KR20150118887A - Method for low power communication in wireless local area network and apparatus for the same - Google Patents

Abstract

Disclosed are a method and an apparatus for low power communications in a wireless local area network (WLAN). The method for low power communications may comprise the following steps: receiving a capability notification frame including first capability-related information from a second station; and configuring a power saving mode of the first station based on the first capability-related information. According to the present invention, power consumption efficiency of a communications system can be enhanced.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for low power communication in a wireless LAN,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low power communication technology, and more particularly, to a low power communication method and apparatus in a wireless LAN.

With the development of information and communication technology, various wireless communication technologies are being developed. Among them, a wireless local area network (WLAN) may be a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), a smart phone A smart phone, a tablet PC, or the like, to wirelessly connect to the Internet in a home, an enterprise, or a specific service providing area.

The standard for wireless LAN technology is being developed as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The wireless LAN technology according to the IEEE 802.11a standard operates based on an orthogonal frequency division multiplexing (OFDM) scheme and can provide a transmission speed of up to 54 Mbps in the 5 GHz band. The wireless LAN technology according to the IEEE 802.11b standard operates based on a direct sequence spread spectrum (DSSS) scheme and can provide a transmission speed of up to 11 Mbps in the 2.4 GHz band. The wireless LAN technology according to the IEEE 802.11g standard operates based on the OFDM scheme or the DSSS scheme, and can provide a transmission speed of up to 54 Mbps in the 2.4 GHz band.

The wireless LAN technology according to the IEEE 802.11n standard operates in the 2.4 GHz band and the 5 GHz band based on the OFDM scheme. When using the multiple input multiple output (OFDM) and OFDM (MIMO-OFDM) spatial stream) at a transmission rate of up to 300 Mbps. According to the IEEE 802.11n standard, the wireless LAN technology can support a channel bandwidth of up to 40 MHz, which in this case can provide a transmission speed of up to 600 Mbps.

As the spread of the wireless LAN is activated and applications using the wireless LAN have been diversified, there is an increasing need for a new wireless LAN technology that supports higher throughput than the existing wireless LAN technology. Very high throughput (VHT) Wireless LAN technology is a proposed technology to support data rates of over 1Gbps. Among them, the wireless LAN technology according to the IEEE 802.11ac standard is a technology for providing an ultra high throughput in a band below 6 GHz, and the wireless LAN technology according to the IEEE 802.11ad standard is a technology for providing an ultra high throughput in a 60 GHz band.

In addition, standards for various wireless LAN technologies have been defined and technology development is under way. Typically, the wireless LAN technology according to the IEEE 802.11af standard is a technology defined for operation of a wireless LAN in a TV idle band, and the wireless LAN technology according to the IEEE 802.11ah standard operates at a low power in a band below 1 GHz The wireless LAN technology according to the IEEE 802.11ai standard is a technology defined for fast initial link setup (FILS) in a wireless LAN system. Recently, IEEE 802.11ax standardization for the purpose of improving frequency efficiency in a dense environment in which a plurality of base stations and terminals exist is proceeding.

Communication systems based on these wireless LAN technologies are introducing advanced wireless technologies to support high throughput and high quality services. In this case, in order to maintain interoperability with the existing wireless LAN standard, a circuit supporting the new wireless LAN standard needs to be added to the existing wireless LAN circuit, thereby increasing the wireless LAN circuit. Also, the power consumption of the communication system is rapidly increasing as the bandwidth to be supported increases, but the battery technology of the terminal does not show any rapid progress. In this technical background, the main power consumption source of the terminal can be regarded as a wireless LAN chipset.

Meanwhile, in a wireless LAN system, a terminal may operate in a doze mode based on a beacon frame to perform power saving. In this case, the terminal can reduce the power consumption by gating the power or clock of the entire circuit except the local timer. However, power saving is not considered in awake mode.

It is an object of the present invention to provide a method for performing low-power communication in a wireless LAN system.

It is another object of the present invention to provide an apparatus for performing low-power communication in a wireless LAN system.

According to another aspect of the present invention, there is provided a low power communication method performed in a first terminal, including: receiving a capability notification frame including first capability information from a second terminal; And setting a power saving mode of the first terminal based on the first capability information.

Here, the first capability related information may include at least one of capabilities of the second terminal and indicators indicating the capability information.

The capability information of the first terminal may include at least one of a wireless LAN standard version, an operation bandwidth, a center frequency, and band information supported by the second terminal.

Here, the power save mode of the first terminal may be set based on the capability information of the second terminal when the capability information of the second terminal includes the capability information of the first terminal .

Here, the low-power communication method may further include the step of transmitting a capability request frame including the second capability related information to the second terminal, wherein the capability notification frame includes the capability management request Frame. ≪ / RTI >

Here, the second capability information may include at least one of the capability information of the first terminal and the indicator indicating the capability information.

The capability information of the first terminal may include at least one of a wireless LAN standard version supported by the first terminal, an operation bandwidth, a center frequency, and band information.

Here, the power save mode of the second terminal may be set based on the capability information of the first terminal when the capability information of the first terminal is included in the second capability related information have.

If the second capability information does not include the capability information of the first terminal but includes an indicator indicating the capability information, the power save mode of the second terminal may include: And may be set based on the capacity of the second terminal.

Here, the power saving mode of the second terminal may be configured such that, when the capacity information of the first terminal is included in the second capacity related information, the power saving mode of the second terminal, May be set based on the capperity.

Here, the capability notification frame may be a CTS frame or a data frame.

Here, the capability request frame may be an RTS frame or a PS-Poll frame.

According to another aspect of the present invention, there is provided a low power communication method performed by a terminal, the method comprising: when receiving a data frame based on an OFDMA scheme from an access point, Calculating a reception ending point of the real data field based on information indicating a length of the real data field, and calculating a reception end time of the real data field based on information indicating a length of the real data field, And operating in a power save mode at a reception end time of the real data field if the data frame is before the reception end time point of the data frame.

Here, the information indicating the length of the substantial data field may be included in the SIGA field or the SIGB field of the data frame.

Here, the low power communication method may further include a step of operating in an awake mode at the end of reception of the data frame.

According to another aspect of the present invention, there is provided a low power communication terminal including a receiving unit receiving a frame and at least one of a power source and a clock provided to each of a plurality of components included in the receiving unit, And a power management unit for controlling each step.

Here, the power management unit may activate a component that performs carrier sensing among the plurality of components through at least one of a power source and a clock in a carrier sensing step before receiving the frame.

Here, when receiving the STF of the frame, the power management unit may activate a component that performs an operation based on the STF among the plurality of components through control of at least one of a power source and a clock.

Here, when receiving the LTF of the frame, the power management unit may activate the LTF-based component among the plurality of components through control of at least one of a power source and a clock.

Here, when receiving the SIG field of the frame, the power management unit may activate a component that performs an operation based on the SIG field among the plurality of components through at least one control of a power source and a clock.

Here, when the data field of the frame is received, the power management unit may activate a component that performs an operation based on the data field among the plurality of components through at least one control of a power source and a clock.

According to the present invention, the power consumption efficiency of the communication system can be improved.

1 is a conceptual diagram showing an embodiment of a configuration of a wireless LAN system according to the IEEE 802.11 standard.
2 is a flowchart illustrating a connection procedure of a terminal in an infrastructure BSS.
3 is a flowchart illustrating a frame transmission procedure according to the CSMA / CA scheme.
4 is a flowchart illustrating a frame transmission / reception procedure of a terminal operating in a power saving mode.
5 is a block diagram illustrating an embodiment of a terminal that performs methods in accordance with the present invention.
6 is a block diagram illustrating an exemplary embodiment of a receiving end of a terminal performing methods according to the present invention.
7 is a block diagram illustrating an embodiment of a power management unit of a terminal that performs methods according to the present invention.
FIG. 8 is a conceptual diagram for explaining a power saving method applied in each reception step of a legacy frame.
FIG. 9 is a conceptual diagram for explaining a power saving method applied in each reception step of a frame according to the IEEE 802.11n / ac standard.
FIG. 10 is a state transition diagram for explaining a power saving method applied to a receiving step of a frame according to the IEEE 802.11n / ac standard.
FIG. 11 is a conceptual diagram for explaining a power saving method applied in each frame receiving step according to the IEEE 802.11ax standard.
FIG. 12 is a state transition diagram for explaining a power saving method applied in each frame receiving step according to the IEEE 802.11ax standard.
13 is a flowchart illustrating a clock-based power saving method according to an embodiment of the present invention.
14 is a flowchart illustrating a power saving method based on capability information related information according to an embodiment of the present invention.
15 is a conceptual diagram illustrating an embodiment of a capability notification frame including the capability related information according to the present invention.
16 is a conceptual diagram showing another embodiment of a capability notification frame including the capability related information according to the present invention.
17 is a conceptual diagram showing another embodiment of a capability notification frame including the capability related information according to the present invention.
18 is a flowchart illustrating a power saving method based on capability information related information according to another embodiment of the present invention.
FIG. 19 is a conceptual diagram illustrating a power saving method based on capability information related information according to another embodiment of the present invention.
20 is a conceptual diagram for explaining a dynamic clock-based power saving method according to an embodiment of the present invention.
21 is a flowchart illustrating a power saving method for each terminal according to an embodiment of the present invention.
22 is a conceptual diagram showing an embodiment of a data frame including power saving information.
23 is a conceptual diagram showing another embodiment of a data frame including power saving information.
24 is a conceptual diagram showing another embodiment of a data frame including power saving information.
25 is a conceptual diagram for explaining a clock-based power saving method using a data frame including power saving information.
26 is a conceptual diagram for explaining a power saving method for each terminal according to another embodiment of the present invention.
27 is a flowchart illustrating a power saving method based on a WLAN standard supported by an access point according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Throughout the specification, a station is a physical layer for medium access control (MAC) and a medium access control (MAC) compliant with the IEEE 802.11 standard. Means any functional medium including an interface. A station (STA) can be divided into a station (STA) which is an access point (AP) and a station (STA) which is a non-AP. A station (STA), which is an access point (AP), may be referred to simply as an access point (AP), and a station (STA) that is a non-AP may be simply referred to as a terminal.

The station STA may include a processor and a transceiver, and may further include a user interface and a display device. A processor is a unit designed to generate a frame to be transmitted through a wireless network or to process a frame received through a wireless network, and may perform various functions for controlling the station (STA). A transceiver is a unit that is functionally connected to a processor and is designed to transmit and receive frames over a wireless network for a station (STA).

An access point (AP) includes a centralized controller, a base station (BS), a radio access station, a node B, an evolved node B, a relay, a multihop relay-BS, a base transceiver system (BTS), a site controller, and the like, and may include some or all of their functions.

A terminal (i.e., a non-access point) may comprise a wireless transmit / receive unit (WTRU), user equipment (UE), a user terminal (UT), an access terminal Refers to a mobile station (MS), a mobile terminal, a subscriber unit, a subscriber station (SS), a wireless device, or a mobile subscriber unit And may include some or all of their functions.

The terminal may be a desktop computer, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a smart phone, a smart watch, smart watch, smart glass, e-book reader, portable multimedia player (PMP), portable game machine, navigation device, digital camera, digital multimedia broadcasting (DMB) A digital audio recorder, a digital audio player, a digital picture recorder, a digital picture player, a digital video recorder, a digital video player ) And the like.

Embodiments of the present invention can be applied to a wireless LAN system conforming to the IEEE 802.11 standard, and can be applied to other communication systems as well as a wireless LAN system conforming to the IEEE 802.11 standard.

For example, embodiments of the present invention may be implemented in a portable Internet such as a wireless personal area network (WPAN), a wireless body area network (WBAN), a wireless broadband internet (WiBro) or a world interoperability for microwave access (WiMax) a 3G mobile communication network such as a wideband code division multiple access (WCDMA) or cdma10000, a high speed downlink packet access (HSDPA) or a high speed uplink (HSUPA) a 3.5G mobile communication network such as a packet access, a 4G mobile communication network such as LTE (Long Term Evolution) or LTE-Advanced, and a 5G mobile communication network.

1 is a conceptual diagram showing an embodiment of a configuration of a wireless LAN system according to the IEEE 802.11 standard.

Referring to FIG. 1, a WLAN system according to the IEEE 802.11 standard may include at least one basic service set (BSS). BSS means a set of stations (STA1, STA2 (AP1), STA3, STA4, STA5 (AP2), STA6, STA7, STA8) that can successfully communicate with each other and communicate with each other, .

The BSS can be divided into an infrastructure BSS (infrastructure BSS) and an independent BSS (IBSS). Here, BSS1 and BSS2 denote an infrastructure BSS, and BSS3 denotes an IBSS.

The BSS1 is a distribution system for connecting a first terminal STA1, a first access point STA2 (AP1) providing a distribution service and a plurality of access points STA2 (AP1), STA5 (AP2) distribution system, DS). In the BSS1, the first access point STA2 (AP1) can manage the first terminal STA1.

The BSS2 connects the third terminal STA3, the fourth terminal STA4, the second access point STA5 (AP2) providing the distribution service and the plurality of access points STA2 (AP1) and STA5 (AP2) And a distribution system (DS). The second access point STA5 (AP2) in the BSS2 can manage the third terminal STA3 and the fourth terminal STA4.

BSS3 means an IBSS operating in an ad-hoc mode. In BSS3, there is no access point which is a centralized management entity. That is, the terminals STA6, STA7, and STA8 in the BSS3 are managed in a distributed manner. In the BSS3, all terminals STA6, STA7, and STA8 may denote a mobile terminal and form a self-contained network since access is not permitted to the distribution system DS.

