Method and apparatus for PPDU transmission and reception in wireless LAN system

Abstract

Disclosed are a method and apparatus for PPDU transmission and reception in a wireless LAN system. The method according to an embodiment of the present disclosure may comprise the steps of: receiving, by the apparatus, a first frame from an AP, wherein the first frame includes information for allocation of a first frequency domain; and transmitting, by the apparatus, a PPDU to the AP on the basis of the first frame.

Description

PPDU transmission and reception method and device in a wireless LAN system

[0001] The present disclosure relates to a method and device for transmitting and receiving a physical protocol data unit (PPDU) in a wireless local area network (WLAN) system.

[0002] New technologies have been introduced for wireless local area networks (WLANs) to improve transmission rates, increase bandwidth, enhance reliability, reduce errors, and reduce latency. Among WLAN technologies, the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series of standards can be referred to as Wi-Fi. For example, recently introduced technologies for WLANs include enhancements for Very High Throughput (VHT) in the 802.11ac standard and enhancements for High Efficiency (HE) in the IEEE 802.11ax standard.

[0003] To provide a more advanced wireless communication environment, improved technologies for Extremely High Throughput (EHT) are being discussed. For example, technologies for Multiple Input Multiple Output (MIMO), which supports increased bandwidth, efficient utilization of multiple bands, and increased spatial streams, and for coordination of multiple access points (APs), are being studied. In particular, various technologies are being studied to support low latency or real-time traffic. Furthermore, new technologies are being discussed to support ultra-high reliability (UHR), including improvements or extensions of EHT technology.

[0004] The technical problem of the present disclosure is to provide a method and device for transmitting and receiving a trigger-based PPDU.

[0005] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0006] A method according to one aspect of the present disclosure may include: receiving, by a device, a first frame from an access point (AP), the first frame including information for allocation of a first frequency range; and transmitting, by the device, a physical protocol data unit (PPDU) to the AP based on the first frame. The PPDU may be transmitted in a second frequency range different from the first frequency range.

[0007] A method according to an additional aspect of the present disclosure may include: transmitting, by an access point (AP), a first frame to a device, the first frame including information for allocation of a first frequency range; and receiving, by the AP, a physical protocol data unit (PPDU) from the device based on the first frame. The PPDU may be transmitted in a second frequency range different from the first frequency range.

[0008] According to the present disclosure, even if some of the frequency resources allocated from trigger frames, etc. are unavailable, trigger-based PPDUs can be transmitted and received through the remaining frequency resources, thereby enabling efficient use of frequency resources.

[0009] In addition, according to the present disclosure, the efficiency of wireless communication can be improved due to efficient use of frequency resources.

[0010] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the description below.

[0011] The accompanying drawings, which are incorporated in and are part of the detailed description to aid in understanding the present disclosure, provide embodiments of the present disclosure and, together with the detailed description, describe the technical features of the present disclosure.

[0012] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0013] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0014] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0015] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0016] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0017] FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0018] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0019] FIG. 8 is a drawing showing an exemplary format of a trigger frame to which the present disclosure can be applied.

[0020] FIG. 9 is a diagram illustrating examples of resource units of a wireless LAN system to which the present disclosure can be applied.

[0021] FIG. 10 is a diagram illustrating examples of resource units of a wireless LAN system to which the present disclosure can be applied.

[0022] FIG. 11 is a diagram illustrating examples of resource units of a wireless LAN system to which the present disclosure can be applied.

[0023] FIG. 12 illustrates a procedure for transmitting and receiving a trigger-based PPDU according to one embodiment of the present disclosure.

[0024] FIG. 13 illustrates a procedure for transmitting and receiving a trigger-based PPDU according to one embodiment of the present disclosure.

[0025] FIG. 14 illustrates the operation of a device for a PPDU transmission and reception method according to one embodiment of the present disclosure.

[0026] FIG. 15 illustrates the operation of an access point for a PPDU transmission and reception method according to one embodiment of the present disclosure.

[0027] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description set forth below, together with the accompanying drawings, is intended to explain exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the present disclosure may be practiced. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, one of ordinary skill in the art will appreciate that the present disclosure may be practiced without these specific details.

[0028] In some cases, to avoid obscuring the concepts of the present disclosure, known structures and devices may be omitted or illustrated in block diagram form focusing on the core functions of each structure and device.

[0029] In the present disclosure, when a component is said to be "connected," "coupled," or "connected" to another component, this may include not only a direct connection but also an indirect connection in which another component exists between them. Furthermore, the terms "comprises" or "has" in the present disclosure specify the presence of the mentioned features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0030] In this disclosure, terms such as "first," "second," etc. are used only to distinguish one component from another, are not used to limit the components, and do not limit the order or importance of components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0031] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and / or" as used herein may refer to any one of the associated enumerated items, or is meant to refer to and encompass any and all possible combinations of two or more of them. Furthermore, the use of " / " between words in this disclosure has the same meaning as "and / or" unless otherwise stated.

