Communication device, communication method, and program

Abstract

To provide a technique to improve communication performance and power performance in a system in which multi-link communication is performed.SOLUTION: A communication device establishes a plurality of communication links with another communication device, acquires information indicating whether the another communication device can execute communication according to a predetermined communication method for performing communication by, with the plurality of communication links being maintained, using some of the plurality of communication links and not using the rest of the communication links, and when the another communication device can execute the communication according to the predetermined communication method, and should execute the communication according to the predetermined communication method, starts the communication according to the predetermined communication method on the basis of control performed by the another communication device.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to data communication 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. For example, in the latest IEEE 802.11ax standard, technologies for improving the communication speed under congested conditions in addition to a high peak throughput of up to 9.6 gigabits per second (Gbps) using OFDMA (Orthogonal Frequency Division Multiple Access) are standardized. Note that OFDMA is an abbreviation for Orthogonal frequency-division multiple access.

[0003] To develop a successor standard aiming for further throughput improvement, frequency utilization efficiency, and communication latency improvement, a new Task Group for developing the IEEE 802.11be standard has been established in the IEEE 802.11 Working Group. In this Task Group, Multi-link communication is being considered as one of the new functions defined in the IEEE 802.11be standard. In multi-link communication, a communication device called a Multi-link device (MLD) uses multiple links in parallel by coordinating and cooperating multiple communication interfaces. Patent Document 1 discloses Enhanced Multi-Link Multi-Radio (EMLMR) that performs initial frame exchange with a predetermined number of spatial streams for each link of multi-link communication and then executes frame exchange on that link. On the other hand, in the IEEE 802.11be standard, as a form of multi-link communication, Enhanced Multi-Link Single Radio (EMLSR) is planned to be defined, which communicates using one link at a time while maintaining multiple links established between MLDs. EMLSR is an abbreviation for Enhanced Multi-Link Single Radio.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When performing multi-link communication, the power consumption of the communication device increases compared to the case of performing communication on a single link. At this time, by using an EMLSR that communicates on one link at a time, it becomes possible to suppress the power consumption of the communication device. Also, in EMLSR, since one link is selectively used from among a plurality of links, for example, in an environment where communication is congested, the communication performance such as delay characteristics can be improved by appropriately selecting available links. However, performing multi-link communication may also improve communication performance and power performance. For example, it is also considered that by performing communication at high speed using multi-link communication, the delay is reduced and the power consumption is also suppressed. Thus, by using EMLSR, the communication performance and power saving effect may be improved, but there may also be cases where the communication performance and power saving effect are not improved due to extra processing being performed. The present invention provides a technique for improving communication performance and power performance in a system in which multi-link communication capable of using EMLSR is performed.

Means for Solving the Problems

[0006] A communication device according to an aspect of the present invention includes an establishing means for establishing a plurality of communication links with another communication device, and a part of the plurality of communication links is selectively used while maintaining the plurality of communication links, and communication is performed without using the remaining part. An acquisition means for acquiring information indicating whether the other communication device can execute communication by a predetermined communication method, and when the other communication device can execute communication by the predetermined communication method and communication by the predetermined communication method should be executed, a communication means for starting communication by the predetermined communication method based on control by the other communication device.

Effects of the Invention

[0007] According to the present invention, it is possible to improve communication performance and power performance in a system in which multi-link communication is performed.

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 to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] (System Configuration) Fig. 1 shows a configuration example of the wireless communication system according to this embodiment. This wireless communication system is configured to include, for example, one access point (AP) 101 and one station (STA) 102. AP 101 and STA 102 are wireless communication devices capable of performing wireless communication compliant with the IEEE 802.11 series of standards including the IEEE 802.11be standard. Note that IEEE is the abbreviation of Institute of Electrical and Electronics Engineers. Also, the IEEE 802.11be standard may also be called the EHT standard. EHT may be the abbreviation of Extremely High Throughput. The IEEE 802.11 series of standards may include the IEEE 802.11a / b / g / n / ac / ax standards. These standards may be called legacy standards. That is, in addition to the IEEE 802.11be standard, AP 101 and STA 102 may be compatible with one or more of the legacy standards. The network 110 formed by AP 101 indicates the range within which AP 101 and STA 102 can communicate. That is, within the range of network 110, STA 102 can receive the signal transmitted by AP 101, and the signal transmitted by STA 102 can be received by AP 101. Note that in addition to the IEEE 802.11 series of standards, AP 101 and STA 102 may also be compatible with other communication standards such as Bluetooth (registered trademark), NFC, UWB, ZigBee, and MBOA. Note that UWB is the abbreviation of Ultra Wide Band, and MBOA is the abbreviation of Multi Band OFDM Alliance. Also, NFC is the abbreviation of Near Field Communication. UWB includes wireless USB, wireless 1394, WiNET, etc. Also, AP 101 and STA 102 may be compatible with the communication standards of wired communication such as wired LAN.

[0011] Note that in FIG. 1, a state where one AP101 and one STA102 exist is shown, but there may be a plurality of AP101s and STA102s. Also, at that time, a plurality of STA102s may be connected to one AP101, or one STA102 may be connected to a plurality of AP101s. The AP101 may be a wireless LAN router, a personal computer (PC), etc., but is not limited thereto. Further, the STA102 may be any electronic device such as a smartphone, a tablet, a mobile phone, a PC, a video camera, a headset, a printer, a display, etc., but is not limited thereto. Also, the AP101 and the STA102 may be information processing devices such as wireless chips capable of performing wireless communication compliant with the IEEE802.11be standard. In the present embodiment, the AP101 and the STA102 may sometimes be referred to as communication devices without distinction.

[0012] One of the new features defined in the IEEE802.11be standard is multi-link communication. In the previous IEEE802.11 series standards, STA102 established a single link with AP101 for data communication. In multi-link communication, STA102 can improve throughput by performing data communication in parallel using two or more links with AP101. Also, in the IEEE802.11be standard, support for the 6GHz band is being considered to expand the frequency bands available to communication devices. That is, in the IEEE802.11 series standards, the use of each frequency band of 2.4GHz band, 5GHz band, 6GHz band, and 60GHz band is defined and can be used for multi-link communication. A plurality of frequency channels are defined for each frequency band. For example, a channel using a bandwidth of 20MHz is defined as a frequency channel used for one wireless link. Note that in the IEEE802.11 series standards, by using adjacent frequency channels together (bonding), a bandwidth of 40MHz or more can be used in one frequency channel. As an example, AP101 can establish and communicate a first link with STA102 using a first frequency channel in the 5GHz band. Also, STA102 can establish and communicate a second link with AP101 using a second frequency channel in the 6GHz band. In this case, AP101 and STA102 can perform multi-link communication using the second link in parallel while maintaining the first link. Thus, in this embodiment, AP101 and STA102 are configured to be able to perform multi-link communication using a plurality of links in network 110.

[0013] In FIG. 1, an example is shown in which three wireless links (links 121, 122, and 123) are established between the AP 101 and the STA 102. As described above, each wireless link may have a different frequency band from each other. For example, the AP 101 and the STA 102 can establish in parallel a link 121 using the 5 GHz band, a link 122 using the 6 GHz band, and a link 123 using the 2.4 GHz band. Also, a plurality of wireless links may be configured by a plurality of different frequency channels belonging to the same frequency band. For example, a multi-link may be configured by two links, a link using channel 15 in the 6 GHz band and a link using channel 207 in the 6 GHz band. Note that in the present embodiment, "ch" is identification information used to identify a specific frequency channel. Further, in a multi-link, a plurality of links belonging to the same frequency band and a link belonging to a frequency band different from these links may be mixed. For example, a multi-link may be configured by a link 121 of channel 36 in the 5 GHz band, a link 122 of channel 149 in the 5 GHz band, and a link 123 of channel 15 in the 6 GHz band. By establishing a plurality of links with different frequency channels between the AP 101 and the STA 102, even when any one of the frequency channels is congested, it becomes possible to communicate using a link with another frequency channel. For this reason, it is possible to avoid a decrease in throughput and an increase in delay.

