Method and apparatus for performing low capability return in wireless LAN

Abstract

In a wireless LAN system, an STA may: receive an ICF, the STA being an STA supporting a DPS operation, and the ICF including an operation mode-related request; transmit an ICR in response to the ICF; determine an operation mode on the basis of whether the operation mode-related request is allowed; and communicate with another STA on the basis of the determined operation mode.

Description

Method and device for performing low capability recovery in wireless LAN

[0001] The present disclosure relates to a method and apparatus for performing a low-capacity recovery while performing a service period-based dynamic power saving operation in a wireless local area network (WLAN). Additionally, the disclosure relates to a method and apparatus for negotiating a service period (SP) that sets the period during which wireless LAN terminals operate in a specific mode, and switching to the set mode based on the negotiation.

[0002]

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

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

[0005] As applications requiring higher reliability emerge, the IEEE 802.11bn standard, an Ultra High Reliability (UHR) wireless LAN technology, is being developed for single Basic Service Set (BSS) environments and / or redundant BSS environments. The goal of the IEEE 802.11bn standard may be to support improved data transmission speeds, enhanced latency performance, and reduced data error rates. Additionally, the IEEE 802.11bn standard can support low-power operation, peer-to-peer communication, and operations designed to increase channel utilization. It can also support a TXOP sharing method, where wireless LAN terminals share communication resources called TXOPs (transmit opportunities) between access points (APs). Furthermore, to increase the efficiency of communication resource utilization, the wireless LAN standard can support non-primary channel access (NPCA) operations, which use a channel other than the primary channel when the primary channel is occupied, and dynamic subchannel operation (DSO). In addition, the Wireless LAN may support Dynamic Power Save (DPS) to improve the power saving performance of the Wireless LAN terminal. The following describes a method in which a Wireless LAN terminal supporting DPS negotiates a service period (SP) and switches to a configured mode based on the negotiation, in accordance with the above description.

[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 performing a low-capacity return during the performance of a service period-based dynamic power saving operation in a wireless LAN.

[0009] The present disclosure relates to a method and apparatus for negotiating an SP that sets the period during which wireless LAN terminals operate in a higher capability mode (HCM) in a wireless LAN, and for switching from an HCM SP to HCM based on the negotiation.

[0010] The present disclosure relates to a method and apparatus for controlling the end time of an HCM SP and switching the operation mode based on the length of a transmit opportunity (TXOP) obtained by a wireless LAN terminal within a BSS during an HCM SP when an HCM SP is negotiated in a wireless LAN.

[0011] The present disclosure relates to a method and apparatus for negotiating a SP to set a period during which wireless LAN terminals operate in a lower capability mode (LCM) in a wireless LAN, and for switching from an LCM SP to LCM based on the negotiation.

[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 receiving an initial control frame (ICF), wherein the STA is a STA that supports dynamic power saving (DPS) operation, and the ICF includes a request related to the operation mode, and the step of transmitting an initial control response (ICR) in response to the ICF, and the step of determining the operation mode based on the request related to the operation mode, and performing communication with the STA that transmitted the initial control frame based on the determined operation mode.

[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 the at least one processor, wherein the specific operation is: receiving an initial control frame (ICF), wherein the STA is a STA that supports dynamic power saving (DPS) operation, wherein the ICF includes a request related to the operation mode, and in response to the ICF, an initial control response (ICR) is transmitted, wherein the ICR includes a response indicating whether to allow the request related to the operation mode, and the operation mode is determined based on whether the request related to the operation mode is allowed, and communication with another STA is performed based on the determined operation mode.

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

[0017] According to one embodiment of the present specification, the ICR includes a response indicating whether to allow a request related to an operation mode, and whether to allow a request related to an operation mode may be determined based on a determined operation mode.

[0018] Additionally, according to one embodiment of the present specification, a request related to an operation mode may be a request regarding whether to fix the operation mode to a specific mode for a preset period, or a request regarding whether to maintain the operation mode in an existing mode for a preset period.

[0019] Additionally, according to one embodiment of the present specification, when a STA operating in a lower capability mode (LCM) receives an ICF, the STA may determine whether to maintain the LCM based on a request related to the operating mode and may instruct another STA whether to maintain the LCM through an ICR.

[0020] Additionally, according to one embodiment of the present specification, when the STA maintains the LCM based on a request related to the operation mode, the ICR includes information indicating the permission of the request related to the operation mode, and when the STA switches from the LCM to a higher capability mode (HCM) based on a request related to the operation mode, the ICR may include information indicating the rejection of the request related to the operation mode.

[0021] Additionally, according to one embodiment of the present specification, the ICF is transmitted from another STA operating as an LCM, and after the ICF transmission, the operating mode of the other STA may be switched from LCM to HCM.

[0022] Additionally, according to one embodiment of the present specification, the ICF may further include a padding field for a switching delay time based on an operation mode switching.

[0023] Additionally, according to one embodiment of the present specification, a request related to the operation mode may indicate at least one of a period of operation fixed as HCM (HCM service period, HCM SP) and a period of operation fixed as LCM (LCM service period, LCM SP).

[0024] In addition, according to one embodiment of the present specification, when an STA obtains a request related to the operation mode for an HCM SP, the STA may operate as an HCM during the HCM SP and perform frame exchange with another STA.

[0025] In addition, according to one embodiment of the present specification, if there are no frames to be transmitted at the time of HCM SP termination after the STA has completed frame exchange with another STA, the HCM may switch the operating mode to LCM.

[0026] In addition, according to one embodiment of the present specification, if the end time of the HCM SP is earlier than the end time of the transmit opportunity (TXOP) in which the other STA participated after the frame exchange between the STA and the other STA is completed, the STA may not transmit a frame to the other STA during the operation mode switching time in which the other STA switches the operation mode based on the end of the TXOP.

[0027] In addition, according to one embodiment of the present specification, if the end time of the HCM SP is earlier than the end time of the TXOP in which the other STA participated after the frame exchange between the STA and the other STA is completed, the TXOP is terminated together at the end time of the HCM SP, and the STA and the other STA can switch their operating modes simultaneously at the end time of the HCM SP.

[0028] In addition, according to one embodiment of the present specification, if the end time of the HCM SP is earlier than the end time of the TXOP in which the other STA participated after the frame exchange between the STA and the other STA is completed, the STA and the other STA switch their operating modes simultaneously at the end time of the HCM SP, and communication within the TXOP can be performed by the other STA operating as an LCM.

[0029] Additionally, according to one embodiment of the present specification, the operation mode may include a lower capability mode (LCM) in which at least one of the operation bandwidth, the number of spatial streams (NSS), and the MCS index is limited based on the DPS operation, and a higher capability mode (HCM) in which the general transmit and receive operation of the STA is possible.

[0030] In addition, according to one embodiment of the present specification, the HCM may be an operating mode without any restrictions other than the upper limit of the operating capability of the wireless LAN terminal.

[0031] Additionally, according to one embodiment of the present specification, when the STA switches the operation mode from LCM to HCM, the STA switches the operation mode from LCM to HCM during the operation mode switching time, and when the STA switches the operation mode from HCM to LCM, the STA can switch the operation mode from HCM to LCM during the operation mode return time.

[0032] Additionally, according to one embodiment of the present specification, at least one of the STA and the other STA may be a non-AP STA or an AP STA.

[0033]

[0034] According to the present disclosure, a method for performing a low-capacity recovery during a service period-based dynamic power saving operation in a wireless LAN can be provided.

[0035] According to the present disclosure, a method can be provided to negotiate an SP that sets the period during which wireless LAN terminals operate as HCM in a wireless LAN, and to switch from an HCM SP to HCM based on the negotiation.

[0036] According to the present disclosure, when an HCM SP is negotiated in a wireless LAN, a method can be provided to adjust the timing of the termination of the HCM SP based on the length of the TXOP acquired by the wireless LAN terminal in the BSS during the HCM SP and to switch the operation mode.

[0037] According to the present disclosure, a method can be provided to negotiate an SP to set a period during which wireless LAN terminals operate as LCM in a wireless LAN, and to switch from an LCM SP to an LCM based on the negotiation.

[0038] 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.

[0039] 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.

[0040]

[0041] FIG. 1 is a diagram showing a communication node within a wireless LAN system to which the present disclosure applies.

[0042] FIG. 2 is a drawing showing a wireless LAN system to which the present disclosure is applied.

[0043] FIG. 3 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applied to the present disclosure.

[0044] FIG. 4 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applied to the present disclosure.

[0045] FIG. 5 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applied to the present disclosure.

[0046] FIG. 6 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applicable to the present disclosure.

[0047] FIG. 7 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applied to the present disclosure.

[0048] FIG. 8 is a flowchart showing the operation of a STA in a wireless LAN to which the present disclosure applies.

[0049]

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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."

[0057] 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.

[0058] 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).

[0059] 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).

[0060] 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).

[0061] 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.

[0062] 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.

[0063] To improve the power saving performance of wireless LAN terminals in a wireless LAN, dynamic power saving (DPS) may be supported. A wireless LAN terminal supporting DPS may operate in a lower capability mode (LCM) that limits its operational capabilities (e.g., number of spatial streams, operational bandwidth or channels, modulation coding scheme (MCS), etc.). A wireless LAN terminal operating in LCM may perform or wait for communication, and then switch to a higher capability mode (HCM) to perform or wait for communication when traffic requiring transmission occurs in its transmit queue (or when requested by another wireless LAN terminal). Here, a wireless LAN terminal supporting DPS operation may require a switching time and / or switch back time to switch its operational capabilities. The switching time may vary depending on the implementation specifications of the STA and the configuration of the operational capability the STA intends to switch, and information regarding the switching time may be exchanged with other STAs within the BSS. Additionally, a wireless LAN terminal that supports DPS operation (e.g., AP 1, non-AP STA 1) can negotiate the use of DPS operation with other wireless LAN terminals that support DPS operation within the BSS. Here, the wireless LAN terminals participating in the negotiation (e.g., AP 1, non-AP STA 1) can negotiate a service period (e.g., HCM service period (HCM SP)) during which they perform communication or wait while fixing their operation mode to HCM through the DPS operation negotiation. A wireless LAN terminal that has negotiated the HCM SP can fix its operation mode to HCM during the negotiated period.A wireless LAN terminal that has negotiated an HCM SP can switch its operating mode back from HCM to LCM at the end of the HCM SP. However, another wireless LAN terminal (e.g., non-AP STA 2) that did not participate in the negotiation within the BSS during the HCM SP may access the channel and acquire a TXOP during the HCM SP. In the above case, the wireless LAN terminal that negotiated the HCM SP may not be able to switch its operating mode from HCM to LCM at the end of the HCM SP due to transmission by the wireless LAN terminal that acquired the TXOP. Consequently, channel access by the wireless LAN terminal that negotiated the HCM SP may be delayed, and the channel efficiency of the wireless LAN network may be lowered. Alternatively, the switching back time of the wireless LAN terminal that negotiated the HCM SP may be delayed, and a case may be considered where another wireless LAN terminal transmits a frame to the wireless LAN terminal that negotiated the HCM SP during the switching back time. In the above case, the wireless LAN terminal that negotiated the HCM SP fails to receive the frame, and the EDCA (enhanced distributed channel access) parameter of the wireless LAN terminal that transmitted the frame may increase, and as a result, channel access may be delayed.

