WO2018008890A1 - Procédé et appareil de fonctionnement en mode d'économie d'énergie txop dans un système de réseau local sans fil - Google Patents

Procédé et appareil de fonctionnement en mode d'économie d'énergie txop dans un système de réseau local sans fil Download PDF

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WO2018008890A1
WO2018008890A1 PCT/KR2017/006836 KR2017006836W WO2018008890A1 WO 2018008890 A1 WO2018008890 A1 WO 2018008890A1 KR 2017006836 W KR2017006836 W KR 2017006836W WO 2018008890 A1 WO2018008890 A1 WO 2018008890A1
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Prior art keywords
station
txop
frame
sta
power save
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PCT/KR2017/006836
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English (en)
Korean (ko)
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박현희
류기선
김서욱
김정기
조한규
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엘지전자 주식회사
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the present disclosure relates to a technique relating to a power save mode in a wireless LAN system, and more particularly, to a method and apparatus for operating in a TXOP power save mode in a wireless station of a wireless LAN system.
  • 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. aims to improve performance in real indoor and outdoor environments, such as in environments where interference sources exist, dense heterogeneous network environments, and high user loads.
  • IEEE Institute of Electronics and Electronics Engineers
  • PHY physical physical access
  • MAC medium access control
  • next-generation WLAN 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.
  • 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.
  • 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.
  • STA are discussing about improving system performance in a dense environment with many STAs.
  • next-generation WLAN 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.
  • D2D direct-to-direct
  • the present specification proposes a technique for operating in the TXOP power save mode.
  • the present specification proposes an example of a method of operating in a TXOP power save mode in a wireless LAN system and an apparatus on which the method is performed.
  • the first station may be a non-AP station and the second station may correspond to an AP station communicating with the non-AP station.
  • the first station may be an intended station or an unintended station.
  • the intended station may correspond to a station that has received a frame containing its AID from the AP station.
  • the unintended station may correspond to a station that receives a frame that does not contain its AID from the AP station.
  • the first station receives a Multi User-Request To Send (MU-RTS) frame during TXOP from the second station.
  • MU-RTS Multi User-Request To Send
  • the MU-RTS frame is used to inform the MU STA that the medium is to be accessed, thereby obtaining the MU TXOP.
  • the first station determines a transition to a doze state for the remainder of the TXOP. That is, even if the TXOP period is not finished, if there is no frame to transmit and receive between the AP and the STA because there is no AID of the STA, the STA transitions to the doze state for the remaining TXOP period. As a result, the power of the STA can be saved more.
  • AID Association Identifier
  • the first station may determine whether to transmit a clear to send (CTS) frame.
  • CTS clear to send
  • the first station may set a network allocation vector (NAV) from a start point of the TXOP.
  • NAV network allocation vector
  • the first station may transition to a doze state for the remainder of the TXOP.
  • the first station If the first station does not transmit the CTS frame, the first station transitions to a doze state for the remainder of the TXOP when the NAV is not reset, and an awake state when the NAV is reset. ) Can be maintained.
  • the first station may determine whether the CTS can be detected until the CTS timeout is reached.
  • the first station may transmit TXOP power save request information through an OMI control field.
  • the TXOP power save request information may be indicated by 1 bit reserved in the OMI control field.
  • the OMI control field may correspond to the OMI A-Control field.
  • the first station may request the TXOP PS through the OMI control field and receive an ACK for the TXOP PS request from the second station.
  • the first station may receive a TXOP power save subfield through a trigger frame from the second station.
  • the TXOP power save subfield may be indicated by 1 bit reserved in the trigger frame.
  • the first station may transition to a doze state for the remaining period of the TXOP.
  • the TXOP power save subfield indicates 0, even if there is no AID of the first station in the MU-RTS frame, the first station does not transition to a doze state for the remaining period of the TXOP.
  • An embodiment using the TXOP power save subfield may be a technique for explicitly signaling that a specific subfield is used for the TXOP PS.
  • the first station may determine a transition to a doze state for the remaining period of the TXOP without performing capability negotiation with the second station.
  • the first station may be an unintended station, so capability negotiation with the second station may be needed via the HE capabilities element.
  • the STA when communication between the STA and the AP is terminated during the TXOP, the STA transitions to the doze state during the remaining TXOP period and may operate in the power save mode. As a result, power of the STA may be saved, and a substantial operating time of the STA operating on a battery basis may be increased.
  • WLAN wireless local area network
  • FIG. 2 is a diagram illustrating an example of a PPDU used in the IEEE standard.
  • FIG. 3 is a diagram illustrating an example of a HE PPDU.
  • FIG. 4 is a diagram illustrating an arrangement of resource units (RUs) used on a 20 MHz band.
  • FIG. 5 is a diagram illustrating an arrangement of resource units (RUs) used on a 40 MHz band.
  • FIG. 6 is a diagram illustrating an arrangement of resource units (RUs) used on an 80 MHz band.
  • FIG. 7 is a diagram illustrating another example of the HE-PPDU.
  • FIG. 8 is a block diagram showing an example of the HE-SIG-B according to the present embodiment.
  • FIG. 9 shows an example of a trigger frame.
  • FIG 11 illustrates an example of subfields included in an individual user information field.
  • FIG. 12 shows an example of an HE Capabilities information field for HE TXOP PS.
  • FIG. 13 shows an example of the operation of the HE TXOP PS for the intended HE STA.
  • 16 is a flowchart illustrating a procedure of operating in a TXOP power save mode according to the present embodiment.
  • 17 is a block diagram illustrating a wireless device to which the present embodiment can be applied.
  • WLAN wireless local area network
  • BSS infrastructure basic service set
  • IEEE Institute of Electrical and Electronic Engineers
  • the WLAN system may include one or more infrastructure BSSs 100 and 105 (hereinafter, BSS).
  • 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 STAs 103-1 and 105-2 that can be coupled 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.
  • STA STA
  • APs 125 and 130 for providing a distribution service
  • DS distribution system
  • 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.
  • 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).
  • 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).
  • FIG. 1 is a conceptual diagram illustrating an IBSS.
  • 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).
  • MAC medium access control
  • IEEE Institute of Electrical and Electronics Engineers
  • 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.
  • WTRU wireless transmit / receive unit
  • UE user equipment
  • MS mobile station
  • UE mobile subscriber unit
  • It may also be called various names such as a mobile subscriber unit or simply a user.
