WO2016195211A1 - Method and apparatus for configuring txop for sta operating in power save mode in wireless lan - Google Patents

Abstract

Disclosed is a method and apparatus for configuring a TXOP for an STA operating in a power save mode in a wireless LAN. A method for a power save mode operation of an STA during a TXOP in a wireless LAN may comprise the steps of: receiving, by an STA, a first PPDU from an AP in a TXOP; when the STA is a receiving STA for the first PPDU, performing, by the STA, an operation in the awake state during an awake duration configured in the TXOP on the basis of the first PPDU; when the STA is the receiving STA, performing, by the STA, an operation in the doze state until the TXOP expires after the expiration of the awake duration; when the STA is not the receiving STA, performing, by the STA, an operation in the doze state during an awake duration configured in the TXOP on the basis of the first PPDU; and when the STA is not the receiving STA, performing, by the STA, a transition from the doze state to the awake state after the expiration of the awake duration so as to receive a second PPDU from the AP in the TXOP.

Description

Method and apparatus for setting TXOP for STA operating in power save mode in WLAN

The present invention relates to wireless communication, and more particularly, to a method and apparatus for setting a transmission opportunity (TXOP) for a station (STA) operating in a power save mode in a WLAN.

Discussion is underway for the next generation wireless local area network (WLAN). In next-generation WLANs, 1) enhancements to the Institute of Electronics and Electronics Engineers (IEEE) 802.11 physical physical access (PHY) and medium access control (MAC) layers in the 2.4 GHz and 5 GHz bands, and 2) spectral efficiency and area throughput. aim to improve performance in real indoor and outdoor environments, such as environments with interference sources, dense heterogeneous network environments, and high user loads. .

The environment mainly considered in the next-generation WLAN is a dense environment having many access points (APs) and a station (STA), and improvements in spectral efficiency and area throughput are discussed in such a dense environment. In addition, in the next generation WLAN, there is an interest in improving practical performance not only in an indoor environment but also in an outdoor environment, which is not much considered in a conventional WLAN.

Specifically, in the next-generation WLAN, there is a great interest in scenarios such as wireless office, smart home, stadium, hotspot, building / apartment, and AP based on the scenario. And STA are discussing about improving system performance in a dense environment with many STAs.

In addition, in the next-generation WLAN, there will be more discussion about improving system performance in outdoor overlapping basic service set (OBSS) environment, improving outdoor environment performance, and cellular offloading, rather than improving single link performance in one basic service set (BSS). It is expected. The directionality of these next-generation WLANs means that next-generation WLANs will increasingly have a technology range similar to that of mobile communications. Considering the recent situation in which mobile communication and WLAN technology are discussed together in the small cell and direct-to-direct (D2D) communication area, the technical and business convergence of next-generation WLAN and mobile communication is expected to become more active.

It is an object of the present invention to provide a method for setting a TXOP for an STA operating in a power save mode in a WLAN.

Still another object of the present invention is to provide an apparatus for setting a TXOP for an STA operating in a power save mode in a WLAN.

According to an aspect of the present invention, a method of operating a power save mode of a station on a transmission opportunity (TXOP) in a wireless LAN according to an aspect of the present invention is performed by the STA from an access point (AP) on the TXOP. 1, when the STA is a receiving STA of the first PPDU, the STA wakes up during an awake duration set based on the first PPDU on the TXOP; Operating in a doze state before expiration of the TXOP after expiration of the awake duration, when the STA is not the receiving STA, when the STA is not the receiving STA, Operating in the doze state during the awake duration set based on the first PPDU on the TXOP and when the STA is not the receiving STA, After expiration of the duration of the wake state transition from the doze state to the awake it may include the step of receiving the PPDU 2 on the TXOP from the AP.

In accordance with another aspect of the present invention, an STA operating in a power save mode on a transmission opportunity (TXOP) in a WLAN according to another aspect of the present invention provides a radio frequency (RF) unit for transmitting and receiving a radio signal and the RF unit. The processor may include a processor operatively coupled to the second processor, wherein the processor receives a first physical protocol data unit (PHY) from an access point (APDU) on the TXOP, and the STA receives the first information. In the case of a receiving STA of 1 PPDU, the TXOP operates in an awake state during the awake duration set based on the first PPDU on the TXOP, and when the STA is the receiving STA, after the awake duration expires of the TXOP. If the STA is in a doze state before expiration and the STA is not the receiving STA, during the awake duration set based on the first PPDU on the TXOP If the STA is in a doze state and the STA is not the receiving STA, it may be implemented to switch from the doze state to the awake state after the expiration of the awake duration to receive a second PPDU on the TXOP from the AP. have.

By setting the transmission opportunity (TXOP) for the STA (station) operating in the power save mode can reduce the power consumption of the STA.

1 is a conceptual diagram illustrating a structure of a wireless local area network (WLAN).

2 is a conceptual diagram illustrating a frame exchange procedure between an AP and a plurality of STAs in a duration of TXOP according to an embodiment of the present invention.

3 is a conceptual diagram illustrating a frame exchange procedure between an AP and a plurality of STAs in a duration of a TXOP according to an embodiment of the present invention.

4 is a conceptual diagram illustrating a frame exchange procedure between an AP and a plurality of STAs according to an embodiment of the present invention.

5 is a conceptual diagram illustrating a DL MU PPDU format according to an embodiment of the present invention.

6 is a conceptual diagram illustrating transmission of an UL MU PPDU according to an embodiment of the present invention.

7 is a block diagram illustrating a wireless device to which an embodiment of the present invention can be applied.

1 is a conceptual diagram illustrating a structure of a wireless local area network (WLAN).

1 shows the structure of the infrastructure basic service set (BSS) of the Institute of Electrical and Electronic Engineers (IEEE) 802.11.

Referring to the top of FIG. 1, the WLAN system may include one or more infrastructure BSSs 100 and 105 (hereinafter, BSS). The BSSs 100 and 105 are a set of APs and STAs such as an access point 125 and a STA1 (station 100-1) capable of successfully synchronizing and communicating with each other, and do not indicate a specific area. The BSS 105 may include one or more joinable STAs 105-1 and 105-2 to one AP 130.

The BSS may include at least one STA, APs 125 and 130 for providing a distribution service, and a distribution system (DS) 110 for connecting a plurality of APs.

The distributed system 110 may connect several BSSs 100 and 105 to implement an extended service set (ESS) 140 which is an extended service set. The ESS 140 may be used as a term indicating one network in which one or several APs 125 and 230 are connected through the distributed system 110. APs included in one ESS 140 may have the same service set identification (SSID).

The portal 120 may serve as a bridge for connecting the WLAN network (IEEE 802.11) with another network (for example, 802.X).

In the BSS as shown in the upper part of FIG. 1, a network between the APs 125 and 130 and a network between the APs 125 and 130 and the STAs 100-1, 105-1 and 105-2 may be implemented. However, it may be possible to perform communication by setting up a network even between STAs without the APs 125 and 130. A network that performs communication by establishing a network even between STAs without APs 125 and 130 is defined as an ad-hoc network or an independent basic service set (BSS).