[0064] In addition, the timing of channel access via EDCA operations after the HCM SP may differ among DPS terminals that negotiated the HCM SP, and subsequent channel access and frame transmission / reception operations via EDCA operations may not be performed correctly. Therefore, the DPS terminal that negotiated the HCM SP can adjust the TXOP acquired by a wireless LAN terminal that did not participate in the HCM SP negotiation so that it terminates at or before the end of the HCM SP. Through the above, if the timing of the operation mode switching differs after the HCM SP, it is possible to ensure that channel access and frame transmission / reception operations via EDCA operations are performed correctly.

[0065] DPS-supported terminals that have negotiated an HCM SP may require a method to smoothly perform channel access and frame transmission and reception operations through EDCA operations performed after the termination of the HCM SP, and the following describes a method for this.

[0066] Consider a case where AP 1, a wireless LAN terminal (AP station, AP-STA) performing the role of an access point (AP) constituting a basic service set (BSS), and non-AP LAN terminals (non-AP STA) connected to AP 1 (e.g., non-AP STA 1, non-AP STA 2) are in operation. The wireless LAN terminals (e.g., AP 1, non-AP STA 1, non-AP STA 2) can transmit or receive frames. The frames transmitted or received by the wireless LAN terminals may be in the form of a single MPDU (MAC protocol data unit) or an A-MPDU (aggregated-MPDU) within a PPDU (PHY protocol data unit), PSDU (PHY service data unit), or MSDU (MAC service data unit). An A-MPDU may be an MPDU composed of a single MSDU formed by connecting multiple MPDUs separated by a delimiter. However, it may not be limited to the forms described above.

[0067] Wireless LAN terminals (e.g., AP 1, non-AP STA 1, non-AP STA 2) can perform an enhanced distributed channel access (EDCA) operation. The EDCA operation may include at least one of a clear channel assessment (CCA) operation and an EDCA backoff procedure (hereinafter referred to as the backoff procedure). Specifically, wireless LAN terminals (e.g., AP 1, non-AP STA 1, non-AP STA 2) can perform a CCA operation (hereinafter referred to as CCA) on a primary 20 MHz channel. CCA may be an operation to determine whether the channel is idle or busy. As a detailed operation of CCA, physical channel sensing (CS) may be an operation to detect carriers transmitted on the channel. Additionally, virtual CS may be an operation to check whether a network allocation vector (NAV) is established through a successful frame exchange. A wireless LAN terminal can perform CCA for a predetermined IFS (inter-frame space) length (e.g., AIFS (Arbitration IFS)[AC], etc.) depending on the type of frame to be transmitted (e.g., a frame with access category (AC) of VO, VI, BE, BO).

[0068] A wireless LAN terminal (e.g., AP 1, non-AP STA 1, non-AP STA 2) may initiate an EDCA backoff procedure (hereinafter referred to as the backoff procedure). The backoff procedure may be a procedure performed to reduce the probability of collision between wireless LAN terminals. The backoff procedure may be a procedure performed by an EDCAF (EDCA function) corresponding to the type of frame to be transmitted (e.g., AC) within the wireless LAN terminal. The EDCAF of the wireless LAN terminal may initiate the backoff procedure when traffic to be transmitted occurs (e.g., when data is entered into the transmit queue of the AC corresponding to the EDCAF) and the channel is occupied. As another example, the EDCAF of the wireless LAN terminal may initiate the backoff procedure if there is a separate instruction (e.g., when it receives an indicator instructing to start the backoff procedure via frame exchange).

[0069] The EDCAF of the wireless LAN terminal initiating the backoff procedure may randomly select a backoff counter (BC) within [0, CW (Contention Window)[AC]] determined by the associated AC. The BC value selected by the EDCAF associated with each AC may be the number of slots for which the EDCAF must perform CCA. If the channel is occupied as a result of the CCA operation performed by the EDCAF on a slot-by-slot basis, the EDCAF may perform a BC reduction operation in each slot. The slot length of the wireless LAN terminal used in the above-described operation may vary. For example, the slot length may consist of one or more AIFS[AC] times, EIFS[AC] times (EIFS - DIFS - AIFSN[AC] Х aSlotTime + aSIFSTime - aRxTxTurnaroundTime) times, or aSlotTime (e.g., 9us), but is not limited thereto. EDCAF can perform CCA according to the backoff procedure in slots corresponding to the selected BC value, and if the channel resulting from the CCA performed in one slot is idle, it can decrease BC by 1. If the channel resulting from the CCA performed when BC becomes 0 is idle, EDCAF can occupy the channel and perform frame transmission. For example, if the channel resulting from the CCA according to the backoff procedure is in an occupied state, the wireless LAN terminal can maintain its BC at the current value for use in the next backoff procedure. When the channel transitions from an occupied state to an idle state, the wireless LAN terminal (or the wireless LAN terminal's EDCAF) can perform the BC decrease procedure according to the EDCAF operation again.

[0070] The frame transmission procedure through EDCA operation may be a procedure in which a CCA is performed for AIFS[AC] on a primary 20 MHz channel, then a frame is transmitted at the slot boundary where BC becomes 0 after waiting for an additional slot time. The value indicated by AIFS[AC] may be the number of slots for performing CCA. Specifically, AIFS[AC] may be a time length of aSIFS(Short Inter-Frame Space)Time + AIFSN[AC](a number specified per AC)* aSlotTime.

[0071] EDCAF may want to access a wider bandwidth channel (broadband channel) including the main 20 MHz channel. To access the broadband channel, EDCAF may perform CCA on the main 20 MHz channel during AIFS[AC], wait for an additional slot time until BC becomes 0, and then transmit a frame including the broadband channel where the result of the CCA operation performed for a period equal to the PIFS (priority interframe space) time prior to the slot boundary where BC becomes 0 is idle. Alternatively, EDCAF may want to transmit a frame using only the main 20 MHz channel regardless of the CCA result of the broadband channel. In the above case, EDCAF may transmit a frame using only the main 20 MHz channel.

[0072] For example, the EDCA operation performed by an EDCAF within a wireless LAN terminal may be an EDCA operation performed by a wireless LAN terminal (e.g., AP 1, non-AP STA 1, non-AP STA 2). The EDCAF may be a logical entity that performs the aforementioned operation within the wireless LAN terminal, and the EDCA operation may be interpreted as an operation of the wireless LAN terminal. However, it is not limited thereto.

[0073] AP 1 and non-AP STA 1 may be wireless LAN terminals capable of dynamically switching their operational capabilities (e.g., number of spatial streams, operational bandwidth or channels, modulation coding scheme (MCS), etc.) between lower capability mode (LCM) and higher capability mode (HCM). That is, AP 1 and non-AP STA 1 may be DPS (dynamic power save) supported terminals. LCM may be an operational mode in which the wireless LAN terminal performs or waits to transmit or receive using an operational capability smaller than at least one of its maximum operational capabilities (e.g., operational bandwidth of 320 MHz or higher, all available spatial streams, highest MCS value, etc.). For example, a DPS-supported terminal operating in LCM (e.g., AP 1, non-AP STA 1) may only use a bandwidth narrower than its maximum operational bandwidth of 320 MHz (e.g., primary 20 MHz channel). As another example, a DPS-supported terminal operating in LCM (e.g., AP 1, non-AP STA 1) may use only one number of spatial streams (NSS). As another example, a DPS-supported terminal operating in LCM (e.g., AP 1, non-AP STA 1) may perform or wait for transmit / receive operations using the lowest modulation and coding scheme (MCS). Additionally, a DPS-supported terminal operating in LCM (e.g., AP 1, non-AP STA 1) may operate based on the combination described above. That is, a DPS-supported terminal operating in LCM (e.g., AP 1, non-AP STA 1) may operate using a capability smaller than that of a wireless LAN terminal in LCM.

[0074] HCM may be an operating mode in which a wireless LAN terminal performs or waits for transmission and reception using its maximum operating capability. In other words, it is an operating mode in which the wireless LAN terminal uses the maximum operating capability available when not using DPS operation. For example, a DPS-supported terminal (e.g., AP 1, non-AP STA 1) operating in HCM may operate at its maximum operating bandwidth of 320 MHz, use the maximum number of spatial streams (NSS) available, and perform or wait for transmission and reception using the highest modulation and coding scheme (MCS).

[0075] When a DPS-supported terminal dynamically switches its operating mode, the operation mode switching may require operation mode switching time. The operation mode switching time may include the switching time required for the switching operation from LCM to HCM and the switching back time required for the switching back operation from HCM to LCM. The aforementioned operation mode switching times (switching time and switching back time) may vary depending on the performance or operating capability of the DPS-supported terminal. Here, the DPS-supported terminal can exchange information regarding its maximum operating capability and operation mode switching time with other DPS-supported terminals. For example, non-AP STA 1, which is a DPS-supported terminal, can exchange information regarding its maximum operating capability (e.g., 320 MHz operating bandwidth) and operation mode switching time with AP 1, which is a DPS-supported terminal. Here, non-AP STA 1 and AP 1 can be aware of each other's information regarding their maximum operating capability and operation mode switching time. Meanwhile, the above switching time may be referred to as DPS padding delay or padding delay, and the above switching back time may be referred to as DPS transition delay or transition delay.

[0076] A DPS-supported terminal may be unable to perform transmit and receive operations during the operation mode switching time. In other words, a DPS-supported terminal cannot perform frame transmit and receive operations during the switching time. Additionally, a DPS-supported terminal may not be able to perform operations for channel access (e.g., CCA) during the switching time. As another example, a DPS-supported terminal may perform frame transmit and receive operations using only the operational capabilities used by the LCM during the operation mode switching time, but is not limited to this.

[0077] Terminals supporting DPS (e.g., AP 1 and non-AP STA 1) can negotiate a period of operation with a fixed operating mode. For example, AP 1 and non-AP STA 1 can negotiate a period of operation (HCM service period, HCM SP) with their operating mode fixed to HCM. For another example, AP 1 and non-AP STA 1 can negotiate a period of operation (LCM service period, LCM SP) with their operating mode fixed to LCM. For example, negotiation for at least one of the aforementioned HCM SP and LCM SP may be performed based on a request, but is not limited thereto.

[0078] At least one of the above-described HCM SP and LCM SP may be a time interval required for frame exchange between AP 1 and non-AP STA 1. As an example, at least one of the above-described HCM SP and LCM SP may be a TXOP. As another example, at least one of the above-described HCM SP and LCM SP may be a time interval that includes the time required for frame exchange between AP 1 and non-AP STA 1 and the time required for switching the operation mode of non-AP STA 1.

