Method and apparatus for preventing hidden node in low-latency channel access operation of wireless LAN

Abstract

In a wireless LAN system, an STA may confirm that a channel transitions from an occupied state to an idle state and remains in the idle state for a first preset time, wherein the STA may: carry out channel access through P-EDCA; transmit a DS after the first preset time, wherein the DS is a DS CTS frame, and a duration field of the DS CTS frame is set to a maximum allowable time of the channel access operation; after the DS is transmitted, carry out a backoff procedure on the basis of the channel access operation; and carry out frame transmission at a slot boundary at which a backoff counter reaches 0.

Description

Method and device for preventing hidden nodes in low-latency channel access operation of wireless LAN

[0001] The present disclosure relates to a method and apparatus for preventing hidden node problems when performing low-latency channel access in a wireless local area network (WLAN).

[0002]

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

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

[0005] As applications requiring higher reliability emerge, the IEEE 802.11bn standard, an Ultra High Reliability (UHR) wireless LAN technology, is being developed for single Basic Service Set (BSS) environments and / or redundant BSS environments. The goal of the IEEE 802.11bn standard may be to support improved data transmission speeds, enhanced latency performance, and reduced data error rates. Additionally, the IEEE 802.11bn standard can support low-power operation, peer-to-peer communication, and operations designed to increase channel utilization. It can also support a TXOP sharing method, where wireless LAN terminals share communication resources (transmit opportunities) between access points (APs). Furthermore, to increase the efficiency of communication resource utilization, the wireless LAN standard can support non-primary channel access (NPCA), which involves using a channel other than the primary channel when the primary channel is occupied. Furthermore, to increase the efficiency of communication resource utilization, wireless LAN standards can support dynamic subchannel operation (DSO), a method in which an AP can identify wireless LAN terminals within its BSS that support only an operating bandwidth narrower than that of the AP, and allocate a portion of the operating bandwidth to a subchannel (DSO channel) rather than the primary channel used for channel access to enable simultaneous transmission. Additionally, wireless LAN standards can support a high-priority channel access method that performs channel access preferentially for low-latency frame transmission. However, using the high-priority channel access method may lead to hidden node issues, and the following describes measures to address this.

[0006] Meanwhile, the technology forming the background of the invention is written to enhance understanding of the background of the invention and may include content that is not prior art already known to a person with ordinary knowledge in the field to which this technology belongs.

[0007]

[0008] The present disclosure relates to a method and apparatus for preventing hidden node problems when performing low-latency channel access in a wireless local area network (WLAN).

[0009] The present disclosure relates to a method and apparatus for preventing hidden node problems when performing a high-priority channel access method in a wireless LAN.

[0010] The present disclosure relates to a method and apparatus for transmitting feedback on a high-priority channel access signal to prevent frame transmission collisions due to a hidden node problem when performing a high-priority channel access method in a wireless LAN.

[0011] The present disclosure relates to a method and apparatus for increasing the low-latency performance of a wireless LAN by preventing frame collisions when performing a high-priority channel access method in a wireless LAN.

[0012] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below.

[0013]

[0014] According to one embodiment of the present specification, a method of operation of a station (STA) in a wireless LAN system may include the step of the STA confirming that the channel is switched from an occupied state to an idle state and that the channel is in an idle state for a first predetermined time, the step of the STA performing channel access through P-EDCA (prioritized enhanced distributed channel access), and the step of transmitting a DS (defer signal) after the first predetermined time, wherein the DS is a DS-CTS (clear to send) frame, the DS-CTS frame includes a MAC (medium access control) header, the duration field of the MAC header is set to the maximum allowable time for channel access operation, and the step of performing a backoff procedure based on the channel access operation after DS transmission, and performing frame transmission at the slot boundary where the backoff counter reaches 0.

[0015] Additionally, according to one embodiment of the present specification, a station (STA) in a wireless LAN system comprises at least one transceiver for transmitting and receiving signals, at least one processor for controlling at least one transceiver, and a memory for storing instructions that cause a non-AP STA to perform a specific operation by at least one processor, wherein the specific operation is: confirming that the channel is switched from an occupied state to an idle state and that the channel is in an idle state for a first predetermined time, wherein the STA performs channel access through P-EDCA (prioritized enhanced distributed channel access), and transmits a DS (defer signal) after the first predetermined time, wherein the DS is a DS CTS (clear to send) frame, the DS CTS frame includes a MAC (medium access control) header, and the duration field of the MAC header is set to the maximum allowable time for the channel access operation, and, after the DS transmission, performs a backoff procedure based on the channel access operation, and can perform frame transmission at the slot boundary where the backoff counter reaches 0.

[0016] In addition, the following points may apply in common.

[0017] According to one embodiment of the present specification, at least one STA receiving a DS-CTS frame may have a network allocation vector (NAV) based on the duration field of the DS-CTS frame set.

[0018] Additionally, according to one embodiment of the present specification, the maximum allowable time for a channel access operation set in the duration field of a DS CTS frame is a time set based on the sum of aSIFSTime and N*aSlotTime, and N can be determined based on P-EDCA related parameters and the maximum value of the P-EDCA competition window.

[0019] Additionally, according to one embodiment of the present specification, the P-EDCA related parameter is the P-EDCA AIFSN (arbitration interframe space number), and the P-EDCA contention window maximum value may be a value determined based on the P-EDCA CWmax parameter.

[0020] Additionally, according to one embodiment of the present specification, the backoff counter may be selected within a competition window determined based on the P-EDCA CWmax parameter, which is the maximum value of the P-EDCA competition window, and the P-EDCA CWmin, which is the minimum value of the P-EDCA competition window.

[0021] Additionally, according to one embodiment of the present specification, the first set time may be determined based on P-EDCA related parameters.

[0022] In addition, according to one embodiment of the present specification, when P-EDCA is used in a basic service set (BSS) that includes STA, P-EDCA related parameters may be determined based on at least one of basic parameter values ​​and modified parameter values.

[0023] Additionally, according to one embodiment of the present specification, the first set time is an AIFS (arbitration interframe space) associated with DS transmission, the AIFS is a time set based on the sum of aSIFSTime and M*aSlotTime, and M can be determined based on at least one of a basic parameter value and a change parameter value.

