WO2015105392A1 - 무선랜에서 파워 세이브 모드 기반의 동작 방법 및 장치 - Google Patents
무선랜에서 파워 세이브 모드 기반의 동작 방법 및 장치 Download PDFInfo
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- WO2015105392A1 WO2015105392A1 PCT/KR2015/000300 KR2015000300W WO2015105392A1 WO 2015105392 A1 WO2015105392 A1 WO 2015105392A1 KR 2015000300 W KR2015000300 W KR 2015000300W WO 2015105392 A1 WO2015105392 A1 WO 2015105392A1
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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
- H04W52/0209—Power saving arrangements in terminal devices
- H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave
- H04W52/0216—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave using a pre-established activity schedule, e.g. traffic indication frame
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/02—Traffic management, e.g. flow control or congestion control
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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
- H04W52/0209—Power saving arrangements in terminal devices
- H04W52/0225—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal
- H04W52/0235—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal where the received signal is a power saving command
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- 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]
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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
- H04W52/0209—Power saving arrangements in terminal devices
- H04W52/0225—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal
- H04W52/0229—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal where the received signal is a wanted signal
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- 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 invention relates to wireless communication, and more particularly, to a method and apparatus for operating based on a power save mode in a wireless local area network (WLAN).
- WLAN wireless local area network
- a power save mechanism (or a power save mode) may be used to increase the lifetime of a WLAN STA.
- the STA operating based on the power saving mode may operate in an awake state or a doze state for power saving.
- the awake state is a state in which normal operation of the STA such as transmission or reception of a frame or channel scanning is possible.
- the doze state dramatically reduces power consumption, making it impossible to transmit or receive a frame and to perform channel scanning.
- the STA when the STA operates in the power saving mode, the STA may be in the doze state and, if necessary, may be switched to the awake state to reduce power consumption.
- the STA may operate by acquiring information on the existence of a frame pending at the AP and periodically switching to an awake state to receive the frame held at the AP.
- the AP may obtain information on the awake state operation timing of the STA, and transmit information on the presence or absence of a frame pending to the AP according to the awake state operation timing of the STA.
- the STA in the doze state may receive a beacon frame by periodically switching from the doze state to the awake state in order to receive information on the existence of a frame to be received from the AP.
- the AP may inform about the existence of a frame to be transmitted to each STA based on a traffic indication map (TIM) included in the beacon frame.
- TIM is used to inform the existence of a unicast frame to be transmitted to the STA
- DTIM delivery traffic indication map
- An object of the present invention is to provide a power save mode based operation method in a WLAN.
- Still another object of the present invention is to provide an operation device based on a power save mode in a WLAN.
- a method of operating a power save mode based on a wireless LAN includes a method in which an STA is transmitted by an access point (AP) after switching to the power save mode. Transitioning from a sleep mode to an active mode based on a listening interval for receiving a 1 beacon frame; when the first beacon frame indicates buffered data for the STA, the STA transitions to the active mode Monitoring a frame for the STA transmitted by the AP before expiration of a timer started in the step; and switching the STA to the sleep mode after expiration of the timer, wherein the timer transmits the frame. Can be reset if
- a station (station) operating in a power save mode is implemented with a radio frequency (RF) unit for transmitting or receiving a radio signal; And a processor operatively connected to the RF unit, wherein the processor is configured to receive the first beacon frame transmitted by an access point (AP) after switching to the power save mode based on a listening interval.
- RF radio frequency
- AP access point
- the STA is transmitted by the AP before expiration of the timer started at the time of switching to the active mode.
- An STA operating in a power save mode may receive the downlink data pending from the AP without transmitting a power saving (PS) -poll frame.
- PS power saving
- WLAN wireless local area network
- FIG. 2 is a conceptual diagram illustrating a scanning method in a WLAN.
- FIG. 3 is a conceptual diagram illustrating an authentication procedure and a combined procedure performed after a scanning procedure of an AP and an STA.
- FIG. 4 is a conceptual diagram illustrating a beacon frame-based power save method.
- FIG. 5 is a conceptual diagram illustrating a beacon frame-based power save method.
- FIG. 6 is a conceptual diagram illustrating a power save method according to an embodiment of the present invention.
- FIG. 7 is a conceptual diagram illustrating a power save method according to an embodiment of the present invention.
- FIG. 8 is a conceptual diagram illustrating a power save method according to an embodiment of the present invention.
- FIG. 9 is a conceptual diagram illustrating a non-PS-poll mode setting element according to an embodiment of the present invention.
- FIG. 10 is a conceptual diagram illustrating a power save operation of an STA according to an embodiment of the present invention.
- FIG. 11 is a conceptual diagram illustrating a non-PS-poll mode TIM element according to an embodiment of the present invention.
- FIG. 12 is a conceptual diagram illustrating a PPDU format for delivering a frame according to an embodiment of the present invention.
- FIG. 13 is a block diagram illustrating a wireless device to which an embodiment of the present invention can be applied.
- WLAN wireless local area network
- FIG. 1 shows the structure of an infrastructure BSS (Basic Service Set) of the Institute of Electrical and Electronic Engineers (IEEE) 802.11.
- BSS Basic Service Set
- IEEE Institute of Electrical and Electronic Engineers 802.11
- 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 joinable STAs 105-1 and 105-2 to one AP 130.
- the BSS may include at least one STA, APs 125 and 130 that provide a distribution service, and a distribution system DS that connects 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.
- 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 a medium access control (MAC) and physical layer interface to a wireless medium that is compliant with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. 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.
- 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).
- 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.
- FIG. 2 is a conceptual diagram illustrating a scanning method in a WLAN.
- a scanning method may be classified into passive scanning 200 and active scanning 250.
- the passive scanning 200 may be performed by the beacon frame 230 periodically broadcasted by the AP 200.
- the AP 200 of the WLAN broadcasts the beacon frame 230 to the non-AP STA 240 every specific period (for example, 100 msec).
- the beacon frame 230 may include information about the current network.
- the non-AP STA 240 receives the beacon frame 230 that is periodically broadcast to receive the network information to perform scanning for the AP 210 and the channel to perform the authentication / association (authentication / association) process Can be.
- the passive scanning method 200 only needs to receive the beacon frame 230 transmitted from the AP 210 without requiring the non-AP STA 240 to transmit the frame.
- passive scanning 200 has the advantage that the overall overhead incurred by the transmission / reception of data in the network is small.
- scanning can be performed manually in proportion to the period of the beacon frame 230, the time taken to perform scanning is relatively increased compared to the active scanning method.
