WO2021029564A1

WO2021029564A1 - Ack for harq operation

Info

Publication number: WO2021029564A1
Application number: PCT/KR2020/009844
Authority: WO
Inventors: 송태원; 김정기; 최진수; 김서욱; 김진민; 박성진; 장인선
Original assignee: 엘지전자 주식회사
Priority date: 2019-08-12
Filing date: 2020-07-27
Publication date: 2021-02-18

Abstract

In a wireless local area network (WLAN) system, a transmitting station (STA) can transmit a physical protocol data unit (PPDU). The transmitting STA can receive a first feedback frame for the PPDU. The transmitting STA can update a retransmission timer on the basis of the first feedback frame. The transmitting STA can retransmit physical (PHY) layer on the basis of the first feedback frame. The first feedback frame can be a PHY layer signal. The retransmission timer can be a timer related to media access control (MAC) layer retransmission.

Description

ACK for HARQ operation

The present specification relates to a method of performing a PHY level HARQ operation in a wireless local area network (LAN) system.

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

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

A method performed by a station (STA) in a wireless local area network (LAN) system according to various embodiments may include a technical feature for performing a HARQ operation. The transmitting station (STA) may transmit a physical protocol data unit (PPDU). The transmitting STA may receive a first feedback frame for the PPDU. The transmitting STA may update a retransmission timer based on the first feedback frame. The transmitting STA may perform physical (PHY) layer retransmission based on the first feedback frame. The first feedback frame may be a PHY layer signal. The retransmission timer may be a timer related to media access control (MAC) layer retransmission.

According to an example of the present specification, the MAC of the STA may not perform retransmission while performing the PHY level HARQ retransmission operation. While the PHY-level HARQ retransmission process is in progress, it is not known whether PHY level HARQ retransmission is being performed at the MAC-level. Accordingly, an attempt to retransmit MPDUs from the MAC of the transmitter may occur. In order to prevent HARQ retransmission at the MAC level while PHY level HARQ retransmission is performed, the SIFS Timeout reset function should be supported. For example, the MAC of the transmitting end may perform retransmission if an ACK or BA frame is not received within a predetermined time. Therefore, it is necessary to reset the retransmission timer that records a certain time. A special field indication for resetting the retransmission timer is not required, and the PHY of the transmitter may inform the MAC of the transmitter through the internal operation of the device.

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

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

3 is a diagram illustrating a general link setup process.

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

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

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

7 is a diagram showing the arrangement of resource units (RU) used in the 80MHz band.

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

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

10 shows the operation according to the UL-MU.

11 shows an example of a trigger frame.

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

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

14 describes the technical features of the UORA technique.

15 shows an example of a channel used/supported/defined within a 2.4 GHz band.

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

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

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

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

20 is a diagram showing an example of chase combining. Chase combining is a method in which the same coded bit as the initial transmission is retransmitted.

21 is a diagram showing an example of an incremental redundancy (IR) method.

22 is a diagram illustrating an embodiment of a MAC frame format including information related to HARQ ACK policy.

23 is a diagram illustrating an embodiment of a HARQ operation method to which a HARQ delayed ACK policy is applied.

24 to 35 are diagrams illustrating an embodiment of a method of operating HARQ.

36 is a diagram illustrating an embodiment of a method of operating a transmitting STA.

37 is a diagram illustrating an embodiment of a method of operating a receiving STA.

38 is a diagram illustrating an embodiment of an operation of a MAC layer of a transmitting STA.

39 is a diagram illustrating an embodiment of an operation of a MAC layer of a receiving STA.

In the present specification,'A or B (A or B)' may mean'only A','only B', or'both A and B'. In other words, in the present specification,'A or B (A or B)' may be interpreted as'A and/or B (A and/or B)'. For example, in the present specification,'A, B or C (A, B or C)' means'only A','only B','only C', or any and all combinations of'A, B and C'( It can mean any combination of A, B and C)'.

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

In the present specification,'at least one of A and B'may mean'only A','only B', or'both A and B'. In addition, the expression'at least one of A or B (at least one of A or B)' or'at least one of A and/or B (at least one of A and/or B)' in the present specification is'at least one A and B (at least one of A and B)' can be interpreted the same.

In addition, in the present specification,'at least one of A, B and C (at least one of A, B and C)' means'only A','only B','only C', or'A, B and C It may mean any combination of A, B and C'. In addition,'at least one of A, B or C (at least one of A, B or C)' or'at least one of A, B and/or C (at least one of A, B and/or C)' It may mean'at least one of A, B and C'.

In addition, 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 other words,'control information' in the present specification is not limited to'EHT-Signal', and'EHT-Signal' may be suggested as an example of'control information'. In addition, even when indicated as'control information (ie, EHT-signal)','EHT-signal' may be proposed as an example of'control information'.

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

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

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

The example of FIG. 1 may perform various technical features described below. 1 is related to at least one STA (station). For example, the

STAs

110 and 120 of the present specification include a mobile terminal, a wireless device, a wireless transmit/receive unit (WTRU), a user equipment (UE), It may be referred to by various names such as a mobile station (MS), a mobile subscriber unit, or simply a user.

STAs

110 and 120 of the present specification may be referred to by various names such as a network, a base station, a Node-B, an access point (AP), a repeater, a router, and a relay. The

STAs

110 and 120 of the present specification may be referred to by various names such as a receiving device, a transmitting device, a receiving STA, a transmitting STA, a receiving device, and a transmitting device.

For example, the

STAs

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

STAs

110 and 120 of the present specification may perform AP and/or non-AP functions. In the present specification, the AP may also be indicated as an AP STA.

The

STAs

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

In the present specification, the

STAs

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

The

STAs

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

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

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

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

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

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

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

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

In the following specification, (transmit/receive) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmit/receive) Terminal, (transmit/receive) device , (Transmission/reception) apparatus, a device called a network, etc. may refer to the

STAs

110 and 120 of FIG. 1. For example, without specific reference numerals (transmission/reception) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmission/reception) Terminal, (transmission Devices displayed as /receive) device, (transmit/receive) apparatus, network, etc. may also mean the

STAs

110 and 120 of FIG. 1. For example, in the following example, an operation in which various STAs transmit and receive signals (eg, PPPDUs) may be performed by the

transceivers

113 and 123 of FIG. 1. In addition, in the following example, an operation in which various STAs generate transmission/reception signals or perform data processing or calculation in advance for transmission/reception signals may be performed by the

processors

111 and 121 of FIG. 1. For example, an example of an operation of generating a transmission/reception signal or performing data processing or calculation in advance for a transmission/reception signal is: 1) Determining bit information of a subfield (SIG, STF, LTF, Data) field included in the PPDU. /Acquisition/configuration/computation/decoding/encoding operations, 2) Time resources or frequency resources (eg, subcarrier resources) used for subfields (SIG, STF, LTF, Data) included in the PPDU, etc. Determination/configuration/retrieve operation, 3) A specific sequence used for the subfields (SIG, STF, LTF, Data) fields included in the PPDU (e.g., pilot sequence, STF/LTF sequence, applied to SIG) An operation of determining/configuring/obtaining an extra sequence), 4) a power control operation and/or a power saving operation applied to the STA, 5) an operation related to determination/acquisition/configuration/calculation/decoding/encoding of an ACK signal, etc. Can include. In addition, in the following example, various information used by various STAs for determination/acquisition/configuration/calculation/decoding/encoding of transmission/reception signals (for example, information related to fields/subfields/control fields/parameters/power, etc.) It may be stored in the

memories

112 and 122 of FIG. 1.

The device/STA of the sub-drawing (a) of FIG. 1 described above may be modified as shown in the sub-drawing (b) of FIG. 1. Hereinafter, the

STAs

110 and 120 of the present specification will be described based on the sub-drawing (b) of FIG. 1.

For example, the

transceivers

113 and 123 illustrated in sub-drawing (b) of FIG. 1 may perform the same functions as the transceiver illustrated in sub-drawing (a) of FIG. 1. For example, the

processing chips

114 and 124 shown in sub-drawing (b) of FIG. 1 may include

processors

111 and 121 and

memories

112 and 122. The

processors

111 and 121 and the

memories

112 and 122 illustrated in sub-drawing (b) of FIG. 1 are the

processors

111 and 121 and the

memories

112 and 122 illustrated in sub-drawing (a) of FIG. ) And can perform the same function.

