WO2020091412A1

WO2020091412A1 - Method and device for performing joint transmission in wireless lan system

Info

Publication number: WO2020091412A1
Application number: PCT/KR2019/014454
Authority: WO
Inventors: 박성진; 김정기; 박은성; 최진수
Original assignee: 엘지전자 주식회사
Priority date: 2018-10-30
Filing date: 2019-10-30
Publication date: 2020-05-07

Abstract

Proposed are a method and a device for performing joint transmission in a wireless LAN system. Specifically, an M-AP selects first to third S-APs which are to participate in joint transmission. The M-AP manages a link with the first to third S-APs to share first information between the first to third S-APs. The M-AP performs joint transmission to an STA through the first to third S-APs on the basis of the first information.

Description

Method and apparatus for performing joint transmission in wireless LAN system

The present specification relates to a technique for performing joint transmission in a wireless LAN system, and more specifically, a method and apparatus for performing joint transmission by selecting an S-AP and performing a sounding procedure by an M-AP in a wireless LAN system It is about.

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

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

In the new WLAN standard, an increased number of spatial streams can be used. In this case, in order to properly use the increased number of spatial streams, the signaling technique in the WLAN system may need to be improved.

This specification proposes a method and apparatus for performing joint transmission in a wireless LAN system.

An example of the present specification proposes a method for performing joint transmission.

This embodiment can be performed in a network environment in which a next generation wireless LAN system is supported. The next-generation wireless LAN system is a wireless LAN system (EHT or 802.11be) that improves the 802.11ax system and may satisfy backward compatibility with the 802.11ax system.

This embodiment is performed by a transmitting STA, and the transmitting STA may correspond to an M-AP. The receiving STA of this embodiment is an STA supporting an EHT (Extremely High Throughput) WLAN system, and is received by the first S-AP, second S-AP, or third S-AP through a joint transmission to a STA that receives data. You can respond.

The master-access point (M-AP) selects first to third slave-access points (S-APs) to participate in the joint transmission.

The M-AP manages a link with the first to third S-APs to share the first information between the first to third S-APs.

The M-AP performs the joint transmission to a STA (station) through the first to third S-APs based on the first information.

According to the embodiment proposed in the present specification, an S-AP suitable for joint transmission is selected by performing a sounding procedure according to a multi-AP coordination scheme, preventing interference from an OBSS STA or an unintended STA, and efficiently performing joint transmission. Can be done with

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

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

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

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

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

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

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

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

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

10 shows the operation according to UL-MU.

11 shows an example of a trigger frame.

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

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

14 describes the technical features of the UORA technique.

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

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

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

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

19 shows an example of activating joint multi-AP transmission.

20 is a diagram illustrating multiple AP adjustment.

21 shows an example of a null steering operation for avoiding interference.

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

23 shows interference nulling and distributed joint beamforming.

24 shows an example of adjusted beamforming.

25 is a view for explaining C-OFDMA.

26 shows an example of the joint transmission.

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

28 shows an example of a network composed of multiple APs.

29 shows an example of joint transmission when direct transmission / reception between M-AP and STA is possible.

30 shows an example of joint transmission when direct transmission / reception is not possible between the M-AP and the STA.

31 is a flowchart illustrating a procedure for performing joint transmission in a transmitting STA according to the present embodiment.

32 is a flowchart illustrating a procedure for receiving data through joint transmission in a receiving STA according to the present embodiment.

33 shows a more detailed wireless device implementing an embodiment of the present invention.

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

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

The following example of the present specification can be applied to various wireless communication systems. For example, the following example of the present specification may be applied to a wireless local area network (WLAN) system. For example, this specification may be applied to the IEEE 802.11a / g / n / ac standard, or the IEEE 802.11ax standard. In addition, the present specification can be applied to the newly proposed EHT standard or IEEE 802.11be standard. Also, an example of the present specification may be applied to a new wireless LAN standard that improves the EHT standard or IEEE 802.11be.

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

The example of FIG. 1 can perform various technical features described below. 1 includes two stations (STA). STA (110, 120) is a mobile terminal (mobile terminal), a wireless device (wireless device), a wireless transmit / receive unit (WTRU), user equipment (User Equipment; UE), mobile station (Mobile Station; MS) , It can also be called various names such as a mobile subscriber unit or simply a user. Further, the

STAs

110 and 120 may be called various names such as a receiving device, a transmitting device, a receiving STA, a transmitting STA, a receiving device, and a transmitting device.

The

STAs

110 and 120 may perform an access point (AP) role or a non-AP role. That is, the

STAs

110 and 120 of the present specification may perform functions of an AP and / or a non-AP.

The

STAs

110 and 120 of the present specification may support various communication standards other than the IEEE 802.11 standard. For example, it may support a communication standard (eg, LTE, LTE-A, 5G NR standard) according to the 3GPP standard. Also, the STA of the present specification may be implemented with various devices such as a mobile phone, a vehicle, and a personal computer.