The access points STA2 (AP1) and STA5 (AP2) can provide a connection to the distributed system (DS) via a wireless medium for the terminals STA1, STA3 and STA4 connected thereto. The communication between the terminals STA1, STA3 and STA4 in the BSS1 or BSS2 is generally performed through the access points STA2 and STA5 and when the direct link is established, STA1, STA3, STA4) is possible.

A plurality of infrastructure BSSs may be interconnected via a distribution system (DS). A plurality of BSSs connected through a distribution system (DS) is referred to as an extended service set (ESS). (STA1, STA3, and STA4) in the same ESS can communicate with each other without interrupting the communication between the terminals (STA1, STA2, APA, STA3, STA4, From the BSS to another BSS.

The distribution system DS is a mechanism by which one access point communicates with another access point, whereby the access point transmits a frame for terminals coupled to the BSS it manages, or moves to another BSS A frame can be transmitted for an arbitrary terminal. The access point can also transmit and receive frames to and from an external network, such as a wired network. Such a distribution system (DS) does not necessarily have to be a network, and there is no restriction on the form if it can provide a predetermined distribution service defined in the IEEE 802.11 standard. For example, the distribution system may be a wireless network, such as a mesh network, or may be a physical structure that connects the access points to each other.

In the IEEE 802.11 standard, frames exchanged between stations are classified into a management frame, a control frame, and a data frame. A management frame is a frame used for exchange of management information that is not forwarded to an upper layer and may be an IFS (interframe) such as distributed coordination function interframe space (DIFS) or point coordination function interframe space (PIFS) space after a backoff procedure has been performed.

A control frame is a frame used to control access to a medium. The control frame is transmitted after the backoff procedure is performed after the lapse of the IFS when the frame is not the response frame of the other frame, and is transmitted without the backoff procedure after the short interframe space (SIFS) if the frame is a response frame of another frame.

A data frame is a frame used for transmission of data forwarded to an upper layer, and is transmitted after a backoff procedure is performed after an IFS has passed.

The type and subtype of a frame can be identified by a type field and a subtype field included in a control field of a frame. Table 1 below shows frames belonging to the management frame in the IEEE 802.11ac standard.

Table 2 below shows frames belonging to the control frame in the IEEE 802.11ac standard.

Table 3 below shows the frames belonging to the data frame and the reserved values in the IEEE 802.11ac standard.

In an intra-architecture BSS, a terminal (STA) may be associated with an access point (AP). The terminal STA can transmit and receive data when it is connected to an access point (AP).

2 is a flowchart illustrating a connection procedure of a terminal in an infrastructure BSS.

Referring to FIG. 2, the connection procedure of the STA in the infrastructure BSS includes a probe step for detecting an access point (AP), an authentication step for a detected access point (AP) And an association step with an access point (AP) that has performed the association process.

The terminal STA may first detect neighboring APs using a passive scanning method or an active scanning method. When using the passive scanning method, the terminal STA can detect neighboring APs by overhearing the beacon frame transmitted by the APs. When using the active scanning method, the terminal STA transmits a probe request frame and receives a probe response frame, which is a response to the probe request frame from the access points APs, It can detect one of the access points APs.

The terminal STA may perform an authentication step with a detected access point (AP) when it detects neighboring access points (APs). In this case, the terminal STA can perform the authentication step with a plurality of access points APs. The authentication algorithm according to the IEEE 802.11 standard can be classified into an open system algorithm for exchanging two authentication frames, a shared key algorithm for exchanging four authentication frames, and the like.

Based on the authentication algorithm according to the IEEE 802.11 standard, the terminal (STA) transmits an authentication request frame and receives an authentication response frame, which is a response to the authentication request frame, from the access point (AP) The authentication with the access point (AP) can be completed.

When the terminal STA has completed the authentication, the terminal STA can perform a connection step with the access point (AP). In this case, the terminal STA can select one of the access points (APs) that have performed the authentication step with the terminal STA, and can perform the connection step with the selected access point (AP). That is, the terminal STA transmits an association request frame to the selected access point (AP) and receives an association response frame, which is a response to the connection request frame, from the selected access point (AP) The connection with the selected access point (AP) can be completed.

A terminal (STA) connected to an access point (AP) can access a wireless channel based on a distributed coordination function (DCF) or enhanced DCF (EDCF). That is, the STA can access a wireless channel based on a carrier sense multiple access (CSMA) / collision avoidance (CA) scheme to avoid collision between frames in a wireless channel.

3 is a flowchart illustrating a frame transmission procedure according to the CSMA / CA scheme.

Referring to FIG. 3, a first STA1 refers to a transmitting terminal to transmit data, and a second terminal STA2 refers to a receiving terminal that receives data transmitted from the first terminal STA1. The third terminal STA3 may be located at a position capable of receiving a frame transmitted from the first terminal STA1 and / or a frame transmitted from the second terminal STA2.

The first terminal STA1 can determine whether a wireless channel is used through carrier sensing. The first STA1 can determine the occupation state of the wireless channel based on the amount of energy existing in the wireless channel or determine the occupancy state of the wireless channel using a NAV (network allocation vector) timer .

The first terminal STA1 may transmit a request to send (RTS) frame to the second terminal STA2 when it is determined that the wireless channel is not used by another terminal during a distributed (coordination function) interframe space (DIFS) . The second terminal STA2 may transmit a clear to send (CTS) frame, which is a response to the RTS frame, to the first terminal STA1 when receiving the RTS frame. In this case, the second terminal STA2 may transmit the CTS frame to the first terminal STA1 after the short interframe space (SIFS) from when the reception of the RTS frame is completed.

Meanwhile, when receiving the RTS frame, the third terminal STA3 transmits a frame transmission period (for example, SIFS + CTS frame + SIFS + data) continuously transmitted by using the duration information included in the RTS frame Frame + SIFS + acknowledgment (ACK) frame). Alternatively, when receiving the CTS frame, the third terminal STA3 may use the period information included in the CTS frame to transmit a frame transmission period (for example, SIFS + data frame + SIFS + ACK frame) You can set the NAV timer for. The third terminal STA3 may update the NAV timer using the period information included in the new frame when the new terminal receives the new frame before the expiration of the NAV timer. The third terminal STA3 does not attempt to connect to the wireless channel until the NAV timer expires.

When receiving the CTS frame, the first terminal STA1 may transmit the data frame to the second terminal STA2 after SIFS from the completion of reception of the CTS frame. When the second terminal STA2 successfully receives the data frame, the second terminal STA2 can transmit an ACK frame, which is a response to the data frame, to the first terminal STA1. In this case, the second terminal STA2 may transmit an ACK frame to the first terminal STA1 after SIFS from the completion of reception of the data frame.

The third terminal STA3 may determine whether the wireless channel is being used through carrier sensing when the NAV timer expires. The third terminal STA3 may attempt to access the wireless channel through a random backoff procedure when it is determined that the wireless channel is not used by another terminal during DIFS since the expiration of the NAV timer.

On the other hand, in the wireless LAN system, the mobile station can always operate in a wake state or operate in a power saving mode (PSM) (i.e., doze mode) for power saving.

4 is a flowchart illustrating a frame transmission / reception procedure of a terminal operating in a power saving mode.

Referring to FIG. 4, an access point (AP) may periodically broadcast beacon frames 400, 403, 404, 405, 406, 409 and may transmit DTIM and beacon frames 404 and 409 including a delivery traffic indication message. The terminals STA1 and STA2 operating in the power saving mode can periodically wake up to receive beacon frames 400, 403, 404, 405, 406 and 409 and beacon frames 400, 403, 404, 405, 406, It is possible to check whether data to be transmitted to itself through a traffic indication map (TIM) or DTIM included in the AP 409 is buffered in an access point (AP). If the buffered data exists in the access point AP, the terminals STA1 and STA2 can stay awake and receive data from the access point AP. If there is no buffered data, , STA2) can transition from the awake mode to the power saving mode.

That is, if the bit in the TIM corresponding to the association ID of its own is set to 1, the terminals STA1 and STA2 are in a power save (PS) state, which indicates that they are awake and ready to receive data, (Or a trigger frame) (401, 407) to an access point (AP). The access point AP can confirm that the terminals STA1 and STA2 are in a state capable of receiving data when receiving power save (PS) -Poll frames 401 and 407, (Or ACK frames) 402 and 408 to the base station. When the access point AP transmits the ACK frames 402 and 408 to the terminals STA1 and STA2 in response to the PS-Poll frames 401 and 407, the access point AP transmits data frames to the terminals STA1 and STA2 at appropriate times. Lt; / RTI > On the other hand, if the bit in the TIM corresponding to its own AID is set to 0, the terminals STA1 and STA2 can transition from the awake mode to the power saving mode.

5 is a block diagram illustrating an embodiment of a terminal that performs methods in accordance with the present invention.

Referring to FIG. 5, the terminal 500 may include a radio frequency (RF) transceiver 510 and a digital modem. The digital modem includes an analog-to-digital converter (ADC) 520, a carrier sensing unit 530, a physical layer (PHY) receiving unit 540, a media access control unit (MAC) 560, a physical layer transmitter 570, and a digital-to-analog converter (DAC) Here, each configuration included in the digital modem may mean a circuit that performs the corresponding function.

The physical layer receiving area may include an ADC 520, a carrier sensing unit 530, a physical layer receiving unit 540, and the like. The carrier sensing unit 530 may include at least one of a saturation based carrier sensing unit 531, a correlation based carrier sensing unit 532, and an energy based carrier sensing unit 533. [ Here, the saturation-based carrier sensing unit 531, the correlation-based carrier sensing unit 532, and the energy-based carrier sensing unit 533 will be described below with reference to FIG.

The physical layer receiving unit 540 includes a data path processing unit and a characterization unit 543 configured by a digital front-end (DFE) 541 and a digital back-end (DBE) 542, path processing unit 543. The DFE 541 may comprise a time domain full band DFE 541-1, at least one time domain sub band DFE 541-2 and a frequency domain full band DFE 541-3. Here, the time domain full band DFE 541-1, at least one time domain subband DFE 541-2, and the frequency domain full band DFE 541-3 will be described below with reference to FIG.

Although the carrier sensing unit 530 is shown separately from the DFE 541, the carrier sensing unit 530 may be included in the DFE 541 according to an embodiment. The physical layer transmission region may include a physical layer transmission unit 570, a DAC 580, and the like.

The power management unit 560 may control the clock (i.e., sampling rate) or power supply of each circuit included in the terminal 500. [ That is, the power management unit 560 can control the clock or power supply of the corresponding circuit by transmitting the power saving control signal xx_ps_ctrl to each circuit. For example, the power management unit 560 may activate or deactivate the carrier sensing unit 530 by transmitting the cs_ps_ctrl signal to the carrier sensing unit 530. [

Here, the rx_dp_ps_ctrl signal may be used to control the power saving operation of the data path processing unit, the rx_cp_ps_ctrl signal may be used to control the power saving operation of the characteristic path processing unit 543, and the phy_ps_ctrl signal may be used to control the power- Can be used to control the power saving operation of the layer transmission area.

Also, the mac_ps_ctrl signal may be used to control the power saving operation of the MAC 550, the tx_ps_ctrl signal may be used to control the power saving operation of the physical layer transmitter 570, and the adc_ps_ctrl signal may be used to control the power- The dac_ps_ctrl signal may be used to control the power saving operation of the DAC 580 and the rf_ps_ctrl signal may be used to control the power saving operation of the RF transceiver 510 . Also, the cs_done signal may mean an indicator indicating that a carrier has been detected.

The power management unit 560 can disable the circuit included in the physical layer reception region when the transmission mode is enabled, and inactivate the circuit included in the physical layer transmission region when the reception mode is enabled. The MAC 550 may control the power management unit 560 based on the power saving method supported by the MAC protocol.

In the case of transition to a power saving mode (i.e., doze mode) recognized by a beacon frame, the power management unit 560 controls the RF transceiver 510, the circuit included in the physical layer reception area, and the circuit included in the physical layer transmission area Can be deactivated. When transmitting a frame in the awake mode, the power management unit 560 can activate the circuit included in the physical layer transmission region and deactivate the circuit included in the physical layer reception region.

Conversely, when receiving a frame in the awake mode, the power management unit 560 can activate the circuit included in the physical layer reception region and deactivate the circuit included in the physical layer transmission region. However, the circuit included in the physical layer reception area always has to operate in a reception standby state because the frame is not known when it will be received, so that the circuit included in the physical layer reception area consumes a lot of power. Therefore, in order to solve this problem, there is a need for a power saving technique for improving the power consumption efficiency in the awake mode.

Embodiments of the present invention may be applied to a legacy terminal conforming to the IEEE 802.11a / b / g standard, a high throughput terminal conforming to the IEEE 802.11n standard, a very high throughput (VHT) terminal conforming to the IEEE 802.11ac standard, And can be applied to a high efficiency WLAN (HEW) terminal according to the 802.11ax standard.

6 is a block diagram illustrating an exemplary embodiment of a receiving end of a terminal performing methods according to the present invention.

6, the receiver of the terminal 500 includes an RF transceiver 510, an ADC 520, a saturation based carrier sensing unit 531, a correlation based carrier sensing unit 532, an energy based carrier sensing unit 533 A time domain full band DFE 541-1, at least one time domain subband DFE 541-2, a fast Fourier transform (FFT) performer 590, a frequency domain full band DFE 541-3, A DBE 542 and a MAC 550. Here, each configuration included in the receiving end of the terminal 500 may refer to a circuit that performs the corresponding function.

Meanwhile, in the communication system according to the IEEE 802.11ac standard, the terminal 500 can perform communication using the bandwidths of 20, 40, 80 and 160 MHz. Also, in the communication system according to the IEEE 802.11ax standard, the terminal 500 can perform communication using a wider bandwidth than the communication system according to the IEEE 802.11ac standard. The frame transmitted through each subband includes a preamble and can be structured to analyze the correlation, received power, time / frequency synchronization characteristic, etc. of each subband in units of 20 MHz bandwidth. Accordingly, the receiving end of the terminal 500 may include a time-domain subband DFE 541-2 for each subband to analyze the characteristics of each subband.