[0014] A communication device capable of multi-link communication is called a Multi-link device (MLD). A communication device that operates as an AP or STA compliant with the IEEE802.11be standard and has functions for operating as an MLD is called an AP MLD or an STA MLD, respectively. The STA MLD may be called a non-AP MLD. In the AP MLD or STA MLD, the communication interface (I / F) constituting each link may be called an Affiliated AP (A-AP) or an Affiliated STA (A-STA), respectively. The Affiliated STA may also be called an Affiliated non-AP STA. The A-APs are associated with the AP MLD and operate on different frequency channels from each other. Also, the A-STAs are associated with the STA MLD and operate on different frequency channels from each other. The state where the A-APs and A-STAs are associated with the AP MLD and STA MLD, respectively, may be said to belong to the MLD. Note that in the following embodiments, the case where multi-link communication using the IEEE802.11be standard is performed will be described, but it is not limited to this. For example, the following discussion can also be applied to multi-link communication compliant with other wireless communication standards and multi-link communication using a plurality of wired links.

[0015] Figure 2 shows an example of a sequence for establishing a multi-link between AP101 and STA102. The AP MLD, AP101, has Affiliated APs (A-APs) - A201 to A-AP-C203 as wireless I / Fs operating on frequency channels corresponding to respective links. Also, the STA MLD, STA102, has Affiliated STAs (A-STAs) - A204 to A-STA-C206 as wireless I / Fs operating on frequency channels corresponding to respective links. Information necessary for establishing multi-link communication between AP101 and STA102 can be mutually notified by a Basic Multi-Link element. For example, the AP MLD transmits a Beacon or Probe Response including a Basic Multi-Link element via each of A-AP-A201 to A-AP-C203 (F211 to F219). Note that the Probe Response can be transmitted in response to a Probe Request transmitted from STA102 (F214 to F219). On the other hand, the STA MLD notifies the AP of the Basic Multi-Link element using an Association Request transmitted via an A-STA described later. STA102 receives a Beacon or Probe Response via each of A-STA-A204 to A-STA-C206. STA102 can detect that AP101 is an AP MLD by checking whether the received Beacon or Probe Response includes a Basic Multi-Link element. When STA102 detects that AP101 is an AP MLD, it acquires information on each A-AP belonging to the AP MLD from the RNR element included in the received Beacon or Probe Response. RNR is an abbreviation for Reduced Neighbor Report. Note that the RNR element may include information on APs around the A-AP that transmitted this RNR element in addition to information on each A-AP belonging to the same AP MLD.For example, the RNR element may include frequency band, channel information, etc. used by each A-AP belonging to the same AP MLD and surrounding APs. Note that the fact that the APs reported by the RNR element belong to the same AP MLD can be indicated by the value of the MLD ID associated with this AP being 0. STA102 can establish a multi-link with AP101 using any of the A-STAs. For example, STA102 can execute procedures for establishing a multi-link with A-AP-A201 via A-STA-A204. As procedures for establishing a multi-link, the exchange of Authentication Frame, Association Request, and Association Response with AP101 can be executed (F220~F222). For example, STA102 can request the establishment of a multi-link with AP101 by sending an Association Request including a Basic Multi-Link element (F221). As an example, the STA MLD determines the frequency channels on which each A-STA operates based on the information of each A-AP obtained by the RNR element. Then, the STA MLD notifies the AP MLD of information such as the frequency channels on which each A-STA operates using the Basic Multi-Link element. The AP MLD obtains information such as the frequency channels on which each A-STA operates from the received Basic Multi-Link element. By the AP MLD returning an Association Response, a multi-link between AP101 and STA102 can be established (F222). The STA MLD switches to the frequency channels determined for the frequency channels on which each A-STA operates. Thereby, without individually executing the link establishment procedure for each link, a plurality of links between each A-AP and each A-STA can be established collectively. Note that after the establishment of the multi-link, AP101 and STA102 can execute the exchange of security information, etc. through the 4-way handshake procedure (F223). Note that if AP101 is not an AP MLD, STA102 can establish a connection using a single frequency channel.The method using the Basic Multi-Link element and the RNR element is an example of a method for exchanging multi-link related information between the AP101 and the STA, and other methods may be used.

[0016] Figure 3 shows an example of an RNR element. The RNR element may be configured to include an Element ID 301, a Length 302, and a Neighbor AP Information 303. The Element ID 301 indicates the type of this element. For example, in the case of an RNR element, 201 may be stored. The Length 302 indicates the length of this element. The Neighbor AP Information 303 may be arranged by the number of APs to be reported. Each Neighbor AP Information 303 may include a TBTT Information Header 304, an Operation Class 305, and a Channel Number 306. Also, each Neighbor AP Information 303 may include a TBTT Information Set 307. The TBTT Information Header 304 is header information indicating the length and the like of each TBTT Information included in the TBTT Information Set 307. The Operation Class 305 is used together with the Channel Number 306 and indicates the start frequency of the primary channel used by the AP (the AP to be reported) associated with the Neighbor AP Information 303. The TBTT Information Set 307 may include a Neighbor AP TBTT Offset 308, a BSSID 309, a Short SSID 310, BSS Parameters 311, and a 20MHz PSD 312. Also, the TBTT Information Set 307 may include MLD Parameters 313. The Neighbor AP TBTT Offset 308 indicates information regarding the timing of the Beacon transmitted by the AP to be reported. The BSSID 309 indicates the identifier of the network configured by the AP to be reported. The Short SSID 310 indicates a value obtained by applying the SSID (Service Set Identifier) to a predetermined calculation formula. The BSS Parameters 311 indicate the parameters of the network configured by the AP to be reported.The MLD Parameters 313 may be composed of an MLD ID 314, a Link ID 315, a BSS Parameters Change Count 316, an All Updates Included 317, and a Reserved 318. The MLD ID 314 indicates the identifier of the AP MLD to which the AP to be reported belongs. If the AP to be reported belongs to the same AP MLD as the AP that transmits the RNR element, the value of the MLD ID 314 may be set to 0. The Link ID 315 indicates the link identifier of the AP to be reported. The BSS Parameters Change Count 316 indicates the period until the network parameters are changed in the AP to be reported. The All Updates Included 317 is set to 1 when all elements updated in the latest parameter update are included. The Reserved 318 is a reserved field.

[0017] As one form of multi-link communication, there is MLSR (Multi-Link Single Radio). Generally, an MLD corresponding to multi-link communication has a plurality of wireless I / Fs, and each wireless I / F is associated with one link, and communication is performed using a plurality of links. On the other hand, in MLSR, the communication device communicates using one link at a time while maintaining the multi-link established with the other communication device. In the IEEE802.11be standard, this MLSR is extended, and EMLSR (Enhanced Multi-Link Single Radio) that communicates while switching to a more suitable link is planned to be defined. For example, in EMLSR, STA102 performs signal detection (Listen operation) on a plurality of links. Then, AP101 transmits an Initial Control Frame using any of the links on which STA102 is performing the Listen operation. After that, between AP101 and STA102, communication such as data is performed using the link on which the Initial Control Frame was transmitted. The Initial Control Frame can be, for example, a MU-RTS Trigger frame or a BSRP Trigger frame, but is not limited to this. MU-RTS is an abbreviation for multi-user request to send. Also, BSRP is an abbreviation for buffer status report poll. The Initial Control Frame can also be transmitted from STA102.

[0018] The information necessary to perform EMLSR between AP101 and STA102 can be notified by the Basic Multi-Link element included in the Beacon or Probe Response transmitted from the AP MLD. For example, if the value of the EMLSR Support field in the Common Info field of the Basic Multi-Link element notified from AP101 is 1, it can be indicated that the AP MLD supports EMLSR. FIG. 4 is an example of a flowchart diagram when performing EMLSR between AP101 and STA102. First, as described above, STA102 establishes a multi-link with AP101 (S401 to S403). For example, STA102 receives the Beacon or Probe Response of an arbitrary A-AP (e.g., A-AP-A201) and confirms that AP101 supports multi-link communication (S401). STA102 acquires the information of each A-AP belonging to AP101, which is the AP MLD, by the RNR element (S402). STA102 executes the procedure for establishing a multi-link with AP101 according to F220 to F222 shown in FIG. 2, for example. STA102 sets the frequency channel on which each A-STA operates to the frequency channel used by each A-AP and establishes a multi-link with AP101 (S403). Then, STA102 performs the procedure for executing EMLSR. First, STA102 checks the value of the EMLSR Support field in the Common Info field of the Basic Multi-Link element included in the received Beacon or Probe Response (S404). That is, STA102 checks whether AP101 supports EMLSR. If the EMLSR Support field is not 1, STA102 determines that AP101 does not support EMLSR (NO in S404) and does not use EMLSR (S408). On the other hand, if the EMLSR Support field is 1, STA102 determines that AP101 supports EMLSR (YES in S404) and requests the start of EMLSR (S405).For example, STA102 can send an EML Operating Mode Notification frame to the AP MLD. When AP101 receives the EML Operating Mode Notification frame, it sends a notification indicating the start of the EMLSR. For example, AP101 can send an EML Operating Mode Notification with the same value set in the EML Control field of the received EML Operating Mode Notification. Assuming that the start of the EMLSR is approved by AP101 when STA102 receives the EML Operating Mode Notification frame (S406), STA102 executes the EMLSR (S407).