[0079] As a specific example, AP 1 may want non-AP STA 1 to operate with its operating mode fixed to HCM (or LCM) for a certain period. In the above case, AP 1 may transmit a frame containing an HCM SP (or LCM SP) request indicator to non-AP STA 1. The frame containing the HCM SP (or LCM SP) request indicator may be an initial control frame (ICF). The HCM SP (or LCM SP) request indicator may contain information regarding the duration of operation as HCM SP (or LCM SP). If non-AP STA 1 recognizes the HCM SP (or LCM SP) request indicator within a frame transmitted by AP 1, non-AP STA 1 may transmit a frame containing an HCM SP (or LCM SP) response indicator to AP 1. As an example, the frame containing the HCM SP (or LCM SP) response indicator may be an initial control response (ICR). The HCM SP (or LCM SP) response indicator within the frame transmitted by non-AP STA 1 may indicate the result of the HCM SP (or LCM SP) negotiation. For example, non-AP STA 1 may accept the HCM SP (or LCM SP) negotiation request from AP 1. That is, the aforementioned HCM SP (or LCM SP) response indicator may indicate acceptance. In the above case, non-AP STA 1 may operate by fixing its mode of operation to HCM (or LCM) during the HCM SP (or LCM SP) period indicated by the HCM SP (or LCM SP) request indicator within the frame transmitted by AP 1.In the above case, non-AP STA 1 operates by fixing its operating mode to HCM (or LCM) during the time interval corresponding to the time when the TXOP of AP 1 or the frame exchange between AP 1 and non-AP STA 1 is completed, as indicated by the HCM SP (or LCM SP) request indicator within the frame transmitted by AP 1.

[0080] For example, if non-AP STA 1 receives an LCM SP request descriptor from AP 1 and non-AP STA 1 chooses to maintain the LCM operating mode, non-AP STA 1 can transmit an LCM SP response descriptor indicated as accept and maintain the LCM operating mode. Alternatively, if non-AP STA 1 receives an HCM SP request descriptor from AP 1 and non-AP STA 1 chooses to maintain the HCM operating mode, non-AP STA 1 can transmit an HCM SP response descriptor indicated as accept and maintain the HCM operating mode.

[0081] As another example, non-AP STA 1 may reject the HCM SP (or LCM SP) negotiation request from AP 1. That is, the aforementioned HCM SP (or LCM SP) response indicator may indicate a reject. Alternatively, if non-AP STA 1 rejects the request from AP 1, non-AP STA 1 may not transmit a frame containing the HCM SP (or LCM SP) response indicator. In the above case, non-AP STA 1 may perform transmit / receive operations or wait without switching its operating mode. For example, if non-AP STA 1 receives an LCM SP request indicator from AP 1 and non-AP STA 1 chooses not to maintain the operating mode as LCM, non-AP STA 1 may maintain the operating mode as HCM. Alternatively, if non-AP STA 1 receives an HCM SP request descriptor from AP 1 and chooses not to maintain the operation mode as HCM, non-AP STA 1 may maintain the operation mode as LCM. If the response descriptor indicates a rejection, the response descriptor may include a rejection reason. For example, rejection reasons may include insufficient battery capacity, insufficient low-latency data requirements, failure to switch to HCM, unknown reason, and other reasons, and are not limited to a specific form. Here, the rejection reason may serve as a basis for determining whether to forward a future request to switch to HCM, but is not limited thereto. Meanwhile, other methods may be considered in which non-AP STA 1 receives a frame containing an LCM SP request descriptor from AP 1 and instructs AP 1 to accept or reject non-AP STA 1's LCM maintenance operation, and are not limited to a specific form.

[0082] As a specific example, at least one of AP 1 and non-AP STA 1 may operate as LCM. For example, at least one of AP 1 and non-AP STA 1 may operate as LCM considering power consumption, but is not limited thereto. AP 1 may transmit an ICF (trigger frame (e.g., MU-RTS trigger frame, BSRP trigger frame)) to non-AP STA 1 operating as LCM, and the ICF may include an LCM SP request indicator. The LCM SP request indicator included in the ICF may be an indicator requesting non-AP STA 1 to remain as LCM for a specific period, as described above. Here, since non-AP STA 1 is operating as LCM, the LCM SP request indicator may be an indicator requesting non-AP STA 1 to continuously remain as LCM. For example, the LCM SP request indicator may be indicated based on at least one of the bits, fields, and subfields within the ICF and is not limited to a specific form. non-AP STA 1 may receive an ICF and transmit an ICR in response. Here, non-AP STA 1 may receive a request from AP 1 and decide whether to switch the operation mode. If non-AP STA 1 is requested to continue maintaining the LCM based on an LCM SP request indicator, non-AP STA 1 may grant AP 1's request to maintain the LCM. For example, non-AP STA 1 may include a response indicator granting to continue maintaining the LCM in the ICR and transmit it, as described above. On the other hand, non-AP STA 1 may choose not to grant AP 1's request and switch the operation mode from LCM to HCM.For example, non-AP STA 1 may include a rejection response indicator in the ICR to change the operating mode to HCM without continuously maintaining LCM, as described above. Additionally, for example, AP 1 may operate in LCM before transmitting the aforementioned request, and may switch the operating mode to HCM before or after transmitting the aforementioned request. That is, considering power consumption, both AP 1 and non-AP STA 1 may operate in LCM, and AP 1 may transmit the aforementioned request while switching the operating mode from LCM to HCM when a frame to be transmitted to non-AP STA 1 occurs, but is not limited to such embodiments. For example, it is also possible for AP 1 to always operate in HCM.

[0083] Additionally, the ICF may include a padding field considering the switching time for non-AP STA 1 to switch its operating mode based on the LCM SP request indicator (e.g., the switching time required to switch the operating mode from LCM to HCM when non-AP STA 1 does not grant AP 1's LCM SP request), which may be as described above. Furthermore, when AP 1 transmits an ICF containing the LCM SP request indicator to non-AP STA 1, non-AP STA 1 may grant or reject AP 1's request; therefore, AP 1 must consider the case where non-AP STA 1 switches its operating mode to HCM. For example, after the LCM SP of AP 1 and non-AP STA 1 has ended, non-AP STA 1 may have operated in HCM by not granting AP 1's LCM SP request. In the above case, non-AP STA 1 must switch its operating mode to LCM after the time the LCM SP ends. When non-AP STA 1 switches its operating mode from HCM to LCM, a switching back time is required. If there is an additional frame to be transmitted to non-AP STA 1 after the termination of the LCM SP of non-AP STA 1, AP 1 can transmit the frame to non-AP STA 1 by performing an EDCA operation on the main 20 MHz channel after the switching back time. The above-described operation relates to the time during which AP 1 can transmit a frame to non-AP STA 1 due to the switching delay that may occur when AP 1 switches its operating mode from LCM SP or HCM SP to HCM.

[0084] AP 1 can transmit a frame containing an LCM SP request descriptor to non-AP STA 1. Here, the frame containing the LCM SP request descriptor can be transmitted up to the bandwidth available to non-AP STA 1 in the HCM. Here, the frame containing the LCM SP request descriptor can be transmitted in a frame format that is duplicated and transmitted per 20 MHz channel (e.g., Non-HT PPDU format, Non-HT Duplicate PPDU format). Additionally, as an example, the frame containing the LCM SP request descriptor may be a trigger frame (e.g., MU-RTS trigger frame, BSRP trigger frame). The UL BW subfield of the common info field of the frame containing the LCM SP request descriptor may indicate the transmission bandwidth of the frame containing the LCM SP request descriptor. The user info field of the frame containing the LCM SP request descriptor may include the association ID (AID) of non-AP STA 1 and indicate the transmission bandwidth of the frame to which non-AP STA 1 must respond to the frame containing the LCM SP request descriptor. The transmission bandwidth of the response frame to the frame containing the LCM SP request indicator may be specified as the bandwidth available to non-AP STA 1 in HCM. Additionally, the frame containing the LCM SP request indicator may include a padding field longer than the time length (e.g., DPS padding delay) required when non-AP STA 1 switches the operation mode from LCM to HCM.

[0085] AP 1 transmits a frame containing an LCM SP request descriptor, and non-AP STA 1 can receive a frame containing an LCM SP request descriptor. If non-AP STA 1 switches its operating mode to HCM without maintaining the LCM operating mode, after switching to the HCM operating mode, non-AP STA 1 can transmit a response frame (e.g., CTS frame, Multi-STA BlockAck frame), etc., to AP 1 using the transmission bandwidth specified by AP 1, with the bandwidth available to non-AP STA 1 in HCM as the upper limit. In the above case, AP 1 can recognize that non-AP STA 1 is operating in HCM by rejecting the LCM SP request. AP 1 can perform frame exchange with non-AP STA 1, with the communication parameters available to non-AP STA 1 in HCM as the upper limit. Specifically, AP 1 can transmit a frame containing an LCM SP request descriptor, with the bandwidth available in the HCM operating parameters of non-AP STA 1 as the upper limit. Here, the bandwidth available in the HCM operation parameters may be wider than the bandwidth available to non-AP STA 1 in LCM. The bandwidth of a frame that AP 1 can transmit in a TXOP may not be greater than the bandwidth of the frame transmitted most recently in the same TXOP. If non-AP STA 1 switches its operation mode to HCM and a bandwidth wider than the operating bandwidth available to non-AP STA 1 in LCM becomes available, the transmission bandwidth limit may be removed or relaxed, as AP 1 has already transmitted a frame containing an LCM SP request descriptor up to the upper limit of the bandwidth available in the non-AP STA 1 HCM operation parameters.

[0086] When non-AP STA 1 maintains an LCM operating mode, non-AP STA 1 may transmit response frames (e.g., CTS frames, Multi-STA BlockAck frames) to AP 1, with the bandwidth available in LCM as the upper limit. The response frames transmitted by non-AP STA 1 may have a narrower bandwidth than the transmission bandwidth specified by AP 1. In the above case, AP 1 may recognize that non-AP STA 1 is operating as LCM by accepting an LCM SP request. AP 1 may perform frame exchange with non-AP STA 1, with the communication parameters available in LCM as the upper limit. As described above, AP 1 may determine whether non-AP STA 1 accepts or rejects an LCM SP request based on the bandwidth of non-AP STA 1. Here, the above operation may be possible even when an LCM SP (or HCM SP) response indicator is used together and is not limited to a specific form.