  • FIG. 2 is a diagram illustrating an example of a PPDU used in the IEEE standard.
  • PPDUs PHY protocol data units
  • LTF and STF fields included training signals
  • SIG-A and SIG-B included control information for the receiving station
  • data fields included user data corresponding to the PSDU.
  • This embodiment proposes an improved technique for the signal (or control information field) used for the data field of the PPDU.
  • the signal proposed in this embodiment may be applied on a high efficiency PPDU (HE PPDU) according to the IEEE 802.11ax standard. That is, the signals to be improved in the present embodiment may be HE-SIG-A and / or HE-SIG-B included in the HE PPDU. Each of HE-SIG-A and HE-SIG-B may also be represented as SIG-A or SIG-B.
  • the improved signal proposed by this embodiment is not necessarily limited to the HE-SIG-A and / or HE-SIG-B standard, and controls / control of various names including control information in a wireless communication system for transmitting user data. Applicable to data fields.
  • FIG. 3 is a diagram illustrating an example of a HE PPDU.
  • the control information field proposed in this embodiment may be HE-SIG-B included in the HE PPDU as shown in FIG. 3.
  • the HE PPDU according to FIG. 3 is an example of a PPDU for multiple users.
  • the HE-SIG-B may be included only for the multi-user, and the HE-SIG-B may be omitted in the PPDU for the single user.
  • a HE-PPDU for a multiple user includes a legacy-short training field (L-STF), a legacy-long training field (L-LTF), a legacy-signal (L-SIG), High efficiency-signal A (HE-SIG-A), high efficiency-signal-B (HE-SIG-B), high efficiency-short training field (HE-STF), high efficiency-long training field (HE-LTF) It may include a data field (or MAC payload) and a PE (Packet Extension) field. Each field may be transmitted during the time period shown (ie, 4 or 8 ms, etc.).
  • FIG. 4 is a diagram illustrating an arrangement of resource units (RUs) used on a 20 MHz band.
  • resource units corresponding to different numbers of tones (ie, subcarriers) may be used to configure some fields of the HE-PPDU.
  • resources may be allocated in units of RUs shown for HE-STF, HE-LTF, and data fields.
  • 26-units ie, units corresponding to 26 tones
  • Six tones may be used as the guard band in the leftmost band of the 20 MHz band, and five tones may be used as the guard band in the rightmost band of the 20 MHz band.
  • seven DC tones are inserted into the center band, that is, the DC band, and 26-units corresponding to each of the 13 tones may exist to the left and right of the DC band.
  • other bands may be allocated 26-unit, 52-unit, 106-unit. Each unit can be assigned for a receiving station, i. E. A user.
  • the RU arrangement of FIG. 4 is utilized not only for the situation for a plurality of users (MU), but also for the situation for a single user (SU), in which case one 242-unit is shown as shown at the bottom of FIG. It is possible to use and in this case three DC tones can be inserted.
  • FIG. 5 is a diagram illustrating an arrangement of resource units (RUs) used on a 40 MHz band.
  • the example of FIG. 5 may also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, and the like.
  • five DC tones can be inserted at the center frequency, 12 tones are used as the guard band in the leftmost band of the 40 MHz band, and 11 tones are in the rightmost band of the 40 MHz band. This guard band can be used.
  • the 484-RU may be used when used for a single user. Meanwhile, the specific number of RUs may be changed as in the example of FIG. 4.
  • FIG. 6 is a diagram illustrating an arrangement of resource units (RUs) used on an 80 MHz band.
  • the example of FIG. 6 may also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, 996-RU, and the like. have.
  • seven or five DC tones can be inserted at the center frequency, and 12 tones are used as the guard band in the leftmost band of the 80 MHz band, and in the rightmost band of the 80 MHz band. Eleven tones can be used as guard bands.
  • 996-RU may be used when used for a single user. Meanwhile, the specific number of RUs may be changed as in the example of FIGS. 4 and 5.
  • FIG. 7 is a diagram illustrating another example of the HE-PPDU.
  • FIG. 7 is another example illustrating the HE-PPDU block of FIG. 3 in terms of frequency.
  • the illustrated L-STF 700 may include a short training orthogonal frequency division multiplexing symbol.
  • the L-STF 700 may be used for frame detection, automatic gain control (AGC), diversity detection, and coarse frequency / time synchronization.
  • AGC automatic gain control
  • the L-LTF 710 may include a long training orthogonal frequency division multiplexing symbol.
  • the L-LTF 710 may be used for fine frequency / time synchronization and channel prediction.
  • L-SIG 720 may be used to transmit control information.
  • the L-SIG 720 may include information about a data rate and a data length.
  • the L-SIG 720 may be repeatedly transmitted. That is, the L-SIG 720 may be configured in a repeating format (for example, may be referred to as an R-LSIG).
  • the HE-SIG-A 730 may include control information common to the receiving station.
  • the HE-SIG-A 730 may include 1) a DL / UL indicator, 2) a BSS color field which is an identifier of a BSS, 3) a field indicating a remaining time of a current TXOP interval, 4) 20, Bandwidth field indicating whether 40, 80, 160, 80 + 80 MHz, 5) field indicating the MCS scheme applied to HE-SIG-B, 6) HE-SIB-B has dual subcarrier modulation for MCS ( field indicating whether it is modulated by dual subcarrier modulation), 7) field indicating the number of symbols used for HE-SIG-B, and 8) indicating whether HE-SIG-B is generated over the entire band.
  • PE Packet Extension
  • CRC field of the HE-SIG-A and the like.
  • Specific fields of the HE-SIG-A may be added or omitted. In addition, some fields may be added or omitted in other environments where the HE-SIG-A is not a multi-user (MU) environment.
  • MU multi-user
  • the HE-SIG-B 740 may be included only when it is a PPDU for a multi-user (MU) as described above.
  • the HE-SIG-A 750 or the HE-SIG-B 760 may include resource allocation information (or virtual resource allocation information) for at least one receiving STA.
  • FIG. 8 is a block diagram showing an example of the HE-SIG-B according to the present embodiment.
  • the HE-SIG-B field includes a common field at the beginning, and the common field can be encoded separately from the following field. That is, as shown in FIG. 8, the HE-SIG-B field may include a common field including common control information and a user-specific field including user-specific control information.
  • the common field may include a corresponding CRC field and may be coded into one BCC block. Subsequent user-specific fields may be coded into one BCC block, including a "user-feature field" for two users and a corresponding CRC field, as shown.