A mobile terminal, a wireless device, a wireless transmit/receive unit (WTRU), a user equipment (UE), a mobile station (MS), and a mobile device described below. Mobile Subscriber Unit, user, user STA, network, base station, Node-B, AP (Access Point), repeater, router, relay, receiving device, transmitting device, receiving STA, transmitting The STA, the receiving device, the transmitting device, the receiving Apparatus, and/or the transmitting Apparatus means the

STAs

110 and 120 shown in sub-drawings (a)/(b) of FIG. 1, or the sub-drawing of FIG. 1 (b It may mean the

processing chips

114 and 124 shown in ). That is, the technical features of the present specification may be performed on the

STAs

110 and 120 shown in sub-drawings (a)/(b) of FIG. 1, and the processing chip shown in sub-drawing (b) of FIG. 114, 124). For example, the technical feature of the transmitting STA transmitting the control signal is that the control signal generated by the

processors

111 and 121 shown in sub-drawings (a)/(b) of FIG. 1 is sub-drawing (a) of FIG. It can be understood as a technical feature transmitted through the

transceivers

113 and 123 shown in )/(b). Alternatively, the technical feature in which the transmitting STA transmits the control signal is a technical feature in which a control signal to be transmitted to the

transceivers

113 and 123 is generated from the

processing chips

114 and 124 shown in sub-drawing (b) of FIG. 1. Can be understood.

For example, the technical characteristic that the receiving STA receives the control signal may be understood as a technical characteristic in which the control signal is received by the

transceivers

113 and 123 shown in sub-drawing (a) of FIG. 1. Alternatively, the technical feature that the receiving STA receives the control signal is that the control signal received by the

transceivers

113 and 123 shown in sub-drawing (a) of FIG. 1 is the processor shown in sub-drawing (a) of FIG. 111, 121) can be understood as a technical feature obtained. Alternatively, the technical feature that the receiving STA receives the control signal is that the control signal received by the

transceivers

113 and 123 shown in sub-drawing (b) of FIG. 1 is a processing chip shown in sub-drawing (b) of FIG. It can be understood as a technical feature obtained by (114, 124).

Referring to sub-drawing (b) of FIG. 1,

software codes

115 and 125 may be included in the

memories

112 and 122. The

software codes

115 and 125 may include instructions for controlling the operations of the

processors

111 and 121. The

software codes

115 and 125 may be included in various programming languages.

The

processors

111 and 121 or the

processing chips

114 and 124 illustrated in FIG. 1 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and/or a data processing device. The processor may be an application processor (AP). For example, the

processors

111 and 121 or the

processing chips

114 and 124 shown in FIG. 1 are a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator). and demodulator). For example, the

processors

111 and 121 or the

processing chips

114 and 124 shown in FIG. 1 are SNAPDRAGONTM series processors manufactured by Qualcomm®, EXYNOSTM series processors manufactured by Samsung®, and It may be an A series processor, a HELIOTM series processor manufactured by MediaTek®, an ATOMTM series processor manufactured by INTEL®, or an enhanced processor thereof.

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

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

The upper part of FIG. 2 shows the structure of an infrastructure BSS (basic service set) of IEEE (institute of electrical and electronic engineers) 802.11.

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

The BSS may include at least one STA,

APs

225 and 230 providing a distribution service, and a distribution system (DS) 210 connecting a plurality of APs.

The distributed system 210 may implement an extended service set (ESS) 240, which is an extended service set, by connecting

several BSSs

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

The portal 220 may serve as a bridge for connecting a wireless LAN network (IEEE 802.11) and another network (eg, 802.X).

In the BSS as shown in the upper part of FIG. 2, a network between the

APs

225 and 230 and a network between the

APs

225 and 230 and the STAs 200-1, 205-1 and 205-2 may be implemented. However, it may be possible to perform communication by setting up a network even between STAs without the

APs

225 and 230. A network that performs communication by configuring a network even between STAs without the

APs

225 and 230 is defined as an ad-hoc network or an independent basic service set (IBSS).

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

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

3 is a diagram illustrating a general link setup process.

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

3 illustrates an example of a network discovery operation including an active scanning process. In active scanning, the STA performing scanning transmits a probe request frame to search for an AP present in the vicinity while moving channels and waits for a response thereto. The responder transmits a probe response frame in response to the probe request frame to the STA that has transmitted the probe request frame. Here, the responder may be an STA that last transmitted a beacon frame in the BSS of the channel being scanned. In BSS, since the AP transmits a beacon frame, the AP becomes a responder, and in IBSS, because STAs in the IBSS rotate and transmit beacon frames, 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 (e.g., 2 Channel) and scanning (that is, probe request/response transmission/reception on channel 2) in the same manner.

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

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

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

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

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

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

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

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

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

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

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

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

As shown at the top of Fig. 5, 26-units (ie, units corresponding to 26 tones) may be arranged. In the leftmost band of the 20MHz band, 6 tones may be used as a guard band, and in the rightmost band of the 20MHz band, 5 tones may be used as the guard band. In addition, 7 DC tones are inserted in the center band, that is, the DC band, and 26-units corresponding to 13 tones may exist on the left and right sides of the DC band. In addition, 26-units, 52-units, and 106-units may be allocated to other bands. Each unit can be assigned for a receiving station, i.e. a user.

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

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

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

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

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

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

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

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

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

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

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

As shown in FIG. 8, the common field 820 and the user-individual field 830 may be encoded separately.

The common field 820 may include N*8 bits of RU allocation information. For example, the RU allocation information may include information on the location of the RU. For example, when a 20 MHz channel is used as shown in FIG. 5, the RU allocation information may include information on which RU (26-RU/52-RU/106-RU) is allocated in which frequency band. .

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

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

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

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

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

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

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

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

For example, if RU allocation is set to '01000010' as shown in FIG. 9, based on Table 2, 106-RUs are allocated to the leftmost-left side of a specific channel, and five 26-RUs are allocated to the right side. I can. In addition, a total of three User STAs may be allocated to the 106-RU through the MU-MIMO scheme. As a result, since a total of 8 User STAs are allocated, the user-individual field 830 of HE-SIG-B may include 8 User fields.

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

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

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

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

As shown in Table 3 and/or Table 4, the second bit (i.e., B11-B14) may include information on the number of Spatial Streams allocated to a plurality of User STAs allocated according to the MU-MIMO scheme. have. For example, when three User STAs are allocated to 106-RU based on the MU-MIMO technique as shown in FIG. 9, N_user is set to '3', and accordingly, N_STS[1], as shown in Table 3, Values of N_STS[2] and N_STS[3] may be determined. For example, when the value of the second bit (B11-B14) is '0011', it may be set as N_STS[1]=4, N_STS[2]=1, and N_STS[3]=1. That is, in the example of FIG. 9, 4 Spatial Streams may be allocated to

User field

1, 1 Spatial Stream may be allocated to

User field

2, and 1 Spatial Stream may be allocated to User field 3.

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

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

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

In addition, the fourth bit (ie, B19) in the user field (ie, 21 bits) may be a reserved field.

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

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

The first bit (eg, B0-B10) in the User field of the second format may include identification information of the User STA. In addition, the second bit (eg, B11-B13) in the user field of the second format may include information on the number of spatial streams applied to the corresponding RU. In addition, the third bit (eg, B14) in the user field of the second format may include information on whether the beamforming steering matrix is applied. The fourth bit (eg, B15-B18) in the User field of the second format may include MCS (Modulation and Coding Scheme) information. In addition, the fifth bit (eg, B19) in the User field of the second format may include information on whether or not Dual Carrier Modulation (DCM) is applied. In addition, the sixth bit (ie, B20) in the user field of the second format may include information on the coding type (eg, BCC or LDPC).

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

The

TB PPDUs

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

Specific characteristics of the trigger frame will be described with reference to FIGS. 11 to 13. Even when UL-MU communication is used, an orthogonal frequency division multiple access (OFDMA) technique or an MU MIMO technique can be used, and an OFDMA and MU MIMO technique can be used simultaneously.

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

Each of the fields shown in FIG. 11 may be partially omitted, and other fields may be added. In addition, 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 includes time information for setting NAV or an identifier of the STA (for example, For example, information on AID) may be included.

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

In addition, it is preferable to include individual user information fields 1160#1 to 1160#N corresponding to the number of receiving STAs receiving the trigger frame of FIG. 11. The individual user information field may be referred to as an'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 shown in FIG. 11 may again include a plurality of subfields.

12 shows an example of a common information field of a trigger frame. Some of the subfields of FIG. 12 may be omitted, and other subfields may be added. In addition, the length of each of the illustrated subfields may be changed.

