Method and apparatus for low power operation in wireless LAN supporting MLSR operation

Abstract

Methods and apparatus for low power operation in a wireless local area network supporting MLSR operation are disclosed. The method of STA MLD comprises the steps of: performing a power saving operation in a first link and a second link; when a first STA associated with the STA MLD operates in a wake-up state in a first link, the first STA receives a beacon frame from a first AP associated with the AP MLD; the first STA performs a first communication with the first AP on the first link based on the beacon frame; after completion of the first communication, when a second STA associated with the STA MLD operates in a wake-up state in a second link, the second STA performs a second communication with a second AP associated with the AP MLD.

Description

Technical Field

[0001] The present invention relates to a wireless local area network (WLAN) communication technology, and more particularly, to a technology for low-power communication in a WLAN supporting multi-link single radio (MLSR) or enhanced MLSR (EMLSR) operation. Background Art

[0002] Recently, with the popularity of mobile devices, wireless local area network technology that can provide fast wireless communication services to mobile devices has become a focus. Wireless local area network technology can be a technology that supports mobile devices (e.g., smart phones, smart tablets, laptops, portable multimedia players, embedded devices, etc.) to access the Internet in a wireless manner based on wireless communication technology.

[0003] The standards for using wireless local area network technology are mainly developed as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards. As the above-mentioned wireless local area network technology has been developed and widely adopted, the applications using wireless local area network technology have been diversified, and there has been a demand for wireless local area network technology that supports higher throughput. In a wireless local area network, a device can perform communication on multiple links. When a device operates on multiple links, its power consumption may increase. Therefore, a low-power communication technology for a device operating on multiple links may be required.

[0004] On the other hand, the technical writing in the background art of the present invention is to enhance the understanding of the background art of the present invention, and may include contents unknown to those of ordinary skill in the art to which the present invention belongs. Summary of the invention

[0005] Technical issues

[0006] The present invention is directed to providing a method and apparatus for low power communication in a wireless local area network supporting multi-link single radio (MLSR) or enhanced MLSR (EMLSR) operation.

[0007] Technical Solution

[0008] According to an exemplary embodiment of the present invention, a method of a station (STA) multi-link device (MLD) for achieving the above-mentioned purpose may include: performing power saving operations on a first link and a second link; when a first STA associated with STAMLD operates in an awake state on the first link, receiving a beacon frame from a first access point (AP) associated with AP MLD; performing a first communication with the first AP on the first link based on the beacon frame by the first STA; and after the first communication is completed, when a second STA associated with STAMLD operates in an awake state on the second link, performing a second communication with a second AP associated with AP MLD by the second STA associated with STAMLD.

[0009] The method may further include: sending a first frame to the AP MLD on one of the first link and the second link, the first frame including information indicating that the power saving operation is performed on the first link and information indicating that the power saving operation is performed on the second link.

[0010] The first frame may further include information indicating the level of power saving operation. When the first level of power saving operation is supported, the operating state of each of the first STA and the second STA may be an awake state or a doze state. When the second level of power saving operation is supported, the operating state of each of the first STA and the second STA may be an awake state or a deep sleep state.

[0011] The level of power saving operation performed on the first link may be different than the level of power saving operation performed on the second link.

[0012] The operation state of the first STA on the first link may be synchronized with the operation state of the second STA on the second link.

[0013] Performing the first communication may include: sending a power save (PS)-poll (Poll) frame for a beacon frame to the first AP on the first link by the first STA; receiving an initial control frame from the first AP on the first link by the first STA; sending a response frame for the initial control frame to the first AP on the first link by the first STA; and receiving a data frame from the first AP on the first link by the first STA.

[0014] In order to receive the initial control frame, the first STA may perform a listening operation on the first link, and the second STA may perform a listening operation on the second link.

[0015] Performing the first communication may include: sending, by the first STA, a PS-Poll frame for a beacon frame to the first AP on the first link; and receiving, by the first STA, a data frame from the first AP on the first link without receiving an initial control frame.

[0016] The PS-Poll frame may include information indicating an operation status of the first STA on the first link and information indicating an operation status of the second STA on the second link.

[0017] Performing the second communication may include: receiving an initial control frame from the second AP on the second link by the second STA; sending a response frame to the initial control frame to the second AP on the second link by the second STA; and receiving a data frame from the second AP on the second link by the second STA.

[0018] Performing the second communication may include: sending, by the second STA, a PS-Poll frame to the second AP on the second link; and receiving, by the second STA, a data frame from the second AP on the second link without receiving an initial control frame.

[0019] According to an exemplary embodiment of the present invention, a STA MLD for achieving the above-mentioned purpose may include: a processor, wherein the processor may enable the STA MLD to execute: performing power saving operations on a first link and a second link; receiving a beacon frame from a first access point (AP) associated with an AP MLD when a first STA associated with the STAMLD operates in an awake state on the first link; performing a first communication with a first AP on the first link based on the beacon frame by the first STA; and after the first communication is completed, when a second STA associated with the STA MLD operates in an awake state on the second link, performing a second communication with a second AP by the second STA associated with the STAMLD, the second AP being associated with the AP MLD.

[0020] The processor may further cause the STAMLD to execute: sending a first frame to the AP MLD on one of the first link and the second link, the first frame including information indicating that the power saving operation is performed on the first link and information indicating that the power saving operation is performed on the second link.

[0021] The first frame may further include information indicating the level of power saving operation. When the first level of power saving operation is supported, the operating state of each of the first STA and the second STA may be an awake state or a doze state. When the second level of power saving operation is supported, the operating state of each of the first STA and the second STA may be an awake state or a deep sleep state.

[0022] The level of power saving operation performed on the first link may be different than the level of power saving operation performed on the second link.

[0023] When executing the first communication, the processor can cause STAMLD to execute: the first STA sends a power save (PS)-poll (Poll) frame for a beacon frame to the first AP on the first link; the first STA receives an initial control frame from the first AP on the first link; the first STA sends a response frame for the initial control frame to the first AP on the first link; and the first STA receives a data frame from the first AP on the first link.

[0024] When performing the first communication, the processor may cause the STA MLD to execute: sending a PS-Poll frame for a beacon frame to the first AP on the first link by the first STA; and receiving a data frame from the first AP on the first link without receiving an initial control frame by the first STA.

[0025] The PS-Poll frame may include information indicating an operation status of the first STA on the first link and information indicating an operation status of the second STA on the second link.

[0026] When executing the second communication, the processor can cause STAMLD to execute: the second STA receives an initial control frame from the second AP on the second link; the second STA sends a response frame to the initial control frame to the second AP on the second link; and the second STA receives a data frame from the second AP on the second link.

[0027] When performing the second communication, the processor may cause STAMLD to execute: sending a PS-Poll frame to the second AP on the second link by the second STA; and receiving a data frame from the second AP on the second link by the second STA without receiving an initial control frame.