[0032] The examples of the present disclosure can be applied to various wireless communication systems. For example, the examples of the present disclosure can be applied to a wireless LAN system. For example, the examples of the present disclosure can be applied to a wireless LAN based on the IEEE 802.11a / g / n / ac / ax / be standards. Furthermore, the examples of the present disclosure can be applied to a wireless LAN based on the newly proposed IEEE 802.11bn (or UHR) standard. Additionally, the examples of the present disclosure can be applied to a wireless LAN based on the next-generation standard after IEEE 802.11bn. Furthermore, the examples of the present disclosure can be applied to a cellular wireless communication system. For example, the examples of the present disclosure can be applied to a cellular wireless communication system based on the LTE (Long Term Evolution) series of technologies and the 5G NR (New Radio) series of technologies of the 3rd Generation Partnership Project (3GPP) standard.

[0033] Below, technical features to which examples of the present disclosure can be applied are described.

[0034] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0035] The first device (100) and the second device (200) illustrated in FIG. 1 may be replaced with various terms such as a terminal, a wireless device, a WTRU (Wireless Transmit Receive Unit), a UE (User Equipment), an MS (Mobile Station), a UT (user terminal), an MSS (Mobile Subscriber Station), an MSS (Mobile Subscriber Unit), an SS (Subscriber Station), an AMS (Advanced Mobile Station), a WT (Wireless terminal), or simply a user. In addition, the first device (100) and the second device (200) may be replaced with various terms such as an access point (AP), a BS (Base Station), a fixed station, a Node B, a BTS (Base Transceiver System), a network, an AI (Artificial Intelligence) system, an RSU (road side unit), a repeater, a router, a relay, a gateway, etc.

[0036] The devices (100, 200) illustrated in FIG. 1 may also be referred to as stations (STAs). For example, the devices (100, 200) illustrated in FIG. 1 may be referred to by various terms such as transmitting device, receiving device, transmitting STA, and receiving STA. For example, the STAs (110, 200) may perform an AP (access point) role or a non-AP role. That is, in the present disclosure, the STAs (110, 200) may perform the functions of an AP and / or a non-AP. When the STAs (110, 200) perform an AP function, they may simply be referred to as APs, and when the STAs (110, 200) perform a non-AP function, they may simply be referred to as STAs. In addition, in the present disclosure, the APs may also be referred to as AP STAs.

[0037] Referring to FIG. 1, the first device (100) and the second device (200) can transmit and receive wireless signals through various wireless LAN technologies (e.g., IEEE 802.11 series). The first device (100) and the second device (200) can include interfaces for a medium access control (MAC) layer and a physical layer (PHY) that follow the provisions of the IEEE 802.11 standard.

[0038] In addition, the first device (100) and the second device (200) may additionally support various communication standards (e.g., 3GPP LTE series, 5G NR series standards, etc.) other than wireless LAN technology. In addition, the device of the present disclosure may be implemented as various devices such as a mobile phone, a vehicle, a personal computer, an AR (Augmented Reality) device, a VR (Virtual Reality) device, etc. In addition, the STA of the present specification may support various communication services such as voice calls, video calls, data communications, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).

[0039] A first device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (102) may process information in the memory (104) to generate first information / signal, and then transmit a wireless signal including the first information / signal via the transceiver (106). In addition, the processor (102) may receive a wireless signal including second information / signal via the transceiver (106), and then store information obtained from signal processing of the second information / signal in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0040] The second device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). In addition, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including instructions for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in the present disclosure. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present disclosure, a device may also mean a communication modem / circuit / chip.

[0041] Hereinafter, the hardware elements of the device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed in the present disclosure, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed in the present disclosure.

[0042] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and driven by one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods and / or operation flowcharts disclosed in this disclosure may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0043] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0044] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of the present disclosure, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of the present disclosure, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed in the present disclosure, via one or more antennas (108, 208). In the present disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0045] For example, one of the STAs (100, 200) may perform the intended operation of an AP, and the other of the STAs (100, 200) may perform the intended operation of a non-AP STA. For example, the transceivers (106, 206) of FIG. 1 may perform transmission and reception operations of signals (e.g., packets or PPDUs (Physical layer Protocol Data Units) according to IEEE 802.11a / b / g / n / ac / ax / be / bn, etc.). In addition, in the present disclosure, operations in which various STAs generate transmission and reception signals or perform data processing or calculations in advance for transmission and reception signals may be performed in the processors (102, 202) of FIG. 1. For example, an example of an operation for generating a transmission / reception signal or performing data processing or operation in advance for a transmission / reception signal may include 1) an operation for determining / obtaining / configuring / computing / decoding / encoding bit information of a field (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in a PPDU, 2) an operation for determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a field (SIG, STF, LTF, Data, etc.) included in a PPDU, 3) an operation for determining / configuring / obtaining a specific sequence (e.g., a pilot sequence, an STF / LTF sequence, an extra sequence applied to SIG) used for a field (SIG, STF, LTF, Data, etc.) included in a PPDU, 4) a power control operation and / or a power saving operation applied to an STA, 5) an operation related to determining / obtaining / configuring / computing / decoding / encoding an ACK signal, etc. Additionally, in the examples below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for determining / acquiring / configuring / computing / decoding / encoding transmission / reception signals can be stored in the memory (104, 204) of FIG. 1.

