Method and apparatus for switching to power saving mode in wireless LAN multi-link

Abstract

In a wireless LAN system, a method performed by a first MLD including a first STA associated with a first link and a second STA associated with a second link comprises the steps of: connecting to a second MLD performing multi-link communication; transmitting, by the first MLD to the second MLD, a first frame on a first link activated for the first STA of the first MLD, wherein the first frame indicates whether to switch to an activation state of the second link; and if the first frame indicates activation of the second link, performing, by the first MLD, frame exchange with the second MLD on the activated first link and second link.

Description

Method and device for switching to power saving mode in wireless LAN multi-link

[0001] The present disclosure relates to a method and apparatus for a wireless LAN terminal supporting multiple links in a wireless local area network to perform data communication by switching to a power-saving mode. Additionally, the present disclosure relates to a method and apparatus for multi-link dynamic low-power operation in a wireless LAN.

[0002]

[0003] With the recent expansion of mobile device adoption, Wireless Local Area Network (WLAN) technology, capable of providing fast wireless communication services to these devices, is receiving significant attention. Based on short-range wireless communication technology, WLAN technology enables mobile devices such as smartphones, smart pads, laptop computers, portable multimedia players, and embedded devices to connect to the internet wirelessly.

[0004] Standards using wireless LAN technology are primarily developed by the IEEE (Institute of Electrical and Electronics Engineers) as the IEEE 802.11 standard. As the aforementioned wireless LAN technology has been developed and disseminated, applications utilizing wireless LAN technology have diversified, and a demand has arisen for wireless LAN technology that supports higher reliability.

[0005] As applications requiring higher reliability emerge, the IEEE 802.11bn standard, an Ultra High Reliability (UHR) wireless LAN technology, is being developed for single Basic Service Set (BSS) environments and / or redundant BSS environments. The goal of the IEEE 802.11bn standard may be to support improved data transmission speeds, enhanced latency performance, and reduced data error rates. Additionally, the IEEE 802.11bn standard can support low-power operation, peer-to-peer communication, and operations designed to increase channel utilization. It can also support a TXOP sharing method, where wireless LAN terminals share communication resources called TXOPs (transmit opportunities) between access points (APs). Furthermore, to increase the efficiency of communication resource utilization, the wireless LAN standard can support non-primary channel access (NPCA) operations, which use a channel other than the primary channel when the primary channel is occupied, and dynamic subchannel operation (DSO). In addition, it may be possible to support CR-TWT (coordinated-restricted target wake time) operation to protect each low-latency communication segment between multiple access points (APs).

[0006] Here, when a wireless LAN terminal performs power-saving operations over multiple links, a method for efficiently switching power-saving modes to perform data communication may be required, and this is described below. Additionally, a method for the wireless LAN terminal to perform power-saving operations by dynamically changing the terminal's transmit / receive capabilities through the exchange of initial control frames and initial response frames may be required, and this is described below.

[0007] Meanwhile, the technology forming the background of the invention is written to enhance understanding of the background of the invention and may include content that is not prior art already known to a person with ordinary knowledge in the field to which this technology belongs.

[0008]

[0009] The present disclosure relates to a method and apparatus for switching to a power-saving mode in multiple links within a wireless LAN.

[0010] The present disclosure relates to a method and apparatus for performing data communication by switching to a power-saving mode when a wireless LAN terminal supporting multiple links receives a request for data communication on some of the multiple links.

[0011] The present disclosure relates to a method and apparatus for rapidly transmitting data frames to increase the data transmission speed when a wireless LAN terminal performs a power saving operation on multiple links.

[0012] The present disclosure relates to a method and apparatus for performing dynamic low-power operation in a wireless LAN network supporting multiple links.

[0013] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below.

[0014]

[0015] According to one embodiment of the present specification, a method of operation of a first multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system may include the steps of: the first MLD being connected to a second MLD that performs multi-link communication; the first MLD transmitting a first frame to the second MLD from a first link that is activated for the first STA of the first MLD, wherein the first frame indicates whether to switch the activation state of the second link and, if the first frame indicates the activation state of the second link, the first MLD performing frame exchange with the second MLD from the first link and the second link that are activated.

[0016] Additionally, according to one embodiment of the present specification, a first multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system comprises at least one transceiver for transmitting and receiving signals, at least one processor for controlling at least one transceiver, and a memory for storing instructions that cause the STA to perform a specific operation by the at least one processor, wherein the specific operation is connected to a second MLD that performs multi-link communication, and the first MLD transmits a first frame to the second MLD from a first link that is activated for the first STA of the first MLD, wherein the first frame indicates whether to switch the activation state of the second link, and when the first frame indicates the activation state of the second link, the first MLD can perform frame exchange with the second MLD from the first link and the second link that are activated.

[0017] According to one embodiment of the present specification, information on the time of transition when the second link is switched to an active state may be indicated along with an indication of whether the second link is switched to an active state.

[0018] Additionally, according to one embodiment of the present specification, the time at which the second link is switched to an active state may be determined based on the time required for the first MLD to switch to an active state in the second link.

[0019] Additionally, according to one embodiment of the present specification, the first MLD can receive at least one frame transmitted from the first link and the second link, respectively, after the second link is activated, based on an instruction regarding whether the activation state of the second link is switched.

[0020] Additionally, according to one embodiment of the present specification, if the first link and the second link are a non-simultaneous transmit and receive (NSTR) link pair that cannot perform simultaneous transmit and receive operations, the frame transmitted from the first link and the frame transmitted from the second link can be synchronized and received at the same time.

[0021] Additionally, according to one embodiment of the present specification, the first MLD indicates that the second link is not switched to an active state in the switching of the active state of the second link, and the first MLD can receive at least one frame transmitted from the first link from the second MLD.

[0022] According to one embodiment of the present specification, a method of operation of a first multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system may include the step of the first MLD being connected to a second MLD that performs multi-link communication, wherein the second MLD includes a third STA associated with a first link and a fourth STA associated with a second link, and the step of the first MLD receiving a first frame from the second MLD on a first link activated for the third STA of the second MLD, wherein the first frame indicates whether to switch the activation state of the second link activated for the fourth STA of the second MLD, and if the first frame indicates the activation state of the second link of the second MLD, the first MLD performs frame exchange with the second MLD on the first link and the second link activated in the second MLD.

[0023] Additionally, according to one embodiment of the present specification, a first multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system comprises at least one transceiver for transmitting and receiving signals, at least one processor for controlling the at least one transceiver, and a memory for storing instructions that cause the STA to perform a specific operation by the at least one processor, wherein the specific operation is connected to a second MLD that performs multi-link communication, wherein the second MLD comprises a third STA associated with the first link and a fourth STA associated with the second link, and the first MLD receives a first frame from the second MLD on a first link activated for the third STA of the second MLD, wherein the first frame indicates whether to switch the activation state of a second link activated for the fourth STA of the second MLD, and when the first frame indicates the activation state of a second link of the second MLD, the first MLD is activated in the second MLD Frame exchange with the second MLD can be performed on the link and the second link.

[0024] According to one embodiment of the present specification, information on the time of transition when the second link is switched to an active state may be indicated along with an indication of whether the second link is switched to an active state.

[0025] Additionally, according to one embodiment of the present specification, the first MLD can transmit at least one frame from each of the first link and the second link to the second MLD after the second link of the second MLD is activated based on an instruction regarding whether the activation state of the second link is switched.

[0026] Additionally, according to one embodiment of the present specification, if the first MLD indicates that the second link is not switched to an active state in the switching of the active state of the second link of the second MLD, the first MLD may transmit a frame to the second MLD using only the first link.

[0027] Additionally, according to one embodiment of the present specification, a method of operation of a non-AP multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system comprises the steps of: transmitting a first frame instructing the non-AP MLD to perform a dynamic power saving (DPS) operation to an AP MLD; receiving a second frame instructing the non-AP MLD to support the performance of a DPS operation; and receiving the second frame and completing a multi-link DPS setting procedure, wherein a DPS operation is set in the non-AP MLD based on the multi-link DPS setting procedure, and the non-AP MLD may operate in a lower capability mode (LCM) on at least one of the first link and the second link.

[0028] Additionally, according to one embodiment of the present specification, a non-AP multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system comprises at least one transceiver for transmitting and receiving signals, at least one processor for controlling at least one transceiver, and a memory for storing instructions that cause the STA to perform a specific operation by the at least one processor, wherein the specific operation is: transmitting a first frame instructing the AP MLD to perform a dynamic power saving (DPS) operation, receiving a second frame instructing the non-AP MLD to support the performance of a DPS operation, and completing a multi-link DPS setup procedure upon receiving the second frame, wherein a DPS operation is set in the non-AP MLD based on the multi-link DPS setup procedure, and the non-AP MLD may operate in a lower capability mode (LCM) on at least one of the first link and the second link.

[0029] Additionally, according to one embodiment of the present specification, the first frame and the second frame are exchanged at least one of the first link and the second link, and the multi-link DPS setting procedure can be set when the exchange of the first frame and the second frame is completed.

[0030] Additionally, according to one embodiment of the present specification, the first frame may include a link identifier indicating a link where a non-AP MLD performs a DPS operation.

[0031] Additionally, according to one embodiment of the present specification, when the first frame includes a link identifier of the first link and a link identifier of the second link, the first frame includes a DPS operation parameter of the first link and a DPS operation parameter of the second link, and each DPS operation parameter may include a DPS padding delay and a DPS switching delay of the corresponding link.

[0032] Additionally, according to one embodiment of the present specification, if the non-AP MLD performs a DPS operation on the first link and does not perform a DPS operation on the second link, the first frame may include the link identifier of the first link and the DPS operation parameter of the first link, and may not include the link identifier of the second link and the operation parameter of the second link.

[0033] Additionally, according to one embodiment of the present specification, if a non-AP MLD performs a DPS operation on a first link and does not perform a DPS operation on a second link, the first frame includes a link identifier of the first link and a link identifier of the second link, and may indicate that a DPS operation parameter corresponding to the second link is not indicated or that a DPS operation is not performed on the second link.

[0034] Additionally, according to one embodiment of the present specification, the first frame and the second frame are exchanged at the first link and the second link, respectively, and the multi-link DPS setting procedure can be set when the first frame and the second frame are exchanged at the first link and the second link, respectively.

[0035] Additionally, according to one embodiment of the present specification, the first frame may indicate DPS operation parameters including a DPS padding delay and a DPS switching delay of a non-AP MLD used in the link where the first frame is transmitted.

[0036] Additionally, according to one embodiment of the present specification, a method of operation of an AP multi-link device (MLD) comprising a first access point (AP) associated with a first link and a second AP associated with a second link in a wireless LAN system comprises the steps of: receiving a first frame from a non-AP MLD instructing the AP MLD to perform a dynamic power saving (DPS) operation; transmitting a second frame instructing the non-AP MLD to support the performance of a DPS operation; and transmitting the second frame and completing a multi-link DPS setup procedure, wherein a DPS operation is set in the non-AP MLD based on the multi-link DPS setup procedure, and the non-AP MLD may operate in a lower capability mode (LCM) on the first link and the second link.

[0037] Additionally, according to one embodiment of the present specification, an AP multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system comprises at least one transceiver for transmitting and receiving signals, at least one processor for controlling at least one transceiver, and a memory for storing instructions that cause the STA to perform a specific operation by the at least one processor, wherein the specific operation is: receiving a first frame from a non-AP MLD instructing to perform a dynamic power saving (DPS) operation, transmitting a second frame instructing to the non-AP MLD to support the performance of the DPS operation, and transmitting the second frame and completing a multi-link DPS setup procedure, wherein a DPS operation is set in the non-AP MLD based on the multi-link DPS setup procedure, and the non-AP MLD may operate in a lower capability mode (LCM) on the first link and the second link.

[0038] According to one embodiment of the present specification, the first link and the second link may be a non-simultaneous transmit and receive (NSTR) link pair that cannot perform simultaneous transmit and receive operations.

[0039] Additionally, according to one embodiment of the present specification, the AP MLD can transmit a frame by performing a channel access operation on a first link for the first AP of the AP MLD, and transmit a frame by performing a channel access operation on a second link for the second AP of the AP MLD.

[0040] Additionally, according to one embodiment of the present specification, a frame transmitted at each of the first link and the second link is an initial control frame, and the non-AP MLD can be operated by switching from LCM to HCM (high capability mode) at the first link and the second link by the initial control frame.

[0041] In addition, according to one embodiment of the present specification, when the channel access operation of the first link is completed first, the backoff counter in the first link is kept at 0, and when the channel access operation of the second link is completed, frame transmission can be performed simultaneously in the first link and the second link.

[0042] Additionally, according to one embodiment of the present specification, padding is set in the initial control frame so that the end time of the initial control frame of the first link and the initial control frame of the second link are the same, and the padding may be set equally in the initial control frame of the first link and the initial control frame of the second link by the longer value between the DPS padding delay of the first link and the DPS padding delay of the second link.

[0043] Additionally, according to one embodiment of the present specification, when the channel access operation of the first link is completed first, frame transmission is performed first on the first link, and when the channel access operation of the second link is completed, frame transmission can be performed on the second link.

[0044] Additionally, according to one embodiment of the present specification, a first DPS padding is set in the initial control frame of the first link and a second PDS padding is set in the initial control frame of the second link, wherein the first DPS padding and the second DPS padding are set such that the end times of the initial control frame of the first link and the initial control frame of the second link are the same, and each of the first DPS padding and the second DPS padding may be set to a value longer than the DPS padding delay of the first link and the DPS padding delay of the second link.

[0045] Additionally, according to one embodiment of the present specification, the LCM may be a mode in which at least one of the operating bandwidth, the number of spatial streams, and the modulation and coding scheme (MCS) is limited, or a mode in which only specific format frames can be received.

[0046]

[0047] According to the present disclosure, a method for switching to a power-saving mode in multiple links within a wireless LAN can be provided.

[0048] According to the present disclosure, a method can be provided for a wireless LAN terminal supporting multiple links to perform data communication by switching to a power saving mode when a request for data communication is received from some of the multiple links.

[0049] According to the present disclosure, when a wireless LAN terminal performs a power saving operation on multiple links, a method can be provided to rapidly transmit data frames to increase the data transmission speed.

[0050] According to the present disclosure, a method for performing dynamic low-power operation in a wireless LAN network supporting multiple links can be provided.

[0051] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below.

[0052] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below.

[0053]

[0054] FIG. 1 is a diagram showing a communication node within a wireless LAN system to which the present disclosure applies.

[0055] FIG. 2 is a drawing showing a wireless LAN system to which the present disclosure is applied.

[0056] FIGS. 3a and 3b are drawings illustrating a method for switching power saving modes in multiple links applicable to the present disclosure.

[0057] FIGS. 4a to 4c are drawings illustrating a method for switching power saving modes in multiple links applicable to the present disclosure.

[0058] FIGS. 5a to 5c are diagrams illustrating a method for switching power saving modes in multiple links.

[0059] FIG. 6 is a diagram showing a wireless LAN network to which the present disclosure applies.

[0060] FIG. 7 is a diagram showing multiple links established between MLDs to which the present disclosure applies.

[0061] FIG. 8 is a diagram illustrating a dynamic power saving operation method applied to the present disclosure.

[0062] FIG. 9 is a diagram illustrating a dynamic low-power operation method in multiple links applicable to the present disclosure.

[0063] FIG. 10 is a diagram illustrating a dynamic low-power operation method in multiple links applicable to the present disclosure.

[0064] FIGS. 11a and FIGS. 11b are drawings illustrating a dynamic low-power operation method in multiple links applicable to the present disclosure.

[0065] FIG. 12 is a diagram illustrating a dynamic low-power operation method in multiple links applicable to the present disclosure.

[0066] FIG. 13 is a flowchart showing the operation of a STA MLD in a wireless LAN to which the present disclosure applies.

[0067] FIG. 14 is a flowchart showing the operation of a STA MLD in a wireless LAN to which the present disclosure applies.

[0068] FIG. 15 is a flowchart showing the operation of an AP MLD in a wireless LAN to which the present disclosure applies.

[0069] FIG. 16 is a flowchart showing the operation of a non-AP MLD in a wireless LAN to which the present disclosure applies.

[0070]

[0071] The present disclosure is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present disclosure to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present disclosure.

[0072] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0073] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0074] The terms used in this disclosure are used merely to describe specific embodiments and are not intended to limit this disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this disclosure, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0075] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this disclosure pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this disclosure.

[0076] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding of the present disclosure, the same reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0077] Below, a wireless communication system to which embodiments according to the present disclosure are applied will be described. The wireless communication system to which embodiments according to the present disclosure are applied is not limited to the details described below, and embodiments according to the present disclosure may be applied to various wireless communication systems. The wireless communication system may be referred to as a "wireless communication network."

[0078] FIG. 1 is a diagram showing a communication node within a wireless LAN system to which the present disclosure applies. Referring to FIG. 1, the communication node (100) may include at least one of a processor (110), memory (120), a transceiver (130), an input / output interface (140), a storage device (150), and a bus (160). For example, the communication node (100) may be an access point (AP), a station (STA), an access point multi-link device (MLD), or a non-AP MLD. However, the communication node may not be limited thereto and may be a node that performs communication with another node or device based on the configuration described above. For example, the operating channel bandwidth supported by the AP may be 20 MHz (megahertz), 80 MHz, 160 MHz, etc. The operating channel bandwidth supported by the station may be 20 MHz, 80 MHz, etc. However, it may not be limited thereto.

[0079] A processor (110) within a communication node (100) can control at least one of a memory (120), a transceiver (130), an input / output interface (140), and a storage device (150) for each component within the communication node. The memory (120) within the communication node (100) can store information regarding commands and instructions executed by the processor (110), and the transceiver (130) may refer to a transceiver, an RF (radio frequency) unit, an RF module, or other components that perform signal transmission and reception. The input / output interface (140) within the communication node (100) is an interface for input and output that can be linked with other interfaces and may further include a separate storage device (150). Each component within the communication node (100) can communicate with one another by being connected by a bus (160).

[0080] However, as an example, each component included in the communication node (100) may be connected via an individual interface or an individual bus centered on the processor (110), rather than via a common bus (160). The processor (1110) may also be connected via a dedicated interface to at least one of the memory (120), the transmission / reception device (130), the input / output interface device (140), and the storage device (150).

[0081] A processor (110) can execute a program command stored in at least one of a memory (120) or a storage device (150). The processor (110) may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present disclosure are performed. Each of the memory (120) and the storage device (150) may be composed of at least one of a volatile storage medium or a non-volatile storage medium. e.g., the memory (120) may be composed of at least one of read-only memory (ROM) or random access memory (RAM).