[0024] Additionally, according to one embodiment of the present specification, the STA transmits the DS and, after receiving a feedback frame from another STA, performs a backoff procedure based on a channel access operation, and can perform frame transmission at the slot boundary where the backoff counter reaches 0.

[0025] Additionally, according to one embodiment of the present specification, DS may be an RTS (request to send) frame, and the feedback frame may be a CTS frame.

[0026] Additionally, according to one embodiment of the present specification, the STA may be a non-AP STA or an AP STA.

[0027] In addition, according to one embodiment of the present specification, the SCRAMBLER_INITIAL_VALUE value set for the DS-CTS frame is a pre-set value, and the SCRAMBLER_INITIAL_VALUE value can be used identically in at least one STA including the STA.

[0028] Additionally, according to one embodiment of the present specification, DS-CTS frames transmitted from at least one STA including STA may be transmitted simultaneously based on the SCRAMBLER_INITIAL_VALUE value.

[0029] In addition, according to one embodiment of the present specification, a DS-CTS frame transmitted from at least one STA including STA may have a physical protocol data unit (PPDU) with identical content based on SCRAMBLER_INITIAL_VALUE with a preset value.

[0030]

[0031] According to the present disclosure, a method can be provided to prevent hidden node problems when performing low-latency channel access in a wireless LAN.

[0032] According to the present disclosure, a method to prevent hidden node problems when performing a high-priority channel access method in a wireless LAN can be provided.

[0033] According to the present disclosure, a method for transmitting feedback on a high-priority channel access signal can be provided to prevent frame transmission collisions due to a hidden node problem when performing a high-priority channel access method in a wireless LAN.

[0034] According to the present disclosure, a method can be provided to increase the low-latency performance of a wireless LAN by preventing frame collisions when performing a high-priority channel access method in a wireless LAN.

[0035] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below.

[0036] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0037]

[0038] FIG. 1 is a diagram showing a communication node within a wireless LAN system to which the present disclosure applies.

[0039] FIG. 2 is a drawing showing a wireless LAN system to which the present disclosure is applied.

[0040] FIG. 3 is a diagram illustrating a method for indicating P-EDCA and channel access parameters when using Priority Enhanced Distributed Channel Access (P-EDCA) for wireless LANs applicable to the present disclosure.

[0041] FIG. 4 is a diagram showing a hidden node prevention method when using wireless LAN P-EDCA applied to the present disclosure.

[0042] FIG. 5 is a diagram showing a hidden node prevention method when using wireless LAN P-EDCA applied to the present disclosure.

[0043] FIG. 6 is a diagram illustrating a hidden node prevention method when using wireless LAN P-EDCA applied to the present disclosure.

[0044] FIG. 7 is a flowchart illustrating the operation of an STA in a wireless LAN to which the present disclosure applies.

[0045]

[0046] The present disclosure is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present disclosure to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present disclosure.

[0047] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0048] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0049] The terms used in this disclosure are used merely to describe specific embodiments and are not intended to limit this disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this disclosure, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0050] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this disclosure pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this disclosure.

[0051] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding of the present disclosure, the same reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0052] Below, a wireless communication system to which embodiments according to the present disclosure are applied will be described. The wireless communication system to which embodiments according to the present disclosure are applied is not limited to the details described below, and embodiments according to the present disclosure may be applied to various wireless communication systems. The wireless communication system may be referred to as a "wireless communication network."

[0053] FIG. 1 is a diagram showing a communication node within a wireless LAN system to which the present disclosure applies. Referring to FIG. 1, the communication node (100) may include at least one of a processor (110), memory (120), a transceiver (130), an input / output interface (140), a storage device (150), and a bus (160). For example, the communication node (100) may be an access point (AP), a station (STA), an access point multi-link device (MLD), or a non-AP MLD. However, the communication node may not be limited thereto and may be a node that performs communication with another node or device based on the configuration described above. For example, the operating channel bandwidth supported by the AP may be 20 MHz (megahertz), 80 MHz, 160 MHz, etc. The operating channel bandwidth supported by the station may be 20 MHz, 80 MHz, etc. However, it may not be limited thereto.

[0054] A processor (110) within a communication node (100) can control at least one of a memory (120), a transceiver (130), an input / output interface (140), and a storage device (150) for each component within the communication node. The memory (120) within the communication node (100) can store information regarding commands and instructions executed by the processor (110), and the transceiver (130) may refer to a transceiver, an RF (radio frequency) unit, an RF module, or other components that perform signal transmission and reception. The input / output interface (140) within the communication node (100) is an interface for input and output that can be linked with other interfaces and may further include a separate storage device (150). Each component within the communication node (100) can communicate with one another by being connected by a bus (160).

[0055] However, as an example, each component included in the communication node (100) may be connected via an individual interface or an individual bus centered on the processor (110), rather than via a common bus (160). The processor (1110) may also be connected via a dedicated interface to at least one of the memory (120), the transmission / reception device (130), the input / output interface device (140), and the storage device (150).

[0056] A processor (110) can execute a program command stored in at least one of a memory (120) or a storage device (150). The processor (110) may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present disclosure are performed. Each of the memory (120) and the storage device (150) may be composed of at least one of a volatile storage medium or a non-volatile storage medium. e.g., the memory (120) may be composed of at least one of read-only memory (ROM) or random access memory (RAM).

[0057] In the following, the relevant operations are described based on the wireless LAN terminal as a station (STA). In accordance with the terminology usage according to IEEE 802.11, STA can refer to both AP STAs operating as access points (APs) and non-AP STAs operating in connection with an AP. However, for the convenience of explanation, APs and non-AP STAs are distinguished below; this distinction is merely for convenience of explanation, and it is self-evident that operations regarding an AP can be applied to both AP STAs and non-AP STAs. Furthermore, it is self-evident that the non-AP STA operations described below can also be applied to both non-AP STAs and AP STAs.

[0058] FIG. 2 is a diagram illustrating a wireless LAN system to which the present disclosure applies. Referring to FIG. 2, the basic service set (BSS) of the wireless LAN system may include one AP (210) and a plurality of non-AP STAs (221, 222, 223, 224), and the plurality of non-AP STAs (221, 222, 223, 224) may be controlled by the AP (210). However, the wireless LAN system is not limited to a BSS, and an environment consisting only of non-AP STAs without a fixed service set or AP may also be considered, and is not limited to a specific form. Each wireless device within the wireless LAN system may include a MAC (medium access control) layer and a physical (PHY) layer, and communication between wireless devices may be performed. For convenience of explanation, the following description focuses on the AP and non-AP STA, but is not limited thereto. For example, the following items may apply equally to other communication nodes or devices and are not limited to a specific form.