- beacon frame For a detailed description of the beacon frame, see IEEE Draft P802.11-REVmb TM / D12, November 2011 'IEEE Standard for Information Technology Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications (hereinafter referred to as IEEE 802.11) 'are described in 8.3.3.2 beacon frame.
- IEEE 802.11 ai may additionally use other formats of beacon frames, and these beacon frames may be referred to as fast initial link setup (FILS) beacon frames.
- a measurement pilot frame may be used in a scanning procedure as a frame including only some information of a beacon frame. Measurement pilot frames are disclosed in the IEEE 802.11 8.5.8.3 measurement pilot format.
- a FILS discovery frame may be defined.
- the FILS discovery frame is a frame transmitted between transmission periods of a beacon frame at each AP and may be a frame transmitted with a shorter period than the beacon frame. That is, the FILS discovery frame is a frame transmitted with a period smaller than the transmission period of the beacon frame.
- the FILS discovery frame may include identifier information (SSID, BSSID) of the AP transmitting the detection frame.
- the FILS discovery frame may be transmitted before the beacon frame is transmitted to the STA to allow the STA to detect in advance that the AP exists in the corresponding channel.
- the interval at which a FILS discovery frame is transmitted from one AP is called a FILS discovery frame transmission interval.
- the FILS discovery frame may include part of information included in the beacon frame and be transmitted.
- the non-AP STA 290 may transmit the probe request frame 270 to the AP 260 to proactively perform scanning.
- the AP 260 After receiving the probe request frame 270 from the non-AP STA 290, the AP 260 waits for a random time to prevent frame collision, and then includes network information in the probe response frame 280. may transmit to the non-AP STA 290. The non-AP STA 290 may obtain network information based on the received probe response frame 280 and stop the scanning process.
- the probe request frame 270 is disclosed in IEEE 802.11 8.3.3.9 and the probe response frame 280 is disclosed in IEEE 802.11 8.3.3.10.
- the AP and the non-AP STA may perform an authentication procedure and an association procedure.
- FIG. 3 is a conceptual diagram illustrating an authentication procedure and a combined procedure performed after a scanning procedure of an AP and an STA.
- an authentication procedure and a combining procedure with one of the scanned APs may be performed.
- Authentication and association procedures can be performed, for example, via two-way handshaking.
- the left side of FIG. 3 is a conceptual diagram illustrating an authentication and combining procedure after passive scanning, and the right side of FIG. 3 is a conceptual diagram showing an authentication and combining procedure after active scanning.
- the authentication procedure and the association procedure are based on an authentication request frame 310 / authentication response frame 320 and an association request frame 330 regardless of whether active scanning method or passive scanning is used.
- / Association response frame 340 may be equally performed by exchanging an association response frame 340 between the AP 300, 350 and the non-AP STA 305, 355.
- the non-AP STAs 305 and 355 may transmit the authentication request frame 310 to the APs 300 and 350.
- the AP 300 or 350 may transmit the authentication response frame 320 to the non-AP STAs 305 and 355 in response to the authentication request frame 310.
- Authentication frame format is disclosed in IEEE 802.11 8.3.3.11.
- the non-AP STAs 305 and 355 may transmit an association request frame 330 to the APs 300 and 305.
- the APs 305 and 355 may transmit the association response frame 340 to the non-AP STAs 300 and 350.
- the association request frame 330 transmitted to the AP includes information on the capabilities of the non-AP STAs 305 and 355. Based on the performance information of the non-AP STAs 305 and 355, the APs 300 and 350 may determine whether support for the non-AP STAs 305 and 355 is possible.
- the APs 300 and 350 may transmit the combined response frame 340 to the non-AP STAs 305 and 355.
- the association response frame 340 may include whether or not to accept the association request frame 340, and the capability information that can be supported by the association response frame 340.
- Association frame format is disclosed in IEEE 802.11 8.3.3.5/8.3.3.6.
- association procedure After the association procedure is performed between the AP and the non-AP STA, normal data transmission and reception may be performed between the AP and the non-AP STA. If the association procedure between the AP and the non-AP STA fails, the association procedure with the AP may be performed again or the association procedure with another AP may be performed again based on the reason for the association failure.
- the STA When the STA is associated with the AP, the STA may be assigned an association identifier (AID) from the AP.
- the AID assigned to the STA may be a unique value within one BSS, and the current AID may be one of 1 to 2007. 14bit is allocated for AID and can be used as the value of AID up to 16383. However, the value of 2008 ⁇ 16383 is reserved.
- 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 an uplink frame pending 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, if there is a pending frame to be transmitted to the STA in the doze state, the AP cannot transmit the frame 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).
- FIG. 4 is a conceptual diagram illustrating a beacon frame-based power save method.
- the AP may periodically transmit a beacon frame
- the STA may periodically switch from the doze state to the awake state to receive the beacon frame in consideration of the transmission timing of the beacon frame.
- the beacon frame may include a traffic indication map element (TIM element).
- TIM element may be used to transmit information on downlink data for the STA pending to the AP.
- the TIM element may transmit information about a frame pending to the STA based on a bitmap.
- the TIM element may be divided into a TIM or a delivery TIM (DTIM).
- the TIM may indicate the presence of pending downlink data to be transmitted to the STA on unicast basis.
- the DTIM may indicate the presence of pending downlink data to be transmitted on a broadcast / multicast basis.
- FIG. 4 discloses a method in which an AP transmits a downlink frame based on an immediate response to a power saving (poll) -poll frame.
- the STA may receive information on the existence of downlink data pending for the STA from the AP based on the TIM of the beacon frame 400.
- the STA may transmit the PS-poll frame 410 to the AP.
- the AP may receive the PS-poll frame 410 from the STA and transmit the downlink frame 420 to the STA in an immediate response to the PS-poll frame 410.
- the immediate response to the PS-poll frame of the AP may be performed after receiving the PS-poll frame and short interframe space (SIFS).
- SIFS short interframe space
- the STA may transmit the ACK frame 430 in response to the downlink frame.
- the STA may be switched back (or transitioned) to the doze state.
- FIG. 4 shows a method of transmitting a downlink frame of an AP based on a deferred response to a PS-poll frame.
- the STA may receive information about the existence of downlink data pending for the STA from the AP based on the TIM of the beacon frame 440.
- the STA may transmit the PS-poll frame 450 to the AP.
- the AP may receive the PS-poll frame 450 from the STA and transmit the ACK frame 460 to the STA in response to the PS-poll frame 450.
