Communication device, communication method, and computer program product

Abstract

The invention provides a communication apparatus, a communication method, and a computer program product. The communication apparatus establishes a plurality of communication links with other communication apparatuses, obtains information indicating whether or not the other communication apparatuses are capable of performing communication using a predetermined communication method in which the communication is performed by the other communication apparatuses while maintaining the plurality of communication links. The communication apparatus performs communication by selectively using a portion of the plurality of communication links without using a remaining portion of the plurality of communication links, and performs communication by using the predetermined communication method in a case where the other communication apparatus is capable of performing communication using the predetermined communication method and is to perform communication using the predetermined communication method, and performs communication using the predetermined communication method in a case where the other communication apparatus is capable of performing communication using the predetermined communication method. Communication using the predetermined communication method is started on the basis of the control by the other communication device.

Description

Technical Field

[0001] The present invention generally relates to a communication device, a communication method, and a computer program product, and more particularly to data communication techniques in a communication device capable of concurrently using multiple links. Background Art

[0002] In recent years, with the increase in the amount of data to be transmitted, the development of communication techniques in wireless LANs (local area networks) and the like has also advanced. As the main communication standard for wireless LANs, the Institute of Electrical and Electronics Engineers (IEEE) 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, the latest standard, IEEE 802.11ax, standardizes a technique that uses orthogonal frequency division multiple access (OFDMA) to achieve a peak throughput of up to 9.6 gigabits per second (Gbps) and also improves the communication speed in congested situations. Note that OFDMA is an abbreviation for "orthogonal frequency division multiple access".

[0003] To develop a subsequent standard aimed at further improving throughput and also improving frequency utilization efficiency and communication latency, a new task group for developing the IEEE 802.11be standard has been established within the IEEE 802.11 working group. This task group is considering multi-link communication as a new feature to be specified in the IEEE 802.11be standard. In multi-link communication, a communication device called a multi-link device (MLD) concurrently uses multiple links by associating and coordinating multiple communication interfaces. Japanese Patent Application Laid-Open No. 2023-51567 discloses enhanced multi-link multi-radio (EMLMR) technology, in which, for each link in multi-link communication, a predetermined number of spatial streams are used for an initial frame exchange, and then frame exchange is performed on the link. On the other hand, the IEEE 802.11be standard is expected to specify enhanced multi-link single-radio (EMLSR) as a form of multi-link communication, in which communication is performed using one link at a time while maintaining multiple links established between MLDs. EMLSR is an abbreviation for enhanced multi-link single-radio.

[0004] When performing multi-link communication, the power consumption of a communication device is higher than when communicating using a single link. When using EMLSR (wherein communication is performed using a single link at a time), the power consumption of the communication device can be reduced. In addition, since EMLSR can selectively use one link from multiple links, in a congested communication environment, for example, by appropriately selecting available links, communication performance (such as latency characteristics) can be improved. However, it is also possible to improve communication performance and power efficiency by performing multi-link communication. For example, by using multi-link communication for high-speed communication, latency can be reduced, and power consumption can also be suppressed. In this way, although in some cases the use of EMLSR improves communication performance and power efficiency, there may also be cases where communication performance and power efficiency are not improved due to additional processing. SUMMARY OF THE INVENTION

[0005] One aspect of the present disclosure provides a technique for improving communication performance and power efficiency in a system that performs multi-link communication capable of using EMLSR.

[0006] According to one aspect of the present invention, there is provided a communication device including: an establishment unit configured to establish a plurality of communication links with another communication device; an acquisition unit configured to acquire information indicating whether the other communication device is capable of performing communication using a predetermined communication method in which, while maintaining the plurality of communication links, a part of the plurality of communication links is selectively used and the remaining part of the plurality of communication links is not used for communication; and a communication unit configured to, when the other communication device is capable of performing communication using the predetermined communication method and is to perform communication using the predetermined communication method, start communication using the predetermined communication method based on control performed by the other communication device.

[0007] According to one aspect of the present invention, there is provided a communication device, the communication device comprising: an establishment unit configured to establish a plurality of communication links with other communication devices; a notification unit configured to notify information indicating whether the communication device is capable of performing communication using a predetermined communication method, in the predetermined communication method, while maintaining the plurality of communication links, selectively using a part of the plurality of communication links and not using the remaining part of the plurality of communication links to perform communication; a determination unit configured to perform an execution determination related to whether to cause the other communication device to perform communication using the predetermined communication method when the other communication device is capable of performing communication using the predetermined communication method; and a control unit configured to perform control such that the other communication device performs communication using the predetermined communication method when the execution determination determines that the other communication device performs communication using the predetermined communication method.

[0008] According to one aspect of the present invention, there is provided a communication method performed by a communication device, the communication method comprising: establishing a plurality of communication links with other communication devices; obtaining information indicating whether the other communication device is capable of performing communication using a predetermined communication method, in the predetermined communication method, while maintaining the plurality of communication links, selectively using a part of the plurality of communication links and not using the remaining part of the plurality of communication links to perform communication; and starting communication using the predetermined communication method based on control performed by the other communication device when the other communication device is capable of performing communication using the predetermined communication method and is to perform communication using the predetermined communication method.

[0009] According to one aspect of the present invention, there is provided a computer program product including instructions, which when executed by a computer included in a communication device, cause the computer to perform the following method, the method comprising: establishing a plurality of communication links with other communication devices; obtaining information indicating whether the other communication device is capable of performing communication using a predetermined communication method, in the predetermined communication method, while maintaining the plurality of communication links, selectively using a part of the plurality of communication links and not using the remaining part of the plurality of communication links to perform communication; and starting communication using the predetermined communication method based on control performed by the other communication device when the other communication device is capable of performing communication using the predetermined communication method and is to perform communication using the predetermined communication method.

[0010] According to an aspect of the present invention, there is provided a communication method performed by a communication device, the communication method including: establishing a plurality of communication links with other communication devices; notifying information indicating whether the communication device is capable of performing communication using a predetermined communication method, in the predetermined communication method, while maintaining the plurality of communication links, selectively using a part of the plurality of communication links and not using the rest of the plurality of communication links to perform communication; performing an execution determination regarding whether to cause the other communication device to perform communication using the predetermined communication method when the other communication device is capable of performing communication using the predetermined communication method; and performing control to cause the other communication device to perform communication using the predetermined communication method when the execution determination determines to cause the other communication device to perform communication using the predetermined communication method.

[0011] According to an aspect of the present invention, there is provided a computer program product including instructions that, when executed by a computer included in a communication device, cause the computer to perform the following method, the method including: establishing a plurality of communication links with other communication devices; notifying information indicating whether the communication device is capable of performing communication using a predetermined communication method, in the predetermined communication method, while maintaining the plurality of communication links, selectively using a part of the plurality of communication links and not using the rest of the plurality of communication links to perform communication; performing an execution determination regarding whether to cause the other communication device to perform communication using the predetermined communication method when the other communication device is capable of performing communication using the predetermined communication method; and performing control to cause the other communication device to perform communication using the predetermined communication method when the execution determination determines to cause the other communication device to perform communication using the predetermined communication method.

[0012] Other features of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram showing an example of the configuration of a wireless communication system.

[0014] Figure 2 is a diagram showing an example of the sequence between an AP and a STA when multi-link communication is established.

[0015] Figure 3 is a diagram showing an example of the configuration of a Reduced Neighbor Report element.

[0016] Figure 4 is a diagram showing an example of the flow of operations performed when a STA executes EMLSR.

[0017] Figure 5 It is a diagram showing an example of the hardware configuration of a communication device.

[0018] Figure 6 It is a diagram showing an example of the functional configuration of a communication device.

[0019] Figure 7 It shows an example of the process of operations performed when the STA executes EMLSR.

[0020] Figure 8 It is a diagram showing an example of the process of operations performed when the STA executes EMLSR.

[0021] Figure 9 It is a diagram showing an example of the process of operations performed when the STA executes EMLSR.

[0022] Figure 10 It is a diagram showing an example of the process of operations performed when the AP executes EMLSR.

[0023] Figure 11 It is a diagram showing an example of the process of operations performed when the STA executes EMLSR.

[0024] Figure 12 It shows an example of the process of operations performed when the STA executes EMLSR. Detailed Description of the Invention

[0025] Hereinafter, embodiments will be described in detail with reference to the drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. In the embodiments, a plurality of features are described, but the invention is not limited to the invention that requires all of these features, and such a plurality of features can be appropriately combined. Further, in the drawings, the same or similar configurations are given the same reference numerals, and redundant descriptions thereof will be omitted.