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

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

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

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

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

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

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

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

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

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

In addition, the subfield of FIG. 13 may include an MCS field 1340. The MCS field 1340 may indicate an MCS scheme applied to a TB PPDU. For example, when BCC coding is applied to the TB PPDU, the coding type field 1330 may be set to '1', and when LDPC coding is applied, the coding type field 1330 may be set to '0'. have.

Hereinafter, a UL OFDMA-based Random Access (UORA) technique will be described.

14 describes the technical features of the UORA technique.

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

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

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

15 shows an example of a channel used/supported/defined within a 2.4 GHz band.

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

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

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

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

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

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

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

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

The 6 GHz band may be referred to as a third band/band. The 6 GHz band may mean a frequency region in which channels with a center frequency of 5.9 GHz or more are used/supported/defined. The specific values shown in FIG. 17 may be changed.

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

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

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

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

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

The PPDU of FIG. 18 may be referred to as various names such as EHT PPDU, transmission PPDU, reception PPDU, 1st type or Nth type PPDU. For example, in this specification, the PPDU or EHT PPDU may be referred to as various names such as a transmission PPDU, a reception PPDU, a first type or an N type PPDU. In addition, the EHT PPU can be used in the EHT system and/or in a new wireless LAN system with an improved EHT system.

The PPDU of FIG. 18 may represent some or all of the PPDU types used in the EHT system. For example, the example of FIG. 18 may be used for both a single-user (SU) mode and a multi-user (MU) mode, only the SU mode, or only the MU mode. For example, in the EHT system, a trigger-based PPDU (TB) may be defined separately or may be configured based on the example of FIG. 18. The trigger frame described through at least one of FIGS. 10 to 14 and the UL-MU operation initiated by the trigger frame (eg, transmission operation of a TB PPDU) may be applied to the EHT system as it is.

In FIG. 18, L-STF to EHT-LTF may be referred to as a preamble or a physical preamble, and may be generated/transmitted/received/acquired/decoded in the physical layer.

The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields of FIG. 18 is set to 312.5 kHz, and the subcarrier spacing of the EHT-STF, EHT-LTF, and Data fields Can be set to 78.125 kHz. That is, the tone index (or subcarrier index) of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields is displayed in units of 312.5 kHz, EHT-STF, EHT-LTF, The tone index (or subcarrier index) of the data field may be displayed in units of 78.125 kHz.

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

The L-SIG field of FIG. 18 may include, for example, 24-bit bit information. For example, the 24-bit information may include a 4 bit Rate field, 1 bit Reserved bit, 12 bit Length field, 1 bit Parity bit, and 6 bit Tail bit. For example, the 12-bit Length field may include information on the length or time duration of the PPDU. For example, the value of the 12-bit Length field may be determined based on the type of PPDU. For example, when the PPDU is a non-HT, HT, VHT PPDU or EHT PPDU, the value of the Length field may be determined as a multiple of 3. For example, when the PPDU is an HE PPDU, a value of the Length field may be determined as'multiple of 3 + 1'or'multiple of 3 +2'. In other words, for non-HT, HT, VHT PPDU or EHT PPDU, the value of the Length field can be determined as a multiple of 3, and for HE PPDU, the value of the Length field is'multiple of 3 + 1'or'multiple of 3' It can be determined as +2'.

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

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

After the RL-SIG of FIG. 18, a Universal SIG (U-SIG) may be inserted. The U-SIG may be referred to by various names such as a first SIG field, a first SIG, a first type SIG, a control signal, a control signal field, and a first (type) control signal.

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

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

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

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

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

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

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

For example, when the EHT PPDU is classified into various types (e.g., EHT PPDU supporting SU, EHT PPDU supporting MU, EHT PPDU related to Trigger Frame, EHT PPDU related to Extended Range transmission, etc.) , Information on the type of the EHT PPDU may be included in version-dependent bits of U-SIG.

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

Preamble puncturing may be applied to the PPDU of FIG. 18. Preamble puncturing refers to applying puncturing to some bands (eg, Secondary 20 MHz band) among the entire bands of the PPDU. For example, when an 80 MHz PPDU is transmitted, the STA may apply puncture to the secondary 20 MHz band of the 80 MHz band, and transmit the PPDU only through the primary 20 MHz band and the secondary 40 MHz band.

For example, the pattern of preamble puncturing may be set in advance. For example, when the first puncturing pattern is applied, puncturing may be applied only to a secondary 20 MHz band within an 80 MHz band. For example, when the second puncturing pattern is applied, puncturing may be applied to only one of two secondary 20 MHz bands included in the secondary 40 MHz band within the 80 MHz band. For example, when the third puncturing pattern is applied, puncturing may be applied only to the secondary 20 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band). For example, when the fourth puncturing pattern is applied, the primary 40 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band) is present and does not belong to the primary 40 MHz band. Puncturing may be applied to at least one 20 MHz channel that does not exist.

Information on preamble puncturing applied to the PPDU may be included in U-SIG and/or EHT-SIG. For example, a first field of U-SIG may contain information on a contiguous bandwidth of a PPDU, and a second field of U-SIG may contain information on preamble puncturing applied to a PPDU. have.

For example, U-SIG and EHT-SIG may include information on preamble puncturing based on the following method. When the bandwidth of the PPDU exceeds 80 MHz, the U-SIG can be individually configured in units of 80 MHz. For example, when the bandwidth of the PPDU is 160 MHz, the PPDU may include a first U-SIG for a first 80 MHz band and a second U-SIG for a second 80 MHz band. In this case, the first field of the first U-SIG includes information on the 160 MHz bandwidth, and the second field of the first U-SIG is information on preamble puncturing applied to the first 80 MHz band (i.e., preamble Information about puncturing patterns) may be included. In addition, the first field of the second U-SIG includes information on a 160 MHz bandwidth, and the second field of the second U-SIG is information on preamble puncturing applied to the second 80 MHz band (ie, preamble puncturing). Information on the processing pattern) may be included. Meanwhile, the EHT-SIG continuing to the first U-SIG may include information on preamble puncturing applied to the second 80 MHz band (ie, information on preamble puncturing pattern), and in the second U-SIG Consecutive EHT-SIG may include information on preamble puncturing applied to the first 80 MHz band (ie, information on preamble puncturing pattern).

Additionally or alternatively, U-SIG and EHT-SIG may include information on preamble puncturing based on the following method. The U-SIG may include information on preamble puncturing for all bands (that is, information on preamble puncturing pattern). That is, the EHT-SIG does not include information on preamble puncturing, and only U-SIG may include information on preamble puncturing (ie, information on preamble puncturing pattern).

U-SIG can be configured in units of 20 MHz. For example, when an 80 MHz PPDU is configured, U-SIG can be duplicated. That is, the same four U-SIGs may be included in the 80 MHz PPDU. PPDUs exceeding the 80 MHz bandwidth may contain different U-SIGs.

The EHT-SIG of FIG. 18 may include the technical features of HE-SIG-B shown in the example of FIGS. 8 to 9 as it is. The EHT-SIG may be referred to by various names such as a second SIG field, a second SIG, a second type SIG, a control signal, a control signal field, and a second (type) control signal.

The EHT-SIG may include N-bit information (eg, 1-bit information) regarding whether the EHT-PPDU supports the SU mode or the MU mode.

EHT-SIG can be configured based on various MCS techniques. As described above, information related to the MCS technique applied to the EHT-SIG may be included in the U-SIG. The EHT-SIG can be configured based on the DCM technique. For example, of the N data tones (e.g., 52 data tones) allocated for EHT-SIG, the first modulation technique is applied to half of the continuous tones, and the second modulation is applied to the remaining half of the tones. The technique can be applied. In other words, the transmitting STA modulates specific control information with a first symbol based on the first modulation technique and allocates it to a continuous half tone, modulates the same control information with a second symbol based on the second modulation technique, and It can be assigned to half of the tone. As described above, information related to whether the DCM technique is applied to the EHT-SIG (for example, a 1-bit field) may be included in the U-SIG. The EHT-STF of FIG. 18 is a multiple input multiple output (MIMO) environment or It can be used to improve automatic gain control estimation in an OFDMA environment. The EHT-LTF of FIG. 18 may be used to estimate a channel in a MIMO environment or an OFDMA environment.