  • the previous field of HE-SIG-B 740 on the MU PPDU may be transmitted in duplicated form.
  • the HE-SIG-B 740 transmitted in a part of the frequency band is the frequency band of the corresponding frequency band (ie, the fourth frequency band).
  • Control information for a data field and a data field of another frequency band (eg, the second frequency band) except for the corresponding frequency band may be included.
  • the HE-SIG-B 740 of a specific frequency band (eg, the second frequency band) duplicates the HE-SIG-B 740 of another frequency band (eg, the fourth frequency band). It can be one format.
  • the HE-SIG-B 740 may be transmitted in encoded form on all transmission resources.
  • the field after the HE-SIG-B 740 may include individual information for each receiving STA that receives the PPDU.
  • the HE-STF 750 may be used to improve automatic gain control estimation in a multiple input multiple output (MIMO) environment or an OFDMA environment.
  • MIMO multiple input multiple output
  • OFDMA orthogonal frequency division multiple access
  • the HE-LTF 760 may be used to estimate a channel in a MIMO environment or an OFDMA environment.
  • the size of the FFT / IFFT applied to the field after the HE-STF 750 and the HE-STF 750 may be different from the size of the FFT / IFFT applied to the field before the HE-STF 750.
  • the size of the FFT / IFFT applied to the fields after the HE-STF 750 and the HE-STF 750 may be four times larger than the size of the IFFT applied to the field before the HE-STF 750.
  • a field of s is called a first field
  • at least one of the data field 770, the HE-STF 750, and the HE-LTF 760 may be referred to as a second field.
  • the first field may include a field related to a legacy system
  • the second field may include a field related to a HE system.
  • 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
  • 2048 FFT for a bandwidth of 160 MHz continuous or discontinuous 160 MHz.
  • / IFFT can be applied.
  • spacing may be applied to a subcarrier having a size of 312.5 kHz, which is a conventional subcarrier spacing, and space may be applied to a subcarrier having a size of 78.125 kHz, as a second field of the HE PPDU.
  • 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 ⁇ s, 0.8 ⁇ s, 1.6 ⁇ s, 2.4 ⁇ s, 3.2 ⁇ s.
  • the frequency band used by the first field and the frequency band used by the second field are represented in FIG. 7, they may not exactly coincide with each other.
  • the main band of the first field L-STF, L-LTF, L-SIG, HE-SIG-A, HE-SIG-B
  • HE-STF the main band of the first field
  • HE-LTF, Data the second field
  • the interface may be inconsistent. 4 to 6, since a plurality of null subcarriers, DC tones, guard tones, etc. are inserted in the process of arranging the RU, it may be difficult to accurately match the interface.
  • the user may receive the HE-SIG-A 730 and may be instructed to receive the downlink PPDU based on the HE-SIG-A 730.
  • the STA may perform decoding based on the changed FFT size from the field after the HE-STF 750 and the HE-STF 750.
  • the STA may stop decoding and configure a network allocation vector (NAV).
  • NAV network allocation vector
  • the cyclic prefix (CP) of the HE-STF 750 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.
  • data (or frame) transmitted from the AP to the STA is called downlink data (or downlink frame), and data (or frame) transmitted from the STA to the AP is called uplink data (or uplink frame).
  • downlink data or downlink frame
  • uplink data or uplink frame
  • 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 referred to as uplink transmission.
  • 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)).
  • PSDU physical layer service data unit
  • MPDU MAC protocol data unit
  • the PPDU header may include a PHY header and a PHY preamble
  • 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
  • the PHY preamble may be expressed as a PLCP preamble in another term.
  • each of the PPDUs, frames, and data transmitted through the uplink transmission may be expressed by the term uplink PPDU, uplink frame, and uplink data.
  • the entire bandwidth may be used for downlink transmission to one STA and uplink transmission to one STA based on single (or single) -orthogonal frequency division multiplexing (SUDM) transmission.
  • the AP may perform downlink (DL) multi-user (MU) transmission based on multiple input multiple output (MU MIMO), and such transmission is referred to as DL MU MIMO transmission. It can be expressed as.
  • an orthogonal frequency division multiple access (OFDMA) based transmission method is preferably supported for uplink transmission and / or downlink transmission. That is, uplink / downlink communication may be performed by allocating data units (eg, RUs) corresponding to different frequency resources to the user.
  • the AP may perform DL MU transmission based on OFDMA, and such transmission may be expressed by the term DL MU OFDMA transmission.
  • the AP may transmit downlink data (or downlink frame, downlink PPDU) to each of the plurality of STAs through each of 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).
  • DL MU OFDMA transmission may be used with DL MU MIMO transmission. For example, DL MU MIMO transmission based on a plurality of space-time streams (or spatial streams) on a specific subband (or subchannel) allocated for DL MU OFDMA transmission is performed. Can be.
  • UL MU transmission uplink multi-user transmission
  • a plurality of STAs transmit data to the AP on the same time resource.
  • Uplink transmission on the overlapped time resource by each of the plurality of STAs may be performed in a frequency domain or a spatial 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 frequency resources allocated thereto.
  • Such a transmission method through different frequency resources may be represented by the term UL MU OFDMA transmission method.
  • each of a plurality of STAs When uplink transmission by each of a plurality of STAs is performed on 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.
  • 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.
  • 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.
  • 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.
  • 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't.
  • OBSS overlapped BSS
  • 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.
  • a WLAN system supporting the OFDMA technology supporting the OFDMA technology. That is, the above-described OFDMA technique is applicable to at least one of downlink and uplink.
  • the above-described MU-MIMO technique may be additionally applied to at least one of downlink and uplink.
  • 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.
  • the AP when uplink transmission by each of a plurality of STAs (eg, non-AP STAs) is performed in the frequency domain, the AP has different frequency resources for each of the plurality of STAs based on OFDMA. It may be allocated as a link transmission resource. In addition, as described above, different frequency resources may be different subbands (or subchannels) or different resource units (RUs).
  • OFDMA orthogonal frequency division multiple access
  • Different frequency resources for each of the plurality of STAs are indicated through a trigger frame.
  • the trigger frame of FIG. 9 allocates resources for uplink multiple-user transmission and may be transmitted from the AP.
  • the trigger frame may consist of a MAC frame and may be included in a PPDU. For example, it may be transmitted through the PPDU shown in FIG. 3, through the legacy PPDU shown in FIG. 2, or through a PPDU specifically designed for the trigger frame. If transmitted through the PPDU of FIG. 3, the trigger frame may be included in the illustrated data field.
