Communication device, control method, and program

Abstract

This communication device receives, from an other communication device, a predetermined frame that includes a predetermined multi-link element. If the predetermined frame is received, the communication device selects a link to be established with the other communication device on the basis of the communication quality of the link that can be established with the other communication device. The communication device establishes the selected link with the other communication device. If a multi-link is established, the communication device performs multi-link communication via the multi-link.

Description

Communication device, control method, and program

[0001] The present invention relates to a communication device that performs wireless communication, a control method for the communication device, and a program.

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard series is known as a major communication standard for wireless LANs. The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax.

[0003] Furthermore, the IEEE 802.11be standard, which is the successor to IEEE 802.11ax, is being developed. A new function of the IEEE 802.11be standard is being considered, which is multi-link communication, in which an AP and a STA establish multiple links on different frequency channels and communicate in parallel. For example, Patent Document 1 describes a mechanism for establishing multiple links for multi-link communication.

[0004] Moreover, APs and STAs that support multi-link communication are called AP MLDs (Multi-Link Devices) and non-AP MLDs (or STA MLDs). Moreover, APs that are associated with AP MLDs and operate on channels different from each other are called affiliated APs, and STAs that are associated with STA MLDs and operate on channels different from each other are called affiliated non-AP STAs (or affiliated STAs).

[0005] Japanese Patent Application Laid-Open No. 2021-103805

[0006] As described above, the IEEE 802.11be standard and its successor standards are considering multi-link communication, in which multiple links are established in parallel between a pair of terminals and communication is performed via the multiple links. In multi-link communication, a STA MLD and an AP MLD simultaneously perform data communication via two or more links, thereby improving throughput.

[0007] However, even if multiple links with poor communication quality are established when the multiple links are established, errors in sending and receiving frames may occur, which may actually reduce communication throughput. Also, even if a link with good communication quality and a link with poor communication quality are established, extra frames are exchanged to exchange information about the link with poor communication quality, which may actually increase communication overhead compared to communication over a single link.

[0008] The present invention has been made in consideration of at least one of the above-mentioned problems. One aspect of the present invention aims to provide a mechanism for improving communication efficiency by selecting an appropriate link when establishing a link. Another aspect of the present invention aims to improve communication efficiency by establishing an appropriate number of links when establishing a link.

[0009] In order to achieve the above object, a communication device according to one embodiment of the present invention has a receiving means for receiving a predetermined frame including a predetermined multilink element from another communication device, a selecting means for selecting a link to be established with the other communication device based on the communication quality of a link that can be established with the other communication device when the receiving means receives the predetermined frame, an establishing means for establishing the link selected by the selecting means with the other communication device, and a communication means for performing multilink communication via the multilink when the establishing means establishes the multilink.

[0010] According to one aspect of the present invention, it is possible to improve communication efficiency by selecting an appropriate link when establishing a link, and according to another aspect of the present invention, it is possible to improve communication efficiency by establishing an appropriate number of links when establishing a link.

[0011] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0012] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0013] FIG. 1 is a diagram showing an example of a network configuration. FIG. 2 is a diagram showing an example of the hardware configuration of an AP MLD and a STA MLD. FIG. 3 is a diagram showing an example of the functional configuration of an AP MLD and a STA MLD. FIG. 4 is a diagram showing an example of a sequence of a Multi-Link connection. FIG. 5 is a diagram showing an example of a flowchart related to link establishment in embodiment 1. FIG. 6 is a diagram showing an example of a flowchart related to link establishment in embodiment 2. FIG. 7 is a diagram showing an example of a flowchart related to link establishment in embodiment 3.

[0014] <Embodiment 1> Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the configurations shown in the following embodiments are merely examples, and the present invention is not limited to the configurations shown in the drawings.

[0015] FIG. 1 shows an example of a network configuration according to this embodiment. FIG. 1 shows an example of a network configuration in which a STA MLD 102 operating as a terminal station participates in a network 100 established by an AP MLD 101 operating as a base station. Note that AP MLD is an abbreviation for Access Point Multi-Link Device, and STA MLD is an abbreviation for Station Multi-Link Device. The STA MLD is also referred to as a non-AP MLD. The AP MLD 101 and the STA MLD 102 are communication devices capable of transmitting and receiving signals to and from each other. Furthermore, each communication device (AP MLD 101, STA MLD 102) can perform wireless communication compliant with the IEEE 802.11be (EHT) standard. Note that IEEE stands for Institute of Electrical and Electronics Engineers. Furthermore, EHT stands for Extremely High Throughput. Note that EHT may also be interpreted as an abbreviation for Extreme High Throughput. Each communication device can communicate at frequencies in the 2.4 GHz band, the 5 GHz band, and the 6 GHz band. The frequency bands used by each communication device are not limited to these, and a different frequency band, such as the 60 GHz band, may be used. Furthermore, each communication device can communicate using channels with frequency widths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz. The frequency width of the channel used by each communication device is not limited to this, and different frequency widths such as 240 MHz and 4 MHz may be used.