[0019] Generally, when performing multi-link communication, compared with communication using one link, the power consumption in the communication device increases. In contrast, by using the EMLSR, it is possible to suppress the power consumption of the communication device by maintaining the establishment of multiple links and performing communication using any one of them. Also, in the EMLSR, since one link is selected from multiple links, for example, in an environment where communication is congested, the communication performance such as delay can be improved by appropriately selecting available links. On the other hand, there are cases where communication performance is improved by performing multi-link communication. For example, in an environment where communication is not congested, by performing high-speed communication using multi-link communication, the delay can be reduced and the power consumption can also be suppressed. Thus, by using the EMLSR, the communication performance and power-saving effect may be improved, but there are also cases where the communication performance and power-saving effect are not improved due to extra processing being performed.

[0020] In view of such circumstances, in this embodiment, STA102 acquires information indicating whether AP101 can execute communication using a predetermined communication method. Then, when AP101 can execute communication using a predetermined communication method and should execute communication using that predetermined communication method, STA102 starts communication using the predetermined communication method based on the control by AP101. For example, the predetermined communication method may be a communication method that performs communication by selectively using a part of the communication link while maintaining a plurality of communication links and not using the remaining part. As an example, the predetermined communication method may be EMLSR, but is not limited thereto, and any communication method that selectively uses a part of the communication link while maintaining a plurality of communication links and does not use the remaining part may be used. For example, in EMLSR, STA102 can selectively use any one of the plurality of links while maintaining them. Hereinafter, EMLSR will be described as an example. The STA102 of this embodiment can perform an execution determination in its own device as to whether to start communication by EMLSR. When it is determined in the execution determination that EMLSR should be executed, STA102 requests AP101 to start communication by EMLSR. Also, while executing EMLSR, STA102 makes a continuation determination as to whether to continue EMLSR, and when it is determined that it should not be continued, requests AP101 to end EMLSR. STA102 may end EMLSR based on the response of AP101. In this way, STA102 does not simply execute EMLSR based on the fact that AP101 supports EMLSR, but executes EMLSR based on the control of AP101 when EMLSR should be executed. On the other hand, the AP101 of this embodiment can perform an execution determination as to whether to cause STA102 to start communication by EMLSR. When it is determined in the execution determination that STA102 should execute EMLSR, AP101 instructs STA102 to start communication by EMLSR. STA102 executes EMLSR based on the execution determination by AP101.Also, while the EMLSR is being executed, AP101 makes a continuation determination as to whether the EMLSR should be continued. If it is determined that the EMLSR should not be continued, an instruction to end the EMLSR is given to STA102. In the following, although the operation example of STA102 is used for explanation, the same operation can also be applied to AP101.

[0021] STA102 can determine whether to execute EMLSR based on the communication quality of each of a plurality of links with AP101. In this case, STA102 can measure, for example, the communication quality of each of the plurality of links with AP101, and when there is a communication link whose value indicating the communication quality is lower than a predetermined threshold, it can determine whether to execute EMLSR based on the number thereof. As an example, STA102 can determine that EMLSR should be executed when there are a plurality of communication links whose values indicating the communication quality are lower than a predetermined threshold. The value indicating the communication quality may be RSSI (Received Signal Strength Indicator) or SNR (Signal to Noise Ratio), and other parameters may be used. In this case, STA102 can calculate RSSI or SNR using the received power of Beacons, Probe Responses, etc. received from AP101. In a link with low communication quality, packet errors and retransmissions are likely to occur, so there is a high possibility of transmission delay. If a transmission delay occurs in some of the links used for multi-link communication, the time for which packets received successfully on other links must be buffered may become longer, so the delay of the entire communication may increase. In such an environment, if EMLSR is selected, the use of links with low communication quality can be avoided, so the communication performance of multi-link communication can be improved. Note that STA102 may use the usage rate of the frequency channels used by each link as the value indicating the communication quality. For example, STA102 measures the ratio of the time during which the received power exceeds a predetermined threshold at each frequency. Then, when there are a plurality of frequency channels whose ratio exceeds a predetermined threshold, it can be determined that EMLSR is to be executed. In a situation where the usage rate of the frequency channel is high and the frequency channel is congested, there is a high possibility that the delay when the communication device obtains an opportunity to transmit increases. In such an environment, if EMLSR is selected, the use of links with increasing delay can be avoided, so the communication performance of multi-link communication can be improved.

[0022] STA102 may determine whether to execute EMLSR based on information acquired from or notified by other communication devices. For example, STA102 may measure the number of devices in the frequency channels used in each of the multiple links with AP101, and determine whether to execute EMLSR based on that number. As an example, STA102 may obtain the number of APs operating in each frequency channel from RNR elements or the like included in Beacons, Probe Responses, etc. received in each frequency channel used in each link. In this case, STA102 identifies the number of frequency channels in which the number of operating APs exceeds a predetermined threshold. Then, STA102 may determine to execute EMLSR if the number of such frequency channels exceeds the predetermined threshold. In a specific frequency channel, if the number of operating APs is large, the proportion of that frequency channel used by devices other than AP101 and STA102 may increase, and thus there is a high possibility of transmission delay. As described above, since an increase in the transmission delay of some of the links used in multi-link may increase the delay of the entire communication, the selection of EMLSR in such an environment can improve the communication performance of multi-link communication. Note that instead of measuring the number of devices in each frequency channel, STA102 may determine whether to execute EMLSR based on an indicator indicating the congestion of the frequency channels notified by AP101. For example, STA102 may use BSS Load elements, Extended BSS Load elements, etc. included in Beacons and Probe Responses as indicators. In this case, STA102 may use the traffic load, the number of connected devices, etc. in the network constituted by each AP as indicators.

[0023] STA102 may determine whether to execute EMLSR based on the state of its own device. For example, STA102 may determine to execute EMLSR when the remaining battery level of its own device is equal to or lower than a predetermined threshold. If all of the multiple wireless I / Fs corresponding to multiple links are operated, the power consumption in STA102 will be relatively high. When the remaining battery level is low, executing EMLSR can slow down the rate at which the remaining battery level decreases. Also, at this time, instead of fixedly using one link, STA102 may select the link to be used based on the communication quality of each link. This makes it possible to reduce power consumption while suppressing a decrease in communication quality. Further, STA102 may determine to execute EMLSR when its own device is performing a power-saving operation with less power consumption than during normal operation. For example, the power-saving operation may be the Power Save operation defined in the IEEE802.11 series standards. STA102 may determine to execute EMLSR when the number of links performing the power-saving operation in the links used for multi-link communication exceeds a predetermined threshold. Also, it may be determined to execute EMLSR when the terminal device on which STA102 is implemented is performing a power-saving operation. For example, the operation system of the terminal device may detect that the remaining battery level is decreasing and execute a power-saving operation. STA102 may determine to execute EMLSR based on the operation of such an operation system of the terminal device.

[0024] STA102 can determine whether to execute EMLSR based on the type of the communicating application. For example, when the communicating application requires low-latency communication (such as real-time communication, printer jobs, autonomous driving, control of drones and robots, etc.), STA102 can determine to execute EMLSR. By communicating while avoiding the use of congested links using EMLSR, it becomes possible to avoid the occurrence of large delays. On the other hand, when the communicating application requires high-capacity communication (such as high-resolution video distribution, etc.), STA102 can determine not to execute EMLSR. By communicating using more links including those with low communication quality, it is possible to complete data transfer faster. In these cases, STA102 can determine that EMLSR should be executed based on, for example, detecting the start of communication of a predetermined traffic type based on the traffic type (Traffic Identifier) of the data being communicated with AP101, etc.

[0025] STA102 can determine whether to execute EMLSR based on an instruction to the own device. For example, when it is set in the user settings to execute EMLSR, STA102 can determine to execute EMLSR. In this case, STA102 can determine whether to execute EMLSR, for example, when establishing a multi-link with AP102 or by periodically checking the settings of the own device by the user. Also, when STA102 receives an instruction from AP101 to execute EMLSR, STA102 can determine to execute EMLSR. For example, STA102 can determine to execute EMLSR by receiving an EML Operating Mode Notification frame. By executing EMLSR based on an instruction from AP101 to the own device, it becomes possible to determine the necessity of executing EMLSR based on measurements only around STA102 or information that cannot be obtained only from notifications from AP101.