  • Each field shown in FIG. 9 may be partially omitted, and another field may be added. In addition, each length can be varied as shown.
  • the frame control field 910 of FIG. 9 includes information about the version of the MAC protocol and other additional control information, and the duration field 920 includes time information for setting the NAV described below.
  • Information about an identifier (eg, AID) of the terminal may be included.
  • the RA field 930 includes address information of the receiving STA of the corresponding trigger frame and may be omitted as necessary.
  • the TA field 940 includes address information of an STA (for example, an AP) that transmits a corresponding trigger frame, and the common information field 950 is common to be applied to a receiving STA that receives the corresponding trigger frame. Contains control information
  • FIG. 10 shows an example of a common information field. Some of the subfields of FIG. 10 may be omitted, and other subfields may be added. In addition, the length of each illustrated subfield may be modified.
  • the illustrated length field 1010 has the same value as the length field of the L-SIG field of the uplink PPDU transmitted corresponding to the trigger frame, and the length field of the L-SIG field of the uplink PPDU indicates the length of the uplink PPDU.
  • the length field 1010 of the trigger frame may be used to indicate the length of the corresponding uplink PPDU.
  • the cascade indicator field 1020 indicates whether a cascade operation is performed.
  • the cascade operation means that downlink MU transmission and uplink MU transmission are performed together in the same TXOP. That is, after downlink MU transmission is performed, it means that uplink MU transmission is performed after a predetermined time (eg, SIFS).
  • a predetermined time eg, SIFS.
  • only one transmitting device (eg, AP) for downlink communication may exist, and a plurality of transmitting devices (eg, non-AP) for uplink communication may exist.
  • the CS request field 1030 indicates whether the state of the radio medium, the NAV, or the like should be considered in a situation in which the receiving apparatus receiving the trigger frame transmits the corresponding uplink PPDU.
  • the HE-SIG-A reservation field 1040 may include information for controlling the content of the SIG-A field (ie, the HE-SIG-A field) of the uplink PPDU transmitted in response to the trigger frame.
  • the GI and LTF type field 1050 may include information about the length of the LTF and the GI length of the uplink PPDU transmitted in response to the corresponding trigger frame.
  • the trigger type field 1060 may indicate the purpose for which the corresponding trigger frame is used, for example, normal triggering, triggering for beamforming, a request for Block ACK / NACK, and the like.
  • per user information fields 960 # 1 to 960 # N corresponding to the number of receiving STAs receiving the trigger frame of FIG. 9.
  • the individual user information field may be called a “RU assignment field”.
  • the trigger frame of FIG. 9 may include a padding field 970 and a frame check sequence field 980.
  • Each of the per user information fields 960 # 1 to 960 # N shown in FIG. 9 preferably includes a plurality of subfields.
  • FIG. 11 illustrates an example of subfields included in an individual user information field. Some of the subfields of FIG. 11 may be omitted, and other subfields may be added. In addition, the length of each illustrated subfield may be modified.
  • An AID12 field or a user identifier field 1110 of FIG. 11 indicates an identifier of an STA (ie, a receiving STA) to which per user information corresponds.
  • An example of the identifier is all or part of an AID. Can be
  • the RU Allocation field 1120 may be included. That is, when the receiving STA identified by the user identifier field 1110 transmits an uplink PPDU in response to the trigger frame of FIG. 9, the corresponding uplink PPDU through the RU indicated by the RU Allocation field 1120. Send.
  • the RU indicated by the RU Allocation field 1120 preferably indicates the RUs shown in FIGS. 4, 5, and 6.
  • the subfield of FIG. 11 may include a coding type field 1130.
  • the coding type field 1130 may indicate a coding type of an uplink PPDU transmitted in response to the trigger frame of FIG. 9. For example, when BCC coding is applied to the uplink PPDU, the coding type field 1130 is set to '1', and when LDPC coding is applied, the coding type field 1130 is set to '0'. Can be.
  • the subfield of FIG. 11 may include an MCS field 1140.
  • the MCS field 1140 may indicate an MCS scheme applied to an uplink PPDU transmitted in response to the trigger frame of FIG. 9.
  • a power save mechanism is provided to increase the lifespan of a STA of a WLAN.
  • the STA can operate based on two modes (or states): active mode (awake state) and sleep mode (doze state). have.
  • the STA may operate in a power save mode based on the awake state or the doze state.
  • the STA in the active mode may perform normal operations such as transmission or reception of a frame and channel scanning.
  • the STA in the sleep mode does not perform transmission or reception of a frame and does not perform channel scanning to reduce power consumption.
  • the STA operating in the power save mode may remain in the doze state to reduce power consumption and, if necessary, switch to an awake state (or transition) to communicate with the AP.
  • the power consumption of the STA may decrease and the lifetime of the STA may also increase.
  • transmission or reception of the frame of the STA is impossible. If there is a pending uplink frame in the STA, the STA may switch from the doze state to the active state and transmit the uplink frame to the AP. On the contrary, when there is a pending frame to be transmitted to the STA in the doze state, the AP cannot transmit the frame pending to the STA until the STA switches to the awake mode.
  • the STA may occasionally switch from the doze state to the awake state and receive information on whether there is a frame pending for the STA from the AP.
  • the AP may transmit information on the existence of downlink data pending for the STA to the STA in consideration of the transition time of the STA to the awake state.
  • the STA may periodically switch from the doze state to the awake state to receive a beacon frame in order to receive information on whether there is a frame pending for the STA.
  • the beacon frame is a frame used for passive scanning of the STA and may include information on the capability of the AP.
  • the AP may transmit a beacon frame to the STA periodically (eg, 100 msec).
  • an STA may operate based on a TXOP power save mode, which is a power save mode based on a transmission opportunity (TXOP) as well as a TIM (Traffic Indication Map) based power save mode included in a beacon frame.
  • TXOP transmission opportunity
  • TIM Traffic Indication Map
  • An STA operating in a TXOP power save mode transitions to a doze state during a TXOP duration (or a TXOP duration set by a frame of another STA) when media occupancy for transmission of a frame of another STA occurs. Can be.
  • the STA operating in the conventional TXOP power save mode receives a downlink frame from the combined AP and partially combines the identifier with the group ID included in the PHY header (or PLCP header) of the downlink PPDU that transmitted the downlink frame. It may be determined whether to switch to a doze state or maintain an awake state based on the (Partial association identifier (AID)).