The RF transceiver 510 may receive an analog signal and may transmit the received analog signal to the ADC 520. [ The ADC 520 may convert the analog signal to a digital signal and may transmit the converted digital signal to the time domain full band DFE 541-1. The time domain full band DFE 541-1 and the time domain subband DFE 541-2 may be located before the FFT performing unit 590 in the DFE 541. [ The frequency domain full band DFE 541-3 of the DFE 541 may be located after the FFT performing unit 590. [

The time domain full band DFE 541-1 can process the entire band and includes a filter 541-1-1, an automatic gain control (AGC) 541-1-2, a digital A DC amplifier 541-1-4, an in-phase-quadrature phase (IQ) corrector 541-1-5, a buffer 541-1-5, (541-1-6), and the like.

The time domain subband DFE 541-2 includes a channel mixer 541-2-1, a signal characteristic analysis filter 541-2-2, a symbol synchronization detector 541-2-3 Correlation detecting unit 541-2-5, a clear channel assessment (CCA) detecting unit 541-2-6, an RSSI (received signal strength indication) detector 541-2-7, a carrier frequency offset (CFO) corrector 541-2-8, and the like.

The frequency domain full band DFE 541-3 includes a demapper 541-3-1, a phase tracking unit 541-3-2, a noise matching unit 541-3 -3), and the like.

The DBE 542 includes a channel equalizer 542-1, a deinterleaver 542-2, a deparser 542-3, a depuncture 542-4, A channel decoder 542-5, a descrambler 542-6, and the like. That is, after the channel compensation is performed, a deinterleaving process, a deparsing process, a depuncturing process, a decoding process, and a descrambling process are sequentially performed in the DBE 542 . Thereafter, the DBE 542 may send the descrambled signal to the MAC 550.

In the following, the signal processing procedure at the receiving end of the terminal 500 will be described in detail.

First, the RF transceiver 510 of the terminal 500 can receive a signal. The received signal can be amplified to an initial gain value, and the amplified signal can be demodulated. The ADC 520 of the terminal 500 can convert the demodulated signal into a digital signal and supplies the converted signal to the filter 541-1-1, the AGC 541-1-2, the saturation-based carrier sensing unit 531 or the like.

The saturation based carrier sensing unit 531 of the terminal 500 may determine that a signal exists in the channel when the signal is saturated in the RF transceiver unit 510 or the ADC 520. [ In other words, if the power of the saturation-based carrier sensing unit 531 of the terminal 500 is higher than a threshold value programmed by a serial to parallel interface (SPI) at the input or output terminal of the RF transceiver 510, . Alternatively, the saturation-based carrier sensing unit 531 of the terminal 500 may count a case where the output signal sample of the ADC 520 becomes equal to or greater than a predetermined threshold value, and if the counted result is a preset value , It can be determined that a signal exists in the channel.

After the carrier sensing is completed, the AGC 541-1-2 of the terminal 500 receives the RSSI from the ADC 520 based on the input signal size of the ADC 520 or the RSSI acquired from the RF transceiver 510 It is possible to perform automatic gain control to adjust the input signal size. The AGC 541-1-2 of the terminal 500 can perform the automatic gain control by controlling the gain of the RF amplifying unit or the digital amplifying unit 541-1-3.

The filter 541-1-1 of the terminal 500 may be composed of an analog filter or a digital filter, and the analog filter or the digital filter may filter the noise component of the gain-controlled signal. The DC removing unit 541-1-4 of the terminal 500 can remove the DC component that changes instantaneously simultaneously with the gain control. The IQ correcting section 541-1-5 of the terminal 500 can remove the IQ gain or phase error generated in the analog IQ path. The buffer 541-1-6 of the terminal 500 can correct the frequency error of the signal received from the IQ correcting unit 541-1-5.

On the other hand, the frequency error can be estimated using a short preamble and a long preamble. The demapper 541-3-1 of the terminal 500 can generate a subcarrier index by classifying the frequency domain signal into data subcarriers and pilot subcarriers. The subcarrier index can be used in the phase compensator 541-3-2 and the channel equalizer 542-1.

The phase compensator 541-3-2 of the UE 500 includes a circuit for compensating the residual frequency error by a pilot after the time domain frequency offset estimation, a circuit for estimating and compensating for the phase noise component by using the pilot, A circuit for compensating for the gain error, and the like. Residual frequency error estimation may be performed in the frequency domain and compensation may be performed in the time domain FFT input buffer. Other phase error compensation, timing error compensation, and gain error compensation can be performed in the frequency domain.

After the phase error is compensated for, the noise matching unit 541-3-3 of the terminal 500 can match the noise using the noise value calculated in the time domain. Channel compensation can then be performed.

On the other hand, in the time domain subband DFE 541-2, the channel mixer 541-2-1 of the terminal 500 can perform channel mixing for the entire band. The filter 541-2-2 of the terminal 500 can filter the mixed channel by a channel unit of 20MHz unit and analyze the frame characteristic received by the channel unit of 20MHz unit. The filter 541-2-2 of the terminal 500 can transmit the result of analyzing the frame characteristics to another circuit included in the terminal 500. [

The symbol synchronization detector 541-2-3 can obtain symbol synchronization for each filtered subband. The autocorrelation detecting unit 541-2-4 and the cross-correlation detecting unit 541-2-5 can obtain the signal correlation for each filtered subband. The CCA detection unit 541-2-6 can obtain the CCA for each filtered subband. The RSSI detecting unit 541-2-7 can obtain the RSSI for each filtered subband. The CFO correction unit 541-2-8 can perform CFO correction based on the autocorrelation obtained through the autocorrelation detection unit 541-2-4.

The symbol synchronization information obtained through the symbol synchronization detecting unit 541-2-3 may be transmitted to the input buffer of the FFT performing unit 590. [ The FFT performing unit 590 of the UE can confirm the starting point of the symbol using the symbol synchronization information. In addition, the FFT performing unit 590 of the terminal may convert the signal received from the buffer 541-1-6 into a frequency domain signal by performing FFT.

The correlation-based carrier sensing unit 532 performs carrier sensing based on the cross-correlation obtained through the autocorrelation and cross-correlation detector 541-2-5 obtained through the autocorrelation detector 541-2-4 . That is, the correlation-based carrier sensing unit 532 can calculate the autocorrelation or cross-correlation using the periodicity of the preamble, and can determine that a signal exists in the channel when the calculated correlation is higher than a preset threshold value .

 The energy-based carrier sensing unit 533 may perform carrier sensing based on the RSSI acquired through the RSSI detecting unit 541-2-7. That is, the energy-based carrier sensing unit 533 may determine that a signal exists in the channel when an energy greater than a threshold value set in a programmable register is detected.

Meanwhile, in the DBE 542, a deinterleaving process, a de-parsing process, a de-puncturing process, a channel decoding process, and a descrambling process can be performed as opposed to a process performed at a transmitting end. Channel estimation can be performed through the channel equalizer 542-1. The deinterleaver 542-2 can perform deinterleaving on the signal received from the channel equalizer 542-1. The de-parser 542-3 can perform de-parsing on the signal received from the de-interleaver 542-2. The de-puncturer 542-4 can perform a de-puncturing on the signal received from the de-parser 542-3.

The channel decoder 542-5 may perform decoding on the signal received from the de-punisher 542-4. The channel decoder 542-5 may be a viterbi decoder, a low density parity check (LDPC) decoder, or the like. The information of the currently operating channel decoder 542-5 may be conveyed via the SIG (SIG) field included in the frame. The descrambler 542-6 can perform descrambling on the signal received from the channel decoder 542-5. The signal having undergone the above process can be transmitted to the MAC 550 in a first in first out (FIFO) manner.

7 is a block diagram illustrating an embodiment of a power management unit of a terminal that performs methods according to the present invention.

7, the power management unit 560 of the terminal 500 may include a control unit 561, a clock generation unit 562, and a power supply unit 563. The control unit 561 can improve the power consumption efficiency by activating only some of the circuits and deactivating other circuits according to the reception step of the frame. The control unit 561 can activate or deactivate the circuit through clock gating and power gating. The power consumption can be expressed by the following equation.

Where P denotes power consumption, P _s denotes static power consumption, and P _d denotes dynamic power consumption. Static power consumption is determined by the chip process and layout, and most of it occurs even if the chip is not driven in the form of leakage power.

Also, C means the gate size (i.e., the size of the circuit to be driven), f means the clock of the circuit, and V means the power applied to the circuit. Dynamic power consumption is proportional to C, f, V ^2. Here, reducing the power applied to the circuit is very difficult and limited by the process used, so it is effective to control C and f to reduce the total power consumption. That is, since all the circuits included in the terminal 500 need not be activated and a high clock is not always used, dynamic power consumption can be minimized when C and f are optimized for a given environment.

Hereinafter, embodiments of the power saving method applied to the reception step of the frame of the wireless LAN system in the awake mode will be briefly described with reference to Figs. 8 to 12. Fig. Embodiments of the power saving method may be implemented independently of each other, or two or more embodiments may be implemented in combination, or some or all of the technical elements constituting each embodiment may be implemented as part of another embodiment May be implemented in combination with all of the technical elements.

FIG. 8 is a conceptual diagram for explaining a power saving method applied in each reception step of a legacy frame.

Referring to FIG. 8, the legacy frame may include a legacy-short training field (L-STF), a legacy-long training field (L-LTF), a legacy-signal (L-SIG) field and a data field. Here, the legacy frame may refer to a frame conforming to the IEEE 802.11a / b / g standard.

The power management unit 560 of the terminal 500 can determine the clock based on the WLAN standard version supported by the access point connected to the terminal 500, the operation bandwidth, the center frequency, and the band information. That is, the power management unit 560 of the terminal 500 can determine that the clock is twice (or twice or more) the frequency of the bandwidth (that is, the operation bandwidth) at which the access point operates. The power management unit 560 of the terminal 500 can set the determined clock in the circuit included in the terminal 500. [

When the setting of the clock is completed, the carrier sensing can be performed. In the carrier sensing state, the power management unit 560 of the terminal 500 selects one of the circuits included in the terminal 500, that is, the carrier sensing unit 530 (that is, the saturation based carrier sensing unit 531 ), The correlation-based carrier sensing unit 532, and the energy-based carrier sensing unit 533), and may deactivate the remaining circuits.

Specifically, in order to activate the correlation-based carrier sensing unit 532, which is one of the main circuits corresponding to the carrier sensing state, and to support the normal operation of the correlation-based carrier sensing unit 532, the power management unit 560 ) Includes an RF transmitting / receiving unit 510, an ADC 520, a filter 541-1-1, a digital amplifying unit 542-1, and the like, which are components on the path starting from the RF transmitting / receiving unit 510 to the correlation based carrier sensing unit 532. [ The DC demultiplexer 541-1-4, the channel mixer 541-2-1, the filter 541-2-2, the auto-correlation detector 541-2-4, Based carrier sensing section 532 and the like.

For power saving, the power management unit 560 of the terminal 500 may deactivate at least one of the components not belonging to the path. Hereinafter, activating a component corresponding to a specific state may mean activating components on a path from the RF transceiver 510 to a component corresponding to a specific state. Also, deactivating the remainder of a component corresponding to a particular state may mean deactivating at least one of the remaining components not belonging to that path.

The carrier sensing unit 530 of the terminal 500 can determine whether there is a signal in the channel through carrier sensing. That is, the carrier sensing unit 530 of the terminal 500 can determine whether there is a signal in the channel by sensing the L-STF of the frame. The carrier sensing unit 530 of the terminal 500 can continue carrier sensing when there is no signal in the channel (i.e., in the idle state).

If it is determined that a signal exists in the channel, gain control for the detected signal can be performed. In the gain control state, the power management unit 560 of the terminal 500 can activate the AGC 541-1-2, which is a circuit for controlling gain among the circuits included in the terminal 500, Can be disabled. The AGC 541-1-2 of the terminal 500 can measure the magnitude of the input signal based on the L-STF of the frame and calculate the gain of the input signal based on the measured result, .

When the gain control is completed, the parameter value associated with the gain control value may be stored in the register, and the power management unit 560 of the terminal 500 may deactivate the AGC 541-1-2. On the other hand, if the gain control fails (that is, the gain control can not be completed within a predetermined time), the gain control state may be shifted to the carrier sensing state. That is, the power management unit 560 of the terminal 500 may deactivate the AGC 541-1-2 and activate the carrier sensing unit 530. [

If the gain control is complete, a coarse CFO correction for the gain controlled signal can be performed. In the coarse CFO correction state, the power management unit 560 of the terminal 500 can activate the CFO correction unit 541-2-8, which is a circuit for performing coarse CFO correction among the circuits included in the terminal 500 , Circuits that are not involved in coarse CFO correction can be deactivated. The CFO correction unit 541-2-8 of the terminal 500 can roughly correct the carrier frequency offset based on the L-STF of the frame.

When the coarse CFO correction is completed, the power management unit 560 of the terminal 500 may deactivate the CFO correction unit 541-2-8. On the other hand, if the coarse CFO correction fails (i.e., the coarse CFO correction is not completed within a predetermined time), the coarse CFO correction state may transition to the carrier sensing state. That is, the power management unit 560 of the terminal 500 may deactivate the CFO correction unit 541-2-8 and activate the carrier sensing unit 530. [

If coarse CFO correction is complete, symbol synchronous detection of the coarse CFO corrected signal may be performed. In the symbol synchronization detection state, the power management unit 560 of the terminal 500 can activate the symbol synchronization detection unit 541-2-3, which is a circuit for performing symbol synchronization detection among the circuits included in the terminal 500 , It is possible to deactivate circuits not involved in symbol synchronization detection. The symbol synchronization detector 541-2-3 of the terminal 500 can estimate the L-STF ending point of the frame, and based on the end point of the L-STF, the symbol synchronization detector 541-2-3 of the terminal 500 detects a guard interval Can be estimated.