[0026] (Device Configuration) Fig. 5 shows an example of the hardware configuration of AP101 and STA102 in this embodiment. AP101 includes a storage unit 501, a control unit 502, a functional unit 503, an input unit 504, an output unit 505, a communication unit 506, and an antenna 507. Note that there may be a plurality of antennas. The storage unit 501 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. In addition to memories such as ROM and RAM, storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs may be used as the storage unit 501. Further, the storage unit 501 may include a plurality of memories and the like. The storage unit 501 can record setting information input from the user to the own device, information regarding the state of the own device such as the remaining amount of the battery provided in the own device, and whether or not a power saving operation is being executed.

[0027] The control unit 502 is composed of one or more processors such as a CPU or an MPU, for example, and controls the entirety of AP101 or STA102 by executing the computer program stored in the storage unit 501. Note that the control unit 502 may control the entirety of AP101 or STA102 in cooperation with the computer program stored in the storage unit 501 and an OS (Operating System). Further, the control unit 502 generates data and signals (wireless frames) to be transmitted in communication with other communication devices. CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Micro Processing Unit. Further, the control unit 502 may include a plurality of processors such as a multi-core processor, and control the entirety of AP101 or STA102 by the plurality of processors. Further, the control unit 502 controls the functional unit 503 to execute predetermined processes such as wireless communication, imaging, printing, and projection. The functional unit 503 is hardware for AP101 or STA102 to execute a predetermined process.

[0028] The input unit 504 receives various operations from the user. The output unit 505 performs various outputs to the user via a monitor screen or a speaker. Here, the output by the output unit 505 may be a display on the monitor screen, an audio output by the speaker, a vibration output, or the like. Note that both the input unit 504 and the output unit 505 may be realized by one module such as a touch panel. Also, the input unit 504 and the output unit 505 may be integrated with the AP101 or the STA102, respectively, or may be separate entities.

[0029] The communication unit 506 controls wireless communication compliant with the IEEE802.11be standard. In addition to the IEEE802.11be standard, the communication unit 506 may control wireless communication compliant with other IEEE802.11 series standards or wired communication such as a wired LAN. The communication unit 506 controls the antenna 507 to transmit and receive signals for wireless communication generated by the control unit 502. The communication unit 506 may be composed of a plurality of communication circuits corresponding to each of the plurality of links. Note that when the AP101 supports communication standards such as the NFC standard and the Bluetooth standard in addition to the IEEE802.11be standard, it may control wireless communication compliant with these communication standards. Also, when the AP101 can execute wireless communication compliant with a plurality of communication standards, it may have a configuration with a communication unit and an antenna corresponding to each communication standard individually. The communication device communicates data such as image data, document data, and video data with the other communication device via the communication unit 506. Note that the antenna 507 may be configured separately from the communication unit 506 or may be configured as one module together with the communication unit 506.

[0030] The antenna 507 is an antenna capable of communication in the 2.4 GHz band, 5 GHz band, 6 GHz band, etc. In the present embodiment, there may be two or more antennas. When the communication unit 506 is composed of a plurality of communication units, there may be an antenna corresponding to each communication unit. Alternatively, there may be different antennas for each frequency band.

[0031] FIG. 6 shows a block diagram of the functional configuration of the communication devices (AP101 and STA102) in this embodiment. The communication device may include a multi-link establishment unit 601, a wireless I / F setting unit 602, a frame processing unit 603, a frame transmission / reception unit 604, a communication quality measurement unit 605, and a communication method control unit 606. The multi-link establishment unit 601 controls communication start processing for establishing one or more links used by the communication device for wireless communication with a counterpart communication device, control processing for functions related to multi-link, addition / deletion processing of links after communication start, and communication end processing for deleting all links. For example, the connection process may be composed of an Authentication process, an Association process, and a 4-Way-Hand-Shake (4WHS) process. The wireless I / F setting unit 602 performs communication settings for each link. For example, the wireless I / F setting unit 602 of STA102 selects and determines the A-AP to which each A-STA connects, sets the frequency channel used by each A-STA, and so on. Also, the wireless I / F setting unit 602 of AP101 sets information on the A-STA connected to each A-AP. Further, the wireless I / F setting unit 602 of AP101 notifies the frame processing unit 603 and the frame transmission / reception unit 604 of information regarding the A-AP and A-STA that establish a link. The frame processing unit 603 generates a frame to be transmitted according to the settings of the wireless I / F setting unit 602. For example, the frame processing unit 603 of AP101 generates a Beacon, a Probe Response, etc. including a Basic Multi-Link element and an RNR element. Also, the frame processing unit 603 of AP101 generates an Authentication, an Association Response, an EML Operating Mode Notification frame, etc. The frame processing unit 603 of STA102 generates a Probe Request, an Association Request, etc. including a Basic Multi-Link element and an RNR element. Also, the frame processing unit 603 of STA102 generates an EML Operating Mode Notification frame. Further, the frame processing unit 603 processes the frame received from the counterpart communication device and acquires information.For example, the frame processing unit 603 of STA102 obtains information indicating that AP101 can perform multi-link communication and EMLSR from the Basic Multi-Link element and RNR element included in the received Beacon or the like. Also, the frame processing unit 603 of STA603 obtains the number of devices in the frequency channel used for multi-link communication. The frame transceiver unit 604 transmits and receives wireless frames including Beacons, Probe Response frames, and data frames generated by the frame processing unit 603 according to an instruction from the wireless I / F setting unit 602. For example, the frame transceiver unit 604 of AP101 can notify STA102 to start EMLSR by transmitting an EML Operating Mode Notification frame. The communication quality measurement unit 605 measures and calculates the communication quality using Beacons, Probe Response frames, etc. received by the frame transceiver unit 604. Note that the communication quality information includes, but is not limited to, RSSI, SNR, etc. The communication method control unit 606 determines whether to execute or continue EMLSR based on the results of the communication quality measurement and calculation by the communication quality measurement unit 605, the information obtained by the frame processing unit 603, the settings and power information of the own device recorded in the storage unit 601, etc.

[0032] (Processing flow) Subsequently, the processing flow executed by AP101 and STA102 as described above, sequences in the wireless communication system, etc. will be described using several embodiments.

[0033] (Processing example 1) FIG. 7 shows an example of a process for determining whether to execute EMLSR based on the communication quality in each of the multi-links established between STA102 and AP101. In FIG. 7, for the same operations as in FIG. 4, the same reference numerals are assigned and detailed descriptions are omitted. This process can be started, for example, when STA102 connects to AP101. Also, STA102 can start this process when detecting another AP101 that can be the next connection destination when the communication quality with the connected AP101 deteriorates.

[0034] First, STA102 receives a Beacon or Probe Response via one of the A-STAs (S401). At this time, STA102 confirms that AP101 is an AP MLD by checking that the Basic Multi-Link element is included in the received Beacon or Probe Response. Then, STA102 acquires information such as the frequency band and frequency channel of each A-AP belonging to AP101, which is an AP MLD, based on the Basic Multi-Link element and the RNR element (S402). For example, when STA102 receives a Beacon transmitted by A-AP-A201 via A-STA-A204, it can acquire information on A-AP-B202 and A-AP-C203 from the Basic Multi-Link element or the like. STA102 measures the communication quality in each frequency channel (S701). For example, STA102 can measure the communication quality with A-AP-A201 by measuring the RSSI, SNR, etc. of the Beacon received via A-STA-A204. Also, STA102 sets A-STA-B205 and A-STA-C203 to the frequency channels used by A-AP-B202 and A-AP-C203 and receives the Beacons and Probe Responses received in each frequency channel. STA102 can measure the communication quality with A-AP-B202 and A-AP-C203 using the RSSI, etc. of the received Beacons or the like. Then, STA102 establishes a multi-link with AP101 (S403).