[0016] Although each communication device is described as being compatible with the IEEE 802.11be standard, it may also be compatible with a legacy standard that predates the IEEE 802.11be standard. Specifically, each communication device may be compatible with at least one of the IEEE 802.11a / b / g / n / ac / ax standards. Furthermore, each communication device may be compatible with any one of successor standards, including the IEEE 802.11bn standard, which is the successor standard to the IEEE 802.11be standard. The IEEE 802.11bn standard is the successor standard to the IEEE 802.11be standard, which aims to achieve improved reliability and low latency, and may also be referred to as IEEE 802.11UHR (Ultra High Reliability). Furthermore, a wireless frame communicated according to the 11bn standard is also referred to as a UHR PPDU. PPDU stands for PLCP Protocol Data Unit, and PLCP stands for Physical Layer Convergence Protocol. The IEEE 802.11 standard, including the above-mentioned legacy standard and successor standard, is referred to as the IEEE 802.11 series standard. In addition to the IEEE 802.11 series standard, other communication standards such as Bluetooth (registered trademark), NFC, UWB, ZigBee, and MBOA may also be supported. UWB stands for Ultra Wide Band, and MBOA stands for Multi Band OFDM Alliance. Furthermore, NFC stands for Near Field Communication. UWB includes wireless USB, wireless 1394, WiNET, etc. Furthermore, it may also be compatible with wired communication standards such as wired LAN. Specific examples of the AP MLD 101 include, but are not limited to, a wireless LAN router and a personal computer (PC), and any communication device capable of operating as an access point may be used. Furthermore, the AP MLD 101 may be an information processing device such as a wireless chip capable of performing wireless communication compliant with the IEEE 802.11be standard.Specific examples of the STA MLD 102 include, but are not limited to, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, a headset, a network camera, a printer, a projector, etc. The STA MLD 102 may also be an information processing device such as a wireless chip capable of performing wireless communication in accordance with the IEEE 802.11be standard.

[0017] The AP MLD 101 and the STA MLD 102 are multi-link devices (MLDs) that can establish multiple links (multi-links) of different frequency channels and perform multi-link communication via the multiple links. The AP MLD includes multiple affiliated APs (hereinafter, APs) for establishing the multiple links. The STA MLD includes multiple affiliated STAs (hereinafter, STAs) for establishing the multiple links.

[0018] In the IEEE 802.11 series standards, the bandwidth of each frequency channel is defined as 20 MHz. Here, a frequency channel refers to a frequency channel defined in the IEEE 802.11 series standards, which define multiple frequency channels in each of the 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz frequency bands. Note that a single frequency channel may utilize a bandwidth of 40 MHz or more by bonding adjacent frequency channels. For example, the AP MLD 101 can establish and communicate with the STA MLD 102 via a link 103 over a first frequency channel in the 5 GHz band. In parallel with this, the STA MLD 102 can establish and communicate with the AP MLD 102 via a link 104 over a second frequency channel in the 6 GHz band. In this case, the STA MLD 102 performs multi-link communication maintaining a second link 104 over a second frequency channel in parallel with a link 103 over a first frequency channel.

[0019] 2 shows an example of the hardware configuration of the STA MLD 102 in this embodiment. The STA MLD 102 has a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207. Note that there may be multiple antennas.

[0020] The storage unit 201 is composed of one or more memories such as ROM and RAM, and stores various information such as computer programs for performing various operations described below and communication parameters for wireless communication. ROM stands for Read Only Memory, and RAM stands for Random Access Memory. 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 also be used as the storage unit 201. Furthermore, the storage unit 201 may include multiple memories.

[0021] The control unit 202 is configured with one or more processors, such as a CPU or MPU, and controls the entire STA MLD 102 by executing a computer program stored in the storage unit 201. The control unit 202 may also control the entire STA MLD 102 in cooperation with the computer program stored in the storage unit 201 and an OS (Operating System). The control unit 202 also generates data and signals (radio frames) to be transmitted in communications with other communication devices. The term "CPU" stands for "Central Processing Unit," and the term "MPU" stands for "Micro Processing Unit." The control unit 202 may also include multiple processors, such as multi-core processors, and the entire STA MLD 102 may be controlled by the multiple processors.

