Method and apparatus for performing reverse transmission in wireless LAN

Abstract

A method for operating an AP in a wireless LAN system includes the steps of: receiving a first frame indicating permission for reverse communication from a first STA; determining a reverse communication period on the basis of a TXOP of the first STA when the first frame indicates permission for reverse communication; transmitting one or more frames to a second STA within the reverse communication period; and terminating the reverse communication when transmission of a last frame among the one or more frames transmitted to the second STA is performed or the reverse communication period expires.

Description

Method and device for performing reverse transmission in wireless LAN

[0001] The present disclosure relates to a method and device for performing reverse transmission in a Wireless Local Area Network (WLAN). Specifically, the present disclosure relates to a method and device for performing artificial intelligence-based reverse communication in a WLAN.

[0002] In addition, the present disclosure relates to a method and device for exchanging frames based on artificial intelligence between multiple link single radio STAs in a wireless LAN.

[0003]

[0004] With the recent proliferation of mobile devices, wireless LAN technology, which can provide fast wireless communication services to these devices, is attracting significant attention. Wireless LAN 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.

[0005] 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.

[0006] Recently, as applications requiring higher reliability arise, the IEEE 802.11bn standard, an ultra-high reliability (UHR) wireless LAN technology, is being developed for single BSS (Basic Service Set) and / or redundant BSS environments. The goals of the IEEE 802.11bn standard may include supporting increased data transmission speeds, improved latency performance, and lower data error rates. Furthermore, the IEEE 802.11bn standard can support low-power operation and direct communication (peer-to-peer, P2P communication).

[0007] In a wireless LAN, multiple terminals can use wireless resources. However, as the number of wireless terminals using wireless resources increases, communication delays due to channel access and inefficient use of wireless resources can occur. This can lead to performance issues in the wireless LAN network.

[0008] 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, and may not be limited to a specific form.

[0009]

[0010] The present disclosure may provide a method and device for performing reverse communication in a wireless LAN.

[0011] The present disclosure can provide a method and device for determining a reverse communication section in a wireless LAN.

[0012] The present disclosure may provide a method and device for recovering a reverse communication section in a wireless LAN.

[0013] The present disclosure may provide a method and device for performing a reverse communication membership negotiation procedure in a wireless LAN.

[0014] The present disclosure can provide a method and device for reducing delay based on artificial intelligence in a wireless LAN and performing reverse communication based on efficient utilization of wireless resources.

[0015] The present disclosure can provide a method for a wireless LAN terminal to perform an EMLSR operation in a wireless LAN, and then transition to a listening operation, which is an operation state of the EMLSR operation, after the wireless LAN terminal transmits a frame for which no response is required to a wireless access point.

[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 will 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 example of the present disclosure, a method for operating an access point (AP) in a wireless LAN system may include the steps of: receiving a first frame indicating permission for reverse communication from a first station (STA); determining a reverse communication period based on a transmission opportunity (TXOP) of the first STA if the first frame indicates permission for reverse communication; transmitting at least one frame to a second STA within the reverse communication period; and performing a last frame transmission among the at least one frame transmitted to the second STA or terminating reverse communication when the reverse communication period expires.

[0019] In addition, according to one example of the present disclosure, a wireless user device includes at least one processor and a memory storing instructions for causing the wireless user device to perform a specific operation by the at least one processor, wherein the specific operation includes: receiving a first frame indicating permission for reverse communication from a first station (STA), determining a reverse communication period based on a transmission opportunity (TXOP) of the first STA when the first frame indicates permission for reverse communication, transmitting at least one frame to a second STA within the reverse communication period, and performing a last frame transmission among the at least one frame to be transmitted to the second STA or terminating the reverse communication when the reverse communication period expires.

[0020] In addition, according to an example of the present disclosure, a method of operating a station (STA) in a wireless LAN system includes a step of transmitting a first frame including a reverse direction grant (RDG) indicating whether reverse communication is permitted to an access point (AP), and a step of transmitting data when a data transmission possible condition is satisfied, wherein the reverse direction grant transmitted to the AP is used by the AP for at least one of a decision on reverse communication based on a transmission opportunity (TXOP) of a wireless user device and a decision on whether to initiate a procedure for transmitting at least one frame to another STA based on the decision on reverse communication, and the data transmission possible condition may be characterized in that the last frame among at least one frame is transmitted by the AP or the reverse communication period expires and reverse communication is terminated.

[0021] In addition, according to one example of the present disclosure, a wireless user device includes at least one processor and a memory storing instructions for causing the wireless user device to perform a specific operation by the at least one processor, wherein the specific operation is: transmitting a first frame including a reverse direction grant (RDG) indicating whether reverse communication is permitted to an access point (AP), and transmitting data when a data transmission possibility condition is satisfied, wherein the reverse direction grant transmitted to the AP is used by the AP for at least one of a decision on reverse communication based on a transmission opportunity (TXOP) of the wireless user device and a decision on whether to initiate a procedure for transmitting at least one frame to another STA based on the decision on reverse communication, and wherein the data transmission possibility condition is characterized in that the last frame among at least one frame is transmitted by the AP or the reverse communication period expires and reverse communication is terminated.

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

[0023] According to one example of the present disclosure, the first frame may include a reverse direction grant (RDG) indicating whether reverse communication is permitted, an AC restriction indicator indicating whether an access category (AC) of data is restricted, and an AC of first STA data, but if the RDG indicates permission for reverse communication, the first frame may further include a reverse direction grant others (RDGO) indicator indicating whether data transmission to other STAs other than the first STA granting reverse communication is possible, and if the AC restriction indicator permits data transmission having an AC different from the AC of the first STA data in reverse communication, the first frame may further include a TXOP extension grant indicator indicating whether a reverse communication period is extendable.

[0024] In addition, according to one example of the present disclosure, the AP initiates reverse communication by transmitting a response frame including information indicating initiation of reverse communication to the first STA, and when the AP transmits at least one frame to a second STA different from the first STA based on an RDGO indicator, the at least one frame includes a next transmission frame presence indicator, and a last frame of the at least one frame can be identified based on the next transmission frame presence indicator.

[0025] In addition, according to one example of the present disclosure, the AP transmits a frame header of the last frame including period information for receiving a response frame from the second STA, and terminates reverse communication based on the period information, but the last frame is received by a first STA having a different receiver address from the last frame, and indicates whether the AP transmits the last frame and the end time of reverse communication based on the period information, and if the TXOP of the first STA remains after the end time of reverse communication, frame transmission by the first STA can be performed through the TXOP of the first STA.

[0026] In addition, according to an example of the present disclosure, when the AC restriction indicator permits data transmission having an AC different from the AC of the first STA data in reverse communication and the TXOP extension grant indicator permits extension of the reverse communication period, the AP may determine the TXOP corresponding to the AC of the second frame as the reverse communication period if the TXOP corresponding to the AC of the second frame transmitted to the second STA is longer than the TXOP of the first STA, and may determine the TXOP of the first STA as the reverse communication period if the TXOP corresponding to the AC of the second frame transmitted to the second STA is shorter than the TXOP of the first STA.

[0027] Additionally, according to an example of the present disclosure, the starting point of the TXOP corresponding to the AC of the second frame may be determined as the starting point of the TXOP of the first STA or the starting point of reverse communication.

[0028] Additionally, according to one example of the present disclosure, the first frame further includes frame segmentation related information, and the AP transmits at least one frame to the second STA according to a segmented frame length indicated based on the frame segmentation related information, wherein at least one of the frames transmitted based on the segmented frame length can be transmitted at a Priority Inter-Frame Space (PIFS) interval that is longer than a short inter-frame space (SIFS).

[0029] In addition, according to one example of the present disclosure, when the AP receives a reverse recovery request frame from the first STA, the reverse communication recovery request frame is received after an SIFS time from the end time of transmission of a second frame among at least one frame, and when the AP receives the reverse communication recovery request frame, the AP may transmit a frame instructing the second STA to stop using reverse communication after the SIFS time or may immediately stop reverse communication.

[0030] In addition, according to an example of the present disclosure, an ack policy of a frame indicating the discontinuation of reverse communication is set to a ack request, and a ack frame for a frame indicating the discontinuation of reverse communication is received after an SIFS time from a second STA that receives the frame indicating the discontinuation of reverse communication based on the ack policy, and the AP can discontinue reverse communication when it receives the ack frame for the frame indicating the discontinuation of reverse communication.

[0031] In addition, according to an example of the present disclosure, when an AP transmits at least one multi-user (MU) frame to a plurality of STAs including a second STA according to a segmented frame length indicated based on frame segmentation-related information, when the AP receives a reverse communication recovery request frame, the AP transmits an MU frame instructing the plurality of STAs including the second STA to stop using reverse communication after an SIFS time or to immediately stop reverse communication, wherein the MU frame may indicate subchannel information on which the plurality of STAs including the second STA will transmit a response frame to the MU frame.

[0032] In addition, according to an example of the present disclosure, the AP performs a reverse communication membership negotiation procedure with at least one of the first STA or STAs capable of providing reverse communication, and determines a reverse communication STA based on the reverse communication membership negotiation procedure, wherein the reverse communication membership negotiation procedure may determine at least one of reverse operation participation level information indicating whether the reverse communication STA necessarily participates in a reverse communication operation, reverse operation participation time information indicating a membership status maintenance time of the reverse communication STA, and reverse communication-related parameters.

[0033] Additionally, according to an example of the present disclosure, the AP may transmit a buffer status report (BSR) including at least one of information on the total data size existing in the queue of the AP, information on the data size per AC, and information on the transmission execution time in reverse communication to a reverse communication STA determined based on a reverse communication negotiation procedure.

[0034] Additionally, according to an example of the present disclosure, an enhanced distributed channel access (EDCA) backoff operation may be performed by the STA for reverse communication use of the AP even if there are no packets in the transmission queue after the backoff for the reverse communication STA determined based on the reverse communication negotiation procedure.

[0035] Additionally, according to an example of the present disclosure, when a MU (multi-user) EDCA parameter is set to allow a reverse communication STA determined based on a reverse communication negotiation procedure to occupy a channel with a lower probability, the MU EDCA parameter may not be applied to the reverse communication STA while the reverse communication membership status is maintained based on reverse operation participation time information, or a separate EDCA parameter for the reverse communication STA may be applied.

[0036]

[0037] According to the present disclosure, a method for performing reverse communication in a wireless LAN can be provided.

[0038] According to the present disclosure, a wireless LAN terminal can grant a reverse communication section to another terminal in a set transmission section.

[0039] According to the present disclosure, a reverse communication section can be determined in a wireless LAN.

[0040] According to the present disclosure, a reverse communication section can be recovered in a wireless LAN.

[0041] According to the present disclosure, a reverse communication membership negotiation procedure can be performed in a wireless LAN.

[0042] According to the present disclosure, a method for selecting reverse communication extension, recovery, and channel access parameters by an artificial intelligence reverse communication scheduling technique in a wireless LAN can be provided, thereby reducing channel access delay and increasing network efficiency.

[0043] According to the present disclosure, a method can be provided in which a wireless LAN terminal performs an EMLSR operation in a wireless LAN, and the wireless LAN terminal transmits a frame for which no response is required to a wireless access point, and then transitions to a listening operation, which is an operation state of the EMLSR operation.

[0044] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the description below.

[0045]

[0046] Figure 1 is a diagram showing a communication node within a wireless LAN system to which the present disclosure is applied.

[0047] Figure 2 is a diagram showing a wireless LAN system to which the present disclosure is applied.

[0048] FIG. 3 is a diagram illustrating a machine learning unit to which the present disclosure is applied.

[0049] FIG. 4 is a flowchart illustrating a method for performing communication based on a machine learning unit to which the present disclosure is applied.

[0050] FIG. 5a and FIG. 5b are diagrams showing a method for extending a reverse communication period to which the present disclosure is applied.

[0051] Figures 6a to 6c are drawings showing a RD section recovery method to which the present disclosure is applied.

[0052] FIG. 7a and FIG. 7b are diagrams showing a reverse transmission induction method of an STA to which the present disclosure is applied.

[0053] FIG. 8 is a diagram illustrating a method for applying differentiated channel access parameters based on reverse transmission induction of an STA to which the present disclosure is applied.

[0054] FIG. 9 is a diagram showing multiple links established between MLDs to which the present disclosure applies.

[0055] FIG. 10 is a diagram illustrating a frame exchange method in an improved multi-link single radio operation of a wireless LAN to which the present disclosure is applied.

[0056] FIG. 11a and FIG. 11b are diagrams illustrating a frame exchange method in an improved multi-link single radio operation of a wireless LAN to which the present disclosure is applied.

[0057] Fig. 12 is a flowchart showing an operation method of an AP performing reverse transmission in a wireless LAN applied to the present disclosure.

[0058] Fig. 13 is a flowchart showing an operation method of an STA that permits reverse transmission in a wireless LAN applied to the present disclosure.

[0059]

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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."

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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).

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] As another example, the machine learning unit (300) may be designed to implement not only the machine learning algorithm but also other machine learning algorithms. 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.

[0076] 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).

[0077] 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 a dedicated bus or interface centered around the processor (110) of the communication node (100), but may not be limited to the above embodiment.

[0078] 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 coordination function) 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.

[0079] 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.

[0080] 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).

[0081] 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.

[0082] FIG. 5A and FIG. 5B are diagrams illustrating a method for extending a reverse communication period applied to the present disclosure. As an example, FIG. 5A and FIG. 5B may be a method for extending a reverse communication period in an environment in which AP (510), STA 1 (520), STA X (531), and STA Y (532) perform communication. However, this is only for convenience of explanation and can be equally applied to operations based on other devices or nodes. In the following, for convenience of explanation, the case in which AP (510), STA 1 (520), STA X (531), and STA Y (532) perform communication is described as the basis.

[0083] Referring to FIG. 5A, STA 1 (520) performs EDCA (Enhanced Distributed Channel Access) backoff, and can transmit a frame if the backoff is successful. That is, STA 1 (520) can occupy a channel based on the EDCA backoff procedure and perform frame transmission on the occupied channel. In the EDCA backoff procedure, EDCA Functions (EDCA Functions) associated with each AC (Access Category) (e.g., AC_VO EDCAF, AC_VI EDCAF, AC_BE EDCAF, AC_BK EDCAF) can determine a random backoff counter value and then decrease the backoff counter value. If the backoff counter value becomes 0 based on the decrease in the backoff counter value, EDCAF can perform frame transmission at the slot boundary of the slot where the backoff counter value becomes 0. Specifically, when the EDCAF of STA 1 (520) performs frame transmission based on the above, the EDCAF of STA 1 (520) may be granted an EDCA TXOP (transmit opportunity). That is, STA 1 (520) may be allocated a TXOP, and STA 1 (520) may initiate communication with other STAs to transmit and receive data within the transmission opportunity (TXOP) period (TXOP Duration) set within the determined TXOP limit. For example, the TXOP limit may be different for each AC, and AC_BK may be 2.258 ms, AC_BE may be 2.528 ms, AC_VI may be 4.096 ms, and AC_VO may be 2.080 ms. Here, the AP can transmit different TXOP limit values ​​based on broadcast, and STAs that receive the corresponding TXOP limit values ​​can use the received values.As another example, the TXOP limit value may be determined by individual settings of the AP and STA, but is not limited to the embodiment.

[0084] Referring to FIG. 5a, if STA 1 (520) succeeds in occupying a channel, the duration parameter in the header of the data to be transmitted (e.g., UL Data) may be set to the TXOP duration. For example, the TXOP duration in FIG. 5a may be set to TXOP (Original). Here, STA 1 (520) may allow another STA to use the TXOP within the set TXOP duration. The operation of allowing another STA to use the TXOP set by the STA may be a reverse direction transmission operation or reverse communication. For example, an STA that initiates reverse direction communication may be an RD initiator, and an STA that is assigned reverse communication may be an RD responder, but may not be limited to the names.