[0028] Beneficial Effects

[0029] According to the present invention, a device (e.g., a multi-link device (MLD), a station (STA), or an access point (AP)) can perform power saving operations on multiple links. For example, each STA associated with a STA MLD can operate in an awake state or a doze state. A STA operating in an awake state can communicate with the AP, while a STA operating in a doze state may not communicate with the AP. Through this power saving operation, the power consumption of the STA MLD can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a block diagram showing a first exemplary embodiment of a communication node constituting a wireless LAN system.

[0031] Figure 2 is a conceptual diagram showing a first exemplary embodiment of multi-links configured between multi-link devices (MLDs).

[0032] Figure 3a is a timing diagram illustrating a first exemplary embodiment of a method for configuring power saving operation in a wireless LAN supporting EMLSR operation.

[0033] Figure 3b is a timing diagram illustrating a second exemplary embodiment of a method for configuring a power saving operation in a wireless LAN supporting EMLSR operation.

[0034] Figure 4a is a timing diagram illustrating a first exemplary embodiment of a downlink communication method during power saving operation of an EMLSR MLD.

[0035] Figure 4b is a timing diagram illustrating a second exemplary embodiment of a downlink communication method during power saving operation of an EMLSR MLD.

[0036] Figure 5a is a timing diagram illustrating a third exemplary embodiment of a downlink communication method during a power saving operation of an EMLSR MLD.

[0037] Figure 5b is a timing diagram illustrating a fourth exemplary embodiment of a downlink communication method during a power saving operation of an EMLSR MLD.

[0038] Figure 6a is a timing diagram illustrating a first exemplary embodiment of a power saving operation of the EMLSR MLD.

[0039] Figure 6b is a timing diagram illustrating a second exemplary embodiment of the power saving operation of the EMLSR MLD.

[0040] Figure 6c is a timing diagram illustrating a third exemplary embodiment of the power saving operation of the EMLSR MLD. DETAILED DESCRIPTION

[0041] Since the present invention can be variously modified and has several forms, specific exemplary embodiments will be shown in the attached drawings and described in detail in the specific embodiments. However, it should be understood that this is not intended to limit the present invention to specific exemplary embodiments, on the contrary, the present invention is intended to cover all modifications and alternative forms falling within the spirit and scope of the present invention.

[0042] Relational terms such as first, second, etc. can be used to describe various elements, but these elements should not be limited by the terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present invention, the first component can be named as the second component, and the second component can also be similarly named as the first component. The term "and / or" means any one or a combination of multiple related and described matters.

[0043] In an exemplary embodiment of the present invention, "at least one of A and B" may mean "at least one of A or B" or "at least one of a combination of one or more of A and B". In addition, "one or more of A and B" may mean "one or more of A or B" or "one or more of a combination of one or more of A and B".

[0044] When it is mentioned that a certain component is "coupled" or "connected" to another component, it should be understood that the certain component is directly "coupled" or "connected" to the other component, or other components may be arranged between them. On the contrary, when it is mentioned that a certain component is "directly coupled" or "directly connected" to another component, it should be understood that no other components are arranged between them.

[0045] The terms used in the present invention are only used to describe specific exemplary embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "including" or "having" are intended to indicate the presence of features, values, steps, operations, components, parts, or combinations thereof described in the specification, but it should be understood that these terms do not exclude the presence or addition of one or more features, values, steps, operations, components, parts, or combinations thereof.

[0046] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as those generally understood by ordinary technicians in the field to which the present invention belongs. Terms that are commonly used and have appeared in dictionaries should be interpreted as having meanings that match the contextual meanings in the field. In this specification, unless explicitly defined, terms are not necessarily interpreted as having formal meanings.

[0047] Hereinafter, the form of the present invention will be described in detail with reference to the attached drawings. In describing the present invention, in order to facilitate a comprehensive understanding of the present invention, the same reference numerals refer to the same elements throughout the description of the drawings, and their repeated description will be omitted.

[0048] Hereinafter, a wireless communication system according to an exemplary embodiment of the present invention will be described. The wireless communication system according to the exemplary embodiment of the present invention is not limited to the content described below, and can be applied to various wireless communication networks according to the exemplary embodiment of the present invention. The wireless communication system can be referred to as a "wireless communication network".

[0049] In an exemplary embodiment, "configuration of an operation (e.g., a transmission operation)" may mean signaling "configuration information (e.g., information element, parameter) of an operation" and / or "information indicating execution of an operation". "Configuration of an information element (e.g., parameter)" may mean signaling an information element. "Configuration of a resource (e.g., a resource region)" may mean signaling setting information of a resource.

[0050] Figure 1 is a block diagram showing a first exemplary embodiment of a communication node constituting a wireless LAN system.

[0051] like Figure 1 As shown, the communication node 100 may be an access point, a station, an access point (AP) multi-link device (MLD), or a non-AP MLD. An access point may be referred to as an "AP", and a station may be referred to as a "STA" or a "non-AP STA". The operating channel width supported by the AP may be 20 megahertz (MHz), 80 MHz, 160 MHz, etc. The operating channel width supported by the STA may be 20 MHz, 80 MHz, etc.

[0052] The communication node 100 may include at least one processor 110, a memory 120, and a transceiver 130 connected to a network to perform communication. The transceiver 130 may be referred to as a transceiver, a radio frequency (RF) unit, an RF module, etc. In addition, the communication node 100 may further include an input interface device 140, an output interface device 150, a storage device 160, etc. The various components included in the communication node 100 may be connected to communicate with each other through a bus 170.

[0053] However, the respective components included in the communication node 100 may be connected through a separate interface or a separate bus centered around the processor 110 instead of the common bus 170. For example, the processor 110 may be connected to at least one of the memory 120, the transceiver 130, the input interface device 140, the output interface device 150, and the storage device 160 through a dedicated interface.

[0054] The processor 110 may execute program instructions stored in at least one of the memory 120 and the storage device 160. The processor 110 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor that executes a method according to an exemplary embodiment of the present invention. Each of the memory 120 and the storage device 160 may be configured as at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 120 may be configured with at least one of a read-only memory (ROM) and a random access memory (RAM).

[0055] Figure 2 is a conceptual diagram showing a first exemplary embodiment of multi-links configured between multi-link devices (MLDs).

[0056] like Figure 2 As shown, the MLD may have a media access control (MAC) address. In an exemplary embodiment, the MLD may refer to an AP MLD and / or a non-AP MLD. The MAC address of the MLD may be used in a multi-link establishment process between a non-AP MLD and an AP MLD. The MAC address of the AP MLD may be different from the MAC address of the non-AP MLD. The AP associated with the AP MLD may have a different MAC address, and the station associated with the non-AP MLD may have a different MAC address. Each AP with a different MAC address within the AP MLD may be responsible for each link and may function as an independent AP.

[0057] Each STA with a different MAC address within a non-AP MLD may be responsible for each link and may function as an independent STA. A non-AP MLD may be referred to as a STA MLD. An MLD may support simultaneous transmit and receive (STR) operations. In this case, the MLD may perform a transmit operation in link 1 and may perform a receive operation in link 2. An MLD that supports STR operations may be referred to as an STR MLD (e.g., STR AP MLD, STR non-AP MLD). In an exemplary embodiment, a link may mean a channel or a frequency band. A device that does not support STR operations may be referred to as a non-STR (NSTR) AP MLD or an NSTR non-AP MLD (or an NSTR STA MLD).

