WO2020180049A1 - Channel estimation using plurality of aps - Google Patents

Abstract

In a wireless local area network (LAN) system, a first shared access point (AP) may receive a first feedback frame from a first station (STA) and receive a second feedback frame from a second STA. The first feedback frame may include channel information between the first STA and first to third shared APs, and the second feedback frame may include channel information between the second STA and the first to third shared APs. The first shared AP may receive a feedback request frame from a sharing AP. The first shared AP transmits a third feedback frame to the sharing AP on the basis of the first and second feedback frames, wherein the third feedback frame may be transmitted according to a UL-MU MIMO scheme.

Description

Channel estimation using multiple APs

The present specification relates to a method of transmitting a feedback signal for channel estimation in a wireless local area network (LAN) system including a plurality of access points (APs).

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

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

A method performed by a sharing access point (AP) in a wireless local area network (LAN) system according to various embodiments has a technical feature of estimating a channel using a plurality of APs to perform multi-AP transmission. Can include. A first shared access point (AP) may receive a first feedback frame from a first station (STA) and a second feedback frame from a second STA. The first feedback frame may include channel information between the first STA and the first to third shared APs. The second feedback frame may include channel information between the second STA and the first to third shared APs. The first shared AP may receive a feedback request frame from a sharing AP. The first shared AP may transmit a third feedback frame to the sharing AP based on the first and second feedback frames. The third feedback frame may be transmitted in the UL-MU MIMO (uplink multi-user multiple input multiple output) method.

According to an example of the present specification, the STA may feed back channel estimation information to slave APs. The STA may inform all the slave APs of all channel estimation information for all the slave APs. That is, channel estimation information can be fed back using a multicast method, and thus, the possibility of receiving the channel estimation information from slave APs can be increased.

Slave APs may receive channel estimation information between all slave APs and STAs from STAs. However, the slave APs may transmit only channel estimation information between themselves and STAs among the received channel estimation information to the master AP. Therefore, it is possible to obtain an effect of reducing the size of channel estimation information transmitted by the slave AP. Slave APs may transmit channel estimation information to the master AP in the UL MU OFDMA scheme.

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 illustrating 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 an arrangement of resource units (RU) used in a 20 MHz band.

6 is a diagram showing an arrangement of a resource unit (RU) used in a 40 MHz band.

7 is a diagram showing the arrangement of resource units (RU) used in 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 scheme.

10 shows the operation according to the 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 subfield included in a per user information field.

14 describes the technical features of the UORA technique.

15 shows an example of a channel used/supported/defined within a 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 shows a modified example of the transmitting device and/or the receiving device of the present specification.

20 shows an example of activating distributed MIMO transmission (eg, joint transmission).

21 is a diagram illustrating multi-AP coordination.

22 shows an example of a null steering operation for interference avoidance.

23 shows an example in which AP coordination and interference are controlled.

24 shows interference nulling and distributed joint beamforming.

25 shows an example of adjusted beamforming.

26 is a diagram for explaining C-OFDMA.

27 shows an example of joint transmission (eg, distributed MIMO).

28 shows an example of performing joint transmission through an M-AP and an S-AP.

29 is a diagram illustrating an example of a network composed of multiple APs.

30 is a diagram illustrating an embodiment of a channel estimation method for performing multi-AP transmission.

31 is a diagram illustrating an embodiment of a channel estimation feedback frame transmitted by an STA.

32 is a diagram illustrating an embodiment of a channel estimation method for performing multi-AP transmission.

33 is a diagram illustrating an embodiment of a feedback frame transmitted by a slave AP.

34 is a diagram illustrating an embodiment of a feedback frame transmitted from a slave AP to a master AP.

35 is a diagram illustrating an example of a network composed of multiple APs.

36 is a diagram illustrating an embodiment of a channel estimation method for performing multi-AP transmission.

37 is a diagram illustrating an embodiment of a channel estimation feedback frame transmitted by an STA.

38 is a diagram illustrating an embodiment of a channel estimation method for performing multi-AP transmission.

39 is a diagram illustrating an embodiment of a feedback frame transmitted by an STA.

40 is a flowchart illustrating an embodiment of a sharing access point (AP) operation.

41 is a flowchart illustrating an embodiment of a shared access point (AP) operation.

42 is a flowchart illustrating an embodiment of a receiving STA (eg, non-AP STA) operation.

In the present specification, “A or B (A or B)” may mean “only A”, “only B” or “both A and B”. In other words, in the present specification, “A or B (A or B)” may be interpreted as “A and/or B (A and/or B)”. For example, in the present specification, “A, B or C (A, B or C)” refers to “only A”, “only B”, “only C”, or “A, B, and any combination of C ( It can mean any combination of A, B and C)”.

A forward slash (/) or comma used in the present specification may mean "and/or". For example, “A/B” may mean “A and/or B”. Accordingly, “A/B” may mean “only A”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, B or C”.

In the present specification, “at least one of A and B” may mean “only A”, “only B”, or “both A and B”. In addition, in this specification, the expression “at least one of A or B” or “at least one of A and/or B” means “at least one It can be interpreted the same as "at least one of A and B".

In addition, in the present specification, “at least one of A, B and C” means “only A”, “only B”, “only C”, or “A, B and C Can mean any combination of A, B and C”. In addition, "at least one of A, B or C" or "at least one of A, B and/or C" means It can mean “at least one of A, B and C”.

In addition, parentheses used in the present specification may mean "for example". Specifically, when displayed as “control information (EHT-Signal)”, “EHT-Signal” may be proposed as an example of “control information”. In other words, “control information” of the present specification is not limited to “EHT-Signal”, and “EHT-Signal” may be suggested 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”.

In the present specification, technical features that are individually described in one drawing may be implemented individually or simultaneously.

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

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

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

The example of FIG. 1 may perform various technical features described below. 1 is related to at least one STA (station). For example, the STAs 110 and 120 of the present specification include a mobile terminal, a wireless device, a wireless transmit/receive unit (WTRU), a user equipment (UE), It may be referred to by various names such as a mobile station (MS), a mobile subscriber unit, or simply a user. STAs 110 and 120 of the present specification may be referred to by 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 referred to by 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 AP and/or non-AP functions. In the present 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 together. For example, communication standards (eg, LTE, LTE-A, 5G NR standards) according to 3GPP standards may be supported. 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 call, video call, data communication, and autonomous driving (Self-Driving, Autonomous-Driving).

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

The STAs 110 and 120 will be described on the basis of the sub-drawing (a) of FIG. 1 as follows.

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 a single chip.

The transceiver 113 of the first STA performs a signal transmission/reception operation. Specifically, IEEE 802.11 packets (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 a 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 transmission signal) to be transmitted through the transceiver.

For example, the second STA 120 may perform an intended operation of a non-AP STA. For example, the non-AP transceiver 123 performs a signal transmission/reception operation. Specifically, IEEE 802.11 packets (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 a 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 reception signal) received through the transceiver 123 and may store a signal (ie, a transmission signal) to be transmitted through the transceiver.

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

For example, in the following specification, an operation of a device indicated as non-AP (or User-STA) may be performed by the first STA 110 or the second STA 120. For example, when the second STA 120 is a non-AP, the operation of the device marked as non-AP is controlled by the processor 121 of the second STA 120 and the processor of the second STA 120 ( A related signal may be transmitted or received through the transceiver 123 controlled by 121). 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 a 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 ( A 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 transmission/reception signals of the AP may be stored in the memory 112 of the first STA 110.

In the following specification, (transmit/receive) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmit/receive) Terminal, (transmit/receive) 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 Devices displayed as /receive) device, (transmit/receive) apparatus, network, etc. may also mean the 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 by the transceivers 113 and 123 of FIG. 1. In addition, in the following example, an operation in which various STAs generate transmission/reception signals or perform data processing or calculation in advance for transmission/reception signals may be performed by 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 calculation in advance for a transmission/reception signal is: 1) Determining bit information of a subfield (SIG, STF, LTF, Data) field included in the PPDU. /Acquisition/configuration/computation/decoding/encoding operations, 2) Time resources or frequency resources (eg, subcarrier resources) used for subfields (SIG, STF, LTF, Data) included in the PPDU, etc. Determination/configuration/retrieve operation, 3) A specific sequence used for the subfields (SIG, STF, LTF, Data) fields included in the PPDU (e.g., pilot sequence, STF/LTF sequence, applied to SIG) An operation of determining/configuring/obtaining an extra sequence), 4) a power control operation and/or a power saving operation applied to the STA, 5) an operation related to determination/acquisition/configuration/calculation/decoding/encoding of an ACK signal, etc. Can include. In addition, in the following example, various information used by various STAs for determination/acquisition/configuration/calculation/decoding/encoding of transmission/reception signals (for example, information related to fields/subfields/control fields/parameters/power, etc.) It may be stored in the memories 112 and 122 of FIG. 1.

The device/STA of the sub-drawing (a) of FIG. 1 described above may be modified as shown in the sub-drawing (b) of FIG. 1. Hereinafter, the STAs 110 and 120 of the present specification will be described based on sub-drawing (b) of FIG. 1.

For example, the transceivers 113 and 123 illustrated in sub-drawing (b) of FIG. 1 may perform the same functions as the transceiver illustrated in sub-drawing (a) of FIG. 1. For example, the processing chips 114 and 124 shown in sub-drawing (b) of FIG. 1 may include processors 111 and 121 and memories 112 and 122. The processors 111 and 121 and the memories 112 and 122 illustrated in sub-drawing (b) of FIG. 1 are the processors 111 and 121 and the memories 112 and 122 illustrated in sub-drawing (a) of FIG. ) And can perform the same function.

A mobile terminal, a wireless device, a wireless transmit/receive unit (WTRU), a user equipment (UE), a mobile station (MS), and a mobile device described below. Mobile Subscriber Unit, user, user STA, network, base station, Node-B, AP (Access Point), repeater, router, relay, receiving device, transmitting device, receiving STA, transmitting The STA, the receiving device, the transmitting device, the receiving Apparatus, and/or the transmitting Apparatus means the STAs 110 and 120 shown in sub-drawings (a)/(b) of FIG. 1, or the sub-drawing of FIG. 1 (b It may mean the processing chips 114 and 124 shown in ). That is, the technical features of the present specification may be performed on the STAs 110 and 120 shown in sub-drawings (a)/(b) of FIG. 1, and the processing chip shown in sub-drawing (b) of FIG. 114, 124). For example, the technical feature of the transmitting STA transmitting the control signal is that the control signal generated by the processors 111 and 121 shown in sub-drawings (a)/(b) of FIG. 1 is sub-drawing (a) of FIG. It can be understood as a technical feature transmitted through the transceivers 113 and 123 shown in )/(b). Alternatively, the technical feature in which the transmitting STA transmits the control signal is a technical feature in which a control signal to be transmitted to the transceivers 113 and 123 is generated from the processing chips 114 and 124 shown in sub-drawing (b) of FIG. 1. Can be understood.

For example, the technical characteristic that the receiving STA receives the control signal may be understood as a technical characteristic in which the control signal is received by the transceivers 113 and 123 shown in sub-drawing (a) of FIG. 1. Alternatively, the technical feature that the receiving STA receives the control signal is that the control signal received by the transceivers 113 and 123 shown in sub-drawing (a) of FIG. 1 is the processor shown in sub-drawing (a) of FIG. 111, 121) can be understood as a technical feature obtained. Alternatively, the technical feature that the receiving STA receives the control signal is that the control signal received by the transceivers 113 and 123 shown in sub-drawing (b) of FIG. 1 is a processing chip shown in sub-drawing (b) of FIG. It can be understood as a technical feature obtained by (114, 124).

Referring to sub-drawing (b) of FIG. 1, software codes 115 and 125 may be included in the memories 112 and 122. The software codes 115 and 125 may include instructions for controlling the operations of the processors 111 and 121. The software codes 115 and 125 may be included in various programming languages.

The processors 111 and 121 or the processing chips 114 and 124 illustrated in FIG. 1 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and/or a data processing device. The processor may be an application processor (AP). For example, the processors 111 and 121 or the processing chips 114 and 124 shown in FIG. 1 are a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator). and demodulator). For example, the processors 111 and 121 or the processing chips 114 and 124 shown in FIG. 1 are SNAPDRAGONTM series processors manufactured by Qualcomm®, EXYNOSTM series processors manufactured by Samsung®, and It may be an A series processor, a HELIOTM series processor manufactured by MediaTek®, an ATOMTM series processor manufactured by INTEL®, or an enhanced processor thereof.

In the present specification, uplink may mean 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 BSS (basic service set) of IEEE (institute of electrical and electronic engineers) 802.11.