In this specification, the

STAs

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

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

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

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

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

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

For example, the operation of the device indicated as the AP in the following specification may be performed in the first STA 110. Specifically, the operation of the device indicated by the AP is controlled by the processor 111 of the first STA 110, and a related signal is transmitted or received through the transceiver 113 controlled by the processor 111 of the first STA 110. Can be. In addition, control information related to the operation of the AP or the transmission / reception signal of the AP may be stored in the memory 112 of the first STA 110.

For example, the operation of the device indicated as non-AP (or User-STA) in the following specification may be performed in the second STA 120. Specifically, the operation of the device marked as non-AP is controlled by the processor 121 of the second STA 120, and a related signal is transmitted through the transceiver 123 controlled by the processor 121 of the second STA 120. Or it can be received. In addition, control information related to the operation of the non-AP or an AP transmission / reception signal may be stored in the memory 212 of the second STA 120.

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

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

Referring to the top of FIG. 2, the wireless LAN system may include one or more infrastructure BSSs 200 and 205 (hereinafter, BSS). The

BSSs

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

The BSS may include at least one STA,

APs

225 and 230 providing a distributed service, and a distributed system (DS, 210) connecting multiple APs.

The distributed system 210 may connect

multiple BSSs

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

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

In the BSS such as the top of FIG. 2, a network between

APs

225 and 230 and a network between

APs

225 and 230 and STAs 200-1, 205-1 and 205-2 may be implemented. However, it may be possible to establish a network between STAs without

APs

225 and 230 to perform communication. A network that establishes a network even among STAs without

APs

225 and 230 to perform communication is defined as an ad-hoc network or an independent basic service set (BSS).

2 is a conceptual diagram showing IBSS.

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

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

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

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

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

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

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

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

The successfully authenticated STA may perform a connection process based on step S330. The connection process includes a process in which the STA transmits an association request frame to the AP, and in response, the AP transmits an association response frame to the STA. For example, the connection request frame includes information related to various capabilities, beacon listening interval, service set identifier (SSID), supported rates, supported channels, RSN, and mobility domain. , Supported operating classes, TIM broadcast request, and information on interworking service capabilities. For example, the connection response frame includes information related to various capabilities, status codes, association ID (AID), support rate, enhanced distributed channel access (EDCA) parameter set, received channel power indicator (RCPI), and received signal to noise (RSNI). Indicator), mobility domain, timeout interval (association comeback time (association comeback time)), overlapping (overlapping) BSS scan parameters, TIM broadcast response, QoS map, and the like information 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 private key setup through 4-way handshaking through an Extensible Authentication Protocol over LAN (EAPOL) frame. .

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

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

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

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

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

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

As shown at the top of Fig. 5, 26-units (i.e., units corresponding to 26 tones) can be arranged. Six tones may be used as a guard band in the leftmost band of the 20 MHz band, and five tones may be used as a guard band in the rightmost band of the 20 MHz band. In addition, 7 DC tones are inserted into the central band, that is, the DC band, and 26-units corresponding to each of 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, ie a user.

Meanwhile, the RU arrangement of FIG. 5 is utilized not only for a situation for multiple users (MU), but also for a situation for single users (SU). In this case, as shown in the bottom of FIG. 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, various sizes of RUs, that is, 26-RU, 52-RU, 106-RU, 242-RU, and the like are proposed. Since the specific size of these RUs can be expanded or increased, this embodiment Is not limited to the specific size of each RU (ie the number of corresponding tones).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

An example of Table 1 shows only a part of RU locations that can be displayed by RU allocation information. For example, the RU allocation information may further include an example of Table 2 below.

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

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

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

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

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

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

The user fields illustrated in FIGS. 8 and 9 may be configured based on two formats. That is, the User field related to the MU-MIMO technique may be configured in the first format, and the User field related to the non-MU-MIMO technique may be configured in the second format. Referring to the example of FIG. 9, User fields 1 to User field 3 may be based on the first format, and User fields 4 to User Field 8 may be based on the second format.

The first format or the second format may include bit information of the same length (for example, 21 bits).

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

TB PPDUs

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The user identifier (User Identifier) field 1310 of FIG. 13 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.

