KR102378708B1 - Operation method of station in wireless local area network - Google Patents

Abstract

A method of operating a station in a wireless LAN is disclosed. A method of operating a station in a wireless LAN according to the present invention comprises the steps of: generating a legacy preamble; generating a high efficiency (HE) preamble including scheduling information of a plurality of receiving stations; and generating a physical layer convergence procedure (PLCP) protocol data unit (PPDU) including the legacy preamble, the HE preamble, and a payload.

Description

How to operate a station in a wireless LAN {OPERATION METHOD OF STATION IN WIRELESS LOCAL AREA NETWORK}

The present invention relates to operation of a station in a wireless LAN, and more particularly, to a technique for generating and transmitting a frame supporting OFDMA in a wireless LAN.

With the development of information and communication technology, various wireless communication technologies are being developed. Among them, wireless local area network (WLAN) is a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), a smart It is a technology that enables wireless access to the Internet at home, in a business, or in a specific service area by using a portable terminal such as a smart phone or a tablet PC.

A standard for a wireless LAN technology is being developed as an IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard. IEEE 802.11a uses an unlicensed band at 5 GHz, and provides a transmission rate of 54 Mbps. IEEE 802.11b provides a transmission speed of 11 Mbps by applying a direct sequence spread spectrum (DSSS) method at 2.4 GHz. IEEE 802.11g applies orthogonal frequency division multiplexing (OFDM) at 2.4 GHz to provide a transmission rate of 54 Mbps. IEEE 802.11n provides a transmission rate of 300 Mbps for four spatial streams by applying multiple input multiple output-OFDM (MIMO-OFDM). IEEE 802.11n supports a channel bandwidth of up to 40 MHz, and in this case, a transmission rate of 600 Mbps is provided.

As the spread of such WLANs is activated and applications using them are diversified, the need for a new WLAN technology to support a higher throughput than the data processing rate supported by IEEE 802.11n has increased. A very high throughput (VHT) wireless LAN technology is one of the IEEE 802.11 wireless LAN technologies proposed to support a data processing rate of 1 Gbps or more. Among them, IEEE 802.11ac is a standard for providing ultra-high throughput in a band below 6 GHz, and IEEE 802.11ad is a standard for providing ultra-high throughput in a band of 60 GHz.

In addition, standards for various wireless LAN technologies have been defined, and standard development is in progress. Typically, IEEE 802.11af is a standard prescribed for the operation of a wireless LAN in a TV white space, IEEE 802.11ah is a standard prescribed to support a large number of terminals operating with low power, and IEEE 802.11ai is a standard prescribed for fast initial link setup (FILS) in a WLAN system. In recent years, the development of the IEEE 802.11ax standard for the purpose of improving frequency efficiency in a dense environment in which a plurality of base stations and terminals exist is in progress.

This wireless LAN technology can use a wide bandwidth such as 80 MHz and a maximum of 160 MHz in order to increase the transmission speed. However, since the WLAN standard has to provide backward compatibility with respect to the previous standard, there is a problem that the remaining bandwidth cannot be used when communicating with a device using a narrow bandwidth. That is, when the AP (access point) is a wireless LAN device using a wide bandwidth and the STA (terminal) is a wireless LAN device using a narrow bandwidth, the AP has a primary channel and a secondary channel can be used simultaneously, but since the STA can use only the primary channel, when the AP transmits data to the STA, the secondary channel cannot be used because data must be transmitted using only the primary channel. This problem also occurs when the STA transmits data to the AP.

It is an object of the present invention to provide a method of operating a station in a wireless LAN in which a wireless LAN device using a wide bandwidth can transmit and receive data to two or more devices simultaneously by dividing the bandwidth.

In accordance with an embodiment of the present invention for achieving the above object, there is provided a method of operating a station in a wireless LAN, the method comprising: generating a legacy preamble; generating a high efficiency (HE) preamble including scheduling information of a plurality of receiving stations; and generating a physical layer convergence procedure (PLCP) protocol data unit (PPDU) including the legacy preamble, the HE preamble, and a payload.

Here, the HE preamble may include a HE-SIG (signal)-A field, a HE-STF (short training field), at least one HE-LTF (long training field), and a HE-SIG-B field.

Here, the HE preamble may include an indicator indicating that the PPDU is transmitted in an orthogonal frequency division multiplexing access (OFDMA) scheme.

Here, the HE preamble may include identification information of a group to which the plurality of receiving stations belong.