Referring to the upper part of FIG. 2, the wireless LAN system may include one or more infrastructure BSSs 200 and 205 (hereinafter, BSS). The BSS (200, 205) is a set of APs and STAs such as an access point (AP) 225 and STA1 (Station, 200-1) that can communicate with each other by successfully synchronizing, and does not indicate a specific area. The BSS 205 may include one or more STAs 205-1 and 205-2 that can be coupled to one AP 230.

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

The distributed system 210 may implement an extended service set (ESS) 240, which is an extended service set, by connecting several BSSs 200 and 205. 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 220 may serve as a bridge for connecting a wireless LAN network (IEEE 802.11) and another network (eg, 802.X).

In the BSS as shown in the upper part of FIG. 2, a network between the APs 225 and 230 and a network between the APs 225 and 230 and the STAs 200-1, 205-1 and 205-2 may be implemented. However, it may be possible to perform communication by setting up a network even between STAs without the APs 225 and 230. A network that performs communication by configuring a network even between STAs without the APs 225 and 230 is defined as an ad-hoc network or an independent basic service set (IBSS).

The lower part of FIG. 2 is a conceptual diagram showing IBSS.

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

3 is a diagram illustrating a general link setup process.

In the illustrated 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 must find a network that can participate. The STA must identify a compatible network before participating in the wireless network. The process of identifying a network existing in a specific area is called scanning. Scanning methods include active scanning and passive scanning.

3 illustrates an example of a network discovery operation including an active scanning process. In active scanning, an STA performing scanning transmits a probe request frame to search for an AP present in the vicinity while moving channels and waits for a response thereto. The responder transmits a probe response frame in response to the probe request frame to the STA that has transmitted the probe request frame. Here, the responder may be an STA that last transmitted a beacon frame in the BSS of the channel being scanned. In BSS, since the AP transmits a beacon frame, the AP becomes a responder, and in IBSS, the responder is not constant because STAs in the IBSS rotate and transmit the beacon frame. 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 stores the next channel (e.g., 2 Channel) and scanning (that is, probe request/response transmission/reception on channel 2) in the same manner.

Although not shown in the example of FIG. 3, the scanning operation may be performed in 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 the management frames in IEEE 802.11, and is periodically transmitted so that an STA that notifies the existence of a wireless network and performs scanning can find a wireless network and participate in the wireless network. In the BSS, the AP performs a role of periodically transmitting a beacon frame, and in IBSS, the STAs in the IBSS rotate and transmit the beacon frame. When the STA performing the scanning receives the beacon frame, it stores information on the BSS included in the beacon frame, moves to another channel, and records the beacon frame information in each channel. The STA receiving the beacon frame may store BSS-related information included in the received beacon frame, move to the next channel, and perform scanning in the next channel in the same manner.

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

The authentication frame consists of an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a robust security network (RSN), and a finite cycle group. Group), etc. can be included.

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 STA that has been successfully authenticated may perform a connection process based on step S330. The association process includes a process in which the STA transmits an association request frame to the AP, and in response thereto, the AP transmits an association response frame to the STA. For example, the connection request frame includes information related to various capabilities, beacon listening intervals, service set identifiers (SSIDs), supported rates, supported channels, RSNs, and mobility domains. , Supported operating classes, TIM broadcast request, interworking service capability, and the like may be included. For example, the connection response frame includes information related to various capabilities, status codes, AID (Association ID), support rate, Enhanced Distributed Channel Access (EDCA) parameter set, Received Channel Power Indicator (RCPI), Received Signal to Noise (RSNI). Indicator), mobility domain, timeout interval (association comeback time), overlapping BSS scan parameter, TIM broadcast response, QoS map, etc. may be included.

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

In addition, FIG. 4 also includes an example of an 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, the HE-PPDU for multiple users (MU) is L-STF (legacy-short training field), L-LTF (legacy-long training field), L-SIG (legacy-signal), HE-SIG-A (high efficiency-signal A), HE-SIG-B (high efficiency-signal-B), HE-STF (high efficiency-short training field), HE-LTF (high efficiency-long training field) , A data field (or MAC payload), and a packet extension (PE) field. Each field may be transmitted during the illustrated time period (ie, 4 or 8 μs, 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, even when a signal is transmitted to one STA, a resource unit may be defined. The resource unit can be used for STF, LTF, data fields, and the like.

5 is a diagram showing an arrangement of resource units (RU) used in a 20 MHz band.

As shown 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 (ie, units corresponding to 26 tones) may be arranged. In the leftmost band of the 20MHz band, 6 tones may be used as a guard band, and in the rightmost band of the 20MHz band, 5 tones may be used as the guard band. In addition, 7 DC tones are inserted in the center band, that is, the DC band, and 26-units corresponding to 13 tones may exist on 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, i.e. a user.

Meanwhile, the RU arrangement of FIG. 5 is utilized not only in a situation for a plurality of users (MU), but also in a situation for a single user (SU). In this case, as shown in the bottom of FIG. 5, one 242-unit is used. It is possible to use and in this case 3 DC tones can be inserted.

In the example of FIG. 5, RUs of various sizes, that is, 26-RU, 52-RU, 106-RU, 242-RU, etc., have been 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 diagram showing an arrangement of a resource unit (RU) used in a 40 MHz band.

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

Also, as shown, when used for a single user, a 484-RU may 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 diagram showing the arrangement of resource units (RU) used in the 80MHz band.

Similar to the use of RUs of various sizes in the examples of FIGS. 5 and 6, the example of FIG. 7 may also be used with 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 as guard bands in the leftmost band of the 80MHz band, and 11 tones are used in the rightmost band of the 80MHz band. It can be used as a guard band. In addition, 26-RU using 13 tones located on the left and right of the DC band can be used.

In addition, as shown, when used for a single user, a 996-RU may be used, and in this case, five DC tones may be inserted.

On the other hand, the fact that the specific number of RUs can be changed is the same as the examples of FIGS. 5 and 6.

The RU arrangement (ie, RU location) shown in FIGS. 5 to 7 can 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 RU arrangement for 80 MHz (that is, the example of FIG. 7) is repeated twice, or the RU arrangement for the 40 MHz (that is, the example of FIG. 6) is 4 times. Can be repeated. In addition, when the EHT PPDU is configured in the 320 MHz band, the arrangement of the RU for 80 MHz (example of FIG. 7) may be repeated 4 times or the arrangement of the RU for 40 MHz (ie, example of FIG. 6) may be repeated 8 times. have.

One RU of the present specification may be allocated for only one STA (eg, non-AP). Alternatively, 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 the trigger frame is performed, the transmitting STA (eg, AP) transmits the first RU (eg, 26/52/106) to the first STA through the trigger frame. /242-RU, etc.), and a second RU (eg, 26/52/106/242-RU, etc.) may be allocated to the second STA. 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 2 STAs may be assigned a second RU (eg, 26/52/106/242-RU, etc.). That is, the transmitting STA (eg, AP) may transmit the HE-STF, HE-LTF, and Data fields for the first STA through the first RU within one MU PPDU, and the second RU through the second RU. HE-STF, HE-LTF, and Data fields for 2 STAs can 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 the SIG-B. The user-individual field 830 may be referred to as a user-individual control field. When the SIG-B is transmitted to a plurality of users, the user-individual field 830 may be applied to only some of the plurality of users.

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

The common field 920 may include RU allocation information of N*8 bits. For example, the RU allocation information may include information on 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 allocated in which frequency band. .

An example of a case in which RU allocation information is composed of 8 bits is as follows.

As in the example of FIG. 5, a maximum of 9 26-RUs may be allocated to a 20 MHz channel. As shown in Table 8, when the RU allocation information of the common field 820 is set to “00000000”, nine 26-RUs may be allocated to a corresponding channel (ie, 20 MHz). In addition, as shown in Table 1, when the RU allocation information of the common field 820 is set to "00000001", seven 26-RUs and one 52-RU are arranged in a corresponding channel. That is, in the example of FIG. 5, 52-RUs may be allocated to the rightmost side and seven 26-RUs may be allocated to the left side.

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

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

"01000y2y1y0" relates to an example in which 106-RU is allocated to the leftmost-left side of a 20 MHz channel, and five 26-RUs are allocated to the right side. In this case, a plurality of STAs (eg, User-STAs) may be allocated to the 106-RU based on the MU-MIMO technique. Specifically, up to 8 STAs (eg, User-STA) may be allocated to 106-RU, and the number of STAs (eg, User-STA) allocated to 106-RU is 3-bit information (y2y1y0). ). For example, when 3-bit information (y2y1y0) is set to N, the number of STAs (eg, User-STAs) allocated to 106-RU based on the MU-MIMO technique may be N+1.

In general, a plurality of different STAs (eg, user STAs) may be allocated to a plurality of RUs. However, for one RU of 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 shown 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 the RU allocation information in 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 nine 26-RUs (ie, a total of 9 User STAs are allocated). That is, up to 9 User STAs may be allocated to a specific channel through the OFDMA scheme. In other words, up to 9 User STAs may be allocated to a specific channel through a non-MU-MIMO scheme.

For example, when RU allocation is set to “01000y2y1y0”, a plurality of User STAs are allocated to 106-RUs disposed on the leftmost-left through the MU-MIMO scheme, and five 26-RUs disposed on the right side are allocated Five User STAs may be allocated through a non-MU-MIMO scheme. This case is embodied through an 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 scheme.

For example, when RU allocation is set to “01000010” as shown in FIG. 9, based on Table 2, 106-RUs are allocated to the leftmost-left side of a specific channel, and five 26-RUs are allocated to the right side. I can. In addition, a total of three User STAs may be allocated to the 106-RU through the MU-MIMO scheme. 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. In addition, as shown in FIG. 8, two User fields may be implemented as one User block field.

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

Each User field may have the same size (eg, 21 bits). For example, the User Field of the first format (the format of the MU-MIMO scheme) 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 allocated (eg, STA-ID, partial AID, etc.) It may include. In addition, the second bit (eg, B11-B14) in the user field (ie, 21 bits) may include information on 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 (i.e., B11-B14) may include information on the number of Spatial Streams allocated to a plurality of User STAs allocated according to the MU-MIMO scheme. have. For example, when three User STAs are allocated to 106-RU based on the MU-MIMO scheme as shown in FIG. 9, N_user is set to “3”, and accordingly, as shown in Table 3, N_STS[1], Values of N_STS[2] and N_STS[3] may be determined. For example, when the value of the second bits B11-B14 is “0011”, it may be set to N_STS[1]=4, N_STS[2]=1, and N_STS[3]=1. That is, in the example of FIG. 9, 4 Spatial Streams may be allocated to User field 1, 1 Spatial Stream may be allocated to User field 2, and 1 Spatial Stream may be allocated to User field 3.

As in the example of Table 3 and/or Table 4, information on the number of spatial streams for a user STA (that is, the second bit, B11-B14) may consist of 4 bits. In addition, information on the number of spatial streams for a user STA (ie, second bits, 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 4 spatial streams for one user STA.

In addition, the third bit (ie, B15-18) in the user field (ie, 21 bits) may include MCS (Modulation and coding scheme) information. MCS information may be applied to a data field in a PPDU in which the corresponding SIG-B is included.

MCS, MCS information, MCS index, MCS field, and the like used in the present specification may be indicated by a specific index value. For example, MCS information may be indicated by index 0 to index 11. The MCS information includes information on a constellation modulation type (e.g., BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM, etc.), and a coding rate (e.g., 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.

In addition, 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 on the coding type (eg, BCC or LDPC). That is, the fifth bit (ie, B20) may include information on 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 (the format of the MU-MIMO scheme). An example of the User field of the second format (non-MU-MIMO format) 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. In addition, 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 the beamforming steering matrix is applied. The fourth bit (eg, B15-B18) in the User field of the second format may include MCS (Modulation and Coding Scheme) information. In addition, the fifth bit (eg, B19) in the User field of the second format may include information on whether or not Dual Carrier Modulation (DCM) is applied. In addition, the sixth bit (ie, B20) in the user field of the second format may include information on the coding type (eg, BCC or LDPC).

10 shows the operation according to the UL-MU. As shown, a transmitting STA (eg, an AP) may perform channel access through contending (ie, a backoff operation) and transmit a trigger frame 1030. That is, the transmitting STA (eg, AP) may transmit a 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 equal to SIFS.

The TB PPDUs 1041 and 1042 may be transmitted at the same time slot and may be transmitted from a plurality of STAs (eg, User STAs) in which an AID is indicated in the trigger frame 1030. The ACK frame 1050 for the TB PPDU may be implemented in various forms.

Specific characteristics of the trigger frame will be described with reference to FIGS. 11 to 13. Even when UL-MU communication is used, an orthogonal frequency division multiple access (OFDMA) technique or an MU MIMO technique can be used, and an OFDMA and MU MIMO technique can 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), and may be transmitted from an AP, for example. The trigger frame may be composed of a MAC frame and may be included in a PPDU.