[0026] System Configuration

[0027] Figure 1An example of the configuration of a wireless communication system according to the present embodiment is shown. For example, the wireless communication system includes an access point (AP) 101 and a station (STA) 102. The AP 101 and the STA 102 are wireless communication devices capable of performing wireless communication conforming to the IEEE 802.11 standard series, including the IEEE 802.11be standard. Note that IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers. The IEEE 802.11be standard may also be referred to as the EHT standard. EHT may be an abbreviation for Extremely High Throughput. The IEEE 802.11 standard series may include the IEEE 802.11a / b / g / n / ac / ax standards. These standards may be referred to as legacy standards. In other words, in addition to the IEEE 802.11be standard, the AP 101 and the STA 102 may also support one or more legacy standards. The network 110 formed by the AP 101 indicates the range within which the AP 101 and the STA 102 can communicate with each other. In other words, within the range of the network 110, the STA 102 can receive the signal sent by the AP 101, and the AP 101 can receive the signal sent by the STA 102. Note that in addition to the IEEE 802.11 standard series, the AP 101 and the STA 102 may also support other communication standards, such as Bluetooth (registered trademark), NFC, UWB, ZigBee, and MBOA. Note that UWB is an abbreviation for ultra wide band, and MBOA is an abbreviation for multi band OFDM alliance. In addition, NFC is an abbreviation for near field communication. UWB includes wireless USB, wireless 1394, WiNET, etc. In addition, the AP 101 and the STA 102 may support a communication standard for wired communication, such as a wired LAN.

[0028] Although Figure 1The figure shows a state where there is one AP 101 and one STA 102, but there can also be multiple APs 101 and STAs 102. In this case, multiple STAs 102 can be connected to one AP 101, and one STA 102 can be connected to multiple APs 101. The AP 101 can be, but is not limited to, a wireless LAN router, a personal computer (PC), etc. In addition, the STA 102 can be any electronic device, such as a smartphone, a tablet computer, a mobile phone, a PC, a camera, headphones, a printer, or a display, but is not limited to these. The AP 101 and the STA 102 can be information processing devices, such as wireless chips capable of performing wireless communication compliant with the IEEE 802.11be standard. In this embodiment, the AP 101 and the STA 102 can be referred to as communication devices, and no distinction is made between the two.

[0029] Multi-link communication is one of the new features defined in the IEEE 802.11be standard. In the traditional IEEE 802.11 standard series, the STA102 establishes a single link with the AP 101 and uses this link for data communication. In multi-link communication, the STA 102 uses two or more links in parallel to communicate with the AP 101, thereby enabling increased throughput. In addition, in the IEEE 802.11be standard, support for the 6 GHz band is being considered to expand the available frequency band for communication devices. In other words, the IEEE 802.11 standard series specifies the use of the 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz frequency bands that can be used for multi-link communication. Multiple frequency channels are defined in each frequency band; for example, channels each using a 20 MHz bandwidth are defined as frequency channels for one wireless link. In the IEEE 802.11 standard series, adjacent frequency channels can be combined (bonded) together to provide a bandwidth of more than 40 MHz in one frequency channel. For example, the AP 101 can establish a first link with the STA 102 using a first frequency channel in the 5 GHz band and communicate on this link. Then, the STA 102 can establish a second link with the AP 101 using a second frequency channel in the 6 GHz band and communicate on this link. In this case, the AP101 and the STA 102 perform multi-link communication, in which the first link is maintained while the second link is used in parallel. Therefore, in this embodiment, the AP 101 and the STA 102 are configured to be able to perform multi-link communication using multiple links in the network 110.

[0030] Figure 1The following example is shown: Three wireless links (links 121, 122, and 123) are established between the AP 101 and the STA 102. As described above, the wireless links can be in different frequency bands from each other. For example, the AP 101 and the STA 102 can establish link 121 using the 5 GHz band, link 122 using the 6 GHz band, and link 123 using the 2.4 GHz band in parallel. In addition, the wireless links can be constructed by different frequency channels belonging to the same frequency band. For example, two links can be used for multi-link communication, where one link uses channel 15ch in the 6 GHz band and the other link uses channel 207ch in the 6 GHz band. In this embodiment, "ch" is identification information for identifying a specific frequency channel. In addition, two links belonging to the same frequency band and links belonging to different frequency bands can be used in combination for multi-link communication. For example, link 121 (using channel 36ch in the 5 GHz band), link 122 (using channel 149ch in the 5 GHz band), and link 123 (using channel 15ch in the 6 GHz band) can be used for multi-link communication. By establishing multiple links between the AP 101 and the STA 102 using different frequency channels, even if one of the frequency channels is congested, communication can be carried out via the link using other frequency channels. This makes it possible to avoid a decrease in throughput and an increase in latency.

[0031] A communication device capable of multi-link communication is called a multi-link device (MLD). A communication device having the function of operating as an AP or STA conforming to the IEEE 802.11be standard and also having the function of operating as an MLD is called an APMLD or a STA MLD. A STA MLD can also be called a non-AP MLD. In an AP MLD or a STA MLD, each communication interface (I / F) constituting a link can be called an attached AP (A-AP) or an attached STA (A-STA). An attached STA is sometimes called an attached non-AP STA. An A-AP is attached to an AP MLD and operates on different frequency channels. In addition, an A-STA is attached to a STA MLD and operates on different frequency channels. When an A-AP or an A-STA is attached to an AP MLD or a STA MLD, it can be said to belong to the MLD. Note that in the following embodiments, the case of multi-link communication using the IEEE 802.11be standard will be described, but the present invention is not limited thereto. For example, the following discussion can also be applied to multi-link communication conforming to other wireless communication standards and multi-link communication using multiple wired links.

[0032] Figure 2An example of a sequence for establishing multi-link communication between the AP 101 and the STA 102 is shown. The AP 101, which is the AP MLD, has attached APs, namely A-AP-A 201 to A-AP-C 203, as wireless I / Fs operating on frequency channels corresponding to respective links. In addition, the STA 102, which is the STA MLD, has attached STAs, namely A-STA-A 204 to A-STA-C 206, as wireless I / Fs operating on frequency channels corresponding to respective links. Information required for establishing multi-link communication between the AP 101 and the STA 102 can be mutually notified by the basic multi-link elements. For example, the AP MLD transmits beacons or probe responses (F211 to F219) including the basic multi-link elements via each of the attached APs A-AP-A 201 to A-AP-C 203. Note that the probe responses (F214 to F219) can be transmitted in response to probe requests sent from the STA 102. On the other hand, the STA MLD notifies the basic multi-link elements to the AP MLD by using an Association Request transmitted via the A-STA, which will be described later. The STA 102 receives beacons or probe responses via the attached STAs A-STA-A 204 to A-STA-C 206. The STA 102 can detect that the AP 101 is the AP MLD by checking whether the received beacon or probe response includes the basic multi-link element. When the STA 102 detects that the AP 101 is the AP MLD, the STA 102 obtains information about the A-APs 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 can include information about the A-APs attached to the same AP MLD and information about the APs near the A-AP that transmits the RNR element. For example, the RNR element can include information about the frequency bands and channels used by the A-APs attached to the same AP MLD and the surrounding APs. Note that the fact that the APs reported by the RNR element are the A-APs attached to the same AP MLD can be indicated by the value of the MLD ID associated with the AP being 0. The STA 102 can use any one of the A-STAs to establish multi-link communication with the AP 101. For example, the STA 102 can perform a process of establishing multi-link communication with the A-AP-A 201 via the A-STA-A 204. As a process of establishing multi-link communication, authentication frames, association requests, and association responses (F220 to F222) can be exchanged with the AP 101. For example, the STA 102 can request the AP 101 to establish multi-link communication by transmitting an association request including the basic multi-link element (F221).As an example, STAMLD determines the frequency channels for each A-STA operation based on the information about A-AP obtained using the RNR element. Then, STA MLD notifies the information such as the frequency channels for A-STA operations to APMLD using the basic multi-link element. AP MLD obtains the information such as the frequency channels for A-STA operations from the received basic multi-link element. When APMLD returns an association response, multi-link communication (F222) can be established between AP 101 and STA 102. STA MLD switches the operation frequency channel of A-STA to the determined frequency channel. This enables multiple links to be collectively established between A-AP and A-STA without separately performing a link establishment process for each link. Note that after establishing multi-link communication, AP 101 and STA 102 can exchange security information, etc., using the 4-way handshake process (F223). Note that if AP 101 is not AP MLD, STA 102 can establish a connection using a single frequency channel. The use of the basic multi-link element and the RNR element is an example of a technique for exchanging information about multi-link communication between AP 101 and STA 102, but other techniques can also be used.

