Method and device for indicating CCA state in non-primary channel access operation in wireless LAN

Abstract

According to the present invention, a method comprises the steps in which: an STA detects transmission of an OBSS on a primary channel in a wireless LAN system; the STA starts to switch an operation channel from the primary channel to an NPCA primary channel on the basis of NPCA switching conditions; a PHY layer of the STA receives, from a MAC layer of the STA, a first primitive for modifying a PHY parameter; the PHY layer of the STA transfers a second primitive to the MAC layer of the STA in response to the first primitive; the PHY layer of the STA receives, from the MAC layer of the STA, a third primitive for initializing a CCA state; and the PHY layer of the STA initializes, on the basis of the third primitive, the CCA state set to an occupied state due to the transmission of the OBSS, wherein the STA can perform a channel access operation on the basis of the initialized CCA state by completing the switching of the operation channel to the NPCA primary channel.

Description

Method and device for indicating CCA status in side-channel access operation of wireless LAN

[0001] The present disclosure relates to a method and apparatus for indicating a clear channel assessment (CCA) status when performing a non-primary channel access (NPCA) operation 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. When NPCA operation is performed, the wireless LAN terminal may perform an operation to switch its operating channel from the primary channel (PCH) to the secondary channel (NPCA primary channel, NPCA PCH) while receiving a PPDU (physical layer protocol data unit). In the above case, the CCA status indicated within the wireless LAN terminal may be indicated as occupied, and thus the NPCA operation may not be performed smoothly. A solution for this is described below.

[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 indicating a CCA status when performing an NPCA operation in a WLAN.

[0009] The present disclosure relates to a method and apparatus for exchanging CCA information for performing NPCA operations between a PHY and a MAC of a wireless LAN terminal that supports NPCA operations in a WLAN.

[0010] The present disclosure relates to a method and apparatus for instructing a CCA state to perform a channel access operation on a sub-channel even when the main channel is occupied, when a wireless LAN terminal supporting NPCA operation in a WLAN switches the operation channel from a main channel to a sub-channel.

[0011] The present disclosure relates to a method and apparatus for performing a channel access operation on a secondary channel even when the primary channel is occupied, when a wireless LAN terminal supporting NPCA operation in a WLAN switches the operation channel from a primary channel to a secondary channel.

[0012] The present disclosure relates to a method and apparatus for identifying a frame transmitted including a main channel by a wireless LAN terminal in a wireless LAN, confirming the existence of a wireless LAN terminal operating on the main channel, and determining the transmission of a response frame for a wireless LAN terminal operating on the main channel.

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

[0014]

[0015] According to one embodiment of the present specification, a method of operation of a station (STA) in a wireless LAN system comprises: a step in which the STA detects the transmission of an overlapping basic service set (OBSS) on a main channel, wherein the transmission of the OBSS includes the transmission of a physical layer protocol data unit (PPDU) of the OBSS; a step in which the STA initiates a switching of an operating channel from a main channel to an NPCA main channel based on a non-primary channel access (NPCA) switching condition; a step in which the physical layer of the STA receives a first primitive for modifying PHY parameters from the medium access control (MAC) layer of the STA; a step in which the physical layer of the STA transmits a second primitive to the MAC layer of the STA in response to the first primitive; a step in which the physical layer of the STA receives a third primitive for initializing a clear channel assessment (CCA) state from the MAC layer of the STA; and a step in which the physical layer of the STA initializes a CCA state set to an occupied state by the transmission of the OBSS based on the third primitive, wherein the STA Channel access operations can be performed based on the initialized CCA state by completing the operation channel switch to the NPCA main channel before the end of the transmission of OBSS.

[0016] 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 the at least one transceiver, and a memory for storing instructions that cause the STA to perform a specific operation by the at least one processor, wherein the specific operation is: detecting the transmission of an overlapping basic service set (OBSS) on a main channel, wherein the transmission of the OBSS includes the transmission of a physical layer protocol data unit (PPDU) of the OBSS, initiating the switching of an operating channel from a main channel to an NPCA main channel based on a non-primary channel access (NPCA) switching condition, wherein the physical layer of the STA receives a first primitive for modifying PHY parameters from the medium access control (MAC) layer of the STA, wherein the physical layer of the STA transmits a second primitive to the MAC layer of the STA in response to the first primitive, and the physical layer of the STA initializes a clear channel assessment (CCA) state from the MAC layer of the STA, a third The STA receives a primitive, and the PHY layer of the STA initializes the CCA state that is set to an occupied state by the transmission of the OBSS based on the third primitive, and the STA can perform a channel access operation based on the initialized CCA state by completing the operation channel switching to the NPCA main channel before the end of the transmission of the OBSS.

[0017] In addition, the following points may apply in common.

[0018] According to one embodiment of the present specification, the PHY layer of the STA performs CCA when operating on the NPCA main channel based on the third primitive, and if the NPCA main channel is idle as a result of the CCA performance, it can pass the fourth primitive to the MAC layer of the STA.

[0019] Additionally, according to one embodiment of the present specification, when the STA determines to switch the operating channel to the NPCA main channel based on the transmission of the OBSS and starts the switching of the operating channel to the NPCA main channel, a first primitive may be generated at the MAC layer of the STA and transmitted to the PHY layer of the STA.

[0020] Additionally, according to one embodiment of the present specification, the first primitive includes a PHY setting vector, and the PHY setting vector may include NPCA main channel parameters and NPCA inactive subchannel bitmap parameters.

[0021] In addition, according to one embodiment of the present specification, the NPCA main channel parameter may include a value indicating the NPCA main channel in which the STA is operated by being indicated through the NPCA operation parameter received by the STA.

[0022] Additionally, according to one embodiment of the present specification, the NPCA main channel parameter may further include information indicating that the STA performs an NPCA operation.

[0023] Additionally, according to one embodiment of the present specification, the NPCA inactive subchannel bitmap parameter may include a value indicating a subchannel that is inactive in the NPCA operation, indicated by an NPCA operation parameter received by the STA.

[0024] Additionally, according to one embodiment of the present specification, the NPCA inactive subchannel bitmap parameter may indicate that the main channel of the basic service set (BSS) containing the STA is inactive.

[0025] In addition, according to one embodiment of the present specification, when the PHY layer of the STA detects the transmission of the OBSS, the PHY layer of the STA detects the PPDU (physical layer protocol data unit) of the OBSS and can maintain the CCA state in a occupied state until the transmission of the PPDU of the OBSS is completed based on information regarding the transmission completion time of the PPDU of the OBSS.

[0026] In addition, according to one embodiment of the present specification, when the PHY layer of the STA initializes the CCA state that is set to an occupied state by the transmission of the OBSS based on the third primitive, the PHY layer of the STA can initialize the transmission completion time information of the PPDU of the OBSS to set the CCA state independently of the transmission completion time of the PPDU of the OBSS.

[0027] Additionally, according to one embodiment of the present specification, when the STA starts returning to the main channel after operating on the NPCA main channel, a first primitive is generated at the MAC layer of the STA and transmitted to the PHY layer of the STA, wherein the first primitive includes a PHY setting vector, and the PHY setting vector may include BSS main channel parameters and BSS inactive subchannel bitmap parameters.

[0028] In addition, according to one embodiment of the present specification, the BSS main channel parameter may include a value indicating the main channel on which the STA is operated.

[0029] Additionally, according to one embodiment of the present specification, the BSS inactive subchannel bitmap parameter may include a value indicating a subchannel that is disabled when the STA is operating on the main channel.

[0030] Additionally, according to one embodiment of the present specification, the third primitive may be characterized by being generated before the transmission of the PPDU of the OBSS detected in the main channel is terminated during the process in which the STA switches the operating channel from the main channel to the NPCA main channel, and being transmitted to the PHY layer of the STA.

[0031] Additionally, according to one embodiment of the present specification, a first primitive is generated while performing a channel switching operation to the NPCA main channel and is transmitted to the PHY layer of the STA, and in response to the first primitive, a second primitive is generated before the NPCA switching delay expires and is transmitted to the MAC layer of the STA, and when the second primitive is transmitted to the MAC layer of the STA, a third primitive may be generated.