[0082] In the following, the relevant operations are described based on the wireless LAN terminal as a station (STA). In accordance with the terminology usage according to IEEE 802.11, STA can refer to both AP STAs operating as access points (APs) and non-AP STAs operating in connection with an AP. However, for the convenience of explanation, APs and non-AP STAs are distinguished below; this distinction is merely for convenience of explanation, and it is self-evident that operations regarding an AP can be applied to both AP STAs and non-AP STAs. Furthermore, it is self-evident that the non-AP STA operations described below can also be applied to both non-AP STAs and AP STAs.

[0083] FIG. 2 is a diagram illustrating a wireless LAN system to which the present disclosure applies. Referring to FIG. 2, the basic service set (BSS) of the wireless LAN system may include one AP (210) and a plurality of non-AP STAs (221, 222, 223, 224), and the plurality of non-AP STAs (221, 222, 223, 224) may be controlled by the AP (210). However, the wireless LAN system is not limited to a BSS, and an environment consisting only of non-AP STAs without a fixed service set or AP may also be considered, and is not limited to a specific form. Each wireless device within the wireless LAN system may include a MAC (medium access control) layer and a physical (PHY) layer, and communication between wireless devices may be performed. For convenience of explanation, the following description focuses on the AP and non-AP STA, but is not limited thereto. For example, the following items may apply equally to other communication nodes or devices and are not limited to a specific form.

[0084] The following describes a method for rapidly performing data communication on the remaining links when a data communication request is received on one of the multiple links, in the case where power saving operation is performed on multiple links within a wireless LAN. Based on power saving operation, a wireless LAN terminal may operate in a lower capability mode (LCM), where the reception bandwidth, reception spatial stream, and receivable frame formats are limited (e.g., only an initial control frame with a fixed format and transmission bandwidth can be received). Alternatively, the wireless LAN terminal may operate in a doze state where it cannot receive frames, and the method of operation based on the aforementioned modes is described below. Furthermore, a wireless LAN terminal supporting multiple links may perform a transition from a lower capability mode to a high capability mode, and the operation based on this is described below.

[0085] Multiple links may be configured in a wireless LAN network. Consider a case where an AP MLD (multi-link device) 1 and a non-AP STA MLD 1 operate on a first link and a second link. The non-AP STA MLD 1 can perform communication by associating with the AP MLD 1. Additionally, there may be an associated AP and a non-AP STA in the AP MLD 1 and the non-AP STA MLD 1. The AP of the AP MLD 1 operating on the first link may be AP 1-1, and the AP of the AP MLD 1 operating on the second link may be AP 1-2 (310-2). Additionally, the non-AP STA of the non-AP STA MLD 1 operating on the first link may be non-AP STA 1-1, and the non-AP STA of the non-AP STA MLD operating on the second link may be non-AP STA 1-2. In the following, the operation of AP 1-1 and AP 1-2 (310-2) may be referred to as the operation of AP MLD 1. Conversely, the operation of AP MLD 1 may be referred to as the operation of AP 1-1 and AP 1-2 (310-2). Additionally, the operation of non-AP STA 1-1 and non-AP STA 1-2 may be referred to as the operation of non-AP STA MLD 1. Conversely, the operation of non-AP STA MLD 1 may be referred to as the operation of non-AP STA 1-1 and non-AP STA 1-2. Additionally, non-AP STA MLD 1 may be a non-simultaneous transmit and receive (NSTR) non-AP STA MLD that cannot perform simultaneous transmit and receive operations on the first link and the second link.

[0086] As another example, the AP MLD may be a mobile AP where a non-AP STA performs the role of an AP. In the mobile AP, the first link may be referred to as the primary link, and the second link may be referred to as the secondary link. The secondary link may be available only when transmitting the primary link, and the mobile AP may be an NSTR MLD. For the convenience of explanation, the following description is based on AP MLD 1 and non-AP STA MLD 1, but is not limited to these terms.

[0087] AP MLD 1 can perform power saving operations. When the subordinate APs of AP MLD 1 perform power saving operations, one of the available power saving modes is doze mode, in which reception of all frames is impossible and channel detection is also impossible. Another power saving mode available when the subordinate APs of AP MLD 1 perform power saving operations is lower capability mode (LCM). LCM may be a mode with fewer restrictions than doze mode. For example, in LCM, at least one of the AP's operating bandwidth and the AP's operating space stream may be limited. As another example, in LCM, the AP may be able to receive only frames of a specific format. Here, the frame of a specific format may be an initial control frame (ICF). The initial control frame may be a BlockAck request (BAR) frame, a request to send (MU) trigger frame, a buffer status report poll (BSRP) trigger frame, or any other frame, and is not limited to a specific form. Another power-saving mode in which the subordinate APs of AP MLD 1 can operate is High Capability Mode (HCM). When an AP operates in HCM, it can perform normal data transmission and reception, and the operating bandwidth and operating space stream are not limited. Therefore, Doze Mode may have the lowest power consumption, while HCM may have the highest. If an AP receives an initial control frame in LCM and performs data communication, the AP may switch from LCM to HCM to operate. As another example, if an AP receives an initial control frame in LCM but power saving takes precedence, the AP may maintain LCM without switching to HCM.

[0088] For example, AP 1-1 operating on the first link can perform LCM operation. On the other hand, AP 1-2 operating on the second link can be made to operate in Doze mode. AP 1-1 can receive an initial control frame while operating in LCM and cause AP 1-1 of the first link to maintain the operation mode as LCM or switch to HCM. Additionally, AP 1-1 can receive an initial control frame while operating in LCM and cause AP 1-2 of the second link to switch from Doze mode to HCM, which enables data communication.

[0089] non-AP STA MLD 1 may intend to communicate with AP MLD 1 over multiple links. non-AP STA MLD 1 may recognize that AP 1-1 operating on the first link is operating in LCM mode. Additionally, non-AP STA MLD 1 may recognize that AP 1-2 operating on the second link is operating in Doze mode. For example, non-AP STA MLD 1 may recognize that AP 1-2 is operating in Doze mode by receiving a frame containing multi-link power saving operation information of the AP MLD from the AP MLD (e.g., at least one of AP 1-1 or AP 1-2 under AP MLD 1). Accordingly, non-AP STA 1-1 of non-AP STA MLD 1 can transmit an ICF to AP 1-1 of AP MLD 1 on the first link. The ICF may include padding fields to secure time for the communication state transition of AP 1-1 (i.e., time to switch modes from LCM to HCM). Additionally, the ICF may include instruction information in which non-AP STA MLD 1 requests communication with AP MLD 1 on the first link and the second link. For example, the instruction information may be a link bitmap or a link ID, but other forms of instruction information may also be possible. If there is communication by a BSS other than the BSS configured by AP 1-2 on the second link (e.g., overlapping basic service set, OBSS), the ICF may additionally indicate the time when channel occupancy by the OBSS ends (i.e., the time when the channel is expected to transition from a busy state to an idle state). If there is no ongoing communication on the second link (or if the above-described information is missing), the above-described indication information included in the ICF may be changed and used as an indicator indicating that the second link is in a suspended state.Additionally, the ICF may include uplink traffic information that non-AP STA MLD 1 must transmit to AP MLD 1. For example, the uplink traffic information may be buffer status report (BSR) information and traffic information by access categories (AC), but is not limited to such embodiments.

[0090] AP 1-1 receives an ICF from non-AP STA 1-1 and can transmit an initial control response (ICR) frame as a response frame. The ICR frame may be referred to as ICR. The ICR may include instruction information indicating whether AP MLD 1 switches to HCM on the first link. If AP MLD 1 indicates switching to HCM on the first link, AP 1-1 can operate as HCM and perform communication operations with non-AP STA 1-1. On the other hand, if AP MLD 1 indicates not switching to HCM on the first link, AP 1-1 can operate as LCM. Accordingly, non-AP STA 1-1 can perform communication by considering at least one of the constraints on the bandwidth and spatial streams available to AP 1-1 based on AP 1-1's operation in LCM. Alternatively, non-AP STA 1-1 can perform communication using only a specific frame format based on the operation of the LCM of AP 1-1.

[0091] The ICR may include information indicating whether AP MLD 1 switches to HCM on the second link and when AP MLD 1 can operate as HCM on the second link. The time required to switch from LCM to HCM (hereinafter referred to as switching time) may be determined by pre-negotiation or pre-configured parameters. The time required to switch from LCM to HCM may be the time required to switch to HCM from the time of receiving the ICF.

[0092] If AP MLD 1 instructs to switch to HCM on the second link, AP MLD 1 may instruct the ICR when AP 1-2 can operate as HCM. Alternatively, if AP MLD 1 instructs to switch to HCM on the second link, AP MLD 1 may recognize that it can operate as HCM after the switching time has elapsed since the ICF reception time. non-AP STA 1-2 can perform data communication when AP 1-2 can operate as HCM on the second link. On the other hand, if AP MLD 1 instructs not to switch to HCM on the second link, AP 1-2 may maintain Doze mode. Therefore, non-AP STA 1-2 cannot perform communication operations with AP 1-2 on the second link. The ICR of AP 1-1 may include information instructing whether AP MLD 1 should transmit a trigger frame to allocate uplink resources to non-AP STA MLD 1. If the ICR instructs the transmission of a trigger frame, AP MLD 1 may transmit a trigger frame to allocate uplink resources to non-AP STA MLD 1. If the ICR instructs not to transmit a trigger frame, AP MLD 1 may not transmit a trigger frame to allocate uplink resources to non-AP STA MLD 1. If AP MLD 1 transmits a trigger frame to allocate uplink resources to non-AP STA MLD 1, the bandwidth and duration of the uplink resources may be determined differently depending on the uplink traffic information transmitted by non-AP STA MLD 1 to AP MLD 1. Meanwhile, AP 1-2 of AP MLD 1 switching to HCM means that AP 1-2 switches its operation to HCM while originally operating in Doze mode. HCM is a mode that can only operate when the link of AP 1-2 is switched to an Awake (or Active) state.

[0093] That is, the ICR transmitted by AP MLD 1 to non-AP STA MLD 1 may include information indicating the mode (or state) of AP MLD 1 on the second link. As another example, AP MLD 1 may be an MLD using multiple links. Among the multiple links of AP MLD 1, the first link may be in an active state and the second link may be in a doze state. AP MLD 1 may include information indicating that the second link is switched to an active state in a frame (e.g., ICR) transmitted through the first link which is in an active state. Alternatively, among the multiple links of AP MLD 1, both the first link and the second link are in an active state, and AP MLD 1 may include information indicating that the second link is switched from an active state to a doze state in a frame (e.g., ICR) transmitted through the first link which is in an active state. That is, AP MLD 1 may transmit a frame containing information indicating whether another link is switched to an active state through the link which is in an active state to non-AP STA MLD 1. In addition, for example, although the above description was made based on AP MLD, it can be applied in the same way when non-AP STA MLD indicates whether to switch the activation state of another link through an active link. For the convenience of explanation, the following description is also made based on AP MLD, but non-AP STA MLD can operate in the same way and may not be limited to a specific form.

[0094] Meanwhile, non-AP STA MLD 1 can perform frame exchange with AP MLD 1 based on a frame containing information indicating whether the activation state of the multiple links of AP MLD 1 is switched. If the frame containing information indicating whether the activation state of the multiple links is switched indicates that the first link of AP MLD 1 is in an active state and the second link is in a dozed (inactive) state, non-AP STA MLD 1 can communicate with AP MLD 1 using only the first link. However, if the frame indicates that the first link of AP MLD 1 is in an active state and the second link is in an active state, non-AP STA MLD 1 can communicate with AP MLD 1 using both the first link and the second link. That is, non-AP STA MLD 1 can determine the available link information of AP MLD 1 based on a frame containing information indicating whether the activation state of the multiple links is switched.

[0095] Meanwhile, AP MLD 1 can transmit a frame containing information indicating whether to switch the activation state of the multi-link, even in a form other than a response frame to a specific frame.

[0096] The length of the duration field included in the MAC header of the ICF transmitted by non-AP STA 1-1 can be set to the estimated transmission time of the ICR length transmitted by AP 1-1 in response to the ICF + SIFS. The duration field can be set considering that a frame after the ICR may not be transmitted immediately or may not be transmitted. That is, it may be a case where AP 1-1 transmits the ICR and fails to perform frame transmission after SIFS or PIFS. The NAV (network allocation vector) set by the ICF may not include the time required for data frame exchange transmitted after the ICF and ICR. The duration included in the MAC header of the ICR transmitted after the ICF may be set to 0. The above-described matters may be applied identically to Figures 3a through 5c below, and it may be possible to change some operations depending on each operation.

[0097] FIGS. 3a and 3b are drawings illustrating a method for switching power saving modes in multiple links applicable to the present disclosure.

[0098] Referring to FIG. 3a, non-AP STA 1-1 (320-1) can transmit an ICF (401) to AP 1-1. non-AP STA 1-2 of non-AP STA MLD 1 can detect that the second link is in an occupied state. non-AP STA 1-2 can recognize the time when the occupancy state ends, and the ICF (401) transmitted by non-AP STA 1-1 (320-1) to AP 1-1 (310-1) may include information on the time when the occupancy state of the second link ends. AP 1-1 (310-1) can transmit an ICR (402) to non-AP STA 1-1 (320-1) in response to the ICF (401). The ICR (402) transmitted by AP 1-1 (310-1) may indicate that AP MLD 1 operates as HCM on the first link and the second link. For example, AP 1-1 (310-1) may operate as HCM immediately after receiving the ICF (401). For another example, AP 1-1 (310-1) may operate as HCM after receiving the ICF (401) and after an additional amount of time. In the above case, the ICR (402) transmitted by AP 1-1 (310-1) to non-AP STA 1-1 (320-1) may further include information on when AP 1-1 (310-1) operates as HCM. Additionally, information regarding the time when AP 1-2 (310-2) operates as HCM on the second link may also be included in ICR (402), and non-AP STA 1-2 can transmit frames to AP 1-2 (310-2) after that time.

[0099] For example, if the release of the second link's occupancy state due to OBSS occurs later than the time of HCM operation of AP 1-2 (310-2), AP 1-2 (310-2) may operate as HCM at the time when the second link's occupancy state due to OBSS is released. Through the above, better power saving operation can be performed. AP 1-2 (310-2) of AP MLD 1 can check whether the release of the second link's occupancy state due to OBSS occurs later than the time of HCM operation by checking the second link occupancy state termination information included in the ICF (401) transmitted by non-AP STA 1-1 (320-1).

[0100] When non-AP STA 1-1 (320-1) receives ICR (402), non-AP STA MLD 1 may perform a channel access operation (e.g., an enhanced distributed channel access (EDCA) backoff operation) on the first link and the second link. The channel access operation of non-AP STA 1-1 (320-1) on the first link may be performed immediately after receiving ICR (402). The channel access operation of non-AP STA 1-2 on the second link may be performed after the channel occupancy state by OBSS ends. AP 1-2 (310-2) may maintain a doze state until the channel occupancy state by OBSS ends. If the channel access operation of non-AP STA 1-1 (320-1) on the first link is completed before that of the second link (e.g., the backoff counter reaches 0), non-AP STA 1-1 (320-1) may keep the backoff counter at 0 and not transmit the frame until the channel access operation of non-AP STA 1-2 is completed. That is, non-AP STA 1-1 (320-1) may keep the backoff counter at 0 and not transmit the frame until the channel access operation of non-AP STA 1-2 is completed in order to synchronize the start time of frame transmission with non-AP STA 1-2. When the channel access operation of non-AP STA 1-2 is completed, non-AP STA 1-1 (320-1) and non-AP STA 1-2 can synchronize the frame transmission start time and transmit uplink data frames (403-1, 403-2) to AP 1-1 (310-1) and AP 1-2 (310-2) of AP MLD 1.The end time of transmission of uplink data frames (403-1, 403-2) transmitted by non-AP STA 1-1 (320-1) and non-AP STA 1-2 can also be synchronized, and AP 1-1 (310-1) and AP 1-2 (310-2) can transmit response frames (e.g., BlockAck frames, 404-1, 404-2) to non-AP STA 1-1 (320-1) and non-AP STA 1-2, respectively.

[0101] Referring to FIG. 3b, non-AP STA 1-1 (320-1) can transmit an ICF (401) to AP 1-1 (310-1). non-AP STA 1-2 of non-AP STA MLD 1 can detect that the channel on the second link is occupied. Since non-AP STA 1-2 can recognize the time when the channel occupancy ends, the ICF (401) transmitted by non-AP STA 1-1 (320-1) to AP 1-1 (310-1) may further include information on the time when the occupancy of the second link ends. AP 1-1 (310-1) (401) can transmit an ICR (402) to non-AP STA 1-1 (320-1) in response to the ICF (401). The ICR (402) transmitted by AP 1-1 (310-1) may indicate that AP MLD 1 operates as an HCM on the first link and the second link.

[0102] For example, AP 1-1 (310-1) may operate as HCM immediately after receiving ICF (401). For another example, AP 1-1 (310-1) may operate as HCM after receiving ICF (401) and after an additional time. In the above case, the ICR (402) that AP 1-1 (310-1) transmits to non-AP STA 1-1 (320-1) may further include information on the time when AP 1-1 (310-1) operates as HCM. Additionally, information on the time when AP 1-2 (310-2) operates as HCM on the second link may also be included in the ICR (402), and non-AP STA 1-2 may transmit a frame to AP 1-2 (310-2) after that time. If the release of the second link's occupancy state due to OBSS occurs later than the time of HCM operation of AP 1-2 (310-2), AP 1-2 (310-2) may operate as HCM at the time the second link's occupancy state due to OBSS is released. That is, AP 1-2 (310-2) may maintain a doze state until the time of termination of the channel occupancy state due to OBSS. The ICR (402) transmitted by AP 1-1 (310-1) to non-AP STA 1-1 (320-1) may contain instruction information that causes AP MLD 1 to transmit a trigger frame to non-AP STA 1-1 (320-1).

[0103] Here, AP 1-1 (310-1) and AP 1-2 (310-2) can perform channel access operations. Among AP 1-1 (310-1) and AP 1-2 (310-2), there may be an AP whose channel access operation is completed first (e.g., when the backoff counter reaches 0). For example, the channel access operation of AP 1-1 (310-1) may be completed before that of AP 1-2 (310-2). In the above case, AP 1-1 (310-1) may keep the backoff counter at 0 and not perform frame transmission until the channel access operation of AP 1-2 (310-2) is completed. Through the above, AP 1-1 (310-1) can synchronize the start time of frame transmission with AP 1-2 (310-2). Alternatively, when the channel access operation of AP 1-2 (310-2) is completed, AP 1-1 (310-1) and AP 1-2 (310-2) may transmit trigger frames (405-1, 405-2) that allocate uplink resources to non-AP STA 1-1 (320-1) and non-AP STA 1-2 of non-AP STA MLD 1, respectively, by synchronizing the start time of transmission of the frames. The start time and end time of transmission of the trigger frames (405-1, 405-2) may be synchronized. Here, the uplink length (UL length) field of the trigger frame (405-1, 405-2) can be set so that the transmission end time of the uplink frames (406-1, 406-2) of non-AP STA 1-1 (320-1) and non-AP STA 1-2 transmitted based on the trigger frame (405-1, 405-2) is the same. That is, the length of the uplink resource allocated based on the uplink length field of the trigger frame (405-1, 405-2) can be set.When non-AP STA 1-1 (320-1) and non-AP STA 1-2 receive trigger frames (405-1, 405-2), they can send uplink frames (406-1, 406-2) to AP 1-1 (310-1) and AP 1-2 (310-2), respectively, and AP 1-1 (310-1) and AP 1-2 (310-2) can send response frames (e.g., BlockAck frames, 407-1, 407-2) to non-AP STA 1-1 (320-1) and non-AP STA 1-2, respectively.