1 is a conceptual diagram illustrating an IBSS.

Referring to the bottom of FIG. 1, the IBSS is a BSS operating in an ad-hoc mode. Since IBSS does not contain an AP, there is no centralized management entity. That is, in the IBSS, the STAs 150-1, 150-2, 150-3, 155-4, and 155-5 are managed in a distributed manner. In the IBSS, all STAs 150-1, 150-2, 150-3, 155-4, and 155-5 may be mobile STAs, and access to a distributed system is not allowed, thus making a self-contained network. network).

A STA is any functional medium that includes medium access control (MAC) conforming to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard and a physical layer interface to a wireless medium. May be used to mean both an AP and a non-AP STA (Non-AP Station).

The STA may include a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit ( It may also be called various names such as a mobile subscriber unit or simply a user.

Hereinafter, in the embodiment of the present invention, the data (or frame) transmitted from the AP to the STA is downlink data (or downlink frame), and the data (or frame) transmitted from the STA to the AP is uplink data (or uplink frame). It can be expressed by the term). In addition, the transmission from the AP to the STA may be expressed in terms of downlink transmission, and the transmission from the STA to the AP may be expressed in terms of uplink transmission.

In addition, each of the PHY protocol data units (PPDUs), frames, and data transmitted through downlink transmission may be expressed in terms of a downlink PPDU, a downlink frame, and downlink data. The PPDU may be a data unit including a PPDU header and a physical layer service data unit (PSDU) (or MAC protocol data unit (MPDU)). The PPDU header may include a PHY header and a PHY preamble, and the PSDU (or MPDU) may be a data unit including a frame (or an information unit of a MAC layer) or indicating a frame. The PHY header may be referred to as a physical layer convergence protocol (PLCP) header in another term, and the PHY preamble may be expressed as a PLCP preamble in another term.

In addition, each of the PPDUs, frames, and data transmitted through uplink transmission may be represented by the term uplink PPDU, uplink frame, and uplink data.

In the existing WLAN system, the entire bandwidth is used for downlink transmission to one STA and uplink transmission of one STA based on single-orthogonal frequency division multiplexing (SUDM) transmission. In addition, in the conventional WLAN system, the AP may perform DL (downlink) multi-user (MU) transmission based on MU MIMO (multiple input multiple output), and such transmission may be expressed by the term DL MU MIMO transmission. Can be.

In a WLAN system according to an embodiment of the present invention, an orthogonal frequency division multiple access (OFDMA) based transmission method may be supported for uplink transmission and downlink transmission. In more detail, in the WLAN system according to the embodiment of the present invention, the AP may perform DL MU transmission based on OFDMA, and such transmission may be expressed by the term DL MU OFDMA transmission. When DL MU OFDMA transmission is performed, the AP may transmit downlink data (or downlink frame, downlink PPDU) to each of the plurality of STAs through the plurality of frequency resources on the overlapped time resources. The plurality of frequency resources may be a plurality of subbands (or subchannels) or a plurality of resource units (RUs) (eg, basic resource units (BRUs) defined with different sizes). DL MU OFDMA transmission can be used with DL MU MIMO transmission. For example, DL MU MIMO transmission based on a plurality of space-time streams (or spatial streams) is performed on a specific subband (or subchannel) allocated for DL MU OFDMA transmission. Can be.

In addition, in a WLAN system according to an embodiment of the present invention, UL MU transmission (uplink multi-user transmission) may be supported for a plurality of STAs to transmit data to an AP on the same time resource. Uplink transmission on the overlapped time resource by each of the plurality of STAs may be performed in the frequency domain or the spatial domain.

When uplink transmission by each of the plurality of STAs is performed in the frequency domain, different frequency resources may be allocated as uplink transmission resources for each of the plurality of STAs based on OFDMA. The different frequency resources may be different subbands (or subchannels) or different resource units (RUs). Each of the plurality of STAs may transmit uplink data to the AP through different allocated frequency resources. The transmission method through these different frequency resources may be represented by the term UL MU OFDMA transmission method.

When uplink transmission by each of the plurality of STAs is performed in the spatial domain, different space-time streams (or spatial streams) are allocated to each of the plurality of STAs, and each of the plurality of STAs transmits uplink data through different space-time streams. Can transmit to the AP. The transmission method through these different spatial streams may be represented by the term UL MU MIMO transmission method.

The UL MU OFDMA transmission and the UL MU MIMO transmission may be performed together. For example, UL MU MIMO transmission based on a plurality of space-time streams (or spatial streams) may be performed on a specific subband (or subchannel) allocated for UL MU OFDMA transmission.

In a conventional WLAN system that did not support MU OFDMA transmission, a multi-channel allocation method was used to allocate a wider bandwidth (for example, a bandwidth exceeding 20 MHz) to one UE. The multi-channel may include a plurality of 20 MHz channels when one channel unit is 20 MHz. In the multi-channel allocation method, a primary channel rule is used to allocate a wide bandwidth to the terminal. If the primary channel rule is used, there is a constraint for allocating a wide bandwidth to the terminal. Specifically, according to the primary channel rule, when a secondary channel adjacent to the primary channel is used in an overlapped BSS (OBSS) and 'busy', the STA may use the remaining channels except the primary channel. Can not. Therefore, the STA can transmit the frame only through the primary channel, thereby being limited to the transmission of the frame through the multi-channel. That is, the primary channel rule used for multi-channel allocation in the existing WLAN system may be a big limitation in obtaining high throughput by operating a wide bandwidth in the current WLAN environment where there are not many OBSS.

In an embodiment of the present invention to solve this problem, a WLAN system supporting an orthogonal frequency division multiple access (OFDMA) technique is disclosed. When OFDMA technology is used, a plurality of terminals may be used simultaneously instead of one terminal without using a primary channel rule. Therefore, wide bandwidth operation is possible, and the efficiency of the operation of radio resources can be improved.

In the present invention, a time-frequency structure assumed in a WLAN system according to an embodiment may be as follows.

The fast fourier transform (FFT) size / inverse fast fourier transform (IFFT) size may be defined as N times (N is a natural number, for example, N = 4) of the FFT / IFFT size used in a conventional WLAN system. . For example, 256 FFT / IFFT is applied for a bandwidth of 20 MHz, 512 FFT / IFFT is applied for a bandwidth of 40 MHz, 1024 FFT / IFFT is applied for a bandwidth of 80 MHz, and 2048 FFT for a bandwidth of 160 MHz continuous or discontinuous 160 MHz. / IFFT can be applied.

The subcarrier spacing may be 1 / N times the size of the subcarrier space used in the conventional WLAN system (N is a natural number, for example, 78.125 kHz when N = 4).