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

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

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

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

14 describes the technical features of the UORA technique.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

1. One. CSMACSMA /CA(carrier sense multiple access/collision avoidance)/ CA (carrier sense multiple access / collision avoidance)

In IEEE 802.11, communication is performed in a shared wireless medium, so it has fundamentally different characteristics from a wired channel environment. For example, in a wired channel environment, communication was possible based on carrier sense multiple access / collision detection (CSMA / CD). For example, once a signal is transmitted from Tx, the channel environment does not change significantly, so Rx is transmitted without experiencing a large signal attenuation. At this time, when two or more signals collide, detection was possible. This is because the power detected at the Rx stage is instantaneously greater than the power transmitted by Tx. However, in the wireless channel environment, various factors (for example, signal attenuation may be large depending on distance or may experience instantaneous deep fading) affect the channel. Tx cannot accurately perform carrier sensing. Therefore, in 802.11, a distributed coordination function (DCF), which is a carrier sense multiple access / collision avoidance (CSMA / CA) mechanism, was introduced. This performs clear channel assessment (CCA) sensing a medium for a specific duration (eg, DCF inter-frame space (DIFS)) before STAs (stations) having data to transmit transmit the data. At this time, if the medium is idle, the STA can transmit using the medium. However, if the medium is busy, data can be transmitted after waiting for another random backoff period in addition to DIFS under the assumption that several STAs are already waiting to use the medium. At this time, the random backoff period enables collision avoidance, because assuming that there are several STAs for transmitting data, each STA has a different probability of backoff interval and eventually has a different transmission time. to be. When one STA starts transmitting, other STAs cannot use the medium.

The random backoff time and procedure are as follows. When a certain medium changes from busy to idle, several STAs start preparing to send data. At this time, in order to minimize collision, STAs that want to transmit data each select a random backoff count and wait for the slot time. The random backoff count is a pseudo-random integer value, and one of the uniform distribution values in the [0 CW] range is selected. CW stands for contention window. The CW parameter takes the CWmin value as the initial value, but if the transmission fails, the value is doubled. For example, if an ACK response for a transmitted data frame is not received, collision may be considered. When the CW value has the CWmax value, the CWmax value is maintained until the data transmission is successful, and the data transfer succeeds and is reset to the CWmin value. At this time, it is desirable to maintain 2 ⁿ -1 for CW, CWmin, and CWmax for convenience of implementation and operation. Meanwhile, when the random backoff procedure is started, the STA selects a random backoff count within the [0 CW] range and continuously monitors the medium while the backoff slot is counted down. In the meantime, when the medium becomes busy, the count down is stopped. When the medium becomes idle again, the countdown of the remaining backoff slot is resumed.

The most basic of CSMA / CA is carrier sense. The terminal uses physical carrier sense and virtual carrier sense to determine whether the DCF medium is busy / idle. Physical carrier sense is achieved at the PHY (physical layer) stage and is performed through energy detection or preamble detection. For example, if it is determined that the voltage level at the Rx stage is read or the preamble is read, it can be determined that the medium is busy. Virtual carrier sense is to prevent other STAs from transmitting data by setting a network allocation vector (NAV), which is achieved through the value of the Duration field of the MAC header.

2. 2. PHYPHY procedure procedure

In the PHY transmit / receive procedure in Wi-Fi, detailed packet configuration methods may be different, but are as follows. It looks like this: For convenience, we will only give examples for 11n and 11ax, but 11g / ac follows a similar procedure.

That is, the PHY transmit procedure is converted to a single PSDU (PHY service data unit) in the PHY stage when an MACDU (MAC protocol data unit) or A-MPDU (Aggregate MPDU) comes from the MAC stage, and preamble and tail bits, padding bits (if necessary) ), And this is called a PPDU.

The PHY receive procedure is usually as follows. When energy detection and preamble detection (L / HT / VHT / HE-preamble detection for each Wifi version) are performed, information on PSDU configuration is obtained from the PHY header (L / HT / VHT / HE-SIG), MAC header is read, and data Read

In the IEEE 802.11 EHT (Extremely High Throughput) TIG, one of the next-generation Wi-Fi features, considering the multi-AP coordination, proposes the following method.

3. 다중 AP 시스템의 향상3. Improvement of multiple AP system

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 multiple AP systems. The hardware of the multi-AP system has already been marketed, and unlike the 16 spatial streams, it costs little.

There are excellent techniques to improve the performance of multiple AP systems. There are distributed MIMO, cooperative transmission, space / time / frequency sharing and reuse, and an effective relay scheme.

19 shows an example of activating joint multi-AP transmission. Referring to FIG. 19, AP 1 sends an adjustment signal to AP 2 and AP 3 to start joint transmission. AP 2 and AP 3 transmit and receive data with multiple STAs using OFDMA and MU-MIMO in one data packet. STA 2 and STA 3 are in different resource units (RUs), 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 a multi-space stream.

4. 다중 AP 조정(Multi AP coordination)4. Multi AP coordination

20 is a diagram illustrating multiple AP adjustment.

Multiple AP coordination utilizes 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 limits than a single AP with a large antenna array.

The techniques of multi-AP steering include null steering for interference avoidance, joint beamforming, and joint MU-MIMO.

Example 1: Null steering to avoid interference

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

5. AP 조정(AP coordination)5. AP coordination

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

Coordinated scheduling: Coordinated scheduling mitigates / decreases 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 transmissions in a coordinated manner rather than spatial reuse. It is necessary to exchange messages between APs.