[0046] Hereinafter, downlink (DL) refers to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. can be transmitted and received through the downlink. In downlink communication, the transmitter may be part of an AP STA, and the receiver may be part of a non-AP STA. Uplink (UL) refers to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs / packets / signals, etc. can be transmitted and received through the uplink. In uplink communication, the transmitter may be part of a non-AP STA, and the receiver may be part of an AP STA.

[0047] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0048] The structure of a wireless LAN system can be composed of multiple components. Through the interaction of multiple components, a wireless LAN that supports transparent STA mobility to the upper layer can be provided. A Basic Service Set (BSS) corresponds to a basic building block of a wireless LAN. FIG. 2 illustrates, by way of example, the existence of two BSSs (BSS1 and BSS2) and the inclusion of two STAs as members of each BSS (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2). The oval representing a BSS in FIG. 2 can also be understood as representing a coverage area in which STAs included in the corresponding BSS maintain communication. This area can be referred to as a Basic Service Area (BSA). When an STA moves outside of a BSA, it cannot directly communicate with other STAs within the BSA.

[0049] If we do not consider the DS illustrated in Figure 2, the most basic type of BSS in a wireless LAN is an Independent BSS (IBSS). For example, an IBSS can have a minimal form consisting of only two STAs. For example, assuming other components are omitted, BSS1 consisting of only STA1 and STA2, or BSS2 consisting of only STA3 and STA4, can be representative examples of an IBSS, respectively. Such a configuration is possible when the STAs can communicate directly without an AP. Furthermore, in this type of WLAN, a LAN can be configured when needed rather than being planned in advance, and this can be called an ad-hoc network. Since an IBSS does not include an AP, there is no centralized management entity. That is, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and access to distributed systems (DS) is not permitted, forming a self-contained network.

[0050] An STA's membership in a BSS can dynamically change, for example, when an STA is turned on or off, or when an STA enters or leaves a BSS area. To become a member of a BSS, an STA can join the BSS using a synchronization process. To access all services in the BSS infrastructure, an STA must be associated with the BSS. This association can be dynamically established and may involve the use of a Distribution System Service (DSS).

[0051] In a wireless LAN, the direct STA-to-STA distance can be limited by PHY performance. While this distance limit may be sufficient in some cases, communication between STAs over longer distances may be required in other cases. To support extended coverage, a distributed system (DS) can be configured.

[0052] DS refers to a structure in which BSSs are interconnected. Specifically, a BSS may exist as an extended component of a network composed of multiple BSSs, as illustrated in Figure 2. DS is a logical concept and can be specified by the characteristics of a distributed system medium (DSM). In this regard, the Wireless Medium (WM) and DSM can be logically distinguished. Each logical medium is used for a different purpose and by different components. These media are neither limited to being identical nor limited to being different. This logical difference between multiple media explains the flexibility of the WLAN architecture (DS architecture or other network architecture). In other words, the WLAN architecture can be implemented in various ways, and the physical characteristics of each implementation can independently specify the WLAN architecture.

[0053] A DS can support mobile devices by providing seamless integration of multiple BSSs and the logical services necessary to handle addresses to destinations. Additionally, a DS may further include a component called a portal, which acts as a bridge for connecting wireless LANs to other networks (e.g., IEEE 802.X).

[0054] An AP is an entity that enables access to a DS through a WM for associated non-AP STAs and also has the functionality of an STA. Data movement between a BSS and a DS can be performed through an AP. For example, STA2 and STA3 illustrated in FIG. 2 have the functionality of an STA and provide the function of allowing associated non-AP STAs (STA1 and STA4) to access the DS. In addition, since all APs are basically STAs, all APs are addressable entities. The address used by an AP for communication on a WM and the address used by an AP for communication on a DSM do not necessarily have to be the same. A BSS consisting of an AP and one or more STAs can be referred to as an infrastructure BSS.

[0055] Data transmitted from one of the STA(s) associated with an AP to the STA address of that AP may always be received on an uncontrolled port and processed by an IEEE 802.1X port access entity. In addition, if the controlled port is authenticated, the transmitted data (or frame) may be forwarded to the DS.

[0056] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0057] An ESS is a network of arbitrary size and complexity, consisting of DSs and BSSs. An ESS may correspond to a set of BSSs connected to a DS. However, an ESS does not include a DS. An ESS network is characterized by appearing as an IBSS at the Logical Link Control (LLC) layer. STAs within an ESS can communicate with each other, and mobile STAs can move from one BSS to another (within the same ESS) transparently to the LLC. APs within an ESS may have the same SSID (service set identification). The SSID is distinct from the BSSID, which is the identifier of the BSS.