The IDFT / DFT length (or effective symbol length) based on inverse discrete fourier transform (IDFT) / discrete fourier transform (DFT) (or FFT / IFFT) may be N times the IDFT / DFT length in the existing WLAN system. . For example, if the IDFT / DFT length is 3.2μs and N = 4 in the existing WLAN system, IDFT / DFT length is 3.2μs * 4 (= 12.8μs) in the WLAN system according to an embodiment of the present invention Can be.

The length of an OFDM symbol may be a value obtained by adding a length of a guard interval (GI) to an IDFT / DFT length. The length of the GI can be various values such as 0.4 μs, 0.8 μs, 1.6 μs, 2.4 μs, 3.2 μs.

Increased IFFT / FFT can be applied in the available system bandwidth in order to improve the throughput of the WLAN system or to improve the robustness against inter-symbol interference (ISI) in an outdoor environment. have. For example, if 128IFFT / FFT (2x IFFT / FFT) or 256IFFT / FFT (4x IFFT / FFT) is applied instead of 64IFFT / FFT in 20MHz bandwidth, the portion of the portion of the cyclic prefix (CP) Reducing the Ratio to Reduce the WLAN system may be designed to obtain throughput gain by the length of the CP. Alternatively, the ratio of CP may be maintained to reduce performance degradation due to ISI in an outdoor environment based on the increased CP duration.

Hereinafter, in the embodiment of the present invention, the operation of the STAs operating in the power save mode within the duration of the TXOP is disclosed. Information on the TXOP for transmission of downlink data / uplink data may be transmitted through a HE (high efficiency) -SIG (signal) field or L (legacy) -SIG (signal) of the PPDU. The information on TXOP is expressed in microsecond units based on 15 bits as in the existing duration field, or expressed in microsecond units or other time units based on x bits (x is any positive integer). Can be.

In an embodiment of the present invention, a method is disclosed in which a plurality of STAs operating in a power save mode are set to a doze state or an awake state based on the information about the TXOP remaining duration. Information on the remaining duration of the TXOP may be expressed as a multiple of the PPDU length being transmitted or a ratio of the entire TXOP.

The STA operating in the power save mode can save power while switching between the doze state and the awake state. The doze state may be a state in which power saving is performed in which transmission / reception of a frame by the STA is not performed, and the awake state may be a state in which transmission / reception of the frame by the STA is performed.

When the STA receiving the PPDU transmitted by the AP satisfies the following condition, the STA may be switched to a doze state (shallow sleep or deep sleep) for a certain duration to maintain the doze state.

The STA that receives the PPDU transmitted by the AP determines whether a partial association identifier (PAID) or group ID indicated by the PPDU matches the STA's PAID, group ID, and if not, the STA is awake. Can be switched to the doze state. Alternatively, the STA that receives the PPDU transmitted by the AP may match the PAID indicated by the PPDU with the STA's PAID, but the RA (receiving address) of the MAC header of the frame included in the PPDU may correspond to the address of the MAC header of the STA. If it does not match, it may transition from the awake state to the doze state. Alternatively, the STA that receives the PPDU may switch to the doze state when the group ID of the PPDU and the group ID of the STA match, but NUM_STA is 0.

In addition, when the STA receives an NDP Announcement Frame (NDP) announcement frame, the PAID indicated by the PPDU carrying the NDP Announcement Frame / NDP Announcement Frame is If 0 and the AID in the STA Info field is not the AID of the STA, the STA may switch from the awake state to the doze state. In addition, when the More data field of the frame received by the STA is 0 and the ACK policy subfield is No ACK or the AP's ACK policy is not No ACK and the AP transmits the ACK frame. The STA may transition from the awake state to the doze state.

Hereinafter, a frame exchange procedure between an AP and a plurality of STAs operating in a power save mode on a duration of a specific TXOP is disclosed.

2 is a conceptual diagram illustrating a frame exchange procedure between an AP and a plurality of STAs in a duration of TXOP according to an embodiment of the present invention.

In FIG. 2, an AP, which is a TXOP holder, may set a TXOP for transmission of a downlink frame. TXOP may mean an opportunity to perform the exchange procedure of the frame through the medium, and TXOP may be a time resource defined by the start time of the exchange procedure and the duration for the exchange procedure. The TXOP holder may be a device that obtained a TXOP. Hereinafter, it will be described on the assumption that the AP is a TXOP holder in the embodiment of the present invention.

The AP may sequentially perform the exchange procedure of the plurality of PPDUs with the plurality of STAs during the TXOP. According to an embodiment of the present invention, the AP may select a PPDU currently transmitted through a PPDU header (eg, a legacy (L) -SIG (signal) field and a high efficiency (SIG) field) of a plurality of PPDUs). As a reference, information about the duration of the remaining TXOP among the entire TXOP and information about the remaining STA to receive the PPDU on the remaining TXOP (for example, partial AID (PAID) or group ID) may be transmitted.

Hereinafter, in the embodiment of the present invention, the remaining TXOPs among the entire TXOPs set may be expressed by the term of the remaining TXOPs. In addition, a STA to receive a frame through a currently transmitted PPDU may be expressed as a target STA, and a STA to receive a frame transmitted through another PPDU to be transmitted after the current PPDU through a remaining TXOP.

According to an embodiment of the present invention, the AP may sequentially exchange frames (or PPDUs) with a plurality of STAs operating in a power save mode during TXOP.

The PPDU header of the PPDU1 210 transmitted by the AP on the TXOP includes the target STA field 240, the remaining STA field 250, the TXOP field 260, the remaining TXOP field 270, and the awake duration field 280. It may include.

The target STA field 240 may include information about a target STA (eg, STA1) that will receive the PPDU1 210.

The remaining STA field 250 includes at least one remaining STA (STA2, STA3) except for a target STA to receive at least one remaining PPDU (eg, PPDU2 230, PPDU3 230, etc.) from the AP during the remaining TXOP. It may include information about.

The TXOP field 260 may include information on the set total TXOP (for example, information on the starting point of the entire TXOP and the duration of the entire TXOP). The overall TXOP may be determined in consideration of transmission times of a plurality of PPDUs (or frames) that the AP transmits to a plurality of STAs in a specific time interval.

The remaining TXOP field 270 may include information on the remaining TXOP (information on the start time of the remaining TXOP and the duration of the remaining TXOP) based on the transmission timing of the PPDU1 210. If PPDU1 210 is the first PPDU transmitted on a TXOP, the remaining TXOPs may be equal to the entire TXOP.

The awake duration field 280 may include information on the awake duration of the target STA in which the target STA (eg, STA1) maintains an awake state. The remaining STAs other than the target STA (eg, STA2 and STA3) maintain the doze state during the awake duration of the indicated target STA based on the awake duration field 280 after switching to the doze state, and the awake duration field If the awake duration of the target STA indicated based on 280 has expired, it may be switched back to the awake state. The AP may transmit a PPDU2 for a specific STA (eg, STA2) among the remaining STAs after the awake duration of the target STA indicated by the awake duration field 280.

