Apparatus and method for expanding frequency band during power saving operation in wireless LAN system

Abstract

This method for an operation of a station (STA) in a wireless LAN system, which is for expanding a frequency band during a power saving operation in the wireless LAN system, comprises: a step of obtaining information related to a power saving operation of an access point (AP); a step of transmitting information related to band expansion which is an operation for transmitting data by using a channel used in the power saving operation and at least one additional channel; and a step of transmitting the data on the basis of at least one of the information related to the band expansion and the information related to the power saving operation, wherein the information related to the power saving operation comprises information about a time required for switching an operating channel of the AP, and the information related to the band expansion includes information indicating the at least one additional channel.

Description

Device and method for expanding frequency band during power saving operation in wireless LAN system

[0001] The present disclosure relates to a wireless local area network (WLAN) system. More specifically, the present disclosure relates to a device and method for expanding a frequency band during power-saving operation in a WLAN system.

[0002] With the recent proliferation of mobile devices, Wireless Local Area Network (WLAN) technology, which can provide fast wireless communication services to these devices, is attracting significant attention. WLAN technology utilizes short-range wireless communication technology to enable mobile devices such as smartphones, tablets, laptops, portable multimedia players, and embedded devices to wirelessly access the Internet.

[0003] As applications requiring higher throughput and real-time transmission arise, the IEEE 802.11be standard, an Extreme High Throughput (EHT) wireless LAN technology, is being developed. The goal of the IEEE 802.11be standard may support a high throughput of 30 Gbps. The IEEE 802.11be standard may support technologies to reduce transmission delay. In addition, the IEEE 802.11be standard may support a wider frequency bandwidth (e.g., 320 MHz bandwidth), multi-link transmission and aggregation operation including operation using multiple bands, multi-AP (Access Point) transmission operation, and / or efficient retransmission operation (e.g., Hybrid Automatic Repeat Request (HARQ) operation).

[0004] Meanwhile, the technology that serves as the background for the invention is written to promote understanding of the background for the invention, and may include content that is not a prior art already known to a person with ordinary skill in the field to which the technology belongs.

[0005] The present disclosure provides a method and device for increasing a data transmission rate of an access point (AP) performing a power saving operation in a wireless LAN system.

[0006] The present disclosure provides a method and device for expanding a bandwidth at which an AP performing a power-saving operation performs communication in a wireless LAN system.

[0007] The present disclosure provides a method and device for expanding the bandwidth of an AP by using a frame transmitted by a STA (station) in a wireless LAN system.

[0008] The present disclosure provides a method and device for communicating with an AP performing a power saving operation using a temporarily expanded bandwidth in a wireless LAN system.

[0009] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0010] A method for operating a STA (station) in a wireless LAN system comprises the steps of: obtaining information related to a power saving operation of an AP (access point); transmitting information related to band expansion, which is an operation for transmitting data using a channel used in the power saving operation and at least one additional channel; and transmitting data based on at least one of the information related to the band expansion and the information related to the power saving operation, wherein the information related to the power saving operation includes information on a time required for switching an operating channel of the AP, and the information related to the band expansion includes information indicating the at least one additional channel.

[0011] A method for operating an access point (AP) in a wireless LAN system comprises the steps of: transmitting information related to a power saving operation; receiving information related to band expansion, which is an operation for transmitting data using a channel used in the power saving operation and at least one additional channel; switching an operating channel based on the information related to the band expansion; and receiving data based on at least one of the information related to the band expansion or the information related to the power saving operation, wherein the information related to the power saving operation includes information on a time for switching the operating channel, and the information related to the band expansion includes information indicating the at least one additional channel.

[0012] In a wireless LAN system, a station (STA) includes a transceiver; and a processor connected to the transceiver, wherein the processor is configured to obtain information related to a power saving operation of an access point (AP), transmit information related to band expansion, which is an operation for transmitting data using a channel used in the power saving operation and at least one additional channel, and transmit data based on at least one of the information related to the band expansion and the information related to the power saving operation, wherein the information related to the power saving operation includes information on a time required for switching an operating channel of the AP, and the information related to the band expansion includes information indicating the at least one additional channel.

[0013] A method for operating an access point (AP) in a wireless LAN system comprises: a transceiver; and a processor connected to the transceiver, wherein the processor is configured to transmit information related to a power saving operation, receive information related to band expansion, which is an operation for transmitting data using a channel used in the power saving operation and at least one additional channel, switch an operating channel based on the information related to the band expansion, and receive data based on at least one of the information related to the band expansion or the information related to the power saving operation, wherein the information related to the power saving operation includes information on a time for switching the operating channel, and the information related to the band expansion includes information indicating at least one additional channel for transmitting the data.

[0014] According to the present disclosure, communication can be performed using an AP in power saving operation and a channel in power saving operation and another channel.

[0015] According to the present disclosure, an AP performing a power saving operation can perform communication using an additional channel.

[0016] According to the present disclosure, communication can be performed using a wide frequency band with an AP performing a power saving operation.

[0017] The effects that can be obtained from the embodiments of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly derived and understood by those skilled in the art to which the technical configuration of the present disclosure is applied, from the description of the embodiments of the present disclosure below. In other words, unintended effects resulting from implementing the configuration described in the present disclosure can also be derived from the embodiments of the present disclosure by those skilled in the art.

[0018] FIG. 1 is a block diagram illustrating a first embodiment of a communication node constituting a wireless LAN system.

[0019] Figure 2 illustrates a first embodiment of a method for expanding the bandwidth of an access point (AP) in power-saving operation.

[0020] Figure 3 illustrates a second embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0021] Figure 4 illustrates a third embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0022] Figure 5 illustrates a fourth embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0023] FIG. 6a illustrates a fifth embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0024] FIG. 6b illustrates a sixth embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0025] FIG. 7 illustrates a seventh embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0026] FIG. 8 illustrates a flowchart of a communication procedure during a power saving operation according to one embodiment of the present disclosure.

[0027] FIG. 9 illustrates a flowchart of a communication procedure during a power saving operation according to one embodiment of the present disclosure.

[0028] FIG. 10 illustrates a flowchart of an expanding bands procedure according to one embodiment of the present disclosure.

[0029] FIG. 11 illustrates a flowchart of a band expansion procedure according to one embodiment of the present disclosure.

[0030] FIG. 12 illustrates a flowchart of a band expansion procedure according to one embodiment of the present disclosure.

[0031] FIG. 13 illustrates a flowchart of a band expansion procedure according to one embodiment of the present disclosure.

[0032] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0033] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a "second component," and similarly, a second component may also be referred to as a "first component." The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0034] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0035] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0036] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0037] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in more detail. In order to facilitate an overall understanding in describing the present invention, identical reference numerals are used for identical components in the drawings, and redundant descriptions of identical components are omitted.

[0038] Below, a wireless communication system to which embodiments of the present invention are applied will be described. The wireless communication system to which embodiments of the present invention are applied is not limited to the descriptions below, and embodiments of the present invention can be applied to various wireless communication systems. The wireless communication system may be referred to as a "wireless communication network."

[0039] Figure 1 is a block diagram illustrating a first embodiment of a communication node constituting a wireless LAN system.

[0040] Referring to FIG. 1, a communication node (100) may be an access point, a station, an access point (AP), a multi-link device (MLD), or a non-AP MLD. An access point may refer to an AP, and a station may refer to an STA or a non-AP STA. The operating channel width supported by the access point may be 20 MHz (megahertz), 80 MHz, 160 MHz, etc. The operating channel width supported by the station may be 20 MHz, 80 MHz, etc.

[0041] A communication node (100) may include at least one processor (110), a memory (120), and a plurality of transmitting and receiving devices (130) that are connected to a network and perform communication. The transmitting and receiving device (130) may be referred to as a transceiver, an RF (radio frequency) unit, an RF module, etc. In addition, the communication node (100) may further include an input interface device (140), an output interface device (150), a storage device (160), etc. Each component included in the communication node (100) may be connected by a bus (170) and communicate with each other.

[0042] However, each component included in the communication node (100) may be connected through an individual interface or individual bus centered around the processor (110), rather than a common bus (170). For example, the processor (110) may be connected to at least one of a memory (120), a transmission / reception device (130), an input interface device (140), an output interface device (150), and a storage device (160) through a dedicated interface.

[0043] The processor (110) can execute program commands stored in at least one of the memory (120) and the storage device (160). The processor (110) may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which methods according to embodiments of the present invention are performed. Each of the memory (120) and the storage device (160) may be configured with at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (120) may be configured with at least one of a read-only memory (ROM) and a random access memory (RAM).

[0044] FIG. 2 is a flowchart illustrating a first embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0045] Referring to FIG. 2, AP 1 and STA 1 associated with AP 1 may operate. AP 1 may perform a power-saving operation. The power-saving operation performed by AP 1 may be an operation to reduce bandwidth (e.g., transmission and reception bandwidth). For example, instead of operating in the original operating bandwidth of 80 MHz, AP 1 may operate only in a 20 MHz bandwidth to save power. Since AP 1 performs the power-saving operation, AP 1 may perform a clear channel assessment (CCA) operation and transmission and reception operations only in the 20 MHz primary channel. AP 1 may transmit a beacon frame (200) or a probe response frame through the 20 MHz primary channel. AP 1 may indicate that AP 1 operates only on the 20 MHz primary channel by setting the Supported Channel Width set bit in the HT Capabilities info field of the MAC header of the beacon frame (200) or the probe response frame and / or the Channel Width field in the VHT Capabilities info field to 0. Alternatively, the power saving operation performed by AP 1 may be a pre-negotiated operation with STAs associated with AP 1 (e.g., STAs including STA 1). AP 1 and STA 1 may have negotiated the power saving operation, and STA 1 may be aware of the operating bandwidth and channel of AP 1, which is the 20 MHz primary channel. Hereinafter, the “20 MHz primary channel” may be referred to as a “Primary 20 MHz channel” or a “main 20 MHz channel.”