[0022] The control unit 202 also controls the function unit 203 to perform predetermined processes such as wireless communication, image capture, printing, projection, etc. The function unit 203 is hardware that enables the STA MLD 102 to perform predetermined processes.

[0023] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user via a monitor screen or a speaker. Here, the output from the output unit 205 may be a display on a monitor screen, an audio output from a speaker, a vibration output, or the like. Note that both the input unit 204 and the output unit 205 may be implemented in a single module, such as a touch panel. Furthermore, the input unit 204 and the output unit 205 may be integrated with the STA MLD 102 or may be separate units.

[0024] The communication unit 206 controls wireless communication conforming to the IEEE 802.11be standard. The communication unit 206 may also control wireless communication conforming to other IEEE 802.11 series standards in addition to the IEEE 802.11be standard, or wired communication such as a wired LAN. The communication unit 206 controls the antenna 207 to transmit and receive signals for wireless communication generated by the control unit 202.

[0025] If the STA MLD 102 supports the NFC standard, Bluetooth standard, or the like in addition to the IEEE 802.11be standard, it may control wireless communications in accordance with these communication standards. Furthermore, if the STA MLD 102 can perform wireless communications in accordance with multiple communication standards, it may be configured to have separate communication units and antennas compatible with each communication standard. The STA MLD 102 communicates data such as image data, text data, and video data with the AP MLD 101 via the communication unit 206. The antenna 207 may be configured separately from the communication unit 206, or may be configured together with the communication unit 206 as a single module.

[0026] The antenna 207 is an antenna capable of communication in the 2.4 GHz band, the 5 GHz band, and the 6 GHz band. The STA MLD 102 may have one or more antennas. Also, a different antenna may be provided for each frequency band. Furthermore, if the STA MLD 102 has multiple antennas, it may have a communication unit 206 corresponding to each antenna.

[0027] The AP MLD 101 has the same hardware configuration as the STA MLD 102. The STA MLD 102 may have as many components as the STAs included in the STA MLD, or may have components shared by the STAs.

[0028] FIG. 3 is a block diagram showing an example of the functional configuration of the STA MLD 102 in this embodiment. In this embodiment, each functional block is stored as a program in the storage unit 201, and the function is implemented by executing the program by the control unit 202. By executing the program, the control unit 202 controls each hardware and performs calculations and processing of information to realize each function. Note that some or all of the functional blocks may be implemented as hardware. In this case, some or all of the functional blocks may be configured by, for example, an ACIC (Application Specific Integrated Circuit). Note that in this embodiment, the AP MLD 101 also has a similar configuration, but for the AP MLD 101, the affiliated STA setting unit 302 in this configuration is an affiliated AP setting unit.

[0029] In this embodiment, the STA MLD 102 includes a multi-link control unit 301 , an affiliated STA setting unit 302 , a frame generation unit 303 , a frame transmission / reception unit 304 , a communication quality measurement unit 305 , and a UI control unit 306 .

[0030] The multi-link control unit 301 controls processes related to link establishment, such as link establishment process and communication start process for establishing one or more links used by the STA MLD 102 for wireless communication with the AP MLD 101, link addition and deletion process after link establishment, and communication termination process for deleting all links. The link establishment process mainly consists of authentication process, association process, and 4-Way Hand Shake (4WHS) process.

[0031] The affiliated STA setting unit 302 selects and determines affiliated STAs in various processes. For example, it controls the selection and determination of affiliated STAs of the STA MLD 102 used in link establishment processing, and the selection and determination of affiliated STAs of the STA MLD 102 used in frame transmission and reception processing.

[0032] The frame processing unit 303 performs processing to generate wireless control frames to be transmitted by the frame transmitting / receiving unit 304 and processing to analyze frames received via the frame transmitting / receiving unit 304. The frame processing unit 303 refers to operation settings such as parameters for communication stored in the storage unit 201 and performs processing to interpret and generate frames. The operation settings can also be configured to be changed based on user operations received via the UI control unit 306. Information about the frames generated by the processing unit 303 is transmitted to the communication partner via the frame transmitting / receiving unit 304. Information about frames received by the frame transmitting / receiving unit 304 is passed to the frame processing unit 302 and analyzed.