[0033] Figure 3An example of an RNR element is shown. The RNR element may include an element ID 301, a length 302, and neighbor AP information 303. The element ID 301 indicates the type of the element. For example, in the case of an RNR element, a value 201 may be stored. The length 302 indicates the length of the element. The number of neighbor AP information 303 may be the same as the number of APs to be announced. Each neighbor AP information 303 may include a TBTT information header 304, an operation class 305, and a channel number 306. Each neighbor AP information 303 may also include a TBTT information set 307. The TBTT information header 304 is header information indicating the length of each TBTT information included in, for example, the TBTT information set 307. The operation class 305 and the channel number 306 are used together to indicate the starting 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 TBTTOffset 308, a BSSID 309, a short SSID 310, BSS parameters 311, and a 20MHz PSD 312. The TBTT information set 307 may also include MLD parameters 313. The Neighbor AP TBTT offset 308 indicates information related to the timing of the beacon sent by the AP to be reported. The BSSID 309 indicates the identifier of the network formed 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 formed by the AP to be reported. The MLD parameters 313 may include an MLD ID 314, a link ID 315, a BSS ParametersChange Count 316, an All Updates Included 317, and a reservation 318. The MLD ID 314 indicates the identifier of the AP MLD to which the AP to be reported belongs. When the AP to be reported and the AP sending the RNR element belong to the same AP MLD, 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 parameter change count 316 indicates the length of time until a change in network parameters is implemented in the AP to be reported. If all update elements are included in the most recent parameter update, the All Updates Included 317 is set to 1. The reservation 318 is a reserved field.

[0034] One form of multi-link communication is multi-link single radio (MLSR). Generally, an MLD that supports multi-link communication has multiple radio I / Fs, and each radio I / F corresponds to one link when communicating using multiple links. On the other hand, in MLSR, a communication device maintains multiple links established with a partner communication device while communicating using one link at a time. It is expected that the IEEE 802.11be standard includes provisions for enhanced multi-link single radio (EMLSR), which is an extension of MLSR and enables switching to a more appropriate link during communication. For example, in EMLSR, STA 102 performs signal detection (listening operation) on multiple links. Then, AP 101 sends an initial control frame using one of the links on which STA 102 is performing the listening operation. Thereafter, data communication and the like are performed between AP 101 and STA 102 using the link on which the initial control frame was sent. For example, the initial control frame can be a MU-RTS trigger frame or a BSRP trigger frame, but is not limited thereto. Here, MU-RTS is an abbreviation for multi-user request to send. In addition, BSRP is an abbreviation for buffer status report poll. The initial control frame can also be sent from STA 102.

[0035] Information required for EMLSR between AP 101 and STA 102 can be notified by a basic multi-link element included in a beacon or a probe response sent from an AP MLD. For example, if the value of the EMLSR support field in the general information field of the basic multi-link element notified from AP 101 is 1, it indicates that the AP MLD supports EMLSR. Figure 4 is an example of a flowchart of EMLSR performed between AP 101 and STA 102. First, as described above, STA 102 establishes multi-link communication with AP 101 (steps S401 to S403). For example, STA 102 receives a beacon or a probe response from an A-AP (e.g., A-AP-A 201) and confirms that AP 101 supports multi-link communication (step S401). STA 102 obtains information about the A-AP attached to AP 101 (i.e., AP MLD) by using an RNR element (step S402). STA 102, according to, for example Figure 2The F220 to F222 shown in [figure] perform a process for establishing multi-link communication with the AP 101. The STA102 sets the operating frequency channel of the A-STA operation to the frequency channel used by the A-AP and establishes multi-link communication with the AP 101 (step S403). Then, the STA 102 performs processing to execute the EMLSR. First, the STA102 checks the value of the EMLSR support field in the general information field of the basic multi-link element included in the received beacon or probe response (step S404). In other words, the STA102 checks whether the AP 101 supports the EMLSR. If the EMLSR support field is not 1, the STA102 determines that the AP 101 does not support the EMLSR (\"No\" in step S404), and does not use the EMLSR (step S408). On the other hand, if the EMLSR support field is 1, the STA 102 determines that the AP 101 supports the EMLSR (\"Yes\" in step S404), and requests the start of the EMLSR (step S405). For example, the STA 102 may send an EML operation mode notification frame to the AP MLD. The AP 101 receives the EML operation mode notification frame and then sends a notification indicating the start of the EMLSR. For example, the AP 101 may send an EML operation mode notification whose value is set to the same as the value of the EML control field of the received EML operation mode notification. When the STA 102 receives the EML operation mode notification frame, it determines that the AP 101 has approved the start of the EMLSR (step S406), and executes the EMLSR (step S407).

[0036] Generally, when performing multi-link communication, the power consumption of the communication device is higher than when communicating using a single link. To solve this problem, by using the EMLSR, while communicating using one of the links, multiple established links are maintained, so that the power consumption of the communication device can be reduced. In addition, in the EMLSR, one link is selected from multiple links. Therefore, for example, in a congested communication environment, by appropriately selecting a link among the available links, the communication performance (for example, the delay can be reduced) can be improved. On the other hand, there are cases where the communication performance is improved by performing multi-link communication. For example, in an environment where the communication is not congested, by using multi-link communication for high-speed communication, the delay can be reduced and the power consumption can be suppressed. In this way, although in some cases the EMLSR improves the communication performance and power efficiency, there may also be cases where the communication performance and power efficiency are not improved due to the additional processing performed.

[0037] In view of this situation, in the present embodiment, the STA 102 obtains information indicating whether the AP 101 can perform communication using a predetermined communication method. If the AP 101 can perform communication using the predetermined communication method and is going to communicate using the predetermined communication method, the STA 102 starts communication using the predetermined communication method based on the control performed by the AP 101. For example, the predetermined communication method may be a communication method in which a plurality of communication links are maintained while selectively using one or more communication links for communication without using the remaining communication links. As an example, the predetermined communication method may be EMLSR, but is not limited thereto, and may be any communication method in which a plurality of communication links are maintained while selectively using one or more communication links without using the remaining communication links. For example, with EMLSR, the STA 102 can maintain a plurality of links while selectively using any one of them. The following will describe by taking EMLSR as an example. In the present embodiment, the STA 102 can make an execution determination regarding whether to start communication using EMLSR on its own. When the STA 102 determines to perform EMLSR when making the execution determination, the STA 102 requests the AP 101 to start communication using EMLSR. In addition, when performing EMLSR, the STA 102 determines whether to continue EMLSR, and when the STA 102 determines not to continue EMLSR, the STA 102 requests the AP 101 to terminate EMLSR. The STA 102 can terminate EMLSR based on the response from the AP 101. In this way, the STA 102 does not perform EMLSR only based on whether the AP 101 supports EMLSR, but performs EMLSR under the control of the AP 101 when it is going to perform EMLSR. On the other hand, the AP 101 in the present embodiment can make an execution determination regarding whether to enable the STA 102 to start communication using EMLSR. When the AP 101 determines that the STA 102 will perform EMLSR when making the execution determination, the AP 101 instructs the STA 102 to start communication using EMLSR. The STA 102 performs EMLSR based on the execution determination made by the AP 101. In addition, when performing EMLSR, the AP 101 determines whether to continue EMLSR, and when the AP 101 determines not to continue EMLSR, the AP 101 instructs the STA 102 to terminate EMLSR. Note that the following will describe by taking the operations performed by the STA 102 as an example, but similar operations can also be applied to the AP 101.

[0038] STA102 can determine whether to perform EMLSR based on the communication quality of each of multiple links between STA 102 and AP 101. In this case, for example, STA 102 can measure the communication quality of each of the multiple links between STA 102 and AP 101, and if there is any communication link with a value indicating that the communication quality is lower than a predetermined threshold, determine whether to perform EMLSR based on the number of such links. As an example, if there are multiple communication links with values indicating that the communication quality is lower than a predetermined threshold, STA 102 can determine to perform EMLSR. The value indicating the communication quality can be the received signal strength indication (RSSI) or the signal-to-noise ratio (SNR), or other parameters can be used. In this case, STA 102 can use the received power of beacons, probe responses, etc. received from AP 101 to calculate RSSI and SNR. When the communication quality of a link is low, packet errors and retransmissions may occur, so it is very likely that there will be a transmission delay. If a transmission delay occurs in one or more of the links used in multi-link communication, the packets successfully received on other links may need to be buffered for a longer period of time, which will increase the overall delay in communication. In this environment, if EMLSR is selected, the links with low communication quality can be avoided, so the communication performance of multi-link communication can be improved. Note that STA 102 can use the utilization rate of the frequency channels used by the links as the value indicating the communication quality. For example, STA102 measures the ratio of the time during which the received power in each frequency channel is higher than a predetermined threshold within a unit time. Then, if there are multiple frequency channels with a ratio higher than a predetermined threshold, it can be determined to perform EMLSR. In the case where the frequency channels have a high utilization rate and are congested, communication devices are very likely to experience more delays when obtaining a transmission opportunity. In this environment, if EMLSR is selected, the links that cause an increase in delay can be avoided, so that the communication performance of multi-link communication can be improved.