[0046] AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 (e.g., delay time required for switching the operating bandwidth of the transceiver, etc.) during a negotiation process with STAs connected to AP 1 (e.g., STAs including STA 1). For example, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in an association response frame during an association process with STAs connected to AP 1 (e.g., STAs including STA 1). Alternatively, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in a beacon frame (200) and / or a probe response frame transmitted by AP 1. Alternatively, AP 1 may indicate requirements for expanding the transmission and reception bandwidth of AP 1 as a separate element in the beacon frame (200) and / or probe response frame transmitted by AP 1. Alternatively, AP 1 may exchange requirements for expanding the transmission and reception bandwidth of AP 1 through an exchange of action frames with STAs connected to AP 1 (e.g., STAs including STA 1). The action frame includes capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) and / or separate elements. AP 1 may indicate requirements for expanding the transmission and reception bandwidth of AP 1 using the action frame.

[0047] STA 1 may want to transmit an uplink (UL) frame (220). For example, the uplink frame (220) may include a PHY layer protocol data unit (PPDU), a MAC layer protocol data unit (MPDU), or an aggregated-MPDU (A-MPDU). STA 1 may perform a channel access operation. The channel access operation may be an EDCA backoff operation and an EDCA TXOP (transmit opportunity) acquisition procedure. Success of the channel access operation means that a backoff counter reaches 0 and transmission is determined at a slot boundary where the backoff counter reaches 0. STA 1 may want to transmit the uplink frame (220) with a wider channel bandwidth than the channel bandwidth in which AP 1 is operating. STA 1 can perform CCA operation during the Priority Inter Frame Space (PIFS) time on a subchannel (e.g., 20 MHz subchannel, 40 MHz subchannel, etc.) starting from the PIFS time before the end time of the EDCA backoff. After the PIFS, STA 1 can transmit a UL PPDU (221) on the 20 MHz main channel, and simultaneously transmit UL PPDUs (223, 225, 227) on empty subchannel(s) (e.g., 20 MHz bandwidth channels). Here, duplicated transmission means that the UL PPDU (221) of the main channel and the UL PPDUs (233, 235, 227) of the subchannels are the same. Duplicated transmission means duplicated PPDU transmission that transmits a PPDU in units of 20 MHz.The length of the UL PPDU (221, 223, 225, 227) transmitted by STA 1 to AP 1 to indicate expansion of the transmission and reception bandwidth of AP 1 and / or the IFS (Inter Frame Space) used for transmission may satisfy requirements (e.g., delay time required for switching the operating bandwidth of a transceiver, etc.) required for expansion of the transmission and reception bandwidth of AP 1 indicated in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in the association response frame, beacon frame (200), and / or probe response frame transmitted by AP 1. The total bandwidth transmitted by STA 1 may be greater than 20 MHz (e.g., 40 MHz, 80 MHz). STA 1 can obtain a Transmit Opportunity (TXOP) through transmission of the UL PPDU (221, 223, 225, 227). STA 1 can use the bandwidth indicator included in the SIG (SIGNAL) field of the PHY preamble of the UL PPDU (221) transmitted on the 20 MHz main channel to indicate to AP 1 information about the channel bandwidth (e.g., 40 MHz, 80 MHz, 160 MHz, 80+80 MHz, 320 MHz, etc.) of the UL PPDU (210) expected to be transmitted subsequently. The SIG field can be HT (high throughput)-SIG, VHT (very high throughput)-SIG, HE (high efficiency)-SIG, EHT (extremely high throughput)-SIG, UHR (ultra-high reliability)-SIG, U (universal)-SIG, L (legacy, non-HT)-SIG, etc. The bandwidth indicator can be a bit or a subfield, etc. The bandwidth indicator may vary depending on the format of the PPDU (221, 223, 225, 227). The bandwidth indicator may be indicated through all or part of the bits of the SERVICE field transmitted after the PHY preamble.AP 1 can prepare the transceiver to support the channel bandwidth of the UL PPDU (210) that STA 1 intends to transmit by referring to the information about the channel bandwidth in the bandwidth indicator of the PHY preamble included in the UL PPDU (221, 223, 225, 227) transmitted by STA 1. For example, the transmission time of the UL PPDU (221, 223, 225, 227) + IFS time may be longer than the time required for AP 1 to prepare the transceiver. The time required for AP 1 to prepare the transceiver may include requirements required for the negotiated transmission / reception bandwidth expansion (e.g., delay time required for switching the transceiver operating bandwidth, etc.). For example, the bandwidth indicated by STA 1 may be 80 MHz. In this case, AP 1 prepares to transmit and receive 80 MHz. STA 1 can transmit UL PPDU (210) to AP 1 with extended bandwidth (e.g., 40 MHz, 80 MHz, 160 MHz, 80+80 MHz, 320 MHz, etc.) after SIFS (Short Inter Frame Space) or a time longer than SIFS time (e.g., PIFS time) after transmitting the first UL PPDU (221, 223, 225, 227). AP 1 can transmit BA (Block Acknowledgement) frame to STA 1 after SIFS after receiving UL PPDU (210).

[0048] AP 1 can return to power saving operation after STA 1's TXOP ends. That is, AP 1 can only operate on the 20 MHz main channel to reduce power consumption after operating with a bandwidth greater than 20 MHz. AP 1 can explicitly notify this to STAs through a beacon frame, etc., or can operate on the 20 MHz channel implicitly after the TXOP ends. For example, if it does not receive a frame from STA 1 for a certain period of time (e.g., PIFS time), or if the AP does not receive a frame from STA 1 for a certain period of time after transmitting a frame to STA 1, the AP reduces its operating bandwidth again and operates on the 20 MHz channel.

[0049] FIG. 3 is a timing diagram illustrating a second embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0050] Referring to FIG. 3, AP 1 and STA 1 connected to AP 1 may operate. AP 1 may perform a power-saving operation. The power-saving operation performed by AP 1 may be an operation to reduce bandwidth (e.g., transmission and reception bandwidth). For example, instead of operating in the original operating bandwidth of 80 MHz, AP 1 may operate only in a 20 MHz bandwidth to save power. Since AP 1 performs the power-saving operation, AP 1 may perform CCA and transmission and reception operations only on the 20 MHz primary channel. AP 1 may transmit a beacon frame (300) or a probe response frame through the 20 MHz primary channel. AP 1 may set the Supported Channel Width set bit in the HT Capabilities info field of the MAC header of the beacon frame (300) or the probe response frame and / or the Channel Width field in the VHT Capabilities info field to 0 to indicate that AP 1 operates only on the 20 MHz primary channel. Alternatively, the power saving operation performed by AP 1 may be a pre-negotiated operation with the STAs associated with AP 1 (e.g., STAs including STA 1). AP 1 and STA 1 may have negotiated the power saving operation, and STA 1 may know the operating bandwidth and channel of AP 1, which is the 20 MHz primary channel.

[0051] AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 (e.g., delay time required for switching the operating bandwidth of the transceiver, etc.) during a negotiation process with STAs connected to AP 1 (e.g., STAs including STA 1). For example, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in an association response frame during an association process with STAs connected to AP 1 (e.g., STAs including STA 1). Alternatively, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in a beacon frame (300) and / or a probe response frame transmitted by AP 1. Alternatively, AP 1 may indicate requirements for expanding the transmission and reception bandwidth of AP 1 as a separate element in the beacon frame (200) and / or probe response frame transmitted by AP 1. Alternatively, AP 1 may exchange requirements for expanding the transmission and reception bandwidth of AP 1 through an exchange of action frames with AP 1 and STAs connected to AP 1 (e.g., STAs including STA 1), and the action frame may include capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) and / or a separate element to indicate requirements for expanding the transmission and reception bandwidth of AP 1.