[0033] The frame transmitting / receiving unit 304 includes an antenna and circuit for transmitting and receiving wireless signals to and from other wireless LAN devices, and a program for controlling them. The frame transmitting / receiving unit 304 controls wireless LAN communications based on the frames generated by the frame processing unit 303 in accordance with the IEEE 802.11 standard series.

[0034] The communication quality measurement unit 305 measures the communication quality of the communication environment based on the Beacon / Probe Response frame received by the frame transmission / reception unit 304, etc. Note that communication quality includes, but is not limited to, RSSI, SNR, MCS, etc. Note that RSSI is an abbreviation for Received Signal Strength Indicator, and is a value indicating the strength of radio waves. Furthermore, SNR is an abbreviation for Signal-to-Noise Ratio (or Signal Noise Rate), and is a value indicating the ratio between the strength of radio waves from the target terminal and the strength of radio waves from other terminals. Furthermore, MCS is an abbreviation for Modulation and Coding Scheme, and is information that indexes a combination of wireless modulation methods, coding rates, etc.

[0035] The UI control unit 306 is composed of hardware related to a user interface, such as a touch panel or buttons, for accepting user operations, and a program for controlling these. For example, the multilink control unit 301 accepts user operations via the UI control unit 306, thereby selecting a remote device to which the STA MLD 102 will connect. Furthermore, the affiliated STA setting unit 302 accepts user operations via the UI control unit 306, thereby selecting and determining the affiliated STA of the STA MLD 102 to be used when the STA MLD 102 establishes a link. The UI control unit 306 may further have a function for displaying information, such as audio output, to the user.

[0036] Next, an overview of the process of establishing multi-link communication will be described. Fig. 4 shows a sequence diagram illustrating an example of the multi-link establishment process in this embodiment. Note that in this embodiment, an overview of the process of searching and detecting surrounding MLDs by the STA MLD and AP MLD using a beacon frame and a probe request / response frame will be described. Then, as the link establishment process, a process of establishing a link with the MLD detected in the search process by the STA MLD and AP MLD using an authentication request / response frame and an association request / response frame will be described.

[0037] In Figure 4, AP MLD 101 includes affiliated AP1 (AP1), affiliated AP2 (AP2), and affiliated AP3 (AP3). AP1 operates in the 2.4 GHz band, AP2 in the 5 GHz band, and AP3 in the 6 GHz band. STA MLD 102 includes affiliated STA1 (STA1), affiliated STA2 (STA2), and affiliated STA3 (STA3). STA1 operates in the 2.4 GHz band, STA2 in the 5 GHz band, and STA3 in the 6 GHz band.

[0038] First, each AP included in the AP MLD 101 transmits a beacon frame in the frequency band in which the AP operates, thereby transmitting information about the network established by the AP MLD 101 to surrounding communication devices. Note that in this embodiment, each AP (AP1, AP2, AP3) transmits a beacon frame, but this is not limiting, and only selected APs (for example, only AP1) may transmit a beacon frame.

[0039] Next, each STA included in the STA MLD 102 transmits a Probe Request frame in the frequency band in which each STA operates, thereby searching for and acquiring information about the surroundings of the STA MLD 102. Note that in this embodiment, each STA (STA1, STA2, STA3) transmits a Probe Request frame, but this is not limited thereto, and only a selected STA (for example, only STA1) may transmit an ML Probe Request frame. Note that the ML Probe Request frame is a search request that includes a Multi-Link element, which will be described later, and is a frame that is transmitted to search for surrounding AP MLDs. Each STA acquires information about the AP MLD 101 by receiving a Probe Response frame (or an ML Probe Response frame) transmitted by the AP of the AP MLD 101 as a response to the transmitted Probe Request frame. In contrast, the AP MLD 101 acquires information about the STA MLD 102 by receiving a Probe Request frame (or an ML Probe Request frame) transmitted by the STA MLD 102.

[0040] In this embodiment, the AP MLD 101 transmits a Beacon frame, and then the STA MLD 102 transmits a Probe Request frame. However, this is not limiting, and the STA MLD 102 may transmit the Probe Request frame first, or the AP MLD 101 may not transmit a Beacon.

[0041] In this way, in the search process of this embodiment, each communication device includes a multi-link element in each frame it transmits. Note that a multi-link element is, for example, a basic multi-link element or a probe request multi-link element. Then, based on the fact that a multi-link element is included in any frame received in this search process, each communication device determines that a multi-link can be established in connection with the communication device that transmitted the frame including the multi-link element. That is, the AP MLD 101 determines that the STA MLD 102 is an MLD and that a multi-link can be established based on the fact that a multi-link element is included in the probe request frame received from the STA MLD 102. Also, the STA MLD 102 determines that the AP MLD 101 is an MLD and that a multi-link can be established based on the fact that a multi-link element is included in the beacon frame or probe response frame received from the AP MLD 101.