[0039] STA 102 can determine whether to perform EMLSR based on information obtained or notified from other communication devices. For example, STA 102 can count the number of devices on the frequency channel used by the link with AP 101 and determine whether to perform EMLSR based on this number. As an example, STA 102 can obtain the number of APs operating on each frequency channel from, for example, the RNR element included in the beacon or probe response received on the frequency channel used by the link. In this case, STA 102 designates the number of frequency channels where the number of operating APs is higher than a predetermined threshold. Then, if the number of frequency channels is higher than the predetermined threshold, STA 102 can determine to perform EMLSR. When a large number of APs operate in a specific frequency channel, the percentage of the frequency channel used by devices other than AP 101 and STA 102 may be large, and transmission delays may occur. As described above, an increase in the transmission delay of one or more links used in multi-link communication increases the overall delay in communication. Therefore, in such an environment, the communication performance of multi-link communication can be improved by selecting EMLSR. Note that instead of counting the number of devices on each frequency channel, STA 102 can determine whether to perform EMLSR based on an indication notified by AP 101 that indicates the congestion of the frequency channel. For example, STA 102 can use the BSS load element, extended BSS load element, etc. included in the beacon or probe response as an indication. In this case, STA 102 can use the traffic load in the network constructed by AP, the number of connected devices, etc. as an indication.

[0040] STA102 can determine whether to perform EMLSR based on its own device state. For example, if the remaining battery power of the device is less than or equal to a predetermined threshold, or lower than the predetermined threshold, STA102 can determine to perform EMLSR. When multiple wireless I / Fs corresponding to multiple links are all in operation, the power consumption in STA102 will become relatively high. When the remaining battery power is low, performing EMLSR can slow down the rate of battery power decline. In addition, in this case, STA102 can select the link to be used based on the communication quality of the link, rather than using one link in a fixed manner. This enables power consumption to be reduced while also preventing a decline in communication quality. In addition, if STA 102 is in a power-saving operation mode where the power consumed is smaller than during normal operation, STA 102 can determine to perform EMLSR. For example, the power-saving operation mode can be the power-saving operation mode defined in the IEEE 802.11 standard series. If the number of links in the power-saving operation mode among the links used in multi-link communication is higher than a predetermined threshold, STA 102 can determine to perform EMLSR. In addition, if the terminal device implementing STA102 is operating in the power-saving operation mode, STA102 can determine to perform EMLSR. For example, when the operating system of the terminal device detects that the remaining battery power is low, it can operate in the power-saving operation mode. STA 102 can determine whether to perform EMLSR based on the operation of the operating system of the terminal device.

[0041] STA102 can determine whether to perform EMLSR based on the type of application in communication. For example, if the application in communication requires low-latency communication (such as real-time communication, printer jobs, autonomous driving, or drone or robot control), STA102 can determine to perform EMLSR. By using EMLSR to avoid using congested links during communication, large delays can be avoided. On the other hand, if the application in communication requires high-capacity communication (such as high-definition video distribution), then STA 102 can determine not to perform EMLSR. By using more links (including links with low communication quality) for communication, data transmission can be completed faster. In this case, STA102 can determine to perform EMLSR by, for example, detecting the start of communication of a predetermined traffic type based on, for example, the traffic type (traffic identifier) of the data communicated with AP 101.

[0042] STA102 can determine whether to execute EMLSR based on the received instruction. For example, if the setting from the user indicates that EMLSR is to be executed, STA 102 can determine to execute EMLSR. In this case, STA 102 can determine whether to execute EMLSR, for example, when establishing multi-link communication with AP 101, or by periodically checking the settings made by the user to the device. In addition, when receiving an instruction to execute EMLSR from AP 101, STA102 can determine to execute EMLSR. For example, STA 102 can determine to execute EMLSR when receiving an EML operation mode notification frame. By executing EMLSR based on the instruction from AP 101, it is possible to determine whether to execute EMLSR based on information that cannot be obtained only by measuring near STA 102 or only by the notification from AP 101.

[0043] Device Configuration

[0044] Figure 5 FIG. shows an example of the hardware configuration of AP 101 and STA 102 in this embodiment. AP 101 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 multiple antennas. The storage unit 501 is constructed by one or more memories (such as ROM, RAM, etc.) and stores various information, such as computer programs for performing various operations described below and communication parameters for wireless communication. ROM and RAM are abbreviations for read only memory and random access memory, respectively. Note that in addition to memories such as ROM or RAM, the storage unit 501 can also be constituted by a storage medium such as a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, or a DVD. In addition, the storage unit 501 can include multiple memories, for example. Note that the storage unit 501 can record the setting information input by the user to the device, information related to the state of the device, such as the remaining battery power included in the device, and whether the power saving operation mode is set.

[0045] The control unit 502 is constructed by one or more processors (such as a CPU or an MPU), and performs overall control of the AP 101 or the STA 102 by executing a computer program stored in the storage unit 501. The control unit 502 can perform overall control of the AP 101 or the STA 102 through the cooperation between the computer program stored in the storage unit 501 and the operating system (OS). In addition, the control unit 502 generates data and signals (radio frames) to be transmitted in communication with other communication devices. Note that CPU is an abbreviation for central processing unit, and MPU is an abbreviation for microprocessing unit. In addition, the control unit 502 may include multiple processors such as a multi-core processor, and the overall control of the AP 101 or the STA 102 may be performed by multiple processors. In addition, the control unit 502 controls the functional unit 503 to perform predetermined processing such as wireless communication, imaging, printing, and projection. The functional unit 503 is hardware that enables the AP 101 or the STA 102 to perform predetermined processing.

[0046] The input unit 504 accepts various operations from the user. The output unit 505 outputs various types of information to the user via the monitor screen and the speaker. Here, the output performed by the output unit 505 may be display on the monitor screen, sound output from the speaker, vibration output, etc. Note that both the input unit 504 and the output unit 505 can be implemented by a single module such as a touch panel. In addition, the input unit 504 and the output unit 505 may be integrated with the AP 101 or the STA 102, or may be separate.

[0047] The communication unit 506 controls wireless communication compliant with the IEEE 802.11be standard. In addition, in addition to the IEEE 802.11be standard, the communication unit 506 can also control wireless communication compliant with other IEEE 802.11 series standards and can control wired communication via a wired LAN or the like. 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 can be constructed by a plurality of communication circuits corresponding to the respective links. Note that if the AP 101 supports the NFC standard, the Bluetooth standard, etc. in addition to the IEEE 802.11be standard, the AP 101 can control wireless communication according to these communication standards. In addition, if the AP 101 can perform wireless communication compliant with multiple communication standards, the AP 101 can be constructed to have a separate communication device and antenna for each communication standard. The communication device communicates data (such as image data, document data, and video data) with other communication devices via the communication unit 506. Note that the antenna 507 can be constructed as a unit separate from the communication unit 506 or can be constructed together with the communication unit 506 as a single module.

[0048] The antenna 507 is an antenna capable of communicating in the 2.4 GHz band, 5 GHz band, 6 GHz band, etc. In this embodiment, there may be two or more antennas, and when the communication unit 506 is constructed by a plurality of communication units, a separate antenna can be provided for each communication unit. In addition, different antennas can be provided for each frequency band.

