Method and apparatus for performing communication in consideration of operation restriction interval in wireless LAN

Abstract

This operation method of an AP in a wireless LAN system may comprise the steps of: transmitting, by the AP, an initial control frame to a first STA; receiving, by the AP, a response frame from the first STA in response to the initial control frame; and performing communication with the first STA on the basis of the response frame.

Description

Method and device for performing communication considering operation restriction range in wireless LAN

[0001] The present disclosure relates to wireless local area network (WLAN) communication technology, and relates to a method for performing communication in a WLAN while considering the operating constraints of wireless resources. Furthermore, the present disclosure relates to a method and device for indicating a communication failure situation due to internal operation of a WLAN device and performing communication suspension and resumption operations based on the indicated communication failure situation.

[0002]

[0003] With the recent proliferation of mobile devices, Wireless Local Area Network (WLAN) technology, which can provide fast wireless communication services to these devices, is attracting significant attention. WLAN technology utilizes short-range wireless communication technology to enable mobile devices such as smartphones, tablets, laptops, portable multimedia players, and embedded devices to wirelessly access the Internet.

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

[0005] As applications requiring higher reliability arise, the IEEE 802.11bn standard, an ultra-high reliability (UHR) wireless LAN technology, is being developed in a single Basic Service Set (BSS) environment and / or redundant BSS environments. The goals of the IEEE 802.11bn standard may support increased data transmission speed, improved delay performance, and improved data error rate. In addition, the IEEE 802.11bn standard may support low-power operation and direct communication (peer-to-peer communication, P2P), and may support a TXOP sharing method in which a wireless LAN terminal shares a communication resource, a TXOP, between multiple access points (APs).

[0006] Below, we describe coordinated time-division communication operations, considering the case where the time-division communication interval is not protected when performing communication using coordinated time-division communication intervals. Furthermore, we describe methods for managing in-device coexistence (IDC) between multiple communication technologies within a device, and methods for managing IDC and communication constraints, considering the impact of internal device operations on communication.

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

[0008]

[0009] The present disclosure relates to a method and device for performing communication while considering an operation restriction section in a wireless LAN.

[0010] The present disclosure relates to a method and device for indicating the availability of wireless resources in a wireless LAN and performing communication based on the indication.

[0011] The present disclosure relates to a method and device for performing communication based on an indication of wireless resource availability in a wireless LAN.

[0012] The present disclosure relates to a method and device for indicating a communication failure situation based on the internal operation of a wireless LAN device and for suspending and resuming communication according to the indicated communication failure situation.

[0013] The present disclosure relates to a method and device for handling a communication failure situation based on an IDC inside a wireless LAN device.

[0014] The present disclosure relates to a method and device for performing communication based on an indication of wireless resource availability based on an artificial intelligence algorithm.

[0015] The present disclosure relates to a method and device for indicating a communication failure situation based on an artificial intelligence algorithm and for suspending and resuming communication according to the indicated communication failure situation.

[0016] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0017]

[0018] According to one embodiment of the present specification, a method for operating an access point (AP) in a wireless LAN system includes a step in which the AP transmits an initial control frame to a first station (STA), a step in which the AP receives a response frame from the first STA in response to the initial control frame, and a step in which the AP performs communication with the first STA based on the response frame, wherein a network allocation vector (NAV) is set for STAs other than the first STA by the initial control frame, the response frame includes an indicator indicating whether the first STA is capable of communication, and when the first STA is indicated as being unable to communicate by the response frame, the NAV set for STAs other than the first STA can be released based on the response frame.

[0019] In addition, according to one embodiment of the present specification, an access point (AP) includes at least one transceiver for transmitting and receiving a signal, at least one processor for controlling the at least one transceiver, and a memory for storing instructions for causing the AP to perform a specific operation by the at least one processor, wherein the specific operation is: transmitting an initial control frame to a first station (STA), the AP receiving a response frame from the first STA in response to the initial control frame, and performing communication with the first STA based on the response frame, wherein a network allocation vector (NAV) is set for STAs other than the first STA by the initial control frame, the response frame includes an indicator indicating whether the first STA is capable of communication, and when the first STA is indicated as being unable to communicate by the response frame, the NAV set for STAs other than the first STA can be released based on the response frame.

[0020] In addition, according to one embodiment of the present specification, in a method of operating a station (STA) in a wireless LAN system, the STA may transmit a restricted operation mode indication frame to an AP; and the STA may operate in a restricted operation mode indicated by the restricted operation mode indication frame.

[0021] In addition, according to one embodiment of the present specification, a station (STA) includes at least one transceiver for transmitting and receiving a signal, at least one processor for controlling the at least one transceiver, and a memory for storing instructions for causing the STA to perform a specific operation by the at least one processor, wherein the specific operation is: transmitting a restricted operation mode indication frame to an AP, and causing the STA to operate in a restricted operation mode indicated by the restricted operation mode indication frame.

[0022] Additionally, the following may be commonly applied:

[0023] According to one embodiment of the present specification, when the AP receives a response frame indicating that the first STA is unable to communicate, the AP may further transmit a CF (contention free)-End frame, wherein the NAV of the second STA that decodes the response frame transmitted by the first STA may be released by the response frame, and the NAV of the third STA that cannot decode the response frame transmitted by the first STA may be released by the CF-End frame.

[0024] In addition, according to one embodiment of the present specification, if there is downlink data to be transmitted to a third STA after the AP receives a response frame indicating that the first STA is unable to communicate, the AP transmits a downlink data frame to the third STA at a transmit opportunity (TXOP) set by an initial control frame, and receives a response frame for the downlink data frame from the third STA, wherein the NAV of the second STA released by the response frame can be reset by the downlink data frame.

[0025] Additionally, according to one embodiment of the present specification, when the first STA is indicated as being unable to communicate by the response frame, the response frame may further include information on the time point at which the first STA is unable to communicate and the period during which the first STA is unable to communicate.

[0026] Additionally, according to one embodiment of the present specification, the duration field value of the MAC (medium access control) header of the response frame is set to a value until the point in time when the first STA becomes unable to communicate after the response frame is transmitted, and the NAV set for STAs other than the first STA can be maintained until the point in time when the first STA becomes unable to communicate based on the duration field value.

[0027] Additionally, according to one embodiment of the present specification, when there is downlink data to be transmitted to the first STA in the AP, the AP may transmit a downlink data frame to the first STA by comparing the communication resumption time of the first STA and the TXOP of the AP based on the communication unavailability time of the first STA and the communication unavailability period information of the first STA.

[0028] Additionally, according to one embodiment of the present specification, when the first STA is indicated as being unable to communicate by the response frame, the response frame further includes a NAV release prohibition indicator, and the NAV set for STAs other than the first STA based on the NAV release prohibition indicator can be maintained.

[0029] In addition, according to one embodiment of the present specification, if the AP does not receive a response frame from the first STA for a preset time after transmitting the initial control frame, the NAV set for STAs other than the first STA by the initial control frame is released after a preset time after receiving the initial control frame, and the AP may lower the MCS (modulation and coding) index for the next frame and increase the channel access parameter.

[0030] Additionally, according to one embodiment of the present specification, when the AP receives a delayed response frame based on the resumption of communication of the first STA, the AP may revert the lowered MCS index and the increased channel access parameter to their original values.

[0031] Additionally, according to one embodiment of the present specification, the AP may be an AP multi link device (MLD) including an AP 1 associated with a first link and an AP 2 associated with a second link, and the first STA may be a first STA MLD including a first STA 1 associated with the first link and a first STA 2 associated with the second link.

[0032] Additionally, according to one embodiment of the present specification, the AP MLD transmits an initial control frame on the first link for AP 1, and the AP MLD receives a response frame transmitted from the first STA MLD on the first link for AP 1, wherein the response frame may include at least one of a first link communication availability indicator and a second link communication availability indicator.

[0033] Additionally, according to one embodiment of the present specification, if it is indicated that communication is not possible on the first link and communication is possible on the second link based on the response frame, the AP MLD may perform a channel access operation on the second link for AP 2 to transmit a downlink data frame of the first STA MLD.

[0034] In addition, according to one embodiment of the present specification, the response frame further includes at least one of a first link communication unavailability period indicator and a second link communication unavailability period indicator, and when a communication-available time point of the second link is earlier than a communication-available time point of the first link based on the first link communication unavailability period indicator and the second link communication unavailability period indicator, the AP MLD performs a channel access operation on the second link for AP 2 to transmit a downlink data frame of the first STA MLD, and when a communication-available time point of the first link is earlier than a communication-available time point of the second link based on the first link communication unavailability period indicator and the second link communication unavailability period indicator, the AP MLD may transmit a downlink data frame of the first STA MLD on the first link for AP 1 based on a TXOP of the AP MLD.

[0035] Additionally, according to one embodiment of the present disclosure, the AP MLD can receive a response frame including at least one of a first link communication availability indicator and a second link communication availability indicator without receiving an initial control frame.

[0036] In addition, according to one embodiment of the present specification, if the AP MLD does not receive a response frame from the first STA MLD for a preset time after transmitting an initial control frame, the NAV set for STAs other than the first STA MLD by the initial control frame is released after a preset time after receiving the initial control frame, the AP MLD lowers an MCS (modulation and coding) index for the next frame, and increases a channel access parameter; however, if the AP MLD receives a delayed response frame from the second link for AP 2, the AP MLD may return the lowered MCS index and the increased channel access parameter to their original values.

[0037] Additionally, according to one embodiment of the present specification, after the AP determines the communication unavailable period of the first STA in the TXOP of the AP based on the response frame, if the AP receives a return frame from the first STA indicating an early termination of the communication unavailable period of the first STA, the AP may resume communication with the first STA.

[0038] In addition, according to one embodiment of the present specification, the AP further transmits a first frame indicating a communication unavailable period of the AP, wherein the first frame includes at least one of information on the communication unavailable period of the AP and information on the reason for the communication unavailable period of the AP, and when the communication unavailable period of the AP ends, the AP can perform communication with the first STA without a re-association procedure based on the maintained configuration information.

[0039] Additionally, according to one embodiment of the present specification, if the AP transmits a return frame indicating an early termination of the AP's communication outage period before the expiration of the AP's communication outage period, the AP may resume communication with the first STA.

[0040] In addition, according to one embodiment of the present specification, the AP further receives a second frame indicating a communication unavailable period of the STA, wherein the second frame includes at least one of information on the communication unavailable period of the STA and information on the reason for the communication unavailable period of the STA, and when the communication unavailable period of the STA ends, the AP can perform communication with the first STA without a re-association procedure based on the maintained configuration information.

[0041] Additionally, according to one embodiment of the present specification, if the AP receives a return frame indicating an early termination of the STA's communication unavailability period before the expiration of the STA's communication unavailability period, the AP may resume communication with the first STA.

[0042] Additionally, according to one embodiment of the present specification, the AP further receives a third frame indicating at least one of a reception-only interval and a transmission-only interval of the STA, wherein the third frame includes an indicator indicating a suspension of a block response policy, and the AP can change the block response policy based on the indicator.

[0043]

[0044] According to the present disclosure, a method for performing communication while considering an operation restriction section in a wireless LAN can be provided.

[0045] According to the present disclosure, a method for indicating the availability of wireless resources in a wireless LAN and performing communication based on the indication can be provided.

[0046] According to the present disclosure, a method for performing communication based on an indication of wireless resource availability in a wireless LAN can be provided.

[0047] According to the present disclosure, a method for indicating a communication failure situation based on the internal operation of a wireless LAN device and for suspending and resuming communication according to the indicated communication failure situation can be provided.

[0048] According to the present disclosure, a method for handling a communication failure situation based on an IDC inside a wireless LAN device can be provided.

[0049] According to the present disclosure, the present disclosure can provide a method for performing communication based on an indication of wireless resource availability based on an artificial intelligence algorithm.

[0050] According to the present disclosure, a method for indicating a communication failure situation based on an artificial intelligence algorithm and for suspending and resuming communication according to the indicated communication failure situation can be provided.

[0051] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below. The effects that can be obtained in the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below.

[0052]

[0053] Figure 1 is a diagram showing a communication node within a wireless LAN system to which the present disclosure is applied.

[0054] Figure 2 is a diagram showing a wireless LAN system to which the present disclosure is applied.

[0055] FIG. 3 is a diagram illustrating a machine learning unit to which the present disclosure is applied.

[0056] FIG. 4 is a flowchart illustrating a method for performing communication based on a machine learning unit to which the present disclosure is applied.

[0057] FIG. 5 is a diagram illustrating a method for negotiating coexistence situation operation before indicating available links in a wireless LAN to which the present disclosure is applied.

[0058] FIG. 6 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied.

[0059] FIG. 7 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied.

[0060] FIG. 8 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied.

[0061] FIG. 9 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied.

[0062] FIG. 10 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied.

[0063] FIG. 11 is a diagram illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure.

[0064] FIG. 12 is a diagram illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure.

[0065] FIG. 13 is a diagram illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure.

[0066] FIG. 14 is a diagram illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure.

[0067] Figures 15a to 15c are diagrams showing a method for resuming communication after a communication unavailable section instruction applied to the present disclosure.

[0068] FIG. 16a and FIG. 16b are diagrams showing a method for resuming communication after indicating a communication failure section in a wireless LAN applicable to the present disclosure.

[0069] FIG. 17a and FIG. 17b are diagrams showing a method for resuming communication after indicating a communication unavailable section in a wireless LAN applicable to the present disclosure.

[0070] FIG. 18a and FIG. 18b are diagrams showing a method for resuming communication after indicating a communication unavailable section in a wireless LAN applicable to the present disclosure.

[0071] Figure 19 is a diagram illustrating a method for resuming communication after indicating a communication failure section in a wireless LAN applicable to the present disclosure.

[0072] Figure 20 is a flowchart illustrating an operation method of an AP that indicates an available link in a wireless LAN applied to the present disclosure.

[0073] FIG. 21 is a flowchart illustrating an operation method of an STA indicating an available link in a wireless LAN applied to the present disclosure.

[0074]

[0075] This disclosure may be subject to various modifications and various embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the disclosure to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the disclosure.

[0076] While terms such as first, second, etc. may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present disclosure, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a 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.

[0077] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0078] The terminology used in this disclosure is only used to describe specific embodiments and is not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this disclosure, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0079] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0080] 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 in describing the present disclosure, identical reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0081] 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 description below, and the embodiments according to the present disclosure can be applied to various wireless communication systems. The wireless communication system may be referred to as a "wireless communication network."

[0082] FIG. 1 is a diagram illustrating a communication node within a wireless LAN system to which the present disclosure applies. Referring to FIG. 1, a communication node (100) may include at least one of a processor (110), a 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 (AP) 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 other nodes or devices based on the above-described configuration. For example, the operating channel width supported by the AP may be 20 megahertz (MHz), 80 MHz, 160 MHz, etc. The operating channel width supported by the station may be 20 MHz, 80 MHz, etc. However, the present invention may not be limited thereto.

[0083] The processor (110) within the 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) as each component within the communication node. The memory (120) within the communication node (100) can store information on commands and instructions executed by the processor (110), and the transceiver (130) can refer to a transceiver, a radio frequency (RF) 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, can be linked with other interfaces, and can further include a separate storage device (150). Each component within the communication node (100) can be connected by a bus (160) to communicate with each other.

[0084] However, as an example, each component included in the communication node (100) may be connected through an individual interface or individual bus centered around the processor (110), rather than a common bus (160). The processor (1110) may be connected to at least one of the memory (120), the transmission / reception device (130), the input / output interface device (140), and the storage device (150) through a dedicated interface.

[0085] The processor (110) can execute program commands stored in at least one of the memory (120) and the storage device (150). The processor (110) may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which the methods according to embodiments of the present disclosure are performed. Each of the memory (120) and the storage device (150) may be configured with at least one of a volatile storage medium or a non-volatile storage medium. For example, the memory (120) may be configured with at least one of a read-only memory (ROM) or a random access memory (RAM).

[0086] FIG. 2 is a diagram illustrating a wireless LAN system to which the present disclosure applies. Referring to FIG. 2, a basic service set (BSS) of the wireless LAN system may include one AP (210) and multiple STAs (221, 222, 223, 224), and the multiple STAs (221, 222, 223, 224) may be controlled by the AP (210). However, the wireless LAN system is not limited to the BSS, and an environment consisting only of STAs without a defined 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 medium access control (MAC) layer and a physical (PHY) layer, and communication may be performed between the wireless devices. For the convenience of explanation, the following description focuses on APs and STAs, but may not be limited thereto. For example, the following may equally apply to other communication nodes or devices and are not limited to a specific form.

[0087] Figure 3 is a diagram illustrating a machine learning unit to which the present disclosure applies. Each wireless device within a wireless LAN system may be connected to a machine learning unit (300). However, this may not be limited to this, and wireless devices not connected to the machine learning unit (300) may also operate.

[0088] For example, the processor (110) of the communication node (100) of FIG. 1 may be connected to the machine learning unit (300). The machine learning unit (900) may be connected to the processor (110) through the input / output interface device (140) of the communication node (100) to communicate. As another example, the machine learning unit (300) may be connected to the processor (110) through the bus (160) of the communication node (100) to communicate. As another example, the machine learning unit (300) may be connected to the processor (110) of the communication node (100) through a separate interface or a dedicated bus to communicate. The machine learning unit (300) may be connected to the memory (120), the transceiver (130), and the storage device (140) through the input / output interface device (140), the bus (160), or the dedicated bus to communicate, but may not be limited to a specific form.