[0087] Additionally, AP 1 can force non-AP STA 1 to maintain its operating mode as LCM. Specifically, AP 1 can transmit a frame containing an LCM SP request descriptor to non-AP STA 1. Here, the frame containing the LCM SP request descriptor may not include padding (e.g., padding field) corresponding to the time length (e.g., DPS padding delay) required for non-AP STA 1 to switch its operating mode. In the above case, non-AP STA 1 may be unable to switch its operating mode from LCM to HCM. Therefore, AP 1 can expect that the operating mode of non-AP STA 1 remains as LCM. Here, the frame containing the LCM SP request descriptor of AP 1 may be transmitted up to the bandwidth available to non-AP STA 1 in LCM. Alternatively, if power saving operation is required for AP 1, the frame containing the LCM SP request descriptor of AP 1 may be transmitted up to the bandwidth available to AP 1 in LCM. Frames containing LCM SP request descriptors must be transmitted in a frame format that is duplicated and transmitted per 20 MHz channel (e.g., Non-HT PPDU format, Non-HT Duplicate PPDU format). Frames containing LCM SP request descriptors may be trigger frames (e.g., MU-RTS trigger frame, BSRP trigger frame). The UL BW subfield of the common info field of a frame containing LCM SP request descriptors may indicate the transmission bandwidth of the frame containing LCM SP request descriptors. The user info field of a frame containing LCM SP request descriptors may contain the AID of non-AP STA 1 and indicate the transmission bandwidth of the frame to which non-AP STA 1 must respond to the frame containing LCM SP request descriptors.The transmission bandwidth of the frame that non-AP STA 1 must respond to for a frame containing an LCM SP request descriptor may be specified with the bandwidth available to non-AP STA 1 in the LCM as the upper limit. Alternatively, if AP 1 requires power saving operation, the transmission bandwidth of the frame that non-AP STA 1 must respond to for a frame containing an LCM SP request descriptor may be specified with the bandwidth available to AP 1 in the LCM as the upper limit.

[0088] non-AP STA 1 maintains the operating mode as LCM, and non-AP STA 1 can transmit a response frame (e.g., CTS frame, Multi-STA BlockAck frame) to AP 1 with the bandwidth available in LCM as the upper limit. After that, AP 1 can perform frame exchange with non-AP STA 1 with the communication parameters available in LCM as the upper limit.

[0089] The aforementioned operation mode switching indicator may be included in the form of a field, subfield, or bit within the MAC (medium access control) header or the user info field or common info field of the frame body within the ICF, but is not limited thereto. When a wireless LAN terminal receives a frame containing an operation mode switching indicator of a DPS-supported terminal, the wireless LAN terminal may perform a switching operation (switching from LCM to HCM) or a switching back operation (switching from HCM to LCM) to switch its operation mode.

[0090] If AP 1 transmits a frame containing an LCM SP request descriptor and confirms that non-AP STA 1 is operating in LCM, AP 1 can perform frame exchange with non-AP STA 1 with the communication parameters available to non-AP STA 1 in LCM as an upper limit. If AP 1 needs to transmit additional frames to non-AP STA 1, since non-AP STA 1 continues to maintain its default operating mode of LCM, there is no need to consider the mode transition delay (e.g., DPS Transition Delay, DPS Switch back Delay) required for non-AP STA 1 to switch its operating mode from HCM to LCM, and AP 1 can freely transmit additional frames to non-AP STA 1.

[0091] On the other hand, if AP 1 can confirm that non-AP STA 1 is operating in HCM, AP 1 can perform frame exchange with non-AP STA 1 with the communication parameters available to non-AP STA 1 in HCM as an upper limit. Here, if AP 1 needs to transmit additional frames to non-AP STA 1, it can transmit additional frames until 'aSIFS + aSlotTime' has elapsed from the time when a frame that does not require an immediate acknowledgment frame is transmitted to non-AP STA 1 or from the time when an immediate acknowledgment frame is received from non-AP STA 1. If the aforementioned time has elapsed, non-AP STA 1 must switch its operating mode from HCM to LCM, so the mode switching delay required for non-AP STA 1 to switch its operating mode from HCM to LCM may be taken into account.

[0092] Additionally, AP 1 may transmit additional frames to non-AP STA 1 after the DPS transition delay has elapsed following the completion of frame exchange with non-AP STA 1. Here, the completion time of frame exchange may be as follows.

[0093] Specifically, if AP 1 does not transmit a separate frame within the time interval from the time when a frame for which an immediate response frame is not required is transmitted to non-AP STA 1 or when an immediate response frame is received from non-AP STA 1 until the time 'aSIFSTime + aSlotTime + aRxPHYStartDelay' has elapsed, the time when frame exchange is completed may be the time when aSIFSTime + aSlotTime + aRxPHYStartDelay has elapsed from the time when an immediate response frame is transmitted to non-AP STA 1 or when an immediate response frame is received from non-AP STA 1.

[0094] Alternatively, if AP 1 transmits a separate frame within the time interval from when a frame for which an immediate response frame is not required is transmitted to non-AP STA 1 or when an immediate response frame is received from non-AP STA 1 until the time aSIFSTime + aSlotTime + aRxPHYStartDelay has elapsed, and the frame is not a frame for which non-AP STA 1 is the destination or a trigger frame for which the AID of non-AP STA 1 is specified, the frame exchange time may be the time of completion of transmission of the trigger frame for which non-AP STA 1 is not the destination or the AID of non-AP STA 1 is specified (the time of completion of transmission of the MPDU or the time of completion of transmission of the PPDU).

[0095] After AP 1 transmits a frame containing an LCM SP request descriptor and receives a response frame from non-AP STA 1, if it is not possible to determine whether non-AP STA 1 is operating as HCM or LCM, AP 1 may assume that non-AP STA 1 is operating as HCM. Alternatively, AP 1 may transmit a frame in the LCM SP with the communication parameters available in non-AP STA 1's LCM as the upper limit, but if it is determined that a DPS switching delay has occurred after the end of the LCM SP, it may transmit an additional frame to non-AP STA 1 after the DPS switching delay of non-AP STA 1. However, if the frame containing the LCM SP request indicator does not contain padding (e.g., padding field) corresponding to the time length (e.g., DPS padding delay) required for non-AP STA 1 to switch the operation mode (i.e., if non-AP STA 1 is instructed to operate as LCM), AP 1 may be considered to be in LCM mode without non-AP STA 1 switching the operation mode to HCM.

[0096] In the above-described DPS operation, the terminal transmitting a frame requesting the counterpart operating as the DPS LCM to operate as the HCM is the DPS requestor, and the terminal receiving the frame requesting the terminal operating as the DPS LCM to operate as the HCM may be referred to as the DPS requestee; however, this is for convenience of explanation only and is not limited to such names. Furthermore, the above-described matters may be applied identically to Figures 3 through 7 below, and may also be modified according to the specific operation in each figure.

[0097] In addition, the following items may be applied equally to FIGS. 3 through 7, and the specific operation may differ depending on each figure. For example, the frame requesting operation as HCM is an ICF, and the ICF may include HCM SP information. The above-described DPS requestor or DPS requestee may be determined based on the entity performing the DPS operation, and both STA and AP may be targets. For example, AP 1 supporting DPS (e.g., DPS requestor) and non-AP STA 1 (e.g., DPS requestee) may negotiate an HCM SP (or LCM SP) through frame exchange. AP 1 may be the DPS requestor and non-AP STA 1 may be the DPS requestee, but this is merely for convenience of explanation and is not limited thereto. That is, the above-described entity is a distinction based on the entity performing the DPS operation, and when AP 1 performs the DPS operation, non-AP STA 1 may become the DPS requester and AP 1 may become the DPS requestee. The operations initiated by AP 1 or non-AP STA 1 in this disclosure can be performed identically even if the subjects are reversed; however, for the sake of convenience of explanation, the description is based on the case where AP 1 is the DPS requestor and non-AP STA 1 is the DPS requestee. AP 1 and non-AP STA 1 can negotiate a transition to HCM by exchanging ICFs and ICRs, and can also determine an HCM SP (or LCM SP). Specifically, AP 1 can request a transition to HCM by transmitting an ICF to non-AP STA 1. AP 1 may include an HCM SP request indicator within the ICF transmitted to non-AP STA 1. Upon receiving the HCM SP request indicator within the ICF, non-AP STA 1 may accept or reject AP 1's request to negotiate an HCM SP.non-AP STA 1 may send an ICR to AP 1 to accept or reject an HCM SP negotiation request. non-AP STA 1 may include an HCM SP response indicator in the ICR sent to AP 1 to indicate acceptance or rejection. If the ICR includes an acceptance indicator, non-AP STA 1 may operate with its operating mode fixed to HCM for the duration indicated by the HCM SP request indicator sent by AP 1 (i.e., the time until the end of the HCM SP). Additionally, AP 1 may be aware that non-AP STA 1 operates in HCM until the end of the HCM SP. If the ICR includes a rejection indicator, non-AP STA 1 may reject the HCM transition request made by AP 1 and continue to operate in LCM mode.

[0098] Here, AP 1 and non-AP STA 1 may initially be operating in LCM. When downlink (DL) traffic that needs to be transmitted from AP 1 to non-AP STA 1 occurs, AP 1 may switch to HCM to transmit the DL traffic. After the DL traffic occurs, AP 1 may perform an EDCA operation (e.g., CCA operation and / or EDCA backoff procedure) on the main 20 MHz channel. Based on the result of the EDCA operation performed on the main 20 MHz channel, AP 1 may transmit an initial frame to non-AP STA 1 through at least one of the main 20 MHz channel and the broadband including the main 20 MHz channel, depending on the operational capability used by non-AP STA 1 in LCM. That is, AP 1 may acquire a TXOP (TXOP 1) on the channel (or broadband) including the main 20 MHz channel.

[0099] The initial frame transmitted by AP 1 to non-AP STA 1 may be an ICF. AP 1 may include an operation capability transition indicator in the ICF transmitted to non-AP STA 1. Upon receiving the operation capability transition indicator within the ICF, non-AP STA 1 may perform its own switching operation. Here, the start time of the switching operation performed by non-AP STA 1 may vary. The start time of the switching operation performed by non-AP STA 1 may be the point at which the decoding result of the Frame Check Sequence (FCS) field within the frame containing the operation capability transition indicator is determined to be normal. As another example, the start time of the switching operation performed by non-AP STA 1 may be the point at which the decoding result of the Intermediate FCS field within the frame containing the operation capability transition indicator is determined to be decoded without errors. The Intermediate FCS field may be at least one of the FCS field inserted within the User Info field in the MAC header of the frame and a part of the FCS field.

[0100] non-AP STA 1 may require a time equal to the switching time (which may also be referred to as the DPS padding delay) until the switching operation is completed. AP 1 may be aware of the switching time of non-AP STA 1 in advance and may add padding to the ICF by referencing the longest value among the possible switching times of non-AP STA 1. The padding may be a field added to the end of the frame to extend the frame transmission time. The padding may include, but is not limited to, the Intermediate FCS field described above. non-AP STA 1 may perform the switching operation after receiving at least one of the Intermediate FCS and the FCS field and determining that the decoding result is a normal decoding. When transmitting the ICF, AP 1 may include padding in the ICF by referencing the expected end time of the switching time of non-AP STA 1, and non-AP STA 1 may perform the switching operation after receiving the ICF. non-AP STA 1 can send an ICR to AP 1 after a short interframe space (SIFS) time following the completion of the switching operation or at the time the switching operation ends.