- the AP may transmit a downlink frame 470 including the pending downlink data to the STA after transmission of the ACK frame 460.
- the STA may monitor the downlink frame 470 transmitted by the AP to the STA after receiving the ACK frame 460.
- the STA may be switched (or transitioned) from the awake state to the doze state again.
- FIG. 5 is a conceptual diagram illustrating a beacon frame-based power save method.
- the DTIM is transmitted through the beacon frame 500.
- Beacon frame 500 may include a DTIM.
- the DTIM may indicate the presence of pending downlink data to be transmitted on a broadcast / multicast basis.
- the AP may transmit a beacon frame 500 including the DTIM to the STA.
- the STA may maintain the awake state without transmitting the PS-poll frame and monitor the transmission of the downlink frame 520.
- the AP may transmit the downlink frame 520 to the STA through a multicast method or a broadcast method.
- the existing TIM element-based power save mechanism (or power save method) disclosed in FIGS. 4 and 5 may have the following problems.
- the STA must transmit a PS-poll frame to the AP in order to receive the TIM and receive downlink data. After the STA is switched from the doze state to the awake state, the STA may transmit the PS-poll frame to the AP through contention-based access.
- transmission of the PS-poll frame may be difficult due to competition between the plurality of STAs.
- a delay from receiving a beacon frame to receiving a downlink frame from the AP of the STA may be large.
- the STA Before receiving a TIM and receiving downlink data, the STA needs to transmit a PS-poll frame and a reception procedure of an ACK frame for the PS-poll frame.
- an embodiment of the present invention discloses a method for reducing signaling overhead and downlink data reception delay of an STA operating in a power save mode.
- the doze state may be used in the same meaning as the sleep mode and the awake state as the active mode. In the doze state, transmission or reception of a frame by the STA may not be performed.
- the transmission from the AP to the STA may be expressed by the term downlink transmission.
- Each of the PPDUs, frames, and data transmitted through downlink transmission may be represented by the terms downlink PPDU, 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 transmission from the STA to the AP may be expressed in the term of downlink transmission.
- Each of the PPDUs, frames, and data transmitted through uplink transmission may be expressed in terms of uplink PPDU, uplink frame, and uplink data.
- FIG. 6 is a conceptual diagram illustrating a power save method according to an embodiment of the present invention.
- a non-PS-poll section 600 and a PS-poll section 610 are defined, and a downlink transmitted by an AP on a non-PS poll section 600 and a PS-poll section 610 of an STA.
- a method of receiving a link frame (or downlink data) is disclosed.
- the STA is a downlink frame (buffered (or pending) downlink data) that is pending without transmission of the PS-poll frame. ) 635.
- the STA receives the beacon frame 630 including a TIM indicating downlink data pending for the STA, the STA does not transmit a PS-poll frame to the AP, and includes downlink data pending from the AP.
- the downlink frame 635 may be received.
- the STA may operate in an awake state (or active mode) for a predetermined time period in the non-PS-poll period 600.
- the downlink frame reception operation of the STA in the non-PS-poll period 600 may be expressed by the term non-PS-poll mode operation.
- the start time of the non-PS-poll section 600 is the time to switch to the first awake state after switching to the power save mode from the non-power save mode (or active mode) of the STA or the power of the STA of the STA. It may be a reception time of the first beacon frame 630 after the switch to the save mode.
- the start time of the non-PS-poll section 600 is assumed to be a transition (or transition) time to the awake state.
- the length (or duration) of the non-PS-poll section 600 may be determined based on a timer that determines the length (or end) of the non-PS-poll section 600.
- the timer for determining the length of the non-PS-poll section 600 (or whether the non-PS-poll section 600 ends) may be expressed by the term non-PS-poll section timer 620.
- the non-PS-poll interval timer 620 may be started at the start of the non-PS-poll interval 600.
- the set timer value is decreased. It may expire at the time of expiration.
- the non-PS-poll interval timer 620 restarts again if the STA receives the downlink frame 635 from the AP (or if the downlink frame 635 is transmitted to the STA by the AP) before the expiration time. Or reset.
- the non-PS-Poll Interval timer 620 may be started.
- the non-PS-poll interval 600 may end and the STA may be switched to the doze state.
- the non-PS-Poll interval timer 620 When the non-PS-Poll interval timer 620 is started, the non-PS-Poll interval timer 620 may be reduced to 0 from the set initial value.
- the initial value of the non-PS-Poll interval timer 620 may be transmitted through a combined response frame transmitted by the AP in the initial access procedure of the STA and the AP.
- the initial value of the non-PS-poll interval timer 620 may be a fixed value or a variable that may be set separately.
- the STA switched to the doze state after the end of the non-PS-poll period 600 may be switched to the awake state based on the listening interval to receive the beacon frame 640.
- the PS-poll section 610 is based on a listening time after the non-PS-poll section 600 of the STA based on a listening interval or a listening interval after the non-PS-poll section 600 of the STA of the STA. After the transition to the awake state may be started at the time of receiving the beacon frame 640.
- the start time of the PS-poll section 610 is assumed to be a transition time to an awake state based on the listening interval.
- the downlink frame reception operation of the STA in the PS-poll period 610 may be expressed by the term PS-poll mode operation.
- the STA operating in the PS poll mode may perform a downlink frame reception operation based on the PS-poll frame 650 as described above with reference to FIGS. 4 and 5.
- the STA may transmit a PS-Poll frame 650 to the AP.
- the AP may receive a downlink frame 645 including downlink data pending to the STA. If there is no downlink frame pending for the STA in the AP, the STA may be switched to the doze state.
- the STA operating in the PS-poll section 610 may be expressed by the term STA operating in the PS-poll mode.
- the STA switched to the doze state after the PS-poll period 610 may switch back to the awake state based on the listening interval and operate in the non-PS-poll mode again to receive the beacon frame 670 from the AP.
- the next non-PS-poll section 660 is based on a listening interval after the PS-poll section 610 of the STA, or a listening interval after the PS-poll section 610 of the STA of the STA. After switching to the awake state based on the start of the beacon frame 670 may be started. Similarly, when the non-PS-poll section timer 620 expires, the non-PS-poll section 660 may end.
- a start time of the non-PS-poll section 660 is assumed to be a time of transition to an awake state.
- the non-PS-poll section (or non-PS-poll mode) may be initiated.
- a non-PS-poll interval may begin.
- the listening interval may be a transition interval to the awake state of the STA for receiving the beacon frame. In other words, the listening interval may indicate how often the STA operating in the power save mode transitions to the awake state (wakes up) to listen to the beacon frame.