[0085] Referring to FIG. 5A, STA 1 (520) may allow reverse communication within the set TXOP. When STA 1 (520) allows reverse communication within the set TXOP, STA 1 (520) may transmit a frame (501) including an RDG (Reverse Direction Grant) indicator, an AC (Access Category) constraint indicator, and an AC of the transmitted data in the header to allow reverse communication. That is, the frame (501) transmitted by STA 1 (520) may be a frame that shares the TXOP with the AP. For example, the STA 1 (520) DL RDG indicator may indicate whether to allow an STA (eg, AP 1) receiving data within the TXOP period (eg, TXOP (Original)) to transmit data in the reverse direction. As a specific example, when RDG is 1, an STA (e.g., AP 1) receiving data within the TXOP period can transmit reverse data to another STA. On the other hand, when RDG is 0, an STA (e.g., AP 1) receiving data within the TXOP period cannot transmit reverse data to another STA.

[0086] When RDG is set to 1, the RD initiator can additionally transmit an RDGO (Reverse Direction Grant Others) indicator in the header. RDGO may be an indicator for target STAs that can transmit reverse data. When RDGO is 0, the RD responder can perform reverse data transmission only to the RD initiator. On the other hand, when RDGO is 1, the RD responder can perform data transmission to STAs other than the RD initiator. For example, when the RDGO indicator is not included in the above-described header, the RD responder can perform reverse data transmission only to the RD initiator. In other words, when the RDGO indicator is not included in the above-described header, the RD responder can operate in the same way as when RDGO is 0.

[0087] The AC Constraint indicator can indicate whether an STA sending data via reverse communication allows only data of the same AC type as the data transmitted by setting up an RDG. If the AC Constraint indicator is 1, an STA sending data via reverse communication can only transmit AC data of the same type as the data transmitted by setting up an RDG. On the other hand, if the AC Constraint indicator is 0, an STA sending data via reverse communication can transmit AC data of a different type than the data transmitted by setting up an RDG. In addition, if the AC Constraint indicator is 0, the header can be transmitted by additionally including a TXOP Extension Allowed indicator. The TXOP Extension Allowed indicator can indicate whether to allow the TXOP restriction extension when transmitting AC data of a different type. When the TXOP Extension Allowed indicator is 0, an STA that transmits AC data of a different type from the data transmitted by setting up an RDG can perform reverse transmission only within the initially set TXOP (TXOP (Original)). On the other hand, when the TXOP Extension Allowed indicator is 1, an STA that transmits AC data of a different type from the data transmitted by setting up an RDG can perform reverse transmission using a TXOP limit longer than the initially set TXOP (TXOP (Original)).

[0088] For example, the RDG indicator, the RDGO indicator, the AC Constraint indicator, and the TXOP Extension Allowed indicator can be 1-bit values. The RDG indicator, the RDGO indicator, the AC Constraint indicator, and the TXOP Extension Allowed indicator can be included in the subfield whose Control ID is CAS (command and status) as the A-control of the header. That is, the RDG indicator, the RDGO indicator, the AC Constraint indicator, and the TXOP Extension Allowed indicator can be included in the CAS A-Control and transmitted.

[0089] Additionally, for example, based on the communication procedure, the RDG indicator can also be used as a More PPDU (Physical Protocol Data Unit) indicator. An STA performing reverse communication as indicated by the RDG can request allocation of an additional reverse communication grant (RDG) by setting the More PPDU indicator to 1 if there is additional data to be transmitted after the currently transmitted data. Additionally, for a terminal that initially allowed the RDG, the RDG indicator of the last transmitted data is interpreted as a More PPDU indicator, and if set to 0, it can be used to mean that there is no additional data to be transmitted.

[0090] Referring to FIG. 5A, STA 1 (520) can transmit data by succeeding in channel competition (i.e., succeeding in the channel access procedure). Here, STA 1 (520) can set up reverse communication to AP 1 (510) within the set TXOP. If STA 1 (520) allows reverse communication to AP 1 (510), STA 1 (520) can set up an RDG in the data (501) frame to be transmitted before the time of allowing reverse communication and transmit it to AP 1 (510).

[0091] Also, as an example, STA 1 (520) can set the AC Constraint indicator to 1 to allow other types of AC transmission. For example, in FIG. 5a, STA 1 (520) can set the TXOP Extension Allowed indicator to 0 to allow other types of AC transmission but perform other types of AC transmission within the existing TXOP constraint (TXOP (Original)). That is, STA 1 (520) can set the TXOP Extension Allowed indicator to 0 to allow other types of AC transmission but not to allow TXOP constraint changes. Since AP 1 (510) has the TXOP Extension Allowed indicator as 0, it can perform reverse communication only within the TXOP (TXOP (Original)) set by STA 1.

[0092] For example, even if the TXOP limit of the AC that AP 1 (510) intends to transmit in reverse communication is shorter than the TXOP set by STA 1 (520), the reverse communication section is not reduced by the TXOP limit of the new AC, and can be set within the TXOP allowed by STA 1 (520).

[0093] When AP 1 (510) has a frame to transmit in reverse communication (e.g., a data frame), AP 1 (510) can transmit a BA (BlockAck) frame (502) as a response frame to the data frame (501) of STA 1 (520) with the MorePPDU indicator set to 1. Through this, AP 1 (510) can instruct STA 1 (520) to initiate reverse communication. For example, STA 1 (520) can allow AP 1 (510) to transmit a frame to another STA other than STA 1 (520) during the reverse communication section. That is, STA 1 (520) can transmit a data frame (501) to AP 1 (510) by setting the RDGO indicator to 1 together with the RDG indicator, and AP 1 (510) can perform frame transmission to another STA (e.g., STA X or STA Y) based on this. AP 1 (510) can transmit frames to other STAs (STA X or STA Y) within the reverse communication section and receive response frames thereto. When there are no more frames to transmit in the reverse communication section, AP 1 (510) can transmit the last frame (503) to be transmitted by setting the MorePPDU indicator of the frame to be transmitted to 0. Here, the duration set in the header of the last frame to be transmitted by AP 1 (510) can be set to the time until the BA for the last frame to be transmitted (503) is received. STA 1 (520) can receive and decode all data transmitted by AP 1 (510) in the reverse communication section even if the receiver address (RA) of the data is not STA 1 (520). Through this, STA 1 (520) can check the MorePPDU parameter (MorePPDU indicator) of the data transmitted by AP 1 (510), and can recognize that AP 1 (510) has terminated the reverse communication section by checking that the MorePPDU indicator is set to 0.More specifically, STA 1 (520) can recognize that AP 1 (510) terminates reverse communication after the time point of the duration of the frame header of the last frame (503) transmitted by AP 1 (510) in which More PPDU is set to 0. If the initially set TXOP remains after the above-described duration, STA 1 (520) can use the TXOP to transmit a frame to AP 1 (510) or another STA. For example, if STA 1 (520) has no frame to transmit to AP 1 (510) or another STA, STA 1 (520) can terminate the TXOP by transmitting a CF-END (contention free-END) frame.

[0094] Referring to FIG. 5b, STA 1 (520) can transmit data by succeeding in channel competition (i.e., succeeding in the channel access procedure). Here, STA 1 (520) can set up reverse communication to AP 1 (510) within the set TXOP. If STA 1 (520) allows reverse communication to AP 1 (510), STA 1 (520) can set up an RDG in a frame (501) to be transmitted before the time at which reverse communication is allowed and transmit it to AP 1 (510). That is, the frame (501) transmitted by STA 1 (520) can be a frame that shares the TXOP with the AP.

[0095] Also, as an example, STA 1 (520) can set the AC Constraint indicator to 1 to allow other types of AC transmission. As an example, FIG. 5b illustrates, differently from FIG. 5a, that STA 1 (520) can set the TXOP Extension Allowed indicator to 1 to allow other types of AC transmission and also to allow changing the changed TXOP constraint of the other types of AC transmission. That is, STA 1 (520) can allow other types of AC transmission and changing the TXOP constraint, and for this purpose, can set the TXOP Extension Allowed indicator to 1. Since AP 1 (510) has the TXOP Extension Allowed indicator as 1, it can apply a different TXOP constraint from the TXOP (TXOP (Original)) set by STA 1 (520).

[0096] Here, the TXOP limit change can be determined using the initially negotiated TXOP value or the predetermined TXOP value. As another example, the TXOP limit change can be determined according to the longest TXOP limit among the ACs of the data to be transmitted in the reverse communication section. When the initially negotiated TXOP value or the predetermined TXOP value is used, the section that can be used for reverse communication can be calculated by applying the negotiated TXOP value or the predetermined TXOP value from the time when the TXOP is initially set. Here, if the newly applied section is shorter than the reverse communication section allocated by STA 1 (520), the section used for reverse communication can be the reverse communication section allocated by STA 1 for reverse communication. As another example, the negotiated TXOP value or the predetermined TXOP value can be applied from the time when the reverse communication section is allocated, and reverse communication can be performed based on this.

[0097] Referring to FIG. 5b, the TXOP Extension Allowed indicator may be set to 1, thereby allowing AP 1 (510) to change the TXOP limit. If the TXOP limit corresponding to the AC of the frame to be transmitted by AP 1 (510) is longer than the TXOP (TXOP (Original), eg AC_VO TXOP) set by STA 1 (520), AP 1 (510) may perform reverse communication within the corresponding section by using the TXOP limit corresponding to the AC of the frame to be transmitted with a longer value (eg AC_VI TXOP). Here, the application of the new TXOP may be used by calculating the new TXOP limit section from the start time of the TXOP initially set by STA 1 (520).

[0098] As another example, the changed TXOP limit can be applied from the point in time when reverse communication is enabled. That is, the new TXOP can be used by determining the interval from which the new TXOP limit is applied, starting from the point in time when reverse communication is enabled.

[0099] As another example, if the TXOP limit of the AC that AP 1 (510) intends to transmit through reverse communication is shorter than the TXOP set by STA 1 (520), the reverse communication section is not reduced by the TXOP limit of the new AC, and can be used within the TXOP allowed by STA 1 (510). As another example, even if the TXOP limit of the AC that AP 1 (510) intends to transmit through reverse communication is shorter than the TXOP set by STA 1 (520), if the new TXOP starts from the time when reverse communication is allowed, the section may be determined by applying the new TXOP limit from the time when reverse communication is allowed (i.e., the new TXOP of AP 1 (510) may start anew from the time when reverse communication is allowed), but the present invention is not limited to this embodiment.

[0100] When there is a frame to be transmitted via reverse communication (e.g., data frame), AP 1 (510) can transmit a BA (BlockAck) frame (502) as a response frame to the data frame (501) of STA 1 (520) by setting the MorePPDU indicator to 1. Through this, AP 1 (510) can instruct STA 1 (520) to initiate reverse communication. For example, STA 1 (520) can allow AP 1 (510) to transmit a frame to another STA other than STA 1 (520) during the reverse communication section. That is, STA 1 (520) can transmit a data frame (501) to AP 1 (510) by setting the RDGO indicator to 1 together with the RDG indicator, and AP 1 (510) can perform frame transmission to another STA based on this. AP 1 (510) can transmit frames to other STAs (STA X (531) or STA Y (532)) within the reverse communication section and receive response frames thereto. When there are no more frames to transmit within the reverse communication section, AP 1 (510) can transmit the last frame (503) to be transmitted with the MorePPDU indicator set to 0.

[0101] Here, the duration set in the header of the last frame transmitted by AP 1 (510) can be set and transmitted until the time of receiving the BA for the last frame (503) transmitted. STA 1 (520) can receive and decode all data transmitted by AP 1 (510) in the reverse communication section even if the receiver address (RA) of the data is not STA 1 (520). Through this, STA 1 (520) can check the MorePPDU parameter of the data transmitted by AP 1 (510), and can recognize that AP 1 (510) has ended the reverse communication section by confirming that the MorePPDU indicator is set to 0. More specifically, STA 1 (520) can recognize that AP 1 (510) terminates reverse communication after the Duration time of the frame header of the last frame (503) transmitted by AP 1 (510) in which More PPDU is set to 0. If the initially set TXOP remains after the aforementioned Duration time, STA 1 (520) can use it to transmit a frame to AP 1 (510) or another STA. For example, if STA 1 (520) has no frame to transmit to AP 1 (510) or another STA, it can transmit a CF-END (contention free-END) frame to terminate the TXOP.

[0102] In the RD section described above, when AP 1 (510) selects STAs (e.g., STA 1, STA X, STA Y) to which frames are to be transmitted and extends the TXOP, a machine learning unit and a machine learning algorithm may be used based on FIGS. 3 and 4. As a specific example, AP 1 (510) can always receive BSR (buffer status report) from STAs and check queue information to be transmitted to STAs. That is, AP 1 (510) can recognize information on traffic to be received or transmitted from STAs. AP 1 (510) can use the traffic information as an input to a machine learning algorithm (e.g., Deep Reinforced Learning). That is, AP 1 can utilize the traffic information as a state obtained from the environment of the DRL algorithm. AP 1 (510) 'scheduling traffic to STAs' and 'extending the TXOP for reverse communication' can be considered actions of the DRL algorithm. Furthermore, AP 1 (510) may transmit more downlink frames to a specific STA or extend the TXOP for reverse communication.

[0103] AP 1 (510) can schedule frames to STAs and then collect traffic information from each of the STAs and AP 1. The collected traffic information of AP 1 can be considered a reward for the DRL algorithm, and AP 1 (510) can train an agent in a direction to maximize the reward. As a specific example, the reward may be appropriate scheduling of traffic, and the agent (i.e., the agent of the DRL algorithm) can perform learning based on this. Through the above, AP 1 (510) can perform optimal scheduling operations (e.g., selecting an optimal STA to perform scheduling and extending a reverse communication section) in the RD section.

[0104] FIGS. 6A to 6C are diagrams illustrating a method for recovering an RD section applied to the present disclosure. Referring to FIGS. 6A to 6C, an environment may be one in which AP 1 (610), STA 1 (620), STA X (630), and STA Y (640) operate in a wireless LAN network. Here, STA X (620) and STA Y (630) may be STAs different from STA 1 (620). However, FIGS. 6A to 6C are merely an example for the convenience of explanation and may not be limited to the corresponding situation.

[0105] STA 1 (620) performs EDCA (Enhanced Distributed Channel Access) backoff, and can transmit a frame if the backoff is successful. That is, STA 1 (620) can occupy a channel based on the EDCA backoff procedure and perform frame transmission on the occupied channel. In the EDCA backoff procedure, the EDCA Functions (EDCA Functions) associated with each AC (Access Category) (e.g., AC_VO EDCAF, AC_VI EDCAF, AC_BE EDCAF, AC_BK EDCAF) can determine a random backoff counter value and then decrease the backoff counter value. If the backoff counter value becomes 0 based on the decrease in the backoff counter value, the EDCAF can transmit a frame at the slot boundary of the slot where the backoff counter value becomes 0. When the EDCAF of STA 1 (620) decides to transmit a frame, the EDCAF of STA 1 (620) may be granted an EDCA TXOP (transmit opportunity). That is, STA 1 (620) may be allocated a TXOP, and STA 1 (620) may initiate communication with other STAs to transmit and receive data within the transmission opportunity (TXOP) period (TXOP Duration) within the set TXOP limit.

[0106] STA 1 (620) may transmit an uplink data frame (601) to AP 1 (610) in the first frame of TXOP. AP 1 (610) may respond to STA 1 (620) with a BA (BlockAck) frame. STA 1 (620) may transmit an uplink data frame (601) to AP 1 (610) again.

[0107] The uplink data frame (601) transmitted by STA 1 (620) may include at least one of an indicator indicating RD (e.g., RDG), an AC (Access category) constraint (AC constraint) indicator, and an RDGO (RDG Others) indicator indicating whether RD is allowed to another STA. For example, the indicator indicating RD may be included in the HT Control field included in the MAC header of the MPDUs (MAC Protocol Data Units) included in the uplink data frame (601) transmitted by STA 1 (620). The information included in the HT Control field may be A-Control information, which may be CAS (command and status) Control. The CAS Control may include an RDG / More PPDU bit. When STA 1 (620) indicates RD to AP 1 (610), the RDG / More PPDU bit may be set to 1. As another example, STA 1 (620) may transmit an RD indication to AP 1 (610) in a different form. For example, the RD indication may be indicated as a single or multiple indications and is not limited to a specific form. In addition, the RD indication from STA 1 (620) to AP 1 (610) may additionally include frame segmentation-related information (e.g., information for PPDU (PHY layer Protocol Data Unit) segmentation). For example, the frame segmentation-related information may be indicated in units of time. As a specific example, the frame segmentation-related information may be indicated in units of TU (time units), and 1 TU is 1024 us. The frame segmentation-related information indicated in units of TU may be a real number, but is not limited to the present embodiment.