23 shows interference nulling and distributed joint beamforming.

Coordinated beamforming: Coordinated beamforming allows simultaneous downlink transmission without co-channel interference caused by beamforming, such as designating a nulling point to another STA or 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, the adjusted beamforming requires adjusted downlink scheduling and improved MU sounding to reduce overhead, synchronization, and the like.

24 shows an example of adjusted beamforming.

The solid arrow in FIG. 24 indicates data transmission in the BSS STA, and the dotted arrow in FIG. 24 is null transmitted to OBSS STAs. As a main attribute, a signal for the user is transmitted from only one AP while forming null in the OBSS STA.

25 is a view for explaining C-OFDMA.

Coordinated-OFDMA (C-OFDMA) is an extension of 11ax OFDMA from a single BSS to multiple BSS scenarios. 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. 25, a spectrum 2510 used for transmission of BSS1 and a spectrum 2520 used for transmission of BSS2 exist in a total of 40 MHz band in a 20 MHz band. Synchronized transmission can be performed to obtain orthogonality. The spectrum 2510 used for the transmission of BSS1 is assigned STAs 1 to 3, and the spectrum 2520 used for the transmission of BSS2 is assigned STAs 4 and 5.

26 shows an example of the joint transmission.

It means performing joint beamforming with a joint transmission and a single STA (J-Tx). Referring to FIG. 26, one STA is serviced by AP1 and AP2.

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

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

The M-AP (Master AP) serves as an AP coordinator. S-AP (Slave AP) participates in joint transmission coordinated by M-AP and may have both STA and AP functions. Referring to FIG. 27, S-AP1 and S-AP2 have a STA function in a coordination step and an AP function in a joint transmission step.

6. 제안하는 6. Offered 실시예Example : 다중 AP 조정 방법(다중 AP 선택과 : Multiple AP adjustment method (with multiple AP selection 사운딩Sounding 방법) Way)

In the Wi-Fi system, multi-AP coordination technology minimizes interference between BSSs during data transmission / reception or transmits / receives data to / from the terminal by sharing channel feedback information and scheduling information of the terminal between APs when transmitting and receiving data frames between the terminal and the AP. This is a method of increasing data transmission efficiency by participating in two or more APs at a time. In the Wi-Fi system, such multi-AP coordination technology has not been standardized yet. Recently, in IEEE802.11 EHT TIG, discussion on standardization related to multi-AP coordination with the next wi-fi technology is ongoing. In this specification, we propose a method in which multiple APs can perform joint transmission by using Multi-AP coordination in a Wi-Fi system.

6.1. Multi-AP 구성6.1. Multi-AP configuration

28 shows an example of a network composed of multiple APs.

Referring to FIG. 28, a master AP (M-AP) selects a plurality of APs performing multi-AP communication by performing a selection procedure for coordinating multiple APs with slave-APs (S-APs). S-AP 1 to S-AP 3 selected by the M-AP may perform a sounding procedure to perform joint transmission to the STA. The description of the M-AP, S-AP (s) and STA shown in FIG. 28 is as follows.

(1) Master AP

-Master AP starts and controls Joint Transmission (JTX).

-The Master AP manages links with Slave-APs to group Slave-APs and share information between Slave-APs.

-The Master AP manages the information of the BSS configured by the Slave APs and the STAs associated with the BSS.

(2) Slave-AP

-Slave-AP can establish control association with Master AP to share control information, management information, and data traffic with each other.

-Slave-AP basically performs the same function as the AP that can form the BSS in the existing WLAN.

(3) STA

-STA configures BSS by associating with Slave AP or Master AP as in the existing WLAN.

6.2. Multi-AP 환경6.2. Multi-AP environment

-Master AP and Slave AP can directly transmit and receive each other.

-Direct transmission and reception between the Master AP and the STA may not be possible.

-Slave AP (associated with STA) and STA can directly transmit and receive each other.

-One of the Slave APs can be the Master AP.

6.3. 조인트 전송 절차의 일례6.3. Example of joint transfer procedure

(1) When the Master AP can directly transmit and receive with the STA

Referring to FIG. 29, the M-AP selects S-AP through a sounding procedure and performs joint transmission to the STA together with the selected S-AP. Details will be described later.

(2) When the Master AP cannot directly transmit / receive the STA

Referring to FIG. 30, the M-AP selects S-AP through a sounding procedure, and only selected S-APs can perform joint transmission for the STA. Details will be described later.

Hereinafter, the joint transmission procedure shown in FIGS. 29 and 30 will be described together. The joint transmission procedure of FIGS. 29 and 30 may be composed of steps 1) to 7).

1) The Master AP sends a JTX trigger frame to Slave AP 1, Slave AP 2, and Slave AP 3 (2910, 3010).

-JTX trigger frame is transmitted to multiple Slave APs at once.

-The Master AP may transmit a JTX trigger frame only to specific Slave APs or all Slave APs that can receive a JTX trigger frame transmitted by a Mater AP.