- the STA receives downlink data (new downlink data and buffered (or pending) downlink data) pending for the STA from the AP on the PS-poll interval and is switched to the doze state, based on the next listening interval After the transition to the awake state, the non-PS-poll section may be started.
- downlink data new downlink data and buffered (or pending) downlink data
- the STA when the SNR of the medium does not satisfy a specific signal to noise ratio (SNR) threshold, the STA may not operate in the non-PS-poll mode. That is, the non-PS-poll period may not be allocated to the STA.
- the SNR threshold for determining the allocation of the non-PS-poll interval may be included in the joint request frame and the joint response frame transmitted or received in the initial access procedure of the STA.
- the STA may transmit the association request frame including the information on the SNR threshold or the AP may transmit the association response frame including the information on the SNR threshold.
- the STA may not operate in the non-PS-poll mode. This will be described later in detail.
- FIG. 7 is a conceptual diagram illustrating a power save method according to an embodiment of the present invention.
- reception of downlink data of an STA is initiated in a non-PS-poll section and a PS-poll section.
- the STA may transmit a frame (power save mode switch indication frame 700) including information indicating that the STA operates in the power save mode to the AP.
- a frame power save mode switch indication frame 700
- the STA transmits a power save mode switch indication frame 700 having a power saving bit (PS bit) set to 1 to indicate that the STA operates in the power save mode to the AP to save power of the STA.
- the AP may be notified of the transition to the mode.
- the STA may receive an ACK frame 710 for the power save mode switch indication frame 700 from the AP and switch to the doze state.
- the STA may switch to the awake mode based on the listening interval after switching to the doze state and receive the first beacon frame 720 after switching to the power save mode.
- the non-PS-poll period when the STA is switched from the non-power save mode to the power save mode and is switched to the awake state based on the listening interval, the non-PS-poll period may be started.
- the STA may operate in the non-PS-poll mode on the non-PS-poll interval. In more detail, the STA may not transmit the PS-poll frame in the non-PS-poll period.
- the STA may operate the non-PS-Poll interval timer when the non-PS-poll interval starts.
- the non-PS-Poll interval timer of the STA for determining whether to end the non-PS-poll interval may be started with the start of the start of the non-PS-poll interval.
- the STA may determine whether there is downlink data pending for the STA based on the TIM of the beacon frame 720. For example, when the TIM included in the beacon frame indicates the presence of downlink data pending in the STA, the STA may monitor downlink frames 730 and 740 transmitted by the AP to the STA.
- the STA operating in the non-PS-poll mode may monitor the downlink frames 730 and 740 until the expiration of the non-PS-poll interval timer without transmitting the PS-poll frame.
- the STA may be switched to the doze state.
- An expiration time of the non-PS poll period timer may be an end time of the non-PS poll interval.
- the STA may maintain the dose state after the end of the non-PS poll interval until it is switched back to the awake state based on the listening interval.
- the STA may maintain an awake state.
- the STA receives the downlink frames 730 and 740 for the STA until the non-PS-poll interval timer expires, the STA resets the non-PS-poll interval timer to an initial value and maintains an awake state and for the STA. Additional downlink frame can be monitored. If the additional downlink frame for the STA is not received until the expiration of the non-PS-poll duration timer after the reset of the non-PS-poll duration timer, the STA may be switched to the doze state.
- the operation of the non-PS-poll section timer may be stopped and switched to the doze state. It may be.
- the STA may switch back to the awake state based on the listening interval after the non-PS-poll period and operate in the PS poll mode.
- the STA operating in the PS-poll mode may determine whether there is downlink data pending for the STA based on the TIM included in the beacon frame 760. If there is no downlink data pending for the STA, the STA may be switched to the doze state again. Conversely, if there is no downlink data pending for the STA, the STA may transmit the PS-poll frame 770 to the AP, receive an ACK frame for the PS-poll frame 770, and receive new downlink data ( Or downlink frames 780 and 790 including buffered (or pending) downlink data).
- the STA operating in the PS poll mode may be switched to the doze state.
- the STA may not receive the pending downlink data due to the end of the non-PS-poll interval timer in the non-PS-poll period. Even in such a case, the STA may receive downlink data pending in the STA based on the PS-poll mode operation in the PS-poll section.
- the STA may be switched to the awake state based on the listening interval to operate in the non-PS-poll mode.
- the STA may receive the beacon frame 795 and monitor downlink data without transmitting the PS-poll frame based on the non-PS-poll interval timer.
- FIG. 8 is a conceptual diagram illustrating a power save method according to an embodiment of the present invention.
- reception of downlink data of a plurality of STAs is started in a non-PS-poll period and a PS-poll period.
- a TIM included in the beacon frames 810, 825, and 850 indicates downlink data that is pending for each of STA1 and STA2.
- each of the STA1 and the STA2 may transmit the power save mode switch instruction frames 800 and 805 instructing the switch to the power save mode to the AP and switch from the non-power save mode to the power save mode.
- Each of the STA1 and the STA2 may receive an ACK frame for the power save mode switch indication frames 800 and 805 from the AP, and switch to the doze state.
- the STA 1 and the STA2 may switch to the awake mode based on the listening interval and operate based on the non-PS-poll mode to receive the downlink frames 815 and 820 from the AP.
- STA1 may maintain the awake state until the non-PS-poll interval timer expires and monitor the downlink frame 815 for STA1 transmitted by the AP.
- the AP may transmit a downlink frame1 815 including downlink data pending for the STA1 to the STA1.
- the STA1 may receive the downlink frame 1 815 and transmit an ACK frame for the downlink frame 1 815 to the AP.
- the STA1 may reset the non-PS-poll interval timer after receiving the downlink frame1 815.
- the reset non-PS-poll interval timer may expire when an additional downlink frame for STA1 is not transmitted.
- STA1 may be switched to the doze state when the non-PS-poll interval timer expires.
- STA2 may maintain the awake state until the non-PS-poll interval timer expires and monitor the downlink frame 820 for STA2 transmitted by the AP.
- the AP may transmit a downlink frame 2 820 including downlink data pending for STA2 to STA2.
- STA2 may receive the downlink frame 2 820 and transmit an ACK frame for the downlink frame 2 820 to the AP.
- the STA2 may reset the non-PS-poll interval timer after receiving the downlink frame 2 820.
- the reset non-PS-poll interval timer may expire when no additional downlink frame for STA2 is transmitted.
- STA2 may be switched to the doze state when the non-PS-poll interval timer expires.