[0108] As another example, the frame-related information may be indicated in units of the duration of the frame (e.g., in units of us, which are frame duration units of the MAC layer). As another example, the frame segmentation-related information may be indicated using the Duration / ID field of the MAC header included in the MPDU of the uplink data frame (602) that includes an indicator for indicating RD to AP 1 (610) to STA 1 (620). For example, the information previously included in the Duration / ID field may have a value of 0 when aSlotTime is 9 us (3600 Mod 9=0) based on 3600 us. Here, if the Duration / ID field value is 3599 us, which is the value obtained by excluding 1 us from the original Duration / ID field, the value may be 8 (3599 Mod 9=8). Here, STA 1 (620) may indicate the frame segmentation-related information by excluding a portion of time from the information that should be included in the existing Duration / ID field. That is, AP 1 (610) can obtain values ​​1 to 8 as frame division related information based on the remainder of 9 obtained through the above-described modulo operation from the Duration / ID field of 3592 to 3599 us. STA 1 (620) can indicate values ​​1 to 8 as frame division related information, and the length information of the frame division can be information previously set by STA 1 (620) and AP 1 (610) based on the values ​​1 to 8. However, the frame division related information can be indicated by a method other than the above-described method and is not limited to a specific form. Here, STA 1 (620) can indicate that the frame transmission interval of AP 1 (610) is a PIFS (Priority Inter-Frame Space) interval. The PIFS interval can be a longer time (for example, a longer time by aSlotTime) than the SIFS (Short Inter-Frame Space) interval.

[0109] Referring to FIG. 6A, AP 1 (610) may transmit a BA frame to STA 1 (620). In addition, the BA frame that AP 1 (610) transmits to STA 1 (620) may include an indicator for accepting or rejecting the RD indicated by STA 1. For example, the indicator for accepting or rejecting the RD may be a MorePPDU parameter (indicator). Specifically, when the MorePPDU indicator is 1, the RD may be accepted, and when the MorePPDU indicator is 0, the RD may be rejected. When AP 1 (610) accepts the RD indicated by STA 1 (620), AP 1 (610) may be granted an RD section within the TXOP of STA 1 (620). The RD section may be the reverse communication section as described above. Here, if the RDGO indicator is 1 in the uplink frame (601) transmitted by STA 1 (620), AP 1 (610) can perform frame transmission to another STA (STA X or STA Y) other than STA 1 (620) within the RD section. That is, AP 1 (610) can transmit at least one frame to at least one STA (eg STA 1, STA X, STA Y) within the RD section. In addition, AP 1 (610) can segment a frame (eg PPDU) according to information for frame segmentation in the RD section. For example, if AP 1 (610) needs to segment a PPDU in units of 500 us, the maximum length of frames transmitted by AP 1 (610) to STAs can be 500 us. In addition, if STA 1 (620) indicates the frame transmission interval of AP 1 as PIFS, the frames transmitted by AP 1 (610) may be separated and transmitted in PIFS units. If the frame transmission interval of AP 1 (610) becomes the PIFS interval, STA 1 (620) may occupy the medium in the RD section during the SIFS time, which is a shorter time than the PIFS, and may be able to perform an operation to recover the TXOP.

[0110] As a specific example, referring to FIG. 6A, the RD section of AP 1 (610) may be the same as the end time of the TXOP of STA 1 (620). That is, AP 1 (610) can use the medium until the TXOP of STA 1 (620) ends. Here, AP 1 (610) can transmit a frame to STA X (631). AP 1 (610) can divide the frame to be transmitted to STA X (631) into three parts based on the frame division related information indicated from STA 1 (620), and each of the divided frames can be transmitted at PIFS intervals. If AP 1 (610) continues to transmit without terminating the RD section, MorePPDU of the frame header transmitted by AP 1 (610) can be set to 1. On the other hand, when AP 1 (610) transmits the last frame of the segmented frame, MorePPDU of the frame header may be set to 0. Here, the response policy (Ack Policy) of the segmented frames may be set to BlockAck. When STA X (631) receives a frame in which the response policy (Ack Policy) is set to BlockAck, STA X (631) may record the reception status of the frame on the BlockAck scoreboard and may not respond to the frame.

[0111] For example, after AP 1 (610) transmits two frames to STA X (631), STA 1 (620) may transmit an RD recovery request frame (602) to AP 1 (610) SIFS after the end time of transmission of the second frame of AP 1 (610). The RD recovery request frame (602) may be a frame that STA 1 (620) transmits to end an RD section and use the remaining TXOP. The RD recovery request frame (602) may be any one of a Quality of Service (QoS) frame requesting RD recovery (e.g., a QoS Null frame indicated by RDG = 0), an action frame, and other frames. When AP 1 (610) receives an RD recovery request frame (6020) from STA 1 (620), AP 1 (610) may perform any one of the operations of Table 1 below.

[0112] [Table 1]

[0113]

[0114]

[0115] Specifically, when AP 1 (610) performs the first operation of Table 1, AP 1 (610) may transmit a QoS Null frame to STA X (631) after SIFS after receiving an RD recovery request frame (602). The transmitted QoS Null frame (603) may have the MorePPDU indicator set to 0, indicating that RD is terminated. STA X (631) may receive a frame whose Ack Policy is Implicit BAR from AP 1 (610), and accordingly transmit a BA frame to AP 1 (610) after SIFS time. As another example, AP 1 (610) may transmit a BAR (BlockAck Request) frame to STA X (631), and STA X (631) may transmit a BA frame (604) to AP 1 (610) based on the BAR frame. The BAR frame may be combined with a QoS Null frame (603) in the form of an A-MPDU, and the QoS Null frame (603) combined with the BAR frame may have a MorePPDU indicator set to 0. Since AP 1 (610) has received the RD recovery request frame (602), it may end the RD interval upon receiving the BA frame (604). Thereafter, the remaining TXOP interval may be used by STA 1 (610).

[0116] As another example, when AP 1 (610) performs the second operation in Table 1, AP 1 (610) may not transmit any more frames. STA 1 (620) may detect that the medium is idle for the PIFS time, and based on this, STA 1 (620) may use the remaining TXOP interval. STA 1 (620) may transmit more frames (e.g., UL Data frames) in the remaining TXOP interval. As described above, STA 1 (620) may obtain an opportunity to use the TXOP again even if the RD interval is assigned to AP 1 (610), and efficiency may be increased in situations where STA 1 (620) must transmit additional frames.

[0117] In addition, as an example, when AP 1 (610) determines target STAs (e.g. STA 1, STA X, STA Y) to which frames are to be transmitted in the RD section, the machine learning unit and machine learning algorithm of FIGS. 3 and 4 described above may be used. As a specific example, AP 1 (610) can always receive BSR (buffer status report) from STAs and check queue information to be transmitted to the STAs. That is, AP 1 (610) can recognize information on traffic to be received or transmitted from STAs. AP 1 (610) can use the traffic information as an input of a machine learning algorithm (e.g. Deep Reinforced Learning). That is, AP 1 (610) can utilize the traffic information as a state obtained from the environment of the DRL algorithm. AP 1 (610) 'scheduling traffic to STAs' may be regarded as an action of the DRL algorithm. Additionally, it may be an action for AP 1 (510) to transmit more downlink frames to a specific STA.

[0118] AP 1 (610) can schedule frames to STAs and then collect traffic information from each of the STAs and AP 1. The collected traffic information of AP 1 can be considered a reward for the DRL algorithm, and AP 1 (610) can train an agent to maximize the reward. As a specific example, the reward may be appropriate scheduling of traffic, and the agent (i.e., the agent of the DRL algorithm) can perform learning based on this. Through the above, AP 1 (610) can perform an optimal scheduling operation (e.g., selecting an optimal STA to perform scheduling) in the RD section.

[0119] FIG. 6b is a diagram illustrating an RD section recovery method applied to the present disclosure. Referring to FIG. 6b, the wireless LAN network may be an environment in which AP 1 (610), STA 1 (620), STA X (631), and STA Y (632) operate. Here, STA X (631) and STA Y (632) may be STAs different from STA 1 (620). In addition, FIG. 6b is only an example for convenience of explanation and may not be limited to the corresponding situation.

[0120] STA 1 (620) performs EDCA (Enhanced Distributed Channel Access) backoff, and can transmit a frame if the backoff is successful. That is, STA 1 (620) can occupy a channel based on the EDCA backoff procedure and perform frame transmission on the occupied channel. In the EDCA backoff procedure, the EDCA Functions (EDCA Functions) associated with each AC (Access Category) (e.g., AC_VO EDCAF, AC_VI EDCAF, AC_BE EDCAF, AC_BK EDCAF) can determine a random backoff counter value and then decrease the backoff counter value. If the backoff counter value becomes 0 based on the decrease in the backoff counter value, the EDCAF can transmit a frame at the slot boundary of the slot where the backoff counter value becomes 0. When the EDCAF of STA 1 (620) determines to transmit a frame, the EDCAF of STA 1 (620) may be granted an EDCA TXOP (transmit opportunity). That is, STA 1 (620) may be allocated a TXOP, and STA 1 (620) may initiate communication with other STAs within the transmission opportunity (TXOP) period (TXOP Duration) within the determined TXOP limit (TXOP limit) to transmit and receive data. STA 1 (620) may transmit an uplink data frame to AP 1 (610) in the first frame of the TXOP. AP 1 (610) may respond to STA 1 (620) with a BA (BlockAck) frame. STA 1 (620) may transmit an uplink data frame (601) back to AP 1 (610).

[0121] The uplink data frame (602) transmitted by STA 1 (620) may include at least one of an indicator indicating RD (e.g., RDG), an AC (Access category) constraint (AC constraint) indicator, and an RDGO (RDG Others) indicator indicating whether RD is allowed to another STA. For example, the indicator indicating RD may be included in the HT Control field included in the MAC header of the MPDUs (MAC Protocol Data Units) included in the uplink data frame (601) transmitted by STA 1 (620). The information included in the HT Control field may be A-Control information, which may be CAS (command and status) Control. The CAS Control may include an RDG / More PPDU bit. When STA 1 (620) indicates RD to AP 1 (610), the RDG / More PPDU bit may be set to 1. As another example, the form of the indicator that STA 1 (620) indicates to AP 1 (610) for RD may vary. For example, the indicator that indicates RD may be indicated as a single or multiple indicators and is not limited to a specific form. In addition, as an example, the indicator that STA 1 (620) indicates to AP 1 (610) for RD may additionally include frame segmentation-related information (e.g., information for PPDU (PHY layer Protocol Data Unit) segmentation). The frame segmentation-related information may be indicated in time units. As a specific example, the frame segmentation-related information may be indicated in TU (time unit) units, and 1 TU is 1024 us. The frame segmentation-related information indicated in TU units may be a real number, but is not limited to the present embodiment.

[0122] As another example, the frame-related information may be indicated in units of the duration of the frame (e.g., in units of us, which are frame duration units of the MAC layer). As another example, the frame segmentation-related information may be indicated using the Duration / ID field of the MAC header included in the MPDU of the uplink data frame (601) that includes an indicator for indicating RD to AP 1 (610) to STA 1 (620). For example, the information previously included in the Duration / ID field may have a value of 0 when the aSlotTime is 9 us (3600 Mod 9=0) based on 3600 us. Here, if the Duration / ID field value is 3599 us, which is the value obtained by excluding 1 us from the original Duration / ID field, the value may be 8 (3599 Mod 9=8). Here, STA 1 (620) may indicate the frame segmentation-related information by excluding a portion of time from the information that should be included in the existing Duration / ID field. That is, AP 1 (610) can obtain values ​​1 to 8, which are frame segmentation-related information, in a manner obtained based on the remainder of 9 through the above-described modulo operation from the Duration / ID field of 3592 to 3599 us. When STA 1 (620) indicates values ​​1 to 8, the length information of the frame segmentation may be information previously set by STA 1 (620) and AP 1 (610) according to the values ​​1 to 8.

[0123] However, frame segmentation-related information may be indicated in a method other than the above-described method and is not limited to a specific form. Here, STA 1 (620) may indicate that the frame transmission interval of AP 1 (610) is a PIFS interval. The PIFS interval may be a longer time than the SIFS interval.

[0124] AP 1 (610) can transmit a BA frame to STA 1 (620). In addition, the BA frame that AP 1 (610) transmits to STA 1 (620) can include an indicator for accepting or rejecting the RD indicated by STA 1. For example, the indicator for accepting or rejecting the RD can be a MorePPDU parameter (indicator). Specifically, when the MorePPDU indicator is 1, the RD is accepted, and when the MorePPDU indicator is 0, the RD is rejected. When AP 1 (610) accepts the RD indicated by STA 1 (620), AP 1 (610) can be assigned an RD section within the TXOP of STA 1 (620). The RD section can be the reverse communication section as described above. Here, if the RDGO indicator is 1 in the uplink frame (601) transmitted by STA 1 (620), AP 1 (610) can perform frame transmission to another STA other than STA 1 within the RD section. That is, AP 1 (610) can transmit at least one frame to at least one STA (e.g. STA 1, STA X, STA Y) within the RD section. In addition, AP 1 (610) can segment a frame (e.g. PPDU) according to information for frame segmentation in the RD section. For example, if AP 1 (610) needs to segment a PPDU in units of 500 us, the maximum length of frames transmitted by AP 1 (610) to STAs can be 500 us. In addition, if STA 1 (620) instructs AP 1 to have a frame transmission interval of PIFS, the frames transmitted by AP 1 (610) may be separated and transmitted in PIFS units. If the frame transmission interval of AP 1 (610) becomes a PIFS interval, STA 1 (620) may occupy the medium in the RD section during the SIFS time, which is a shorter time than PIFS, and may be capable of recovering the TXOP.

[0125] As a specific example, referring to FIG. 6B, the RD section of AP 1 (610) may be the same as the end time of the TXOP of STA 1 (620). That is, AP 1 (610) can use the medium until the end time of the TXOP of STA 1 (620). Here, AP 1 (610) can transmit a frame to STA X (631). AP 1 (610) can divide the frame to be transmitted to STA X (631) into two based on frame division related information indicated from STA 1 (620), and the divided frames can be transmitted at PIFS intervals. Here, the response policy (Ack Policy) of the first frame among the divided frames can be set to BlockAck. For example, the second frame among the segmented frames may be transmitted PIFS time after the end of transmission of the first frame, and the ack policy may be set to Implicit BAR. For example, if AP 1 (610) continues transmission without terminating the RD section, MorePPDU of the transmitted frame header may be set to 1. Accordingly, MorePPDU of the first frame and the second frame transmitted by AP 1 (610) to STA X (631) may be set to 1. If STA X (631) receives a frame in which the ack policy is set to BlockAck, STA X (631) may record the reception status of the frame on the BlockAck scoreboard and may not perform a ack response to the frame. On the other hand, if STA X (631) receives a frame (the second frame) in which the Ack Policy is set to Implicit BAR, STA X (631) can transmit a BA frame to AP 1 (610) after an SIFS time from the reception end time of the frame. That is, the interval between frames can be a PIFS time or an SIFS time based on the Ack Policy.For example, AP 1 (610) may transmit to another STA (e.g., STA Y) using the RD section after transmitting a data frame to STA X (631), and accordingly, the MorePPDU parameter of the second frame described above may be set to 1.

[0126] Referring to FIG. 6b, AP 1 (610) may transmit two frames to STA X (631) and then perform frame transmission to STA Y (632). For example, the frame that AP 1 (610) transmits to STA Y (632) may be divided into three, but this is only an example for convenience of explanation and may not be limited thereto.

