WO2020116885A1 - Channel protection for preventing procedure delay - Google Patents

Abstract

In a wireless local area network system, a first type AP may transmit a first frame related to a channel sounding between a second type AP and a non-AP station (STA) to at least one second type AP for performing multi-AP transmission. The first type AP may receive, from the second type AP, a second frame related to a result on the channel sounding. The first frame may include a duration field, a value of the duration field is configured to protect a time interval from a first time point related to the first frame to a second time point related to the second frame, and the second time point may be a time point before a short inter frame space (SIFS) from the second frame.

Description

Channel protection to prevent procedural delay

The present specification relates to channel protection for preventing delay of a procedure for multi-access point (AP) transmission in a wireless local area network (LAN) system.

The wireless local area network (WLAN) has been improved in various ways. For example, the IEEE 802.11ax standard proposed an improved communication environment using orthogonal frequency division multiple access (OFDMA) and downlink multi-user multiple input (MIMO) techniques.

This specification proposes technical features that can be used in new communication standards. For example, the new communication standard may be an recently discussed extreme high throughput (EHT) standard. The EHT standard can use newly proposed increased bandwidth, improved PHY layer protocol data unit (PPDU) structure, improved sequence, and hybrid automatic repeat request (HARQ) technique. The EHT standard may be referred to as the IEEE 802.11be standard.

The method performed in a wireless local area network (WLAN) system according to various embodiments relates to a technical feature in which a first type AP protects a channel to prevent a process delay. For example, the first type AP transmits a first frame related to sounding of a channel between the second type AP and a non-AP STA (station) to at least one second type AP performing multi-AP transmission. Can transmit. In the first type AP, a second frame related to the sounding result of the channel may be received from the second type AP. The first frame may include a duration field, and a value of the duration field is a time interval from a first time point related to the first frame to a second time point related to the second frame. It is set to protect the, and the second time point may be a time point before the short inter frame space (SIFS) from the second frame.

According to an example according to the present specification, a series of procedures for multi-access point (AP) transmission may be performed without delay. For example, when a series of procedures for multi-AP transmission starts, a STA (station) may perform a series of procedures without delay by occupying a channel for a period of time until the series of procedures ends. Therefore, efficient communication may be possible.

1 shows an example of a transmitting device and/or a receiving device of the present specification.

2 is a conceptual diagram showing the structure of a wireless LAN (WLAN).

3 is a diagram for explaining a general link setup process.

4 is a diagram showing an example of a PPDU used in the IEEE standard.

5 is a diagram showing the arrangement of a resource unit (RU) used on a 20MHz band.

6 is a view showing the arrangement of a resource unit (RU) used on the 40MHz band.

7 is a view showing the arrangement of a resource unit (RU) used on the 80MHz band.

8 shows the structure of the HE-SIG-B field.

9 shows an example in which a plurality of User STAs are allocated to the same RU through the MU-MIMO technique.

10 shows the operation according to UL-MU.

11 shows an example of a trigger frame.

12 shows an example of a common information field of a trigger frame.

13 shows an example of a sub-field included in a per user information field.

14 describes the technical features of the UORA technique.

15 shows an example of channels used/supported/defined within the 2.4 GHz band.

16 shows an example of a channel used/supported/defined within a 5 GHz band.

17 shows an example of a channel used/supported/defined within a 6 GHz band.

18 shows an example of a PPDU used in the present specification.

19 to 21 are diagrams illustrating embodiments of a method of performing a pre-procedure in a wireless LAN system.

22 to 24 are diagrams illustrating embodiments of a method of protecting a time interval for performing a procedure in a WLAN system.

25 and 26 are flowcharts illustrating an embodiment of a signal transmission method using a multi-AP.

27 is a flowchart illustrating an embodiment of the operation of the first type AP.

28 is a flowchart for explaining an embodiment of the second type AP operation.

The slash (/) or comma (comma) used in this specification may mean “and/or”. For example, “A/B” means “A and/or B”, and thus may mean “only A” or “only B” or “one of A and B”. In addition, technical features that are individually described in one drawing may be individually or simultaneously implemented.

Also, parentheses used in the present specification may mean “for example”. Specifically, when indicated as “control information (EHT-Signal)”, “EHT-Signal” may be proposed as an example of “control information”. In addition, even when displayed as “control information (ie, EHT-signal)”, “EHT-signal” may be proposed as an example of “control information”.

The following example of the present specification can be applied to various wireless communication systems. For example, the following example of the present specification may be applied to a wireless local area network (WLAN) system. For example, this specification may be applied to the IEEE 802.11a/g/n/ac standard, or the IEEE 802.11ax standard. In addition, this specification may be applied to the newly proposed EHT standard or IEEE 802.11be standard. Also, an example of the present specification may be applied to a new wireless LAN standard that improves the EHT standard or IEEE 802.11be. Also, an example of the present specification may be applied to a mobile communication system. For example, it may be applied to a Long Term Evolution (LTE) based on the 3rd Generation Partnership Project (3GPP) standard and a mobile communication system based on its evolution. In addition, an example of the present specification may be applied to a 5G NR standard communication system based on the 3GPP standard.

Hereinafter, technical features to which the present specification can be applied will be described to describe the technical features of the present specification.

1 shows an example of a transmitting device and/or a receiving device of the present specification.

The example of FIG. 1 can perform various technical features described below. 1 includes two stations (STA). STA (110, 120) herein is a mobile terminal (mobile terminal), a wireless device (wireless device), a wireless transmit/receive unit (WTRU), user equipment (User Equipment; UE), mobile station (Mobile Station) ; MS), a mobile subscriber unit (Mobile Subscriber Unit) or simply a user (user), etc. can also be called various names. STAs 110 and 120 of the present specification may be referred to as various names such as a network, a base station, a Node-B, an access point (AP), a repeater, a router, and a relay. The STAs 110 and 120 of the present specification may be called various names such as a receiving device, a transmitting device, a receiving STA, a transmitting STA, a receiving device, and a transmitting device.

For example, the STAs 110 and 120 may perform an access point (AP) role or a non-AP role. That is, the STAs 110 and 120 of the present specification may perform functions of an AP and/or a non-AP. In this specification, the AP may also be indicated as an AP STA.

The STAs 110 and 120 of the present specification may support various communication standards other than the IEEE 802.11 standard. For example, it may support a communication standard (eg, LTE, LTE-A, 5G NR standard) according to the 3GPP standard. In addition, the STA of the present specification may be implemented with various devices such as a mobile phone, a vehicle, and a personal computer. In addition, the STA of the present specification may support communication for various communication services such as voice calls, video calls, data communication, and self-driving, autonomous-driving.

In this specification, the STAs 110 and 120 may include a medium access control (MAC) compliant with the IEEE 802.11 standard and a physical layer interface to a wireless medium.

The first STA 110 may include a processor 111, a memory 112, and a transceiver 113. The illustrated processor, memory, and transceiver may each be implemented as separate chips, or at least two or more blocks/functions may be implemented through one chip.

The transceiver 113 of the first STA performs a signal transmission/reception operation. Specifically, an IEEE 802.11 packet (eg, IEEE 802.11a/b/g/n/ac/ax/be, etc.) can be transmitted and received.

For example, the first STA 110 may perform an intended operation of the AP. For example, the processor 111 of the AP may receive a signal through the transceiver 113, process the received signal, generate a transmission signal, and perform control for signal transmission. The memory 112 of the AP may store a signal (ie, a received signal) received through the transceiver 113 and may store a signal (ie, a transmitted signal) to be transmitted through the transceiver.

For example, the second STA 120 may perform an intended operation of the Non-AP STA. For example, the non-AP transceiver 123 performs a signal transmission/reception operation. Specifically, an IEEE 802.11 packet (eg, IEEE 802.11a/b/g/n/ac/ax/be, etc.) can be transmitted and received.

For example, the processor 121 of the Non-AP STA may receive a signal through the transceiver 123, process the received signal, generate a transmission signal, and perform control for signal transmission. The memory 122 of the non-AP STA may store a signal (ie, a received signal) received through the transceiver 123 and may store a signal (ie, a transmitted signal) to be transmitted through the transceiver.

For example, the operation of the device indicated as the AP in the following specification may be performed in the first STA 110 or the second STA 120. For example, when the first STA 110 is an AP, the operation of the device indicated by the AP is controlled by the processor 111 of the first STA 110 and by the processor 111 of the first STA 110. Related signals may be transmitted or received via the controlled transceiver 113. In addition, control information related to the operation of the AP or the transmission/reception signal of the AP may be stored in the memory 112 of the first STA 110. In addition, when the second STA 110 is an AP, the operation of the device indicated by the AP is controlled by the processor 121 of the second STA 120 and controlled by the processor 121 of the second STA 120. The related signal may be transmitted or received through the transceiver 123. In addition, control information related to the operation of the AP or the transmission/reception signal of the AP may be stored in the memory 122 of the second STA 110.

For example, the operation of the device indicated as non-AP (or User-STA) in the following specification may be performed by the first STA 110 or the second STA 120. For example, when the second STA 120 is non-AP, the operation of the device indicated as non-AP is controlled by the processor 121 of the second STA 120, and the processor of the second STA 120 ( 121), a related signal may be transmitted or received through the transceiver 123 controlled by the controller. In addition, control information related to the operation of the non-AP or transmission/reception signals of the AP may be stored in the memory 122 of the second STA 120. For example, when the first STA 110 is non-AP, the operation of the device indicated as non-AP is controlled by the processor 111 of the first STA 110, and the processor of the first STA 120 ( The related signal may be transmitted or received through the transceiver 113 controlled by 111). In addition, control information related to the operation of the non-AP or the transmission/reception signal of the AP may be stored in the memory 112 of the first STA 110.

In the following specification, (transmission/reception) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmission/reception) Terminal, (transmission/reception) device , (Transmission/reception) apparatus, a device called a network, etc. may refer to the STAs 110 and 120 of FIG. 1. For example, without specific reference numerals (transmission/reception) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmission/reception) Terminal, (transmission /Reception) device, (transmission/reception) apparatus, and a device displayed as a network may also mean STAs 110 and 120 of FIG. 1. For example, in the following example, an operation in which various STAs transmit and receive signals (eg, PPPDUs) may be performed in the transceivers 113 and 123 of FIG. 1. In addition, in the following example, an operation in which various STAs generate a transmission/reception signal or perform data processing or calculation in advance for a transmission/reception signal may be performed in the processors 111 and 121 of FIG. 1. For example, an example of an operation of generating a transmission/reception signal or performing data processing or operation in advance for a transmission/reception signal is: 1) Determining bit information of a subfield (SIG, STF, LTF, Data) field included in a PPDU /Acquisition/Configuration/Calculation/Decoding/Encoding operation, 2) Time resource or frequency resource (for example, subcarrier resource) used for subfields (SIG, STF, LTF, Data) fields included in the PPDU. Determining/configuring/retrieving, 3) a specific sequence used for a subfield (SIG, STF, LTF, Data) field included in the PPDU (eg, pilot sequence, STF/LTF sequence, applied to SIG Extra sequence), etc., determining/configuring/acquiring, 4) power control and/or power saving operations applied to the STA, 5) ACK signal determination/acquisition/configuration/operation/decoding/encoding It can contain. In addition, in the following example, various STAs use various information used for determination/acquisition/configuration/operation/decoding/encoding of transmission/reception signals (for example, information related to fields/subfields/control fields/parameters/powers). It may be stored in the memory 112, 122 of FIG.

In this specification, the uplink may refer to a link for communication from a non-AP STA to an AP STA, and an uplink PPDU/packet/signal may be transmitted through the uplink. In addition, in this specification, the downlink may mean a link for communication from an AP STA to a non-AP STA, and a downlink PPDU/packet/signal may be transmitted through the downlink.