[0035] STA102 determines whether AP101 supports EMLSR (S404). If it does not support it (NO in S404), it decides not to execute EMLSR (S408). On the other hand, if AP101 supports EMLSR (YES in S404), STA102 determines whether the communication quality between STA102 and AP101 meets a predetermined condition (S702). For example, STA102 identifies the communication quality of each link based on the RSSI of Beacons received from each A-AP, etc., and determines whether the predetermined condition is met. As an example, first, STA102 determines whether the RSSI measured is greater than the minimum reception power required to use the lowest modulation and coding scheme (MCS) with the lowest transmission rate in each link. For example, STA102 may set as a predetermined condition that the number of links where the RSSI measured is lower than the minimum reception power is equal to or greater than a predetermined threshold. Note that MCS indexes a combination of wireless modulation methods, coding rates, etc., and the MCS that a communication device can use varies depending on the communication environment. For example, the lower the communication quality, the lower the MCS with a lower transmission rate may be used. In this case, STA102 can compare the measured RSSI of each link with the minimum reception power and identify the number of links where the RSSI is below the minimum reception power. For example, STA102 may determine that the communication quality will be improved by using EMLSR if the RSSI is below the minimum reception power in a plurality (for example, two or more) of links. In this case, STA102 performs the procedure for executing EMLSR for AP101 (S405 - S407). Note that STA102 may determine to use EMLSR if the RSSI is below the minimum reception power in three or more links. Also, STA102 may determine whether to use EMLSR based on the ratio of the number of links where the RSSI is below the minimum reception power to the number of links established between STA102 and AP101. On the other hand, if STA102 does not meet the predetermined condition (NO in S702), it determines not to execute EMLSR (S408). For example, STA102 may determine that the predetermined condition is not met if the RSSI is above the minimum reception power in any link.Note that the threshold value used for the predetermined conditions is not limited to the minimum received power, and may be the received power required to use a predetermined MCS. Also, when the RSSI in one link falls below the minimum received power, STA102 may determine that the predetermined conditions are satisfied. In this way, when the communication quality of the link between AP101 and STA102 satisfies the predetermined conditions, by executing EMLSR, it becomes possible to select one from among the links with good quality and perform communication. Thereby, it is possible to improve the communication performance when using EMLSR.

[0036] When STA102 receives a response from AP101 to the request for starting EMLSR, it starts communication in EMLSR. Here, during the execution of EMLSR, STA102 can select the link with the best communication quality among the multiple links it maintains and perform communication. For example, STA102 measures the communication quality of the frequency channels used in each link while maintaining each link. STA102 may periodically measure the communication quality using a Beacon or the like received from AP101, or may measure the communication quality using a frame exchanged with AP101 prior to transmission. Also, each time STA102 measures the communication quality, it may update the link used in EMLSR. Also, STA102 can select one from among the links whose communication quality exceeds a predetermined threshold value among the multiple links using a random number or the like and perform communication. Furthermore, STA102 can select a predetermined number of links in order from the ones with high communication quality among the multiple links, and select one from among them and perform communication. In this way, when STA102 is executing EMLSR, by selecting a link with good communication quality from among the multiple links it maintains and performing communication, it is possible to improve the communication performance when using EMLSR.

[0037] Note that STA102 can measure the communication quality of each link during the execution of EMLSR and terminate EMLSR when a predetermined condition is satisfied. In this case, after terminating EMLSR, STA102 can execute multi-link communication that uses multiple links in parallel. As an example, STA102 can determine to terminate EMLSR when a predetermined condition used when executing EMLSR is not satisfied. For example, STA102 measures the RSSI and SNR of the Beacon and Probe Response transmitted by each A-AP received at each link. Then, it is determined whether the RSSI or the like of each link exceeds the minimum reception power. For example, when STA102 sets as a predetermined condition that the RSSI is below the minimum reception power in two or more links when executing EMLSR, it can be determined to terminate EMLSR when there are not two or more links where the RSSI is below the minimum reception power. Also, STA102 may determine whether to continue EMLSR using a condition different from the predetermined condition used when executing EMLSR. For example, when STA102 sets as a predetermined condition that the RSSI is below the minimum reception power in two or more links when executing EMLSR, it can be determined to terminate EMLSR when the RSSI exceeds the minimum reception power in all links. In this way, when the communication quality of the link between AP101 and STA102 satisfies a predetermined condition during the execution of EMLSR, by terminating EMLSR, it becomes possible to communicate using multiple high-quality links in parallel. Thereby, the communication performance between AP101 and STA102 can be improved.

[0038] (Processing Example 2) FIG. 8 shows an example of a process in which STA102 determines whether to execute EMLSR based on information acquired from or notified by other communication devices. In FIG. 8, for operations similar to those in FIG. 4 or FIG. 7, the same reference numerals are assigned and detailed descriptions are omitted. For example, STA102 acquires information on each A-AP belonging to AP101 which is an AP MLD from a Beacon or Probe Response transmitted by AP101, and establishes a multi-link with AP101 (S401, S402, and S403). At this time, STA102 uses an RNR element or a Basic Multi-Link element included in a Beacon or the like transmitted from AP101 to acquire information on A-APs belonging to AP101 which is an AP MLD and other surrounding APs. For example, STA102 can specify the frequency channels on which each A-AP included in AP101 operates by using an RNR element or a Basic Multi-Link element, and acquire information on other APs using those frequency channels. Then, STA102 calculates the number of devices operating on the frequency channels on which each A-AP operates (S801). For example, in a Basic Multi-Link element, the same MLD ID is assigned to each A-AP constituting one AP MLD. Therefore, for example, STA102 can calculate the number of APs on the frequency channels on which each A-AP operates by counting the number of different MLD IDs included in the Basic Multi-Link element for each frequency channel. Also, STA102 may calculate the number of APs on each frequency channel by using A-STAs included in its own device. For example, STA102 specifies the frequency channels on which each A-AP included in AP101 operates by using an RNR element or a Basic Multi-Link element. Then, STA102 receives Beacons or Probe Responses transmitted by other APs on each frequency channel. For example, STA102 can receive Beacons or Probe Responses on each frequency channel by setting each A-STA of its own device to the frequency channels on which each A-AP operates.STA102 can calculate the number of APs operating on each frequency channel using the AP identifiers and RNR elements included in the received Beacon and Probe Response. Note that the devices calculated by STA102 as devices operating on each frequency channel are not limited to APs, and may include the number of STAs connected to each AP and communication devices of other wireless systems. For example, STA102 may obtain and use the number of STAs connected to each AP using the BSS Load, Extended BSS Load, etc. included in the Beacon and Probe Response. Also, the information that can be obtained from other communication devices that STA102 can use is not limited to the number of operating devices. For example, STA102 may obtain and use the utilization rate of the frequency channel, etc. STA102 can obtain the utilization rate of the frequency channel using the BSS Load, Extended BSS Load, etc. included in the Beacon and Probe Response.

[0039] When STA102 establishes a multi-link with AP101, it determines whether AP101 supports EMLSR (S404), and determines whether a predetermined condition is satisfied based on the information obtained in S801 (S802). For example, STA102 determines whether the number of devices in each frequency channel used for the multi-link satisfies a predetermined condition (S802). For example, STA102 uses the number of APs in each frequency channel calculated in S801 to identify the number of frequency channels where the number of APs exceeds a predetermined threshold. Note that STA102 may identify the number of frequency channels where the number of devices operating on that frequency channel exceeds a predetermined threshold using the number of STAs connected to those APs instead of, or in addition to, the number of APs. Also, STA102 may identify the number of frequency channels where the utilization rate of the frequency channels in each frequency channel exceeds a predetermined threshold instead of the number of devices. And when the number of those frequency channels exceeds a predetermined threshold, STA102 determines that the predetermined condition is satisfied and determines to execute EMLSR. For example, STA102 may determine that the communication performance is improved by using EMLSR when the number of APs exceeds a predetermined threshold in a plurality (e.g., two or more) of frequency channels. Note that STA102 may also determine to use EMLSR when the number of APs exceeds a predetermined threshold in one or three or more frequency channels. When STA102 determines that the predetermined condition is satisfied (YES in S802), it executes the procedures of S405 to S407 and starts EMLSR. On the other hand, when STA102 determines that the predetermined condition is not satisfied (NO in S802), it does not execute EMLSR (S408). In this way, by determining whether to execute EMLSR based on the congestion of the frequency channels used in the multi-link between AP101 and STA102, it becomes possible to select one of the links with low delay and communicate. Thereby, the communication performance between AP101 and STA102 can be improved.

[0040] When STA102 receives a response to the request for the start of EMLSR from AP101, it starts communication in EMLSR. Here, during the execution of EMLSR, STA102 can select one link from a plurality of links and execute communication based on information acquired from other communication devices or information notified thereto. For example, while maintaining each link, STA102 measures congestion in the frequency channels used in each link based on information acquired from other communication devices or information notified thereto. For example, STA102 may acquire the number of APs, STAs, etc. operating on each frequency channel using a Beacon or the like received from AP101, or may acquire the usage rate of the frequency channel. Then, STA102 may select one link from a plurality of links based on the acquired information. For example, STA102 may select the link with the smallest number of devices operating on the frequency channel being used. STA102 may update the link used in EMLSR each time it acquires information from other communication devices. Also, STA102 can select one from among the links where the number of operating devices and the usage rate of the frequency channel are lower than a predetermined threshold using a random number or the like and execute communication. Further, STA102 can select a predetermined number in order from the links where the number of operating devices and the usage rate of the frequency channel are small, and select one from among them and execute communication. In this way, by having STA102 select a less congested link based on information acquired from other communication devices or information notified thereto and execute EMLSR, it is possible to improve the communication performance when using EMLSR.