[0089] For example, the machine learning unit (300) may include at least one ML (Machine Learning) processor (310), ML memory (320), ML input / output interface (330), and ML bus (340). The ML processor (310), ML memory (320), and ML input / output interface (330) may be connected to and communicate with each other through the ML bus (340). As another example, the ML processor (310) may be connected to and communicate with at least one of the ML memory (320) and the ML input / output interface (330) through a dedicated bus or interface. The ML processor (310) may be a central processing unit, a graphics processing unit, a dedicated processor on which methods according to embodiments of the present disclosure are performed, or a processor in which at least one of the central processing unit and the dedicated processor is combined. The ML processor (310) may include at least one of a training unit (311), a verification unit (312), a performance unit (313), and an updating unit (313). The training unit (311), the verification unit (312), the performance unit (313), and the updating unit (313) may be logical entities configured by software or hardware processing devices. For example, the ML processor (310) may perform at least one of training, verification, execution, and updating of a machine learning model. The machine learning model may be in the form of a plurality of matrices or vectors. As a specific example, the machine learning model may include weights, a transition matrix, and hyperparameters that implement and learn a single or multiple combined machine learning algorithms (e.g., a deep neural network (DNN), a convolutional neural network (CNN), a recurrent neural network (RNN), and a deep reinforcement learning (DRL) algorithm).A machine learning model may include an input layer, at least one hidden layer, and an output layer to implement a deep neural network (DNN) algorithm. Each of the input layer, hidden layer, and output layer may include at least one perceptron (e.g., an artificial neuron). The perceptron includes an activation function, input weights, and a bias. Multiple perceptrons may have inputs and outputs connected to form an input layer, a hidden layer, and an output layer. The machine learning model may include a convolution algorithm and the DNN algorithm to implement a CNN algorithm. The convolution algorithm convolves a kernel matrix with input data in matrix form and may be performed at least once on the input data. When the convolution algorithm is performed on the input data, the size of the data may be increased through concatenation or reduced through pooling. The input data on which the convolution algorithm has been performed at least once is used as input data for the DNN algorithm. For example, a machine learning model may include a DNN algorithm and a cell structure to implement an RNN algorithm. The cell structure may be a structure that remembers previous input data and inputs it on its own, and may be used in at least one perceptron of the DNN algorithm. A machine learning model may include an agent, an environment structure, and a DNN algorithm to implement a DRL algorithm. In a DRL algorithm, an agent can observe the environment and perform an optimal action based on the observed data. The environment can provide feedback as a reward to the agent based on the agent's action. Based on the above, the agent can learn a policy for taking an optimal action.Agents can use DNN algorithms to learn optimal actions.

[0090] As another example, the machine learning unit (300) may be designed to additionally implement other machine learning algorithms in addition to the aforementioned machine learning algorithms (e.g., DNN, CNN, RNN, and DRL). To this end, the machine learning unit (300) may include additional components for implementing other machine learning algorithms. The ML memory (320) within the machine learning unit (300) may store machine learning models and machine learning algorithms. The implementation of the machine learning algorithms may be performed by the ML processor (310) based on the machine learning models.

[0091] As another example, all or part of the functions of the machine learning unit (300) may be integrated into the processor (110) and memory (120) of the communication node (100). That is, the processor (110) of the communication node (100) may perform all or part of the functions of the ML processor (310), and the memory (120) may perform all or part of the functions of the ML memory (320). When the processor (110) and memory (120) of the communication node (100) perform all of the functions of the machine learning unit (300), the machine learning unit (300) may not be connected by the input / output interface (140), and the processor (110) and memory (120) may operate as the machine learning unit (300).

[0092] As another example, the machine learning unit (300) may be connected not through the input / output interface (140) of the communication node (100), but through a bus (160), or through a dedicated bus or interface centered around the processor (110) of the communication node (100), but may not be limited to the above embodiment.

[0093] FIG. 4 is a flowchart illustrating a method for performing communication based on a machine learning unit to which the present disclosure is applied. Referring to FIG. 4, the machine learning unit (300) is connected to a communication node (100), collects communication data, and can perform prediction based on a machine learning model (S410). As an example, the above-described prediction may be performed by the execution unit (313) of the machine learning unit (300), but is not limited thereto. Here, the communication data collected by the machine learning unit (300) may include at least one of channel noise status, channel congestion, reception strength, collision frequency, and other information obtained from a physical layer. In addition, the communication data may include information obtained from a MAC layer, and is not limited to a specific form. The communication data collected by the machine learning unit (300) may be provided as input to the machine learning model itself. As another example, the communication data collected by the machine learning unit (300) may be provided as input to the machine learning model after being operated or processed. For example, the prediction result of the machine learning unit (300) may be at least one of a physical layer and MAC parameter (e.g., MCS (modulation and coding scheme) parameter, beamforming parameter, EDCA (enhanced distributed channel access) parameter, etc.). As another example, the prediction result of the machine learning unit (300) may be information for packet scheduling, multi-AP operation scheduling, and other scheduling, but is not limited to a specific form. As another example, the communication node (100) may receive all or part of the machine learning model from another communication node. All or part of the machine learning model may be collected by the machine learning unit (300) and is not limited to a specific form. As an example, the communication node (100) may perform communication based on the prediction of the machine learning unit (300).(S420) In addition, the machine learning unit (300) can collect communication data based on the performed communication, and based on this, machine learning model verification can be performed (S430) or machine learning model training (S440) can be performed. In addition, as an example, the machine learning model can be exchanged with other communication nodes (S450), and the exchanged machine learning model information can be used for machine learning model verification or machine learning model training. As an example, when machine learning model verification is performed, it can be verified whether the communication operation performed by the prediction of the machine learning unit (300) is appropriate. As a specific example, the machine learning model verification can be performed based on at least one of the frame collision frequency, transmission error frequency, and packet transmission delay of the communication node (100), and an operation of determining whether the communication performance of the communication node (100) has been improved can be performed.

[0094] In addition, for example, if it is determined that training of a machine learning model is necessary (e.g., if communication performance has not improved, if it is determined that the performance of a machine learning model of another communication node (e.g., all or part of the machine learning model) is superior to that of the current communication node (100), the communication node (100) may perform machine learning model training. In another example, the communication node (100) may exchange the machine learning model with other communication nodes without performing machine learning model verification or machine learning model training. In addition, for example, if it is determined that training of a machine learning model is not necessary, the communication node (100) may exchange the machine learning model with other communication nodes without performing machine learning model training.

[0095] Here, the machine learning model may be trained (or learned) based on at least one of the collected communication data and all or part of the machine learning model of another communication node. The training of the machine learning model may be performed by the training unit (311) and may be performed based on at least one of the collected communication data and the output of the machine learning model of another communication node and the machine learning model of the communication node (100).

[0096] As another example, part or all of the machine learning model of the communication node (1000) may be replaced with part or all of the machine learning model of another communication node by the updating unit (314) of the machine learning unit (300). As another example, the machine learning model (e.g., part or all of the machine learning model) of the communication node (100) may be shared with another communication node. Alternatively, the communication node (100) may operate only based on machine learning model verification and training without exchanging the machine learning model with other communication nodes, and is not limited to a specific form. As an example, in the present disclosure, at least one of changing the order, adding or removing steps, and repeating specific steps may be performed in the steps of the flowchart. In other words, the flowchart is an example describing the operation of the machine learning unit (300) of the wireless communication node (100), and the procedures and operations thereof may be modified in various ways. For example, after training a machine learning model, it may be possible to perform a machine learning model validation step again to validate the trained machine learning model, and it may not be limited to a specific form.

[0097] Hereinafter, a method for indicating an available link in a wireless LAN is described. In a wireless LAN network, an access point (AP, e.g., AP 1) and multiple stations (STAs, non-AP STAs) (e.g., STA 1, STA X, STA Y, etc.) can operate. Multiple STAs can be connected (or associated) to AP 1 and perform communication based on the connection. Here, X and Y are natural numbers that can be different from each other and can be referred to to distinguish the STAs. For example, STA 1 and STA Y can be ultra high reliability (UHR) STAs. Specifically, STA 1 and STA Y can be terminals that support UHR and IEEE 802.11bn or a later developed IEEE 802.11 communication protocol. On the other hand, STA X can be a legacy terminal. That is, STA X may be a terminal that supports an IEEE 802.11 communication protocol (e.g., IEEE 802.11ac, IEEE 802.11ax, IEEE 802.11be) developed prior to the UHR and IEEE 802.11bn protocols. Therefore, STA X may not support UHR and IEEE 802.11bn functions, and may not recognize frame formats and functions newly added in IEEE 802.11bn. However, this is only one example and may not be limited to the embodiment.

[0098] In the present disclosure, IEEE 802.11bn may be referred to as UHR, and IEEE 802.11bn functions may be referred to as UHR functions. Conversely, UHR may be interpreted as IEEE 802.11bn. In addition, the use of other names should be interpreted similarly to the above-described designation method. For example, the UHR frame format should be understood as the IEEE 802.11bn frame format, and the IEEE 802.11bn frame format may also be understood as the UHR frame format. However, for the convenience of explanation, the following description will be based on the UHR function and UHR frame format.

[0099] For example, STA 1 may negotiate with AP 1 for dynamic unavailability operation (DUO) operation and receive an initial control frame (ICF) before receiving a downlink data frame from AP 1. The procedure for determining whether STA 1 can communicate or not through ICF and RCF exchange may be a DUO operation, which will be described later.

[0100] Here, a situation in which STA 1 cannot communicate can be considered. A basic NAV (network allocation vector) may be set for STA 1 by another wireless LAN terminal. Communication by another wireless LAN terminal may be any one of communication by an AP other than the aforementioned AP 1, communication by STAs connected to an AP other than AP 1, and communication by an overlapping BSS (basic service set) but may not be limited thereto. Alternatively, STA 1 may not be able to communicate due to coexistence within the device. For example, STA 1 may transmit or receive data using a wireless communication technology other than wireless LAN. In the above-described case, wireless LAN transmission and reception of STA 1 may be limited, and STA 1 may be able to transmit only short control frames.

[0101] AP 1 may want to transmit a downlink data frame to STA 1. AP 1 may perform a channel access operation to transmit data to STA 1. The channel access operation may be an enhanced distributed channel access (EDCA) backoff operation. Here, AP 1 may succeed in the channel access operation. Success in the channel access operation may mean that EDCAF (EDCA function) initiates transmission at a slot boundary of a slot in which the EDCA backoff counter reaches 0. When EDCAF initiates transmission, AP 1 may be granted a transmit opportunity (TXOP). That is, AP 1 may obtain a TXOP, but is not limited to a specific term. A TXOP may be a time period in which a wireless LAN terminal can transmit multiple frames.

[0102] For example, AP 1 may transmit the above-described ICF to STA 1 as the first frame of TXOP. The ICF may be a frame in a specific format, such as a trigger frame (e.g., MU (multi-user)-RTS (request to send) trigger frame, BSRP (buffer status report poll) trigger frame) or an RTS frame. However, the ICF may not be limited to a specific form. STA 1 may be unable to communicate due to the above-described basic NAV setting or coexistence within the device. Therefore, STA 1 may transmit a response control frame (RCF) as a response frame to the ICF transmitted by AP 1, and the RCF may include an indicator indicating that STA 1 is unable to communicate. As another example, the RCF may include at least one of an indicator indicating that STA 1 is unable to communicate and an indicator indicating a communication unavailable period of STA 1.

[0103] An indicator indicating that communication is impossible and an indicator indicating a communication impossible section may be included in the RCF in at least one of a subfield, a field, an information element, an element, an indication bit, and a bit, but may not be limited to a specific form. An indicator indicating a communication impossible section may indicate at least one of a start time of a communication impossible section and an end time of a communication impossible section. Here, the end time of a communication impossible section may be a time when communication is possible.

[0104] As another example, the RCF frame may further include an indicator prohibiting NAV release. The indicator prohibiting NAV release may indicate that an STA that decodes the RCF frame prohibits NAV release even when the RCF frame is received.

[0105] STA X and STA Y can receive the ICF transmitted by AP 1. When STA X and STA Y detect a frame for the ICF (e.g., when the primitive PHY-RXSTART.indication of each PHY layer included in STA X and STA Y is generated, or when the channel is detected as busy as a result of carrier sense), STA X and STA Y can set the NAV as much as the value of the duration field included in the MAC header of the ICF. The value of the duration field included in the MAC header of the ICF can be set to a value corresponding to the TXOP of AP 1. That is, the NAV set in STA X and STA Y can be set up to the TXOP of AP 1.

[0106] STA X, which is a legacy STA, may not be able to decode an RCF frame, which is a UHR frame. That is, STA X may not be able to receive an RCF frame transmitted by STA 1, which is a UHR STA, and thus STA X may continue to maintain the NAV without releasing it. On the other hand, STA Y, which is a UHR STA, can decode an RCF frame, which is a UHR frame. If STA Y decodes the RCF frame, STA Y may release the NAV set through the RCF frame in advance. However, if the RCF frame includes an indicator prohibiting NAV release, STA Y may not release the NAV even after decoding the RCF frame.

[0107] For example, the operations illustrated in FIGS. 5 to 13 below may be based on the aforementioned situations. Furthermore, the operations illustrated in FIGS. 5 to 13 below may be performed individually or as a combination of specific operations based on the aforementioned situations, and may not be limited to a specific form.

[0108] FIG. 5 is a diagram illustrating a method for negotiating coexistence situation operation before indicating available links in a wireless LAN to which the present disclosure is applied.

[0109] Referring to FIG. 5, as described above, STA 1 (520) may be unable to communicate with AP 1 (510). Here, STA 1 (520) may initiate a procedure that allows it to indicate to AP 1 (510) a section where communication is impossible. For example, AP 1 (510) may perform a procedure to determine whether STA 1 (520) is unable to communicate.

[0110] Specifically, AP 1 (510) may transmit an ICF to STA 1 (520), and STA 1 (520) may transmit an RCF in response thereto. For example, the RCF may be referred to as an ICR (initial control response). In addition, the RCF may be referred to by other names and is not limited to a specific form. The RCF may indicate whether STA 1 (520) is capable of communication. That is, the RCF may indicate whether STA 1 (520) is capable of communication or not. In addition, the RCF may further indicate maximum time information as the communication possible time of STA 1 (520) or maximum time information as the communication impossible time. For example, a procedure for confirming whether STA 1 (520) is capable of communication or not through an ICF and RCF exchange may be referred to as a DUO (dynamic unavailability operation) operation. However, it may not be limited to that name, but for convenience of explanation, it is referred to as DUO below.

[0111] When a communication failure occurs, STA 1 (520) must perform a frame exchange procedure for DUO operation. For example, STA 1 (520) may transmit a frame including an indicator indicating the use of DUO operation to AP 1 (510). For example, the frame including the indicator indicating the use of DUO may be an ultra high reliability (UHR) operating mode notification (OMN) frame (601-1). For example, the UHR OMN frame may be an action frame. AP 1 (510) may receive the above-described frame (601-1) and transmit a frame (601-2) including an indicator confirming the use of DUO to STA 1 (520). The frame (601-2) including the indicator confirming the use of DUO may be a frame having the same or a similar format as the frame (601-1) including the indicator indicating the use of DUO. The DUO operation may be initiated after a certain period of time after STA 1 (520) transmits a frame (601-1) containing an indicator indicating the use of the DUO operation to AP 1 (510). That is, after a certain period of time after STA 1 (520) transmits a frame (601-1) containing an indicator indicating the use of the DUO operation to AP 1 (510), AP 1 (510) may transmit an ICF (601) to STA 1 (520) and receive an RCF (602) from STA 1 (520).

[0112] As another example, the DUO operation may be initiated when STA 1 (520) transmits a frame (601-1) containing an indicator indicating the use of DUO to AP 1 (510) and then receives a frame (601-2) containing an indicator confirming the use of DUO from AP 1 (510), but may not be limited to that embodiment.

[0113] As another example, whether STA 1 (520) supports DUO operation (or DUO mode) may be indicated. STA 1 (520) may be a wireless LAN terminal that supports DUO operation (or DUO mode) or may not support it. That is, depending on the wireless LAN terminal type, whether STA 1 (520) supports DUO operation may vary, and information on whether DUO operation is supported may be transmitted. In addition, AP 1 (510) may also be a wireless LAN terminal that supports DUO operation (or DUO mode) or may not support it. That is, depending on the wireless LAN terminal type, whether AP 1 (510) supports DUO operation may vary, and information on whether DUO operation is supported may be transmitted.

[0114] For example, STA 1 (520) supporting DUO operation can transmit a request frame indicating whether to use DUO operation (or whether to enable DUO mode) to AP 1 (510). Here, an indicator indicating whether to use DUO operation can be included in the request frame, but is not limited to the embodiment. AP 1 (510) can transmit a response frame to STA 1 (520) in response to the request frame, and based on the above, AP 1 (510) and STA 1 (520) can perform DUO operation (or DUO mode).

[0115] When AP 1 (510) and STA 1 (520) use DUO operation, AP 1 (510) may always transmit an ICF before transmitting a downlink data frame to STA 1 (520). For example, the ICF may be a BSRP (Buffer Status Report Poll) trigger frame. The BSRP trigger frame may be referred to as a BSRP frame in the present disclosure. As another example, the ICF may be a MU (multi-user)-RTS (request to send) trigger frame. In addition, as an example, the ICF may be a frame for a case where DUO operation (or DUO mode) of STA 1 (520) is permitted, but may not be limited thereto. That is, when AP 1 (510) successfully performs a channel access operation and transmits a downlink data frame to STA 1 (520), AP 1 (510) can transmit an ICF to STA 1 (520) before transmitting the downlink data frame. Meanwhile, when AP 1 (510) successfully performs a channel access operation and transmits a frame other than a downlink data frame to STA 1 (520) (e.g., a trigger frame that allocates uplink resources to STA 1 (520)), AP 1 (510) can transmit an ICF to STA 1 (520) before transmitting the other frame.