[0058] MLD can send and receive frames in multiple links by utilizing a non-contiguous bandwidth extension scheme (e.g., 80MHz+80MHz). Multi-link operation can include multi-band transmission. AP MLD can include multiple APs, and the multiple APs can operate in different links. Each of the multiple APs can perform the function of a lower MAC layer. Each of the multiple APs can be referred to as a "communication node" or a "lower entity". The communication node (i.e., AP) can be in the upper layer (or Figure 1 The non-AP MLD may include multiple STAs, and the multiple STAs may operate in different links. Each of the multiple STAs may be referred to as a "communication node" or a "lower entity". The communication node (i.e., STA) may be in an upper layer (or Figure 1 Operates under the control of the processor 110 shown.

[0059] MLD can perform communication in multiple frequency bands (i.e., multi-band). For example, MLD can perform communication using 80MHz bandwidth according to a channel extension scheme (e.g., bandwidth extension scheme) on the 2.4GHz band, and perform communication using 160MHz bandwidth according to a channel extension scheme on the 5GHz band. MLD can perform communication using 160MHz bandwidth in the 5GHz band, and can perform communication using 160MHz bandwidth in the 6GHz band. A frequency band (e.g., a channel) utilized by MLD can be defined as a link. Alternatively, multiple links can be configured in a frequency band utilized by MLD. For example, MLD can configure one link in the 2.4GHz band, and two links in the 6GHz band. Each link can be referred to as a first link, a second link, and a third link. Alternatively, each link can be referred to as link 1, link 2, link 3, etc. The link number can be set by the access point, and an identifier (identifier, ID) can be assigned to each link.

[0060] MLD (e.g., AP MLD and / or non-AP MLD) can configure multi-link by performing an access process and / or a negotiation process for multi-link operation. In this case, the number and / or links to be utilized in the multi-link can be configured. Non-AP MLD (e.g., STA) can identify information on a frequency band that can communicate with AP MLD. In the negotiation process of multi-link operation between non-AP MLD and APMLD, non-AP MLD can configure one or more links of the links supported by AP MLD for multi-link operation. A station that does not support multi-link operation (e.g., IEEE 802.11a / b / g / n / ac / ax STA) can be connected to one or more links of the multi-link supported by AP MLD.

[0061] When the frequency band spacing between multiple links (for example, the frequency band spacing between link 1 and link 2 in the frequency domain) is sufficient, the MLD may be able to perform the STR operation. For example, the MLD can use link 1 among the multiple links to send physical layer protocol data unit (PHY (physical) layer protocol data unit, PPDU) 1, and can use link 2 among the multiple links to receive PPDU2. On the other hand, if the MLD performs the STR operation when the frequency band spacing between multiple links is insufficient, in-device coexistence (IDC) interference, which is interference between multiple links, may occur. Accordingly, when the bandwidth spacing between multiple links is insufficient, the MLD may not be able to perform the STR operation. The link pair having the above-mentioned interference relationship may be a link pair with non-simultaneous transmit and receive (NSTR) restrictions. Here, the MLD may be referred to as an "NSTR AP MLD" or an "NSTR non-AP MLD."

[0062] For example, a multilink including link 1, link 2, and link 3 may be configured between the AP MLD and the non-AP MLD 1. When the frequency band interval between link 1 and link 3 is sufficient, the AP MLD may perform the STR operation using link 1 and link 3. That is, the AP MLD may send a frame using link 1 and receive a frame using link 3. When the frequency band interval between link 1 and link 2 is insufficient, the AP MLD may not be able to perform the STR operation using link 1 and link 2. When the frequency band interval between link 2 and link 3 is insufficient, the AP MLD may not be able to perform the STR operation using link 2 and link 3.

[0063] On the other hand, in a wireless local area network system, a negotiation process for multi-link operation can be performed in an access process between a station and an access point. A device (e.g., access point, station) supporting multiple links may be referred to as a "multi-link device (MLD)". An access point supporting multiple links may be referred to as an "AP MLD", and a station supporting multiple links may be referred to as a "non-AP MLD" or a "STA MLD". The AP MLD may have a physical address (e.g., a MAC address) for each link. The AP MLD may be implemented as if there is an AP responsible for each link alone. Multiple APs may be managed within one AP MLD. Therefore, coordination between multiple APs belonging to the same AP MLD is possible. The STA MLD may have a physical address (e.g., a MAC address) for each link. The STA MLD may be implemented as if there is an STA responsible for each link alone. Multiple STAs may be managed within one STA MLD. Therefore, coordination between multiple STAs belonging to the same STAMLD is possible.

[0064] For example, AP1 of AP MLD and STA1 of STA MLD may each be responsible for a first link and perform communication using the first link. AP2 of AP MLD and STA2 of STA MLD may each be responsible for a second link and perform communication using the second link. STA2 may receive state change information for the first link on the second link. In this case, STA MLD may collect information (e.g., state change information) received on each link and control an operation performed by STA1 based on the collected information.

[0065] Hereinafter, a data transmission and reception method in a wireless local area network system will be described. Even when describing a method (e.g., transmission or reception of a signal) performed at a first communication node among communication nodes, the corresponding second communication node may also perform a method (e.g., reception or transmission of a signal) corresponding to the method performed at the first communication node. That is, when describing the operation of an STA, an AP corresponding thereto may perform an operation corresponding to the operation of the STA. Conversely, when describing the operation of an AP, an STA corresponding thereto may perform an operation corresponding to the operation of the AP.

[0066] In an exemplary embodiment, the operation of STA may be interpreted as the operation of STAMLD, the operation of STAMLD may be interpreted as the operation of STA, the operation of AP may be interpreted as the operation of AP MLD, and the operation of AP MLD may be interpreted as the operation of AP. The STA of STA MLD may refer to the STA associated with STA MLD, and the AP of AP MLD may refer to the AP associated with AP MLD. When STAMLD includes a first STA operating on a first link and a second STA operating on a second link, the operation of STAMLD on the first link may be interpreted as the operation of the first STA, and the operation of STA MLD on the second link may be interpreted as the operation of the second STA. When AP MLD includes a first AP operating on the first link and a second AP operating on the second link, the operation of AP MLD on the first link may be interpreted as the operation of the first AP, and the operation of AP MLD on the second link may be interpreted as the operation of the second AP. In an exemplary embodiment, the transmission time of a frame may refer to the transmission start time or the transmission end time, and the reception time of a frame may refer to the reception start time or the reception end time. The transmission time may be interpreted as corresponding to the reception time. The time point may be interpreted as the time, and the time may be interpreted as the time point.

[0067] On the other hand, low power operation of a multi-link single radio (MLSR) MLD or an enhanced MLSR (EMLSR) MLD for operation on multiple links may be defined. In the present invention, the operation of the MLSR MLD may be interpreted as the operation of the EMLSR MLD, the operation of the EMLSR MLD may be interpreted as the operation of the MLSR MLD, and the low power operation may refer to a power saving operation.