Each of the fields shown 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 setting NAV or an identifier of the STA (for example, For example, information on AID) may be included.

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

In addition, it is preferable to include individual 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 “allocation 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 shown in FIG. 11 may again include a plurality of subfields.

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. In addition, the length of each of the illustrated subfields may 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 in response to the corresponding trigger frame, and the length field of the L-SIG field of the uplink PPDU represents the length of the uplink PPDU. As a result, the length field 1210 of the trigger frame may be used to indicate the length of the corresponding uplink PPDU.

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

The CS request field 1230 indicates whether to consider the state of the radio medium or the NAV in a situation in which the receiving device receiving the corresponding trigger frame transmits the corresponding uplink PPDU.

The HE-SIG-A information field 1240 may include information for controlling the content of the SIG-A field (ie, the HE-SIG-A field) of the uplink PPDU transmitted in response to the corresponding trigger frame.

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

In this specification, it may be assumed that the trigger type field 1260 of the trigger frame indicates a basic type of 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 subfield included in a per user information field. The user information field 1300 of FIG. 13 may be understood as any of the individual user information fields 1160#1 to 1160#N mentioned in FIG. 11 above. Some of the subfields included in the user information field 1300 of FIG. 13 may be omitted, and other subfields may be added. In addition, the length of each of the illustrated subfields may be changed.

A user identifier field 1310 of FIG. 13 indicates 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.

In addition, an RU Allocation field 1320 may be included. That is, when the receiving STA identified by the user identifier field 1310 transmits the TB PPDU corresponding to the trigger frame, it transmits the TB PPDU 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 subfield of FIG. 13 may include a coding type field 1330. The coding type field 1330 may indicate the coding type of the 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.

In addition, the subfield of FIG. 13 may include an MCS field 1340. The MCS field 1340 may indicate an MCS scheme applied to a 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 UL OFDMA-based Random Access (UORA) technique will be described.

14 describes the technical features of the UORA technique.

The transmitting STA (eg, AP) may allocate 6 RU resources as shown in FIG. 14 through a trigger frame. Specifically, the AP is a first RU resource (AID 0, RU 1), a second RU resource (AID 0, RU 2), a third RU resource (AID 0, RU 3), a fourth RU resource (AID 2045, RU 4), a fifth RU resource (AID 2045, RU 5), and a sixth RU resource (AID 3, RU 6) may be allocated. Information on 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, for example, the RU allocation field 1320 of FIG. 13. AID=0 may mean a UORA resource for an associated STA, and AID=2045 may mean a UORA resource for an un-associated STA. Accordingly, the first to third RU resources of FIG. 14 may be used as UORA resources for an associated STA, and the fourth to fifth RU resources of FIG. 14 are for un-associated STAs. 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 OBO (OFDMA random access BackOff) counter of STA1 is reduced to 0, and STA1 randomly selects the second RU resources (AID 0, RU 2). In addition, since the OBO counter of STA2/3 is greater than 0, uplink resources are not allocated to STA2/3. In addition, since STA4 in FIG. 14 includes its AID (ie, AID=3) in the trigger frame, resources of RU 6 are allocated without backoff.

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

15 shows an example of a channel used/supported/defined within a 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 refer to a frequency region in which channels having a center frequency adjacent to 2.4 GHz (eg, channels having a center frequency located within 2.4 to 2.5 GHz) are used/supported/defined.

The 2.4 GHz band may contain multiple 20 MHz channels. 20 MHz in the 2.4 GHz band may have multiple channel indexes (eg, index 1 to index 14). For example, a center frequency of a 20 MHz channel to which channel index 1 is assigned may be 2.412 GHz, a center frequency of a 20 MHz channel to which channel index 2 is assigned may be 2.417 GHz, and 20 MHz to which channel index N is assigned The center frequency of the channel may be (2.407 + 0.005*N) GHz. The channel index may be referred to by various names such as channel number. Specific values of the channel index and the center frequency may be changed.

15 exemplarily shows four channels in a 2.4 GHz band. Each of the illustrated first to fourth frequency regions 1510 to 1540 may include one channel. For example, the first frequency domain 1510 may include channel 1 (a 20 MHz channel having 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 channel 11 may be set to 2462 MHz. The fourth frequency domain 1540 may include channel 14. At this time, the center frequency of 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 another name such as the second band/band. The 5 GHz band may mean 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 values shown in FIG. 16 may be changed.

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

A plurality of channels may be set within 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, a frequency range/range of 5170 MHz to 5330 MHz in UNII-1 and UNII-2 may be divided into eight 20 MHz channels. The frequency range/range from 5170 MHz to 5330 MHz can be divided into four channels through the 40 MHz frequency domain. The 5170 MHz to 5330 MHz frequency domain/range can 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 as a third band/band. The 6 GHz band may mean a frequency region in which channels with a center frequency of 5.9 GHz or more are used/supported/defined. The specific 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, the leftmost channel of the 20 MHz channel of FIG. 17 may have an index number 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 of 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, It may be 165, 169, 173, 177, 181, 185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229, 233. In addition, according to the above-described (5.940 + 0.005*N) GHz rule, the index of the 40 MHz channel in 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, a 240 MHz channel or a 320 MHz channel may be added.

Hereinafter, the PPDU transmitted/received by the STA of the present specification will be described.

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

The PPDU of FIG. 18 may be referred to as various names such as EHT PPDU, transmission PPDU, reception PPDU, 1st type or Nth type PPDU. In addition, it can be used in the EHT system and/or a new wireless LAN system that has improved the EHT system.

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

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

The SIG A and/or SIG B fields of FIG. 18 may include additional fields (eg, SIG C or one control symbol, etc.). Of the SIG A and SIG B fields, all/some of the subcarrier spacing and all/some of the additionally defined SIG fields may be set to 312.5 kHz. Meanwhile, the subcarrier spacing for a part of the newly defined SIG field may be set to a preset value (eg, 312.5 kHz or 78.125 kHz).

In the PPDU of FIG. 18, the L-LTF and the L-STF may be the same as the conventional field.

The L-SIG field of FIG. 18 may include, for example, 24-bit bit information. For example, the 24-bit information may include a 4 bit Rate field, 1 bit Reserved bit, 12 bit Length field, 1 bit Parity bit, and 6 bit Tail bit. For example, the 12-bit Length field may include information on the number of octets of a Physical Service Data Unit (PSDU). For example, the value of the 12-bit Length field may be determined based on the type of PPDU. For example, when the PPDU is a non-HT, HT, VHT PPDU or EHT PPDU, the value of the Length field may be determined as a multiple 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, for non-HT, HT, VHT PPDU or EHT PPDU, the value of the Length field can be determined as a multiple of 3, and for HE PPDU, the value of the Length field is "multiple of 3 + 1" or "multiple of 3 It can be determined as +2”.

For example, the transmitting STA may apply BCC encoding based on a code rate of 1/2 to 24-bit information of the L-SIG field. Thereafter, the transmitting STA may obtain a 48-bit BCC coded bit. BPSK modulation is applied to the 48-bit coded bits, so that 48 BPSK symbols may be generated. The transmitting STA may map 48 BPSK symbols to locations 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 indices -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 a signal of {-1, -1, -1, 1} to the subcarrier index {-28, -27, +27, +28}. The above signal can be used for channel estimation in the frequency domain corresponding to {-28, -27, +27, +28}.

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

After the RL-SIG of FIG. 18, for example, EHT-SIG-A or one control symbol may be inserted. Symbols located after RL-SIG (ie, EHT-SIG-A or one control symbol in the present specification) may be referred to as various names such as a U-SIG (Universal SIG) field.

A symbol (eg, U-SIG) consecutive to the RL-SIG may include information of N bits, and may include information for identifying the type of EHT PPDU. For example, the U-SIG may be configured based on two symbols (eg, two consecutive OFDM symbols). Each symbol (eg, OFDM symbol) for U-SIG may have a duration of 4 us. Each symbol of U-SIG can be used to transmit 26 bits of information. For example, each symbol of U-SIG may be transmitted and received based on 52 data tones and 4 pilot tones.

Through the U-SIG (or U-SIG field), for example, A-bit information (eg, 52 un-coded bits) may be transmitted, and the first symbol of U-SIG is the first of the total A-bit information. X-bit information (eg, 26 un-coded bits) is transmitted, and the second symbol of U-SIG can transmit remaining Y-bit information (eg, 26 un-coded bits) of the total A-bit information. have. For example, the transmitting STA may acquire 26 un-coded bits included in each U-SIG symbol. The transmitting STA may generate a 52-coded bit by performing convolutional encoding on the basis of a rate of R=1/2, and may perform interleaving on the 52-coded bit. The transmitting STA may generate 52 BPSK symbols allocated to each U-SIG symbol by performing BPSK modulation on the interleaved 52-coded bits. One U-SIG symbol may be transmitted based on 56 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. 52 BPSK symbols generated by the transmitting STA may be transmitted based on the remaining tones (subcarriers) excluding the pilot tones -21, -7, +7, and +21 tones.

For example, A-bit information (e.g., 52 un-coded bits) transmitted by U-SIG is a CRC field (e.g., a 4-bit long field) and a tail field (e.g., a 6-bit long field). ) Can be included. The CRC field and the tail field may be transmitted through the second symbol of U-SIG. The CRC field may be generated based on 26 bits allocated to the first symbol of U-SIG and the remaining 16 bits excluding the CRC/tail field in the second symbol, and may be generated based on a conventional CRC calculation algorithm. I can. In addition, the tail field may be used to terminate trellis of a convolutional decoder, and may be set to “000000”, for example.

A bit information (eg, 52 un-coded bits) transmitted by U-SIG (or U-SIG field) may be divided into version-independent bits and version-dependent bits. For example, the size of version-independent bits may be fixed or variable. For example, version-independent bits may be allocated only to the first symbol of U-SIG, or version-independent bits may be allocated to both the first symbol and the second symbol of U-SIG. For example, version-independent bits and version-dependent bits may be referred to by various names such as a first bit and a second bit.

For example, the version-independent bits of U-SIG may include a 3-bit PHY version identifier. For example, the 3-bit PHY version identifier may include information related to the PHY version of the transmission/reception PPDU. For example, the first value of the 3-bit PHY version identifier may indicate that the transmission/reception PPDU is an EHT PPDU. In other words, when transmitting the EHT PPDU, the transmitting STA may set a 3-bit PHY version identifier as the first value. In other words, the receiving STA may determine that the received PPDU is an EHT PPDU based on the PHY version identifier having the first value.

For example, the version-independent bits of U-SIG may include a 1-bit UL/DL flag field. The first value of the 1-bit UL/DL flag field is related to UL communication, and the second value of the UL/DL flag field is related to DL communication.

For example, the version-independent bits of U-SIG may include information on the length of TXOP and information on the BSS color ID.

For example, when the EHT PPDU is classified 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.) , Information about the type of the EHT PPDU may be included in version-independent bits or version-dependent bits of U-SIG.

For example, the U-SIG field is 1) a bandwidth field containing information about the bandwidth, 2) a field containing information about the MCS technique applied to SIG-B, and 3) dual subcarrier modulation in SIG-B ( An indication field containing information related to whether or not dual subcarrier modulation) is applied, 4) A field containing information about the number of symbols used for SIG-B, 5) Whether SIG-B is generated over the entire band It may include a field including information on whether or not, 6) a field including information on an LTF/STF type, and 7) information on a field indicating the length of the LTF and the length of the CP.

The SIG-B of FIG. 18 may include the technical features 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 an OFDMA environment. The LTF of FIG. 18 may be used to estimate a channel in a MIMO environment or an OFDMA environment.

The STF of FIG. 18 may be set in various types. For example, the first type of STF (that is, 1x STF) 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 0.8 μs period signal may be repeated 5 times to become a first type STF having a length of 4 μs. For example, the second type of STF (that is, 2x STF) 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 1.6 μs period signal 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 intervals of four subcarriers. The STF signal generated based on the third type STF sequence may have a period of 3.2 μs, and the period signal of 3.2 μs 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 type 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, GIs of various lengths (eg, 0.8/1/6/3.2 μs) may be applied to the first/second/third type LTF.

Information on the type of STF and/or LTF (including information on GI applied to the 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, data) of FIG. 18 may be configured based on RUs 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 (ie, when MU PPDU is used), some fields (eg, STF, LTF, data) of FIG. 18 are shown in FIGS. 5 to 7, etc. 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 are transmitted and received through the second RU. Can be. In this case, the positions of the first and second RUs 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 items. For example, 1) the first symbol after the L-LTF signal of the received PPDU is BPSK, 2) 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 an EHT PPDU. When the received PPDU is determined to be an EHT PPDU, the receiving STA is the type of the EHT PPDU (e.g., SU/MU/Trigger-based/Extended Range type) based on bit information included in the symbol after RL-SIG of FIG. ) Can be detected. In other words, the receiving STA is 1) the first symbol after the L-LTF signal, which is BSPK, 2) RL-SIG that is consecutive to the L-SIG field and is the same as L-SIG, 3) the result of applying “modulo 3” L-SIG including a Length field set to 0”, and 4) a received PPDU based on a 3-bit PHY version identifier (eg, a PHY version identifier having a first value) of the aforementioned U-SIG. It can be judged as EHT PPDU.