Here, the scheduling information may include information indicating a frequency band allocated to each of the plurality of reception stations.

Here, the scheduling information may include information indicating a bandwidth of a frequency band allocated to each of the plurality of reception stations.

Here, the scheduling information may include identification information of the plurality of reception stations allocated to each of the plurality of frequency bands.

Here, the scheduling information may be included in the HE-SIG-A field.

Here, the method may further include transmitting the generated PPDU in an orthogonal frequency division multiplexing access (OFDMA) scheme.

According to another embodiment of the present invention for achieving the above object, there is provided a method of operating a station in a wireless LAN, the method comprising: acquiring a legacy preamble of a physical layer convergence procedure (PLCP) protocol data unit (PPDU); obtaining a high efficiency (HE) preamble of the PPDU; and acquiring at least one data unit included in the payload of the PPDU through a resource indicated by scheduling information for a plurality of receiving stations included in the HE preamble. there is.

Here, the HE preamble may include a HE-SIG (signal)-A field, a HE-STF (short training field), at least one HE-LTF (long training field), and a HE-SIG-B field.

Here, the HE preamble may include an indicator indicating that the PPDU is transmitted in an orthogonal frequency division multiplexing access (OFDMA) scheme.

Here, the HE preamble may include identification information of a group to which the plurality of receiving stations belong.

Here, the scheduling information may include information indicating a frequency band allocated to each of the plurality of reception stations.

Here, the scheduling information may include information indicating a bandwidth of a frequency band allocated to each of the plurality of reception stations.

Here, the scheduling information may include identification information of the plurality of reception stations allocated to each of the plurality of frequency bands.

Here, the scheduling information may be included in the HE-SIG-A field.

Here, the PPDU may be received in an orthogonal frequency division multiplexing access (OFDMA) scheme.

According to the present invention, a wireless LAN device (AP, access point, transmission station) can simultaneously transmit data to two or more devices (terminal, reception station) using different frequency bands using OFDMA technology. Accordingly, it is possible to more efficiently use a wide bandwidth while maintaining backward compatibility for data transmission with devices using a narrow bandwidth.

1 is a conceptual diagram illustrating an embodiment of the configuration of an IEEE 802.11 wireless LAN system.
2 is a conceptual diagram illustrating an access process of a terminal in an infrastructure BSS.
3 is a conceptual diagram illustrating an embodiment of a data transmission process of an access point.
4 is a timing diagram illustrating an operation in which a transmitting station transmits a data unit to a plurality of receiving stations by dividing a bandwidth.
5 is a flowchart of an embodiment for explaining a method of operating a station in a wireless LAN according to the present invention.
6 is a conceptual diagram illustrating a HE-PPDU structure defined in IEEE 802.11ax, a wireless LAN standard.
7 is a conceptual diagram illustrating the HE-SIG-A field shown in FIG. 6 .
8 is a conceptual diagram for explaining an example of a scheduling information field included in the HE-SIG-A field.
9 is a conceptual diagram for explaining another example of a scheduling information field included in the HE-SIG-A field.
10 is a conceptual diagram for explaining another example of a scheduling information field included in the HE-SIG-A field.
11 is a conceptual diagram for explaining an example of an OFDMA PPDU generated by a transmitting station.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

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

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and 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 a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate the overall understanding, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

Throughout the specification, a station (STA) is a medium access control (MAC) conforming to the IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard and a physical layer for a wireless medium (medium). It means any functional medium including an interface. The station STA may be divided into a station STA that is an access point (AP) and a station STA that is a non-AP. A station (STA) that is an access point (AP) may be simply called an access point (AP), and a station (STA) that is a non-access point (non-AP) may simply be called a terminal.

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

Access point (AP) is centralized controller, base station (base station, BS), radio access station (radio access station), node B (node B), advanced node B (evolved node B), MMR (mobile multihop relay)-BS , a base transceiver system (BTS), or a site controller, and the like, and may include some or all functions thereof.

A terminal includes a wireless transmit/receive unit (WTRU), user equipment (UE), user terminal (UT), access terminal (AT), mobile station (MS), may refer to a mobile terminal, a subscriber unit, a subscriber station (SS), a wireless device, or a mobile subscriber unit, and the like, and some of them Or it can include all functions.

