible to accommodate a large number of communication devices and perform communication with good communication quality. In addition, when a plurality of frequencies belonging to the same frequency band are included among the frequencies used for multi-link communication in AP101, AP101 can select a frequency to be stopped from among the frequencies belonging to the same frequency band. Thereby, the frequency interval between the frequencies used among a plurality of links can be increased, the possibility of performing the STR operation in each link can be enhanced, and the interference between the links can be reduced. For example, when the frequencies used by AP101 for multi-link communication are 36ch in the 5 GHz band, 5ch and 213ch in the 6 GHz band, respectively, AP101 can select 5ch in the 6 GHz band as the frequency to be stopped. Similarly, even if the frequency bands to which the frequencies used by AP101 for multi-link communication belong are different from each other, AP101 can preferentially select the frequencies included in a combination of relatively close frequencies. Thereby, the frequency interval between the frequencies remaining as the frequencies that can be used by AP101 for multi-link communication can be increased.

[0075] As a predetermined condition, AP101 can use a condition associated with a specific frequency. For example, when the frequency used for multi-link communication includes a frequency that requires the implementation of the DFS function, AP101 can preferentially select this frequency as the frequency to stop using. This eliminates the need to execute the DFS function and can avoid the possibility of changing the frequency due to radar detection. On the other hand, AP101 can leave the frequency that requires the implementation of the DFS function and preferentially select the other frequencies as the frequencies to stop using. Since the frequency that requires the DFS function can be a frequency with a relatively small number of communication terminals, AP101 can maintain a frequency that can obtain a relatively high communication speed. Also, when PSC is included in the frequency set as available for multi-link communication by the device itself, AP101 can preferentially select PSC as the frequency to stop using. This reduces the possibility that AP101 becomes difficult to be detected from the STA, and can reduce the possibility that the transmission of data frames is hindered by the transmission and reception of control frames such as Probe Response. On the other hand, AP101 can leave PSC and preferentially select the frequencies other than PSC as the frequencies to stop using. This maintains the possibility that AP101 can be detected from the STA, and while ensuring connectivity, the number of frequencies available for multi-link communication can be reduced.

[0076] AP101 can use conditions associated with interference as predetermined conditions. For example, AP101 can select, from the frequencies used by the own device for multi-link communication, a frequency with a large amount of interference as the frequency to stop using. For example, AP101 can leave frequencies with less interference and select a frequency to stop using from the other frequencies based on an index indicating the amount of interference detected during the communication of the own device. The index indicating the amount of interference can include the number of Beacons or other frames from other APs at each frequency, the ratio of the period during which the frequency is busy per unit time, and the like. Also, AP101 can cause the connected STA102 to report surrounding interference and select a frequency to stop using based on the interference detected by the own device and the interference reported from STA102. The method by which AP101 specifies the amount of interference at each frequency can be the method described above in Embodiment 1 and the like. Thereby, it is possible to reduce the influence on throughput and traffic by reducing the number of links used in parallel by AP101 in multi-link communication. Note that AP101 can set a predetermined threshold value and select one from the frequencies for which the index indicating the amount of interference exceeds the predetermined threshold value based on a random number or other conditions. The index indicating the amount of interference can be the ratio of the period during which the frequency is busy per unit time, the number of other APs, the number of received frames, the intensity of the signal received from other networks, and the like.

[0077] AP101 can use a condition associated with the number of STAs connected to its own device as a predetermined condition. For example, AP101 can select, from among the frequencies used by its own device for multi-link communication, a frequency to stop using the link with a small number of STAs used for multi-link communication with its own device. By selecting a frequency with a small number of STAs in use, it is possible to reduce the impact on communication with STA102 by reducing the number of links used in parallel in multi-link communication by AP101. In addition, when the frequency to be deleted by STA102 is used for multi-link communication, AP101 may recommend migrating to other frequencies available for multi-link communication. For example, AP101 can recommend migration to other frequencies by transmitting a BSS Transition Management Query frame or a BSS Transition Management Request frame to STA102. Also, AP101 can notify the remaining period until the frequency is stopped using and the migration destination frequency, etc. by the BSS Transition Management Request frame. Further, when the number of STAs using each frequency changes as a result of recommending migration to other frequencies to a plurality of STAs, AP101 may select a frequency to stop using based on the number of STAs after the change. For example, AP101 selects a plurality of candidates for the frequency to stop using and recommends migration to other frequencies to STA102 using any frequency in multi-link communication. Then, after a predetermined period has elapsed, AP101 can select a candidate frequency with a small number of STAs in use as the frequency to stop using. Alternatively, AP101 can select a frequency to leave as a frequency with a large number of STAs using each frequency and select a frequency to stop using from among the other frequencies.

[0078] FIG. 15 shows an example of a flowchart when AP101 in the present embodiment reduces the number of links used in parallel in multi-link communication with its own device and selects a frequency to stop using. In this flowchart, as described above, it is assumed that AP101 has set three frequencies as frequencies available for multi-link communication in network 110 configured by its own device. Then, AP101 determines whether to stop using any of these three frequencies (S1501). For example, AP101 may execute this determination when starting to operate as an AP, or may execute it periodically. AP101 may execute this determination when the communication traffic volume handled by its own device has decreased. For example, when the communication frequency or communication volume between AP101 and STA102 falls below a threshold (when the amount of data to be communicated or the number of data packets is below a predetermined threshold, etc.), when the number of STA connections falls below a threshold, etc., AP101 may determine to stop using any frequency. Also, when receiving an instruction to reduce the number of links used in parallel in multi-link communication or to stop using a frequency in an input of setting change by the user, AP101 may determine to stop using any frequency. Further, when the power supply of its own device is removed or when the remaining battery level becomes equal to or lower than a predetermined threshold, AP101 may determine to stop using any frequency. Furthermore, when the communication of specific types of data such as print data or image (photo, video, etc.) data or the communication of data of a specific application is completed in the communication between AP101 and STA102, AP101 may determine to stop using any frequency. Also, when detecting interference exceeding a threshold at the frequency used by its own device for multi-link communication, AP101 may determine to stop using that frequency. In this case, AP101 may add another frequency as a frequency available for multi-link communication by its own device before or after stopping using this frequency. That is, AP101 may also determine to stop using a frequency when changing the frequencies available for multi-link communication by its own device. For example, when detecting that another frequency has less interference or less congestion, or when performing DFS operation, etc., AP101 may also change to another frequency.