[0058] In a wireless LAN system, no assumptions are made about the relative physical locations of BSSs, and all of the following configurations are possible: BSSs can be partially overlapping, which is commonly used to provide continuous coverage. BSSs can also be physically disconnected, and there is no logical distance limit between them. BSSs can also be physically co-located, which can be used to provide redundancy. Furthermore, one (or more) IBSS or ESS networks can physically co-exist with one (or more) ESS networks. This can occur in cases where an ad-hoc network operates at the same location as an ESS network, where physically overlapping wireless networks are configured by different organizations, or where two or more different access and security policies are required at the same location.

[0059] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0060] For an STA to set up a link and transmit and receive data on a network, it must first discover the network, perform authentication, establish an association, and complete security authentication procedures. The link setup process can also be referred to as the session initiation process or session setup process. Furthermore, the discovery, authentication, association, and security setup processes of the link setup process can be collectively referred to as the association process.

[0061] In step S310, the STA may perform a network discovery operation. This network discovery operation may include scanning operations by the STA. That is, for the STA to access a network, it must search for available networks. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning.

[0062] Scanning methods include active scanning and passive scanning. Figure 3 illustrates a network discovery operation including an active scanning process as an example. In active scanning, an STA performing scanning transmits a probe request frame to discover any APs in the vicinity while moving between channels and waits for a response. The responder transmits a probe response frame in response to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In the BSS, the AP transmits the beacon frame, so the AP becomes the responder. In the IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not fixed. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe requests / responses on channel 2) in the same manner.

[0063] Although not shown in Figure 3, the scanning operation can also be performed in a passive scanning manner. In passive scanning, the STA performing the scanning moves between channels and waits for a beacon frame. A beacon frame is one of the management frames defined in IEEE 802.11. It announces the existence of a wireless network and is periodically transmitted so that the STA performing the scanning can find the wireless network and participate in the wireless network. In the BSS, the AP performs the role of periodically transmitting the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the STA performing the scanning receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. The STA receiving the beacon frame stores the BSS-related information included in the received beacon frame and moves to the next channel to perform scanning on the next channel in the same manner. Comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.

[0064] After the STA discovers the network, an authentication process may be performed in step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step S340 described below.

[0065] The authentication process involves the STA sending an authentication request frame to the AP, and the AP responding by sending an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0066] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group. These are just some examples of information that may be included in an authentication request / response frame, and may be replaced with other information or include additional information.

[0067] An STA can send an authentication request frame to an AP. The AP can determine whether to grant authentication to the STA based on the information contained in the received authentication request frame. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0068] After the STA is successfully authenticated, an association process may be performed in step S330. The association process includes a process in which the STA transmits an association request frame to the AP, and in response, the AP transmits an association response frame to the STA.

[0069] For example, the association request frame may include information about various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, an RSN, a mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, the association response frame may include information about various capabilities, a status code, an Association ID (AID), supported rates, an Enhanced Distributed Channel Access (EDCA) parameter set, a Received Channel Power Indicator (RCPI), a Received Signal to Noise Indicator (RSNI), a mobility domain, a timeout interval (e.g., an association comeback time), overlapping BSS scan parameters, a TIM broadcast response, a Quality of Service (QoS) map, etc. These are just some examples of information that may be included in a combined request / response frame, and may be replaced by other information or include additional information.

[0070] After the STA successfully joins the network, a security setup process may be performed in step S340. The security setup process in step S340 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request / response, the authentication process in step S320 may be referred to as a first authentication process, and the security setup process in step S340 may also be referred to simply as an authentication process.

[0071] The security setup process of step S340 may include, for example, a process of establishing a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame. Furthermore, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.

[0072] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0073] In wireless LAN systems, the basic access mechanism of MAC (Medium Access Control) is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). The CSMA / CA mechanism, also known as the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, essentially employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or STA may perform a Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., a DCF Inter-Frame Space (DIFS)) before starting transmission. If the sensing result determines that the medium is in an idle state, the AP and / or STA may start transmitting frames through the medium. On the other hand, if the medium is detected to be occupied or busy, the AP and / or STA may not start its own transmission, but may wait for a delay period (e.g., a random backoff period) for medium access before attempting to transmit frames. By applying a random backoff period, multiple STAs are expected to attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

[0074] In addition, the IEEE 802.11 MAC protocol provides the Hybrid Coordination Function (HCF). The HCF is based on the DCF and the Point Coordination Function (PCF). The PCF is a polling-based synchronous access method that periodically polls all receiving APs and / or STAs to ensure that they receive data frames. In addition, the HCF has the Enhanced Distributed Channel Access (EDCA) and the HCF Controlled Channel Access (HCCA). The EDCA is a contention-based access method for a provider to provide data frames to multiple users, while the HCCA uses a non-contention-based channel access method that utilizes a polling mechanism. In addition, the HCF includes a medium access mechanism to improve the Quality of Service (QoS) of the wireless LAN, and can transmit QoS data in both the Contention Period (CP) and the Contention Free Period (CFP).