[0032] Additionally, according to one embodiment of the present specification, the transmission of an OBSS detected in the main channel includes a trigger frame, and the MAC layer of the STA confirms the normal reception of the trigger frame based on the Intermediate Frame Check Sequence (I-FCS) field included in the trigger frame before the end of reception of the trigger frame, and generates a first primitive and a third primitive.

[0033] Additionally, according to one embodiment of the present specification, the trigger frame may further include a padding field set such that the time length from the time of completion of reception of the I-FCS field to the time of termination of reception of the trigger frame is greater than or equal to the switching delay required to switch the operating channel.

[0034] In addition, according to one embodiment of the present specification, the NPCA switching condition may be characterized as being satisfied when the remaining duration until the expected end of reception of an OBSS transmission detected in the main channel is greater than a preset NPCA minimum duration threshold.

[0035] Additionally, according to one embodiment of the present specification, the first primitive may be PHY-CONFIG.request primitive, the second primitive may be PHY-CONFIG.confirm primitive, the third primitive may be PHY-CCARESET.request primitive, and the fourth primitive may be PHY-CCA.indication(IDLE) primitive.

[0036] In addition, according to one embodiment of the present specification, when the STA completes the operation channel switching to the NPCA main channel and performs a channel access operation, the STA may perform at least one of an EDCA (enhanced distributed channel access) TXOP (transmit opportunity) acquisition operation and an EDCA backoff operation based on the initialized CCA state.

[0037] Additionally, according to one embodiment of the present specification, the STA may be a non-AP STA or an AP STA.

[0038]

[0039] According to the present disclosure, a method for indicating the CCA status when performing NPCA operation in a WLAN can be provided.

[0040] According to the present disclosure, a method can be provided for the PHY and MAC of a wireless LAN terminal that supports NPCA operation in a WLAN to exchange CCA information for performing NPCA operation.

[0041] According to the present disclosure, a method can be provided to instruct a CCA state to perform a channel access operation on a sub-channel even when the main channel is occupied, when a wireless LAN terminal supporting NPCA operation in a WLAN switches the operation channel from a main channel to a sub-channel.

[0042] According to the present disclosure, a method can be provided to perform a channel access operation on a sub-channel even when the main channel is occupied, when a wireless LAN terminal supporting NPCA operation in a WLAN switches the operation channel from the main channel to a sub-channel.

[0043] The technical problems to be solved by the present 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 the present disclosure belongs from the description below.

[0044] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below.

[0045]

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

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

[0048]

[0049] FIG. 3 is a diagram showing a wireless LAN network to which the present disclosure applies.

[0050] FIG. 4 is a diagram illustrating a CCA status indication method for wireless LAN sub-channel access operation applied to the present disclosure.

[0051] FIG. 5 is a diagram illustrating a CCA status indication method for wireless LAN sub-channel access operation applied to the present disclosure.

[0052] FIG. 6 is a diagram illustrating a CCA status indication method for wireless LAN sub-channel access operation applied to the present disclosure.

[0053] FIG. 7 is a flowchart illustrating the operation of an STA in a wireless LAN to which the present disclosure applies.

[0054]

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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."

[0062] 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.

[0063] 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).

[0064] 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).

[0065] 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).

[0066] 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.

[0067] 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.

[0068] The following describes the case where a wireless LAN terminal performs an NPCA operation. While receiving a PPDU (physical layer protocol data unit), the wireless LAN terminal may perform an operation to switch its operating channel from the primary channel (PCH) to the secondary channel (NPCA primary channel, NPCA PCH). In the above case, the 'PHY-CCA.indication primitive' that the PHY (physical) within the wireless LAN terminal instructs the MAC (medium access control) as a result of receiving the PPDU may indicate that the CCA state is busy on the primary channel, and the CCA state may be maintained until the expected end time of receiving the PPDU. Therefore, at the expected end time of receiving the PPDU, the PHY may indicate via the 'PHY-CCA.indication primitive' that the CCA state is idle on the primary channel. If the CCA state indicated by the 'PHY-CCA.indication primitive' indicates that the CCA state is busy on the primary channel, the MAC within the wireless LAN terminal may wait without performing a channel access operation. Therefore, in the situation described above, even if the wireless LAN terminal switches the operating channel to the secondary channel (NPCA main channel), the 'PHY-CCA.indication primitive' can indicate that the CCA state is occupied on the main channel until the expected end of reception of the PPDU received on the main channel. Accordingly, the MAC within the wireless LAN terminal may not be able to perform channel access operations until the expected end of reception of the PPDU received on the main channel (or until the PHY transmits the 'PHY-CCA.indication primitive' indicating that the CCA state is on the main channel idle), even though the secondary channel (NPCA PCH) is actually idle. As a result, NPCA operations may not be performed smoothly, and a solution for this is described below.

[0069] FIG. 3 is a diagram illustrating a wireless LAN network to which the present disclosure applies. Referring to FIG. 3, wireless LAN terminals AP 1 and AP 2, which are access points (APs), can operate in the wireless LAN network. AP 1 and AP 2 can each configure BSS (Basic Service Set) 1 and BSS 2. Additionally, non-AP STA 1 and non-AP STA 2, which are wireless LAN terminals that are not APs (non-AP STAs), can operate in the wireless LAN network. non-AP STA 1 can be connected to AP 1 and operate in BSS 1, and non-AP STA 2 can be connected to AP 2 and operate in BSS 2. AP 1 and AP 2 can configure a Primary Channel (PCH) used when accessing a channel in their respective BSSs. The above-described wireless LAN terminals (e.g., AP 1, AP 2, non-AP STA 1, non-AP STA 2) may need to access and occupy the main channel of the BSS to which they belong in order to communicate with other wireless LAN terminals. Here, the channel access operations performed by the wireless LAN terminals may vary. For example, the channel access operations may include at least one of the distributed coordination function (DCF) procedure, enhanced distributed channel access (EDCA) procedure, backoff procedure, and EDCA TXOP (transmit opportunity) acquisition procedure, but are not limited thereto.

[0070] Meanwhile, the aforementioned BSS 1 and BSS 2 may be in an overlapping BSS (OBSS) relationship with each other. For example, non-AP STA 1, which is a wireless LAN terminal within BSS 1, may transmit frames by occupying the main channel, which is a channel for channel access. When non-AP STA 1 transmits frames by occupying the main channel, non-AP STA 1 may transmit frames by including a secondary channel (SCH) within the operating bandwidth of BSS 1 in addition to the main channel of BSS 1.

[0071] In a wireless LAN network, in addition to BSS 1, there may be another BSS (BSS 2). Here, if a frame transmitted by non-AP STA 1, including the main channel and sub-channel of BSS 1, occupies at least one of the main channel and sub-channel of BSS 2 and is received by a wireless LAN terminal (e.g., AP 2, non-AP STA 2) operating in BSS 2, the above transmission may affect the channel access and frame transmission / reception operations of the wireless LAN terminal operating in BSS 2. As described above, if communication within one BSS affects communication in an adjacent other BSS (e.g., if channel access, frame transmission / reception operations, etc. of BSS 2 become impossible as a result of channel access operations performed in BSS 1, and / or if transmission by a wireless LAN terminal of BSS 1 is detected in the main channel of BSS 2), the two BSSs may recognize each other as OBSS. For example, in the above case, BSS 1 and BSS 2 can each recognize each other as OBSS.