- transmission of the PS-poll frame by each of the STA1 and the STA2 operating in the non-PS-poll mode may not be performed.
- the congestion of the medium due to the PS-poll frame and the signaling overhead for the transmission of the PS-poll frame may be reduced.
- each of STA1 and STA2 may receive a downlink frame without transmitting a PS-poll frame. Therefore, the reception delay of the downlink frame of each of the STA1 and the STA2 can be reduced.
- each of the STA 1 and STA2 switched to the doze state may be switched to the awake mode based on the listening interval to operate in the PS-poll mode.
- FIG. 8 it is assumed that the listening intervals of the STA1 and the STA2 are the same.
- Each of STA1 and STA2 may transmit PS-poll frames 830 and 840 to the AP through contention-based channel access.
- STA1 acquires a channel access right before STA2.
- the STA1 may acquire a channel access right before the STA2 and transmit the PS-poll frame 1 830 to the AP.
- the STA1 may receive an ACK frame in response to the PS-poll frame1 830 to the AP.
- the AP After transmitting the ACK frame, the AP may transmit downlink frame 3 835 including downlink data pending for STA1.
- the STA1 may transmit an ACK frame to the AP in response to the downlink frame3 835.
- the STA1 switches to the doze state when a field indicating the presence of additional pending downlink data included in the downlink frame 3 835 (eg, the MoreData field) indicates the absence of additional pending downlink data. Can be.
- the STA2 may acquire a channel access right through contention-based channel access and transmit the PS-poll frame 2 to the AP.
- the STA2 may receive an ACK frame in response to the PS-poll frame2 840 to the AP.
- the AP may transmit downlink frame 4 845 including downlink data pending for STA2.
- STA2 may transmit an ACK frame to the AP in response to the downlink frame 4 (845).
- the STA2 switches to the doze state when a field indicating the presence of additional pending downlink data included in the downlink frame 4 (845) (eg, the MoreData field) indicates the absence of additional pending downlink data. Can be.
- the STA- and / or STA2 may perform the PS- of STA- and STA2 in the PS-poll interval. Based on the poll mode operation, downlink data pending for STA1 and / or STA2 may be received.
- the STA1 and the STA2 may switch back to the awake state based on the listening interval and operate in the non-PS-poll mode again.
- Each of the STA1 and the STA2 may receive the beacon frame 850 and monitor the downlink data 860 without transmitting the PS-poll frame based on the non-PS-poll interval timer.
- FIG. 9 is a conceptual diagram illustrating a non-PS-poll mode setting element according to an embodiment of the present invention.
- a non-PS-poll mode setting element (or a non-PS-poll mode parameter set element) for non-PS-poll mode based operation of an STA is disclosed.
- the non-PS-poll mode setting element may be transmitted through a separate frame, but a frame transmitted or received between the STA and the AP upon initial access to the STA's AP (eg, a beacon frame, a join request frame, or a join response). Frame).
- the non-PS-poll mode setting element includes an element ID field 900, a length field 910, a non-PS-poll mode timer field 920, an SNR threshold field 930. ), And a mobility threshold field 940.
- the element ID field 900 may include identifier information for indicating a non-PS-poll mode setting element.
- the length field 910 may include information about the length of the non-PS-poll mode timer field, the SNR threshold field, and the mobility threshold field.
- the non-PS-poll mode timer field 920 may include information about a default operation time of the STA in the non-PS-poll mode.
- the basic operation time may be a time for maintaining an awake state when the STA has not received the downlink frame.
- the non-PS-poll mode timer field 920 may include information on an initial value of the non-PS-poll interval timer.
- the initial value of the non-PS-poll interval timer may be a multiple of the listening interval. For example, when the value of the non-PS-poll mode timer field 920 is 1, the STA may operate in the non-PS-poll mode for (2 * Beacon Interval). Alternatively, when the value of the non-PS-poll mode timer field 920 is 2, the STA may operate in the non-PS-Poll mode for (3 * Beacon Interval). Alternatively, the non-PS-poll mode timer field 920 may directly include information on a time interval for non-PS-poll mode operation of the STA in ms.
- the SNR threshold field 930 may include information on the minimum SNR (or SNR threshold) of the medium for the STA to operate in the non-PS-poll mode. As described above, when the SNR of the medium is greater than or equal to the minimum SNR, the STA may operate in the non-PS-poll mode.
- the mobility threshold field 940 may include information on the minimum mobility (or mobility threshold) of the STA for the STA to operate in the non-PS-poll mode.
- the STA may perform the operation in the non-PS-poll mode only when the mobility is less than or equal to the minimum mobility.
- the STA may basically operate based on the non-PS-poll mode.
- FIG. 10 is a conceptual diagram illustrating a power save operation of an STA according to an embodiment of the present invention.
- a non-PS-poll mode operation of an STA is disclosed based on a separate bitmap for non-PS-poll mode operation.
- a non-PS-poll mode TIM including information on a separate bitmap for non-PS-poll mode operation of an STA may be defined.
- the non-PS-poll mode TIM may indicate reception of downlink data (or downlink frame) based on the non-PS-poll mode operation of the STA.
- the STA receives the beacon frame 1000 based on the listening interval, and the beacon frame 1000 may include a non-PS-poll mode TIM.
- the non PS-poll mode TIM may include a bitmap field (eg, a partial virtual bitmap) and the bitmap field may include information about the non PS-poll mode TIM bitmap. .
- Non-PS-poll Mode When the TIM bitmap indicates data pending to the STA, the STA may operate in the non-PS-poll mode.
- the legacy TIM and the non-PS-poll mode TIM of the beacon frame 1000 may be included.
- the legacy TIM may include a legacy virtual TIM bitmap for indicating downlink data pending for the STA.
- the non-PS-poll mode TIM may include a non-PS-poll mode TIM bitmap for indicating downlink data pending for the STA. If the downlink data pending for the STA is indicated based on the legacy TIM, the STA may operate in the PS-poll mode to receive the downlink frame. If downlink data pending for the STA is indicated based on the non-PS-poll TIM, the STA may receive the downlink frame by operating in the non-PS-poll mode.
- the beacon frame 1000 transmitted by the AP may include a legacy TIM and a non-PS-poll mode TIM.
- the STA may operate in the PS-poll mode to receive the downlink data from the AP. Specifically, when the bit value for the STA indicates downlink data pending for the STA on the legacy virtual TIM bitmap included in the legacy TIM (or the STA indicates a positive indication at the position of the STA on the legacy virtual TIM bitmap of the legacy TIM). (detecting a positive indication), the STA may operate based on the PS-poll mode to receive downlink data from the AP.