[0079] When AP101 determines to suspend the use of a link (YES in S1501), it determines whether there is a connected STA (S1502). If there is no connected STA (NO in S1502), AP101 can select a frequency to be suspended from, for example, frequencies with a narrow available frequency bandwidth (S1507). Also, AP101 may select a frequency to be suspended from frequencies with a wide available frequency bandwidth. AP101 may select a frequency belonging to a specific frequency band. The method for AP101 to select a frequency to be suspended is not limited to these, and any of the above-described methods can be applied.

[0080] On the other hand, when there is a connected STA (YES in S1502), the AP101 can determine the frequency to be stopped based on the information obtained from the STA102. For example, when the AP101 has received a frame including the NSTR Indication Bitmap field from the STA102 (YES in S1503), the AP101 can select a frequency so that the number of STR link pairs in the STA102 increases (S1508). For example, the AP101 can select from the frequencies used for the NSTR link pairs in the connected STA102. Also, when the AP101 has not received a frame including the NSTR Indication Bitmap field from the STA102 (NO in S1503), the AP101 can request the STA102 to perform measurements (S1504). For example, the AP101 can send a Beacon Report Request to the STA102. When the AP101 receives a Beacon Report from the STA102, it can select the frequency to be stopped including the interference situation detected by its own device. For example, the AP101 determines whether there is a frequency that is congested (has a lot of interference) exceeding a predetermined threshold at the frequency used by its own device for multi-link communication (S1505). When there are multiple frequencies that are congested exceeding the predetermined threshold (YES in S1505), the AP101 selects one of them (S1506). When there is no frequency that is congested exceeding the predetermined threshold (NO in S1505), the AP101 can select the frequency to be stopped by applying the above method (S1507). Note that the method by which the AP101 selects the frequency to be stopped when there are multiple candidate frequencies is not limited to the above method. For example, the AP101 may select the frequency to be stopped by combining the above methods. That is, the AP101 can select a frequency by using any of the above predetermined conditions individually or in combination.

[0081] Regarding the sequence of communication with STA102 when any of the frequencies used by AP101 in this embodiment for multi-link communication is stopped from being used, it will be described using the sequence example in FIG. 5. Note that descriptions of operations similar to those made using FIG. 5 in Embodiment 1 are omitted. In this example, AP101 stops using a frequency during multi-link communication and notifies STA102. First, AP101 uses a Beacon to notify information about the links and frequencies available for multi-link communication with its own device (for example, the Link ID of each of the three links and the frequencies being used, etc.) (F501). For example, AP101 notifies the information of each link using the Multi-Link element included in the Beacon (or Probe Response). Then, between F501 and F502, AP101 selects the frequency to be stopped from use and notifies the information of the selected frequency (F502). For example, AP101 can notify the information of the frequency to be stopped from use using Link Reconfiguration Notify. As an example, AP101 can use the Reconfiguration Multi-Link element 804 of the Link Reconfiguration Notify frame 821 shown in FIG. 8. In the Reconfiguration Multi-Link element 804 in this embodiment, in order to indicate the deletion of a link (stopping the use of a frequency), a value of 0 or 3 can be stored in the Operation Update type subfield. When the value of the Operation Update type subfield is 0, it is indicated that the AP is to be excluded. That is, it can be indicated to stop one of the plurality of AP functions corresponding to each of the plurality of links in the multi-link communication in AP101 and executing the operation as an AP in that link. Also, when the value of the Operation Update type subfield is 3, it is indicated that the corresponding frequency is to be stopped from use. Further, AP101 can transmit the updated link and frequency information in the Multi-Link element included in subsequent Beacons, Probe Responses, etc. (F503).That is, after stopping the use of a frequency, the AP101 can transmit in a Beacon, Probe Response, etc. that it transmits, excluding the information of the link corresponding to the frequency whose use has been stopped. Then, between the AP101 and the STA102, communication is executed using the frequency to be used for the updated multi-link communication without using the frequency whose use has been stopped.

[0082] As described above, in this embodiment, the AP101 reduces the number of links used in parallel in multi-link communication, selects the frequency to stop using, and notifies the STA102. The frequency to stop using can be selected based on predetermined conditions associated with the STR operation, available frequency bandwidth, frequency band, specific frequency, interference, the number of STAs connected to the own device, etc. Thus, according to this embodiment, the AP101 selects a frequency so that the performance of multi-link communication is less affected or the performance is improved as the frequency to stop using. Thereby, in multi-link communication, it is possible to suppress a decrease in performance due to reducing the number of links used in parallel and to improve the performance.

[0083] (Example 5) In this embodiment, an operation example when the STA102 requests the AP101 to delete one of the links used for multi-link communication will be described. First, assume that the STA102 has established three links, link 121 to link 123, as the links used for multi-link communication with the AP101. Then, the STA101 requests the AP101 to delete the link that satisfies a predetermined condition from among these three links. Hereinafter, an example of the predetermined condition for the STA102 to select the link to be deleted will be described.

[0084] STA102 can use conditions associated with communication quality as predetermined conditions. For example, STA102 can select, as the link to be deleted, a link corresponding to a frequency with low communication quality. As an example, STA102 calculates the difference in communication quality at each frequency using indicators indicating communication quality such as RSSI and SNR, and if there is a frequency at which the difference in communication quality exceeds a predetermined threshold, it can select, as the link to be deleted, a link corresponding to the frequency with low communication quality. Thereby, since STA102 can use a link with good communication quality with AP101, it can communicate at a high MCS. As a result, high throughput and a low retransmission rate can be achieved. In this way, by deleting a link with low communication quality, it is possible to enhance the effect of deleting the link. Note that, as a method for STA102 to identify the communication quality of each link, the method described in the above-described Embodiment 2 or the like can be applied. When there are a plurality of frequencies at which the difference in communication quality exceeds a predetermined threshold, STA102 can select one from among the frequencies with low communication quality based on a random number or other conditions. Also, STA102 may select a link corresponding to the frequency with the lowest communication quality among the frequencies used in multi-link communication. Further, STA102 can select a predetermined number of links in order from the link with the lowest communication quality and select a link from among them using a random number or other conditions. Also, STA102 can set a predetermined threshold and select one link from among the links at which indicators indicating communication quality such as SNR and RSSI are below the predetermined threshold using a random number or other conditions.