[0041] Note that STA102 can terminate the EMLSR when it meets a predetermined condition based on information obtained from or notified by other communication devices during the execution of the EMLSR. For example, STA102 can calculate the number of devices and the usage rate in the frequency channels used in each link, and can terminate the EMLSR when a predetermined condition is met. In this case, after terminating the EMLSR, STA102 can execute multi-link communication that uses multiple links in parallel. For example, STA102 identifies the number of devices using the Beacon or Probe Response transmitted by each A-AP received in each link. STA102 may also identify the number of devices at each frequency using the A-STA that the device itself has. Then, it is determined whether the number of devices at each frequency, etc., exceeds a predetermined threshold. As an example, when the predetermined condition used when executing the EMLSR is not satisfied, STA102 may determine to terminate the EMLSR. For example, when the number of APs in two or more links exceeds a predetermined threshold when executing the EMLSR is set as a predetermined condition, STA102 may determine to terminate the EMLSR when there are not two or more links where the number of APs exceeds the predetermined threshold. Also, STA102 may determine whether to continue the EMLSR using a condition different from the predetermined condition used when executing the EMLSR. For example, when the number of APs in two or more links exceeds a predetermined threshold when executing the EMLSR is set as a predetermined condition, STA102 may determine to terminate the EMLSR when the number of APs in all links is below the predetermined threshold. In this way, when another STA102 meets a predetermined condition based on information obtained from or notified by other communication devices and terminates the EMLSR, it becomes possible to communicate using multiple less congested links in parallel. Thereby, the communication performance between AP101 and STA102 can be improved.

[0042] (Processing Example 3) FIG. 9 shows an example of a process in which STA102 determines whether to execute EMLSR based on the state of its own device. In FIG. 9, the same operations as those in FIGS. 4, 7, and 8 are given the same reference numerals, and detailed descriptions thereof are omitted. For example, STA102 acquires information on each A-AP belonging to AP101, which is an AP MLD, from a Beacon or Probe Response transmitted by AP101, and establishes a multi-link with AP101 (S401, S402, and S403). When STA102 establishes a multi-link with AP101, it determines whether AP101 supports EMLSR (S404), and checks the state of its own device (S901). For example, STA102 determines whether the remaining amount of the battery possessed by its own device is below a threshold value. When the remaining amount of the battery is below the threshold value, STA102 determines that a predetermined condition is satisfied (YES in S901), executes the procedures of S405 to S407, and starts EMLSR. On the other hand, when STA102 determines that the predetermined condition is not satisfied (NO in S901), it does not execute EMLSR (S408). In S901, instead of checking the remaining amount of the battery, STA102 may determine whether its own device is executing a power-saving operation, whether a setting to execute EMLSR is set according to the user's setting, the type and communication volume of the application being communicated, and the like. In this way, by determining whether to execute EMLSR based on the state of STA102, it becomes possible to communicate while switching between multi-link communication that uses a plurality of links in parallel and EMLSR that uses one link. Thereby, while maintaining the communication performance when using EMLSR, power saving of the device can be achieved.

[0043] During the execution of EMLSR, STA102 can monitor the status of its own device and terminate EMLSR when a predetermined condition is met. In this case, after terminating EMLSR, STA102 can execute multi-link communication that uses multiple links in parallel. For example, STA102 can determine that a predetermined condition is met and terminate EMLSR when the remaining battery level of its own device exceeds a predetermined threshold, when its own device shifts from power-saving operation to normal operation, when the user cancels the EMLSR setting, etc. Also, STA102 can determine that a predetermined condition is met and terminate EMLSR when the type or traffic volume of traffic by an application communicating with AP101 changes. Thus, if STA102 terminates EMLSR when a predetermined condition associated with the status of its own device is satisfied during the execution of EMLSR, it becomes possible to switch between EMLSR and multi-link communication that uses multiple links in parallel according to the status of the own device. Thereby, it is possible to improve the communication performance and power performance when STA102 performs multi-link communication.

[0044] During the execution of EMLSR, STA102 can select the link with the best communication quality among the multiple links being maintained and execute communication by the method shown in Processing Example 1. Also, during the execution of EMLSR, STA102 can select one link from among the multiple links based on information acquired from or notified by other communication devices and execute communication by the method shown in Processing Example 2.

[0045] (Processing Example 4) Figures 10 and 11 show an example of the processing when STA102 executes EMLSR based on an instruction from AP101 to the own device. Figure 10 shows the operation of AP101 in this processing. First, AP101 transmits a Beacon or a Probe Response via each of the A-APs of the own device (S1001). By including a Basic Multi-Link element in the Beacon or the Probe Response, AP101 can notify that the own device supports multi-link communication. Also, AP101 can notify information on each A-AP included in the own device and surrounding APs using the Basic Multi-Link element and the RNR element. Then, AP101 can receive a multi-link establishment request from STA102 (S1002). For example, the multi-link establishment request from STA102 can be made by an Association Request including a Basic Multi-Link element. In response to the multi-link establishment request from STA102, AP101 can establish a multi-link with STA102 (S1003). For example, AP101 can establish a multi-link by transmitting an Association Response including a Basic Multi-Link element. Note that AP101 can perform an association between each A-AP owned by AP101 and each A-STA owned by STA102 by exchanging the Association Request and the Association Response. That is, it can determine a combination of an A-AP and an A-STA that constitutes each link used in multi-link communication. Then, AP101 determines whether STA102 supports EMLSR (S1004). For example, AP1004 can determine whether STA102 supports EMLSR based on the value of EMLSR Support in the Basic Multi-Link element included in the Association Request received from STA102. When STA102 supports EMLSR (YES in S1004), AP101 determines whether to cause STA102 to execute EMLSR (S1005).For example, the AP101 can determine whether to cause the STA102 to execute the EMLSR by using a predetermined condition for determining whether the STA102 executes the EMLSR in Processing Examples 1 to 3. That is, the AP101 can determine whether to cause the STA102 to execute the EMLSR based on information such as the communication quality between the AP101 and the STA102, the number of devices operating on each frequency channel used in multi-link, and the usage rate. As an example, the AP101 can determine that the EMLSR should be executed when there are two or more communication links in which the value indicating the communication quality (such as RSSI or SNR) is lower than a predetermined threshold among the plurality of communication links established with the STA102. Further, the AP101 may estimate the number of devices operating in the frequency channel corresponding to each of the plurality of communication links established with the STA102 for each frequency channel. Then, the AP101 can determine that the EMLSR should be executed when there are two or more frequency channels in which the estimated number of devices exceeds a predetermined threshold. Note that the AP101 may obtain the battery state, the power saving operation state, the user settings, etc. in the STA102 and make a determination based on this information. Such information can be obtained by the AP101 requesting a report from the STA102 and receiving the report notified from the STA102. Further, the AP101 may make a determination based on the type of application communicating with the STA102. When the AP101 determines to cause the STA102 to execute the EMLSR (YES in S1005), it gives an instruction to start the EMLSR (S1006). For example, the AP101 can give an instruction to the STA102 by using the EML Operating Mode Notification. Then, the AP101 executes communication by the EMLSR with the STA102 (S1007). The AP101 may execute the EMLSR by receiving an EML Operating Mode Notification having the same value as the EML Control field of the transmitted EML Operating Mode Notification.Note that when STA102 does not support EMLSR (NO in S1004) or when it is determined not to execute EMLSR on STA102 (NO in S1005), AP101 does not cause STA102 to execute EMLSR (S1008).