[0059] The following describes a method for using feedback to prevent hidden node issues when performing high-priority channel access. This prevents frame collisions and increases the low-latency performance of the wireless LAN.

[0060] FIG. 3 is a diagram illustrating a method for indicating P-EDCA and channel access parameters when using Priority Enhanced Distributed Channel Access (P-EDCA) for wireless LANs applicable to the present disclosure.

[0061] Referring to FIG. 3, an AP (310) and a plurality of STAs connected to the AP (310) (e.g., non-AP STA 1 (320), non-AP STA 2 (330), non-AP STA 2 (340)) may operate in a wireless LAN network. The AP (310) and the plurality of STAs connected to the AP (310) may form a basic service set (BSS). Here, the AP (310) may instruct the use of high-priority P-EDCA within the BSS. The AP (310) may include and transmit P-EDCA usage instruction information in a beacon or probe response frame to convey instruction information regarding P-EDCA usage to all STAs connected to the AP (310). As another example, P-EDCA may also be performed by individual STAs without instruction from the AP (310) and is not limited to a specific form.

[0062] When STAs using P-EDCA perform channel access using P-EDCA, the STAs using P-EDCA can perform the following P-EDCA channel access operations.

[0063]

[0064] [P-EDCA Channel Access Operation]

[0065] Step 1: Verify that the medium is not in a busy state for AIFS[P-EDCA] hours since the last detected busy (physical CS (carrier sense), virtual CS).

[0066] A. AIFS(arbitration inter frame space)[P-EDCA] may be identical to DIFS(DCF(distributed coordinated function) IFS). Alternatively, AIFS[P-EDCA] may be identical to AIFS[VO]. Alternatively, the time length of AIFS[P-EDCA] may be selected each time during the P-EDCA channel access operation. In the above case, AIFS[P-EDCA] may be set by selecting either the same time length as AIFS[VO] or a different time length at the start of the P-EDCA channel access operation (i.e., at the start of Step 1). For example, the different time length described above may be set to a time longer than AIFS[VO] by N multiples of aSlotTime (N is an integer greater than or equal to 1).

[0067]

[0068] Step 2: In Step 1, if the medium is not in a occupied state (i.e., in an idle state), transmit a DS (defer signal).

[0069] A. A Defer Signal can be a frame such as a CTS (clear to send) frame or an RTS (request to send) frame. If the Defer Signal is a CTS frame, it may be referred to as DS-CTS.

[0070] i. If the Defer Signal is a CTS frame or an RTS frame, the CTS frame and the RTS frame may be frames whose format and content are defined in advance so that frames of the same format and content can be transmitted simultaneously from multiple STAs without collisions. Meanwhile, the CTS frame and the RTS frame are MAC frames and may have a MAC header. The MAC header may include a duration field, and the duration field may be a field indicating the remaining time related to the exchange or transmission of the frame. In the above case, the Duration field of the Defer Signal may be 1) a time interval from the time of completion of transmission of the Defer Signal until the time of completion of the maximum allowable time of the channel access operation defined in Step 3. Or 2) a time obtained by subtracting 'aSIFSTime + AIFSN[i] x (aSlotTime)' from the time of completion of transmission of the Defer Signal until the time of completion of the maximum allowable time of the channel access operation defined in Step 3. Here, AIFSN[i] is the smallest AIFSN[i] value in the EDCA parameter set of the BSS. Or 3) it may be the time obtained by subtracting 'aSIFSTime + (AIFSN[i]-1) x (aSlotTime)' from the completion time of the maximum allowed time of the channel access operation defined in Step 3, starting from the completion time of the Defer Signal transmission. Here, AIFSN[i] is the smallest AIFSN[i] value in the EDCA parameter set of the BSS. Or 4) it may be the time obtained by subtracting 'aSIFSTime + 2 x (aSlotTime)' from the completion time of the maximum allowed time of the channel access operation defined in Step 3, starting from the completion time of the Defer Signal transmission. Here, AIFSN[i] is the smallest AIFSN[i] value in the EDCA parameter set of the BSS.Or 5) it may be the time obtained by subtracting 'aSIFSTime + aSlotTime' from the completion time of the maximum allowable time for the channel access operation defined in Step 3, starting from the time the Defer Signal transmission is completed. Here, AIFSN[i] is the smallest AIFSN[i] value in the EDCA Parameter set of the corresponding BSS. The duration field of the Defer Signal (i.e., the duration field of the MAC header) may be used to temporarily suspend transmission by STAs that do not perform P-EDCA operations. Specifically, STAs that do not perform P-EDCA operations receiving the Defer Signal may set a Network Allocation Vector (NAV) based on the time interval information indicated in the duration field of the Defer Signal's MAC header. When the NAV is set, STAs that do not perform P-EDCA operations detect the medium as busy. STAs that perform P-EDCA operations perform channel access operations within the NAV interval.

[0071] B. Alternatively, the Defer Signal may be a signal in which only the PHY Preamble exists. The PHY Preamble may also be a signal in which the format and content are defined in advance so that the same format and content can be transmitted without collision. In the above case, if the TXOP_DURATION field exists in the Defer Signal, the value may be 1) the time interval from the time the Defer Signal is completed until the time of completion of the maximum allowable time of the channel access operation defined in Step 3. Or, 2) the time obtained by subtracting 'aSIFSTime + AIFSN[i] x (aSlotTime)' from the time the Defer Signal is completed until the time of completion of the maximum allowable time of the channel access operation defined in Step 3. Here, AIFSN[i] is the smallest AIFSN[i] value in the EDCA Parameter set of the corresponding BSS. Or, 3) it may be the time obtained by subtracting 'aSIFSTime + (AIFSN[i]-1) x (aSlotTime)' from the completion time of the maximum allowable time of the channel access operation defined in Step 3, starting from the completion time of the Defer Signal transmission. Here, AIFSN[i] is the smallest AIFSN[i] value in the EDCA Parameter set of the BSS. Or, 4) it may be the time obtained by subtracting 'aSIFSTime + 2 x (aSlotTime)' from the completion time of the maximum allowable time of the channel access operation defined in Step 3, starting from the completion time of the Defer Signal transmission. Here, AIFSN[i] is the smallest AIFSN[i] value in the EDCA Parameter set of the BSS. Or, 5) it may be the time obtained by subtracting 'aSIFSTime + aSlotTime' from the completion time of the maximum allowable time of the channel access operation defined in Step 3, starting from the completion time of the Defer Signal transmission. Here, AIFSN[i] is the smallest AIFSN[i] value in the EDCA Parameter set of the corresponding BSS.