For example, the receiving STA may determine the type of the received PPDU as an HE PPDU based on the following. For example, 1) the first symbol after the L-LTF signal is BPSK, 2) RL-SIG repeating L-SIG is detected, and 3) “modulo 3” is applied to the length value of L-SIG. When the result is detected as “1” or “2”, the received PPDU may be determined as an 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 items. For example, if 1) the first symbol after the L-LTF signal is BPSK, and 2) the L-SIG repeating RL-SIG is not detected, the received PPDU will be determined as non-HT, HT and VHT PPDU. I can. In addition, even if the receiving STA detects the repetition of RL-SIG, if the result of applying “modulo 3” to the length value of L-SIG is detected as “0”, the receiving PPDU is non-HT, HT and VHT PPDU. It can be judged as.

In the following example, (transmit/receive/uplink/downward) signal, (transmit/receive/uplink/downlink) frame, (transmit/receive/uplink/downlink) packet, (transmit/receive/uplink/downlink) data unit, ( A signal displayed as transmission/reception/up/down) data may be a signal transmitted/received based on the PPDU of FIG. 18. The PPDU of FIG. 18 may be used to transmit and receive various types of frames. For example, the PPDU of FIG. 18 may be used for a control frame. An example of a control frame may include request to send (RTS), clear to send (CTS), Power Save-Poll (PS-Poll), BlockACKReq, BlockAck, NDP (Null Data Packet) announcement, and Trigger Frame. For example, the PPDU of FIG. 18 may 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, and Probe Response frame. For example, the PPDU of FIG. 18 may 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.

19 shows a modified example of the transmitting device and/or the receiving device of the present specification.

Each of the devices/STAs of sub-drawings (a)/(b) of FIG. 1 may be modified as shown in FIG. 19. The transceiver 630 of FIG. 19 may be the same as the transceivers 113 and 123 of FIG. 1. The transceiver 630 of FIG. 19 may include a receiver and a transmitter.

The processor 610 of FIG. 19 may be the same as the processors 111 and 121 of FIG. 1. Alternatively, the processor 610 of FIG. 19 may be the same as the processing chips 114 and 124 of FIG. 1.

The memory 150 of FIG. 19 may be the same as the memories 112 and 122 of FIG. 1. Alternatively, the memory 150 of FIG. 19 may be a separate external memory different from the memories 112 and 122 of FIG. 1.

Referring to FIG. 19, the power management module 611 manages power for the processor 610 and/or the transceiver 630. The battery 612 supplies power to the power management module 611. The display 613 outputs a result processed by the processor 610. Keypad 614 receives input to be used by processor 610. The keypad 614 may be displayed on the display 613. The SIM card 615 may be an integrated circuit used to securely store an IMSI (international mobile subscriber identity) used to identify and authenticate a subscriber in a mobile phone device such as a mobile phone and a computer and a key associated therewith. .

Referring to FIG. 19, the speaker 640 may output a sound-related result processed by the processor 610. The microphone 641 may receive a sound-related input to be used by the processor 610.

Mesh Wi-Fi (Multi-AP Solution) is well accepted in the market for better coverage, easy deployment and high throughput.

It is desirable to improve the performance of mesh Wi-Fi by optimizing the joint of MAC and PHY for multi-AP systems. Hardware for multi-AP systems is already on the market and, unlike 16 spatial streams, costs little.

There are great techniques to improve the performance of multi-AP systems. Distributed MIMO, cooperative transmission, space/time/frequency sharing and reuse, and effective relay schemes.

20 shows an example of activating distributed MIMO transmission (eg, joint transmission). Referring to FIG. 20, AP 1 transmits a coordination signal to AP 2 and AP 3 to start distributed MIMO transmission. AP 2 and AP 3 transmit and receive data with a plurality of STAs using OFDMA and MU-MIMO within one data packet. STA 2 and STA 3 are in different resource units (RU), and each RU is a frequency segment. STA 1 and STA 4 are in the same resource unit using MU-MIMO. Each RU may be transmitted in multiple spatial streams.

21 is a diagram illustrating multi-AP coordination.

Multi-AP coordination utilizes a wired (eg, enterprise) or wireless (eg, home mesh) backbone for data+clock synchronization.

In addition, multi-AP coordination has improved link budget and regulated power limitations than a single AP with a large antenna array.

Techniques for multi-AP coordination include null steering for interference avoidance, joint beamforming, and joint MU-MIMO.

Example 1: null steering for interference avoidance

22 shows an example of a null steering operation for interference avoidance. Null steering for interference avoidance is useful when the AP has a large dimension (4x4 or 8x8).

23 shows an example in which AP coordination and interference are controlled.

Coordinated scheduling: Coordinated scheduling mitigates/reduces the number of collisions from AP/STA of another BSS.

In addition, coordinated scheduling is a distributed mechanism, and increases the number/probability of parallel transmission in a coordinated manner rather than spatial reuse. Message exchange between APs is required.

24 shows interference nulling and distributed joint beamforming.

Coordinated beamforming: Coordinated beamforming can designate a nulling point to another STA or perform downlink transmission at the same time without co-channel interference due to beamforming, such as distributed joint beamforming. have.

In addition, coordinated beamforming is suitable for managed deployments (eg, corporate offices, hotels), and has the advantage of area throughput and a consistent user experience. In addition, adjusted beamforming requires adjusted downlink scheduling and improved MU sounding to reduce overhead and synchronization.

25 shows an example of adjusted beamforming.

The solid arrow in FIG. 25 indicates data transmission within the BSS STA, and the dotted arrow in FIG. 25 is null transmitted to the OBSS STAs. As a main attribute, a signal to a user is transmitted from only one AP while forming null in the OBSS STA.

26 is a diagram for explaining C-OFDMA.

Coordinated-OFDMA (C-OFDMA) is an extension of 11ax OFDMA from a single BSS to a multiple BSS scenario. In addition, C-OFDMA efficiently utilizes frequency resources throughout the network. In addition, C-OFDMA improves efficiency when BSS traffic does not fully utilize resources.

Referring to FIG. 26, a spectrum 2610 used for transmission of BSS1 and a spectrum 2620 used for transmission of BSS2 each exist in a 20MHz band in a total 40MHz band. Synchronized transmission can be performed to obtain orthogonality. STAs 1 to 3 are allocated to the spectrum 2610 used for transmission of BSS1, and STAs 4 and 5 are allocated to the spectrum 2620 used for transmission of BSS2.

27 shows an example of joint transmission (eg, distributed MIMO).

It means performing joint transmission and joint beamforming to a single STA (J-Tx). Referring to FIG. 27, one STA is receiving service by AP1 and AP2.

Joint transmission may have stricter synchronization requirements and should be considered separately. Joint transmission can be performed more easily than joint processing transmission for multiple STAs. However, joint transmission may exploit beamforming and power gain from multiple APs.

28 shows an example of performing joint transmission through an M-AP and an S-AP.

The M-AP (Master AP) acts as an AP coordinator. S-AP (Slave AP) participates in joint transmission coordinated by the M-AP, and may have both the functions of the STA and the AP. Referring to FIG. 28, S-AP1 has an STA function in a coordination step, and S-AP2 has an AP function in a joint transmission step.

Multi-AP coordination technology in a wireless LAN system minimizes interference between BSSs when transmitting and receiving data by sharing channel feedback information and scheduling information of terminals between APs when transmitting and receiving data frames between the terminals and APs Two or more APs participate in this method to increase data transmission efficiency. In the WLAN system, such a multi-AP coordination technology has not yet been standardized, but in IEEE802.11 EHT TIG, a discussion on standardization related to Multi-AP coordination as a next-generation technology is underway. In this specification, a method in which multiple APs can participate in data transmission using multi-AP coordination in a wireless LAN system is proposed. Multi-AP (MAP) transmission may include joint transmission and coordinated transmission. Joint transmission is a method in which multiple APs simultaneously transmit one piece of data to an STA using their antennas. The coordinated transmission is a method of simultaneously transmitting one data to the STA using a coordinated scheduling method, a coordinated beamforming method, a C-OFDMA method, a coordinated spatial reuse method, and the like. The adjusted space reuse method is a method of reusing the same time-frequency resource in another space by using power intensity.

An example of the present specification described below is related to a technical feature in which a master AP controls signal transmission of slave APs. Devices described below (e.g., master AP, slave AP, STA (station)) may be the STAs of FIG. 1, and signals or PPDUs described below are of FIG. Can be based on PPDU.

In this specification, the sharing AP may include an AP that performs a master AP operation. The sharing AP of the present specification may be replaced with various expressions. For example, the sharing AP may be replaced with various expressions such as a master AP, a first AP and/or a transmitting AP. In the present specification, the shared AP may include an AP that performs a slave AP operation. The shared AP of the present specification may be replaced with various expressions. For example, the shared AP may be replaced with various expressions such as a slave AP, a first AP and/or a transmitting AP.

The shared AP (eg, a slave AP) may receive a feedback frame from the STA. The feedback frame (eg, MAP reference feedback frame) includes feedback information between a first shared AP (S-AP 1) and an STA, feedback information between a second shared AP (S-AP 2) and an STA, and a third share It may include feedback information between the de AP (S-AP 3) and the STA. The feedback frame transmitted by STA a may include all of channel information between STA a and the first shared AP, channel information between STA a and the second shared AP, and channel information between STA a and the third shared AP. . The feedback frame may include subfields including feedback information related to each shared AP. When there are three shared APs, the feedback frame may include a feedback subfield for the first shared AP, a feedback subfield for the second shared AP, and a feedback subfield for the third shared AP. . The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frame may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like. STA a may transmit a feedback frame to the first shared AP that has made an association with STA a. After the first shared AP receives the feedback frame from STA a, the second shared AP may transmit the MAP poll frame to the STA b associated with the second shared AP. STA b may receive the MAP poll frame from the second shared AP. When STA b receives the MAP poll frame, it may transmit a feedback frame to the second shared AP that has established an association. The order in which STAs transmit feedback frames may be determined by the sharing AP. For example, the sharing AP may transmit a MAP trigger frame notifying the start of a channel estimation procedure to the shared APs, and the MAP trigger frame may include information related to an order in which STAs transmit a feedback frame. For example, shared APs may use a null data packet (NDP) frame as a reference signal. Shared APs may transmit a null data packet announcement (NDPA) frame to STAs before transmitting the NDP frame. The NDPA frame may include information related to an order in which STAs transmit a feedback frame. For example, information related to the order in which STAs transmit the feedback frame may be included in the STA information subfield of the NDPA frame. The STA can receive the NDPA frame and know the order of transmitting the feedback frame. After that, the STA may receive the NDP frame and estimate the channel. The STA may transmit a feedback frame including channel information based on an order of transmitting the feedback frame.

The feedback frame (e.g., MAP reference feedback frame) is feedback information between a first shared AP (S-AP 1) and an STA, feedback information between a second shared AP (S-AP 2) and an STA, and a sharing AP It may include feedback information between the (M-AP) and the STA. The feedback frame transmitted by STA a may include channel information between STA a and the first shared AP, channel information between STA a and the second shared AP, and channel information between STA a and the sharing AP. The feedback frame may include subfields including feedback information related to each shared AP. When one sharing AP and two shared APs exist, the feedback frame includes a feedback subfield for the first shared AP, a feedback subfield for the second shared AP, and a feedback subfield for the sharing AP. Can include. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frame may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like. The STA (eg, STA a) may transmit a feedback frame to the sharing AP. The next STA (eg, STA b) may receive the MAP poll frame from the sharing AP. When the next STA receives the MAP poll frame, it may transmit a feedback frame to the sharing AP. The order in which the STAs (STA a, STA b) transmit the feedback frame may be determined by the sharing AP. For example, the sharing AP may transmit a MAP trigger frame notifying the start of a channel estimation procedure to the shared APs, and the MAP trigger frame may include information related to an order in which STAs transmit a feedback frame. For example, the sharing AP and the shared AP may use a null data packet (NDP) frame as a reference signal. The sharing AP and the shared AP may transmit a null data packet announcement (NDPA) frame to STAs before transmitting the NDP frame. The NDPA frame may include information related to an order in which STAs transmit a feedback frame. For example, information related to the order in which STAs transmit the feedback frame may be included in the STA information subfield of the NDPA frame. The STA can receive the NDPA frame and know the order of transmitting the feedback frame. After that, the STA may receive the NDP frame and estimate the channel. The STA may transmit a feedback frame including channel information based on an order of transmitting the feedback frame.