2 is a conceptual diagram showing the structure of a wireless LAN (WLAN).

The upper part of FIG. 2 shows the structure of an infrastructure basic service set (BSS) of the Institute of Electrical and Electronic Engineers (IEEE) 802.11.

Referring to the top of FIG. 2, the wireless LAN system may include one or more infrastructure BSSs 200 and 205 (hereinafter, BSS). The BSSs 200 and 205 are a set of APs and STAs such as an access point (AP) and STA1 (Station, 200-1) that can successfully communicate with each other by synchronizing, and are not a concept indicating a specific area. The BSS 205 may include one or more combineable STAs 205-1 and 205-2 in one AP 230.

The BSS may include at least one STA, APs 225 and 230 providing a distributed service, and a distributed system (DS, 210) connecting multiple APs.

The distributed system 210 may connect multiple BSSs 200 and 205 to implement an extended service set (ESS) 240. The ESS 240 may be used as a term indicating one network formed by connecting one or several APs through the distributed system 210. APs included in one ESS 240 may have the same service set identification (SSID).

The portal (portal, 220) may serve as a bridge that performs a connection between a wireless LAN network (IEEE 802.11) and another network (eg, 802.X).

In the BSS such as the top of FIG. 2, a network between APs 225 and 230 and a network between APs 225 and 230 and STAs 200-1, 205-1 and 205-2 may be implemented. However, it may be possible to establish a network between STAs without APs 225 and 230 to perform communication. A network that establishes a network even among STAs without APs 225 and 230 to perform communication is defined as an ad-hoc network or an independent basic service set (BSS).

2 is a conceptual diagram showing IBSS.

2, IBSS is a BSS operating in an ad-hoc mode. Since IBSS does not include an AP, there is no centralized management entity performing central management functions. That is, STAs 250-1, 250-2, 250-3, 255-4, and 255-5 in IBSS are managed in a distributed manner. In IBSS, all STAs (250-1, 250-2, 250-3, 255-4, 255-5) can be made of mobile STAs, and access to a distributed system is not allowed, so a self-contained network (self-contained) network).

3 is a diagram for explaining a general link setup process.

In step S310, the STA may perform a network discovery operation. The network discovery operation may include a scanning operation of the STA. That is, in order for the STA to access the network, it is necessary to find a network to participate. The STA must identify a compatible network before joining a wireless network, and the network identification process existing in a specific area is called scanning. The scanning methods include active scanning and passive scanning.

3 illustrates a network discovery operation that includes an active scanning process by way of example. In active scanning, the STA performing scanning transmits a probe request frame and waits for a response to search for which AP is present while moving channels. The responder transmits a probe response frame to the STA that has transmitted the probe request frame in response to the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In the BSS, since the AP transmits the beacon frame, the AP becomes a responder, and in the IBSS, the STAs in the IBSS rotate and transmit the beacon frame, so the responder is not constant. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 stores BSS-related information included in the received probe response frame, and then transmits the next channel (for example, number 2). Channel) to perform scanning (ie, probe request/response transmission/reception on channel 2) in the same way.

Although not shown in the example of FIG. 3, the scanning operation may be performed by a passive scanning method. An STA performing scanning based on passive scanning may wait for a beacon frame while moving channels. The beacon frame is one of management frames in IEEE 802.11, and is periodically transmitted to inform the presence of the wireless network and allow STAs performing scanning to find the wireless network and participate in the wireless network. In the BSS, the AP serves to periodically transmit the beacon frame, and in the IBSS, STAs in the IBSS rotate and transmit the beacon frame. Upon receiving the beacon frame, the STA performing scanning stores information on the BSS included in the beacon frame and records beacon frame information in each channel while moving to another channel. The STA receiving the beacon frame may store BSS-related information included in the received beacon frame and move to the next channel to perform scanning in the next channel in the same manner.

The STA discovering the network may perform an authentication process through step SS320. Such an authentication process may be referred to as a first authentication process in order to clearly distinguish the security setup operation of step S340, which will be described later. The authentication process of S320 may include a process in which the STA sends an authentication request frame to the AP, and in response, the AP sends an authentication response frame to the STA. The authentication frame used for authentication request/response corresponds to a management frame.

The authentication frame includes the authentication algorithm number, authentication transaction sequence number, status code, challenge text, robust security network (RSN), and finite cycle group (Finite Cyclic). Group).

The STA may transmit an authentication request frame to the AP. The AP may determine whether to allow authentication for the corresponding STA based on the information included in the received authentication request frame. The AP may provide the result of the authentication process to the STA through the authentication response frame.

The successfully authenticated STA may perform a connection process based on step S330. The connection process includes a process in which the STA transmits an association request frame to the AP, and in response, the AP transmits an association response frame to the STA. For example, the connection request frame includes information related to various capabilities, beacon listening interval, service set identifier (SSID), supported rates, supported channels, RSN, and mobility domain. , Supported operating classes, TIM broadcast request, and information on interworking service capabilities. For example, the connection response frame includes information related to various capabilities, status codes, association ID (AID), support rate, (Enhanced Distributed Channel Access) parameter set, received channel power indicator (RCPI), and received signal to noise indicator (RSNI). ), mobility domain, timeout interval (association comeback time), overlapping (overlapping) BSS scan parameters, TIM broadcast response, QoS map, and other information.

Thereafter, in step S340, the STA may perform a security setup process. The security setup process of step S340 may include, for example, a process of performing private key setup through 4-way handshaking through an Extensible Authentication Protocol over LAN (EAPOL) frame. .

4 is a diagram showing an example of a PPDU used in the IEEE standard.

As illustrated, various types of PHY protocol data units (PPDUs) have been used in standards such as IEEE a/g/n/ac. Specifically, the LTF and STF fields included a training signal, and SIG-A and SIG-B included control information for the receiving station, and the data field contained user data corresponding to PSDU (MAC PDU/Aggregated MAC PDU). Was included.

4 also includes an example of the HE PPDU of the IEEE 802.11ax standard. The HE PPDU according to FIG. 4 is an example of a PPDU for multiple users, and HE-SIG-B is included only for multiple users, and the corresponding HE-SIG-B may be omitted in the PPDU for a single user.

As shown, HE-PPDU for multiple users (MU) is a legacy-short training field (L-STF), legacy-long training field (L-LTF), legacy-signal (L-SIG), High efficiency-signal A (HE-SIG-A), high efficiency-signal-B (HE-SIG-B), high efficiency-short training field (HE-STF), high efficiency-long training field (HE-LTF) , Data field (or MAC payload) and PE (Packet Extension) field. Each field can be transmitted during the illustrated time period (ie, 4 or 8 ms, etc.).

Hereinafter, a resource unit (RU) used in the PPDU will be described. The resource unit may include a plurality of subcarriers (or tones). The resource unit may be used when transmitting signals to multiple STAs based on the OFDMA technique. Also, a resource unit may be defined when transmitting a signal to one STA. Resource units can be used for STF, LTF, data fields, and the like.

5 is a diagram showing the arrangement of a resource unit (RU) used on a 20MHz band.

As illustrated in FIG. 5, Resource Units (RUs) corresponding to different numbers of tones (ie, subcarriers) may be used to configure some fields of the HE-PPDU. For example, resources may be allocated in units of RU shown for HE-STF, HE-LTF, and data fields.

As shown at the top of Fig. 5, 26-units (i.e., units corresponding to 26 tones) can be arranged. Six tones may be used as a guard band in the leftmost band of the 20 MHz band, and five tones may be used as a guard band in the rightmost band of the 20 MHz band. In addition, 7 DC tones are inserted into the central band, that is, the DC band, and 26-units corresponding to 13 tones may exist in the left and right sides of the DC band. In addition, 26-units, 52-units, and 106-units may be allocated to other bands. Each unit can be assigned for a receiving station, ie a user.

Meanwhile, the RU arrangement of FIG. 5 is utilized not only for a situation for multiple users (MU), but also for a situation for single users (SU). In this case, as shown in the bottom of FIG. It is possible to use and in this case 3 DC tones can be inserted.

In the example of FIG. 5, various sizes of RUs, that is, 26-RU, 52-RU, 106-RU, 242-RU, and the like are proposed. Since the specific size of these RUs can be expanded or increased, this embodiment Is not limited to the specific size of each RU (ie the number of corresponding tones).

6 is a view showing the arrangement of a resource unit (RU) used on the 40MHz band.

Just as RUs of various sizes are used in the example of FIG. 5, examples of FIG. 6 may also be 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, and the like. In addition, 5 DC tones can be inserted into the center frequency, 12 tones are used as a guard band in the leftmost band of the 40 MHz band, and 11 tones are used in a rightmost band of the 40 MHz band. It can be used as a guard band.

Also, as shown, when used for a single user, 484-RU can be used. Meanwhile, the fact that the specific number of RUs can be changed is the same as the example of FIG. 4.

7 is a view showing the arrangement of a resource unit (RU) used on the 80MHz band.

Just as RUs of various sizes are used in the examples of FIGS. 5 and 6, examples of FIG. 7 may also be 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, 996-RU, etc. have. In addition, 7 DC tones can be inserted into the center frequency, 12 tones are used in the leftmost band of the 80 MHz band as a guard band, and 11 tones are located in the rightmost band of the 80 MHz band. It can be used as a guard band. It is also possible to use 26-RUs with 13 tones located on the left and right sides of the DC band.

Also, as shown, when used for a single user, 996-RU can be used, in which case 5 DC tones can be inserted.

Meanwhile, the fact that the specific number of RUs can be changed is the same as the example of FIGS. 5 and 6.

The RU arrangement (ie, RU location) shown in FIGS. 5 to 7 may be applied to a new wireless LAN system (eg, EHT system) as it is. Meanwhile, in the 160 MHz band supported by the new WLAN system, the arrangement of the RU for 80 MHz (that is, the example of FIG. 7) is repeated twice or the arrangement of the RU for 40 MHz (that is, the example of FIG. 6) is 4 times It can be repeated. In addition, when the EHT PPDU is configured in the 320 MHz band, the arrangement of RUs for 80 MHz (example of FIG. 7) may be repeated 4 times or the arrangement of RUs for 40 MHz (ie, example of FIG. 6) may be repeated 8 times. have.

One RU in this specification may be allocated for only one STA (eg, non-AP). Or, a plurality of RUs may be allocated for one STA (eg, non-AP).

The RU described herein may be used for UL (Uplink) communication and DL (Downlink) communication. For example, when UL-MU communication solicited by a trigger frame is performed, the transmitting STA (eg, AP) transmits a first RU to the first STA through the trigger frame (eg, 26/52/106 /242-RU, etc.), and the second STA may be assigned a second RU (eg, 26/52/106/242-RU, etc.). Thereafter, the first STA may transmit the first Trigger-based PPDU based on the first RU, and the second STA may transmit the second Trigger-based PPDU based on the second RU. The first/second trigger-based PPDU is transmitted to the AP in the same time interval.

For example, when a DL MU PPDU is configured, the transmitting STA (eg, AP) allocates a first RU (eg, 26/52/106/242-RU, etc.) to the first STA, and A second RU (for example, 26/52/106/242-RU, etc.) may be allocated to the 2 STAs. That is, the transmitting STA (for example, the AP) can transmit the HE-STF, HE-LTF, and Data fields for the first STA through the first RU in one MU PPDU, and the second STA through the second RU. The HE-STF, HE-LTF, and Data fields for 2 STAs may be transmitted.

Information on the arrangement of the RU may be signaled through HE-SIG-B.

8 shows the structure of the HE-SIG-B field.