[0075] Referring to Fig. 4, an operation based on a random backoff period is described. When a medium that was occupied / busy changes to an idle state, multiple STAs can attempt to transmit data (or frames). To minimize collisions, each STA can select a random backoff count, wait for the corresponding slot time, and then attempt transmission. The random backoff count has a pseudo-random integer value and can be determined as one of the values ​​in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given an initial value of CWmin, but can take a value doubled in case of transmission failure (e.g., when an ACK for a transmitted frame is not received). When the CW parameter value becomes CWmax, data transmission can be attempted while maintaining the CWmax value until data transmission is successful, and if data transmission is successful, it is reset to the CWmin value. The CW, CWmin, and CWmax values ​​are 2. n It is desirable to set it to -1 (n=0, 1, 2, ...).

[0076] Once the random backoff process begins, the STA continues to monitor the medium while counting down the backoff slots according to the determined backoff count value. If the medium is monitored as occupied, the countdown stops and waits. When the medium becomes idle, the remaining countdown resumes.

[0077] In the example of FIG. 4, when a packet to be transmitted reaches the MAC of STA3, STA3 can immediately transmit a frame if it confirms that the medium is idle for DIFS. The remaining STAs monitor the medium for occupied / busy states and wait. In the meantime, data to be transmitted may also occur in each of STA1, STA2, and STA5, and each STA can count down the backoff slot according to a random backoff count value selected by each STA after waiting for DIFS if the medium is monitored as idle. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value. In other words, this example shows a case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 when STA2 finishes the backoff count and starts frame transmission. STA1 and STA5 briefly stop counting down and wait while STA2 occupies the medium. When STA2's occupation ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the backoff count that they had stopped. That is, they can start transmitting frames after counting down the remaining backoff slots equal to the remaining backoff time. Since STA5's remaining backoff time is shorter than STA1's, STA5 starts transmitting frames. While STA2 occupies the medium, STA4 may also have data to transmit. From STA4's perspective, when the medium becomes idle, it waits for DIFS, counts down according to its selected random backoff count value, and then starts transmitting frames. In the example of Figure 4, the remaining backoff time of STA5 coincidentally matches the random backoff count value of STA4, in which case a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failure in data transmission.In this case, STA4 and STA5 can select a random backoff count value and perform a countdown after doubling the CW value. STA1 waits while the medium is occupied by transmissions from STA4 and STA5, and when the medium becomes idle, it waits for DIFS and can start transmitting frames after the remaining backoff time elapses.

[0078] As in the example of Fig. 4, a data frame is a frame used for transmitting data forwarded to a higher layer, and can be transmitted after a backoff performed after DIFS elapses from when the medium becomes idle. Additionally, a management frame is a frame used for exchanging management information that is not forwarded to a higher layer, and is transmitted after a backoff performed after an IFS elapses, such as DIFS or PIFS (Point coordination function IFS). Subtype frames of a management frame include a beacon, an association request / response, a re-association request / response, a probe request / response, and an authentication request / response. A control frame is a frame used to control access to the medium. The subtype frames of the control frame include Request-To-Send (RTS), Clear-To-Send (CTS), Acknowledgment (ACK), Power Save-Poll (PS-Poll), Block ACK (BlockAck), Block ACK Request (BlockACKReq), Null Data Packet Announcement (NDP), and Trigger. If the control frame is not a response frame to the previous frame, it is transmitted after a backoff performed after the DIFS (Direct Inverse Frame Stop) has elapsed, and if it is a response frame to the previous frame, it is transmitted without a backoff performed after the SIFS (short IFS). The type and subtype of the frame can be identified by the type field and subtype field in the Frame Control (FC) field.

[0079] A QoS (Quality of Service) STA can transmit a frame after a backoff performed after the AIFS (arbitration IFS) for the access category (AC) to which the frame belongs, i.e., AIFS[i] (where i is a value determined by the AC), has elapsed. Here, the frames for which AIFS[i] can be used can be data frames, management frames, and also control frames that are not response frames.

[0080] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0081] As mentioned above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, in which STAs directly sense the medium. Virtual carrier sensing is intended to address potential issues in medium access, such as the hidden node problem. For virtual carrier sensing, the MAC of an STA can utilize a Network Allocation Vector (NAV). The NAV is a value that an STA that is currently using or has the right to use the medium indicates to other STAs the remaining time until the medium becomes available. Therefore, the value set as NAV corresponds to the period during which the STA transmitting the frame is scheduled to use the medium, and an STA receiving the NAV value is prohibited from accessing the medium during that period. For example, the NAV can be set based on the value of the "duration" field in the MAC header of the frame.