The awake duration field 280 may represent an awake duration of the target STA based on the information on the ratio for the remaining TXOP indicated by the remaining TXOP field. For example, the awake duration field 280 may include a bit value corresponding to 1/4, and in this case, the awake duration field 280 may correspond to a target STA corresponding to a quarter of the remaining TXOP. The target STA (eg, STA1) may indicate that the wake state is maintained during the wake duration. When the remaining STAs (eg, STA2 and STA3) are switched to the doze state and the awake duration of the target STA corresponding to 1/4 of the remaining TXOP expires, the remaining STAs (eg, STA2 and STA3) may be switched back to the awake state.

In the operation of specific STAs, STA1, which is the target STA that receives the PPDU1 210 transmitted by the AP, maintains an awake state during the awake duration of the target STA, while maintaining the awake state for the STA1 through the PPDU1 210 transmitted from the AP. A frame (or downlink data) may be received. When the awake duration of the target STA has expired, the STA1 may switch the awake state to the doze state and maintain the doze state for the remaining time after the awake duration of the target STA of the entire TXOP.

In addition, the remaining STAs STA2 and STA3 except for the target STA receiving the PPDU1 210 maintain the doze state during the awake duration of the target STA by decoding the header of the PPDU1 210, and the awake duration of the target STA is reduced. After expiration, it may be switched to the awake state and receive PPDU2 220 which is another PPDU transmitted by the AP. Hereinafter, a method is disclosed in which an AP transmits PPDU2 220 after PPDU1 210 to STA2 which is a target STA of PPDU2 220 on the entire TXOP.

The PPDU header of PPDU2 220, which is another PPDU transmitted in the TXOP, may also include a target STA field, a remaining STA field, a TXOP field, a remaining TXOP field, and an awake duration field.

The target STA field may include information on a target STA (eg, STA2) to receive the PPDU.

The remaining STA field may include information about at least one remaining STA (eg, STA3) except for a target STA that will receive at least one remaining PPDU from the AP during the remaining TXOP.

The TXOP field may include information on all configured TXOPs (for example, information on a start time of all TXOPs and a duration of all TXOPs).

The remaining TXOP field may include information about the remaining TXOP (start time of the remaining TXOP and duration of the remaining TXOP) based on the transmission timing of the PPDU2 220.

The awake duration field may include information on the awake duration of the target STA in which the target STA (eg, STA2) maintains an awake state. The remaining STA (eg, STA3), which is a non-target STA, which is not a target STA, maintains the doze state during the awake duration of the indicated target STA based on the awake duration field after switching to the doze state, and sets the awake duration field. If the awake duration of the target STA indicated on the basis has expired, it may be switched back to the awake state. The AP may transmit the PPDU for the remaining STA (eg, STA3) after the awake duration of the target STA.

In the operation of specific STAs, STA2, which is a target STA that receives the PPDU2 220 transmitted by the AP, receives a frame through the PPDU2 220 transmitted from the AP while maintaining an awake state during the awake duration of the target STA. can do. When the awake duration of the target STA STA2 expires, the STA2 may switch the awake state to the doze state and maintain the doze state for the remaining time after the awake duration of the target STA of the entire TXOP.

In addition, STA3, which is a remaining STA except for the target STA that has received the PPDU2 220, maintains a doze state during the awake duration of the target STA through decoding the header of the PPDU2 220, and the awake duration of the target STA has expired. After the transition to the awake state may receive PPDU3 (230), which is another PPDU transmitted by the AP.

The PPDU header of PPDU3 230, which is another PPDU transmitted in the TXOP, may similarly include a target STA field, a remaining STA field, a TXOP field, a remaining TXOP field, and an awake duration field.

If the PPDU3 230 is the last PPDU transmitted on the TXOP, the remaining STAs do not exist. Therefore, the remaining STA field is a preset specific value for indicating that there is no remaining STA instead of information on the remaining STAs (eg, '0000…'). Alternatively, the remaining STA field may not be included in the PPDU header.

In addition, the awake duration field may be set to 1, and the awake duration field set to 1 may indicate that the entire TXOP expires after the awake duration of STA3.

3 is a conceptual diagram illustrating a frame exchange procedure between an AP and a plurality of STAs in a duration of a TXOP according to an embodiment of the present invention.

In FIG. 3, a procedure of exchanging a PPDU (or frame / data unit) on a TXOP with a plurality of STAs STA1, STA2, and STA3 is disclosed. In FIG. 2, for convenience of description, it is assumed that the PPDU sizes are the same and the TXOP holder is the AP.

The PPDU1 header of PPDU1 (or data unit 1) 310 transmitted by the AP to STA1 may include the remaining TXOP field and the awake duration field. The remaining TXOP field of the PPDU1 header may include information about TXOP1, which is the remaining TXOP of the entire TXOPs, based on the transmission of the PPDU1 310. The awake duration field of the PPDU1 header may include information on the awake duration of the target STA1. The information on the awake duration of the STA1 may include information about a time resource represented by ratio information based on the TXOP1. For example, the awake duration field of the PPDU1 header may include a bit value corresponding to 2/5. In this case, the awake duration of STA1 may be a time resource corresponding to 2/5 of TXOP1 indicated by the remaining TXOP field of the PPDU1 header. The STA1 may maintain an awake state for a time resource corresponding to the awake duration of the STA1. After the awake duration of STA1 expires, the STA1 may be switched to the doze state and remain in the doze state on the remaining TXOP.

The STA1 may receive at least one PPDU (PPDU1 310, PPDU2 320, etc.) during a time resource corresponding to the awake duration of the STA1, and may transmit an ACK frame in response to the reception of the at least one PPDU.

The AP may transmit the PPDU2 (or data unit 2) 320 to the target STA. The PPDU2 header of PPDU2 320 may include the remaining TXOP field and the awake duration field. The remaining TXOP field of the PPDU2 header may include information about TXOP2 which is the remaining TXOP of the entire TXOPs based on the transmission of the PPDU2 320. The awake duration field of the PPDU2 header may include information on the awake duration of the target STA1. The awake duration of the STA1 set by the awake duration field of the PPDU1 header and the awake duration of the STA2 set by the awake duration field of the PPDU2 header may be the same. Alternatively, the awake duration of STA1 set by the awake duration field of the PPDU2 header may be a value readjusted by the AP. For example, when the awake duration of the STA1 set by the awake duration field of the PPDU1 header is unnecessarily long or short, the AP may adjust the awake duration of the STA1 through the awake duration field of the PPDU2 header.

In addition, the PPDU1 header transmitted by the AP may include a target STA field and a remaining STA field, the target STA field may include identification information of STA1 that is a target STA, and the remaining STAs may include PPDU1 on TXOP except for the target STA. It may include identification information of STA2 and STA3 to receive the PPDU transmitted after 310.

The STA2 and the STA3 may receive the PPDU1 310 in the awake state, decode the remaining STA fields of the PPDU1 header, and switch to the doze state in the awake state. The STA2 and the STA3 may maintain a doze state for a time resource corresponding to the awake duration of the STA1, and may be switched to the awake state when the awake duration of the STA1 has expired.