When the symbol synchronization detection is completed, the power management unit 560 of the terminal 500 may deactivate the symbol synchronization detection unit 541-2-3. On the other hand, when symbol synchronization detection fails (that is, symbol synchronization detection is not completed within a predetermined time), the symbol synchronization detection state can be shifted to the carrier sensing state. That is, the power management unit 560 of the terminal 500 may deactivate the symbol synchronization detection unit 541-2-3 and activate the carrier sensing unit 530. [

When symbol synchronization detection is completed, fine CFO correction can be performed. In the fine CFO correction state, the power management unit 560 of the terminal 500 can activate the CFO correction unit 541-2-8, which is a circuit for performing fine CFO correction among the circuits included in the terminal 500 , It is possible to deactivate circuits that are not involved in fine CFO correction. The CFO correction unit 541-2-8 of the terminal 500 can precisely correct the carrier frequency offset based on the L-LTF of the frame.

When finer CFO correction is completed, the power management unit 560 of the terminal 500 can deactivate the CFO correction unit 541-2-8. On the other hand, if the detailed CFO correction fails (that is, the detailed CFO correction is not completed within a predetermined time), the fine CFO correction state can be shifted to the carrier sensing state. That is, the power management unit 560 of the terminal 500 may deactivate the CFO correction unit 541-2-8 and activate the carrier sensing unit 530. [

When fine CFO correction is completed, channel estimation can be performed. In the channel estimation state, the power management unit 560 of the terminal 500 can activate the channel equalizer 542-1, which is a circuit for performing channel estimation among the circuits included in the terminal 500, You can deactivate non-involved circuits. The channel equalizer 542-1 of the UE 500 can estimate the channel state based on the L-LTF of the frame and estimate the signal to noise ratio (SNR) based on the estimated channel state. The estimated channel state may be used for decoding the L-SIG field included in the frame.

When the channel estimation is completed, decoding of the L-SIG field can be performed. In the decoding state of the L-SIG field, the power management unit 560 of the terminal 500 can activate the channel decoder 542-5, which is a circuit that performs decoding among the circuits included in the terminal 500, Can be deactivated. The channel decoder 542-5 of the terminal 500 can compare the SNR estimated based on the channel quality and the link quality required according to the frame length and rate information obtained from the L-SIG field.

If the link quality is determined to be impossible to decode (i.e., the link quality is equal to or greater than the SNR) as a result of the comparison of the link quality and the SNR, the power management unit 560 of the terminal 500 adds the frame length and rate information acquired from the L- All the circuits included in the receiver can be deactivated during the estimated frame transmission time (i.e., the RX power saving state). When the frame transmission time is terminated, the power management unit 560 of the terminal 500 can activate the carrier sensing unit 530 (i.e., the carrier sensing state). On the other hand, when it is determined that decoding is possible as a result of the comparison of the link quality and the SNR (i.e., the link quality is lower than the SNR), the channel decoder 542-5 can decode the L-SIG field.

Compensation of the phase error can be performed after decoding of the L-SIG field. In the phase error compensation state, the power management unit 560 of the terminal 500 can activate the phase compensation unit 541-3-2, which is a circuit for compensating the phase error among the circuits included in the terminal 500 And can disable circuits that are not involved in phase error compensation. The phase compensator 541-3-2 of the terminal 500 can estimate the phase error and compensate the estimated error. When the loop filter for phase error compensation is stabilized, the power management unit 560 of the terminal 500 may deactivate the phase compensation unit 541-3-2.

The inactivation period of the phase compensator 541-3-2 may vary depending on the length of the frame. For example, the power management unit 560 of the terminal 500 may deactivate the phase compensation unit 541-3-2 until the end of frame reception when the frame is shorter than a predetermined length. On the other hand, the power management unit 560 of the terminal 500 may control the phase compensation unit 541-3-2 to periodically estimate and compensate for the phase error when the frame is longer than a predetermined length.

After decoding of the L-SIG field, decoding of the data field may be performed. In the decoding state of the data field, the MAC 550 of the terminal 500 can decode the data field. When the decoding of the data field is completed, the power management unit 560 of the terminal 500 can activate the carrier sensing unit 530.

FIG. 9 is a conceptual diagram for explaining a power saving method applied to each frame in accordance with the IEEE 802.11n / ac standard. FIG. 10 illustrates a power saving method applied to each frame in accordance with the IEEE 802.11n / ac standard And Fig.

9 and 10, a frame according to the IEEE 802.11n standard includes an L-STF, an L-LTF, an L-SIG field, a high throughput-signal A (HT-SIGA) training field, a high throughput-long training field (HT-LTF), a high throughput-signal B (HT-SIGB) field, and a data field. The frame according to the IEEE 802.11ac standard includes a L-STF, an L-LTF, an L-SIG field, a VHT-SIGA (very high throughput-signal A) field, a VHT- a very high throughput-signal B field, a VHT-SIGB field, and a data field.

A coarse CFO correction state 1003, a detailed symbol synchronization detection state 1004, a fine CFO correction state 1005, a channel estimation state 1006, and a channel estimation state 1006. The clock decision state 1000, the carrier sensing state 1001, the gain control state 1002, , The operation of the power management unit 560 of the terminal 500 and the operation of the circuit controlled by the power management unit 560 in the L-SIG field decoding state 1007 are the same as the operations in each state described with reference to Fig. 8 can do.

When decoding of the L-SIG field is completed, decoding of the HT-SIGA field (or VHT-SIGA field) may be performed. In the decoding state 1008 of the HT-SIGA field (or the VHT-SIGA field), the channel decoder 542-5 of the UE 500 receives the modulation and / coding scheme, frame length, and transmission mode.

The channel decoder 542-5 of the terminal 500 can determine the channel quality of the received signal based on the estimated link quality (i.e., the link quality required for reception of a successful frame based on the length of the received frame, the bandwidth, the standard version, The estimated SNR can be compared. If the link quality is equal to or greater than the SNR, the power management unit 560 of the terminal 500 may deactivate all the circuits included in the receiver during the estimated frame transmission period (i.e., the RX power saving state 1009). When the frame transmission period is terminated, the power management unit 560 of the terminal 500 can activate the carrier sensing unit 530 (i.e., the carrier sensing state 1001).

Also, when a CRC error occurs as a result of decoding of the HT-SIGA field (or VHT-SIGA field), the decoding state 1008 of the HT-SIGA field (or VHT-SIGA field) may be transited to the carrier sensing state 1001 have. That is, the power management unit 560 of the terminal 500 may deactivate the channel decoder 542-5 and activate the carrier sensing unit 530. [ On the other hand, if the required link quality is lower than the SNR, the channel decoder 542-5 may decode the HT-SIGA field (or VHT-SIGA field) and the data field.

When decoding of the HT-SIGA field (or VHT-SIGA field) is completed, fine gain control can be performed. In the fine gain control state 1010, the power management unit 560 of the terminal 500 can activate the AGC 541-1-2, which is a circuit for performing fine gain control among the circuits included in the terminal 500 And deactivate circuits that are not involved in fine gain control. The AGC 541-1-2 of the terminal 500 can finely control the gain based on the HT-STF (or VHT-STF). In the case of a beamforming signal, the AGC 541-1-2 of the UE 500 can compensate for the gain difference of the beamforming signal because the gain can be greatly changed. When fine gain control is completed, the power management unit 560 of the terminal 500 can deactivate the AGC 541-1-2.

Channel estimation can be performed after fine gain control. In the channel estimation state 1011, the power management unit 560 of the terminal 500 can activate the channel equalizer 542-1, which is a circuit for performing channel estimation among the circuits included in the terminal 500, It is possible to deactivate circuits that are not involved in channel estimation. The channel equalizer 542-1 of the terminal 500 can estimate the channel based on the HT-LTF (or VHT-LTF). When the channel estimation is completed, the power management unit 560 of the terminal 500 may deactivate the channel equalizer 542-1. Also, the power management unit 560 of the terminal 500 may deactivate all of the circuits for extracting the signal characteristics of the subband unit after receiving the HT-LTF (or VHT-LTF).

After the channel estimation, decoding of the HT-SIGB field (or VHT-SIGB field) may be performed. In the decoding state 1012 of the HT-SIGB field (or the VHT-SIGB field), the power management unit 560 of the terminal 500 includes a channel decoder 542-5, which is a circuit that performs decoding among the circuits included in the terminal, And disable circuits that are not involved in decoding. The channel decoder 542-5 of the terminal 500 may decode the HT-SIGB field (or the VHT-SIGB field). When the decoding of the HT-SIGB field (or the VHT-SIGB field) is completed, the power management unit 560 of the terminal 500 may deactivate the channel decoder 542-5.

Compensation of the phase error can be performed after decoding of the HT-SIGB field (or VHT-SIGB field). In the phase error compensation state, the power management unit 560 of the terminal 500 can activate the phase compensation unit 541-3-2, which is a circuit for compensating the phase error among the circuits included in the terminal 500 have. The phase compensator 541-3-2 of the terminal 500 can estimate the phase error and compensate the estimated error. When the loop filter for phase error compensation is stabilized, the power management unit 560 of the terminal 500 may deactivate the phase compensation unit 541-3-2.

The inactivation period of the phase compensator 541-3-2 may vary depending on the length of the frame. For example, the power management unit 560 of the terminal 500 may deactivate the phase compensation unit 541-3-2 until the end of transmission of the frame if the frame is shorter than a predetermined length. On the other hand, the power management unit 560 of the terminal 500 may control the phase compensation unit 541-3-2 to periodically estimate and compensate for the phase error when the frame is longer than a predetermined length.

After decoding of the HT-SIGB field (or VHT-SIGB field), decoding of the data field may be performed. In the decoding state 1013 of the data field, the MAC 550 of the terminal 500 may decode the data field. When the decoding of the data field is completed, the power management unit 560 of the terminal 500 can activate the carrier sensing unit 530.

FIG. 11 is a conceptual diagram for explaining a power saving method applied to each frame in accordance with the IEEE 802.11ax standard, FIG. 12 is a diagram for explaining a power saving method applied to each frame in accordance with the IEEE 802.11ax standard, It is a transition.

11 and 12, a frame according to the IEEE 802.11ax standard includes an L-STF, an L-LTF, an L-SIG field, a HEW-SIGA field, a HEW- STF, a HEW- . ≪ / RTI > The HEW-SIGA field, the HEW-STF, the HEW-LTF and the HEW-SIGB fields may refer to fields specified for a communication system according to the IEEE 802.11ax standard.

The power saving method based on the L-STF, the L-LTF, the L-SIG field, the HEW-SIGA field, the HEW-STF, the HEW-LTF and the HEW- May be the same as the power saving method described with reference to FIG. That is, the HEW-SIGA field corresponds to the HT-SIGA field (or the VHT-SIGA field), the HEW-STF corresponds to the HT-STF (or VHT- STF) LTF), and the HEW-SIGB field corresponds to the HT-SIGB field (or the VHT-SIGB field).

In the following, details of embodiments of the power saving method described above will be described. The power saving method is largely divided into a clock-based power saving method, a power saving method by adjusting the gate size (i.e., the size of the driven circuit) of the receiving step of the frame, the orthogonal frequency division multiple access (OFDMA) a power saving method in a multiple input multiple output (WDM) transmission environment, and a power saving method according to a wireless LAN standard supported by an access point.

In the following, a clock-based power saving method will be described.

The power management unit 560 of the terminal 500 that accesses and communicates with the access point receives a standard version (e.g., IEEE 802.11a / b / g / n / ac / ax) supported by the access point, When the operating bandwidth, center frequency, and band information are known, a clock can be set based on the information.

For example, when accessing an access point according to the IEEE 802.11n standard, the terminal 500 according to the IEEE 802.11ac standard does not need to support the 80 MHz bandwidth because the access point operates with a bandwidth of 20 MHz or a bandwidth of 40 MHz. Therefore, the power management unit 560 of the terminal 500 according to the IEEE 802.11ac standard can determine the clock based on the 40 MHz bandwidth instead of the 80 MHz bandwidth, and can set the determined clock in the circuit included in the terminal 500. Here, the clock set by the power management unit 560 may denote a nyquist frequency, and may be oversampled according to an implementation. In this way, the power management unit 560 of the terminal 500 can increase the power consumption efficiency by setting the clock based on the operation bandwidth of the access point.

Table 4 below shows the operating bandwidth and the clock set based on the WLAN standard.

When the access point operates at a bandwidth of 20 MHz, since the operation bandwidth is 20 MHz, the terminal 500 according to the IEEE 802.11a / n / ac standard can set the clock to 40 MHz, which is twice the operation bandwidth. When the access point operates at a bandwidth of 40 MHz, since the operation bandwidth is 40 MHz, the terminal 500 according to the IEEE 802.11n / ac standard can set the clock at 80 MHz which is twice the operation bandwidth. Meanwhile, since the terminal 500 according to the IEEE 802.11a standard does not support a 40 MHz bandwidth, it is not possible to set a clock for a 40 MHz bandwidth.