[0101] AP 1, having received the ICR transmitted by the aforementioned non-AP STA 1, can transmit a data frame after receiving the ICR and after the SIFS time. Non-AP STA 1, having received the data frame transmitted by AP 1, can respond with a BlockAck (BA) frame after receiving the data frame and after the SIFS time. Since non-AP STA 1 has completed the transition of the operating mode from LCM to HCM, AP 1 can transmit a frame (e.g., a data frame) using the operating capabilities and parameters available to non-AP STA 1 in HCM (e.g., maximum bandwidth, maximum number of spatial streams, frame format, etc. supported by non-AP STA 1). Non-AP STA 1 can receive the frame transmitted by AP 1 using the parameters and operating capabilities supported by HCM and recognize that AP 1 is operating in HCM. Therefore, non-AP STA 1 can also transmit a response frame (e.g., a BA frame) to AP 1 using the operating capabilities and parameters supported by AP 1 in HCM.

[0102] As another example, AP 1 and non-AP STA 1 may initially be operating in LCM. Here, uplink (UL) traffic that needs to be transmitted to AP 1 may occur on non-AP STA 1. non-AP STA 1 may perform an operation to switch to HCM to transmit the UL traffic. After the UL traffic arrives, non-AP STA 1 may perform an EDCA operation on the main 20 MHz channel (e.g., at least one of a CCA operation and an EDCA backoff procedure). Based on the result of the EDCA operation performed on the main 20 MHz channel, non-AP STA 1 may transmit an initial frame to AP 1 using the main 20 MHz channel and at least one of the broadband including the main 20 MHz channel, using the operational capability that AP 1 uses in LCM. That is, non-AP STA 1 may acquire a TXOP (TXOP 1) on the channel (or broadband) including the main 20 MHz channel.

[0103] The first frame transmitted by non-AP STA 1 to AP 1 may be an ICF. Non-AP STA 1 may include an operation capability transition indicator in the ICF transmitted to AP 1. Upon receiving the operation capability transition indicator within the ICF, AP 1 may perform its switching operation. The start time of the switching operation performed by AP 1 may vary. The start time of the switching operation performed by AP 1 may be the point at which the decoding result of the FCS field within the frame containing the operation capability transition indicator is determined to be successfully decoded. As another example, the start time of the switching operation performed by AP 1 may be the point at which the decoding result of the Intermediate FCS field within the frame containing the operation capability transition indicator is determined to be decoded without errors. The Intermediate FCS field may be at least one of the FCS field inserted within the user info field in the MAC header of the frame and a part of the FCS field.

[0104] AP 1 may require time equal to the switching time to complete the switching operation. non-AP STA 1 may recognize the switching time of AP 1 in advance and may add padding to the ICF by referencing the longest value among the possible switching times of AP 1. The padding may be a field added to the end of the frame to extend the frame transmission time. The padding may include, but is not limited to, the aforementioned Intermediate FCS field. AP 1 may perform the switching operation after receiving at least one of the Intermediate FCS and the FCS field, and after determining that the decoding result is a normal decoding. When transmitting the ICF, non-AP STA 1 may include padding in the ICF by referencing the expected end time of AP 1's switching time, and AP 1 may perform the switching operation after receiving the ICF. AP 1 may transmit an ICR to non-AP STA 1 after the SIFS (short interframe space) time following the completion of the switching operation or at the time the switching operation ends.

[0105] non-AP STA 1, having received the ICR transmitted by the aforementioned AP 1, can transmit a data frame after receiving the ICR and after the SIFS time. AP 1, having received the data frame transmitted by non-AP STA 1, can respond with a BlockAck (BA) frame after receiving the data frame and after the SIFS time. Since AP 1 has completed the transition of the operating mode from LCM to HCM, non-AP STA 1 can transmit a frame (e.g., a data frame) using the operating capabilities and parameters available to AP 1 in HCM (e.g., maximum bandwidth, maximum number of spatial streams, frame format, etc. supported by non-AP STA 1). AP 1 receives the frame transmitted by non-AP STA 1 using the parameters and operating capabilities supported in HCM and can recognize that non-AP STA 1 is operating in HCM. Accordingly, AP 1 can also transmit a response frame (e.g., BA frame) to non-AP STA 1 using the operation capabilities and parameters supported by HCM. Here, the above-described matters may be applied identically in FIGS. 3 to 7, and the specific operations may differ depending on the figure.

[0106] FIG. 3 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on the wireless LAN service period applicable to the present disclosure. FIG. 3 is described based on the case where AP 1 (310) transmits an ICF (401) as a frame requesting operation as HCM, and non-AP STA 1 (320) transmits an ICR (402) in response thereto. That is, AP 1 (310) may be the DPS requestor and non-AP STA 1 (320) may be the DPS requestee, and AP 1 (310) and non-AP STA 1 (320) may negotiate a transition to HCM by exchanging ICF and ICR, and AP 1 (310) may transmit a data frame (403) to non-AP STA 1 (320) and receive a response frame (404) thereto. However, this is for convenience of explanation only and is not limited thereto.

[0107] Referring to FIG. 3, after TXOP 1 initiated by AP 1 (310) or non-AP STA 1 (320) is terminated, wireless LAN terminals within the BSS (e.g., AP 1 (310), non-AP STA 1 (320), non-AP STA 2 (330)) can access the channel and acquire TXOP by performing EDCA operations on the main 20 MHz channel during the HCM SP period. For example, AP 1 (310) can access the channel by performing EDCA operations on the main 20 MHz channel during the HCM SP period and acquire TXOP (TXOP 2) by transmitting an initial frame to non-AP STA 1 (320). For example, the frame initially transmitted by AP 1 (310) to STA 1 may be an ICF. AP 1 (310) can see that non-AP STA 1 (320) is operating in HCM during the HCM SP period, so it can see that non-AP STA 1 (320) does not require switching time to switch the operating mode. Therefore, AP 1 (310) may not include padding in the ICF initially transmitted to non-AP STA 1 (320). Additionally, the ICF may be transmitted using bandwidth within the maximum bandwidth that non-AP STA 1 (320) can support in HCM. Non-AP STA 1 (320), upon receiving the ICF transmitted by AP 1 (310), may send an ICR as a response to AP 1 (310) after receiving the ICF and after SIFS time, using bandwidth within the maximum bandwidth that can operate in HCM. AP 1 (310), which receives the ICR transmitted by non-AP STA 1 (320), can transmit a data frame using bandwidth within the maximum bandwidth supported by HCM after receiving the ICR and SIFS time.A non-AP STA 1 (320) that receives a data frame transmitted by AP 1 (310) can respond by sending a BlockAck (BA) frame to AP 1 (310) after receiving the data frame and SIFS time.

[0108] As another example, referring to FIG. 3, AP 1 (310) may transmit a data frame (405) immediately using bandwidth within the maximum bandwidth that non-AP STA 1 (320) can support in the HCM without transmitting an ICF to non-AP STA 1 (320). Upon receiving the data frame (405) transmitted by AP 1 (310), non-AP STA 1 (320) may respond by transmitting a BA frame (406) to AP 1 (310) after receiving the data frame (405) and after SIFS time. The end time of the HCM SP may be the end time of TXOP 2 or thereafter. AP 1 (310) and non-AP STA 1 (320) that negotiated the HCM SP may perform a switching back operation at the end time of the HCM SP. AP 1 (310) and non-AP STA 1 (320), having performed a switching back operation, can switch their operating mode to LCM and access the channel by performing an EDCA operation on the main 20 MHz channel. The above-described operation may also apply when non-AP STA 1 (320) operates from LCM SP to HCM. That is, even when non-AP STA 1 (320) operates from LCM SP to HCM, a channel access operation method after switching back similar to when non-AP STA 1 (320) operates from HCM SP may be used. AP 1 (310) may request LCM SP to non-AP STA 1 (320), but non-AP STA 1 (320) may not grant it and switch its operating mode to HCM. non-AP STA 1 (320) may perform a switching back operation to switch its operating mode from HCM to LCM at the end of the LCM SP. The non-AP STA 1 (320) that performed the switching back operation can switch its operation mode to LCM, and AP 1 (310) can access the channel by performing an EDCA operation on the main 20 MHz channel after the switching back operation is performed.

[0109] FIG. 4 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applied to the present disclosure.

[0110] FIG. 4 describes the case where AP 1 (310) transmits an ICF (401) as a frame requesting operation as HCM, and non-AP STA 1 (320) transmits an ICR (402) in response. That is, AP 1 (310) may be the DPS requestor and non-AP STA 1 (320) may be the DPS requestee, and AP 1 (310) and non-AP STA 1 (320) may negotiate a transition to HCM by exchanging ICF and ICR, and AP 1 (310) may transmit a data frame (403) to non-AP STA 1 (320) and receive a response frame (404) in response. However, this is for convenience of explanation only and is not limited thereto.

[0111] Referring to FIG. 4, after TXOP 1 initiated by AP 1 (310) or non-AP STA 1 (320) is terminated, wireless LAN terminals within the BSS (e.g., AP 1 (310), non-AP STA 1 (320), non-AP STA 2 (330)) can access the channel and obtain a TXOP by performing the aforementioned EDCA operation on the main 20 MHz channel during the HCM SP period. For example, non-AP STA 2 (330) can access the channel by performing the EDCA operation on the main 20 MHz channel during the HCM SP period and obtain a TXOP (TXOP 2) by transmitting an initial frame (407) to AP 1 (310). non-AP STA 2 (330) can recognize the duration of the HCM SP negotiated between non-AP STA 1 (320) and AP 1 (310) by receiving frames exchanged between non-AP STA 1 (320) and AP 1 (310). Thus, non-AP STA 2 (330) can recognize that AP 1 (310) is operating in HCM mode. Here, non-AP STA 2 (330) can transmit the ICF (407) using a bandwidth within the maximum bandwidth supported by non-AP STA 2 (330) (if the bandwidth supported by AP 1 (310) is smaller than the bandwidth supported by non-AP STA 2 (330), then the bandwidth within the maximum bandwidth supported by AP 1 (310)). AP 1 (310), having received the ICF (407) transmitted by non-AP STA 2 (330), can respond by transmitting an ICR (408) to non-AP STA 2 (330) after SIFS time, using a bandwidth corresponding to the bandwidth in which non-AP STA 2 (330) transmitted the ICF. Non-AP STA 2 (330), having received the ICR (408) transmitted by AP 1 (310), can transmit a data frame (409) after SIFS time, having received the ICR (408).AP 1 (310), having received a data frame (409) transmitted by non-AP STA 2 (330), can respond by sending a BlockAck (BA) frame (410) to non-AP STA 2 (330) after receiving the data frame (409) and SIFS time.