[0068] STA MLD may support MLSR operation or EMLSR operation. A STAMLD supporting EMLSR operation may be referred to as EMLSRSTAMLD. A STA associated with an EMLSR STAMLD may be referred to as an EMLSR STA. AP MLD may support MLSR operation or EMLSR operation. An AP MLD supporting EMLSR operation may be referred to as an EMLSR AP MLD. An AP associated with an EMLSR AP MLD may be referred to as an EMLSR AP. In the present invention, EMLSR MLD may refer to EMLSR STAMLD and / or EMLSR AP MLD, STAMLD may refer to an EMLSR STA MLD supporting EMLSR operation, and AP MLD may refer to an EMLSR APMLD supporting EMLSR operation.

[0069] Among the APs associated with AP MLD 1, the AP operating on the first link may be referred to as AP 1-1 (e.g., the first AP), and the AP operating on the second link may be referred to as AP 1-2 (e.g., the second AP). Among the STAs associated with STAMLD 1, the STA operating on the first link may be referred to as STA1-1 (e.g., the first STA), and the STA operating on the second link may be referred to as STA 1-2 (e.g., the second STA).

[0070] Figure 3a is a timing diagram showing a first exemplary embodiment of a method for configuring a power saving operation in a wireless local area network supporting EMLSR operation, Figure 3b is a timing diagram illustrating a second exemplary embodiment of a method for configuring a power saving operation in a wireless LAN supporting EMLSR operation.

[0071] like Figure 3a and Figure 3b As shown, the STA MLD may send an action frame (e.g., an extremely high throughput (EHT) action frame) including power saving information to the AP MLD. The AP MLD may receive the action frame from the STA MLD and identify the power saving information included in the action frame. The fields, subfields, information elements and / or indicator bits included in the action frame may represent the power saving information. Alternatively, the STA MLD may send a data frame (e.g., an uplink data frame) or a quality of service (QoS) empty frame including power saving information to the AP MLD. The AP MLD may receive a data frame or a QoS empty frame from the STAMLD and identify the power saving information included in the data frame or the QoS empty frame. The power saving information may be included in the A-control form of the high throughput (HT) control field in the MAC header of the data frame or the QoS empty frame. In other words, the A-control field of the HT control field in the MAC header included in the data frame or the QoS empty frame may include the power saving information. The A-control field may be a variant of the HT control field.

[0072] The power saving information transmitted on the first link may be power saving information for the second link. The power saving information transmitted on the second link may be power saving information for the first link. The power saving information may include link-specific power saving information. For example, the power saving information may include information indicating whether a power saving operation is performed on the first link and information indicating whether a power saving operation is performed on the second link. In other words, the power saving information transmitted by the STAMLD on one of the first link and the second link may include information indicating whether a power saving operation is performed on the first link and information indicating whether a power saving operation is performed on the second link. In order to indicate link-specific power saving information, the power saving information may include a link bitmap and / or a link indicator. The link indicator may be a link ID.

[0073] Action frames (e.g., EHT action frames), data frames, and QoS empty frames including power saving information may be referred to as power saving indication frames. For example, STAMLD 1 (e.g., STA1-1) may send a power saving indication frame indicating a power saving operation (e.g., power saving mode, power saving state) of a second link to AP MLD 1 (e.g., AP 1-1) on a first link. The power saving indication frame sent by STAMLD 1 (e.g., STA1-1) on a first link may include information indicating that STAMLD 1 (e.g., STA1-2) performs a power saving operation on a second link. The power saving indication frame may include a power saving mode (PM). A PM set to a first value (e.g., 0) may indicate that a power saving operation is not performed. A PM set to a second value (e.g., 1) may indicate that a power saving operation is performed. If a power saving operation is not performed on the second link, STA 1-2 may always operate in an awake state. If a power saving operation is performed on the second link, STA 1-2 may operate in an awake state or a doze state.

[0074] The AP MLD 1 may receive a power saving indication frame from the STA MLD 1 on the first link, and based on information included in the power saving indication frame, the AP MLD 1 may determine that the STA MLD 1 performs a power saving operation on the first link and / or on the second link. In this case, the AP MLD 1 may perform communication (e.g., downlink communication) for the STA MLD 1 in consideration of the power saving operation of the STA MLD 1. The downlink communication of the AP MLD 1 may include a bufferable unit (BU) transmission operation of the AP MLD 1, an automatic power save delivery (APSD) transmission operation, and the like.

[0075] When STA MLD 1 performs a power saving operation, the EMLSR operation may be modified or suspended. STA MLD 1 may be an EMLSR STAMLD that performs an EMLSR operation on both the first link and the second link. In other words, both the first link and the second link may be EMLSR links. STA MLD 1 may send a power saving indication frame including information indicating that STA MLD1 performs a power saving operation on the second link to AP MLD 1 on the first link. AP MLD 1 may receive the power saving indication frame from STAMLD 1, and based on the information included in the power saving indication frame, AP MLD 1 may determine that STA 1-2 performs a power saving operation on the second link. Accordingly, AP MLD 1 may perform a BU storage operation and / or an APSD operation on STA 1-2.

[0076] In addition, AP MLD 1 may modify the EMLSR operation (e.g., the EMLSR operation for STA MLD 1). In other words, AP MLD 1 may determine that STA MLD 1 does not perform the EMLSR operation. In this case, AP MLD 1 may send a data frame (e.g., a downlink frame) to STA MLD 1 on the first link and / or the second link without sending an initial control frame (e.g., a multi-user request to send (MU-RTS) trigger frame or a buffer status report poll (BSRP) trigger frame).

[0077] Figure 4a is a timing diagram showing a first exemplary embodiment of a downlink communication method during power saving operation of an EMLSR MLD, Figure 4b is a timing diagram illustrating a second exemplary embodiment of a downlink communication method during power saving operation of an EMLSR MLD.

[0078] like Figure 4a and Figure 4b As shown, STAMLD 1 can perform power saving operations on multiple links. Each STA associated with STA MLD 1 can operate in an awake state for sending and receiving frames. In other words, the STA can operate in an awake state during the frame sending and receiving period. Outside the frame sending and receiving period, the STA can operate in a doze state or an awake state as needed. In the awake state, the STA (e.g., STA MLD) may be able to send and receive frames. In the doze state, the STA (e.g., STAMLD) may not be able to send or receive frames.

[0079] STA MLD 1 may perform power saving operations on the first link and / or the second link. STA MLD 1 may operate in an awake or doze state according to a specific period to receive a beacon frame. STA MLD 1 may receive a beacon frame from AP MLD1 on the first link and identify a traffic indication map (TIM) included in the beacon frame. Based on the TIM, STA MLD 1 may determine that there is downlink traffic (e.g., BU) to be received by STA MLD 1 on the first link and / or the second link. If there is a BU to be received by STA MLD 1 on the first link, STA1-1 of STA MLD 1 may send a power saving (PS)-poll (Poll) frame to AP 1-1. The PS-Poll frame of STA 1-1 may be sent to indicate that STA 1-1 wishes to receive a BU on the first link.