[0104] FIGS. 4a to 4c are drawings illustrating a method for switching power saving modes in multiple links applicable to the present disclosure.

[0105] Referring to FIG. 4a, non-AP STA 1-1 (320-1) can transmit an ICF (408) to AP 1-1 (310-1). AP 1-1 (310-1) can transmit an ICR (409) to non-AP STA 1-1 (320-1) in response to the ICF (408). The ICR (409) transmitted by AP 1-1 (310-1) can indicate that AP MLD 1 continues to operate as LCM on the first link and operates in Doze mode on the second link. If there is a frame to be transmitted to AP 1-1 (310-1) by non-AP STA 1-1 (320-1), non-AP STA 1-1 (320-1) can perform uplink frame (410) transmission using the limited frequency bandwidth and spatial stream in which AP 1-1 (310-1) operates in LCM. As another example, if AP 1-1 (310-1) is only able to receive an initial control frame in LCM, non-AP STA 1-1 (320-1) may not be able to transmit a frame to AP 1-1 (310-1). On the other hand, the non-AP STA 1-2 of the second link performs a channel access operation to transmit an uplink data frame that is synchronized with the start time of the non-AP STA 1-1 (320-1) of the first link, and the non-AP STA 1-2 of the second link can complete the channel access operation (e.g., when the backoff counter reaches 0). The non-AP STA 1-2 can keep the backoff counter at 0 and delay frame transmission until the non-AP STA 1-1 (320-1) receives an ICR (409) from AP 1-1 (310-1). When non-AP STA 1-1 (320-1) receives an ICR (409) from AP 1-1 (310-1), and the received ICR (409) indicates that AP 1-2 (310-2) of the second link operates in Doze mode, non-AP STA 1-2 may be unable to use the second link.Therefore, non-AP STA 1-2 can discard the backoff counter that is kept at 0, and data frames may not be transmitted on the second link.

[0106] Referring to FIG. 4b, non-AP STA 1-1 (320-1) can transmit an ICF (408) to AP 1-1 (310-1). AP 1-1 (310-1) can transmit an ICR (409) to non-AP STA 1-1 (320-1) in response to the ICF (408). The ICR (409) transmitted by AP 1-1 (310-1) can indicate that AP MLD 1 operates in HCM mode on the first link and in Doze mode on the second link. If there is a frame to be transmitted to AP 1-1 (310-1) by non-AP STA 1-1 (320-1), non-AP STA 1-1 (320-1) receives an ICR (409) from AP 1-1 (310-1) and, after SIFS or PIFS time, can transmit an uplink frame (411) using the operational bandwidth and spatial stream supported by the HCM of AP 1-1 (310-1) (e.g., the general operational bandwidth and spatial stream of AP 1-1). Non-AP STA 1-2 of the second link performs a channel access operation to transmit an uplink frame that is synchronized with the start time of non-AP STA 1-1 (320-1) of the first link, and non-AP STA 1-2 of the second link can complete the channel access operation (e.g., when the backoff counter reaches 0). non-AP STA 1-2 may keep the backoff counter at 0 and delay frame transmission until non-AP STA 1-1 (320-1) receives an ICR (409) from AP 1-1 (310-1). When non-AP STA 1-1 (320-1) receives an ICR (409) from AP 1-1 (310-1) and the received ICR (409) indicates that AP 1-2 of the second link is operating in Doze mode, non-AP STA 1-2 may be unable to use the second link. Therefore, non-AP STA 1-2 may discard the backoff counter kept at 0 and may not perform data frame transmission on the second link.

[0107] Additionally, consider cases where it takes more time for the AP 1-1 (310-1) of the first link to switch from LCM to HCM. For example, the AP 1-1 (310-1) may not be able to switch its operating mode to HCM even after sending the ICR (409) to the non-AP STA 1-1 (320-1). In the above case, the AP 1-1 (310-1) may indicate to the ICR (409) the expected time of transition when the AP 1-1 (310-1) will operate in HCM. As another example, the switching time required for the AP 1-1 (310-1) to switch to HCM may be a value that is negotiated in advance or known. The length of the duration field in the MAC header of the ICR (409) may indicate the length until the point in time when AP 1-1 (310-1) operates as HCM, and may set a NAV to prevent other STAs, excluding non-AP STA 1-1 (320-1), from accessing the medium during the time when AP 1-1 (310-1) switches to HCM. The non-AP STA 1-1 (320-1) may receive the ICR (409) and wait without performing frame transmission until the point in time when AP 1-1 (310-1) operates as HCM as indicated by AP 1-1 (310-1). After that, the non-AP STA 1-1 (320-1) may perform uplink frame (411) transmission to AP 1-1 (310-1) at the point in time when AP 1-1 (310-1) operates as HCM.

[0108] As another example, non-AP STA 1-1 (320-1) may receive ICR (409) and repeatedly perform EDCA backoff operations until the point in time when AP 1-1 (310-1) instructed by AP 1-1 (310-1) operates as HCM. When non-AP STA 1-1 (320-1) performs EDCA backoff operations, non-AP STA 1-1 (320-1) may not increment the EDCA channel access parameters CW[AC] and QSRC[AC]. non-AP STA 1-1 (320-1) may initialize the EDCA channel access parameters CW[AC] and QSRC[AC] (e.g., CW[AC] to CWmin[AC], QSRC[AC] to 0), select a backoff counter, and repeatedly perform backoff operations. Alternatively, non-AP STA 1-1 (320-1) may repeatedly perform backoff operations using the CW[AC] and QSRC[AC] that were last used for channel access. If the channel access operation of non-AP STA 1-1 (320-1) is completed after the point in time when AP 1-1 (310-1) is operating in HCM, non-AP STA 1-1 (320-1) may transmit an uplink frame (411) to AP 1-1 (310-1).

[0109] Additionally, the non-AP STA 1-2 of the second link may perform a channel access operation to transmit an uplink frame that is synchronized with the start time of the non-AP STA 1-1 (320-1) of the first link. The non-AP STA 1-2 of the second link may complete the channel access operation (e.g., when the backoff counter reaches 0). The non-AP STA 1-2 may delay frame transmission by keeping the backoff counter at 0 until the non-AP STA 1-1 (320-1) receives an ICR (409) from AP 1-1 (310-1). If non-AP STA 1-1 (320-1) receives an ICR (409) from AP 1-1 (310-1) and the received ICR (409) indicates that AP 1-2 of the second link is operating in doze mode, non-AP STA 1-2 may be unable to use the second link. Consequently, non-AP STA 1-2 may discard a backoff counter that is kept at 0, and data frames may not be transmitted on the second link.

[0110] Referring to FIG. 4c, non-AP STA 1-1 (320-1) can transmit an ICF (408) to AP 1-1 (310-1). AP 1-1 (310-1) can transmit an ICR (409) to non-AP STA 1-1 (320-1) in response to the ICF (408). The ICR (409) transmitted by AP 1-1 (310-1) may indicate that AP MLD 1 operates as HCM on the first link and operates in HCM mode on the second link. The time when AP 1-2 operates as HCM on the second link may be later than the time when AP 1-1 (310-1) operates as HCM, and AP 1-1 (310-1) may indicate the time when AP 1-2 operates as HCM in the ICR (409). non-AP STA 1-1 (320-1) can receive an ICR (409) from AP 1-1 (310-1) and determine when AP 1-2 is operating as HCM. When non-AP STA 1-1 (320-1) and non-AP STA 1-2 perform transmission using multiple links (i.e., using the first link and the second link simultaneously), non-AP STA 1-1 (320-1) and non-AP STA 1-2 may need to synchronize the start time of frame transmission on multiple links. In the above case, non-AP STA 1-1 (320-1) can perform a channel access operation from the time it completes receiving the ICR (409) from AP 1-1 (310-1). If the channel access operation is completed earlier than when AP 1-1 (310-1) operates as HCM (e.g., when the backoff counter reaches 0), non-AP STA 1-1 (320-1) may keep the backoff counter at 0. The non-AP STA 1-2 of the second link may perform a channel access operation to transmit an uplink frame that is synchronized in start time with the non-AP STA 1-1 (320-1) of the first link, and the non-AP STA 1-2 of the second link completes the channel access operation (e.g.The backoff counter may reach 0. The non-AP STA 1-2 may keep the backoff counter at 0 and delay frame transmission until the non-AP STA 1-1 (320-1) receives the ICR (409) from the AP 1-1 (310-1). If the non-AP STA 1-2 determines that the non-AP STA 1-1 (320-1) receives the ICR (409) from the AP 1-1 (310-1) and that the AP 1-2 is operating in HCM, the non-AP STA 1-2 may further keep the backoff counter at 0 and delay frame transmission until the AP 1-2 is operating in HCM. non-AP STA 1-1 (320-1) and non-AP STA 1-2 can transmit uplink frames (412-1, 412-2) with synchronized transmission start times to AP 1-1 (310-1) and AP 1-2 of AP MLD 1 after the point in time when both AP 1-1 (310-1) and AP 1-2 are operating as HCM and after the point in time when both non-AP STA 1-1 (320-1) and non-AP STA 1-2 have completed channel access operations.

[0111] FIGS. 5a to 5c are diagrams illustrating a method for switching power saving modes in multiple links.

[0112] Referring to FIG. 5a, non-AP STA 1-1 (320-1) can transmit an ICF (413-1) to AP 1-1 (310-1). AP 1-1 (310-1) can transmit an ICR (414) to non-AP STA 1-1 (320-1) in response to the ICF (413-1). The ICR (414) transmitted by AP 1-1 (310-1) can indicate that AP MLD 1 continues to operate as an LCM on the first link and operates in Doze mode on the second link. If there is a frame to be transmitted to AP 1-1 (310-1) by non-AP STA 1-1 (320-1), non-AP STA 1-1 (320-1) can transmit an uplink frame (415) using the limited frequency bandwidth and spatial stream in which AP 1-1 (310-1) operates in the LCM. As another example, if AP 1-1 (310-1) is only capable of receiving an initial control frame in the LCM, non-AP STA 1-1 (320-1) may not be able to transmit a frame to AP 1-1 (310-1). Non-AP STA 1-2 of the second link can perform a channel access operation for transmitting an uplink frame that is synchronized with the start time of non-AP STA 1-1 (320-1) of the first link. Here, the non-AP STA 1-1 (320-1) and non-AP STA 1-2 of the first link and the second link, respectively, can transmit an ICF (413-1, 413-2) with the same transmission start time and transmission end time. That is, non-AP STA 1-2 can transmit the ICF (413-2) on the second link. non-AP STA 1-2 can transmit the ICF (413-2) and perform the channel access operation again after PIFS. non-AP STA 1-2 can wait until the AP 1-2 of the second link operates as HCM.When non-AP STA 1-2 performs a channel access operation again, non-AP STA 1-2 may perform the channel access operation by selecting a backoff counter using the existing CW[AC] and QSRC[AC] values. Alternatively, non-AP STA 1-2 may perform the channel access operation by selecting a backoff counter using the initialized CW[AC] and QSRC[AC] values ​​(e.g., CW[AC] initialized to CWmin[AC] and QSRC[AC] initialized to 0), and the non-AP STA 1-2 of the second link may complete the channel access operation (e.g., when the backoff counter reaches 0). non-AP STA 1-2 may delay frame transmission by keeping the backoff counter at 0 until the point when AP 1-2 operates as HCM. When non-AP STA 1-1 (320-1) receives an ICR (414) from AP 1-1 (310-1) and the received ICR (414) indicates that AP 1-2 of the second link is operating in doze mode, non-AP STA 1-2 may be unable to use the second link. Consequently, non-AP STA 1-2 may discard a backoff counter that is kept at 0, and data frames may not be transmitted on the second link.

[0113] Referring to FIG. 5b, non-AP STA 1-1 (320-1) can transmit an ICF (413-1) to AP 1-1 (310-1). AP 1-1 (310-1) can transmit an ICR (414) to non-AP STA 1-1 (320-1) in response to the ICF (413-1). The ICR (414) transmitted by AP 1-1 (310-1) can indicate that AP MLD 1 operates in HCM mode on the first link and in Doze mode on the second link. If there is a frame to be transmitted to AP 1-1 (310-1) by non-AP STA 1-1 (320-1), non-AP STA 1-1 (320-1) receives an ICR (414) from AP 1-1 (310-1) and, after SIFS or PIFS time, can transmit an uplink frame (416) using the operational bandwidth and spatial stream supported by the HCM of AP 1-1 (310-1) (e.g., the general operational bandwidth and spatial stream of AP 1-1 (310-1)). Here, non-AP STA 1-1 (320-1) and non-AP STA 1-2 of the first link and the second link can transmit an ICF (413-1, 413-2) with the same transmission start time and transmission end time. That is, non-AP STA 1-2 can transmit an ICF (413-2) on the second link. non-AP STA 1-2 can transmit ICF (413-2) and perform channel access operations again after PIFS. When non-AP STA 1-2 performs channel access operations again, non-AP STA 1-2 can perform channel access operations by selecting a backoff counter using the existing CW[AC] and QSRC[AC] values. Alternatively, non-AP STA 1-2 can perform channel access operations by selecting a backoff counter using the initialized CW[AC] and QSRC[AC] values ​​(e.g., CW[AC] initialized to CWmin[AC] and QSRC[AC] initialized to 0).That is, non-AP STA 1-2 may wait until the AP 1-2 of the second link operates in HCM mode. The non-AP STA 1-2 of the second link may complete a channel access operation (e.g., the backoff counter reaches 0). The non-AP STA 1-2 may keep the backoff counter at 0 and delay frame transmission until the AP 1-2 operates in HCM mode. When non-AP STA 1-1 (320-1) receives an ICR (414) from AP 1-1 (310-1), and the received ICR (414) indicates that the AP 1-2 of the second link operates in Doze mode, the non-AP STA 1-2 may be unable to use the second link. Therefore, the non-AP STA 1-2 may discard the backoff counter that is kept at 0, and data frames may not be transmitted on the second link.

[0114] As another example, it may take longer for the AP 1-1 (310-1) of the first link to switch from LCM to HCM. Here, the AP 1-1 (310-1) may not be able to switch its operating mode to HCM even after the time it sends the ICR (414) to the non-AP STA 1-1 (320-1). In the above case, the AP 1-1 (310-1) may indicate to the ICR (414) the expected time of transition when the AP 1-1 (310-1) operates as HCM. The length of the duration field in the MAC header of the ICR (414) may indicate the length until the time when the AP 1-1 (310-1) operates as HCM. Here, a NAV can be configured to prevent other STAs, excluding non-AP STA 1-1 (320-1), from accessing the medium during the time that AP 1-1 (310-1) switches to HCM. Non-AP STA 1-1 (320-1) receives the ICR (414) and waits without performing frame transmission until the time when AP 1-1 (310-1) operates as HCM as instructed by AP 1-1 (310-1), and then transmits an uplink frame to AP 1-1 (310-1) at the time when AP 1-1 (310-1) operates as HCM. As another example, non-AP STA 1-1 (320-1) may receive ICR (414) and repeatedly perform EDCA backoff operations until the point in time when AP 1-1 (310-1) instructed by AP 1-1 (310-1) operates as HCM. When non-AP STA 1-1 (320-1) performs EDCA backoff operations, non-AP STA 1-1 (320-1) may not increment the EDCA channel access parameters CW[AC] and QSRC[AC]. non-AP STA 1-1 (320-1) may repeatedly perform backoff operations by setting the EDCA channel access parameters CW[AC] and QSRC[AC] to initial (e.g., CW[AC] to CWmin[AC], QSRC[AC] to 0) and then selecting a backoff counter.Alternatively, non-AP STA 1-1 (320-1) may repeatedly perform backoff operations using the CW[AC] and QSRC[AC] that were last used for channel access. If the channel access operation of non-AP STA 1-1 (320-1) is completed after the point in time when AP 1-1 (310-1) is operating in HCM, non-AP STA 1-1 (320-1) may transmit an uplink frame to AP 1-1 (310-1). The non-AP STA 1-2 of the second link may perform a channel access operation to transmit an uplink frame that is synchronized with the start time of the non-AP STA 1-1 (320-1) of the first link. The non-AP STA 1-2 of the second link may complete the channel access operation (e.g., when the backoff counter reaches 0). non-AP STA 1-2 may keep the backoff counter at 0 and delay frame transmission until non-AP STA 1-1 (320-1) receives an ICR (414) from AP 1-1 (310-1). When non-AP STA 1-1 (320-1) receives an ICR (414) from AP 1-1 (310-1) and the received ICR (414) indicates that AP 1-2 of the second link is operating in Doze mode, non-AP STA 1-2 may be unable to use the second link. Therefore, non-AP STA 1-2 may discard the backoff counter that is kept at 0, and data frames may not be transmitted on the second link.

[0115] Referring to FIG. 5c, non-AP STA 1-1 (320-1) can transmit an ICF (413-1) to AP 1-1 (310-1). AP 1-1 (310-1) can transmit an ICR (414) to non-AP STA 1-1 (320-1) in response to the ICF (413-1). The ICR (414) transmitted by AP 1-1 (310-1) can indicate that AP MLD 1 operates as HCM on the first link and operates in HCM mode on the second link. The time when AP 1-2 operates as HCM on the second link may be later than the time when AP 1-1 (310-1) operates as HCM, and AP 1-1 (310-1) can indicate the time when AP 1-2 operates as HCM in the ICR (414). non-AP STA 1-1 (320-1) can receive an ICR (414) from AP 1-1 (310-1) and determine when AP 1-2 is operating as HCM. In order for non-AP STA 1-1 (320-1) and non-AP STA 1-2 to perform transmission using multiple links (i.e., using the first link and the second link simultaneously), they may need to synchronize the frame transmission start times on multiple links. In the above case, non-AP STA 1-1 (320-1) can perform a channel access operation from the time it has finished receiving the ICR (414) from AP 1-1 (310-1). Here, if the channel access operation is completed earlier than when AP 1-1 (310-1) operates as HCM (e.g., when the backoff counter reaches 0), the non-AP STA 1-1 (320-1) can keep the backoff counter at 0.