[0072] C. The Duration value of the MAC header of the Defer Signal may be the EIFS (extended interframe space) value. Alternatively, if the Defer Signal is a signal containing only a PHY preamble, STAs that do not perform P-EDCA operations must wait without performing channel access operations during the EIFS time because they may detect the frame as an error when receiving the Defer Signal.

[0073]

[0074] Step 3: STAs that have transmitted the DS may perform a channel access operation (e.g., performing a random backoff operation consisting of AIFS[VO] + multiple aSlotTime times, or performing a random backoff operation consisting of multiple aSlotTime times). Additionally, STAs that have not transmitted the DS but possess a frame corresponding to the conditions for performing a P-EDCA channel access operation may perform a P-EDCA channel access operation after receiving the DS transmitted by the AP (310) or another STA. STAs corresponding to the above conditions may be excluded from the operation of setting the NAV (network allocation vector) by receiving the DS after receiving the DS. Alternatively, if the NAV is set by receiving the DS, the NAV may be canceled.

[0075] A. The random backoff operation is an operation that selects a random backoff counter, decrements the backoff counter for each slot time (e.g., each of AIFS[VO] and multiple aSlotTimes may be a slot, or each of multiple aSlotTimes may be a slot), and transmits a frame at the slot boundary where the backoff counter reaches 0.

[0076] B. The random backoff counter selection may be an integer selected by a uniform random method in the interval [0, CW[P-EDCA]].

[0077] Meanwhile, referring to steps 3A and B, the maximum backoff length that P-EDCA STAs can perform after DS transmission may be the sum of AIFS time (e.g., AIFS[VO] time) and CW[P-EDCA] * aSlotTime. CW[P-EDCA] may be a value indicated by AP (310), but may be a pre-specified value (e.g., 7). The aforementioned pre-specified value may be equal to or based on the P-EDCA CWmax value. The aforementioned P-EDCA CWmax value and the P-EDCA CWmin value may be values ​​that can be set and indicated as integers greater than or equal to 1.

[0078]

[0079] Step 4: The STA that has completed the random backoff operation transmits a frame at the slot boundary where the backoff counter reaches 0.

[0080] In Step 2 of the P-EDCA channel access operation, DS may be a frame transmitted by the STA(s). Here, the duration field of DS may be the time interval from the time DS transmission is completed until the maximum allowable time of the channel access operation defined in Step 3 described above. For example, the maximum allowable time of the channel access operation may be 'AIFS[VO] + multiple aSlotTime times'. Here, AIFS[VO] may be 'SIFS(Short Interframe Space) + AIFSN(arbitration interframe space number) * aSlotTime', and the maximum allowable time of the channel access operation may be the maximum value of '[0, CW[P-EDCA]]', taking into account the P-EDCA CWmax value. That is, the size of the maximum contention window used for the channel access operation performed after DS transmission may be taken into account. Accordingly, the maximum allowable time may be expressed as the sum of the SIFS, the AIFSN, and the maximum value of the Contention Window (CW) (e.g., P-EDCA CWmax), multiplied by aSlotTime, but is not limited thereto. The default value of the aforementioned AIFSN used in the calculation of the DS duration field in Step 2 and the calculation of the AIFS used in the channel access operation in Step 3 may be set to 2. Alternatively, the AP (310) may indicate the aforementioned AIFSN. Here, the AIFSN may be referred to as P-EDCA AIFSN, but this is merely a name or term for convenience of explanation and is not limited thereto, and may be used as other terms or names. The AIFSN is a value that can be set and indicated as an integer value greater than or equal to 0. Another STA that receives a DS with the duration field set as described above may set a NAV (network allocation vector) considering the duration field of the DS and may not perform frame transmission in that period. On the other hand, certain STAs may not be able to receive DS.If STAs are in a hidden node relationship, frames and signals transmitted by a specific node may not be detected. Therefore, if a DS is transmitted by a specific STA, STAs in a hidden node relationship with that specific STA may not receive the DS. For example, STAs that do not use or support P-EDCA may not receive the DS and may detect the medium as idle to perform normal channel access operations (e.g., EDCA channel access operation, EDCA backoff operation). As a specific example, non-AP STA 2 (340) may be in a hidden node relationship where it cannot receive frames from non-AP STA 1 (320) and non-AP STA 2 (330). That is, non-AP STA 2 (340) cannot detect the DS and data frames of non-AP STA 1 (320) and non-AP STA 2 (330). Here, non-AP STA 1 (320) and non-AP STA 2 (330) have transmitted DS, but non-AP STA 2 (340) may not receive the DS transmitted by non-AP STA 1 (320) and non-AP STA 2 (330). Therefore, non-AP STA 2 (340) may perform a channel access operation (e.g., a general EDCA channel access operation that does not follow the P-EDCA channel access operation). When non-AP STA 2 (340) succeeds in the channel access operation and starts transmitting a frame, the frame transmitted by non-AP STA 2 (340) may collide with the DS of non-AP STA 1 (320) and non-AP STA 2 (330). After non-AP STA 1 (320) or non-AP STA 2 (330) transmits DS, the frame transmitted in step 3 described above and the frame transmitted by non-AP STA 2 (340) may collide. Therefore, the P-EDCA channel access operation may fail, and methods to account for this are described below.

[0081] FIG. 4 is a diagram showing a hidden node prevention method when using wireless LAN P-EDCA applied to the present disclosure.