Here, a desktop computer, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a smart phone, a smart watch that can communicate with a terminal (smart watch), smart glass, e-book reader, PMP (Portable Multimedia Player), portable game console, navigation device, digital camera, DMB (Digital Multimedia Broadcasting) player, digital voice Digital audio recorder, digital audio player, digital picture recorder, digital picture player, digital video recorder, digital video player ) can be used.

1 is a conceptual diagram illustrating an embodiment of the configuration of an IEEE 802.11 wireless LAN system.

Referring to FIG. 1 , an IEEE 802.11 wireless LAN system includes at least one basic service set (BSS). BSS means a set of stations (STA 1, STA 2 (AP 1), STA 3, STA 4, STA 5 (AP 2)) that can communicate with each other through successful synchronization, and the concept of a specific area is not.

BSS can be divided into infrastructure BSS (infrastructure BSS) and independent BSS (IBSS), and BSS 1 and BSS 2 mean infrastructure BSS. BSS 1 connects a terminal (STA 1), an access point providing a distribution service (STA 2 (AP 1)), and a plurality of access points (STA 2 (AP 1), STA 5 (AP 2)) It may include a distribution system (Distribution System, DS). In BSS 1, the access point STA 2 (AP 1) may manage the terminal STA 1 .

BSS 2 connects terminals (STA 3, STA 4), an access point providing a distribution service (STA 5 (AP 2)), and a plurality of access points (STA 2 (AP 1), STA 5 (AP 2)). A distribution system may be included. In BSS 2, the access point STA 5 (AP 2) may manage the terminals STA 3 and STA 4 .

Meanwhile, the independent BSS is a BSS operating in an ad-hoc mode. Since the IBSS does not include an access point, there is no centralized management entity that performs a centralized management function. That is, in IBSS, terminals are managed in a distributed manner. In the IBSS, all terminals may be mobile terminals, and since access to the distribution system (DS) is not allowed, they form a self-contained network.

The access point (STA 2 (AP 1), STA 5 (AP 2)) provides access to the distributed system (DS) through the wireless medium for the terminals (STA 1, STA 3, STA 4) coupled thereto. can In BSS 1 or BSS 2, communication between terminals (STA 1, STA 3, STA 4) is generally made through an access point (STA 2 (AP 1), STA 5 (AP 2)), but a direct link (direct link), direct communication between terminals STA 1 , STA 3 , and STA 4 is possible.

A plurality of infrastructure BSSs may be interconnected through a distribution system (DS). A plurality of BSSs connected through a distribution system (DS) is called an extended service set (ESS). Stations included in the ESS can communicate with each other, and within the same ESS, a terminal can move from one BSS to another while communicating seamlessly.

The distribution system (DS) is a mechanism for one access point to communicate with another access point, and according to this, the access point transmits a frame for terminals connected to the BSS it manages, or moves to another BSS. A frame may be transmitted for any terminal. In addition, the access point may 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 if it can provide a predetermined distribution service stipulated in the IEEE 802.11 standard, there is no restriction on its form. For example, the distribution system may be a wireless network such as a mesh network or a physical structure that connects access points to each other.

The method of operating a transmitting station and a receiving station performed in a wireless LAN according to an embodiment of the present invention, which will be described later, can be applied to the above-described IEEE 802.11 wireless LAN system, and not only the IEEE 802.11 wireless LAN system but also a wireless personal area (WPAN) network), mobile Internet such as wireless body area network (WBAN), wireless broadband internet (WiBro) or world interoperability for microwave access (WiMax), global system for mobile communication (GSM) or 2G such as code division multiple access (CDMA) Mobile communication network, 3G mobile communication network such as wideband code division multiple access (WCDMA) or cdma2000, 3.5G mobile communication network such as high speed downlink packet access (HSDPA) or high speed uplink packet access (HSUPA), long term (LTE) evolution) or can be applied to various networks such as 4G mobile communication networks such as LTE-Advanced, and 5G mobile communication networks.

Next, the MAC frame format of the wireless LAN system will be described. The MAC frame is largely classified into a data frame, a management frame, and a control frame. The data frame includes data to be transmitted to the terminal, and is transmitted to the terminal from a higher layer. The management frame is used to support IEEE 802.11 services. Control frames are used to support transmission of data frames and management frames.

The management frame includes an association request frame, an association response frame, a reassociation request frame, a reassociation response frame, a probe request frame, and a probe response. ) frame, a beacon frame, an authentication frame, an action frame, and the like.

The control frame includes a block ACK request frame, a block ACK frame, a power save (PS)-Poll frame, a request to send (RTS) frame, a clear to send (CTS) frame, an ACK frame, and a contention free (CF)-End frame. It may mean a frame or the like.