The EHT-STF of FIG. 18 may be set in various types. For example, the first type of STF (that is, 1x STF) may be generated based on a first type STF sequence in which non-zero coefficients are arranged at 16 subcarrier intervals. The STF signal generated based on the first type STF sequence may have a period of 0.8 μs, and the 0.8 μs period signal may be repeated 5 times to become a first type STF having a length of 4 μs. For example, the second type of STF (that is, 2x STF) may be generated based on a second type STF sequence in which non-zero coefficients are arranged at 8 subcarrier intervals. The STF signal generated based on the second type STF sequence may have a period of 1.6 μs, and the 1.6 μs period signal may be repeated 5 times to become a second type EHT-STF having a length of 8 μs. Hereinafter, an example of a sequence (ie, an EHT-STF sequence) for configuring the EHT-STF is presented. The following sequence can be modified in various ways.

The EHT-STF may be configured based on the following M sequence.

M = {-1, -1, -1, 1, 1, 1, -1, 1, 1, 1, -1, 1, 1, -1, 1}

EHT-STF for 20 MHz PPDU may be configured based on the following equation. The following example may be a first type (ie, 1x STF) sequence. For example, the first type sequence may be included in an EHT-PPDU other than a trigger-based (TB) PPDU. In the following equation, (a:b:c) may mean a section defined as a b tone interval (ie, subcarrier interval) from a tone index (ie, subcarrier index) to c tone index. For example, Equation 2 below may represent a sequence defined by 16 tone intervals from the tone index -112 to the 112 index. Since subcarrier spacing of 78.125 kHz is applied to the EHT-STF, 16 tone intervals may mean that EHT-STF coefficients (or elements) are arranged at 78.125 * 16 = 1250 kHz intervals. Also, * means multiplication and sqrt() means square root.

EHT-STF(-112:16:112) = {M}*(1 + j)/sqrt(2)

EHT-STF(0) = 0

EHT-STF for 40 MHz PPDU may be configured based on the following equation. The following example may be a first type (ie, 1x STF) sequence.

EHT-STF(-240:16:240) = {M, 0, -M}*(1 + j)/sqrt(2)

EHT-STF for the 80 MHz PPDU may be configured based on the following equation. The following example may be a first type (ie, 1x STF) sequence.

EHT-STF(-496:16:496) = (M, 1, -M, 0, -M, 1, -M}*(1 + j)/sqrt(2)

The EHT-STF for 160 MHz PPDU may be configured based on the following equation. The following example may be a first type (ie, 1x STF) sequence.

EHT-STF(-1008:16:1008) = (M, 1, -M, 0, -M, 1, -M, 0, -M, -1, M, 0, -M, 1, -M} *(1 + j)/sqrt(2)

The sequence for the lower 80 MHz of the EHT-STF for the 80+80 MHz PPDU may be the same as in Equation 4. A sequence for an upper 80 MHz among EHT-STFs for an 80+80 MHz PPDU may be configured based on the following equation.

EHT-STF(-496:16:496) = {-M, -1, M, 0, -M, 1, -M}*(1 + j)/sqrt(2)

Equations 7 to 11 below relate to an example of a second type (ie, 2x STF) sequence.

EHT-STF(-120:8:120) = (M, 0, -M}*(1 + j)/sqrt(2)

EHT-STF for 40 MHz PPDU may be configured based on the following equation.

EHT-STF(-248:8:248) = (M, -1, -M, 0, M, -1, M}*(1 + j)/sqrt(2)

EHT-STF(-248) = 0

EHT-STF(248) = 0

EHT-STF for the 80 MHz PPDU may be configured based on the following equation.

EHT-STF(-504:8:504) = (M, -1, M, -1, -M, -1, M, 0, -M, 1, M, 1, -M, 1, -M} *(1 + j)/sqrt(2)

The EHT-STF for 160 MHz PPDU may be configured based on the following equation.

EHT-STF(-1016:16:1016) = (M, -1, M, -1, -M, -1, M, 0, -M, 1, M, 1, -M, 1, -M, 0, -M, 1, -M, 1, M, 1, -M, 0, -M, 1, M, 1, -M, 1, -M}*(1 + j)/sqrt(2)

EHT-STF(-8)=0, EHT-STF(8)=0,

EHT-STF(-1016)=0, EHT-STF(1016)=0

The sequence for the lower 80 MHz of the EHT-STF for the 80+80 MHz PPDU may be the same as in Equation 9. A sequence for an upper 80 MHz among EHT-STFs for an 80+80 MHz PPDU may be configured based on the following equation.

EHT-STF(-504:8:504) = {-M, 1, -M, 1, M, 1, -M, 0, -M, 1, M, 1, -M, 1, -M}* (1 + j)/sqrt(2)

EHT-STF(-504)=0,

EHT-STF(504)=0

The EHT-LTF may have first, second, and third types (ie, 1x, 2x, 4x LTF). For example, the first/second/third type LTF may be generated based on an LTF sequence in which a non-zero coefficient is arranged at 4/2/1 subcarrier intervals. The first/second/third type LTF may have a time length of 3.2/6.4/12.8 μs. In addition, GIs of various lengths (eg, 0.8/1/6/3.2 μs) may be applied to the first/second/third type LTF.

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

The PPDU of FIG. 18 (ie, EHT-PPDU) may be configured based on the examples of FIGS. 5 and 6.

For example, an EHT PPDU transmitted on a 20 MHz band, that is, a 20 MHz EHT PPDU may be configured based on the RU of FIG. 5. That is, the location of the EHT-STF, EHT-LTF, and RU of the data field included in the EHT PPDU may be determined as shown in FIG. 5.

The EHT PPDU transmitted on the 40 MHz band, that is, the 40 MHz EHT PPDU may be configured based on the RU of FIG. 6. That is, the location of the EHT-STF, EHT-LTF, and RU of the data field included in the EHT PPDU may be determined as shown in FIG. 6.

Since the RU position of FIG. 6 corresponds to 40 MHz, if the pattern of FIG. 6 is repeated twice, a tone-plan for 80 MHz may be determined. That is, the 80 MHz EHT PPDU may be transmitted based on a new tone-plan in which the RU of FIG. 6 is repeated twice, not the RU of FIG. 7.

When the pattern of FIG. 6 is repeated twice, 23 tones (ie, 11 guard tones + 12 guard tones) may be configured in the DC region. That is, a tone-plan for an 80 MHz EHT PPDU allocated based on OFDMA may have 23 DC tones. In contrast, the 80 MHz EHT PPDU (i.e., non-OFDMA full bandwidth 80 MHz PPDU) allocated on the basis of Non-OFDMA is configured based on 996 RU and consists of 5 DC tones, 12 left guard tones, and 11 right guard tones. It may include.

The tone-plan for 160/240/320 MHz may be configured in a form of repeating the pattern of FIG. 6 several times.

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

The receiving STA may determine the type of the received PPDU as the EHT PPDU based on the following items. For example, 1) the first symbol after the L-LTF signal of the received PPDU is BPSK, 2) RL-SIG where the L-SIG of the received PPDU is repeated is detected, and 3) the length of the L-SIG of the received PPDU When the result of applying'modulo 3'to the value of the field is detected as '0', the received PPDU may be determined as an EHT PPDU. When the received PPDU is determined to be an EHT PPDU, the receiving STA is the type of the EHT PPDU (e.g., SU/MU/Trigger-based/Extended Range type) based on bit information included in the symbol after RL-SIG of FIG. ) Can be detected. In other words, the receiving STA is 1) the first symbol after the L-LTF signal, which is BSPK, 2) RL-SIG that is consecutive to the L-SIG field and is the same as L-SIG, and 3) the result of applying'modulo 3'is' L-SIG including a Length field set to 0', and 4) a received PPDU based on the 3-bit PHY version identifier (eg, PHY version identifier having a first value) of the above-described U-SIG. It can be judged as an EHT PPDU.

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

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

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

Each of the devices/STAs of sub-drawings (a)/(b) of FIG. 1 may be modified as shown in FIG. The transceiver 630 of FIG. 19 may be the same as the

transceivers

113 and 123 of FIG. 1. The transceiver 630 of FIG. 19 may include a receiver and a transmitter.

The processor 610 of FIG. 19 may be the same as the

processors

111 and 121 of FIG. 1. Alternatively, the processor 610 of FIG. 19 may be the same as the

processing chips

114 and 124 of FIG. 1.

The memory 150 of FIG. 19 may be the same as the

memories

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

memories

112 and 122 of FIG. 1.

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

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

The STA, the receiving end, and the transmitting end described below may be the devices of FIGS. 1 and/or 19, and the PPDU may be the PPDU of FIG. 18. The STA may be an AP or a non-AP STA. An STA (eg, an AP or a non-AP STA) described below may be an STA supporting multi-link (eg, an AP multi-link device (MLD) or a non-AP STA MLD).