- the STA may operate based on the non-PS-poll mode to receive downlink data from the AP. have. Specifically, when the bit value for the STA indicates downlink data pending for the STA on the non-PS-poll mode TIM bitmap of the non-PS-poll mode TIM (or the STA is a non-PS-poll mode TIM). When a positive indication is detected at the position of the STA on the poll mode TIM bitmap), the STA may operate based on the non-PS-poll mode to receive downlink data from the AP.
- the STA may switch to the doze state when the non-PS-poll interval timer is operated and the non-PS-poll interval timer expires.
- the AP may indicate the downlink data pending for one STA based on one bitmap of a legacy virtual TIM bitmap and a non-PS-poll mode TIM bitmap.
- the STA may operate in the PS-poll mode or the non-PS-poll mode based on one bitmap indicating the presence of the pending downlink data among the legacy virtual TIM bitmap and the non-PS-poll mode TIM bitmap.
- FIG. 11 is a conceptual diagram illustrating a non-PS-poll mode TIM element according to an embodiment of the present invention.
- a non-PS-poll mode TIM element for non-PS-poll mode based operation of an STA is disclosed.
- the non-PS-poll mode TIM element may be transmitted via a beacon frame.
- the non-PS-poll mode TIM elements include element ID field 1100, length field 1110, DTIM count field 1120, DTIM period field 1130, bitmap control field 1140, and partial It may include a virtual bitmap field 1150.
- It may include an element ID field 1100, a length field 1110, a DTIM count field 1120, a DTIM period field 1130, a bitmap control field 1140, and a partial virtual bitmap field 1150. have.
- the element ID field 1100 may include identifier information for indicating a non-PS-poll mode TIM element.
- the length field 1110 may include information about the length of a DTIM count field, a DTIM period field, a bitmap control field, and a partial virtual bitmap field.
- the DTIM count field 1120 may indicate how many beacon frames appear before the next DTIM. If the DTIM count is 0, it may indicate that the current TIM is DTIM.
- the DTIM period field 1130 may include information on the number of beacon intervals between successive DTIMs. If all TIMs are DTIMs, the value of the DTIM period field may be 1.
- the bitmap control field 1140 may include bitmap offset information for interpretation of the partial virtual bitmap field.
- the partial virtual bitmap field 1150 may include information on the aforementioned non-PS-poll mode TIM bitmap.
- the STA may determine whether to perform a non-PS-poll mode based operation based on the non-PS-poll mode TIM bitmap included in the partial virtual bitmap field 1150.
- FIG. 12 is a conceptual diagram illustrating a PPDU format for delivering a frame according to an embodiment of the present invention.
- the PPDU may include a PPDU header and a MAC protocol data unit (MPDU) (or a physical layer service data unit (PSDU)).
- MPDU MAC protocol data unit
- PSDU physical layer service data unit
- the frame may correspond to an MPDU.
- the PPDU header in the PPDU format may be used to mean a PHY header and a PHY preamble of the PPDU.
- the PPDU format disclosed in FIG. 12 may be used to carry the aforementioned downlink frame, ACK frame, and the like.
- the PPDU header of the downlink PPDU may include a legacy short training field (L-STF), a legacy long training field (L-LTF), a legacy-signal (L-SIG), and an HE-SIG A.
- L-STF legacy short training field
- L-LTF legacy long training field
- L-SIG legacy-signal
- HE-SIG A high efficiency-signal A
- HE-STF high efficiency-short training field
- HE-LTF high efficiency-long training field
- HE-SIG B high efficiency-signal-B
- the L-STF 1200 may include a short training orthogonal frequency division multiplexing symbol.
- the L-STF 1200 may be used for frame detection, automatic gain control (AGC), diversity detection, and coarse frequency / time synchronization.
- AGC automatic gain control
- the L-LTF 1210 may include a long training orthogonal frequency division multiplexing symbol.
- the L-LTF 1210 may be used for fine frequency / time synchronization and channel prediction.
- L-SIG 1220 may be used to transmit control information.
- the L-SIG 1220 may include information about a data rate and a data length.
- the HE-SIG A 1230 may include identification information of a STA for indicating a target STA to receive a downlink PPDU.
- the STA may determine whether to receive the information included in the HE-SIG A 1230 based on the identifier information of the target STA.
- the STA may perform additional decoding on the downlink PPDU.
- the HE-SIG A 1230 may be configured to receive downlink data (frequency resources (or subbands) based on orthogonal frequency division multiplexing (OFDMA) or space time stream resources (MIMO (multilple input multiple output) based). Information may be included).
- OFDMA orthogonal frequency division multiplexing
- MIMO multiple input multiple output
- the HE-STF 1240 may be used to improve automatic gain control estimation in a MIMO environment or an OFDMA environment.
- the HE-LTF 1250 may be used to estimate a channel in a MIMO environment or an OFDMA environment.
- the HE-SIG B 1260 may include information about a length MCS (modulation and coding scheme) of a physical layer service data unit (PSDU) for each STA, and tail bits.
- MCS modulation and coding scheme
- PSDU physical layer service data unit
- the size of the inverse fast fourier transform (IFFT) applied to the fields after the HE-STF 1240 and the HE-STF 1240 and the size of the IFFT applied to the field before the HE-STF 1240 may be different.
- the size of the IFFT applied to the field after the HE-STF 1240 and the HE-STF 1240 may be four times larger than the size of the IFFT applied to the field before the HE-STF 1240.
- the STA may be determined whether to decode the field.
- the STA is based on the FFT size changed from the fields after the HE-STF 1240 and the HE-STF 1240. Decoding can be performed.
- the STA may stop decoding and configure a network allocation vector (NAV).
- NAV network allocation vector
- the cyclic prefix (CP) of the HE-STF 1240 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.
- the order of the fields constituting the format of the PPDU disclosed at the top of FIG. 12 may vary.
- the HE-SIG B 1215 of the HE portion may be located immediately after the HE-SIG A 1205, as disclosed in the interruption of FIG. 12.
- the STA may decode up to the HE-SIG A 1205 and the HE-SIG B 1215, receive necessary control information, and make NAV settings.
- the size of the IFFT applied to the fields after the HE-STF 1225 and the HE-STF 1225 may be different from the size of the IFFT applied to the fields before the HE-STF 1225.
- the STA may receive the HE-SIG A 1205 and the HE-SIG B 1215.
- reception of the downlink PPDU is indicated by the identifier of the target STA of the HE-SIG A 1205
- the STA may perform decoding on the downlink PPDU by changing the FFT size from the HE-STF 1225.