2 is a conceptual diagram illustrating an access process of a terminal in an infrastructure BSS.

In order for the terminal (STA) to transmit and receive data in the infrastructure BSS, the terminal (STA) must first be connected to an access point (AP).

Referring to FIG. 2 , the access process of the terminal (STA) in the infrastructure BSS largely includes 1) a step of detecting an access point (AP) (probe step), 2) an authentication step with the detected access point (AP) (authentication step) ), and 3) an association step with an authenticated access point (AP).

The terminal (STA) may first detect neighboring access points (APs) through a detection process. The detection process is divided into a passive scanning method and an active scanning method. The passive scanning method may be performed by overhearing beacons transmitted by neighboring access points (APs). Meanwhile, the active scanning method may be performed by broadcasting a probe request frame. Upon receiving the probe request frame, the AP may transmit a probe response frame corresponding to the probe request frame to the corresponding terminal (STA). The terminal (STA) can know the existence of the neighboring access points (APs) by receiving the probe response frame.

Thereafter, the terminal (STA) may perform authentication with the detected access point (AP), and may perform authentication with a plurality of detected access points (APs). An authentication algorithm according to the IEEE 802.11 standard may be divided into an open system algorithm for exchanging two authentication frames and a shared key algorithm for exchanging four authentication frames. Through the process of exchanging an authentication request frame and an authentication response frame based on such an authentication algorithm, the terminal STA may perform authentication with the access point AP.

Finally, the terminal (STA) may select one access point (AP) from among a plurality of authenticated access points (APs), and may perform a connection process with the selected access point (AP). That is, the terminal (STA) transmits a connection request frame to the selected access point (AP), and the access point (AP) receiving the connection request frame transmits a connection response frame corresponding to the connection request frame to the corresponding terminal (STA). do. As described above, through the process of exchanging the connection request frame and the connection response frame, the terminal STA may perform a connection process with the access point AP.

3 is a conceptual diagram illustrating an embodiment of a data transmission process of an access point.

Referring to FIG. 3 , an access point (AP) periodically broadcasts a beacon, and may broadcast a beacon including a DTIM at three beacon intervals. The terminals (STA 1, STA 2) in the power save mode (PSM) periodically wake up to receive a beacon, check the TIM or DTIM included in the beacon, and the data to be transmitted to the access point is transmitted to the access point. Check if it is buffered. In this case, when buffered data exists, the terminals STA 1 and STA 2 maintain an awake state to receive data from the access point AP, and when there is no buffered data, the terminals STA 1 and STA 2 ) returns to the power saving state (ie, the doze state).

That is, when a bit in the TIM corresponding to its AID is set to 1, the terminals STA 1 and STA 2 are awake and ready to receive data with a PS-Poll frame (or trigger ( trigger) frame) to the access point (AP), and the access point (AP) confirms that the terminals (STA 1, STA 2) are ready for data reception by receiving the PS-Poll frame, and the terminal (STA 1) , STA 2) may transmit data or acknowledgment (ACK). When the ACK is transmitted to the terminals STA 1 and STA 2 , the access point AP may transmit data to the terminals STA 1 and STA 2 at an appropriate time. On the other hand, when the bit in the TIM corresponding to its own AID is set to 0, the terminals STA 1 and STA 2 return to the power saving state.

4 is a timing diagram illustrating an operation in which a transmitting station (eg, an AP) transmits a data unit to a plurality of receiving stations (eg, STA 1 and STA 2 ) by dividing a bandwidth.

4, the transmitting station (AP) using OFDMA (orthogonal frequency division multiplexing access) to the receiving stations (STA1 and STA2) respectively using a primary channel (primary channel) and a secondary channel (secondary channel) using This is an example of operation when data units are transmitted at the same time. L (legacy)-STF (short training field), L-LTF (long training field), L-SIG (signal) of OFDMA PPDU (physical layer convergence procedure (PLCP) protocol data unit) transmitted by the transmitting station (AP) A field and a high efficiency (HE)-SIG-A field are transmitted using both a primary channel and a secondary channel, and accordingly, the receiving stations STA1 and STA2 transmit the L-STF, L-LTF, L-SIG field and The HE-SIG-A field is received in the same way. In addition, the HE-SIG-B field and the data units DATA 1 and 2 are independently transmitted through each of the primary channel and the secondary channel, and the receiving stations STA1 and STA2 each correspond to a channel to be received by themselves. Only the HE-SIG-B field and data unit can be received. Stations that have received the HE-SIG-B field and data unit through a channel they can receive transmit ACK after short interframe space (SIFS) defined in the WLAN standard. In this case, the receiving stations STA1 and STA2 transmit ACKs through the channels of the data units they have received.