Hybrid automatic repeat request (HARQ) is a method of using a forward error correcting (FEC) technique and an automatic error request (ARQ) technique together. Unlike a general automatic repeat request (ARQ), HARQ may additionally transmit information related to an FEC code capable of detecting an error. The receiving terminal may attempt error recovery through the FEC code, and if error recovery fails, it may request retransmission to the transmitting terminal through ARQ. HARQ is used in standards such as high-speed downlink packet access (HSDPA), IEEE802.16e, and long term evolution (LTE), but HARQ has not been used in a contention-based wireless local area network (WLAN) environment. .

Introduction of HARQ is being considered in EHT (extreme high throughput), a standard discussed after IEEE802.11ax. When HARQ is introduced, coverage can be expanded in a low signal-to-noise ratio (SNR) environment, that is, in an environment where the distance between the transmitting terminal and the receiving terminal is far, higher throughput can be obtained in a high SNR environment. I can.

Upon receiving the HARQ retransmitted frame, the receiving terminal may perform decoding by combining the previously received original frame and the retransmitted frame. Here, it may be necessary to discuss the unit for retransmission. HARQ retransmission may be performed in units of codewords at the PHY level, or HARQ retransmissions may be performed in units of MPDUs at the MAC level.

Hereinafter, a hybrid automatic repeat request (HARQ) technique applied to an example of the present specification will be described. The terminal described below may be the device of FIG. 1 and/or FIG. 19, and the PPDU may be the PPDU of FIG. 18. The terminal may be an AP or a non-AP STA.

The HARQ technique is a technique that combines a forward error correction (FEC) scheme and an automatic repeat request (ARQ) scheme. According to the HARQ scheme, it is checked whether the data received by the physical layer contains an error that cannot be decoded, and if an error occurs, performance is improved by requesting retransmission.

The HARQ-based receiver basically attempts error correction for received data and determines whether to retransmit using an error detection code. The error detection code may be various codes. For example, in the case of using a cyclic redundancy check (CRC), when an error of received data is detected through a CRC detection process, the receiver transmits a non-acknowledgement (NACK) signal to the transmitter. Upon receiving the NACK signal, the transmitter transmits appropriate retransmission data according to the HARQ mode. A receiver receiving retransmission data improves reception performance by combining and decoding previous data and retransmission data.

The HARQ mode can be classified into Chase combining and IR (incremental redundancy). Chase combining is a method of obtaining a signal-to-noise ratio (SNR) gain by combining data with retransmitted data without discarding the error-detected data. IR is a method of obtaining a coding gain by incrementally transmitting additional redundant information to retransmitted data.

21 is a diagram showing an example of an incremental redundancy (IR) method. In the IR (incremental redundancy) scheme, the coded bits that are initially transmitted and retransmitted afterwards may be different as follows. Accordingly, when the IR scheme is used, the STA performing retransmission generally transmits the IR version (or packet version/retransmission version) to the receiving STA. In the following figure, an example in which the transmitting STA performs retransmission in the order of IR version 1, IR Version 2, IR Version 3, and IR Version 1. The receiving STA may combine and decode the received packet/signal.

HARQ can have an effect of increasing coverage in a low SNR environment (eg, an environment in which the distance between the transmitting terminal and the receiving terminal is far). HARQ can have an effect of increasing throughput in a high SNR environment.

In order to perform HARQ, it is necessary to inform the transmitting terminal of a response (ie, acknowledgment (ACK) or negative acknowledgment (NACK)) to data received by the receiving terminal. When receiving a response (eg, a block ack (BA) frame, etc.) to a plurality of HARQ units (eg, A-MPDU (aggregated-MPDU) including a plurality of MPDUs (MAC protocol data units)) , The transmitting terminal can regard an MPDU that is not included in the BA (block ACK) bitmap as NACK, and the transmitting terminal performs various operations (e.g., HARQ incremental redundancy (IR)) based on this. can do. However, when the receiving terminal successfully decodes the PHY header but fails to decode a single-MPDU (S-MPDU), or fails to decode all of a plurality of HARQ units (eg, MPDU) due to an error, In the existing environment, the receiving terminal cannot transmit feedback on this. Accordingly, the transmitting terminal cannot distinguish whether the transmitted PPDU has a collision or a reception failure due to a channel error. That is, the transmitting terminal does not know whether decoding of the PHY header has succeeded in the receiving terminal, but has failed to decode only the data or whether decoding of both the PHY header and data has failed.

Hereinafter, a NACK frame that can be used in HARQ operation is defined. Through this, the transmitting terminal can know whether there is a collision of transmitted data. Collision may mean a case in which the receiving terminal fails to decode both the PHY header and data of the received signal.

When the reception terminal fails to decode the PHY header of the reception signal, the reception terminal may not store the data of the reception signal in the buffer. That is, if the receiving terminal fails to decode the PHY header of the received signal (eg, the first signal), the retransmitted signal (eg, the second signal) and the received signal (eg, the first signal) Combining may not be performed. When decoding of the PHY header of the received signal fails, the receiving terminal may determine that it will be difficult to use data of the received signal. Relatively, since the PHY header is transmitted at a slower rate than the data, it is less likely to fail to decode compared to the data. Therefore, when decoding of the PHY header fails, data included in the same signal may not be stored in a buffer for HARQ combining.

Meanwhile, when decoding of the PHY header of the received signal is successful, but only decoding of the data of the received signal fails, the receiving terminal may store the data of the received signal in a buffer for the HARQ operation. The receiving terminal may combine the data of the received signal stored in the buffer and the retransmitted data. In HARQ combining, both a chase combining (CC) technique and an incremental redundacy (IR) technique may be used. Alternatively, a separate HARQ operation may be performed based on the NACK signal.

If the PHY header is successfully decoded, but fails to decode S-MPDU (single-MPDU), or fails to decode all MPDUs in aggregated-MPDU (A-MPDU), the receiving terminal has failed to decode the MAC header. It is not possible to directly find out the address (transmitter address, TA) of the sending terminal. However, the receiving terminal may estimate whether it is a PPDU transmitted from an access point (AP) associated with it based on the UL/DL (uplink/downlink) field and the BSS Color field included in the PHY header. Or, for example, information for HARQ operation (eg, TXID (transmitter identifier), BSS (basic service set) color, Short BSSID, RXID (receiver identifier)), STA ID, AID (association identifier), New Data If /ReTx indicator (initial transmission/retransmission indicator), etc.) is included in the PHY header of the PPDU, the receiving terminal can know whether the PPDU and/or HARQ unit (eg, MPDU) is a signal transmitted to the corresponding terminal. .

HARQ is a method of using a forward error-correcting (FEC) technique and an automatic error request (ARQ) technique together. Unlike general ARQ, an FEC code capable of detecting an error may be included in the information. When receiving a signal, the receiver first attempts error recovery, and if the recovery fails, it may request retransmission to the transmitter through ARQ. Although HARQ is already used in standards such as high-speed downlink packet access (HSDPA), IEEE 802.16e, and long-term evolution (LTE), it has not been used in a contention-based WLAN environment.

Introduction of HARQ is being considered in Extreme high throughput (EHT), a standard discussed after IEEE 802.11ax. If HARQ is introduced, coverage can be expanded in a low SNR environment, that is, in an environment where the distance between the transmitting end and the receiving end is long, and in a high SNR environment, higher throughput can be exhibited.

HARQ combining may be performed by LLR combining at the PHY layer, but may be divided into PHY-level HARQ and MAC-level HARQ according to a retransmission unit and a layer responsible for retransmission. Since PHY-level HARQ operates separately from the MAC procedure, it must be designed to coexist with the existing MAC automatic repeat-request (ARQ).

Specifically, in an environment in which only the existing MAC ARQ is operated, when transmission is successfully performed or only some MPDUs have been successfully received, the receiving end may transmit an ACK frame or a Block Ack frame to notify. When decoding of all MPDUs fails or collision occurs, the receiving end may not transmit an ACK frame or Block Ack frame, and the transmitting end can know that decoding of all MPDUs has failed or a collision has occurred through the waiting of the SIFS interval. have. However, if the PHY-level HARQ retransmission process is in progress, the transmitter/receiver MAC cannot know whether HARQ retransmission is occurring. Therefore, there is no choice but to use the Delayed ACK policy, which can degrade the overall MAC efficiency.