After the awake duration of the STA1 expires and the STA2 and the STA3 are switched to the awake state, the AP may transmit the PPDU3 330 targeting the STA2.

The PPDU3 header of PPDU3 (or data unit 3) 330 transmitted by the AP to STA2 may include a remaining TXOP field and an awake duration field. The remaining TXOP field of the PPDU3 header may include information about TXOP3 which is the remaining TXOP of the entire TXOPs based on the transmission of the PPDU3 330. The awake duration field of the PPDU3 header may include information on the awake duration of the target STA2. The information on the awake duration of the STA2 may include information about a time resource represented by ratio information based on TXOP3. For example, the awake duration field of the PPDU3 header may include a bit value corresponding to 1/3. In this case, the awake duration of STA2 may be a time resource corresponding to 1/3 of TXOP3 indicated by the remaining TXOP fields of the PPDU3 header. The STA2 may maintain an awake state for a time resource corresponding to the awake duration of the STA2. After the awake duration of STA2 expires, the STA2 may be switched to the doze state and remain in the doze state on the remaining TXOP.

The STA2 may receive at least one PPDU (eg, PPDU3 330, etc.) during a time resource corresponding to the awake duration of the STA2, and transmit an ACK frame in response to the reception of the at least one PPDU.

The STA3 may receive the PPDU3 330 in the awake state, decode the remaining STA fields of the PPDU3 header, and switch to the doze state in the awake state. The STA3 may maintain the doze state for a time resource corresponding to the awake duration of the STA2, and may be switched to the awake state when the awake duration of the STA2 expires.

After the awake duration of the STA2 expires and the STA3 transitions to the awake state, the AP may transmit a PPDU4 (or data unit 4) 340 targeting the STA3.

The PPDU4 header of PPDU4 (or data unit 4) 340 transmitted by the AP to STA3 may include a remaining TXOP field and an awake duration field. The remaining TXOP field of the PPDU4 header may include information about TXOP4, which is the remaining TXOP of the entire TXOPs, based on the transmission of the PPDU4 340. The awake duration field of the PPDU4 header may include information on the awake duration of the target STA3. The information on the awake duration of the STA2 may include information about a time resource represented by ratio information based on TXOP4. For example, the awake duration field of the PPDU4 header may include a bit value corresponding to 1/2. In this case, the awake duration of STA3 may be a time resource corresponding to 1/2 of TXOP4 indicated by the remaining TXOP fields of the PPDU4 header. The STA3 may maintain an awake state for a time resource corresponding to the awake duration of the STA3. After the awake duration of STA3 expires, the STA3 may be switched to the doze state and remain in the doze state on the remaining TXOP.

The STA3 may receive at least one PPDU (eg, PPDU4 340, PPDU5 350, etc.) during a time resource corresponding to the awake duration of the STA3, and transmit an ACK frame in response to the at least one PPDU. have.

The remaining TXOP field of the PPDU5 header transmitted by the AP during the awake duration of STA3 may include information about TXOP5, which is the remaining TXOP of the entire TXOPs based on the transmission of the PPDU5 350. TXOP5 may be the last TXOP interval for transmission of the PPDU of the AP. Accordingly, the awake duration field of the PPDU5 header indicates 1, which may indicate that the rest of the entire interval is the awake duration of the STA3, and may also indicate that the PPDU5 350 is the last PPDU transmitted on the TXOP.

Table 1 below shows a bit value of a 2-bit awake duration field and a ratio value based on the duration of the remaining TXOP for determining the awake duration of the target STA corresponding to the bit value.

Awake Duration Field Bit Value	Remaining TXOP Base Rate Value
00	0
01	1/3
10	2/3
11	3/3

As described above, the AP (or TXOP holder) may transmit information on the remaining TXOP through the remaining TXOP field, and transmit the remaining TXOP reference ratio value through the awake duration field to indicate the awake duration of the target STA. .

The target STA may determine the awake duration by multiplying the duration of the remaining TXOP by the remaining TXOP reference ratio value corresponding to the bit value of the awake duration field. The target STA may remain awake during the awake duration. The remaining STA may remain in the doze state during the awake duration of the target STA.

For example, when the bit value of the awake duration field transmitted by the AP is '00', the STA may continuously maintain the awake state on the entire TXOP. As another example, when the bit value of the awake duration field transmitted by the AP is '01', the target STA maintains an awake state for a time resource unit by multiplying the duration of the remaining TXOP by 1/3 and the remaining STAs remain. The doze state can be maintained for a time resource unit multiplied by 1/3 of the duration of the TXOP.

If the bit value of the Awake Duration field transmitted by the AP is '10', the target STA remains awake for the time resource unit multiplied by the duration of the remaining TXOPs by 2/3, and the remaining STAs remain in the duration of the remaining TXOPs. A dose state can be maintained for a time resource unit multiplied by 2/3. In addition, when the bit value of the awake duration field transmitted by the AP is '11', the target STA maintains the awake state for the time resource unit multiplied by the duration of the remaining TXOP by 3/3, and the remaining STAs remain in the remaining TXOP. A dose state can be maintained for a time resource unit multiplied by 3/3 of the duration.

Tables 2 and 3 below show a bit value of the 3-bit awake duration field and a ratio value based on the duration of the remaining TXOP for determining the awake duration of the target STA corresponding to the bit value.

Awake Duration Field Bit Value	Remaining TXOP Base Rate Value
000	0
001	1/4
010	2/4
011	3/4
100	4/4
101	reserved
110	reserved
111	reserved

Awake Duration Field Bit Value	Remaining TXOP Base Rate Value
000	0
001	1/7
010	2/7
011	3/7
100	4/7
101	5/7
110	6/7
111	7/7

If the Awake Duration field bit is 3 bits, the TXOP duration can represent up to 1/4 units (see Table 2), 1/5 units, 1/6 units, 1/7 units (see Table 3), and the remaining bit values. Can be preserved. A plurality of units (eg, 1/4 unit, 1/6 unit, etc.) may be mixed to set the remaining TXOP reference ratio values.

As disclosed in Table 1, the target STA may determine the awake duration by multiplying the duration of the remaining TXOP by the remaining TXOP reference ratio value corresponding to the bit value of the awake duration field. The target STA may remain awake during the awake duration. The remaining STA may remain in the doze state during the awake duration of the target STA.

In Tables 1 to 3, the case where the awake duration field bit value is configured as 2 bits or 3 bits is disclosed. However, the awake duration field may be extended to x bits (x is any positive integer). In this case, the unit may be applied as 1 / M (M is any positive integer).

Also, in the embodiment of the present invention, only the case where the AP (or TXOP holder) transmits downlink data to a single STA is disclosed, but this is for convenience and the AP (or TXOP holder) transmits downlink data to a plurality of STAs. The same may be applied to the case. When downlink data is transmitted to a plurality of STAs, a frame exchange procedure between the AP and the plurality of STAs may be performed on the aforementioned duration of the TXOP for the plurality of STAs based on the group ID.