The feedback frame 3910 is a feedback frame (eg, MAP reference feedback frame) transmitted by STA a, and the feedback frame 3920 is a feedback frame (eg, MAP reference feedback frame) transmitted by STA b. The feedback frame 3910 may include all of channel information between STA a and the first shared AP, channel information between STA a and the second shared AP, and channel information between STA a and the sharing AP. The feedback frame 3920 may include all of channel information between STA b and the first shared AP, channel information between STA b and the second shared AP, and channel information between STA b and the sharing AP. The feedback frame may include subfields including feedback information related to each shared AP and the sharing AP. When there are two shared APs, the feedback frame 3910 includes a feedback subfield 3911 for the sharing AP, a feedback subfield 3912 for the first shared AP, and a feedback for the second shared AP. A subfield 3913 may be included. When there are two shared APs, the feedback frame 3920 includes a feedback subfield 3921 for the sharing AP, a feedback subfield 3922 for the first shared AP, and a feedback for the second shared AP. A subfield 3923 may be included. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frames 3910 and 3920 may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like. The feedback frames 3910 and 3920 may include addresses of shared APs to receive the feedback frames 3910 and 3920 and address information of the sharing AP. The sharing AP and the shared APs may receive the feedback frames 3910 and 3920 based on the recipient addresses of the feedback frames 3910 and 3920. The sharing AP and the shared APs receiving the feedback frames 3910 and 3920 may acquire channel information between each STA and the shared AP and channel information between each STA and the sharing AP. In a multi-AP environment, since the sharing AP can acquire the channel state between the shared APs and the STAs within one transmission opportunity (TXOP), the influence of the channel change over time can be minimized. Therefore, it is possible to obtain an effect of performing more robust multi-AP transmission.

The shared AP may receive a feedback request frame from the sharing AP. The feedback request frame may be a feedback trigger frame described above. The feedback request frame may be a signal for the sharing AP to request a feedback frame from the shared AP.

For example, the sharing AP may transmit a feedback trigger frame (eg, a MAP feedback trigger frame) to shared APs that have association with receiving STAs. For example, the sharing AP may transmit a feedback trigger frame to a first shared AP associated with STA a and a second shared AP associated with STA b. The feedback trigger frame may be a signal for the sharing AP to request channel information with the STA from the shared APs. The feedback trigger frame may include resource (eg, RU) allocation information for the shared APs to transmit the feedback frame. The feedback trigger frame may include information related to an order in which the shared APs transmit the feedback frame. For example, the sharing AP transmits information that the first shared AP first transmits the feedback frame to the sharing AP through the feedback trigger frame, and then the second shared AP transmits information to transmit the feedback frame to the sharing AP. I can.

For example, the sharing AP to all shared APs (eg, a first shared AP, a second shared AP, a third shared AP) that transmitted a reference signal (eg, an NDP frame). A feedback trigger frame (eg, MAP reference feedback frame) may be transmitted. The feedback trigger frame may be a signal that requests the sharing AP to feed back channel information sent by STAs to the shared APs. The sharing AP may sequentially transmit the feedback trigger frame to the shared APs.

Shared APs may receive a feedback trigger frame from the sharing AP. The feedback trigger frame may include resource allocation information for the shared APs to transmit the feedback frame.

The shared AP may transmit a feedback frame to the sharing AP.

The shared AP may transmit a feedback frame to the sharing AP based on the feedback frame received from the STA. Channel information between the shared AP and the STA included in the feedback frame transmitted by the shared AP may be the same as the channel information transmitted by the STA to the shared AP. Shared APs may simultaneously transmit a feedback frame to the sharing AP in UL MU OFDMA (uplink multi-user orthogonal frequency division multiplexing access) scheme.

The shared AP may transmit a feedback frame to the sharing AP based on the feedback frame received from the STA. Channel information between the shared AP and the STA included in the feedback frame transmitted by the shared AP may be the same as the channel information transmitted by the STA to the shared AP. Shared APs may simultaneously transmit a feedback frame to the sharing AP in UL MU OFDMA (uplink multi-user orthogonal frequency division multiplexing access) scheme. When the shared APs receive the feedback trigger frame from the sharing AP, they may generate a feedback frame to be transmitted to the sharing AP using the feedback frame received from the STAs. The shared APs can transmit the generated feedback frame to the sharing AP. A feedback frame may be transmitted to the sharing AP. Shared APs may transmit a feedback frame using UL MU OFDMA (uplink multi-user orthogonal frequency division multiple access). The RU to be used for the UL MU OFDMA may be determined based on resource allocation information included in the feedback trigger frame received from the sharing AP.

29 is a diagram illustrating an example of a network composed of multiple APs. There may be two types of access points (APs) in the WLAN system. For example, there may be a master AP (M-AP) and a slave AP (S-AP). The master AP may be referred to as a sharing AP, and the slave AP may be referred to as a shared AP. Hereinafter, they are referred to as master AP and slave AP. Multi-AP transmission (Multi-AP) may refer to a method of transmitting a signal to an STA using a plurality of APs. For example, multi-AP transmission may refer to a transmission method such as distributed MIMO, C-OFDMA, coordinated beamforming, and coordinated spatial reuse. APs (eg, master AP, slave AP, etc.) may transmit and receive signals through wireless communication with each other.

The master AP may select the slave APs and a plurality of slave APs that perform multi-AP transmission. For example, slave APs 1, 2, and 3 selected by the master AP may perform signal transmission to STAs a and b.

The master AP may play a role of coordinating a plurality of APs existing in the WLAN system. For example, the master AP may play a role of initiating and controlling multi-AP transmission. For example, the master AP may group the slave APs and manage a link with the slave APs so that information can be shared between the slave APs. For example, the master AP may manage information on a BSS configured by slave APs and information on STAs associated with the corresponding BSS.

The slave AP may be coordinated by the master AP and may participate in multi-AP transmission. For example, the slave AP may establish an association with the master AP, and may share control information, management information, and data traffic with the master AP. For example, the slave AP may basically perform the same function as an AP capable of forming a BSS in an existing WLAN.

Slave APs, which are candidates for multi-AP transmission, may transmit and receive directly with the master AP. STAs as recipients of multi-AP transmission may be able to directly transmit/receive with slave APs. The master AP and STAs may not be able to directly transmit/receive to each other, but the master AP may know the existence of STAs. STAs may be associated with one of the slave APs.

As shown in FIG. 29, a channel estimation procedure in a wireless LAN system including a plurality of APs (eg, master AP, slave AP, etc.) is as follows.

30 is a diagram illustrating an embodiment of a channel estimation method for performing multi-AP transmission. The master AP of FIG. 30 may not directly transmit/receive with the STA. The communication network of FIG. 30 may be the same as the communication network of FIG. 29.

Referring to FIG. 30, STAs may estimate a channel between candidate slave APs and the STA based on signals transmitted from candidate slave APs capable of performing multi-AP transmission. STAs may transmit the estimated channel information to the slave AP. Channel information can be finally delivered to the master AP.

STAs may transmit channel estimation information with slave APs to a slave AP that has an association with the STA. That is, the STA may transmit the feedback frame only to the slave AP that has made an association with it. The STA may receive a reference signal from all slave APs and may estimate a channel between all slave APs and the STA. For example, STA a may estimate all of the channels between the first slave AP, the second slave AP, and the third slave AP and the STA a. STA a may transmit channel information between the first to third slave APs and STA a to the first slave AP associated with STA a through the feedback frame.

31 is a diagram illustrating an embodiment of a channel estimation feedback frame transmitted by an STA.

Referring to FIG. 31, a feedback frame (for example, a MAP reference feedback frame) includes feedback information between a first slave AP (S-AP 1) and an STA, and feedback information between a second slave AP (S-AP 2) and an STA. , It may include feedback information between the third slave AP (S-AP 3) and the STA. The feedback frame transmitted by STA a may include all of channel information between STA a and the first slave AP, channel information between STA a and the second slave AP, and channel information between STA a and the third slave AP.

The feedback frame may include subfields including feedback information related to each slave AP. When there are three slave APs, the feedback frame may include a feedback subfield for the first slave AP, a feedback subfield for the second slave AP, and a feedback subfield for the third slave AP. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frame may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like.

Referring back to FIG. 30, STA a may transmit a feedback frame to a first slave AP that has an association with STA a. After the first slave AP receives the feedback frame from STA a, the second slave AP may transmit a MAP poll frame to STA b associated with the second slave AP.

STA b may receive the MAP poll frame from the second slave AP. Upon receiving the MAP poll frame, the STA b may transmit a feedback frame to the second slave AP that has established an association. The order in which STAs transmit the feedback frames may be determined by the master AP. For example, the master AP may transmit a MAP trigger frame notifying the start of the channel estimation procedure to the slave APs, and the MAP trigger frame may include information related to the order in which STAs transmit the feedback frame. For example, slave APs may use a null data packet (NDP) frame as a reference signal. Slave APs may transmit a null data packet announcement (NDPA) frame to STAs before transmitting the NDP frame. The NDPA frame may include information related to an order in which STAs transmit a feedback frame. For example, information related to the order in which STAs transmit the feedback frame may be included in the STA information subfield of the NDPA frame.

The STA can receive the NDPA frame and know the order of transmitting the feedback frame. After that, the STA may receive the NDP frame and estimate the channel. The STA may transmit a feedback frame including channel information based on an order of transmitting the feedback frame.

The power used by the AP for transmission and the power used by the STA for transmission may be different from each other. For example, the power used by the AP for transmission may be greater than the power used by the STA for transmission. Therefore, when the slave AP and the STA are far apart, the STA may receive a signal transmitted by the slave AP, but the slave AP may not receive a signal transmitted by the STA. Accordingly, the STA may transmit the feedback frame to the slave AP that has made an association with it. For example, STA a may transmit a feedback frame to a first slave AP that has an association with STA a. Since the associated STA and the slave AP are not so far away that it is difficult to receive a signal, transmitting the feedback frame to the slave AP with which the STA has an association is the power between downlink (DL) and uplink (UL). You can get the effect of preventing power imbalance problem.

The master AP may transmit a feedback trigger frame (eg, a MAP feedback trigger frame) to slave APs that have an association with receiving STAs. For example, the master AP may transmit a feedback trigger frame to a first slave AP associated with STA a and a second slave AP associated with STA b. The feedback trigger frame may be a signal for the master AP to request channel information with the STA from the slave APs.

The feedback trigger frame may include resource (eg, RU) allocation information for slave APs to transmit the feedback frame. The feedback trigger frame may include information related to an order in which the slave APs transmit the feedback frame. For example, the master AP may transmit information indicating that the first slave AP first transmits the feedback frame to the master AP and then the second slave AP transmits the feedback frame to the master AP through the feedback trigger frame.

The slave AP may transmit a feedback frame to the master AP based on the feedback frame received from the STA. Channel information between the slave AP and the STA included in the feedback frame transmitted by the slave AP may be the same as the channel information transmitted by the STA to the slave AP. Slave APs may simultaneously transmit a feedback frame to the master AP in UL MU OFDMA (uplink multi-user orthogonal frequency division multiplexing access) scheme.

32 is a diagram illustrating an embodiment of a channel estimation method for performing multi-AP transmission. The master AP of FIG. 32 may not perform direct transmission/reception with the STA. The communication network of FIG. 32 may be the same as the communication network of FIG. 29.

Referring to FIG. 32, STAs may estimate a channel between candidate slave APs and the STA based on signals sent from candidate slave APs capable of performing multi-AP transmission. STAs may transmit the estimated channel information to the slave AP. Channel information can be finally delivered to the master AP.

The embodiment of FIG. 32 has an effect of rapidly transmitting channel estimation information in a multi-AP environment. The embodiment of FIG. 32 may be a method having the effect of reducing the time overhead most among methods of transmitting a feedback frame.

Slave APs may use a null data packet (NDP) frame as a reference signal. Slave APs may transmit NDP frames to STAs. The STA may receive the NDP frame and estimate the channel.

STAs may transmit a feedback frame (eg, MAP reference feedback frame) including channel information to slave APs that have transmitted the NDP frame.

STAs can simultaneously transmit the feedback frame. For example, STA a and STA b may be allocated different resources (e.g., RU) to transmit a feedback frame, and may be assigned to each other in the same frequency band by UL MU MIMO (uplink multi-user multiple input multiple output). Another RU can be used to simultaneously transmit the feedback frame. For example, STA a and STA b may transmit a feedback frame to all slave APs that have transmitted NDP in a multicast method.

33 is a diagram illustrating an embodiment of a feedback frame transmitted by a slave AP.