[0116] When STA 1 (520) receives the ICF (602-1) of AP 1 (510) and can receive a downlink data frame (604-1) from AP 1 (510), STA 1 (520) can transmit an RCF (603-1) to AP 1 (510) indicating whether STA 1 (520) can receive the downlink data frame (604-1). For example, the RCF (603-1) may be a Multi-STA BlockAck (BA) frame, but is not limited thereto. When AP 1 (510) receives the RCF (603-1) of STA 1 (520), it can transmit a downlink data frame (604-1) to STA 1 (520).

[0117] On the other hand, if STA 1 (520) is unable to receive a downlink data frame, STA 1 (520) may instruct AP 1 (510) that STA 1 (520) is unable to receive a downlink data frame. For example, STA 1 (520) may transmit to AP 1 (510) an RCF (603-2) indicating a time and a period during which STA 1 (520) can receive frames. Alternatively, STA 1 (520) may transmit to AP 1 (510) an RCF (603-2) indicating a time and a period during which STA 1 (520) is unable to receive data frames. When AP 1 (510) receives RCF (603-2), it may not transmit a downlink data frame (604) to STA 1 (520) during the unavailable period from the time when data frame reception is impossible as indicated by RCF (603-2).

[0118] Also, as an example, the start time of the data reception unavailable period of STA 1 (520) may be indicated in the RCF (603-2) that STA 1 (520) transmits in response to the ICF (602-2) of AP 1 (510). The start time of the data reception unavailable period may occur after the RCF (603-2) is transmitted. In the opposite interpretation, STA 1 (520) may be able to transmit and receive data frames until the start time of the data reception unavailable period even after the RCF (603-2) is transmitted. AP 1 (510) may set the duration field value of the MAC header of the ICF (602-2) transmitted to STA 1 (520) to a value equal to "the expected time length of the RCF (603-2) transmitted by STA 1 (520) + SIFS". In addition, when STAs other than STA 1 (520) receive the ICF (602-2) transmitted by AP 1 (510), they may set a network allocation vector (NAV). Here, the length of the NAV may be the duration field value of the MAC header of the ICF (602-2) (i.e., “expected time length of the RCF transmitted by STA 1 (520) + SIFS”). The NAV may be a period in which virtual carrier sensing is set to busy (or occupied). STAs may detect the channel as busy during the period in which the NAV is set and may not perform a channel access operation for frame transmission.

[0119] STA 1 (520) can receive ICF (602-2) of AP 1 (510) and transmit RCF (603-2). Here, since STA 1 (520) is a receiving target of ICF (602-2) transmitted by AP 1 (510), it can transmit RCF (603-2) indicating the start time of a data reception unavailable period of STA 1 (520) without setting NAV. For example, the value of the duration field of the MAC header of RCF (603-2) can be set to 0. If the value of the duration field of the MAC header of RCF (603-2) transmitted by STA 1 (520) is 0, STAs other than AP 1 (510) can terminate NAV upon receiving RCF (603-2) without updating NAV.

[0120] As another example, the MAC header duration field value of the RCF (603-2) may indicate a value until the start of the data reception unavailable period after the RCF transmission of STA 1 (520). STAs other than AP 1 (510) that received the RCF (603-2) of STA 1 (520) may update their NAVs upon receiving the RCF (603-2). If the MAC header duration field value of the RCF (603-2) indicates a value until the start of the data reception unavailable period after the RCF (603-2) transmission of STA 1 (520), other STAs may set (update) their NAVs until the start of the data reception unavailable period of STA 1 (520). AP 1 (510) can check the start time of the data reception unavailable period indicated by RCF (603-2) of STA 1 (520) and terminate frame exchange (downlink data frame (604-2) transmission and response frame reception for the downlink data frame) with STA 1 (520) before that time. Therefore, AP 1 (510) can early terminate TXOP (transmit opportunity), which is a time resource for performing frame exchange of AP 1 (510). Meanwhile, STAs other than STA 1 (520) and AP 1 (510) can set NAV to protect RCF (603-2) transmission of STA 1 (520) upon receiving ICF (602-2). For example, STAs other than STA 1 (520) and AP 1 (510) need not set the NAV to an unnecessarily long length even when RCF (603-2) indicates that STA 1 (520) cannot transmit or receive data.In addition, if the TXOP initially acquired by AP 1 (510) is prematurely terminated by the start time of the data reception unavailable interval indicated by the RCF (603-2) of STA 1 (520), the value of the duration field of the MAC header of the RCF (603-2) of STA 1 (520) and / or the downlink data frame (604-2) that AP 1 (510) transmits to STA 1 (520) may be set to a time before the start time of the data reception unavailable interval indicated by the RCF (603-2) of STA 1 (520), which is the early termination time of the TXOP. Accordingly, STAs other than STA 1 (520) and AP 1 (510) may set a NAV corresponding to the end time of the early terminated TXOP, rather than a NAV corresponding to the length of the TXOP initially acquired by AP 1 (510), and may prevent the NAV from being set unnecessarily long.

[0121] For example, the above-described DUO-based operation disclosed in FIG. 5 may be used before the method of indicating available links in a wireless LAN disclosed in FIGS. 6 to 13 described below is used.

[0122] FIG. 6 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied. Referring to FIG. 6, AP 1 (510) can transmit an ICF (e.g., MU-RTS, 605) and receive an RCF (606) from STA 1 (520). AP 1 (510) can recognize that STA 1 (520) is unable to communicate through the RCF (606). Here, AP 1 (510) can consider that there is no frame to be transmitted to STA 1 (520) in the transmission queue. Here, AP 1 (510) has no more frames to transmit and may want to release the set NAV. Therefore, AP 1 (510) can transmit a CF (contention free)-End frame (607). The CF-End frame (607) may be a frame used when releasing the NAV. STA X (530) may receive the CF-End frame (607) and release the set NAV. On the other hand, STA Y (540) may decode the RCF (606) and recognize that STA 1 (520) is unable to communicate. Here, STA Y (540) may release the NAV when it decodes the RCF (606). Since STA Y (540) released the NAV in advance, there may not be a set NAV when it receives the CF-End frame (607). Therefore, STA Y (540) may ignore the CF-End frame (607). As another example, STA Y (540) may detect the RCF (606) but may not be able to decode it due to a reception error. In the above-described case, STA Y (540) can release the NAV set by ICF (605) when receiving the CF-End frame (607). Here, STA X (530) and STA Y (540) whose NAVs have been released can perform a channel access operation, and if the channel access operation is successful, can transmit a frame.

[0123] As another example, the duration field value of the MAC header of the ICF (605) that AP 1 (510) transmits to STA 1 (520) may be set to only the length of time (e.g., expected length of the ICF + SIFS) that is transmitted to STA 1 (520). As an example, the duration field of the MAC header of the RCF (606) that STA 1 (520) transmits to AP 1 (510) may be set to 0. Meanwhile, STAs other than STA 1 (e.g., STA X, STA Y) may initially receive the ICF (605) of AP 1 (510) and set the NAV. The NAV may be set to the amount of time required for the ICF (605) of STA 1 (520) to be transmitted. If the duration field value of the MAC header of the RCF (606) transmitted by STA 1 (520) is set to 0, STAs other than STA 1 (520) (e.g., STA X, STA Y) may not update the NAV for a longer period. That is, the NAV may be terminated after the transmission of the RCF (606) is completed. STAs other than STA 1 may minimize unnecessary NAVs set after the transmission of the RCF (606). For example, the above-described method may set the NAV by setting the duration field value of the MAC header of the ICF (605) using a single protection method.

[0124] As another example, AP 1 (510) may recognize that STA 1 (520) is unable to communicate through RCF (606). Here, AP 1 (510) may consider that there is no frame to be transmitted to STA 1 (520) in the transmission queue. Even if AP 1 (510) considers that there is no frame to be transmitted to STA 1 (520) in the transmission queue, there may be a frame to be transmitted in the transmission queue (e.g., a data frame whose destination is not STA 1 (520)). AP 1 (510) may transmit more frames to be transmitted that exist in the transmission queue. If the end point of the data frame exchange transmitted by AP 1 (510) is terminated earlier than the communication section indicated by the value of the duration field of the MAC header of ICF (605), AP 1 (510) may want to release the set NAV. Therefore, AP 1 (510) can transmit a CF (contention free)-End frame (607).

[0125] FIG. 7 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied.

[0126] Referring to FIG. 7, AP 1 (510) can transmit ICF (e.g. MU-RTS, 608) and receive RCF (609) from STA 1 (520). AP 1 (510) can recognize that STA 1 (520) is unable to communicate through RCF (602). Here, AP 1 (510) can consider that there is no frame to be transmitted to STA 1 (520) in the transmission queue. On the other hand, AP 1 (510) may have data to be transmitted to another STA (e.g. STA X). For example, AP 1 (510) may transmit a downlink data frame (610) to STA X (530), and STA X (530) may transmit a response frame (e.g., BA (block ACK (acknowledgement)) frame, ACK frame, 611) in response to the downlink data frame (610) of AP 1 (510). AP 1 (510) may transmit downlink data frames to STAs except for STA 1 (520) with which communication is impossible by using all of its TXOPs, or may perform a TXOP sharing operation to share a communication section with STAs except for STA 1 (520). For example, the TXOP sharing operation may be a triggered TXOP sharing operation. Even if STA Y (540) decode RCF (609) and release NAV, it can set NAV again when it detects a frame (e.g., downlink frame) of AP 1 (510). Here, NAV can be set as much as TXOP of AP 1 (510). That is, the value of the duration field of the MAC header of the frame of AP 1 (510) can indicate the end point of the TXOP of AP 1 (510), and when STA Y (540) detects a frame of AP 1 (510), it can check the value of the duration field of the MAC header and set NAV again.

[0127] FIG. 8 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied.

[0128] Referring to FIG. 8, AP 1 (510) can transmit an ICF (e.g., MU-RTS, 612) and receive an RCF (613) from STA 1 (520). AP 1 (510) can recognize that STA 1 (520) is unable to communicate through the RCF (613). Here, AP 1 (510) can consider that there is no frame to be transmitted to STA 1 (520) in the transmission queue. On the other hand, AP 1 (510) may have data to be transmitted to another STA (e.g., STA X). AP 1 (510) may transmit a downlink data frame (614) to STA X (530), and STA X (530) may transmit a response frame (e.g., BA (block ACK (acknowledgement)) frame, ACK frame, 615) in response to the downlink data frame (614) of AP 1 (510). AP 1 (510) may transmit downlink data frames to STAs excluding STA 1 (520) with which communication is impossible by using some or all of its TXOP, or may perform a TXOP sharing operation to share a communication section with STAs excluding STA 1 (520). For example, the TXOP sharing operation may be a triggered TXOP sharing operation.

[0129] After that, AP 1 (510) can transmit a downlink frame (616) to STA 1 (520) within the TXOP of AP 1 (510) at the time when STA 1 (520) can communicate. STA 1 (520) can transmit a response frame (e.g., BA (block ACK (acknowledgement)) frame, ACK frame, 617) in response to the downlink data frame (616) of AP 1 (510). As another example, AP 1 (510) may not transmit a downlink frame to STA 1 (520) within the TXOP of AP 1 (510). As a specific example, if the communication possible time of STA 1 (520) is after the TXOP of AP 1 (510) or when the TXOP of AP 1 (510) is running low, AP 1 (510) may not be able to transmit a downlink frame to STA 1 (520).

[0130] Here, AP 1 (510) can perform a channel access operation after TXOP is over, and if the channel access operation is successful, can transmit a downlink frame to STA 1 (520). In addition, AP 1 (510) can transmit ICF first before transmitting a downlink data frame to STA 1 (520) at a time when STA 1 (520) can communicate or after STA 1 (510) can communicate. Even if STA Y (540) decodes RCF (613) and releases NAV, it can set NAV again if it detects a frame (e.g., downlink frame) of AP 1 (510). Here, NAV can be set as much as TXOP of AP 1 (510).

[0131] FIG. 9 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure is applied. Referring to FIG. 9, AP 1 (510) can transmit an ICF (e.g., MU-RTS, 618) and receive an RCF (619) from STA 1 (520). AP 1 (510) can recognize that STA 1 (520) is unable to communicate through the RCF (619). The RCF (619) can indicate a communication unavailable section of STA 1 (520). Here, the RCF (619) of STA 1 (520) can include an indicator for prohibiting NAV release. The reason why STA 1 (520) includes an indicator for prohibiting NAV release in the RCF (619) may be to prohibit transmission by other STAs or APs on the channel. That is, the directive to prohibit NAV release may be for the purpose of channel quiet. STA 1 (520) may have a purpose of performing communication (e.g., direct communication, non-wireless LAN communication, etc.) within the TXOP of AP 1 (510). AP 1 (510) may receive RCF (619) and may not perform any frame transmission until the communication-capable time of STA 1 (520). Since NAV is set for STA X (530) and STA Y (540) during the TXOP of AP 1 (510), STA X (530) and STA Y (540) may detect that the channel is busy (or occupied) and may not perform any frame transmission.

[0132] As another example, AP 1 (510) may transmit a frame (not shown) indicating channel quiet after receiving RCF (619). The frame indicating channel quiet may be a frame including a quiet time period (QTP) and a quiet element (e.g., a beacon frame, a probe response frame). As an example, STA 1 (520) may perform communication using a wireless communication technology other than wireless LAN communication, or may perform direct wireless LAN communication. AP 1 (510) may transmit a frame indicating channel quiet during a period corresponding to a communication unavailable period of STA 1 (520). Meanwhile, the end time of the communication unavailable period indicated by STA 1 (520) may be later than the end time of the TXOP acquired by AP 1 (510). In this case, AP 1 (510) may indicate channel quiet only until the TXOP acquired by AP 1 (510), or AP 1 (510) may transmit a frame indicating channel quiet during a period corresponding to a communication unavailable period that ends after the TXOP acquired by AP 1 (510) of STA 1 (520) in order to more actively protect the communication period of STA 1 (520). AP 1 (510) may transmit a downlink data frame (620) to STA 1 (520) at a communication-available time of STA 1 (520). STA 1 (520) may respond to the downlink data frame (620) of AP 1 (510) with a response frame (621). As another example, AP 1 (510) may first transmit an ICF before transmitting a downlink data frame to STA 1 (520) at a communication-capable time of STA 1 (520).

[0133] FIG. 10 is a diagram illustrating a method for indicating an available link in a wireless LAN to which the present disclosure applies. Referring to FIG. 10, STA 1 (520) may receive the ICF (622) of AP 1 (510), but may not be able to transmit a frame. Accordingly, STA 1 (520) may not be able to transmit an RCF in response to the ICF (622) of AP 1 (510). If AP 1 (510) does not detect frame reception until after the priority interframe space (PIFS) or the PIFS time, AP 1 (510) may consider the initial frame exchange of TXOP to have failed. Here, STA X (530) and STA Y (540) may prematurely terminate the NAV set by the initial control frame (622) when the 'NAVTimeout' time has elapsed from the time of completion of reception of the initial control frame (622) (more specifically, when the PHY-RXSTART.indication primitive is not generated because the preamble of the PPDU is not detected within the NAVTimeout time), and 'NAVTimeout' may be as shown in the following mathematical expression 1.

[0134] [Mathematical Formula 1]

[0135] NAVTimeout = (2 Х aSIFSTime) + (CTS_Time) + aRxPHYStartDelay + (2 Х aSlotTime)

[0136]

[0137] In mathematical expression 1, 'aSIFSTime' is the time corresponding to SIFS (short interframe space), 'CTS_Time' is the maximum length of the CTS (clear to send) frame, 'aRxPHYStartDelay' is the physical layer reception delay time, and 'aSlotTime' may be the wireless LAN single slot time. Here, 'CTS_Time' may be replaced with the maximum length of the RCF frame or an approximate value of the maximum length, but may not be limited to a specific form.

[0138] As another example, if the initial control frame is a BSRP trigger frame, Equation 1 can be transformed into Equation 2 below.

[0139] [Equation 2]

[0140] NAVTimeout = (2 Х aSIFSTime) + T_PREAMBLE + T_SIGNAL + UL_Length + aRxPHYStartDelay + (2 Х aSlotTime)

[0141]

[0142] In this case, 'T_PREAMBLE' is the length of the PPDU preamble of the RCF, 'T_SIGNAL' is the length of the PPDU SIGNAL field of the RCF, 'UL_Length' is the UL Length length indicated by the initial control frame, and 'aRxPHYStartDelay' is the delay time it takes for the PHY to generate the PHY-RXSTART.indication primitive. aSlotTime can be, but is not limited to, 9us.

[0143] For example, STA X (530) and STA Y (540) may prematurely terminate the NAV set by the initial control frame (622) if the 'NAVTimeout' time of Equation 2 has elapsed after receiving the BSRP trigger frame with the initial control frame (622) (more specifically, if the PHY-RXSTART.indication primitive is not generated because the preamble of the PPDU is not detected within the NAVTimeout time), as described above.

[0144] If AP 1 (510) determines that TXOP has failed, it can lower the MCS (modulation and coding) index for the next frame transmitted to STA 1 (520). For example, a higher MCS index may result in a faster data transmission speed, but the data transmission may not be robust. On the other hand, a lower MCS index may result in a slower data transmission speed, but the data transmission may be more robust. In other words, data transmission stability may be higher. Here, AP 1 (510) may want to transmit data more robustly because the data transmitted to STA 1 (520) has failed, and thus may lower the MCS index. In addition, AP 1 (510) may increase the channel access parameter (EDCA parameter) because the frame transmission has failed. For example, the contention window (CW)[AC] per AC (access categories) can increase by M times (e.g., 2 times), and the QoS STA retry count (QSRC)[AC] per AC can increase by N times (e.g., 1). However, this is just one example and is not limited thereto.