In addition, the frame exchange procedure between the AP and the plurality of STAs in the present patent may be extended and applied to MU-based transmission (MU-OFDMA, MU-MIMO).

4 is a conceptual diagram illustrating a frame exchange procedure between an AP and a plurality of STAs according to an embodiment of the present invention.

In FIG. 4, when MU-based transmission is performed, a frame exchange procedure between an AP and a plurality of STAs is disclosed.

Referring to FIG. 4, the AP may transmit a DL MU PPDU1 410 including Frame 1 for STA1 and Frame 2 for STA2 to STA1 and STA2.

The DL MU PPDU1 410 may include a target STA field, a remaining STA field, a TXOP field, a remaining TXOP field, and an awake duration field.

The target STA field may include information on target STAs STA1 and STA2 to receive the DL MU PPDU1 410 transmitted based on the MU.

The remaining STA field may include information about the remaining STAs STA3 and STA4 to receive the remaining DL MU PPDUs (eg, DL MU PPDU2 420) transmitted on the MU basis.

The TXOP field may include information on the entire TXOP duration to be transmitted based on the MU.

The remaining TXOP field may include information on the remaining TXOP after transmission of the current DL MU PPDU.

The awake duration field may represent the awake duration of the target STA based on the information on the ratio for the remaining TXOP indicated by the remaining TXOP field.

In the case of a DL MU PPDU, a PPDU header includes a resource (frequency resource (eg, channel, resource unit), a space-time stream unit (spatial stream unit) for each of a plurality of target STAs. It may further include information about).

In operation of specific STAs, the target STAs STA1 and STA2, which have received the DL MU PPDU1 410 transmitted by the AP, are transmitted through the DL MU PPDU transmitted from the AP while maintaining an awake state during the awake duration of the target STA. A frame can be received. When the awake duration of the target STA has expired, STA1 and STA2 may switch the awake state to the doze state and maintain the doze state for the remaining time after the awake duration of the target STA among the entire TXOPs.

In addition, the remaining STAs STA3 and STA4 except the target STA receiving the DL MU PPDU1 410 maintain a doze state during the awake duration of the target STA by decoding the header of the DL MU PPDU1 410. After the awake duration expires, it may be switched to the awake state and receive the DL MU PPDU2 420, which is another PPDU transmitted by the AP. Hereinafter, a method in which the AP transmits the DL MU PPDU2 420 after the DL MU PPDU1 410 to the target STAs STA3 and STA4 on the entire TXOP is disclosed.

Similarly, the PPDU header of the DL MU PPDU2 420, which is another DL MU PPDU transmitted in the TXOP, may also include a target STA field, remaining STA fields, TXOP fields, remaining TXOP fields, and awake duration fields.

In the operation of specific STAs, the target STAs STA3 and STA4, which have received the DL MU PPDU2 420 transmitted by the AP, receive the DL MU PPDU2 transmitted by the AP while maintaining the awake state during the awake duration of the target STA. Frame can be received.

In another embodiment of the present invention, a method is disclosed in which a STA maintains a doze state during a TXOP period using only a transmission opportunity (TXOP) field without an awake duration field. If the awake duration field is not specified in the HE SIG-A and only the TXOP field is specified, the dosing state may be maintained for the TXOP period only for the STA corresponding to the following condition.

1) Negotiate using an HE Capability IE (or HE Operation IE) through an association process with the AP in advance so as to maintain the dose state during TXOP, or a data transmission / reception process STA negotiated using a HE-A contril field.

2) The TXOP field value of the HE SIG-A or the duration field of the MAC header of the received packet is not 0, and the receiving MAC address (or STA AID identifier) matches the STA own MAC address (or STA AID identifier). STA does not.

However, for the STA negotiated to maintain the doze state during TXOP, the AP may have the following packet transmission rule.

The STA does not transmit a packet within the TXOP period to the STA that may possibly maintain the doze state during the TXOP period. For example, assuming TXOP power save is activated in STA1, the AP transmits a packet for STA1 as the first packet of TXOP, and if it is necessary to transmit a plurality of packets to STA1 in the same TXOP, the first packet and the second packet. For example, by continuously transmitting the packet to the STA1, the STA1 does not enter the dose state to receive the packet transmitted to the STA1. Separately, if the first packet was not a packet for STA1, the STA1 may enter the doze state for the remaining TXOP period after acknowledging the first packet. Therefore, no packet for STA1 is transmitted in the remaining TXOP intervals. It is recommended that the AP not transmit packets for STA1 for the remainder of the original TXOP even if the AP did not send a packet for STA1 as the first packet of the TXOP, even if the TXOP was truncated or stopped in the middle and terminated TXOP. It means.

If the AP transmits the RTS frame to the STA1 before packet transmission and confirms the reception of the CTS frame from the STA1, the first packet after the RTS frame / CTS frame may not be a packet for the STA1. That is, the STA1 responds with the CTS frame after receiving the RTS frame, and may expect that there is a packet transmitted to the STA1 during the corresponding TXOP. In this case, the STA1 does not enter the doze state during the TXOP.

5 is a conceptual diagram illustrating a DL MU PPDU format according to an embodiment of the present invention.

5 illustrates a DL MU PPDU format transmitted by an AP based on OFDMA according to an embodiment of the present invention. A TWT response element may be transmitted to a plurality of STAs through a data field of a DL MU PPDU format. The AP may transmit the plurality of TWT response elements to the plurality of STAs through one DL MU PPDU.

Referring to FIG. 5, the PPDU header of the DL MU PPDU includes a legacy-short training field (L-STF), a legacy-long training field (L-LTF), a legacy-signal (L-SIG), and a HE-SIG A (high). efficiency-signal A), high efficiency-signal-B (HE-SIG B), high efficiency-short training field (HE-STF), high efficiency-long training field (HE-LTF), data field (or MAC payload ) May be included. From the PHY header to the L-SIG may be divided into a legacy part and a high efficiency (HE) part after the L-SIG.

The L-STF 500 may include a short training orthogonal frequency division multiplexing symbol. The L-STF 500 may be used for frame detection, automatic gain control (AGC), diversity detection, and coarse frequency / time synchronization.

The L-LTF 510 may include a long training orthogonal frequency division multiplexing symbol. The L-LTF 510 may be used for fine frequency / time synchronization and channel prediction.

L-SIG 520 may be used to transmit control information. The L-SIG 520 may include information about a data rate and a data length.

The HE-SIG A 530 may include information for indicating an STA to receive the DL MU PPDU. For example, the HE-SIG A 530 may be an indicator indicating whether a transmitted PPDU is DL transmission or UL transmission, an identifier of a specific STA (or AP) to receive the PPDU, and information for indicating a group of the specific STA. It may include. In addition, when the DL MU PPDU is transmitted based on OFDMA or MIMO, the HE-SIG A 530 may also include resource allocation information for receiving the DL MU PPDU of the STA.