[0085] STA102 can use conditions associated with the STR operation as predetermined conditions. For example, if among the frequencies used for multi-link communication with AP101 there is a combination of frequencies in which the STR operation cannot be performed, STA102 can select a link to be deleted from among the links using those frequencies. That is, when there is a combination of frequencies that form an NSTR link pair for the own device or AP101 among the frequencies used for multi-link communication, STA102 can select a link to be deleted from among the links using those frequencies. For example, if a combination of any two of the above three frequencies forms an NSTR link pair for the own device or AP101, STA102 can select a link using any of the frequencies in that combination. By selecting frequencies so as to eliminate the NSTR link pair, the restrictions on data transmission between the links that have occurred until then can be eliminated. As a result, effects such as an improvement in throughput and delay commensurate with multi-link communication can be obtained. Note that as a method for STA102 to detect an NSTR link pair in the own device or AP101, the methods described above in Embodiment 1 and the like can be applied.

[0086] STA102 can use conditions associated with interference as predetermined conditions. For example, as the link to be deleted, STA102 can select a link using a frequency with a large number of other STAs connected to the AP101 to which the own device is connected or a frequency with a large amount of interference. As a method for STA102 to obtain the number of other STAs connected to AP101 and the amount of interference, the methods described above in Embodiment 1, 2, and the like can be applied. Thereby, STA102 can perform multi-link communication with AP101 using a link in which it is easy to acquire the right to transmit. Note that STA102 can set a predetermined threshold value and select one from among the frequencies in which the index indicating the amount of interference exceeds the predetermined threshold value based on a random number, other conditions, or the like. The index indicating the amount of interference can be the ratio of the period during which the frequency is busy per unit time, the number of other APs, the number of received frames, the number of other STAs connected to the AP to which the own device is connected, the intensity of the signal received from other networks, or the like.

[0087] STA102 can use, as a predetermined condition, a condition associated with the available frequency bandwidth at the frequency used for multi-link communication. For example, STA102 can select, as the link to be deleted, a link using a frequency with a narrow available bandwidth for communication. By selecting a link using a frequency with a narrow available bandwidth, the communication capacity reduced by the deletion of the link can be made small. On the other hand, STA102 can select, as the link to be deleted, a link using a frequency with a wide available bandwidth. For example, when the purpose of reducing the frequencies available for STA102 for multi-link communication is power saving due to a decrease in the communication volume in its own device or reduction of interference to other communication devices, the effect can be enhanced by releasing a frequency that can use a wide bandwidth. Note that when there are multiple frequencies with the widest or narrowest available bandwidths at each of the frequencies used for multi-link communication, STA102 can select a link corresponding to one of the frequencies based on a random number or other conditions. Also, STA102 can set a predetermined threshold value and select a link corresponding to one frequency based on a random number or other conditions from among the frequencies with an available bandwidth wider or narrower than the threshold value. Note that STA102 can select a link to be deleted from among other links, leaving the links using the frequencies with the widest or narrowest available bandwidths at each of the frequencies used for multi-link communication. STA102 can set a predetermined threshold value and select a frequency to stop using from among other links, leaving the links using the frequencies with an available bandwidth wider or narrower than the threshold value.

[0088] STA102 can use conditions associated with the frequency band to which the frequencies used for multi-link communication belong as predetermined conditions. For example, STA102 can select, as the link to be deleted, a link corresponding to a frequency belonging to a specific frequency band. Or, STA102 can select, as the link to be deleted, a link from among other links while leaving the link corresponding to the frequency belonging to a specific frequency band. For example, assume that the frequencies used by STA102 for multi-link communication are respectively frequencies belonging to the 2.4 GHz band, 5 GHz band, and 6 GHz band. In this case, STA102 can select, as the link to be deleted, a link from among other links while leaving the link corresponding to the frequency belonging to the 6 GHz band. By leaving the link corresponding to the frequency belonging to the 6 GHz band, relatively higher communication speed, high throughput, reduction of delay, etc. can be made possible. Also, STA102 can select, as the link to be deleted, a link from among other links while leaving the link corresponding to the frequency belonging to the 2.4 GHz band. By leaving the link corresponding to the frequency belonging to the 2.4 GHz band, communication with AP101 can be made possible over a wider range. Also, AP101 can select, as the link to be deleted, a link from among other links while leaving the link corresponding to the frequency belonging to the 5 GHz band. Since the 5 GHz band has the advantages of both the 2.4 GHz band and the 6 GHz band, it is possible to perform communication over a relatively wide range and with good communication quality. When a plurality of frequencies belonging to the same frequency band are included among the frequencies used by STA102 for multi-link communication, STA102 can select, as the link to be deleted, a link from among the links corresponding to the frequencies belonging to the same frequency band. Even if the frequency bands to which the respective frequencies used by STA102 for multi-link communication belong are different from each other, STA102 can preferentially select a link using frequencies included in a combination of relatively close frequencies. Thereby, the frequency interval between the frequencies to be left as the frequencies used by STA102 for multi-link communication can be widened.