[0049] Figure 6It is a block diagram showing the functional configuration of the communication devices (AP 101 and STA 102) of 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: a communication start process for establishing one or more links for wireless communication used by the communication device with a partner communication device; a control process for controlling functions related to multi-link communication; an addition process and a deletion process for adding and deleting links after the start of communication; and a communication end process for deleting all links. For example, the connection process may consist of an authentication process, an association process, and a 4-way handshake (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 STA 102 selects and determines the A-APs to be connected to each A-STA, and sets frequency channels and the like to be used by each A-STA. In addition, the wireless I / F setting unit 602 of AP 101 sets information related to the A-STAs connected to each A-AP. In addition, the wireless I / F setting unit 602 of AP 101 notifies the frame processing unit 603 and the frame transmission / reception unit 604 of information related to the A-APs and A-STAs with which links are to be established. The frame processing unit 603 generates frames to be transmitted according to the settings made by the wireless I / F setting unit 602. For example, the frame processing unit 603 of AP 101 generates beacons and probe responses including basic multi-link elements and RNR elements, etc. In addition, the frame processing unit 603 of AP 101 generates frames such as authentication frames, association response frames, and EML operation mode notification frames. For example, the frame processing unit 603 of STA102 generates association requests and probe requests including basic multi-link elements and RNR elements. In addition, the frame processing unit 603 of STA102 generates EML operation mode notification frames. In addition, the frame processing unit 603 processes frames received from a partner communication device and obtains information. For example, the frame processing unit 603 of STA 102 obtains information indicating that AP 101 can perform multi-link communication and EMLSR from the basic multi-link elements and RNR elements included in the received beacon, etc. In addition, the frame processing unit 603 of STA102 obtains the number of devices on the frequency channel for multi-link communication. According to an instruction from the wireless I / F setting unit 602, the frame transmission / reception unit 604 transmits wireless frames (including data frames and beacons and probe response frames generated by the frame processing unit 603), and receives wireless frames from a partner device. For example, the frame transmission / reception unit 604 of AP 101 can notify STA 102 that EMLSR is about to start by transmitting an EML operation mode notification frame. The communication quality measurement unit 605 uses beacons or probe response frames received by the frame transmission / reception unit 604 to measure and calculate the communication quality.Note that examples of communication quality information include, but are not limited to, RSSI and SNR. The communication method control unit 606 determines whether to execute or continue EMLSR based on, for example, the results of the communication quality measured and calculated by the communication quality measurement unit 605, the information acquired by the frame processing unit 603, the settings of the device recorded in the storage unit 501, and the power information, etc.

[0050] Processing flow

[0051] Next, several embodiments will be used to describe the processing flow of the above AP 101 and STA 102, the sequence in the wireless communication system, etc.

[0052] Processing example 1

[0053] Figure 7 An example of the process in which STA 102 determines whether to execute EMLSR based on the communication quality of the link in the multi-link communication established with AP 101 is shown. Note that in Figure 7 the operations similar to those in Figure 4 are denoted by the same reference numerals and their detailed descriptions will be omitted. For example, when STA 102 is connected to AP 101, this process can start. In addition, if the communication quality of the communication between STA 102 and the currently connected AP 101 deteriorates, STA 102 can start this process when detecting another AP 101 that can be used as the next connection destination.

[0054] First, STA 102 receives a beacon or a probe response via one of the A-STAs (step S401). At this time, STA 102 confirms that AP 101 is an AP MLD by verifying that the received beacon or probe response includes the basic multi-link element. Then, STA 102 obtains information such as the frequency bands and frequency channels of the respective A-APs (i.e., AP MLD) attached to AP 101 based on the basic multi-link element and the RNR element (step S402). For example, if a beacon transmitted by A-AP-A 201 is received via A-STA-A 204, STA 102 can obtain information about A-AP-B 202 and A-AP-C 203 from the basic multi-link element and the like. STA 102 measures the communication quality on each frequency channel (step S701). For example, STA 102 can measure the communication quality with A-AP-A 201 by measuring the RSSI, SNR, etc. of the beacon received via A-STA-A 204. Then, STA 102 sets A-STA-B 205 and A-STA-C 206 to the frequency channels used by A-AP-B 202 and A-AP-C 203, and receives the beacons and probe responses received on this frequency channel. STA 102 can measure the communication quality with A-AP-B 202 and A-AP-C 203 using the RSSI, etc. of the received beacons and the like. Then, STA 102 establishes multi-link communication with AP 101 (step S403).

[0055] STA102 determines whether AP 101 supports EMLSR (step S404). If it does not support EMLSR ("No" in step S404), it is determined not to execute EMLSR (step S408). On the other hand, if AP 101 supports EMLSR ("Yes" in step S404), STA 102 determines whether the communication quality with AP 101 meets a predetermined condition (step S702). For example, STA 102 specifies the communication quality of the link based on the RSSI of the beacon etc. received from the A-AP, and determines whether the predetermined condition is met. As an example, first, STA102 determines whether the measured RSSI is greater than the minimum received power required to use the modulation and coding scheme (MCS) with the lowest transmission rate on each link. For example, STA 102 can set the predetermined condition as follows: the number of links where the measured RSSI is lower than the minimum received power is greater than or equal to a predetermined threshold. Note that MCS is an index of the combination of wireless modulation schemes, coding rates, etc., and the MCS that can be used by the communication device changes according to the communication environment. For example, the worse the communication quality, the lower the transmission rate MCS that can be used. In this example, STA102 can compare the measured RSSI of each link with the minimum received power and specify the number of links where the RSSI is lower than the minimum received power. For example, if for multiple (e.g., two or more) links, the RSSI is lower than the minimum received power, STA102 can determine that using EMLSR will improve the communication quality. In this case, STA 102 performs the process of executing EMLSR with AP 101 (steps S405 to S407). Note that when the RSSI is lower than the minimum received power in three or more links, STA102 can determine to use EMLSR. In addition, STA102 can determine whether to use EMLSR based on the ratio of the number of links where the RSSI is lower than the minimum received power to the number of links established with AP 101. On the other hand, if the predetermined condition is not met ("No" in step S702), STA 102 determines not to execute EMLSR (step S408). For example, if the RSSI is greater than the minimum received power for any link, STA 102 can determine that the predetermined condition is not met. Note that the threshold used as the predetermined condition is not limited to the minimum received power and can be the received power required to use a predetermined MCS. In addition, if the RSSI is lower than the minimum received power for one link, STA102 can determine that the predetermined condition is met. In this way, if the communication quality of one or more links between AP 101 and STA 102 meets the predetermined condition, by executing EMLSR, a link can be selected from the links with good quality for communication. This makes it possible to improve the communication performance when using EMLSR.

[0056] When STA102 receives a response to the request to start EMLSR from AP 101, it starts communicating using EMLSR. Here, while executing EMLSR, STA 102 can select the link with the best communication quality from the maintained links and perform communication using the selected link. For example, while maintaining the links, STA102 measures the communication quality of the frequency channels used by each link. STA102 can regularly measure the communication quality using beacons etc. received from AP 101, or can measure the communication quality using frames exchanged with AP 101 before transmission. Each time the communication quality is measured, STA102 can update the link used in EMLSR. In addition, STA 102 can use a random number etc. to select a link with a communication quality higher than a predetermined threshold from multiple links and perform communication using the selected link. In addition, STA102 can select a predetermined number of links in descending order of communication quality from multiple links and select one link from the selected links to perform communication. In this way, when executing EMLSR, STA 102 can select a link with good communication quality from multiple maintained links and perform communication using the selected link, thereby improving the communication performance when using EMLSR.

[0057] Note that when executing EMLSR, STA 102 can measure the communication quality of each link and can terminate EMLSR when a predetermined condition is met. In this case, after terminating EMLSR, STA 102 can use multiple links in parallel to perform multi-link communication. As an example, if the predetermined condition used when executing EMLSR is not met, STA102 can determine to terminate EMLSR. For example, STA 102 measures the RSSI or SNR of the beacon or probe response received from the A-AP on each link. Then it determines whether the RSSI etc. of the link is higher than the minimum received power. For example, if the predetermined condition for executing EMLSR is that the RSSI is lower than the minimum received power for two or more links, then when there are no two or more links with RSSI lower than the minimum received power, STA102 can determine to terminate EMLSR. In addition, STA102 can use a condition different from the predetermined condition used when executing EMLSR to determine whether to continue EMLSR. For example, if the predetermined condition for executing EMLSR is that the RSSI is lower than the minimum received power for two or more links, then when the RSSI is higher than the minimum received power for all links, STA102 can determine to terminate EMLSR. In this way, if the communication quality of the link between AP 101 and STA 102 meets the predetermined condition while executing EMLSR, EMLSR can be terminated, so that multiple links with good quality can be used in parallel for communication. This makes it possible to improve the communication performance between AP 101 and STA102.