In addition, the HE-SIG A 530 may include color bit information, bandwidth information, transmission opportunity (TXOP) duration information, tail bits, CRC bits, and HE-SIG for BSS identification information. It may include modulation and coding scheme (MCS) information for the B 540, symbol number information for the HE-SIG B 540, and cyclic prefix (CP) (or guard interval (GI)) length information.

In addition, the HE-SIG A 530 may include the aforementioned target STA field, remaining STA field, TXOP field, remaining TXOP field, and awake duration field.

In addition, the HE-SIG A 530 may have a repetition mode for extending the transmission range. If a repetitive mode is used in the HE-SIG A 530, the use of the repetitive mode may be indicated prior to the HE-SIG A 530. In the repeat mode, the HE-SIG A 530 may be repeated once. The bit interleaver may be bypassed in repeated HE-SIG A symbols.

The HE-SIG B 540 may include information about a length MCS of a physical layer service data unit (PSDU) for each STA, tail bits, and the like. In addition, the HE-SIG B 540 may include information on an STA to receive a PPDU, OFDMA-based resource allocation information (or MU-MIMO-based resource allocation information). If the HE-SIG B 540 includes OFDMA-based resource allocation information (or MU-MIMO related information), the HE-SIG A 530 may not include resource allocation information.

The previous field of the HE-SIG B 540 on the DL MU PPDU may be transmitted in duplicated form in each of different transmission resources. In the case of the HE-SIG B 540, the HE-SIG B 540 transmitted in some resource units (for example, resource unit 1, resource unit 2) is an independent field containing individual information, and the remaining resources The HE-SIG B 540 transmitted in a unit (eg, resource unit 3 and resource unit 4) is the HE-SIG B 540 transmitted in another resource unit (eg, resource unit 1, resource unit 2). ) May be in a format duplicated.

In more detail, the HE-SIG B 540 may include a common block and a plurality of user blocks. The general block may include information on resource allocation, and the user block may include STA-specific information (or user specific information). A separate CRC may be defined for the general block, and a separate CRC may be defined for each of the set number of user blocks. For example, the HE-SIG B 740 includes one common block and five user blocks (user blocks 1 to 5), and user blocks in units of two user blocks. It may be assumed that a CRC for is defined. In this case, the CRC1 for the general block, the CRC2 for the user block 1 and the user block 2, the CRC3 for the user block 3 and the user block 4, and the CRC4 for the user block 5 may be included in the HE-SIG B.

Each of the plurality of user blocks included in the HE-SIG B 540 transmitted in one resource unit may include information about the plurality of users. For example, the user block 1 may include user specific information about STA1 and STA2, and the user block 2 may include user specific information about STA3 and STA4.

HE SIG B1 transmitted in resource unit 1 and HE SIG B2 transmitted in resource unit 2 may be HE SIG B including different information. For example, HE SIG B1 transmitted in resource unit 1 may include a general block and a user block for STA 1 and STA2, and HE SIG B2 transmitted in resource unit 2 may include a general block for STA 3 and STA4 and It may include a user block. As described above, the HE SIG B1 transmitted in the resource unit 3 may be generated by duplication of the HE SIG B1 transmitted in the resource unit 1, and the HE SIG B2 transmitted in the resource unit 4 may be the HE SIG transmitted in the resource unit 1. It can be generated by duplication of B2.

The HE-STF 550 may be used to improve automatic gain control estimation in a multiple input multiple output (MIMO) environment or an OFDMA environment.

Specifically, the STA1 may receive the HE-STF1 transmitted through the resource unit 1 from the AP, and decode the data field 1 (or frame 1) by performing synchronization, channel tracking / prediction, and AGC. Similarly, the STA2 may receive the HE-STF2 transmitted through the resource unit 2 from the AP, and decode the data field 2 (or frame 2) by performing synchronization, channel tracking / prediction, and AGC. The STA3 may receive the HE-STF3 transmitted through the resource unit 3 from the AP, and decode the data field 3 (or frame 3) by performing synchronization, channel tracking / prediction, and AGC. The STA4 may receive the HE-STF4 transmitted through the resource unit 4 from the AP, and decode the data field 4 (or frame 4) by performing synchronization, channel tracking / prediction, and AGC.

The HE-LTF 560 may be used to estimate a channel in a MIMO environment or an OFDMA environment.

The size of the IFFT applied to the field after the HE-STF 550 and the HE-STF 550 may be different from the size of the IFFT applied to the field before the HE-STF 550. For example, the size of the IFFT applied to the field after the HE-STF 550 and the HE-STF 550 may be four times larger than the size of the IFFT applied to the field before the HE-STF 550. The STA may receive the HE-SIG A 530 and may be instructed to receive the downlink PPDU based on the HE-SIG A 530. In this case, the STA may perform decoding based on the changed FFT size from the field after the HE-STF 550 and the HE-STF 550. On the contrary, when the STA is not instructed to receive the downlink PPDU based on the HE-SIG A 530, the STA may stop decoding and configure a network allocation vector (NAV). The cyclic prefix (CP) of the HE-STF 550 may have a larger size than the CP of another field, and during this CP period, the STA may perform decoding on the downlink PPDU by changing the FFT size.

An access point (AP) allocates each of a plurality of resource units for each of a plurality of STAs over the entire bandwidth, and each of the individual data fields (or downlinks) for each of the plurality of STAs through each of the plurality of resource units to the plurality of STAs Link frame) can be transmitted. Information about the allocation of each of the plurality of resource units for each of the plurality of STAs may be included in the HE-SIG A 550 or the HE-SIG B 560 as described above.

6 is a conceptual diagram illustrating transmission of an UL MU PPDU according to an embodiment of the present invention.

Referring to FIG. 6, a plurality of STAs may transmit a UL MU PPDU to an AP based on UL MU OFDMA. The data field 670 of the UL MU PPDU may include uplink data (or uplink frame) triggered by the trigger frame. The AP may receive a plurality of UL frames transmitted by a plurality of STAs through a plurality of UL MU PPDUs transmitted on overlapping time resources.

The L-STF 600, the L-LTF 610, the L-SIG 620, the HE-SIG A 630, and the HE-SIG B 640 may perform the roles disclosed in FIG. 5. Information included in the signal field (L-SIG 620, HE-SIG A 630, HE-SIG B 640) may be generated based on the information included in the signal field of the received DL MU PPDU. .

The STA1 may perform uplink transmission through the entire bandwidth up to the HE-SIG B 640 and uplink transmission through the allocated bandwidth after the HE-STF 650. The STA1 may transmit an uplink frame based on the UL MU PPDU through the allocated bandwidth (eg, resource unit 1). The AP may allocate uplink resources of each of a plurality of STAs based on a DL MU PPDU (eg, HE-SIG A / B), and each of the plurality of STAs is allocated an uplink resource and transmits a UL MU PPDU. Can be.

7 is a block diagram illustrating a wireless device to which an embodiment of the present invention can be applied.