-The address of the STA that receives the JTX, the BSS information to which the STA belongs, and the address of the Slave AP that has been associated with the STA.

-Slave APs that receive JTX trigger frames operate to match the Master AP or Slave APs with synchronization (Timing, carrier frequency offset (CFO), sampling frequency offset (SFO), and phase drift).

-In the case of Figure 30, the Slave AP (Slave AP 1) associated with the STA prepares to transmit a NDP (Null Data Packet) request frame.

-Slave APs (Slave AP 2, Slave AP 3) that are not associated with the STA prepare to receive an NDP frame to be transmitted by the STA in the future.

2) Slave AP (associated with STA) transmits a JTX NDP request frame to the STA (3020).

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

-Include the address of the STA and the address or indicator of Slave APs that will receive JTX NDP frames in the future.

-The STA receiving the JTX NDP request prepares to transmit the JTX NDP.

2-1) If the STA can directly receive the frame transmitted by the Master AP, the procedure of step 2) may be omitted, and the Master AP may directly transmit the JTX NDP request frame to the STA (2920). The content included in the JTX trigger frame and JTX NDP request of FIG. 29 and the JTX trigger frame and JTX NDP request of FIG. 30 may be the same. In addition, the Master AP may perform steps 1) and 2) at the same time.

3) STA transmits the JTX NDP frame to Slave APs (2930, 3030).

-The STA transmits only the preamble as in the existing NDP format or includes information indicating the slave APs to be received using the newly defined JTX NDP frame.

-When the STA transmits only the preamble, the content is included in the PHY header, and when the STA sends the newly defined JTX NDP frame to indicate the Slave APs, the content is included in the payload.

-Slave APs that receive the JTX NDP frame each estimate the channel with the corresponding STA.

-Slave APs that have received the JTX NDP frame each have channel information with the corresponding STA (received signal strength indicator (RSSI), signal-to-noise ratio (SNR), signal-to-interference-plus-noise ratio (SINR), etc. ).

-Slave APs that have received the JTX NDP frame perform an operation of matching the synchronization between the STA and the Slave APs (Timing, CFO, SFO, Phase drift).

-If the indicators of the Slave APs are included in the JTX NDP frame, the Slave APs can clearly see if the JTX NDP frame is from them.

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

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

4) The Master AP transmits a JTX NDP feedback trigger frame to Slave APs (2940, 3040). The JTX NDP feedback trigger frame is a frame for requesting or triggering a JTX NDP feedback frame.

-The Master AP transmits the JTX NDP feedback trigger frame to the corresponding Slave APs at once.

-Slave AP indicators included in the JTX trigger frame and indicators of the Slave APs are included in the JTX NDP feedback trigger frame.

-Slave APs that have received the JTX NDP feedback trigger frame operate to synchronize the Master AP or Slave APs (Timing, CFO, SFO, Phase drift), and prepare to transmit the JTX NDP feedback frame.

5) Slave APs transmit the JTX NDP feedback frame to the Master AP (2950, 3050).

-Slave APs transmit JTX NDP feedback frames in UL MU-MIMO or UL MU-OFDMA.

-Instead of the above method, JTX NDP feedback frames may be transmitted in order of one Slave AP at the same time.

-The JTX NDP feedback frame includes channel estimation values between each Slave AP and the corresponding STA.

-The Master AP receiving the JTX NDP feedback frame combines the individual channel estimation values between the Slave APs and the corresponding STA into one channel, and selects the Slave APs most suitable for the JTX based on the combined channel information.

6) The Master AP transmits a JTX selection frame to selected Slave APs based on JTX NDP feedback (2960, 3060).

-Among the Slave APs included in the JTX trigger frame and the JTX NDP feedback trigger frame, the JTX selection frame is transmitted only to the Slave APs that will finally participate in JTX. At this time, data can be transmitted between the Master AP and the Slave APs by including data to be transmitted to JTX.

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

-The JTX selection frame contains the addresses or indicators of slave APs that will participate in JTX.

-The JTX selection frame may include data to be transmitted to JTX. Depending on the purpose, the Master AP may share the same data with each Slave AP or different data.)

-Selected Slave APs that have received the JTX selection frame are ready to start JTX.

6-1) The Master AP can send the JTX NDP request once again before performing data sharing to the Slave APs to perform the channel estimation procedure for the JTX and finally select the Slave APs to participate in the JTX.

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

7) The selected Slave APs transmit data to the corresponding STA using JTX (2970, 3070). In the case of Figure 29, the Master AP can transmit data using JTX with the selected Slave AP 1 (2970).

Hereinafter, the above-described embodiment will be described with reference to FIGS. 18 to 30.

The example of FIG. 31 may be performed in a network environment in which a next generation wireless LAN system is supported. The next-generation wireless LAN system is a wireless LAN system (EHT or 802.11be) that improves the 802.11ax system and may satisfy backward compatibility with the 802.11ax system.