[0042] Furthermore, the STA MLD 102 acquires information about each AP of the opposing AP MLD 101 in this search process as information for establishing a link in the link establishment process described below. The STA MLD 102 acquires frequency band and channel information about each AP belonging to the AP 101 from an RNR (Reduced Neighbor Report) element included in the Beacon frame or Probe Response frame transmitted by the AP MLD 101. The STA MLD 102 then performs the link establishment process described below based on the information about each AP acquired from the RNR element.

[0043] Next, the link establishment process of each communication device in the multi-link establishment process will be described. In the link establishment process of this embodiment, the AP MLD 101 and the STA MLD 102 establish a link by transmitting and receiving various frames such as an authentication frame, an association frame, and frames related to 4-way handshake.

[0044] First, the STA MLD 102 transmits an Authentication Request frame using one of the links it wishes to establish with the AP MLD 101. Communication of various frames in this establishment process is assumed to be performed over the link over which the Authentication Request frame was transmitted. In response to this, the AP MLD 101 transmits an Authentication Response frame. In this embodiment, the STA MLD 102 and the AP MLD 101 establish a multi-link by transmitting and receiving various frames using STA1 and AP1, respectively.

[0045] Next, the STA MLD 102 transmits an Association Request frame including information about links that it wishes to establish with the AP MLD 101. For example, the STA MLD 102 indicates that it wishes to establish multiple links with the AP MLD 101 by including information about multiple links in which AP1, AP2, and AP3 operate in the frame. In response, the AP MLD 101 transmits an Association Response frame including information permitting (or denying) the establishment of links with the STA MLD 102. By permitting the establishment of multiple links in the Association Response frame, multiple links are established between the STA MLD 102 and the AP MLD 101.

[0046] The above is the establishment process of each communication device in the multi-link establishment process. In the above description, the establishment process of this embodiment is described as establishing three links, namely, links in the 2.4 GHz band, the 5 GHz band, and the 6 GHz band, but this is not limited to this. For example, only one link (single link) may be established in the link establishment process.

[0047] Furthermore, in multi-link communication, links between communication devices may be established via multiple different channels within the same frequency band. For example, a first link may be established on channel 36 in the 5 GHz band, and a second link may be established on channel 48 in the 5 GHz band. Links of the same frequency band and links of different frequency bands may be mixed. For example, the AP MLD 101 and the STA MLD 102 may establish a link 103 on channel 36 in the 5 GHz band, as well as a link on channel 149 in the 5 GHz band and a link on channel 15 in the 6 GHz band. By establishing multiple connections with the STA MLD 102 on different frequency bands, the AP MLD 101 can establish communication with the STA MLD 102 on another band even when one band is congested, thereby preventing a decrease in throughput and communication delays in communication with the STA MLD 102.

[0048] However, if the establishment process described in Figure 4 simply establishes all communication links that can be established based on the device's capabilities when establishing the multiple links, multiple links may be established, including links with poor communication quality.

[0049] Here, even if multiple links with poor communication quality are established, errors may occur in sending and receiving frames, which may not result in an improvement in communication throughput. Furthermore, even if a link with good communication quality and a link with poor communication quality are established, the exchange of information about the link with poor communication quality may result in the exchange of extra frames, which may actually increase communication overhead compared to communication via a single link. In light of this, this embodiment provides a mechanism for establishing more suitable links by measuring communication quality when establishing multiple links and performing control to select the link to be established based on the communication quality. A detailed description will be given below using a flowchart. FIG. 5 is a flowchart showing an example of a process in which the STA MLD 102 determines which link to use to establish a link (multi-link or single link) after recognizing that the opposing AP MLD 101 is a communication device (MLD) capable of establishing a multi-link. In this embodiment, the STA MLD 102 determines which link to use to establish a link based on the communication quality of each link. In this embodiment, it is assumed that each process shown in the flowchart of FIG. 5 is realized by the processor of the control unit 202 of the STA MLD 102 executing a program for implementing each control module. Note that data transmission and reception processes are realized in cooperation with hardware such as a communication unit. Note that, in cases where it is necessary to clarify the subject of a process, each functional unit realized by the control unit 202 executing a program will be described as the subject. Note that, as mentioned above, some or all of the processes can also be realized by hardware such as an ASIC, ASSP, or SoC. ASSP stands for Application Specific Standard Product, and SoC stands for System on a Chip.