[0080] STA MLD 1 may perform EMLSR operations on both the first link and the second link, and the first link and the second link may be EMLSR links.

[0081] exist Figure 4a In the exemplary embodiment shown, AP 1-1 can receive a PS-Poll frame from STA 1-1 and send a reception response frame to STA 1-1 in response to the PS-Poll frame. In the present invention, the reception response frame can be an acknowledgment (ACK) frame or a block ACK (BA) frame. STA 1-1 can receive a reception response frame for a PS-Poll frame from AP 1-1. Upon receiving the reception response frame of AP 1-1, STA MLD 1 can perform a listening operation on both the first link and the second link. STAMLD 1 can be an EMLSR STA MLD. STA MLD 1 can perform a listening operation on a link (e.g., a first link) to which a PS-Poll frame has been sent until a reception operation for at least one BU begins. The listening operation can be performed to receive an initial control frame and / or a data frame.

[0082] During the listening operation (which is performed until the BU reception operation starts), STA MLD 1 may refrain from sending an uplink frame (e.g., a PS-Poll frame, a data frame, etc.) to AP MLD 1 on another link (e.g., the second link). After sending a reception response frame for a PS-Poll frame for STAMLD 1 (e.g., STA1-1), AP MLD 1 may initiate an EMLSR transmission process for BU transmission by sending an initial control frame (e.g., a MU-RTS trigger frame) on a link (e.g., the first link) on which the PS-Poll frame has been received. The initial control frame may be used for EMLSR operation. STA 1-1 may perform a listening operation on the first link to receive an initial control frame and / or a data frame, and STA1-2 may perform a listening operation on the second link to receive an initial control frame and / or a data frame.

[0083] STA 1-1 may receive an initial control frame (e.g., a MU-RTS trigger frame) from AP 1-1, and send a clear to send (CTS) frame to AP 1-1 after a short inter-frame space (SIFS) from the reception time of the initial control frame. AP 1-1 may receive a CTS frame from STA 1-1, and send a BU (e.g., a data frame including a BU) to STA 1-1 after SIFS from the reception time of the CTS frame. STA 1-1 may receive a BU from AP 1-1, and send a reception response frame for the BU to AP 1-1 after SIFS from the reception time of the BU. AP 1-1 may receive a reception response frame for the BU from STA 1-1.

[0084] The transmission of an uplink frame (e.g., a PS-Poll frame, a data frame, etc.) on another link (e.g., a second link) may be performed after the BU send / receive operation on the first link is completed. The BU send / receive operation may include a send / receive operation for a reception response frame of the BU. Alternatively, the transmission of an uplink frame on another link (e.g., a second link) may be possible after the EMLSR conversion delay from the completion time of the BU send / receive operation on the first link. The EMLSR conversion delay may be applied after "aSIFSTime+aSlotTime+aRxPHYStartDelay" from the completion time of the BU send / receive operation on the first link. In other words, it may be possible to send an uplink frame on another link after "aSIFSTime+aSlotTime+aRxPHYStartDelay+EMLSR conversion delay" from the completion time of the BU send / receive operation on the first link.

[0085] Since STA MLD 1 is an EMLSR STA MLD, STAMLD 1 may suppress the transmission operation of uplink frames (e.g., PS-Poll frames, data frames, etc.) on the second link until a BU is received on the first link on which the PS-Poll frame has been sent. AP 1-1 of AP MLD 1 may perform a BU transmission operation after sending an initial control frame (e.g., MU-RTS trigger frame) to STA 1-1. STAMLD 1 may convert the state of the first link from the listening state to the normal state, and may receive a BU from AP MLD 1 in the normal state. In the listening state, STAMLD 1 may perform a listening operation, and in the normal state, STA MLD 1 may perform a normal sending / receiving operation. Converting the state of the first link to the listening state or the normal state may mean that the state (e.g., the operating state) of STA 1-1 operating on the first link is converted to the listening state or the normal state. Converting the state of the second link to the listening state or the normal state may mean that the state (e.g., the operating state) of STA1-2 operating on the second link is converted to the listening state or the normal state.

[0086] STA 1-1 may send a reception response frame (e.g., an ACK frame or a BA frame) for the BU to AP 1-1. After the reception operation of the BU on the first link is completed, STA MLD 1 may convert the state of the second link to a listening state or a normal state. From the time when the state of the second link is converted to the listening state or the normal state, STA 1-2 may perform a channel sensing operation during the MediumSyncDelay time without sending a frame. MediumSyncDelay may be referred to as a medium synchronization delay, a medium delay, or a synchronization delay. The MediumSyncDelay time may be a timer. If a network allocation vector (NAV) is set within the MediumSyncDelay timer, the MediumSyncDelay timer may be released. After the MediumSyncDelay time, STA1-2 may send a PS-Poll frame to AP 1-2 to receive the BU. AP 1-2 may receive the PS-Poll frame from STA 1-2 and send a data frame including the BU to STA 1-2. STA 1-2 may receive a data frame from AP 1-2.

[0087] Alternatively, after the MediumSyncDelay time, STA 1-2 may send an uplink frame (e.g., a data frame) to AP 1-2. AP 1-2 may receive the uplink frame from STA 1-2 and send a reception response frame for the uplink frame to STA 1-2. STA 1-2 may receive a reception response frame for the uplink frame from AP 1-2. As another method, STA 1-2 may send an RTS frame to AP 1-2 within the MediumSyncDelay time. AP 1-2 may receive an RTS frame from STA 1-2 and send a CTS frame to STA 1-2 in response to the RTS frame. Upon receiving the CTS frame from AP 1-2, STA 1-2 may send an uplink frame (e.g., a PS-Poll frame, a data frame, etc.) to AP 1-2.

[0088] exist Figure 4b In the illustrated embodiment, STA1-1 may send a PS-Poll frame to AP 1-1. AP 1-1 may receive the PS-Poll frame from STA1-1 and send a BU (e.g., a data frame including the BU) to STA1-1 in response to the PS-Poll frame. STA1-1 may receive the BU from AP 1-1 and send a reception response frame for the BU to AP 1-1. When the reception operation of the BU is completed on the first link, STA MLD 1 may convert the state of the second link to a listening state or a normal state. In other words, STA 1-2 may perform a listening operation or a normal transmission / reception operation.

[0089] STA 1-2 may perform a channel sensing operation without sending a frame during the MediumSyncDelay time from the time when the state of the second link is converted to the listening state or the normal state. After the MediumSyncDelay time, STA 1-2 may send a PS-Poll frame to AP 1-2 to receive a BU. AP 1-2 may receive the PS-Poll frame from STA 1-2 and send a data frame including a BU to STA 1-2. STA 1-2 may receive a data frame from AP 1-2.