[0052] STA 1 may want to transmit an uplink frame (330). For example, the uplink frame (330) may include a PHY layer protocol data unit (PPDU), a MAC layer protocol data unit (MPDU), or an aggregated-MPDU (A-MPDU). STA 1 may perform a channel access operation. The channel access operation may be an EDCA backoff operation and an EDCA TXOP (transmit opportunity) acquisition procedure. Success of the channel access operation means that the backoff counter reaches 0 and transmission is determined at a slot boundary where the backoff counter reaches 0. STA 1 may want to transmit the uplink frame (330) with a wider channel bandwidth than the channel bandwidth in which AP 1 is operating. STA 1 can perform CCA operation for PIFS (Priority Inter Frame Space) time on a subchannel (e.g., 20 MHz subchannel, 40 MHz subchannel, etc.) before the end time of EDCA backoff. After PIFS, STA 1 can transmit an RTS frame (311) on the 20 MHz main channel, and simultaneously transmit a CTS-to-self frame (313, 315, 317) on the empty subchannel(s) (20 MHz bandwidth channels). The CTS-to-self frames (313, 315, 317) are CTS (Clear To Send) frames in which the address of the RA (Receiver Address) field is set to STA 1 itself. The total bandwidth over which STA 1 transmits CTS-to-self frames (313, 315, 317) may be greater than 20 MHz (40 MHz, 80 MHz).STA 1 can acquire TXOP (Transmit Opportunity) by transmitting RTS frame (311) and CTS-to-self frame (313, 315, 317). The TA (Transmitter Address) of the RTS frame (311) transmitted by STA 1 to AP 1 through a 20 MHz main channel may be a Bandwidth Signaling TA. The Bandwidth Signaling TA uses several bits of the TA to indicate the bandwidth. Alternatively, the Bandwidth Signaling TA may indicate that the SERVICE field included in the PPDU indicates the bandwidth. The SERVICE field may be located after the PHY preamble in the PPDU. If the Bandwidth Signaling TA is included in the TA of the RTS frame, the receiver of the RTS frame can identify the bandwidth on which the RTS frame is transmitted by checking the SERVICE field. STA 1 can use the Bandwidth Signaling TA of the RTS frame (311) transmitted on the 20 MHz main channel to indicate to AP 1 information about the channel bandwidth (e.g., 40 MHz, 80 MHz, 160 MHz, 80+80 MHz, 320 MHz, etc.) of the UL PPDU (330) expected to be transmitted subsequently. AP 1 can prepare its transceiver to support the channel bandwidth of the UL PPDU (330) that STA 1 intends to transmit by referring to the Bandwidth Signaling TA of the RTS frame (311) transmitted by STA 1 on the 20 MHz main channel. For example, the transmission time of the UL PPDU (330) + IFS time may be longer than the time required for AP 1 to prepare its transceiver. The time required for AP 1 to prepare the transceiver may include requirements for the negotiated transmit and receive bandwidth expansion (e.g., delay time required for the transceiver operating bandwidth to be switched, etc.).For example, the bandwidth indicated by STA 1 may be 80 MHz, and AP 1 prepares to transmit and receive 80 MHz. AP 1 may transmit a CTS frame (320) to STA 1 through the 20 MHz main channel after SIFS from the time of receiving the RTS frame (311) through the 20 MHz main channel. The CTS frame (320) transmitted by AP 1 may be transmitted in duplicate on the 20 MHz main channel and sub-channel(s) on which the RTS frame (311) was previously received. AP 1 may indicate the bandwidth of the channel on which transmission and reception are ready by using the bandwidth indicator included in the SIG field of the PHY preamble of the PPDU including the CTS frame (320). STA 1 can transmit a UL PPDU (330) to AP 1 with an extended bandwidth (e.g., 40 MHz, 80 MHz, 160 MHz, 80+80 MHz, 320 MHz, etc.) after SIFS after receiving the CTS frame by referring to the bandwidth indicator included in the SIG field of the PHY frames of the PPDU including the received CTS frame (320). AP 1 can transmit a BA (Block Acknowledgement) frame to STA 1 after SIFS after receiving the UL PPDU (330).

[0053] AP 1 can return to power saving operation after STA 1's TXOP ends. That is, AP 1 can operate only on the 20 MHz primary channel to reduce power consumption after operating with a bandwidth greater than 20 MHz. AP 1 can explicitly notify this to STAs through a beacon frame or a probe response frame, or can operate on the 20 MHz primary channel implicitly after the TXOP ends. For example, if the AP does not receive a frame from STA 1 for a certain period of time (e.g., PIFS time), or if the AP does not receive a frame from STA 1 for a certain period of time after transmitting a frame to STA 1, the AP reduces the operating bandwidth again and operates on the 20 MHz channel.

[0054] FIG. 4 is a timing diagram illustrating a third embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0055] Referring to FIG. 4, AP 1 and STA 1 connected to AP 1 can operate. AP 1 can perform a power-saving operation. The power-saving operation performed by AP 1 may be an operation to reduce bandwidth (e.g., transmission and reception bandwidth). For example, instead of operating in the original operating bandwidth of 80 MHz, AP 1 may operate only in a 20 MHz bandwidth to save power. Since AP 1 performs the power-saving operation, AP 1 can perform CCA and transmission and reception operations only on the 20 MHz primary channel. AP 1 can transmit a beacon frame (400) or a probe response frame through the 20 MHz primary channel. AP 1 can inform that AP 1 operates only on the 20 MHz primary channel by setting the Supported Channel Width set bit in the HT Capabilities info field of the MAC header of the beacon frame (400) or the probe response frame to 0 and / or the Channel Width field in the VHT Capabilities info field. Alternatively, the power saving operation performed by AP 1 may be a pre-negotiated operation with the STAs associated with AP 1 (e.g., STAs including STA 1). AP 1 and STA 1 may have pre-negotiated the power saving operation, and based on the negotiation, STA 1 may know the operating bandwidth and channel of AP 1, which is the 20 MHz primary channel.

[0056] AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 (e.g., delay time required for switching the operating bandwidth of the transceiver, etc.) during a negotiation process with STAs connected to AP 1 (e.g., STAs including STA 1). For example, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in an association response frame during an association process with STAs connected to AP 1 (e.g., STAs including STA 1). Alternatively, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in a beacon frame (400) and / or a probe response frame transmitted by AP 1. Alternatively, AP 1 may indicate requirements for expanding the transmission and reception bandwidth of AP 1 as a separate element in the beacon frame (200) and / or probe response frame transmitted by AP 1. Alternatively, AP 1 may exchange requirements for expanding the transmission and reception bandwidth of AP 1 through an exchange of action frames with AP 1 and STAs connected to AP 1 (e.g., STAs including STA 1), and the action frame may include capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) and / or a separate element to indicate requirements for expanding the transmission and reception bandwidth of AP 1.

[0057] STA 1 may want to transmit an uplink frame (440). For example, the uplink frame (440) may include a PHY layer protocol data unit (PPDU), a MAC layer protocol data unit (MPDU), or an aggregated-MPDU (A-MPDU). STA 1 may perform a channel access operation. The channel access operation may be an EDCA backoff operation and an EDCA TXOP (transmit opportunity) acquisition procedure. Success of the channel access operation means that the backoff counter reaches 0 and transmission is determined at a slot boundary where the backoff counter reaches 0. STA 1 may want to transmit the uplink frame (440) with a wider channel bandwidth than the channel bandwidth in which AP 1 is operating. STA 1 can perform CCA operation for PIFS (Priority Inter Frame Space) time on a subchannel (e.g., 20 MHz subchannel, 40 MHz subchannel, etc.) before the end time of EDCA backoff. After PIFS, STA 1 can simultaneously transmit a CTS-to-self frame (410) on empty subchannel(s) including the 20 MHz main channel. STA 1 can obtain a TXOP (Transmit Opportunity) by transmitting the CTS-to-self frame (410). The CTS-to-self frame (410) is a CTS (Clear To Send) frame in which the address of the RA (Receiver Address) field is set to STA 1 itself.STA 1 can use the bandwidth indicator included in the SIG field of the PHY preamble of the PPDU including the CTS-to-self frame (410) to be transmitted to transmit information about the channel bandwidth (e.g., 40 MHz, 80 MHz, 160 MHz, 80+80 MHz, 320 MHz, etc.) of the UL PPDU (440) expected to be transmitted subsequently to AP 1. AP 1 can prepare its transceiver to support the channel bandwidth of the UL PPDU (440) to be transmitted by STA 1 with reference to the bandwidth indicator included in the SIG field of the PHY preamble of the PPDU including the CTS-to-self frame (410) transmitted by STA 1. For example, the transmission time of the UL PPDU (440) + IFS time may be longer than the time required for AP 1 to prepare its transceiver. The time required for AP 1 to prepare the transceiver may include requirements for the negotiated transmission and reception bandwidth expansion (e.g., delay time required for switching the transceiver operating bandwidth, etc.). STA 1 may transmit an RTS frame (420) to AP 1 after SIFS after transmitting the CTS-to-self frame (410). The RTS frame transmitted by STA 1 to AP 1 may be transmitted in duplicate on the 20 MHz primary channel and sub-channel(s) on which the CTS-to-self frame (410) was previously transmitted. The TA of the RTS frame (420) transmitted by STA 1 may be a Bandwidth Signaling TA. The Bandwidth Signaling TA uses several bits of the TA to indicate the bandwidth. Alternatively, the Bandwidth Signaling TA itself indicates that the SERVICE field included after the PHY preamble included in the PPDU indicates the bandwidth. When a Bandwidth Signaling TA is included in the TA of an RTS frame, the receiver of the RTS frame can identify the bandwidth over which the RTS frame was transmitted by checking the SERVICE field.AP 1 may prepare a transceiver to support the channel bandwidth of a UL PPDU (440) that STA 1 intends to transmit by referring to a bandwidth indicator included in a SIG field of a PHY preamble of a PPDU including a CTS-to-self frame (410) transmitted by STA 1 and / or a Bandwidth Signaling TA of an RTS frame (420). For example, the transmission time of the UL PPDU (440) + IFS time may be longer than the time required for AP 1 to prepare the transceiver. AP 1 may transmit a CTS frame (430) to STA 1 after an SIFS after receiving the RTS frame (420). The CTS frame (430) transmitted by AP 1 may be transmitted in duplicate on a 20 MHz primary channel on which the RTS frame (420) was previously received and on a secondary channel(s) on which transmission and reception preparation is complete. STA 1 may transmit a UL PPDU (440) to AP 1 with an extended bandwidth (e.g., 40 MHz, 80 MHz, 160 MHz, 80+80 MHz, 320 MHz, etc.) after SIFS after receiving the CTS frame (430) by referring to the bandwidth of the channel through which the CTS frame (430) was transmitted. AP 1 may transmit a BA (Block Acknowledgement) frame to STA 1 after SIFS after receiving the UL PPDU (440).