[0112] As another example, non-AP STA 2 (330) can transmit a data frame directly to AP 1 (310) without transmitting an ICF, using bandwidth within the maximum bandwidth supported by non-AP STA 2 (330) (if the bandwidth supported by AP 1 (310) is smaller than the bandwidth supported by non-AP STA 2 (330), then bandwidth within the maximum bandwidth supported by AP 1 (310)). AP 1 (310), upon receiving the data frame transmitted by non-AP STA 2 (330), can respond by transmitting a BA frame to non-AP STA 2 (330) after receiving the data frame and SIFS time.

[0113] The method described above can be used in the same way even when non-AP STA 2 (330) directly transmits a data frame to non-AP STA 1 (320) (DPS Requestee). Since non-AP STA 2 (330) is aware of the duration of the HCM SP negotiated between non-AP STA 1 (320) and AP 1 (310) by receiving the frames exchanged between non-AP STA 1 (320) and AP 1 (310), it can recognize that non-AP STA 1 (320) is operating in HCM mode during the HCM SP interval. Therefore, within the HCM SP where non-AP STA 1 (320) is operating in HCM mode, non-AP STA 2 (330) can transmit without including padding in the ICF or transmit the data frame directly without the ICF transmission procedure. Since the bandwidth used for the ICF or data frame transmission described above is operated as an HCM, it can be transmitted using a bandwidth within the maximum bandwidth that non-AP STA 2 (330) can support (if the bandwidth supported by non-AP STA 1 (320) is smaller than the bandwidth supported by non-AP STA 2 (330), then the bandwidth within the maximum bandwidth supported by non-AP STA 1 (320)).

[0114] Here, the end time of the HCM SP may be the end time of TXOP 2 or an earlier time. The non-AP STA 1 (320) that negotiated the HCM SP may perform a switching back operation to LCM at the end time of the HCM SP if there is no frame that the non-AP STA 1 (320) needs to receive during the HCM SP period. That is, the non-AP STA 1 (320) may perform a switching back operation while AP 1 (310) and non-AP STA 2 (330) are performing transmit and receive operations within TXOP 2. Therefore, the completion time of the switching back operation of the non-AP STA 1 (320) may be the end time of TXOP 2 or an earlier time. The non-AP STA 1 (320) may recognize that AP 1 (310) can perform a switching back operation after the end time of TXOP 2. In the above case, AP 1 (310) may be unable to receive frames transmitted by non-AP STA 1 (320) during the switching back time. Therefore, non-AP STA 1 (320) may wait during the switching back time without performing transmission for frames to be transmitted, even if the EDCA operation is completed during the switching back time based on the end time of AP 1 (310)'s TXOP 2. After the switching back time of AP 1 (310), non-AP STA 1 (320) can transmit frames on the main 20 MHz channel.

[0115] Additionally, AP 1 (310), which negotiated the aforementioned HCM SP, can perform a switching back operation to LCM at the time of the HCM SP termination if there is no frame that AP 1 (310) needs to receive during the HCM SP period. That is, when non-AP STA 2 (330) and non-AP STA 1 (320) perform frame transmission and reception, AP 1 (310) can perform a switching back operation while non-AP STA 1 (320) and non-AP STA 2 (330) perform transmission and reception operations within TXOP 2. Here, the time of completion of the switching back operation of AP 1 (310) may be the time of the TXOP 2 termination or a time earlier. AP 1 (310) can recognize that non-AP STA 1 (320) can perform a switching back operation after the time of the TXOP 2 termination. In the above case, non-AP STA 1 (320) may not be able to receive the frame transmitted by AP 1 (310) during the switching back time. Therefore, AP 1 (310) may wait for the transmission of the frame to be transmitted even if the EDCA operation is completed during the switching back time based on the end time of TXOP 2 of non-AP STA 1 (320). AP 1 (310) may transmit the frame to be transmitted on the main 20 MHz channel after the switching back time of non-AP STA 1 (320).

[0116] FIG. 5 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applied to the present disclosure.

[0117] FIG. 5 describes the case where AP 1 (310) transmits an ICF (401) as a frame requesting operation as HCM, and non-AP STA 1 (320) transmits an ICR (402) in response. That is, AP 1 (310) may be the DPS requestor and non-AP STA 1 (320) may be the DPS requestee, and AP 1 (310) and non-AP STA 1 (320) may negotiate a transition to HCM by exchanging ICF and ICR, and AP 1 (310) may transmit a data frame (403) to non-AP STA 1 (320) and receive a response frame (404) in response. However, this is for convenience of explanation only and is not limited thereto.

[0118] Referring to FIG. 5, after TXOP 1 initiated by AP 1 (310) or non-AP STA 1 (320) is terminated, wireless LAN terminals within the BSS (e.g., AP 1 (310), non-AP STA 1 (320), non-AP STA 2 (330)) can access the channel and obtain a TXOP by performing the aforementioned EDCA operation on the main 20 MHz channel during the HCM SP period. For example, non-AP STA 2 (330) can access the channel by performing the EDCA operation on the main 20 MHz channel during the HCM SP period and obtain a TXOP (TXOP 2) by transmitting an initial frame (407) to AP 1 (310). non-AP STA 2 (330) can recognize the duration of the HCM SP negotiated between non-AP STA 1 (320) and AP 1 (310) by receiving frames exchanged between non-AP STA 1 (320) and AP 1 (310). Thus, non-AP STA 2 (330) can recognize that AP 1 (310) is operating in HCM mode. Here, non-AP STA 2 (330) can transmit the ICF (407) using a bandwidth within the maximum bandwidth supported by non-AP STA 2 (330) (if the bandwidth supported by AP 1 (310) is smaller than the bandwidth supported by non-AP STA 2 (330), then the bandwidth within the maximum bandwidth supported by AP 1 (310)). AP 1 (310), having received the ICF (407) transmitted by non-AP STA 2 (330), can respond by transmitting an ICR (408) to non-AP STA 2 (330) after SIFS time, using a bandwidth corresponding to the bandwidth in which non-AP STA 2 (330) transmitted the ICF. Non-AP STA 2 (330), having received the ICR (408) transmitted by AP 1 (310), can transmit a data frame (409) after SIFS time, having received the ICR (408).AP 1 (310), having received a data frame (409) transmitted by non-AP STA 2 (330), can respond by sending a BlockAck (BA) frame (410) to non-AP STA 2 (330) after receiving the data frame (409) and SIFS time.

[0119] As another example, non-AP STA 2 (330) can transmit a data frame directly to AP 1 (310) without transmitting an ICF, using bandwidth within the maximum bandwidth supported by non-AP STA 2 (330) (if the bandwidth supported by AP 1 (310) is smaller than the bandwidth supported by non-AP STA 2 (330), then bandwidth within the maximum bandwidth supported by AP 1 (310)). AP 1 (310), upon receiving the data frame transmitted by non-AP STA 2 (330), can respond by transmitting a BA frame to non-AP STA 2 (330) after receiving the data frame and SIFS time.

[0120] The method described above can be used in the same way when non-AP STA 2 (330) directly transmits a data frame to non-AP STA 1 (320) (DPS Requestee). Since non-AP STA 2 (330) is aware of the duration of the HCM SP negotiated between non-AP STA 1 (320) and AP 1 (310) by receiving the frames exchanged between non-AP STA 1 (320) and AP 1 (310), it can recognize that non-AP STA 1 (320) is operating in HCM mode during the HCM SP period. Therefore, non-AP STA 2 (330) can transmit without including padding in the ICF or transmit the data frame directly without the ICF transmission procedure within the HCM SP where non-AP STA 1 (320) is operating in HCM mode. Since the bandwidth used for the ICF or data frame transmission described above is operated as an HCM, it can be transmitted using a bandwidth within the maximum bandwidth that non-AP STA 2 (330) can support (if the bandwidth supported by non-AP STA 1 (320) is smaller than the bandwidth supported by non-AP STA 2 (330), then the bandwidth within the maximum bandwidth supported by non-AP STA 1 (320)).

[0121] Here, when non-AP STA 2 (330) transmits a frame to AP 1 (310), AP 1 (310) can recognize that the end time of TXOP 2 indicated by the MAC header duration value of the ICF (407) transmitted by non-AP STA 2 (330) is later than the end time of the HCM SP negotiated between AP 1 (310) and non-AP STA 1 (320). AP 1 (310) may want to align the end time of TXOP 2 with the end time of the HCM SP. AP 1 (310) may receive the ICF (407) transmitted by non-AP STA 2 (330) and, after SIFS time, transmit an ICR (408) to non-AP STA 2 (330) in response to the ICF (407). Here, the MAC header duration value of the ICR (408) transmitted by AP 1 (310) can be set to indicate the end time of the HCM SP. The non-AP STA 2 (330) can check the MAC header duration value of the ICR (407) transmitted by AP 1 (310) and perform a transmit / receive operation in TXOP 2, and TXOP 2 can be terminated at the end time of the HCM SP.

[0122] Additionally, the method described above may be applied in the same way when non-AP STA 2 (330) performs frame transmission to non-AP STA 1 (320). When non-AP STA 2 (330) transmits a frame to non-AP STA 1 (320), non-AP STA 1 (320) may recognize that the end time of TXOP 2 indicated by the MAC header duration value of the ICF transmitted by non-AP STA 2 (330) is later than the end time of the HCM SP negotiated by AP 1 (310) and non-AP STA 1 (320). In the above case, non-AP STA 1 (320) may want to align the end time of TXOP 2 with the end time of the HCM SP. non-AP STA 1 (320) receives an ICF transmitted by non-AP STA 2 (330) and, after SIFS time, can transmit an ICR to non-AP STA 2 (330) in response to the ICF. Here, the MAC header duration value of the ICR transmitted by non-AP STA 1 (320) can be set to indicate the end time of the HCM SP. non-AP STA 2 (330) checks the MAC header duration value of the ICR transmitted by non-AP STA 1 (320) and can perform a transmit / receive operation in TXOP 2. TXOP 2 can be terminated at the end time of the HCM SP.

[0123] AP 1 (310) and non-AP STA 1 (320) that negotiated the HCM SP can perform a switching back operation at the time of the HCM SP termination (i.e., at the time of TXOP 2 termination). AP 1 (310) and non-AP STA 1 (320) that performed the switching back operation can switch their operation mode to LCM and access the channel by performing the EDCA operation on the main 20 MHz channel.

[0124] FIG. 6 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applicable to the present disclosure.

[0125] FIG. 6 describes the case where AP 1 (310) transmits an ICF (401) as a frame requesting operation as HCM, and non-AP STA 1 (320) transmits an ICR (402) in response. That is, AP 1 (310) may be the DPS requestor and non-AP STA 1 (320) may be the DPS requestee, and AP 1 (310) and non-AP STA 1 (320) may negotiate a transition to HCM by exchanging ICF and ICR, and AP 1 (310) may transmit a data frame (403) to non-AP STA 1 (320) and receive a response frame (404) in response. However, this is for convenience of explanation only and is not limited thereto.