[0116] The non-AP STA 1-2 of the second link may have performed a channel access operation to transmit an uplink frame whose start time is synchronized with the non-AP STA 1-1 (320-1) of the first link. The non-AP STA 1-2 of the second link may have performed a channel access operation to transmit an uplink frame (417-1, 417-2) whose start time is synchronized with the non-AP STA 1-2 of the first link. The non-AP STA 1-1 (320-1) and non-AP STA 1-2 of the first and second links may transmit an ICF (413-1, 413-2) with the same transmission start time and transmission end time. That is, the non-AP STA 1-2 may transmit an ICF (413-2) on the second link. The non-AP STA 1-2 can transmit the ICF (413-2) and perform the channel access operation again after the PIFS. That is, it can wait until the AP 1-2 of the second link operates as an HCM. When the non-AP STA 1-2 performs the channel access operation again, the non-AP STA 1-2 can perform the channel access operation by selecting a backoff counter using the existing CW[AC] and QSRC[AC] values. Alternatively, the non-AP STA 1-2 can perform the channel access operation by selecting a backoff counter using the initialized CW[AC] and QSRC[AC] values ​​(e.g., CW[AC] initialized to CWmin[AC] and QSRC[AC] initialized to 0). The non-AP STA 1-2 of the second link can complete the channel access operation (e.g., when the backoff counter reaches 0). non-AP STA 1-2 can delay frame transmission by keeping the backoff counter at 0 until AP 1-2 operates as HCM.non-AP STA 1-1 (320-1) and non-AP STA 1-2 can transmit uplink frames (417-1, 417-2) with synchronized transmission start times to AP 1-1 (310-1) and AP 1-2 of AP MLD 1 after both AP 1-1 (310-1) and AP 1-2 have completed all channel access operations.

[0117] In the above-described FIGS. 3a to 5c, keeping the backoff counter at 0 and delaying transmission despite there being a frame to be transmitted may be an action in which the transmission queue is assumed to be empty at the time the backoff is successful, and there is a frame to be sent in the transmission queue at the time transmission is to be performed.

[0118] As another example, in FIGS. 3a to 5c described above, the ICR indicating the multi-link power saving operation of AP MLD 1 may be transmitted independently without being transmitted as a response frame of non-AP STA MLD 1. Before communicating with AP MLD 1, non-AP STA MLD 1 can check the multi-link operation status of AP MLD 1 based on the ICR received from AP MLD 1 (e.g., an ICR received as a response frame for the ICF of non-AP MLD 1 or an ICR transmitted independently by AP MLD 1 and received by non-AP MLD 1). For example, if the ICR received by non-AP STA MLD 1 from AP MLD 1 is in a first link state of awake (e.g., including LCM and HCM) and a second link state of doze, non-AP STA MLD 1 may communicate with AP MLD 1 using only the first link, or perform the ICF transmission procedure described above in FIGS. 3a to 5c.

[0119] Additionally, as an example, non-AP STA MLD 1 can perform the same operation or a similar power saving operation as AP MLD 1. non-AP STA 1-1, where non-AP STA MLD 1 operates on the first link, can operate as an LCM, and non-AP STA 1-2, where non-AP STA MLD 1 operates on the second link, can operate in a doze state. In order for AP MLD 1 to transmit a data frame to non-AP STA MLD 1, AP MLD 1 must transmit an initial control frame to the first link of non-AP STA MLD 1 as illustrated in FIGS. 3a through 5c, and may perform channel access operations on the first link and the second link. Alternatively, based on the ICR received from non-AP STA MLD 1, if the first link is in an awake state (e.g., including LCM and HCM) and the second link is in a doze state, AP MLD 1 may communicate with non-AP STA MLD 1 using only the first link, or perform the ICF transmission procedure described above in FIGS. 3a to 5c.

[0120] FIG. 6 is a diagram showing a wireless LAN network to which the present disclosure applies, and FIG. 7 is a diagram showing multiple links established between MLDs to which the present disclosure applies.

[0121] Referring to FIGS. 6 and 7, an MLD may have a single MAC (medium access control) address. The MLD may refer to an AP MLD or a non-AP STA MLD, but is not limited thereto. The MAC address of the MLD may be used in a multi-link setup procedure between a non-AP STA MLD and an AP MLD. The MAC address of the AP MLD may be different from the MAC address of the non-AP STA MLD. The AP(s) associated with the AP MLD may have different MAC addresses, and the STA(s) associated with the non-AP STA MLD may also have different MAC addresses. APs within the AP MLD with different MAC addresses may each be responsible for a link and may perform the role of an independent AP. Additionally, STAs within the non-AP STA MLD with different MAC addresses may each be responsible for a link and may perform the role of an independent STA.

[0122] For example, an MLD may support STR (simultaneous transmit and receive) operation. In the above case, the MLD may perform a transmit operation on a first link and simultaneously perform a receive operation on a second link. An MLD that supports STR operation may be referred to as an STR MLD (e.g., STR AP MLD, STR non-AP STA MLD), but is not limited to such terms. For example, a link may refer to a portion consisting of a channel, band, or other frequency range. Although the following description is based on a link, it applies equally even if the link is a channel, band, or other frequency range, and is not limited to a specific form. However, for the convenience of explanation, the description is based on a link.

[0123] Devices that do not support STR operation may be referred to as NSTR (non-STR) AP MLD or NSTR non-AP STA MLD, but are not limited to such terms.

[0124] The MLD can transmit and receive frames over multiple links by using a discontinuous bandwidth expansion method (e.g., 80 MHz + 80 MHz). Multi-link operation may include multi-band transmission. The AP MLD may include multiple APs, and the multiple APs may operate on different links. Additionally, each of the multiple APs may perform the function(s) of the lower MAC layer. Each of the multiple APs may be referred to as a "communication node" or a "subordinate entity," and the communication node (i.e., AP) may operate under the control of the upper layer (or processor).

[0125] Additionally, a non-AP STA MLD may include multiple STAs, and the multiple STAs may operate on different links. Each of the multiple STAs may be referred to as a "communication node" or a "subordinate entity," and the communication node (i.e., STA) may operate under the control of a higher layer (or processor).

[0126] The MLD can perform communication in multi-band. For example, the MLD can perform communication in the 2.4 GHz band using a 40 MHz bandwidth according to a channel expansion method (e.g., bandwidth expansion method). Additionally, the MLD can perform communication in the 5 GHz band using a 160 MHz bandwidth according to a channel expansion method. Furthermore, the MLD can perform communication in the 6 GHz band using a 160 MHz bandwidth. For example, a single frequency band (e.g., a single channel) used by the MLD can be defined as a single link. As another example, multiple links can be established within a single frequency band used by the MLD. As a specific example, the MLD can establish one link in the 2.4 GHz band and two links in the 6 GHz band. Each link may be referred to as the first link, the second link, and the third link, but this is for the convenience of explanation only and is not limited thereto. In other words, links can be established in various forms, and for the convenience of explanation below, they will be referred to as links.

[0127] An MLD (e.g., AP MLD and / or non-AP STA MLD) can establish multiple links by performing at least one of a connection procedure and a negotiation procedure for multiple link operation. When multiple links are established, the number of links and the links to be used among the multiple links can be established. A non-AP STA MLD can verify band information capable of communicating with an AP MLD. In the negotiation procedure for multiple link operation between a non-AP STA MLD and an AP MLD, a non-AP STA MLD can configure one or more links among those supported by the AP MLD to be used for multiple link operation. A STA that does not support multiple link operation (e.g., IEEE 802.11a / b / g / n / ac / ax STA) can be connected to one or more links among the multiple links supported by the AP MLD. If the band spacing between multiple links (e.g., the band spacing between a first link and a second link in the frequency domain) is sufficient, the MLD can perform an STR operation. For example, an MLD can transmit a PPDU (PLCP (physical layer convergence procedure) protocol data unit) 1 using the first link among multiple links and receive a PPDU 2 using the second link among multiple links. On the other hand, if the bandwidth between multiple links is insufficient, in-device coexistence (IDC) interference, which is interference between multiple links, may occur if the MLD performs an STR operation. Therefore, if the bandwidth between multiple links is insufficient, the MLD may not be able to perform an STR operation.

[0128] For example, multiple links including a first link, a second link, and a third link may be established between an AP MLD and a non-AP STA MLD 1. If the bandwidth between the first link and link 3 is sufficient, the AP MLD can perform an STR operation using the first link and the third link. That is, the AP MLD can transmit a frame using the first link while simultaneously receiving a frame using the third link. On the other hand, if the bandwidth between the first link and the second link is insufficient, the AP MLD may not be able to perform an STR operation using the first link and the second link. Alternatively, if the bandwidth between the second link and the third link is insufficient, the AP MLD may not be able to perform an STR operation using the second link and the third link.

[0129] In addition, the following describes the configuration and execution methods for dynamic power saving (DPS) performed across multiple links. While the following description of DPS configuration and execution methods is based on UHR OMN (operating mode notification) frames, it is not limited to this. For example, UHR OMP (operating mode and parameters) frames may be used instead of UHR OMN frames for DPS configuration and execution. Specifically, UHR OMP request frames may be used instead of UHR OMN request frames, and UHR OMP response frames may be used instead of UHR OMN response frames.

[0130] Here, the UHR OMP frame may be the UHR Link Reconfiguration frame itself. As another example, the UHR OMP frame may be any one of the messages, indicators, modes of operation, elements, fields, and other forms within the UHR Link Reconfiguration frame, and is not limited to a specific form. For the convenience of explanation, the following description is based on the UHR OMN frame, but it is self-evident that this applies equally to the UHR OMP frame.

[0131] FIG. 8 is a diagram illustrating a dynamic power saving operation method applied to the present disclosure.

[0132] In a wireless LAN network, AP 1 (510) and non-AP STA 1, which is associated with AP 1, may operate. In a wireless LAN network, at least one of AP 1 (510) and non-AP STA 1 (520) may perform dynamic power saving (DPS). Here, dynamic low-power operation may be determined through negotiation between AP 1 (510) and non-AP STA 1 (520). During the association procedure between AP 1 (510) and non-AP STA 1 (520), capability information of AP 1 (510) and non-AP STA 1 (520) may be exchanged. AP 1 (510) and non-AP STA 1 (520) may perform negotiation on whether to use DPS operation based on the exchanged capability information. For example, AP 1 (510) can perform operations to support non-AP STA 1 (520) when it uses DPS (e.g., an initial control frame (ICF) transmission operation, a frame transmission operation according to the capability mode (low capability mode / high capability mode) of non-AP STA 1 (520). In the above case, AP 1 (510) sets the DPS assisting support bit of the UHR MAC Capabilities Information field of the UHR (ultra high reliability) capabilities element included in at least one frame among the frames exchanged in the connection procedure with non-AP STA 1 (520) to 1.

[0133] For example, non-AP STA 1 (520) can perform a transition between low capability mode and high capability mode based on DPS operation. Additionally, non-AP STA 1 (520) can respond with an initial control response (ICR) to the AP's ICF based on DPS operation. Additionally, non-AP STA 1 (520) can perform other operations based on DPS, but is not limited to a specific form. In the above case, non-AP STA 1 (520) sets the DPS support bit of the UHR MAC Capabilities Information field of the UHR capabilities element included in at least one frame among the frames exchanged during the connection procedure with AP 1 (510) to 1.

[0134] When the information described above is exchanged, non-AP STA 1 (520) can recognize that AP 1 (510) supports the DPS of non-AP STA 1 (520). Additionally, AP 1 (510) can recognize that non-AP STA 1 (520) is capable of performing DPS operations. That is, AP 1 (510) and non-AP STA 1 (520) can negotiate for DPS support.

[0135] After the negotiation process described above, non-AP STA 1 (520) may want to perform a DPS operation. If non-AP STA 1 (520) wants to perform a DPS operation, non-AP STA 1 (520) may send a UHR OMN (operating mode notification) frame (601) to AP 1 (510). The UHR OMN frame (601) may contain parameters for non-AP STA 1 (520) to perform a DPS operation. Specifically, the UHR OMN frame (601) may include a UHR control field and a DPS Operation Parameters field. The UHR control field may indicate whether the DPS is enabled (or disabled). The DPS operation parameters may include a DPS padding delay, which is the time involved in the non-AP STA 1 (520) performing the DPS operation switching from LCM (lower capability mode) to HCM (higher capability mode), and a DPS switching delay, which is the time involved in the non-AP STA 1 (520) switching from HCM to LCM. The DPS operation may be initiated after the non-AP STA 1 (520) transmits a UHR OMN frame (601) to AP 1 (510) and a certain amount of time has passed. As another example, the DPS operation may be initiated when the non-AP STA 1 (520) transmits a UHR OMN frame to AP 1 (510) and then receives a UHR OMN frame (602) from AP 1 (510).For example, the UHR OMN frame (601) may be a UHR OMN Request frame or a UHR OMP Request frame, and the UHR OMN frame (602) may be a UHR OMN Response or a UHR OMP Response. That is, the UHR OMN frame (601) is a UHR OMP Request. The UHR OMN frame (602) is a UHR OMP Response.

[0136] For example, when non-AP STA 1 (520) initiates DPS operation, it may operate in LCM mode. That is, when non-AP STA 1 (520) initiates DPS operation, the default operation mode is LCM. As another example, when non-AP STA 1 (520) initiates DPS operation, it may operate in HCM mode until it receives a frame from AP 1 (510), and then operate in LCM mode after it has finished receiving a frame from AP 1 (510). As a specific example, if non-AP STA 1 (520) receives a frame that requires an acknowledgment frame transmission according to the acknowledgment policy (Ack policy) of the frame received from the AP, non-AP STA 1 (520) may switch from HCM to LCM after waiting for time Tt after the transmission of the acknowledgment frame is completed (or after the reception of the frame is completed if it receives a frame that does not require an acknowledgment frame transmission).

[0137] DPS operation may be referred to as dynamic low-power operation. The power saving mode available during dynamic power saving operation may be a lower capability mode (LCM) with fewer restrictions than Dose mode. In LCM, the AP and STA may be limited in at least one of the operating bandwidth, the number of spatial streams (Nss), and the modulation and coding scheme (MCS). Alternatively, in LCM, the AP and STA may be able to receive only frames of a specific format. For example, a frame of a specific format may be an initial control frame (ICF), but is not limited thereto. The initial control frame may be a BlockAck request (BAR) frame, a multi-user request to send (MU) trigger frame, or a buffer status report poll (BSRP) trigger frame, but is not limited thereto. In the LCM, as described above, frame transmission and reception may be possible in which constraints according to at least one of the limited operating bandwidth, the number of operating space streams, and the MCS are satisfied.

[0138] Another power saving mode available during dynamic power saving operation may be Higher Capability Mode (HCM). When operating in HCM, the wireless LAN terminal can perform normal data transmission and reception, and the operating bandwidth and operating spatial stream may not be limited. Based on the above, power consumption may be lower when operating in LCM than when operating in HCM. Additionally, the following description is based on non-AP STA, but this applies equally to AP STA. However, for the convenience of explanation, the description is based on non-AP STA.

[0139] An AP or STA operating in DPS mode may receive an ICF (603) in LCM mode. When an AP or STA receives an ICF (603), the AP or STA may operate in HCM mode. Here, a separate transition time or switch time may be required for the AP or STA to switch from LCM mode to HCM mode. For example, a padding field present in the ICF (603) may be included corresponding to the time described above. That is, the padding field may be a field intended to extend the time length of the frame and ensure a transition time or switch time. Thus, the length of the padding field may be a time corresponding to or greater than the transition time (or switch time). Here, a DPS padding delay field included in the UHR OMN frames (601, 602) exchanged between non-AP STA 1 and AP 1 (510) may indicate the transition time (or switch time). An AP or STA operating as HCM upon receiving an ICF (603) may transmit an ICR (initial control response) frame (604) (which may be abbreviated as ICR). After the ICF and ICR exchange procedure is completed, the AP or STA operating as HCM may complete frame transmission and reception. When frame transmission and reception is completed, the AP or STA may switch from HCM to LCM and operate. A separate transition time (or switching time) may be required for the AP or STA to switch from HCM to LCM and operate. A DPS switching delay field included in the UHR OMN frame exchanged between non-AP STA 1 (520) and AP 1 (510) may indicate the aforementioned transition time (or switching time). For example, the AP or STA may have at least one of the operating bandwidth and the operating space stream limited during the corresponding transition time (or switching time). As another example, an AP or STA may be able to receive only frames of a specific format during the corresponding transition time (or switching time).As another example, an AP or STA may be able to receive only frames of a specific format during the corresponding transition time (or switching time). Alternatively, an AP or STA may be able to transmit only frames of a specific format during the corresponding transition time (or switching time).

[0140] Referring to FIG. 8, non-AP STA 1 (520) can perform a DPS operation. In the above case, AP 1 (510) can perform a channel access operation. The channel access operation may be an enhanced distributed channel access (EDCA) operation, and if the channel access operation is successful, a transmit opportunity (TXOP) can be obtained, which is a time interval for transmitting a frame. The TXOP can be obtained from the entire bandwidth available to AP 1 (510) (e.g., 40 MHz, 80 MHz, 160 MHz, 320 MHz, etc.). For example, since non-AP STA 1 (520) operates as an LCM based on the DPS operation, the receiving bandwidth of non-AP STA 1 (520) may be limited (e.g., limited to 20 MHz). AP 1 (510) can transmit an ICF duplicated in 20 MHz increments to non-AP STA 1 (520) to occupy the entire bandwidth of the TXOP acquired by AP 1 (510) while enabling non-AP STA 1 (520) to receive frames. The ICF duplicated in 20 MHz increments can be transmitted duplicated for the bandwidth of the TXOP acquired by the AP. Here, the ICF can instruct non-AP STA 1 (520) on bandwidth information. The bandwidth information may be instructed by a Bandwidth Signaling TA set in the transmitter address (TA) of the MAC header included in the ICF, or by the L-SIG field of the PHY preamble and other fields. Alternatively, the bandwidth information may be instructed through a combination of the Bandwidth Signaling TA set and the L-SIG field of the PHY preamble.

[0141] The format of the ICF may be a Non-HT (high throughput) Duplicate PPDU format, and the ICF may be a trigger frame (e.g., a BSRP (buffer status report poll) trigger frame, a MU-RTS (multi-user request to send) trigger frame). The ICF may include a padding field that guarantees a transition time that allows non-AP STA 1 (520) to operate from LCM to HCM, and the transition time may be a DPS padding delay. Upon receiving the ICF, non-AP STA 1 (520) may switch the operation mode from LCM to HCM, and non-AP STA 1 (520) that has switched the operation mode to HCM may send an ICR to AP 1 (510). After that, AP 1 (510) may send a data frame to non-AP STA 1 (520). Since non-AP STA 1 (520) operates as an HCM, AP 1 (510) can transmit data frames in the full bandwidth, full spatial stream, and full frame format supported by non-AP STA 1 (520). That is, the AP can perform normal data transmission and reception, and the operating bandwidth and operating spatial stream are not limited. non-AP STA 1 (520) can receive data frames from AP 1 (510) and can also transmit a response frame (BlockAck frame). When non-AP STA 1 (520) completes receiving a frame from AP 1 (510) and the frame is a frame that does not require a response frame (or when non-AP STA 1 (520) completes receiving a frame from AP 1 (510) and completes sending a response frame by requesting a response frame), non-AP STA 1 (520) may wait for the next frame received from AP 1 (510) for a certain period of time (e.g., aSIFSTime + aSlotTime + aRxPHYStartDelay time).The above time may be referred to as Tw time. If no frame is detected during the Tw time (e.g., if no PHY-RXSTART.indication primitive occurs), non-AP STA 1 (520) may switch the operation mode from HCM to LCM, which may be the end of HCM operation, but is not limited to that term.