[0082] In the example of FIG. 5, it is assumed that STA1 wants to transmit data to STA2, and STA3 is in a position to overhear some or all of the frames transmitted and received between STA1 and STA2.

[0083] In order to reduce the possibility of collisions in transmissions of multiple STAs in a CSMA / CA-based frame transmission operation, a mechanism using RTS / CTS frames may be applied. In the example of FIG. 5, while STA1 is transmitting, STA3 may determine that the medium is idle based on carrier sensing results. That is, STA1 may correspond to a hidden node for STA3. Alternatively, in the example of FIG. 5, while STA2 is transmitting, STA3 may determine that the medium is idle based on carrier sensing results. That is, STA2 may correspond to a hidden node for STA3. By exchanging RTS / CTS frames before performing data transmission and reception between STA1 and STA2, STAs outside the transmission range of either STA1 or STA2, or STAs outside the carrier sensing range for transmissions from STA1 or STA3, may not attempt to occupy the channel during data transmission and reception between STA1 and STA2.

[0084] Specifically, STA1 can determine whether a channel is occupied through carrier sensing. In terms of physical carrier sensing, STA1 can determine channel occupancy idleness based on the energy level or signal correlation detected in the channel. Furthermore, in terms of virtual carrier sensing, STA1 can determine the channel occupancy status using a network allocation vector (NAV) timer.

[0085] STA1 can transmit an RTS frame to STA2 after performing a backoff if the channel is idle during the DIFS. STA2 can transmit a CTS frame, which is a response to the RTS frame, to STA1 after an SIFS if it receives the RTS frame.

[0086] If STA3 cannot overhear a CTS frame from STA2 but can overhear an RTS frame from STA1, STA3 can use the duration information contained in the RTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame). Alternatively, if STA3 cannot overhear an RTS frame from STA1 but can overhear a CTS frame from STA2, STA3 can use the duration information contained in the CTS frame to set a NAV timer for the subsequent consecutively transmitted frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame). That is, if STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly. If STA3 receives a new frame before the NAV timer expires, it can update the NAV timer using the duration information contained in the new frame. STA3 does not attempt channel access until the NAV timer expires.

[0087] If STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 after SIFS from the time when the CTS frame is completely received. If STA2 successfully receives the data frame, it can transmit an ACK frame in response to the data frame to STA1 after SIFS. STA3 can determine whether the channel is in use through carrier sensing if the NAV timer expires. If STA3 determines that the channel is not in use by another terminal during the DIFS after the NAV timer expires, it can attempt channel access after a contention window (CW) following a random backoff has elapsed.

[0088] FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.

[0089] The PHY layer can prepare an MPDU (MAC PDU) to be transmitted based on an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer. For example, when a command requesting the start of transmission of the PHY layer is received from the MAC layer, the PHY layer can switch to transmission mode and transmit the information (e.g., data) provided by the MAC layer in the form of a frame. In addition, when the PHY layer detects a valid preamble of the received frame, it monitors the header of the preamble and sends a command to the MAC layer notifying the start of reception of the PHY layer.

[0090] In this way, information transmission / reception in a wireless LAN system is done in the form of frames, and for this purpose, the PHY layer Protocol Data Unit (PPDU) format is defined.

[0091] A basic PPDU may include a Short Training Field (STF), a Long Training Field (LTF), a SIGNAL (SIG) field, and a Data field. The most basic (e.g., non-HT (High Throughput) as illustrated in FIG. 7) PPDU format may consist of only the Legacy-STF (L-STF), Legacy-LTF (L-LTF), Legacy-SIG (L-SIG) fields, and a Data field. Additionally, depending on the type of PPDU format (e.g., HT-mixed format PPDU, HT-greenfield format PPDU, VHT (Very High Throughput) PPDU, etc.), additional (or different types of) RL-SIG, U-SIG, non-legacy SIG field, non-legacy STF, non-legacy LTF, (i.e., xx-SIG, xx-STF, xx-LTF (e.g., xx is HT, VHT, HE, EHT, etc.)) may be included between the L-SIG field and the data field. More specific details will be described later with reference to FIG. 7.

[0092] STF is a signal for signal detection, AGC (Automatic Gain Control), diversity selection, and precise time synchronization, while LTF is a signal for channel estimation, frequency error estimation, etc. STF and LTF can be said to be signals for synchronization and channel estimation of the OFDM physical layer.

[0093] The SIG field may include various information related to PPDU transmission and reception. For example, the L-SIG field may consist of 24 bits and may include a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity field, and a 6-bit Tail field. The RATE field may include information about the modulation and coding rate of data. For example, the 12-bit Length field may include information about 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 the PPDU. For example, for a non-HT, HT, VHT, or EHT PPDU, the value of the Length field may be determined as a multiple of 3. For example, for HE PPDU, the value of the Length field can be determined as a multiple of 3 + 1 or a multiple of 3 + 2.