  • AID Partial association identifier
  • the STA may be switched to the doze state when the group identifier included in the PHY header of the received downlink PPDU does not match.
  • the STA matches the group identifier included in the PHY header of the downlink PPDU and the group identifier of the STA, but the PAID included in the PHY header of the downlink PPDU does not match, the STA goes into a doze state. Can be switched.
  • VHT TXOP power save is defined.
  • the STA may enter the doze state for the TXOP duration when receiving an unintended frame. However, if the STA enters the doze state for the TXOP duration after receiving the Overlapped BSS (OBSS) frame, it may miss the Intra BSS frame intended for the OBSS frame. In addition, since the BSS color and TXOP duration fields are not defined in the VHT SIG field, the STA cannot distinguish the OBSS frame from the intra BSS frame and cannot enter the TXOP PS after receiving only the VHT preamble.
  • OBSS Overlapped BSS
  • the BSS color field is defined in the PPDU header of the PPDU.
  • the BSS color field includes information for indicating the BSS that transmitted the PPDU (or frame). If the BSS color field indicates another BSS, the STA may know that the received PPDU was transmitted from an AP of another BSS.
  • 802.11ax there are several mechanisms for power saving, such as intra PPDU power save and target wave time (TWT).
  • TWT target wave time
  • the HE STA in the intra PPDU power save mode may enter the doze state until the received PPDU ends. In this case, the HE STA must consider using the medium during the doze state and transition to the awake state at the end of the PPDU. Finally, the HE STA must repeat the transition to sleep and awake states in all PPDUs for intra PPDU power saves.
  • the HE STA may set individual TWT agreements for TWT operation and may utilize broadcast TWT operation for power saving.
  • TWT enables the STA to manage BSS activities by scheduling the STAs to operate at different times to minimize the competition between the STAs and to reduce the time required for the STAs in the power save mode to be awake. Since individual TWT operations are based on STA criteria, STAs without a TWT agreement cannot power save using TWT operations.
  • the AP In the case of the TWT operation, the AP must have a restriction for scheduling the TWT STA according to the TWT SP (Service Period). In a high density environment, the AP may need to schedule the STA more dynamically.
  • TWT SP Service Period
  • a HE TXOP power save (PS) is defined. This allows the STA requesting the HE TXOP PS to sleep for the remaining TXOP when the packet is not transmitted to itself when receiving the packet from the AP. Eventually, the STA requesting the HE TXOP PS can be informed whether to receive a further schedule.
  • the HE TXOP PS mechanism is useful for a non-TWT STA to power save in an awake state.
  • the STA In order for the STA to enter the doze state for the remainder of the TXOP, the STA must know the information that it will not be scheduled by the AP for the TXOP.
  • the MU-RTS trigger frame can be used to define this information without defining new control signaling.
  • the HE TXOP PS mechanism defined in the present specification is as follows. If there is no matching AID in the intra BSS MU-RTS frame, the STA may enter a doze state for the remaining TXOP duration for the HE TXOP PS.
  • HE TXOP PS can be defined as an optional feature by adding capability bits to the HE Capabilities element.
  • FIG. 12 shows an example of an HE Capabilities information field for HE TXOP PS.
  • HE TXOP PS Support bit in the HE Capabilities element. Capability negotiation is performed through HE TXOP PS Support in the HE Capabilities information field of FIG. 12.
  • the HE TXOP PS may be defined as mandatory, and in the case of the STA, the HE TXOP PS may be defined as optional. Accordingly, the AP and the STA that have completed the capability negotiation may perform an operation process for the HE TXOP PS.
  • a HE TXOP PS Support field may be defined using 1 bit in the HE Capabilities information field.
  • the HE TXOP PS subfield of the HE Capabilities information field may be defined as shown in the following table.
  • Subfield Definition Encoding HE TXOP PS Indicates whether the non-AP HE STA has enabled TXOP power save or whether the AP supports TXOP power save mode Set to 0 if the non-AP HE STA does not enable TXOP power save mode.Set to 1 if the non-AP HE STA enables TXOP power save mode.Set to 0 if the AP does not support TXOP power save mode.Set to 1 if the AP supports TXOP power save mode.
  • a non-AP HE STA whose HE TXOP PS Support field of the HE Capabilities element is 1 may enter a doze state until the end of TXOP when the following condition is satisfied.
  • the non-AP HE STA receives an intra BSS MU-RTS trigger frame that does not have a user information field addressed to the STA. That is, all AID12 subfields 1110 of the user information field of the MU-RTS trigger frame are not the same as the AID of the STA. And, if the STA instructed to receive the control frame having a TA set to the transmitted BSSID (Rx Control Frame To MultiBSS set to 1 in HE Capabilities element), the MU-RTS trigger frame is the AP associated with the STA or transmitted Sent by AP corresponding to BSSID
  • the PHY-RXSTART.indication primitive is received from the PHY during the NAVTimeout period from when the MAC receives the PHY-RXEND.indication primitive corresponding to the detection of the MU-RTS trigger frame.
  • the NAVTimeout period is equal to (2 x aSIFSTime) + (CTS_Time) + aRxPHYStartDelay + (2 x aSlotTime).
  • Option 1 If the HE STA that is not capable of the TWT operation can perform the HE TXOP PS outside the TWT SP, coexistence is not allowed in the same period.
  • TWT SP allows coexistence of HE TXOP PS.
  • the cascade indicator field 1020 of the trigger frame in the TWT SP is not affected by the HE TXOP PS. That is, even if the cascade indicator field 1020 indicates 0 and the transmission of the trigger frame is terminated, the HE TXOP PS is not affected.
  • the HE TXOP PS is a technique in which an STA that receives an unintentional frame during TXOP remains dormant until the end of the TXOP.
  • the conditions for performing the HE TXOP PS are as follows.
  • Condition 1 There is no STAID that matches the intra BSS MU-RTS frame. If the unintentional HE STA receives the MU-RTS frame without its AID, it may be in a doze state for the remaining TXOP interval for the HE TXOP PS.
  • EOSP End Of Service Period
  • More Data is set to 0.
  • the intended STA sends an acknowledgment for the frame for the HE TXOP PS and then enters the doze state for the remaining TXOP duration. Can be.
  • the negotiation method for the HE TXOP PS is as follows.