[0082] Referring to FIG. 4, a case can be considered in which an AP (310) and non-AP STA 1 (320), non-AP STA 2 (330), and non-AP STA 2 (340) connected to the AP (310) operate in a wireless LAN network. Here, non-AP STA 1 (320) and non-AP STA 2 (330) support the P-EDCA channel access operation described in FIG. 3 and may have low-latency data frames to be transmitted through the P-EDCA channel access operation. non-AP STA 2 (340) may not support the P-EDCA operation described in FIG. 3. non-AP STA 2 (340) may be in a hidden node relationship that cannot receive frames from non-AP STA 1 (320) and non-AP STA 2 (330). That is, non-AP STA 2 (340) cannot detect the DS and data frames of non-AP STA 1 (320) and non-AP STA 2 (330). However, this is for convenience of explanation only and is not limited to the situation described above.

[0083] Referring to FIG. 4, in a BSS configured by AP (310), non-AP STA 1 (320), non-AP STA 2 (330), and non-AP STA 2 (340), the channel may be switched to an idle state after an occupied state resulting from frame transmission. When the channel is switched to an idle state, non-AP STA 1 (320) and non-AP STA 2 (330) may perform the P-EDCA channel access operation described in FIG. 3. When the channel is switched to an idle state after an occupied state resulting from frame transmission in the BSS, non-AP STA 2 (340) may perform the EDCA channel access operation. For example, the channel may be occupied by transmission from the AP (310). Here, if the AP (310) succeeds in a channel access operation (e.g., EDCA (enhanced distributed channel access) TXOP (transmit opportunity) acquisition procedure, EDCA backoff procedure), it acquires a TXOP, which is a time interval during which multiple frames can be transmitted, and can transmit frames to non-AP STA 2 (340). The AP (310) can exchange RTS frames (401), CTS frames (402), data frames (403), and response frames (404) with non-AP STA 2 (340). Here, there may be a residual TXOP in the TXOP of the AP (310).

[0084] Additionally, as an example, AP (310) and non-AP STA 1 (320) and non-AP STA 2 (330) may have established a stream classification service (SCS) session. When establishing the SCS, the low-latency traffic cycle of non-AP STA 1 (320) and non-AP STA 2 (330) and the delay information of the low-latency traffic may be directed to AP (310). Thus, AP (310) may recognize that at least one of non-AP STA 1 (320) and non-AP STA 2 (330) requires low-latency transmission after the completion of the TXOP of AP (310). In the above case, AP (310) may transmit DS (405) within the TXOP. As another example, AP (310) may transmit DS after AIFS[P-EDCA_AP] time after the TXOP has ended. Here, AIFS[P-EDCA_AP] is a smaller value than AIFS[P-EDCA] used by the STAs, so that the AP (310) can transmit DS before the STAs. Alternatively, AIFS[P-EDCA_AP] may be equal to AIFS[P-EDCA]. In the above case, the AP (310) and the STAs can transmit DS with the same priority.

[0085] Here, the DS (405) transmitted by the AP (310) can be received by all STAs connected to the AP (310) (i.e., non-AP STA 1 (320) to non-AP STA 2 (340)). Thus, non-AP STA 2 (340) can receive the DS (405) after performing frame exchange with the AP (310). Based on the received DS (405), non-AP STA 2 (340) can set a NAV, which is a period for setting the virtual CS to an occupied state, and accordingly, the EDCA channel access operation of non-AP STA 2 (340) can be stopped. Even if non-AP STA 1 (320) and non-AP STA 2 (330) receive the DS (405) transmitted by the AP (310) without transmitting a DS, they can perform the P-EDCA operation described above in FIG. 3. That is, even if non-AP STA 1 (320) and non-AP STA 2 (330) have not transmitted DS, if they receive DS (405) from AP (310), they can perform the P-EDCA operation by considering that they have performed Step 2 of the [P-EDCA Channel Access Operation] described above. Therefore, non-AP STA 1 (320) and non-AP STA 2 (330) can perform the channel access operation, which is Step 3 described above. non-AP STA 1 (320) and non-AP STA 2 (330) can transmit a frame (406) by performing Steps 3 and 4 described above as the P-EDCA channel access operation, and since non-AP STA 2 (340) stops the channel access operation, frame collisions can be prevented during the P-EDCA operation.

[0086] As another example, Figures 5 and 6 below may be hidden node prevention methods with P-EDCA operations different from those described above.

[0087] FIG. 5 is a diagram illustrating a hidden node prevention method when using wireless LAN P-EDCA applicable to the present disclosure. Referring to FIG. 5, a case can be considered in which an AP (310) and non-AP STA 1 (320), non-AP STA 2 (330), and non-AP STA 2 (340) connected to the AP (310) operate in a wireless LAN network. Here, non-AP STA 1 (320) and non-AP STA 2 (330) support the P-EDCA channel access operation described above in FIG. 3 and may have low-latency data frames to be transmitted through the P-EDCA channel access operation. non-AP STA 2 (340) may not support the P-EDCA operation described above in FIG. 3. Here, non-AP STA 2 (340) may be in a hidden node relationship that cannot receive frames from non-AP STA 1 (320) and non-AP STA 2 (330). That is, non-AP STA 2 (340) cannot detect the DS and data frames of non-AP STA 1 (320) and non-AP STA 2 (330). However, this is for convenience of explanation only and is not limited to the situation described above.

[0088] Additionally, a frame transmission procedure of the AP (310) can be performed in the network configuration described above, which may be as shown in FIG. 4. Subsequently, non-AP STA 1 (320) and non-AP STA 2 (330) detect the medium from an occupied state to an idle state, and transmit DS (408-1, 408-2) according to steps 1 and 2 through the P-EDCA channel access operation described above. Here, non-AP STA 2 (340) may be in a hidden node relationship that cannot receive frames from non-AP STA 1 (320) and non-AP STA 2 (330). That is, non-AP STA 2 (340) cannot detect DS and data frames from non-AP STA 1 (320) and non-AP STA 2 (330). Therefore, non-AP STA 2 (340) may not receive DS (408-1, 408-2) transmitted by non-AP STA 1 (320) and non-AP STA 2 (330), and may perform EDCA operations. Here, AP (310) may transmit a feedback signal (or feedback frame) (409) after non-AP STA 1 (320) and non-AP STA 2 (330) transmit DS (408-1, 408-2) and after a short interframe space (SIFS) time. For example, AP (310) may transmit a null data PPDU (NDP) as the feedback signal (409) in response to the received DS (408-1, 408-2). Here, the NDP may be a signal containing only a PHY preamble. As another example, the AP (310) may transmit a CTS frame as a feedback signal (or feedback frame) (409) to the DS (408-1, 408-2). After receiving the feedback frame (409), the non-AP STA 1 (320) and the non-AP STA 2 (330) may perform step 3 of the [P-EDCA channel access operation] described above.That is, non-AP STA 1 (320) and non-AP STA 2 (330) may not perform the random backoff operation of the [P-EDCA channel access operation] described above immediately after transmitting DS (408-1, 408-2), but may perform it after transmitting DS (408-1, 408-2) and receiving the feedback signal (or feedback frame) (409). Meanwhile, non-AP STA 2 (340) may receive the feedback signal (409) of the AP (310) and set the NAV as a period during which the medium is detected to be in an occupied state for a certain period. For example, the NAV may be set based on the L-LENGTH field included in the L-SIG of the NDP. Since the medium is detected to be in an occupied state by the virtual CCA due to the NAV setting, non-AP STA 2 (340) may stop the EDCA channel access operation and the transmission of subsequent frames may also be stopped. Therefore, frame collisions between non-AP STA 1 (320) and non-AP STA 2 (330) using P-EDCA and non-AP STA 2 (340) not using P-EDCA can be prevented.