[0142] When non-AP STA 1 (520) switches from HCM to LCM, a separate switching time may occur. The separate switching time may be a DPS switching delay, which may be referred to as Tt. non-AP STA 1 (520) may operate in LCM after the switching time Tt. During the switching time that occurs when non-AP STA 1 (520) switches from HCM to LCM, non-AP STA 1 (520) may receive frames that are receivable in LCM (e.g., frames in which at least one of bandwidth, spatial stream, or format is limited or fixed). The above-described operation may be applied in the same or similar way to non-AP STA 1 (520) AP 1 (510) (i.e., when the STA transmits to the AP).

[0143] Also, Tw time is the following<Tw 조건 1> ,<Tw 조건 2> and<Tw 조건 3> It can start if one of the cases is satisfied.

[0144]

[0145] <Tw 조건 1>

[0146] If the PPDU transmitted by the STA is a response to the most recently received frame from the AP, it starts at the time the transmission of the PPDU is completed.

[0147]

[0148] <Tw 조건 2>

[0149] If the PPDU received from an AP or another STA contains a frame that does not require an immediate response, start at the time the reception of the PPDU is complete.

[0150]

[0151] <Tw 조건 3>

[0152] If the PPDU transmitted by the STA includes a frame that does not require an immediate response, it starts at the time the transmission of the PPDU is completed.

[0153]

[0154] non-AP STA 1 (520) performs the following for the duration of Tw when Tw is initiated after the completion of reception of the initial control frame<LCM 전환> When the conditions are met, it no longer operates as an HCM and switches to an LCM.

[0155] <LCM 전환>

[0156] - The MAC layer of STA 1 does not receive the PHY-RXSTART.indication primitive from the PHY layer and does not send the PHY-TXSTART.request primitive.

[0157] - The MAC layer of STA 1 does not receive the PHY-TXSTART.confirm primitive from the PHY layer.

[0158] - There is no nonempty transmit queue in STA 1.

[0159] - STA 1 does not intend to transmit a frame or schedule transmission

[0160]

[0161] <LCM 전환>In the conditions, the MAC layer of non-AP STA 1 (520) receiving the PHY-RXSTART.indication primitive from the PHY layer may mean that non-AP STA 1 (520) detects a frame being received. Additionally, the MAC layer of non-AP STA 1 (520) may mean that it detects a frame sending the PHY-TXSTART.request primitive to the PHY layer. The MAC layer of non-AP STA 1 (520) receiving the PHY-TXSTART.confirm primitive from the PHY layer may mean that non-AP STA 1 (520) intends to start transmitting a frame.

[0162] Also, as an example, non-AP STA 1 (520) receives the PHY-RXSTART.indication primitive within Tw time.<LCM 전환> Even if the conditions are not met, the following<LCM 전환 - 수신> If the conditions are met, it may need to operate as an LCM instead of an HCM.<LCM 전환> Without satisfying the conditions<LCM 전환 - 수신> If the conditions are not met, non-AP STA 1 (520) may have to operate as HCM without switching to LCM.

[0163] <LCM 전환 - 수신>

[0164] - If the MAC layer of STA 1 receives the PHY-RXSTART.indication primitive from the PHY layer, and the recipient of the received frame is not STA 1

[0165] - When the MAC layer of STA 1 receives the PHY-RXSTART.indication primitive from the PHY layer and the received frame is a trigger frame

[0166] - If the received trigger frame does not allocate a RU (resource unit) for STA 1

[0167] - When the MAC layer of STA 1 receives the PHY-RXSTART.indication primitive from the PHY layer and the received frame is a CTS (clear to send) frame

[0168] - If the receiver address (RA) of the CTS frame is not the address of the AP connected to STA 1 (i.e., the address of AP 1 (510))

[0169]

[0170] The aforementioned<LCM 전환> and<LCM 전환 - 수신> The PPDU defined in the conditions may be a PHY layer frame (physical layer frame), and the physical layer frame may include an MPDU (MAC protocol data unit), which is a MAC layer frame.

[0171] Referring to FIG. 8, the non-AP STA MLD 1 operating on the first link may be non-AP STA 1 (520), the non-AP STA operating on the second link may be non-AP STA 2, and the non-AP STA operating on the third link may be non-AP STA 3. The AP MLD 1 operating on the first link may be AP 1 (510), the AP operating on the second link may be AP 2 (530), and the AP operating on the third link may be AP 3.

[0172] Here, non-AP STA MLD 1 may perform different DPS operations depending on the link. For example, if the STA MLD has a first link, a second link, and a third link, non-AP STA 1 (520) and non-AP STA 2 may perform DPS operations, while non-AP STA 3 may not perform DPS operations. DPS settings for multiple links may be set by the exchange of UHR OMN frames between MLDs. For example, the exchange of UHR OMN frames between non-AP STA MLD 1 and AP MLD 1 may be performed between non-AP STA 1 (520) and AP 1 (510) of the first link. Alternatively, the exchange of UHR OMN frames between non-AP STA MLD 1 and AP MLD 1 may be such that the non-AP STA 1 (520) of the first link transmits to AP 1 (510), and AP 2 (530) of AP MLD 1 transmits a UHR OMN frame in response to the non-AP STA 2 of non-AP STA MLD 1.

[0173] When DPS settings for multiple links are configured via UHR OMN frame exchange between MLDs, the UHR control field of the UHR OMN frame may include a link identifier (e.g., link ID bitmap, link ID) performing the DPS operation and DPS operation parameters for each link (e.g., DPS padding delay and DPS switching delay). For example, the link identifier may indicate a first link and a second link, which are the links where the DPS operation is performed. In this case, the number of DPS operation parameter fields containing DPS operation parameters (e.g., DPS padding delay and DPS switching delay) is equal to the number of links using DPS. That is, DPS operation parameter fields for each link may be included in the UHR OMN frame in correspondence with the number of links using DPS. The DPS operation parameter field for each link indicates the respective DPS operation parameters (e.g., DPS padding delay and DPS switching delay) of the STAs operating on the links where the DPS operation of the non-AP STA MLD 1 is used (e.g., non-AP STA 1 (520) operating on the first link of the non-AP STA MLD 1 and non-AP STA 2 (540) operating on the second link). In addition, the DPS operation parameters can be configured in various ways by multi-link operation, and for example, if the DPS operation parameters are the same in the first link and the second link, a single DPS operation parameter field may be included in the UHR OMN frame. That is, a separate DPS operation parameter field for each link may be included in the UHR OMN frame, but if the DPS operation parameters are the same in each link, it may also be possible to include a single DPS operation parameter field in the UHR OMN frame. However, this is not limited to the above embodiment.

[0174] Meanwhile, a third link for which a DPS operation is not performed may be indicated in a UHR OMN frame. If Non-AP STA MLD 1 does not intend to perform a DPS operation on the third link, the link identifier may indicate the first link and the second link, which are links for which a DPS operation is performed, but may not indicate the link identifier of the third link. Additionally, the DPS operation parameters of the third link are not indicated. Alternatively, Non-AP STA MLD 1 may indicate the first link and the second link, which are links for which a DPS operation is performed, and the third link for which a DPS operation is not performed, but may indicate in the DPS operation parameters of the third link that the third link does not use a DPS operation, or exclude the DPS operation parameters of the third link.

[0175] Additionally, if the STA MLD has a first link and a second link, the non-AP STA 1 (520) may perform a DPS operation, and the non-AP STA 2 may not perform a DPS operation. The DPS setting for multiple links may be set by the exchange of UHR OMN frames between MLDs. For example, the exchange of UHR OMN frames between the non-AP STA MLD 1 and the AP MLD 1 may be performed between the non-AP STA 1 (520) and the AP 1 (510) of the first link. Alternatively, the exchange of UHR OMN frames between the non-AP STA MLD 1 and the AP MLD 1 may be performed by the non-AP STA 1 (520) of the first link transmitting to the AP 1 (510), and the AP 2 (530) of the AP MLD 1 transmitting a UHR OMN frame in response to the non-AP STA 2 of the non-AP STA MLD 1.

[0176] When DPS settings for multiple links are configured via UHR OMN frame exchange between MLDs, the UHR control field of the UHR OMN frame may include a link identifier (e.g., link ID bitmap, link ID) that performs the DPS operation. For example, the link identifier may include the link identifier of a first link, which is the link where the DPS operation is performed, and may not include the link identifier of a second link, which is the link where the DPS operation is not performed. Here, the UHR OMN frame may include only the DPS operation parameters for the first link and may not include the operation parameters for the second link.

[0177] As another example, the UHR OMN frame may include respective link identifiers indicating a first link where a DPS operation is performed and a second link where a DPS operation is not performed. Here, the UHR OMN frame may not indicate DPS operation parameters for the second link where a DPS operation is not performed, or it may separately indicate that the second link does not perform a DPS operation. Through the above description, it can be recognized that a DPS operation is not performed on the second link.

[0178] For convenience of explanation, the present disclosure describes multiple links based on two or three links, but it may be applied equally even if there are more links, and the operation may not be limited to two or three links. As another example, DPS settings for multiple links may be performed individually for each link. If non-AP STA MLD 1 intends to perform DPS operations on the first link and the second link, non-AP STA 1 (520) and AP 1 (510) of the first link may exchange UHR OMN frames, and non-AP STA 2 and AP 2 (530) of the second link may exchange UHR OMN frames. As an example, the above-described matters may be applied in FIGS. 9 to 12 below and may be modified according to each operation.

[0179] FIG. 9 is a diagram illustrating a dynamic low-power operation method in multiple links applicable to the present disclosure.

[0180] Referring to FIG. 9, one can consider a non-AP STA 1 (520) of a non-AP STA MLD 1 operating in the first link and an AP 1 (510) of an AP MLD 1. As another example, the non-AP STA 1 (520) may be a STA not included in the MLD. Alternatively, the AP 1 (510) may be an AP not included in the MLD and is not limited to a specific form.

[0181] UHR OMN frame exchange can be initiated through the DPS setup procedure. By non-AP STA 1 (520) transmitting a UHR OMN frame (601) to AP 1 (510) and AP 1 (510) transmitting a UHR OMN frame (602) back to non-AP STA 1 (520), non-AP STA 1 (520) can initiate a DPS operation on the first link, and AP 1 (510) can support the DPS operation of non-AP STA 1 (520). For example, non-AP STA 1 (520) may be a DPS STA and AP 1 (510) may be a DPS Assisting AP, but is not limited thereto. Additionally, according to the DPS setup procedure, AP 1 (510) can recognize the DPS padding delay and DPS switching delay information of non-AP STA 1 (520).

[0182] non-AP STA 1 (520) can transmit a data frame to AP 1 (510) by performing channel access operations (e.g., EDCA backoff operation and EDCA TXOP acquisition procedure) in LCM mode. In the above case, non-AP STA 1 (520) can acquire a TXOP (transmit opportunity), which is a time interval during which multiple frames can be transmitted. For example, the data frame may be transmitted in accordance with constraints according to at least one of the limited bandwidth, limited NSS, and limited MCS according to LCM. The data frame transmitted by non-AP STA 1 (520) may be transmitted with a bandwidth of 20 MHz, and the data frame may be an MPDU (MAC protocol data unit). Here, non-AP STA 1 (520) may switch from LCM to HCM and operate after transmitting the first data frame. The MPDU may include a MAC header, and the non-AP STA 1 (520) may use the MAC header to request time for HCM switching from the AP 1 (510), the recipient of the data frame. For example, the non-AP STA 1 (520) may transmit by including single response scheduling (SRS) information in the MAC header. The SRS information may be information that specifies the length of the response frame for a frame containing the SRS information. That is, it may specify the length of the response frame (606) for a data frame (605) containing the SRS information. The non-AP STA 1 (520) may perform transmission by including the SRS information in the data frame (605) transmitted to the AP 1 (510). The time length indicated by the SRS information may be greater than or equal to 'AP 1's expected maximum response frame length' + 'DPS padding delay' time.The 'expected maximum response frame length of AP 1' can be calculated based on the length of the BlockAck session and data frame established by non-AP STA 1 (520) with AP 1 (510). The SRS information may further include an indicator requesting a transition from LCM to HCM by non-AP STA 1 (520). AP 1 (510) receives a data frame (605) transmitted by non-AP STA 1 (520) and can check the SRS information in the MAC header of the data frame (605) transmitted by non-AP STA 1 (520). AP 1 (510) can adjust the length of the response frame (frame containing a BlockAck frame, 606) to be transmitted to non-AP STA 1 (520) based on the SRS information.

[0183] AP 1 (510) receives a data frame (605) and can transmit a response frame (606) to non-AP STA 1 (520). The response frame (606) may include a BlockAck frame indicating the reception status of the data frame received from non-AP STA 1 (520). Additionally, A (aggregated)-MPDU EOF (end of frame) padding may be included in the response frame to adjust the length of the response frame (606) to match the length of the response frame included in the SRS information transmitted by non-AP STA 1 (520) to AP 1 (510). Alternatively, a BlockAck frame and at least one QoS (quality of service) Null frame may be concatenated in the form of an A-MPDU to form the response frame. Here, at least one QoS Null frame may be padding. The padding described above may be bits for extending the length of the frame. While padding is being transmitted, a receiver (e.g., non-AP STA 1 (520)) receiving a frame containing padding can change its operating state. Additionally, AP 1 (510) can recognize that non-AP STA 1 (520) is transitioning from LCM to HCM while the response frame transmitted by AP 1 (510) is being transmitted if the SRS information in the MAC header of the data frame transmitted by non-AP STA 1 (520) is longer than the response frame that AP 1 (510) intends to transmit (e.g., if it is longer by the DPS padding delay than the length of AP 1's original response frame) or if the SRS information contains an indicator that non-AP STA 1 (520) is requesting a transition from LCM to HCM.

[0184] non-AP STA 1 (520) can receive a padded response frame (606) from AP 1 (510). Specifically, non-AP STA 1 (520) receives a BlockAck frame included in the response frame (606), and then non-AP STA 1 (520) can perform a transition from LCM to HCM. non-AP STA 1 (520) can operate in HCM after the end of transmission of the response frame from AP 1 (510). That is, non-AP STA 1 (520) can transmit frames using at least one of the unlimited bandwidth, NSS, and MCS within the capabilities of non-AP STA 1 (520). However, since the bandwidth of the data frame initially transmitted by non-AP STA 1 (520) is 20 MHz, additional channel access methods may be required for non-AP STA 1 (520) to transmit using a wider bandwidth. As another example, non-AP STA 1 (520) can transmit frames to AP 1 (510) using at least one of unrestricted NSS and MCS instead of using wide bandwidth, and is not limited to a specific form.

[0185] When non-AP STA 1 (520) operates in HCM mode to extend the bandwidth of frames transmitted to AP 1 (510), non-AP STA 1 (520) receives a response frame from AP 1 (510) and, instead of transmitting additional data frames after SIFS (short interframe space), can transmit frames after PIFS (priority interframe space), which is a longer time than SIFS. During PIFS time, non-AP STA 1 (520) can perform channel sensing operations on the entire channel where non-AP STA 1 (520) can operate. Based on channel sensing operations, if non-AP STA 1 (520) can transmit additional data frames with a bandwidth wider than 20 MHz (e.g., if the wide bandwidth channel is idle during PIFS time), non-AP STA 1 (520) can transmit data frames to AP 1 (510) using the wide bandwidth (e.g., bandwidth greater than 40 MHz). On the other hand, if non-AP STA 1 (520) can only use a 20 MHz channel, non-AP STA 1 (520) may have to transmit data frames using only a 20 MHz bandwidth. Here, at least one of the NSS and MCS of the data frames additionally transmitted by non-AP STA 1 (520) to AP 1 (510) may be set higher than the data frame initially transmitted by non-AP STA 1 (520) to AP 1 (510), thereby enabling non-AP STA 1 (520) to transmit more data to AP 1 (510) in the same amount of time.

[0186] As another example, to extend the bandwidth of frames transmitted to AP 1 (510) after non-AP STA 1 (520) operates in HCM mode, non-AP STA 1 (520) may receive a response frame from AP 1 (510) and, instead of transmitting additional data frames after SIFS (short interframe space), perform a new channel access procedure (EDCA backoff operation and EDCA TXOP acquisition procedure). While the channel access procedure is being performed, non-AP STA 1 (520) may perform a channel sensing operation over the entire operable channel. Based on the channel sensing operation, if non-AP STA 1 (520) can transmit additional data frames with a bandwidth wider than 20 MHz (e.g., if a wide-bandwidth channel is idle during PIFS time), non-AP STA 1 (520) may transmit data frames to AP 1 (510) using the wide bandwidth (e.g., bandwidth greater than 40 MHz). If non-AP STA 1 (520) can only use a 20 MHz channel, non-AP STA 1 (520) may need to transmit data frames using only a 20 MHz bandwidth. However, at least one of the NSS and MCS of the data frames additionally transmitted by non-AP STA 1 (520) to AP 1 (510) may be set higher than the data frame initially transmitted by non-AP STA 1 (520) to AP 1 (510), and non-AP STA 1 (520) may be able to transmit more data to AP 1 (510) in the same amount of time. Even when transmitting over a wider bandwidth by performing the new channel access procedure described above, the total number of TXOPs that can be transmitted may be limited to the initially set TXOP. Here, the limitation to the TXOP may be because other STAs may have set the Network Allocation Vector (NAV) based on the initially set TXOP, thereby increasing the channel access success rate.

[0187] As another example, if non-AP STA 1 (520) operates in HCM mode and expands the bandwidth of frames transmitted to AP 1 (510), non-AP STA 1 (520) receives a response frame from AP 1 (510) and can transmit additional data frames after the SIFS (short interframe space). Here, non-AP STA 1 (520) can transmit data frames to AP 1 (510) using a wide bandwidth (e.g., bandwidth of 40 MHz or more) after the SIFS time.