[0058] Processing Example 2

[0059] Figure 8 An example of a process in which STA102 determines whether to execute EMLSR based on information obtained from or notified by other communication devices is shown. Note that in Figure 8 , with Figure 4 or Figure 7Operations similar to those in [description] are denoted by the same reference numerals, and their detailed descriptions will be omitted. For example, STA 102 obtains information related to the A-AP attached to AP 101 (i.e., AP MLD) from the beacon or probe response sent by AP 101, and establishes multi-link communication with AP 101 (steps S401, step S402, and step S403). At this time, STA 102 uses the RNR element or basic multi-link element included in the beacon etc. sent by AP 101 to obtain information related to the A-AP attached to AP 101 (i.e., AP MLD) and other surrounding APs. For example, STA 102 can use the RNR element or basic multi-link element to specify the frequency channels on which each A-AP operation in AP 101 is performed, and obtain information related to other APs using this frequency channel. Then, STA 102 calculates the number of devices operating on each frequency channel where the A-AP operates (step S801). For example, in the basic multi-link element, the same MLD ID is assigned to each A-AP that constitutes the same AP MLD. Therefore, for example, STA 102 can calculate the number of APs on the frequency channel where the A-AP operates by counting the number of different MLD IDs included in the basic multi-link element for each frequency channel. In addition, STA 102 can calculate the number of APs on each frequency channel using the included A-STA. For example, STA 102 specifies the frequency channels on which each A-AP operation in AP 101 is performed by using the RNR element or basic multi-link element. Then, STA 102 receives the beacons and probe responses sent by other APs on each frequency channel. For example, STA 102 can receive the beacons and probe responses on each frequency channel by setting the included A-STA to the frequency channel where the A-AP operates. STA 102 can calculate the number of APs operating on each frequency channel by using the AP identifier or RNR element included in the received beacons and probe responses. Note that the number of devices counted by STA 102 as operating on each frequency channel is not limited to the number of APs, and may include the number of STAs connected to each AP and the number of communication devices of other wireless systems. For example, STA 102 can obtain and use the number of STAs connected to each AP by using the BSS load, extended BSS load, etc. included in the beacon or probe response. In addition, the information that STA 102 can obtain and use from other communication devices is not limited to the number of operating devices. For example, STA 102 can obtain and use the utilization rate of the frequency channel, etc. STA 102 can obtain the utilization rate of the frequency channel by using the BSS load, extended BSS load, etc. included in the beacon or probe response.

[0060] When establishing multi-link communication with AP 101, STA 102 determines whether AP 101 supports EMLSR (step S404), and determines whether a predetermined condition is satisfied based on the information obtained in step S801 (step S802). For example, STA 102 determines whether the number of devices on the frequency channels for multi-link satisfies a predetermined condition (step S802). For example, STA 102 uses the number of APs on each frequency channel calculated in step S801 to specify the number of frequency channels with the number of APs higher than a predetermined threshold. In addition, instead of or in addition to the number of APs, STA 102 can also use the number of STAs connected to the AP to specify the number of frequency channels with the number of devices operating on the frequency channel higher than a predetermined threshold. Alternatively, instead of the number of devices, STA 102 can specify the number of frequency channels with utilization higher than a predetermined threshold. If the number of frequency channels is higher than a predetermined threshold, STA 102 determines that the predetermined condition is satisfied and determines to execute EMLSR. For example, if the number of APs is higher than a predetermined threshold in multiple (e.g., two or more) frequency channels, STA 102 can determine that the communication performance will be improved by using EMLSR. Note that if the number of APs is higher than a predetermined threshold in one or three or more frequency channels, STA 102 can determine to use EMLSR. When it is determined that the predetermined condition is satisfied (Yes in step S802), STA 102 performs the processing of steps S405 to S407 and starts EMLSR. On the other hand, when it is determined that the predetermined condition is not satisfied (No in step S802), STA 102 does not execute EMLSR (step S408). By determining whether to execute EMLSR based on the congestion of the frequency channels used in the multi-link communication between AP 101 and STA 102, a link with a shorter delay can be selected for communication. This makes it possible to improve the communication performance between AP 101 and STA 102.

[0061] When the STA 102 receives a response to the request to start the EMLSR from the AP 101, it starts the communication using the EMLSR. Here, while executing the EMLSR, the STA 102 can select one link from multiple links based on the information obtained or notified from other communication devices and perform the communication. For example, while maintaining each link, the STA 102 measures the congestion of the frequency channel used by the link based on the information obtained or notified from other communication devices. For example, the STA 102 can obtain the number of APs, STAs, etc. operating on each frequency channel by using the beacon received from the AP 101, etc., and can obtain the utilization rate of the frequency channel. Then, the STA 102 can select one link from the links based on the obtained information. For example, the STA 102 can select the link with the smallest number of devices operating on the used frequency channel. Each time the STA 102 obtains information from other communication devices, it can update the link used in the EMLSR. In addition, the STA 102 can use a random number, etc. to select one link from the links where the number of operating devices or the utilization rate of the frequency channel is lower than a predetermined threshold and perform the communication using the selected link. In addition, the STA 102 can select a predetermined number of links in descending order of the number of operating devices or the utilization rate of the frequency channel and select one of them to perform the communication. In this way, the STA 102 can select a less congested link based on the information obtained or notified from other communication devices and perform the EMLSR, thereby improving the communication performance when using the EMLSR.

[0062] Note that when performing EMLSR, if STA102 meets a predetermined condition based on information obtained or notified from other communication devices, STA102 may terminate EMLSR. For example, STA 102 may calculate the number of devices or the utilization rate of the frequency channels used by each link and terminate EMLSR when the predetermined condition is met. In this case, after terminating EMLSR, STA 102 may perform multi-link communication using multiple links in parallel. For example, STA 102 uses the beacons or probe responses received from the A-AP on each link to specify the number of devices. STA 102 may use the included A-STA to specify the number of devices on each frequency. Then, it is determined whether the number of devices on each frequency is higher than a predetermined threshold. As an example, if the predetermined condition used when performing EMLSR is not met, STA102 may determine to terminate EMLSR. For example, if the predetermined condition is that the number of APs for two or more links is higher than a predetermined threshold when performing EMLSR, then when there are no two or more links with the number of APs higher than the predetermined threshold, STA 102 may determine to terminate EMLSR. In addition, STA 102 may use a condition different from the predetermined condition used when performing EMLSR to determine whether to continue EMLSR. For example, if the predetermined condition is that the number of APs for two or more links is higher than a predetermined threshold when performing EMLSR, then when the number of APs for all links is lower than the predetermined threshold, STA102 may determine to terminate EMLSR. In this way, if other STA 102 terminates EMLSR when a predetermined condition based on information obtained or notified from other communication devices is met, multiple less congested links can be used in parallel for communication. This makes it possible to improve the communication performance between AP 101 and STA102.

[0063] Processing Example 3

[0064] Figure 9 An example showing the process in which STA102 determines whether to perform EMLSR based on the device state is shown. Note that in Figure 9 in, compared with Figure 4 , Figure 7 and Figure 8Operations similar to those in [description] are denoted by the same reference numerals, and their detailed descriptions will be omitted. For example, STA 102 obtains information related to the A-AP attached to AP 101 (i.e., AP MLD) from the beacon or probe response sent by AP 101, and establishes multi-link communication with AP 101 (steps S401, S402, and S403). When establishing multi-link communication with AP 101, STA 102 determines whether AP 101 supports EMLSR (step S404), and checks its own device status (step S901). For example, STA 102 determines whether the remaining battery power is lower than a threshold. If the remaining battery power is lower than the threshold, then STA 102 determines that a predetermined condition is satisfied ( "Yes" in step S901), performs the processing of steps S405 to S407, and starts EMLSR. On the other hand, when it is determined that the predetermined condition is not satisfied ( "No" in step S901), STA 102 does not perform EMLSR (step S408). Note that in step S901, instead of checking the remaining battery power, STA 102 can, for example, determine whether it is operating in the power-saving operation mode, determine whether the user has set to execute EMLSR, or determine the type of application for communication, traffic volume, etc. In this way, by determining whether to execute EMLSR based on the status of STA 102, it is possible to switch between multi-link communication using multiple links in parallel and EMLSR using a single link during communication. This makes it possible to reduce the power consumption of the device while maintaining the communication performance when using EMLSR.

[0065] Note that when executing EMLSR, STA 102 can monitor its own device status and terminate EMLSR when a predetermined condition is satisfied. In this case, after terminating EMLSR, STA 102 can perform multi-link communication using multiple links in parallel. For example, if the remaining battery power of the device is higher than a predetermined threshold, if the device changes from the power-saving operation to the normal operation, or if the user cancels the EMLSR setting, then STA 102 can determine that the predetermined condition is satisfied and terminate EMLSR. In addition, if the type or quantity of traffic caused by the application communicating with AP 101 changes, then STA 102 can determine that the predetermined condition is satisfied and terminate EMLSR. In this way, if STA 102 terminates EMLSR when a predetermined condition associated with its own device status is satisfied during the execution of EMLSR, it is possible to switch between EMLSR and multi-link communication using multiple links in parallel according to the status of the device itself. This makes it possible to improve the communication performance and power performance when STA 102 performs multi-link communication.