Referring to FIG. 33, a feedback frame 3310 is a feedback frame transmitted by STA a (eg, MAP reference feedback frame), and a feedback frame 3320 is a feedback frame transmitted by STA b (eg, MAP reference feedback frame). The feedback frame 3310 may include all of channel information between STA a and the first slave AP, channel information between STA a and the second slave AP, and channel information between STA a and the third slave AP. The feedback frame 3320 may include all of channel information between the STA b and the first slave AP, channel information between the STA b and the second slave AP, and channel information between the STA b and the third slave AP.

The feedback frame may include subfields including feedback information related to each slave AP. When three slave APs exist, the feedback frame 3310 includes a feedback subfield 3311 for the first slave AP, a feedback subfield 3312 for the second slave AP, and a feedback subfield for the third slave AP. (3313) may be included. When there are three slave APs, the feedback frame 3320 includes a feedback subfield 3321 for the first slave AP, a feedback subfield 3322 for the second slave AP, and a feedback subfield for the third slave AP. (3323) may be included. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frames 3310 and 3320 may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like.

The feedback frames 3310 and 3320 may include address information of slave APs that will receive the feedback frames 3310 and 3320. Slave APs may receive the feedback frames 3310 and 3320 based on the recipient addresses of the feedback frames 3310 and 3320. Slave APs receiving the feedback frames 3310 and 3320 may acquire channel information between respective STAs and the slave AP.

Referring back to FIG. 32, the master AP triggers feedback to all slave APs (eg, a first slave AP, a second slave AP, and a third slave AP) that transmitted a reference signal (eg, an NDP frame). A frame (eg, MAP reference feedback frame) may be transmitted. The feedback trigger frame may be a signal requesting the master AP to feed back channel information sent by STAs to the slave APs. The master AP may sequentially transmit the feedback trigger frame to the slave APs.

Slave APs may receive a feedback trigger frame from the master AP. The feedback trigger frame may include resource allocation information for slave APs to transmit the feedback frame.

When the slave APs receive the feedback trigger frame from the master AP, they may generate a feedback frame to be transmitted to the master AP by using the feedback frame received from the STAs. Slave APs may transmit the generated feedback frame to the master AP. A feedback frame can be transmitted to the master AP. Slave APs may transmit a feedback frame using UL MU OFDMA (uplink multi-user orthogonal frequency division multiple access). The RU to be used for the UL MU OFDMA may be determined based on resource allocation information included in the feedback trigger frame received from the master AP.

34 is a diagram illustrating an embodiment of a feedback frame transmitted from a slave AP to a master AP.

Referring to FIG. 34, a feedback frame 3410 is a feedback frame (e.g., a MAP reference feedback frame) transmitted by a first slave AP, and a feedback frame 3420 is a feedback frame (e.g., a second slave AP) transmitted. For example, MAP reference feedback frame). The feedback frame 3410 may include channel information 3412 between the first slave AP and the STA a and channel information 3412 between the first slave AP and the STA b. The feedback frame 3420 may include channel information 3421 between the second slave AP and STA a and channel information 3422 between the second slave AP and STA b. The feedback frame 3430 may include channel information 3431 between the third slave AP and the STA a and channel information 3432 between the third slave AP and the STA b.

Referring back to FIG. 32, slave APs may acquire all channel information between the STA and the first to third slave APs from the STA, but the slave APs may transmit only channel information between themselves and the STAs to the master AP. Accordingly, it is possible to obtain an effect of reducing the size of the feedback frame transmitted by the slave APs.

In a multi-AP environment, since the master AP can acquire the channel state between the slave APs and the STAs within one transmission opportunity (TXOP), the influence of the channel change over time can be minimized. Therefore, it is possible to obtain an effect of performing more robust multi-AP transmission.

35 is a diagram illustrating an example of a network composed of multiple APs.

Referring to FIG. 35, two types of access points (APs) may exist in a WLAN system. For example, there may be a master AP (M-AP) and a slave AP (S-AP). The master AP may be referred to as a sharing AP, and the slave AP may be referred to as a shared AP. Hereinafter, they are referred to as master AP and slave AP. Multi-AP transmission may refer to a method of transmitting a signal to an STA using a plurality of APs. For example, multi-AP transmission may refer to a transmission method such as distributed MIMO, C-OFDMA, coordinated beamforming, and coordinated spatial reuse. APs (eg, master AP, slave AP, etc.) may transmit and receive signals through wireless communication with each other.

The master AP may select the slave APs and a plurality of slave APs that perform multi-AP transmission. For example, the slave APs 1 and 2 selected by the master AP and the master AP may perform signal transmission to STAs a and b.

The master AP may play a role of coordinating a plurality of APs existing in the WLAN system. For example, the master AP may play a role of initiating and controlling multi-AP transmission. For example, the master AP may group the slave APs and manage a link with the slave APs so that information can be shared between the slave APs. For example, the master AP may manage information on a BSS configured by slave APs and information on STAs associated with the corresponding BSS.

The slave AP may be coordinated by the master AP and may participate in multi-AP transmission. For example, the slave AP may establish an association with the master AP, and may share control information, management information, and data traffic with the master AP. For example, the slave AP may basically perform the same function as an AP capable of forming a BSS in an existing WLAN.

Slave APs, which are candidates for multi-AP transmission, may transmit and receive directly with the master AP. STAs as recipients of multi-AP transmission may be able to directly transmit/receive with slave APs. The master AP and STAs may directly transmit and receive each other. As shown in FIG. 35, a channel estimation procedure in a wireless LAN system including a plurality of APs (eg, a master AP, a slave AP, etc.) is as follows.

36 is a diagram illustrating an embodiment of a channel estimation method for performing multi-AP transmission. The master AP of FIG. 36 may perform direct transmission/reception with the STA. The communication network of FIG. 36 may be the same as the communication network of FIG. 35.

Referring to FIG. 36, STAs may estimate a channel between candidate slave APs and the STA based on signals sent from candidate slave APs capable of performing multi-AP transmission. STAs may transmit the estimated channel information to the master AP.

STAs may transmit channel estimation information with slave APs to the master AP. The STA may receive a reference signal from all slave APs and the master AP, and may estimate a channel between all slave APs and the STA and a channel between the master AP and the STA. For example, STA a may estimate all of a first slave AP, a second slave AP, a third slave AP, and a channel between the master AP and STA a. STA a may transmit channel information between the first to third slave APs and STA a to the master AP through the feedback frame.

37 is a diagram illustrating an embodiment of a channel estimation feedback frame transmitted by an STA.

Referring to FIG. 37, a feedback frame (for example, a MAP reference feedback frame) includes feedback information between a first slave AP (S-AP 1) and an STA, and feedback information between a second slave AP (S-AP 2) and an STA. , It may include feedback information between the master AP (M-AP) and the STA. The feedback frame transmitted by STA a may include all of channel information between STA a and the first slave AP, channel information between STA a and the second slave AP, and channel information between STA a and the master AP.

The feedback frame may include subfields including feedback information related to each slave AP. When one master AP and two slave APs exist, the feedback frame may include a feedback subfield for the first slave AP, a feedback subfield for the second slave AP, and a feedback subfield for the master AP. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frame may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like.

Referring back to FIG. 36, the STA (eg, STA a) may transmit a feedback frame to the master AP. The next STA (eg, STA b) may receive the MAP poll frame from the master AP. When the next STA receives the MAP poll frame, it may transmit a feedback frame to the master AP. The order in which the STAs STA a and STA b transmit the feedback frame may be determined by the master AP. For example, the master AP may transmit a MAP trigger frame notifying the start of the channel estimation procedure to the slave APs, and the MAP trigger frame may include information related to the order in which STAs transmit the feedback frame. For example, the master AP and the slave APs may use a null data packet (NDP) frame as a reference signal. The master AP and the slave APs may transmit a null data packet announcement (NDPA) frame to STAs before transmitting the NDP frame. The NDPA frame may include information related to an order in which STAs transmit a feedback frame. For example, information related to the order in which STAs transmit the feedback frame may be included in the STA information subfield of the NDPA frame.

The STA can receive the NDPA frame and know the order of transmitting the feedback frame. After that, the STA may receive the NDP frame and estimate the channel. The STA may transmit a feedback frame including channel information based on an order of transmitting the feedback frame.

38 is a diagram illustrating an embodiment of a channel estimation method for performing multi-AP transmission. The master AP of FIG. 38 may perform direct transmission/reception with the STA. The communication network of FIG. 38 may be the same as the communication network of FIG. 35.

Referring to FIG. 38, STAs may estimate candidate slave APs and a channel between the master AP and the STA based on signals sent by the master AP and candidate slave APs capable of performing multi-AP transmission. STAs may transmit the estimated channel information to the master AP.

The embodiment of FIG. 38 has an effect of rapidly transmitting channel estimation information in a multi-AP environment. The embodiment of FIG. 38 may be a method having the effect of reducing the time overhead most among methods of transmitting a feedback frame.

Slave APs and master APs may use a null data packet (NDP) frame as a reference signal. Slave APs and master APs may transmit NDP frames to STAs. The STA may receive the NDP frame and estimate the channel.

STAs may transmit a feedback frame (eg, MAP reference feedback frame) including channel information to the master AP.

STAs can simultaneously transmit the feedback frame. For example, STA a and STA b may be allocated different resources (e.g., RU) to transmit a feedback frame, and may be assigned to each other in the same frequency band by UL MU MIMO (uplink multi-user multiple input multiple output). Another RU can be used to simultaneously transmit the feedback frame. For example, STAs may be assigned an RU for UL MU MIMO transmission from a master AP through a MAP trigger frame.

39 is a diagram illustrating an embodiment of a feedback frame transmitted by an STA.

Referring to FIG. 39, a feedback frame 3910 is a feedback frame transmitted by STA a (eg, MAP reference feedback frame), and a feedback frame 3920 is a feedback frame transmitted by STA b (eg, MAP reference feedback frame). The feedback frame 3910 may include all of channel information between the STA a and the first slave AP, channel information between the STA a and the second slave AP, and channel information between the STA a and the master AP. The feedback frame 3920 may include all of channel information between the STA b and the first slave AP, channel information between the STA b and the second slave AP, and channel information between the STA b and the master AP.

The feedback frame may include subfields including feedback information related to each slave AP and master AP. When there are two slave APs, the feedback frame 3910 includes a feedback subfield 3911 for the master AP, a feedback subfield 3912 for the first slave AP, and a feedback subfield 3913 for the second slave AP. ) Can be included. When there are two slave APs, the feedback frame 3920 includes a feedback subfield 3921 for the master AP, a feedback subfield 3922 for the first slave AP, and a feedback subfield 3923 for the second slave AP. ) Can be included. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frames 3910 and 3920 may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like.

The feedback frames 3910 and 3920 may include addresses of slave APs to receive the feedback frames 3910 and 3920 and address information of the master AP. The master AP and the slave APs may receive the feedback frames 3910 and 3920 based on the recipient address of the feedback frames 3910 and 3920. Upon receiving the feedback frames 3910 and 3920, the master AP and the slave APs may acquire channel information between each STA and the slave AP and channel information between each STA and the master AP.

In a multi-AP environment, since the master AP can acquire the channel state between the slave APs and the STAs within one transmission opportunity (TXOP), the influence of the channel change over time can be minimized. Therefore, it is possible to obtain an effect of performing more robust multi-AP transmission.

40 is a flowchart illustrating an embodiment of a sharing access point (AP) operation.

Referring to FIG. 40, a sharing AP (eg, a master AP) may transmit a multi-AP (MAP) trigger frame (S4010). The sharing AP may transmit a MAP trigger frame indicating the start of the channel estimation procedure to the shared APs in order to start the channel estimation procedure between the shared APs and the receiving STAs.

For example, the sharing AP may transmit a MAP trigger frame notifying the start of a channel estimation procedure to the shared APs, and the MAP trigger frame may include information related to an order in which STAs transmit a feedback frame. For example, shared APs may use a null data packet (NDP) frame as a reference signal. Shared APs may transmit a null data packet announcement (NDPA) frame to STAs before transmitting the NDP frame. The NDPA frame may include information related to an order in which STAs transmit a feedback frame. For example, information related to the order in which STAs transmit the feedback frame may be included in the STA information subfield of the NDPA frame.

The sharing AP may transmit a feedback trigger frame (S4020). For example, the sharing AP may transmit a feedback trigger frame (eg, a MAP feedback trigger frame) to shared APs that have association with receiving STAs. For example, the sharing AP may transmit a feedback trigger frame to a first shared AP associated with STA a and a second shared AP associated with STA b. The feedback trigger frame may be a signal for the sharing AP to request channel information with the STA from the shared APs.

For example, the sharing AP to all shared APs (eg, a first shared AP, a second shared AP, a third shared AP) that transmitted a reference signal (eg, an NDP frame). A feedback trigger frame (eg, MAP reference feedback frame) may be transmitted. The feedback trigger frame may be a signal that requests the sharing AP to feed back channel information sent by STAs to the shared APs. The sharing AP may sequentially transmit the feedback trigger frame to the shared APs.