[0127] After AP 1 (610) transmits two frames to STA X (631), AP 1 (610) can perform frame transmission to STA Y (632). The frame that AP 1 (610) transmits to STA Y (632) can be divided into three, and each divided frame can be transmitted at a PIFS interval. If AP 1 (610) continues to transmit without terminating the RD section, MorePPDU of the frame header transmitted by AP 1 (610) can be set to 1. On the other hand, if AP 1 (610) transmits the last frame of the divided frames, MorePPDU of the frame header can be set to 0.

[0128] For example, after AP 1 (610) transmits two frames to STA Y (632), STA 1 (620) may transmit an RD recovery request frame (602) to AP 1 (610) SIFS after the end time of transmission of the second frame of AP 1 (610). The RD recovery request frame (602) may be a frame that STA 1 (620) transmits to end an RD section and use the remaining TXOP. The RD recovery request frame (602) may be any one of a Quality of Service (QoS) frame requesting RD recovery (e.g., a QoS Null frame indicated by RDG = 0), an action frame, and other frames. When AP 1 (610) receives the RD recovery request frame (602) from STA 1 (620), AP 1 (610) may perform any one of the operations in Table 2 below.

[0129]

[0130] [Table 2]

[0131]

[0132]

[0133] When AP 1 (610) performs the first operation of Table 2, after receiving an RD recovery request frame (602), AP 1 (610) may transmit at least one of a QoS Null frame, a BAR frame (e.g., a BAR frame, a MU (multi user)-BAR frame), trigger frames, and a combination of the above frames (e.g., combining the above frames in the form of an A-MPDU) to at least one STA (e.g., STA X and STA Y) after SIFS, and may receive a BA frame from at least one STA. For example, when a frame transmitted by AP 1 (610) includes a More PPDU parameter, AP 1 (610) may set the MorePPDU indicator to 0 to indicate that RD is terminated. For example, AP 1 (610) may transmit a QoS Null frame (603) whose Ack Policy is Implicit BAR to STA Y (632). That is, STA Y (632) can receive a frame with an Ack Policy of Implicit BAR from AP 1 (610), and STA Y (632) can receive the frame and transmit a BA frame (604) to AP 1 (610) after an SIFS time. Since AP 1 (610) has received an RD recovery request frame (602) from STA 1 (620), AP 1 (610) can terminate the RD interval upon receiving the BA frame (604). Thereafter, STA 1 (620) can use the remaining TXOP interval.

[0134] As another example, when AP 1 (610) performs the second operation in Table 2, AP 1 (610) may not transmit any more frames. STA 1 (620) may detect that the medium is idle for the PIFS time, and based on this, the remaining TXOP interval may be used by STA 1 (620). STA 1 (620) may transmit more frames (e.g., UL Data frames) in the remaining TXOP interval. As described above, STA 1 (620) may obtain an opportunity to use the TXOP again even if the RD interval is assigned to AP 1 (610), and the efficiency may be increased in situations where STA 1 (620) needs to transmit additional frames.

[0135] In addition, as an example, if STA 1 (620) transmits an RD recovery request frame SIFS time after the end of frame transmission of AP 1 (610), a collision may occur when STA X (631) or STA Y (632) transmits a BA frame depending on the response policy (Ack Policy) of the frame transmitted by AP 1 (610). In order to prevent the above-described collision, STA 1 (620) may check the response policy (Ack Policy) included in the frame transmitted by the AP and may not transmit the RD recovery frame (602) if the response policy (Ack Policy) is set to implicit BAR. As another example, STA 1 (620) may not transmit the RD recovery frame (602) to prevent collision in other cases where a collision may occur based on the frame transmitted by the AP, but is not limited to the embodiment.

[0136] As another example, the Ack Policy of frames transmitted by AP 1 (610) may be restricted so as not to be set to implicit BAR within the RD period. That is, a collision may not occur due to other STAs transmitting BA frames after SIFS based on the frames transmitted by AP 1 (610). Accordingly, STA 1 (620) may transmit an RD recovery frame (602) after SIFS time after the end time of the frame transmitted by AP 1 (610). When AP 1 (610) receives the RD recovery frame, AP 1 (610) may transmit at least one of a QoS Null frame, a BAR frame (e.g., a BAR frame, a MU (multi user)-BAR frame), trigger frames, and a combination of the above frames (e.g., combining the above frames in the form of an A-MPDU and transmitting them) to at least one STA (e.g., STA X and STA Y), and may receive a BA frame from at least one STA.

[0137] In addition, as an example, when AP 1 (610) determines target STAs (e.g. STA 1, STA X, STA Y) to which frames are to be transmitted in the RD section, the machine learning unit and machine learning algorithm of FIGS. 3 and 4 described above may be used. As a specific example, AP 1 (610) can always receive BSR (buffer status report) from STAs and check queue information to be transmitted to the STAs. That is, AP 1 (610) can recognize information on traffic to be received or transmitted from STAs. AP 1 (610) can use the traffic information as an input of a machine learning algorithm (e.g. Deep Reinforced Learning). That is, AP 1 (610) can utilize the traffic information as a state obtained from the environment of the DRL algorithm. AP 1 (610) 'scheduling traffic to STAs' may be regarded as an action of the DRL algorithm. Additionally, it may be an action for AP 1 (610) to transmit more downlink frames to a specific STA.

[0138] FIG. 6C is a diagram illustrating an RD section recovery method applied to the present disclosure. Referring to FIG. 6C, the wireless LAN network may be an environment in which AP 1 (610), STA 1 (620), STA X (631), and STA Y (632) operate. Here, STA X (631) and STA Y (632) may be STAs different from STA 1 (620). In addition, FIG. 6C is merely an example for convenience of explanation and may not be limited to the situation.

[0139] STA 1 (620) performs EDCA (Enhanced Distributed Channel Access) backoff, and can transmit a frame if the backoff is successful. That is, STA 1 (620) can occupy a channel based on the EDCA backoff procedure and perform frame transmission on the occupied channel. In the EDCA backoff procedure, the EDCA Functions (EDCA Functions) associated with each AC (Access Category) (e.g., AC_VO EDCAF, AC_VI EDCAF, AC_BE EDCAF, AC_BK EDCAF) can determine a random backoff counter value and then decrease the backoff counter value. If the backoff counter value becomes 0 based on the decrease in the backoff counter value, the EDCAF can transmit a frame at the slot boundary of the slot where the backoff counter value becomes 0. When the EDCAF of STA 1 decides to transmit a frame, the EDCAF of STA 1 (620) may be granted an EDCA TXOP (transmit opportunity). That is, STA 1 (620) may be allocated a TXOP, and STA 1 (620) may initiate communication with other STAs and transmit data within the set transmission opportunity (TXOP) period (TXOP Duration) within the set TXOP limit.

[0140] STA 1 (620) may transmit an uplink data frame (701) to AP 1 (610) in the first frame of TXOP. AP 1 (710) may respond to STA 1 (720) with a BA (BlockAck) frame. STA 1 (620) may transmit an uplink data frame (601) to AP 1 (610) again.

[0141] The uplink data frame (601) transmitted by STA 1 (620) may include at least one of an indicator indicating RD (e.g., RDG), an AC (Access category) constraint (AC constraint) indicator, and an RDGO (RDG Others) indicator indicating whether RD is allowed to another STA. For example, the indicator indicating RD may be included in the HT Control field included in the MAC header of the MPDUs (MAC Protocol Data Units) included in the uplink data frame (601) transmitted by STA 1 (620). The information included in the HT Control field may be A-Control information, which may be CAS (command and status) Control. The CAS Control may include an RDG / More PPDU bit. When STA 1 (720) indicates RD to AP 1 (710), the RDG / More PPDU bit may be set to 1. As another example, the form of the directive that STA 1 (620) uses to instruct AP 1 (610) to perform RD may vary. For example, the directive that instructs RD may be instructed as a single or multiple directives, and is not limited to a specific form.

[0142] Additionally, the instruction that STA 1 (620) uses to instruct AP 1 (610) to perform RD may additionally include frame segmentation-related information (e.g., information for PPDU (PHY layer Protocol Data Unit) segmentation). For example, the frame segmentation-related information may be indicated in units of time. As a specific example, the frame segmentation-related information may be indicated in units of TU (time units), and 1 TU is 1024 us. The frame segmentation-related information indicated in units of TU may be a real number, but is not limited to the present embodiment.

[0143] As another example, the frame-related information may be indicated in units of the duration of the frame (e.g., in units of us, which are frame duration units of the MAC layer). As another example, the frame segmentation-related information may be indicated using the Duration / ID field of the MAC header included in the MPDU of the uplink data frame (601) that includes an indicator for indicating RD to AP 1 (610) to STA 1 (620). For example, the information previously included in the Duration / ID field may have a value of 0 when the aSlotTime is 9 us (3600 Mod 9=0) based on 3600 us. Here, if the Duration / ID field value is 3599 us, which is the value obtained by excluding 1 us from the original Duration / ID field, the value may be 8 (3599 Mod 9=8). Here, STA 1 (620) may indicate the frame segmentation-related information by excluding a portion of time from the information that should be included in the existing Duration / ID field. That is, AP 1 (610) can obtain the frame division related information values ​​1 to 8 in a manner obtained based on the remainder of 9 through the above-described modulo operation from the Duration / ID field of 3592 to 3599 us. When STA 1 (620) indicates the values ​​1 to 8, the length information of the frame division may be information previously set by STA 1 (620) and AP 1 (610) according to the values ​​1 to 8. However, the frame division related information may be indicated by a method other than the above-described method and is not limited to a specific form. Here, STA 1 (620) may indicate that the frame transmission interval of AP 1 (610) is a PIFS interval. The PIFS interval may be a longer time than the SIFS interval.

[0144] AP 1 (610) can transmit a BA frame to STA 1 (620). In addition, the BA frame that AP 1 (710) transmits to STA 1 (720) can include an indicator for accepting or rejecting the RD indicated by STA 1. For example, the indicator for accepting or rejecting the RD can be a MorePPDU parameter (indicator). Specifically, when the MorePPDU indicator is 1, the RD is accepted, and when the MorePPDU indicator is 0, the RD is rejected. When AP 1 (610) accepts the RD indicated by STA 1 (620), AP 1 (610) can be assigned an RD section within the TXOP of STA 1 (620). The RD section can be the reverse communication section as described above. Here, if the RDGO indicator is 1 in the uplink frame (601) transmitted by STA 1 (620), AP 1 (610) can perform frame transmission to another STA other than STA 1 within the RD section. That is, AP 1 (610) can transmit at least one frame to at least one STA (e.g. STA 1, STA X, STA Y) within the RD section. In addition, AP 1 (610) can segment a frame (e.g. PPDU) according to information for frame segmentation in the RD section. For example, if AP 1 (610) needs to segment a PPDU in units of 500 us, the maximum length of frames transmitted by AP 1 (610) to STAs can be 500 us. In addition, if STA 1 (620) instructs AP 1 to have a frame transmission interval of PIFS, the frames transmitted by AP 1 (610) may be separated and transmitted in PIFS units. If the frame transmission interval of AP 1 (610) becomes a PIFS interval, STA 1 may occupy the medium in the RD section during SIFS time, which is a shorter time than PIFS, and may be capable of recovering TXOP.

[0145] As a specific example, referring to FIG. 6c, the RD section of AP 1 (610) may be the same as the end time of the TXOP of STA 1 (620). That is, AP 1 (610) can use the medium until the TXOP of STA 1 (620) ends. Here, AP 1 (610) may transmit MU (multi-user) frames (e.g., MU PPDU) to STA X (631) and STA Y (632) in the RD section. The MU frame may be divided and transmitted according to frame division-related information indicated by STA 1 (620), and the transmission interval of the divided MU frames may be the PIFS time. If AP 1 (610) continues to transmit without terminating the RD section, MorePPDU of the transmitted frame header may be set to 1. On the other hand, when AP 1 (610) transmits the last frame of the segmented frame in the RD section, MorePPDU of the transmitted frame header may be set to 0.

[0146] For example, when AP 1 (610) transmits MU frames, STA 1 (620) may transmit an RD recovery request frame (605) in a SIFS time shorter than the PIFS interval, which is the interval between frames transmitted by AP 1 (610). The RD recovery request frame (605) may be a frame transmitted by STA 1 (620) to end an RD section and use the remaining TXOP. The RD recovery request frame (605) may be any one of a QoS frame requesting RD recovery (e.g., a QoS Null frame indicated by RDG = 0), an action frame, and other frames, and is not limited to a specific form. When AP 1 receives the RD recovery request frame, AP 1 (610) may perform any one of the operations of Table 3 below.

[0147] [Table 3]

[0148]

[0149]

[0150] When AP 1 (610) performs the first operation of Table 3, after receiving the RD recovery request frame (605), AP 1 (610) may transmit at least one of a QoS Null frame, a BAR frame (e.g., a BAR frame, a MU (multi user)-BAR frame), trigger frames, and a combination of the above frames (e.g., combining the above frames in the form of an A-MPDU) to at least one STA (e.g., STA X and STA Y) after SIFS, and may receive a BA frame from at least one STA. For example, when a frame transmitted by AP 1 (610) includes a More PPDU parameter, AP 1 (610) may set the MorePPDU indicator to 0 to indicate that RD is terminated. For example, when AP 1 (610) transmits an MU-BAR frame to STA X (631) and STA Y (632), the MU-BAR frame (606) may be a trigger frame. Here, the MU-BAR frame (606) may indicate a subchannel (e.g., OFDMA subchannel, resource unit) on which STA X (631) and STA Y (632) should transmit a BA frame (607). STA X (631) and STA Y (632) may transmit the BA frame (607) to AP 1 (610) after SIFS based on the subchannel information indicated in the MU-BAR frame (606) of AP 1 (610). When AP 1 (610) receives the BA frame (607), the RD interval may be terminated, and STA 1 (620) may reuse the remaining TXOP interval.

[0151] As another example, when AP 1 (610) performs the second operation in Table 3, AP 1 (610) may not transmit any more frames. STA 1 (620) may detect that the medium is idle for the PIFS time, and based on this, the remaining TXOP interval may be used by STA 1 (620). STA 1 (620) may transmit more frames (e.g., UL Data frames) in the remaining TXOP interval. As described above, STA 1 (620) may obtain an opportunity to use the TXOP again even if the RD interval is assigned to AP 1 (610), and the efficiency may be increased in situations where STA 1 (620) needs to transmit additional frames.

[0152] In addition, as an example, when AP 1 (610) determines target STAs (e.g. STA 1, STA X, STA Y) to which frames are to be transmitted in the RD section, the machine learning unit and machine learning algorithm of FIGS. 3 and 4 described above may be used. As a specific example, AP 1 (610) can always receive BSR (buffer status report) from STAs and check queue information to be transmitted to the STAs. That is, AP 1 (610) can recognize information on traffic to be received or transmitted from STAs. AP 1 (610) can use the traffic information as an input of a machine learning algorithm (e.g. Deep Reinforced Learning). That is, AP 1 (710) can utilize the traffic information as a state obtained from the environment of the DRL algorithm. AP 1 (610) 'scheduling traffic to STAs' may be regarded as an action of the DRL algorithm. In addition, the action may be for AP 1 (610) to transmit more downlink frames to a specific STA or trigger an uplink frame. In addition, as an example, AP 1 (610) may schedule frames to STAs and then collect traffic information from each of the STAs and AP 1 (610). The collected traffic information of AP 1 (610) may be considered as a reward for the DRL algorithm. AP 1 (610) may train its agent (i.e., the agent of the DRL algorithm) in a direction that maximizes the reward. As an example, the direction that maximizes the reward may be appropriately scheduling traffic, but may not be limited thereto. Through the above, AP 1 (610) may perform an optimal scheduling operation (e.g., selecting an optimal STA to perform scheduling and scheduling uplink frames) in the RD section.

[0153] FIG. 7a and FIG. 7b are diagrams showing a reverse transmission induction method of an STA applied to the present disclosure.