[0089] STA102 can use conditions associated with a specific frequency as a predetermined condition. For example, when the frequency used for multi-link communication includes a frequency that requires the implementation of the DFS function, STA102 can be preferentially selected as the link to delete the link corresponding to this frequency. Thereby, it becomes unnecessary to execute the DFS function, and the possibility of changing the frequency due to radar detection can be avoided. On the other hand, STA102 can be preferentially selected as the link to leave the link corresponding to the frequency that requires the implementation of the DFS function and delete other links. Thereby, STA101 can maintain a link that can obtain a relatively high communication speed. Also, when the PSC is included in the frequency used by the own device for multi-link communication, STA102 can preferentially select the link corresponding to the PSC as the link to be deleted. Thereby, multi-link communication can be executed using a frequency with a small number of communication terminals in use. On the other hand, STA102 can be preferentially selected as the link to leave the link corresponding to the PSC and delete other links. Thereby, while ensuring connectivity with AP101, the number of frequencies available for multi-link communication can be reduced.

[0090] FIG. 16 shows an example of a flowchart when STA102 requests link deletion to AP101 in the present embodiment. In this flowchart, as described above, it is assumed that three links, link 121 to link 123, are established as links that can be used for multi-link communication between AP101 and STA102. Then, STA102 determines whether to delete any of these three links (S1601). For example, STA102 may execute this determination when the own device is connected to AP101, or may execute it periodically. STA102 may execute this determination when the amount of communication traffic handled by the own device has decreased. For example, STA102 may determine to delete any link when the communication frequency or communication volume with AP101 falls below a threshold (such as when the amount of data to be communicated or the number of data packets falls below a predetermined threshold). Also, STA102 may determine to delete any link when the number of connections of other STAs in link 121 to link 123 exceeds a threshold. Also, STA102 may determine to delete any link when it receives an instruction to delete a link in the input of setting change by the user. Also, STA102 may determine to delete any link when the own device is removed from the power source or when the remaining battery level becomes equal to or less than a predetermined threshold. Further, STA102 may determine to delete any link when the communication of specific types of data such as print data or image (photo, video, etc.) data is completed in the communication with AP101, or when the communication of data of a specific application is completed. Note that STA102 may determine to delete any link when it detects that traffic is congested in link 121 to link 123. Note that STA102 determines that link deletion cannot be performed when the number of links established with AP101 is 1.

[0091] When STA102 determines to delete a link (YES in S1601), for example, it determines whether there is a frequency with lower communication quality than other frequencies (S1602). When there is a frequency with lower communication quality than other frequencies (YES in S1602), it selects the frequency with the lowest communication quality among them (S1603). For example, STA102 compares the SNR etc. of the frames received from AP101 at the frequencies used for multi-link communication with each AP101. And when there is one or more frequencies whose difference from other frequencies is greater than a predetermined threshold, STA102 may select the frequency with the lowest SNR among those frequencies. Note that STA102 may also make a determination based on whether there is a frequency for which an index (such as SNR) specifying the communication quality at each frequency exceeds a predetermined threshold. In this case, STA102 may select the frequency with the lowest numerical value of the index from among one or more frequencies exceeding the predetermined threshold.

[0092] When the difference in communication quality between frequencies is not large (NO in S1602), STA102 determines whether there is a link among the links (link 121 to link 123) used in multi-link communication for which the own device cannot perform the STR operation (S1604). When there is a combination of links for which the STR operation cannot be performed (YES in S1604), it determines the links included in that combination as the links to be deleted (S1605). When there is no link operating in NSTR (NO in S1604), STA102 selects, as the link to be deleted, a frequency with a large number of connections of other STAs (S1606). Note that in S1606, instead of the method of selecting, as the link to be deleted, a link with a large number of connections of other STAs, STA102 may select the link to be deleted using other methods described above. Note that the method for STA102 to select the link to be deleted from among the links used in multi-link communication may be a combination of the above-described multiple methods, and when combined, they can be executed in any order. That is, STA102 can select frequencies using any of the above-described predetermined conditions individually or in combination.

[0093] Regarding the sequence of communication with AP101 when STA102 in this embodiment requests the deletion of a link used for multi-link communication, it will be described using the sequence example in FIG. 11. Note that the description of the same operations performed using FIG. 11 in Embodiment 2 will be omitted. In this example, STA102 makes a request to AP101 to delete a link during multi-link communication. First, AP101 notifies information on links including frequencies available for multi-link communication with its own device using a Beacon (F1101). Then, between F1101 and F1102, STA102 selects the link to be deleted and requests AP101 to delete the link (F1102). For example, STA102 can select the link to be deleted using the flowchart example shown in FIG. 16. Also, for example, STA102 can request AP101 to delete the link using a Link Reconfiguration Request. As an example, AP101 can use the Reconfiguration Multi-Link element 804 of the Link Reconfiguration Request frame 822 shown in FIG. 8(B). In this embodiment, since the Reconfiguration Multi-Link element 804 indicates the deletion of a link, a value of 3 can be stored in the Operation Update type subfield. When AP101 receives a Link Reconfiguration Request, it determines whether it can delete the requested link and notifies the determination result to STA102 (F1103). For example, AP101 can notify STA102 of the response to the link deletion request using a Link Reconfiguration Response. Then, communication is executed between AP101 and STA102 using the frequencies used for the updated multi-link communication without using the frequencies that have stopped being used.

[0094] Figure 17 shows an example of a flowchart when AP101 determines whether link deletion is possible based on a request from STA102 and sends a response. First, when AP101 receives a link deletion request from STA102, it determines whether the link can be deleted (S1701). If the link can be deleted (YES in S1701), AP101 sets the Status code to Success (S1702). If the link cannot be deleted (NO in S1701), AP101 indicates the reason for failure in the Status code (S1704). For example, if the reason for the failure of link addition is that a large amount of communication data is buffered, AP101 can notify STA102 with a Status code of 142. These Status code notifications are made for all the links requested by STA102, including the link to be deleted. AP101 notifies STA102 of the response including the Status code. For example, AP101 can notify STA102 of a Link Reconfiguration Response including the Status code (S1703).

[0095] As described above, in this embodiment, in order for STA102 to delete the links used in multi-link communication, it selects the frequencies to be stopped using and requests AP101 to delete the links using the selected frequencies. The frequencies corresponding to the links to be deleted can be selected based on predetermined conditions associated with communication quality, STR operation, interference, available frequency bandwidth, frequency band, specific frequencies, etc. Thus, according to this embodiment, STA102 selects a frequency as the frequency used in the link to be deleted so that the performance of multi-link communication is less affected or the performance is improved. Thereby, in multi-link communication, it is possible to suppress a decrease in performance due to link deletion and also improve the performance.