[0089] As another example, non-AP STA 2 (340) can detect a frame error when receiving the NDP of AP (310) because the NDP frame is a signal that does not have a MAC frame. Therefore, non-AP STA 2 (340) can wait for the EIFS (Extended Inter-frame Space) time, which is longer than SIFS and AIFS [P-EDCA]. During the EIFS time, non-AP STA 2 (340) can stop channel access operations and stop subsequent frame transmission. Thus, frame collisions between non-AP STA 1 (320) and non-AP STA 2 (330) using P-EDCA and non-AP STA 2 (340) not using P-EDCA can be prevented.

[0090] As another example, referring to FIG. 5, non-AP STA 1 (320) and non-AP STA 2 (330) in P-EDCA can simultaneously transmit CTS frames to DS (408-1, 408-2). Meanwhile, the CTS frames (i.e., MAC frames) transmitted by non-AP STA 1 (320) and non-AP STA 2 (330) connected to AP (310) may be S-CTS frames in which the form of the PPDU (physical protocol data unit) containing the MAC frame is identical. For example, the S-CTS frames may be frames in which the PPDU transmission parameters (e.g., SCRAMBLER_INITIAL_VALUE)) are set identically. That is, the same DS frame format may be used within the BSS configured by AP (310), non-AP STA 1 (320), and non-AP STA 2 (330). Here, a method may be required to match the format of the PPDU of non-AP STA 1 (320) and non-AP STA 2 (330). The AP (310) may specify the SCRAMBLER_INITIAL_VALUE parameter for transmitting the PPDU as a DS in the beacon frame transmitted to non-AP STA 1 (320) and non-AP STA 2 (330). Alternatively, the SCRAMBLER_INITIAL_VALUE parameter may be a value pre-specified for the DS, but is not limited to a specific format. As described above, non-AP STA 1 (320) and non-AP STA 2 (330) may transmit the PPDU using the same SCRAMBLER_INITIAL_VALUE parameter when transmitting the DS. Therefore, the DS transmitted by non-AP STA 1 (320) and non-AP STA 2 (330) may have the same MAC frame and the same PPDU format, and the AP (310) can decode the DS normally without frame collision between non-AP STA 1 (320) and non-AP STA 2 (330).Additionally, the contents of the MAC frames transmitted by non-AP STA 1 (320) and non-AP STA 2 (330) may be identical. For example, the MAC header of the CTS frame transmitted by non-AP STA 1 (320) and non-AP STA 2 (330) may include the RA (receiver address) field of the CTS frame. Here, the address in the RA field may indicate the same address for non-AP STA 1 (320) and non-AP STA 2 (330). For example, the address may be set to the address of the AP (310) to which non-AP STA 1 (320) and non-AP STA 2 (330) are connected. Accordingly, the AP (310) can recognize that it has received a DS from STAs connected to the AP (310), such as non-AP STA 1 (320) and non-AP STA 2 (330), and can transmit a feedback frame for the frame as described above. Based on the above, the MAC frame format of the DS transmitted by non-AP STA 1 (320) and non-AP STA 2 (330) connected to the same AP (310) can be matched.

[0091] Here, as an example, an AP other than the aforementioned AP may operate, and said AP It could be. connected to It can operate, P-EDCA can also be used. If the RA field of the DS transmitted by is not set to AP, the AP When it receives the DS transmitted by, it does not send feedback. Meanwhile, Is When receiving DS from, the RA field of DS You can confirm that it is set to and send feedback to DS.

[0092] Here, there may be a STA that does not directly transmit the DS but performs a P-EDCA operation through a DS transmitted by another STA within the same BSS. In the above case, if the RA field of the DS transmitted by another STA within the same BSS is the MAC address of the AP (310), the terminal that did not directly transmit the DS may not be able to distinguish between the received DS and a regular CTS frame. Therefore, the RA field value of the DS may be set to a specific value and transmitted. For example, the specific value may be a value based on the MAC address of the AP (310). As a specific example, the RA field value of the DS may be determined by setting the Individual / Group bit (LSB of the first octet of the AP's MAC address) of the AP's (310) MAC address to 1. Therefore, a STA that does not directly transmit a DS but performs a P-EDCA operation through a DS transmitted by another STA within the same BSS can recognize the received CTS frame as a DS and participate in a subsequent P-EDCA operation if the SCRAMBLER_INITIAL_VALUE parameter value of the received CTS frame is set as the SCRAMBLER_INITIAL_VALUE value for DS transmission and the RA of the CTS frame is set to a specific value.