[0072] Additionally, wireless LAN terminals (e.g., AP 1, non-AP STA 1) of a wireless LAN network may support non-primary channel access (NPCA) operation. An AP that supports NPCA operation may be referred to as an NPCA AP, and a non-AP STA that supports NPCA operation may be referred to as an NPCA non-AP STA; furthermore, NPCA STA may be used as a collective term for both NPCA APs and NPCA non-AP STAs. However, it is not limited to these names or terms. NPCA may be a method by which an NPCA STA performs channel access by switching the operating channel to one of the non-primary channels among the operating channels of a BSS, excluding the primary channel, when the primary channel of the BSS to which it belongs is occupied by an OBSS. Specifically, an NPCA AP may designate one of the non-primary channels among the operating channels of its BSS, excluding the primary channel, as the NPCA primary channel (NPCA PCH). An NPCA AP can transmit information about the NPCA main channel to an NPCA non-AP STA through frames transmitted within the aforementioned BSS (e.g., Beacon, Probe Response, UHR OMP (Ultra High Reliability Operation Mode and Parameters)). Additionally, an NPCA AP can negotiate the use of NPCA with an NPCA non-AP STA. The negotiation for NPCA use can be performed through frame exchange between the NPCA AP and the NPCA non-AP STA. At least one of the NPCA AP and the NPCA non-AP STA that negotiated the use of NPCA with the NPCA AP can perform NPCA if channel access is impossible because an OBSS occupies the main channel of the BSS in which it is included.That is, at least one of the NPCA AP and NPCA non-AP STA that negotiated NPCA usage with the NPCA AP can switch its operation channel to the NPCA main channel and perform channel access on the NPCA main channel.

[0073] NPCA operation can be performed when the OBSS occupies the main channel of the BSS (i.e., when the OBSS affects the BSS), and it may be efficient to perform the NPCA operation only when the duration of the time the OBSS occupies the main channel is sufficiently long. Therefore, a minimum duration threshold for performing NPCA (e.g., NPCA minimum duration threshold) may be set in the NPCA operation. In the above-described NPCA operation, an NPCA switching time (e.g., NPCA switching time) may be required for the NPCA STA to switch its operating channel from the main channel to the NPCA main channel. Conversely, an NPCA switch back time (e.g., NPCA switch back time) may be required for the NPCA STA to switch its operating channel back from the NPCA main channel to the main channel. The NPCA STA can exchange information regarding the NPCA main channel, NPCA switching time, NPCA switch back time, and NPCA minimum duration threshold described above in at least one of the fields, subfields, elements, bit(s), and other forms within the frames (e.g., Beacon, Probe Response, UHR OMP (Ultra High Reliability Operation Mode and Parameters)) exchanged during the NPCA negotiation process described above.

[0074] When an NPCA STA receives an OBSS frame on the main channel, the NPCA STA may switch its operating channel to the NPCA main channel only when certain conditions are satisfied. For example, the conditions for switching to the NPCA main channel (NPCA switching conditions) may be as follows.

[0075] 1) If the NPCA STA receives a PPDU on the main channel of the BSS and / or receives a PHY-RXSTART.indication primitive for a HE / EHT / UHR PPDU, and all of the following conditions are satisfied:

[0076] A. When the above-mentioned PPDU is classified as an inter-BSS PPDU

[0077] B. When the duration value of the above-described PPDU or the 'duration + TXOP_DURATION value of the RXVECTOR parameter' of the above PPDU is greater than the most recently received or transmitted NPCA Minimum Duration Threshold value in the corresponding BSS.

[0078] C. When the value of the bandwidth field of the PHY preamble of the above-described PPDU has a bandwidth of 20 / 40 / 80 / 160 MHz, and the PPDU does not occupy the NPCA main channel based on the channel allocation of the operating band of the above-described NPCA STA.

[0079]

[0080] 2) If the NPCA STA receives a PPDU containing a control frame, which is a single control frame exchange process, on the main channel of the BSS, and receives a PPDU containing an initial response frame, and all of the following conditions are satisfied:

[0081] A. When the above-mentioned PPDU(s) are classified as inter-BSS PPDU.

[0082] B. When the TXOP length determined by the value of the duration field of the received frames (control frame, initial response frame) is greater than the most recently received or transmitted NPCA minimum duration threshold value in the corresponding BSS.

[0083] C. When the PPDU bandwidth indicated by the above-described PPDU or the value of the RXVECTOR parameter CH_BANDWIDTH_IN_NON_HT indicates 20 / 40 / 80 / 160 MHz, and the above-described PPDU does not occupy the NPCA main channel based on the channel allocation of the operating band of the above-described NPCA STA.

[0084]

[0085] An NPCA STA that has switched its operating channel to the NPCA main channel according to the conditions described above may perform channel access operations on the NPCA main channel. The NPCA STA may exchange frames with another NPCA STA within at least one of the TXOP it has acquired and the TXOP acquired by another NPCA STA. An NPCA STA operating on the NPCA main channel described above may switch its operating channel to the main channel using information regarding the time when the PPDU transmission / reception of the OBSS or the OBSS TXOP, which was checked to verify whether the initial NPCA switching condition is met, ends. The time when the NPCA STA completes switching its operating channel from the NPCA main channel to the main channel may be the same time when the PPDU transmission / reception of the OBSS or the OBSS TXOP ends, or a time earlier than the time described above, or a time later than the time described above.

[0086] A PHY (physical) and a MAC (medium access control) can operate within a wireless LAN terminal. The PHY is an entity that performs physical layer operations, and the MAC is an entity that performs media access operations to the wireless medium where the PHY operates. The PHY and MAC can exchange information with each other. The information exchanged between the PHY and MAC can be diverse and may be exchanged in the form of primitives. The aforementioned primitives may not be information forms with a fixed format. For example, when information regarding a specific primitive is defined in a wireless LAN system (e.g., IEEE 802.11), the primitive may be a primitive based on the defined information. As a specific example, the PHY can transmit the media occupancy status (e.g., Clear Channel Assessment (CCA) status) to the MAC in the form of 'PHY-CCA.indication primitive'. The 'PHY-CCA.indication primitive' may include status information indicating whether the medium is occupied, channel-list information indicating the occupied channel if the medium is occupied, and other information. A MAC that receives the 'PHY-CCA.indication primitive' transmitted by the PHY can determine the state of the medium and decide whether to perform a medium access operation using the information indicated by the 'PHY-CCA.indication primitive'. The aforementioned primitive may be a structure (or structure) that defines basic information to be exchanged between the PHY and the MAC. That is, the occurrence (or transmission, creation, or sending) of a primitive and the reception of a primitive may signify signaling and / or messaging exchange between logical or physical entities such as the PHY and the MAC. The information exchanged during the signaling and / or messaging exchange process conforms to IEEE 802.11. It may be similar to, but not limited to, the basic form of the primitive defined in the standard, and may have a variety of other forms capable of exchanging the essential information defined by the primitive.

[0087] For example, a PHY may receive a PPDU on the main channel. If the received PPDU indicates that the main channel is occupied, the PHY may transmit a 'PHY-CCA.indication(BUSY, {primary}) primitive' to the MAC, which contains information indicating that the current CCA state is occupied (BUSY) and that the main channel (e.g., BSS main 20 MHz channel) is occupied. Upon receiving the 'PHY-CCA.indication(BUSY, {primary}) primitive' from the PHY, the MAC can recognize that the main channel is occupied. Therefore, the MAC may not perform media access operations (e.g., EDCA operation, backoff operation, etc.) unless it receives the 'PHY-CCA.indication(IDLE) primitive' indicating that the CCA state of the main channel is idle (IDLE). Meanwhile, in the present disclosure, 'PHY-CCA.indication(BUSY) primitive' may be 'PHY-CCA.indication(BUSY, {primary}) primitive' containing occupancy information of the main channel (e.g., BSS main 20MHz channel, NPCA main channel, etc.) described above, but its form may be more diverse.