[0145] The above-described operation may increase the channel access parameter of AP 1 (510). Accordingly, the channel access delay of AP 1 (510) may increase, and the data transmission speed between AP 1 (510) and STA 1 (520) may decrease, resulting in a deterioration in wireless LAN communication performance. However, since STA 1 (520) was able to receive the ICF (622) of AP 1 (510), the unnecessary deterioration in wireless LAN communication performance due to the above-described operation may be resolved. For example, STA 1 (520) may perform a channel access operation from a point in time when wireless LAN communication is possible, and if the channel access operation is successful, transmit a lagged RCF (623) to AP 1 (510). The lagged RCF (623) may indicate to AP 1 (510) that STA 1 (520) is capable of wireless LAN communication. When AP 1 (510) receives the RCF (623) of STA 1 (520), AP 1 (510) can return the increased channel access parameter to the initial value or the value before the increase. In addition, AP 1 (510) can increase the MCS index transmitted to STA 1 (520) to the value before the decrease. Accordingly, the channel access delay of AP 1 (510) can be minimized, and the reduction in transmission speed between AP 1 (510) and STA 1 (520) can also be minimized. In other words, the wireless LAN communication performance may not be degraded. AP 1 (510) can transmit a response frame (624) to the RCF (623) of STA 1 (520). As another example, instead of transmitting a response frame to STA 1 (520), AP 1 (510) may transmit a downlink frame to STA 1 (520) or a trigger frame requesting uplink resources of STA 1 (520). As another example, STA 1 (520) may not have been able to receive the ICF (622) of AP 1 (510). Regardless of whether AP 1 (510) transmits the ICF (622), STA 1 (520) experiences a communication failure period that it cannot instruct to AP 1 (510) (e.g. In the case where a situation occurs where a communication unavailable section instruction through the RCF frame, etc. and a pre-scheduled communication unavailable section instruction are impossible, STA 1 (520) may perform a channel access operation after the end of the communication unavailable section to attempt frame transmission to AP 1 (510). The delayed RCF (623) may indicate to AP 1 (510) that STA 1 (520) is capable of wireless LAN communication. In addition, AP 1 (510) may increase the MCS index transmitted to STA 1 (520) to a value prior to decreasing it. Accordingly, the channel access delay of AP 1 (510) may be minimized, and the reduction in transmission speed between AP 1 (510) and STA 1 (520) may also be minimized.

[0146] The above delayed RCF (623) frame may be transmitted using the MCS previously used by STA 1 (510). When AP 1 (510) can receive the delayed RCF (623) from STA 1 (520) and confirm the MCS of the delayed RCF (623), AP 1 (510) may decrease the MCS index transmitted to STA 1 (520) to a previous value or increase the MCS of the delayed RCF (623) transmitted by STA 1 (520). The format of the delayed RCF (623) may follow the format of a data frame such as a QoS Null frame or a QoS Data frame, rather than a control frame such as a Multi-STA BlockAck frame or a BlockAck frame.

[0147] For example, referring to FIGS. 5 to 10 described above, STA 1 (520) can use the machine learning unit and machine learning algorithm illustrated in FIGS. 1 to 4 to determine a communication unavailable section. As a specific example, STA 1 (520) can input traffic of communication using wireless LAN direct communication or a wireless communication technology other than wireless LAN communication technology to the machine learning unit. The machine learning unit can analyze the traffic pattern of STA 1 (520). Accordingly, the machine learning unit can predict in advance when STA 1 (520) will be unavailable for communication, and the communication unavailable section of STA 1 (520) included in the RCF can include the start time and the end time of the communication unavailable section predicted by the machine learning unit.

[0148] As another example, an AP multi-link device (MLD) (e.g., AP MLD 1) and a STA MLD (non-AP MLD) (e.g., STA MLD 1) may operate in a wireless LAN network. The AP MLD and the STA MLD may support multi-link operation and communicate on multiple links. Each link of the multi-link may be a plurality of basic service sets (BSSs) configured on different frequencies or channels. Alternatively, each link of the multi-link may be configured within a subchannel within a specific bandwidth. For example, a link may be configured for a single 20MHz subchannel within a 320MHz channel or a set of 20MHz subchannels. As another example, a subchannel may be a unit smaller than a 20MHz channel unit (e.g., a tone unit). Here, a tone may be a unit for indicating each OFDMA (orthogonal frequency division multiple access) subcarrier. In addition, OFDMA subcarriers, tones, can be grouped together to form a resource unit (RU) unit that can be used in a channel. That is, a subchannel may be a RU unit smaller than a 20MHz channel unit, and is not limited to a specific form. Multiple APs can be affiliated with under the AP MLD. Similarly, multiple STAs (non-AP STAs) can be affiliated with under the STA MLD. The associated APs and STAs can operate on each link of the multi-link. In the following, an AP operating on the first link with AP MLD 1 may be AP 1-1, and an AP operating on the second link with AP MLD 1 may be AP 1-2. In addition, an STA operating on the first link with STA MLD 1 may be STA 1-1, and an STA operating on the second link may be STA 1-2.For example, in the present disclosure, the operation of the MLD can be interpreted as the operation of the lower STA and AP, and conversely, the operation of the STA and AP can be interpreted as the operation of the upper MLD. AP MLD 1 and STA MLD 1 can be connected (or associated) to each other and communicate, and the connection between the MLDs can be referred to as a multi-link setup.

[0149] In a wireless LAN network, multiple STAs (non-AP STAs) can operate. For example, STA X and STA Y as multiple STAs can operate in the wireless LAN network. Here, the multiple STAs can be connected to (or associated with) AP 1 and perform communication. For example, X and Y are natural numbers and can be different values. That is, STA X and STA Y can be different STAs. For example, STAs under STA MLD 1 (STA 1-1 and STA 1-2) and STA Y are UHR (ultra high reliability) STAs. That is, STA MLD 1 and STA Y can be terminals supporting UHR and IEEE 802.11bn or a later developed IEEE 802.11 communication protocol. On the other hand, STA X can be a legacy terminal. That is, STA X may be a terminal that supports an IEEE 802.11 communication protocol (e.g., IEEE 802.11ac, IEEE 802.11ax, IEEE 802.11be) developed prior to the UHR and IEEE 802.11bn protocols. Therefore, STA X may not support the UHR and IEEE 802.11bn functions, and may not recognize the frame format and functions newly added in IEEE 802.11bn.

[0150] In this disclosure, IEEE 802.11bn may be referred to as UHR, and IEEE 802.11bn functions may be referred to as UHR functions. Conversely, UHR may be interpreted as IEEE 802.11bn. In addition, other similar designations should be interpreted similarly to the above-described designation method. For example, the UHR frame format should be understood as the IEEE 802.11bn frame format, and the IEEE 802.11bn frame format may also be understood as the UHR frame format. For convenience of explanation, the following description will be based on the UHR function and UHR frame format.

[0151] For example, STA 1-1 may receive an ICF before receiving a downlink data frame from AP 1-1 by negotiating with AP 1-1 for the DUO operation disclosed in FIG. 5. Specifically, STA 1-1 may be associated with STA MLD 1, and AP 1-1 may be associated with AP MLD 1. The negotiation for the DUO operation performed by STA 1-1 and AP 1-1 may be a negotiation between STA MLD 1 to which STA 1-1 is associated and AP MLD 1 to which AP 1-1 is associated. That is, STA 1-1 and AP 1-1 may perform DUO operation negotiation and DUO operation on behalf of their respective associated MLDs. In the above-described case, STA 1-1 and STA 1-2 of STA MLD 1 can receive an initial control frame before receiving a downlink data frame from AP 1-1 and AP 1-2 of AP MLD 1.

[0152] Here, a situation in which STA 1-1 of STA MLD 1 cannot communicate can be considered. STA 1-1 of STA MLD 1 may have a basic NAV (network allocation vector) set by another wireless LAN terminal. Communication by another wireless LAN terminal may be any one of communication by an AP other than the aforementioned AP 1, communication by STAs connected to an AP other than AP 1, and communication by an overlapping BSS (basic service set) (OBSS), but may not be limited thereto. Alternatively, STA 1-1 of STA MLD 1 may not be able to communicate due to coexistence within the device. For example, STA 1-1 of STA MLD 1 may transmit or receive data using a wireless communication technology other than a wireless LAN. In the above-described case, wireless LAN transmission and reception of STA 1-1 of STA MLD 1 may be limited, and STA 1-1 of STA MLD 1 may be able to transmit only a short control frame.

[0153] AP 1-1 of AP MLD 1 may want to transmit a downlink data frame to STA 1-1 of STA MLD 1. AP 1-1 of AP MLD 1 may perform a channel access operation to transmit data to STA 1-1 of STA MLD 1. The channel access operation may be an enhanced distributed channel access (EDCA) backoff operation. AP 1-1 of AP MLD 1 may succeed in the channel access operation. Success in the channel access operation may mean that EDCAF (EDCA function) initiates transmission at a slot boundary of a slot in which an EDCA backoff counter reaches 0. When EDCAF initiates transmission, AP 1-1 of AP MLD 1 may be granted a transmit opportunity (TXOP). That is, AP 1-1 of AP MLD 1 may obtain a TXOP, but is not limited to a specific term. TXOP may be a time period in which a wireless LAN terminal can transmit multiple frames. AP 1-1 of AP MLD 1 may transmit an ICF to STA 1-1 of STA MLD 1 as the first frame of the TXOP. The ICF may be a frame in a specific format, such as a trigger frame (e.g., MU (multi-user)-RTS (request to send) trigger frame, BSRP (buffer status report poll) trigger frame) or an RTS frame. However, the ICF may not be limited to a specific format.

[0154] For example, STA 1-1 of STA MLD 1 may be unable to communicate due to the above-described basic NAV setting or coexistence within the device. Therefore, STA 1-1 of STA MLD 1 may transmit a response control frame (RCF) as a response frame to the ICF of AP 1-1 of AP MLD 1, and the RCF may include an indicator indicating that STA 1-1 of STA MLD 1 is unable to communicate. In addition, the RCF may include an indicator indicating a link on which STA MLD 1 can communicate. For example, the RCF may include an indicator indicating a second link (e.g., a link bitmap indicating bits in a position corresponding to a link ID (identifier), link ID) to indicate that STA MLD 1 is capable of communicating on the second link.

[0155] As another example, the RCF may include an indicator indicating the first link to indicate that STA MLD 1 is unable to communicate on the first link. Furthermore, the RCF may include an indicator indicating a link-specific communication unavailable period of STA MLD 1. As a specific example, the RCF may include at least one of an indicator indicating a link-specific communication unavailable period in the first link and an indicator indicating a link-specific communication unavailable period in the second link. The indicator indicating a link that is capable of communication (or an indicator indicating a link that is unable to communicate) may indicate whether communication is possible (or unavailable) for each subchannel when each link of the multi-link is configured for each subchannel. The indicator indicating a link-specific communication unavailable period may indicate a link-specific communication unavailable period for each subchannel when each link of the multi-link is configured for each subchannel. A link that is unable to communicate or a subchannel that is unable to communicate may be referred to as an inactive link or an inactive subchannel. An inactive link or an inactive subchannel may be indicated as active or inactive using an indicator in the form of a bitmap. For example, a directive can indicate a disabled link or subchannel by setting the bit corresponding to the position to 1, and can indicate an activated link or subchannel by setting the bit corresponding to the position to 0. As a specific example, when activating all links or all subchannels, it can be indicated by setting all bits in the inactive bitmap to 0.

[0156] For example, the above-described communication-capable link indicator (or communication-uncapable link indicator) or the link-specific communication-uncapable interval indicator may be included in a frame that includes an indicator indicating that STA 1 uses the DUO transmitted to AP 1 in the above-described DUO negotiation, rather than an RCF frame, and may not be limited to a specific form. The above-described indicators may be included in the RCF in various forms, such as a subfield, a field, an information element, an element, an indication bit, or a bit. At least one piece of information among the above-described indicators may be included in the RCF frame. The indicator indicating the communication-uncapable interval may indicate at least one of the start time of the communication-uncapable interval and the end time of the communication-uncapable interval. Here, the end time of the communication-uncapable interval may be a time when communication is possible.

[0157] Also, for example, a link may be a channel, a subchannel, or a bandwidth. That is, a communicable link indicator may be a communicable channel indicator or a communicable subchannel indicator, and replacing a link with a channel or a subchannel as described above and below may be equally applicable. However, for convenience of explanation, the following description is based on a link, but the matters described below may equally apply to channels, subchannels, or bandwidths. More specifically, an MLD as a wireless LAN terminal may operate on a specific channel, a specific subchannel, or a specific bandwidth allocated within multiple links. That is, indicating a communicable link may refer to the possibility of communication on a specific channel, a specific subchannel, or a specific bandwidth of a specific link on which the MLD can operate. Considering the above, the link described below may equally apply to channels, subchannels, or bandwidths. In addition, the matters described above may equally apply to a non-MLD wireless LAN terminal that uses multiple channels, multiple subchannels, or multiple bandwidths, and may not be limited to a specific form. However, for the convenience of explanation, the following description is based on links to MLD.

[0158] When STA MLD 1 includes a bitmap indicator including inactive subchannel information in an RCF frame, AP MLD 1 may transmit a response frame thereto. STA MLD 1 may not transmit or receive data with AP MLD 1 through the inactive subchannel from the time point of receiving the response frame from AP MLD 1. The RCF frame may further include time interval information as information from the time point of application of the inactive subchannel to the time point of application end. STA MLD 1 may not transmit or receive data through the inactive subchannel during the time point corresponding to the time interval information after receiving the response frame from AP MLD 1.

[0159] For example, the operations illustrated in FIGS. 11 to 14 below may be based on the aforementioned situations. Furthermore, the operations illustrated in FIGS. 11 to 14 below may be performed individually or as a combination of specific operations based on the aforementioned situations, and may not be limited to a specific form.

[0160] FIG. 11 is a diagram illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure. Referring to FIG. 11, STA 1-1 (520-1) of STA MLD 1 can transmit RCF (626) in response to ICF (625) of AP 1-1 (510-1) of AP MLD 1 on a first link. Here, the RCF (626) transmitted by STA 1-1 (520-1) of STA MLD 1 can indicate that communication is possible on a second link. When AP 1-1 (510-1) of AP MLD 1 receives RCF (626), it can transmit a CF-End frame to early terminate TXOP. Alternatively, AP 1-1 (510-1) of AP MLD 1 may transmit frames to STAs other than STA 1-1 (520-1) of STA MLD 1 (e.g. STA X, STA Y) in the remaining TXOP.

[0161] AP MLD 1 can recognize that STA 1-2 (520-2) of STA MLD 1 is communicable on the second link based on RCF (626) of STA MLD 1. Here, AP 1-2 (510-2) of AP MLD 1, where AP MLD 1 operates on the second link, can perform a channel access operation to transmit a downlink frame (627) to STA 1-2 (520-2) of STA MLD 1. If AP 1-2 (510-2) of AP MLD 1 succeeds in the channel access operation, AP 1-2 (510-2) of AP MLD 1 can transmit a downlink frame (627) to STA 1-2 (520-2) of STA MLD 1. STA 1-2 (520-2) of STA MLD 1 can receive a downlink frame (627) of AP 1-2 (510-2) of AP MLD 1, and transmit a response frame (628) to AP 1-2 (510-2) of AP MLD 1. That is, when AP MLD 1 receives a frame (e.g. RCF frame) indicating (e.g. inactivity bitmap) that the first link of STA MLD 1 is incapable of communication (disabled) and the second link is capable of communication (enabled), AP MLD 1 does not transmit a frame to STA 1-1 (520-1) of STA MLD 1 operating on the first link, and AP 1-2 (510-2) of AP MLD 1 can transmit a frame to STA 1-2 (520-2) of STA MLD 1. That is, AP MLD 1 can perform communication using only some links to transmit frames to STA MLD 1. Here, links may be channels, subchannels, or other bands. For example, the AP may perform communication using some channels, subchannels, or bands to transmit frames to STAs. However, for convenience of explanation, the present disclosure will be described based on links.

[0162] When STA MLD 1 wants to communicate with AP MLD 1 again using the first link, STA MLD 1 can transmit a frame (e.g., RCF, UHR OMN frame) to AP MLD 1 indicating that the first link is available. For example, whether a specific link (or channel, subchannel) is available (or unavailable) can be indicated in the form of an inactive bitmap, and an inactive link (or channel, subchannel) among all links (or channels, subchannels) can be indicated by being set to 1. For example, an operation of communicating using some links (or channels, subchannels) can be a channel puncturing operation. As a specific example, when the first link among the first and second links is not used (disabled) and a frame is transmitted using the second link, a punctured frame may be transmitted on the first link. As another example, a case where the first to third links exist can be considered. In the above-described case, when the first link and the third link are used for frame transmission and the second link is not used for frame transmission, a punctured frame may be transmitted on the second link. The punctured frame may not be transmitted on the corresponding link (or channel, subchannel). In the case of a subchannel, only a channel designated as an inactive channel in the entire band may be punctured and other channels may be used to transmit data frames. Here, the STA (or STA MLD) that transmitted the frame indicating that the first link is available may be an STA (or STA MLD) operating in a restricted operation mode. The STA operating in the restricted operation mode may be an STA in which a specific value for the restricted operation mode included in the above-described frame is set to a first value.Alternatively, an STA (or STA MLD) that transmits a frame indicating that the first link is available (e.g., a frame indicating that the first link (or subchannel) is active, the second link (or subchannel) is inactive, or at least one link or subchannel is inactive) without the separate value may be an STA (or STA MLD) operating under a restricted operation mode.