[0154] In a wireless LAN, an AP (710) can serve as a connection point for a wide-area network while communicating with multiple STAs in a one-to-many manner. Therefore, the AP (710) may require more transmission opportunities than non-AP STAs (720), but in a wireless LAN, both the AP (710) and non-AP STAs (720) may have equal channel access probabilities. Considering the above, balancing the downlink (DL) transmission volume of the AP (710) and the uplink (UL) transmission volume of the STAs by providing the AP (710) with more transmission opportunities than non-AP STAs (720) may help improve the overall performance of the network. Here, considering the above-described problem, the STAs can utilize the acquired transmission opportunity (TXOP) for reverse direction (RD, Reverse Direction) transmission by the AP (710) as DL, and a method for this is described below.

[0155] Referring to FIG. 7a, STA 1 (720) performs EDCA (Enhanced Distributed Channel Access) backoff, and can transmit a frame if the backoff is successful. That is, STA 2 (720) can occupy a channel based on the EDCA backoff procedure and perform frame transmission on the occupied channel. In the EDCA backoff procedure, EDCA Functions (EDCA Functions) associated with each AC (Access Category) (e.g., AC_VO EDCAF, AC_VI EDCAF, AC_BE EDCAF, AC_BK EDCAF) can determine a random backoff counter value and then decrease the backoff counter value. If the backoff counter value becomes 0 based on the decrease in the backoff counter value, the EDCAF can transmit a frame at the slot boundary of the slot where the backoff counter value becomes 0. When the EDCAF of STA 1 decides to transmit a frame, the EDCAF of STA 1 (620) may be granted an EDCA TXOP (transmit opportunity). That is, STA 1 (720) may be allocated a TXOP, and STA 1 (720) may initiate communication with other STAs to transmit and receive data within the set transmission opportunity (TXOP) period (TXOP Duration) within the set TXOP limit.

[0156] STA 1 (720) may transmit an uplink data frame to AP 1 (710) in the first frame of TXOP. AP 1 (710) may respond to STA 1 (720) with a BA (BlockAck) frame. STA 1 (720) may transmit an uplink data frame to AP 1 (710) again. Here, an indicator indicating RD may be included in the HT Control field included in the MAC header of MPDUs included in the uplink data frame transmitted by STA 1 (720). The information included in the HT Control field may be A-Control information, which may be CAS (command and status) Control. The CAS Control may include an RDG / More PPDU bit. STA 1 (710) may allow the communicating counterpart to use the configured transmission opportunity period, TXOP, which may be a reverse direction transmission operation or reverse communication. For example, an STA that initiates reverse direction communication may be an RD initiator, and an STA that is assigned reverse direction communication may be an RD responder. For example, STA 1 (720) may allow reverse direction communication within a configured TXOP. To allow reverse direction communication, the header of the data to be transmitted may include an RDG indicator, an AC Constraint indicator, and an AC of the data to be transmitted. The RDG indicator may indicate whether an STA (e.g., AP 1) that receives data within a TXOP period (e.g., TXOP (Original)) is allowed to transmit data in the reverse direction. As a specific example, when RDG is 1, an STA (e.g., AP 1) that receives data within the TXOP period may transmit reverse direction data to another STA. On the other hand, when RDG is 0, an STA (e.g., AP 1) that receives data within the TXOP period may transmit reverse data to another STA.AP 1) cannot transmit reverse data to other STAs.

[0157] When RDG is set to 1, the RD initiator can additionally transmit an RDGO (Reverse Direction Grant Others) indicator in the header. RDGO may be an indicator for target STAs that can transmit reverse data. When RDGO is 0, the RD responder can perform reverse data transmission only to the RD initiator. On the other hand, when RDGO is 1, the RD responder can perform data transmission to STAs other than the RD initiator. For example, when the RDGO indicator is not included in the above-described header, the RD responder can perform reverse data transmission only to the RD initiator. In other words, the RD responder can operate in the same way as when RDGO is 0.

[0158] The AC Constraint indicator can indicate whether an STA sending data via reverse communication only allows data of the same AC type as the data transmitted by setting up an RDG. If the AC Constraint indicator is 1, the STA sending data via reverse communication can only transmit AC data of the same type as the data transmitted by setting up an RDG. On the other hand, if the AC Constraint indicator is 0, the STA sending data via reverse communication can transmit AC data of a different type from the data transmitted by setting up an RDG. For example, if the AC Constraint indicator is 0, the STA sending data via reverse communication can perform data transmission of a different AC, and thus the TXOP limit of the different AC may be applied.

[0159] Here, STAs (RD terminals) that induce reverse transmission of the AP (710) can determine the reverse transmission method and specific operations through prior consultation with the AP (710). Specifically, RD terminals can become RD terminals through the RD Membership Negotiation process. RD membership negotiation can be performed through the exchange of separate action frames. As another example, RD membership negotiation can be performed in another association process and may not be limited to a specific form.

[0160] For example, RD membership negotiation may be a procedure in which an STA determines at least one of RD operation participation level information, time information for RD operation participation, and parameter information based on the RD operation. As a specific example, the time information for RD operation participation, which is information on the period of time for which RD operation participation is performed, may be an RD membership timer. For example, if an STA performs an RD operation again while the RD membership timer is in effect, the RD membership timer may be restarted. That is, the initially set RD membership timer value may be reset and restarted.

[0161] When RD membership negotiation is performed, it can be determined whether STAs participating in RD membership negotiations participate in RD operations mandatorily or optionally. For example, if STAs participate in RD operations mandatorily, the STAs can induce reverse transmission of the AP every time a condition for RD operations is met in the TXOPs it acquires. On the other hand, if STAs participate in RD operations optionally, the STAs can selectively perform RD operations for each TXOP it acquires. In addition, other parameter information included in the negotiation may include a flag bit indicating whether AC restrictions are considered in the RD operations performed after the negotiation. For example, if the flag bit is not included, STAs performing RD operations in the AP may apply a condition that does not restrict AC. As another example, a parameter included in the negotiation may indicate whether STAs participating in RD operations are allowed to access the channel with a different EDCA parameter set from other STAs. Here, if the STAs participating in the RD operation are allowed to access the channel with a different EDCA parameter set from other STAs by the corresponding parameter, the AP may transmit a separate EDCA parameter set for the SATs participating in the RD operation. In addition, the AP may transmit its own buffer status information (Buffer Status Report, BSR) to the STA. When the AP transmits its own BSR to the STA, the AP may transmit information indicating the time when the BSR information expires together with the BSR.

[0162] For example, in conventional wireless LANs, non-AP STAs are required to continuously transmit buffer status information (Buffer Status Reports (BSR)) in the QoS data frames they transmit. Therefore, it may be possible for the AP to continuously track the buffer status of non-AP STAs. On the other hand, the AP does not perform the operation of notifying non-AP STAs of BSRs for general DL data other than TIM (traffic indication map) information transmitted for the purpose of power saving. Therefore, STAs participating in RD operations cannot determine whether the AP requires reverse transmission. In addition, STAs participating in RD operations cannot recognize the amount of data required by the AP for RD transmission and the transmission time required for reverse transmission, which may reduce the efficiency of the RD operation.

[0163] Considering the above-described problems, the AP may transmit its BSR information by including it in a DL transmission frame. The BSR information may be transmitted by being included in the QoS Control field of all or specific QoS data (or Null) frames. As another example, the BSR information may be included in the A-Control field included in the header of the MAC frame. As another example, the AP may transmit the BSR information through a separate action frame. As another example, the AP may transmit the BSR information as a specific field in the preamble of the PPDU. As a specific example, when the AP transmits an MU PPDU to a DL MU, a condition may be added that the BSR information must be transmitted in the preamble of the MU PPDU transmitted to the DL MU, since STAs participating in the RD operation may not be able to receive the MAC frame. As another example, when an AP transmits an MU PPDU to a DL MU, the AP may transmit a BSR by allocating at least one RU (resource unit) as a broadcast AID, but may not be limited to that embodiment.

[0164] Here, the BSR information of the AP may include at least one of the total data size information existing in the AP's queue and the data size information for each AC. As another example, the BSR information of the AP may include information excluding the size of the buffered BU (buffer unit) transmitted to the STA during power saving. As an example, the BSR information of the AP may be size information of a specific unit (e.g., octet). In addition, whether or not the type of data included in the BSR information exists may be indicated through 1-bit indication information, and is not limited to a specific form.

[0165] For example, the AP's DL transmission may have different transmission lengths depending on the MCS allowed by the receiving STA. Therefore, the AP may transmit the time information required for DL ​​transmission as BSR information instead of the data size. As a specific example, the AP may include transmission time information for performing reverse transmission in the next RD transmission in the BSR and transmit it. As another example, the BSR may include information on the minimum time required for reverse transmission. Here, the above information may be AC-specific.

[0166] As a specific example, if an STA has negotiated to participate in the RD operation, the STA can collect as much BSR information as possible from the AP. Accordingly, the STA that has negotiated to participate in the RD operation can attempt to receive all frames that may include a BSR transmitted from the AP. For example, the STA performing the RD operation can check the reverse transmission related data of the AP (710) based on the most recent BSR of the AP that has been normally received. If the STA performing the RD operation determines that the reverse transmission related data of the AP exists, the STA performing the RD operation can perform the RD operation. On the other hand, if the AP does not meet the minimum time condition required for RD transmission, the STA performing the RD operation may not perform the RD operation.

[0167] In addition, if the application of AC limitation of RD is instructed during the negotiation process, the STA performing the RD operation can determine whether RD is possible based on the AC condition of the TXOP. For example, if the BSR information received by the STA (by AC) expires according to the timer condition, a condition may be added that the STA performing the RD operation does not perform the RD operation. For example, if it is possible for the STA performing the RD operation to transmit all data or transmission times specified in the BSR of the AP within the RD based on whether the AC limitation is applied, the STA performing the RD operation can set the length of the TXOP to the sum of the time required for all of its transmissions and the time required for all RD transmissions. As another example, all TXOPs that induce reverse transmission of the AP may always be set to the TXOP limitation value of the AC of the TXOP, but may not be limited to the embodiment.

[0168] FIG. 7B is a diagram illustrating a reverse transmission method applied to the present disclosure. Referring to FIG. 7B, if there are no more packets in the transmission queue in a post-backoff situation, the STA may not attempt to access the channel to acquire a TXOP while maintaining the backoff counter at 0. In other words, if there are no packets in the transmission queue after the backoff, the STA may not attempt to occupy the channel. However, as described above, the STA that performed the RD membership negotiation may attempt to access the channel to acquire a TXOP to induce the AP's RD transmission according to the AP's BSR information. For example, if the STA that performed the RD membership negotiation receives the AP's BSR information during the post-backoff process (for example, the backoff process performed after the queue corresponding to each AC is emptied of packets), the STA that performed the RD membership negotiation may perform the EDAC backoff operation even if there are no packets in its transmission queue. That is, an STA that has performed RD membership negotiation can perform an EDAC backoff operation by considering that there is data for transmission in its transmission queue.

[0169] Considering AC restrictions in RD membership, and when the AP transmits BSR information for RD per AC, the STA that performed RD membership negotiation can consider that data for transmission exists in the queue only for the AC corresponding to the RD transmission. Here, RD transmission may not be allowed only for the same AC as the AC of the TXOP. Since RD transmission may allow RD transmission of ACs higher than the AC of the TXOP, the same condition may be applied. As a specific example, the AP (710) may notify the STA that performed RD membership negotiation that RD data for AC_VI exists. Here, in case of the TXOP for AC_VI / BE / BK, AC_VI transmission of the AP (710) may be allowed, but in case of the TXOP for AC_VO, AC_VI transmission in the RD cannot be allowed. Therefore, an STA that has performed RD membership negotiation may perform backoff operations by considering that data exists in the transmission queue for AC_VI / BE / BK, but may not consider that data exists in the transmission queue for AC_VO.

[0170] For example, if an STA acquires BSR information of an AP through a TXOP from another STA or AP while the backoff counter remains at 0 due to no data in the transmission queue, the STA may consider that data exists in the transmission queue in the middle of the TXOP. In the above case, the STA may be highly likely to collide with other STAs in the same situation immediately after the end of the TXOP. Therefore, if the STA obtains BSR information of the AP (710) in the middle of the TXOP of another STA or AP while the STA maintains the backoff counter at 0, the STA may need to reset the backoff counter of the AC (for example, set the counter uniformly randomly among [0, CW]) when attempting to access the channel for reverse transmission. Alternatively, if the STA obtains BSR information of the AP (710) in the middle of the TXOP of another STA or AP while the STA maintains the backoff counter at 0, and the backoff counter is already a non-zero value, the STA does not need to reset the backoff counter.

[0171] Referring to FIG. 7b, when an STA that has performed RD membership negotiation acquires a TXOP for reverse transmission of an AP in a situation where there is no data to transmit, the STA that has performed RD membership negotiation may indicate reverse transmission through a QoS Null frame as the first frame of the TXOP excluding the RTS / CTS frame. Here, the conditions related to setting the TXOP length and applying the AC restriction may be applied in the same manner as in FIG. 7a and are not limited to a specific form. As described above, the operation of allowing STAs to participate in RD membership with AP 1 and the operation of allowing reverse transmission may be determined based on the machine learning unit and machine learning algorithm of FIGS. 3 and 4. For example, the STAs may receive a BSR (buffer status report) from the AP and determine whether the STAs should allow reverse transmission to the AP. The STAs may use the traffic information obtained from the BSR of the AP as input to a machine learning algorithm (e.g., Deep Reinforced Learning). That is, STAs can utilize the traffic information as a state obtained from the environment of the DRL algorithm. The STAs 'scheduling reverse transmission to the AP' can be considered an action of the DRL algorithm. In addition, the AP can perform reverse transmission of frames to STAs, and then the AP can transmit BSR to inform the STAs of the traffic information. The STAs collect the traffic information of the AP, and the collected traffic information can be considered as a reward of the DRL algorithm. The STAs can learn their agents (i.e., agents of the DRL algorithm) in a direction that maximizes the reward. Here, maximizing the reward can mean that traffic is scheduled appropriately, and the STAs can perform optimal RD operations with the AP (710).

[0172] FIG. 8 is a diagram illustrating a method for applying differentiated channel access parameters to an STA to induce reverse transmission of the STA applied to the present disclosure. Referring to FIG. 8, an STA may perform RD membership negotiation with an AP in the same or similar manner as in FIG. 7A and FIG. 7B. In the above-described case, the STA may share a preset RD membership timer with the AP. Here, an STA performing an RD operation to induce reverse transmission may contribute to the network by resolving the AP's DL data. Considering the above-described point, differentiated channel access parameters may be applied to an STA performing an RD operation. For example, in a wireless LAN, when an AP induces UL MU transmission to an STA, the STA participating in the UL MU transmission may access the channel with a lower probability by applying MU EDCA parameters. Here, when MU EDCA parameters are applied to an STA performing an RD operation, the AP's reverse transmission opportunity based on the STA performing the RD operation may be reduced. For example, the MU EDCA parameter may be a parameter that is more disadvantageous to channel access than the default EDCA parameter. Considering the above, the MU EDCA parameter may not be applied to an STA performing an RD operation.

[0173] As a specific example, if the conditions for applying MU EDCA parameters are met for an STA that has performed RD membership negotiation, the STA that has performed RD membership negotiation may be exempted from applying MU EDCA parameters or may have its application postponed for a preset timer period (i.e., RD ​​membership Timer). For example, the preset timer period may be set based on parameters exchanged during the RD membership negotiation process. For example, if the preset timer is applied, the STA that has performed RD membership negotiation may induce reverse transmission of the AP before the timer expires. In the above case, the STA may reset the timer value to an initial value and postpone the application of the MU EDCA parameters again. That is, the STA may restart with the timer value set in the RD membership negotiation. On the other hand, the STA may have to apply the MU EDCA parameters when the preset timer expires.

[0174] As another example, if the MU EDCA parameter is being applied to the STA, and the STA successfully induces reverse transmission of the AP, the MU EDCA parameter may be deactivated. In the above-described case, the MU EDCA parameter may be changed to the default EDCA parameter, and the backoff counter value may be reset while changed to the default EDCA parameter.