In step S3110, a master-access point (M-AP) selects first to third slave-access points (S-APs) to participate in the joint transmission.

In step S3120, the M-AP manages a link with the first to third S-APs to share the first information between the first to third S-APs.

In step S3130, the M-AP performs the joint transmission to a STA (station) through the first to third S-APs based on the first information.

The M-AP is based on a connection with the first to third S-APs, information about a basic service set (BSS) of the first to third S-APs, and information about a STA associated with the BSS. Can be obtained.

The first information may include control information, management information, and data traffic information for the joint transmission.

The M-AP may transmit a joint transmission trigger frame to the first to third S-APs.

The joint transmission trigger frame may include information about the address of the STA, the BSS to which the STA belongs, and the address of the S-AP associated with the STA. Synchronization between the M-AP and the first to third S-APs may be performed based on the joint transmission trigger frame.

When the S-AP associated with the STA is the first S-AP, a joint transmission NDP (Null Data Packet) request frame may be transmitted to the STA by the first S-AP. The joint transmission NDP request frame may include information about the address of the STA and the address of the S-AP to receive the joint transmission NDP frame.

When a channel reciprocity is supported by a channel between the first to third S-APs and the STA, the joint transmission NDP frame may be transmitted to the first to third S-APs by the STA. .

The joint transmission NDP frame may include information on the address of the S-AP to receive the joint transmission NDP frame.

Based on the joint transmission NDP frame, channel estimation between the first to third S-APs and the STA is performed, channel information between the first to third S-APs and the STA is obtained, and the first The synchronization between the third S-AP and the STA may be performed.

The channel information may include a received signal strength indicator (RSSI), a signal-to-noise ratio (SNR), and a signal-to-interference-plus-noise ratio (SINR).

Channel reciprocity is a method of estimating a downlink (DL) channel through a sounding procedure of an uplink (UL) channel. In the present embodiment, the UL MU transmission of the STA (joint transmission NDP) is performed using channel reciprocity. Frame), a method for performing estimation of DL channels of S-APs will be described.

The M-AP may transmit a joint transmission NDP feedback trigger frame to the first to third S-APs.

The M-AP may receive a joint transmission NDP feedback frame in response to the joint transmission NDP feedback trigger frame from the first to third S-APs.

The M-AP may select the optimal S-AP for the joint transmission based on the joint transmission NDP feedback frame.

Specifically, the joint transmission NDP feedback frame may include channel information in which individual values of channel estimation performed between the first to third S-APs and the STA are combined into one. The optimal S-AP for the joint transmission may be selected as the first and second S-APs based on the channel information combined into the one.

The M-AP may transmit a joint transmission selection frame to the first and second S-APs.

The joint transmission selection frame is based on data to be used for the joint transmission, antennas to be used by the first and second S-APs, the number of streams supported by the first and second S-APs, and modulation and coding scheme (MCS). Information.

The data can be shared between the M-AP and the first and second S-APs. The data may be transmitted to the STA by the first and second S-APs. That is, joint transmission by multiple APs may be performed through the above-described procedure.

When the channel between the first to third S-APs and the STA does not support channel reciprocity, the joint transmission NDP frame includes only a Long Training Field (LTF) for one stream. Can be. The STA can only report the power strength through the LTF, and multi-input multi-output (MIMO) is not supported when transmitting a JTX NDP frame.

The joint transmission NDP frame may be transmitted to the STA by the first and second S-APs.

The example of FIG. 32 may be performed in a network environment in which a next generation wireless LAN system is supported. The next-generation wireless LAN system is a wireless LAN system (EHT or 802.11be) that improves the 802.11ax system and may satisfy backward compatibility with the 802.11ax system.

This embodiment is performed at the receiving STA, and the receiving STA is an STA supporting an Extreme High Throughput (EHT) wireless LAN system, and performs joint transmission from the first S-AP, the second S-AP, or the third S-AP. It may correspond to the STA receiving the data. The transmitting STA of this embodiment may correspond to the M-AP.

In step S3210, a STA (station) receives the data from the first and second S-AP (Slave-Access Point) through the joint transmission.

In step S3220, the STA decodes the data.

The first and second S-APs are S-APs selected by a master-access point (M-AP) among the first to third S-APs.

In order to share the first information between the first to third S-APs, the M-AP and the first to third S-AP links are established.

The data is received based on the first information.

Channel reciprocity is a method of estimating a downlink (DL) channel through a sounding procedure of an uplink (UL) channel. In the present embodiment, the STA uses UL MU transmission (joint transmission NDP) using channel reciprocity. Frame), a method for performing estimation of DL channels of S-APs will be described.

7. 장치 구성7. Device Configuration

33 shows a more detailed wireless device implementing an embodiment of the present invention. The present invention described above for the transmitting device or the receiving device can be applied to this embodiment.