As shown, the HE-SIG-B field 810 includes a common field 820 and a user-specific field 830. The common field 820 may include information commonly applied to all users (ie, user STAs) receiving SIG-B. The user-individual field 830 may be referred to as a user-individual control field. The user-individual field 830 may be applied to only some of a plurality of users when SIG-B is delivered to a plurality of users.

8, the common field 920 and the user-individual field 930 may be separately encoded.

The common field 920 may include N*8 bits of RU allocation information. For example, the RU allocation information may include information regarding the location of the RU. For example, when a 20 MHz channel is used as shown in FIG. 5, the RU allocation information may include information on which RU (26-RU/52-RU/106-RU) is arranged in which frequency band. .

An example of the case where the RU allocation information is composed of 8 bits is as follows.

As in the example of FIG. 5, up to nine 26-RUs may be allocated to a 20 MHz channel. When RU allocation information of the common field 820 is set as “00000000” as shown in Table 8, nine 26-RUs may be allocated to the corresponding channel (ie, 20 MHz). In addition, when RU allocation information of the common field 820 is set as “00000001” as shown in Table 1, seven 26-RUs and one 52-RU are arranged in corresponding channels. That is, in the example of FIG. 5, 52-RU is allocated on the right-most side and seven 26-RU are allocated on the left side.

An example of Table 1 shows only a part of RU locations that can be displayed by RU allocation information.

For example, RU allocation information may include an example of Table 2 below.

“01000y2y1y0” is related to an example in which 106-RU is allocated to the left-most side of a 20 MHz channel, and 5 26-RU are allocated to the right side. In this case, a number of STAs (eg, User-STA) may be assigned to the 106-RU based on the MU-MIMO technique. Specifically, for the 106-RU, up to 8 STAs (eg, User-STA) can be allocated, and the number of STAs (eg, User-STA) allocated to the 106-RU is 3 bit information (y2y1y0) ). For example, when the 3-bit information (y2y1y0) is set to N, the number of STAs (eg, User-STA) allocated to the 106-RU based on the MU-MIMO technique may be N+1.

In general, a plurality of different STAs (eg, User STAs) may be assigned to a plurality of RUs. However, for one RU having a specific size (eg, 106 subcarriers) or more, a plurality of STAs (eg, User STAs) may be allocated based on the MU-MIMO technique.

As illustrated in FIG. 8, the user-individual field 830 may include a plurality of user fields. As described above, the number of STAs (eg, User STAs) allocated to a specific channel may be determined based on RU allocation information of the common field 820. For example, when the RU allocation information of the common field 820 is "00000000", one User STA may be allocated to each of the nine 26-RUs (that is, a total of nine User STAs are allocated). That is, up to 9 User STAs may be allocated to a specific channel through OFDMA. In other words, up to 9 User STAs can be assigned to a specific channel through a non-MU-MIMO technique.

For example, when the RU allocation is set to “01000y2y1y0”, a plurality of User STAs are allocated through the MU-MIMO technique to 106-RUs disposed at the left-most side, and five 26-RUs disposed at the right side thereof. Five user STAs may be allocated through a non-MU-MIMO technique. This case is embodied through the example of FIG. 9.

9 shows an example in which a plurality of User STAs are allocated to the same RU through the MU-MIMO technique.

For example, when RU allocation is set to “01000010” as shown in FIG. 9, based on Table 2, 106-RU is allocated to the left-most of a specific channel and 5 26-RU are allocated to the right. Can be. In addition, a total of three User STAs can be allocated to the 106-RU through the MU-MIMO technique. As a result, since a total of 8 User STAs are allocated, the user-individual field 830 of HE-SIG-B may include 8 User fields.

Eight User fields may be included in the order shown in FIG. 9. Also, as illustrated in FIG. 8, two user fields may be implemented as one user block field.

The user fields illustrated in FIGS. 8 and 9 may be configured based on two formats. That is, the User field related to the MU-MIMO technique may be configured in the first format, and the User field related to the non-MU-MIMO technique may be configured in the second format. Referring to the example of FIG. 9, User fields 1 to User field 3 may be based on the first format, and User fields 4 to User Field 8 may be based on the second format. The first format or the second format may include bit information of the same length (for example, 21 bits).

Each User field may have the same size (for example, 21 bits). For example, the User Field of the first format (format of MU-MIMO technique) may be configured as follows.

For example, the first bit (eg, B0-B10) in the User field (ie, 21 bits) is the identification information of the User STA to which the corresponding User field is assigned (eg, STA-ID, partial AID, etc.) It may include. Also, the second bit (eg, B11-B14) in the User field (ie, 21 bits) may include information regarding spatial configuration. Specifically, an example of the second bit (ie, B11-B14) may be as shown in Tables 3 to 4 below.

As shown in Table 3 and/or Table 4, the second bit (that is, B11-B14) may include information on the number of spatial streams allocated to a plurality of User STAs allocated according to the MU-MIMO technique. have. For example, when three User STAs are allocated to the 106-RU based on the MU-MIMO scheme as shown in FIG. 9, N_user is set to “3”, and accordingly, N_STS[1] as shown in Table 3, The values of N_STS[2] and N_STS[3] can be determined. For example, when the value of the second bit (B11-B14) is “0011”, N_STS[1]=4, N_STS[2]=1, and N_STS[3]=1. That is, in the example of FIG. 9, four spatial streams may be allocated to user field 1, one spatial stream may be allocated to user field 2, and one spatial stream may be allocated to user field 3.

As in the example of Table 3 and/or Table 4, information about the number of spatial streams for the user station (user STA) (ie, the second bit, B11-B14) may be composed of 4 bits. In addition, information on the number of spatial streams for the user station (user STA) (ie, the second bit, B11-B14) may support up to eight spatial streams. In addition, information on the number of spatial streams (ie, second bits, B11-B14) may support up to four spatial streams for one User STA.

Also, the third bit (ie, B15-18) in the User field (ie, 21 bits) may include Modulation and Coding Scheme (MCS) information. MCS information can be applied to a data field in a PPDU that includes the corresponding SIG-B.

The MCS, MCS information, MCS index, and MCS field used in this specification may be indicated by specific index values. For example, MCS information may be indicated by index 0 to index 11. The MCS information includes information on the constellation modulation type (eg, BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM, etc.), and coding rate (eg, 1/2, 2/ 3, 3/4, 5/6, etc.). Information on the channel coding type (eg, BCC or LDPC) may be excluded from the MCS information.

Also, the fourth bit (ie, B19) in the User field (ie, 21 bits) may be a Reserved field.

In addition, the fifth bit (ie, B20) in the User field (ie, 21 bits) may include information regarding a coding type (eg, BCC or LDPC). That is, the fifth bit (ie, B20) may include information about the type of channel coding (eg, BCC or LDPC) applied to the data field in the PPDU including the corresponding SIG-B.

The above-described example relates to the User Field of the first format (format of MU-MIMO technique). An example of the User field in the second format (format of a non-MU-MIMO technique) is as follows.

The first bit (eg, B0-B10) in the User field of the second format may include identification information of the User STA. Also, the second bit (eg, B11-B13) in the user field of the second format may include information on the number of spatial streams applied to the corresponding RU. In addition, the third bit (eg, B14) in the user field of the second format may include information on whether a beamforming steering matrix is applied. The fourth bit (eg, B15-B18) in the User field of the second format may include Modulation and Coding Scheme (MCS) information. In addition, the fifth bit (eg, B19) in the User field of the second format may include information about whether DCM (Dual Carrier Modulation) is applied. Also, the sixth bit (ie, B20) in the User field of the second format may include information regarding a coding type (eg, BCC or LDPC).

10 shows the operation according to UL-MU. As illustrated, the transmitting STA (eg, AP) may perform channel access through contending (ie, backoff operation) and transmit a trigger frame 1030. That is, the transmitting STA (eg, AP) may transmit the PPDU including the Trigger Frame 1330. When a PPDU including a trigger frame is received, a trigger-based (TB) PPDU is transmitted after a delay of SIFS.

TB PPDUs 1041 and 1042 may be transmitted at the same time, and may be transmitted from a plurality of STAs (eg, User STAs) whose AIDs are indicated in the Trigger frame 1030. The ACK frame 1050 for the TB PPDU may be implemented in various forms.

The specific features of the trigger frame are described with reference to FIGS. 11 to 13. Even when UL-MU communication is used, an orthogonal frequency division multiple access (OFDMA) technique or MU MIMO technique may be used, and OFDMA and MU MIMO techniques may be used simultaneously.

11 shows an example of a trigger frame. The trigger frame of FIG. 11 allocates resources for uplink multiple-user transmission (MU) transmission, and may be transmitted, for example, from an AP. The trigger frame may consist of a MAC frame and may be included in the PPDU.

Each field illustrated in FIG. 11 may be partially omitted, and other fields may be added. Also, the length of each field may be changed differently from that shown.

The frame control field 1110 of FIG. 11 includes information on the version of the MAC protocol and other additional control information, and the duration field 1120 is time information for NAV setting or an identifier of the STA (eg For example, AID) may be included.

In addition, the RA field 1130 includes address information of a receiving STA of a corresponding trigger frame, and may be omitted if necessary. The TA field 1140 includes address information of an STA (eg, AP) that transmits the trigger frame, and the common information field 1150 is applied to a receiving STA that receives the trigger frame. Contains control information. For example, a field indicating the length of the L-SIG field of the uplink PPDU transmitted corresponding to the trigger frame or a SIG-A field of the uplink PPDU transmitted corresponding to the trigger frame (ie, HE-SIG-A Field). In addition, as the common control information, information on the length of the CP of the uplink PPDU transmitted corresponding to the trigger frame or information on the length of the LTF field may be included.

In addition, it is preferable to include individual user information (per user information) fields 1160#1 to 1160#N corresponding to the number of receiving STAs receiving the trigger frame of FIG. 11. The individual user information field may be referred to as an “assignment field”.

In addition, the trigger frame of FIG. 11 may include a padding field 1170 and a frame check sequence field 1180.

Each of the individual user information fields 1160#1 to 1160#N illustrated in FIG. 11 may include a plurality of subfields again.

12 shows an example of a common information field of a trigger frame. Some of the subfields of FIG. 12 may be omitted, and other subfields may be added. Also, the length of each of the illustrated sub-fields can be changed.

The illustrated length field 1210 has the same value as the length field of the L-SIG field of the uplink PPDU transmitted corresponding to the corresponding trigger frame, and the length field of the L-SIG field of the uplink PPDU indicates the length of the uplink PPDU. As a result, the length field 1210 of the trigger frame can be used to indicate the length of the corresponding uplink PPDU.

In addition, the cascade indicator field 1220 indicates whether a cascade operation is performed. Cascade operation means that downlink MU transmission and uplink MU transmission are performed together in the same TXOP. That is, after the downlink MU transmission is performed, it means that the uplink MU transmission is performed after a predetermined time (for example, SIFS). During the casecade operation, only one transmission device (eg, AP) performing downlink communication may exist, and a plurality of transmission devices (eg, non-AP) performing uplink communication may exist.

The CS request field 1230 indicates whether a state of a radio medium or NAV should be considered in a situation in which a receiving device that has received a corresponding trigger frame transmits a corresponding uplink PPDU.

The HE-SIG-A information field 1240 may include information that controls the content of the SIG-A field (that is, the HE-SIG-A field) of the uplink PPDU transmitted corresponding to the trigger frame.

The CP and LTF type field 1250 may include information on the length and CP length of the LTF of the uplink PPDU transmitted corresponding to the corresponding trigger frame. The trigger type field 1060 may indicate the purpose for which the corresponding trigger frame is used, for example, normal triggering, triggering for beamforming, request for Block ACK/NACK, and the like.