[0175] As another example, STAs that have performed RD membership can perform channel access based on a separate EDCA parameter set. For example, STAs may receive a separate EDCA parameter set during the RD membership negotiation process or receive a separate EDCA parameter set via a separate frame after the RD membership negotiation process is completed.

[0176] For example, when STAs participate in RD membership as an AP, EDCA parameters can be determined based on the machine learning unit and machine learning algorithm of FIGS. 3 and 4. The AP can utilize the network traffic situation (e.g., load factor, delay, packet error rate) as a state obtained from the environment of the DRL algorithm. The AP's selection of appropriate channel access parameters is considered an action of the DRL algorithm. STAs can communicate based on the channel access parameters selected by the AP, and the AP can then collect the network traffic situation. The collected traffic information can be considered a reward for the DRL algorithm. The AP can train its agent (i.e., the agent of the DRL algorithm) in a way that maximizes the reward. Here, the direction of maximizing the reward can mean that traffic is scheduled appropriately, and the AP can instruct the STAs participating in the RD membership on the optimal channel access parameters.

[0177] In addition, as an example, in a wireless LAN, an STA may support enhanced multi-link single-radio (EMLSR) operation, and an operation based on this may be required. FIG. 9 is a diagram illustrating a multi-link established between multi-link devices (MLDs) applied to the present disclosure. Referring to FIG. 9, an MLD may have one medium access control (MAC) address. For example, an MLD may refer to an AP MLD and / or a non-AP MLD. The MAC address of the MLD may be used in a multi-link setup procedure between a non-AP MLD and an AP MLD. The MAC address of the AP MLD may be different from the MAC address of the non-AP MLD. Access points associated with an AP MLD may have different MAC addresses, and station(s) associated with a non-AP MLD may have different MAC addresses. Access points within an AP MLD having different MAC addresses may be responsible for each link and may function as independent access points (APs).

[0178] Stations within a non-AP MLD with different MAC addresses can be responsible for each link and can act as independent stations (STAs). The non-AP MLD may also be referred to as a STA MLD. The MLD may support STR (simultaneous transmit and receive) operation. In this case, the MLD may perform a transmission operation on link 1 and a reception operation on link 2. An MLD supporting the STR operation may be referred to as an STR MLD (e.g., STR AP MLD, STR non-AP MLD). For example, a link may mean a channel or a band. An STA that does not support the STR operation may be referred to as an NSTR (non-STR) AP MLD or an NSTR non-AP MLD (or, an NSTR STA MLD), but is not limited to the embodiment.

[0179] MLD can transmit and receive frames on multiple links by using a non-continuous bandwidth expansion scheme (e.g., 80MHz + 80MHz). Multi-link operation can include multi-band transmission. AP MLD can include multiple access points, which can operate on different links. Each of the multiple access points can perform the function(s) of the lower MAC layer. Each of the multiple access points can be referred to as a "communication node" or a "subordinate entity." The communication node (i.e., AP) can operate under the control of a higher layer (or, the processor (110) illustrated in FIG. 1). Non-AP MLD can include multiple STAs, which can operate on different links. Each of the multiple STAs can be referred to as a "communication node" or a "subordinate entity." The communication node (i.e., STA) can operate under the control of a higher layer (or, the processor (110) illustrated in FIG. 1).

[0180] MLD can perform communications in multiple bands. For example, MLD can perform communications using a 40MHz bandwidth in the 2.4GHz band according to a channel expansion method (e.g., bandwidth expansion method) and can perform communications using a 160MHz bandwidth in the 5GHz band according to a channel expansion method. MLD can perform communications using a 160MHz bandwidth in the 5GHz band and a 160MHz bandwidth in the 6GHz band. One frequency band (e.g., one channel) used by MLD can be defined as one link. Alternatively, multiple links can be established in one frequency band used by MLD. For example, MLD can establish one link in the 2.4GHz band and two links in the 6GHz band. Each link can be referred to as a first link, a second link, a third link, etc. Alternatively, each link can be referred to as link 1, link 2, link 3, etc. The link number may be set by the access point, and an ID (identifier) ​​may be assigned to each link, but may not be limited to the embodiment.

[0181] An MLD (e.g., an AP MLD and / or a non-AP MLD) can establish multiple links by performing an access procedure and / or a negotiation procedure for multi-link operation. In the above-described case, the number of links and / or a link to be used among multiple links can be established. A non-AP MLD (e.g., an STA) can check information on a band that can be communicated with the AP MLD. In the negotiation procedure for multi-link operation between a non-AP MLD and an AP MLD, the non-AP MLD can establish one or more links among the links supported by the AP MLD to be used for multi-link operation. An STA (e.g., an IEEE 802.11a / b / g / n / ac / ax station) that does not support multi-link operation can be connected to one or more links among the multiple links supported by the AP MLD.

[0182] When the bandwidth gap between multiple links (e.g., the bandwidth gap between links 1 and 2 in the frequency domain) is sufficient, the MLD can perform the STR operation. For example, the MLD can transmit PPDU (PLCP (physical layer convergence procedure) protocol data unit) 1 using link 1 among the multiple links, and can receive PPDU 2 using link 2 among the multiple links. On the other hand, if the bandwidth gap between the multiple links is insufficient and the MLD performs the STR operation, in-device coexistence (IDC) interference, which is interference between the multiple links, may occur. Therefore, if the bandwidth gap between the multiple links is insufficient, the MLD may not be able to perform the STR operation. The link pair having the above-described interference relationship may be a Non Simultaneous Transmit and Receive (NSTR) limited link pair. Here, the MLD may be an NSTR AP MLD or an NSTR non-AP MLD.

[0183] For example, multiple links including link 1, link 2, and link 3 can be established between AP MLD and non-AP MLD 1. If the bandwidth gap between link 1 and link 3 is sufficient, AP MLD can perform STR operation using link 1 and link 3. That is, AP MLD can transmit frame using link 1 and receive frame using link 3. If the bandwidth gap between link 1 and link 2 is not sufficient, AP MLD may not perform STR operation using link 1 and link 2. If the bandwidth gap between link 2 and link 3 is not sufficient, AP MLD may not perform STR operation using link 2 and link 3.

[0184] Meanwhile, in a wireless LAN system, a negotiation procedure for multi-link operation may be performed during an access procedure between an STA and an AP. A device supporting multiple links (e.g., an AP, a STA) may be referred to as a multi-link device (MLD). An access point supporting multiple links may be referred to as an AP MLD, and an STA supporting multiple links may be referred to as a non-AP MLD or a STA MLD. The AP MLD may have a physical address (e.g., a MAC address) for each link. Here, the AP MLD may be implemented as if there were separate APs responsible for each link. Multiple APs may be managed within a single AP MLD. Therefore, coordination between multiple APs belonging to the same AP MLD may be possible. The STA MLD may have a physical address (e.g., a MAC address) for each link. The STA MLD may be implemented as if there were separate STAs responsible for each link. Multiple STAs may be managed within a single STA MLD. Therefore, coordination between multiple STAs belonging to the same STA MLD may be possible.

[0185] For example, AP1 of the AP MLD and STA1 of the STA MLD can each be in charge of a first link and can communicate using the first link. AP2 of the AP MLD and STA2 of the STA MLD can each be in charge of a second link and can communicate using the second link. STA2 can receive status change information about the first link from the second link. In this case, the STA MLD can collect information (e.g., status change information) received from each link and control an operation performed by STA1 based on the collected information.

[0186] Next, methods for transmitting and receiving data in a wireless LAN system will be described. Even if a method (e.g., transmitting or receiving a signal) performed by a first communication node among communication nodes is described, a corresponding second communication node can perform a method (e.g., receiving or transmitting a signal) corresponding to the method performed by the first communication node. That is, if an operation of an STA is described, an AP corresponding to it can perform an operation corresponding to the operation of the STA. Conversely, if an operation of an AP is described, an STA corresponding to it can perform an operation corresponding to the operation of the AP. For example, an operation of an STA can be interpreted as an operation of an STA MLD, and an operation of an STA MLD can be interpreted as an operation of an STA. In addition, an operation of an AP can be interpreted as an operation of an AP MLD, and an operation of an AP MLD can be interpreted as an operation of an AP.

[0187] FIG. 10 is a diagram illustrating a frame exchange method in an improved multi-link single radio operation of a wireless LAN to which the present disclosure is applied. Referring to FIG. 10, an AP MLD 1 operating in a first link (1010) may be referred to as AP 1, and an AP operating in a second link (1020) may be referred to as AP 2. An STA operating in a first link (1010) with STA MLD 1 may be referred to as STA 1, and an STA operating in a second link (1020) with STA MLD 1 may be referred to as STA 2. STA MLD 1 may be an Enhanced Multi-Link Single Radio (EMLSR) STA MLD. An EMLSR STA MLD may perform an EMLSR operation, and STA MLD 1 may perform an EMLSR operation in the first link (1010) and the second link (1020). STAs on each link of STA MLD 1 may be referred to as EMLSR STAs.

[0188] For example, STA 1, which is an STA operating on the first link (1010), may be referred to as an EMLSR STA. The EMLSR STA MLD may initiate or terminate the EMLSR operation or mode by exchanging EML Operating Mode Notification (OMN) frames with the AP MLD. Before the EMLSR mode is terminated or initiated, either STA 1 or STA 2 may perform normal transmission and reception operations and listening operations using one transceiver (e.g., radio) at a predetermined time. STA 1 and STA 2 cannot perform normal transmission and reception operations at the same time. When the EMLSR STA MLD initiates the EMLSR mode by exchanging EML OMN frames, the EMLSR mode operation may be performed on the EMLSR links negotiated with the AP MLD. EMLSR mode operation can be composed of an operation (e.g. Listening Operation) of listening to whether an Initial Control Frame, which is a frame in a specified format, is transmitted from the EMLSR links, and a normal transmission / reception operation (e.g. EMLSR Operation) of transitioning all receiving radios (e.g. receiving antennas) or transmitting / receiving radios (e.g. transmitting / receiving antennas) operating on other links to the link through which the Initial Control Frame was transmitted to receive frames transmitted from the AP MLD.

[0189] When the EMLSR STA MLD transmits to the AP MLD, it can transmit by transitioning all radios to one of the EMLSR links. STA 1 can perform normal transmission and reception operations and listening operations. STA 1 can transmit and receive all frames in normal transmission and reception operations. STA 1 can receive only frames in a predetermined format in the listening operation. The frame in the predetermined format may be an Initial Control Frame. The Initial Control Frame may be an MU-RTS trigger frame or a BSRP trigger frame. The MU-RTS trigger frame may also be referred to as an MU-RTS frame in the present disclosure. STA 2 belonging to (e.g. affiliated with) EMLSR STA MLD 1 can operate in a listening operation if the operation state of STA 1 is a listening operation. Here, if the operation state of STA 1 is a normal transmission and reception operation, it may be in a transmission and reception impossible state. STA 2 may be in a state of neither transmitting nor receiving during the time Tt required for STA 1 to transition from listening operation to normal transmitting and receiving operation or from normal transmitting and receiving operation to listening operation. The above-described change in operating state may be equally applied to STA 1 when STA 2 is in listening operation and normal transmitting and receiving operation.

[0190] For example, in the first link (1010), AP 1 may obtain a TXOP, which is a time period in which multiple frames can be transmitted, by performing a channel access operation (e.g., EDCA backoff operation). In the first link (1010), STA 1 may receive an initial control frame (e.g., MU-RTS trigger frame). The initial control frame may include padding bits and / or a padding field that increase the length of the frame in consideration of the radio switching time of STA 1. STA 1 may respond with a CTS frame after a SIFS time from the time of completion of reception of the initial control frame. At this time, STA 1 may wait for the Tw time. The Tw time is a time composed of 'aSIFSTime + aSlotTime + aRxPHYStartDelay'. aRxPHYStartDelay may be 20 μs.

[0191] Tw time is the next time in Table 5 after receiving the initial control frame.<Tw 조건 1> ,<Tw 조건 2> and<Tw 조건 3> It can start when one of the cases is satisfied.

[0192] In addition, if STA 1 starts Tw after the completion of reception of the initial control frame and the <listening> condition in Table 4 is met during the Tw time, it does not operate in normal transmission / reception operation, but switches to listening operation.

[0193] [Table 4]

[0194]

[0195]

[0196] In the <Listening> condition of Table 4, when the MAC layer of STA 1 receives the PHY-RXSTART.indication primitive from the PHY layer, it means that STA 1 has detected a frame being received. When the MAC layer of STA 1 transmits the PHY-TXSTART.request primitive to the PHY layer, and when the MAC layer of STA 1 receives the PHY-TXSTART.confirm primitive from the PHY layer, it may mean that STA 1 wants to start transmitting a frame.

[0197] STA 1 can receive an MU-RTS TXS (triggered TXOP sharing) trigger frame from AP 1 after SIFS. Therefore, the MAC layer of STA 1 can receive a PHY-RXSTART.indication from the PHY layer, which does not satisfy the <listening> condition and thus does not return to the listening operation but continues to perform normal transmission and reception operations. The MU-RTS TXS trigger frame is a frame that indicates that AP 1 shares the TXOP of AP 1 with STA 1. The MU-RTS TXS trigger frame includes the AID (association identifier) ​​of STA 1, the length of the allocated time in which STA 1 can transmit a data frame, and a TXS sharing mode indicator. When the TXS sharing mode indicator is set to 1, STA 1 can transmit frames only to the AP (e.g., AP 1) to which STA 1 is associated within the allocated time. When the TXS shared mode indicator is set to 2, STA 1 can transmit frames to AP 1 and other STAs (e.g., other STAs not associated with EMLSR STA MLD) within the allocated time. STA 1 can transmit a CTS frame after an SIFS time after receiving an MU-RTS TXS trigger frame. STA 1 checks whether the <listening> condition is satisfied for a time period Tw from the time when the transmission of the CTS frame is completed. If the <listening> condition is not satisfied for a time period Tw, STA 1 does not transition to the listening operation but continues to perform normal transmission and reception operations. STA 1 may transmit a data frame within the time allocated by AP 1 and may transmit the data frame after an SIFS time from the time when the transmission of the CTS frame is completed.

[0198] When the TXS shared mode indicator is 1, the data frame must be transmitted only to AP 1, and when the TXS shared mode indicator is 2, the data frame can be transmitted to AP 1 or another STA (e.g. STA 3). Therefore, when STA 1 initiates transmission of a data frame, since the MAC layer of STA 1 transmits the PHY-TXSTART.request primitive to the PHY layer within the Tw time, and the MAC layer of STA 1 receives the PHY-TXSTART.confirm primitive from the PHY layer, the <listening> condition is not satisfied, so STA 1 does not return to the listening operation but operates in the normal transmitting and receiving operation. The frame that STA 1 transmits to AP 1 can be transmitted with the Ack policy set to "No Ack" which does not request an immediate response, "Normal ACK" which requests an immediate response, or "Implicit BAR". For frames transmitted with "Normal ACK" or "Implicit BAR" setting, which request an immediate response, the STA corresponding to the receiver of the frame (e.g., AP 1 or another STA if the TXS shared mode indicator is 2) transmits a response frame, which is an immediate response, after a SIFS period after receiving the frame. The response frame can be a BlockAck frame or an Ack frame.

[0199] STA 1 receives an ACK or BlockAck, which is an immediate response. Since ACK or BlockAck is a frame that does not require an immediate response, receiving ACK or BlockAck<Tw 조건 2> Since it corresponds to "When a PPDU received from an AP or another STA includes a frame that does not require an immediate response, it starts at the time of completion of reception of the PPDU.", Tw starts at the time of completion of reception of a PPDU including ACK or BlockAck. In the case of "No Ack" that does not request an immediate response, STA 1 transmits to AP 1 a frame for which AP 1 does not need to transmit a response frame that is an immediate response. The response frame may be a BlockAck frame or an Ack frame. If STA 1 transmits to AP 1 a frame for which it does not need to transmit a response frame,<Tw 조건 3> Since "If the STA transmitted PPDU contains a frame that does not require an immediate response, the transmission of the PPDU starts at the completion time of the PPDU transmission." is satisfied, the Tw time is started after transmitting the frame to AP 1.