[0058] AP 1 can return to power saving operation after STA 1's TXOP ends. That is, AP 1 can operate only on the 20 MHz main channel to reduce power consumption after operating with a bandwidth greater than 20 MHz. AP 1 can explicitly signal this with a beacon frame or a probe response frame, or it can operate on the 20 MHz channel implicitly after the TXOP ends. For example, if the AP does not receive a frame from STA 1 for a certain period of time (e.g., PIFS time), or if the AP does not receive a frame from STA 1 for a certain period of time after transmitting a frame to STA 1, the AP reduces the operating bandwidth again and operates on the 20 MHz channel.

[0059] FIG. 5 is a timing diagram illustrating a fourth embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0060] Referring to FIG. 5, AP 1 and STA 1 associated with AP 1 may operate. AP 1 may perform a power-saving operation. The power-saving operation performed by AP 1 may be an operation to reduce bandwidth (e.g., transmission and reception bandwidth). For example, instead of operating in the original operating bandwidth of 80 MHz, AP 1 may operate only in a 20 MHz bandwidth to save power. Since AP 1 performs the power-saving operation, AP 1 may perform CCA and transmission and reception operations only in the 20 MHz primary channel. AP 1 may transmit a beacon frame (500) or a probe response frame through the 20 MHz primary channel. AP 1 may indicate that it operates only on the 20 MHz primary channel by setting the Supported Channel Width set bit in the HT Capabilities info field of the MAC header of the beacon frame (500) or probe response frame transmitted by AP 1 and / or the Channel Width field in the VHT Capabilities info field to 0. Alternatively, the power saving operation performed by AP 1 may be an operation pre-negotiated with STAs associated with AP 1 (e.g., STAs including STA 1). AP 1 and STA 1 may have negotiated the power saving operation, and STA 1 may be aware of the operating bandwidth and channel of AP 1, which is the 20 MHz primary channel.

[0061] AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 (e.g., delay time required for switching the operating bandwidth of the transceiver, etc.) during a negotiation process with STAs connected to AP 1 (e.g., STAs including STA 1). For example, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in an association response frame during an association process with STAs connected to AP 1 (e.g., STAs including STA 1). Alternatively, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in a beacon frame (500) and / or a probe response frame transmitted by AP 1. Alternatively, AP 1 may indicate requirements for expanding the transmission and reception bandwidth of AP 1 as a separate element in the beacon frame (200) and / or probe response frame transmitted by AP 1. Alternatively, AP 1 may exchange requirements for expanding the transmission and reception bandwidth of AP 1 through an exchange of action frames with AP 1 and STAs connected to AP 1 (e.g., STAs including STA 1), and the action frame may include capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) and / or a separate element to indicate requirements for expanding the transmission and reception bandwidth of AP 1.

[0062] STA 1 may want to transmit an uplink frame (530). For example, the uplink frame (530) may include a PHY layer protocol data unit (PPDU), a MAC layer protocol data unit (MPDU), or an aggregated-MPDU (A-MPDU). STA 1 may perform a channel access operation. The channel access operation may be an EDCA backoff operation and an EDCA TXOP (transmit opportunity) acquisition procedure. Success of the channel access operation means that a backoff counter reaches 0 and transmission is determined at a slot boundary where the backoff counter reaches 0. STA 1 may want to transmit the uplink frame (530) with a wider channel bandwidth than the channel bandwidth in which AP 1 is operating. STA 1 can perform CCA operation for PIFS (Priority Inter Frame Space) time on a subchannel (e.g., 20 MHz subchannel, 40 MHz subchannel, etc.) before the end of EDCA backoff. After PIFS, STA 1 can transmit UL PPDU (510) on 20 MHz main channel and simultaneously transmit UL PPDU (510) on empty subchannel(s) (20 MHz bandwidth channels). The total bandwidth transmitted by STA 1 can be greater than 20 MHz (40 MHz, 80 MHz). STA 1 can obtain TXOP (Transmit Opportunity) by transmitting UL PPDU (510).

[0063] The frame (510) that STA 1 transmits for the first time within a TXOP may not be a MAC frame. The frame (510) that is transmitted for the first time may only include a PHY preamble. That is, the frame (510) that is transmitted for the first time may be a PPDU that only has a PHY preamble and no PHY data field, i.e., a null data PPDU (NDP). The NDP (510) may be transmitted over a bandwidth wider than 20 MHz (e.g., an 80 MHz bandwidth). The NDP (510) may be transmitted in duplicate for every 20 MHz. The PHY preamble of the NDP (510) may include multiple SIG fields (e.g., U-SIG). The U-SIG may indicate the bandwidth that STA 1 intends to transmit. For example, the U-SIG has a 3-bit bandwidth field. The used bandwidth is indicated according to the value of the bandwidth field. The U-SIG has a TXOP field. The TXOP field indicates the length of the TXOP acquired by STA 1. The U-SIG may include an indicator indicating whether STA 1 transmits on the uplink and a BSS color, which is information that distinguishes the BSS of AP 1. In addition to the U-SIG, one of the above information (the bandwidth that STA 1 intends to transmit, the TXOP length, an indicator indicating uplink transmission, and a BSS color) may also be indicated in a SIG that may be included in a preamble, such as an L-SIG, HT-SIG, VHT-SIG, HE-SIG, EHT-SIG, or HR-SIG.

[0064] STA 1 can satisfy requirements for expanding the transmission and reception bandwidth of AP 1 (e.g., delay time required for switching the operating bandwidth of the transceiver, etc.) by repeatedly transmitting the PHY preamble of NDP (510). That is, STA 1 can additionally transmit a frame (520) including a PHY preamble. Alternatively, STA 1 can transmit a QoS Null frame to AP 1 to satisfy requirements for expanding the transmission and reception bandwidth of AP 1. The QoS Null frame that STA 1 transmits to AP 1 may be a QoS Null (No ACK) frame that does not require Acknowledgement. STA 1 can indicate the bandwidth it wants to use by using A-Control information included in the MAC header of the QoS Null frame. Alternatively, STA 1 can indicate the bandwidth it wants to use by using the PHY preamble of the QoS Null frame including the preamble including the U-SIG. For example, the U-SIG of the PHY preamble of the QoS Null frame has a 3-bit bandwidth field, and the used bandwidth is indicated by the value of the 3-bit bandwidth field of the U-SIG. In addition, the U-SIG has a TXOP field, and the length of the TXOP acquired by STA 1 is indicated by the TXOP field. The U-SIG may include an indicator and a BSS color to indicate whether STA 1 transmits on the uplink. Here, the BSS color means information for distinguishing the BSS of AP 1.

[0065] AP 1 can receive the NDP (510) or QoS Null frame transmitted by STA 1. Using the BSS color information and the indicator indicating uplink transmission in the received NDP (510) or QoS Null frame, AP 1 can determine whether an STA (e.g., STA 1) connected to AP 1 wants to transmit to AP 1. Based on the transmission bandwidth of STA 1 indicated in the preamble included in the received NDP (510) or QoS Null frame, AP 1 prepares the receiver to perform transmission and reception operations in the bandwidth indicated by STA 1 (e.g., 80 MHz). STA 1 can transmit a frame (530) (e.g., UL PPDU) to AP 1 after an SIFS time or a time longer than SIFS (e.g., PIFS) from the end time of transmission of the NDP (510) or QoS Null frame. The frame (530) transmitted by STA 1 is a frame transmitted on a channel wider than 20 MHz bandwidth (e.g., an 80 MHz channel). AP 1 can transmit a BA (Block Acknowledgement) frame to STA 1 after SIFS after receiving the UL PPDU (530) from STA 1.

[0066] AP 1 can return to power saving operation after STA 1's TXOP ends. That is, AP 1 can operate only on the 20 MHz main channel to reduce power consumption after operating with a bandwidth greater than 20 MHz. AP 1 can explicitly signal this with a beacon frame, etc., or can operate on the 20 MHz channel implicitly after the TXOP ends. For example, if the AP does not receive a frame from STA 1 for a certain period of time (e.g., PIFS time), or if the AP does not receive a frame from STA 1 for a certain period of time after transmitting a frame to STA 1, the AP reduces the operating bandwidth again and operates on the 20 MHz channel.

[0067] FIG. 6a and FIG. 6b are timing diagrams illustrating the fifth and sixth embodiments of a method for expanding the bandwidth of an AP in power-saving operation.