[0066] Note that while performing EMLSR, the STA 102 can use the technique shown in Processing Example 1 to select the link with the best communication quality from among multiple maintained links and perform communication using the selected link. Additionally, when performing EMLSR, the STA 102 can use the technique shown in Processing Example 2 to select one link from among multiple links based on information obtained or notified from other communication devices and perform communication using the selected link.

[0067] Processing Example 4

[0068] Figure 10 and Figure 11 shows an example of the processing when the STA 102 performs EMLSR based on an instruction received from the AP 101. Figure 10Shows the operations of AP 101 in this process. First, AP 101 sends beacons or probe responses via each included A-AP (step S1001). AP 101 can notify support for multi-link communication by including a basic multi-link element in the beacon or probe response. In addition, AP 101 can use the basic multi-link element or RNR element to notify information related to the included A-AP and surrounding APs. Then, AP 101 can receive a request to establish multi-link communication from STA 102 (step S1002). For example, a request to establish multi-link communication from STA 102 can be made through an association request that includes a basic multi-link element. In response to the request to establish multi-link communication from STA 102, AP 101 can establish multi-link communication with STA 102 (step S1003). For example, AP 101 can establish multi-link communication by sending an association response that includes a basic multi-link element. Note that AP 101 can establish an association between the A-AP of AP 101 and the A-STA of STA102 by exchanging an association request and an association response. In other words, the combination of the A-AP and A-STA that constitute the links used in multi-link communication can be determined. Then, AP 101 determines whether STA102 supports EMLSR (step S1004). For example, AP 101 can determine whether STA102 supports EMLSR based on the EMLSR support value in the basic multi-link element included in the association request received from STA 102. If STA 102 supports EMLSR (Yes in step S1004), then AP 101 determines whether to make STA 102 perform EMLSR (step S1005). For example, when determining whether to make STA 102 perform EMLSR, AP 101 can use the predetermined conditions described above in Processing Examples 1 to 3 for determining whether STA 102 is to perform EMLSR. Specifically, AP 101 can determine whether to make STA 102 perform EMLSR based on information such as the communication quality between AP 101 and STA102, or the number of devices operating on each frequency channel used in multi-link communication, utilization rate, etc. As an example, if there are two or more communication links in the communication link established with STA102 where the values indicating communication quality (RSSI, SNR, etc.) are lower than a predetermined threshold, then AP 101 can determine to perform EMLSR. AP 101 can also estimate the number of devices operating on each frequency channel corresponding to the communication link established with STA102. If there are two or more frequency channels where the estimated number of devices is higher than a predetermined threshold, then AP 101 can determine to perform EMLSR. Note that AP 101 can obtain the battery state, power-saving operation state, user settings, etc. of STA102 and make a determination based on the obtained information.This information can be obtained by the AP 101 requesting a report from the STA 102 and receiving the report from the STA 102. The AP 101 can also make a determination based on the type of application communicating with the STA 102. When the AP 101 determines that the STA 102 is to perform EMLSR (Yes in step S1005), it instructs the STA 102 to start EMLSR (step S1006). For example, the AP 101 can use an EML operation mode notification to instruct the STA 102. Then, the AP 101 performs communication with the STA 102 using EMLSR (step S1007). The AP 101 can perform EMLSR when it receives an EML operation mode notification (the value of which is the same as the EML control field of the sent EML operation mode notification). Note that when the AP 101 determines that the STA 102 does not support EMLSR (No in step S1004) or does not cause the STA 102 to perform EMLSR (No in step S1005), it does not cause the STA 102 to perform EMLSR (step S1008).

[0069] Note that while performing EMLSR, the AP 101 can measure the communication quality of each link, or the number of devices operating on each frequency channel used in multi-link communication, utilization rate, etc., and terminate EMLSR when a predetermined condition is met. In addition, the AP 101 can terminate EMLSR based on the status of the STA 102 obtained from the STA 102 (remaining battery power, power-saving operation status, user settings, type of application for communication, etc.). In this case, the AP 101 can notify the STA 102 of the instruction to terminate EMLSR. For example, the AP 101 can use an EML operation mode notification to notify the STA 102 of the instruction to terminate EMLSR. After terminating EMLSR, the AP 101 can perform multi-link communication using multiple links in parallel. As an example, if the predetermined condition used when performing EMLSR is not met, the AP 101 can determine to terminate EMLSR. In addition, the AP 101 can use a condition different from the predetermined condition used when performing EMLSR to determine whether to continue EMLSR. When determining whether to cause the STA 102 to continue EMLSR, the AP 101 can use the predetermined conditions for determining whether the STA 102 is to continue EMLSR described in the above Processing Examples 1 to 3. In this way, when performing EMLSR, the AP 101 determines whether to cause the STA 102 to continue EMLSR, and if the predetermined condition is met, terminates EMLSR, thereby enabling the communication performance between the AP 101 and the STA 102 to be improved.

[0070] Note that, similar to the operation of STA 101 shown in Processing Example 1, during the execution of EMLSR, AP 101 can select the link with the best communication quality from the maintained links and perform communication using the selected link. Additionally, similar to the operation of STA 101 shown in Processing Example 2, when executing EMLSR, AP 101 can select one link from multiple links based on the number of devices operating on each frequency channel used in multi-link communication, utilization rate, etc., and perform communication using the selected link.

[0071] Figure 11 Illustrates the operation of STA102 in this process. Note that in Figure 11 the operations similar to those in Figure 4 and Figures 7 to 9 are given the same reference numerals and their detailed descriptions will be omitted. For example, STA102 obtains information related to A-AP attached to AP 101 from the beacon or probe response sent by AP 101 and establishes multi-link communication with AP 101 (Steps S401, Step S402, and Step S403). When establishing multi-link communication with AP 101, STA 102 determines whether AP 101 supports EMLSR (Step S404). Then, when STA 102 receives an instruction to execute EMLSR from AP 101 ( "Yes" in Step S1101), it executes EMLSR (Step S407). On the other hand, if no instruction is received from AP 101 ( "No" in Step S1101), then STA102 does not execute EMLSR (Step S408). Additionally, if no instruction is received from AP 101, then STA102 can determine whether to execute EMLSR based on, for example, Figures 7 to 9 and the processes shown in Figure 12 described later, etc., and request AP 101 to execute EMLSR based on this determination. Additionally, when executing EMLSR, if STA102 receives a notification of an instruction to terminate EMLSR from AP 101, it can terminate EMLSR.

[0072] Processing Example 5

[0073] STA102 can execute a combination of the above processing procedures. Figure 12 Illustrates an example of the following process, in which STA 102 determines whether to execute EMLSR based on the communication quality between AP 101 and STA 102, and information obtained or notified from other communication devices (for example, the number of devices operating on the same frequency channel). Note that in Figure 12 the operations similar to those in Figure 4 , Figures 7 to 9 and Figure 11Operations similar to those in [description] are given the same reference numerals, and their detailed descriptions will be omitted. For example, when establishing multiple links with AP 101, STA 102 measures the communication quality of each link (step S701) and obtains the number of devices operating on the frequency channels used by each link (step S801). The method of measuring the communication quality and the method of obtaining the number of devices can be the methods described above with reference to Figure 7 and Figure 8 Then, when STA102 confirms that AP 101 supports EMLSR (Yes in step S404), it determines whether the measured communication quality satisfies a predetermined condition (step S702) and whether the obtained number of devices satisfies a predetermined condition (step S802). The method of determining the condition regarding the communication quality and the method of determining the condition regarding the number of devices can be the methods described above with reference to Figure 7 and Figure 8 Then, if the predetermined condition regarding the communication quality is satisfied and the predetermined condition regarding the number of devices is also satisfied (Yes in step S702 and Yes in step S802), then STA 102 performs the process for executing EMLSR (steps S405 to S407). On the other hand, if at least one of the predetermined condition regarding the communication quality and the predetermined condition regarding the number of devices is not satisfied (No in step S702 or No in step S802), then STA102 does not execute EMLSR (step S408). Note that the condition determination can be performed sequentially or in parallel. In addition, the sequence of the condition determination can be changed. In this way, by determining whether to use EMLSR based on multiple conditions, it is possible to more accurately determine whether to use EMLSR or perform multi-link communication using multiple links in parallel. For example, even if there are multiple links that can provide a predetermined level of communication quality, if the delay of one of these links is long, selecting EMLSR can avoid deterioration of communication performance due to increased delay.