According to the current MAC acknowledgment procedure, the response method after PPDU is divided into 1) immediate ACK and 2) delayed (no immediate) ACK. In the case of Immediate ACK, the transmitter can receive the ACK/BlockAck after SIFS after transmitting the PPDU. In the case of delayed ACK, if the transmitting end transmits the PPDU and then retransmits the BlockAck request (BAR), the ACK/BlockAck can be received after SIFS.

On the Tx side, the immediate ACK policy cannot be used due to the HARQ retransmission process in the PHY-side. On the other hand, in the case of the delayed ACK policy, it is difficult for the Tx MAC to determine when to transmit the BAR frame, and there is a disadvantage in that additional overhead is generated due to the BAR frame. Therefore, it is necessary to modify the existing ACK policy to be suitable for HARQ or to introduce a new ACK policy suitable for HARQ.

Hereinafter, a MAC-level ACK policy capable of improving MAC efficiency in PHY-level retransmission HARQ will be described.

In the following specification, a HARQ burst is proposed as an example of a HARQ unit, but if it is made of PHY-level retransmission, a HARQ PPDU may be configured in various units other than the HARQ burst. That is, in the present specification, a codeword, a multiple of codewords (i.e., a plurality of codewords), or an arbitrary block may be used as a HARQ retransmission unit, but for convenience of description below, some examples include HARQ bursts. Explained as a basis.

Ack policy may be indicated through the MAC header in the MAC frame as shown in FIG. 22. The example below is an example of one of the possible methods, and may be defined with different fields or different bit values.

Referring to FIG. 22, the HARQ ACK policy may be determined as HARQ Responsive ACK or HARQ Delayed ACK. For example, the HARQ ACK policy may be included in the Ack Policy Indicator subfield included in the QoS control field in the MAC header. However, this is only an embodiment, and a field including HARQ ACK policy information is not limited thereto.

While the PHY-level HARQ retransmission process is in progress, it is not known whether PHY level HARQ retransmission is being performed at the MAC-level. Accordingly, an attempt to retransmit MPDUs from the MAC of the transmitter may occur. In order to prevent HARQ retransmission at the MAC level while PHY level HARQ retransmission is performed, the SIFS Timeout reset function should be supported. For example, the MAC of the transmitting end may perform retransmission if an ACK or BA frame is not received within a predetermined time. Therefore, it is necessary to reset the retransmission timer that records a certain time. A special field indication for resetting the retransmission timer is not required, and the PHY of the transmitter may inform the MAC of the transmitter through the internal operation of the device.

In the conventional operation, when the transmitting end does not receive a response frame (eg, ACK, BlockAck frame) during SIFS after transmitting the packet, it is regarded as transmission failure and retransmits the packet. However, when PHY-level HARQ retransmission is performed, the transmitting end cannot receive a response frame in SIFS. Accordingly, in order to prevent the MAC of the transmitting end from performing retransmission while the PHY level HARQ retransmission is performed, a method of informing the duration of the retransmission packet to the MAC of the transmitting end may be needed when the PHY of the transmitting end starts PHY level retransmission.

Hereinafter, the HARQ feedback frame (HARQ F/B) may be a PHY signal generated and received at the PHY level, and the BA frame may be a MAC signal generated and received at the MAC level.

One. HARQ Delayed ACK

Referring to FIG.23, when the receiving end MAC is the HARQ delayed ACK policy, similar to the existing BlockAck policy, when the transmission process is finished (i.e., after successfully receiving a signal at the PHY level of the receiving end, the receiving end MAC receives data from the receiving end PHY. In case) transmission status can be recorded. The receiving end MAC does not perform an operation such as transmitting an ACK/BA frame, and may expect a BlockAckReq (BAR) frame or an MPDU including a subsequent implicit block ack request or HARQ delayed ack policy. For example, the receiving end may then receive the BAR frame and transmit the BA frame.

The timeout value defined in HARQ delayed ACK may be a sum of the transmission time of the PPDU and the SIFS. Alternatively, the value included in the ADDBA request frame, which was supported by the existing 802.11, can be used, or a separately negotiated or implicitly defined value can be used. When the timeout value expires, the transmitter considers that the signal has not been received at the receiver, and may perform retransmission. That is, the timeout is a MAC retransmission timer, and since the MAC level retransmission is performed when the timeout value expires, it is necessary to update the timeout value while the PHY level retransmission is performed.

Since the MAC address is not included in the PHY HARQ feedback frame, the timeout value cannot be updated at the transmitting MAC side. For this purpose, information for HARQ transmission (eg, TXID (eg, BSS Color, Short BSSID, etc.), RXID (eg, STA_ID, AID, etc.), New Data/ReTx indicator, etc.) is a PHY header (eg. , EHT SIG, HARQ-SIG, etc.), and the receiving terminal can know whether the corresponding PPDU/corresponding HARQ Unit is transmitted to the corresponding terminal.

24 is a diagram illustrating an embodiment of a method of operating HARQ.

24 is an embodiment of an operation procedure of HARQ delayed ACK when initial transmission is successful. The receiving end PHY may check whether the received PPDU has an error, and when determining that all HARQ PHY units have been normally received, this may be notified to the receiving end MAC. That is, the PHY of the receiving end may transmit information that the PPDU has been received without error to the MAC of the receiving end. Similar to the case where the existing BlockAck policy is applied, the receiving-end MAC can transmit a BlockAck or a frame corresponding thereto when a BAR or implicit BAR frame is received from the transmitting-end MAC while storing whether or not transmission is successful.

25 is a diagram illustrating an embodiment of a method of operating HARQ.

Referring to FIG. 25, when decoding of some of the HARQ PHY units in the receiving PHY fails, the receiving PHY may request retransmission through the HARQ feedback frame. That is, the receiving end PHY may transmit a HARQ feedback frame including information on HARQ PHY units for which decoding has failed. Upon receiving the HARQ feedback frame, the transmitter PHY causes the transmitter MAC to update the timeout value and performs HARQ retransmission based on the received HARQ feedback frame. That is, the transmitting end may update the retransmission timer based on the HARQ feedback frame, and may perform PHY layer retransmission based on the HARQ feedback frame.

Thereafter, the transmitting end PHY may perform retransmission, and the receiving end may receive the retransmission PPDU. The PHY of the receiving end can check the error of the retransmitted PPDU, and if there is no error, it can transmit the data to the MAC of the receiving end. The receiving end PHY may transmit a HARQ feedback frame. The transmitter may transmit a BAR frame based on the HARQ feedback frame. The receiving end can receive the BAR frame and can transmit the BA frame.

26 is a diagram illustrating an embodiment of a method of operating HARQ.

Referring to FIG. 26, even in a situation in which HARQ retransmission can be attempted because all MPDUs have not been successfully transmitted, MAC BlockAck may be transmitted due to TXOP limit or max retransmission counter limitation. In this case, the receiving end MAC may inform the transmitting end of the MPDU that has not been successfully received by using the bitmap field inside the BlockAck (or HARQ feedback frame), and the transmitting end can transmit data again based on the bitmap of the BA frame when transmission is possible. Can be transmitted.

27 is a diagram illustrating an embodiment of a method of operating HARQ.

Referring to FIG. 27, it can be seen how the timeout value is used. If the receiving end cannot decode the PHY header, it cannot request HARQ retransmission. When the transmitting-end MAC receives the HARQ feedback frame from the receiving-end PHY (i.e., the transmitting-end PHY delivers the HARQ feedback frame information received from the receiving-end PHY to the transmitting-end MAC), or when it receives the BlockAck from the receiving-end MAC, it updates the timeout value. Otherwise, the A-MPDU can be retransmitted after the timeout expires.

28 is a diagram illustrating an embodiment of a method of operating HARQ.

28 is another embodiment that can be taken when the timeout has expired (ie, the retransmission timer has expired). When the timeout expires, the transmitting end MAC may transmit a block ack request (BAR) without retransmitting the MPDU. If the A-MPDU transmission is successful, but the Block Ack frame is not properly transmitted, if the BAR is transmitted by the transmitting end MAC, unnecessary transmission can be omitted, thereby increasing throughput. However, if HARQ retransmission is required because an error occurs in the previous transmission, the throughput may decrease due to additional BAR and BA frame transmission.

2. HARQ responsive ACK

29 is a diagram illustrating an embodiment of a method of operating HARQ.

Referring to FIG. 29, in the case of the HARQ responsive ACK policy, the receiving end MAC may respond with an Ack or BlockAck frame immediately after the transmission process is finished, similar to the conventional Normal ACK or Implicit BAR Ack policy. For example, when a signal is successfully received at the receiver PHY level and the receiver MAC receives data from the receiver PHY, the receiver may immediately transmit an Ack or BlockAck frame.