[0088] The PHY can determine the expected end time of reception of the PPDU by decoding the PPDU's preamble. For example, the PHY can recognize the value of the LENGTH field within the L-SIG field of the PPDU's preamble as the length of the PPDU and determine the expected end time of reception. In other words, it can determine the duration of the PPDU. Until the expected end time of reception, the PHY may not transmit the 'PHY-CCA.indication(IDLE) primitive,' which indicates that the main channel is in an idle state, to the MAC. That is, it transmits the 'PHY-CCA.indication(BUSY) primitive,' which indicates that the main channel is occupied. However, even if the expected reception end time of the PPDU has not been reached, if the MAC transmits the 'PHY-CCARESET.request primitive' instructing the PHY to initialize the CCA state, the PHY may initialize the CCA state (e.g., setting the CCA state to idle, or indicating whether the channel is occupied based on physical layer channel detection that begins after the initialization of the physical layer channel detection state). When the CCA state is initialized, the PHY may transmit the 'PHY-CCA.indication(IDLE) primitive' to the MAC, indicating that the main channel is idle. Specifically, the PHY may set a timer variable based on the time length information of the PPDU. Even if the PHY fails to detect the signal of the PPDU or the energy from the signal, such as in the case of carrier loss during PPDU reception, it may generate the 'PHY-CCA.indication(BUSY) primitive' until the expected transmission completion time of the first detected PPDU. In other words, the PHY can indicate the medium to be busy until the expected completion time of the PPDU transmission, regardless of the actual energy intensity received. MAC is 'PHY-CCARESET.When the 'request primitive' is transmitted, the PHY may stop indicating the medium's occupancy status based on the expected completion time of the previously received PPDU. In other words, the generation of the 'PHY-CCA.indication(BUSY) primitive', which must continue until the expected completion time of the PPDU, is stopped. That is, the PHY no longer considers the expected completion time of the PPDU when indicating the medium's occupancy status and performs the CCA operation by initializing the state associated with the reception of the PPDU. When the PHY receives the 'PHY-CCARESET.request primitive' from the MAC, it may generate the 'PHY-CCA.indication primitive' indicating whether the medium is occupied using PHY energy detection (PHYED) and / or PHY carrier sense (PHYCS). The PHY generates the 'PHY-CCA.indication(IDLE) primitive' if the medium is idle and generates the 'PHY-CCA.indication(BUSY) primitive' if the medium is occupied. Here, the above-described operation PHYCS (PHY carrier sense) is an operation that detects the start of a PPDU for each 20 MHz channel in which the PHY operates, and may include at least one of a PPDU preamble detection operation and a PPDU reception operation. Additionally, the above-described operation PHYED is an operation that detects the strength of a signal or energy (e.g., power) received for each 20 MHz channel in which the PHY operates. According to PHYED, if the strength of the signal or energy detected in each 20 MHz channel is greater than a certain level, the corresponding 20 MHz channel is determined to be in an occupied state, and otherwise, the medium is determined to be in an idle state.

[0089] FIG. 4 is a diagram illustrating a CCA status indication method for wireless LAN sub-channel access operation applied to the present disclosure.

[0090] Referring to FIG. 4, AP 1, AP 2, non-AP STA 1, and non-AP STA 2 may operate in a wireless LAN network. AP 1, AP 2, non-AP STA 1, and non-AP STA 2 may be wireless LAN terminals operating based on the configuration of the wireless LAN network described above in FIG. 3. That is, AP 1 may form BSS 1 and non-AP STA 1 may be connected to AP 1. Also, AP 2 may form BSS 2 and non-AP STA 2 may be connected to AP 2. Additionally, BSS 1 and BSS 2 may be OBSS to each other. Here, at least one of AP 1 and non-AP STA 1 may be a wireless LAN terminal that follows the 'NPCA operation' described above in FIG. 3.

[0091] At least one of AP 1 and non-AP STA 1 can receive a PPDU (401) transmitted from BSS 2. At least one of AP 1 and non-AP STA 1 that receives the PPDU (401) transmitted from BSS 2 can follow the 'CCA status indication method' described in FIG. 3. That is, at least one of the PHYs of AP 1 and non-AP STA 1 can transmit a 'PHY-CCA.indication(BUSY, {primary}) primitive' to the MAC, which indicates that the main channel is occupied as a result of receiving the PPDU (401) transmitted from BSS 2. At least one of the PHYs among AP 1 and non-AP STA 1 can decode the preamble of the PPDU (401) transmitted from the received BSS 2 to recognize the expected end time of reception of the PPDU (401) described above, and may not transmit the 'PHY-CCA.indication(IDLE) primitive' indicating that the main channel is idle until the expected end time of reception of the PPDU (401) to the MAC. That is, transmit the 'PHY-CCA.indication(BUSY) primitive' indicating that the main channel is occupied.

[0092] Here, at least one of AP 1 and non-AP STA 1 may decide to switch the operating channel from the main channel to the NPCA main channel by satisfying the NPCA switching conditions of the NPCA operation described in FIG. 3. At the time of initiating the NPCA switching operation, the MAC of at least one of AP 1 and non-AP STA 1 may transmit a 'PHY-CONFIG.request primitive' to the PHY to modify PHY parameters. PHY parameters may include information related to the operating channel of the PHY. Modifying PHY parameters may change the actual operating frequency and frequency piercing operation of the wireless LAN STA in which the PHY operates. The 'PHY-CONFIG.request primitive' may include a 'PHYCONFIG_VECTOR' containing PHY parameter information to be transmitted. The MAC may transmit the channel number information of the NPCA main channel for NPCA transmission and reception operations to the 'PHYCONFIG_VECTOR'. Here, channel number information may be transmitted along with information specifying that it is an NPCA main channel rather than a BSS main channel, or information specifying that the MAC performs an NPCA operation. Upon receiving 'PHY-CONFIG.request primitive', the PHY can change the channel performing the preamble decoding operation to the channel corresponding to the channel number information of the NPCA main channel.

[0093] As another example, if the MAC transmits 'PHYCONFIG_VECTOR' containing channel number information for the NPCA main channel for NPCA transmit / receive operations, the aforementioned channel number information may not include information specifying that it is the NPCA main channel. That is, the PHY may recognize the channel number information transmitted by the MAC as channel number information for changing the main channel, and may not distinguish whether the channel number information is the main channel or the NPCA main channel. 'PHYCONFIG_VECTOR' may include a disabled subchannel bitmap, which is a bitmap for unused channels (i.e., channels that are cleared without transmitting a signal by performing preamble puncturing during PPDU transmission). The disabled subchannel bitmap may be a bitmap indicating whether the channel is available (non-punctured) or unavailable (punctured) in 20 MHz channel units. For example, an AP may instruct non-AP STAs to the aforementioned disabled subchannel bitmap using management frames (e.g., beacon frames, OMP (operation mode and parameters) frames, probe response frames) and other frames. The disabled subchannel bitmap may include a bitmap used when NPCA STAs operate on the BSS main channel and a bitmap used when operating on the NPCA main channel. The bitmap used when operating on the NPCA main channel may be referred to as the NPCA disabled subchannel bitmap, but is not limited to that name. Additionally, the bitmap used when operating on the BSS main channel may be the disabled subchannel bitmap, but is not limited to that name.For example, an inactive subchannel bitmap may be referred to as a basic inactive subchannel bitmap in this disclosure to distinguish it from an NPCA inactive subchannel bitmap, but this is for convenience of explanation only and is not limited thereto.

[0094] When an NPCA STA switches the channel from the BSS main channel to the NPCA main channel, 'PHYCONFIG_VECTOR' may contain an NPCA inactive subchannel bitmap. The NPCA STA's PHY can detect the changed inactive subchannel bitmap. This allows the NPCA STA to transmit a frame (PPDU) without using the punctured 20 MHz channel. In other words, the NPCA STA can perform preamble puncturing. For example, the NPCA inactive subchannel bitmap may indicate that the BSS main channel is punctured.

[0095] At least one MAC among AP 1 and non-AP STA 1 may transmit 'PHY-CCARESET.request primitive' to PHY at a time when the NPCA switching time transmitted in the frame exchanged during the NPCA negotiation process has elapsed from any of the following times.