[0094] The data field may include a SERVICE field, a Physical layer Service Data Unit (PSDU), a PPDU TAIL bit, and, if necessary, padding bits. Some bits of the SERVICE field may be used to synchronize the descrambler at the receiving end. The PSDU corresponds to a MAC PDU defined at the MAC layer and may contain data generated / used by upper layers. The PPDU TAIL bit may be used to return the encoder to a 0 state. The padding bit may be used to adjust the length of the data field to a predetermined unit.

[0095] MAC PDUs are defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a Frame Check Sequence (FCS). A MAC frame is composed of MAC PDUs and can be transmitted / received through the PSDU in the data portion of the PPDU format.

[0096] The MAC header includes a Frame Control field, a Duration / ID field, an Address field, etc. The Frame Control field may include control information required for frame transmission / reception. The Duration / ID field may be set to a time for transmitting the corresponding frame, etc. The Address subfields may indicate the receiver address, transmitter address, destination address, and source address of the frame, and some Address subfields may be omitted. For specific details of each subfield of the MAC header, including the Sequence Control, QoS Control, and HT Control subfields, refer to the IEEE 802.11 standard document.

[0097] The Null-Data PPDU (NDP) format refers to a PPDU format that does not include a data field. In other words, NDP refers to a frame format that includes a PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields, and, if additionally present, non-legacy SIG, non-legacy STF, and non-legacy LTF) in the general PPDU format, and does not include the remaining part (i.e., data field).

[0098] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0099] Standards such as IEEE 802.11a / g / n / ac / ax use various PPDU formats. The basic PPDU format (IEEE 802.11a / g) includes L-LTF, L-STF, L-SIG, and Data fields. The basic PPDU format can also be referred to as the non-HT PPDU format (Fig. 7(a)).

[0100] The HT PPDU format (IEEE 802.11n) additionally includes HT-SIG, HT-STF, and HT-LFT(s) fields in addition to the basic PPDU format. The HT PPDU format illustrated in Fig. 7(b) may be referred to as an HT-mixed format. Additionally, an HT-greenfield format PPDU may be defined, which corresponds to a format that does not include L-STF, L-LTF, and L-SIG, but consists of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data fields (not illustrated).

[0101] An example of the VHT PPDU format (IEEE 802.11ac) includes VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format (Fig. 7(c)).

[0102] An example of a HE PPDU format (IEEE 802.11ax) additionally includes RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in addition to the basic PPDU format (Fig. 7(d)). Depending on specific examples of the HE PPDU format, some fields may be excluded or their lengths may vary. For example, the HE-SIG-B field is included in the HE PPDU format for multi-users (MUs), but the HE PPDU format for single users (SUs) does not include the HE-SIG-B. In addition, the HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 8us. The HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16us. For example, RL-SIG can be configured identically to L-SIG. The receiving STA can determine that the received PPDU is a HE PPDU or an EHT PPDU, described later, based on the presence of RL-SIG.

[0103] The EHT PPDU format may include the EHT MU (multi-user) PPDU of FIG. 7(e) and the EHT TB (trigger-based) PPDU of FIG. 7(f). The EHT PPDU format is similar to the HE PPDU format in that it includes an RL-SIG following an L-SIG, but may include a U (universal)-SIG, an EHT-SIG, an EHT-STF, and an EHT-LTF following the RL-SIG.

[0104] The EHT MU PPDU in FIG. 7(e) corresponds to a PPDU that carries one or more data (or PSDUs) for one or more users. That is, the EHT MU PPDU can be used for both SU transmission and MU transmission. For example, the EHT MU PPDU can correspond to a PPDU for one receiving STA or multiple receiving STAs.

[0105] The EHT TB PPDU of Fig. 7(f) omits the EHT-SIG compared to the EHT MU PPDU. An STA that has received a trigger for UL MU transmission (e.g., a trigger frame or TRS (triggered response scheduling)) can perform UL transmission based on the EHT TB PPDU format.

[0106] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated so that even legacy STAs can attempt demodulation and decoding, and can be mapped based on a predetermined subcarrier frequency interval (e.g., 312.5 kHz). These can be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields can be encoded and modulated so that they can be demodulated and decoded by an STA that has successfully decoded a non-legacy SIG (e.g., U-SIG and / or EHT-SIG) and obtained the information contained in the corresponding field, and can be mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

[0107] Similarly, in the HE PPDU format, the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields may be referred to as pre-HE modulation fields, and the HE-STF, HE-LTF, Data, and PE fields may be referred to as HE modulation fields. Additionally, in the VHT PPDU format, the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields may be referred to as pre-VHT modulation fields, and the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields may be referred to as VHT modulation fields.