[0090] Alternatively, after the MediumSyncDelay time, STA 1-2 may send an uplink frame (e.g., a data frame) to AP 1-2. AP 1-2 may receive the uplink frame from STA 1-2 and send a reception response frame for the uplink frame to STA 1-2. STA 1-2 may receive a reception response frame for the uplink frame from AP 1-2. As another method, STA 1-2 may send an RTS frame to AP 1-2 within the MediumSyncDelay time. AP 1-2 may receive an RTS frame from STA 1-2 and send a CTS frame to STA 1-2 in response to the RTS frame. If a CTS frame is received from AP 1-2, STA 1-2 may send an uplink frame (e.g., a PS-Poll frame, a data frame, etc.) to AP 1-2.

[0091] Figure 5a is a timing diagram showing a third exemplary embodiment of a downlink communication method during power saving operation of an EMLSR MLD, Figure 5b is a timing diagram illustrating a fourth exemplary embodiment of a downlink communication method during a power saving operation of an EMLSR MLD.

[0092] like Figure 5a and Figure 5b As shown, STAMLD 1 can perform power saving operations on multiple links. Each STA associated with STA MLD 1 can operate in an awake state for sending and receiving frames. In other words, the STA can operate in an awake state during the frame sending and receiving period. Outside the frame sending and receiving period, the STA can operate in a doze state or an awake state as needed. In the awake state, the STA (e.g., STA MLD) may be able to send and receive frames. In the doze state, the STA (e.g., STA MLD) may not be able to send or receive frames.

[0093] STA MLD 1 may perform EMLSR operations on both the first link and the second link, and the first link and the second link may be EMLSR links.

[0094] STA MLD 1 may perform power saving operations on the first link and / or the second link. STA MLD 1 may operate in an awake or doze state according to a specific period to receive a beacon frame. STAMLD 1 may receive a beacon frame from AP MLD 1 on the first link and identify a TIM and / or a multi-link service indication element included in the beacon frame. TIM may be a bitmap indicating an association identifier (AID). The multi-link service indication element may be a link bitmap associated with an AID corresponding to a bit set to 1 in the TIM. The link bitmap may be configured for the AID. Based on the TIM and / or the multi-link service indication element, STA MLD 1 may identify that a downlink service (e.g., BU) to be received by STAMLD 1 exists on the first link and / or the second link. If there is a BU to be received by STA MLD 1 on the first link, STA1-1 of STAMLD1 may send a PS-Poll frame to AP 1-1. The PS-Poll frame of STA1-1 may be sent to inform the STAs that the MLD (eg, STA1-1 and STA1-2) wishes to receive BUs on multiple links (eg, a first link and a second link).

[0095] In other words, the PS-Poll frame sent on the first link belonging to the EMLSR link may indicate not only the power management state (e.g., awake state) of the first link, but also the power management state (e.g., awake state) of another link (e.g., second link) belonging to the EMLSR link. The power management state may refer to the operating state of the STA. The state in which the first link is in the awake state may mean that STA 1-1 is able to receive a BU on the first link. The state in which the second link is in the awake state may mean that STA 1-2 is able to receive a BU on the second link. The PS-Poll frame sent by STA MLD 1 (e.g., STA 1-1) to AP MLD 1 (e.g., AP 1-1) may be a conventional PS-Poll frame used in a wireless local area network. Alternatively, the PS-Poll frame sent by STAMLD 1 (e.g., STA 1-1) to AP MLD 1 (e.g., AP 1-1) may be a multi-link (multi-link, ML) PS-Poll frame indicating multiple links. As another method, the PS-Poll frame sent on the first link may indicate the PM bit of the first link and / or the second link. For example, the PS-Poll frame may indicate the PM bit of the second link. If the PM bit is set to 0, STA1-2 may always operate in the awake state on the second link. If the PM bit is set to 1, STA 1-2 may operate in the awake state or the doze state on the second link.

[0096] exist Figure 5a In the exemplary embodiment shown, STA 1-1 may send a PS-Poll frame to AP 1-1. AP 1-1 may receive the PS-Poll frame from STA 1-1. Upon receiving the PS-Poll frame from STA 1-1, AP 1-1 may determine that STA 1-1 is capable of receiving BUs on multiple links (e.g., a first link and a second link). AP 1-1 may send a BU (e.g., a data frame including a BU) to STA 1-1 in response to the PS-Poll frame. STA 1-1 may receive the BU from AP 1-1 and send a reception response frame for the BU to AP 1-1.

[0097] When the receiving operation of the BU is completed on the first link, the STA 1-2 of the STAMLD 1 may operate in the awake state on the second link during the transition delay time (e.g., EMLSR transition delay period) from the completion time of the receiving operation of the BU on the first link to the receiving BU on the second link. The EMLSR transition delay may be applied after "aSIFSTime+aSlotTime+aRxPHYStartDelay" from the completion time of the BU sending / receiving operation on the first link. In other words, it may be possible to send an uplink frame on another link after "aSIFSTime+aSlotTime+aRxPHYStartDelay+EMLSR transition delay" from the completion time of the BU sending / receiving operation on the first link.

[0098] After the completion time of the BU reception operation on the first link, STAMLD 1 may convert the state of the second link to the normal state. The state (e.g., operation state) of STA 1-2 may be converted to the normal state, and STA 1-2 operating in the normal state may perform a channel sensing operation without sending a frame during the MediumSyncDelay period. The MediumSyncDelay time may be a timer. If NAV is set within the MediumSyncDelay timer, the MediumSyncDelay timer may be released.

[0099] STA1-2 may receive a BU from AP 1-2 on the second link without an initial control frame. Here, AP 1-2 may send a BU on the second link after the EMLSR conversion delay time from the reception time of the reception response frame of STA1-1. As another method, STA 1-2 may receive an initial control frame (e.g., a MU-RTS trigger frame) from AP 1-2 on the second link. Here, AP 1-2 may send an initial control frame on the second link after the EMLSR conversion delay time from the reception time of the reception response frame of STA 1-1. STA 1-2 may send a response frame (e.g., a CTS frame) to AP 1-2 in response to the initial control frame, and receive a BU from AP 1-2. STA 1-2 may send a reception response frame for the BU to AP 1-2.

[0100] exist Figure 5b In the exemplary embodiment shown, STA1-1 can send a PS-Poll frame to AP 1-1. AP 1-1 can receive a PS-Poll frame from STA1-1. Upon receiving the PS-Poll frame of STA 1-1, AP 1-1 can determine that STA MLD1 (e.g., STA1-1 and STA1-2) can receive BUs on multiple links (e.g., a first link and a second link). AP 1-1 can send a reception response frame for the PS-Poll frame to STA1-1. STA 1-2 of STA MLD 1 can be converted to an awake state within the EMLSR conversion delay time from the reception time of the reception response frame of AP 1-1. After completing the PS-Poll frame transmission operation on the first link and / or the reception response frame reception operation for the PS-Poll frame, STA MLD 1 can perform a listening operation on the first link and the second link to receive BUs on the two links. In other words, STA1-1 can operate in a listening state on the first link, and STA 1-2 can operate in a listening state on the second link.