When the access point operates at a bandwidth of 80 MHz, since the operation bandwidth is 80 MHz, the terminal 500 according to the IEEE 802.11ac standard can set a clock at 160 MHz which is twice the operation bandwidth. Meanwhile, since the terminal 500 according to the IEEE 802.11a / n standard does not support the 80 MHz bandwidth, the clock for the 80 MHz bandwidth can not be set. When the access point operates at a bandwidth of 160 MHz, since the operation bandwidth is 160 MHz, the terminal 500 according to the IEEE 802.11ac standard can set the clock at 320 MHz, which is twice the operation bandwidth. Meanwhile, since the terminal 500 according to the IEEE 802.11a / n standard does not support the 160 MHz bandwidth, it can not set a clock for the 160 MHz bandwidth.

The access point and the terminal 500 according to the IEEE 802.11ax standard can support a wider bandwidth. For example, when the access point operates at a bandwidth of 320 MHz, the operation bandwidth is 320 MHz, so that the terminal 500 can set the clock at 640 MHz, which is double the operation bandwidth.

In the following, a power saving method based on notification of capacity-related information among clock-based power saving methods will be described. The power saving methods based on the notification of the capability related information can be roughly classified into three types.

The first method is to acquire the capability information of the UE through the exchange of a capability request frame / capability notification frame between the UEs. Here, the capability notification frame is a response to the capability request frame, and the capability related information can be included in the capability notification frame. A specific embodiment of the first method will be described below with reference to FIG.

The second method is to acquire the capability information of the terminal through the capability notification frame. Here, the capability related information may be included in the capability notification frame. The second method differs from the first method in that it acquires the capability information of the UE only by exchanging the capability notification frame without exchanging the capability request frame. A specific embodiment of the second method will be described below with reference to Figs. 14 to 17. Fig.

The third method is to acquire the capability information of the UE through the exchange of the Capabilityity Request Frame / Capability Notification Frame among the UEs. Here, the capability notification frame is a response to the capability request frame, and the capability related information can be included in both the capability request frame and the capability notification frame. The third method differs from the first method in that both the Capability Request Frame and the Capability Notice Frame contain information about the Capability. A specific embodiment of the third method will be described below with reference to FIGS. 18 and 19. FIG.

Here, the capability related information may include at least one of the capability information of the terminal and the indicator indicating the capability information. The capability information of the terminal may include at least one of a standard version, an operation bandwidth, a center frequency, and band information supported by the terminal.

13 is a flowchart illustrating a clock-based power saving method according to an embodiment of the present invention.

Referring to FIG. 13, the first terminal STA 1 may denote an AP or a non-AP, and the second terminal STA 2 may denote an AP or a non-AP. The first terminal STA 1 may generate a capability request frame requesting the capability information of the second terminal STA 2 and may transmit the generated capability order frame to the second terminal STA 2, 2) (S1300).

The second terminal STA2 can generate a capability notification frame including the capability related information when the second terminal STA2 receives the capability request frame. The capability related information may include the capability information of the second terminal STA2. The capability information of the second terminal STA 2 may be a wireless LAN standard version supported by the second terminal STA 2 (for example, IEEE 802.11a / b / g / n / ac / , 40 MHz, 80 MHz, etc.), center frequency and band information. Here, the band information may indicate which band is used among a plurality of bands, and may be expressed in a bitmap form or an index form. The second terminal STA 2 may transmit the capability notification frame including the capability related information to the first terminal STA 1 (S 1310).

When the first terminal STA 1 receives the capability notification frame in response to the capability request frame, the first terminal STA 1 can set the clock based on the information included in the capability notification frame (S 1320) . That is, the first terminal STA 1 transmits the information included in the capability announcement frame (i.e., the WLAN standard version, the operation bandwidth, the center frequency, and the band information supported by the second terminal STA 2) The bandwidth at which the second terminal STA 2 operates can be known. The first terminal STA 1 can determine that the operating bandwidth of the second terminal STA 2 is twice the clock. The first terminal STA 1 may set the determined clock to the circuits included therein. Here, the process of setting the clock may be performed by the power management unit 560 of the first terminal STA 1.

Thereafter, the second terminal STA 1 can receive the frame from the second terminal STA 2 based on the set clock.

14 is a flowchart illustrating a power saving method based on capability information related information according to an embodiment of the present invention.

Referring to FIG. 14, the first STA 1 may denote an AP or a non-AP, and the second STA 2 may denote an AP or a non-AP. The second terminal STA2 may generate a capability notification frame including the capability related information (S1400). Here, the capability related information may include the capability information of the second terminal STA2.

The capability information of the second terminal STA 2 may include at least one of a wireless LAN standard version supported by the second terminal STA 2, an operation bandwidth, a center frequency, and band information. Here, the band information may indicate which band is used among a plurality of bands, and may be expressed in a bitmap form or an index form. The capability announcement frame may refer to a data frame, a management frame, or a control frame according to the IEEE 802.11 standard. The first terminal STA 1 may transmit the capability announcement frame including the capability related information to the first terminal STA 1 (S 1410).

In the following, the structure of the capability notification frame including the capability related information will be described.

15 is a conceptual diagram illustrating an embodiment of a capability notification frame including the capability related information according to the present invention.

Referring to FIG. 15, a frame for a legacy terminal may include an L-STF, an L-LTF, an L-SIG field, and a data field. The second terminal STA 2 may set the capability related information in the data field of the frame for the legacy terminal.

FIG. 16 is a conceptual view showing another embodiment of the capability notification frame including the capability related information according to the present invention, and FIG. 17 is a schematic view of a capabilty information frame Fig. 8 is a conceptual diagram showing another embodiment of the notification frame.

16 and 17, a frame according to the IEEE 802.11ax standard includes L-STF, L-LTF, L-SIG, HEW-SIGA field, HEW-STF, HEW-LTF, HEW- . Here, the HEW-SIGA field, the HEW-STF, the HEW-LTF, and the HEW-SIGB field may be fields specified for the communication system according to the IEEE 802.11ax standard. The second terminal STA2 may set the capability related information in the data field of the frame conforming to the IEEE 802.11ax standard. Alternatively, the second terminal STA 2 may set the capability-related information in a SIG field (for example, HEW-SIGA or HEW-SIGB) of a frame conforming to the IEEE 802.11ax standard.

Referring again to FIG. 14, when the first terminal STA 1 receives the capability notification frame including the capability related information from the second terminal STA 2, the first terminal STA 1 includes the capability information in the capacity notification frame And the clock can be set based on the capacity-related information (S1420). That is, the first terminal STA 1 transmits the capability information of the second terminal STA 2 included in the capability related information (i.e., the standard version of the wireless LAN supported by the second terminal STA 2, The center frequency, and the band information) of the second terminal STA 2.

The first terminal STA 1 can determine that the operating bandwidth of the second terminal STA 2 is twice the clock. The first terminal STA 1 may set the determined clock to the circuits included therein. Here, the process of setting the clock may be performed by the power management unit 560 of the first terminal STA 1. Thereafter, the circuits included in the first terminal STA 1 may operate based on the set clock.

FIG. 18 is a flowchart illustrating a power saving method based on capability information-related information according to another embodiment of the present invention, FIG. 19 is a flowchart illustrating a power saving method based on capability information-related information according to another embodiment of the present invention Fig.

18 and 19, the first terminal STA 1 may denote an AP or a no-AP, and the second terminal STA 1 may denote an AP or a non-AP. Capability-related information The power-saving method based on notification can be performed in three ways.

The first scheme is a scheme in which a UE to transmit a data frame advertises capability information. The second scheme is a scheme in which a UE to receive a data frame advertises capability information. In the third scheme, And the terminal to receive the data frame announce the capability information. Another difference between the respective schemes is that the types of information included in the Capability Request Frame and the Capability Notification Frame are different from each other.

A method for notifying the capability information of a terminal to transmit a data frame, which is the first scheme, is as follows.

The first terminal STA 1 can generate the capability related information including the indicator and the capability information indicating that the capability of the first terminal STA 1 is informed of the capability information of the first terminal STA 1, The second terminal STA2 can transmit the random request frame to the second terminal STA2 (S1500). Here, the capability order frame may indicate that the first terminal STA 1 can support capability-based operation based on capability information.

The capability information may include at least one of the WLAN standard version, the operation bandwidth, the center frequency, and the bandwidth information supported by the first terminal STA 1 to the second terminal STA 2. The band information may indicate which band among a plurality of bands is used, and may be expressed in a bitmap form or an index form. The capability request frame may be a control frame, a management frame, or a data frame. For example, the capability request frame may be an RTS frame or a PS-Poll frame.

The second terminal STA2 can receive the capability request frame from the first terminal STA1 and can receive the capability information of the first terminal STA1 included in the capability request frame , Indicator, and capability information). The second terminal STA 2 can know that the capacity information of the first terminal STA 1 is known through the indicator and can recognize the wireless LAN standard version, the operation bandwidth, the center frequency, It can be seen that communication based on the band indicated by the band information is supported by the first terminal STA 1.

The second terminal STA 2 can determine whether the frame can be received based on the capability related information included in the capability request frame. That is, the second terminal STA 2 determines whether the capability based on the bandwidth, the center frequency, and the band information included in the capability information of the wireless LAN standard version, the operation bandwidth, the center frequency, can do. If the second terminal STA 2 can not receive the frame based on the capability information included in the capability request frame, the second terminal STA 2 does not transmit a response to the capability request frame to the first terminal STA 1 .

On the other hand, if the second terminal STA2 can receive the frame based on the capability information included in the capability request frame, the second terminal STA2 can generate a capability notification frame including an indicator indicating the frame, The generated capability notification frame may be transmitted to the first terminal STA 1 (S 1510). Here, the capability notification frame may be a control frame, a management frame, or a data frame. For example, the capability notification frame may be a CTS frame.

After transmitting the capability notification frame to the first terminal STA 1 in response to the capability request frame, the second terminal STA 2 transmits the capability related information included in the capability order frame (S1520). That is, since the second terminal STA 2 can know the bandwidth at which the first terminal STA 1 operates based on the capability information among the capability information, You can decide to double as a clock. The second terminal STA 2 may set the determined clock to the circuits included therein.

For example, when the bitmap indicating the band information is 11100000, it indicates that the operating bandwidth supported by the first terminal STA 1 to the second terminal STA 2 is 60 MHz continuous, ) Can set the clock to 120MHz, which is double of 60MHz. Alternatively, when the bitmap indicating the bandwidth information is 10010000, it indicates that the operating bandwidth supported by the first terminal STA 1 to the second terminal STA 2 is 40 MHz, which is discontinuous. Therefore, the second terminal STA 2 must operate at a bandwidth of at least 80 MHz in order to receive the discontinuous 40 MHz, so that the clock can be set to 160 MHz which is twice the 80 MHz. Here, the process of setting the clock may be performed by the power management unit 560 of the second terminal STA2.

On the other hand, the second terminal STA 2 can determine the time to operate with the set clock. For example, when the capacity availability frame is an RTS frame, the second terminal STA 2 may determine a time indicated by a duration field included in the RTS frame as a time to operate with a predetermined clock. When the capability notification frame is a CTS frame, the second terminal STA2 may determine the time indicated by the duration field included in the CTS frame as a time to operate with the set clock.

In addition, the second terminal STA 2 can set the operation band based on the capability related information. That is, since the second terminal STA 2 can know the band in which the first terminal STA 1 operates based on the capability information among the capability information, the operation band of the first terminal STA 1, It is possible to set its own operation band to cope with it. Here, it is described that the step S1520 is performed after the step S1510, but the order in which the step S1520 is performed is not limited thereto. That is, step S1520 may be performed before step S1510.

The first terminal STA 1 may transmit the data frame to the second terminal STA 2 in response to the capacity availability frame in response to the capability request frame (S 1530). That is, the first terminal STA 1 transmits a data frame to the second terminal STA 2 (STA 2) through the band indicated by the WLAN standard version, the operation bandwidth, the center frequency, and the band information included in the capability information among the capability information ).

The second terminal STA 2 can receive the data frame from the first terminal STA 1 based on the set clock and can transmit the ACK frame to the first terminal STA 1 when the data frame has been successfully received (S1540). Thus, the second terminal STA 2 can reduce the reception power.

A method in which a terminal that receives a data frame of the second scheme advertises the capability information is as follows.

The first terminal STA 1 can generate the capability related information including the indicator indicating that it can support the transmission of the capability information by notifying the first terminal STA 1 of the capability information, The request frame can be transmitted to the second terminal STA2 (S1500). Here, the capability order frame may indicate that the first terminal STA 1 can support capability-based operation based on capability information. The capability request frame may be a control frame, a management frame, or a data frame. For example, the capability request frame may be an RTS frame or a PS-Poll frame.

The second terminal STA 2 can receive the capability request frame from the first terminal STA 1 and acquire the indicator included in the capability request frame. That is, the second terminal STA 2 can confirm that the first terminal STA 1 can support the transmission based on the announcement of the capability information through an indicator included in the capability order frame. In this case, in order to reduce the reception power, the second terminal STA 2 can receive the available bandwidth (that is, the operation bandwidth of the second terminal STA 2) in consideration of the battery status, the life time, Can be determined.

The second terminal STA 2 can generate the capability related information including the indicator and the capability information indicating that the capability information is announced, and the second terminal STA 2 transmits the capability information It may transmit the notification frame to the first terminal STA1 (S1510). The capability information may include at least one of a wireless LAN standard version supported by the second terminal STA 2, an operation bandwidth, a center frequency, and band information. The band information may indicate which band among a plurality of bands is used, and may be expressed in a bitmap form or an index form. The capability notification frame may be a control frame, a management frame, or a data frame. For example, the capability notification frame may be a CTS frame.

After transmitting the capability notification frame to the first terminal STA 1 in response to the capability order frame, the second terminal STA 2 can set the clock based on its own capability (S1520). That is, the second terminal STA 2 can determine that the clock is twice the operating bandwidth of the second terminal STA 2. The second terminal STA 2 may set the determined clock to the circuits included therein. Here, the process of setting the clock may be performed by the power management unit 560 of the second terminal STA2.