[0188] AP 1 (510) receives an additional data frame from non-AP STA 1 (520) and can send a response frame to non-AP STA 1 (520). After the transmission of the additional data frame is complete, non-AP STA 1 (520) may no longer have any data frames to transmit. That is, the TXOP of non-AP STA 1 (520) may be terminated. If the additional data frame is a frame that does not require a response frame from AP 1 (510), non-AP STA 1 (520)<Tw 조건 3> The Tw time (waiting time) can be started by.

[0189] Or, if non-AP STA 1 (520) is a frame where additional data frames are frames that require a response frame from AP 1 (510),<Tw 조건 2> The Tw time (waiting time) can be started by... Within the Tw time<LCM 전환> If the condition is met, non-AP STA 1 (520) can operate as LCM again after the DPS switching delay time. Within the Tw time, non-AP STA 1 (520) receives the PHY-RXSTART.indication primitive<LCM 전환> Even if the conditions are not met<LCM 전환 - 수신> If the conditions are met, it does not operate as HCM and can return to LCM after the DPS switching time.

[0190] FIG. 10 is a diagram illustrating a dynamic low-power operation method in multiple links applicable to the present disclosure.

[0191] Referring to FIG. 10, a case can be considered in which non-AP STA 1 of non-AP STA MLD 1 operates on the first link and non-AP STA 2 of non-AP STA MLD 1 operates on the second link. Additionally, AP 1 (510) of AP MLD 1 operates on the first link and AP 2 (530) of AP MLD 1 operates on the second link. Here, for non-AP STA MLD 1, the first link and the second link may be a non-simultaneous transmit and receive (NSTR) link pair.

[0192] The above-described DPS setup procedure can be initiated through the exchange of UHR OMN frames. A DPS operation between AP MLD 1 and non-AP STA MLD 1 can be established by the non-AP STA 1 of non-AP STA MLD 1 transmitting a UHR OMN frame (601) to AP 1 (510), and AP 1 (510) of AP MLD 1 transmitting a UHR OMN frame (602) back to non-AP STA 1. Specifically, a DPS operation can be established on the first link and the second link of non-AP STA MLD 1. That is, a multi-link DPS setup can be performed. According to the multi-link DPS setup, the non-AP STA 1 on the first link can initiate a DPS operation, and AP 1 (510) can support the DPS operation of the non-AP STA 1. non-AP STA 1 is a DPS STA, and AP 1 (510) may be a DPS assisting AP. Additionally, non-AP STA 2 may initiate a DPS operation on the second link, and AP 2 (530) may support the DPS operation of non-AP STA 2. non-AP STA 2 is a DPS STA, and AP 2 (530) may be a DPS assisting AP.

[0193] According to the multi-link DPS configuration described above, AP MLD 1 can recognize a common DPS padding delay and a DPS switching delay in the first link and the second link of non-AP STA MLD 1. Alternatively, AP MLD 1 can recognize different DPS padding delays and DPS switching delays in the first link and the second link of non-AP STA MLD 1, respectively. Alternatively, it can recognize the same DPS padding delay and DPS switching delay in the first link and the second link of non-AP STA MLD 1.

[0194] Here, the first link where non-AP STA 1 of non-AP STA MLD 1 operates and the second link where non-AP STA 2 of non-AP STA MLD 1 operates may be an NSTR Link Pair (NSTR Link Pair). Therefore, in order for non-AP STA MLD 1 to transmit frames simultaneously on the first link and the second link, the start and end times of the frame transmitted on the first link and the frame transmitted on the second link may need to be synchronized. non-AP STA 1 and non-AP STA 2 may perform channel access operations in LCM mode. The channel access operation of non-AP STA 1 (520) may be completed first (e.g., the backoff counter reaches 0), and the channel access operation of non-AP STA 2 may not be completed even after the channel access operation of non-AP STA 1 (520) is completed. Since non-AP STA 1 (520) and non-AP STA 2 must transmit frames simultaneously, non-AP STA 1 (520) may keep the backoff counter at 0 and not perform frame transmission until the channel access operation of non-AP STA 2 is completed. After that, when the channel access operation of non-AP STA 2 is completed, non-AP STA 1 (520) may perform frame transmission simultaneously with non-AP STA 2. In the above case, non-AP STA 1 (520) and non-AP STA 2 may acquire a TXOP (transmit opportunity), which is a time interval during which multiple frames can be transmitted on each of the first link and the second link.

[0195] non-AP STA 1 (520) and non-AP STA 2 can transmit data frames in LCM. The data frames can be transmitted in accordance with constraints according to at least one of the limited bandwidth, limited NSS, and limited MCS according to the LCM described above. For example, the data frames transmitted by non-AP STA 1 (520) can be transmitted with a bandwidth of 20 MHz. The data frames may be MPDUs (MAC protocol data units). non-AP STA 1 (520) and non-AP STA 2 may want to operate from LCM to HCM after transmitting the first data frame. Here, the MPDU may include a MAC header, and non-AP STA 1 (520) and non-AP STA 2 may use the MAC header to request time for HCM transition from AP 1 (510) and AP 2 (530), the recipients of the data frames. Here, non-AP STA 1 (520) and non-AP STA 2 can perform transmission by including SRS (single response scheduling) information in the MAC header.

[0196] SRS information may be information that specifies the length of a response frame (608-1, 608-2) for a frame (607-1, 607-2) containing SRS information. That is, it may specify the length of a response frame (608-1, 608-2) for a data frame (607-1, 607-2) containing SRS information. Each of non-AP STA 1 (520) and non-AP STA 2 may transmit the SRS information by including it in a data frame (607-1, 607-2) that is transmitted to AP 1 (510) and AP 2 (530), respectively. Here, if the DPS padding delay of non-AP STA 1 (520) and non-AP STA 2 is the same, the time length indicated by the SRS information in the first link and the second link may be longer than or equal to 'the longer of the expected maximum response frame length of AP 1 or the maximum response frame length of AP 2 (530)' + 'DPS padding delay' time. If the DPS padding delay of non-AP STA 1 (520) and non-AP STA 2 is different, the time length indicated by the SRS information in the first link and the second link may be longer than 'the longer of the expected maximum response frame length of AP 1 or the maximum response frame length of AP 2 (530)' + 'the longer of the DPS padding delay of non-AP STA 1 or the DPS padding delay of non-AP STA 2'. The above-described action may be an action to request sufficient time from the AP for both non-AP STA 1 (520) and non-AP STA 2 to transition from LCM to HCM. The 'estimated maximum response frame length of AP 1' and the 'estimated maximum response frame length of AP 2 (530)' may be calculated based on the length of the BlockAck session and data frame established by non-AP STA 1 (520) and non-AP STA 2 with AP 1 (510) and AP 2 (530).

[0197] Additionally, the SRS information may further include an indicator requesting non-AP STA 1 (520) and non-AP STA 2 to switch from LCM to HCM. AP 1 (510) and AP 2 (530) can receive data frames transmitted by non-AP STA 1 (520) and non-AP STA 2. Additionally, AP 1 (510) and AP 2 (530) can check the SRS information in the MAC header of the data frames (607-1, 607-2) transmitted by non-AP STA 1 (520) and non-AP STA 2. AP 1 (510) and AP 2 (530) can adjust the length of the response frame (frame including a BlockAck frame) to be transmitted to non-AP STA 1 (520) and non-AP STA 2 based on the SRS information. After that, AP 1 (510) can send a response frame to non-AP STA 1 (520), and AP 2 (530) can also send a response frame to non-AP STA 2. Here, the start time of the response frames sent by AP 1 (510) and AP 2 (530) may be the same. Also, the end time of the transmission of the response frames sent by AP 1 (510) and AP 2 (530) may be the same. The fact that the start time of the response frames sent by AP 1 (510) and AP 2 (530) is the same may be because the end time of the transmission of the data frames sent by non-AP STA 1 (520) and non-AP STA 2 of non-AP STA MLD 1 to AP 1 (510) and AP 2 (530), respectively, is the same. The end time of transmission of the response frame transmitted by AP 1 (510) and AP 2 (530) may be the same because the length of the response frame indicated by the SRS information in the MAC header of the data frame transmitted by non-AP STA 1 (520) and non-AP STA 2 to AP 1 (510) and AP 2 (530) is the same.

[0198] The response frames transmitted by each of AP 1 (510) and AP 2 (530) may include a BlockAck frame indicating the reception status of a data frame received from non-AP STA 1 (520). Additionally, the length of the response frame may be adjusted to match the length of the response frame included in the SRS information transmitted by each of non-AP STA 1 (520) and non-AP STA 2 to AP 1 (510) and AP 2 (530). For the above, the response frame may include A (aggregated)-MPDU EOF (end of frame) padding. Alternatively, a BlockAck frame and at least one QoS Null frame may be concatenated in an A-MPDU form to form the response frame. Here, at least one QoS Null frame may be padding. The padding may be bits for extending the length of the frame. Receivers receiving a frame containing padding (e.g., non-AP STA 1 and non-AP STA 2) can change their operating state while the padding is being transmitted. Additionally, AP 1 (510) and AP 2 (530) can recognize that the response frame sent by each of non-AP STA 1 (520) and non-AP STA 2 to AP 1 (510) and AP 2 (530) is being sent to AP 1 (530) while the response frame is being sent to AP 1 (510) and AP 2 (530) is being sent to AP 1 (530) and AP 2 (530) if the SRS information in the MAC header of the data frame sent by non-AP STA 1 (520) and non-AP STA 2 is longer than the response frame that AP 1 (510) and AP 2 (530) intends to send (e.g., if it is longer by the DPS padding delay than the length of the original response frame of AP 1 (510) and AP 2 (530)) or if the SRS information includes an indicator requesting a transition from LCM to HCM by non-AP STA 1 (520) and non-AP STA 2.

[0199] non-AP STA 1 (520) and non-AP STA 2 can receive padded response frames from AP 1 (510) and AP 2 (530). Specifically, each of non-AP STA 1 (520) and non-AP STA 2 can receive a BlockAck frame included in the response frame and then perform a transition from LCM to HCM. Each of non-AP STA 1 (520) and non-AP STA 2 can operate in HCM after the end of the response frame transmission by AP 1 (510) and AP 2 (530). That is, each of non-AP STA 1 (520) and non-AP STA 2 can perform frame transmission using bandwidth, NSS, and MCS that are not limited within the capabilities of the STAs. Each of non-AP STA 1 (520) and non-AP STA 2 can perform normal frame transmission.

[0200] However, since the bandwidth of the data frame initially transmitted by non-AP STA 1 (520) and non-AP STA 2 is 20 MHz, additional channel access methods may be required for non-AP STA 1 (520) and non-AP STA 2 to transmit using a wider bandwidth. Alternatively, instead of using a wider bandwidth, non-AP STA 1 (520) and non-AP STA 2 may each transmit frames to AP 1 (510) and AP 2 (530) using unrestricted NSS and MCS.

[0201] To extend the bandwidth of frames transmitted to AP 1 (510) and AP 2 (530) after non-AP STA 1 (520) and non-AP STA 2 are operating in HCM mode, each of non-AP STA 1 (520) and non-AP STA 2 may receive a response frame from AP 1 (510) and AP 2 (530) and transmit a frame after PIFS (priority interframe space), which is a longer time than SIFS, instead of transmitting additional data frames after SIFS (short interframe space). During PIFS time, each of non-AP STA 1 (520) and non-AP STA 2 may perform channel sensing operations over the entire operable channel. Based on channel detection operation, if non-AP STA 1 (520) or non-AP STA 2 each can transmit additional data frames with a bandwidth wider than 20 MHz (e.g., if the wide bandwidth channel is idle during PIFS time), non-AP STA 1 (520) or non-AP STA 2 each can transmit data frames to AP 1 (510) or AP 2 (530) using a wide bandwidth (e.g., a bandwidth of 40 MHz or more).

[0202] If at least one of non-AP STA 1 (520) and non-AP STA 2 can only use a 20 MHz channel, at least one of non-AP STA 1 (520) and non-AP STA 2 may need to transmit data frames using only each 20 MHz bandwidth. Here, at least one of non-AP STA 1 (520) and non-AP STA 2 may set the NSS and MCS of the additional data frames transmitted higher than the data frames initially transmitted to at least one of AP 1 (510) and AP 2 (530). This allows at least one of non-AP STA 1 (520) and non-AP STA 2 to transmit more data to at least one of AP 1 (510) and AP 2 (530) at the same time.

[0203] As another example, to extend the bandwidth of a frame transmitted to at least one of AP 1 (510) and AP 2 (530) after at least one of non-AP STA 1 (520) and non-AP STA 2 is operating in HCM mode, at least one of non-AP STA 1 (520) and non-AP STA 2 may receive a response frame and, instead of transmitting an additional data frame after the short interframe space (SIFS), perform a new channel access procedure (EDCA backoff operation and EDCA TXOP acquisition procedure). At least one of non-AP STA 1 (520) and non-AP STA 2 (540) may perform a channel sensing operation over the entire operable channel while the channel access procedure is being performed. Based on channel detection operation, if at least one of non-AP STA 1 (520) and non-AP STA 2 (540) can transmit additional data frames with a bandwidth wider than 20 MHz (e.g., if the wide bandwidth channel is idle during PIFS time), at least one of non-AP STA 1 (520) and non-AP STA 2 (540) can transmit data frames using a wide bandwidth (e.g., a bandwidth of 40 MHz or more). If at least one of non-AP STA 1 (520) and non-AP STA 2 (540) can only use a 20 MHz channel, at least one of non-AP STA 1 (520) and non-AP STA 2 (540) can perform data frame transmission using only a 20 MHz bandwidth.

[0204] At least one of non-AP STA 1 (520) and non-AP STA 2 (540) performs a channel detection operation while performing a channel access operation, and can check the available bandwidth according to the channel detection operation. When the channel access operation of at least one of non-AP STA 1 (520) and non-AP STA 2 (540) is completed, a frame can be transmitted in the available bandwidth.

[0205] Here, if the channel access operations of non-AP STA 1 (520) and non-AP STA 2 (540) end simultaneously, each of non-AP STA 1 (520) and non-AP STA 2 (540) can immediately synchronize the start time of frame transmission on the first link and the second link to transmit data frames to each of AP 1 (510) and AP 2 (530). If the channel access operations of non-AP STA 1 (520) and non-AP STA 2 (540) do not end simultaneously (e.g., if the channel access operation of non-AP STA 1 (520) is completed first), non-AP STA 1 (520) can wait for the completion of the channel access operation of non-AP STA 2 (540). That is, non-AP STA 1 (520) may not perform data frame transmission while keeping the backoff counter at 0. When the channel access operation of non-AP STA 2 is completed, non-AP STA 1 (520) and non-AP STA 2 (540) can each synchronize the start time of frame transmission on the first link and the second link and transmit the data frame to AP 1 (510) and AP 2 (530), respectively.

[0206] Even when transmitting over a wider bandwidth by performing the new channel access procedure described above, the total number of TXOPs that can be transmitted may be limited to the initially set TXOP. This limitation to the initial TXOP may be because other STAs may have set NAVs based on the initially set TXOP, thereby increasing the channel access success rate.

[0207] As another example, non-AP STA 1 (520) and non-AP STA 2 (540) operate in HCM mode, and to extend the bandwidth of frames transmitted to AP 1 (510) and AP 2 (530), non-AP STA 1 (520) and non-AP STA 2 (540) receive response frames from AP 1 (510) and AP 2 (530) and transmit additional data frames after the short interframe space (SIFS). Here, each of non-AP STA 1 (520) and non-AP STA 2 (540) can transmit data frames to each of AP 1 (510) and AP 2 (530) using a wide bandwidth (e.g., bandwidth of 40 MHz or more) after the SIFS time.

[0208] AP 1 (510) and AP 2 (530) each receive additional data frames from non-AP STA 1 (520) and non-AP STA 2 (540) and may transmit a response frame to non-AP STA 1 (520) and non-AP STA 2 (540), respectively. After the transmission of the additional data frame is complete, non-AP STA 1 (520) and non-AP STA 2 (540) may no longer have any data frames to transmit. That is, the TXOP of non-AP STA 1 (520) and non-AP STA 2 (540) may be terminated. If the additional data frame transmitted by non-AP STA 1 (520) and non-AP STA 2 (540), respectively, is a frame that does not require a response frame from AP 1 (510) and AP 2 (530),<Tw 조건 3> The waiting time (Tw time) can be started by... Or, if an additional data frame of at least one of non-AP STA 1 (520) and non-AP STA 2 (540) is a frame that requires a response frame of at least one of AP 1 (510) and AP 2 (530),<Tw 조건 2> The Tw time (waiting time) can be started by... Within the Tw time<LCM 전환> If the condition is met, at least one of non-AP STA 1 (520) and non-AP STA 2 (540) may operate as an LCM again after a DPS switching delay time. Within the Tw time, at least one of non-AP STA 1 (520) and non-AP STA 2 (540) receives a PHY-RXSTART.indication primitive<LCM 전환> Even if the conditions are not met<LCM 전환 - 수신> If the conditions are met, it does not operate as HCM and can return to LCM after the DPS switching delay time.

[0209] For example, the last frames transmitted by non-AP STA 1 (520) and non-AP STA 2 (540) may not contain SRS information requesting the response frame length from AP 1 (510) and AP 2 (530). That is, the last transmitted data frame of the TXOP may not contain SRS information, and the lengths of the response frames transmitted by AP 1 (510) and AP 2 (530) may differ. Here, since the end times of the response frame transmission by AP 1 (510) and AP 2 (530) may differ, non-AP STA 1 (520) and non-AP STA 2 each<Tw 조건 2> The timing of when it starts may differ, and the timing of when non-AP STA 1 and non-AP STA 2 operate from HCM to LCM may differ.

[0210] FIGS. 11a and FIGS. 11b are drawings illustrating a dynamic low-power operation method in multiple links applicable to the present disclosure.

[0211] Referring to FIG. 11a and FIG. 11b, one can consider a non-AP STA 1 (520) of a non-AP STA MLD 1 operating in the first link and an AP 1 (510) of an AP MLD 1. As another example, the non-AP STA 1 (520) may be a STA not included in the MLD. Alternatively, the AP 1 (510) may be an AP not included in the MLD and is not limited to a specific form.

[0212] The DPS setup procedure can be initiated through the exchange of UHR OMN frames. By non-AP STA 1 (520) transmitting a UHR OMN frame (601) to AP 1 (510) and AP 1 (510) transmitting a UHR OMN frame (602) back to non-AP STA 1 (520), non-AP STA 1 (520) can initiate DPS operation on the first link. Additionally, AP 1 (510) can support the DPS operation of non-AP STA 1 (520). non-AP STA 1 (520) may be a DPS STA, and AP 1 (510) may be a DPS-supporting AP. According to the above-described DPS setup procedure, AP 1 (510) can recognize the DPS padding delay and DPS switching delay information of non-AP STA 1 (520). For example, the first link and the second link on which the non-AP STA 1 (520) and non-AP STA 2 of the non-AP STA MLD 1 operate may be a non-simultaneous transmission / reception link pair (NSTR Link Pair). Accordingly, at least one of the transmission start time and transmission end time of the frame transmitted by AP 1 (510) and AP 2 (530) of the AP MLD 1 to the non-AP STA MLD 1 may need to be synchronized.