30 and 31 are diagrams illustrating an embodiment of a method of operating HARQ.

30 and 31 are examples of an operation procedure of HARQ responsive ACK when initial transmission is successful. The receiving end PHY may check whether the received PPDU has an error, and when determining that all HARQ PHY units have been normally received, this may be notified to the receiving end MAC. For example, the receiving end PHY may transmit information indicating that all HARQ PHY units have been normally received to the receiving end MAC.

For example, as shown in FIG. 30, a receiving end PHY may transmit a HARQ feedback frame including information that all HARQ PHY units have been normally received, and a receiving end MAC may transmit a BA frame.

For example, as shown in FIG. 31, the receiving end may directly transmit the BA frame without transmitting the HARQ feedback frame.

As for the response method of the receiving end, a method of transmitting both HARQ Feedback or HARQ Feedback and BlockAck frame at the PHY-level is also possible.

32 is a diagram illustrating an embodiment of a method of operating HARQ.

Referring to FIG. 32, when decoding of some of the HARQ PHY units in the receiving PHY fails, the receiving PHY may request retransmission through the HARQ feedback frame. That is, the receiving end PHY may transmit a HARQ feedback frame including information on HARQ PHY units for which decoding has failed. Upon receiving the HARQ feedback frame, the transmitter PHY causes the transmitter MAC to update the timeout value and performs HARQ retransmission based on the received HARQ feedback frame. That is, the transmitting end may update the retransmission timer based on the HARQ feedback frame, and may perform PHY layer retransmission based on the HARQ feedback frame.

Thereafter, the receiving end can transmit the BA frame if data transmission is successful.

33 is a diagram illustrating an embodiment of a method of operating HARQ.

Referring to FIG. 33, even in a situation in which HARQ retransmission can be attempted because all MPDUs are not successfully transmitted, there may be a case in which MAC BlockAck needs to be transmitted due to TXOP limit or max retransmission counter limitation. In this case, the receiving end MAC may inform the transmitting end of the MPDU that has not been successfully received using a bitmap field inside the BlockAck, and the transmitting end may transmit data again based on the bitmap of the BA frame when transmission is possible.

34 is a diagram illustrating an embodiment of a method of operating HARQ.

Referring to FIG. 34, it can be seen how the timeout value is used. If the receiving end cannot decode the PHY header, it cannot request HARQ retransmission. When the transmitting-end MAC receives the HARQ feedback frame from the receiving-end PHY (i.e., the transmitting-end PHY delivers the HARQ feedback frame information received from the receiving-end PHY to the transmitting-end MAC), or when it receives the BlockAck from the receiving-end MAC, it updates the timeout value. Otherwise, the A-MPDU can be retransmitted after the timeout expires.

35 is a diagram illustrating an embodiment of a method of operating HARQ.

Referring to FIG. 35, this is another embodiment that can be taken when timeout has expired (that is, when the retransmission timer has expired). When the timeout expires, the transmitting end MAC may transmit a block ack request (BAR) without retransmitting the MPDU. If the A-MPDU transmission is successful, but the Block Ack frame is not properly transmitted, if the BAR is transmitted by the transmitting end MAC, unnecessary transmission can be omitted, thereby increasing throughput. However, if HARQ retransmission is required because an error occurs in the previous transmission, the throughput may decrease due to additional BAR and BA frame transmission.

Referring to FIG. 36, the transmitting STA may perform association with the receiving STA (S3610). For example, if the transmitting STA is a non-AP STA, an association process may be performed with an AP, and if the transmitting STA is an AP, an association process may be performed with the non-AP STA. Block Ack policy of subsequent transmission can be negotiated through ADDBA request/response or information exchange corresponding thereto.

When the transmitting STA receives data to be transmitted (eg, TCP/IP PDU, etc.) from the upper layer, the MAC-layer constructs an MPDU with this data. The QoS Control field or a field corresponding thereto may include an Ack Policy. The transmitting STA may generate a PPDU by combining a PHY header with an MPDU or multiple A-MPDUs (MPDUs) at the PHY-level.

The transmitting station (STA) may transmit a physical protocol data unit (PPDU) (S3620). The transmitting STA may store the PPDU transmitted to the buffer for each HARQ PHY unit (eg, codeword).

The transmitting STA may receive the feedback frame (S3630). When the transmitting STA receives feedback indicating that the receiving STA has normally received the MPDU, if there is data transmitted from the upper layer, the transmitting STA may prepare for the next transmission. For example, the receiving end PHY may check whether the received PPDU has an error, and when it is determined that all HARQ PHY units have been normally received, this may be notified to the receiving end MAC. That is, the PHY of the receiving end may transmit information that the PPDU has been received without error to the MAC of the receiving end. Similar to the case where the existing BlockAck policy is applied, the receiving-end MAC can transmit a BlockAck or a frame corresponding thereto when a BAR or implicit BAR frame is received from the transmitting-end MAC while storing whether or not transmission is successful.

When the transmitting STA receives the NACK frame, that is, feedback indicating that normal reception has not been performed, the stored codeword may be retransmitted based on the feedback information. When HARQ is applied, the transmitting STA may have to wait for a predetermined timeout period even if it does not receive a response from the MAC of the transmitting STA in SIFS regardless of the ack policy. For example, when decoding of some HARQ PHY units in the receiving PHY fails, the receiving PHY may request retransmission through the HARQ feedback frame. That is, the receiving end PHY may transmit a HARQ feedback frame including information on HARQ PHY units for which decoding has failed. Upon receiving the HARQ feedback frame, the transmitter PHY causes the transmitter MAC to update the timeout value and performs HARQ retransmission based on the received HARQ feedback frame.

That is, the transmitting end may update the retransmission timer based on the HARQ feedback frame (S3640), and may perform PHY layer retransmission based on the HARQ feedback frame (S3650).

The transmitting end PHY may perform retransmission, and the receiving end may receive the retransmission PPDU. The PHY of the receiving end can check the error of the retransmitted PPDU, and if there is no error, it can transmit the data to the MAC of the receiving end. The receiving end PHY may transmit the HARQ feedback frame, and the transmitting end PHY may receive the HARQ feedback frame (S3660). The transmitter may transmit a BAR frame based on the HARQ feedback frame (S3670). The receiving end can receive the BAR frame and can transmit the BA frame. The transmitter may receive the BA frame (S3680).

Referring to FIG. 37, the receiving STA may perform association with the transmitting STA (S3710). For example, if the transmitting STA is a non-AP STA, an association process may be performed with an AP, and if the transmitting STA is an AP, an association process may be performed with the non-AP STA. Block Ack policy of subsequent transmission can be negotiated through ADDBA request/response or information exchange corresponding thereto.

The receiving station (STA) may receive a physical protocol data unit (PPDU) (S3720). The transmitting STA may store the PPDU transmitted to the buffer for each HARQ PHY unit (eg, codeword).

The receiving STA may transmit a feedback frame (S3730). When the transmitting STA receives feedback indicating that the receiving STA has normally received the MPDU, if there is data transmitted from the upper layer, the transmitting STA may prepare for the next transmission. For example, the receiving end PHY may check whether the received PPDU has an error, and when it is determined that all HARQ PHY units have been normally received, this may be notified to the receiving end MAC. That is, the PHY of the receiving end may transmit information that the PPDU has been received without error to the MAC of the receiving end. Similar to the case where the existing BlockAck policy is applied, the receiving-end MAC can transmit a BlockAck or a frame corresponding thereto when a BAR or implicit BAR frame is received from the transmitting-end MAC while storing whether or not transmission is successful.

That is, the transmitting end may update the retransmission timer based on the HARQ feedback frame, and may perform PHY layer retransmission based on the HARQ feedback frame.

The receiving STA may receive retransmission from the transmitting STA (S3740). The transmitting end PHY may perform retransmission, and the receiving end may receive the retransmission PPDU. The PHY of the receiving end can check the error of the retransmitted PPDU, and if there is no error, it can transmit the data to the MAC of the receiving end. The receiving end PHY may transmit a HARQ feedback frame (S3750). The transmitter may transmit a BAR frame based on the HARQ feedback frame, and the receiver may receive the BAR frame (S3760). The receiving end may transmit a BA frame (S3770).

Some of the detailed steps shown in the examples of FIGS. 36 and 37 may be omitted. For example, steps S3610, S3660, S3670, and S3680 may be omitted. In addition to the steps shown in FIGS. 36 and 37, other steps may be added, and the order of the steps may be different. Some of the above steps may have their own technical meaning.