In the present specification, it can be assumed that the trigger type field 1260 of the trigger frame indicates a basic type trigger frame for normal triggering. For example, a basic type trigger frame may be referred to as a basic trigger frame.

13 shows an example of a sub-field included in a per user information field. The user information field 1300 of FIG. 13 may be understood as any one of the individual user information fields 1160#1 to 1160#N mentioned in FIG. 11. Some of the subfields included in the user information field 1300 of FIG. 13 may be omitted, and other subfields may be added. Also, the length of each of the illustrated sub-fields can be changed.

The user identifier (User Identifier) field 1310 of FIG. 13 represents an identifier of an STA (ie, a receiving STA) corresponding to per user information, and an example of the identifier is an association identifier (AID) of the receiving STA It can be all or part of the value.

Also, a RU Allocation field 1320 may be included. That is, when the receiving STA identified by the user identifier field 1310 transmits the TB PPDU in response to the trigger frame, the TB PPDU is transmitted through the RU indicated by the RU allocation field 1320. In this case, the RU indicated by the RU Allocation field 1320 may be the RU shown in FIGS. 5, 6, and 7.

The sub-field of FIG. 13 may include a coding type field 1330. The coding type field 1330 may indicate a coding type of TB PPDU. For example, when BCC coding is applied to the TB PPDU, the coding type field 1330 may be set to '1', and when LDPC coding is applied, the coding type field 1330 may be set to '0'. have.

Also, the sub-field of FIG. 13 may include an MCS field 1340. The MCS field 1340 may indicate an MCS technique applied to TB PPDU. For example, when BCC coding is applied to the TB PPDU, the coding type field 1330 may be set to '1', and when LDPC coding is applied, the coding type field 1330 may be set to '0'. have.

Hereinafter, a UORA (UL OFDMA-based random access) technique will be described.

14 describes the technical features of the UORA technique.

The transmitting STA (eg, AP) may allocate 6 RU resources as illustrated in FIG. 14 through a trigger frame. Specifically, the AP includes first RU resources (AID 0, RU 1), second RU resources (AID 0, RU 2), third RU resources (AID 0, RU 3), and fourth RU resources (AID 2045, RU) 4), the fifth RU resource (AID 2045, RU 5), the sixth RU resource (AID 3, RU 6) can be allocated. Information regarding AID 0, AID 3, or AID 2045 may be included, for example, in the user identification field 1310 of FIG. 13. Information about RU 1 to RU 6 may be included in the RU allocation field 1320 of FIG. 13, for example. AID=0 may refer to a UORA resource for an associated STA, and AID=2045 may refer to a UORA resource for an un-associated STA. Accordingly, the first to third RU resources of FIG. 14 may be used as a UORA resource for an associated STA, and the fourth to fifth RU resources of FIG. 14 for a non-associated STA It may be used as a UORA resource, and the sixth RU resource of FIG. 14 may be used as a resource for a normal UL MU.

In the example of FIG. 14, the ODMA (OFDMA random access BackOff) counter of STA1 is decreased to 0, so that STA1 randomly selects the second RU resources (AID 0 and RU 2). In addition, since the OBO counter of STA2/3 is larger than 0, uplink resources are not allocated to STA2/3. In addition, in FIG. 14, since the STA4 includes its own AID (that is, AID=3) in the trigger frame, resources of RU 6 are allocated without backoff.

Specifically, since STA1 in FIG. 14 is an associated STA, there are a total of 3 eligible RA RUs for STA1 (RU 1, RU 2, and RU 3), and accordingly, STA1 decreases the OBO counter by 3, resulting in an OBO counter. It became zero. In addition, since STA2 in FIG. 14 is an associated STA, there are a total of 3 eligible RA RUs for STA2 (RU 1, RU 2, RU 3), and accordingly, STA2 reduces the OBO counter by 3, but the OBO counter is 0. It is in a larger state. In addition, since STA3 of FIG. 14 is a non-associated STA, there are a total of two eligible RA RUs for STA3 (RU 4 and RU 5), and accordingly, STA3 reduces the OBO counter by 2, but the OBO counter is It is greater than zero.

15 shows an example of channels used/supported/defined within the 2.4 GHz band.

The 2.4 GHz band may be referred to by other names such as the first band (band). In addition, the 2.4 GHz band may mean a frequency range in which channels having a center frequency adjacent to 2.4 GHz (eg, channels having a center frequency within 2.4 to 2.5 GHz) are used/supported/defined.

The 2.4 GHz band may include multiple 20 MHz channels. 20 MHz in the 2.4 GHz band may have multiple channel indices (eg, index 1 to index 14). For example, the center frequency of a 20 MHz channel to which channel index 1 is allocated may be 2.412 GHz, the center frequency of a 20 MHz channel to which channel index 2 is allocated may be 2.417 GHz, and the 20 MHz to which channel index N is allocated. The center frequency of the channel may be (2.407 + 0.005*N) GHz. The channel index may be called various names such as a channel number. The specific values of the channel index and the center frequency can be changed.

15 exemplarily shows four channels in the 2.4 GHz band. The illustrated first frequency domain 1510 to the fourth frequency domain 1540 may each include one channel. For example, the first frequency domain 1510 may include a channel 1 (a 20 MHz channel having an index 1). At this time, the center frequency of channel 1 may be set to 2412 MHz. The second frequency domain 1520 may include channel 6. At this time, the center frequency of channel 6 may be set to 2437 MHz. The third frequency domain 1530 may include channel 11. At this time, the center frequency of the channel 11 may be set to 2462 MHz. The fourth frequency domain 1540 may include channel 14. At this time, the center frequency of the channel 14 may be set to 2484 MHz.

16 shows an example of a channel used/supported/defined within a 5 GHz band.

The 5 GHz band may be referred to by other names such as the second band/band. The 5 GHz band may refer to a frequency range in which channels having a center frequency of 5 GHz or more and less than 6 GHz (or less than 5.9 GHz) are used/supported/defined. Alternatively, the 5 GHz band may include a plurality of channels between 4.5 GHz and 5.5 GHz. The specific numerical values shown in FIG. 16 may be changed.

A plurality of channels in the 5 GHz band includes UNII (Unlicensed National Information Infrastructure)-1, UNII-2, UNII-3, and ISM. UNII-1 can be called UNII Low. UNII-2 may include frequency domains called UNII Mid and UNII-2Extended. UNII-3 can be called UNII-Upper.

Multiple channels may be set in the 5 GHz band, and the bandwidth of each channel may be variously set to 20 MHz, 40 MHz, 80 MHz, or 160 MHz. For example, the 5170 MHz to 5330 MHz frequency range/range in UNII-1 and UNII-2 may be divided into eight 20 MHz channels. The 5170 MHz to 5330 MHz frequency domain/range can be divided into four channels through the 40 MHz frequency domain. The 5170 MHz to 5330 MHz frequency domain/range may be divided into two channels through the 80 MHz frequency domain. Alternatively, the 5170 MHz to 5330 MHz frequency domain/range may be divided into one channel through the 160 MHz frequency domain.

17 shows an example of a channel used/supported/defined within a 6 GHz band.

The 6 GHz band may be referred to by other names such as third band/band. The 6 GHz band may mean a frequency domain in which channels with a center frequency of 5.9 GHz or higher are used/supported/defined. The specific numerical values shown in FIG. 17 may be changed.

For example, the 20 MHz channel of FIG. 17 may be defined from 5.940 GHz. Specifically, among the 20 MHz channels of FIG. 17, the left-most channel may have an index 1 (or a channel index, a channel number, etc.), and a center frequency of 5.945 GHz may be allocated. That is, the center frequency of the index N channel may be determined as (5.940 + 0.005*N) GHz.

Accordingly, the index (or channel number) of the 20 MHz channel in FIG. 17 is 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125, 129, 133, 137, 141, 145, 149, 153, 157, 161, 165, 169, 173, 177, 181, 185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229, 233. In addition, according to the (5.940 + 0.005 * N) GHz rule described above, the index of the 40 MHz channel of FIG. 17 is 3, 11, 19, 27, 35, 43, 51, 59, 67, 75, 83, 91, 99, 107, 115, 123, 131, 139, 147, 155, 163, 171, 179, 187, 195, 203, 211, 219, 227.

In the example of FIG. 17, 20, 40, 80, and 160 MHz channels are shown, but additionally, 240 MHz or 320 MHz channels may be added.

Hereinafter, a PPDU transmitted/received by the STA of the present specification is described.

18 shows an example of a PPDU used in the present specification.

The PPDU of FIG. 18 may be called various names such as an EHT PPDU, a transmitting PPDU, a receiving PPDU, a first type or an N-type PPDU. In addition, it can be used in a new wireless LAN system with an improved EHT system and/or an EHT system.

The sub-field of FIG. 18 may be changed to various names. For example, the SIG A field may be called an EHT-SIG-A field, the SIG B field an EHT-SIG-B, the STF field an EHT-STF field, and the LTF field an EHT-LTF field.

The subcarrier spacing of the L-LTF, L-STF, L-SIG, and RL-SIG fields of FIG. 18 may be determined as 312.5 kHz, and the subcarrier spacing of the STF, LTF, and Data fields may be determined as 78.125 kHz. That is, the subcarrier index of the L-LTF, L-STF, L-SIG, and RL-SIG fields may be displayed in 312.5 kHz units, and the subcarrier index of the STF, LTF, and Data fields may be displayed in 78.125 kHz units.

The SIG A and/or SIG B fields of FIG. 18 may include additional fields (eg, SIG C or one control symbol, etc.). The subcarrier spacing of all/part of the SIG A and SIG B fields may be set to 312.5 kHz, and the subcarrier spacing of the remaining portions may be set to 78.125 kHz.

The PPDU of FIG. 18 may have the same L-LTF and L-STF fields.

The L-SIG field of FIG. 18 may include, for example, 24-bit bit information. For example, the 24-bit information may include a rate field of 4 bits, a reserved bit of 1 bit, a length field of 12 bits, a parity bit of 1 bit, and a tail bit of 6 bits. For example, the 12-bit Length field may include information on the number of octets of the PSDU (Physical Service Data Unit). For example, the value of the 12-bit Length field may be determined based on the type of PPDU. For example, if the PPDU is a non-HT, HT, VHT PPDU or an EHT PPDU, the value of the Length field may be determined in multiples of 3. For example, when the PPDU is an HE PPDU, the value of the Length field may be determined as “multiple of 3 + 1” or “multiple of 3 +2”. In other words, the value of the Length field can be determined as a multiple of 3 for non-HT, HT, VHT PPDU or EHT PPDU, and the value of the Length field for HE PPDU is a multiple of 3 + 1 or multiple of 3 +2”.

For example, the transmitting STA may apply BCC encoding based on a code rate of 1/2 to the 24-bit information of the L-SIG field. Thereafter, the transmitting STA may acquire 48 bits of BCC coded bits. For the 48-bit coded bit, BPSK modulation may be applied to generate 48 BPSK symbols. The transmitting STA may map 48 BPSK symbols to positions excluding pilot subcarriers {subcarrier index -21, -7, +7, +21} and DC subcarrier {subcarrier index 0}. As a result, 48 BPSK symbols can be mapped to subcarrier indexes -26 to -22, -20 to -8, -6 to -1, +1 to +6, +8 to +20, and +22 to +26. have. The transmitting STA may additionally map signals of {-1, -1, -1, 1} to the subcarrier index {-28, -27, +27, +28}. The above signal can be used for channel estimation for a frequency domain corresponding to {-28, -27, +27, +28}.