  • Implicit method The AP should announce whether or not the HE STA supports power saving during TXOP in the beacon / probe response frame. If the HE STA has an unintended frame that it receives during TXOP, the HE STA may enter a doze state and may sleep until the end of the TXOP.
  • the AP should not transmit the frame to the HE STA. This is because the NAV at the start of TXOP could enter the doze state until it expires. Due to the problem of TXOP truncation, the HE STA may inform the HE TXOP PS with a signal that can be used by the OMI A-Control (Operating Mode Indication Aggregated-Control) field (1 bit signaling).
  • OMI A-Control Operating Mode Indication Aggregated-Control
  • the OMI may indicate a transmit operating mode (TOM) or a receive operating mode (ROM).
  • the reception operation mode is related to an operation in which an STA (eg, a non-AP STA) reporting an operation mode receives a signal from a counterpart STA (eg, an AP).
  • the transmission operation mode is related to an operation of transmitting a signal to the STA (eg, a non-AP STA) that the other STA (eg, the AP) reported the operation mode.
  • the operation mode may correspond to the number of spatial streams and / or the size of the channel bandwidth.
  • the AP must inform whether the HE STA supports power saving during the TXOP in the beacon / probe response frame.
  • An HE STA (eg, an intended or unintended STA) may negotiate to support the HE TXOP PS.
  • the bits for HE TXOP PS Capability in the HE capabilities information of the HE Capabilities element indicate the following.
  • the AP When transmitted in a beacon / probe response, the AP indicates whether the HE STA of the BSS can enter the doze state (ie, the HE TXOP PS mode).
  • the AP may set the HE TXOP PS subfield to 1 in the HE Capabilities element transmitted to request participation in the HE TXOP PS by all HE STAs that are associated and declared to support power saving.
  • the HE TXOP PS subfield is set to 1, the HE TXOP PS indicates a HE STA. If the HE TXOP PS subfield is set to 0, the HE TXOP PS subfield is set to 0, indicating a HE STA rather than the HE TXOP PS.
  • the AP should inform whether the HE STA supports power saving during TXOP in the beacon / probe response frame.
  • the AP must know whether the HE STA is capable of power saving during TXOP.
  • the HE STA must inform the AP of switching between TXOP PS modes.
  • One bit of the OMI A-Control field may be used.
  • the AP needs to indicate whether the HE STA is allowed to enter the doze state during that TXOP.
  • the intended STA and the unintended STA must be defined separately.
  • the HE STA in the HE TXOP PS mode must know the TXOP duration and AID intended by the AP. For example, this is done by checking the duration / ID field of the MU-RTS frame. Requires MU-RTS / CTS exchange at TXOP start.
  • the AP must buffer the data frame of the HE STA entering the doze state until the TXOP ends.
  • FIG. 13 shows an example of the operation of the HE TXOP PS for the intended HE STA.
  • the EOSP subfield and the More Data field may be used implicitly in the DL data for the HE TXOP PS.
  • the intended STA sends an acknowledgment for the frame for the HE TXOP PS and then enters the doze state for the remaining TXOP duration.
  • the EOSP subfield is set to 1 to indicate the end of the current SP in the last frame, and the More Data field is set to 0 to indicate that there is no more buffered data.
  • reception of the trigger frame with the cascade indicator field 1020 may be implicitly considered in the UL data for the HE TXOP PS.
  • the intended STA may implicitly enter the doze state for the remaining TXOP duration after transmitting UL data for the HE TXOP PS.
  • the cascade indicator field 1020 is set to 0 to indicate the last trigger frame.
  • an existing subfield may support HE TXOP PS as follows. That is, the present embodiment may use the existing EOSP subfield and the More Data field to perform HE TXOP PS during the remaining TXOP.
  • the AP sets the EOSP subfield to 1 to indicate the end of the current Service Period in the last frame and the More Data field to 0 to implicitly indicate that no additional buffered data is available for HE TXOP PS. do.
  • the EOSP subfield When the EOSP subfield receives the frame 1310 transmitted by the AP with 1 or the More Data field 0, the intended STA sends an acknowledgment 1320 for the frame for the HE TXOP PS and then the rest. You can enter the Doze state for the duration of the TXOP.
  • the AP sends a Doze state for the remaining TXOP duration after sending an acknowledgment 1340 for UL Data. Can enter The above embodiment may be applied even when the capability negotiation is performed between the AP and the STA or the capability negotiation is not performed.
  • APSD HC sets the EOSP subfield to 1 in transmission and retransmission of the last frame of the SP to terminate the scheduled / unscheduled SP, otherwise set to 0.
  • the STA requesting the TWT may classify one of the following events as an initial TWT SP end event.
  • the ACK is transmitted in response to the request frame sent by the TWT response STA in which the EOSP subfield is 1 or the More Data field is 0.
  • the intended STA may use the EOSP and More Data fields to sleep during the remaining TXOP.
  • the AP Even if the HE STA negotiates the capability of the HE TXOP PS with the AP, the AP needs to know whether the HE STA is capable of power saving during the TXOP. If the AP does not know which STA enters the doze state for the remaining TXOP duration, the AP may transmit a frame (which may be a loss).
  • the HE STA must inform the AP of switching between TXOP PS modes.
  • OMI signaling may be explicitly used to enable HE TXOP PS.
  • the HE STA may transmit an OMI A-Control field indicating the HE TXOP PS to the AP. That is, the HE STA may request the HE TXOP PS through the HE TXOP PS subfield 1410 of the OMI A-Control field.
  • the HE TXOP PS subfield 1410 may be set to 0 to indicate that the HE STA does not want to sleep during TXOP. In addition, the HE TXOP PS subfield 1410 may be set to 1 to indicate that the HE STA wants to enter the doze state for the remaining TXOP.
  • the AP (or OMI responder) receiving the HE TXOP PS request confirms the HE TXOP PS of the HE STA by sending an ACK to the HE STA. Thereafter, when the MU-RTS (in case of RTS-CTS protection) transmitted from the AP, the trigger frame or the first frame does not include the AID of the HE STA requesting the TXOP PS, the HE STA may sleep for the remaining TXOP.
  • the MU-RTS in case of RTS-CTS protection
  • the STA requesting the TXOP PS through the OMI receives an ACK from the AP and enters the doze state during the TXOP when there is no AID in the frame received during the TXOP duration.
  • the OMI responder may enter the doze state until the TXOP ends under the following conditions.