Also, the second terminal STA 2 can determine the time to operate with the set clock. For example, when the capability request frame is an RTS frame, the second terminal STA 2 may determine the time indicated by the duration field included in the RTS frame as a time operated with the set clock. When the capability notification frame is a CTS frame, the second terminal STA2 may determine the time indicated by the duration field included in the CTS frame as a time to operate with the set clock. Here, it is described that the step S1520 is performed after the step S1510, but the order in which the step S1520 is performed is not limited thereto. That is, step S1520 may be performed before step S1510.

The first terminal STA 1 may receive the capability announcement frame from the second terminal STA 2 in response to the capability request frame, Related information (i. E., The indicator and the capability information). The first terminal STA 1 can recognize that the capacity information of the second terminal STA 2 is known through the indicator and can recognize that the second terminal STA 2 included in the capability information It can be seen that communication based on the LAN standard version, the operation bandwidth, the center frequency, and the band indicated by the band information is supported by the second terminal STA 2.

The first terminal STA 1 may transmit the data frame to the second terminal STA 2 through the band indicated by the capability information of the second terminal STA 2 included in the capability announcement frame S1530).

For example, when the bitmap indicating the band information is 11100000, the first terminal STA 1 may transmit the data frame to the second terminal STA 2 through the continuous 60 MHz band. When the bitmap representing the band information is 10010000, the first terminal STA 1 may transmit the data frame to the second terminal STA 2 through the discontinuous 40 MHz band. The second terminal STA 2 sets the clock to 120 MHz, which is twice the clock rate of 60 MHz, when the bitmap indicating the band information is 11100000, and when the bitmap indicating the band information is 10010000, the second terminal STA 2 ) Can receive a data frame transmitted from the first terminal (STA 1) based on the clock (which is set to 160 MHz, which is twice the frequency of 80 MHz since it must operate at 80 MHz), and if the data frame is successfully received, To the first terminal STA 1 (S1540). Thus, the second terminal STA 2 can reduce the reception power.

A scheme of transmitting the data frame, which is the third scheme, and a terminal receiving the data frame announce capability information are as follows.

The first terminal STA 1 can generate the capability related information including the indicator and the capability information indicating that the capability of the first terminal STA 1 is informed of the capability information of the first terminal STA 1, The second terminal STA2 can transmit the random request frame to the second terminal STA2 (S1500). Here, the capability order frame may indicate that the first terminal STA 1 can support capability-based operation based on capability information.

 The capability information may include at least one of one or more WLAN standard versions supported by the first terminal STA 1, one or more operation bandwidths, one or more center frequencies, and one or more band information. The band information may indicate which band among a plurality of bands is used, and may be expressed in a bitmap form or an index form. The capability request frame may be a control frame, a management frame, or a data frame. For example, the capability request frame may be an RTS frame or a PS-Poll frame.

The second terminal STA2 can receive the capability request frame from the first terminal STA1 and can receive the capability information of the first terminal STA1 included in the capability request frame , Indicator, and capability information). The second terminal STA 2 can know that the capacity information of the first terminal STA 1 is known through the indicator and can recognize the wireless LAN standard version, the operation bandwidth, the center frequency, It can be seen that communication based on the band indicated by the band information is supported by the first terminal STA 1.

The second terminal STA2 may transmit one or more capabilities included in the capability request frame (one or more wireless LAN standard versions, one or more operation bandwidths, one The center frequency and one or more band information). For example, the second terminal STA 2 may determine the receivable bandwidth (i.e., the operating bandwidth of the second terminal STA 2) among the one or more operating bandwidths. The second terminal STA2 can generate the capability related information including the indicator indicating that the capability information is announced and the selected capability information and the capability information including the generated capability information The notification frame may be transmitted to the first terminal STA1 (S1510). The capability information may include at least one of a wireless LAN standard version supported by the second terminal STA 2, an operation bandwidth, a center frequency, and band information.

The band information may indicate which band among a plurality of bands is used, and may be expressed in a bitmap form or an index form. The capability notification frame may be a control frame, a management frame, or a data frame. For example, the capability notification frame may be a CTS frame. The capability information included in the capability notification frame may be set within the range of the capability information included in the capability request frame.

After transmitting the capability notification frame to the first terminal STA 1 in response to the capability order frame, the second terminal STA 2 transmits the capability information included in the capability order frame, The clock can be set in consideration of all of its own capabilities (S1520). That is, the second terminal STA 2 can determine that the operating bandwidth of the first terminal STA 1 is twice the common operating bandwidth of the first terminal STA 1 as a clock. The second terminal STA 2 may set the determined clock to the circuits included therein. Here, the process of setting the clock may be performed by the power management unit 560 of the second terminal STA2.

Also, the second terminal STA 2 can determine the time to operate with the set clock. For example, when the capability request frame is an RTS frame, the second terminal STA 2 may determine the time indicated by the duration field included in the RTS frame as a time operated with the set clock. When the capability notification frame is a CTS frame, the second terminal STA2 may determine the time indicated by the duration field included in the CTS frame as a time to operate with the set clock. Here, it is described that the step S1520 is performed after the step S1510, but the order in which the step S1520 is performed is not limited thereto. That is, step S1520 may be performed before step S1510.

The first terminal STA 1 may transmit the data frame to the second terminal STA 2 in response to the capacity availability frame in response to the capability request frame (S 1530). That is, the first terminal STA 1 transmits the data frame in the common band indicated by the capability information included in the capability order frame and the capability information included in the capability announcement frame to the second terminal STA 2).

The second terminal STA 2 can receive the data frame from the first terminal STA 1 based on the set clock and can transmit the ACK frame to the first terminal STA 1 when the data frame has been successfully received (S1540). Thus, the second terminal STA 2 can reduce the reception power.

On the other hand, in the power saving method based on the capacity related information announcement, the information included in the capability request frame (or the capability notification frame) includes a service field used as a scramble initialization bit Field located in front of the service field). That is, one bit of the service field can be used for indicating whether or not the capability related information is known.

The field setting values per channel mode and operation bandwidth can be set as shown in Table 5 below. That is, the terminal receiving the capability order frame (or the capability notification frame) can confirm the channel mode and the operation bandwidth of the counterpart terminal based on Table 5 below. Table 5 below shows a case where the operating bandwidth is 160 MHz.

If the channel mode is continuous, the band positions can be displayed in an index form as shown in Table 6 below. Table 6 below shows a case where the operating bandwidth is 160 MHz.

Meanwhile, the power management unit 560 of the terminal 500 can set the clock based on the characteristics of the frame when receiving the frame. That is, since the power management unit 560 of the terminal 500 can recognize the band mode based on the correlation or power of each preamble included in the frame and can recognize the operation bandwidth based on the SIG field included in the frame, The clock can be set based on the band mode and the operating bandwidth.

20 is a conceptual diagram for explaining a dynamic clock-based power saving method according to an embodiment of the present invention.

Referring to FIG. 20, the terminal 500 connected to the access point can operate as a default clock in the reception standby mode. For example, when accessing an access point that supports a bandwidth of 20/40/80 MHz, the terminal 500 can set the clock to 160 MHz and operate at a 160 MHz clock because the maximum operating bandwidth is 80 MHz.

When the terminal 500 receives a frame, the terminal 500 can detect the bandwidth based on the preamble included in the frame, and can reset the clock from the next field (i.e., the L-SIG field) according to the result of detecting the bandwidth. That is, when the preamble included in the frame is detected in units of 20 MHz, the terminal 500 can determine the bandwidth to be 40 MHz. If the bandwidth is 40 MHz, the terminal 500 can reset the clock to 80 MHz and operate the L- .

After that, the terminal 500 can detect the bandwidth by decoding the SIG field included in the frame, and can reset the clock from the next field (i.e., HEW-STF) based on the detected bandwidth. That is, when the decoding result bandwidth of the HEW-SIGA field included in the frame is determined to be 20 MHz, the terminal 500 can reset the clock to 40 MHz since the operation bandwidth is 20 MHz, and can operate at 40 MHz clock from HEW- .

The terminal 500 can maintain the clock set based on the HEW-SIGA field until the processing of the frame (i.e., decoding of the data field) is completed, and can change the clock to the default clock when the processing of the frame is completed. That is, the terminal 500 can decode the data field with a 40 MHz clock and reset the clock to 160 MHz to support all the bandwidth of the access point when the processing of the data field is completed.

Hereinafter, a power saving method through the step-by-step circuit control of the frame will be described.

Here, the circuit included in the terminal 500 may mean each of the configurations shown in Figs. 5 to 7. The electric power saving method based on the control of the gate size includes a power saving method based on carrier sensing, a power saving method based on automatic gain control, an LTF based power saving method, a PAID (partial AID) based power saving method, Power saving method based on wireless LAN standard version, power saving method based on packet error, detailed power saving method based on automatic gain control, power saving method based on DFE, power saving method based on phase compensation, etc. have.

The power saving method based on the carrier sensing is as follows. The power management unit 560 of the terminal 500 controls the carrier sensing unit 530 (i.e., the saturation based carrier sensing unit 531, the correlation based carrier sensing unit 532, the energy based carrier sensing unit 533) can be controlled. For example, the power management unit 560 of the terminal 500 can activate only the carrier sensing unit 530 during an idle listening period in which no signal is present, The carrier sensing unit 530 can be deactivated and the remaining circuits can be activated.

The power saving method based on automatic gain control is as follows. The power management unit 560 of the terminal 500 can activate the AGC 541-1-2 when a signal is detected through carrier sensing. The activated AGC 541-1-2 can perform gain control based on the L-STF included in the frame. The power management unit 560 of the terminal 500 may deactivate the AGC 541-1-2 when the gain control is completed.

The power saving method based on L-LTF is as follows. When the gain control is completed, an L-LTF based power saving method can be performed. The terminal 500 can determine whether to process the frame based on the L-LTF included in the frame. For example, the terminal 500 can calculate the SNR using the repetitive LTF symbol of the L-LTF of the frame, and obtain the transmission mode information from the SIG field included in the frame. The terminal 500 may estimate the decoding success probability of the frame based on the SNR and the transmission mode and may not decode the transmitted field if the decoding success probability is lower than a preset threshold value. That is, the power management unit 560 of the terminal 500 may deactivate the circuit associated with the frame process (i.e., the circuit used to receive the frame) until the end of reception of the frame.

The PAID-based power saving method is as follows. The terminal 500 can obtain the PAID from the SIG field included in the frame and if the obtained PAID does not match the PAID of the terminal 500, the transmitted field (i.e., HT-STF (or VHT-STF) -LTF (or VHT-LTF), HT-SIGB (or VHT-SIGB) field, data field). That is, when the PAID does not match, the power management unit 560 of the terminal 500 may deactivate the circuit associated with the frame process (i.e., the circuit used to receive the frame) until the reception end of the corresponding frame.

The power saving method based on the channel codec is as follows. The power management unit 560 of the terminal 500 can control the operation of the channel decoder according to the type of the channel code indicated by the SIG field included in the frame. Here, the channel decoder may be a Viterbi decoder, an LDPC decoder, or the like. For example, the power management unit 560 of the terminal 500 can activate the Viterbi decoder of the channel decoder and deactivate the LDPC decoder when the SIG field included in the frame indicates a Viterbi code. In contrast, if the SIG field included in the frame includes the LDPC code, the power management unit 560 of the terminal 500 can activate the LDPC decoder among the channel decoders and deactivate the Viterbi decoder.

The power saving method based on the wireless LAN standard version is as follows. A receiving end supporting the IEEE 802.11b standard and a receiving end supporting the IEEE 802.11a / g / n / ac / ax standard (i.e., a receiving end supporting the OFDM scheme) And they do not operate at the same time. Accordingly, if the preamble and the SIG field included in the frame indicate that the current frame is a frame conforming to the IEEE 802.11b standard, the power management unit 560 of the terminal 500 can activate the receiving end supporting the IEEE 802.11b standard, It is possible to inactivate the receiving end supporting the method.

On the other hand, if the preamble and the SIG field included in the frame indicate that the current frame is a frame conforming to the IEEE 802.11a / g / n / ac / ax standard, the power management unit 560 of the terminal 500 And disable the receiving end supporting the IEEE 802.11b standard.

The power saving method based on the packet error is as follows. The terminal 500 may initiate a state machine and transition to a carrier sensing state when a cyclic redundancy check (CRC) error occurs in a HEW-SIG field of a frame conforming to the IEEE 802.11ax standard. In this case, the power management unit 560 of the terminal 500 can activate the carrier sensing unit 530 and deactivate the remaining circuits.

The power saving method based on detailed automatic gain control is as follows. The power management unit 560 of the terminal 500 can activate the AGC 541-1-2 before receiving the HEW-STF of the frame conforming to the IEEE 802.11ax standard. The activated AGC 541-1-2 may perform gain control based on the HEW-STF, and may store gain control values and related parameters. The power management unit 560 of the terminal 500 may deactivate the AGC 541-1-2 when the HEW-STF-based gain control is completed.

The power saving method based on DFE is as follows. The power management unit 560 of the terminal 500 may deactivate the DFE processing the next time-domain subband while processing the data field of the frame. That is, the power management unit 560 of the UE 500 includes a channel mixer 541-2-1, a filter 541-2-2, a symbol synchronization detector 541-2, -23, an auto-correlation detecting unit 541-2-4, an inter-correlation detecting unit 541-2-5, a CCA detecting unit 541-2-6, an RSSI detecting unit 541-2-7, The control unit 541-2-8 and the like can be deactivated.