[0093] As another example, the form of the DS frame is a BSS composed of an AP (310), a non-AP STA 1 (320), and a STA 2. and It can be used commonly in the BSS configured by. AP and A common SCRAMBLER_INITIAL_VALUE may be negotiated among them, or a predefined SCRAMBLER_INITIAL_VALUE may exist. Thus, non-AP STA 1 (320), STA 2 and It can transmit all DS in the same PPDU format. In addition, AP and When transmitting a common DS frame, the RA field address used may be negotiated or have a predetermined value. For example, the RA field address is AP and It may be a known groupcast address, broadcast address, and other address, but is not limited to a specific form. Or, AP and Among them, the address of the aforementioned AP (i.e., BSSID) is the AP and It can be used as the address of the RA field used during DS transmission, representing. non-AP STA 1 (320), STA 2 and It can transmit a common DS after the AIFS time following the detection of the last media occupancy state, and then perform a channel access operation to transmit a low-latency frame. Meanwhile, the AP and is non-AP STA 1(320), STA 2 and It can receive the common DS transmitted by and send feedback. AP and As described above, the format of the feedback frame transmitted by [it] may also have the SCRAMBLER_INITIAL_VALUE of the PPDU be a predetermined or negotiated value. Additionally, the RA and TA fields of the MAC header of the feedback frame may also be predetermined or negotiated values. Therefore, the form of the feedback frame is AP and ...can be identical. Also, as an example, AP (and the above The feedback frame transmitted by ) may be an RTS frame in addition to NDP (null data PPDU) and CTS frames, and is not limited to a specific form.

[0094] FIG. 6 is a diagram illustrating a hidden node prevention method when using wireless LAN P-EDCA applicable to the present disclosure. Referring to FIG. 6, a case can be considered in which an AP (310) and non-AP STA 1 (320), non-AP STA 2 (330), and non-AP STA 3 (340) connected to the AP (310) operate in a wireless LAN network. Here, non-AP STA 1 (320) and non-AP STA 2 (330) support the P-EDCA channel access operation described above in FIG. 3 and may have low-latency data frames to be transmitted through the P-EDCA channel access operation. non-AP STA 2 (340) may not support the P-EDCA operation described above in FIG. 3. Here, non-AP STA 2 (340) may be in a hidden node relationship that cannot receive frames from non-AP STA 1 (320) and non-AP STA 2 (330). That is, non-AP STA 2 (340) cannot detect DS and data frames of non-AP STA 1 (320) and non-AP STA 2 (330). However, this is for convenience of explanation only and is not limited to the situation described above. In addition, the frame transmission procedure of the AP (310) can be performed in the network configuration described above, and this may be as shown in FIG. 4. Subsequently, non-AP STA 1 (320) and non-AP STA 2 (330) can detect that the medium has switched from an occupied state to an idle state and transmit DS. In addition, non-AP STA 2 (340) may be in a hidden node relationship where it cannot receive frames from non-AP STA 1 (320) and non-AP STA 2 (330). That is, non-AP STA 2 (340) cannot detect the DS and data frames of non-AP STA 1 (320) and non-AP STA 2 (330).Therefore, non-AP STA 2 (340) may not receive DS from non-AP STA 1 (320) and non-AP STA 2 (330), and non-AP STA 2 (340) may perform EDCA operation (i.e., general EDCA channel access operation that does not follow [P-EDCA channel access operation]).

[0095] Here, the DS (412-1, 412-2) transmitted by non-AP STA 1 (320) and non-AP STA 2 (330) may be S (simultaneous)-RTS frames (412-1, 412-2) requesting the transmission of a CTS frame by the AP (310). The S-RTS frames (412-1, 412-2) may be frames that can be received without collision even if multiple STAs transmit identically, as described above in [P-EDCA Channel Access Operation]. That is, the AP (310) or STA may receive S-RTS frames (412-1, 412-2) transmitted from multiple STAs. As an example, the S-RTS frames (412-1, 412-2) may be RTS frames configured to have the same TA (transmitter address) and RA (receiver address) and the same Scrambler Seed. Here, TA and RA may be the same address, or may be a designated address indicating that it is DS.

[0096] When non-AP STA 1 (320) and non-AP STA 2 (330) transmit S-RTS frames (412-1, 412-2) that are DS, the AP (310) may receive the S-RTS frames (412-1, 412-2) and transmit a CTS frame (413) after a short interframe space (SIFS) time. Here, the RA of the CTS frame (413) may be an address specified to indicate that it is a response to the DS (412-1, 412-2). The RA of the CTS frame (413) may be the same as the address indicating that it is a DS in at least one of the TA and RA used in the S-RTS frames (412-1, 412-2). non-AP STA 1 (320) and non-AP STA 2 (330) can perform step 3 of [P-EDCA channel access operation] after receiving the CTS frame (413). That is, non-AP STA 1 (320) and non-AP STA 2 (330) can perform the random backoff operation after receiving the CTS frame (413) after transmitting the DS (412-1, 412-2) rather than immediately after transmitting the DS. Meanwhile, non-AP STA 2 (340) can receive the CTS frame (413) of the AP (310) and set a NAV, which is a period during which the medium is detected to be in an occupied state for a certain period. Since the medium is detected to be in an occupied state, non-AP STA 2 (340) can stop the EDCA channel access operation and stop the transmission of subsequent frames. Therefore, frame collisions between non-AP STA 1 (320) and non-AP STA 2 (330) using P-EDCA and non-AP STA 2 (340) not using P-EDCA can be prevented.

[0097] FIG. 7 is a flowchart illustrating the operation of an STA in a wireless LAN to which the present disclosure applies.

[0098] According to one embodiment of the present specification, in a wireless LAN system, an STA can confirm that the channel has transitioned from an occupied state to an idle state and that the channel remains idle for a first predetermined time (S710). After that, the STA can perform channel access via P-EDCA and transmit a DS after the first predetermined time (S720). Here, the DS is a DS-CTS frame, the DS-CTS frame includes a MAC header, and the duration field of the MAC header can be set to the maximum allowable time for the channel access operation. After that, the STA can perform a backoff procedure based on the channel access operation after transmitting the DS and transmit a frame at the slot boundary where the backoff counter reaches 0 (S730).

[0099] Additionally, at least one STA receiving a DS-CTS frame may have a NAV based on the duration field of the DS-CTS frame set. The maximum allowable time for channel access operations set in the duration field of the DS-CTS frame is a time set based on the sum of aSIFSTime and N*aSlotTime, where N can be determined based on P-EDCA related parameters and the maximum value of the P-EDCA contention window. Additionally, the P-EDCA related parameter may be P-EDCA AIFSN, and the maximum value of the P-EDCA contention window may be a value determined based on the P-EDCA CWmax parameter. Additionally, the backoff counter may be selected within a contention window determined based on the P-EDCA CWmax parameter, which is the maximum value of the P-EDCA contention window, and the P-EDCA CWmin, which is the minimum value of the P-EDCA contention window. Additionally, the first set time may be determined based on the P-EDCA related parameters.