[0096] - The point in time when it is decided to perform the NPCA switching operation

[0097] - The point at which NPCA switching operation begins

[0098] - While performing NPCA switching operation

[0099] - The point at which operation begins on the NPCA main channel after completing the NPCA switching operation

[0100] - At the point in time when it is decided to perform the NPCA switching operation, or

[0101] - The point at which NPCA operation begins

[0102]

[0103] A PHY that receives the 'PHY-CCARESET.request primitive' transmitted by at least one MAC among AP 1 and non-AP STA 1 may receive a PPDU and reset the CCA state to the occupied state. That is, the PHY may not always maintain the CCA state in the occupied state until the expected transmission of the PPDU is complete. If the channel is idle as a result of the physical layer CCA operation, the PHY may set it to the idle state. Conversely, if the channel is occupied, the PHY may set it to the occupied state. After the above-described PHY resets the CCA state, it may perform CCA on the NPCA main channel at the time when at least one of AP 1 and non-AP STA 1 starts an operation on the NPCA main channel. If the NPCA main channel is idle as a result of performing the above-described CCA, the above-described PHY may transmit the 'PHY-CCA.indication(IDLE) primitive' to the MAC. A MAC that receives the 'PHY-CCA.indication(IDLE) primitive' transmitted by the PHY can recognize that the NPCA main channel is idle and can perform channel access operations (e.g., EDCA TXOP acquisition operation, EDCA backoff operation, etc.) on the NPCA main channel. Therefore, at least one of the NPCA operations of AP 1 and non-AP STA 1 can be performed smoothly.

[0104] Additionally, the MAC may transmit a 'PHY-CONFIG.request primitive' to the PHY to modify PHY parameters at the time it initiates the operation of returning to the BSS main channel after completing all NPCA operations on the NPCA main channel. PHY parameters may include information related to the PHY's operating channel. Modification of PHY parameters may change the actual operating frequency, frequency piercing operation, and other operations of the wireless LAN STA on which the PHY operates, but is not limited to a specific form. The MAC may include channel number information of the main channel for BSS main channel transmission and reception operations in 'PHYCONFIG_VECTOR'. Here, the aforementioned channel number information may be transmitted together with information specifying that it is the BSS main channel or information specifying that the MAC has terminated the NPCA operation. Upon receiving the 'PHY-CONFIG.request primitive', the PHY may change the channel performing the preamble decoding operation to the channel corresponding to the BSS main channel channel number information.

[0105] As another example, if the MAC includes channel number information of the main channel for BSS main channel transmit / receive operations in 'PHYCONFIG_VECTOR', it may not include information specifying the termination of the NPCA operation. That is, the PHY may recognize the channel number information transmitted by the MAC as channel number information for changing the main channel, and may not distinguish whether the channel number information is information received due to the termination of the NPCA operation. When the NPCA STA switches the channel from the NPCA main channel to the BSS main channel, it may include the default disabled subchannel bitmap used in the BSS main channel in 'PHYCONFIG_VECTOR'. The NPCA STA's PHY can verify the changed default disabled subchannel bitmap. Through this, the NPCA STA may be able to transmit a frame (PPDU) without using the punctured 20 MHz channel. In other words, it can perform a preamble puncturing operation.

[0106] As described above, at least one of AP 1 and non-AP STA 1 receives the PPDU (401) of BSS 2 on the main channel, and the PHY can indicate that the main channel is occupied. Subsequently, at least one of AP 1 and non-AP STA 1 can switch the operating channel to the NPCA main channel if the NPCA operation conditions are met. In the case described above, the MAC can initialize the CCA state of the PHY. When at least one of AP 1 and non-AP STA 1 starts an operation on the NPCA main channel (i.e., when CCA can be performed), the PHY can perform CCA to confirm that the NPCA main channel is idle and can transmit the CCA result to the MAC. That is, the physical layer CCA result channel can indicate that it is idle through the 'PHY-CCA.indication(IDLE) primitive'. The MAC can recognize that the CCA state has changed from the initial occupied state to the idle state. MAC can perform an EDCA TXOP acquisition operation and / or an EDCA backoff operation when the channel performing channel access (here, the NPCA main channel) transitions from an occupied state to an idle state. Thus, as described above, at least one of AP 1 and non-AP STA 1 can access the channel on the NPCA main channel and perform frame transmission and reception. Meanwhile, the NPCA main channel may be detected as occupied even after the PHY initializes the CCA state. In the above case, the PHY can indicate that the physical layer CCA result channel is occupied through the 'PHY-CCA.indication(BUSY) primitive'.

[0107] Meanwhile, when PHY receives a 'PHY-CONFIG.request primitive' from MAC, it may send a 'PHY-CONFIG.confirm primitive' in response. The 'PHY-CONFIG.confirm primitive' may occur at the time when the NPCA switching operation begins, or during the execution of the NPCA switching operation.

[0108] FIG. 5 is a diagram illustrating a CCA status indication method for wireless LAN sub-channel access operation applied to the present disclosure.

[0109] Referring to FIG. 5, AP 1, AP 2, non-AP STA 1, and non-AP STA 2 may operate in a wireless LAN network. AP 1, AP 2, non-AP STA 1, and non-AP STA 2 may be wireless LAN terminals operating based on the configuration of the wireless LAN network described above in FIG. 3. That is, AP 1 may form BSS 1 and non-AP STA 1 may be connected to AP 1. Also, AP 2 may form BSS 2 and non-AP STA 2 may be connected to AP 2. Additionally, BSS 1 and BSS 2 may be OBSS to each other. Here, at least one of AP 1 and non-AP STA 1 may be a wireless LAN terminal that follows the 'NPCA operation' described above in FIG. 3.

[0110] At least one of AP 1 and non-AP STA 1 may have received a PPDU (401) transmitted from BSS 2. At least one of AP 1 and non-AP STA 1 that received the PPDU (401) transmitted from BSS 2 may follow the 'CCA status indication method' described above in FIG. 3. That is, at least one of the PHYs of AP 1 and non-AP STA 1 may transmit a 'PHY-CCA.indication(BUSY, {primary}) primitive' to the MAC, which indicates that the main channel is occupied as a result of receiving the PPDU (401) transmitted from BSS 2. At least one of the PHYs among AP 1 and non-AP STA 1 can decode the preamble of the PPDU (401) transmitted from the received BSS 2 to recognize the expected end time of reception of the PPDU (401) described above, and may not transmit the 'PHY-CCA.indication(IDLE) primitive' indicating that the main channel is idle until the expected end time of reception of the PPDU (401) to the MAC. That is, transmit the 'PHY-CCA.indication(BUSY) primitive' indicating that the main channel is occupied.

[0111] Here, at least one of AP 1 and non-AP STA 1 may decide to switch the operating channel from the main channel to the NPCA main channel by satisfying the NPCA switching conditions of the NPCA operation described in FIG. 3. At least one of the PHYs of AP 1 and non-AP STA 1 may distinguish between the main channel and the NPCA main channel and perform CCA on the main channel and the NPCA main channel. Accordingly, at least one of AP 1 and non-AP STA 1 may distinguish the results of the CCA operation between the main channel and the NPCA main channel and transmit them to the MAC. At the time of starting the NPCA switching operation, the MAC may transmit a 'PHY-CONFIG.request primitive' to the PHY to modify the PHY parameters. The PHY parameters may include information related to the operating channel of the PHY. Modification of the PHY parameters may change the actual operating frequency, frequency piercing operation, and other operations of the wireless LAN STA on which the PHY operates, but is not limited to a specific form. The 'PHY-CONFIG.request primitive' may include a 'PHYCONFIG_VECTOR' containing PHY parameter information to be transmitted. The MAC may include channel number information of the NPCA main channel for NPCA transmission and reception operations in the 'PHYCONFIG_VECTOR'. Here, the channel number information may be transmitted along with information specifying that it is the NPCA main channel rather than the BSS main channel, or information specifying that the MAC performs an NPCA operation. Upon receiving the 'PHY-CONFIG.request primitive', the PHY may change the channel performing the preamble decoding operation to the channel corresponding to the channel number information of the NPCA main channel. The PHY may perform CCA on the NPCA main channel at the time when at least one of AP 1 and non-AP STA 1 starts an operation on the NPCA main channel.If, as a result of performing CCA, the NPCA main channel is idle, the PHY may transmit a 'PHY-NPCACCA.indication(IDLE) primitive' to the MAC indicating that the NPCA main channel is idle. For example, the operation of the PHY transmitting the 'PHY-NPCACCA.indication primitive' to the MAC may be performed only when the PHY receives at least one of the channel number information of the NPCA main channel and information specifying that the channel number information is the NPCA main channel from the MAC. Upon receiving the 'PHY-NPCACCA.indication(IDLE) primitive' transmitted by the PHY, the MAC may recognize that the NPCA main channel is idle and may perform channel access operations (e.g., EDCA TXOP acquisition operation, EDCA backoff operation, etc.) on the NPCA main channel. That is, at least one of the MACs of AP 1 and non-AP STA 1 can use the information indicated by the 'PHY-CCA.indication(BUSY, {primary}) primitive' transmitted as a result of the CCA performed by the PHY on the main channel only on the main channel, and can ignore the information indicated by the 'PHY-CCA.indication(BUSY, {primary}) primitive' while at least one of the AP 1 and non-AP STA 1 is operating on the NPCA main channel.