The power saving method based on phase compensation is as follows. The power management unit 560 of the terminal 500 can control the operation of the phase compensation unit 541-3-2. The power management unit 560 of the terminal 500 can simultaneously activate the phase compensation unit 541-3-2 when the data field included in the frame is decoded. The activated phase compensator 541-3-2 can estimate the phase error based on a small number of pilot signals and then use the loop filter to filter the noise to stabilize the phase error.

The power management unit 560 of the terminal 500 may deactivate the phase compensation unit 541-3-2 for a predetermined period of time to reduce power consumption due to a complicated operation after the phase error is stabilized, So that the operation of the phase compensating unit 541-3-2 can be controlled to compensate. For example, the power management unit 560 of the terminal 500 may inactivate the phase compensation unit 541-3-2 from the time when the phase error is stabilized until the reception end of the frame when the length of the frame is shorter than a preset length . On the other hand, the power management unit 560 of the terminal 500 may control the operation of the phase compensator 541-3-2 to periodically compensate the phase error when the length of the frame is longer than a predetermined length.

Hereinafter, a power saving method in an OFDMA or MU-MIMO transmission environment will be described.

When the communication system operates in the downlink OFDMA scheme or the downlink MU-MIMO scheme, the actual data fields (i.e., data fields except for the padding portion) transmitted to each terminal 500 are different . In this case, each of the terminals 500 can operate in a power saving mode from the end of reception of the real data field included in the frame to the end of the reception of the data frame. At this time, the terminal 500 may operate in a doze mode for power saving and may operate in a power saving mode in an awake mode.

21 is a flowchart illustrating a power saving method for each terminal according to an embodiment of the present invention.

Referring to FIG. 21, the first STA 1 may denote an AP or a non-AP, and the second STA 2 may denote an AP or a non-AP. The first STA 1 may transmit a data frame based on a downlink OFDMA scheme or a downlink MU-MIMO scheme. The first terminal STA 1 may generate power saving information including information indicating the length of the substantial data field, and may generate a data frame including power saving information (S 2100).

The power saving information can be divided into common power saving information and terminal specific power saving information. The common power saving information may mean power saving information commonly provided to all terminals. For example, the common power saving information may include a terminal identifier or a group identifier indicating terminals receiving a frame based on a downlink OFDMA scheme or a downlink MU-MIMO scheme. Also, the common power saving information may include at least one of an indicator indicating operation in a power saving mode for each terminal and information indicating a type of power saving mode (for example, a power saving mode for each terminal, a clock power saving mode, etc.) .

The UE-specific power saving information may mean power saving information provided to each UE. For example, the UE-specific power saving information may include at least one of an identifier of a UE and information indicating a length of a substantial data field. In addition, the UE-specific power saving information may further include at least one of an operation bandwidth, a center frequency, band information, and modulation and coding scheme (MCS) information of the first terminal STA 1.

The first terminal STA 1 may generate a SIG field including power saving information and may generate a data frame including the generated SIG field. The first STA 1 may transmit the data frame including the power saving information to the UEs using the OFDMA scheme or the MU-MIMO scheme (S2110). The second terminal STA2 can acquire power saving information (i.e., common power saving information, terminal specific power saving mode) included in the SIG field of the data frame when the data frame is received.

The second terminal STA 2 can determine whether the terminal identifier (or group identifier) included in the common power saving information matches the identifier of the second terminal STA 2 when the common power saving information is acquired. The second terminal STA 2 may receive a field transmitted after the SIG field if its identifier matches the terminal identifier (or group identifier) included in the common power saving information. On the other hand, the second terminal STA 2 may not receive a field transmitted after the SIG field if its identifier does not match the terminal identifier (or group identifier) included in the common power saving information. In this case, the power management unit 560 of the second terminal STA 2 may deactivate all the circuits included in the receiver until the end of transmission of the corresponding frame.

The second terminal STA2 may check the length of the real data field included in the frame based on the information included in the UE-specific power saving information (S2120). Also, the second terminal STA 2 can confirm the operation bandwidth of the first terminal STA 1 based on the information included in the terminal-specific power saving information, can determine the operation bandwidth to be twice the clock, The clock can be set in the circuits included in itself. Here, the process of setting the clock may be performed by the power management unit 560 of the second terminal STA2.

After that, the second terminal STA2 can receive the real data field included in the data frame. In this case, when the reception end time of the real data field is earlier than the reception end time of the data frame, the second terminal STA2 transmits a power save mode (i.e., Mode, a power saving mode in an awake mode) (S2130). The second terminal STA2 can transition from the power save mode to the awake mode after the reception end time of the data frame (S2140), and transmits the ACK frame to the first terminal STA 1 in response to the reception of the frame (S2150).

22 is a conceptual diagram showing an embodiment of a data frame including power saving information.

Referring to FIG. 22, an access point may transmit a data frame to terminals STA1, STA2, STA3, and STA4 in a downlink OFDMA or downlink MU-MIMO scheme. The data frame may include L-STF, L-LTF, L-SIG field, HEW-SIGA field, HEW-STF, HEW-LTF, HEW-SIGB field and data field. The HEW-SIGA field, the HEW-STF, the HEW-LTF and the HEW-SIGB fields may refer to fields specified for a communication system according to the IEEE 802.11ax standard.

 The access point may generate a HEW-SIGA field including common power saving information, and may generate a HEW-SIGB field including terminal specific power saving information. The common power saving information includes a terminal identifier (or a group identifier) indicating terminals receiving a frame based on a downlink OFDMA scheme or a downlink MU-MIMO scheme, an indicator indicating that the terminal operates in a power saving mode for each terminal, And information indicating the type of information. The UE-specific power saving information may include at least one of information indicating a length of an actual data field, an operation bandwidth of an access point, a center frequency, band information, and MCS information.

Based on the UE-specific power saving information, the first terminal STA1 can recognize that the reception end time of the real data field is equal to the reception end time of the data frame. Therefore, the first terminal STA1 does not operate in the power saving mode (i.e., the doze mode, the power save mode in the awake mode) from the reception end point of the substantial data field to the reception end point of the data frame. On the other hand, the second terminal STA2, the third terminal STA3 and the fourth terminal STA4 can recognize that the reception end time of the real data field is faster than the reception end time of the data frame based on the UE- have. Accordingly, the second terminal STA2, the third terminal STA3, and the fourth terminal STA4 are able to transmit a pay-saving mode (i.e., a doze mode, an awake mode, In the power save mode).

23 is a conceptual diagram showing another embodiment of a data frame including power saving information.

Referring to FIG. 23, an access point may transmit a data frame to terminals STA1, STA2, STA3, and STA4 in a downlink OFDMA or downlink MU-MIMO scheme. The data frame may include L-STF, L-LTF, L-SIG field, HEW-SIGA field, HEW-STF, HEW-LTF and data field. The HEW-SIGA field, HEW-STF, and HEW-LTF may refer to fields specified for a communication system according to the IEEE 802.11ax standard.

 The access point can generate a HEW-SIGA field including the UE-specific power saving information. The terminal-specific power saving information includes information indicating a length of an actual data field, an operation bandwidth of the access point, a center frequency, band information, MCS information, an indicator indicating operation in a power saving mode for each terminal, And a terminal identifier (or group identifier).

Based on the UE-specific power saving information, the first terminal STA1 can recognize that the reception end time of the real data field is equal to the reception end time of the data frame. Therefore, the first terminal STA1 does not operate in the power saving mode (i.e., the doze mode, the power save mode in the awake mode) from the reception end point of the substantial data field to the reception end point of the data frame. On the other hand, the second terminal STA2, the third terminal STA3 and the fourth terminal STA4 can recognize that the reception end time of the real data field is faster than the reception end time of the data frame based on the UE- have. Accordingly, the second terminal STA2, the third terminal STA3, and the fourth terminal STA4 are in a power save mode (i.e., a doze mode, an awake mode, In the power save mode).

24 is a conceptual diagram showing another embodiment of a data frame including power saving information.

Referring to FIG. 24, an access point may transmit a data frame to terminals STA1, STA2, STA3, and STA4 in a downlink OFDMA or downlink MU-MIMO scheme. The data frame may include L-STF, L-LTF, L-SIG field, HEW-SIGA field, HEW-STF, HEW-LTF, HEW-SIGB field and data field. The HEW-SIGA field, the HEW-STF, the HEW-LTF and the HEW-SIGB fields may refer to fields specified for a communication system according to the IEEE 802.11ax standard.

 The access point can generate the HEW-SIGA field including the UE-specific power saving information and generate the HEW-SIGB field including the extended UE-specific power saving information. The UE-specific power saving information and the extended UE-specific power saving information may include the same information. For example, the UE-specific power saving information (or extended UE-specific power saving information) includes information indicating the length of the substantial data field, the operation bandwidth of the access point, center frequency, band information, MCS information, Information indicating the type of the power saving mode, and a terminal identifier (or group identifier).

Alternatively, the UE-specific power saving information may include extended UE-specific power saving information and other information. For example, the UE-specific power saving information may include only the information indicating the length of the substantial data field, and the extended UE-specific power saving information may include information other than the information indicating the length of the substantial data field.

Based on the UE-specific power saving information (or extended UE-specific power saving information), the first terminal STA1 can recognize that the reception end time of the real data field is equal to the reception end time of the data frame. Therefore, the first terminal STA1 does not operate in the power saving mode (i.e., the doze mode, the power save mode in the awake mode) from the reception end point of the substantial data field to the reception end point of the data frame. On the other hand, the second terminal STA2, the third terminal STA3, and the fourth terminal STA4 determine whether the reception end point of the real data field is the data It is possible to know that the reception time of the frame is earlier than the reception end time. Accordingly, the second terminal STA2, the third terminal STA3, and the fourth terminal STA4 are able to transmit a pay-saving mode (i.e., a doze mode, an awake mode, In the power save mode).

25 is a conceptual diagram for explaining a clock-based power saving method using a data frame including power saving information.

Referring to FIG. 25, an access point may transmit a data frame to terminals STA1, STA2, STA3 in a downlink OFDMA or downlink MU-MIMO scheme. The data frame may include L-STF, L-LTF, L-SIG field, HEW-SIGA field, HEW-STF, HEW-LTF, HEW-SIGB field and data field. The HEW-SIGA field, the HEW-STF, the HEW-LTF and the HEW-SIGB fields may refer to fields specified for a communication system according to the IEEE 802.11ax standard.

 The access point may generate a HEW-SIGA field including common power saving information, and may generate a HEW-SIGB field including terminal specific power saving information. The common power saving information includes a terminal identifier (or a group identifier) indicating terminals receiving a frame based on a downlink OFDMA scheme or a downlink MU-MIMO scheme, an indicator indicating that the terminal operates in a power saving mode for each terminal, And information indicating the type of information. The UE-specific power saving information may include at least one of information indicating a length of an actual data field, an operation bandwidth of an access point, a center frequency, band information, and MCS information.

Alternatively, the access point may generate the HEW-SIGA field including the UE-specific power saving information, and may generate the HEW-SIGB field including the extended UE-specific power saving information. The UE-specific power saving information and the extended UE-specific power saving information may include the same information.

For example, the UE-specific power saving information (or extended UE-specific power saving information) includes information indicating the length of the substantial data field, the operation bandwidth of the access point, center frequency, band information, MCS information, Information indicating the type of the power saving mode, and a terminal identifier (or group identifier).

Alternatively, the UE-specific power saving information may include extended UE-specific power saving information and other information. For example, the UE-specific power saving information may include only the information indicating the length of the substantial data field, and the extended UE-specific power saving information may include information other than the information indicating the length of the substantial data field.

Since the first terminal STA1 knows that the operation bandwidth of the access point is 40 MHz based on the information included in the terminal specific power saving information (or extended terminal specific power saving information) Can be set. Also, the first terminal STA1 can recognize that the reception end point of the real data field is equal to the reception end point of the data frame based on the information included in the terminal specific power saving information (or extended terminal specific power saving information) have. Accordingly, the first terminal STA 1 can receive the data field based on the 80 MHz clock, and can perform power save mode (i.e., doze mode, awake mode, In the power save mode).

On the other hand, the second terminal STA2 and the third terminal STA3 can recognize that the operation bandwidth of the access point is 20 MHz based on the information included in the terminal-specific power saving information (or extended terminal specific power saving information) , The clock can be set to 40 MHz, which is double the operation bandwidth. Also, the second terminal STA2 and the third terminal STA3 may determine that the reception end time of the real data field is the reception of the data frame based on the information included in the terminal specific power saving information (or the extended terminal specific power saving information) It can be seen that it is faster than the end point. Accordingly, the second terminal STA2 and the third terminal STA3 can receive the data field based on the 40 MHz clock, and the power saving mode (i.e., the power saving mode) from the reception end point of the real data field to the reception end point of the data frame, A doze mode, and a power saving mode in an awake mode).

Meanwhile, the power saving method based on the capability information notification described above can be applied to a communication system supporting the downlink OFDMA scheme or the downlink MU-MIMO scheme.

26 is a conceptual diagram for explaining a power saving method for each terminal according to another embodiment of the present invention.

Referring to FIG. 26, an access point (AP) may transmit a capability request frame to terminals (STA1, STA2, STA3, STA4) in a downlink OFDMA scheme or a downlink MU-MIMO scheme. The capability request frame may mean a control frame, a management frame, or a data frame. For example, the capability request frame may refer to an RTS frame.

Each of the terminals STA1, STA2, STA3, and STA4 may transmit a capability notification frame to an access point (AP) in response to the capability request frame. The capability announcement frame may refer to a control frame, a management frame, or a data frame. For example, the capability notification frame may refer to a CTS frame.