[0163] For example, the perforation of a link may indicate the perforation of a specific subchannel. Specifically, an operation in which the first link is not used among the first link and the second link and a frame is transmitted using the second link may be an operation in which the first subchannel is not used and the second subchannel is used to transmit the frame. That is, a perforated frame may be transmitted on the first subchannel. If both the first link (or the first subchannel) and the second link (or the second subchannel) are used to transmit the frame, no link (or subchannel) may be perforated. Meanwhile, the STA MLD 1 may retransmit a frame indicating that the first link (or channel, subchannel) transmitted is available (hereinafter, “link (or channel, subchannel) availability indication”). This may be transmitted to indicate that the second link (or channel, subchannel) is available again. AP MLD 1 receives a link availability indication frame indicating that both the first link (or channel, subchannel) and the second link (or channel, subchannel) of STA MLD 1 are available, and frame transmission operation can be performed on all links (or subchannels) without using the channel puncturing operation as described above. The link (or channel, subchannel) availability indication frame can be a frame including an indicator that can indicate that the specific link described above is available and that it is not available in the form of an inactive bitmap. In order to indicate that all links (or channels, subchannels) are available, all bitmaps can be set to 0 to indicate that no link (or channel, subchannel) is inactive. AP MLD 1 can transmit a response frame to the link (or channel, subchannel) availability indication frame, and STA MLD 1 can transmit and receive frames with AP 1 using all links (or channels, subchannels) after receiving the response frame.The above link (or channel, subchannel) availability indication frame may further include time interval information indicating when activation of an inactive subchannel is applied and for how long. After receiving a response frame from AP MLD 1, STA MLD 1 transmits and receives data using all links (or channels, subchannels) during the time interval corresponding to the above time interval information.

[0164] As another example, information about link deactivation may be indicated through a Disabled Subchannel Bitmap subfield in a frame. The Disabled Subchannel Bitmap subfield may indicate activation or deactivation of one or more subchannels (e.g., 20MHz subchannels) within a specific bandwidth (e.g., BSS bandwidth). Here, the STA (or STA MLD) that transmitted the above-described frame may be an STA (or STA MLD) operating in a restricted operation mode. The STA operating in a restricted operation mode may be an STA in which a specific value for the restricted operation mode of the above-described frame is set to a first value, and whether it is in a restricted operation mode may be determined by the STA level or the STA MLD level. Alternatively, even without the separate value, the STA (or STA MLD) that transmitted the above-described frame (a frame indicating deactivation of a subchannel) may be an STA (or STA MLD) operating in a restricted operation mode. For example, as described above, the STA MLD may operate in a restricted operation mode so that only a specific link or a specific subchannel is used, but may not be limited thereto. That is, an STA operating in a restricted operation mode may not use one or more inactive subchannels indicated through the inactive subchannel bitmap subfield. Specifically, the inactive subchannel bitmap may include bits corresponding to each subchannel, and whether or not the subchannel is inactive may be indicated by the corresponding value. A subchannel indicated as inactive through a bit of the inactive subchannel bitmap may be punctured, and a subchannel indicated as active may not be punctured, as described above.

[0165] FIG. 12 is a diagram illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure. Referring to FIG. 12, STA 1-1 (520-1) of STA MLD 1 may transmit an RCF (630) in response to an ICF (629) of AP 1-1 (510-1) of AP MLD 1 in the first link. Here, the RCF (630) transmitted by STA 1-1 (520-1) of STA MLD 1 may indicate the availability time of the first link and the second link. That is, the RCF (630) may include an indicator of a communication unavailable period of the first link and the second link. For example, a case where the communication available time of the first link is later than the communication available time of the second link may be considered. AP 1-1 (510-1) of AP MLD 1 may transmit a CF-End frame to early terminate the TXOP. Alternatively, AP 1-1 (510-1) of AP MLD 1 may transmit frames to STAs other than STA 1-1 (520-1) of STA MLD 1. Alternatively, other STAs may perform an operation of releasing NAV upon receiving RCF (630) as in the operations of FIGS. 7 and 8.

[0166] For example, AP MLD 1 can perform a channel access operation on a second link with an earlier communication possible time. AP 1-2 (510-2) of AP MLD 1 can perform a channel access operation, and the EDCA backoff counter of AP 1-2 (510-2) of AP MLD 1 can reach 0. For example, if the time at which the EDCA backoff counter of AP 1-2 (510-2) of AP MLD 1 reaches 0 is earlier than the communication possible time of the second link, AP 1-2 (510-2) of AP MLD 1 can maintain the EDCA backoff counter as 0 without transmitting a frame. After that, AP 1-2 (510-2) of AP MLD 1 can transmit a downlink frame (631) to STA 1-2 (520-2) of STA MLD 1 at the communication possible time of the second link. On the other hand, if the time at which the EDCA backoff counter of AP 1-2 (510-2) of AP MLD 1 reaches 0 is the same as or later than the time at which the second link can communicate, AP 1-2 (510-2) of AP MLD 1 can transmit a downlink frame (631) to STA 1-2 (520-2) of STA MLD 1 at the slot boundary at which the backoff counter reaches 0. STA 1-2 (520-2) of STA MLD 1 can receive the downlink frame (631) of AP 1-2 (510-2) of AP MLD 1 and transmit a response frame (632) to AP 1-2 (510-2) of AP MLD 1.

[0167] As another example, the communication possible time of the first link may be earlier than that of the second link. For example, if the communication possible time of the first link is earlier than the TXOP of AP 1-1 (510-1) of AP MLD 1 and the end time of the TXOP of AP 1-1 (510-1) of AP MLD 1 from the communication possible time of the first link is sufficient to transmit a frame to STA 1-1 (520-1) of STA MLD 1, then AP 1-1 (510-1) of AP MLD 1 may transmit a downlink frame to STA 1-1 (520-1) of STA MLD 1. On the other hand, if the communication possible time of the first link is not earlier than the TXOP of AP 1-1 (510-1) of AP MLD 1 or if the end time of the TXOP of AP 1-1 (510-1) is not sufficient to transmit a frame to STA 1-1 (520-1) of STA MLD 1, AP 1-1 (510-1) of AP MLD 1 may perform a channel access operation after the TXOP ends to transmit a frame to STA 1-1 (520-1) of STA MLD 1.

[0168] FIG. 13 is a diagram illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure.

[0169] Referring to FIG. 13, if at least one of the links (or channels, subchannels) of STA MLD 1 is incapable of communication, i.e., is deactivated, STA MLD 1 may transmit an unsolicited RCF (633) without receiving an ICF from AP MLD 1. For example, STA MLD 1 may transmit the RCF (633) on the first link. The RCF (633) transmitted by STA MLD 1 on the first link may include a communication-unavailable section of the first link and a communication-unavailable section of the second link. AP MLD 1 may transmit a response frame to the RCF, and if STA MLD 1 receives the response frame, it may communicate with AP MLD 1 without using the deactivated link (or channel, subchannel) indicated in the RCF. If the communication-unavailable section is included, it may communicate with AP MLD 1 only in the corresponding section without using the deactivated link (or channel, subchannel).

[0170] For example, a case may be considered where the communication possible time of the first link is later than the communication possible time of the second link. Here, if there is a frame that AP MLD 1 needs to transmit to STA MLD 1, AP MLD 1 may perform a channel access operation on the second link having an earlier communication possible time based on RCF (633). AP 1-2 (510-2) of AP MLD 1 may perform a channel access operation, and the EDCA backoff counter of AP 1-2 (510-2) of AP MLD 1 may reach 0. If the time at which the EDCA backoff counter of AP 1-2 (510-2) of AP MLD 1 reaches 0 is earlier than the communication possible time of the second link, AP 1-2 (510-2) of AP MLD 1 may not transmit a frame and maintain the EDCA backoff counter as 0. After that, AP 1-2 (510-2) of AP MLD 1 can transmit a downlink frame (634) to STA 1-2 (520-2) of STA MLD 1 at the time when communication is possible on the second link.

[0171] On the other hand, if the time at which the EDCA backoff counter of AP 1-2 (510-2) of AP MLD 1 reaches 0 is the same as or later than the time at which the second link can communicate, AP 1-2 (510-2) of AP MLD 1 can transmit a downlink frame (634) to STA 1-2 (520-2) of STA MLD 1 at the slot boundary at which the backoff counter reaches 0. STA 1-2 (520-2) of STA MLD 1 can receive the downlink frame (634) of AP 1-2 (510-2) of AP MLD 1 and transmit a response frame (635) to AP 1-2 (510-2) of AP MLD 1.

[0172] When AP MLD 1 receives a frame (e.g., RCF frame) indicating that the first link and the second link of STA MLD 1 are available for communication after a certain period of time, and when the second link is available for communication earlier, AP MLD 1 can transmit a frame to STA MLD 1 at the time when the second link is available for communication. That is, AP MLD 1 can perform communication using only some links (or channels, subchannels) to transmit frames to STA MLD 1. AP MLD 1 can transmit frames to STA MLD 1 using both the first link and the second link at the time when both the first link and the second link are available. That is, AP MLD 1 can perform communication using the entire link (or channel, subchannel) to transmit frames to STA MLD 1.

[0173] Meanwhile, an operation of communicating using some links (or channels, subchannels) may be a channel puncturing operation. As a specific example, if the first link is not used among the first and second links and the second link is used to transmit a frame, a punctured frame may be transmitted on the first link. As another example, a case in which the first to third links exist may be considered. In the above-described case, if the first and third links are used for frame transmission and the second link is not used for frame transmission, a punctured frame may be transmitted on the second link.

[0174] For example, the perforation of a link may indicate the perforation of a specific subchannel. Specifically, an operation in which the first link is not used and a frame is transmitted using the second link among the first and second links may be an operation in which the first subchannel is not used and the frame is transmitted using the second subchannel. In other words, a perforated frame may be transmitted on the first subchannel. If both the first link (or the first subchannel) and the second link (or the second subchannel) are used and a frame is transmitted, no link (or subchannel) may be perforated.

[0175] FIG. 14 is a diagram illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure.

[0176] Referring to FIG. 14, STA 1-1 (520-1) of STA MLD 1 may receive ICF (636) of AP 1-1 (510-1) of AP MLD 1, but may not transmit a frame. That is, STA 1-1 (520-1) of STA MLD 1 may not transmit RCF in response to ICF (636) of AP 1-1 (510-1) of AP MLD 1. If frame reception is not detected until PIFS (priority interframe space) or after PIFS time, AP 1-1 (510-1) of AP MLD 1 may consider that initial frame exchange of TXOP has failed.

[0177] For example, STA X and STA Y may prematurely terminate the NAV set by the initial control frame when the NAVTimeout time has elapsed from the time of completion of reception of ICF (636) (more specifically, when the PHY-RXSTART.indication primitive is not generated because the preamble of the PPDU is not detected within the NAVTimeout time), which may be as shown in the mathematical expression 1 described above.

[0178] If AP 1-1 (510-1) of AP MLD 1 determines that the TXOP has failed, it can lower the MCS (modulation and coding) index for the next frame transmitted to STA 1-1 (520-1) of STA MLD 1. For example, a higher MCS index may result in faster data transmission, but may not result in robust data transmission. On the other hand, a lower MCS index may result in slower data transmission, but may result in more robust data transmission. In other words, data transmission stability may be higher.

[0179] Here, AP 1-1 (510-1) of AP MLD 1 will want to transmit data more robustly because the data transmitted to STA 1-1 (520-1) of STA MLD 1 failed. In addition, AP 1-1 (510-1) of AP MLD 1 may increase the channel access parameters (EDCA parameters) because the frame transmission failed. For example, the contention window (CW) [AC] per AC (access category) may increase by M times (e.g., 2 times), and the QSRC (QoS STA retry count) [AC] per AC may increase by N times (e.g., 1). However, this is just one example and is not limited thereto.

[0180] The above-described operation may increase the channel access parameter of AP 1-1 (510-1) of AP MLD 1. Accordingly, the channel access delay of AP 1-1 (510-1) of AP MLD 1 may increase, and the data transmission speed between AP 1-1 (510-1) of AP MLD 1 and STA 1-1 (520-1) of STA MLD 1 may decrease, resulting in a deterioration of wireless LAN communication performance. However, since STA 1-1 (520-1) of STA MLD 1 was able to receive the ICF (636) of AP 1-1 (510-1) of AP MLD 1, the unnecessary deterioration of wireless LAN communication performance caused by the above-described operation may be resolved.

[0181] STA MLD 1 may be capable of communicating on the second link. STA 1-2 (520-2) of STA MLD 1 may perform a channel access operation, and if the channel access operation is successful, may transmit an RCF (637) to AP 1-2 (510-2) of AP MLD 1 of the second link. In the above case, the RCF (637) may indicate that STA 1-2 (520-2) of STA MLD 1 was able to receive the RCF (637). If AP 1-2 (510-2) of AP MLD 1 receives the RCF (637) of STA 1-2 (520-2) of STA MLD 1, AP 1-1 (510-1) of AP MLD 1 may return the increased channel access parameter to the initial value or the value before the increase. Likewise, AP 1-1 (510-1) of AP MLD 1 can increase the MCS index transmitted to STA 1-1 (520-1) of STA MLD 1 to the value before decreasing the MCS index. Therefore, the channel access delay of AP 1-1 (510-1) of AP MLD 1 can be minimized, and the reduction in transmission speed between AP 1-1 (510-1) of AP MLD 1 and STA 1-1 (520-1) of STA MLD 1 can be minimized. Through this, wireless LAN communication performance may not be reduced.

[0182] AP 1-2 (510-2) of AP MLD 1 may transmit a response frame (638) to the RCF (637) of STA 1-2 (520-2) of STA MLD 1. Alternatively, AP 1-2 (510-2) of AP MLD 1 may transmit a downlink frame to STA 1-2 (520-2) of STA MLD 1 instead of transmitting a response frame to STA 1-2 (520-2) of STA MLD 1, or may transmit a trigger frame requesting uplink resources of STA 1-2 (520-2) of STA MLD 1.

[0183] As another example, STA 1-2 (520-2) of STA MLD 1 may not have been able to receive the ICF (636) of AP 1-1 (510-1) of AP MLD 1. Regardless of whether AP 1-1 (510-1) of AP MLD 1 transmits the ICF (636), if a communication unavailable period occurs that cannot be indicated to the APs to which lower STAs are connected (e.g., a situation occurs where indication of a communication unavailable period through the RCF frame or a previously scheduled communication unavailable period is impossible), STA MLD 1 may transmit a delayed RCF (637) indicating a communication unavailable period of STA MLD 1 (specifically, a communication unavailable period of STAs below STA MLD 1) to AP MLD 1 using an available STA. The delayed RCF (637) can indicate to AP 1 (510-1) of AP MLD 1 that STA 1-1 (520-1) of STA MLD 1 is capable of wireless LAN communication. In addition, the delayed RCF (637) can be transmitted by STA 1-2 (520-2) of STA MLD 1 that is capable of communication and operates on the second link. Alternatively, the delayed RCF (637) can be transmitted by a lower STA of STA MLD 1 that is capable of communication earlier. AP MLD 1 can receive the delayed RCF (637) from STA MLD 1, and AP 1 (510-1) under AP MLD 1 can increase the MCS index transmitted to STA 1-1 (520-1) of STA MLD 1 to a value before decreasing it. Accordingly, the channel access delay of AP 1 (510-1) of AP MLD 1 can be minimized, and the reduction in transmission speed between AP 1 (510-1) of AP MLD 1 and STA 1 (520-1) of STA MLD 1 can also be minimized.For example, the format of the delayed RCF (637) may follow the format of a 'QoS Null' frame, a 'QoS Data' frame, or other types of data frames, rather than a control frame such as a 'Multi-STA BlockAck' frame or a 'BlockAck' frame.

[0184] Referring to FIGS. 11 to 14, TTLM (TID (traffic identified) - to - Link Mapping) may be set for AP MLD 1 and STA MLD 1. TTLM may be a setting that maps traffic with a specific TID to be transmitted only on a specific link. For example, TTLM may be set so that AC_BE (best effort) is transmitted only on the first link, and the remaining ACs can be transmitted on all links. However, if STA MLD 1 transmits an RCF frame, TTLM may be ignored. As a specific example, if AP MLD 1 receives an RCF frame from STA MLD 1, it may transmit an AC_BE frame to the second link. This may be an operation in which AP MLD 1, which received the RCF frame, temporarily regards TTLM as "TID-to-all link mapping".

[0185] In the embodiments of FIGS. 11 to 14, STA MLD 1 and lower STAs of STA MLD 1 may use the machine learning unit and machine learning algorithm illustrated in FIGS. 1 to 4 to determine a communication unavailable section. For example, STA MLD 1 may input traffic of communication using wireless LAN direct communication or a wireless communication technology other than a wireless LAN communication technology to the machine learning unit. The machine learning unit may analyze the traffic pattern of STA MLD 1. Accordingly, the machine learning unit may predict in advance when communication will be unavailable on each link of STA MLD 1, and the communication unavailable section of STA MLD 1 or lower STAs of STA MLD 1 included in the RCF frame may include the start time and the end time of the communication unavailable section predicted by the machine learning unit.

[0186] In a wireless LAN network, AP 1 and non-AP STAs operating in connection with AP 1 can perform communication. For example, non-AP STAs may also be referred to as STAs. STAs operating in connection with AP 1 may include STA 1. Here, the connection may be an association procedure. In the association procedure, AP 1 and STA 1 may exchange communication parameters and capability parameters with each other, and AP 1 may assign an AID (association identifier) ​​to STA 1. In addition, after AP 1 and STA 1 are associated (or associated), AP 1 and STA 1 may configure various communication sessions, such as BlockAck sessions, with each other. AP 1 and STA 1 may perform communication based on the established communication session. AP 1 may maintain configuration information configured in the association procedure with STAs, the communication session configuration setup procedure, and other procedures, and may communicate with STAs using the maintained information. For example, the operations illustrated in FIGS. 15a to 19 below may be based on the aforementioned situations. Furthermore, the operations illustrated in FIGS. 15a to 19 below may be performed individually or as a combination of specific operations based on the aforementioned situations, and may not be limited to a specific form.