[0126] Referring to FIG. 6, after TXOP 1 initiated by AP 1 (310) or non-AP STA 1 (320) is terminated, a wireless LAN terminal within the BSS (e.g., AP 1 (310), non-AP STA 1 (320), non-AP STA 2 (330)) can access the channel and obtain a TXOP by performing the aforementioned EDCA operation on the main 20 MHz channel during the HCM SP period. For example, non-AP STA 2 (330) can access the channel by performing the EDCA operation on the main 20 MHz channel during the HCM SP period and obtain a TXOP (TXOP 2) by transmitting an initial frame (407) to AP 1 (310). non-AP STA 2 (330) can recognize the duration of the HCM SP negotiated between non-AP STA 1 (320) and AP 1 (310) by receiving frames exchanged between non-AP STA 1 (320) and AP 1 (310). Thus, non-AP STA 2 (330) can recognize that AP 1 (310) is operating in HCM mode. Here, non-AP STA 2 (330) can transmit the ICF (407) using a bandwidth within the maximum bandwidth supported by non-AP STA 2 (330) (if the bandwidth supported by AP 1 (310) is smaller than the bandwidth supported by non-AP STA 2 (330), then the bandwidth within the maximum bandwidth supported by AP 1 (310)). AP 1 (310), having received the ICF (407) transmitted by non-AP STA 2 (330), can respond by transmitting an ICR (408) to non-AP STA 2 (330) after SIFS time, using a bandwidth corresponding to the bandwidth in which non-AP STA 2 (330) transmitted the ICF. Non-AP STA 2 (330), having received the ICR (408) transmitted by AP 1 (310), can transmit a data frame (409) after SIFS time, having received the ICR (408).AP 1 (310), having received a data frame (409) transmitted by non-AP STA 2 (330), can respond by sending a BlockAck (BA) frame (410) to non-AP STA 2 (330) after receiving the data frame (409) and SIFS time.

[0127] As another example, non-AP STA 2 (330) can transmit a data frame directly to AP 1 (310) without transmitting an ICF, using bandwidth within the maximum bandwidth supported by non-AP STA 2 (330) (if the bandwidth supported by AP 1 (310) is smaller than the bandwidth supported by non-AP STA 2 (330), then bandwidth within the maximum bandwidth supported by AP 1 (310)). AP 1 (310), upon receiving the data frame transmitted by non-AP STA 2 (330), can respond by transmitting a BA frame to non-AP STA 2 (330) after receiving the data frame and SIFS time.

[0128] The method described above can be used in the same way when non-AP STA 2 (330) directly transmits a data frame to non-AP STA 1 (320) (DPS Requestee). Since non-AP STA 2 (330) is aware of the duration of the HCM SP negotiated between non-AP STA 1 (320) and AP 1 (310) by receiving the frames exchanged between non-AP STA 1 (320) and AP 1 (310), it can recognize that non-AP STA 1 (320) is operating in HCM mode during the HCM SP period. Therefore, non-AP STA 2 (330) can transmit without including padding in the ICF or transmit the data frame directly without the ICF transmission procedure within the HCM SP where non-AP STA 1 (320) is operating in HCM mode. Since the bandwidth used for the ICF or data frame transmission described above is operated as an HCM, it can be transmitted using a bandwidth within the maximum bandwidth that non-AP STA 2 (330) can support (if the bandwidth supported by non-AP STA 1 (320) is smaller than the bandwidth supported by non-AP STA 2 (330), then the bandwidth within the maximum bandwidth supported by non-AP STA 1 (320)).

[0129] Here, the end time of the HCM SP may be the end time of TXOP 2 or an earlier time. If there is no frame that non-AP STA 1 (320) needs to receive during the HCM SP period, non-AP STA 1 (320) that negotiated the HCM SP may perform a switching back operation to LCM at the end time of the HCM SP. When AP 1 (310) and non-AP STA 2 (330) perform transmit / receive operations within TXOP 2, non-AP STA 1 (320) may perform a switching back operation while AP 1 (310) and non-AP STA 2 (330) perform transmit / receive operations within TXOP 2. The completion time of the switching back operation of non-AP STA 1 (320) may be the end time of TXOP 2 or an earlier time. non-AP STA 1 (320) can recognize that AP 1 (310) may perform a switching back operation after the end time of TXOP 2. In the above case, AP 1 (310) may be unable to receive frames transmitted by non-AP STA 1 (320) during the switching back time. Therefore, non-AP STA 1 (320) may wait without performing frame transmission even if the EDCA operation is completed during the switching back time relative to the end time of TXOP 2 of AP 1 (310). After the switching back time of AP 1 (310), non-AP STA 1 (320) can transmit frames on the main 20 MHz channel.

[0130] As another example, AP 1 (310) that negotiated the HCM SP may perform a switching back operation to LCM at the time of the HCM SP termination if there are no frames that AP 1 (310) needs to receive during the HCM SP period. When non-AP STA 2 (330) and non-AP STA 1 (320) perform transmit and receive operations within TXOP 2, AP 1 (310) may perform a switching back operation while non-AP STA 1 (320) and non-AP STA 2 (330) perform transmit and receive operations within TXOP 2. The time of completion of the switching back operation by AP 1 (310) may be the time of the TXOP 2 termination or an earlier time. AP 1 (310) may recognize that non-AP STA 1 (320) may perform a switching back operation after the TXOP 2 termination time. In the above case, non-AP STA 1 (320) may not be able to receive frames transmitted by AP 1 (310) during the switching back time. Therefore, AP 1 (310) may wait without performing frame transmission during the switching back time, even if the EDCA operation is completed during the switching back time based on the end time of TXOP 2 of non-AP STA 1 (320). AP 1 (310) may transmit frames to be transmitted on the main 20 MHz channel after the switching back time of non-AP STA 1 (320).

[0131] Here, detection of the wireless medium may be impossible during the switching back time required for the switching back operation performed by non-AP STA 1 (320) at the end of the HCM SP. That is, non-AP STA 1 (320) may be unable to detect the channel and may consider the channel to be idle. Therefore, a STA (e.g., another STA in a BSS, an Overlapping BSS (OBSS) STA, etc.) that has not set a Network Allocation Vector (NAV) for TXOP 2 because it has not correctly received the frames (e.g., ICF, ICR, Data frame, BA, etc.) exchanged by AP 1 (310) and non-AP STA 2 (330) within TXOP 2 may determine that the wireless medium is idle according to the aforementioned EDCA operation (e.g., CCA). The STA that has not set a NAV for TXOP 2 may start channel access and frame transmission through the EDCA operation. Here, a frame transmitted by a STA that has not set a NAV for TXOP 2 may collide with a frame transmitted by AP 1 (310) or non-AP STA 2 (330) within TXOP 2 (e.g., Data frame, BA, etc.).

[0132] To resolve the frame collision problem caused by a STA that has not set a NAV for TXOP 2, if non-AP STA 2 (330) is aware of the HCM SP set by AP 1 (310) and non-AP STA 1 (320), it can recognize in advance that non-AP STA 1 (320) will perform a switching back operation at the time of the HCM SP termination. Therefore, non-AP STA 2 (330) can transmit frames (e.g., Data frames, Non-Data PPDU (NDP), etc., 411) so that the wireless medium is not idle during the switching back time of non-AP STA 1 (320). The transmission time of the frames (411) transmitted by non-AP STA 2 (330) during the switching back time of non-AP STA 1 (320) may vary. For example, a frame (411) transmitted by non-AP STA 2 (330) during the switching back time of non-AP STA 1 (320) may be transmitted from the start time of the switching back time of non-AP STA 1 (320) until the end time of the switching back time of non-AP STA 1 (320). For another example, a frame (411) transmitted by non-AP STA 2 (330) during the switching back time of non-AP STA 1 (320) may be transmitted from the start time of the switching back time of non-AP STA 1 (320) until SIFS time after the end time of the switching back time of non-AP STA 1 (320) until SIFS time before the end time of the switching back time of non-AP STA 1 (320).

[0133] FIG. 7 is a diagram illustrating a low-capacity recovery method during dynamic power saving based on wireless LAN service period applied to the present disclosure.

[0134] FIG. 7 describes the case where AP 1 (310) transmits an ICF (401) as a frame requesting operation as HCM, and non-AP STA 1 (320) transmits an ICR (402) in response. That is, AP 1 (310) may be the DPS requestor and non-AP STA 1 (320) may be the DPS requestee, and AP 1 (310) and non-AP STA 1 (320) may negotiate a transition to HCM by exchanging ICF and ICR, and AP 1 (310) may transmit a data frame (403) to non-AP STA 1 (320) and receive a response frame (404) in response. However, this is for convenience of explanation only and is not limited thereto.

[0135] Referring to FIG. 7, after TXOP 1 initiated by AP 1 (310) or non-AP STA 1 (320) is terminated, wireless LAN terminals within the BSS (e.g., AP 1 (310), non-AP STA 1 (320), non-AP STA 2 (330)) can access the channel and obtain a TXOP by performing the aforementioned EDCA operation on the main 20 MHz channel during the HCM SP period. For example, non-AP STA 2 (330) can access the channel by performing the EDCA operation on the main 20 MHz channel during the HCM SP period and obtain a TXOP (TXOP 2) by transmitting an initial frame (407) to AP 1 (310). non-AP STA 2 (330) can recognize the duration of the HCM SP negotiated between non-AP STA 1 (320) and AP 1 (310) by receiving frames exchanged between non-AP STA 1 (320) and AP 1 (310). Thus, non-AP STA 2 (330) can recognize that AP 1 (310) is operating in HCM mode. Here, non-AP STA 2 (330) can transmit the ICF (407) using a bandwidth within the maximum bandwidth supported by non-AP STA 2 (330) (if the bandwidth supported by AP 1 (310) is smaller than the bandwidth supported by non-AP STA 2 (330), then the bandwidth within the maximum bandwidth supported by AP 1 (310)). AP 1 (310), having received the ICF (407) transmitted by non-AP STA 2 (330), can respond by transmitting an ICR (408) to non-AP STA 2 (330) after SIFS time, using a bandwidth corresponding to the bandwidth in which non-AP STA 2 (330) transmitted the ICF. Non-AP STA 2 (330), having received the ICR (408) transmitted by AP 1 (310), can transmit a data frame (409) after SIFS time, having received the ICR (408).AP 1 (310), having received a data frame (409) transmitted by non-AP STA 2 (330), can respond by sending a BlockAck (BA) frame (410) to non-AP STA 2 (330) after receiving the data frame (409) and SIFS time.