[0050] This process may be started based on the control of the multi-link control unit 301, for example, when the power of the STA MLD 102 is turned on.

[0051] First, the frame transmission / reception unit 304 of the STA MLD 102 receives a beacon frame or a probe response frame transmitted by the opposite AP (S501). In this embodiment, it is assumed that the beacon / probe response frame transmitted by AP1 of the AP MLD 101 is received by STA1 of the STA MLD 102.

[0052] Next, the frame processing unit 303 of the STA MLD 102 analyzes the Beacon / Probe Response frame received by the frame transmission / reception unit 304 in S501. Then, based on the results of this analysis, it determines whether the opposing AP is an MLD that supports multi-link (S502). In S502, it determines whether the opposing AP is an MLD based on whether the Beacon / Probe Response frame transmitted by the opposing AP contains a Multi-Link element. If the frame contains a Multi-Link element, it determines that the opposing AP that transmitted the frame is an MLD and is an AP that can establish multi-link. On the other hand, if the Beacon / Probe Response frame received in S601 does not include a Multi-Link element, a single link is established between the opposing AP that transmitted the frame and the link that received the frame (S503). Note that in this embodiment, the opposing AP is the AP MLD 101, and the Beacon / Probe Response frame transmitted by AP1 of the AP MLD 101 includes a Multi-Link element.

[0053] If it is determined in S502 that the opposite AP is an AP MLD that supports multi-link, the STA MLD 102 analyzes the RNR element included in the Beacon / Probe Response frame transmitted by the AP MLD. Based on the analysis results, the STA MLD 102 acquires information about APs other than the AP that transmitted the frame (S504). In this embodiment, the STA MLD 102 acquires information about APs 2 and 3 of the AP MLD 101 from the Beacon / Probe Response frame transmitted by AP 1 of the AP MLD 101. Also, here, for example, information that can identify the frequency band of the link on which each AP operates, information that can identify the channel, and the like are acquired from the RNR Element included in the Beacon / Probe Response Beacon / Probe Response frame.

[0054] Next, based on the information acquired in S504, the beacon / probe response frames transmitted by AP2 and AP3 are received, and detailed information about AP2 and AP3 is acquired (S505).

[0055] Next, based on the frame received by the frame transmission / reception unit 304 of the STA MLD 102, the communication quality measurement unit 305 measures the communication quality of each link on which each AP belonging to the AP MLD 101 operates (S506). For example, the STA MLD 102 transmits a Probe Request frame to each AP on the link on which each AP belonging to the AP MLD 101 operates via the frame transmission / reception unit 304, and receives a Probe Response frame from each AP. Then, the communication quality determination unit 305 measures communication quality information based on the received frame.

[0056] Then, it is determined whether the communication quality of each link acquired in S506 exceeds a predetermined threshold. (S507) Here, the predetermined threshold may be, for example, RSSI = -30 dBm or RSSI = -50 dBm. By setting such a threshold, it becomes possible to select only links with high communication quality as links to be established. The predetermined threshold may also be RSSI = -90 dBm or RSSI = -100 dBm. By setting such a threshold, it becomes possible to select links that ensure a minimum level of communication quality as links to be established.

[0057] Furthermore, the predetermined threshold may be, for example, SNR=40, SNR=25, or SNR=20. By setting such a threshold, it becomes possible to select only links with high communication quality as links to be established. Furthermore, the predetermined threshold may be SNR=10. By setting such a threshold, it becomes possible to select links that ensure a minimum level of communication quality as links to be established.

[0058] Furthermore, the predetermined threshold may be, for example, the communication quality required to use MCS0. MCS is an indexed combination of wireless modulation schemes, coding rates, etc., and the MCS used varies depending on the communication environment. MCS0 is the scheme with the lowest throughput and is used when the communication environment is extremely poor. If the RSSI is below the threshold for using MCS0, it may be determined that the link is in a poor communication environment. Note that, although the communication quality required to use MCS0 is set as the predetermined threshold in this embodiment, this is not limiting. For example, the communication quality required to use an MCS such as MCS4, which is used in a communication environment better than MCS0, may also be set as the predetermined threshold. Note that the above-mentioned predetermined threshold is merely an example, and the system may be configured so that the user can set the predetermined threshold via the UI control unit 306.