[0187] Figures 15a to 15c are drawings showing a method for resuming communication after indicating a communication failure section.

[0188] AP 1 (710) may transmit an IDC (in-device coexistence) indication frame. The IDC indication frame may be a frame indicating a communication unavailable period of AP 1 (710). The IDC indication frame may include at least one of a start time of the communication unavailable period of AP 1 (710), an end time of the communication unavailable period of AP 1 (710), and a length of the communication unavailable period of AP 1 (710). For example, the IDC indication frame may include a TWT (target wake time) element. The TWT element or quiet element (or quiet channel element) included in the IDC indication frame may indicate a communication unavailable period of AP 1 (710).

[0189] For example, if the IDC indication frame is a management frame, the IDC indication frame may be, but is not limited to, one of a probe response frame, a beacon frame, and an action frame. As another example, the IDC indication frame may be in the form of a trigger frame. If the IDC indication frame is a trigger frame, the IDC indication frame may be, but is not limited to, a MU (multi-user)-RTS (request to send) trigger frame or a BSRP (buffer status report poll) trigger frame.

[0190] The IDC indication frame of AP 1 (710) may be transmitted in a broadcast manner. Transmitting the IDC indication frame in a broadcast manner may mean that the receiver address of the MAC (medium access control) header of the frame is set to a broadcast address and transmitted. In other words, all wireless LAN terminals within the reception range of the IDC indication frame may be expected to receive the frame. As another example, the IDC indication frame of AP 1 (710) may be transmitted in a unicast manner. Transmitting the IDC indication frame in a unicast manner may mean that the receiver address of the MAC (medium access control) header of the frame is set to a unicast address, which is the MAC address of an individual terminal, and transmitted. In other words, the IDC indication frame may be expected to be received only by specific terminals having a unicast address.

[0191] The IDC instruction frame of the AP may additionally indicate the reason for the occurrence of the communication unavailable period of AP 1 (710). When AP 1 (710) indicates the reason for the communication unavailable period, the actions to be performed by STAs (STAs including STA 1 (720)) connected to AP 1 (710) may be indicated differently depending on the reason for the communication unavailable period of AP 1 (710).

[0192] As a specific example, a case where AP 1 (710) temporarily restarts a device can be considered. AP 1 (710) can indicate 'device restart' or 'temporary interruption' in the IDC instruction frame as the reason for the communication unavailability period of AP 1 (710). The reason may be that AP 1 (710) can resume communication soon. Therefore, the inclusion of the above-described reason in the IDC instruction frame may mean that AP 1 (710) maintains the association (or binding, association) state of STAs connected to AP 1 (710). Accordingly, AP 1 (710) and STAs connected to AP 1 (710) can maintain the setting information set in the association procedure, the communication session configuration setting procedure, and other procedures, and can use the maintained information even after communication is resumed.

[0193] As another example, a case may be considered where AP 1 (710) performs peer-to-peer (P2P) communication or performs a power-saving operation. This may be because AP 1 (710) can resume communication soon. Therefore, the inclusion of the above-described reason in the IDC instruction frame may mean that AP 1 (710) maintains the association (or binding, association) state of STAs connected to AP 1 (710). Accordingly, AP 1 (710) and STAs connected to AP 1 (710) can maintain the configuration information set in the association procedure, the communication session configuration setup procedure, and other procedures, and can use the maintained information even after communication is resumed.

[0194] As another example, the IDC instruction frame may include an instruction (a instruction for setting information) that instructs AP 1 (710) to maintain its configuration information for a separate reason. The instruction for setting information may include at least one of the following: communication parameters negotiated during association, capability parameters, BlockAck session information, security session information, and low-power session information. Furthermore, the instruction for setting information may include essential information (e.g., AID) required by communication terminals to communicate.

[0195] For example, referring to FIG. 15A, STAs connected to AP 1 (710) can receive an IDC indication frame (801) of AP 1 (710). The IDC indication frame (801) of AP 1 (710) can include information on a communication unavailable section of AP 1 (710). In addition, the IDC indication frame (801) can indicate a 'temporary interruption' or a 'device restart' as a reason for the communication unavailable section of AP 1 (710). Alternatively, a configuration information indicator can be set and transmitted in the IDC indication frame (801). For example, the configuration information indicator can indicate that configuration information set after connecting to AP 1 (710) is to be maintained. STA 1 (720) (an STA connected to AP 1 (710)) can receive the IDC indication frame (801) of the AP. STA 1 (720) can identify a communication unavailable period of AP 1 (710) based on the IDC indication frame (801) and may not transmit frames to AP 1 (710) during the unavailable period. For example, STA 1 (720) can perform direct communication (peer-to-peer communication) with another terminal during the unavailable period of AP 1 (710). As another example, STA 1 (720) can perform low-power operation during the unavailable period of AP 1 (710), but may not be limited to the embodiment.

[0196] Here, if a 'temporary interruption' or 'device restart' is indicated due to a communication unavailable period of the IDC instruction frame (801) of AP 1 (710) despite the fact that communication is impossible, or if a configuration information indicator is set in the IDC instruction frame (801), STA 1 (720) can maintain the configuration information set after connecting to AP 1 (710). When the communication unavailable period of AP 1 (710) ends, STA 1 (720) can immediately resume communication with AP 1 (710). That is, STA 1 (720) can transmit an uplink frame (802) to AP 1 (710) or receive a downlink frame (803) from AP 1 (710) without re-association (or re-association) based on the maintained configuration information when the communication unavailable period of AP 1 (710) ends.

[0197] As another example, referring to FIG. 15b, even though AP 1 (710) is unable to communicate, if a 'temporary interruption' or 'device restart' is indicated due to a communication unavailable period of the IDC instruction frame (804) of AP 1 (710), or if a configuration information instruction is set, STA 1 (720) can maintain the established session after connecting to AP 1 (710), which may be the same as FIG. 15a. Accordingly, when the communication unavailable period of AP 1 (710) ends, STA 1 (720) can immediately resume communication with AP 1 (710).

[0198] Here, the communication unavailability period of AP 1 (710) may end early. For example, the device restart of AP 1 (710) may end earlier than the end point of the initially indicated communication unavailability period. Therefore, AP 1 (710) may be able to communicate with STAs before the end point of the indicated communication unavailability period. Considering the above, AP 1 (710) may transmit a comeback frame (805) before the end point of the communication unavailability period.

[0199] For example, the return frame (805) may be a frame indicating that AP 1 (710) is capable of communication again. The return frame (805) may be a short control frame (e.g., a CTS frame, an RTS frame, a CF-End frame). As another example, the return frame (805) may be a downlink data frame transmitted to an STA connected to AP 1 (710) (e.g., to STA 1 (720)). As another example, the return frame (805) may be a management frame. The recovery frame (805) may be at least one of a beacon frame, a probe response frame, and an action frame, but may not be limited thereto. When AP 1 (710) transmits the return frame (805), STA 1 (720) may receive the return frame (805). If STA 1 (720) successfully receives the return frame (805), STA 1 (720) can recognize that AP 1 (710) is capable of communication and can early terminate the communication unavailable period of AP 1 (710). STA 1 (720) can resume communication with AP 1 (710) because the communication unavailable period of AP 1 (710) has ended. For example, if the communication unavailable period of AP 1 (710) is early terminated, STA 1 (720) can transmit an uplink frame (806) to AP 1 (710) or receive a downlink frame (807) from AP 1 (710) without reassociation (or reassociation) based on the maintained configuration information.

[0200] As another example, referring to FIG. 15c, AP 1 (710) may transmit an IDC indication frame (808) to indicate a communication unavailable period of AP 1 (710). When the communication unavailable period of AP 1 (710) ends, STA 1 (720) may resume communication with AP 1 (710), and the corresponding operations may be the same as FIG. 15a. Here, AP 1 (710) may lose some or all of the session information with STA 1 (720) during the communication unavailable period. Alternatively, STA 1 (720) may lose some or all of the session information with AP 1 (710) during the communication unavailable period. In the above-described case, AP 1 (710) and STA 1 (720) may need to re-establish session information for communication.

[0201] If both AP 1 (710) and STA 1 (720) lose session information, AP 1 (710) may transmit a probe response frame to STA 1 (720). Here, before AP 1 (710) transmits the probe response frame to STA 1 (720), STA 1 (720) may transmit a probe request frame to AP 1 (710). STA 1 (720) may transmit an association request frame to AP 1 (710) based on the probe response frame of AP 1 (710).

[0202] As another example, if STA 1 (720) maintains capability information, operating channel information, and other configuration information for AP 1 (710), STA 1 (720) can immediately transmit an association request (809) frame to AP 1 (710). If AP 1 (710) receives the association request frame (809) of STA 1 (720), AP 1 (710) can generate and transmit an association response (810) frame. Here, the association response frame can include an AID. That is, AP 1 (710) and STA 1 (720) can perform a new connection procedure as an exchange procedure for at least one of a probe response, an association request frame, and an association response frame. Afterwards, AP 1 (710) and STA 1 (720) can re-establish sessions for communication (e.g., security session, BlockAck session). Since AP 1 (710) and STA 1 (720) are aware of the frequency information on which they were previously operating, an additional scanning process may not be necessary before performing the connection procedure. For example, since STA 1 (720) is aware of the operating channel of AP 1 (710), STA 1 (720) can immediately perform the connection procedure with AP 1 (710) without performing a separate channel scan at the end of the communication unavailable period of AP 1 (710). Since additional channel scanning is unnecessary, the delay can be reduced.

[0203] As another example, AP 1 (710) may lose some or all session information with all STAs during a period of communication failure. Here, AP 1 (710) may transmit a probe response frame to all STAs using a broadcast address. The STAs may immediately perform a setup procedure for communication with AP 1 (710), including an association procedure, after the communication failure period.

[0204] For example, consider a case where the configuration information indicator is set to 0 in the IDC instruction frame (808) of AP 1 (710) and transmitted. That is, the configuration information may not be maintained. However, since AP 1 (710) uses the same parameters, STAs may not receive beacons. However, since the configuration information (e.g., AID, etc.) is not maintained, STAs may have to perform a configuration procedure for communication again through an association procedure or other procedure after the communication failure period, and the configuration information indicator being set to 0 in the IDC instruction frame (808) may indicate the above-described matter. STAs may perform a configuration procedure for communication with AP 1 (710), including an association procedure, immediately after the communication failure period.

[0205] As another example, in FIGS. 15A to 15C, the communication unavailable period of AP 1 (710) may be a TWT service period (SP). If the IDC indication frame includes a TWT (target wake time) element, the communication unavailable period of AP 1 (710) may be indicated by a TWT SP indicated by the TWT element. Accordingly, an early termination of the TWT SP may indicate an early termination of the communication unavailable period of AP 1 (710).

[0206] For example, the actual length of the communication unavailability interval of AP 1 (710) may be shorter than the length of the communication unavailability interval initially indicated by AP 1 (710). In order to indicate that the communication unavailability interval of AP 1 (710) is ending early, the TWT SP of AP 1 (710) that is the communication unavailability interval may need to be terminated early. AP 1 (710) may transmit a 'frame terminating the TWT SP' within the communication unavailability interval of AP 1 (710). A frame that terminates a TWT SP may be, but is not limited to, at least one of a QoS data or QoS Null frame with the End of Service Period (EOSP) subfield of the QoS Control field of the MAC header set to 1, a TWT Information Frame containing an indicator indicating the termination of the TWT SP, and a frame that is not a QoS data or QoS Null frame and does not require a response frame but has the More Data bit of the MAC header set to 0.

[0207] When the AP transmits a frame terminating the TWT SP, a TWT SP termination event may occur. That is, when AP 1 (710) needs to initiate (resume) communication, the TWT SP of AP 1 (710) may generate a TWT SP termination event, and the TWT SP of AP 1 (710) may be terminated. That is, the communication unavailable period of AP 1 (710) may be terminated. In the above-described case, STAs connected to AP 1 (710) may resume communication with AP 1 (710).

[0208] Figures 16a and 16b are diagrams showing a method for resuming communication after indicating a communication unavailable section in a wireless LAN.

[0209] Referring to FIG. 16A, STA 1 (720) may transmit an IDC indication frame (811) to AP 1 (710). The IDC indication frame (811) may be a frame indicating that STA 1 (720) cannot communicate with AP 1 (710). The IDC indication frame (811) may include at least one of a start time of a communication impossibility period between STA 1 (720) and AP 1 (710), an end time of the communication impossibility period, and a length of the communication impossibility period. As an example, the IDC indication frame (811) may be a response control frame (RCF) transmitted unsolicited. As another example, the IDC indication frame (811) may be a management frame (e.g., an action frame). AP 1 (710) can receive the IDC instruction frame (811) of STA 1 (720) and check the section in which communication is impossible of STA 1 (720).

[0210] Referring to FIG. 16b, AP 1 (710) may transmit an initial control frame (ICF, 814) to STA 1 (720). The ICF (814) may be a frame expecting a response frame from STA 1 (720). STA 1 (720) may transmit an RCF (815) as a response frame to the ICF (814). Here, the RCF (815) may be the IDC indication frame of FIG. 16a described above. That is, the RCF (815) may indicate a communication unavailable section of STA 1 (720).

[0211] As another example, STA 1 (720) may transmit a frame of a different form than RCF in response to ICF (814) indicating a communication unavailable period of STA 1 (720), and may not be limited to a specific form. AP 1 (710) may receive a response frame to ICF (814) from STA 1 (720) and confirm the communication unavailable period of STA 1 (720).

[0212] Referring to FIGS. 16A and 16B, AP 1 (710) can communicate with STA 1 (720) in a section that is not a communication-impossible section of STA 1 (720) (i.e., an available section). That is, AP 1 (710) can receive an uplink frame (812-1) or transmit a downlink frame (812-2) from STA 1 (720). On the other hand, AP 1 (710) may not transmit or receive frames to STA 1 (720) in a communication-impossible section of STA 1 (720). STA 1 (720) may perform heterogeneous communication (e.g., Bluetooth communication, cellular communication) other than wireless LAN communication in a communication-impossible section indicated by an IDC indication frame, or may communicate directly with another terminal. Therefore, STA 1 (720) may not communicate with AP 1 (710) in the communication impossibility section indicated by the IDC instruction frame.

[0213] Here, the heterogeneous communication or direct communication of STA 1 (720) may end faster than the communication unavailable period indicated by the IDC indication frame of STA 1 (720). Therefore, STA 1 (720) may want to perform communication with AP 1 (710) again and may want to end the communication unavailable period of AP 1 (710). For example, STA 1 (720) may transmit a comeback frame (813-1, 813-2) before the end of the communication unavailable period. The comeback frame (813-1, 813-2) may be a frame that indicates to AP 1 (710) that communication of STA 1 (720) is possible again. The comeback frame (813-1, 813-2) may be a short control frame (e.g., CTS frame, RTS frame, CF-End frame).

[0214] As another example, the return frame (813-1, 813-2) may be an uplink data frame (e.g. QoS data frame) or a QoS Null frame transmitted to the AP (e.g. AP 1 (710)). As another example, the return frame (813-1, 813-2) may be a management frame (e.g. action frame). When STA 1 (720) transmits the return frame (813-1, 813-2), AP 1 (710) can receive the return frame (813-1, 813-2). When AP 1 (710) receives the return frame (813-1, 813-2) from STA 1 (720), it can recognize that STA 1 (720) is capable of communication. Accordingly, AP 1 (710) can release the communication unavailable section of STA 1 (720) set based on the IDC instruction frame of STA 1 (720) and perform communication with STA 1 (720).

[0215]

[0216] Next, you can consider a method for resuming communication after indicating a communication failure area in the wireless LAN.

[0217] STA 1 (720) may transmit an IDC indication frame to AP 1 (710). The IDC indication frame may be a frame indicating that STA 1 (720) cannot communicate with AP 1 (710). The IDC indication frame may include at least one of a start time of a communication impossibility period between STA 1 (720) and AP 1 (710), an end time of the communication impossibility period, and a length of the communication impossibility period. For example, the IDC indication frame may be a response control frame (RCF) transmitted unsolicited. As another example, the IDC indication frame may be a management frame (e.g., an action frame). If the IDC indication frame is an action frame, the IDC indication frame may be, but is not limited to, a UHR (ultra high reliability) OMN (operating mode notification) frame. The UHR OMN frame may include operating parameters of STA 1 (720) (e.g., communication parameters that can be used when only reception is possible in a communication-unavailable section of STA 1 (720)). AP 1 (710) may receive the IDC indication frame of STA 1 (720) to identify the communication-unavailable section of STA 1 (720). AP 1 (710) may transmit a response frame to the IDC indication frame, and STA 1 (720) may apply the items indicated in the IDC indication frame (e.g., transmission and reception possible section, reception-only section, etc.) after receiving the response frame.