- the STA may configure a network allocation vector (NAV).
- NAV network allocation vector
- a downlink PPDU format for downlink (DL) multi-user (MU) transmission is disclosed.
- the downlink PPDU may be transmitted to the STA through different downlink transmission resources (frequency resources or spatial streams) based on OFDMA. That is, downlink data may be transmitted to a plurality of STAs through a plurality of subbands based on a downlink PPDU format for DL MU transmission.
- the AP transmits a downlink frame including downlink data pending to one STA.
- downlink data may be transmitted in a downlink PPDU format for DL MU transmission to a plurality of STAs in an awake state.
- the previous field of the HE-SIG B 1245 on the downlink PPDU may be transmitted in a duplicated form in each of different downlink transmission resources.
- the HE-SIG B 1245 may be transmitted in encoded form on all transmission resources.
- the field after the HE-SIG B 1245 may include individual information for each of the plurality of STAs receiving the downlink PPDU.
- the CRC for each field may be included in the downlink PPDU.
- the CRC for each field may not be included in the downlink PPDU.
- the downlink PPDU format for DL MU transmission according to the embodiment of the present invention can reduce the CRC overhead of the downlink frame by using the HE-SIG B 1245 in the form of encoding on all transmission resources.
- the downlink PPDU format for DL MU transmission may be encoded based on an IFFT size different from that of the field before the HE-STF 1255 and the field after the HE-STF 1255. Accordingly, when the STA receives the HE-SIG A 1235 and the HE-SIG B 1245 and is instructed to receive the downlink PPDU based on the HE-SIG A 1235, the STA-STF 1255 is used. Decoding of the downlink PPDU may be performed by changing the FFT size.
- FIG. 13 is a block diagram illustrating a wireless device to which an embodiment of the present invention can be applied.
- the wireless device 1300 may be an STA that may implement the above-described embodiment and may be an AP 1300 or a non-AP station (or STA) 1350.
- the AP 1300 includes a processor 1310, a memory 1320, and an RF unit 1330.
- the RF unit 1330 may be connected to the processor 1310 to transmit / receive a radio signal.
- the processor 1310 may implement the functions, processes, and / or methods proposed in the present invention.
- the processor 1310 may be implemented to perform the operation of the wireless device according to the embodiment of the present invention described above.
- the processor may perform the operation of the wireless device disclosed in the embodiment of FIGS. 1 to 12.
- the processor 1310 may transmit a downlink frame including downlink data pending for the STA to the STA without receiving the PS-poll frame.
- the STA operates in the PS-poll mode
- the PS-poll frame is transmitted by the STA
- the downlink frame including the downlink data pending for the STA may be transmitted to the STA.
- the processor may transmit a non-PS-poll mode parameter set element for reception of the frame based on a timer (non-PS-poll mode timer) to the STA.
- the processor may include a non-PS-poll mode parameter set element including a non-PS-poll mode timer field, a signal to noise ratio (SNR) threshold field, and a mobility threshold field.
- SNR signal to noise ratio
- the non-PS-poll mode timer field includes information on an initial setting value of a timer
- the SNR threshold field includes information on a threshold value of an SNR for a reception operation of a timer-based frame of an STA
- a mobility threshold value may include information on a threshold of mobility for receiving a timer-based frame of the STA.
- the STA 1350 includes a processor 1360, a memory 1370, and an RF unit 1380.
- the RF unit 1380 may be connected to the processor 1360 to transmit / receive a radio signal.
- the processor 1360 may implement the functions, processes, and / or methods proposed in the present invention.
- the processor 1320 may be implemented to perform the operation of the wireless device according to the embodiment of the present invention described above.
- the processor may perform the operation of the wireless device in the embodiment of FIGS. 1 to 12.
- the processor 1360 may switch the operation mode of the STA from the sleep mode to the active mode based on the listening interval for receiving the first beacon frame transmitted by the access point (AP) after switching to the power save mode. If the first beacon frame indicates buffered data for the STA, monitor the frame for the STA transmitted by the AP until the expiration of the timer (non PS-poll mode timer) started at the time of transition to the active mode; After the timer expires, the operation mode of the STA may be switched to the sleep mode. The timer may be reset when the frame is transmitted.
- the timer non PS-poll mode timer
- the processor 1360 switches the operation mode from the sleep mode to the active mode to receive the second beacon frame transmitted by the AP based on the listening interval, and the second beacon frame indicates the buffered data for the STA.
- the power saving (PS) -poll frame is transmitted to the AP, the polled frame is monitored based on the PS-poll frame transmitted from the AP, and when the end of transmission of the polled frame is indicated, You can switch to sleep mode.
- the second beacon frame may be transmitted after the first beacon frame.
- the processor 1360 switches the operation mode from the sleep mode to the active mode to receive the third beacon frame transmitted by the AP based on the listening interval, and the third beacon frame indicates the buffered data for the STA. If so, it may be implemented to monitor the frame for the STA transmitted from the AP until expiration of the timer started at the time of switching to the active mode.
- the third beacon frame may be transmitted after the second beacon frame.
- Processors 1310 and 1360 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 1320 and 1370 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices.
- the RF unit 1330 and 1380 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 may be stored in the memories 1320 and 1370 and executed by the processors 1310 and 1360.
- the memories 1320 and 1370 may be inside or outside the processors 1310 and 1360, and may be connected to the processors 1310 and 1360 by various well-known means.