The transmitting STA may generate the RL-SIG generated in the same way as the L-SIG. BPSK modulation may be applied to RL-SIG. The receiving STA can know that the received PPDU is an HE PPDU or an EHT PPDU based on the presence of the RL-SIG.

After RL-SIG in FIG. 18, for example, EHT-SIG-A or one control symbol may be inserted. The symbol (i.e., EHT-SIG-A or one control symbol) contiguous to the RL-SIG may include 26 bits of information, and may include information for identifying the type of the EHT PPDU. For example, when the EHT PPDU is divided into various types (e.g., EHT PPDU supporting SU, EHT PPDU supporting MU, EHT PPDU related to Trigger Frame, EHT PPDU related to Extended Range transmission, etc.) , EHT PPDU type information may be included in a symbol subsequent to the RL-SIG.

The symbol subsequent to the RL-SIG may include, for example, information about the length of the TXOP and information about the BSS color ID. For example, a SIG-A field may be configured in succession to a symbol (eg, one control symbol) consecutive to RL-SIG. Alternatively, a symbol subsequent to RL-SIG may be a SIG-A field.

For example, the SIG-A field is 1) a DL/UL indicator, 2) a BSS color field that is an identifier of a BSS, 3) a field including information on the remaining time of the current TXOP section, 4) a bandwidth. Bandwidth field including information, 5) Field including information on MCS technique applied to SIG-B, 6) Contains information related to whether dual subcarrier modulation technique is applied to SIG-B Indication field, 7) a field including information on the number of symbols used for SIG-B, 8) a field including information on whether SIG-B is generated over the entire band, 9) LTF/STF A field including information on the type of 10, 10) may include information on a field indicating the length of the LTF and CP length.

SIG-B of FIG. 18 may include the technical characteristics of HE-SIG-B shown in the example of FIGS. 8 to 9 as it is.

The STF of FIG. 18 may be used to improve automatic gain control estimation in a multiple input multiple output (MIMO) environment or OFDMA environment. The LTF of FIG. 18 can be used to estimate a channel in a MIMO environment or an OFDMA environment.

The STF of FIG. 18 can be set to various types. For example, a first type (that is, 1x STF) among STFs may be generated based on a first type STF sequence in which non-zero coefficients are arranged at 16 subcarrier intervals. The STF signal generated based on the first type STF sequence may have a period of 0.8 μs, and the period signal of 0.8 μs may be repeated 5 times to become a first type STF having a length of 4 μs. For example, a second type (that is, 2x STF) among STFs may be generated based on a second type STF sequence in which non-zero coefficients are arranged at 8 subcarrier intervals. The STF signal generated based on the second type STF sequence may have a period of 1.6 μs, and the period signal of 1.6 μs may be repeated 5 times to become a second type EHT-STF having a length of 8 μs. For example, a third type of STF (ie, 4x EHT-STF) may be generated based on a third type STF sequence in which non-zero coefficients are arranged at four subcarrier intervals. The STF signal generated based on the third type STF sequence may have a period of 3.2 μs, and the 3.2 μs period signal may be repeated 5 times to become a third type EHT-STF having a length of 16 μs. Only some of the above-described first to third types of EHT-STF sequences may be used. In addition, the EHT-LTF field may have first, second, and third types (ie, 1x, 2x, 4x LTF). For example, the first/second/third type LTF field may be generated based on an LTF sequence in which non-zero coefficients are arranged at 4/2/1 subcarrier intervals. The first/second/third type LTF may have a time length of 3.2/6.4/12.8 μs. In addition, various lengths of GI (eg, 0.8/1/6/3.2 μs) may be applied to the first/second/third type LTF.

Information about the type of STF and/or LTF (including information on GI applied to LTF) may be included in the SIG A field and/or the SIG B field of FIG. 18.

The PPDU of FIG. 18 may support various bandwidths. For example, the PPDU of FIG. 18 may have a bandwidth of 20/40/80/160/240/320 MHz. For example, some fields (eg, STF, LTF, and data) of FIG. 18 may be configured based on the RU shown in FIGS. 5 to 7 and the like. For example, when there is one receiving STA of the PPDU of FIG. 18, all fields of the PPDU of FIG. 18 may occupy the entire bandwidth. For example, when there are multiple receiving STAs of the PPDU of FIG. 18 (that is, when an MU PPDU is used), some fields (eg, STF, LTF, data) of FIG. 18 are illustrated in FIGS. 5 to 7 and the like. It can be configured based on the RU. For example, the STF, LTF, and data fields for the first receiving STA of the PPDU may be transmitted and received through the first RU, and the STF, LTF, and data fields for the second receiving STA of the PPDU may be transmitted and received through the second RU. Can be. In this case, the location of the first/second RU may be determined based on FIGS. 5 to 7 and the like.

The PPDU of FIG. 18 may be determined (or identified) as an EHT PPDU based on the following method.

The receiving STA may determine the type of the received PPDU as the EHT PPDU based on the following. For example, 1) the first symbol after the L-LTF signal of the received PPDU is BPSK, 2) the RL-SIG where the L-SIG of the received PPDU is repeated is detected, and 3) the length of the L-SIG of the received PPDU. When the result of applying “modulo 3” to the value is detected as “0”, the received PPDU may be determined as the EHT PPDU. If the received PPDU is determined to be the EHT PPDU, the receiving STA is based on the bit information included in the symbol after RL-SIG in FIG. 18, and the type of the EHT PPDU (eg, SU/MU/Trigger-based/Extended Range type) ) Can be detected. In other words, the receiving STA is 1) the first symbol after the L-LTF signal, which is the BSPK, 2) the result of applying the RL-SIG identical to the L-SIG in the L-SIG field and 3) “modulo 3”. Based on the L-SIG including the Length field set to “0”, the received PPDU can be determined as the EHT PPDU.

For example, the receiving STA may determine the type of the received PPDU as HE PPDU based on the following. For example, 1) the first symbol after the L-LTF signal is BPSK, 2) the RL-SIG where the L-SIG is repeated is detected, and 3) “modulo 3” is applied to the length value of the L-SIG. When the result is detected as "1" or "2", the received PPDU may be determined as the HE PPDU.

For example, the receiving STA may determine the type of the received PPDU as non-HT, HT and VHT PPDU based on the following. For example, 1) the first symbol after the L-LTF signal is BPSK, 2) the RL-SIG where the L-SIG is repeated is not detected, and 3) “modulo 3” for the length value of the L-SIG. When the applied result is detected as “0”, the received PPDU can be determined as non-HT, HT and VHT PPDU.

In the following example, (Send/Receive/Up/Down) signal, (Send/Receive/Up/Down) frame, (Send/Receive/Up/Down) packet, (Send/Receive/Up/Down) data unit, ( The signal represented by transmission/reception/upward/downward data may be a signal transmitted and received based on the PPDU of FIG. 18. The PPDU of FIG. 18 can be used to transmit and receive various types of frames. For example, the PPDU of FIG. 18 can be used for a control frame. Examples of the control frame may include a request to send (RTS), a clear to send (CTS), a Power Save-Poll (PS-Poll), a BlockACKReq, a BlockAck, a NDP (Null Data Packet) announcement, and a Trigger Frame. For example, the PPDU of FIG. 18 can be used for a management frame. An example of a management frame may include a Beacon frame, (Re-)Association Request frame, (Re-)Association Response frame, Probe Request frame, Probe Response frame. For example, the PPDU of FIG. 18 can be used for a data frame. For example, the PPDU of FIG. 18 may be used to simultaneously transmit at least two or more of a control frame, a management frame, and a data frame.

An example of the present specification described below relates to a technical feature in which an STA performs an operation for protecting a wireless medium from interference during a specific procedure.

The first type AP may transmit a first frame related to sounding of a channel between the second type AP and a station (STA) to at least one second type AP performing multi-AP transmission. For example, the first frame may be a frame that starts one procedure. The first type AP may receive a second frame related to the sounding result of the channel from the second type AP. For example, the second frame may be a frame ending the procedure.

The first frame may include a duration field. The value of the duration field may be set to protect a time interval from a first time point related to the first frame to a second time point related to the second frame. The second time point may be a time point before the short inter frame space (SIFS) from the second frame. For example, the first time point may be a time point when the transmission of the first frame is completed at the first type AP, and the second time point may be a time point at which the reception of the second frame is started at the first type AP. For example, the time interval between the first frame and the second frame may be larger than SIFS.

For example, the value of the duration field may be determined based on the length of frames transmitted between the first frame and the second frame. For example, one procedure may consist of transmission/reception of a first frame, a second frame, and frames transmitted between the first frame and the second frame. For example, the first type AP may acquire the length of frames transmitted between the first frame and the second frame, and may determine the value of the duration field based on the length of the acquired frames.

For example, the first frame may include information related to APs and STAs that do not set a network allocation vector (NAV) based on the value of the duration field. For example, identifiers of APs and STAs that do not set a network allocation vector (NAV) (eg, AID, etc.) may be included in the first frame. The duration field may be included in the MAC header or PHY header of the first frame. For example, the first frame may be a PPDU.

19 to 21 are diagrams illustrating embodiments of a method of performing a pre-procedure in a wireless LAN system.

The horizontal axis in FIGS. 19 to 21 is a time axis. In order to transmit/receive data using new technologies such as MU-MIMO, OFDMA, Wide bandwidth TX, Joint TX, STAs may perform a preliminary procedure. For example, STAs may perform a preliminary procedure to support new technologies such as MU-MIMO, OFDMA, Wide bandwidth TX, and Joint TX. The pre-procedure may mean an operation of transmitting/receiving a frame for prior information required for data transmission/reception using a new technique. In the following, a method is described for protecting a pre-procedure from interference by occupying a wireless medium (eg, a channel) while the pre-procedure is being performed.

While a specific procedure is performed, STAs 110 and 120 (for example, an AP or a non-AP STA) performing the procedure may transmit/receive a frame to transmit necessary information. In order to perform a specific procedure, transmission/reception of a plurality of frames may need to be performed. When the transmission interval between frames is equal to or greater than SIFS or point coordination function (PCF) Inter Frame Space (PIFS), interference may occur. When interference occurs, the STAs 110 and 120 may not complete the procedure within a desired time.

For example, in order to perform a specific procedure, transmission of the first to fifth frames may have to be performed. After the first frame is transmitted, transmission of the second to fifth frames may be delayed due to transmission of the STAs 110 and 120 that do not perform the corresponding procedure before the second frame is transmitted. Therefore, a method may be needed to protect the procedure from interference. The first to fifth frames may be PPDUs.

Referring to FIG. 19, the first STAs 110 and 120 may transmit the first frame to the second STAs 110 and 120. The first frame is a frame at the beginning of the first procedure, and the second frame is a frame at the end of the first procedure. In other words, the first procedure begins with the first frame and ends with the second frame. The first procedure may include transmission of frames other than the first frame and the second frame. Frame transmission performed in the first procedure may be performed by the third STAs 110 and 120 rather than the first STAs 110 and 120 and the second STAs 110 and 120. The second STAs 110 and 120 may receive the first frame from the first STAs 110 and 120. The second STAs 110 and 120 may transmit the second frame to the first STAs 110 and 120, and the first STAs 110 and 120 receive the second frame from the second STAs 110 and 120. can do.

Referring to FIG. 20, the first STAs 110 and 120 may transmit the first frame to the second STAs 110 and 120. The first frame is a frame at the beginning of the second procedure, and the second frame is a frame at the end of the second procedure. The second procedure may include transmission of frames other than the first frame and the second frame. The second STAs 110 and 120 may receive the first frame from the first STAs 110 and 120. The first STAs 110 and 120 may transmit the second frame to the second STAs 110 and 120, and the second STAs 110 and 120 receive the second frame from the first STAs 110 and 120. can do. Frame transmission performed within the second procedure may be performed by the third STAs 110 and 120 rather than the first STAs 110 and 120 and the second STAs 110 and 120.