Since third stations (Others) other than the receiving stations (STA1 and STA2) can also receive the legacy preamble, the primary channel and the secondary channel are busy during the OFDMA PPDU period by the L-SIG field. busy) state can be recognized. In addition, although the ACKs transmitted by the receiving stations STA1 and STA2 respectively use different channels, they have data units of exactly the same content and length, and thus have the L-SIG field of the same content. For this reason, the third stations normally detect the L-SIG field, and can recognize that the primary channel and the secondary channel are busy during the ACK period. For the above operation, the HE-SIG-A field of the OFDMA PPDU contains information on whether the PPDU is an OFDMA PPDU, information on stations capable of receiving the OFDMA PPDU, and information on which channels each station can use. Included. As a method of notifying information on stations capable of receiving the corresponding PPDU, the transmitting station sets the stations simultaneously receiving the OFDMA PPDU into a group in advance, ID information of the OFDMA group is included. Stations that have received the OFDMA PPDU can confirm that the PPDU is a PPDU that they can receive if the Group ID included in the PPDU is identification information of the OFDMA group it includes.

5 is a flowchart of an embodiment for explaining a method of operating a station in a wireless LAN according to the present invention.

Referring to FIG. 5 , a transmitting station (that may be referred to as an access point (AP), an access point, a transmitting STA, etc.) pre-groups stations capable of receiving an OFDMA PPDU, and identifies the grouped receiving stations. Set identification information (group ID) for (S100). Grouping of receiving stations and setting of identification information may be performed according to periodic and aperiodic event occurrence. For example, a signal for group establishment may be periodically or aperiodically broadcast from the transmitting station to the receiving stations, and the same group identification information may be set for the receiving stations responding to the transmitted signal. Also, as the receiving station enters the service area of the transmitting station, group identification information for the receiving station may be set. FIG. 5 assumes that the grouped receiving stations are STA 1 to STA 4 .

After step S100, the transmitting station generates a legacy preamble of the OFDMA PPDU (S102).

6 is a conceptual diagram illustrating a HE-PPDU structure defined in IEEE 802.11ax, a wireless LAN standard.

Referring to FIG. 6 , the HE-PPDU may include a legacy preamble, an HE preamble, and a payload. The legacy preamble may include information for supporting timing synchronization, carrier offset recovery, and channel estimation performed by the station receiving the HE-PPDU.

The legacy preamble may include L-STF, L-LTF and L-SIG fields. L-STF is carrier sensing to detect that a signal is present in the channel currently used, and matches the radio signal input to the antenna to the operating area of the analog circuit and analog-to-digital converter. It may include information for automatic gain control and coarse carrier frequency offset correction. The L-LTF may include information for more precise frequency offset correction and symbol synchronization, an L-SIG field, and information for estimating a channel response for demodulation of the HE-SIG. By using repetitive sequences such as L-STF and L-LTF, various characteristics of a channel such as interference, Doppler, and delay spread can be estimated. The L-SIG may include control information necessary for a station receiving the HE-PPDU to demodulate the HE-PPDU. For example, L-SIG includes packet length, modulation coding schemes (MCS), bandwidth and channel encoding schemes, beamforming, space time block codes (STBC), smoothing, multiple-input multiple-output (MU-MIMO), and the like. Supporting information may be included.

After step S102, the transmitting station generates an HE preamble including scheduling information of a plurality of receiving stations (S104). The HE preamble may include information for supporting timing synchronization, carrier offset recovery, and channel estimation performed by the station receiving the HE-PPDU.

Referring to FIG. 6 , the HE preamble may include a HE-STF, at least one HE-LTF, a HE-SIG-A field, and a HE-SIG-B field. HE-STF and HE-LTF may include information corresponding to the aforementioned L-STF or L-LTF. In addition, the HE-SIG-A field and the HE-SIG-B field may separately include common control information and dedicated information required for a specific receiving station group, respectively.

The HE-SIG-A field includes information on whether the corresponding HE-PPDU is an OFDMA PPDU, group identification information for receiving stations capable of receiving the corresponding OFDMA PPDU, and scheduling information on which bands each receiving station uses. and the like.