[0096] (Embodiment 6) In this embodiment, an operation example is described in which the AP 101 recommends to the STA 102 the deletion of a link used for multi-link communication with the STA 102, and the STA 102 requests the AP 101 to delete the link in response thereto. First, as in Embodiment 5, it is assumed that three links, i.e., Link 121 to Link 123, are established as links used for multi-link communication between the AP 101 and the STA 102. Then, the AP 101 recommends to the STA 102 the deletion of a link that satisfies a predetermined condition among these three links. The STA 102 determines whether to delete the link recommended by the AP 101, and if it determines to delete the link, it requests the AP 101 to delete the link. Below, the sequence exchanged between the AP 101 and the STA 102 and the format of the frame used are described.

[0097] Regarding the sequence of communication with STA102 when AP101 in this embodiment recommends deleting a link used for multi-link communication to STA102, it will be described using the sequence example in FIG. 13. Note that the description of operations similar to those described using FIG. 13 in Embodiment 3 will be omitted. In this example, AP101 recommends deleting a link to STA102 during multi-link communication. First, AP101 notifies information on links including frequencies available for multi-link communication with its own device using a Beacon (F1301). Then, between F1301 and F1302, AP101 selects a link to be deleted and recommends deleting the link to STA102 (F1302). For example, AP101 can recommend deleting a link to STA102 using Link Recommendation. When STA102 receives a recommendation to delete a link from the AP, it determines whether to delete the link. If it determines to delete the link, it requests AP101 to delete the link (F1303). For example, STA102 can request deleting a link using Link Reconfiguration Request. Note that when recommending deleting a link, AP101 may recommend to STA102 including information specifying the link to be deleted. Also, STA102 may request deleting the link recommended by AP101, or may request deleting another link selected by its own device. When AP101 receives a request to delete a link from STA102, it determines whether it can delete the requested link and notifies the determination result to STA102 (F1304). For example, AP101 can respond to the request to delete a link to STA102 using Link Reconfiguration Response. Then, communication is executed between AP101 and STA102 using the frequencies to be used for the updated multi-link communication without using the frequencies that have stopped being used.

[0098] FIG. 18 shows an example of a flowchart when AP101 selects a link recommended for STA102. In this flowchart, as described above, it is assumed that three links, link 121 to link 123, are established as links used for multi-link communication between AP101 and STA102. Then, AP101 determines whether to delete any of these three links (S1801). For example, AP101 can execute this determination when connecting to STA102. AP101 can execute this determination periodically after connecting to STA102. Also, AP101 can determine to recommend link deletion when the communication frequency or communication volume between AP101 and STA102 falls below a threshold (such as when the amount of data to be communicated or the number of data packets is below a predetermined threshold). Also, AP101 can determine to recommend link deletion when the number of connections of other STAs in link 121 to link 123 exceeds a threshold. AP101 can determine to recommend link deletion when receiving an instruction to delete the link with STA102 in the input of setting change by the user. Also, AP101 can determine to recommend link deletion when the own device is removed from the power source or when the remaining battery level becomes equal to or lower than a predetermined threshold. Further, AP101 can determine to recommend link deletion when the communication of specific types of data such as print data or image (photo, video, etc.) data is completed in the communication with STA102, or when the communication of data of a specific application is completed. Note that AP101 can determine to recommend link deletion when detecting that traffic is congested in link 121 to link 123. Note that AP101 determines that link deletion is not possible when the number of links established between AP101 and STA102 is 1.

[0099] When AP101 determines to recommend adding a link (YES in S1801), for example, it determines whether there is a link among the links (Link 121 to Link 123) used in multi-link communication where the own device or STA102 cannot perform the STR operation (S1802). If there is a combination of links where the STR operation cannot be performed (YES in S1802), AP101 determines the links included in that combination as the links to be deleted (S1803). If there is no link operating in NSTR (NO in S1802), AP101 selects, as the link to be deleted, the frequency with a large number of connections of other STAs (S1804). Note that in S1804, instead of the method of selecting the link to be deleted as the link with a large number of connections of other STAs, AP101 can select the link to be deleted using other methods described above. Note that the method of selecting the link to be deleted from among the links used by AP101 for multi-link communication with STA102 may combine the above-described multiple methods and can be executed in any order when combined. That is, AP101 can select the frequency recommended for STA102 using any of the above-described predetermined conditions individually or in combination.

[0100] AP101 can recommend link deletion to STA102 using Link Recommendation. Also, AP101 can recommend link deletion to STA102 using Link Reconfigurtion Notify. For example, AP101 can use the AID Bitmap element 811 and the Muti-Link Traffic Indication element 812 in the Link Recommendation 824 shown in FIG. 8(D). AP101 can use the AID Bitmap element 811 to indicate, in the Link Recommendation frame 824, the STAs for which link deletion is recommended. For example, each bit included in the AID Bitmap element 811 corresponds to each AID that uniquely identifies each STA, and the bit corresponding to the STA for which link deletion is recommended can be set to 1. Note that by setting a plurality of bits included in the AID Bitmap element 811 to 1, it is possible to recommend link deletion for a plurality of STAs at once. Also, AP101 can use the Multi-Link Traffic Indication element 812 to indicate the recommended links. For example, AP101 can set 0 to the Link ID corresponding to the recommended link in the Multi-Link Traffic Indication element 812 for each AID indicated by the AID Bitmap element 811. STA102 can recognize whether link deletion is recommended for its own device by checking the AID Bitmap element 811 of the received Link Rcommendation frame 824. Also, STA102 can similarly recognize the Link ID of the recommended link by checking the Multi-Link Traffic Indication element 812. That is, STA102 can recognize that link deletion is recommended when the Link ID corresponding to the link used in the multi-link communication with AP101 is set to 0.Note that the AP101 can transmit a Beacon or the like including the Multi-Link Traffic Indication element 812 instead of the Link Recommendation frame 824. The Beacon or the like may include a Probe Response, FILS Discovery, Link Reconfiguration Notify 821, etc. Note that the AP101 can recommend link deletion to a specific STA102 by transmitting a Link Reconfiguration Notify 821 including a Reconfiguration Multi-Link element to the STA102.