The wireless device includes a processor 610, a power management module 611, a battery 612, a display 613, a keypad 614, a subscriber identification module (SIM) card 615, a memory 620, and a transceiver 630 ), One or more antennas 631, a speaker 640 and a microphone 641.

The processor 610 may be configured to implement the proposed functions, procedures and / or methods described herein. Layers of the radio interface protocol may be implemented in the processor 610. The processor 610 may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and / or data processing devices. The processor may be an application processor (AP). The processor 610 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). Examples of processors 610 include SNAPDRAGONTM series processors manufactured by Qualcomm®, EXYNOSTM series processors manufactured by Samsung®, A series processors manufactured by Apple®, HELIOTM series processors manufactured by MediaTek®, and INTEL®. It may be an ATOMTM series processor manufactured by or a corresponding next-generation processor.

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 the results 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 is an integrated circuit used to securely store an international mobile subscriber identity (IMSI) 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. Many SIM cards can also store contact information.

The memory 620 is operatively coupled with the processor 610, and stores various information for operating the processor 610. The memory 620 may include read-only memory (ROM), random access memory (RAM), flash memory, a memory card, a storage medium, and / or other storage devices. When the embodiment is implemented in software, the techniques described herein may be implemented as a module (eg, procedure, function, etc.) that performs the functions described herein. Modules may be stored in memory 620 and executed by processor 610. The memory 620 may be implemented inside the processor 610. Alternatively, the memory 620 may be implemented outside the processor 610 and may be communicatively connected to the processor 610 through various means known in the art.

The transceiver 630 is operatively coupled with the processor 610, and transmits and / or receives wireless signals. The transceiver 630 includes a transmitter and a receiver. The transmitting and receiving unit 630 may include a baseband circuit for processing radio frequency signals. The transmitting and receiving unit controls one or more antennas 631 to transmit and / or receive wireless signals.

The speaker 640 outputs sound-related results processed by the processor 610. The microphone 641 receives sound-related inputs to be used by the processor 610.

In the case of a transmitting STA, the processor 610 selects first to third slave-access points (S-APs) to participate in the joint transmission, and shares first information between the first to third S-APs In order to manage the link with the first to third S-APs, the joint transmission to the STA (station) is performed through the first to third S-APs based on the first information.

In the case of a receiving STA, the processor 610 receives the data through the joint transmission from the first and second slave-access points (S-APs) and decodes the data.

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

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

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

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

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

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

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

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

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

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

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

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

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

Augmented reality refers to virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology provides real-world objects or backgrounds only as CG images, AR technology provides CG images made virtually on real objects, and MR technology is a computer that mixes and combines virtual objects in the real world. Graphics technology.

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

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

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

Claims

In the method of performing joint transmission (joint transmission) in a wireless LAN system,

A master-access point (M-AP) selecting first to third slave-access points (S-APs) to participate in the joint transmission;

Managing, by the M-AP, a link with the first to third S-APs to share first information between the first to third S-APs; And

And the M-AP performing the joint transmission to a STA (station) through the first to third S-APs based on the first information.

Way.
According to claim 1,

The M-AP, based on a connection with the first to third S-APs, information about a basic service set (BSS) of the first to third S-APs and an STA associated with the BSS Further comprising obtaining the information

Way.
According to claim 1,

The first information includes control information, management information, and data traffic information for the joint transmission.

Way.
According to claim 1,

The M-AP, further comprising the step of transmitting the joint transmission trigger frame to the first to third S-AP,

The joint transmission trigger frame includes information about the address of the STA, the BSS to which the STA belongs, and the address of the S-AP associated with the STA,

Synchronization between the M-AP and the first to third S-APs is performed based on the joint transmission trigger frame.

Way.
The method of claim 4,

When the S-AP associated with the STA is the first S-AP,

A joint transmission NDP (Null Data Packet) request frame is transmitted to the STA by the first S-AP,

The joint transmission NDP request frame includes information on the address of the STA and the address of the S-AP to receive the joint transmission NDP frame.

Way.
The method of claim 5,

When the channel between the first to third S-AP and the STA is supported by channel reciprocity,

The joint transmission NDP frame is transmitted to the first to third S-APs by the STA,

The joint transmission NDP frame includes information on the address of the S-AP to receive the joint transmission NDP frame,

Based on the joint transmission NDP frame, channel estimation between the first to third S-AP and the STA is performed, channel information between the first to third S-AP and the STA is obtained, and the first The synchronization between the third S-AP and the STA is performed,

The channel information includes a received signal strength indicator (RSSI), a signal-to-noise ratio (SNR), and a signal-to-interference-plus-noise ratio (SINR).