The feedback trigger frame may include resource (eg, RU) allocation information for the shared APs to transmit the feedback frame. The feedback trigger frame may include information related to an order in which the shared APs transmit the feedback frame. For example, the sharing AP transmits information that the first shared AP first transmits the feedback frame to the sharing AP through the feedback trigger frame, and then the second shared AP transmits information to transmit the feedback frame to the sharing AP. I can.

The sharing AP may receive feedback frames from the shared APs (S4030).

Referring to FIG. 33, a feedback frame 3310 is a feedback frame transmitted by STA a (eg, MAP reference feedback frame), and a feedback frame 3320 is a feedback frame transmitted by STA b (eg, MAP reference feedback frame). The feedback frame 3310 may include all of channel information between STA a and the first shared AP, channel information between STA a and the second shared AP, and channel information between STA a and the third shared AP. The feedback frame 3320 may include all channel information between STA b and the first shared AP, channel information between STA b and the second shared AP, and channel information between STA b and the third shared AP.

The feedback frame may include subfields including feedback information related to each shared AP. If there are three shared APs, the feedback frame 3310 is in the feedback subfield 3311 for the first shared AP, the feedback subfield 3312 for the second shared AP, and the third shared AP. A feedback subfield 3313 for may be included. When there are three shared APs, the feedback frame 3320 is in the feedback subfield 3321 for the first shared AP, the feedback subfield 3322 for the second shared AP, and the third shared AP. A feedback subfield 3323 for may be included. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frames 3310 and 3320 may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like.

The feedback frames 3310 and 3320 may include address information of shared APs that will receive the feedback frames 3310 and 3320. The shared APs may receive the feedback frames 3310 and 3320 based on the recipient addresses of the feedback frames 3310 and 3320. The shared APs receiving the feedback frames 3310 and 3320 may acquire channel information between each STA and the shared AP.

Alternatively, the sharing AP may receive feedback frames from STAs (S4030). When the sharing AP can directly transmit/receive with STAs, the feedback trigger frame transmission (S4020) may not be performed, and the sharing AP may directly receive the feedback frames from the STAs (S4030).

Referring to FIG. 39, a feedback frame 3910 is a feedback frame transmitted by STA a (eg, MAP reference feedback frame), and a feedback frame 3920 is a feedback frame transmitted by STA b (eg, MAP reference feedback frame). The feedback frame 3910 may include all of channel information between STA a and the first shared AP, channel information between STA a and the second shared AP, and channel information between STA a and the sharing AP. The feedback frame 3920 may include all of channel information between STA b and the first shared AP, channel information between STA b and the second shared AP, and channel information between STA b and the sharing AP.

The feedback frame may include subfields including feedback information related to each shared AP and the sharing AP. When there are two shared APs, the feedback frame 3910 includes a feedback subfield 3911 for the sharing AP, a feedback subfield 3912 for the first shared AP, and a feedback for the second shared AP. A subfield 3913 may be included. When there are two shared APs, the feedback frame 3920 includes a feedback subfield 3921 for the sharing AP, a feedback subfield 3922 for the first shared AP, and a feedback for the second shared AP. A subfield 3923 may be included. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frames 3910 and 3920 may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like.

The feedback frames 3910 and 3920 may include addresses of shared APs to receive the feedback frames 3910 and 3920 and address information of the sharing AP. The sharing AP and the shared APs may receive the feedback frames 3910 and 3920 based on the recipient addresses of the feedback frames 3910 and 3920. The sharing AP and the shared APs receiving the feedback frames 3910 and 3920 may acquire channel information between each STA and the shared AP and channel information between each STA and the sharing AP.

In a multi-AP environment, since the sharing AP can acquire the channel state between the shared APs and the STAs within one transmission opportunity (TXOP), the influence of the channel change over time can be minimized. Therefore, it is possible to obtain an effect of performing more robust multi-AP transmission.

41 is a flowchart illustrating an embodiment of a shared access point (AP) operation.

Referring to FIG. 41, a shared AP (eg, a slave AP) may receive a feedback frame from an STA (S4110).

Referring to FIG. 31, a feedback frame (for example, a MAP reference feedback frame) includes feedback information between a first shared AP (S-AP 1) and an STA, and between a second shared AP (S-AP 2) and the STA. Feedback information and feedback information between the third shared AP (S-AP 3) and the STA may be included. The feedback frame transmitted by STA a may include all of channel information between STA a and the first shared AP, channel information between STA a and the second shared AP, and channel information between STA a and the third shared AP. . The feedback frame may include subfields including feedback information related to each shared AP. When there are three shared APs, the feedback frame may include a feedback subfield for the first shared AP, a feedback subfield for the second shared AP, and a feedback subfield for the third shared AP. . The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frame may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like. STA a may transmit a feedback frame to the first shared AP that has made an association with STA a. After the first shared AP receives the feedback frame from STA a, the second shared AP may transmit the MAP poll frame to the STA b associated with the second shared AP. STA b may receive the MAP poll frame from the second shared AP. When STA b receives the MAP poll frame, it may transmit a feedback frame to the second shared AP that has established an association. The order in which STAs transmit feedback frames may be determined by the sharing AP. For example, the sharing AP may transmit a MAP trigger frame notifying the start of a channel estimation procedure to the shared APs, and the MAP trigger frame may include information related to an order in which STAs transmit a feedback frame. For example, shared APs may use a null data packet (NDP) frame as a reference signal. Shared APs may transmit a null data packet announcement (NDPA) frame to STAs before transmitting the NDP frame. The NDPA frame may include information related to an order in which STAs transmit a feedback frame. For example, information related to the order in which STAs transmit the feedback frame may be included in the STA information subfield of the NDPA frame. The STA can receive the NDPA frame and know the order of transmitting the feedback frame. After that, the STA may receive the NDP frame and estimate the channel. The STA may transmit a feedback frame including channel information based on an order of transmitting the feedback frame.

Referring to FIG. 37, a feedback frame (eg, a MAP reference feedback frame) includes feedback information between a first shared AP (S-AP 1) and an STA, and between a second shared AP (S-AP 2) and the STA. Feedback information and feedback information between the sharing AP (M-AP) and the STA may be included. The feedback frame transmitted by STA a may include channel information between STA a and the first shared AP, channel information between STA a and the second shared AP, and channel information between STA a and the sharing AP. The feedback frame may include subfields including feedback information related to each shared AP. When one sharing AP and two shared APs exist, the feedback frame includes a feedback subfield for the first shared AP, a feedback subfield for the second shared AP, and a feedback subfield for the sharing AP. Can include. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frame may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like. The STA (eg, STA a) may transmit a feedback frame to the sharing AP. The next STA (eg, STA b) may receive the MAP poll frame from the sharing AP. When the next STA receives the MAP poll frame, it may transmit a feedback frame to the sharing AP. The order in which the STAs (STA a, STA b) transmit the feedback frame may be determined by the sharing AP. For example, the sharing AP may transmit a MAP trigger frame notifying the start of a channel estimation procedure to the shared APs, and the MAP trigger frame may include information related to an order in which STAs transmit a feedback frame. For example, the sharing AP and the shared AP may use a null data packet (NDP) frame as a reference signal. The sharing AP and the shared AP may transmit a null data packet announcement (NDPA) frame to STAs before transmitting the NDP frame. The NDPA frame may include information related to an order in which STAs transmit a feedback frame. For example, information related to the order in which STAs transmit the feedback frame may be included in the STA information subfield of the NDPA frame. The STA can receive the NDPA frame and know the order of transmitting the feedback frame. After that, the STA may receive the NDP frame and estimate the channel. The STA may transmit a feedback frame including channel information based on an order of transmitting the feedback frame.

Referring to FIG. 39, a feedback frame 3910 is a feedback frame transmitted by STA a (eg, MAP reference feedback frame), and a feedback frame 3920 is a feedback frame transmitted by STA b (eg, MAP reference feedback frame). The feedback frame 3910 may include all of channel information between STA a and the first shared AP, channel information between STA a and the second shared AP, and channel information between STA a and the sharing AP. The feedback frame 3920 may include all of channel information between STA b and the first shared AP, channel information between STA b and the second shared AP, and channel information between STA b and the sharing AP. The feedback frame may include subfields including feedback information related to each shared AP and the sharing AP. When there are two shared APs, the feedback frame 3910 includes a feedback subfield 3911 for the sharing AP, a feedback subfield 3912 for the first shared AP, and a feedback for the second shared AP. A subfield 3913 may be included. When there are two shared APs, the feedback frame 3920 includes a feedback subfield 3921 for the sharing AP, a feedback subfield 3922 for the first shared AP, and a feedback for the second shared AP. A subfield 3923 may be included. The content of each feedback subfield may vary according to a multi-AP transmission scheme (eg, distributed MIMO, C-OFDMA, coordinated beamforming, coordinated spatial reuse, etc.). For example, the feedback frames 3910 and 3920 may include a channel state information (CSI) value for each stream, a clear channel assessment (CCA) result for each resource unit (RU), a CCA result for each channel, and the like. The feedback frames 3910 and 3920 may include addresses of shared APs to receive the feedback frames 3910 and 3920 and address information of the sharing AP. The sharing AP and the shared APs may receive the feedback frames 3910 and 3920 based on the recipient addresses of the feedback frames 3910 and 3920. The sharing AP and the shared APs receiving the feedback frames 3910 and 3920 may acquire channel information between each STA and the shared AP and channel information between each STA and the sharing AP. In a multi-AP environment, since the sharing AP can acquire the channel state between the shared APs and the STAs within one transmission opportunity (TXOP), the influence of the channel change over time can be minimized. Therefore, it is possible to obtain an effect of performing more robust multi-AP transmission.

The shared AP may receive a feedback request frame from the sharing AP (S4120).

The feedback request frame may be a feedback trigger frame described above. The feedback request frame may be a signal for the sharing AP to request a feedback frame from the shared AP.

For example, the sharing AP may transmit a feedback trigger frame (eg, a MAP feedback trigger frame) to shared APs that have association with receiving STAs. For example, the sharing AP may transmit a feedback trigger frame to a first shared AP associated with STA a and a second shared AP associated with STA b. The feedback trigger frame may be a signal for the sharing AP to request channel information with the STA from the shared APs. The feedback trigger frame may include resource (eg, RU) allocation information for the shared APs to transmit the feedback frame. The feedback trigger frame may include information related to an order in which the shared APs transmit the feedback frame. For example, the sharing AP transmits information that the first shared AP first transmits the feedback frame to the sharing AP through the feedback trigger frame, and then the second shared AP transmits information to transmit the feedback frame to the sharing AP. I can.

For example, the sharing AP to all shared APs (eg, a first shared AP, a second shared AP, a third shared AP) that transmitted a reference signal (eg, an NDP frame). A feedback trigger frame (eg, MAP reference feedback frame) may be transmitted. The feedback trigger frame may be a signal that requests the sharing AP to feed back channel information sent by STAs to the shared APs. The sharing AP may sequentially transmit the feedback trigger frame to the shared APs.

Shared APs may receive a feedback trigger frame from the sharing AP. The feedback trigger frame may include resource allocation information for the shared APs to transmit the feedback frame.

The shared AP may transmit a feedback frame to the sharing AP (S4130).

The shared AP may transmit a feedback frame to the sharing AP based on the feedback frame received from the STA. Channel information between the shared AP and the STA included in the feedback frame transmitted by the shared AP may be the same as the channel information transmitted by the STA to the shared AP. Shared APs may simultaneously transmit a feedback frame to the sharing AP in UL MU OFDMA (uplink multi-user orthogonal frequency division multiplexing access) scheme.

The shared AP may transmit a feedback frame to the sharing AP based on the feedback frame received from the STA. Channel information between the shared AP and the STA included in the feedback frame transmitted by the shared AP may be the same as the channel information transmitted by the STA to the shared AP. Shared APs may simultaneously transmit a feedback frame to the sharing AP in UL MU OFDMA (uplink multi-user orthogonal frequency division multiplexing access) scheme. When the shared APs receive the feedback trigger frame from the sharing AP, they may generate a feedback frame to be transmitted to the sharing AP using the feedback frame received from the STAs. The shared APs can transmit the generated feedback frame to the sharing AP. A feedback frame may be transmitted to the sharing AP. Shared APs may transmit a feedback frame using UL MU OFDMA (uplink multi-user orthogonal frequency division multiple access). The RU to be used for the UL MU OFDMA may be determined based on resource allocation information included in the feedback trigger frame received from the sharing AP.

42 is a flowchart illustrating an embodiment of a receiving STA (eg, non-AP STA) operation.