[0101] The STA102 that has received the Multi-Link Traffic Indication element 812 can determine whether to request the recommended link deletion. Note that the STA102 can request the deletion of other links without requesting the deletion of the link recommended by the AP101. In this case, the STA102 can select the link to be deleted according to the flow example in FIG. 16. Then, the AP101 can determine whether to permit the link deletion according to the flow example in FIG. 17.

[0102] As described above, in this embodiment, in order to recommend reducing the number of links used in parallel in the multi-link communication between the AP101 and the STA102, the frequency is selected, and the STA102 is recommended to delete the link using the selected frequency. The frequency corresponding to the link to be added can be selected based on predetermined conditions such as conditions associated with the STR operation, conditions associated with interference, conditions associated with the available frequency bandwidth, conditions associated with the frequency band, and conditions associated with a specific frequency. Thus, according to this embodiment, the AP101 selects a frequency so that the performance of the multi-link communication is less affected or the performance is improved as the frequency used for the link to be deleted in the multi-link communication with the STA102. Thereby, in the communication multi-link communication, it is possible to suppress a decrease in performance due to link deletion and to improve the performance.

[0103] (Modification example) In the above description, a technique for increasing or a function for decreasing the number of links used for multi-link communication between the AP101 and the STA102 has been described. However, this technology is also applicable to multi-link communication among a plurality of STAs. Further, the AP101 and the STA102 can change the frequencies used in each link, or make requests or recommendations therefor, by simultaneously executing a function for increasing and a function for decreasing the number of links used for multi-link communication. Furthermore, in the above description, when increasing or decreasing the number of links used in parallel with multi-link communication, an example of selecting the frequencies to be used or stopped using has been described. However, the increase or decrease in the number of links and the timing of selecting the frequencies to be used or stopped using can be independent. For example, the AP101 can notify the STA102 of a number of frequencies greater than the number of links used in parallel with multi-link communication, and can execute multi-link communication with the STA102 using some of those frequencies. In this case, the AP101 can add or stop using the frequencies available for multi-link communication independently of the increase or decrease in the number of links used in parallel with multi-link communication.

[0104] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium, and having one or more processors in a computer of the system or apparatus read and execute the program. Further, it can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