Way.
The method of claim 6,

Sending, by the M-AP, a joint transmission NDP feedback trigger frame to the first to third S-APs;

The M-AP receiving a joint transmission NDP feedback frame that is a response to the joint transmission NDP feedback trigger frame from the first to third S-APs; And

The M-AP, further comprising the step of selecting the optimal S-AP for the joint transmission based on the joint transmission NDP feedback frame,

The joint transmission NDP feedback frame includes channel information in which individual values of channel estimation performed between the first to third S-APs and the STA are combined into one,

The S-AP that is optimal for the joint transmission is selected as the first and second S-APs based on the channel information combined into the one.

Way.
The method of claim 7,

The M-AP, further comprising the step of transmitting the joint transmission selection frame to the first and second S-AP,

The joint transmission selection frame is based on data to be used for the joint transmission, antennas to be used by the first and second S-APs, the number of streams supported by the first and second S-APs, and modulation and coding scheme (MCS). Information about,

The data is shared between the M-AP and the first and second S-APs,

The data is transmitted to the STA by the first and second S-AP

Way.
The method of claim 7,

When the channel between the first to third S-AP and the STA does not support channel reciprocity,

The joint transmission NDP frame includes only a LTF (Long Training Field) for one stream, or

The joint transmission NDP frame is transmitted to the STA by the first and second S-APs.

Way.
In a master-access point (M-AP) performing joint transmission in a wireless LAN system, the M-AP includes:

Memory;

Transceiver; And

A processor operatively coupled to the memory and the transceiver, the processor comprising:

Select first to third S-APs (Slave-Access Points) to participate in the joint transmission;

Manage links with the first to third S-APs to share first information between the first to third S-APs; And

Performing the joint transmission to a STA (station) through the first to third S-AP based on the first information

Wireless devices.
The method of claim 10,

The processor, based on the connection with the first to third S-AP, information on the basic service set (BSS) of the first to third S-AP and information on the STA associated with the BSS To acquire

Wireless devices.
The method of claim 10,

The first information includes control information, management information, and data traffic information for the joint transmission.

Wireless devices.
The method of claim 10,

The processor transmits a joint transmission trigger frame to the first to third S-APs,

The joint transmission trigger frame includes information about the address of the STA, the BSS to which the STA belongs, and the address of the S-AP associated with the STA,

Synchronization between the M-AP and the first to third S-APs is performed based on the joint transmission trigger frame.

Wireless devices.
The method of claim 13,

When the S-AP associated with the STA is the first S-AP,

A joint transmission NDP (Null Data Packet) request frame is transmitted to the STA by the first S-AP,

The joint transmission NDP request frame includes information on the address of the STA and the address of the S-AP to receive the joint transmission NDP frame.

Wireless devices.
The method of claim 14,

When the channel between the first to third S-AP and the STA is supported by channel reciprocity,

The joint transmission NDP frame is transmitted to the first to third S-APs by the STA,

The joint transmission NDP frame includes information on the address of the S-AP to receive the joint transmission NDP frame,

Based on the joint transmission NDP frame, channel estimation between the first to third S-AP and the STA is performed, channel information between the first to third S-AP and the STA is obtained, and the first The synchronization between the third S-AP and the STA is performed,

The channel information includes a received signal strength indicator (RSSI), a signal-to-noise ratio (SNR), and a signal-to-interference-plus-noise ratio (SINR).

Wireless devices.
The method of claim 15,

The processor transmits a joint transmission NDP feedback trigger frame to the first to third S-APs;

The processor receives a joint transmission NDP feedback frame in response to the joint transmission NDP feedback trigger frame from the first to third S-APs; And

The processor selects the optimal S-AP for the joint transmission based on the joint transmission NDP feedback frame,

The joint transmission NDP feedback frame includes channel information in which individual values of channel estimation performed between the first to third S-APs and the STA are combined into one,

The S-AP that is optimal for the joint transmission is selected as the first and second S-APs based on the channel information combined into the one.

Wireless devices.
The method of claim 16,

The processor transmits a joint transmission selection frame to the first and second S-APs,

The joint transmission selection frame is based on data to be used for the joint transmission, antennas to be used by the first and second S-APs, the number of streams supported by the first and second S-APs, and modulation and coding scheme (MCS). Information about,

The data is shared between the M-AP and the first and second S-APs,

The data is transmitted to the STA by the first and second S-AP

Wireless devices.
The method of claim 16,

When the channel between the first to third S-AP and the STA does not support channel reciprocity,

The joint transmission NDP frame includes only a LTF (Long Training Field) for one stream, or

The joint transmission NDP frame is transmitted to the STA by the first and second S-APs.

Wireless devices.
In the method of receiving data through a joint transmission (joint transmission) in a wireless LAN system,

STA (station), receiving the data from the first and second S-AP (Slave-Access Point) through the joint transmission; And

The STA, comprising the step of decoding the data,

The first and second S-APs are S-APs selected by a master-access point (M-AP) among the first to third S-APs,

The M-AP and the first to third S-AP links are established to share the first information between the first to third S-APs,

The data is received based on the first information

Way.