[0101] STA 1-2 may perform a channel sensing operation without sending a frame during the MediumSyncDelay time from the time of transition to the listening state on the second link. The MediumSyncDelay time may be a timer. If NAV is set within the MediumSyncDelay timer, the MediumSyncDelay timer may be released. AP1-2 of AP MLD 1 may send an initial control frame (e.g., a MU-RTS trigger frame) to STA 1-2. Here, AP 1-2 may send an initial control frame on the second link after the EMLSR transition delay from the reception time of the reception response frame of STA1-1. STA 1-2 may receive the initial control frame from AP 1-2. Upon receiving the initial control frame from AP 1-2, the state (e.g., operating state) of STA 1-2 may be transitioned from the listening state to the normal state. STA1-2 may send a response frame (e.g., a CTS frame) to AP 1-2 in response to the initial control frame. AP 1-2 may receive a CTS frame from STA 1-2 and send a BU to STA1-2. STA1-2 may receive the BU from AP 1-2 and transmit a reception response frame for the BU to AP 1-2. AP 1-2 may receive the reception response frame for the BU from STA 1-2.

[0102] After receiving the BU on the second link, STA MLD 1 may perform listening operations on both the first link and the second link to receive additional BUs from AP MLD 1. In other words, STA 1-1 may operate in a listening state on the first link, and STA 1-2 may operate in a listening state on the second link.

[0103] Figure 6a is a timing diagram showing a first exemplary embodiment of the power saving operation of the EMLSR MLD, Figure 6b is a timing diagram showing a second exemplary embodiment of the power saving operation of the EMLSR MLD, Figure 6c is a timing diagram illustrating a third exemplary embodiment of the power saving operation of the EMLSR MLD.

[0104] like Figures 6a to 6cAs shown, the STA associated with STAMLD 1 can operate in a deep sleep state. The STA operating in a deep sleep state may not receive beacon frames. For example, if STA1-2 operates in a deep sleep state on the second link, STA 1-2 may not perform a beacon frame reception operation on the second link. In the deep sleep state, STA1-2 may not perform communication. The power consumption in the deep sleep state may be lower than the power consumption in the doze state. When a link indication is received on a link other than the second link (e.g., the first link), or when an uplink frame is sent on a link other than the second link (e.g., the first link), the state of STA1-2 on the second link (e.g., the operating state) may be converted from a deep sleep state to a wake-up state. STA1-2 operating in an awake state on the second link may perform frame sending and receiving operations.

[0105] A frame including information about the power management state of each STA associated with the STA MLD may be sent. The power management state may indicate a power saving level. Information about the power management state may be included in the A-control form of the HT control field in the MAC header of the frame. In other words, the A-control field of the HT control field in the MAC header of the frame may include information about the power management state. The power management state may be indicated by a power saving level bit (e.g., an additional power saving level bit). The power saving level bit may be 2 bits and may be set as shown in Table 1 below.

[0106] [Table 1]

[0107]

[0108] The power saving level may refer to the level of power saving operation. In the first power saving level (e.g., level 1 of power saving operation), the STA (e.g., STAMLD) may not perform power saving operation. In the second power saving level (e.g., level 2 of power saving operation), the STA may operate in an awake state or a doze state. In the third power saving level (e.g., level 3 of power saving operation), the STA may operate in an awake state or a deep sleep state. In the fourth power saving level (e.g., level 4 of power saving operation), the STA may not support the awake state. In Figure 3a and / or Figure 3b In an exemplary embodiment of, information about the power saving level (e.g., the power saving level bit) may be included in a power saving indication frame (e.g., an action frame, a data frame). The same power saving level may be applied to multiple links. Alternatively, different power saving levels may be applied to multiple links. For example, a second power saving level may be applied on a first link, and a third power saving level may be applied on a second link.

[0109] exist Figure 6aIn an exemplary embodiment of the present invention, the link-specific power saving states of STA MLD 1 can be synchronized. If STAMLD 1 is an EMLSR STAMLD, STA MLD 1 can include a single radio device. In this case, when the power saving states are synchronized across links (e.g., EMLSR links), the power saving effect can be increased. The power saving states of STA1-1 and STA1-2 associated with STAMLD 1 can be synchronized. STA1-1 can operate in a doze state or a wake-up state. When STA1-1 operates in a doze state, STA1-2 can operate in a deep sleep state (or doze state). The start time and / or end time of the period in which STA1-1 operates in the doze state can be the same as the start time and / or end time of the period in which STA1-2 operates in the deep sleep state. When STA 1-1 operates in a wake-up state, STA 1-2 can also operate in a wake-up state. The start time and / or end time of the period in which STA1-1 operates in the wake-up state can be the same as the start time and / or end time of the period in which STA 1-2 operates in the wake-up state.

[0110] STA MLD 1 may transition between power saving states according to a specific cycle (e.g., a specific time period). For example, STA 1-1 may perform transitions "doze state→wake-up state" and / or "wake-up state→doze state" according to a specific cycle. STA1-2 may perform transitions "deep sleep state→wake-up state" and / or "wake-up state→deep sleep state" according to a specific cycle. The specific cycle may be a cycle pre-agreed between STA MLD 1 and AP MLD 1. The specific cycle may be a beacon frame cycle. Alternatively, the specific cycle may be a multiple of the beacon frame cycle.

[0111] exist Figure 6bIn an exemplary embodiment of the present invention, the link-specific power saving states of STA MLD 1 may not be synchronized. The power saving states of STA 1-1 and STA 1-2 associated with STA MLD 1 may not be synchronized. The power saving level and / or the transition period of the power saving state may be independently configured on each link. The power saving level on the first link may be different from the power saving level on the second link. The transition period of the power saving state on the first link may be different from the transition period of the power saving state on the second link. For example, STA1-1 may perform the transition "doze state→wake-up state" and / or "wake-up state→doze state" according to the first cycle. STA 1-2 may perform the transition of "deep sleep state→wake-up state" and / or "wake-up state→deep sleep state" according to the second cycle. The first cycle and / or the second cycle may be a cycle pre-agreed between STA MLD 1 and AP MLD 1. The first cycle and / or the second cycle may be a beacon frame cycle. Alternatively, the specific cycle may be a multiple of the beacon frame cycle.

[0112] exist Figure 6c In an exemplary embodiment of , STA 1-1 may operate in an awake state or a doze state, and STA 1-2 may operate in an awake state or a deep sleep state. When specific information (e.g., a TIM included in a beacon frame) is received on a first link, the state of STA1-2 on a second link (e.g., an operation state) may be converted from a deep sleep state to an awake state. For example, STA1-1 of STAMLD 1 may receive a beacon frame from AP 1-2 and identify the TIM included in the beacon frame. If the TIM indicates the use of the second link or if the TIM indicates the presence of a BU to be transmitted on the second link, STA 1-2 of STAMLD 1 may be converted from a deep sleep state to an awake state, and perform additional operations to receive a BU from AP MLD 1 (e.g., AP 1-2). As another method, STAMLD 1 may be referred to as AP MLD 2, and APMLD 1 may be referred to as STAMLD 2. In other words, STA MLD 1 may operate as an AP MLD, and AP MLD 1 may operate as a STAMLD (non-AP MLD). When AP MLD 2 operates in the awake state on the first link, it can operate in the deep sleep state or doze state on the second link. If AP MLD 2 receives a frame from STA MLD 2 on the first link (for example, if AP MLD 2 receives specific information requesting to use the second link), AP MLD 2 can operate in the awake state on the second link, and AP MLD 2 and STA MLD 2 can perform communication operations on both the first link and the second link.