Referring to FIG. 38, the MAC layer of a transmitting STA may transmit an A-MPDU (S3810). For example, the MAC layer of the transmitting STA may deliver the A-MPDU to the PHY layer.

The MAC layer of the transmitting STA may wait for ACK/BA until the timeout value (S3820).

When the MAC layer of the transmitting STA receives information related to PHY feedback reception from the PHY layer of the transmitting STA, it may update the timeout value (S3830). For example, when the MAC layer of the transmitting STA receives information related to PHY feedback reception from the PHY layer of the transmitting STA, it can know that PHY level HARQ retransmission is being performed, and thus, the timeout value for MAC retransmission can be updated. have.

If the MAC layer of the transmitting STA does not receive the ACK/BA within the timeout value, it may retransmit the A-MPDU or transmit the BAR frame (S3840).

When the MAC layer of the transmitting STA receives the ACK/BA within the timeout value, the receiving STA may retransmit a signal in which reception has failed based on the ACK/BA frame (S3850).

The MAC layer of the transmitting STA may transmit the next packet if there is no signal that the receiving STA has failed to receive based on the received ACK/BA (S3860).

Referring to FIG. 39, the MAC layer of the receiving STA may wait for A-MPDU reception (S3910).

When the MAC layer of the receiving STA receives the A-MPDU from the PHY layer of the receiving STA, it may decode the A-MPDU and transmit an ACK/BA frame for the A-MPDU (S3920).

The technical features of the present specification described above can be applied to various devices and methods. For example, the technical features of the present specification described above may be performed/supported through the apparatus of FIGS. 1 and/or 19. For example, the technical features of the present specification described above may be applied only to a part of FIGS. 1 and/or 19. For example, the technical features of the present specification described above may be implemented based on the

processing chips

114 and 124 of FIG. 1, or implemented based on the

processors

111 and 121 and the

memories

112 and 122 of FIG. 1. , May be implemented based on the processor 610 and the memory 620 of FIG. 19. For example, an apparatus of the present specification includes a memory and a processor operatively coupled to the memory, the processor transmitting a physical protocol data unit (PPDU); Receive a first feedback frame for the PPDU; Updating a retransmission timer based on the first feedback frame; And it is set to perform physical (PHY) layer retransmission based on the first feedback frame, the first feedback frame is a PHY layer signal, and the retransmission timer may be a timer related to media access control (MAC) layer retransmission. .

Technical features of the present specification may be implemented based on a computer readable medium (CRM). For example, the CRM proposed by the present specification includes at least an instruction based on being executed by at least one processor of an STA (station) of a wireless local area network (LAN) system. In a computer readable medium, the method comprising: transmitting a physical protocol data unit (PPDU); Receiving a first feedback frame for the PPDU; Updating a retransmission timer based on the first feedback frame; And performing physical (PHY) layer retransmission based on the first feedback frame, wherein the first feedback frame is a PHY layer signal, and the retransmission timer is a timer related to media access control (MAC) layer retransmission. , It is possible to store instructions for performing an operation. Instructions stored in the CRM of the present specification may be executed by at least one processor. At least one processor related to the CRM of the present specification may be the

processors

111 and 121 or the

processing chips

114 and 124 of FIG. 1, or the processor 610 of FIG. 19. Meanwhile, the CRM of the present specification may be the

memories

112 and 122 of FIG. 1, the memory 620 of FIG. 19, or a separate external memory/storage medium/disk.

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

Artificial intelligence refers to the field of researching artificial intelligence or the methodology that can create it, and machine learning (Machine Learning) refers to the field of studying methodologies to define and solve various problems dealt with in the field of artificial intelligence do. Machine learning is also defined as an algorithm that improves the performance of a task through continuous experience.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Claims

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

Transmitting, by a transmitting station, a physical protocol data unit (PPDU);

Receiving, by the transmitting STA, a first feedback frame for the PPDU;

Updating, by the transmitting STA, a retransmission timer based on the first feedback frame; And

The transmitting STA includes performing physical (PHY) layer retransmission based on the first feedback frame,

The first feedback frame is a PHY layer signal,

The retransmission timer is a timer related to media access control (MAC) layer retransmission,

Way.
The method according to claim 1,

When the retransmission timer expires,

The transmitting STA performs MAC layer retransmission,

Way.
The method according to claim 1,

The transmitting STA retransmits a transmission failure PHY layer retransmission unit among at least one PHY layer retransmission unit based on the first feedback frame,

Way.
The method according to claim 1,

The transmitting STA receives a second feedback frame for the retransmitted PPDU,

The second feedback frame is a PHY layer signal,

The second feedback frame including information that the receiving STA has successfully received the retransmitted PPDU; And

The transmitting STA further comprises transmitting a block acknowledgment request (BAR) frame,

Way.
The method of claim 4,

The transmitting STA further comprises receiving a block acknowledgment (BA) frame from the receiving STA,

The BA frame is a MAC layer signal,

Way.
The method according to claim 1,

The transmitting STA further comprises receiving a block acknowledgment (BA) frame from the receiving STA,

The BA frame is a MAC layer signal,

Way.
The method according to claim 1,

The first feedback frame is generated based on whether reception is successful in the PHY layer of the receiving STA,

Way.
The method according to claim 1,

The first feedback frame includes information related to whether or not reception is successful in units of codewords,

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

A transceiver for transmitting and receiving a radio signal; And

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

Transmits a physical protocol data unit (PPDU);

Receive a first feedback frame for the PPDU;

Updating a retransmission timer based on the first feedback frame; And

It is set to perform physical (PHY) layer retransmission based on the first feedback frame,

The first feedback frame is a PHY layer signal,

The retransmission timer is a timer related to media access control (MAC) layer retransmission,

Sending STA.
The method of claim 9,

When the retransmission timer expires,

The processor is configured to perform MAC layer retransmission,

Sending STA.
The method of claim 9,

The processor retransmits a transmission failure PHY layer retransmission unit among at least one PHY layer retransmission unit based on the first feedback frame,

Sending STA.
The method of claim 9,

The processor,

Receiving a second feedback frame for the retransmitted PPDU,

The second feedback frame is a PHY layer signal,

The second feedback frame includes information that the receiving STA has successfully received the retransmitted PPDU; And

Configured to transmit a block acknowledgment request (BAR) frame,

Sending STA.
The method of claim 12,

The processor is configured to receive a block acknowledgment (BA) frame from the receiving STA,

The BA frame is a MAC layer signal,

Sending STA.
The method of claim 9,

The processor is configured to receive a block acknowledgment (BA) frame from a receiving STA,

The BA frame is a MAC layer signal,

Sending STA.
The method of claim 9,

The first feedback frame is generated based on whether reception is successful in the PHY layer of the receiving STA,

Sending STA.
The method of claim 9,

The first feedback frame includes information related to whether or not reception is successful in units of codewords,

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

Receiving, by a receiving STA (station), a physical protocol data unit (PPDU);

Checking, by the receiving STA, an error of the PPDU in a physical (PHY) layer;

Transmitting, by the receiving STA, a feedback frame for the PPDU based on the error check; And

Including the step of the receiving STA, receiving a PHY layer retransmission,

The feedback frame is a PHY layer signal,

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

A transceiver for transmitting and receiving a radio signal; And

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

Receive a physical protocol data unit (PPDU);

Checks the error of the PPDU in the PHY (physical) layer;

Transmitting a feedback frame for the PPDU based on the error check; And

Is configured to receive PHY layer retransmissions,

The feedback frame is a PHY layer signal,

Receiving STA.
At least one computer-readable recording medium containing instructions based on execution by at least one processor of a transmitting STA (station) of a wireless local area network (LAN) system. medium),

Transmitting a physical protocol data unit (PPDU);

Receiving a first feedback frame for the PPDU;

Updating a retransmission timer based on the first feedback frame; And

Including the step of performing PHY (physical) layer retransmission based on the first feedback frame,

The first feedback frame is a PHY layer signal,

The retransmission timer performs an operation, which is a timer related to media access control (MAC) layer retransmission,

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

Memory; And

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

Transmits a physical protocol data unit (PPDU);

Receive a first feedback frame for the PPDU;

Updating a retransmission timer based on the first feedback frame; And

It is set to perform physical (PHY) layer retransmission based on the first feedback frame,

The first feedback frame is a PHY layer signal,

The retransmission timer is a timer related to media access control (MAC) layer retransmission,

Device.