[0059] If it is determined in S507 that there are a plurality of links whose communication quality exceeds a predetermined threshold, a multi-link is established between the AP MLD 101 and the plurality of links (S509).

[0060] On the other hand, if the result of the determination in S507 is that there are no links whose communication quality exceeds the predetermined threshold, a single link is established with the AP MLD 101 (S508). Note that if there is no link whose communication quality exceeds the predetermined threshold, a single link may be established with the link with the best communication quality.

[0061] The above describes an embodiment in which the STA MLD 102 establishes a multi-link based on the presence of multiple links whose communication quality exceeds a predetermined threshold when establishing a link with the AP MLD 101. In this way, by appropriately determining whether or not the STA MLD 102 establishes a multi-link with the AP MLD 101, the STA 102 can prevent the overhead from increasing after establishing a multi-link with the AP 101 compared to establishing a single link.

[0062] Second Embodiment In the first embodiment, the case where communication quality is used as a criterion for selecting a link is exemplified. In the second embodiment, a mechanism for selecting a link with fewer restrictions on transmission and reception as a criterion for selecting a link will be described.

[0063] There are two types of multilinks: one capable of STR operation and one capable of only NSTR operation (not capable of STR operation). A multilink capable of STR operation is a multilink consisting of a pair of links in which, when a multilink including at least a first link and a second link is established with another communication device, transmission operation is possible on the second link while reception operation is being performed on the first link. In contrast, a multilink capable of only NSTR operation is a multilink consisting of a pair of links with the constraint that the second link must perform the same transmission and reception operation in synchronization with the transmission and reception operation of the first link. Therefore, a multilink capable of STR operation is expected to have improved communication throughput compared to a multilink that is subject to the constraint of NSTR operation.

[0064] Therefore, in this embodiment, in order to establish a multi-link that is not restricted by the above-mentioned NSTR (STR operable), when the STA MLD 102 establishes a link with the AP MLD 101, it is determined whether to establish the multi-link based on whether the AP MLD 101 is capable of STR operation when the multi-link is established.

[0065] Note that STR is an abbreviation for Simultaneous Transmit and Receive, and NSTR is an abbreviation for Nonsimultaneous Transmit and Receive.

[0066] The flow of this embodiment will be described below with reference to FIG.

[0067] The processing from S601 to S604 in this embodiment is the same as the processing from S501 to S504 in the first embodiment, and therefore a description thereof will be omitted.

[0068] In this embodiment, when a multi-link is established with the opposing AP MLD, it is determined whether or not to perform a connection via the multi-link based on whether or not STR operation is possible (S605).

[0069] For example, whether the opposing AP is capable of STR operation is determined based on information contained in the Multi-Link element of the Beacon / Probe Response frame transmitted by the opposing AP MLD. More specifically, this is determined by looking at bit 7 of the MLD Capabilities and Operations subfield of the Multi-Link element. If this bit is 1, it is determined that the opposing AP MLD is capable of STR operation, and if this bit is 0, it is determined that the opposing AP MLD is not capable of STR operation.

[0070] As a result of this determination, it is determined that the opposing AP MLD can operate in STR and that establishing a multi-link is expected to improve communication throughput, and so a multi-link is established (S607).On the other hand, if it is determined in S607 that the opposing AP MLD cannot operate in STR, a single link is established with the AP with the best communication quality based on the communication quality information of each link calculated in S606 (S606).

[0071] Third Embodiment In the first embodiment, a case where communication quality is used as a criterion for selecting a link was exemplified. In the second embodiment, a case where a link with fewer restrictions on transmission and reception is selected as a criterion for selecting a link was exemplified. In the third embodiment, a flow will be described in which, when the STA MLD 102 establishes a link with the AP MLD 101, it is determined whether to establish a multi-link based on the remaining battery power of the STA MLD 102.

[0072] The processing from S701 to S704 in this embodiment is the same as the processing from S501 to S504 in the first embodiment, and therefore a description thereof will be omitted.

[0073] In this embodiment, after the calculation of the communication quality information of each AP is completed, it is confirmed whether the remaining battery charge of the STA MLD 102 is equal to or greater than a predetermined threshold (S705). If the remaining battery charge of the STA MLD 102 is equal to or greater than the predetermined threshold, a multi-link is established with the AP MLD 101 (S707). On the other hand, if the remaining battery charge of the STA MLD 102 is less than the predetermined threshold, a single-link is established with the AP MLD 101 (S706).