[0213] AP MLD 1 may want to transmit data frames to non-AP STA MLD 1 using the first link and the second link. AP 1 (510) and AP 2 (530) of AP MLD 1 may each perform channel access operations (e.g., EDCA backoff operation and EDCA channel access procedure) on the first link and the second link, respectively.

[0214] Referring to FIG. 11a, AP 1 (510) and AP 2 (530) each transmit an ICF to a STA performing a DPS operation to switch non-AP STA 1 (520) and non-AP STA 2 of non-AP STA MLD 1 from LCM to HCM. Since non-AP STA 1 (520) and non-AP STA 2 (540) of non-AP STA MLD 1 operate on the first link and the second link, which are the NSTR link pairs of non-AP STA MLD 1, AP 1 (510) and AP 2 (530) of AP MLD 1 may need to transmit the ICF by synchronizing the transmission start time and transmission end time on the first link and the second link. When the channel access operation of one of AP 1 (510) and AP 2 (530) is completed simultaneously (e.g., the backoff counter reaches 0), AP 1 (510) and AP 2 (530) can transmit ICF (609-1, 609-2) simultaneously on the first link and the second link.

[0215] However, the channel access operation of one of AP 1 (510) and AP 2 (530) may be completed first. For example, the channel access operation of AP 1 (510) may be completed first. In the above case, AP 1 (510) may keep the backoff counter at 0 and wait without transmitting a frame until AP 2 (530) completes the channel access operation (i.e., AP 2 initiates a TXOP). When the channel access operation of AP 2 (530) is completed, AP 1 (510) and AP 2 (530) may simultaneously transmit the ICF (609-1, 609-2) to non-AP STA 1 (520) and non-AP STA 2 (540). Meanwhile, there may be some time difference (e.g., a time difference of 4 us or less) when AP 1 (510) and AP 2 (530) transmit the ICF simultaneously. The ICF (609-1, 609-2) of non-AP STA 1 (520) and non-AP STA 2 (540) may be a BSRP (buffer status report poll) trigger frame, a MU-RTS (multi-user request to send) trigger frame, or other frames, but are not limited to a specific form.

[0216] The ICF (609-1, 609-2) of AP 1 (510) and AP 2 (530) may include a padding field that guarantees the time for non-AP STA 1 (520) and non-AP STA 2 (540) to operate from LCM to HCM. The padding field may be a field for increasing the length of the frame. For example, the padding field may be included after the intermediate FCS (frame check sequence), which is an error check sequence included in the middle of the trigger frame. If the DPS padding delay of non-AP STA 1 (520) and non-AP STA 2 (540) is the same, the length of the padding field of the first link and the second link may be set to the length of the DPS padding delay time of non-AP STA 1 (520) or non-AP STA 2 (540). As another example, if the DPS padding delays of non-AP STA 1 (520) and non-AP STA 2 (540) are different, the length of the padding field of the first link and the second link may be set to the longer of the DPS padding lengths of non-AP STA 1 (520) and non-AP STA 2 (540) or longer. This allows the padding field of the ICF to provide sufficient time for both non-AP STA 1 (520) and non-AP STA 2 (540) to transition from LCM to HCM. As described above, the transmission start time of the ICF (609-1, 609-2) transmitted by AP 1 (510) and AP 2 (530) on the first link and the second link may be the same, and the transmission end time may also be the same. In addition, both non-AP STA 1 (520) and non-AP STA 2 (540) can operate as HCMs when they have finished receiving the ICF (609-1, 609-2) transmitted by AP 1 (510) and AP 2 (530), and can perform frame exchanges in HCMs with AP 1 (510) and AP 2 (530), respectively.

[0217] Referring to FIG. 11b, AP 1 (510) and AP 2 (530) may transmit ICF (610-1, 610-2) to the STA performing the DPS operation to switch non-AP STA 1 (520) and non-AP STA 2 (540) of non-AP STA MLD 1 from LCM to HCM. Since non-AP STA 1 (520) and non-AP STA 2 (540) of non-AP STA MLD 1 operate on the first link and the second link, which are the NSTR link pair of non-AP STA MLD 1, AP 1 (510) and AP 2 (530) of AP MLD 1 may need to transmit the transmission end time of ICF (610-1, 610-2) in synchronization with the first link and the second link. When the channel access operation of one of AP 1 (510) and AP 2 (530) is completed simultaneously (e.g., the backoff counter reaches 0), AP 1 (510) and AP 2 (530) can transmit the ICF simultaneously on the first link and the second link.

[0218] However, the channel access operation of one of AP 1 (510) and AP 2 (530) may be completed first. For example, the channel access operation of AP 1 (510) may be completed first. In the above case, AP 1 (510) may transmit the ICF (610-1) first. AP 2 (530) may also transmit the ICF (610-2) if the channel access operation is successful. Here, the difference in the completion time of the ICF (610-1) of AP 1 (510) and the ICF (610-2) of AP 2 (530) may be taken into account. The ICFs (610-1, 610-2) of AP 1 (510) and AP 2 (530) may be BSRP (buffer status report poll) trigger frames, MU-RTS (multi-user request to send) trigger frames, or other frames, and are not limited to a specific form. The ICF (610-1, 610-2) of AP 1 (510) and AP 2 (530) may include a padding field that is a field that guarantees the time for non-AP STA 1 (520) and non-AP STA 2 (540) to operate from LCM to HCM. The padding field may be a field for increasing the length of the frame. For example, the padding field may be included after the intermediate FCS (frame check sequence), which is an error check sequence included in the middle of the trigger frame.

[0219] If the DPS padding delay of non-AP STA 1 (520) and non-AP STA 2 (540) is the same, padding fields equal to the same DPS padding delay may be added to the ICFs (610-1, 610-2) of AP 1 (510) and AP 2 (530). Since the ICF (610-1) of AP 1 (510) is transmitted earlier than the ICF (610-2) of AP 2 (530) and has the same padding field length, transmission may end earlier than that of the ICF (610-2) of AP 2 (530). Therefore, the transmission end times of the ICFs of each AP may not be synchronized. The ICF (610-1) of AP 1 (510) may include not only padding equal to the DPS padding delay of non-AP STA 1 (520), but also additional padding (e.g., padding 2, Padding_2) for synchronizing the transmission end time with the ICF (610-2) of AP 2 (530), thereby synchronizing the transmission end times of the ICFs (610-1, 610-2) of AP 1 (510) and AP 2 (530). The additional padding may be an additional padding field, but it may also be an extension of the length of the padding field included in the ICF (610-1).

[0220] If the DPS padding delay of non-AP STA 1 (520) is shorter than the DPS padding delay of non-AP STA 2 (540), the ICF (610-1) of AP 1 (510) is transmitted earlier than the ICF (610-2) of AP 2 (530), and since it has a shorter padding field length, transmission may end earlier than the ICF (610-2) of AP 2 (530). Therefore, the transmission end times of the ICFs of each AP may not be synchronized. The ICF (610-1) of AP 1 (510) may include not only padding equal to the DPS padding delay of non-AP STA 1 (520), but also additional padding (e.g., Padding 2, Padding_2) for synchronizing the transmission end time with the ICF (610-2) of AP 2 (530).

[0221] As another example, if the transmission of the ICF (610-1) of AP 1 (510) ends later than the transmission of the ICF (610-2) of AP 2 (530) because the DPS padding delay of non-AP STA 1 (520) is longer than the DPS padding delay of non-AP STA 2 (540), the ICF (610-2) of AP 2 (530) may have padding equal to the DPS padding delay of non-AP STA 2 (540) added, as well as additional padding (e.g., padding 2, Padding_2) to synchronize the transmission end times with the ICF (610-1) of AP 1 (510). The transmission end times of the ICFs of AP 1 (510) and AP 2 (530) can be synchronized. Additional padding may be an additional padding field, but it may also be an extension of the length of the padding field included in ICF(610-2).

[0222] In FIG. 11b, AP 1 (510) and AP 2 (530) may need to calculate the length of the padding field in advance before transmitting the ICF. For example, if AP 1 (510) and AP 2 (530) decide to transmit the ICFs (610-1, 610-2) simultaneously, they may calculate the length of the padding field included in the ICFs (610-1, 610-2) based on FIG. 11a in advance, and construct and transmit the ICF based on this. For example, if AP 1 (510) and AP 2 (530) decide not to transmit ICFs (610-1, 610-2) simultaneously, AP MLD 1 must pre-calculate the length of the padding field included in the ICFs (610-1, 610-2) based on the remaining backoff counter value of AP 1 (510) and AP 2 (530) (or / and the remaining channel access time based on the remaining backoff counter value), and the DPS padding delay information per link of STA MLD 1. For example, it is expected that the backoff counter of AP 1 (510) is smaller than the backoff counter of AP 2 (530) and that the ICF can be transmitted first, and the DPS padding delay of STA 2 connected to AP 2 (530) is equal to or longer than the padding delay of STA 1 connected to AP 1 (510), or the DPS padding delay is shorter than the padding delay of STA 1 connected to AP 1 (510), but the remaining channel access length due to the remaining backoff counter value of AP 2 (530) is long. In this case, if additional padding length is not considered for the ICF (610-1) transmitted by AP 1 (510), the time of completion of transmission of the ICF (610-1) may be before the time of completion of transmission of the ICF (610-2) transmitted by AP 2 (530).Accordingly, AP MLD 1 can calculate the length of a padding field including an additional padding length of the ICF (610-1) so that the transmission completion times of the ICF (610-1) transmitted by AP 1 (510) and the ICF (610-2) expected to be transmitted by AP 2 (530) after channel access is complete are the same. Alternatively, there may be cases where the backoff counter of AP 1 (510) (510) is smaller than the backoff counter of AP 2, so the ICF is expected to be transmitted first, but the DPS padding delay of STA 2 connected to AP 2 is shorter than the padding delay of STA 1 connected to AP 1 (510). In this case, if the additional padding length is not considered for the ICF (610-2) transmitted by AP 2, the transmission completion time of the ICF (610-2) may be before the transmission completion time of the ICF (610-1) transmitted by AP 1 (510). Accordingly, AP MLD 1 can calculate an additional padding length of the ICF (610-2) such that the transmission completion times of the ICF (610-1) transmitted by AP 1 (510) and the ICF (610-2) expected to be transmitted by AP 2 after channel access is complete are the same. However, if the calculation of the padding length is not possible, padding of a different form than the padding field included in the user information field of the ICF may be added. For example, the additional padding may be end-of-frame (EOF) padding using the delimiter or similar indicator of the MPDU included in the A-MPDU (aggregated MPDU), or other MAC padding methods. Alternatively, the additional padding may be physical layer (PHY) padding that is not added during MAC layer frame transmission (e.g., PHY padding including packet extensions).

[0223] Referring to FIGS. 11a and 11b, the ICF can be transmitted in a duplicate PPDU format that is duplicated and transmitted per 20 MHz channel. For example, it can be duplicated per 20 MHz and transmitted on channels of 40 MHz, 80 MHz, 160 MHz, or 320 MHz, but is not limited thereto.

[0224] The non-AP STA 1 (520) and non-AP STA 2 (540) of the non-AP STA MLD 1 can receive an ICF from AP 1 (510) and AP 2 (530) of the AP MLD 1 and can switch the operation mode from LCM to HCM during the padding field included in the ICF. After switching to HCM mode, the non-AP STA 1 (520) and non-AP STA 2 (540) of the non-AP STA MLD 1 can respond to AP 1 (510) and AP 2 using an ICR frame. Here, the transmission start time and transmission end time of the ICR frame can be synchronized. AP 1 (510) and AP 2 of the AP MLD 1 can transmit downlink frames using the bandwidth, NSS, and MCS that are receivable in HCM by the non-AP STA 1 (520) and non-AP STA 2 (540). non-AP STA MLD 1 can receive frames from AP MLD 1 and transmit response frames. That is, non-AP STA 1 (520) and non-AP STA 2 (540) can transmit response frames for frames received from AP 1 (510) and AP 2. non-AP STA 1 (520) and non-AP STA 2 (540)<Tw 조건 1> Depending on Tw time<LCM 전환> If the condition is met, at least one of non-AP STA 1 (520) and non-AP STA 2 (540) may operate as an LCM again after a DPS switching delay time. Within the Tw time, at least one of non-AP STA 1 (520) and non-AP STA 2 (540) receives a PHY-RXSTART.indication primitive<LCM 전환> Even if the conditions are not met<LCM 전환 - 수신> If the conditions are met, it does not operate as HCM and can return to LCM after the DPS switching delay time.

[0225] FIG. 12 is a diagram illustrating a dynamic low-power operation method in multiple links applicable to the present disclosure.

[0226] Referring to FIG. 12, non-AP STA 1 (520) of non-AP STA MLD 1 and AP 1 (510) of AP MLD 1 operating on the first link may be considered. As another example, non-AP STA 1 (520) may be a STA not included in the MLD. Alternatively, AP 1 (510) may be an AP not included in the MLD and is not limited to a specific form. The DPS setup procedure may be initiated through the exchange of UHR OMN frames. The non-AP STA 1 (520) may initiate DPS operation on the first link by transmitting a UHR OMN frame (601) to AP 1 (510) and AP 1 (510) transmitting a UHR OMN frame (602) back to non-AP STA 1 (520). Additionally, AP 1 (510) can support the DPS operation of non-AP STA 1 (520). non-AP STA 1 (520) is a DPS STA, and AP 1 (510) may be a DPS-supported AP. According to the DPS setting procedure described above, AP 1 (510) can recognize the DPS padding delay and DPS switching delay information of non-AP STA 1 (520). The first link and the second link on which non-AP STA 1 (520) and non-AP STA 2 (540) of non-AP STA MLD 1 operate may be STR (simultaneous transmit and receive) link pairs rather than NSTR link pairs. Therefore, at least one of the transmission start time and transmission end time of the frame transmitted by AP 1 (510) and AP 2 of AP MLD 1 to non-AP STA MLD 1 may not be synchronized.

[0227] AP 1 (510) and AP 2 can transmit an ICF to a STA performing a DPS operation to enable non-AP STA 1 (520) and non-AP STA 2 (540) of non-AP STA MLD 1 to switch from LCM to HCM operation. When the channel access operation of one of AP 1 (510) and AP 2 is completed simultaneously (e.g., when the backoff counter reaches 0), AP 1 (510) and AP 2 can each transmit an ICF on the first link and the second link simultaneously.

[0228] Here, the channel access operation of one of AP 1 (510) and AP 2 may be completed first. For example, the channel access operation of AP 1 (510) may be completed first. In the case described above, AP 1 (510) may transmit the ICF (611-1) first. AP 2 may also transmit the ICF (611-2) if the channel access operation is successful. The ICFs (611-1, 611-2) of AP 1 (510) and AP 2 may be BSRP (buffer status report poll) trigger frames, MU-RTS (multi-user request to send) trigger frames, or other frames, and are not limited to a specific form. The ICF (611-1, 611-2) may include a padding field which is a field that guarantees the time for non-AP STA 1 (520) and non-AP STA 2 (540) to operate from LCM to HCM. The padding field may be a field to increase the length of the frame. The padding field may be included after the intermediate FCS (frame check sequence), which is an error check sequence included in the middle of the trigger frame. If the DPS padding delay of non-AP STA 1 (520) and non-AP STA 2 (540) is the same, the ICF (611-1, 611-2) of AP 1 (510) and AP 2 may have padding fields of the same DPS padding added. Alternatively, if the DPS padding delays of non-AP STA 1 (520) and non-AP STA 2 (540) are different, a padding field equal to the length of the DPS padding delay of non-AP STA 1 (520) may be added to the ICF (611-1) of AP 1 (510), and a padding field equal to the length of the DPS padding delay of non-AP STA 2 (540) may be included in the ICF (611-2) of AP 2.

[0229] The ICF may be transmitted in a duplicate PPDU format that is duplicated and transmitted per 20 MHz channel. For example, it may be duplicated per 20 MHz and be 40 MHz, 80 MHz, 160 MHz, or 320 MHz, but is not limited thereto. The non-AP STA 1 (520) and non-AP STA 2 (540) of the non-AP STA MLD 1 may receive the ICF (611-1, 611-2) from the AP 1 (510) and AP 2 of the AP MLD 1 and may switch the operating mode from LCM to HCM during the padding field included in the ICF. After switching to HCM mode, the non-AP STA 1 (520) and non-AP STA 2 (540) of the non-AP STA MLD 1 may respond to the AP 1 (510) and AP 2 using an ICR frame. Here, the transmission start time and transmission end time of the ICR frame can be synchronized if the transmission end time of the ICF of AP 1 (510) and AP 2 is the same. However, since the first link and the second link may be STRs, they may not be synchronized if the transmission end time of the ICF of AP 1 (510) and AP 2 is different.

[0230] AP 1 (510) and AP 2 of AP MLD 1 can transmit downlink frames using the bandwidth, NSS, and MCS that non-AP STA 1 (520) and non-AP STA 2 (540) can receive in the HCM. That is, AP 1 (510) and AP 2 can perform general data transmission and reception, and the operating bandwidth and operating space stream are not limited. non-AP STA MLD 1 can receive frames from AP MLD 1 and transmit response frames. That is, non-AP STA 1 (520) and non-AP STA 2 (540) can transmit response frames for frames received from AP 1 (510) and AP 2.

[0231] non-AP STA 1 (520) and non-AP STA 2 (540)<Tw 조건 1> Depending on Tw time<LCM 전환> If the condition is met, at least one of non-AP STA 1 (520) and non-AP STA 2 (540) may operate as an LCM again after a DPS switching delay time. Within the Tw time, at least one of non-AP STA 1 (520) and non-AP STA 2 (540) receives a PHY-RXSTART.indication primitive<LCM 전환> Even if the conditions are not met<LCM 전환 - 수신> If the condition is met, it does not operate as HCM and can operate as LCM again after the DPS switching delay time. non-AP STA 1 (520)<Tw 조건 1> Depending on the time when Tw starts and non-AP STA 2(540)<Tw 조건 1> The timing of the start of Tw may vary depending on the circumstances. That is, the timing at which non-AP STA 1 (520) and non-AP STA 2 (540) stop HCM operation and switch back to LCM may differ. For example, a downlink frame sent by AP 1 (510) to non-AP STA 1 (520) may end earlier than a downlink frame sent by AP 2 to non-AP STA 2 (540). non-AP STA 1 (520) sends a response frame to AP 1 (510) and<Tw 조건 1> It can start before non-AP STA 2(540), and during Tw time<LCM 전환> If the condition is met, non-AP STA 1 (520) can operate as LCM again after the DPS switching delay time. Within the Tw time, non-AP STA 1 (520) receives the PHY-RXSTART.indication primitive<LCM 전환> Even if the conditions are not met<LCM 전환 - 수신> If the conditions are met, it does not operate as HCM and can return to LCM after the DPS switching delay time.That is, non-AP STA 1 (520) can stop HCM operation and perform LCM operation before non-AP STA 2 (540).