[0218] As another example, the IDC indication frame of STA 1 (720) may further indicate that communication with STA 1 (720) is not completely impossible during the communication impossible section of STA 1 (720). As a specific example, STA 1 (720) may only be capable of reception during the communication impossible section. Therefore, the communication prohibited section indicated by STA 1 (720) through the IDC indication frame of STA 1 (720) may be referred to as a reception-only section of STA 1 (720). The reception-only section may be a section in which STA 1 (720) suspends the "HT-Immediate BA agreement" established through the "BlockAck (BA) Agreement" with AP 1 (710). If the communication impossible section information is not included in the IDC indication frame, the "HT-Immediate BA agreement" suspension is applied after transmitting the IDC indication frame. When AP 1 (710) transmits a response frame to an IDC indication frame, STA 1 (720) may apply a "HT-Immediate BA agreement" suspension after receiving the response frame. STA 1 (720) may be instructed to operate in a restricted operation mode through the IDC indication frame. An STA operating in a restricted operation mode may be an STA in which a specific value for the restricted operation mode of the IDC indication frame is set to a first value, and whether it is in the restricted operation mode may be determined by the STA level or the STA MLD level. Alternatively, even without the separate value, an STA (or STA MLD) that transmitted the IDC indication frame (a frame instructing to suspend the HT-Immediate BA agreement) may be an STA (or STA MLD) operating in a restricted operation mode.

[0219] In order to release the receive-only interval (i.e., to resume (active) the "HT-Immediate BA agreement"), the IDC indication frame can be transmitted again. If STA 1 (720) transmits an IDC indication frame indicating the resumption (active) of the "HT-Immediate BA agreement" and then AP 1 (710) transmits a response frame to the IDC indication frame, STA 1 (720) can apply the resumption (active) of the "HT-Immediate BA agreement" after receiving the response frame. That is, STA 1 (720) can transmit a block ack (BA), which is an immediate response frame, after SIFS time after receiving the data frame in relation to the received data frame. In addition, the IDC indication frame can further include information on the time interval at which the resumption (active) of the "HT-Immediate BA agreement" starts. If the IDC indication frame further includes information on the time interval at which the "HT-Immediate BA agreement" resumption (active) starts, STA 1 (720) can transmit a BA, which is an immediate response frame, after SIFS time after receiving the data frame in relation to the data frame received after the indicated time. Here, a section other than the reception-only section of STA 1 (720) may be a section in which STA 1 (720) can transmit and receive. In other words, the reception-only section is the "HT-Immediate BA agreement" suspend section in which BA is not transmitted, and the section in which transmission and reception is possible is the "HT-Immediate BA agreement" resumption (active) section in which BA can be transmitted. In the transmission and reception possible section of STA 1 (720), STA 1 (720) can receive frames from AP 1 (710) and send response frames (eg) to AP 1 (710).block ack (BA). In addition, the IDC indication frame of STA 1 (720) may further include a block response (BlockAck) method that STA 1 (720) intends to use in the communication prohibited section. As a specific example, STA 1 (720) may not be able to use an immediate block response (immediate block ack) in the communication prohibited section indicated by STA 1 (720). As an example, the immediate block response may be "HT (high throughput)-immediate block ack", but may not be limited thereto. Here, the IDC indication frame of STA 1 (720) may indicate a suspension of a block response agreement (Block Ack agreement) established by STA 1 (720) with AP 1 (710) in the communication prohibited section of STA 1 (720). The block response agreement may be "HT-immediate Block Ack agreement", but may not be limited thereto. For example, in the case described above, STA 1 (720) and AP 1 (710) may use a delayed block ack method to perform frame exchange. The delayed block ack method may be a method in which STA 1 (720) does not transmit a BlockAck frame immediately after receiving a frame from AP 1 (710), but transmits a BlockAck frame after a certain period of time after receiving the frame from AP 1 (710). As another example, if a temporary suspension of block ack agreement between STA 1 (720) and AP 1 (710) is instructed, the BlockAck method may not be used. In the case described above, AP 1 (710) may not transmit an A-MPDU (aggregated-MPDU) including multiple MPDUs (MAC (medium access control) protocol data units) to STA 1 (720).That is, AP 1 (710) can transmit a single MPDU to STA 1 (720). In addition, as an example, AP 1 (710) can transmit only one MSDU (MAC service data unit) in the MPDU transmitted to STA 1 (720). When STA 1 (720) receives a frame from AP 1 (710), it can transmit a response (Ack) frame for a single MPDU (or MSDU).

[0220] STA 1 (720) and AP 1 (710) can transmit and receive uplink and downlink data frames and response frames (e.g., ACK (acknowledgement) frame, BlockAck (BA) frame) for the data frames in the transmission and reception possible section of STA 1 (720). The response policy (Ack Policy) of the uplink and downlink data frames transmitted by STA 1 (720) and AP 1 (710) can be set as a response policy requesting an immediate response. For example, the response policy can be an implicit BAR policy (implicit BAR (BlockAck request) policy). The implicit BAR policy can be a response policy that requests transmission of a block response (BlockAck) frame as an immediate response frame after a short interframe space (SIFS) time from the time of completion of transmission of the data frame. Accordingly, when STA 1 (720) transmits an uplink data frame with an implicit BAR response policy set to AP 1 (710), AP 1 (710) can transmit a block response (BlockAck) frame indicating a reception status for the uplink data frame of STA 1 (720) to STA 1 (720) after SIFS. Conversely, when AP 1 (710) transmits a downlink data frame with an implicit BAR policy set to STA 1 (720), STA 1 (720) receives the downlink data frame and can transmit a block response frame indicating a reception status for the downlink data frame of AP 1 (710) to AP 1 (710) after SIFS. In addition, for example, in the transmission and reception possible section of STA 1 (720), in addition to the data frame exchange set with the above-described implicit BAR policy, data frame exchange with a different form of response policy set may be possible, and may not be limited to a specific form.

[0221] STA 1 (720) can no longer perform frame transmission in the receive-only section of STA 1 (720). AP 1 (710) can confirm an indicator in the IDC indication frame of STA 1 (720) that STA 1 (720) indicates suspension of immediate block response agreement (or HT immediate block ack agreement). If AP 1 (710) confirms an indicator in the IDC indication frame that indicates suspension of immediate block response agreement, AP 1 (710) cannot use immediate block response (or HT immediate block ack) in the receive-only section of STA 1 (720). That is, in the above case, STA 1 (720) cannot transmit an immediate block response (BlockAck) frame for a frame received from AP 1 (710). Therefore, AP 1 (710) may need to select an ack policy that does not require STA 1 (720) to immediately transmit a block response frame.

[0222] AP 1 (710) can transmit a downlink data frame to STA 1 (720), but can transmit the downlink data frame by setting a response policy that does not require STA 1 (720) to immediately transmit a response frame. As a specific example, AP 1 (710) can transmit the downlink data frame to STA 1 (720) by setting the response policy of the downlink data frame to a block response policy (Block Ack policy). The block response policy does not require a terminal receiving the frame to immediately transmit a response frame, but can record the reception status of the received data frame in a block response (BlockAck) scoreboard. Accordingly, STA 1 (720) can record the reception status for the downlink data frame transmitted by AP 1 (710) in the block response scoreboard, but may not transmit a block response (BlockAck, BA) frame as a response frame.

[0223] In addition, AP 1 (710) may not transmit a trigger frame to STA 1 (720) in the reception-only period of STA 1 (720). That is, AP 1 (710) may not allocate uplink resources to STA 1 (720), and AP 1 (710) may not transmit a frame to STA 1 (720) that causes STA 1 (720) to transmit a response frame or an uplink frame. STA 1 (720) may transmit a block response frame indicating a reception status for a downlink frame of AP 1 (710) after the reception-only period of STA 1 (720) ends.

[0224] As another example, STA 1 (720) can no longer perform frame transmission in the receive-only interval of STA 1 (720). AP 1 (710) can check the indicator in the IDC indication frame of STA 1 (720) that STA 1 (720) instructs to suspend the immediate block ack agreement (or HT immediate block ack agreement). In the above-described case, AP 1 (710) cannot use the immediate block ack (or HT immediate block ack) in the receive-only interval of STA 1 (720). Here, STA 1 (720) may not perform frame reception acknowledgment even if it uses all block acknowledgments. STA 1 (720) cannot transmit an immediate block acknowledgment (BlockAck) frame for a frame received from AP 1 (710), and cannot transmit a delayed block acknowledgment (BlockAck) frame. Accordingly, AP 1 (710) may select a response policy in which STA 1 (720) does not need to transmit a BlockAck frame. STA 1 (720) may be capable of transmitting an Ack frame (an Ack frame, not a BlockAck frame). For example, AP 1 (710) may be capable of transmitting only a single MPDU to STA 1 (720) at a time. STA 1 (720) may receive a single MPDU from AP 1 (710) and transmit a response frame for the single MPDU of AP 1 (710). The response frame may be a frame indicating that the frame has been normally received. If STA 1 (720) does not properly receive the single MPDU of AP 1 (710), STA 1 (720) may not transmit a response frame to AP 1 (710).Alternatively, if STA 1 (720) is unable to transmit an Ack frame, STA 1 (720) may transmit a block response frame indicating the reception status for the downlink frame of AP 1 (710) after the reception-only period of STA 1 (720) ends.

[0225] As another example, if the IDC instruction frame of STA 1 (720) further indicates that communication is not completely impossible in a section where communication is impossible for STA 1 (720), STA 1 (720) may only be able to transmit in the section where communication is impossible. Accordingly, the communication prohibition section indicated by STA 1 (720) may be a transmission-only section or a reception-only section of STA 1 (720). A section that is not a transmission-only section of STA 1 (720) is a section where transmission and reception are possible for STA 1 (720). In a section where transmission and reception are possible for STA 1 (720), STA 1 (720) can receive frames from AP 1 (710) and transmit frames to AP 1 (710). STA 1 (720) and AP 1 (710) can transmit and receive uplink and downlink data frames and response frames to data frames (e.g., ACK (acknowledgement) frame, BlockAck (BA) frame) in the transmission and reception possible section of STA 1 (720).

[0226] The response policy of the uplink and downlink data frames transmitted by STA 1 (720) and AP 1 (710) can be set to a response policy that requests an immediate response. For example, the response policy may be an implicit BAR (BlockAck request) policy. The implicit BAR policy may be a response policy that requests transmission of a BA frame as a response frame immediately after a short interframe space (SIFS) from the time of completion of transmission of a data frame. Accordingly, when STA 1 (720) transmits an uplink data frame with an implicit BAR response policy set to AP 1 (710), AP 1 (710) may transmit a block response frame indicating a reception status for the uplink data frame of STA 1 (720) to STA 1 (720) after SIFS. Conversely, when AP 1 (710) transmits a downlink data frame with an implicit BAR policy set to STA 1 (720), STA 1 (720) may transmit a block response frame indicating a reception status for the uplink data frame of AP 1 (710) to AP 1 (710) after SIFS. A block response frame indicating the reception status for a data frame can be transmitted to AP 1 (710). In the transmission and reception possible section of STA 1 (720), not only the exchange of data frames with the aforementioned implicit BAR policy set, but also the exchange of data frames with various response policies set, can be possible.

[0227] On the other hand, STA 1 (720) can no longer receive frames in the transmission-only section of STA 1 (720). STA 1 (720) can transmit an uplink data frame to AP 1 (710), but may need to transmit the uplink data frame by setting a response policy that does not require AP 1 (710) to immediately transmit the response frame. For example, STA 1 (720) may transmit the uplink data frame to AP 1 (710) by setting the response policy of the uplink data frame to a block response policy. The block response policy does not require the terminal receiving the frame to immediately transmit the response frame, but may record the reception status of the received data frame in a block response scoreboard. Accordingly, AP 1 (710) can record the reception status of the uplink data frame transmitted by STA 1 (720) in the block response scoreboard. On the other hand, AP 1 (710) may not transmit a block response frame as a response frame. In addition, AP 1 (710) may not transmit a frame to STA 1 (720) in the transmission-only section of STA 1 (720), and may transmit a block response frame indicating the reception status of the uplink frame of STA 1 (720) after the transmission-only section of STA 1 (720) ends.

[0228] For example, FIGS. 17a and 17b may be cases where a reception-only section of STA 1 (720) applied to the present disclosure is indicated.

[0229] Referring to FIG. 17A, AP 1 (710) may transmit a BAR frame (817) requesting a block response (BlockAck) frame of STA 1 (720) after the reception-only period of STA 1 (720) ends (i.e., in a period in which STA 1 (720) can transmit and receive). The BAR frame (817) may be a frame for requesting a block response frame (818) for the downlink data frames (816-1, 816-2) of AP 1 (710) received by STA 1 (720). STA 1 (720) records the reception status of the downlink data frame received from AP 1 (710) on the block response scoreboard, and thus can transmit a block response frame (818) indicating the reception status of the downlink data frame (816-1, 816-2) to AP 1 (710) based on the information. AP 1 (710) receives the block response frame (818) of STA 1 (720), and can perform retransmission if there is a frame in which a reception error occurred in STA 1 (720).

[0230] As another example, referring to FIG. 17b, STA 1 (720) may transmit a block response frame (820) indicating the reception status of the downlink data frames (819-1, 819-2) received from AP 1 (710) without receiving a BAR frame from AP 1 (710) after the reception-only section of STA 1 (720) ends (i.e., in the section in which STA 1 (720) can transmit and receive). Since STA 1 (720) has recorded the reception status of the downlink data frames (819-1, 819-2) received from AP 1 (710) on the scoreboard as a block response, STA 1 (720) may transmit a block response frame (820) indicating the reception status of the downlink frame to AP 1 (710) based on the information. AP 1 (710) receives a block response frame (820) from STA 1 (720), and if there is a frame in which a reception error occurred in STA 1 (720), retransmission can be performed. That is, since AP 1 (710) has received a block response frame from STA 1 (720), it may not transmit a BAR frame to STA 1 (720).

[0231] As another example, AP 1 (710) can transmit an additional data frame to STA 1 (720) after the reception-only section of STA 1 (720) ends (i.e., in the section in which STA 1 (720) can transmit and receive), and the response policy of the data frame can be set to an implicit BAR policy and transmitted. Since STA 1 (720) has recorded the reception status of the downlink data frame received from AP 1 (710) in the block response scoreboard, STA 1 (720) can transmit a block response frame (818) indicating the reception status of the additional data frame and downlink data frames (816-1, 816-2) to AP 1 (710) based on the information. AP 1 (710) receives the block response frame (818) of STA 1 (720) and can perform retransmission if STA 1 (720) has a frame in which a reception error has occurred.

[0232] As another example, FIGS. 18a and 18b may be cases where a transmission-only section of STA 1 applied to the present disclosure is indicated.

[0233] Referring to FIG. 18A, STA 1 (720) may transmit a BAR frame (822) requesting a block response frame (823) of AP 1 (710) after the transmission-only section of STA 1 (720) ends. That is, STA 1 (720) may transmit a BAR frame (822) requesting a block response frame (823) of AP 1 (710) in the transmission-reception possible section of STA 1 (720). The BAR frame (822) may be a frame requesting a block response frame (823) for the uplink data frames (821-1, 821-2) of STA 1 (720) received by AP 1 (710). Since AP 1 (710) records the reception status of the uplink data frame (821-1, 821-2) received from STA 1 (720) on the block response scoreboard, it can transmit a block response frame (823) indicating the reception status of the uplink data frame (821-1, 821-2) to STA 1 (720) based on the information. STA 1 (720) receives the block response frame (823) of AP 1 (710) and can perform retransmission if there is a frame in which a reception error occurred in AP 1 (710).

[0234] Referring to FIG. 18b, AP 1 (710) can transmit a block response frame (825) indicating the reception status of uplink data frames (824-1, 824-2) received from STA 1 (720) even if it does not receive a BAR frame from STA 1 (720) after the transmission-only section of STA 1 (720) ends. That is, AP 1 (710) can transmit a block response frame (825) indicating the reception status of uplink data frames (824-1, 824-2) received from STA 1 (720) even if it does not receive a BAR frame from STA 1 (720) in the transmission-reception possible section of STA 1 (720). Since AP 1 (710) records the reception status of the uplink data frames (824-1, 824-2) received from STA 1 (720) on the block response scoreboard, it can transmit a block response frame (825) indicating the reception status of the uplink data frames (824-1, 824-2) to STA 1 (720) based on the information. Since STA 1 (720) received the block response frame (825) of AP 1 (710), it can perform retransmission if there is a frame in which a reception error occurred in AP 1 (710). Since STA 1 (720) received the block response frame (825) from AP 1 (710), STA 1 (720) may not transmit a BAR frame to AP 1 (710).

[0235] As another example, STA 1 (720) may transmit an additional data frame to AP 1 (710) after the transmission-only section of STA 1 (720) ends, and the response policy of the data frame may be set to an implicit BAR policy and transmitted. Since AP 1 (710) has recorded the reception status of the uplink data frames (821-1, 821-2) received from STA 1 (720) in the block response scoreboard, it may transmit a block response frame (823) indicating the reception status of the additional data frame and the uplink data frames (821-1, 821-2) to STA 1 (720) based on the information. STA 1 (720) may receive the block response frame (823) of AP 1 (710) and perform retransmission if there is a frame in which a reception error has occurred in AP 1 (710).

[0236] Figure 19 is a diagram illustrating a method for resuming communication after indicating a communication failure section in a wireless LAN applicable to the present disclosure.