Referring to FIG. 21, the second STAs 110 and 120 may transmit the first frame to the first STAs 110 and 120. The first frame is a frame at the beginning of the third procedure, and the second frame is a frame at the end of the third procedure. The third procedure may include transmission of frames other than the first frame and the second frame. The first STAs 110 and 120 may receive the first frame from the second STAs 110 and 120. The second STAs 110 and 120 may transmit the second frame to the first STAs 110 and 120, and the first STAs 110 and 120 receive the second frame from the second STAs 110 and 120. can do. Frame transmission performed in the third procedure may be performed by the third STAs 110 and 120 rather than the first STAs 110 and 120 and the second STAs 110 and 120.

The first frame and the second frame of FIGS. 19 to 21 may be frames including information necessary to perform a procedure (eg, a first procedure, a second procedure, and a third procedure). Depending on which procedure is in progress, the first frame and the second frame may be frames exchanged between STAs 110 and 120 (for example, FIG. 19 ), and frames transmitted by one STA 110 and 120 It may be (for example, Figure 20, Figure 21). The first STAs 110 and 120 may be AP or non-AP STAs, and the second STAs 110 and 120 may be APs or non-AP STAs. There may be two or more STAs 110 and 120 participating in the procedure.

In order to perform the procedure in FIGS. 19 to 21, the first frame and the second frame must be transmitted/received. For example, after the first STAs 110 and 120 transmit the first frame, the first STAs 110 and 120 again acquire a channel through contention and transmit the second frame. When the channel acquisition for transmitting the second frame by the first STAs 110 and 120 is delayed, information on the first frame may no longer be valid. When the channel acquisition for the first STAs 110 and 120 to transmit the second frame is delayed, the time required to complete the procedure is prolonged, so the performance of the communication system may deteriorate. Hereinafter, a method for protecting a time interval for performing a procedure from interference is described.

22 is a diagram illustrating an embodiment of a method of protecting a time interval for performing a procedure in a wireless LAN system.

Referring to FIG. 22, the first STAs 110 and 120 may transmit the first frame to the second STAs 110 and 120. The first frame is the frame at the beginning of the procedure, and the second frame is the frame at the end of the procedure. In other words, the procedure begins with the first frame and ends with the second frame. The procedure may include transmission of frames other than the first frame and the second frame. That is, transmission of another frame may be performed between transmission of the first frame and transmission of the second frame. The frame transmission performed within the procedure may be performed by the third STAs 110 and 120 rather than the first STAs 110 and 120 and the second STAs 110 and 120. The second STAs 110 and 120 may receive the first frame from the first STAs 110 and 120.

The first STAs 110 and 120 may protect a time period for performing a procedure by using a duration field of the first frame. For example, the first STAs 110 and 120 may protect a time period for performing a procedure by using a value of the duration field included in the MAC header of the first frame or the TXOP duration field included in the PHY header. The first frame may be a PPDU.

For example, the first STAs 110 and 120 protect the time interval of the duration field of the first frame from the first time point related to the first frame to the second time point related to the second frame. Can be set.

For example, the first time point is the time point at which transmission of the first frame is completed at the first STAs 110 and 120, and the second time point is the time point at which the reception of the second frame is started at the first STAs 110 and 120 (or , When the transmission of the second frame is started by the second STAs 110 and 120 ).

For example, the second time point is set to a point in time between the time point when SIFS (or PIFS) starts from the time point when the reception of the second frame starts from the time point when the second frame starts to be received by the first STAs 110 and 120. Can be. For convenience, the transmission time and reception time of the frame are regarded as the same time.

STAs 110 and 120 who do not participate in the procedure may set the NAV based on the value of the duration field of the first frame when the first frame is received. That is, STAs 110 and 120 who do not participate in the procedure may not transmit during the time period corresponding to the value of the duration field of the first frame when the first frame is received.

For example, if the STAs 110 and 120 participating in the procedure are only the transmitting STAs 110 and 120 and the receiving STAs 110 and 120, for the STAs 110 and 120 participating in the procedure in the first frame Information may not be included. For example, when the STAs 110 and 120 participating in the procedure exist in addition to the transmitting STAs 110 and 120 and the receiving STAs 110 and 120, for performing the procedures of the corresponding STAs 110 and 120 (ie, Information related to STAs 110 and 120 performing a procedure on a first frame (for example, identifier information of STAs 110 and 120 performing a procedure) to prevent NAV setting by the first frame) May be included. STAs 110 and 120 performing the procedure may receive the first frame and may not set the NAV based on information related to the STAs 110 and 120 performing the procedure.

When the second time point is set to a point in time between the time point at which the reception of the second frame starts from the time point before SIFS (or PIFS) from the time point at which the second frame is started at the first STAs 110 and 120, the first time point Since the time interval between when the NAV setting of other STAs 110 and 120 is released by the duration field of the frame and when the second frame is transmitted is less than or equal to SIFS, interference by other STAs 110 and 120 is prevented. Can be. For example, the second time point may be set to a later time point than the time point at which the reception of the second frame is started at the first STAs 110 and 120.

The first STAs 110 and 120 may know in advance information about the time required for the corresponding procedure. For example, the first STAs 110 and 120 may know in advance the lengths of the frames transmitted in a specific procedure, and the duration field based on the lengths of the frames and the intervals between the frames (for example, SIFS). You can determine the value of The first STAs 110 and 120 may generate a first frame based on the determined duration field value.

23 is a diagram illustrating an embodiment of a method of protecting a time interval for performing a procedure in a wireless LAN system.

Referring to FIG. 23, the first STAs 110 and 120 may transmit the first frame to the second STAs 110 and 120. The first frame is the frame at the beginning of the procedure, and the second frame is the frame at the end of the procedure. In other words, the procedure begins with the first frame and ends with the second frame. The second STAs 110 and 120 may receive the first frame from the first STAs 110 and 120.

The first STAs 110 and 120 may protect a time period for performing a procedure by using an arbitrary signal (eg, dummy signal) after the first frame transmission. For example, the first STAs 110 and 120 may transmit an arbitrary signal during a time interval from a first time point related to the first frame to a second time point related to the second frame.

For example, the first time point is the time point at which transmission of the first frame is completed at the first STAs 110 and 120, and the second time point is the time point at which the reception of the second frame is started at the first STAs 110 and 120 (or , When the transmission of the second frame is started by the second STAs 110 and 120 ). For convenience, the transmission time and reception time of the frame are regarded as the same time.

For example, the second time point is set to a point in time between the time point when SIFS (or PIFS) starts from the time point when the reception of the second frame starts from the time point when the second frame starts to be received by the first STAs 110 and 120. Can be. For convenience, the transmission time and reception time of the frame are regarded as the same time.

Due to an arbitrary signal transmitted by the first STAs 110 and 120, no STAs 110 and 120 can transmit signals during the time period from the first time point to the second time point. For example, when STAs 110 and 120 not participating in the procedure perform energy detection (ED) to transmit a signal during a time period from the first time point to the second time point, energy by an arbitrary signal is detected. . That is, during the time period from the first time point to the second time point, since the result of the ED is a busy state, other STAs 110 and 120 cannot transmit a signal.

If the second time point is set to a point in time between the time point at which the reception of the second frame starts from the time point before the SIFS (or PIFS) from the time point at which the second frame is started at the first STAs 110 and 120, any Since the time interval between the end of the busy state of the channel by the signal and the time when the second frame is transmitted is less than or equal to SIFS, interference by other STAs 110 and 120 can be prevented. For example, the second time point may be set to a later time point than the time point at which the reception of the second frame is started at the first STAs 110 and 120.

The first STAs 110 and 120 may know in advance information about the time required for the corresponding procedure. For example, the first STA (110, 120) may know in advance the length of the frames transmitted in a specific procedure, and any length based on the length of the frames and the interval between the frames (for example, SIFS) The length of the signal can be determined.

For example, an arbitrary signal may be generated by adjusting the length of padding using a padding bit of the first frame.

24 is a diagram illustrating an embodiment of a method of protecting a time interval for performing a procedure in a wireless LAN system.

Referring to FIG. 24, the first STAs 110 and 120 may transmit the first frame to the second STAs 110 and 120. The first frame is the frame at the beginning of the procedure, and the second frame is the frame at the end of the procedure. In other words, the procedure begins with the first frame and ends with the second frame. The procedure may include transmission of frames other than the first frame and the second frame. That is, transmission of another frame may be performed between transmission of the first frame and transmission of the second frame. The frame transmission performed within the procedure may be performed by the third STAs 110 and 120 rather than the first STAs 110 and 120 and the second STAs 110 and 120. The second STAs 110 and 120 may receive the first frame from the first STAs 110 and 120.

The first STAs 110 and 120 may protect a time period for performing the procedure by using the length field of the PPDU including the first frame. For example, the first STAs 110 and 120 may protect a time period for performing the procedure by using the value of the length field included in the PHY header of the PPDU including the first frame.

For example, the first STA (110, 120) is a time interval (time interval) from the first time associated with the first frame to the second time associated with the second frame, the value of the length field of the PPDU including the first frame ).

For example, the first time point is the time point at which transmission of the first frame is completed at the first STAs 110 and 120, and the second time point is the time point at which the reception of the second frame is started at the first STAs 110 and 120 (or , When the transmission of the second frame is started by the second STAs 110 and 120 ). For convenience, the transmission time and reception time of the frame are regarded as the same time.

For example, the second time point is set to a point in time between the time point when SIFS (or PIFS) starts from the time point when the reception of the second frame starts from the time point when the second frame starts to be received by the first STAs 110 and 120. Can be. For convenience, the transmission time and reception time of the frame are regarded as the same time.

STAs 110 and 120 who do not participate in the procedure may not transmit during a time period corresponding to the value of the length field of the PPDU including the first frame when the first frame is received. For example, a time period corresponding to the value of the length field of the PPDU including the first frame may be set to a busy state.

For example, for performing the procedure of the STAs 110 and 120 participating in the procedure (that is, ignoring the length field value of the PPDU including the first frame and transmitting the frame), performing the procedure on the first frame Information related to STAs 110 and 120 (eg, identifier information of STAs 110 and 120 performing a procedure) may be included. STAs 110 and 120 performing the procedure may receive the first frame, and ignore the length field value of the PPDU including the first frame based on information related to the STAs 110 and 120 performing the procedure. And send the frame. The STAs 110 and 120 performing the procedure may know the length of the PPDU including the actual first frame based on a preset value, or through the actual PPDU length value indicated separately.

When the second time point is set to a point in time between the time point at which the reception of the second frame starts and the time before SIFS (or PIFS) from the time point at which the second frame is started at the first STAs 110 and 120, the first time point Interference by other STAs 110 and 120 because the time interval between when other STAs 110 and 120 cannot perform signal transmission by the length field of the frame and when the second frame is transmitted is less than or equal to SIFS. This can be prevented. For example, the second time point may be set to a later time point than the time point at which the reception of the second frame is started at the first STAs 110 and 120.

The first STAs 110 and 120 may know in advance information about the time required for the corresponding procedure. For example, the first STAs 110 and 120 may know in advance the lengths of the frames transmitted in a specific procedure, and the length field based on the lengths of the transmitted frames and the intervals between the frames (for example, SIFS). You can determine the value of The first STAs 110 and 120 may generate a PPDU including the first frame based on the determined length field value.

Hereinafter, a transmission method using a multi-AP is described.

25 and 26 are flowcharts illustrating an embodiment of a signal transmission method using a multi-AP.