[0112] The above-described MAC may transmit a 'PHY-CONFIG.request primitive' to the PHY to modify PHY parameters at the time when the operation to return to the BSS main channel begins after completing all NPCA operations on the NPCA main channel. PHY parameters may include information related to the PHY's operating channel. Modification of PHY parameters may change the actual operating frequency, frequency piercing operation, and other operations of the wireless LAN STA on which the PHY operates, but is not limited to a specific form. The MAC may include channel number information of the main channel for BSS main channel transmission and reception operations in 'PHYCONFIG_VECTOR'. Here, the above-described channel number information may include and transmit information specifying that it is the BSS main channel or information specifying that the MAC has terminated the NPCA operation. Upon receiving the 'PHY-CONFIG.request primitive', the PHY may stop generating and transmitting the 'PHY-NPCACCA.indication primitive' and may change the channel performing the preamble decoding operation to the channel corresponding to the channel number information of the BSS main channel.

[0113] As described above, at least one of AP 1 and non-AP STA 1 receives the PPDU (401) of BSS 2 on the main channel, and the PHY can indicate that the main channel is occupied. Subsequently, if at least one of AP 1 and non-AP STA 1 meets the NPCA operation conditions, the operation channel can be switched to the NPCA main channel. When at least one of AP 1 and non-AP STA 1 starts operation on the NPCA main channel (i.e., when CCA can be performed), the PHY can perform CCA to confirm that the NPCA main channel is idle and can transmit the CCA result to the MAC. The MAC can recognize that the CCA status of the NPCA main channel has transitioned from the initial occupied state to the idle state. When the channel performing channel access (here, the NPCA main channel) transitions from the occupied state to the idle state, the MAC can perform at least one of an EDCA TXOP acquisition operation and an EDCA backoff operation. Accordingly, as described above, at least one of AP 1 and non-AP STA 1 can access the channel in the NPCA main channel and perform frame transmission and reception.

[0114] Meanwhile, when the PHY receives the 'PHY-CONFIG.request primitive' from the MAC, it may send the 'PHY-CONFIG.confirm primitive' in response. The 'PHY-CONFIG.confirm primitive' may occur at any of the time when the NPCA switching operation begins, during the NPCA switching operation, or at any other time, and is not limited to a specific form.

[0115] FIG. 6 is a diagram illustrating a CCA status indication method for wireless LAN sub-channel access operation applied to the present disclosure.

[0116] Referring to FIG. 6, AP 1, AP 2, non-AP STA 1, and non-AP STA 2 may operate in a wireless LAN network. AP 1, AP 2, non-AP STA 1, and non-AP STA 2 may be wireless LAN terminals operating based on the configuration of the wireless LAN network described above in FIG. 3. That is, AP 1 may form BSS 1 and non-AP STA 1 may be connected to AP 1. Additionally, AP 2 may form BSS 2 and non-AP STA 2 may be connected to AP 2.

[0117] AP 1 can transmit a trigger frame (e.g., MU-RTS frame, Buffer Status Report Poll (BSRP) frame, etc.) to at least one of the non-AP STAs connected to it. AP 1 can transmit the trigger frame including an 'Intermediate FCS (frame check sequence) (I-FCS, 402)'. The FCS field is a field included for the purpose of confirming the normal reception of a frame (MPDU (MAC protocol data unit)) and is located at the end of the frame so that it can be used by the MAC to determine the normal reception of the frame at the time of end of frame reception. The I-FCS (402) is a field that includes all or part of the FCS field and can be included in the User Info field within the trigger frame. That is, the I-FCS (402) may be a field used to determine the normal reception of the trigger frame before the time of end of trigger frame reception. I-FCS (402) can be used when a wireless LAN terminal receiving a trigger frame needs time to stop the frame reception operation in the middle of receiving the trigger frame and to perform another operation.

[0118] For example, a wireless LAN terminal (e.g., STA 1) receiving a trigger frame may be a DPS STA, which is a wireless LAN terminal that supports dynamic power save (DPS) operation. In the case where an operation mode switching time (e.g., DPS padding delay) must be guaranteed according to the DPS operation in the above-described DPS STA, AP 1 may transmit a trigger frame including an I-FCS (402) such that the time length from the time when the I-FCS (402) is received until the time when the frame reception ends is equal to or longer than the operation mode switching time of the wireless LAN terminal.

[0119] As another example, a wireless LAN terminal (e.g., STA 1) receiving a trigger frame may be a DSO STA, which is a wireless LAN terminal that supports dynamic subband operation (DSO). In the case where an operation channel switching time (e.g., DSO Switching Delay) must be guaranteed according to the DSO operation in the above-described DSO STA, AP 1 may transmit a trigger frame including an I-FCS (402) such that the time length from the time when the I-FCS (402) is received until the time when the frame reception ends is equal to or longer than the operation channel switching time of the wireless LAN terminal.

[0120] As another example, the wireless LAN terminal (e.g., STA 1) receiving the trigger frame may be an EMLSR STA, which is a wireless LAN terminal that supports EMLSR (enhanced multi-link single radio). While the aforementioned EMLSR STA is operating in listening mode according to EMLSR operation, it may receive an ICF (e.g., trigger frame) transmitted by AP 1, and a preparation time (e.g., EMLSR padding delay) for operation on the link that received the ICF may be guaranteed. AP 1 may transmit the ICF (trigger frame) by including the I-FCS (402) such that the time length from the time the I-FCS (402) is received until the time the frame reception ends is equal to or longer than the EMLSR padding delay of the EMLSR STA.

[0121] At least one of the non-AP STAs that receives the trigger frame transmitted by AP 1 may follow the 'CCA status indication method' described in Fig. 3. That is, at least one PHY of the non-AP STA may transmit a 'PHY-CCA.indication(BUSY, {primary}) primitive' to the MAC, indicating that the main channel is in an occupied state as a result of receiving the trigger frame. At least one PHY of the non-AP STA may decode the preamble of the received trigger frame to recognize the expected end time of reception of the PPDU. At least one of the non-AP STAs may not transmit a 'PHY-CCA.indication(IDLE) primitive' to the MAC, indicating that the main channel is idle until the expected end time of reception of the PPDU. That is, at least one PHY of the non-AP STA may transmit a 'PHY-CCA.indication(BUSY) primitive', indicating that the main channel is in an occupied state.

[0122] Here, at least one of the non-AP STAs can check the I-FCS (402) within the trigger frame transmitted by AP 1 and confirm that the frame has been successfully received. For example, if at least one of the non-AP STAs performs a DPS operation, a DSO operation, and / or an EMLSR operation and requires a change in the operation channel (or bandwidth), the MAC of at least one of the non-AP STAs can transmit a 'PHY-CONFIG.request primitive' to the PHY to modify the PHY parameters.

[0123] PHY parameters may include information related to the operating channel of the PHY. Modification of PHY parameters may change the actual operating frequency and frequency punching operation of the wireless LAN STA on which the PHY operates. The 'PHY-CONFIG.request primitive' transmitted by the MAC to the PHY may include a 'PHYCONFIG_VECTOR' containing the PHY parameter information to be transmitted. The MAC may include channel (or bandwidth) used in DPS operation, DSO subband channel, and / or EMLSR link (channel) information in the 'PHYCONFIG_VECTOR'. Upon receiving the 'PHY-CONFIG.request primitive', the PHY may change at least one of the channels and / or bandwidths for performing preamble decoding operations to the channel and / or bandwidth specified by the 'PHYCONFIG_VECTOR'.