[0200] STA 1 may not expect to receive a response frame from AP 1, and STA 1 checks whether the <listening> condition is satisfied for Tw time from the time of completion of frame transmission. If the <listening> condition is not satisfied for Tw time, STA 1 does not transition to the listening operation but continues to perform normal transmission and reception operation. STA 1 may need to transmit an additional data frame in the time allocated by AP 1, and the additional data frame of STA 1 may be a frame that returns the allocated time to AP 1 in TXS mode 2 (e.g., a QoS data frame including a CAS control subfield or a QoS Null frame). The HT control field included in the MAC header of the additional data frame of STA 1 may include a CAS control subfield in the A-Control format. The CAS control subfield may include an RDG / More PPDU bit, and if this bit is set to 0, STA 1 returns the allocated time to AP 1. After transmitting the additional frame, STA 1 can no longer transmit frames from AP 1 during the allocated time. The additional data frames transmitted by STA 1 can be transmitted with the Ack policy set to No Ack. In other words, STA 1 transmits frames to AP 1 that AP 1 does not need to transmit a response frame for.

[0201] The response frame can be a BlockAck frame or an Ack frame. If STA 1 transmits a frame to AP 1 that does not require a response frame,<Tw 조건 3> Since "If the STA transmitted PPDU includes a frame that does not require an immediate response, it starts at the time of completion of transmission of the PPDU," the Tw time is started after transmitting the frame to AP 1. The frame that STA 1 transmits that does not need to transmit a response frame may be a frame that does not request an Ack (i.e., a response frame), such as an Action No Ack frame, in addition to a frame in which the Ack Policy is set to No Ack.

[0202] STA 1 may not expect to receive a response frame from AP 1, and STA 1 checks whether the <listening> condition is satisfied for a time period Tw from the time of completion of frame transmission. If STA 1 does not satisfy the <listening> condition, it does not operate in a listening operation and continues to perform normal transmission and reception operations. However, STA 1 may not want to transmit any more frames, so the STA 1 MAC layer may not transmit the PHY-TXSTART.request primitive, and the STA 1 MAC layer may not receive the PHY-TXSTART.confirm primitive from the PHY layer. AP 1 may not transmit a frame to STA 1, and thus the STA 1 MAC layer may not receive the PHY-RXSTART.indication primitive. Therefore, the <listening> condition is satisfied, and STA 1 and STA 2 can operate in a listening operation after a time period Tw has elapsed and a time period Tt has passed. Tt time is the time when STA MLD 1 linked to STA 1 switches the radio chain.

[0203] FIG. 11A and FIG. 11B are diagrams illustrating a frame exchange method in an improved multi-link single radio operation of a wireless LAN applied to the present disclosure. Referring to FIG. 11A and FIG. 11B, an AP MLD 1 operating in a first link (1110) may be referred to as AP 1, and an AP operating in a second link (1120) may be referred to as AP 2. An STA operating in a first link (1110) with STA MLD 1 may be referred to as STA 1, and an STA operating in a second link (1120) with STA MLD 1 may be referred to as STA 2. In addition, STA MLD 1 may be an Enhanced Multi-Link Single Radio (EMLSR) STA MLD.

[0204] The EMLSR STA MLD can perform the EMLSR operation, and STA MLD 1 is a first link (1110) and can perform the EMLSR operation in a second link (1120). STAs in each link of STA MLD 1 may be referred to as EMLSR STAs. For example, STA 1, which is an STA operating in the first link (1110), may be referred to as an EMLSR STA. The EMLSR STA MLD can initiate or terminate the EMLSR operation or mode by exchanging an EML Operating Mode Notification (OMN) frame with the AP MLD.

[0205] Before the EMLSR mode is terminated or initiated, either STA 1 or STA 2 can perform normal transmission / reception operations and listening operations using one transceiver (e.g. radio) at a predetermined time. Here, STA 1 and STA 2 cannot perform normal transmission / reception operations at the same time. When the EMLSR STA MLD initiates the EMLSR mode through an EML OMN frame exchange, the EMLSR mode operation can be performed on the EMLSR links negotiated with the AP MLD. The EMLSR mode operation consists of an operation of listening for transmission of an Initial Control Frame, which is a frame in a predetermined format, on the EMLSR links (e.g. Listening Operation), and a normal transmission / reception operation of transitioning all receiving radios (e.g. receiving antennas) or transmitting / receiving radios (e.g. transmitting / receiving antennas) operating on other links to the link on which the Initial Control Frame was transmitted, to receive frames transmitted from the AP MLD (e.g. EMLSR Operation).

[0206] When the EMLSR STA MLD transmits to the AP MLD, it can transmit by transitioning all radios to one of the EMLSR links. STA 1 can perform normal transmission and reception operations and listening operations. STA 1 can transmit and receive all frames in normal transmission and reception operations. STA 1 can receive only frames in a predetermined format in the listening operation. The frame in the predetermined format may be an Initial Control Frame. The Initial Control Frame may be an MU-RTS trigger frame or a BSRP trigger frame. The MU-RTS trigger frame may also be referred to as an MU-RTS frame in the present disclosure. STA 2 belonging to (e.g. affiliated with) EMLSR STA MLD 1 may operate in a listening operation if the operation state of STA 1 is a listening operation. If the operation state of STA 1 is a normal transmission and reception operation, it may be in a transmission and reception impossible state. STA 2 may be in a state of neither transmitting nor receiving during the time Tt required for STA 1 to transition from listening operation to normal transmitting and receiving operation or from normal transmitting and receiving operation to listening operation. The above-described change in operating state may be equally applied to STA 1 when STA 2 is in listening operation and normal transmitting and receiving operation.

[0207] In the first link, AP 1 may obtain a TXOP, which is a time period in which multiple frames can be transmitted, by performing a channel access operation (e.g., EDCA backoff operation). In the first link, STA 1 may receive an initial control frame (e.g., MU-RTS trigger frame). The initial control frame may include padding bits and / or a padding field to increase the length of the frame in consideration of the radio switching time of STA 1. STA 1 may respond with a CTS frame after a SIFS time from the time of completion of reception of the initial control frame. At this time, STA 1 may wait for the Tw time. The Tw time is a time composed of 'aSIFSTime + aSlotTime + aRxPHYStartDelay'. aRxPHYStartDelay may be 20 μs.

[0208] Tw time is the time after receiving the initial control frame as shown in Table 5 below.<Tw 조건 1> ,<Tw 조건 2> and<Tw 조건 3> It can be started when one of the cases is satisfied. For example, in the <listening> condition of Table 5, when the MAC layer of STA 1 receives the PHY-RXSTART.indication primitive from the PHY layer, it means that STA 1 has detected a frame being received. When the MAC layer of STA 1 transmits the PHY-TXSTART.request primitive to the PHY layer, and when the MAC layer of STA 1 receives the PHY-TXSTART.confirm primitive from the PHY layer, it means that STA 1 wants to start frame transmission.

[0209] [Table 5]

[0210]

[0211]

[0212] STA 1 can receive a trigger frame from AP 1 after SIFS. The trigger frame is a basic trigger frame. Therefore, the MAC layer of STA 1 can receive PHY-RXSTART.indication from the PHY layer, which does not satisfy the <listening> condition and thus does not return to the listening operation, but continues to perform normal transmission and reception operations. The trigger frame is a frame instructing AP 1 to allocate uplink resources to STA 1. The trigger frame includes the AID (association identifier) ​​of STA 1, the uplink length (uplink (UL) Length) at which STA 1 can transmit a data frame, and resource information (e.g., resource unit (RU) information, which is an orthogonal frequency division multiple access (OFDMA) resource) that STA 1 can transmit on the uplink. After receiving the trigger frame, an uplink data frame can be transmitted to AP 1 after SIFS.

[0213] The uplink data frame is transmitted in the UL TB (trigger based) PPDU (physical layer protocol data unit) format. The UL TB PPDU may be a response frame to the trigger frame of AP 1. At this time, the uplink data frame transmitted by STA 1 may be transmitted with the Ack policy set to "No Ack" that does not request an immediate response, "Normal ACK" that requests an immediate response, or "Implicit BAR". In the case of a frame transmitted with the Ack policy set to "Normal ACK" or "Implicit BAR" that requests an immediate response, the STA corresponding to the receiver of the frame (e.g., AP 1 or another STA when the TXS shared mode indicator is 2) transmits a response frame that is an immediate response after an SIFS time after receiving the frame.

[0214] The response frame can be a BlockAck frame or an Ack frame. STA 1 receives an ACK or BlockAck, which is an immediate response. Since an ACK or BlockAck is a frame that does not require an immediate response, receiving an ACK or BlockAck<Tw 조건 2> "If a PPDU received from an AP or another STA contains a frame that does not require an immediate response, it starts at the time of completion of reception of the PPDU." Therefore, Tw starts at the time of completion of reception of a PPDU containing ACK or BlockAck.

[0215] In the case of "No Ack" that does not request an immediate response, STA 1 transmits a frame to AP 1 that does not require AP 1 to transmit a response frame with an immediate response. The response frame can be a BlockAck frame or an Ack frame. If STA 1 transmits a frame to AP 1 that does not require a response frame,<Tw 조건 3> Since "If the PPDU transmitted by the STA includes a frame that does not require an immediate response, it starts at the time of completion of transmission of the PPDU," the Tw time is started after transmitting the frame to AP 1. The frame that does not need to transmit the response frame transmitted by the STA 1 may be a frame that does not request an Ack, such as an Action No Ack frame, in addition to a frame in which the Ack Policy is set to No Ack.

[0216] Referring to FIG. 11a, STA 1 checks whether the <listening> condition is satisfied for Tw time from the time of completion of transmission of the uplink data frame. The Ack Policy of the uplink data transmitted by STA 1 to AP 1 is set to No Ack and transmitted. In other words, STA 1 transmitted a frame that does not require an immediate response frame. Alternatively, the frame transmitted by STA 1 may be a frame that does not require a response frame, such as an Action No Ack frame. Therefore, if STA 1 transmits a frame that does not require a response frame to AP 1,<Tw 조건 3> Since "If the STA transmitted PPDU includes a frame that does not require an immediate response, it starts at the time of completion of transmission of the PPDU." is satisfied, the Tw time period is started after transmitting the frame to AP 1. If the <listening> condition is not satisfied during the Tw time period, STA 1 does not transition to the listening operation and continues to perform normal transmission and reception operations. STA 1 can receive an additional frame (e.g., data frame, trigger frame, etc.) from AP 1 after the SIFS time period from the time of completion of transmission of the uplink data frame. In this case, the MAC layer of STA 1 receives the PHY-RXSTART.indication primitive from the PHY layer. Therefore, STA 1 may not satisfy the <listening> condition within the Tw time period. Therefore, STA 1 can operate in normal transmission and reception operations without transitioning to the listening operation. Alternatively, STA 1 may not receive additional frames (e.g., data frames, trigger frames, etc.) from AP 1 after SIFS time from the completion time of transmission of an uplink data frame, and STA 1 may not transmit frames to AP 1. In this case, STA 1 satisfies the <listening> condition within Tw time.Therefore, STA 1 and STA 2 can operate by transitioning to the listening operation after the time Tw has elapsed and after the time Tt. The time Tt is the time when STA MLD 1 linked to STA 1 switches the radio chain.

[0217] Referring to FIG. 11b, AP 1 may have allocated uplink resources to other STAs in addition to STA 1 in the trigger frame. Therefore, after SIFS from the end of the trigger frame of AP 1, other STAs including STA 1 may transmit frames to AP 1 in UL OFDMA mode (i.e., multi-user mode). STA 1 checks whether the <listening> condition is satisfied for Tw time from the time of completion of transmission of the uplink data frame. The Ack Policy of the uplink data transmitted by STA 1 to AP 1 was set to No Ack and transmitted. In other words, STA 1 transmitted a frame that does not require an immediate response frame. Therefore, if STA 1 transmits a frame that does not require a response frame to AP 1,<Tw 조건 3> Since "If the STA transmitted PPDU includes a frame that does not require an immediate response, it starts at the time of completion of transmission of the PPDU," the Tw time is started after transmitting the frame to AP 1. At least one STA among the other STAs except STA 1 may have transmitted a frame requesting a response frame to the AP (e.g., a frame including a Normal Ack or an Implicit BAR Ack Policy).

[0218] STA 1 does not operate in the listening operation if the <listening> condition is not satisfied for the Tw time period, and continues to perform normal transmission and reception operations. AP 1 can transmit a response frame even if the Ack policy of the uplink data frame of STA 1 is set to No Ack or the uplink frame is a frame that does not require a response frame, such as an Action No Ack frame, because other STAs other than STA 1 have transmitted frames that require a response frame. The response frame can be transmitted SIFS time after the time when STA 1 and other STAs complete transmitting the uplink data frame. In this case, the MAC layer of STA 1 receives the PHY-RXSTART.indication primitive from the PHY layer. Therefore, STA 1 may not satisfy the <listening> condition within the Tw time period. Therefore, STA 1 can operate in the normal transmission and reception operation without transitioning to the listening operation. The response frame can be an Ack frame or a BlockAck frame.

[0219] FIG. 10, FIG. 11a, and FIG. 11b illustrate that the EMLSR operation of STA 1 may operate based on the machine learning unit and machine learning algorithm of FIG. 3 and FIG. 4. For example, a machine learning algorithm may be used to determine whether the PHY layer of STA 1 transmits a frame and whether a frame is received. The PHY layer of STA 1 may input a received signal to the machine learning unit to determine whether an EMLSR operation should be performed from the received signal. The machine learning unit may use the machine learning algorithm to determine whether the signal received at the PHY layer is a wireless LAN physical layer preamble conforming to the IEEE 802.11 standard. If the received signal is a wireless LAN physical layer preamble conforming to the IEEE 802.11 standard, the PHY layer of STA 1 may transmit a PHY-RXSTART.indication_ml primitive to the MAC layer. The PHY-RXSTART.indication_ml primitive can serve the same purpose as the PHY-RXSTART.indication primitive, but can be transmitted when the primitive is generated based on a machine learning unit or algorithm.

[0220] FIG. 12 is a flowchart illustrating an operation method of an AP performing reverse transmission in a wireless LAN applicable to the present disclosure. Referring to FIG. 12, the AP may receive a first frame indicating reverse communication permission from a first STA and reverse communication permission to an STA other than the first STA based on the reverse communication permission (S1210). For example, the first frame may be an uplink frame transmitted from the first STA to the AP, but is not limited thereto. The AP may determine a reverse communication period based on a TXOP of the first STA if the first frame indicates permission for reverse communication and, based on the permission for reverse communication, indicates permission for reverse communication to another STA other than the first STA. (S1220) The AP may transmit at least one frame to the second STA within the reverse communication period (S1230) and terminate the reverse communication when the last frame among the at least one frame to be transmitted to the second STA is transmitted or the reverse communication period expires. (S1240) As an example, the first STA may be an STA that permits reverse communication to the AP, and the second STA may be the first STA or another STA, and is not limited to a specific form. As an example, the AP may include at least one processor and a memory that stores instructions for causing a wireless user device to perform a specific operation by the at least one processor, and may perform the above-described operation based thereon.

[0221] In addition, as an example, the AP initiates reverse communication by transmitting a response frame including information indicating initiation of reverse communication to the first STA, and when the AP transmits at least one frame to a second STA different from the first STA based on an RDGO indicator, the at least one frame may include an indicator indicating whether a next transmission frame exists, and the last frame of the at least one frame may be identified based on the indicator indicating whether a next transmission frame exists. The AP may transmit the last frame including period information for receiving a response frame from the second STA in the frame header, and may terminate reverse communication based on the period information. Even if the receiver address of the last frame is not the first STA, the first STA may receive the last frame and identify whether the AP transmits the last frame and the end time of reverse communication based on the period information. If the TXOP of the first STA remains after the end time of reverse communication, the first STA may transmit a frame to another STA through the TXOP of the first STA.