[0074] As described above, according to this embodiment, the communication device obtains information indicating whether a partner communication device can perform communication using a predetermined communication method. Then, if the partner communication device can perform communication using the predetermined communication method and is to perform communication using the predetermined communication method, communication using the predetermined communication method starts based on the control performed by the partner communication device. In other words, the communication device does not simply perform communication using the predetermined communication method based on the fact that the partner communication device supports the predetermined communication method, but rather performs the predetermined communication method based on the control performed by the partner communication device when the predetermined communication method is to be performed. In this way, the communication device can appropriately switch between the predetermined communication method and normal multi-link communication according to the environment while performing communication. This makes it possible to improve the communication performance and power performance of multi-link communication. In this embodiment, EMLSR is used as an example of the predetermined communication method for selectively using one of the established multiple links for communication while maintaining them, but this technique can also be applied to other communication methods. For example, the present invention can also be applied to a communication method in which, while maintaining multiple communication links, communication is performed by selectively using two or more of the links and not using the remaining links. In this case, the communication device can select multiple links with good communication quality, etc. from the maintained multiple links and perform communication using the selected links.

[0075] Other embodiments

[0076] Embodiments of the present invention can also be implemented by a computer of a system or apparatus that reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more fully referred to as a "non-transitory computer-readable storage medium") to perform the functions of one or more of the above-described embodiments, and / or includes one or more circuits (e.g., an application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiments. Moreover, embodiments of the present invention can be implemented by a method of, for example, the computer of the system or apparatus reading and executing the computer-executable instructions from the storage medium to perform the functions of one or more of the above-described embodiments, and / or controlling the one or more circuits to perform the functions of one or more of the above-described embodiments. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessing unit (MPU)), and may include a network of separate computers or separate processors to read and execute the computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, a hard disk, a random access memory (RAM), a read-only memory (ROM), a memory of a distributed computing system, an optical disk (such as a compact disc (CD), a digital versatile disc (DVD), or a Blu-ray disc (BD) TM ), a flash device, and a memory card, among others.

[0077] Embodiments of the present invention can also be implemented by the following method, that is, by providing software (including a computer program product including computer programs / instructions) for performing the functions of the above-described embodiments to a system or apparatus via a network or various storage media, and the computer (central processing unit (CPU), microprocessing unit (MPU)) of the system or apparatus reads and executes the computer programs / instructions.

[0078] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation so as to cover all such variations and equivalent structures and functions.

Claims

1. A communication device, comprising: a establishing unit configured to establish a plurality of communication links with other communication devices; an obtaining unit configured to obtain information indicating whether the other communication devices are capable of performing communication using a predetermined communication method, in which, while maintaining the plurality of communication links, a part of the plurality of communication links is selectively used without using the remaining part of the plurality of communication links for communication; and a communication unit configured to start communication using the predetermined communication method based on control by the other communication device when the other communication devices are capable of performing communication using the predetermined communication method and are to perform communication using the predetermined communication method.

2. The communication device according to claim 1, further comprising: a determining unit configured to perform an execution determination related to whether to start communication using the predetermined communication method, where when the execution determination determines to perform communication using the predetermined communication method, the communication unit requests the other communication devices to start communication using the predetermined communication method.

3. The communication device according to claim 2, where when one or more of the plurality of communication links include a value indicating communication quality lower than a predetermined threshold, the determining unit determines to perform communication using the predetermined communication method.

4. The communication device according to claim 3, where the value indicating communication quality is a received signal strength indication RRSI or a signal-to-noise ratio SNR.

5. The communication device according to claim 2, where the determining unit further estimates the number of devices operating on each of a plurality of frequency channels corresponding to the plurality of communication links, and when one or more of the plurality of frequency channels include the estimated number of devices higher than a predetermined threshold, the determining unit determines to perform communication using the predetermined communication method.

6. The communication device according to claim 2, where when the communication device operates in a power saving operation mode, the determining unit determines to perform communication using the predetermined communication method.

7. The communication device according to claim 2, where when the remaining battery power of the communication device is less than or equal to a predetermined threshold, the determining unit determines to perform communication using the predetermined communication method.

8. The communication device according to claim 1, where when receiving an instruction indicating to perform communication using the predetermined communication method from the other communication device, the communication unit starts communication using the predetermined communication method.

9. The communication device according to claim 2, where the determining unit further performs a continuation determination related to whether to continue communication using the predetermined communication method while the communication unit performs communication using the predetermined communication method, and In the case of continuing to determine that communication using the predetermined communication method is not to be continued, the communication unit requests the other communication device to terminate communication using the predetermined communication method.

10. The communication device according to claim 8, wherein in the case of receiving an instruction from the other communication device to terminate communication using the predetermined communication method, the communication unit terminates communication using the predetermined communication method.

11. The communication device according to any one of claims 1 to 10, wherein the communication device includes a plurality of communication circuits respectively corresponding to the plurality of communication links.

12. A communication device, comprising: a establishing unit configured to establish a plurality of communication links with other communication devices; a notification unit configured to notify information indicating whether the communication device can perform communication using a predetermined communication method, in which, while maintaining the plurality of communication links, a part of the plurality of communication links is selectively used without using the remaining part of the plurality of communication links for communication; a determining unit configured to perform an execution determination regarding whether to cause the other communication device to perform communication using the predetermined communication method in the case where the other communication device can perform communication using the predetermined communication method; and a control unit configured to, in the case where the execution determination determines that the other communication device performs communication using the predetermined communication method, perform control so that the other communication device performs communication using the predetermined communication method.

13. The communication device according to claim 12, wherein the determining unit performs the execution determination based on a request from the other communication device, and in the case where the execution determination determines that the other communication device performs communication using the predetermined communication method, the control unit, in response to the request, instructs the other communication device to perform communication using the predetermined communication method.

14. The communication device according to claim 12, wherein the control unit sends an instruction to the other communication device to perform communication using the predetermined communication method.

15. The communication device according to claim 12, wherein in the case where one or more of the plurality of communication links include a value indicating communication quality that is lower than a predetermined threshold, the determining unit determines to cause the other communication device to perform communication using the predetermined communication method.

16. The communication device according to claim 15, wherein the value indicating communication quality is a received signal strength indication RSSI or a signal-to-noise ratio SNR.

17. The communication device according to claim 12, wherein The determining unit also estimates, for each of a plurality of frequency channels respectively corresponding to the plurality of communication links, the number of devices operating on each of the plurality of frequency channels, and in a case where the plurality of frequency channels include one or more frequency channels on which the estimated number of devices is higher than a predetermined threshold, the determining unit determines to cause the other communication device to perform communication using the predetermined communication method.

18. The communication device according to claim 12, wherein while the other communication device performs communication using the predetermined communication method, in a case where it is determined that the other communication device does not continue to perform communication using the predetermined communication method, the determining unit controls the other communication device to terminate communication using the predetermined communication method.

19. The communication device according to any one of claims 12 to 18, wherein the communication device includes a plurality of communication circuits respectively corresponding to the plurality of communication links.

20. A communication method performed by a communication device, the communication method comprising: establishing a plurality of communication links with other communication devices; obtaining information indicating whether the other communication device is capable of performing communication using a predetermined communication method, in which, while maintaining the plurality of communication links, a part of the plurality of communication links is selectively used and the remaining part of the plurality of communication links is not used for communication; and in a case where the other communication device is capable of performing communication using the predetermined communication method and is to perform communication using the predetermined communication method, starting communication using the predetermined communication method based on control performed by the other communication device.

21. A computer program product comprising instructions that, when executed by a computer included in a communication device, cause the computer to perform the communication method according to claim 20.

22. A communication method performed by a communication device, the communication method comprising: establishing a plurality of communication links with other communication devices; notifying information indicating whether the communication device is capable of performing communication using a predetermined communication method, in which, while maintaining the plurality of communication links, a part of the plurality of communication links is selectively used and the remaining part of the plurality of communication links is not used for communication; performing an execution determination regarding whether to cause the other communication device to perform communication using the predetermined communication method in a case where the other communication device is capable of performing communication using the predetermined communication method; and in a case where the execution determination determines to cause the other communication device to perform communication using the predetermined communication method, performing control to cause the other communication device to perform communication using the predetermined communication method.

23. A computer program product including instructions that, when executed by a computer included in a communication device, cause the computer to perform the communication method according to claim 22.

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