[0068] Referring to FIGS. 6A and 6B, AP 1 and STA 1 associated with AP 1 may operate. AP 1 may perform a power-saving operation. The power-saving operation performed by AP 1 may be an operation to reduce bandwidth (e.g., transmission and reception bandwidth). For example, instead of operating in the original operating bandwidth of 80 MHz, AP 1 may operate only in a 20 MHz bandwidth to save power. Since AP 1 performs the power-saving operation, AP 1 may perform CCA and transmission and reception operations only in the 20 MHz primary channel. AP 1 may transmit a beacon frame (600) or a probe response frame through the 20 MHz primary channel. AP 1 may indicate that it operates only on the 20 MHz primary channel by setting the Supported Channel Width set bit in the HT Capabilities info field of the MAC header of the beacon frame (600) or probe response frame transmitted by AP 1 and / or the Channel Width field in the VHT Capabilities info field to 0. Alternatively, the power saving operation performed by AP 1 may be an operation pre-negotiated with STAs associated with AP 1 (e.g., STAs including STA 1). AP 1 and STA 1 may have negotiated the power saving operation, and STA 1 may be aware of the operating bandwidth and channel of AP 1, which is the 20 MHz primary channel.

[0069] AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 (e.g., delay time required for switching the operating bandwidth of the transceiver, etc.) during a negotiation process with STAs connected to AP 1 (e.g., STAs including STA 1). For example, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in an association response frame during an association process with STAs connected to AP 1 (e.g., STAs including STA 1). Alternatively, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in a beacon frame (600) and / or a probe response frame transmitted by AP 1. Alternatively, AP 1 may indicate requirements for expanding the transmission and reception bandwidth of AP 1 as a separate element in the beacon frame (200) and / or probe response frame transmitted by AP 1. Alternatively, AP 1 may exchange requirements for expanding the transmission and reception bandwidth of AP 1 through an exchange of action frames with AP 1 and STAs connected to AP 1 (e.g., STAs including STA 1), and the action frame may include capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) and / or a separate element to indicate requirements for expanding the transmission and reception bandwidth of AP 1.

[0070] STA 1 may want to transmit an uplink frame (620). For example, the uplink frame (620) may include a PHY layer protocol data unit (PPDU), a MAC layer protocol data unit (MPDU), or an aggregated-MPDU (A-MPDU). STA 1 may perform a channel access operation. The channel access operation may be an EDCA backoff operation and an EDCA TXOP (transmit opportunity) acquisition procedure. Success of the channel access operation means that the backoff counter reaches 0 and transmission is determined at a slot boundary where the backoff counter reaches 0. STA 1 may want to transmit the uplink frame (620) through a channel bandwidth wider than the channel bandwidth on which AP 1 is operating. STA 1 can perform CCA operation for PIFS (Priority Inter Frame Space) time on a subchannel (e.g., 20 MHz subchannel, 40 MHz subchannel, etc.) before the end time of EDCA backoff. After PIFS, STA 1 can transmit UL PPDU (610) on 20 MHz main channel and simultaneously transmit UL PPDU (610) on empty subchannel(s) (20 MHz bandwidth channels). The total bandwidth transmitted by STA 1 can be greater than 20 MHz (40 MHz, 80 MHz). STA 1 can obtain TXOP (Transmit Opportunity) through UL PPDU transmission.

[0071] Referring to FIG. 6A, the UL PPDU, which is the first frame transmitted by STA 1 within the TXOP, may be transmitted with a bandwidth wider than 20 MHz (e.g., 80 MHz). The UL PPDU of STA 1 may include two PHY preambles (611, 613). That is, STA 1 initially transmits the PHY preamble (611) to each 20 MHz channel of the 80 MHz channel, and after the PHY preamble (611) transmission is terminated, the PHY preamble (613) is repeatedly transmitted once more. This operation may be to secure time for expanding the operating bandwidth of AP 1 from 20 MHz to 80 MHz. Alternatively, STA 1 may initially transmit a PHY preamble (611) in each 20MHz channel of the 80MHz channel, and repeatedly transmit the PHY preamble until the requirements for expanding the transmit and receive bandwidth of AP 1 (e.g., the delay time required for switching the transceiver operating bandwidth, etc.) are met.

[0072] The PHY preamble (611, 613) may include multiple SIG fields (e.g., U-SIG). The U-SIG may indicate the bandwidth that STA 1 intends to transmit. For example, the U-SIG may include a 3-bit bandwidth field. The used bandwidth is indicated according to the value of the bandwidth field. The U-SIG includes a TXOP field. The TXOP field indicates the length of the TXOP acquired by STA 1. The U-SIG may include an indicator indicating whether STA 1 transmits on the uplink and a BSS color, which is information that distinguishes the BSS of AP 1. In addition to the U-SIG, at least one of several types of SIGs that can be included in the preamble (e.g., L-SIG, HT-SIG, VHT-SIG, HE-SIG, EHT-SIG, or UHR-SIG) may indicate one of the bandwidth that STA 1 wants to transmit, the TXOP length, an indicator indicating uplink transmission, or a BSS color. The PHY preamble (611) that STA 1 transmits first using the UL PPDU further includes an indicator indicating that a preamble (613) is to be additionally transmitted thereafter.

[0073] AP 1 can receive the UL PPDU transmitted by STA 1. AP 1 can use the BSS color information of the PHY preamble (611, 613) of the received UL PPDU and the indicator indicating uplink transmission to determine whether an STA (e.g., STA 1) connected to AP 1 wants to transmit data to AP 1. Based on the transmission bandwidth of STA 1 indicated in the preamble (611, 613) included in the received PPDU, AP 1 prepares the receiver to perform transmission and reception operations in the bandwidth indicated by STA 1 (e.g., 80 MHz). The time required for AP 1 to prepare the transceiver may be as long as the requirements required for the negotiated transmission and reception bandwidth expansion (e.g., the delay time required for switching the transceiver operating bandwidth, etc.). The operation of AP 1 changing the operating bandwidth of the receiver can be performed by the first PHY preamble (611) included in the UL PPDU transmitted by STA 1. AP 1 can re-check the bandwidth in which the PPDU (620) is transmitted from the second and subsequent included PHY preambles (613). AP 1 can perform operations for receiving in a wide channel bandwidth, such as channel measurement operations and training. AP 1 receives the UL PPDU (620) from STA 1 using an 80 MHz channel. AP 1 can transmit a BA (Block Acknowledgement) frame to STA 1 after SIFS from the time of completion of reception of the UL PPDU (620) from STA 1.

[0074] Referring to FIG. 6b, the UL PPDU, which is the first frame transmitted by STA 1 within the TXOP, can be transmitted using a bandwidth wider than 20 MHz (e.g., 80 MHz). STA 1 transmits a PHY preamble (611) to each 20 MHz channel of the 80 MHz channel, and after the transmission of the PHY preamble (611) is terminated, transmits a PPDU (630) duplicated at 20 MHz to AP 1. The PHY preamble (611) can include multiple SIG fields (e.g., U-SIG). The U-SIG can indicate the bandwidth that STA 1 intends to transmit. For example, the U-SIG can include a 3-bit bandwidth field and can indicate the used bandwidth according to the value of the bandwidth field. The bandwidth that STA 1 wants to transmit can be indicated through at least one of several types of SIGs that can be included in the preamble, such as L-SIG, HT-SIG, VHT-SIG, HE-SIG, EHT-SIG, or UHR-SIG, in addition to U-SIG. AP 1 can receive 20MHz PPDU (630) and check the bandwidth that STA 1 wants to transmit. The bandwidth that STA 1 wants to transmit may be 80MHz. AP 1 can receive 20MHz PPDU (630) from STA 1 from the time of receiving the preamble (611) until the requirements for transmission and reception bandwidth expansion (e.g., delay time required for switching the operating bandwidth of the transceiver) are satisfied. After STA 1 transmits the preamble (611) of the PPDU, STA 1 can train the transceiver of AP 1 to expand the transmission and reception bandwidth of AP 1 by transmitting a midamble (PHY Midamble, 640) at a point in time when AP 1 can transmit and receive in the expanded bandwidth by referring to the requirements necessary for expanding the transmission and reception bandwidth of AP 1. The operation of training the transceiver may be for AP 1 to operate in a wide bandwidth.The midamble (640) may be inserted in the middle of the data fields (e.g., data bit(s), data symbol(s)) of the PPDU (620, 630). In other words, the midamble (640) may be inserted between the PPDU (620) and the 20 MHz PPDU (630). The midamble may be all or part of the preamble included in the middle of the PPDU (620) (e.g., at least one field among (HE, EHT, UHR)-LTF (long training field), (HE, EHT, UHR)-STF (short training field), L-SIG, (HE, EHT, U, UHR)-SIG). When AP 1 is capable of transmitting and receiving in a wide bandwidth, STA 1 may transmit a wide bandwidth (e.g., 80 MHz bandwidth) PPDU (620) to AP 1, and AP 1 receives an 80 MHz bandwidth PPDU from STA 1. AP 1 can transmit a BA (Block Acknowledgement) frame to STA 1 after SIFS after receiving UL PPDU (620) from STA 1.

[0075] Referring back to FIGS. 6A and 6B , AP 1 may return to power-saving operation after STA 1's TXOP ends. That is, AP 1 may operate only on the 20 MHz main channel to reduce power consumption after operating with a bandwidth greater than 20 MHz. AP 1 may explicitly signal this with a beacon frame or the like, or may implicitly operate on the 20 MHz channel after the TXOP ends. For example, if the AP does not receive a frame from STA 1 for a certain period of time (e.g., PIFS time), or if the AP does not receive a frame from STA 1 for a certain period of time after transmitting a frame to STA 1, the AP reduces its operating bandwidth again to operate on the 20 MHz channel.