[0136] As another example, non-AP STA 2 (330) can transmit a data frame directly to AP 1 (310) without transmitting an ICF, using bandwidth within the maximum bandwidth supported by non-AP STA 2 (330) (if the bandwidth supported by AP 1 (310) is smaller than the bandwidth supported by non-AP STA 2 (330), then bandwidth within the maximum bandwidth supported by AP 1 (310)). AP 1 (310), upon receiving the data frame transmitted by non-AP STA 2 (330), can respond by transmitting a BA frame to non-AP STA 2 (330) after receiving the data frame and SIFS time.

[0137] The method described above can be used in the same way when non-AP STA 2 (330) directly transmits a data frame to non-AP STA 1 (320) (DPS Requestee). Since non-AP STA 2 (330) is aware of the duration of the HCM SP negotiated between non-AP STA 1 (320) and AP 1 (310) by receiving the frames exchanged between non-AP STA 1 (320) and AP 1 (310), it can recognize that non-AP STA 1 (320) is operating in HCM mode during the HCM SP period. Therefore, non-AP STA 2 (330) can transmit without including padding in the ICF or transmit the data frame directly without the ICF transmission procedure within the HCM SP where non-AP STA 1 (320) is operating in HCM mode. Since the bandwidth used for the ICF or data frame transmission described above is operated as an HCM, it can be transmitted using a bandwidth within the maximum bandwidth that non-AP STA 2 (330) can support (if the bandwidth supported by non-AP STA 1 (320) is smaller than the bandwidth supported by non-AP STA 2 (330), then the bandwidth within the maximum bandwidth supported by non-AP STA 1 (320)).

[0138] Here, AP 1 (310) may be a DPS-supported terminal that performs frame transmission and reception using the operational capability used by the LCM during its operation mode switching. The end time of TXOP 2 acquired by non-AP STA 2 (330) may be later than the end time of the HCM SP negotiated by AP 1 (310) and non-AP STA 1 (320). That is, there may be time remaining in TXOP 2 during which frame transmission and reception operations are possible even after the end time of the HCM SP. Additionally, non-AP STA 2 (330) may recognize in advance the end time of the HCM SP negotiated by AP 1 (310) and non-AP STA 1 (320), and non-AP STA 2 (330) may recognize that AP 1 (310) performs a switching back operation at the end time of the HCM SP. In the above-described case, if non-AP STA 2 (330) intends to transmit a frame (e.g., data frame, 412) to AP 1 (310) at a time when AP 1 (310) is expected to perform a switching back operation, non-AP STA 2 (330) may transmit the frame (412) using the operating capability that AP 1 (310) uses in the LCM. The transmission time of the frame (412) transmitted by non-AP STA 2 (330) using the LCM operating capability of AP 1 (310) may be the same as or longer than the time when AP 1 (310) finishes its switching back time. AP 1 (310) may receive the frame (412) transmitted by non-AP STA 2 (330) using the LCM operating capability of AP 1 (310) and respond by transmitting a BA frame (413) to non-AP STA 2 (330) after SIFS time.

[0139] FIG. 8 is a flowchart illustrating the operation of an STA in a wireless LAN to which the present disclosure applies. Referring to FIG. 8, the STA may receive an initial control frame (ICF) (S810). Here, the STA is a STA that supports dynamic power saving (DPS) operation, and the ICF may include a request related to the operation mode. Subsequently, the STA may transmit an ICR in response to the ICF (S820). Subsequently, the STA may determine the operation mode based on the request related to the operation mode and perform communication with the STA that transmitted the initial control frame based on the determined operation mode (S830).

[0140] Here, the ICR includes a response indicating whether to allow a request related to the operation mode, and the decision to allow the request related to the operation mode may be based on the determined operation mode. Additionally, the request related to the operation mode may be a request regarding whether to fix the operation mode to a specific mode for a preset period, or a request regarding whether to maintain the operation mode in the existing mode for a preset period.

[0141] Additionally, when an STA operating in lower capability mode (LCM) receives an ICF, the STA determines whether to maintain the LCM based on a request regarding the operating mode and can instruct other STAs regarding whether to maintain the LCM through an ICR. Here, if the STA maintains the LCM based on a request regarding the operating mode, the ICR includes information instructing to allow the request regarding the operating mode, and if the STA switches from the LCM to a higher capability mode (HCM) based on a request regarding the operating mode, the ICR may include information instructing to reject the request regarding the operating mode.

[0142] Additionally, an ICF is transmitted from another STA operating as LCM, and after the transmission of the ICF, the operating mode of the other STA may be switched from LCM to HCM. The ICF may further include a padding field for a transition delay time based on the operating mode transition. Additionally, a request regarding the operating mode may specify at least one of a period of fixed operation as HCM (HCM service period, HCM SP) and a period of fixed operation as LCM (LCM service period, LCM SP). Additionally, if an STA obtains a request regarding the operating mode for the HCM SP, the STA may operate as HCM during the HCM SP and perform frame exchange with another STA. Additionally, if the STA has completed frame exchange with another STA and there are no frames to transmit at the end of the HCM SP, it may switch the operating mode from HCM to LCM. In addition, if the end time of the HCM SP is earlier than the end time of the transmit opportunity (TXOP) in which the other STA participated after the frame exchange between the STA and the other STA is completed, the STA may not transmit a frame to the other STA during the operation mode switching time in which the other STA switches its operation mode based on the end of the TXOP. In addition, if the end time of the HCM SP is earlier than the end time of the TXOP in which the other STA participated after the frame exchange between the STA and the other STA is completed, the TXOP is terminated together with the end time of the HCM SP, and the STA and the other STA may switch their operation modes simultaneously with the end time of the HCM SP.

[0143] For example, if the end time of the HCM SP is earlier than the end time of the TXOP in which the other STA participated after the frame exchange between the STA and the other STA is completed, the STA and the other STA may simultaneously switch operating modes at the end time of the HCM SP, and communication within the TXOP may be performed by the other STA operating as LCM. Additionally, the operating modes may include a lower capability mode (LCM) in which at least one of the operating bandwidth, the number of spatial streams (NSS), and the MCS index is limited based on DPS operation, and a higher capability mode (HCM) in which the STA's general transmit and receive operations are possible. Additionally, HCM may be an operating mode without any restrictions other than the upper limit of the wireless LAN terminal's operating capability. Additionally, when the STA switches the operation mode from LCM to HCM, the STA switches the operation mode from LCM to HCM during the operation mode switching time, and when the STA switches the operation mode from HCM to LCM, the STA switches the operation mode from HCM to LCM during the operation mode return time. Additionally, at least one of the STA and the other STA may be a non-AP STA or an AP STA.

[0144] 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.

[0145]

[0146] 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 receives an initial control frame (ICF), wherein the STA is an STA that supports dynamic power saving (DPS) operation, and the ICF includes a request related to the operation mode; A method of operation comprising: a step of transmitting an ICR (initial control response) in response to the above ICF; and a step of determining an operation mode based on a request related to the operation mode, and communicating with the STA that transmitted the initial control frame based on the determined operation mode.

2. In Paragraph 1, A method of operation in which the above ICR includes a response indicating whether to allow a request related to the above operation mode, and whether to allow a request related to the above operation mode is determined based on the determined operation mode.

3. In Paragraph 2, A method of operation in which a request regarding the above-mentioned operation mode is a request for whether to fix the above-mentioned operation mode to a specific mode for a preset period, or a request for whether to maintain the above-mentioned operation mode to an existing mode for a preset period.

4. In Paragraph 3, A method of operation in which, when the STA operating in a lower capability mode (LCM) receives the ICF, the STA determines whether to maintain the LCM based on a request related to the operating mode and instructs the other STA whether to maintain the LCM through the ICR.

5. In Paragraph 4, If the above STA maintains the LCM based on the above operation mode related request, the above ICR includes information indicating the permission of the operation mode related request, and A method of operation in which, when the STA switches from the LCM to a higher capability mode (HCM) based on a request related to the operation mode, the ICR includes information indicating a rejection of the request related to the operation mode.

6. In Paragraph 4, A method of operation in which the above ICF is transmitted from the other STA operating as an LCM, and after the transmission of the above ICF, the operating mode of the other STA is switched from the LCM to the HCM.

7. In Paragraph 1, The above ICF further includes a padding field for a switching delay time based on an operation mode switching, in a method of operation.

8. In Paragraph 1, A method of operation in which the above request regarding the operation mode indicates at least one of a period of operation fixed to HCM (HCM service period, HCM SP) and a period of operation fixed to LCM (LCM service period, LCM SP).

9. In Paragraph 8, A method of operation in which, when the above STA obtains a request related to the operation mode for the above HCM SP, the above STA operates as an HCM during the above HCM SP and performs frame exchange with the other STA.

10. In Paragraph 9, A method of operation in which the above STA switches the operating mode of the HCM to the LCM if there is no frame to be transmitted at the time of termination of the HCM SP after completing frame exchange with the above other STA.

11. In Paragraph 10, A method of operation in which, if the end time of the above HCM SP is earlier than the end time of the transmit opportunity (TXOP) in which the other STA participated after the frame exchange between the STA and the other STA is completed, the STA does not transmit a frame to the other STA during the operation mode switching time in which the other STA switches its operation mode based on the end of the TXOP.

12. In Paragraph 10, A method of operation in which, if the termination time of the above HCM SP is earlier than the termination time of the TXOP in which the other STA participated after the frame exchange between the STA and the other STA is completed, the TXOP is terminated together at the termination time of the above HCM SP, and the STA and the other STA simultaneously switch their operating modes at the termination time of the above HCM SP.

13. In Paragraph 10, A method of operation in which, if the end time of the above HCM SP is earlier than the end time of the TXOP in which the other STA participated after the frame exchange between the STA and the other STA is completed, the STA and the other STA simultaneously switch operating modes at the end time of the above HCM SP, and communication within the TXOP is performed by the other STA operating as the LCM.

14. In Paragraph 1, The above operation mode includes a lower capability mode (LCM) in which at least one of the operation bandwidth, the number of spatial streams (NSS), and the MCS index is limited based on the DPS operation, and a higher capability mode (HCM) in which the general transmit and receive operation of the STA is possible.

15. In Paragraph 14, The above HCM is an operation method in which there are no other restrictions other than the upper limit of the wireless LAN terminal's operating capability.

16. In Paragraph 1, When the above STA switches the operation mode from the LCM to the HCM, the STA switches the operation mode from the LCM to the HCM during the operation mode switching time, and A method of operation in which, when the above STA switches the operation mode from the above HCM to the above LCM, the above STA switches the operation mode from the above HCM to the above LCM during the operation mode return time.

17. In Paragraph 1, A method of operation in which at least one of the above STA and the other STA is a non-AP STA or an AP STA.

18. 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: An initial control frame (ICF) is received, wherein the STA is an STA that supports dynamic power saving (DPS) operation, and the ICF includes a request related to the operation mode, and Transmit an initial control response (ICR) in response to the above ICF, wherein the ICR includes a response indicating whether to allow a request related to the operation mode, and A STA that determines an operation mode based on whether a request related to the above operation mode is permitted, and performs communication with another STA based on the determined operation mode.

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