[0124] At least one MAC among the non-AP STAs can check the I-FCS (402) and, if the normal reception of the frame is confirmed, transmit 'PHY-CCARESET.request primitive' to the PHY. The time at which at least one MAC among the non-AP STAs transmits 'PHY-CCARESET.request primitive' to the PHY can vary from the time when the I-FCS (402) is confirmed, during the wireless LAN operation (e.g., DPS mode switching, DSO channel switching, EMLSR operation, etc.) after the I-FCS (402) is confirmed, the time when the wireless LAN operation is completed, and any other time, and is not limited to a specific time.

[0125] A PHY that receives the PHY-'CCARESET.request primitive' transmitted by at least one MAC among the non-AP STAs can receive a trigger frame and reset the CCA state set to the occupied state. That is, the PHY described above can set the CCA state to the idle state without maintaining the CCA state in the occupied state. After resetting the CCA state, the PHY can perform CCA using the newly configured channel and / or bandwidth via the 'PHY-CONFIG.request primitive' at the time when at least one of the non-AP STAs starts wireless LAN operation (e.g., when transmission and reception begin after DPS mode switching is complete, when transmission and reception begin after channel switching to a DSO subband is complete, when operation begins on an EMLSR link that has received an ICF (trigger frame), etc.). If the channel is idle as a result of performing CCA, the PHY described above can transmit the 'PHY-CCA.indication(IDLE) primitive' to the MAC. A MAC that receives the 'PHY-CCA.indication(IDLE) primitive' transmitted by the PHY can recognize that the channel is idle and can perform channel access operations (e.g., EDCA operation, backoff operation, etc.).

[0126] As another example, at least one of the non-AP STAs that received the trigger frame can transmit a response frame (e.g., CTS frame, BSR frame, Data frame, etc.) to the trigger frame only if the channel allocated through the trigger frame is idle, based on the CCA result during the SIFS (short interframe space) after receiving the trigger frame, when the 'CS required bit' of the trigger frame is set to 1. Here, at least one of the non-AP STAs that performed the above-described CCA reset method can complete preparations to perform wireless LAN operations until the end of receiving the trigger frame after checking the I-FCS (402), and can perform CCA during the SIFS time by resetting the CCA state even before the end of receiving the trigger frame. That is, at least one of the non-AP STAs can perform a CS operation after receiving the trigger frame and transmit a response frame to the trigger frame.

[0127] As described above, at least one of the non-AP STAs can receive a trigger frame (or ICF) transmitted by AP 1, and the PHY can indicate via MAC that the main channel is occupied. Subsequently, at least one of the non-AP STAs can receive the I-FCS (402) within the trigger frame to confirm the normal reception of the frame, and may no longer perform the trigger frame reception operation and instead perform a wireless LAN operation that it supports (e.g., DPS, DSO, EMLSR). In the above case, the MAC can initialize the CCA state of the PHY. The PHY can perform CCA for the SIFS time after receiving a trigger frame after at least one of the non-AP STAs starts wireless LAN operation (e.g., when transmission and reception begin after DPS mode switching is complete, when transmission and reception begin after channel switching to a DSO subband is complete, or when transmission and reception begin after preparation time for operation on the link that received the ICF (trigger frame)), thereby confirming that the channel (or bandwidth) on which the PHY is currently operating is idle, and can transmit the CCA result to the MAC. That is, the MAC can successfully perform CCA and transmit a response frame when the 'CS required bit' of the trigger frame is set to 1.

[0128] Meanwhile, when the PHY receives the 'PHY-CONFIG.request primitive' from the MAC, it may send the 'PHY-CONFIG.confirm primitive' in response. The 'PHY-CONFIG.confirm primitive' may occur at any of the time when the NPCA switching operation begins, during the NPCA switching operation, or at any other time, and is not limited to a specific form.

[0129] FIG. 7 is a flowchart illustrating the operation of an STA in a wireless LAN to which the present disclosure applies. Referring to FIG. 7, the STA can detect the transmission of an overlapping basic service set (OBSS) on the main channel (S710). Here, the transmission of the OBSS may include the transmission of a physical layer protocol data unit (PPDU) of the OBSS. After that, the STA may start switching the operating channel from the primary channel to the NPCA primary channel based on the NPCA (non-primary channel access) switching condition (S720). Here, the STA's PHY (physical) layer receives a first primitive for modifying PHY parameters from the STA's MAC (medium access control) layer (S730), and the STA's PHY layer may transmit a second primitive to the STA's MAC layer in response to the first primitive (S740). After that, the STA's PHY layer receives a third primitive for initializing the CCA (clear channel assessment) state from the STA's MAC layer (S750), and the STA's PHY layer may initialize the CCA state set to the occupied state by the transmission of OBSS based on the third primitive (S760). Here, the STA may complete the switching of the operating channel to the NPCA primary channel before the end of the transmission of OBSS and perform a channel access operation based on the initialized CCA state.

[0130] For example, the PHY layer of the STA may perform CCA when operating on the NPCA main channel based on the third primitive, and if the NPCA main channel is idle as a result of the CCA performance, the fourth primitive may be passed to the MAC layer of the STA. Additionally, when the STA determines to switch the operating channel to the NPCA main channel based on the transmission of OBSS and starts the switching to the NPCA main channel, the first primitive may be generated at the MAC layer of the STA and passed to the PHY layer of the STA. The first primitive includes a PHY configuration vector, and the PHY configuration vector may include NPCA main channel parameters and NPCA inactive subchannel bitmap parameters.

[0131] Additionally, the NPCA main channel parameter may include a value indicating the NPCA main channel on which the STA operates, as indicated by the NPCA operation parameter received by the STA. The NPCA main channel parameter may further include information indicating that the STA performs an NPCA operation. Additionally, the NPCA inactive subchannel bitmap parameter may include a value indicating the subchannel that is disabled in the NPCA operation, as indicated by the NPCA operation parameter received by the STA. Here, the NPCA inactive subchannel bitmap parameter may indicate that the main channel of the basic service set (BSS) containing the STA is disabled. Additionally, if the STA's PHY layer detects transmission by the OBSS, the STA's PHY layer detects the OBSS's physical layer protocol data unit (PPDU) and, based on the transmission completion time information of the OBSS's PPDU, may maintain the CCA state in an occupied state until the transmission completion time of the OBSS's PPDU. In addition, when the PHY layer of the STA initializes the CCA state set to an occupied state by the transmission of the OBSS based on the third primitive, the PHY layer of the STA initializes the transmission completion time information of the PPDU of the OBSS so that the CCA state can be set independently of the transmission completion time of the PPDU of the OBSS.

[0132] Additionally, when the STA begins to return to the main channel after operating on the NPCA main channel, a first primitive may be generated at the MAC layer of the STA and passed to the PHY layer of the STA. Here, the first primitive includes a PHY configuration vector, and the PHY configuration vector may include BSS main channel parameters and BSS inactive subchannel bitmap parameters.

[0133] Additionally, the BSS main channel parameter may include a value indicating the main channel on which the STA operates. The BSS inactive subchannel bitmap parameter may include a value indicating a subchannel that is disabled when the STA operates on the main channel. Additionally, the third primitive may be characterized by being generated before the transmission of the PPDU of the OBSS detected on the main channel is terminated during the process of the STA switching the operating channel from the main channel to the NPCA main channel, and being transmitted to the STA's PHY layer. Additionally, the first primitive may be generated while performing the channel switching operation to the NPCA main channel and transmitted to the STA's PHY layer, and in response to the first primitive, the second primitive may be generated before the NPCA switching delay expires and transmitted to the STA's MAC layer. When the second primitive is transmitted to the STA's MAC layer, the third primitive may be generated.