  • the HE STA When the HE STA receives a DL PPDU not included in its AID from the AP, the HE STA may be in a doze state until the TXOP ends.
  • the HE STA When the HE STA receives the MU-RTS not included in its AID, if the HE STA listens to the CTS, the HE STA may be in a doze state until the TXOP ends.
  • the HE STA When the HE STA receives the MU-RTS not included in its AID, if the HE STA does not listen to the CTS, the HE STA may be in the doze state until the TXOP ends after waiting for the CTS timeout.
  • the HE STA may enter the doze state until the TXOP ends.
  • the HE STA may enter the doze state until the TXOP ends.
  • the AP should be able to schedule the first priority for the STA. This is because the STA requesting the HE TXOP PS may sleep immediately after receiving the packet from the AP.
  • the STA is sent at the start of TXOP.
  • the STA requesting the HE TXOP PS as described above may enter the doze state when there is no AID (or MAC address) in the packet received from the AP.
  • the AP needs to indicate whether the HE STA can enter a doze state during the TXOP.
  • a NAV-set sequence or trigger frame may be used (ie, the NAV-set sequence (eg, MU-RTS / CTS) is HE TXOP). May indicate a list of PS STAs)
  • the HE-STA may know whether it is scheduled in this TXOP. In this case, the HE STA may transmit the CTS frame 1520 in response to the MU-RTS frame.
  • the unintentional HE STA When the unintentional HE STA receives the MU-RTS frame 1510 without its AID, it may be in a doze state for the remaining TXOP period for the HE TXOP PS.
  • the HE STA in the HE TXOP PS mode must know the TXOP duration. This is done by checking the Duration field of the MU-RTS frame. MU-RTS / CTS exchange may be required at the start of TXOP.
  • the HE STA sends a MU-RTS (or RTS) to the CTS response.
  • the STA may enter the doze state after setting the NAV and checking whether the NAV is reset or not. If the STA hears the CTS, it may enter the doze state. If the STA does not hear the CTS, the STA waits for the CTS timeout and checks if the NAV is reset. Therefore, the STA may enter the dormant state unless the NAV is reset.
  • signaling may be performed using a specific subfield for the TXOP PS of an unintended STA or may be performed without signaling.
  • Embodiment 1 of signaling may be indicated through OMI.
  • a reserved 1 bit of the OMI A-Control field may be defined as HE TXOP PS.
  • Embodiment 2 of signaling may be indicated through a control frame (MU-RTS).
  • HE TXOP PS expressed by 1 bit can be defined using one subfield among reserved subfields of the common information field of the trigger frame illustrated in FIG. 10.
  • GI And LTF Type field 1050 MU MIMO LTF Mode field, Number of LTFs field, STBC field, LDPC Extra Symbol field, AP TX Power field, Packet Extension field, Spatial Reuse shown in FIG. Field, HE-SIG-A Reserved field 1040, and reserved fields are subfields that are not currently used in the MU-RTS and are reserved.
  • TXOP PS subfield can be represented by only 1 bit, it can be used as an indicator subfield of TXOP PS by using one of the reserved subfields described.
  • TXOP PS 1: In case of unintentional user of MU-RTS, perform TXOP PS.
  • TXOP PS 0: Even if an unintentional user of MU-RTS cannot wake up, TXOP PS cannot be performed.
  • the STA may implicitly define that the TXOP PS may be performed. For example, when capability negotiation is performed through the HE capabilities element, an unintended user whose AID is not present in the AID list of the user information field in the MU-RTS may perform TXOP PS for the remaining TXOP period.
  • the MU-RTS defines that TXOP PS can be used if an unintended user does not include his or her AID.
  • TXOP PS When inserting AID into MU-RTS, if there is no AID, TXOP PS can be performed (implicit method).
  • Example 1 If an unintended user receives MU-RTS while operating without signaling for TXOP PS, as in Example 1: There is no response from a frame such as CTS after MU-RTS (for example, if no packet is detected). Since the STAs should not sleep for the case, the TXOP PS may be applied in consideration of the NAVTimeout period.
  • TXOP PS is possible for the remaining TXOP.
  • Similar to NAV reset operation process for example, STA can sleep if NAV reset is not possible, and STA must stay awake if NAV reset occurs
  • the UE If the UE considers until TXOP truncation is performed to perform the TXOP PS, wait until the NAVTimeout period (non-DMG BSS) after receiving the MU-RTS and then detect the specific signal (for example, CTS) at that time TXOP PS It is defined as performing.
  • TXOP PS cannot be performed. That is, if any frame is detected after the MU-RTS reception, the NAV is not reset, so TXOP PS can be performed.
  • NAVTimeout period (2 * aSIFSTime) + (CTS_Time) + aRxPHYStartDelay + (2 * aSlotTime)
  • CTS_Time is calculated using the length of the CTS frame and the data rate at which the RTS frame used for the most recent NAV update was received.
  • TXOP PS may be implicitly performed.
  • the AP allows the HE STA to enter the doze state during TXOP as follows:
  • the AP must announce whether the HE STA supports power saving during TXOP in the beacon / probe response frame.
  • the AP In order to know whether the HE STA intends to power save the TXOP, the AP should send an acknowledgment in response to the OMI A-Control field with an indication of the HE TXOP PS.
  • the AP At the start of the TXOP, the AP must include a NAV-set sequence (eg MU-RTS / CTS) with a duration / ID value.
  • a NAV-set sequence eg MU-RTS / CTS
  • the AP should not transmit a frame to the HE STA.
  • the AP truncates the TXOP in which the HE STA can enter the doze state, it should not transmit a frame to the HE STA that can enter the doze state until the NAV set at the start of the TXOP expires.
  • the HE STA in the HE TXOP PS state may enter the doze state until the corresponding TXOP ends as follows:
  • -HE STA that wants to save power during TXOP should indicate HE TXOP PS in OMI A-Control field.
  • the HE STA When the HE STA negotiating the capability of the HE TXOP PS with the AP receives a frame indicated by an EOSP field of 1 and a More Data field of 0, the HE STA may enter a doze state until the corresponding TXOP ends.
  • the HE STA that transmits the HE TXOP PS enabled OMI A-Control field receives a frame indicated by 1 in the EOSP field and the More Data field is 0, the HE STA may enter a doze state until the corresponding TXOP ends. have.
  • the HE STA in the HE TXOP PS state and entering the doze state must continue to operate its NAV timer during the doze state and switch to the awake state when the NAV timer expires.