[0113] The operation of the method according to the exemplary embodiment of the present invention can be implemented as a computer-readable program or code in a computer-readable recording medium. The computer-readable recording medium may include a recording device of all types having data that can be read by a computer system. In addition, the computer-readable recording medium can store and execute programs or codes, which can be distributed in a computer system connected via a network and read by a computer in a distributed manner.

[0114] Computer readable recording media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM or flash memory. Program instructions may include not only machine language codes created by a compiler, but also high-level language codes that can be executed by a computer using an interpreter.

[0115] Although some aspects of the present invention have been described in the context of a device, these aspects may indicate the corresponding description according to the method, and a block or device may correspond to the step of the method or the feature of the step. Similarly, the aspects described in the context of the method may be represented as the feature of a corresponding block or project or a corresponding device. Some or all steps of the method may be performed by (or using) a hardware device such as a microprocessor, a programmable computer or an electronic circuit. In some embodiments, one or more of the most important steps of the method may be performed by such a device.

[0116] In some exemplary embodiments, a programmable logic device such as a field programmable gate array can be used to perform some or all of the functions of the methods described herein. In some exemplary embodiments, the field programmable gate array can be operated with a microprocessor to perform one of the methods described herein. Typically, the method is preferably performed by a specific hardware device.

[0117] The description of the present invention is merely exemplary in nature, and therefore variant forms that do not deviate from the essence of the present invention are intended to be within the scope of the present invention. Such variant forms should not be considered as departing from the spirit and scope of the present invention. Therefore, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A method of a station (STA) multi-link device (MLD), comprising: performing a power saving operation on the first link and the second link; When a first STA associated with the STA MLD operates in an awake state on a first link, receiving a beacon frame from a first access point (AP) associated with the AP MLD; Performing, by the first STA, a first communication with the first AP on the first link based on the beacon frame; as well as After the first communication is completed, when the second STA associated with the STA MLD operates in an awake state on the second link, a second communication with a second AP associated with the AP MLD is performed by the second STA associated with the STA MLD.

2. The method according to claim 1, further comprising: A first frame is transmitted to the APMLD on one of the first link and the second link, the first frame including information indicating that a power saving operation is performed on the first link and information indicating that a power saving operation is performed on the second link.

3. The method according to claim 2, wherein: The first frame further includes information indicating a level of power saving operation, when the first level of power saving operation is supported, the operating state of each of the first STA and the second STA is an awake state or a doze state, and when the second level of power saving operation is supported, the operating state of each of the first STA and the second STA is an awake state or a deep sleep state.

4. The method according to claim 3, wherein: The level of power saving operation performed on the first link is different from the level of power saving operation performed on the second link.

5. The method according to claim 3, wherein: An operation state of the first STA on the first link is synchronized with an operation state of the second STA on the second link.

6. The method according to claim 1, wherein: Performing the first communication includes: The first STA sends a power save (PS)-Poll frame for the beacon frame to the first AP on the first link; Receiving, by the first STA, an initial control frame from the first AP on the first link; The first STA sends a response frame to the initial control frame to the first AP on the first link; and A data frame is received by a first STA from a first AP on a first link.

7. The method according to claim 6, wherein: In order to receive the initial control frame, the first STA performs a listening operation on the first link, and the second STA performs a listening operation on the second link.

8. The method according to claim 1, wherein: Performing the first communication includes: The first STA sends a PS-Poll frame for the beacon frame to the first AP on the first link; and A data frame is received by the first STA from the first AP on the first link without receiving an initial control frame.

9. The method according to claim 8, wherein: The PS-Poll frame includes information indicating an operation status of the first STA on the first link and information indicating an operation status of the second STA on the second link.

10. The method according to claim 1, wherein: Performing the second communication includes: Receiving, by the second STA, an initial control frame from the second AP on the second link; The second STA sends a response frame to the initial control frame to the second AP on the second link; and A data frame is received by the second STA from the second AP on the second link.

11. The method according to claim 1, wherein: Performing the second communication includes: The second STA sends a PS-Poll frame to the second AP on the second link; and The data frame is received by the second STA from the second AP on the second link without receiving the initial control frame.

12. A station (STA) multi-link device (MLD), comprising a processor, wherein the processor causes the STA MLD to perform: performing a power saving operation on the first link and the second link; When a first STA associated with the STA MLD operates in an awake state on a first link, receiving a beacon frame from a first access point (AP) associated with the AP MLD; Performing, by the first STA, a first communication with the first AP on the first link based on the beacon frame; as well as After the first communication is completed, when the second STA associated with the STA MLD operates in an awake state on the second link, a second communication with a second AP associated with the AP MLD is performed by the second STA associated with the STA MLD.

13. The STA MLD according to claim 12, wherein: The processor further causes the STA MLD to execute: sending a first frame to the AP MLD on one of the first link and the second link, the first frame including information indicating that the power saving operation is performed on the first link and information indicating that the power saving operation is performed on the second link.

14. The STA MLD according to claim 13, wherein: The first frame further includes information indicating a level of power saving operation, when the first level of power saving operation is supported, the operating state of each of the first STA and the second STA is an awake state or a doze state, and when the second level of power saving operation is supported, the operating state of each of the first STA and the second STA is an awake state or a deep sleep state.

15. The STA MLD according to claim 14, wherein: The level of power saving operation performed on the first link is different from the level of power saving operation performed on the second link.

16. The STA MLD according to claim 12, wherein: When performing the first communication, the processor causes the STA MLD to execute: The first STA sends a power save (PS)-Poll frame for the beacon frame to the first AP on the first link; Receiving, by the first STA, an initial control frame from the first AP on the first link; The first STA sends a response frame to the initial control frame to the first AP on the first link; as well as A data frame is received by a first STA from a first AP on a first link.

17. The STA MLD according to claim 12, wherein: When performing the first communication, the processor causes the STA MLD to execute: The first STA sends a PS-Poll frame for the beacon frame to the first AP on the first link; as well as A data frame is received by the first STA from the first AP on the first link without receiving an initial control frame.

18. The STA MLD according to claim 17, wherein: The PS-Poll frame includes information indicating an operation state of the first STA on the first link and information indicating an operation state of the second STA on the second link.

19. The STA MLD according to claim 12, wherein: When performing the second communication, the processor causes the STA MLD to execute: Receiving, by the second STA, an initial control frame from the second AP on the second link; The second STA sends a response frame to the initial control frame to the second AP on the second link; as well as A data frame is received by the second STA from the second AP on the second link.

20. The STA MLD according to claim 12, wherein: When performing the second communication, the processor causes the STA MLD to execute: The second STA sends a PS-Poll frame to the second AP on the second link; as well as The data frame is received by the second STA from the second AP on the second link without receiving the initial control frame.

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