[0237] Referring to FIG. 19, STA 1 (720) may want to search for other APs (e.g., AP 2, AP 3). Here, a channel on which at least one of AP 2 (730) and AP 3 (740) operates may be different from the channel of AP 1 (710). For example, when STA 1 (720) searches for AP 2 (730) and AP 3 (740), a communication unavailable period may occur in STA 1 (720). When STA 1 (720) searches for other APs, STA 1 (720) may want to perform a roaming operation, which may result in a communication unavailable period. STA 1 (720) may transmit an IDC indication frame (826) to AP 1 (710) to indicate to AP 1 (710) a communication unavailable period due to the search for other APs. The IDC indication frame (826) may be a frame indicating that STA 1 (720) is unable to communicate with AP 1 (710). The IDC indication frame (826) may include at least one of the start time of a period in which STA 1 (720) is unable to communicate with AP 1 (710), the end time of the period in which communication is impossible, and the length of the period in which communication is impossible. The IDC indication frame (826) may be a response control frame (RCF) transmitted unsolicited. Alternatively, the IDC indication frame (826) may be a management frame (e.g., an action frame). AP 1 (710) may receive the IDC indication frame (826) of STA 1 (720) and confirm the period in which communication is impossible for STA 1 (720). For example, STA 1 (720) may set multiple communication unavailable periods for STA 1 (720) by transmitting an IDC instruction frame (826). The communication unavailable periods for STA 1 (720) may be referred to as discovery periods for STA 1 (720), and STA 1 (720) may be unable to communicate with AP 1 (710) during the discovery period for STA 1 (720).As a specific example, the search period of STA 1 (720) may be set twice, and may be referred to as search period 1 (search period 1) of STA 1 (720) and search period 2 (search period 2) of STA 1 (720), respectively. However, this is for convenience of explanation and may not be limited thereto. STA 1 (720) may search for AP 2 (730) in search period 1. STA 1 (720) may operate on a channel on which AP 2 (730) operates in search period 1 to search for AP 2 (730). STA 1 (720) may search for AP 2 (730) by transmitting a probe request frame (827) and receiving a probe response frame (828) from AP 2 (730) (i.e., active scanning). As another example, STA 1 (720) can search for AP 2 by receiving a beacon frame from AP 2 (730) (i.e., passive scanning). Similarly, STA 1 (720) can search for AP 3 (740) in search section 2 by either active scanning or passive scanning.

[0238] AP 1 (710) may not transmit frames to STA 1 (720) that cannot receive frames from AP 1 (710) in search periods 1 and 2. As described above, AP 1 (710) may prevent a situation in which wireless communication resources are wasted. Here, at least one of search periods 1 and 2 of STA 1 (720) may be terminated early. For example, STA 1 (720) may give up searching for an AP or may complete searching for an AP early. If STA 1 (720) wishes to terminate the search period early, STA 1 (720) may transmit a return frame to AP 1 (710) as described above. When AP 1 (710) receives a return frame from STA 1 (720), AP 1 (710) can release the discovery period of STA 1 (720) and transmit a data frame to STA 1 (720). However, this is for convenience of explanation and is not limited to the embodiment.

[0239] Referring to FIGS. 11 to 14 and FIGS. 17a and 17b , an STA (or STA MLD) may operate in a restricted operation mode. There may be a restricted operation mode indication frame, which is a frame that indicates at least one of a deactivation subchannel (i.e., a deactivation subchannel bitmap) of the STA according to FIGS. 11 to 14 or a suspension of an HT-immediate BA agreement according to FIGS. 17a and 17b . That is, an STA may indicate both a deactivation subchannel and a suspension of an HT-immediate BA agreement at once through a single frame. For example, if an STA transmits a restricted operation mode indication frame to an AP, and the restricted operation mode indication frame indicates at least one of a deactivation subchannel and a suspension of an HT-immediate BA agreement, the AP may know that the STA must perform at least one of a deactivation subchannel and a suspension of an HT-immediate BA agreement. In this case, the STA operates in a restricted operation mode. The AP may transmit a punctured frame to the STA using the operation method according to FIGS. 11 to 14 when the STA has a disabled subchannel, and may transmit a frame to the STA according to FIGS. 17a and 17b when the STA indicates the termination of the HT-immediate BA agreement. Meanwhile, the STA may indicate both the presence of a disabled subchannel and the indication of the HT-immediate BA agreement. In this case, the AP must transmit a frame to the STA using both the methods of FIGS. 11 to 14 and FIGS. 17a and 17b. Meanwhile, in FIGS. 11 to 14, the STA may use the restricted operation mode indication frame to indicate the disabled subchannel.Additionally, in FIG. 17a and FIG. 17, the STA may use the restricted operation mode indication frame to indicate the termination of the HT-immediate BA agreement.

[0240] FIG. 20 is a flowchart illustrating a method for indicating an available link in a wireless LAN applied to the present disclosure. An AP may transmit an initial control frame to a first STA (S2010). Thereafter, the AP receives a response frame from the first STA in response to the initial control frame (S2020), and the AP may communicate with the first STA based on the response frame (S2030). Here, the response frame may be the RCF or ICR described above, but is not limited thereto. For example, if the AP receives a response frame indicating that the first STA is unable to communicate, it may further transmit a CF-End frame. The NAV of a second STA that decodes the response frame transmitted by the first STA may be released by the response frame, and the NAV of a third STA that cannot decode the response frame transmitted by the first STA may be released by the CF-End frame. Additionally, if there is downlink data to be transmitted to a third STA after the AP receives a response frame indicating that the first STA is unable to communicate, the AP may transmit a downlink data frame to the third STA in the TXOP set by the initial control frame, and receive a response frame for the downlink data frame from the third STA. The NAV of the second STA released by the response frame may be reset by the downlink data frame.

[0241] In addition, if the first STA is indicated as being unavailable for communication by the response frame, the response frame may further include information on the point in time when the first STA becomes unavailable for communication and the period during which the first STA becomes unavailable for communication. Here, the value of the duration field of the MAC header of the response frame is set to a value until the point in time when the first STA becomes unavailable for communication after the response frame is transmitted, and the NAV set for STAs other than the first STA may be maintained based on the value of the duration field until the point in time when the first STA becomes unavailable for communication. In addition, if there is downlink data to be transmitted to the first STA in the AP, the AP may compare the point in time when the first STA becomes unavailable for communication and the TXOP of the AP based on the information on the point in time when the first STA becomes unavailable for communication and the period during which the first STA becomes unavailable for communication, and transmit a downlink data frame to the first STA. In addition, if the first STA is indicated as being unavailable for communication by the response frame, the response frame may further include a NAV release prohibition indicator, and the NAV set for STAs other than the first STA may be maintained based on the NAV release prohibition indicator. In addition, if the AP does not receive a response frame from the first STA for a preset time after transmitting the initial control frame, the NAV set for STAs other than the first STA by the initial control frame is released after a preset time after receiving the initial control frame, and the AP may lower the MCS (modulation and coding) index for the next frame and increase the channel access parameter. In addition, according to one embodiment of the present specification, if the AP receives a delayed response frame based on the resumption of communication of the first STA, the AP may return the lowered MCS index and the increased channel access parameter to their previous values.In addition, according to one embodiment of the present specification, the AP may be an AP multi-link device (MLD) including AP 1 associated with a first link and AP 2 associated with a second link, and the first STA may be a first STA MLD including a first STA 1 associated with the first link and a first STA 2 associated with the second link. For example, the AP MLD may transmit an initial control frame on the first link for AP 1, and the AP MLD may receive a response frame transmitted from the first STA MLD for AP 1 through the first link, wherein the response frame may include at least one of a first link communication availability indicator and a second link communication availability indicator. In addition, when it is indicated based on the response frame that communication is not possible on the first link and communication is possible on the second link, the AP MLD may perform a channel access operation on the second link for AP 2 to transmit a downlink data frame of the first STA MLD. For example, the response frame further includes at least one of a first link communication unavailability period indicator and a second link communication unavailability period indicator, and if the communication possible time of the second link is earlier than the communication possible time of the first link based on the first link communication unavailability period indicator and the second link communication unavailability period indicator, the AP MLD may perform a channel access operation on the second link for AP 2 to transmit the downlink data frame of the first STA MLD, and if the communication possible time of the first link is earlier than the communication possible time of the second link based on the first link communication unavailability period indicator and the second link communication unavailability period indicator, the AP MLD may transmit the downlink data frame of the first STA MLD on the first link for AP 1 based on the TXOP of the AP MLD.In addition, according to one embodiment of the present specification, the AP MLD can receive a response frame including at least one of a first link communication availability indicator and a second link communication availability indicator without receiving an initial control frame. Here, if the AP MLD does not receive a response frame from the first STA MLD for a preset time after transmitting the initial control frame, the NAV set for STAs other than the first STA MLD by the initial control frame is released after a preset time after receiving the initial control frame, and the AP MLD lowers an MCS (modulation and coding) index for the next frame and increases a channel access parameter; however, if the AP MLD receives a delayed response frame from the second link for AP 2, the AP MLD can return the lowered MCS index and the increased channel access parameter to their original values. Additionally, after the AP determines the communication unavailability period of the first STA in the TXOP of the AP based on the response frame, if the AP receives a return frame from the first STA indicating an early termination of the communication unavailability period of the first STA, the AP can resume communication with the first STA.

[0242] FIG. 21 is a flowchart illustrating an operation method of an STA indicating an available link in a wireless LAN applied to the present disclosure. Referring to FIG. 21, an STA may transmit a restricted operation mode indication frame to an AP (S2110). In the above-described case, the STA may operate in a restricted operation mode indicated by the restricted operation mode indication frame (S2120). Here, the restricted operation mode indication frame may include information indicating at least one of deactivation link information of the STA (e.g., deactivation subchannel bitmap information) for the restricted operation mode operation of the STA or whether to stop the BA negotiation (or HT-immediate BA negotiation) content (agreement). As an example, the restricted operation mode indication frame may include bitmap information indicating a deactivation link (or subchannel) of the STA. The STA may transmit a restricted operation mode indication frame including bitmap information indicating a deactivation link (or subchannel), and perform puncturing for a link (or subchannel) indicated to be deactivated in the bitmap as a restricted operation. That is, the STA and the AP may not use a link (or subchannel) that is indicated to be disabled via a bitmap in communication. As another example, the restricted operation mode indication frame may include information indicating the application of a suspension of the BA agreement. The STA may transmit a restricted operation mode indication frame containing information indicating the suspension of the BA agreement, and may apply the suspension of the existing BA agreement as a restricted operation. That is, the STA may suspend the BA agreement established with the AP through a Block Ack (BA) Agreement.

[0243] The methods according to the present disclosure may be implemented in the form of program instructions that can be executed by various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., 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 may be known and available to those skilled in the art of computer software. Examples of the computer-readable medium include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include not only machine language codes generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc. The above-described hardware devices 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 disclosure has been described with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present disclosure without departing from the spirit and scope of the present disclosure as set forth in the claims below.

[0244]

[0245]

[0246]

[0247] The above may also apply to other systems.

Claims

1. In the operating method of an access point (AP) in a wireless LAN system, A step in which the AP transmits an initial control frame to a first station (STA); A step in which the AP receives a response frame from the first STA in response to the initial control frame; and Including a step of performing communication with the first STA based on the response frame, NAV (network allocation vector) is set for STAs other than the first STA by the above initial control frame, The above response frame includes an indicator of whether the first STA can communicate, An operating method in which, when the first STA is indicated as being unable to communicate by the response frame, the NAV set for STAs other than the first STA is released based on the response frame.

2. In paragraph 1, When the AP receives the response frame indicating that the first STA is unable to communicate, it further transmits a CF (contention free)-End frame. An operating method, wherein the NAV of a second STA that decodes the response frame transmitted by the first STA is released by the response frame, and the NAV of a third STA that cannot decode the response frame transmitted by the first STA is released by the CF-End frame.

3. In paragraph 2, If there is downlink data to be transmitted to the third STA after the AP receives the response frame indicating that the first STA is unable to communicate, the AP transmits a downlink data frame to the third STA at a transmit opportunity (TXOP) set by the initial control frame, and receives a response frame for the downlink data frame from the third STA. An operating method in which the NAV of the second STA released by the response frame is reset by the downlink data frame.

4. In paragraph 1, An operating method, wherein, when the first STA is indicated as being unable to communicate by the response frame, the response frame further includes information on the time point at which the first STA is unable to communicate and the period during which the first STA is unable to communicate.

5. In paragraph 4, The duration field value of the MAC (medium access control) header of the response frame is set to a value until the point in time when the first STA becomes unable to communicate after transmitting the response frame, An operating method in which the NAV set for the other STAs other than the first STA is maintained until the communication of the first STA becomes impossible based on the duration field value.

6. In paragraph 4, An operating method in which, when there is downlink data to be transmitted to the first STA in the AP, the AP compares the communication resumption time of the first STA and the TXOP of the AP based on the communication unavailability time of the first STA and the communication unavailability period information of the first STA, and transmits a downlink data frame to the first STA.

7. In paragraph 1, If the first STA is indicated as being unable to communicate by the response frame, the response frame further includes a NAV release prohibition indicator, An operating method in which the NAV set for STAs other than the first STA is maintained based on the NAV release prohibition indicator.

8. In paragraph 1, If the AP does not receive the response frame from the first STA for a preset period of time after transmitting the initial control frame, the NAV set for the other STAs other than the first STA by the initial control frame is released after a preset period of time after receiving the initial control frame. The above AP operates by lowering the MCS (modulation and coding) index for the next frame and increasing the channel access parameter.

9. In paragraph 8, An operating method in which, when the AP receives a delayed response frame based on the resumption of communication of the first STA, the AP returns the lowered MCS index and the increased channel access parameter to their original values.

10. In paragraph 1, The above AP is an AP multi link device (MLD) including AP 1 associated with a first link and AP 2 associated with a second link, The method of operation, wherein the first STA is a first STA MLD including a first STA 1 associated with the first link and a first STA 2 associated with the second link.

11. In paragraph 10, The AP MLD transmits the initial control frame on the first link for the AP 1, and the AP MLD receives the response frame transmitted from the first STA MLD on the first link for the AP 1. A method of operation, wherein the response frame includes at least one of a first link communication availability indicator and a second link communication availability indicator.

12. In paragraph 11, An operating method in which, based on the response frame, if it is indicated that communication is impossible on the first link and communication is possible on the second link, the AP MLD performs a channel access operation on the second link for the AP 2 to transmit a downlink data frame of the first STA MLD.

13. In paragraph 11, The above response frame further includes at least one of a first link communication unavailable section indicator and a second link communication unavailable section indicator, If the communication possible time of the second link is earlier than the communication possible time of the first link based on the first link communication unavailable section indicator and the second link communication unavailable section indicator, the AP MLD performs a channel access operation on the second link for the AP 2 to transmit the downlink data frame of the first STA MLD, An operating method in which, when the communication possible time of the first link is earlier than the communication possible time of the second link based on the first link communication unavailable section indicator and the second link communication unavailable section indicator, the AP MLD transmits a downlink data frame of the first STA MLD on the first link for the AP 1 based on the TXOP of the AP MLD.

14. In paragraph 11, A method of operation, wherein the AP MLD receives the response frame including at least one of the first link communication availability indicator and the second link communication availability indicator without receiving the initial control frame.

15. In paragraph 11, If the AP MLD does not receive the response frame from the first STA MLD for a preset time after transmitting the initial control frame, the NAV set for the other STAs other than the first STA MLD by the initial control frame is released after a preset time after receiving the initial control frame, and the AP MLD lowers the MCS (modulation and coding) index for the next frame and increases the channel access parameter. An operating method in which, when the AP MLD receives a delayed response frame from the second link for the AP 2, the AP MLD returns the lowered MCS index and the increased channel access parameter to their original values.

16. In paragraph 1, An operating method in which, after a communication unavailable period of a first STA is determined in a TXOP of an AP based on the response frame, when the AP receives a return frame from the first STA indicating an early termination of the communication unavailable period of the first STA, the AP resumes communication with the first STA.

17. In paragraph 1, An operating method in which the AP further transmits a first frame indicating a communication unavailable period of the AP, the first frame including at least one of information on the communication unavailable period of the AP and information on the reason for the communication unavailable period of the AP, and the AP performs communication with the first STA without a re-association procedure based on the maintained configuration information when the communication unavailable period of the AP ends.

18. In paragraph 17, An operating method in which the AP resumes communication with the first STA when the AP transmits a return frame instructing early termination of the AP's communication unavailability period before the expiration of the AP's communication unavailability period.

19. In paragraph 1, An operating method in which the AP further receives a second frame indicating a communication unavailable period of the STA, the second frame including at least one of information on the communication unavailable period of the STA and information on the reason for the communication unavailable period of the STA, and the AP performs communication with the first STA without a re-association procedure based on the maintained configuration information when the communication unavailable period of the STA ends.

20. In paragraph 17, An operating method in which the AP resumes communication with the first STA when the AP receives a return frame instructing early termination of the STA's communication unavailability period before the expiration of the STA's communication unavailability period.

21. In paragraph 1, The AP further receives a third frame indicating at least one of a reception-only interval and a transmission-only interval of the STA, wherein the third frame includes an indicator indicating a temporary suspension of a block response policy, A method of operation in which the above AP changes a block response policy based on the above directive.

22. In the access point (AP), At least one transceiver for transmitting and receiving signals; At least one processor controlling at least one transceiver; and A memory storing instructions that cause the AP to perform a specific operation by at least one processor, The above specific actions are: Transmit an initial control frame to the first station (STA), The AP receives a response frame from the first STA in response to the initial control frame, and Perform communication with the first STA based on the above response frame, The network allocation vector (NAV) is set to STAs other than the first STA by the initial control frame, The above response frame includes an indicator of whether the first STA can communicate, An AP in which the NAV set for STAs other than the first STA is released based on the response frame when the first STA is indicated as being unable to communicate by the response frame.

23. In the operation method of a station (STA) in a wireless LAN system, A step of transmitting a restricted operation mode indication frame to the AP; and An operating method comprising a step of causing an STA to operate in a restricted operating mode indicated by a restricted operating mode indication frame.

24. At the station (STA), At least one transceiver for transmitting and receiving signals; At least one processor controlling at least one transceiver; and A memory storing instructions that cause the STA to perform a specific operation by at least one processor, The above specific actions are: Transmits a restricted operation mode indication frame to the AP, and An STA that operates in a restricted operation mode as directed by a restricted operation mode indication frame.

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