[0046] Note that during the execution of EMLSR, AP101 measures the communication quality of each link, the number of devices operating on each frequency channel used in multi-link, the usage rate, etc. and can terminate EMLSR when a predetermined condition is satisfied. Also, AP101 can terminate EMLSR based on the state of STA102 acquired from STA102 (remaining battery level, power-saving operation status, user settings, type of application to communicate, etc.). In this case, AP101 can send a notification instructing STA102 to terminate EMLSR. For example, AP101 can use EML Operating Mode Notification to send a notification instructing STA102 to terminate EMLSR. After terminating EMLSR, AP101 can execute multi-link communication using multiple links in parallel. As an example, AP101 can determine to terminate EMLSR when a predetermined condition used when executing EMLSR is not satisfied. Also, AP101 may determine whether to continue EMLSR using a condition different from the predetermined condition used when executing EMLSR. AP101 can determine whether to continue EMLSR on STA102 using the predetermined condition for determining whether STA102 continues EMLSR described in Processing Examples 1 to 3 above. In this way, by determining whether to continue EMLSR on STA102 by AP101 during the execution of EMLSR and terminating EMLSR when a predetermined condition is satisfied, the communication performance between AP101 and STA102 can be improved.

[0047] Note that, similar to the operation of STA101 shown in Processing Example 1, during the execution of EMLSR, AP101 can select the link with the best communication quality among the multiple links it maintains and perform communication. Also, similar to the operation of STA101 shown in Processing Example 2, during the execution of EMLSR, AP101 can select one link from among the multiple links based on the number of devices operating on each frequency channel used for multi-link, the usage rate, etc., and perform communication.

[0048] Figure 11 shows the operation of AP101 in this process. In Figure 11, for operations similar to those in Figures 4 and 7 to 9, the same reference numbers are assigned and detailed descriptions are omitted. For example, STA102 acquires information on each A-AP belonging to AP101 from the Beacon or Probe Response transmitted by AP101 and establishes a multi-link with AP101 (S401, S402, and S403). After establishing a multi-link with AP101, STA102 determines whether AP101 supports EMLSR (S404). Then, when STA102 receives an instruction to execute EMLSR from AP101 (YES in S1101), it executes EMLSR (S407). On the other hand, when STA102 does not receive an instruction from AP101 (NO in S1101), it does not execute EMLSR (S408). Note that when STA102 does not receive an instruction from AP101, it can determine whether to execute EMLSR based on the processes shown in Figures 7 to 9 and Figure 12 described later, etc., and request AP101 to execute EMLSR based on that determination. Also, during the execution of EMLSR, when STA102 receives a notification instructing it to end EMLSR from AP101, it can end EMLSR.

[0049] (Processing Example 5) STA102 may execute the above processes in combination. FIG. 12 shows an example of a process in which STA102 determines whether to execute EMLSR based on the communication quality between AP101 and STA102 and information acquired from or notified by other communication devices (for example, the number of devices operating on the same frequency channel). In FIG. 12, for operations similar to those in FIGS. 4, 7 to 9, and 11, the same reference numerals are assigned and detailed descriptions are omitted. For example, when establishing a multi-link with AP101, STA102 measures the communication quality of each link (S701) and acquires the number of devices operating on the frequency channel used by each link (S801). As the method for measuring the communication quality and the method for acquiring the number of devices, the methods described above in the descriptions of FIGS. 7 and 8 can be respectively applied. Then, when STA102 confirms that AP101 supports EMLSR (YES in S404), it determines whether the measured communication quality satisfies a predetermined condition (S702) and whether the acquired number of devices satisfies a predetermined condition (S802). As the method for determining the condition regarding the communication quality and the method for determining the condition regarding the number of devices, the methods described above in the descriptions of FIGS. 7 and 8 can be respectively applied. Then, when the predetermined condition regarding the communication quality is satisfied and the predetermined condition regarding the number of devices is satisfied (YES in S702 and YES in S802), STA102 performs procedures for executing EMLSR (S405 to S407). On the other hand, when at least one of the predetermined condition regarding the communication quality or the predetermined condition regarding the number of devices is not satisfied (NO in S702 or NO in S802), STA102 does not execute EMLSR (S408). Note that each condition determination may be performed in order or in parallel. Also, the order of each condition determination may be changed. In this way, by determining whether to use EMLSR based on a plurality of conditions, it becomes possible to determine with higher accuracy which of the multi-link communication using EMLSR and a plurality of links in parallel should be used. For example, even when there are a plurality of links that can obtain a predetermined communication quality, if a link with a large delay is included among them, by selecting EMLSR, it becomes possible to avoid a decrease in communication performance due to an increase in delay.

[0050] As described above, according to this embodiment, the communication device acquires information indicating whether the other communication device can perform communication using a predetermined communication method. Then, when the other communication device can perform communication using the predetermined communication method and should perform communication using the predetermined communication method, the communication device starts communication using the predetermined communication method based on the control by the other communication device. That is, the communication device does not simply perform communication using the predetermined communication method based on the fact that the other communication device supports the predetermined communication method, but when the predetermined communication method should be executed, the communication device executes the predetermined communication method based on the control of the other communication device. In this way, the communication device can perform communication while appropriately switching between the predetermined communication method and normal multi-link communication according to the environment. As a result, the communication performance and power performance of multi-link communication can be improved. In this embodiment, as the predetermined communication method, EMLSR that performs communication by selectively using one of the established multiple links while maintaining the multiple links is described as an example, but the present technology is also applicable to other communication methods. For example, it is also applicable to a communication method that performs communication by selectively using two or more of the maintained multiple communication links without using the remaining links. In this case, the communication device can select multiple links with good communication quality or the like from the multiple maintained links and perform communication.

[0051] 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 device via a network or a storage medium, and having one or more processors in a computer of the system or device read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

[0052] (Summary of the embodiment) Summarizing at least a part of the above-described embodiment, it is as follows. (Item 1) A communication device, establishing means for establishing a plurality of communication links with another communication device, Acquisition means for acquiring information indicating whether the other communication device can execute communication by a predetermined communication method in which communication is performed selectively using a part of the plurality of communication links and not using the remaining part while maintaining the plurality of communication links; Communication means for starting communication by the predetermined communication method based on control by the other communication device when the other communication device can execute communication by the predetermined communication method and communication by the predetermined communication method should be performed. A communication device characterized by the above. (Item 2) Further comprising determination means for performing an execution determination as to whether or not to start communication by the predetermined communication method, When it is determined by the execution determination that communication by the predetermined communication method should be performed, the communication means requests the other communication device to start communication by the predetermined communication method. The communication device according to item 1, characterized by the above. (Item 3) When there is one or more communication links in the plurality of communication links in which a value indicating communication quality is lower than a predetermined threshold, the determination means determines that communication by the predetermined communication method should be performed. The communication device according to item 2, characterized by the above. (Item 4) The value indicating the communication quality is RSSI (Received Signal Strength Indicator) or SNR (Signal to Noise Ratio). The communication device according to item 3, characterized by the above. (Item 5) The determination means estimates the number of devices operating in the frequency channel corresponding to each of the plurality of communication links for each frequency channel, and when there is one or more frequency channels in which the estimated number of devices exceeds a predetermined threshold, determines that communication by the predetermined communication method should be performed. The communication device according to item 2, characterized by the above. (Item 6) When the determination means determines that the communication device is executing a power-saving operation, it determines that communication should be executed using the predetermined communication method. The communication device according to item 2, characterized in that. (Item 7) When the remaining amount of the battery of the communication device is equal to or less than a predetermined threshold value, the determination means determines that communication should be executed using the predetermined communication method. The communication device according to item 2, characterized in that. (Item 8) When the communication means receives an instruction indicating that communication is to be executed using the predetermined communication method from the other communication device, the communication means starts communication using the predetermined communication method. The communication device according to item 1, characterized in that. (Item 9) While the communication means is executing communication using the predetermined communication method, the determination means further makes a continuation determination as to whether communication using the predetermined communication method should be continued, When it is determined by the continuation determination that communication using the predetermined communication method should not be continued, the communication means requests the other communication device to end communication using the predetermined communication method. The communication device according to item 2, characterized in that. (Item 10) When the communication means receives an instruction indicating that communication using the predetermined communication method is to be ended from the other communication device, the communication means ends communication using the predetermined communication method. The communication device according to item 8, characterized in that. (Item 11) The communication device has a plurality of communication circuits corresponding to each of the plurality of communication links. The communication device according to any one of items 1 to 10, characterized in that. (Item 12) A communication device, establishing means for establishing a plurality of communication links with another communication device, Notification means for notifying information indicating whether the communication device can perform communication by a predetermined communication method in which communication is performed using a part of the plurality of communication links selectively while maintaining the plurality of communication links and not using the remaining part; Determination means for making an execution determination as to whether or not to cause the other communication device to perform communication by the predetermined communication method when the other communication device can perform communication by the predetermined communication method; Control means for controlling the other communication device to perform communication by the predetermined communication method when it is determined that the other communication device should perform communication by the predetermined communication method based on the execution determination. The communication device is characterized by having the above. A communication device characterized by the above. (Item 13) The determination means makes the execution determination based on a request from the other communication device. When it is determined in the execution determination that the other communication device should perform communication by the predetermined communication method, the control means gives an instruction to the other communication device to perform communication by the predetermined communication method in a response to the request. The communication device according to item 12, characterized by the above. (Item 14) The control means transmits an instruction to the other communication device to perform communication by the predetermined communication method. The communication device according to item 12, characterized by the above. (Item 15) When there is one or more communication links in the plurality of communication links in which a value indicating communication quality is lower than a predetermined threshold, the determination means determines that communication by the predetermined communication method should be performed. The communication device according to item 12, characterized by the above. (Item 16) The communication device according to item 15, wherein the value indicating the communication quality is RSSI (Received Signal Strength Indicator) or SNR (Signal to Noise Ratio). (Item 17) The determination means estimates, for each frequency channel, the number of devices operating in the frequency channel corresponding to each of the plurality of communication links, and determines that communication by the predetermined communication method should be executed when there is one or more frequency channels in which the estimated number of devices exceeds a predetermined threshold value. The communication device according to item 12, characterized in that. (Item 18) Based on the determination that the other communication device should not continue communication by the predetermined communication method while the other communication device is executing communication by the predetermined communication method, the determination means controls the other communication device to end communication by the predetermined communication method. The communication device according to item 12, characterized in that. (Item 19) The communication device includes a plurality of communication circuits corresponding to each of the plurality of communication links. The communication device according to any one of items 12 to 18, characterized in that. (Item 20) A communication method executed by a communication device, comprising: An establishment step of establishing a plurality of communication links with another communication device; An acquisition step of acquiring information indicating whether the other communication device can execute communication by a predetermined communication method in which communication is performed using some of the plurality of communication links selectively while maintaining the plurality of communication links and not using the other part; A communication step of starting communication by the predetermined communication method based on control by the other communication device when the other communication device can execute communication by the predetermined communication method and communication by the predetermined communication method should be executed. A communication method characterized by that. (Item 21) A communication method executed by a communication device, comprising: An establishment step of establishing a plurality of communication links with another communication device; A notification step of notifying information indicating whether the communication device can execute communication by a predetermined communication method in which communication is performed using a part of the plurality of communication links selectively and not using the remaining part while maintaining the plurality of communication links; A determination step of determining whether or not to cause the other communication device to execute communication by the predetermined communication method when the other communication device can execute communication by the predetermined communication method; A control step of controlling the other communication device to execute communication by the predetermined communication method when it is determined that communication by the predetermined communication method should be executed by the execution determination. A communication method characterized by the above. (Item 22) A program for causing a computer to function as each means included in the communication device according to any one of Items 1 to 19.