Referring to FIG. 25, the first type APs 110 and 120 (eg, the master AP) select the second type APs 110 and 120 through a sounding procedure, and the selected second type APs 110 and 120 120) (eg, Slave APs) can perform multi-AP transmission to the STAs 110 and 120.

The multi-AP transmission procedure of FIG. 25 may be configured in steps 1) to 7).

1) The first type AP (110, 120) transmits a JTX trigger frame to the second type AP 1 (110, 120), the second type AP 2 (110, 120), and the second type AP 3 (110, 120). do.

<Sending method>

-The JTX trigger frame is transmitted to a plurality of second type APs at once.

-The first type APs 110 and 120 may transmit the JTX trigger frame only to specific second type APs 110 and 120, and the JTX trigger frame transmitted by the first type APs 110 and 120 may be transmitted. It is also possible to transmit all the second type APs 110 and 120 that can be received.

<Included content or information>

-The address of the STA (110, 120) receiving the JTX, the BSS information to which the STA (110, 120) belongs, and the address of the second type AP (110, 120) in association with the corresponding STA (110, 120)

<action>

-The second type APs receiving the JTX trigger frame are first type APs (110, 120) or second type APs (110, 120) synced with each other (Timing, carrier frequency offset (CFO), sampling frequency offset (SFO)) , Phase drift).

In the case of FIG. 25, the second type APs 110 and 120 (for example, the second type APs 1 110 and 120) associated with the corresponding STAs 110 and 120 are NDPs (Null Data Packet). Prepare to send the request frame.

-The second type APs 110 and 120 that are not associated with the corresponding STAs 110 and 120 (for example, the second type AP 2 (110 and 120) and the second type AP 3 (110 and 120)) They prepare to receive NDP frames to be transmitted by the corresponding STAs 110 and 120 in the future.

2) The second type APs 110 and 120 (associated with STA) transmit the JTX NDP request frame to the STAs 110 and 120.

<Sending method>

-The JTX NDP request frame can be transmitted in a control mode using SU PPDU format.

<Included content or information>

-Include the address of the STA (110, 120), the address or indicator of the second type AP (110, 120) to receive the future JTX NDP frame.

<action>

-The corresponding STAs 110 and 120 that have received the JTX NDP request prepare to transmit the JTX NDP.

2-1) If the STA (110, 120) can directly receive the frame transmitted by the first type AP (110, 120), the procedure of step 2) may be omitted, and the first type AP (110) , 120) may directly transmit the JTX NDP request frame to the STAs 110 and 120. The first type APs 110 and 120 may perform steps 1) and 2) at once.

3) The STA transmits the JTX NDP frame to the second type APs 110 and 120.

<Sending method>

-The STAs 110 and 120 transmit only preambles as in the existing NDP format or include information that can indicate the second type APs 110 and 120 to be received using the newly defined JTX NDP frame. .

<Included content or information>

-When the STAs 110 and 120 only transmit the preamble, include the content in the PHY header, and when the STAs 110 and 120 instruct the second type APs by transmitting the newly defined JTX NDP frame, in the payload. Contains content.

<action>

-The second type APs 110 and 120 receiving the JTX NDP frame each estimate a channel with the corresponding STAs 110 and 120.

-Each of the second type APs 110 and 120 receiving the JTX NDP frame has channel information with the corresponding STAs 110 and 120 (received signal strength indicator (RSSI), signal-to-noise ratio (SNR), and SINR ( signal-to-interference-plus-noise ratio), etc.).

-The second type APs 110 and 120 that have received the JTX NDP frame perform an operation of matching the synchronization between the STAs 110 and 120 and the second type APs 110 and 120 (Timing, CFO, SFO, Phase drift). do.

-When the indicators of the second type APs 110 and 120 are included in the JTX NDP frame, the second type APs 110 and 120 can clearly know whether the JTX NDP frame comes to them.

-The operation of 3) describes a channel estimation method in multi-user (MU) transmission using channel reciprocity. Channel reciprocity means a method of estimating a downlink (DL) channel through a sounding procedure of an uplink (UL) channel.

3-1) If channel reciprocity is not supported, the STAs 110 and 120 may transmit a new JTX NDP frame including only LTF for one stream without using the existing NDP frame. At this time, the STAs 110 and 120 can only report the power intensity and do not support Multi-Input Multi-Output (MIMO) when transmitting JTX NDP frames. At this time, it is also possible to check whether the frames that the second type APs 110 and 120 came to fit by including the indicators of the second type APs 110 and 120 in the newly defined frame.

4) The first type APs 110 and 120 transmit JTX NDP feedback trigger frames to the second type APs 110 and 120. The JTX NDP feedback trigger frame is a frame for requesting or triggering a JTX NDP feedback frame.

<Sending method>

-The first type APs 110 and 120 transmit JTX NDP feedback trigger frames to the corresponding second type APs 110 and 120 at once.

<Included content or information>

-As the indicators of the second type APs 110 and 120 included in the JTX trigger frame, the indicators of the second type APs 110 and 120 are included in the JTX NDP feedback trigger frame.

<action>

-The second type APs 110 and 120 that received the JTX NDP feedback trigger frame are synchronized between the first type APs 110 and 120 or the second type APs 110 and 120 (Timing, CFO, SFO, Phase drift) ), and prepare to transmit the JTX NDP feedback frame.

5) The second type APs 110 and 120 transmit the JTX NDP feedback frame to the first type APs 110 and 120.

<Sending method>

-The second type APs 110 and 120 transmit a JTX NDP feedback frame in UL MU-MIMO or UL MU-OFDMA.

-JTX NDP feedback frames may be transmitted in order of one second type AP (110, 120) at the same time, not the above method.

<Included content or information>

-The JTX NDP feedback frame includes channel estimation values between the respective second type APs 110 and 120 and the corresponding STAs 110 and 120.

<action>

-The first type APs 110 and 120 receiving the JTX NDP feedback frame combine the individual channel estimation values between the second type APs 110 and 120 and the corresponding STAs 110 and 120 into one channel, and the combined channels Based on the information, the second type APs 110 and 120 that are most suitable for JTX are selected.

6) The first type APs 110 and 120 transmit JTX selection frames to the second type APs 110 and 120 selected based on the JTX NDP feedback.

<Sending method>

-Among the second type APs included in the JTX trigger frame and the JTX NDP feedback trigger frame, the JTX selection frame is transmitted only to the second type APs that will finally participate in JTX. In this case, data sharing between the first type APs 110 and 120 and the second type APs 110 and 120 may be performed by including data to be transmitted through JTX.

<Included content or information>

-The JTX selection frame includes antenna information to be used for each second type AP (110, 120), number of streams, and information about JTX settings such as Modulation and Coding Scheme (MCS).

-The JTX selection frame includes the address or indicator of the second type APs to participate in JTX.

-The JTX selection frame may include data to be transmitted by JTX. Depending on the purpose, the first type APs 110 and 120 may share the same data with each second type AP 110 and 120, or may share different data.)

<action>

-The selected second type APs 110 and 120 that have received the JTX selection frame prepare to start JTX.

6-1) The first type APs 110 and 120 transmit a JTX NDP request once again before sharing data with the second type APs 110 and 120 to perform a channel estimation procedure for JTX and participate in JTX. The second type APs 110 and 120 may be finally selected.

6-2) If channel reciprocity is not supported, channel estimation for JTX is performed using the JTX NDP frame transmitted by the second type APs 110 and 120 selected through the selection procedure to the STAs 110 and 120. Can be. That is, since channel reciprocity is not supported, the selected second type APs 110 and 120 can perform channel estimation by directly transmitting a JTX NDP frame to DL.

7) The selected second type APs 110 and 120 transmit data to the corresponding STAs 110 and 120 using JTX. For example, the first type AP 110 and 120 may transmit data using JTX together with the selected second type AP 1 110 and 120.

Referring to FIG. 26, the first type APs 110 and 120 (eg, Master AP) select the second type APs 110 and 120, and the selected second type APs 110 and 120 (eg, For example, only Slave APs can perform sounding for the STAs 110 and 120.

The multi-AP transmission procedure of FIG. 26 may be configured in steps 1) to 7).

1) The first type APs 110 and 120 may select the second type APs 110 and 120 and transmit a JTX trigger frame to the selected second type APs 110 and 120. The transmission method, included content or information, and operation may be the same as step 1) described in FIG. 25.

2) Channel estimation for JTX can be performed using the JTX NDP frame transmitted by the second type APs 110 and 120 to the STAs 110 and 120. For example, when channel reciprocity is not supported, the selected second type APs 110 and 120 may directly transmit a JTX NDP frame to DL to perform channel estimation. The second type APs 110 and 120 may transmit the JTX NDP announce frame before transmitting the JTX NDP frame.

3) The second type APs 110 and 120 may transmit the JTX NDP frame to the STA.

4) STAs 110 and 120 may transmit a JTX NDP feedback frame including channel estimation information between the second type APs 110 and 120 and the STA based on the received JTX NDP frame.

5) The second type APs 110 and 120 receiving the JTX NDP feedback frame may transmit the JTX NDP feedback frame including the received channel estimation information to the first type APs 110 and 120.

Steps 6) and 7) may be the same as steps 6) and 7) described in FIG. 25.

The procedure for protecting the procedures of FIGS. 22 to 24 may be used so that the procedure for multi-AP transmission of FIGS. 25 and 26 can be performed without delay. For example, steps 1) to 3) of FIG. 25 may be protected by one procedure, steps 4) of FIG. 25 and steps 5) of FIG. 25 may be protected by one procedure, and Steps 1) to 5) may be protected by one procedure, steps 6) and 7) of FIG. 25 may be protected by one procedure, and steps 1) through 7) of FIG. 25 may be protected by one procedure. Can be protected by procedures.

27 is a flowchart for explaining an embodiment of the operation of the first type APs 110 and 120.

Referring to FIG. 27, the first type APs 110 and 120 may acquire information on a time interval required for performing the procedure (S2710). For example, the first type APs 110 and 120 may know in advance information about the time required for the corresponding procedure. For example, the first type APs 110 and 120 may know in advance the length of frames transmitted in a specific procedure, and protect based on the length of the frames to be transmitted and the interval between frames (for example, SIFS). It is possible to determine the length of the time interval to be performed. For example, the first type APs 110 and 120 may protect the time period using any one or more of the methods described in FIGS. 22 to 24.

The first type APs 110 and 120 may transmit the first frame (S2720). For example, the first frame may be a PPDU. For example, the first frame may be a JTX trigger frame transmitted in step 1) of FIG. 25. For example, the first frame may be a frame transmitted to at least one second type AP 110 or 120 performing multi-AP transmission. For example, the first frame may be a frame related to sounding of a channel between the second type APs 110 and 120 and the STAs 110 and 120. For example, the first frame includes a duration field, and the value of the duration field protects a time interval from a first time point related to the first frame to a second time point related to the second frame. The second time point may be a time point before the short inter frame space (SIFS) from the second frame. For example, the length of a padding bit of the first frame is set to protect a time interval from a first time point related to the first frame to a second time point related to the second frame. The second time point may be a time point before the short inter frame space (SIFS) from the second frame. For example, the length field included in the PHY header of the first frame is set to protect the time interval from the first time point related to the first frame to the second time point related to the second frame, and the second time The time point may be a time point before the short inter frame space (SIFS) from the second frame. For example, the first time point related to the first frame may be a time point at which transmission of the first frame is completed.