[0076]

[0077] FIG. 7 is a timing diagram illustrating a seventh embodiment of a method for expanding the bandwidth of an AP in power-saving operation.

[0078] Referring to FIG. 7, AP 1 and STA 1 associated with AP 1 may operate. AP 1 may perform a power-saving operation. The power-saving operation performed by AP 1 may be an operation to reduce bandwidth (e.g., transmission and reception bandwidth). For example, instead of operating in the original operating bandwidth of 80 MHz, AP 1 may operate only in a 20 MHz bandwidth to save power. Since AP 1 performs the power-saving operation, AP 1 may perform CCA and transmission and reception operations only in the 20 MHz primary channel. AP 1 may transmit a beacon frame (700) or a probe response frame through the 20 MHz primary channel. AP 1 may indicate that it operates only on the 20 MHz primary channel by setting the Supported Channel Width set bit in the HT Capabilities info field of the MAC header of the beacon frame (700) or probe response frame transmitted by AP 1 and / or the Channel Width field in the VHT Capabilities info field to 0. Alternatively, the power saving operation performed by AP 1 may be an operation pre-negotiated with STAs associated with AP 1 (e.g., STAs including STA 1). AP 1 and STA 1 may have negotiated the power saving operation, and STA 1 may be aware of the operating bandwidth and channel of AP 1, which is the 20 MHz primary channel.

[0079] AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 (e.g., delay time required for switching the operating bandwidth of the transceiver, etc.) during a negotiation process with STAs connected to AP 1 (e.g., STAs including STA 1). For example, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in an association response frame during an association process with STAs connected to AP 1 (e.g., STAs including STA 1). Alternatively, AP 1 can indicate requirements for expanding the transmission and reception bandwidth of AP 1 in the form of capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) in a beacon frame (700) and / or a probe response frame transmitted by AP 1. During the connection process, information for identifying AP 1 (e.g., an AID (association identifier) ​​that can indicate AP 1) may also be negotiated or indicated. Alternatively, AP 1 may indicate requirements for expanding the transmission and reception bandwidth of AP 1 as a separate element in a beacon frame (200) and / or a probe response frame transmitted by AP 1. Alternatively, AP 1 may exchange requirements for expanding the transmission and reception bandwidth of AP 1 through an action frame exchange with AP 1 and STAs connected to AP 1 (e.g., STAs including STA 1), and the action frame may include capabilities (e.g., EHT capabilities element, UHR capabilities element, etc.) and / or a separate element to indicate requirements for expanding the transmission and reception bandwidth of AP 1.

[0080] STA 1 may want to transmit an uplink frame (730). For example, the uplink frame (730) may include a PHY layer protocol data unit (PPDU), a MAC layer protocol data unit (MPDU), or an aggregated-MPDU (A-MPDU). STA 1 may perform a channel access operation. The channel access operation may be an EDCA backoff operation and an EDCA TXOP (transmit opportunity) acquisition procedure. Success of the channel access operation means that the backoff counter reaches 0 and transmission is determined at a slot boundary where the backoff counter reaches 0. STA 1 may want to transmit the uplink frame (730) with a wider channel bandwidth than the channel bandwidth in which AP 1 is operating. STA 1 can perform CCA operation for PIFS (Priority Inter Frame Space) time on a subchannel (e.g., 20 MHz subchannel, 40 MHz subchannel, etc.) before the end time of EDCA backoff. After PIFS, STA 1 can transmit UL PPDU (711) on 20 MHz main channel and simultaneously transmit UL PPDU (711) on empty subchannel(s) (20 MHz bandwidth channels). The total bandwidth transmitted by STA 1 can be greater than 20 MHz (40 MHz, 80 MHz). STA 1 can obtain TXOP (Transmit Opportunity) by transmitting UL PPDU (711).

[0081] The UL PPDU (711), which is the first frame transmitted by STA 1 within the TXOP, can be transmitted with a bandwidth wider than 20 MHz (e.g., 80 MHz). The UL PPDU (711) that STA 1 transmits for the first time within the TXOP can be duplicated and transmitted for each 20 MHz channel. That is, multiple PPDUs (711) can be transmitted. As a more detailed example, when STA 1 transmits a frame using an 80 MHz bandwidth, STA 1 simultaneously transmits identical PPDUs (711) that are duplicated on four 20 MHz channels. The PPDUs (711) that are transmitted for the first time may include an MU-RTS trigger frame. Hereinafter, the PPDU (711) that is transmitted for the first time is referred to as an MU-RTS trigger frame. The MU-RTS trigger frame is also referred to as an MU-RTS frame. The MU-RTS trigger frame (711) transmitted by STA 1 may include information indicating a bandwidth (e.g., 80 MHz bandwidth) that AP 1 should use. The MU-RTS trigger frame (711) includes an indicator that can identify AP 1 (e.g., all or part of an AID (association identifier) ​​and / or a MAC address predetermined for AP 1). The bandwidth that AP 1 should use and the indicator that can identify AP 1 may be included in at least one of a user info field or a common info field, which are fields included in the MU-RTS trigger frame (711). AP 1 adds padding (713) (e.g., padding field, padding bit) to the last part of the MU-RTS trigger frame (711) so that the time required for AP 1 to switch the transceiver operation to a wide channel bandwidth is equal to or longer than the time required. The time required for AP 1 to prepare the transceiver may be as long as the requirements for the negotiated transmit and receive bandwidth expansion (e.g., delay time required for the transceiver operating bandwidth to be switched, etc.).Padding (713) is added to increase the time length of the frame (711). That is, during the length of the padding (713) of the MU-RTS frame (711) transmitted by STA 1, AP 1 can switch the transceiver to operate to a wider channel bandwidth. AP 1 can receive the MU-RTS trigger frame (711) transmitted by STA 1. AP 1 checks the bandwidth (e.g., 80 MHz) indicated by the MU-RTS trigger frame (711) and switches the transceiver to transmit and receive on the 80 MHz channel. AP 1 transmits a CTS frame (720) on the 80 MHz channel an SIFS time after the time at which reception of the MU-RTS trigger frame (711) is completed. STA 1 transmits a UL PPDU (730) on an 80MHz channel after an SIFS time from the time when reception of the CTS frame (720) of AP 1 is completed. AP 1 receives the UL PPDU (730) from STA 1 using the 80MHz channel. AP 1 can transmit a BA (Block Acknowledgement) frame to STA 1 after an SIFS time after receiving the UL PPDU (730) of STA 1. Meanwhile, the function of the MU-RTS trigger frame can be replaced by a BSRP (buffer status report poll) trigger frame. STA 1 transmits the BSRP trigger frame to AP 1. The BSRP trigger frame indicates the bandwidth that STA 1 wants to use. The BSRP trigger frame includes padding having a length equal to or longer than the requirement for expanding the transmission and reception bandwidth of AP 1.

[0082] AP 1 can return to power saving operation after STA 1's TXOP ends. That is, AP 1 can operate only on the 20 MHz main channel to reduce power consumption after operating with a bandwidth greater than 20 MHz. AP 1 can explicitly notify this to STAs through a beacon frame, etc., or can operate on the 20 MHz channel implicitly after the TXOP ends. For example, if the AP does not receive a frame from STA 1 for a certain period of time (e.g., PIFS time), or if the AP does not receive a frame from STA 1 for a certain period of time after transmitting a frame to STA 1, the AP reduces the operating bandwidth again and operates on the 20 MHz channel.

[0083]

[0084] Hereinafter, a procedure for bandwidth expansion during power saving operation is described. Here, "bandwidth expansion" refers to an operation for temporarily expanding a bandwidth used for communication. "Bandwidth" may refer to a frequency band. The term "bandwidth" may be used with substantially the same meaning as "channel." The procedure for bandwidth expansion may be performed by an AP and an STA. An AP in a power saving state may communicate using a primary channel and some of the secondary channels. For example, an AP and an STA in a power saving state may communicate using only the primary channel. Here, the bandwidth of the primary channel may be 20 MHz. According to one embodiment of the present disclosure, an AP and an STA in a power saving state may temporarily expand a bandwidth used for communication by performing a procedure for bandwidth expansion. In other words, communication may be performed using the channel used for power saving operation and at least one additional channel. This expanded bandwidth is referred to as an extension channel. That is, the extension channels refer to channels that an AP and an STA in a power saving state temporarily use for data transmission or reception. An extension channel may include a primary channel and secondary channels. The total bandwidth of the extension channel may be equal to or less than the maximum bandwidth available to the AP.

[0085]

[0086] FIG. 8 illustrates a flowchart of a communication procedure during a power-saving operation according to one embodiment of the present disclosure. The procedure illustrated in FIG. 8 is performed by an STA (e.g., STA 1 of FIG. 2 ). The STA illustrated in FIG. 8 is an STA connected to an AP (e.g., AP 1 of FIG. 2 ).

[0087] Referring to FIG. 8, in step S801, the STA acquires information related to a power-saving operation. For example, the information related to the power-saving operation may include at least one of the time required to switch the operating channel, the requirements required for bandwidth expansion, or information indicating whether the power-saving operation is performed. Here, the time required to switch the operating channel refers to the time required for the AP operating on the channel used for the power-saving operation (e.g., the 20 MHz primary channel) to switch, change, or control the hardware or software such as the transceiver to operate on the extension channel. The information related to the power-saving operation may be acquired through negotiations related to the power-saving operation between the AP and the STA. Alternatively, the information related to the power-saving operation may be acquired from a frame transmitted from the AP (e.g., the beacon frame (200) of FIG. 2). The frame transmitted from the AP may be a beacon frame or a probe response frame. The STA may receive the frame transmitted from the AP via the primary channel.