[0074] In addition, the predetermined threshold in this embodiment may be, for example, a remaining battery capacity of 20% or 10%. By setting such a threshold, when it is desired to reduce power consumption, it is possible to further reduce power consumption by not establishing a multi-link.

[0075] <Other Embodiments> Each communication device described in each of the above embodiments may be a printer having a printing means. When operating as a printer, it is possible to print image data acquired through data exchange with a partner device onto a sheet of paper or the like. The printing method of the printer may be an electrophotographic method that achieves printing by transferring and fixing toner onto a sheet of paper or the like, or an inkjet method that achieves printing by ejecting color material onto a sheet of paper or the like.

[0076] Furthermore, each communication device described in this embodiment may be a digital still camera having an image capturing means. When operating as a camera, it is possible to exchange captured image data with a partner device, for example.

[0077] Furthermore, in the third embodiment, whether or not to establish a multi-link with the peer AP MLD is selected based on the remaining battery power of the STA MLD, but this is not limiting. For example, whether or not to establish a multi-link may be determined based on whether the STA MLD is operating in a power-saving mode that consumes less power than during normal operation. In this case, when the STA MLD is operating normally, a multi-link is established with the AP MLD. On the other hand, when the STA MLD is operating in a power-saving mode, a single link is established with the AP MLD.

[0078] For example, the STA MLD 102 may be configured to establish a multi-link only when the STR operation is possible when there are a plurality of links whose communication quality exceeds a predetermined threshold among the links that can be established with the AP MLD 101, and when a multi-link is established with the plurality of links whose communication quality exceeds the predetermined threshold.

[0079] Alternatively, a recording medium on which program code for software that realizes the above-described functions is recorded may be supplied to a system or device, and the computer (CPU, MPU) of the system or device may read and execute the program code stored on the recording medium. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiments, and the recording medium on which the program code is stored constitutes the above-described device.

[0080] Examples of storage media that can be used to supply the program code include flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, and DVDs.

[0081] Furthermore, the above-mentioned functions may be realized not only by the computer executing the read program code, but also by the operating system (OS) running on the computer performing some or all of the actual processing based on the instructions of the program code.

[0082] Furthermore, the program code read from the storage medium may be written to a memory provided in a function expansion board inserted into a computer or a function expansion unit connected to the computer, and a CPU provided in the function expansion board or function expansion unit may then perform some or all of the actual processing based on the instructions of the program code to realize the above-mentioned functions.

[0083] The present invention can also be realized by supplying a program that realizes one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., an ASIC) that realizes one or more of the functions.

[0084] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0085] This application claims priority based on Japanese Patent Application No. 2023-125130, filed on July 31, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A communication device comprising: a receiving means for receiving a predetermined frame including a predetermined multilink element from another communication device; a selecting means for selecting a link to be established with the other communication device based on the communication quality of a link that can be established with the other communication device when the receiving means receives the predetermined frame; an establishing means for establishing the link selected by the selecting means with the other communication device; and a communication means for performing multilink communication via the multilink when the establishing means establishes a multilink.

2. The communication device according to claim 1, wherein when said selection means selects only one link as the link to be established, said establishment means establishes a single link with said other communication device.

3. A communication device as described in claim 1 or claim 2, characterized in that when the selection means selects multiple links as links to be established with the other communication device, the establishment means establishes the multi-link consisting of the multiple links.

4. A communication device according to any one of claims 1 to 3, characterized in that, when the receiving means receives the predetermined frame, the selecting means selects a link having a communication quality higher than a predetermined threshold.

5. A communication device according to any one of claims 1 to 4, characterized in that the predetermined frame is a management frame.

6. The communication device according to any one of claims 1 to 5, wherein the communication quality is a Received Signal Strength Indicator (RSSI).

7. The communication device according to any one of claims 1 to 5, wherein the communication quality is a signal-to-noise ratio (SNR).

8. A communication device according to any one of claims 3 to 7, characterized in that, if there is no link whose communication quality is higher than a predetermined threshold, the selection means selects the link with the highest communication quality among the links that can be established.

9. A method for controlling a communication device, comprising: a receiving step of receiving a predetermined frame including a predetermined multilink element from another communication device; a selection means for selecting a link to be established with the other communication device based on the communication quality of a link that can be established with the other communication device when the predetermined frame is received by the receiving step; an establishment means for establishing the link selected by the selection means with the other communication device; and a communication means for performing multilink communication via the multilink when the establishment means establishes a multilink.

10. A program for causing a computer to function as the control method for a communication device according to any one of claims 9.

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