[0105] (Summary of the embodiment) Summarizing at least a part of the above-described embodiment, it is as follows. (Item 1) A communication device capable of performing multi-link communication using a plurality of links corresponding to each of a plurality of frequencies in accordance with the IEEE802.11 series standards with another communication device, selection means for selecting, based on predetermined conditions from among a plurality of candidate frequencies, a frequency associated with an additional link when increasing the number of the links used in parallel in the multi-link communication; notification means for notifying the other communication device of the frequency selected by the selection means A communication device characterized by the above. (Item 2) The communication device is an access point device, and the other communication device is a station device, The notification means notifies the plurality of station devices of the frequency selected by the selection means The communication device according to item 1, characterized by the above. (Item 3) The communication device is a station device, and the other communication device is an access point device, The notification means requests the access point device to add the link associated with the frequency selected by the selection means The communication device according to item 1, characterized by the above. (Item 4) The communication device is an access point device, and the other communication device is a station device, The notification means recommends to the station device to add the link associated with the frequency selected by the selection means The communication device according to item 1, characterized by the above. (Item 5) The predetermined condition is a condition associated with the number of other communication devices using each of the candidate frequencies, When the number of other communication devices using the first frequency included in the candidate frequencies is less than the number of other communication devices using the second frequency included in the candidate frequencies and different from the first frequency, the selection means preferentially selects the first frequency The communication device according to item 1, characterized by the above. (Item 6) The communication device is a station device, and the other communication device is an access point device, The predetermined condition is a condition associated with the number of other station devices communicating with the access point device using each of the candidate frequencies When the number of the other station devices communicating with the access point device using a first frequency included in the candidate frequencies is less than the number of the other station devices communicating with the access point device using a second frequency included in the candidate frequencies and different from the first frequency, the selection means preferentially selects the first frequency. The communication device according to item 1, characterized in that. (Item 7) The predetermined condition is a condition associated with STR (Simultaneous Transmit and Receive) in which transmission and reception in the plurality of links are performed independently. The selection means preferentially selects, from among the candidate frequencies, a frequency capable of executing the STR with respect to the frequency used in the multi-link communication. The communication device according to item 1, characterized in that. (Item 8) The predetermined condition is a condition associated with a frequency interval between the candidate frequency and the frequency used in the multi-link communication. When the frequency interval between a first frequency included in the candidate frequencies and the frequency used in the multi-link communication is larger than the frequency interval between a second frequency included in the candidate frequencies and different from the first frequency and the frequency used in the multi-link communication, the selection means preferentially selects the first frequency. The communication device according to item 1, characterized in that. (Item 9) The predetermined condition is a condition associated with a frequency bandwidth available in the candidate frequency. When the frequency bandwidth available at a first frequency included in the candidate frequencies is wider than the frequency bandwidth available at a second frequency included in the candidate frequencies and different from the first frequency, the selection means preferentially selects the first frequency. The communication device according to item 1, characterized in that. (Item 10) The predetermined condition is a condition associated with the frequency band to which the candidate frequency belongs, The selection means preferentially selects a frequency belonging to a predetermined frequency band from among the candidate frequencies. The communication device according to item 1, characterized in that. (Item 11) A communication device capable of performing multi-link communication using a plurality of links corresponding to each of a plurality of frequencies conforming to the IEEE802.11 series standards with another communication device, When reducing the number of links in the multi-link communication, selection means for selecting a frequency to stop using based on a predetermined condition from among the frequencies used in the multi-link communication; Communication means for performing the multi-link communication with the other communication device without using the frequency selected by the selection means. The communication device is characterized by that. (Item 12) The communication device is an access point device, and the other communication device is a station device, The access point device further includes notification means for notifying a plurality of the station devices of deletion of a link corresponding to the frequency selected by the selection means. The communication device according to item 11, characterized in that. (Item 13) The communication device is an access point device, and the other communication device is a station device, The access point device further includes notification means for notifying a plurality of the station devices of the frequencies used in the multi-link communication after excluding the frequency selected by the selection means. The communication device according to item 11, characterized in that. (Item 14) The communication device is a station device, and the other communication device is an access point device, The station device further includes request means for requesting the access point device to delete a link corresponding to the frequency selected by the selection means. The communication device according to item 11, characterized in that... (Item 15) The communication device is an access point device, and the other communication device is a station device. The access point device further has a recommending means for recommending to the station device the deletion of a link corresponding to the frequency selected by the selecting means. The communication device according to item 11, characterized in that... (Item 16) The communication device is an access point device, and the other communication device is a station device connected to the access point device. The predetermined condition is a condition associated with the number of devices different from the communication device and the other communication device that use each of the frequencies used in the multi-link communication. When the number of first devices using a first frequency included in the frequencies used in the multi-link communication is greater than the number of second devices using a second frequency different from the first frequency and included in the frequencies used in the multi-link communication, the selecting means preferentially selects the first frequency. The communication device according to item 11, characterized in that... (Item 17) The communication device is a station device, and the other communication device is an access point device. The predetermined condition is a condition associated with the number of other station devices communicating with the access point device using each of the frequencies used in the multi-link communication. When the number of other station devices communicating with the access point device using a first frequency included in the frequencies used in the multi-link communication is greater than the number of other station devices communicating with the access point device using a second frequency different from the first frequency and included in the frequencies used in the multi-link communication, the selecting means preferentially selects the first frequency. The communication device according to item 11, characterized in that... (Item 18) The predetermined condition is a condition associated with STR (Simultaneous Transmit and Receive) in which transmission and reception in the plurality of links are performed independently of each other, The selection means is a combination of two frequencies included in the frequencies used in the multi-link communication. When there is a combination in which the STR cannot be executed, the frequencies included in the combination are preferentially selected. The communication device according to item 11, characterized in that. (Item 19) The predetermined condition is a condition associated with the frequency interval between the frequencies used in the multi-link communication, In a combination of two frequencies included in the frequencies used in the multi-link communication, the selection means preferentially selects the frequencies included in the first combination when the frequency interval of the first combination is smaller than the frequency interval of the second combination different from the first combination. The communication device according to item 11, characterized in that. (Item 20) The predetermined condition is a condition associated with the available frequency bandwidth at each of the frequencies used in the multi-link communication, When the available frequency bandwidth at a first frequency included in the frequencies used in the multi-link communication is narrower than the available frequency bandwidth at a second frequency included in the frequencies used in the multi-link communication and different from the first frequency, the selection means preferentially selects the first frequency. The communication device according to item 11, characterized in that. (Item 21) The predetermined condition is a condition associated with the frequency band to which the frequencies used in the multi-link communication belong, The selection means preferentially selects the frequencies belonging to a predetermined frequency band from among the frequencies used in the multi-link communication. The communication device according to item 11, characterized in that. (Item 22) A control method executed by a communication device capable of performing multi-link communication using a plurality of links corresponding to each of a plurality of frequencies in accordance with the IEEE802.11 series standards with another communication device, comprising: When increasing the number of links used in parallel in the multi-link communication, a selection step of selecting a frequency associated with an additional link based on a predetermined condition from among a plurality of candidate frequencies; A notification step of notifying the other communication device of the frequency selected in the selection step. A control method characterized by the above. (Item 23) A control method executed by a communication device capable of performing multi-link communication using a plurality of links corresponding to each of a plurality of frequencies in accordance with the IEEE802.11 series standards with another communication device, comprising: When reducing the number of links in the multi-link communication, a selection step of selecting a frequency to stop using based on a predetermined condition from among the frequencies used in the multi-link communication; A communication step of performing the multi-link communication with the other communication device without using the frequency selected in the selection step. A control method characterized by the above. (Item 24) A program for causing a computer to function as each means included in the communication device according to any one of Items 1 to 21.

[0106] The invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, claims are attached to disclose the scope of the invention.

Description of Reference Numerals

[0107] 101: AP, 102: STA, 301: Link number control unit, 302: Data frame processing unit, 303: Communication frame transmission / reception unit

Claims

1. A communication device capable of performing multi-link communication using a plurality of links corresponding to each of a plurality of frequencies in accordance with the IEEE 802.11 series standards with another communication device, when increasing the number of links used in parallel in the multi-link communication, selection means for selecting a frequency associated with an additional link based on a predetermined condition from among a plurality of candidate frequencies; notification means for notifying the other communication device of the frequency selected by the selection means. A communication device characterized by the above.

2. The communication device is an access point device, the other communication device is a station device, the notification means notifies a plurality of the station devices of the frequency selected by the selection means. The communication device according to claim 1, characterized by the above.

3. The communication device is a station device, the other communication device is an access point device, the notification means requests the access point device to add the link associated with the frequency selected by the selection means. The communication device according to claim 1, characterized by the above.

4. The communication device is an access point device, the other communication device is a station device, the notification means recommends to the station device the addition of the link associated with the frequency selected by the selection means. The communication device according to claim 1, characterized by the above.

5. The predetermined condition is a condition associated with the number of other communication devices using each of the candidate frequencies, the selection means preferentially selects the first frequency when the number of other communication devices using the first frequency included in the candidate frequencies is less than the number of other communication devices using a second frequency different from the first frequency and included in the candidate frequencies. The communication device according to claim 1, characterized by the above.