[0232] In the embodiments of FIGS. 11a to 12 described above, the padding included in the ICF may be a padding field using the user info field of the trigger frame, but it may be more diverse. For example, the padding may be end-of-frame (EOF) padding using the delimiter or similar indicator of the MPDU included in the A-MPDU (aggregated MPDU), or other MAC padding methods. Alternatively, the padding may be physical layer (PHY) padding that is not added during MAC layer frame transmission (e.g., PHY padding including packet extensions). The padding field using the user info field, MAC padding other than the padding field, and PHY padding may be used in combination. However, regardless of the padding method, the padding increases the time length of the frame, and the function of the padding, which allows the STA receiving the padding to switch the operating mode based on the time length extended by the padding, does not change even if each different padding method is used alone or in combination.

[0233] FIG. 13 is a flowchart illustrating the operation of an STA MLD in a wireless LAN to which the present disclosure applies. Referring to FIG. 13, a method of operation of a first MLD including a first STA associated with a first link and a second STA associated with a second link may be provided. Here, the first MLD may be connected to a second MLD that performs multi-link communication. (S1310) The first MLD may transmit a first frame to the second MLD from a first link that is activated for the first STA of the first MLD. (S1320) The first frame indicates whether to switch the activation state of the second link, and if the first frame indicates the activation state of the second link, the first MLD may perform frame exchange with the second MLD from the first link and the second link that are activated. (S1320) Here, along with the indication of whether to switch the activation state of the second link, information on the time of transition when the second link switches to an active state may be indicated. Additionally, the point at which the second link transitions to an active state may be determined based on the time required for the first MLD to transition to an active state on the second link. Based on the indication of whether the second link transitions to an active state, the first MLD may receive at least one frame transmitted from the first link and the second link, respectively, from the second MLD after the second link is activated. Furthermore, if the first link and the second link are a non-simultaneous transmit and receive (NSTR) link pair that cannot perform simultaneous transmit and receive operations, the frame transmitted from the first link and the frame transmitted from the second link may be synchronized and received at the same time. Additionally, the first MLD indicates that the second link does not transition to an active state in the indication of whether the second link transitions to an active state, and the first MLD may receive at least one frame transmitted from the first link from the second MLD.

[0234] FIG. 14 is a flowchart illustrating the operation of an STA MLD in a wireless LAN to which the present disclosure applies. A method of operation of a first MLD including a first STA associated with a first link and a second STA associated with a second link can be provided in a wireless LAN system.

[0235] Specifically, the first MLD may be connected to a second MLD that performs multi-link communication. (S1410) The second MLD includes a third STA associated with the first link and a fourth STA associated with the second link, and the first MLD may receive a first frame from the second MLD on the first link that is activated for the third STA of the second MLD. (S1420) Here, the first frame may indicate whether to switch the activation state of the second link that is activated for the fourth STA of the second MLD. If the first frame indicates the activation state of the second link of the second MLD, the first MLD can perform frame exchange with the second MLD on the first link and the second link that are activated in the second MLD. (S1430) For example, the first MLD of FIG. 13 may be an MLD that transmits a frame on the activated first link, and the first MLD of FIG. 14 may be an MLD that receives a frame on the activated first link, but is not limited thereto.

[0236] Here, along with an instruction regarding whether the second link is switched to an active state, information regarding the transition time at which the second link is switched to an active state may be provided. Additionally, based on the instruction regarding whether the second link is switched to an active state, the first MLD may transmit at least one frame from each of the first link and the second link to the second MLD after the second link of the second MLD is activated. Furthermore, if the first MLD indicates that the second link is not switched to an active state in the instruction regarding whether the second link of the second MLD is switched to an active state, the first MLD may transmit a frame to the second MLD using only the first link.

[0237] FIG. 15 is a flowchart illustrating the operation of an AP MLD in a wireless LAN to which the present disclosure applies. Referring to FIG. 15, a method of operation of an AP MLD including a first AP associated with a first link and a second AP associated with a second link in a wireless LAN system may be provided. Specifically, the AP MLD may receive a first frame from a non-AP MLD instructing it to perform a DPS operation (S1510). Then, the AP MLD may transmit a second frame instructing the non-AP MLD to support the performance of a DPS operation (S1520), and may complete a multi-link DPS setup procedure by transmitting the second frame (S1530). Here, based on the multi-link DPS setup procedure, a DPS operation is set in the non-AP MLD, and the non-AP MLD may operate in a lower capability mode (LCM) on the first link and the second link. Here, the first link and the second link may be a non-simultaneous transmit and receive (NSTR) link pair that cannot perform simultaneous transmit and receive operations. Additionally, the AP MLD can transmit a frame by performing a channel access operation on the first link for the first AP of the AP MLD, and transmit a frame by performing a channel access operation on the second link for the second AP of the AP MLD. Additionally, the frame transmitted on each of the first link and the second link is an initial control frame, and the non-AP MLD can be operated by switching from LCM to HCM (high capability mode) on the first link and the second link by the initial control frame. Additionally, if the channel access operation on the first link is completed first, the backoff counter on the first link is maintained at 0, and when the channel access operation on the second link is completed, frame transmission can be performed simultaneously on the first link and the second link.Additionally, padding is set in the initial control frame so that the end times of the initial control frame of the first link and the initial control frame of the second link are the same, and the padding may be set identically in the initial control frame of the first link and the initial control frame of the second link as the longer value between the DPS padding delay of the first link and the DPS padding delay of the second link. Furthermore, if the channel access operation of the first link is completed first, frame transmission may be performed first on the first link, and if the channel access operation of the second link is completed, frame transmission may be performed on the second link. Additionally, a first DPS padding is set in the initial control frame of the first link, and a second PDS padding is set in the initial control frame of the second link, wherein the first DPS padding and the second DPS padding are set such that the end times of the initial control frame of the first link and the initial control frame of the second link are the same, and each of the first DPS padding and the second DPS padding may be set to a value longer than the DPS padding delay of the first link and the DPS padding delay of the second link. Additionally, the LCM may be a mode in which at least one of the operating bandwidth, the number of spatial streams, and the modulation and coding scheme (MCS) is limited, or a mode in which only specific format frames can be received.

[0238] FIG. 16 is a flowchart illustrating the operation of a non-AP MLD in a wireless LAN to which the present disclosure applies. Referring to FIG. 16, a method of operation of a non-AP MLD including a first STA associated with a first link and a second STA associated with a second link can be provided in a wireless LAN system. Specifically, the non-AP MLD can transmit a first frame instructing the AP MLD to perform a dynamic power saving (DPS) operation (S1610). Then, the non-AP MLD receives a second frame instructing the non-AP MLD to support the performance of a DPS operation (S1620), and can complete a multi-link DPS setup procedure upon receiving the second frame (S1630). Here, based on the multi-link DPS setup procedure, a DPS operation is set in the non-AP MLD, and the non-AP MLD can operate in a lower capability mode (LCM) on at least one of the first link and the second link. Here, the first frame and the second frame are exchanged on at least one of the first link and the second link, and the multi-link DPS setup procedure can be established when the exchange of the first frame and the second frame is completed. For example, the first frame may include a link identifier indicating the link where the non-AP MLD performs the DPS operation. Additionally, if the first frame includes the link identifier of the first link and the link identifier of the second link, the first frame includes the DPS operation parameters of the first link and the DPS operation parameters of the second link, and each DPS operation parameter may include the DPS padding delay and DPS switching delay of the corresponding link. Additionally, if the non-AP MLD performs the DPS operation on the first link and does not perform the DPS operation on the second link, the first frame may include the link identifier of the first link and the DPS operation parameters of the first link, and may not include the link identifier of the second link and the operation parameters of the second link.Additionally, if the non-AP MLD performs a DPS operation on the first link and does not perform a DPS operation on the second link, the first frame may include the link identifier of the first link and the link identifier of the second link, and may indicate that the DPS operation parameter corresponding to the second link is not specified or that the DPS operation is not performed on the second link. Additionally, the first frame and the second frame are exchanged on the first link and the second link, respectively, and the multi-link DPS setup procedure may be established when the first frame and the second frame are completed to be exchanged on the first link and the second link, respectively. Additionally, the first frame may indicate DPS operation parameters including the DPS padding delay and DPS switching delay of the non-AP MLD used on the link where the first frame is transmitted.

[0239] The methods according to the present disclosure may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either alone or in combination. The program instructions recorded on the computer-readable medium may be those specifically designed and configured for the present disclosure, or they may be those known and available to those skilled in the art of computer software. Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions include machine code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate as at least one software module to perform the operations of the present disclosure, and vice versa. Although the present invention has been described with reference to the embodiments above, those skilled in the art will understand that various modifications and changes can be made to the present disclosure without departing from the spirit and scope of the disclosure as set forth in the following claims.

[0240]

[0241] The above-mentioned matters may also be applied to other systems.

Claims

1. A method of operation of a first multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system, A step in which the first MLD is connected to a second MLD that performs multi-link communication; The step of the first MLD transmitting a first frame to the second MLD from the first link activated for the first STA of the first MLD, wherein the first frame indicates whether the activation state of the second link is switched; and A method of operation comprising the step of performing a frame exchange with the second MLD in the first link and the second link in which the first MLD is activated when the first frame indicates the activation state of the second link.

2. In Paragraph 1, A method of operation in which information on the time of transition when the second link is switched to an active state is indicated, along with an indication of whether the second link is switched to an active state.

3. In Paragraph 2, A method of operation in which the point at which the second link is switched to an active state is determined based on the time required for the first MLD to switch to an active state in the second link.

4. In Paragraph 1, A method of operation in which the first MLD receives at least one frame transmitted from the first link and the second link, respectively, after the second link is activated, based on an instruction regarding whether the activation state of the second link is switched.

5. In Paragraph 4, A method of operation in which, when the first link and the second link are a pair of non-simultaneous transmit and receive (NSTR) links that cannot perform simultaneous transmit and receive operations, a frame transmitted from the first link and a frame transmitted from the second link are synchronized and received at the same time.

6. In Paragraph 1, A method of operation in which the first MLD indicates whether the second link is switched to an active state, and the first MLD receives at least one frame transmitted from the first link from the second MLD.

7. A method of operation of a first multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system, A step in which the first MLD is connected to a second MLD that performs multi-link communication, wherein the second MLD includes a third STA associated with the first link and a fourth STA associated with the second link; A step in which the first MLD receives a first frame from the second MLD at the first link activated for the third STA of the second MLD, wherein the first frame indicates whether to switch the activation state of the second link activated for the fourth STA of the second MLD; and A method of operation comprising the step of, when the first frame indicates the activation state of the second link of the second MLD, the first MLD performing a frame exchange with the second MLD at the first link and the second link activated in the second MLD.

8. In Paragraph 7, A method of operation in which information on the time of transition when the second link is switched to an active state is indicated, along with an indication of whether the second link is switched to an active state.

9. In Paragraph 7, A method of operation in which the first MLD transmits at least one frame from each of the first link and the second link to the second MLD after the second link of the second MLD is activated, based on an instruction regarding whether the activation state of the second link is switched.

10. In Paragraph 7, A method of operation in which, when the first MLD indicates that the second link is not switched to an active state in the switching of the active state of the second link of the second MLD, the first MLD transmits a frame to the second MLD using only the first link.

11. A method of operation of a non-AP multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system, A step in which the above-mentioned non-AP MLD transmits a first frame to the AP MLD instructing the execution of a DPS (dynamic power saving) operation; The step of the above non-AP MLD receiving a second frame instructing support for performing a DPS operation; and The method includes the step of receiving the second frame and completing the multi-link DPS setup procedure, A method of operation in which a DPS operation is set in the non-AP MLD based on the above multi-link DPS setting procedure, and the non-AP MLD operates in LCM (lower capability mode) in at least one of the first link and the second link.

12. In Paragraph 11, A method of operation in which the first frame and the second frame are exchanged at least one of the first link and the second link, and the multi-link DPS setting procedure is set when the exchange of the first frame and the second frame is completed.

13. In Paragraph 12, A method of operation in which the first frame includes a link identifier indicating a link in which the non-AP MLD performs a DPS operation.

14. In Paragraph 13, A method of operation in which, when the first frame includes a link identifier of a first link and a link identifier of a second link, the first frame includes a DPS operation parameter of a first link and a DPS operation parameter of a second link, and each DPS operation parameter includes a DPS padding delay and a DPS switching delay of a corresponding link.

15. In Paragraph 13, A method of operation in which, when the above non-AP MLD performs a DPS operation on the first link and does not perform a DPS operation on the second link, the first frame includes a link identifier of the first link and a DPS operation parameter of the first link, and does not include a link identifier of the second link and an operation parameter of the second link.

16. In Paragraph 13, A method of operation in which, when the above non-AP MLD performs a DPS operation on the first link and does not perform a DPS operation on the second link, the first frame includes a link identifier of the first link and a link identifier of the second link, and a DPS operation parameter corresponding to the second link is not indicated or it is indicated that a DPS operation is not performed on the second link.

17. In Paragraph 11, A method of operation in which the first frame and the second frame are exchanged at the first link and the second link, respectively, and the multi-link DPS setting procedure is set when the first frame and the second frame are exchanged at the first link and the second link, respectively.

18. In Paragraph 11, A method of operation in which the first frame indicates DPS operation parameters including a DPS padding delay and a DPS switching delay of the non-AP MLD used in the link where the first frame is transmitted.

19. A method of operation of an AP multi-link device (MLD) comprising a first access point (AP) associated with a first link and a second AP associated with a second link in a wireless LAN system, The step of the above AP MLD receiving a first frame from a non-AP MLD instructing the execution of a DPS (dynamic power saving) operation; A step of transmitting a second frame instructing support for performing DPS operation to the above non-AP MLD; and The method includes the step of transmitting the second frame and completing the multi-link DPS setup procedure, A method of operation in which a DPS operation is set in a non-AP MLD based on the above multi-link DPS setting procedure, and the non-AP MLD operates in LCM (lower capability mode) in the first link and the second link.

20. In Paragraph 19, A method of operation in which the first link and the second link are a pair of NSTR (non-simultaneous transmit and receive) links that cannot perform simultaneous transmit and receive operations.

21. In Paragraph 19, A method of operation in which the above AP MLD transmits a frame by performing a channel access operation on the first link for the above AP MLD's first AP, and transmits a frame by performing a channel access operation on the second link for the above AP MLD's second AP.

22. In Article 21, A method of operation in which a frame transmitted at each of the first link and the second link is an initial control frame, and the non-AP MLD is switched from LCM to HCM (high capability mode) at the first link and the second link by the initial control frame.

23. In Paragraph 22, A method of operation in which, when the channel access operation of the first link is completed first, the backoff counter in the first link is maintained at 0, and when the channel access operation of the second link is completed, frame transmission is performed simultaneously in the first link and the second link.

24. In Paragraph 23, A method of operation in which padding is set in the initial control frame so that the end time of the initial control frame of the first link and the initial control frame of the second link are the same, wherein the padding is set equally in the initial control frame of the first link and the initial control frame of the second link by the longer value between the DPS padding delay of the first link and the DPS padding delay of the second link.

25. In Paragraph 22, A method of operation in which, when the channel access operation of the first link is completed first, frame transmission is performed first on the first link, and when the channel access operation of the second link is completed, frame transmission is performed on the second link.

26. In Paragraph 25, A method of operation in which a first DPS padding is set in the initial control frame of the first link and a second PDS padding is set in the initial control frame of the second link, wherein the first DPS padding and the second DPS padding are set such that the end times of the initial control frame of the first link and the initial control frame of the second link are the same, and each of the first DPS padding and the second DPS padding is set to a value longer than the DPS padding delay of the first link and the DPS padding delay of the second link.

27. In Paragraph 19, The above LCM is a mode of operation in which at least one of the operating bandwidth, the number of spatial streams, and the modulation and coding scheme (MCS) is limited, or a mode in which only specific format frames can be received.

28. In a first multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system, At least one transceiver for transmitting and receiving signals; At least one processor controlling the above-mentioned at least one transmitting and receiving unit; and It includes a memory that stores instructions for the STA to perform a specific operation by the at least one processor, and The above specific operation is: Connected to a second MLD that performs multi-link communication, The first MLD transmits a first frame to the second MLD from the first link activated for the first STA of the first MLD, wherein the first frame indicates whether the activation state of the second link is switched, and A first MLD that performs frame exchange with the second MLD in the first link and the second link where the first MLD is activated, when the first frame indicates the activation state of the second link.

29. A first multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system, At least one transceiver for transmitting and receiving signals; At least one processor controlling the above-mentioned at least one transmitting and receiving unit; and It includes a memory that stores instructions for the STA to perform a specific operation by the at least one processor, and The above specific operation is: Connected to a second MLD that performs multi-link communication, wherein the second MLD includes a third STA associated with the first link and a fourth STA associated with the second link; The first MLD receives a first frame from the second MLD at the first link activated for the third STA of the second MLD, wherein the first frame indicates whether to switch the activation state of the second link activated for the fourth STA of the second MLD, and A first MLD in which, when the first frame indicates the activation state of the second link of the second MLD, the first MLD performs frame exchange with the second MLD at the first link activated in the second MLD and at the second link.

30. A non-AP multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system, At least one transceiver for transmitting and receiving signals; At least one processor controlling the above-mentioned at least one transmitting and receiving unit; and It includes a memory that stores instructions for the STA to perform a specific operation by the at least one processor, and The above specific operation is: Transmit a first frame instructing the execution of a DPS (dynamic power saving) operation to the AP MLD, and The above non-AP MLD receives a second frame instructing support for performing DPS operations, and A non-AP MLD that receives the second frame and completes the multi-link DPS setup procedure, wherein a DPS operation is set in the non-AP MLD based on the multi-link DPS setup procedure, and the non-AP MLD operates in LCM (lower capability mode) on at least one of the first link and the second link.

31. An AP multi-link device (MLD) comprising a first station (STA) associated with a first link and a second STA associated with a second link in a wireless LAN system, At least one transceiver for transmitting and receiving signals; At least one processor controlling the above-mentioned at least one transmitting and receiving unit; and It includes a memory that stores instructions for the STA to perform a specific operation by the at least one processor, and The above specific operation is: Receive a first frame from a non-AP MLD instructing the execution of a DPS (dynamic power saving) operation, and Transmit a second frame instructing support for DPS operation execution to the above non-AP MLD, and An AP MLD that transmits the second frame and completes the multi-link DPS setup procedure, wherein a DPS operation is set in the non-AP MLD based on the multi-link DPS setup procedure, and the non-AP MLD operates in LCM (lower capability mode) on the first link and the second link.

Images