[0222] In addition, as an example, if the AC restriction indicator permits data transmission having an AC different from the AC of the first STA data in reverse communication, and the TXOP extension grant indicator permits extension of the reverse communication period, the AP may determine the TXOP corresponding to the AC of the second frame as the reverse communication period if the TXOP corresponding to the AC of the second frame transmitted to the second STA is longer than the TXOP of the first STA. On the other hand, if the TXOP corresponding to the AC of the second frame transmitted to the second STA is shorter than the TXOP of the first STA, the TXOP of the first STA may be determined as the reverse communication period, as described above. In addition, as an example, the start time of the TXOP corresponding to the AC of the second frame may be determined as the start time of the TXOP of the first STA or the start time of reverse communication. Here, the second frame may be any frame and may not be limited to a specific form.

[0223] In addition, as an example, the first frame may further include frame segmentation-related information, and the AP may transmit at least one frame to the second STA according to a segmented frame length indicated based on the frame segmentation-related information. Here, at least one of the frames transmitted based on the segmented frame length may be transmitted at a Priority Inter-Frame Space (PIFS) interval that is longer than a short inter-frame space (SIFS). In addition, when the first STA transmits an RD recovery request frame to the AP, the reverse communication recovery request frame is transmitted after an SIFS time from the transmission end time of the second frame among the at least one frame, and when the AP receives the reverse communication recovery request frame, the AP may transmit a frame indicating to stop reverse communication to the second STA after the SIFS time or may immediately stop reverse communication.

[0224] In addition, the ack policy of the frame indicating the suspension of reverse communication is set to a ack request, and the second STA receiving the frame indicating the suspension of reverse communication transmits a ack frame for the frame indicating the suspension of reverse communication to the AP based on the ack policy after an SIFS time after receiving the frame indicating the suspension of reverse communication, and the AP can suspend reverse communication when it receives the ack frame for the frame indicating the suspension of reverse communication. In addition, when the AP transmits at least one multi-user (MU) frame to a plurality of STAs including the second STA according to a segmented frame length indicated based on frame segmentation-related information, when the AP receives a reverse communication recovery request frame, the AP can transmit an MU frame for indicating the suspension of reverse communication to the plurality of STAs including the second STA after an SIFS time or can immediately suspend reverse communication. Here, the MU frame can indicate subchannel information on which the plurality of STAs including the second STA will transmit a response frame to the MU frame.

[0225] In addition, the AP may perform a reverse communication membership negotiation procedure with at least one of the first STA or STAs capable of providing reverse communication, and determine a reverse communication STA based on the reverse communication membership negotiation procedure. For example, the reverse communication membership negotiation procedure may determine at least one of reverse operation participation level information indicating whether the reverse communication STA necessarily participates in the reverse communication operation, reverse operation participation time information indicating the membership status maintenance time of the reverse communication STA, and reverse communication-related parameters, which are as described above. In addition, the AP may transmit a buffer status report (BSR) including at least one of total data size information existing in the queue of the AP, data size information by AC, and transmission execution time information in reverse communication to the reverse communication STA determined based on the reverse communication negotiation procedure. A reverse communication STA determined based on a reverse communication negotiation procedure can perform an enhanced distributed channel access (EDCA) backoff operation for reverse communication use of an AP even if there are no packets in a transmission queue after the backoff. In addition, if a multi-user (MU) EDCA parameter is set to allow a reverse communication STA determined based on the reverse communication negotiation procedure to occupy a channel with a lower probability, the reverse communication STA may not apply the MU EDCA parameter or may apply a separate EDCA parameter for the reverse communication STA while the reverse communication membership status is maintained based on reverse operation participation time information.

[0226] FIG. 13 is a flowchart illustrating an operation method of an STA that permits reverse transmission in a wireless LAN applied to the present disclosure. The STA may transmit a first frame indicating reverse communication permission to an AP and reverse communication permission to another STA other than the STA based on the reverse communication permission. (S1310) Here, if the first frame indicates reverse communication permission, a reverse communication period may be determined at the AP based on the TXOP of the STA. The AP may transmit at least one frame to the STA or another STA described above within the reverse communication period, and may perform data transmission if the last frame among the at least one frame transmitted to the other STA is transmitted or if there is a remaining period of the TXOP of the STA after the reverse communication period expires and reverse communication is terminated. (S1320) Here, the STA may perform the above-described operation by including at least one processor and a memory that stores instructions for causing a wireless user device to perform a specific operation by the at least one processor.

[0227] For example, an AP initiates reverse communication by transmitting a response frame including information indicating the initiation of reverse communication to an STA, and when the AP transmits at least one frame to an STA different from the STA based on an RDGO indicator, at least one frame may include an indicator indicating whether a next transmission frame exists, and the last frame of the at least one frame may be identified based on the indicator indicating whether a next transmission frame exists. The AP may transmit the last frame including information on a period for receiving a response frame from another STA in the frame header, and may terminate reverse communication based on the period information. Even if the receiver address of the last frame is not an STA, the STA may receive the last frame and identify whether the AP transmits the last frame and the end time of reverse communication based on the period information. If the TXOP of the STA remains after the end time of reverse communication, the STA may transmit a frame to another STA through the TXOP of the STA, as described above.

[0228] In addition, as an example, if the AC limit indicator permits data transmission having an AC different from the AC of STA data in reverse communication, and the TXOP extension grant indicator permits extension of the reverse communication period, the AP may determine the TXOP corresponding to the AC of the second frame as the reverse communication period if the TXOP corresponding to the AC of the second frame transmitted to another STA is longer than the TXOP of the STA. On the other hand, if the TXOP corresponding to the AC of the second frame transmitted to another STA is shorter than the TXOP of the STA, the TXOP of the STA may be determined as the reverse communication period, as described above. In addition, as an example, the start time of the TXOP corresponding to the AC of the second frame may be determined as the start time of the TXOP of the STA or the start time of reverse communication. Here, the second frame may be any frame and may not be limited to a specific form.

[0229] In addition, as an example, the first frame may further include frame segmentation-related information, and the AP may transmit at least one frame to another STA according to a segmented frame length indicated based on the frame segmentation-related information. Here, at least one of the frames transmitted based on the segmented frame length may be transmitted at a Priority Inter-Frame Space (PIFS) interval that is longer than a short inter-frame space (SIFS). In addition, when the STA transmits an RD recovery request frame to the AP, the reverse communication recovery request frame is transmitted after an SIFS time from the transmission end time of the second frame among the at least one frame, and when the AP receives the reverse communication recovery request frame, the AP may transmit a frame instructing the STA to stop using reverse communication after the SIFS time or may immediately stop reverse communication.

[0230] In addition, the ack policy of the frame indicating the suspension of reverse communication is set to an ack request, and another STA receiving the frame indicating the suspension of reverse communication transmits a ack frame to the AP based on the ack policy after a SIFS time after receiving the frame indicating the suspension of reverse communication, and the AP can suspend reverse communication when it receives the ack frame to the frame indicating the suspension of reverse communication. In addition, when the AP transmits at least one multi-user (MU) frame to a plurality of STAs including other STAs according to a segmented frame length indicated based on frame segmentation-related information, when the AP receives a reverse communication recovery request frame, the AP can transmit an MU frame indicating the suspension of reverse communication to a plurality of STAs including other STAs after a SIFS time or can immediately suspend reverse communication. Here, the MU frame can indicate subchannel information on which the plurality of STAs including other STAs will transmit a response frame to the MU frame.

[0231] In addition, the AP may perform a reverse communication membership negotiation procedure with at least one of the STA or STAs capable of providing reverse communication, and determine a reverse communication STA based on the reverse communication membership negotiation procedure. For example, the reverse communication membership negotiation procedure may determine at least one of reverse operation participation level information indicating whether the reverse communication STA necessarily participates in the reverse communication operation, reverse operation participation time information indicating the membership status maintenance time of the reverse communication STA, and reverse communication-related parameters, which are as described above. In addition, the AP may transmit a buffer status report (BSR) including at least one of total data size information existing in the queue of the AP, data size information by AC, and transmission execution time information in reverse communication to the reverse communication STA determined based on the reverse communication negotiation procedure. A reverse communication STA determined based on a reverse communication negotiation procedure can perform an enhanced distributed channel access (EDCA) backoff operation for reverse communication use of an AP even if there are no packets in a transmission queue after the backoff. In addition, if a multi-user (MU) EDCA parameter is set to allow a reverse communication STA determined based on the reverse communication negotiation procedure to occupy a channel with a lower probability, the reverse communication STA may not apply the MU EDCA parameter or may apply a separate EDCA parameter for the reverse communication STA while the reverse communication membership status is maintained based on reverse operation participation time information.

[0232] 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., either singly 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 computer software art.

[0233] Examples of computer-readable media 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 hardware devices described above may be configured to operate with at least one software module to perform the operations of the present disclosure, and vice versa.

[0234] 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.

[0235]

[0236] The above may also apply to other systems.

Claims

1. In the operation method of an access point (AP) in a wireless LAN system, A step of receiving a first frame indicating permission for reverse communication from a first station (STA); A step of determining a reverse communication period based on a transmission opportunity (TXOP) of the first STA when the first frame indicates permission for the reverse communication; A step of transmitting at least one frame to a second STA within the above reverse communication period; and An operating method of an AP, comprising the step of performing transmission of the last frame among the at least one frame transmitted to the second STA or terminating the reverse communication when the reverse communication period expires.

2. In paragraph 1, The first frame includes a reverse direction grant (RDG) indicating whether reverse communication is permitted, an AC restriction indicator indicating whether the access category (AC) of data is restricted, and an AC of the first STA data. If the RDG indicates permission for the reverse communication, it further includes a reverse direction grant others (RDGO) indicator indicating whether data transmission is possible to other STAs other than the first STA that allows the reverse communication. An operating method of an AP, further comprising a TXOP extension grant indicator indicating whether the reverse communication period can be extended, when the AC restriction indicator permits data transmission having an AC different from the AC of the first STA data in the reverse communication.

3. In paragraph 1, The AP initiates the reverse communication by transmitting a response frame including information indicating the initiation of the reverse communication to the first STA, An AP operation method, wherein when the AP transmits the at least one frame to the second STA different from the first STA based on the RDGO indicator, the at least one frame includes a next transmission frame presence indicator, and the last frame among the at least one frame is verified based on the next transmission frame presence indicator.

4. In paragraph 3, The AP transmits the frame header of the last frame including the period information for receiving the response frame from the second STA, and terminates the reverse communication based on the period information. The last frame is received by the first STA with a different receiver address of the last frame, and indicates whether the AP transmits the last frame and the end point of the reverse communication based on the duration information, An AP operation method in which frame transmission by the first STA is performed through the TXOP of the first STA when the TXOP of the first STA remains after the termination point of the above reverse communication.

5. In paragraph 2, If the AC restriction indicator permits data transmission having an AC different from the AC of the first STA data in the reverse communication, and the TXOP extension grant indicator permits extension of the reverse communication period, the AP determines the TXOP corresponding to the AC of the second frame transmitted to the second STA as the reverse communication period if the TXOP corresponding to the AC of the second frame is longer than the TXOP of the first STA, An AP operation method, wherein if a TXOP corresponding to the AC of the second frame transmitted to the second STA is shorter than the TXOP of the first STA, the TXOP of the first STA is determined as the reverse communication period.

6. In paragraph 5, An AP operation method, wherein the start time of the TXOP corresponding to the AC of the second frame is determined as the start time of the TXOP of the first STA or the start time of the reverse communication.

7. In paragraph 1, The first frame further includes frame division related information, and the AP transmits at least one frame to the second STA according to a divided frame length indicated based on the frame division related information. An operation method of an AP, wherein at least one of the frames transmitted based on the divided frame length is transmitted at a PIFS (Priority Inter-Frame Space) interval that is longer than a SIFS (short inter-frame space).

8. In paragraph 7, When the AP receives a reverse recovery request frame from the first STA, the reverse communication recovery request frame is received after the SIFS time from the end time of transmission of the second frame among the at least one frame, An AP operation method in which, upon receiving the reverse communication recovery request frame, the AP transmits a frame instructing the second STA to stop using reverse communication after the SIFS time or immediately stops the reverse communication.

9. In paragraph 8, The ack policy of the frame indicating the suspension of the use of the reverse communication is set to a response request, and a response frame to the frame indicating the suspension of the use of the reverse communication based on the ack policy is received after the SIFS time after receiving the frame indicating the suspension of the use of the reverse communication from the second STA that receives the frame indicating the suspension of the use of the reverse communication. An operating method of an AP, wherein the AP stops the reverse communication when it receives the response frame to the frame instructing to stop the reverse communication.

10. In paragraph 9, When the AP transmits at least one multi-user (MU) frame to a plurality of STAs including the second STA according to a segmented frame length indicated based on the frame segmentation-related information, when the AP receives the reverse communication recovery request frame, it transmits an MU frame indicating to stop the reverse communication to the plurality of STAs including the second STA after the SIFS time or immediately stops the reverse communication. An AP operating method, wherein the MU frame indicates subchannel information on which the plurality of STAs including the second STA are to transmit a response frame to the MU frame.

11. In paragraph 1, An operating method of an AP, wherein the AP performs a reverse communication membership negotiation procedure with at least one of the first STA or STAs capable of providing reverse communication, and determines a reverse communication STA based on the reverse communication membership negotiation procedure, wherein the reverse communication membership negotiation procedure determines at least one of reverse operation participation level information indicating whether the reverse communication STA necessarily participates in reverse communication operation, reverse operation participation time information indicating a membership status maintenance time of the reverse communication STA, and reverse communication-related parameters.

12. In paragraph 11, An AP operation method, wherein the AP transmits a buffer status report (BSR) including at least one of total data size information existing in the AP's queue, data size information by AC, and transmission execution time information in the reverse communication to the reverse communication STA determined based on the reverse communication negotiation procedure.

13. In paragraph 12, An operating method of an AP, wherein an EDCA (enhanced distributed channel access) backoff operation is performed by the STA for use of the reverse communication of the AP even when there is no packet in the transmission queue after the backoff of the reverse communication STA determined based on the reverse communication negotiation procedure.

14. In paragraph 13, An AP operation method, wherein, when a MU (multi user) EDCA parameter is set to allow a reverse communication STA determined based on the reverse communication negotiation procedure to occupy a channel with a lower probability, the MU EDCA parameter is not applied to the reverse communication STA or a separate EDCA parameter for the reverse communication STA is applied while the reverse communication membership status is maintained based on the reverse operation participation time information.

15. For wireless user devices, at least one processor; and A memory storing instructions that cause the wireless user device to perform a specific operation by the at least one processor, The above specific actions are: Receive a first frame indicating permission for reverse communication from a first station (STA), If the first frame indicates permission for the reverse communication, the reverse communication period is determined based on the transmission opportunity (TXOP) of the first STA, Transmitting at least one frame to the second STA within the above reverse communication period, and A wireless user device that terminates the reverse communication when the last frame transmission of the at least one frame transmitted to the second STA is performed or when the reverse communication period expires.

16. In the operation method of a station (STA) in a wireless LAN system, A step of transmitting a first frame including a reverse direction grant (RDG) indicating whether reverse communication is permitted to an access point (AP); and Including a step of transmitting data when the data transmission enablement condition is satisfied; The reverse communication indicator transmitted to the AP is used by the AP to determine reverse communication based on the transmission opportunity (TXOP) of the STA. A method of operating an STA, characterized in that the above data transmission possible condition is that the last frame transmission of at least one frame is performed by the AP or the period of the reverse communication expires and the reverse communication is terminated.

17. For wireless user devices, at least one processor; and A memory storing instructions that cause the wireless user device to perform a specific operation by the at least one processor, The above specific actions are: Transmitting a first frame including a reverse direction grant (RDG) indicating whether reverse communication is permitted to an access point (AP), and When the conditions for data transmission are met, data is transmitted. The reverse communication indicator transmitted to the AP is used by the AP to determine reverse communication based on the transmission opportunity (TXOP) of the wireless user device. A wireless user device, characterized in that the above data transmission possible condition is that the last frame transmission of at least one frame is performed by the AP or the period of the reverse communication expires and the reverse communication is terminated.

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