[0088] In step S803, the STA performs a CCA operation. Here, CCA refers to an operation for detecting the physical availability of a wireless channel. CCA may be performed for a time period equal to the PIFS. CCA may be performed so that it ends when a frame containing information related to bandwidth extension (e.g., the RTS frame (311) of FIG. 2) is transmitted. CCA may be performed using at least some of the primary channel or secondary channel.

[0089] In step S805, the STA transmits a frame including information related to bandwidth extension. For example, the frame including information related to bandwidth extension may include at least one of a PPDU (e.g., UL PPDU (211) of FIG. 2), a CTS frame (e.g., a CTS-to-self frame (410) of FIG. 4), an RTS frame (e.g., an RTS frame (311) of FIG. 3), an MU-RTS frame (e.g., an MU-RTS trigger frame (711) of FIG. 7), a QoS Null frame, or an NDP (e.g., an NDP (510) of FIG. 5). The frame including information related to bandwidth extension may be transmitted to the AP. The information related to bandwidth extension includes information about an extension channel. The extension channel includes at least one of a primary channel and secondary channels. The frame including information related to bandwidth extension may be transmitted through the extension channel.

[0090] In step S807, the STA transmits a data frame (e.g., UL PPDU (220) of FIG. 2) based on information related to bandwidth extension. For example, the STA may transmit the data frame based on information about a channel included in the information related to bandwidth extension. In other words, the data frame may be transmitted through a channel indicated by the information about the channel. For example, if the information about the channel indicates a primary channel and a secondary channel with a bandwidth of 20 MHz, the data frame may be transmitted through the primary channel and the secondary channel with a bandwidth of 20 MHz.

[0091]

[0092] FIG. 9 illustrates a flowchart of a communication procedure during a power-saving operation according to one embodiment of the present disclosure. The procedure illustrated in FIG. 9 is performed by an AP (e.g., AP 1 of FIG. 2 ). The AP illustrated in FIG. 9 is an AP connected to an STA (e.g., STA 1 of FIG. 2 ). The AP illustrated in FIG. 9 may be an AP performing a power-saving operation. In other words, the AP may be an AP operating only on the primary channel.

[0093] Referring to FIG. 9, in step S901, the AP transmits information related to a power-saving operation. For example, the information related to the power-saving operation may include at least one of the time required to switch the operating channel, requirements required for bandwidth expansion, or information indicating whether the power-saving operation is performed. Here, the time required to switch the operating channel refers to the time required for the AP operating on the channel used for the power-saving operation (e.g., 20 MHz primary channel) to switch, change, or control hardware or software such as a transceiver to operate on the extension channel. The information related to the power-saving operation may be transmitted during a negotiation process related to the power-saving operation between the AP and the STA. Alternatively, the information related to the power-saving operation may be transmitted using a frame (e.g., a beacon frame (200) of FIG. 2). For example, the AP may transmit information related to the power-saving operation using a beacon frame or a probe response frame. The AP may transmit information related to the power-saving operation through the primary channel.

[0094] In step S903, the AP performs a CCA operation. Here, CCA refers to an operation for detecting whether a wireless channel is physically available. CCA can be performed on the primary channel. After performing the CCA operation, the AP can transmit the CCA result to the STA. In other words, the AP can transmit information indicating whether the wireless channel is physically available to the STA.

[0095] In step S905, the AP receives a frame including information related to bandwidth extension. The frame including information related to bandwidth extension may be received from an STA. For example, the frame including information related to bandwidth extension may include at least one of a PPDU (e.g., UL PPDU (211) of FIG. 2), a CTS frame (e.g., a CTS-to-self frame (410) of FIG. 4), an RTS frame (e.g., an RTS frame (311) of FIG. 3), an MU-RTS frame (e.g., an MU-RTS trigger frame (711) of FIG. 7), a QoS Null frame, or an NDP (e.g., an NDP (510) of FIG. 5). The information related to bandwidth extension includes information about an extension channel. The extension channel includes at least one of a primary channel and secondary channels. After receiving information related to bandwidth extension, the AP may switch an operating channel from the primary channel to the extension channel to perform communication on the extension channel. After switching the operating channel, the AP may transmit a response frame (e.g., a CTS frame (320) of FIG. 3). For example, the response frame may include a CTS frame. Switching the operating channel may include an operation for controlling the AP's transceiver to communicate via an extension channel.

[0096] In step S907, the AP receives a data frame (e.g., UL PPDU (330) of FIG. 3) based on information related to bandwidth extension. For example, the AP may receive the data frame based on information about an extension channel included in the information related to bandwidth extension. In other words, the data frame may be received via the extension channel. For example, if the information about the extension channel indicates a primary channel and a subchannel with a bandwidth of 20 MHz, the data frame may be received via the primary channel and a subchannel with a bandwidth of 20 MHz.

[0097]

[0098] Although steps S805 and S807, or steps S905 and S907, are described separately in FIGS. 8 and 9 , steps S805 and S807, or steps S905 and S907, may be performed as a single step according to one embodiment of the present disclosure. For example, information related to bandwidth extension may be included in a data frame. For example, information related to bandwidth extension may be included in a preamble of a data frame (e.g., preamble (611) of FIG. 6 ).

[0099]

[0100] Below, a detailed embodiment of the bandwidth expansion procedure is described. The bandwidth expansion procedure may be performed after a power-saving operation is performed by exchanging information related to negotiation between the AP and STA, or by exchanging information related to the power-saving operation. For example, the bandwidth expansion procedure described below may be performed after step S801 of FIG. 8 or step S901 of FIG. 9.

[0101]

[0102] FIG. 10 illustrates a flowchart of a bandwidth expansion procedure according to one embodiment of the present disclosure. The procedure of FIG. 10 is performed by an STA (e.g., STA 1 of FIG. 2 ).

[0103] Referring to FIG. 10, in step S1001, the STA acquires CCA information. The CCA information can be acquired through a CCA operation. CCA information is information indicating whether a wireless channel is physically available. The STA can perform the CCA operation on all operating channels. For example, the STA can perform the CCA operation starting from PIFS before the time when the backoff for acquiring the TXOP is completed. Alternatively, the CCA information can be received from an AP (e.g., AP 1 in FIG. 2).

[0104] In step S1003, the STA may transmit a control frame. For example, the control frame may include at least one of a CTS frame, a CTS-to-Self frame (e.g., the CTS-to-self frame (410) of FIG. 4), an RTS frame (e.g., the RTS frame (311) of FIG. 3), or an MU-RTS frame (e.g., the MU-RTS trigger frame (711) of FIG. 7). The STA may transmit the control frame through all operating channels. Here, the control frames of each channel may be the same control frame. For example, the control frames of each channel may be duplicated control frames. The control frame includes information related to bandwidth extension. The information related to bandwidth extension may include information indicating channels used for communication and bandwidths of the channels. The control frame may include padding (e.g., padding (713) of FIG. 7). The total time length of the control frame and the padding may be equal to or longer than the time for which the AP's transceiver switches. That is, the total time length of the control frame and padding can be equal to or longer than the time required to switch the operating channel.

[0105] In step S1005, the STA receives a confirmation frame (e.g., a CTS frame (320) of FIG. 3). For example, the confirmation frame may be a CTS frame. The STA may receive the confirmation frame from the AP. For example, the STA may receive the confirmation frame through the primary channel. As another example, the STA may receive the confirmation frame through the channels through which the control frame was transmitted. The confirmation frame may include information indicating a channel that is ready for communication. For example, the confirmation frame may indicate a channel that is ready for communication using the SIG field of the PHY preamble. After receiving the confirmation frame, the STA may transmit data using the extension channel.

[0106]

[0107] FIG. 11 illustrates a flowchart of a bandwidth expansion procedure according to one embodiment of the present disclosure. The procedure of FIG. 11 is performed by an AP. The procedure of FIG. 11 may correspond to the procedure of FIG. 10.

[0108] In step S1101, the AP performs a CCA operation. Here, the CCA operation refers to an operation for detecting whether a wireless channel is physically available. The CCA operation can be performed on the primary channel. After performing the CCA operation, the AP can transmit the CCA result to the STA. In other words, the AP can transmit information indicating whether the wireless channel is physically available to the STA.

[0109] In step S1103, the AP may receive a control frame. For example, the control frame may include at least one of a CTS frame, a CTS-to-Self frame (e.g., the CTS-to-self frame (410) of FIG. 4), an RTS frame (e.g., the RTS frame (311) of FIG. 3), or an MU-RTS frame (e.g., the MU-RTS trigger frame (711) of FIG. 7). The AP may receive the control frame through all operating channels. Here, the control frames of each channel may be the same control frame. For example, the control frames of each channel may be duplicated control frames. The control frame includes information related to bandwidth extension. The information related to bandwidth extension may include information indicating channels used for communication and bandwidths of the channels. The control frame may include padding (e.g., padding (713) of FIG. 7). The total time length of the control frame and the padding may be equal to or longer than the time it takes for the AP to switch operating channels. The AP can switch the operating channel after receiving the control frame. The AP can switch the operating channel while receiving the control frame and padding.