7 is a conceptual diagram illustrating the HE-SIG-A field shown in FIG. 6 . Referring to FIG. 7 , it may include an OFDMA indicator field, a field related to group identification information (Group ID), a scheduling information field, and information fields belonging to the conventional HE-SIG-A field.

The OFDMA indicator field is an information field indicating that a transmission frame is transmitted in the OFDMA scheme, and when the corresponding HE-PPDU is an OFDMA transmission frame, OFDMA “ENABLE” information may be included.

In addition, the group identification information field is an identification information field of a group to which a plurality of reception stations belong, and may include information about a group ID in which reception stations capable of receiving an OFDMA PPDU are grouped. The station receiving the OFDMA PPDU may recognize that the PPDU is the PPDU it should receive if the group ID included in the PPDU is identification information of the OFDMA group it includes.

In addition, the scheduling information field may include a scheduling information field for a frequency band that each of the plurality of receiving stations can use.

8 is a conceptual diagram for explaining an example of a scheduling information field included in the HE-SIG-A field.

Referring to FIG. 8 , the scheduling information field may include information indicating a frequency band allocated to each of a plurality of reception stations. Here, the information indicating the frequency band is band information on a frequency that can be used for each reception station included in the OFDMA group among the bandwidths used in the BSS. Accordingly, if there are M receiving stations in one OFDMA group and the bandwidth used for the corresponding BSS consists of N unit bands, information indicating N frequency bands exists for each of the M receiving stations. Information indicating such a frequency band may be displayed as a bitmap. For example, it is assumed that the used bandwidth of the corresponding BSS is 80 MHz and corresponds to OFDMA enable. In addition, the bandwidth of the unit band is 20 MHz, the first station (STA[0]) of the OFDMA group uses the first 20 MHz, the second station (STA[1]) uses the next 40 MHz, and the third station (STA [ 2]) does not use this frequency band, and it is assumed that the fourth station (MU(3)) uses the last 20MHz. According to this assumption, the BW field of the HE-SIG-A field may include information of the bandwidth "80 MHz", the OFDMA field may include "ENABLE" information for OFDMA, and the group identification information field (Group ID ) may include a corresponding group ID, and the scheduling information field is information indicating a frequency band, and bitmap information "1000", "0110" for each of the stations (STA[0] to STA[3]) , "0000", and "0001". Accordingly, it can be seen from the bitmap information “1000” that the first station STA[0] can use 20 MHz corresponding to the first unit band among the 80 MHz bandwidth used. Also, it can be seen from the bitmap information "0110" that the second station (STA[1]) can use 40 MHz corresponding to the second and third unit bands among the 80 MHz bandwidth used. Also, from the bitmap information “0000”, the third station (STA[2]) can know that there is no usable band among the 80 MHz bandwidth. In addition, it can be seen from the bitmap information “0001” that the fourth station (STA[3]) can use 20 MHz corresponding to the last fourth unit band among the 80 MHz bandwidth used.

9 is a conceptual diagram for explaining another example of a scheduling information field included in the HE-SIG-A field.

Referring to FIG. 9 , the scheduling information field may include information indicating a bandwidth of a frequency band allocated to each of a plurality of receiving stations. Here, the information indicating the bandwidth means sequential bandwidth information on a frequency for a band usable for each reception station included in the OFDMA group among the bandwidths used in the BSS. For example, it is assumed that the bandwidth used for the BSS is 80 MHz and the bandwidth of the unit band is 20 MHz. In addition, the first station (STA[0]) of the OFDMA group uses the first 20 MHz, the second station (STA[1]) uses the next 40 MHz, and the third station (STA[2]) uses the frequency band not, it is assumed that the fourth station (STA [3]) uses the last 20 MHz. According to this assumption, the scheduling information field of the HE-SIG-A field is information indicating bandwidth for the stations (STA[0] to STA[3]), from STA[0] BW to STA[3] BW. Information of "20 MHz", "40 MHz", "0 MHz", and "20 MHz" may be included, respectively.

10 is a conceptual diagram for explaining another example of a scheduling information field included in the HE-SIG-A field.