Here, the transmission procedure of the capability request frame and the capability notification frame can be performed based on the power saving method based on the capability information notification described with reference to Figs. 18 and 19. [ The difference between the power saving method for each terminal shown in FIG. 26 and the power saving method based on the capability information notification shown in FIG. 18 and FIG. 19 is that the capacity request frame Information indicating the length of a substantial data field included in a frame (i.e., a capacity availability frame, a data frame transmitted after the capacity availability notification frame).

That is, according to a scheme in which the terminal that transmits the data frame of the first scheme announces the capability information, the capability request frame includes an indicator indicating that the capability information is known, And may include information indicating the length of the actual data field included. The capability information may include at least one of a wireless LAN standard version supported by an access point (AP), an operation bandwidth, a center frequency, and band information. The capability notification frame may include an indicator indicating that the data frame can be received based on the capability information included in the capability request frame.

According to a scheme in which the terminal that receives the data frame, which is the second scheme, discloses the capability information, the capability request frame is included in an indicator and a data frame indicating that it is capable of supporting the transmission of the capability information by notification And information indicating the length of the real data field. The capability notification frame may include indicator and capability information indicating that the capability information is known. The capability information may include at least one of a wireless LAN standard version, an operation bandwidth, a center frequency, and band information supported by each of the terminals STA1, STA2, STA3, and STA4.

The third scheme is a scheme in which both a terminal for transmitting a data frame and a terminal for receiving a data frame announce capability information. The capability request frame is an indicator for indicating capability information, And information indicating the length of the real data field included in the data frame. The capability information may include at least one of a wireless LAN standard version supported by an access point (AP), an operation bandwidth, a center frequency, and band information. The capability notification frame may include indicator and capability information indicating that the capability information is known. The capability information may include at least one of a wireless LAN standard version, an operation bandwidth, a center frequency, and band information supported by each of the terminals STA1, STA2, STA3, and STA4.

In FIG. 26, it is assumed that an access point (AP) and terminals STA1, STA2, STA3, and STA4 operate based on a second scheme. The access point (AP) transmits a capability request frame including information indicating the length of the substantial data field included in the data frame and an indicator indicating that it is capable of supporting the transmission of the capability information by downlink OFDMA or down STA2, STA3, and STA4 based on the link MU-MIMO scheme.

The first terminal STA1 receives an identifier indicating that the capability information is to be notified when receiving the capability request frame, an identifier indicating the capability bandwidth 40 MHz, a bandwidth index {0, 1} Can be generated. Here, the band indices {k1, k2} may indicate that the k1-th band and the k2-th band are allocated. The first terminal STA1 may transmit the capability notification frame to the access point (AP) in response to the capability request frame.

If the second terminal STA2 does not support the power saving method based on the capability information notification, the second terminal STA2 may simply transmit the capability notification frame to the access point (AP) in response to the capability request frame. That is, the capability notification frame includes information indicating the capability information announcement, a wireless LAN standard version supported by the second terminal STA 2, operation bandwidth, center frequency, band information, and the like I never do that.

The third terminal STA3 generates a capacity availability notification frame including an indicator indicating that capacity information is known when the capacity request frame is received, an operating bandwidth of 20 MHz, a band index {3}, and the like . The third terminal STA3 may transmit the capability notification frame to the access point (AP) in response to the capability request frame.

The fourth terminal STA4 is an indicator indicating that the capability information is notified when the capacity request frame is received, the capacity of the terminal 4 including the operation bandwidth of 80 MHz, the band index {4,5,6,7} A provisioning frame can be generated. The fourth terminal STA4 may transmit the capability notification frame to the access point (AP) in response to the capability request frame.

Here, the terminals STA1, STA2, STA3, and STA4 can transmit the capability notification frame to the access point (AP) in the OFDMA scheme.

The access point (AP) can transmit a data frame to the terminals (STA1, STA2, STA3, STA4) based on the information included in the capability notification frame when the access point (AP) receives the capability announcement frame. For example, an access point (AP) may transmit a data frame to the first terminal STA1 within the band indicated by the operating band-width of 40 MHz and the band index {0, 1}. The access point AP may transmit the data frame to the third terminal STA3 within the band indicated by the band index {3} and the operating bandwidth of 20 MHz. The access point AP may transmit the data frame to the fourth terminal STA4 within the band indicated by the operation index 80 MHz and the band index {4,5,6,7}. Meanwhile, since the capability information of the second terminal STA2 is not known, the access point AP can transmit the data frame to the second terminal STA2 within a bandwidth that the access point AP can support.

The terminals STA1, STA2, STA3, STA4 can receive a data frame transmitted from an access point (AP). At this time, the first terminal STA1 can recognize that the reception end point of the real data field and the reception end point of the data frame are identical based on the information included in the Capabilityity Request frame, Based on the included information, you can set the clock to 80 MHz, which is twice the operating bandwidth. Accordingly, the first terminal STA1 can receive the data frame based on the 80 MHz clock, and can perform the power save mode (i.e., the power saving mode in the doze mode and the awake mode) Mode).

The second terminal STA2 can know that the reception end point of the real data field is faster than the reception end point of the data frame based on the information included in the capacity availability frame. Therefore, the second terminal STA 2 can receive the data frame based on the 320 MHz clock, which is twice the operation bandwidth that the access point (AP) can support. The second terminal STA 2 can receive the data frame from the reception end point of the real data field (I.e., the doze mode, the power saving mode in the awake mode).

The third terminal STA3 can recognize that the reception end time of the real data field is earlier than the reception end time of the data frame based on the information included in the capability order frame, Based on the information, a clock of 40 MHz, which is twice the operation bandwidth, can be set. Accordingly, the third terminal STA3 can receive the data frame on the basis of the 40 MHz clock, and is capable of receiving the data frame in the power save mode (i.e., the doze mode, the awake mode, Power saving mode).

The fourth terminal STA4 can recognize that the reception end point of the real data field is faster than the reception end point of the data frame based on the information included in the capacity availability frame, Based on the information, it is possible to set a clock of 160 MHz which is twice the operation band frequency. Accordingly, the fourth terminal STA4 can receive the data frame based on the 160MHz clock, and can transmit power in the power save mode (i.e., in the doze mode and the awake mode) from the reception end point of the real data field to the reception end point of the data frame Power saving mode).

The terminals STA1, STA2, STA3, and STA4 can transmit an ACK frame to an access point (AP) in an OFDMA scheme when they successfully receive a frame.

In the following, a power saving method according to the wireless LAN standard supported by the access point will be described. Based on the phase modulation of the SIG field included in the frame, the terminal 500 can determine whether the current frame is a frame conforming to the IEEE 802.11a standard, a frame conforming to the IEEE 802.11n standard, or a frame conforming to the IEEE 802.11ac standard. In addition, the terminal 500 can determine whether the current frame is a frame conforming to the IEEE 802.11ax standard based on the SIG field included in the frame or the additionally allocated transmission mode bits.

27 is a flowchart illustrating a power saving method based on a WLAN standard supported by an access point according to an embodiment of the present invention.

Referring to FIG. 27, the terminal 500 can receive a frame from an arbitrary access point and check the SIG field of the frame (S2700). The terminal 500 can determine whether the IEEE 802.11 standard supported by the access point that transmitted the frame based on the phase modulation of the SIG field is more advanced than the IEEE 802.11 standard supported by the access point to which the access point is connected in operation S2710.

When the IEEE 802.11 standard (e.g., IEEE 802.11ac) supported by the access point that transmitted the frame is newer than the IEEE 802.11 standard (e.g., IEEE 802.11n) supported by the access point to which the terminal 500 is connected , The terminal 500 can stop receiving the remaining frames (i.e., the fields transmitted after the SIG field) (S2730), and the power saving mode (i.e., the power save mode in the doze mode and the awake mode) Mode) (S2740).

On the other hand, if the IEEE 802.11 standard supported by the access point that transmitted the frame is not more recent than the IEEE 802.11 standard supported by the access point to which the terminal 500 is connected, It can be determined whether the IEEE 802.11 standard is newer than the IEEE 802.11 standard supported by the access point that transmitted the frame (S2720).

When the IEEE 802.11 standard (for example, IEEE 802.11ac) supported by the access point to which the terminal 500 is connected is newer than the IEEE 802.11 standard (for example, IEEE 802.11n) supported by the access point that transmitted the frame , The terminal 500 can stop receiving the remaining frames (i.e., the fields transmitted after the SIG field) (S2730), and the power saving mode (i.e., the power save mode in the doze mode and the awake mode) Mode) (S2740).

Meanwhile, if the IEEE 802.11 standard supported by the access point to which the terminal 500 is connected is the same as the IEEE 802.11 standard supported by the access point that transmitted the frame, the terminal 500 transmits the remaining frames (i.e., Field) (S2750).

The capability capability request frame and the capability notification frame corresponding to the capability relevancy related frame described in the embodiments of the present invention may be a management frame, a control frame, or a data frame.

When the capability related frame corresponds to a management frame, the capability request frame and the capability notify frame may be a request frame and a response frame defined in IEEE 802.11ac as shown in Table 1. [ For example, the capability request frame and the capability notification frame may be a connection request frame and a connection response frame, respectively. Alternatively, if the capability notification frame does not correspond to the response frame of the capability request frame, the capability notification frame may be a beacon frame.

When the capability related frame corresponds to a control frame, the capability request frame and the capability notify frame may be an RTS frame and a CTS frame, respectively, as shown in Table 2. [

The capability capability request frame and the capability notification frame may be newly defined as a control frame or a management frame and may be newly defined as a spare frame in the IEEE 802.11ac for identification of the capability capability frame and the capability notification frame. A reserved value may be used.

Embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. Program instructions to be recorded on a computer-readable medium may be those specially designed and constructed for embodiments of the present invention or may be available to those skilled in the art of computer software.

The computer-readable medium may refer to a hardware device that is specifically configured to store and execute program instructions, such as a ROM, a RAM, a flash memory, and the like. A hardware device may be configured to operate with at least one software module to perform operations in accordance with embodiments of the present invention, and vice versa. A program instruction may refer to a high-level language code that may be executed on a computer based on, for example, an interpreter, as well as machine code as produced by a compiler

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (21)

A low power communication method performed in a first terminal,
Receiving a capability notification frame including first capability-related information from a second terminal; And
And setting a power saving mode of the first terminal based on the first capability information. The method according to claim 1,
The first capability information may include:
And an indicator indicating notification of the capability information and the capability information of the second terminal. The method of claim 2,
Wherein the capability information of the first terminal comprises:
Wherein the second terminal includes at least one of a standard version, an operation bandwidth, a center frequency, and band information of a wireless LAN supported by the second terminal. Claim 2
Wherein the power save mode of the first terminal comprises:
Wherein the capability information of the second terminal is set based on the capability information of the second terminal when the capability information of the second terminal is included in the first capability information. The method according to claim 1,
The low power communication method includes:
Further comprising the step of transmitting a capability request frame including second capability-related information to the second terminal,
Wherein the capability notification frame is a response to the capability request frame. The method of claim 5,
The second capability information may include:
And an indicator indicating notification of the capability information and the capability information of the first terminal. The method of claim 6,
Wherein the capability information of the first terminal comprises:
Wherein the first terminal includes at least one of a wireless LAN standard version, an operation bandwidth, a center frequency, and band information supported by the first terminal. The method of claim 6,
The power save mode of the second terminal includes:
Wherein the capability information is set based on the capability information of the first terminal when the capability information of the first terminal is included in the second capability information. The method of claim 6,
The power save mode of the second terminal includes:
When the second capability information does not include the capability information of the first terminal but includes an indicator indicating the capability information, a low power set based on the capaity of the second terminal Communication method. The method of claim 6,
The power save mode of the second terminal includes:
Wherein the capability information is set based on the capability information of the first terminal and the capabilty of the second terminal when the capability information of the first terminal is included in the second capability information. The method according to claim 1,
The capability notification frame includes:
A low power communication method that is a clear to send (CTS) frame or a data frame. The method according to claim 1,
The capability request frame includes:
A low power communication method, wherein the method is a request to send (RTS) frame or a power save (PS) frame. A low power communication method performed in a terminal,
When a data frame is received from an access point based on an orthogonal frequency division multiple access (OFDMA) scheme, a data frame is received from the data frame except for a padding portion included in the data frame, Obtaining information indicating a length of a data field;
Calculating a reception end point of the real data field based on information indicating a length of the real data field; And
And operating in a power saving mode at a reception end time of the pseudo data field when the reception end time of the pseudo data field is before the reception end time of the data frame. 14. The method of claim 13,
Wherein the information indicating the length of the substantial data field includes:
(SIGA) or SIGB (signal B) field of the data frame. 14. The method of claim 13,
The low power communication method includes:
And operating in an awake mode at the end of reception of the data frame. A receiving unit for receiving a frame; And
And a power management unit for controlling at least one of a power source and a clock provided to each of a plurality of components included in the reception unit according to a reception step of the frame. 18. The method of claim 16,
The power management unit includes:
A low power communication terminal that activates a component that performs carrier sensing among the plurality of components through control of at least one of a power source and a clock in a carrier sensing phase. 18. The method of claim 16,
The power management unit includes:
And activates a component that performs an operation based on the STF among the plurality of components through control of at least one of a power source and a clock when receiving a short training field (STF) of the frame. 18. The method of claim 16,
The power management unit includes:
And activates a component that performs the operation based on the LTF among the plurality of components through control of at least one of a power source and a clock when receiving a long training field (LTF) of the frame. 18. The method of claim 16,
The power management unit includes:
A low power communication terminal that activates a component that performs an operation based on the SIG field among the plurality of components through control of at least one of a power source and a clock when receiving a SIG (signal) field of the frame. 18. The method of claim 16,
The power management unit includes:
And when receiving a data field of the frame, activates a component of the plurality of components performing an operation based on the data field through control of at least one of a power source and a clock.

Images