The first type APs 110 and 120 may receive the second frame. For example, the second frame may be a JTX NDP feedback frame transmitted in step 5) of FIG. 25. For example, the second frame may be a frame related to the sounding result of the channel from the second type APs 110 and 120. The first frame is the frame at the beginning of the procedure, and the second frame is the frame at the end of the procedure. In other words, the procedure begins with the first frame and ends with the second frame. The procedure may include transmission of frames other than the first frame and the second frame. That is, transmission of another frame may be performed between transmission of the first frame and transmission of the second frame. Frame transmission performed in the procedure may be performed by STAs 110 and 120 other than the first type APs 110 and 120 and the second type APs 110 and 120. For example, if one procedure means frame transmission/reception from steps 1) to 5) of FIG. 25, the JTX trigger frame transmitted in step 1) becomes the first frame, and transmitted in step 5) The JTX NDP feedback frame may be the second frame.

If the second time point is set to a point in time between the time point at which the reception of the second frame starts from the time before SIFS (or PIFS) from the time point at which the second frame is started at the first type APs 110 and 120, Since the time interval between when other STAs 110 and 120 cannot perform signal transmission by one frame and when the second frame is transmitted is less than SIFS, interference by other STAs 110 and 120 is prevented. Can be. For example, the second time point may be set to a later time point than the time point at which the reception of the second frame is started at the first type APs 110 and 120.

28 is a flowchart for explaining an embodiment of the operation of the second type APs 110 and 120.

Referring to FIG. 28, the second type APs 110 and 120 may receive the first frame (S2810). For example, the first frame may be a PPDU. For example, the first frame may be a JTX trigger frame transmitted in step 1) of FIG. 25. For example, the first frame may be a frame transmitted to at least one second type AP 110 or 120 performing multi-AP transmission. For example, the first frame may be a frame related to sounding of a channel between the second type APs 110 and 120 and the STAs 110 and 120. For example, the first frame includes a duration field, and the value of the duration field protects a time interval from a first time point related to the first frame to a second time point related to the second frame. The second time point may be a time point before the short inter frame space (SIFS) from the second frame. For example, the length of a padding bit of the first frame is set to protect a time interval from a first time point related to the first frame to a second time point related to the second frame. The second time point may be a time point before the short inter frame space (SIFS) from the second frame. For example, the length field included in the PHY header of the first frame is set to protect the time interval from the first time point related to the first frame to the second time point related to the second frame, and the second time The time point may be a time point before the short inter frame space (SIFS) from the second frame. For example, the first time point related to the first frame may be a time point at which transmission of the first frame is completed.

The second type APs 110 and 120 may transmit the second frame. For example, the second frame may be a JTX NDP feedback frame transmitted in step 5) of FIG. 25. For example, the second frame may be a frame related to the sounding result of the channel from the second type APs 110 and 120. The first frame is the frame at the beginning of the procedure, and the second frame is the frame at the end of the procedure. In other words, the procedure begins with the first frame and ends with the second frame. The procedure may include transmission of frames other than the first frame and the second frame. That is, transmission of another frame may be performed between transmission of the first frame and transmission of the second frame. Frame transmission performed in the procedure may be performed by STAs 110 and 120 other than the first type APs 110 and 120 and the second type APs 110 and 120. For example, if one procedure means frame transmission/reception from steps 1) to 5) of FIG. 25, the JTX trigger frame transmitted in step 1) becomes the first frame, and transmitted in step 5) The JTX NDP feedback frame may be the second frame.

If the second time point is set to a point in time between the time point at which the reception of the second frame starts from the time before SIFS (or PIFS) from the time point at which the second frame is started at the first type APs 110 and 120, Since the time interval between when other STAs 110 and 120 cannot perform signal transmission by one frame and when the second frame is transmitted is less than SIFS, interference by other STAs 110 and 120 is prevented. Can be. For example, the second time point may be set to a later time point than the time point at which the reception of the second frame is started at the first type APs 110 and 120.

Some of the detailed steps shown in the examples of FIGS. 27 and 28 may be omitted, and other steps may be added. For example, in FIG. 27, a step of transmitting a third frame and/or a step of receiving a fourth frame may be added between the transmission of the first frame (S2720) and the reception of the second frame (S2730). For example, in FIG. 27, step S2710 of acquiring information on a time interval required for performing the procedure may be omitted.

When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) performing the above-described function. Modules are stored in memory and can be executed by a processor. The memory may be internal or external to the processor, and may be connected to the processor by various well-known means.

The technical features of the present specification described above can be applied to various application or business models. For example, the above-described technical features may be applied for wireless communication in a device supporting artificial intelligence (AI).

Artificial intelligence refers to the field of studying artificial intelligence or a methodology to create it, and machine learning refers to the field of studying the methodology to define and solve various problems in the field of artificial intelligence. do. Machine learning is defined as an algorithm that improves the performance of a job through constant experience.

An artificial neural network (ANN) is a model used in machine learning, and may refer to an overall model having a problem-solving ability, composed of artificial neurons (nodes) forming a network through synaptic coupling. The artificial neural network may be defined by a connection pattern between neurons in different layers, a learning process for updating model parameters, and an activation function that generates output values.

The artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer contains one or more neurons, and an artificial neural network can include neurons and synapses connecting neurons. In an artificial neural network, each neuron may output a function value of an input function input through a synapse, a weight, and an active function for bias.

The model parameter means a parameter determined through learning, and includes weights of synaptic connections and bias of neurons. In addition, the hyperparameter means a parameter that must be set before learning in a machine learning algorithm, and includes learning rate, number of iterations, mini-batch size, initialization function, and the like.

The purpose of learning an artificial neural network can be seen as determining model parameters that minimize the loss function. The loss function can be used as an index to determine an optimal model parameter in the learning process of an artificial neural network.

Machine learning can be classified into supervised learning, unsupervised learning, and reinforcement learning according to the learning method.

Supervised learning refers to a method of training an artificial neural network while a label for training data is given, and a label is a correct answer (or a result value) that the artificial neural network must infer when the training data is input to the artificial neural network. Can mean Unsupervised learning may refer to a method of training an artificial neural network without a label for learning data. Reinforcement learning may refer to a learning method in which an agent defined in a certain environment is trained to select an action or a sequence of actions to maximize cumulative reward in each state.

Machine learning, which is implemented as a deep neural network (DNN) that includes a plurality of hidden layers among artificial neural networks, is also referred to as deep learning (deep learning), and deep learning is a part of machine learning. In the following, machine learning is used to mean deep learning.

In addition, the above-described technical features can be applied to the wireless communication of the robot.

A robot can mean a machine that automatically handles or acts on a task given by its own capabilities. Particularly, a robot having a function of recognizing the environment and determining an operation by itself can be referred to as an intelligent robot.

Robots can be classified into industrial, medical, household, and military according to the purpose or field of use. The robot may be provided with a driving unit including an actuator or a motor to perform various physical operations such as moving a robot joint. In addition, the movable robot includes a wheel, a brake, a propeller, and the like in the driving unit, so that it can travel on the ground or fly in the air through the driving unit.

In addition, the above-described technical features can be applied to a device that supports augmented reality.

Augmented reality refers to virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology provides objects or backgrounds in the real world only as CG images, AR technology provides CG images made virtually on real objects, and MR technology provides computers by mixing and combining virtual objects in the real world It is a graphics technology.

MR technology is similar to AR technology in that it shows both real and virtual objects. However, in AR technology, a virtual object is used as a complementary form to a real object, whereas in MR technology, there is a difference in that a virtual object and a real object are used with equal characteristics.

XR technology can be applied to Head-Mount Display (HMD), Head-Up Display (HUD), mobile phone, tablet PC, laptop, desktop, TV, digital signage, etc. It can be called.

The claims described herein can be combined in various ways. For example, the technical features of the method claims of the present specification may be combined and implemented as a device, and the technical features of the device claims of the specification may be combined and implemented as a method. Further, the technical features of the method claims of the present specification and the technical features of the device claims may be combined and implemented as a device, and the technical features of the method claims of the specification and the device claims of the present specification may be combined and implemented as a method.

Claims (20)

1. In a method of performing a multi-access point (AP) transmission in a wireless local area network (WLAN) system,

   Obtaining, in the first type AP, information related to a duration field; And

   In the first type AP, transmitting a first frame related to sounding of a channel between the second type AP and a non-AP STA (station) to at least one second type AP performing multi-AP transmission. Including the steps,

   The first frame includes the duration field,

   Way.
2. The method according to claim 1,

   In the first type AP, receiving a second frame related to the sounding result of the channel from the second type AP,

   The duration field value is set to protect a time interval from a first time point related to the first frame to a second time point related to the second frame, and the second time point is from the second frame. The time before the Short Inter Frame Space (SIFS),

   Way.
3. The method according to claim 2,

   The first time point is a time point when the transmission of the first frame is completed,

   The second time point is a time point before SIFS from a time point when the reception of the second frame starts.

   Way.
4. The method according to claim 1,

   In the first type AP, comprising the step of transmitting a second frame to the second type AP,

   The duration field value is set to protect a time interval from a first time point related to the first frame to a second time point related to the second frame, and the second time point is from the second frame. The time before the Short Inter Frame Space (SIFS),

   Way.
5. The method according to claim 3,

   The first time point is a time point when the transmission of the first frame is completed,

   The second time point is a time point before SIFS from a time point when the transmission of the second frame starts.

   Way.
6. The method according to claim 1,

   The value of the duration field is determined based on the length of frames transmitted between the first frame and the second frame,

   Way.
7. The method according to claim 1,

   The first frame includes information related to an AP and a non-AP STA that do not set a network allocation vector (NAV) based on the value of the duration field,

   Way.
8. The method according to claim 1,

   The time interval between the first frame and the second frame is greater than SIFS,

   Way.
9. The method according to claim 1,

   The duration field is included in a medium access control (MAC) header,

   Way.
10. The method according to claim 1,

    The duration field is included in the PHY (physical) header,

    Way.
11. In a type 1 access point (AP) used in a wireless local area network (WLAN) system, the first type AP includes:

    A transceiver; And

    Includes a processor connected to the transceiver, the processor,

    Acquire information related to a duration field; And

    A first frame related to sounding of a channel between the second type AP and a non-AP STA (station) is transmitted to at least one second type AP performing multi-AP transmission,

    The first frame is set to include the duration field,

    Type 1 AP.
12. The method of claim 11,

    The processor,

    It is configured to receive a second frame related to the sounding result of the channel from the second type AP,

    The duration field value is set to protect a time interval from a first time point related to the first frame to a second time point related to the second frame, and the second time point is from the second frame. The time before the Short Inter Frame Space (SIFS),

    Type 1 AP.
13. The method according to claim 12,

    The first time point is a time point when the transmission of the first frame is completed,

    The second time point is a time point before SIFS from a time point when the reception of the second frame starts.

    Type 1 AP.
14. The method according to claim 11,

    The processor,

    It is configured to transmit a second frame to the second type AP,

    The duration field value is set to protect a time interval from a first time point related to the first frame to a second time point related to the second frame, and the second time point is from the second frame. The time before the Short Inter Frame Space (SIFS),

    Type 1 AP.
15. The method of claim 13,

    The first time point is a time point when the transmission of the first frame is completed,

    The second time point is a time point before SIFS from a time point when the transmission of the second frame starts.

    Type 1 AP.
16. The method of claim 11,

    The value of the duration field is determined based on the length of frames transmitted between the first frame and the second frame,

    Type 1 AP.
17. The method of claim 11,

    The first frame includes information related to an AP and a non-AP STA that do not set a network allocation vector (NAV) based on the value of the duration field,

    Type 1 AP.
18. The method of claim 11,

    The time interval between the first frame and the second frame is greater than SIFS,

    Type 1 AP.
19. The method of claim 11,

    The duration field is included in a medium access control (MAC) header,

    Type 1 AP.
20. The method of claim 11,

    The duration field is included in the PHY (physical) header,

    Type 1 AP.

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