6. The communication device is a station device, the other communication device is an access point device, the predetermined condition is a condition associated with the number of other station devices communicating with the access point device using each of the candidate frequencies. When the number of the other station devices communicating with the access point device using a first frequency included in the candidate frequencies is less than the number of the other station devices communicating with the access point device using a second frequency included in the candidate frequencies and different from the first frequency, the selection means preferentially selects the first frequency. The communication device according to claim 1, characterized in that.

7. The predetermined condition is a condition associated with STR (Simultaneous Transmit and Receive) in which transmission and reception in the plurality of links are performed independently. The selection means preferentially selects, from among the candidate frequencies, a frequency capable of executing the STR with respect to the frequency used in the multi-link communication. The communication device according to claim 1, characterized in that.

8. The predetermined condition is a condition associated with a frequency interval between the candidate frequencies and the frequency used in the multi-link communication. When the frequency interval between a first frequency included in the candidate frequencies and the frequency used in the multi-link communication is larger than the frequency interval between a second frequency included in the candidate frequencies and different from the first frequency and the frequency used in the multi-link communication, the selection means preferentially selects the first frequency. The communication device according to claim 1, characterized in that.

9. The predetermined condition is a condition associated with a frequency bandwidth available in the candidate frequencies. When the frequency bandwidth available at a first frequency included in the candidate frequencies is wider than the frequency bandwidth available at a second frequency included in the candidate frequencies and different from the first frequency, the selection means preferentially selects the first frequency. The communication device according to claim 1, characterized in that.

10. The predetermined condition is a condition associated with a frequency band to which the candidate frequencies belong. The selection means preferentially selects, from among the candidate frequencies, a frequency belonging to a predetermined frequency band. The communication device according to claim 1, characterized in that.

11. A communication device capable of performing multi-link communication using a plurality of links corresponding to a plurality of frequencies conforming to the IEEE 802.11 series standards with another communication device. When reducing the number of links in the multi-link communication, selection means for selecting a frequency to stop using from among the frequencies used in the multi-link communication based on a predetermined condition; Communication means for performing the multi-link communication with the other communication device without using the frequency selected by the selection means; A communication device characterized by the above.

12. The communication device is an access point device, and the other communication device is a station device. The access point device further includes notification means for notifying a plurality of the station devices of deletion of a link corresponding to the frequency selected by the selection means. The communication device according to claim 11, characterized by the above.

13. The communication device is an access point device, and the other communication device is a station device. The access point device further includes notification means for notifying a plurality of the station devices of the frequencies used in the multi-link communication after excluding the frequency selected by the selection means. The communication device according to claim 11, characterized by the above.

14. The communication device is a station device, and the other communication device is an access point device. The station device further includes request means for requesting the access point device to delete a link corresponding to the frequency selected by the selection means. The communication device according to claim 11, characterized by the above.

15. The communication device is an access point device, and the other communication device is a station device. The access point device further includes recommendation means for recommending to the station device the deletion of a link corresponding to the frequency selected by the selection means. The communication device according to claim 11, characterized by the above.

16. The communication device is an access point device, and the other communication device is a station device connected to the access point device. The predetermined condition is a condition associated with the number of devices different from the communication device and the other communication device that are using each of the frequencies used in the multi-link communication. When the number of first devices using a first frequency included in the frequencies used for the multi-link communication is greater than the number of second devices using a second frequency different from the first frequency and included in the frequencies used for the multi-link communication, the selection means preferentially selects the first frequency. The communication device according to claim 11, characterized in that.

17. The communication device is a station device, and the other communication device is an access point device. The predetermined condition is a condition associated with the number of other station devices communicating with the access point device using each of the frequencies used for the multi-link communication. When the number of other station devices communicating with the access point device using a first frequency included in the frequencies used for the multi-link communication is greater than the number of other station devices communicating with the access point device using a second frequency different from the first frequency and included in the frequencies used for the multi-link communication, the selection means preferentially selects the first frequency. The communication device according to claim 11, characterized in that.

18. The predetermined condition is a condition associated with STR (Simultaneous Transmit and Receive) in which transmission and reception in the plurality of links are performed independently. When there is a combination of two frequencies included in the frequencies used for the multi-link communication and the combination cannot execute the STR, the selection means preferentially selects the frequencies included in the combination. The communication device according to claim 11, characterized in that.

19. The predetermined condition is a condition associated with the frequency interval between the frequencies used for the multi-link communication. In a combination of two frequencies included in the frequencies used for the multi-link communication, when the frequency interval of the first combination is smaller than the frequency interval of a second combination different from the first combination, the selection means preferentially selects the frequencies included in the first combination. The communication device according to claim 11, characterized in that.

20. The predetermined condition is a condition associated with the available frequency bandwidth in each of the frequencies used for the multi-link communication. When the bandwidth of the frequency band available at a first frequency included in the frequencies used for the multi-link communication is narrower than the bandwidth of the frequency band available at a second frequency included in the frequencies used for the multi-link communication and different from the first frequency, the selection means preferentially selects the first frequency. The communication device according to claim 11, characterized in that.

21. The predetermined condition is a condition associated with the frequency band to which the frequency used for the multi-link communication belongs, The selection means preferentially selects a frequency belonging to a predetermined frequency band from among the frequencies used for the multi-link communication. The communication device according to claim 11, characterized in that.

22. A control method executed by a communication device capable of performing multi-link communication using a plurality of links corresponding to each of a plurality of frequencies conforming to the IEEE 802.11 series standards with another communication device, When increasing the number of links used in parallel in the multi-link communication, a selection step of selecting a frequency associated with the link to be added based on a predetermined condition from among a plurality of candidate frequencies; A notification step of notifying the other communication device of the frequency selected in the selection step. A control method characterized by that.

23. A control method executed by a communication device capable of performing multi-link communication using a plurality of links corresponding to each of a plurality of frequencies conforming to the IEEE 802.11 series standards with another communication device, When reducing the number of links in the multi-link communication, a selection step of selecting a frequency to stop using based on a predetermined condition from among the frequencies used for the multi-link communication; A communication step of performing the multi-link communication with the other communication device without using the frequency selected in the selection step. A control method characterized by that.

24. A program for causing a computer to function as each means included in the communication device according to claim 1.

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