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Abstract
Description
Claims (10)
- 무선랜에서 파워 세이브 모드 기반의 동작 방법은,
STA(station)이 상기 파워 세이브 모드로 전환 후 AP(access point)에 의해 전송되는 제1 비콘 프레임의 수신을 위해 청취 인터벌을 기반으로 슬립 모드에서 액티브 모드로 전환되는 단계;
상기 제1 비콘 프레임이 상기 STA에 대해 버퍼된 데이터를 지시하는 경우, 상기 STA이 상기 액티브 모드로의 전환 시점에 시작된 타이머의 만료 전까지 상기 AP에 의해 전송되는 상기 STA에 대한 프레임을 모니터링하는 단계; 및
상기 STA이 상기 타이머의 만료 후에 상기 슬립 모드로 전환되는 단계를 포함하되,
상기 타이머는 상기 프레임이 전송되는 경우 리셋되는 방법. - 제1항에 있어서,
상기 STA이 상기 청취 인터벌을 기반으로 상기 AP에 의해 전송되는 제2 비콘 프레임의 수신을 위해 상기 슬립 모드에서 상기 액티브 모드로 전환되되, 상기 제2 비콘 프레임은 상기 제1 비콘 프레임 이후에 전송되는, 단계;
상기 제2 비콘 프레임이 상기 STA에 대해 버퍼된 데이터를 지시하는 경우, 상기 STA이 상기 AP로 PS(power saving)-poll 프레임을 전송하는 단계;
상기 STA이 상기 AP로부터 전송되는 상기 PS-poll 프레임에 기반하여 폴링된 프레임을 모니터링하는 단계;
상기 STA이 상기 폴링된 프레임의 전송의 종료가 지시되는 경우, 상기 슬립 모드로 전환되는 단계;
상기 STA이 상기 청취 인터벌을 기반으로 상기 AP에 의해 전송되는 제3 비콘 프레임의 수신을 위해 상기 슬립 모드에서 상기 액티브 모드로 전환되되, 상기 제3 비콘 프레임은 상기 제2 비콘 프레임 이후에 전송되는 단계; 및
상기 제3 비콘 프레임이 상기 STA에 대해 버퍼된 데이터를 지시하는 경우, 상기 STA이 상기 액티브 모드로의 전환 시점에 시작된 상기 타이머의 만료 전까지 상기 AP로부터 전송되는 상기 STA에 대한 프레임을 모니터링하는 단계를 더 포함하는 것을 특징으로 하는 방법. - 제1항에 있어서,
상기 STA은 상기 AP로부터 상기 타이머 기반의 상기 프레임의 수신을 위한 비 PS-poll 모드 파라메터 집합 요소를 수신하는 단계를 더 포함하고,
상기 비 PS-poll 모드 파라메터 집합 요소는 비 PS-poll 모드 타이머 필드를 포함하고,
상기 비 PS-poll 모드 타이머 필드는 상기 타이머의 초기 설정 값에 대한 정보를 포함하는 것을 특징으로 하는 방법. - 제3항에 있어서,
상기 초기 설정 값은 상기 청취 인터벌의 배수로 결정되는 것을 특징으로 하는 방법. - 제3항에 있어서,
상기 비 PS-poll 모드 파라메터 집합 요소는 SNR(signal to noise ratio) 임계값 필드, 이동성 임계값 필드를 더 포함하고,
상기 SNR 임계값 필드는 상기 STA의 상기 타이머 기반의 상기 프레임의 수신 동작을 위한 SNR의 임계값에 대한 정보를 포함하고,
상기 이동성 임계값 필드는 상기 STA의 상기 타이머 기반의 상기 프레임의 수신 동작을 위한 이동성의 임계값에 대한 정보를 포함하는 것을 특징으로 하는 방법. - 무선랜에서 파워 세이브 모드를 기반으로 동작하는 STA(station)에 있어서, 상기 STA는,
무선 신호를 송신 또는 수신하기 위해 구현된 RF(radio frequency)부; 및
상기 RF부와 동작 가능하도록(operatively) 연결되는 프로세서를 포함하되,
상기 프로세서는 상기 파워 세이브 모드로 전환 후 AP(access point)에 의해 전송되는 제1 비콘 프레임의 수신을 위해 청취 인터벌을 기반으로 상기 STA의 동작 모드를 슬립 모드에서 액티브 모드로 전환하고
상기 제1 비콘 프레임이 상기 STA에 대해 버퍼된 데이터를 지시하는 경우, 상기 액티브 모드로의 전환 시점에 시작된 타이머의 만료 전까지 상기 AP에 의해 전송되는 상기 STA에 대한 프레임을 모니터링하고,
상기 타이머의 만료 후에 상기 STA의 동작 모드를 상기 슬립 모드로 전환하도록 구현되되,
상기 타이머는 상기 프레임이 전송되는 경우 리셋되는 STA. - 제6항에 있어서,
상기 프로세서는 상기 청취 인터벌을 기반으로 상기 AP에 의해 전송되는 제2 비콘 프레임의 수신을 위해 상기 동작 모드를 상기 슬립 모드에서 상기 액티브 모드로 전환하고,
상기 제2 비콘 프레임이 상기 STA에 대해 버퍼된 데이터를 지시하는 경우, 상기 AP로 PS(power saving)-poll 프레임을 전송하고,
상기 AP로부터 전송되는 상기 PS-poll 프레임에 기반하여 폴링된 프레임을 모니터링하고,
상기 폴링된 프레임의 전송의 종료가 지시되는 경우, 상기 동작 모드를 상기 슬립 모드로 전환하고
상기 청취 인터벌을 기반으로 상기 AP에 의해 전송되는 제3 비콘 프레임의 수신을 위해 상기 동작 모드를 상기 슬립 모드에서 상기 액티브 모드로 전환하고,
상기 제3 비콘 프레임이 상기 STA에 대해 버퍼된 데이터를 지시하는 경우, 상기 액티브 모드로의 전환 시점에 시작된 상기 타이머의 만료 전까지 상기 AP로부터 전송되는 상기 STA에 대한 프레임을 모니터링하도록 구현되되,
상기 제2 비콘 프레임은 상기 제1 비콘 프레임 이후에 전송되고,
상기 제3 비콘 프레임은 상기 제2 비콘 프레임 이후에 전송되는 것을 특징으로 하는 STA. - 제6항에 있어서,
상기 프로세서는 상기 AP로부터 상기 타이머 기반의 상기 프레임의 수신을 위한 비 PS-poll 모드 파라메터 집합 요소를 수신하고,
상기 비 PS-poll 모드 파라메터 집합 요소는 비 PS-poll 모드 타이머 필드를 포함하고,
상기 비 PS-poll 모드 타이머 필드는 상기 타이머의 초기 설정 값에 대한 정보를 포함하는 것을 특징으로 하는 STA. - 제8항에 있어서,
상기 초기 설정 값은 상기 청취 인터벌의 배수로 결정되는 것을 특징으로 하는 STA. - 제8항에 있어서,
상기 비 PS-poll 모드 파라메터 집합 요소는 SNR(signal to noise ratio) 임계값 필드, 이동성 임계값 필드를 더 포함하고,
상기 SNR 임계값 필드는 상기 STA의 상기 타이머 기반의 상기 프레임의 수신 동작을 위한 SNR의 임계값에 대한 정보를 포함하고,
상기 이동성 임계값 필드는 상기 STA의 상기 타이머 기반의 상기 프레임의 수신 동작을 위한 이동성의 임계값에 대한 정보를 포함하는 것을 특징으로 하는 STA.
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