Referring to FIG. 42, a receiving STA may receive a reference signal from a shared AP (S4210). The STA may receive a reference signal from all the shared APs and may estimate a channel between all the shared APs and the STA. For example, shared APs may use a null data packet (NDP) frame as a reference signal.

The STA may transmit a feedback frame (S4220).

For example, STAs may transmit channel estimation information with shared APs to a shared AP that has an association with the STA. That is, the STA can transmit the feedback frame only to the shared AP that has an association with itself. The STA may receive a reference signal from all the shared APs and may estimate a channel between all the shared APs and the STA. For example, STA a may estimate all of the channels between the first shared AP, the second shared AP, and the third shared AP and the STA a. The STA a may transmit channel information between the first to third shared APs and STA a to the first shared AP associated with STA a through the feedback frame. For example, shared APs may use a null data packet (NDP) frame as a reference signal. Shared APs may transmit a null data packet announcement (NDPA) frame to STAs before transmitting the NDP frame. The NDPA frame may include information related to an order in which STAs transmit a feedback frame. For example, information related to the order in which STAs transmit the feedback frame may be included in the STA information subfield of the NDPA frame. The STA can receive the NDPA frame and know the order of transmitting the feedback frame. After that, the STA may receive the NDP frame and estimate the channel. The STA may transmit a feedback frame including channel information based on an order of transmitting the feedback frame.

For example, STAs may transmit a feedback frame (eg, MAP reference feedback frame) including channel information to shared APs that have transmitted the NDP frame. STAs can simultaneously transmit the feedback frame. For example, STA a and STA b may be allocated different resources (e.g., RU) to transmit a feedback frame, and may be assigned to each other in the same frequency band by UL MU MIMO (uplink multi-user multiple input multiple output). Another RU can be used to simultaneously transmit the feedback frame. For example, STA a and STA b may transmit a feedback frame to all shared APs that have transmitted NDP in a multicast manner.

Some of the detailed steps shown in the example of FIGS. 40 to 42 may be omitted, and other steps may be added. For example, the steps of transmitting the MAP trigger frame (S4010) and/or the feedback trigger frame (S4030) in FIG. 40 may be omitted.

The technical features of the present specification described above can be applied to various devices and methods. For example, the technical features of the present specification described above may be performed/supported through the apparatus of FIGS. 1 and/or 19. For example, the technical features of the present specification described above may be applied only to a part of FIGS. 1 and/or 19. For example, the technical features of the present specification described above may be implemented based on the processing chips 114 and 124 of FIG. 1, or implemented based on the processors 111 and 121 and the memories 112 and 122 of FIG. 1. , May be implemented based on the processor 610 and the memory 620 of FIG. 19. For example, the apparatus of the present specification includes a memory and a processor operably coupled to the memory, wherein the processor receives a first feedback frame from a first station and receives a first feedback frame from a second STA. Receive a second feedback frame, wherein the first feedback frame includes channel information between the first STA and the first to third shared APs, and the second feedback frame includes the second STA and the first to third APs. 3 Including channel information between shared APs, receiving a feedback request frame from a sharing AP, and transmitting a third feedback frame to the sharing AP based on the first and second feedback frames, The third feedback frame may be configured to be transmitted in an UL-MU MIMO (uplink multi-user multiple input multiple output) method.

Technical features of the present specification may be implemented based on a computer readable medium (CRM). For example, the CRM proposed by the present specification is an instruction based on being executed by at least one processor of a shared AP (Access Point) of a wireless local area network (LAN) system ( instruction), comprising: receiving a first feedback frame from a first STA (station), and receiving a second feedback frame from a second STA, The first feedback frame includes channel information between the first STA and the first to third shared APs, and the second feedback frame includes channel information between the second STA and the first to third shared APs. Including, receiving a feedback request frame from a sharing AP, and transmitting a third feedback frame to the sharing AP based on the first and second feedback frames, the third feedback frame May store instructions for performing an operation including a step, which is transmitted in an UL-MU MIMO (uplink multi-user multiple input multiple output) method. Instructions stored in the CRM of the present specification may be executed by at least one processor. At least one processor related to the CRM of the present specification may be the processors 111 and 121 or the processing chips 114 and 124 of FIG. 1, or the processor 610 of FIG. 19. Meanwhile, the CRM of the present specification may be the memories 112 and 122 of FIG. 1, the memory 620 of FIG. 19, or a separate external memory/storage medium/disk.

The technical features of the present specification described above can be applied to various applications 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 researching artificial intelligence or the methodology to create it, and machine learning (Machine Learning) refers to the field of researching methodologies to define and solve various problems dealt with in the field of artificial intelligence. do. Machine learning is also defined as an algorithm that improves the performance of a task through continuous experience.

An artificial neural network (ANN) is a model used in machine learning, and may refer to an overall model with problem-solving capability, which is composed of artificial neurons (nodes) that form a network by combining synapses. The artificial neural network may be defined by a connection pattern between neurons of different layers, a learning process for updating model parameters, and an activation function for generating an output value.

The artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer includes one or more neurons, and the artificial neural network may include neurons and synapses connecting neurons. In an artificial neural network, each neuron can output a function of an activation function for input signals, weights, and biases input through synapses.

Model parameters refer to parameters determined through learning, and include weights of synaptic connections and biases of neurons. In addition, hyperparameters refer to parameters that must be set before learning in a machine learning algorithm, and include a learning rate, iteration count, mini-batch size, and initialization function.

The purpose of learning artificial neural networks 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 the 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 when a label for training data is given, and a label indicates the correct answer (or result value) that the artificial neural network must infer when training data is input to the artificial neural network. It can mean. Unsupervised learning may refer to a method of training an artificial neural network in a state where a label for training data is not given. Reinforcement learning may mean a learning method in which an agent defined in a certain environment learns to select an action or action sequence that maximizes the cumulative reward in each state.

Among artificial neural networks, machine learning implemented as a deep neural network (DNN) including a plurality of hidden layers is sometimes referred to as deep learning (deep learning), and deep learning is a part of machine learning. Hereinafter, machine learning is used in the sense including deep learning.

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

A robot may refer to a machine that automatically processes or operates a task given by its own capabilities. In particular, a robot having a function of recognizing the environment and performing an operation by self-determining may be referred to as an intelligent robot.

Robots can be classified into industrial, medical, household, military, etc. depending on 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, and can travel on the ground or fly in the air through the driving unit.

In addition, the above-described technical features may be applied to a device supporting extended reality.

The extended reality collectively refers to Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR). VR technology provides only CG images of real world objects or backgrounds, AR technology provides virtually created CG images on top of real object images, and MR technology is a computer that mixes and combines virtual objects in the real world. It is a graphic technology.

MR technology is similar to AR technology in that it shows real and virtual objects together. However, in AR technology, virtual objects are used in a form that complements real objects, whereas in MR technology, virtual objects and real objects are used with equal characteristics.

XR technology can be applied to HMD (Head-Mount Display), HUD (Head-Up Display), mobile phones, tablet PCs, laptops, desktops, TVs, digital signage, etc., and devices applied with XR technology are XR devices. It can be called as.

The claims set forth herein may be combined in a variety of ways. For example, the technical features of the method claims of the present specification may be combined to be implemented as a device, and the technical features of the device claims of the present specification may be combined to be implemented by a method. In addition, the technical characteristics of the method claim of the present specification and the technical characteristics of the device claim may be combined to be implemented as a device, and the technical characteristics of the method claim of the present specification and the technical characteristics of the device claim may be combined to be implemented by a method.

Claims (16)

1. In a method performed in a wireless local area network (LAN) system,

   A first shared AP (Access Point) receives a first feedback frame from a first STA (station) and a second feedback frame from a second STA, wherein the first feedback frame is the first Including channel information between the STA and the first to third shared APs, and the second feedback frame including channel information between the second STA and the first to third shared APs;

   Receiving, by the first shared AP, a feedback request frame from a sharing AP; And

   The first shared AP transmits a third feedback frame to the sharing AP based on the first and second feedback frames, and the third feedback frame is UL-MU uplink multi-user multiple input multiple (MIMO). output) method, including steps,

   Way.
2. The method according to claim 1,

   The first STA is associated with the first shared AP, and the second STA is associated with the second shared AP,

   Way.
3. The method according to claim 1,

   The third feedback frame includes channel information between the first shared AP and the first STA and channel information between the first shared AP and the second STA,

   Way.
4. The method according to claim 1,

   The first shared AP receives the first and second frames in a UL MU MIMO scheme,

   Way.
5. The method according to claim 1,

   Receiving, by the first shared AP, resource allocation information for transmission of the first feedback frame and resource allocation information for transmission of the second feedback frame from the sharing AP; And

   The first shared AP, transmitting resource allocation information for transmitting the first feedback frame to the first STA, and transmitting resource allocation information for transmitting the second feedback frame to the second STA. Included,

   Way.
6. The method according to claim 1,

   The third feedback frame includes information related to at least one of channel state information (CSI) for each stream, clear channel assessment (CCA) result for each resource unit (RU), and CCA result for each channel,

   Way.
7. In a shared (shared) AP (Access Point) used in a wireless local area network (LAN) system, the shared AP,

   A transceiver for transmitting and receiving a radio signal; And

   Including a processor connected to the transceiver, wherein the processor,

   A first feedback frame is received from a first STA (station), and a second feedback frame is received from a second STA, wherein the first feedback frame includes channel information between the first STA and the first to third shared APs. And the second feedback frame includes channel information between the second STA and the first to third shared APs;

   Receive a feedback request frame from a sharing AP; And

   A third feedback frame is transmitted to the sharing AP based on the first and second feedback frames, wherein the third feedback frame is configured to be transmitted in an UL-MU MIMO (uplink multi-user multiple input multiple output) method,

   Shared AP.
8. The method of claim 7,

   The first STA is associated with the first shared AP, and the second STA is associated with the second shared AP,

   Shared AP.
9. The method of claim 7,

   The third feedback frame includes channel information between the first shared AP and the first STA and channel information between the first shared AP and the second STA,

   Shared AP.
10. The method of claim 7,

    The first shared AP receives the first and second frames in a UL MU MIMO scheme,

    Shared AP.
11. The method of claim 7,

    Receiving, by the first shared AP, resource allocation information for transmitting the first feedback frame and resource allocation information for transmitting the second feedback frame from the sharing AP; And

    The first shared AP, transmitting resource allocation information for transmitting the first feedback frame to the first STA, and transmitting resource allocation information for transmitting the second feedback frame to the second STA. Included,

    Shared AP.
12. The method of claim 7,

    The third feedback frame includes information related to at least one of channel state information (CSI) for each stream, clear channel assessment (CCA) result for each resource unit (RU), and CCA result for each channel,

    Shared AP.
13. In a method performed in a wireless local area network (LAN) system,

    Receiving, by an STA (station), first to third reference signals from the first to third shared APs, respectively; And

    The STA transmits a feedback frame to the first shared AP, wherein the feedback frame includes channel information between the first to third shared APs and the STA, and the feedback frame is UL-MU MIMO (uplink Transmitted in a multi-user multiple input multiple output) manner, comprising the steps of,

    Way.
14. In the STA (station) used in a wireless local area network (LAN) system, the STA,

    A transceiver for transmitting and receiving a radio signal; And

    Including a processor connected to the transceiver, wherein the processor,

    Receiving first to third reference signals from the first to third shared APs, respectively; And

    A feedback frame is transmitted to the first shared AP, wherein the feedback frame includes channel information between the first to third shared APs and the STA, and the feedback frame is UL-MU uplink multi-user multiple (MIMO) input multiple output),

    STA.
15. Readable with at least one computer including instructions based on execution by at least one processor of a shared access point (AP) of a wireless local area network (LAN) system. In a computer readable medium,

    A first feedback frame is received from a first STA (station), and a second feedback frame is received from a second STA, wherein the first feedback frame includes channel information between the first STA and the first to third shared APs. Wherein the second feedback frame includes channel information between the second STA and the first to third shared APs;

    Receiving a feedback request frame from a sharing AP; And

    Transmitting a third feedback frame based on the first and second feedback frames to the sharing AP, wherein the third feedback frame is transmitted in an UL-MU MIMO (uplink multi-user multiple input multiple output) method. To perform an operation including,

    Device.
16. In a device on a wireless local area network (LAN) system,

    Memory; And

    A processor operatively coupled to the memory, wherein the processor:

    A first feedback frame is received from a first STA (station), and a second feedback frame is received from a second STA, wherein the first feedback frame includes channel information between the first STA and the first to third shared APs. And the second feedback frame includes channel information between the second STA and the first to third shared APs;

    Receive a feedback request frame from a sharing AP; And

    A third feedback frame is transmitted to the sharing AP based on the first and second feedback frames, wherein the third feedback frame is configured to be transmitted in an UL-MU MIMO (uplink multi-user multiple input multiple output) method,

    Device.

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