[0134] Additionally, the transmission of the OBSS detected in the main channel includes a trigger frame, and the MAC layer of the STA can confirm the normal reception of the trigger frame based on the Intermediate Frame Check Sequence (I-FCS) field included in the trigger frame before the end of reception of the trigger frame, and generate a first primitive and a third primitive. Additionally, the trigger frame may further include a padding field set so that the time length from the end of reception of the I-FCS field to the end of reception of the trigger frame is greater than or equal to the switching delay required to switch the operating channel. Additionally, the NPCA switching condition can be satisfied when the remaining duration until the expected end of reception of the OBSS transmission detected in the main channel is greater than a preset NPCA minimum duration threshold.

[0135] For example, the first primitive may be PHY-CONFIG.request primitive, the second primitive may be PHY-CONFIG.confirm primitive, the third primitive may be PHY-CCARESET.request primitive, and the fourth primitive may be PHY-CCA.indication(IDLE) primitive.

[0136] When the STA completes the operation channel switch to the NPCA main channel and performs a channel access operation, the STA may perform at least one of an EDCA (enhanced distributed channel access) TXOP (transmit opportunity) acquisition operation and an EDCA backoff operation based on the initialized CCA state. Additionally, as an example, the STA may be a non-AP STA or an AP STA.

[0137] 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.

[0138]

[0139] 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, The above STA detects the transmission of an overlapping basic service set (OBSS) on the main channel, wherein the transmission of the OBSS includes the transmission of a physical layer protocol data unit (PPDU) of the OBSS; A step in which the above STA starts switching the operating channel from the main channel to the NPCA main channel based on the NPCA (non-primary channel access) switching condition; A step in which the PHY (physical) layer of the STA receives a first primitive for modifying PHY parameters from the MAC (medium access control) layer of the STA; The step of the PHY layer of the STA transmitting a second primitive to the MAC layer of the STA in response to the first primitive; The step of the PHY layer of the STA receiving a third primitive that initializes the CCA (clear channel assessment) state from the MAC layer of the STA; and The PHY layer of the STA includes the step of initializing a CCA state set to an occupied state by the transmission of the OBSS based on the third primitive, wherein A method of operation in which the above STA completes the operation channel switching to the above NPCA main channel before the termination of transmission of the above OBSS and performs a channel access operation based on the above CCA state that has been initialized.

2. In Paragraph 1, A method of operation in which the PHY layer of the STA performs CCA when operating on the NPCA main channel based on the third primitive, and if the NPCA main channel is idle as a result of the CCA performance, transmits the fourth primitive to the MAC layer of the STA.

3. In Paragraph 1, A method of operation in which, when the STA determines to switch the operating channel to the NPCA main channel based on the transmission of the OBSS and starts the switching of the operating channel to the NPCA main channel, the first primitive is generated at the MAC layer of the STA and transmitted to the PHY layer of the STA.

4. In Paragraph 3, A method of operation in which the first primitive includes a PHY setting vector, and the PHY setting vector includes NPCA main channel parameters and NPCA inactive subchannel bitmap parameters.

5. In Paragraph 4, A method of operation in which the above NPCA main channel parameter includes a value indicating the NPCA main channel in which the STA operates, indicated through the NPCA operation parameter received by the STA.

6. In Paragraph 5, A method of operation in which the above NPCA main channel parameter further includes information indicating that the STA performs an NPCA operation.

7. In Paragraph 3, A method of operation in which the above NPCA inactive subchannel bitmap parameter includes a value indicating a subchannel that is disabled in NPCA operation, indicated through the NPCA operation parameter received by the STA.

8. In Paragraph 7, A method of operation in which the above NPCA inactive subchannel bitmap parameter indicates that the main channel of the BSS (basic service set) containing the above STA is inactive.

9. In Paragraph 1, A method of operation in which, when the PHY layer of the STA detects the transmission of the OBSS, the PHY layer of the STA detects the PPDU (physical layer protocol data unit) of the OBSS and maintains the CCA state in a occupied state until the transmission completion time of the PPDU of the OBSS based on information regarding the transmission completion time of the PPDU of the OBSS.

10. In Paragraph 9, A method of operation in which, when the PHY layer of the STA initializes a CCA state set to an occupied state by the transmission of the OBSS based on the third primitive, the PHY layer of the STA initializes the transmission completion time information of the PPDU of the OBSS to set the CCA state independently of the transmission completion time of the PPDU of the OBSS.

11. In Paragraph 1, A method of operation in which, when the STA starts returning to the main channel after operating on the NPCA main channel, the first primitive is generated at the MAC layer of the STA and transmitted to the PHY layer of the STA, wherein the first primitive includes a PHY setting vector, and the PHY setting vector includes BSS main channel parameters and BSS inactive subchannel bitmap parameters.

12. In Paragraph 11, A method of operation in which the above BSS main channel parameter includes a value indicating the main channel in which the above STA operates.

13. In Paragraph 11, A method of operation in which the above BSS inactive subchannel bitmap parameter includes a value indicating a subchannel that is disabled when the above STA operates on the main channel.

14. In Paragraph 1, A method of operation characterized in that the above third primitive is generated before the transmission of the PPDU of the OBSS detected in the main channel is terminated during the process in which the STA switches the operating channel from the main channel to the NPCA main channel, and is transmitted to the PHY layer of the STA.

15. In Paragraph 14, A method of operation in which the first primitive is generated while performing a channel switching operation to the NPCA main channel and is transmitted to the PHY layer of the STA, and in response to the first primitive, the second primitive is generated before the NPCA switching delay expires and is transmitted to the MAC layer of the STA, and when the second primitive is transmitted to the MAC layer of the STA, the third primitive is generated.

16. In Paragraph 1, A method of operation characterized in that the transmission of the OBSS detected in the main channel includes a trigger frame, and the MAC layer of the STA confirms the normal reception of the trigger frame based on the I-FCS (Intermediate Frame Check Sequence) field included in the trigger frame before the end of reception of the trigger frame, and generates the first primitive and the third primitive.

17. In Paragraph 16, A method of operation characterized in that the trigger frame further includes a padding field configured such that the time length from the time of completion of reception of the I-FCS field to the time of termination of reception of the trigger frame is greater than or equal to the switching delay required to switch the operation channel.

18. In Paragraph 1, A method of operation characterized in that the above NPCA switching condition is satisfied when the remaining duration until the expected end of reception of the OBSS transmission detected in the main channel is greater than a preset NPCA minimum duration threshold.

19. In Paragraph 2, The first primitive mentioned above is a PHY-CONFIG.request primitive, and The above second primitive is a PHY-CONFIG.confirm primitive, and The above third primitive is the PHY-CCARESET.request primitive, and The above fourth primitive is a method of operation that is a PHY-CCA.indication(IDLE) primitive.

20. In Paragraph 1, A method of operation in which, when the STA completes an operation channel switch to the NPCA main channel and performs the channel access operation, the STA performs at least one of an EDCA (enhanced distributed channel access) TXOP (transmit opportunity) acquisition operation and an EDCA backoff operation based on the initialized CCA state.

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

22. 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 STA to perform a specific operation by the at least one processor, and The above specific operation is: Detect the transmission of an overlapping basic service set (OBSS) on the main channel, wherein the transmission of the OBSS includes the transmission of a physical layer protocol data unit (PPDU) of the OBSS, and Based on the NPCA (non-primary channel access) switching condition, the operation channel is switched from the primary channel to the NPCA primary channel, and The PHY (physical) layer of the above STA receives a first primitive for modifying PHY parameters from the MAC (medium access control) layer of the above STA, and The PHY layer of the STA transmits a second primitive to the MAC layer of the STA in response to the first primitive, and The PHY layer of the STA receives a third primitive that initializes the CCA (clear channel assessment) state from the MAC layer of the STA, and The PHY layer of the STA initializes the CCA state set to an occupied state by the transmission of the OBSS based on the third primitive, wherein the STA completes an operating channel switch to the NPCA main channel before the end of the transmission of the OBSS and performs a channel access operation based on the initialized CCA state.

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