Referring to FIG. 7, the wireless device may be an AP 700 or a non-AP station (or STA) 750 that may implement the above-described embodiment.

The AP 700 includes a processor 710, a memory 720, and a radio frequency unit 730.

The RF unit 730 may be connected to the processor 710 to transmit / receive a radio signal.

The processor 710 may implement the functions, processes, and / or methods proposed in the present invention. For example, the processor 710 may be implemented to perform the operation of the AP according to the above-described embodiment of the present invention. The processor may perform the operation of the AP disclosed in the embodiment of FIGS. 1 to 6.

For example, the processor 710 may be implemented to transmit the first PPDU and the second PPDU to the STA.

In this case, the first PPDU may include a remaining TXOP field and an awake duration field, and the remaining TXOP field may include information on the remaining duration of the TXOP based on a transmission time point of the first PPDU. The awake duration field may include information for determining an awake duration based on the remaining duration. In more detail, the awake duration field may include a ratio value of a time interval corresponding to the awake duration among the remaining durations, and the magnitude of the awake duration may be determined based on a product of the remaining duration and the ratio value. The remaining TXOP field and the awake duration field may be included in the signal field of the PPDU header of the first PPDU.

In addition, the first PPDU may further include a target STA field and a remaining STA field, the target STA field includes information on an STA to receive the first PPDU, and the remaining STA field is on a TXOP after the first PPDU. It may include information on a receiving STA to receive the second PPDU transmitted.

The STA 750 includes a processor 760, a memory 770, and a radio frequency unit 780.

The RF unit 780 may be connected to the processor 760 to transmit / receive a radio signal.

The processor 760 may implement the functions, processes, and / or methods proposed in the present invention. For example, the processor 760 may be implemented to perform the operation of the STA according to the above-described embodiment of the present invention. The processor may perform an operation of the STA in the embodiment of FIGS. 1 to 6.

For example, the processor 760 receives a first physical protocol data unit (PHY) from an access point (APDU) on a TXOP, and if the STA is a receiving STA of the first PPDU, the processor 760 receives the first PPDU on the TXOP. When operating in the awake state during the set awake duration based on the STA, the STA may be implemented to operate in the doze state before the expiration of the TXOP after the expiration of the awake duration.

Further, when the STA is not the receiving STA, the processor 760 operates in a doze state during the awake duration set based on the first PPDU on the TXOP, and when the STA is not the receiving STA, the doze state after expiration of the awake duration. Transitions to an awake state at may be implemented to receive a second PPDU on the TXOP from the AP.

In this case, the first PPDU may include a remaining TXOP field and an awake duration field, and the remaining TXOP field may include information on the remaining duration of the TXOP based on a transmission time of the first PPDU.

The awake duration field may include information for determining an awake duration based on the remaining duration. In more detail, the awake duration field may include a ratio value of a time interval corresponding to the awake duration among the remaining durations, and the magnitude of the awake duration may be determined based on a product of the remaining duration and the ratio value. The remaining TXOP field and the awake duration field may be included in the signal field of the PPDU header of the first PPDU.

In addition, the first PPDU may further include a target STA field and a remaining STA field, the target STA field includes information on an STA to receive the first PPDU, and the remaining STA field is on a TXOP after the first PPDU. It may include information on a receiving STA to receive the second PPDU transmitted.

Processors 710 and 760 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, data processing devices, and / or converters for interconverting baseband signals and wireless signals. The memories 720 and 770 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The RF unit 730 or 1780 may include one or more antennas for transmitting and / or receiving a radio signal.

When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in the memories 720 and 770 and executed by the processors 710 and 760. The memories 720 and 770 may be inside or outside the processors 710 and 760, and may be connected to the processors 710 and 760 by various well-known means.

Claims (10)

1. A method of operating a power save mode of a station on a transmission opportunity (TXOP) in a WLAN,

   Receiving, by the STA, a first physical protocol data unit (PHY) from an access point (AP) on the TXOP;

   If the STA is a receiving STA of the first PPDU, operating the awake state during the awake duration set based on the first PPDU on the TXOP;

   When the STA is the receiving STA, operating the STA in a doze state after expiration of the awake duration and before expiration of the TXOP;

   If the STA is not the receiving STA, operating the STA in the doze state during the awake duration established based on the first PPDU on the TXOP; And

   If the STA is not the receiving STA, transitioning from the doze state to the awake state after expiration of the awake duration and receiving a second PPDU on the TXOP from the AP.
2. The method of claim 1,

   The first PPDU includes a remaining TXOP field and an awake duration field.

   The remaining TXOP field includes information on the remaining duration of the TXOP on the basis of the transmission time of the first PPDU,

   The awake duration field includes information for determining the awake duration based on the remaining duration.
3. The method of claim 2,

   The awake duration field may include a ratio value of a time interval corresponding to the awake duration among the remaining durations.

   The magnitude of the awake duration is determined based on the product of the remaining duration and the ratio value.
4. The method of claim 2,

   The remaining TXOP field and the awake duration field are included in a signal field of a PPDU header of the first PPDU.
5. The method of claim 1,

   The first PPDU further includes a target STA field and a remaining STA field,

   The target STA field includes information on an STA to receive the first PPDU,

   The remaining STA field may include information on a receiving STA to receive the second PPDU transmitted on the TXOP after the first PPDU.
6. An STA operating in a power save mode on a transmission opportunity (TXOP) in a WLAN,

   A radio frequency (RF) unit for transmitting and receiving a radio signal; And

   A processor operatively coupled with the RF unit,

   The processor receives a first physical protocol data unit (PHY) from an access point (AP) on the TXOP,

   When the STA is a receiving STA of the first PPDU, the STA operates in an awake state for an awake duration set based on the first PPDU on the TXOP.

   When the STA is the receiving STA, operates in a doze state after expiration of the awake duration and before expiration of the TXOP;

   When the STA is not the receiving STA, operates in the doze state during the awake duration set based on the first PPDU on the TXOP,

   And when the STA is not the receiving STA, transition from the doze state to the awake state after the expiration of the awake duration, and is configured to receive a second PPDU on the TXOP from the AP.
7. The method of claim 6,

   The first PPDU includes a remaining TXOP field and an awake duration field.

   The remaining TXOP field includes information on the remaining duration of the TXOP on the basis of the transmission time of the first PPDU,

   The awake duration field includes information for determining the awake duration based on the remaining duration.
8. The method of claim 7, wherein

   The awake duration field may include a ratio value of a time interval corresponding to the awake duration among the remaining durations.

   The size of the awake duration is determined based on the product of the remaining duration and the ratio value.
9. The method of claim 7, wherein

   The remaining TXOP field and the awake duration field are included in the signal field of the PPDU header of the first PPDU.
10. The method of claim 6,

    The first PPDU further includes a target STA field and a remaining STA field,

    The target STA field includes information on an STA to receive the first PPDU,

    The remaining STA field includes information on a receiving STA that will receive the second PPDU transmitted on the TXOP after the first PPDU.

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