Referring to FIG. 10 , the scheduling information field may include identification information of a plurality of reception stations allocated to each of a plurality of frequency bands. Here, the station identification information means identification information for each of the reception stations that can use each unit band in the bandwidth used in the BSS among the reception stations included in the OFDMA group. In this case, the station identification information may include an association identifier (AID), a partial association identifier (PAID), or a minimum unit identifier arbitrarily designated for the receiving station. The AID or PAID refers to information such as an ID allocated by a transmitting station to each of a plurality of receiving stations in the BSS. In addition, the arbitrarily designated minimum unit identifier means identification information expressed by the minimum number of bits for a plurality of receiving stations. For example, it is assumed that the bandwidth used for the BSS is 80 MHz and the bandwidth of the unit band is 20 MHz. In addition, the first station (STA[0]) of the OFDMA group uses the first 20 MHz, the second station (STA[1]) uses the next 40 MHz, and the third station (STA[2]) uses the frequency band not, it is assumed that the fourth station (STA [3]) uses the last 20 MHz. According to this assumption, the scheduling information field of the HE-SIG-A field is station identification information for unit bands (CH[0] STA to CH[3] STA), from CH[0] STA to CH[3] STA. up to and including information of “STA 0”, “STA 1”, “STA 1”, and “STA 3”, respectively.

After step S104, the transmitting station generates a PPDU including the legacy preamble, the HE preamble, and the payload (S106). The payload may include data units.

11 is a conceptual diagram for explaining an example of an OFDMA PPDU generated by a transmitting station.

Referring to FIG. 11 , each OFDMA PPDU to be transmitted through each of the unit bands CH 0 to CH 3 having a bandwidth of 80 MHz and a bandwidth of 20 MHz of the corresponding BSS is exemplified. The OFDMA PPDU to be transmitted through 20 MHz of the unit band CH 0 includes the same legacy preamble and HE-SIG-A field as other OFDMA PPDUs, and among the HE preambles, HE-STF 1, HE-LTF 1 _{1,.., n} , HE-SIG-B 1 field and DATA 1 may be included as unique fields. In addition, the OFDMA PPDU to be transmitted through 40 MHz of unit bands CH 1 and 2 includes the same legacy preamble and HE-SIG-A fields as other OFDMA PPDUs, and among HE preambles, HE-STF 2, HE-LTF 2 _{1, .., n} , HE-SIG-B 2 fields and DATA 2 may be included as unique fields. In addition, the OFDMA PPDU to be transmitted through 20MHz of the unit band CH 3 includes the same legacy preamble and HE-SIG-A fields as other OFDMA PPDUs, and among the HE preambles, HE-STF 3, HE-LTF 3 _{1,.. , n} , HE-SIG-B 3 fields and DATA 3 may be included as unique fields.

After step S106, the transmitting station transmits the generated PPDU to each receiving station in the OFDMA method (S108). Referring to FIG. 11, among the fields of the OFDMA PPDU, L-STF, L-LTF, and L-SIG fields corresponding to the legacy preamble and the HE-SIG-A field corresponding to the HE preamble include receiving stations (STA[0] to Commonly transmitted to STA[2]), the HE-STF, at least one HE-LTF, and HE-SIG-B field of the HE preamble and the data unit are transmitted to the respective receiving stations (STA[0] to STA[2] ) are transmitted individually.

After step S108, each of the receiving stations (that may be referred to as a terminal, a receiving STA, etc.) obtains a legacy preamble of the PPDU transmitted from the transmitting station (S110). Receiving stations may receive the PPDU in the OFDMA scheme, and may obtain a legacy preamble from among the received PPDUs. In this case, the acquired legacy preamble is information for supporting timing synchronization, carrier offset recovery, or channel estimation performed by the receiving station, and may include L-STF, L-LTF, and L-SIG fields.

After step S110, each of the receiving stations acquires the HE preamble of the PPDU (S112). The HE preamble may include a HE-SIG-A field, a HE-STF field, and at least one HE-LTF and HE-SIG-B field. In particular, the HE-SIG-A field may include an OFDMA indicator field as information for indicating whether the corresponding HE-PPDU is an OFDMA PPDU. In addition, the HE-SIG-A field may include a field regarding group identification information (Group ID) in which receiving stations capable of receiving OFDMA PPDUs are grouped. In addition, the HE-SIG-A field may include a scheduling information field for which band the station receiving the OFDMA PPDU can use. The scheduling information field may include information indicating a frequency band, information indicating a bandwidth of a frequency band, or station identification information for a plurality of receiving stations allocated to a plurality of frequency bands.

After step S112, each of the receiving stations acquires at least one data unit included in the payload of the PPDU through a resource indicated by scheduling information for a plurality of receiving stations included in the HE preamble (S114).