  • the operation of the unintended STA for the HE TXOP PS may be as follows.
  • Option 1 If there is no capability negotiation of the HE TXOP PS with the AP, when the HE STA receives an MU-RTS frame without its AID from the AP, the HE STA may implicitly enter the doze state for the remainder of the TXOP period. have.
  • Option 2 After performing the HE TXOP PS capability negotiation with the AP using the HE capability information of the HE Capabilities element, if the HE STA receives an MU-RTS frame without its own AID from the AP, it is implied for the remaining TXOP period. Can enter the doze state.
  • the HE STA may perform (or not) the capability negotiation, and the HE STA may instruct the AP to enable the HE TXOP PS.
  • the HE STA may enter the doze state for the remaining TXOP duration.
  • the HE STA when the HE STA receives an MU-RTS frame having its AID from the AP, the HE STA should not enter the doze state for the remaining TXOP duration.
  • the above technique enables a significant power saving if the HE STA does not have a frame to receive during TXOP.
  • the HE STA informs the AP and enters the TXOP PS mode.
  • the AP starts the NAV-set sequence when allowing power saving during TXOP.
  • 16 is a flowchart illustrating a procedure of operating in a TXOP power save mode according to the present embodiment.
  • the first station may be a non-AP station and the second station may correspond to an AP station communicating with the non-AP station.
  • the first station may be an intended station or an unintended station.
  • the intended station may correspond to a station that has received a frame containing its AID from the AP station.
  • the unintended station may correspond to a station that receives a frame that does not contain its AID from the AP station.
  • step S1610 the first station receives a Multi User-Request To Send (MU-RTS) frame during TXOP from the second station.
  • MU-RTS Multi User-Request To Send
  • the MU-RTS frame is used to inform the MU STA that the medium is to be accessed, thereby obtaining the MU TXOP.
  • step S1620 if there is no Association Identifier (AID) of the first station in the MU-RTS frame, the first station determines a transition to a doze state for the remaining period of the TXOP. That is, even if the TXOP period is not finished, if there is no frame to transmit and receive between the AP and the STA because there is no AID of the STA, the STA transitions to the doze state for the remaining TXOP period. As a result, the power of the STA can be saved more.
  • AID Association Identifier
  • the first station may determine whether to transmit a clear to send (CTS) frame.
  • CTS clear to send
  • the first station may set a network allocation vector (NAV) from a start point of the TXOP.
  • NAV network allocation vector
  • the first station may transition to a doze state for the remainder of the TXOP.
  • the first station If the first station does not transmit the CTS frame, the first station transitions to a doze state for the remainder of the TXOP when the NAV is not reset, and an awake state when the NAV is reset. ) Can be maintained.
  • the first station may determine whether the CTS can be detected until the CTS timeout is reached.
  • the first station may transmit TXOP power save request information through an OMI control field.
  • the TXOP power save request information may be indicated by 1 bit reserved in the OMI control field.
  • the OMI control field may correspond to the OMI A-Control field.
  • the first station may request the TXOP PS through the OMI control field and receive an ACK for the TXOP PS request from the second station.
  • the first station may receive a TXOP power save subfield through a trigger frame from the second station.
  • the TXOP power save subfield may be indicated by 1 bit reserved in the trigger frame.
  • the first station may transition to a doze state for the remaining period of the TXOP.
  • the TXOP power save subfield indicates 0, even if there is no AID of the first station in the MU-RTS frame, the first station does not transition to a doze state for the remaining period of the TXOP.
  • An embodiment using the TXOP power save subfield may be a technique for explicitly signaling that a specific subfield is used for the TXOP PS.
  • the first station may determine a transition to a doze state for the remaining period of the TXOP without performing capability negotiation with the second station.
  • the first station may be an unintended station, so capability negotiation with the second station may be needed via the HE capabilities element.
  • 17 is a block diagram illustrating a wireless device to which the present embodiment can be applied.
  • the wireless device may be an AP or a non-AP station (STA) that may implement the above-described embodiment.
  • the wireless device may correspond to the above-described user or may correspond to a transmission device for transmitting a signal to the user.
  • the AP 1700 includes a processor 1710, a memory 1720, and a radio frequency unit 1730.
  • the RF unit 1730 may be connected to the processor 1710 to transmit / receive a radio signal.
  • the processor 1710 may implement the functions, processes, and / or methods proposed herein.
  • the processor 1710 may perform an operation according to the present embodiment described above. That is, the processor 1710 may perform an operation that may be performed by the AP during the operations disclosed in the embodiments of FIGS. 1 to 16.
  • the non-AP STA 1750 includes a processor 1760, a memory 1770, and a radio frequency unit 1780.
  • the RF unit 1780 may be connected to the processor 1760 to transmit / receive a radio signal.
  • the processor 1760 may implement the functions, processes, and / or methods proposed in this embodiment.
  • the processor 1760 may be implemented to perform the non-AP STA operation according to the present embodiment described above.
  • the processor may perform the operation of the non-AP STA in the embodiment of FIGS. 1 to 16.
  • Processors 1710 and 1760 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 1720 and 1770 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices.
  • the RF unit 1730 and 1780 may include one or more antennas for transmitting and / or receiving a radio signal.
  • the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function.
  • the module is stored in the memories 1720 and 1770 and may be executed by the processors 1710 and 1760.
  • the memories 1720 and 1770 may be inside or outside the processors 1710 and 1760, and may be connected to the processors 1710 and 1760 by various well-known means.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

La présente invention concerne un procédé de fonctionnement dans un mode d'économie d'énergie TXOP dans un système de réseau local sans fil. En particulier, une première station reçoit une trame MU-RTS en provenance d'une seconde station pendant une TXOP. Lorsque l'AID de la première station n'est pas inclus dans la trame MU-RTS, la première station détermine le passage à un état de repos pour la période restante de la TXOP.
PCT/KR2017/006836 2016-07-07 2017-06-28 Procédé et appareil de fonctionnement en mode d'économie d'énergie txop dans un système de réseau local sans fil WO2018008890A1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
US201662359209P 2016-07-07 2016-07-07
US62/359,209 2016-07-07
US201662408067P 2016-10-14 2016-10-14
US62/408,067 2016-10-14
US201662410404P 2016-10-20 2016-10-20
US62/410,404 2016-10-20
US201762510763P 2017-05-25 2017-05-25
US62/510,763 2017-05-25

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