[0110] In step S1105, the AP transmits a confirmation frame (e.g., a CTS frame (320) of FIG. 3). For example, the confirmation frame may be a CTS frame. The AP may transmit the confirmation frame to the STA. For example, the AP may transmit the confirmation frame over the primary channel. As another example, the AP may transmit the confirmation frame over the channels on which the control frame was received. The confirmation frame may include information indicating a channel that is ready for communication. For example, the confirmation frame may indicate a channel that is ready for communication using the SIG field of the PHY preamble.

[0111]

[0112] FIG. 12 illustrates a flowchart of a bandwidth expansion procedure according to one embodiment of the present disclosure. FIG. 12 describes the procedure performed by an STA.

[0113] Referring to FIG. 12, in step S1201, the STA acquires CCA information. The CCA information can be acquired through a CCA operation. CCA information is information indicating whether a wireless channel is physically available. The STA can perform the CCA operation on all operating channels. For example, the STA can perform the CCA operation starting from PIFS before the time when the backoff for acquiring the TXOP is completed. Alternatively, the CCA information can be received from the AP.

[0114] In step S1203, the STA transmits information related to bandwidth expansion. The information related to bandwidth expansion may be included in at least one of a preamble (e.g., preamble (611) of FIG. 6A), an NDP (e.g., NDP (510) of FIG. 5), or a QoS Null. For example, the information related to bandwidth expansion may be transmitted using an NDP or QoS Null frame. As another example, the information related to bandwidth expansion may be transmitted using a preamble included in a data frame. When the information related to bandwidth expansion is transmitted using a preamble, the preamble may be repeatedly transmitted until the bandwidth switching is completed. The information related to bandwidth expansion may be transmitted using the entire communication bandwidth. The information related to bandwidth expansion may include information indicating channels used for communication.

[0115] In step S1205, the STA transmits data based on information related to bandwidth extension. The data may be transmitted using at least one data frame (e.g., data frames 620 and 630 of FIG. 6B ). Here, at least one data frame may be a frame including the preamble of step S1203. In other words, steps S1203 and S1205 may be performed using at least one data frame. At least one data frame may further include a midamble (e.g., midamble 640 of FIG. 6B ). The data may be transmitted from the time when bandwidth switching is completed. The data may be transmitted using the entire communication bandwidth.

[0116]

[0117] FIG. 13 illustrates a flowchart of a bandwidth expansion procedure according to one embodiment of the present disclosure. FIG. 13 describes a procedure performed by an AP (e.g., AP 1 of FIG. 2 ). The procedure of FIG. 13 may correspond to the procedure of FIG. 12 .

[0118] Referring to FIG. 13, in step S1301, the AP acquires CCA information. The CCA information can be acquired through a CCA operation. CCA information is information indicating whether a wireless channel is physically available. The AP can perform a CCA operation on the primary channel. After performing the CCA operation, the AP can transmit the result of the CCA to an STA (e.g., STA 1 in FIG. 2). In other words, the AP can transmit information indicating whether the wireless channel is physically available to the STA.

[0119] In step S1303, the AP receives information related to bandwidth expansion. The information related to bandwidth expansion may be included in at least one of a preamble (e.g., preamble (611) of FIG. 6A), an NDP (e.g., NDP (510) of FIG. 5), or a QoS Null. For example, the information related to bandwidth expansion may be received using an NDP or QoS Null frame. As another example, the information related to bandwidth expansion may be received using a preamble included in a data frame. If the information related to bandwidth expansion is received using a preamble, the preamble may be repeatedly received until the bandwidth switching is completed. The information related to bandwidth expansion may be received using the entire communication band. The information related to bandwidth expansion may include information indicating channels used for communication.

[0120] In step S1305, the AP receives data based on information related to bandwidth expansion. The data may be received using at least one data frame (e.g., data frames 620 and 630 of FIG. 6B ). Here, at least one data frame may be a frame including the preamble of step S1303. In other words, steps S1303 and S1305 may be performed using at least one frame. At least one data frame may further include a midamble (e.g., midamble 640 of FIG. 6B ). Data may be received from the time when bandwidth switching is completed. Data may be received using the entire communication bandwidth.

[0121]

[0122] In the embodiments of FIGS. 12 and 13, multiple preambles or midambles may be transmitted. The multiple preambles or midambles may have a duration longer than or equal to the time it takes for the AP to switch between operating channels. In other words, multiple preambles or midambles may be transmitted so that data can be transmitted after the AP switches between operating channels.

[0123]

[0124] While bandwidth limitation is assumed as an example of a power-saving operation in this disclosure, the power-saving operation of this disclosure is not limited thereto. The power-saving operation may include at least one of bandwidth limitation, transmission signal strength limitation, or transmission time limitation. However, any power-saving operation applicable to a person skilled in the art, not limited to the described operation, may be included in the power-saving operation of this disclosure.

[0125]

[0126] The methods according to the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either singly or in combination. The program instructions recorded on the computer-readable medium may be those specifically designed and constructed for the present invention, or may be known and available to those skilled in the computer software art.

[0127] Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include not only machine language codes generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

[0128] Although the present invention has been described with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

[0129] The present disclosure can be used in devices and recording media in a wireless LAN system.

Claims

1. A method for operation of STA (station) in a wireless LAN system, A step of acquiring information related to a power saving operation of an AP (access point); A step of transmitting information related to a band expansion operation for transmitting data using the channel used in the above power saving operation and at least one additional channel; and A step of transmitting data based on at least one of the information related to the bandwidth expansion or the information related to the power saving operation, Information related to the above power saving operation includes information about the time required to switch the operating channel of the AP, A method wherein the information related to the above bandwidth extension includes information indicating at least one additional channel.

2. In paragraph 1, Further comprising a step of performing a CCA (clear channel assessment) operation from a predefined time prior to the start of transmission of information related to the above bandwidth expansion, The above CCA operation is performed in the above operation channel.

3. In paragraph 1, Further comprising the step of receiving a response to information related to the above bandwidth extension, The above data is transmitted after the above response is received.

4. In paragraph 1, A method in which information related to the above power saving operation is obtained using a beacon frame or probe response frame transmitted from the AP.

5. In paragraph 1, A method in which information related to the above power saving operation is obtained based on negotiation with the AP.

6. In paragraph 1, Information related to the above bandwidth extension is transmitted using a control frame.

7. In paragraph 6, The time length of the above control frame is longer than or equal to the time required to switch the above operation channel.

8. In paragraph 6, The above control frame includes padding, The sum of the time lengths of the above padding and the above control frame is longer than or equal to the time required to switch the operating channel.

9. In paragraph 1, A method in which information related to the above bandwidth extension is transmitted using a preamble of a data frame for transmitting the above data.

10. In paragraph 1, A method in which information related to the above bandwidth extension is transmitted using the above operating channel.

11. In paragraph 1, The above data is transmitted using a data frame including a preamble and a midamble, The above midamble is transmitted after the time required for switching the operating channel has elapsed.

12. In a method for operating an AP (access point) in a wireless LAN system, A step of transmitting information related to a power saving operation; A step of receiving information related to band expansion, which is an operation for transmitting data using a channel used in the above power saving operation and at least one additional channel; A step of switching the operating channel based on information related to the above bandwidth expansion; and A step of receiving data based on at least one of information related to the bandwidth expansion or information related to the power saving operation, Information related to the above power saving operation includes information about the time for switching the operation channel, A method wherein the information related to the above bandwidth extension includes information indicating at least one additional channel.

13. In paragraph 12, A method further comprising the step of transmitting a response to information related to said bandwidth extension.

14. In paragraph 12, Information related to the above power saving operation is transmitted using a beacon frame or a probe response frame.

15. In paragraph 12, Information related to the above power saving operation is transmitted using a beacon frame or a probe response frame.

16. In paragraph 12, A method in which information related to the above power saving operation is transmitted based on negotiation for the above power saving operation.

17. In paragraph 12, Information related to the above bandwidth extension is received using a control frame, The above control frame includes padding, The time length of the above control frame is longer than or equal to the time for switching the operation channel.

18. In paragraph 12, The above data is transmitted using a data frame including at least one of a preamble and a midamble, The above preamble includes information related to the bandwidth extension, The above midamble is transmitted after the time required for the AP to switch the operating channel has elapsed.

19. In a wireless LAN system, at STA (station), Transmitter and receiver; and Including a processor connected to the above transceiver, The above processor, Obtain information related to power saving operation of AP (access point), Transmitting information related to band expansion, which is an operation for transmitting data using the channel used in the above power saving operation and at least one additional channel, configured to transmit data based on at least one of the information related to the above bandwidth expansion or the information related to the above power saving operation, Information related to the above power saving operation includes information about the time required to switch the operating channel of the AP, Information related to the above bandwidth extension is a STA including information indicating at least one additional channel.

20. In a method for operating an AP (access point) in a wireless LAN system, Transmitter and receiver; and Including a processor connected to the above transceiver, The above processor, Transmits information related to power saving operations, Receive information related to band expansion, which is an operation for transmitting data using a channel used in the above power saving operation and at least one additional channel, Switch the operating channel based on the information related to the above bandwidth expansion, configured to receive data based on at least one of the information related to the above bandwidth expansion or the information related to the above power saving operation, Information related to the above power saving operation includes information about the time for switching the operation channel, Information related to the above bandwidth extension, an AP including information indicating at least one additional channel.

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