Each receiving station may acquire a data unit based on information indicating a frequency band allocated to each of the plurality of stations as information of the HE preamble. Information indicating such a frequency band may be displayed as a bitmap. Accordingly, if the information indicating the frequency band includes band information on a frequency that it can use, the receiving station may obtain a data unit included in the payload of the PPDU received through the corresponding frequency band.

Also, the receiving station may acquire the data unit based on information indicating the bandwidth of a frequency band allocated to each of the plurality of stations as information of the HE preamble. That is, if the receiving station determines that the bandwidth information is a bandwidth on a frequency that it can use, it may acquire a data unit included in the payload of a PPDU received through the corresponding bandwidth.

In addition, the receiving station may obtain the data unit based on identification information of the plurality of receiving stations allocated to each of the plurality of frequency bands as information of the HEW preamble. That is, when it is determined that the station identification information is identification information corresponding to the station identification information, the reception station may acquire a data unit included in the payload of the PPDU received through a frequency band corresponding to the station identification information.

After step S114, each of the receiving stations transmits an ACK to the transmitting station through the frequency band used by them after SIFS (S116). Accordingly, stations other than the receiving stations may recognize that they are busy with respect to frequency bands used by the receiving stations during the ACK period.

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

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

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

Claims (18)

A method of operating a station in a wireless LAN, comprising:
generating a legacy preamble;
generating a high efficiency (HE) preamble including scheduling information of a first receiving station and a second receiving station; and
generating a physical layer convergence procedure (PLCP) protocol data unit (PPDU) including the legacy preamble, the HE preamble, and a payload;
The scheduling information includes first information indicating a first frequency band allocated to the first reception station and second information indicating a second frequency band allocated to the second reception station. The method according to claim 1,
The HE preamble includes a HE-SIG (signal)-A field, a HE-STF (short training field), at least one HE-LTF (long training field) and a HE-SIG-B field. how it works. The method according to claim 1,
The HE preamble includes an indicator indicating that the PPDU is transmitted in an orthogonal frequency division multiplexing access (OFDMA) scheme. The method according to claim 1,
The HE preamble comprises identification information of a group to which the first receiving station and the second receiving station belong. delete The method according to claim 1,
The method of operating a station, wherein the scheduling information includes third information indicating the bandwidth of the first frequency band and fourth information indicating the bandwidth of the second frequency band. The method according to claim 1,
The method of operating a station, wherein the scheduling information includes identification information of the first receiving station and the second receiving station allocated to each of a plurality of frequency bands. 3. The method according to claim 2,
The method of operating a station, characterized in that the scheduling information is included in the HE-SIG-A field. The method according to claim 1,
The method of operating a station, characterized in that it further comprises the step of transmitting the PPDU in an orthogonal frequency division multiplexing access (OFDMA) scheme. A method of operating a station in a wireless LAN, comprising:
obtaining a legacy preamble of a physical layer convergence procedure (PLCP) protocol data unit (PPDU);
obtaining a high efficiency (HE) preamble of the PPDU; and
Obtaining at least one data unit included in the payload of the PPDU through a resource indicated by scheduling information for the first receiving station and the second receiving station included in the HE preamble includes,
The scheduling information includes first information indicating a first frequency band allocated to the first reception station and second information indicating a second frequency band allocated to the second reception station. 11. The method of claim 10,
The HE preamble includes a HE-SIG (signal)-A field, a HE-STF (short training field), at least one HE-LTF (long training field) and a HE-SIG-B field. how it works. 11. The method of claim 10,
The HE preamble includes an indicator indicating that the PPDU is transmitted in an orthogonal frequency division multiplexing access (OFDMA) scheme. 11. The method of claim 10,
The HE preamble comprises identification information of a group to which the first receiving station and the second receiving station belong. delete 11. The method of claim 10,
The method of operating a station, wherein the scheduling information includes third information indicating the bandwidth of the first frequency band and fourth information indicating the bandwidth of the second frequency band. 11. The method of claim 10,
The method of operating a station, wherein the scheduling information includes identification information of the first receiving station and the second receiving station allocated to each of a plurality of frequency bands. 12. The method of claim 11,
The method of operating a station, characterized in that the scheduling information is included in the HE-SIG-A field. 11. The method of claim 10,
The method of operating a station, characterized in that receiving the PPDU in an orthogonal frequency division multiplexing access (OFDMA) scheme.

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