[0100] Additionally, when P-EDCA is used in a basic service set (BSS) that includes an STA, the P-EDCA-related parameters may be determined based on at least one of the basic parameter values ​​and the modified parameter values. Here, the first set time is the arbitration interframe space (AIFS) associated with DS transmission, the AIFS is a time set based on the sum of aSIFSTime and M*aSlotTime, and M may be determined based on at least one of the basic parameter values ​​and the modified parameter values. Additionally, the STA may perform a backoff procedure based on channel access operations after transmitting a DS and receiving a feedback frame from another STA, and may perform frame transmission at the slot boundary where the backoff counter reaches 0. Additionally, the DS may be an RTS frame, and the feedback frame may be a CTS frame. As an example, the STA may be a non-AP STA or an AP STA. Additionally, the SCRAMBLER_INITIAL_VALUE value set for the DS-CTS frame is a pre-set value, and the SCRAMBLER_INITIAL_VALUE value can be used identically in at least one STA including the STA. Additionally, DS-CTS frames transmitted from at least one STA including the STA can be transmitted simultaneously based on the SCRAMBLER_INITIAL_VALUE value. Additionally, DS-CTS frames transmitted from at least one STA including the STA can have a PPDU (physical protocol data unit) with identical content based on the SCRAMBLER_INITIAL_VALUE as a pre-set value.

[0101] The methods according to the present disclosure may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either alone or in combination. The program instructions recorded on the computer-readable medium may be those specifically designed and configured for the present disclosure, or they may be those known and available to those skilled in the art of computer software. Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions include machine code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate as at least one software module to perform the operations of the present disclosure, and vice versa. Although the present invention has been described with reference to the embodiments above, those skilled in the art will understand that various modifications and changes can be made to the present disclosure without departing from the spirit and scope of the disclosure as set forth in the following claims.

[0102]

[0103] The above-mentioned matters may also be applied to other systems.

Claims

1. In the method of operation of a station (STA) in a wireless LAN system, A step in which the above STA confirms that the channel is switched from an occupied state to an idle state and that the channel is in an idle state for a first pre-set time, wherein the STA performs channel access through P-EDCA (prioritized enhanced distributed channel access); A step of transmitting a DS (defer signal) after the first set time above, wherein the DS is a DS-CTS (clear to send) frame, the DS-CTS frame includes a MAC (medium access control) header, and the duration field of the MAC header is set to the maximum allowable time for channel access operation; and A method of operation comprising the step of performing a backoff procedure based on a channel access operation after the above DS transmission, and performing frame transmission at a slot boundary where the backoff counter reaches 0.

2. In Paragraph 1, A method of operation in which a network allocation vector (NAV) based on the duration field of the DS-CTS frame is set in at least one STA receiving the DS-CTS frame.

3. In Paragraph 1, A method of operation in which the maximum allowable time for the channel access operation set in the duration field of the above DS-CTS frame is a time set based on the sum of aSIFSTime and N*aSlotTime, and N is determined based on P-EDCA related parameters and the maximum value of the P-EDCA competition window.

4. In Paragraph 3, A method of operation in which the above-mentioned P-EDCA related parameter is the P-EDCA AIFSN (arbitration interframe space number), and the above-mentioned P-EDCA contention window maximum value is a value determined based on the P-EDCA CWmax parameter.

5. In Paragraph 4, A method of operation in which the backoff counter is selected within a competition window determined based on the P-EDCA CWmax parameter, which is the maximum value of the P-EDCA competition window, and the P-EDCA CWmin, which is the minimum value of the P-EDCA competition window.

6. In Paragraph 1, The above-mentioned first set time is determined based on P-EDCA related parameters, in a method of operation.

7. In Paragraph 6, A method of operation in which, when the above P-EDCA is used in a BSS (basic service set) including the above STA, the P-EDCA related parameter is determined based on at least one of a basic parameter value and a modified parameter value.

8. In Paragraph 7, A method of operation in which the first time set above is an AIFS (arbitration interframe space) related to the DS transmission, the AIFS is a time set based on the sum of aSIFSTime and M*aSlotTime, and M is determined based on at least one of the basic parameter value and the change parameter value.

9. In Paragraph 1, A method of operation in which the STA transmits the DS and, after receiving a feedback frame from another STA, performs the backoff procedure based on the channel access operation, and performs frame transmission at the slot boundary where the backoff counter reaches 0.

10. In Paragraph 9, A method of operation in which the above DS is an RTS (request to send) frame and the above feedback frame is a CTS frame.

11. In Paragraph 1, A method of operation in which the above STA is a non-AP STA or an AP STA.

12. In Paragraph 1, A method of operation in which the SCRAMBLER_INITIAL_VALUE value set for the above DS-CTS frame is a pre-set value, and the SCRAMBLER_INITIAL_VALUE value is used identically in at least one STA including the above STA.

13. In Paragraph 12, A method of operation in which the DS-CTS frames transmitted from at least one STA including the above STA are simultaneously transmitted based on the SCRAMBLER_INITIAL_VALUE value.

14. In Paragraph 12, A method of operation in which the DS-CTS frame transmitted from at least one STA including the above STA has a PPDU (physical protocol data unit) with identical content based on the SCRAMBLER_INITIAL_VALUE with the above preset value.

15. In a wireless LAN system, regarding a station (STA), At least one transceiver for transmitting and receiving signals; At least one processor controlling the above-mentioned at least one transmitting and receiving unit; and It includes a memory that stores instructions for the non-AP STA to perform a specific operation by the above at least one processor, and The above specific operation is: The channel is switched from an occupied state to an idle state, and it is confirmed that the channel is in an idle state for a first set period of time, wherein the STA performs channel access through P-EDCA (prioritized enhanced distributed channel access), and Transmit a DS (defer signal) after the first set time above, wherein the DS is a DS CTS (clear to send) frame, the DS CTS frame includes a MAC (medium access control) header, the duration field of the MAC header is set to the maximum allowable time for channel access operation, and A method of operation that performs a backoff procedure based on channel access operation after the above DS transmission, and performs frame transmission at the slot boundary where the backoff counter reaches 0.

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