[0053] 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

[0054] 101: AP, 102: STA, 601: Multi-link Establishment Unit, 602: Wireless I / F Setting Unit, Frame Processing Unit 603, Frame Transmission / Reception Unit 604, Communication Quality Measurement Unit 605, Communication Method Control Unit: 606

Claims

1. A communication device, comprising: establishing means for establishing a plurality of communication links with other communication devices; acquiring means for acquiring information indicating whether the other communication device can execute communication by a predetermined communication method in which communication is performed selectively using a part of the plurality of communication links and not using the remaining part while maintaining the plurality of communication links; communication means for starting communication by the predetermined communication method based on control by the other communication device when the other communication device can execute communication by the predetermined communication method and communication by the predetermined communication method should be performed. The communication device is characterized in that.

2. The communication device further comprises determination means for determining whether to start communication by the predetermined communication method, wherein the communication means requests the other communication device to start communication by the predetermined communication method when it is determined by the execution determination that communication by the predetermined communication method should be performed. The communication device according to claim 1, characterized in that.

3. The determination means determines that communication by the predetermined communication method should be performed when there is one or more communication links in the plurality of communication links in which a value indicating communication quality is lower than a predetermined threshold. The communication device according to claim 2, characterized in that.

4. The value indicating the communication quality is RSSI (Received Signal Strength Indicator) or SNR (Signal to Noise Ratio). The communication device according to claim 3, characterized in that.

5. The determination means estimates the number of devices operating in the frequency channel corresponding to each of the plurality of communication links for each frequency channel, and determines that communication by the predetermined communication method should be performed when there is one or more frequency channels in which the estimated number of devices exceeds a predetermined threshold. The communication device according to claim 2, characterized in that.

6. The determination means determines that communication by the predetermined communication method should be performed when the communication device is executing a power saving operation. The communication device according to claim 2, characterized in that.

7. The determination means determines that communication by the predetermined communication method should be performed when the remaining amount of the battery of the communication device is equal to or less than a predetermined threshold. The communication device according to claim 2, characterized in that.

8. When the communication means receives an instruction indicating to execute communication by the predetermined communication method from the other communication device, it starts communication by the predetermined communication method. The communication device according to claim 1, characterized in that.

9. While the communication means is executing communication by the predetermined communication method, the determination means further makes a continuation determination as to whether to continue communication by the predetermined communication method. When it is determined by the continuation determination that communication by the predetermined communication method should not be continued, the communication means requests the other communication device to end communication by the predetermined communication method. The communication device according to claim 2, characterized in that.

10. When the communication means receives an instruction indicating to end communication by the predetermined communication method from the other communication device, it ends communication by the predetermined communication method. The communication device according to claim 8, characterized in that.

11. The communication device has a plurality of communication circuits corresponding to each of the plurality of communication links. The communication device according to claim 1, characterized in that.

12. A communication device, An establishment means for establishing a plurality of communication links with another communication device, Notification means for notifying information indicating whether the communication device can execute communication by a predetermined communication method in which communication is performed using only a part of the plurality of communication links selectively while maintaining the plurality of communication links and not using the remaining part, Determination means for making an execution determination as to whether the other communication device should execute communication by the predetermined communication method when the other communication device can execute communication by the predetermined communication method, Control means for controlling the other communication device to execute communication by the predetermined communication method when it is determined by the execution determination that the other communication device should execute communication by the predetermined communication method. A communication device, characterized in that.

13. The determination means makes the execution determination based on a request from the other communication device. When it is determined in the execution determination that the other communication device should execute communication by the predetermined communication method, the control means issues an instruction to the other communication device to execute communication by the predetermined communication method in the response to the request. The communication device according to claim 12, characterized in that.

14. The control means transmits an instruction to the other communication device to execute communication by the predetermined communication method. The communication device according to claim 12, characterized in that...

15. When there is one or more communication links among the plurality of communication links in which the value indicating the communication quality is lower than a predetermined threshold, the determination means determines that communication should be executed by the predetermined communication method. The communication device according to claim 12, characterized in that...

16. The communication device according to claim 15, wherein the value indicating the communication quality is RSSI (Received Signal Strength Indicator) or SNR (Signal to Noise Ratio).

17. The determination means estimates the number of devices operating in the frequency channel corresponding to each of the plurality of communication links for each frequency channel, and when there is one or more frequency channels in which the estimated number of devices exceeds a predetermined threshold, determines that communication should be executed by the predetermined communication method. The communication device according to claim 12, characterized in that...

18. Based on the determination that the communication by the predetermined communication method should not be continued while the other communication device is executing communication by the predetermined communication method, the determination means controls the other communication device to end the communication by the predetermined communication method. The communication device according to claim 12, characterized in that...

19. The communication device has a plurality of communication circuits corresponding to each of the plurality of communication links. The communication device according to claim 12, characterized in that...

20. A communication method executed by a communication device, comprising: An establishment step of establishing a plurality of communication links with another communication device; An acquisition step of acquiring information indicating whether the other communication device can execute communication by a predetermined communication method in which communication is performed using only a part of the plurality of communication links selectively while maintaining the plurality of communication links; A communication step of starting communication by the predetermined communication method based on the control by the other communication device when the other communication device can execute communication by the predetermined communication method and communication by the predetermined communication method should be executed. A communication method, characterized in that...

21. A communication method executed by a communication device, comprising: An establishment step of establishing a plurality of communication links with another communication device; A notification step of notifying information indicating whether the communication device can execute communication by a predetermined communication method in which communication is performed using a part of the plurality of communication links selectively and not using the remaining part while maintaining the plurality of communication links; A determination step of determining whether or not to cause the other communication device to execute communication by the predetermined communication method when the other communication device can execute communication by the predetermined communication method; A control step of controlling the other communication device to execute communication by the predetermined communication method when it is determined by the execution determination that communication by the predetermined communication method should be executed. A communication method characterized by the above.

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

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