[0108] The U-SIG included in the EHT PPDU format of FIG. 7 can be configured based on, for example, two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., OFDM symbol) for the U-SIG can have a duration of 4 us, and the U-SIG can have a total duration of 8 us. Each symbol of the U-SIG can be used to transmit 26 bits of information. For example, each symbol of the U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0109] U-SIGs can be configured in 20MHz units. For example, when an 80MHz PPDU is configured, the same U-SIG can be duplicated in 20MHz units. That is, four identical U-SIGs can be included in an 80MHz PPDU. When the bandwidth exceeds 80MHz, for example, for a 160MHz PPDU, the U-SIGs in the first 80MHz unit and the U-SIGs in the second 80MHz unit can be different.

[0110] For example, A uncoded bits may be transmitted via U-SIG, and a first symbol of U-SIG (e.g., a U-SIG-1 symbol) may transmit the first X bits of information out of a total A bits of information, and a second symbol of U-SIG (e.g., a U-SIG-2 symbol) may transmit the remaining Y bits of information out of a total A bits of information. The A bits of information (e.g., 52 uncoded bits) may include a CRC field (e.g., a field of 4 bits in length) and a tail field (e.g., a field of 6 bits in length). The tail field may be used to terminate the trellis of the convolutional decoder and may be set to 0, for example.

[0111] The A bit information transmitted by U-SIG can be divided into version-independent bits and version-dependent bits. For example, U-SIG can be included in a new PPDU format (e.g., UHR PPDU format) not shown in FIG. 7, and in the format of the U-SIG field included in the EHT PPDU format and the format of the U-SIG field included in the UHR PPDU format, the version-independent bits can be the same, and some or all of the version-dependent bits can be different.

[0112] For example, the size of the version-independent bits of U-SIG can be fixed or variable. The version-independent bits can be assigned only to U-SIG-1 symbols, or to both U-SIG-1 symbols and U-SIG-2 symbols. The version-independent bits and the version-dependent bits can be called by various names, such as the first control bit and the second control bit.

[0113] For example, the version-independent bits of the U-SIG may include a 3-bit PHY version identifier, which may indicate the PHY version (e.g., EHT, UHR, etc.) of the transmitted and received PPDUs. The version-independent bits of the U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication. The version-independent bits of the U-SIG may include information about the length of a transmission opportunity (TXOP) and information about a BSS color ID.

[0114] For example, the version-dependent bits of the U-SIG may contain information that directly or indirectly indicates the type of PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.).

[0115] Information required for PPDU transmission and reception may be included in the U-SIG. For example, the U-SIG may further include information about bandwidth, information about the MCS technique applied to the non-legacy SIG (e.g., EHT-SIG or UHR-SIG), information indicating whether a dual carrier modulation (DCM) technique (e.g., a technique to achieve an effect similar to frequency diversity by reusing the same signal on two subcarriers) is applied to the non-legacy SIG, information about the number of symbols used for the non-legacy SIG, information about whether the non-legacy SIG is generated across the entire band, etc.

[0116] Some of the information required for transmitting and receiving a PPDU may be included in the U-SIG and / or the non-legacy SIG (e.g., EHT-SIG or UHR-SIG, etc.). For example, information about the type of the non-legacy LTF / STF (e.g., EHT-LTF / EHT-STF or UHR-LTF / UHR-STF, etc.), information about the length of the non-legacy LTF and the cyclic prefix (CP) length, information about the guard interval (GI) applicable to the non-legacy LTF, information about preamble puncturing applicable to the PPDU, information about resource unit (RU) allocation, etc. may be included only in the U-SIG, may be included only in the non-legacy SIG, or may be indicated by a combination of the information included in the U-SIG and the information included in the non-legacy SIG.

[0117] Preamble puncturing may refer to the transmission of a PPDU in which no signal is present in one or more frequency units within the PPDU's bandwidth. For example, the size of the frequency unit (or the resolution of the preamble puncturing) may be defined as 20 MHz, 40 MHz, etc. For example, preamble puncturing may be applied to a PPDU bandwidth greater than a certain size.

[0118] In the example of FIG. 7, non-legacy SIGs such as HE-SIG-B and EHT-SIG may include control information for the receiving STA. The non-legacy SIG may be transmitted over at least one symbol, and each symbol may have a length of 4 us. Information regarding the number of symbols used for the EHT-SIG may be included in a previous SIG (e.g., HE-SIG-A, U-SIG, etc.).

[0119] Non-legacy SIGs, such as HE-SIG-B and EHT-SIG, may contain common fields and user-specific fields. Common and user-specific fields may be coded separately.

[0120] In some cases, common fields may be omitted. For example, in a compressed mode where non-OFDMA (orthogonal frequency multiple access) is applied, common fields may be omitted, and multiple STAs may receive PPDUs (e.g., data fields of PPDUs) over the same frequency band. In a non-compressed mode where OFDMA is applied, multiple users may receive PPDUs (e.g., data fields of PPDUs) over different frequency bands.

[0121] The number of user-specific fields can be determined based on the number of users. A single user block field can contain up to two user fields. Each user field can be associated with either MU-MIMO allocation or non-MU-MIMO allocation.

[0122] The common field may include CRC bits and Tail bits, the length of the CRC bits may be determined as 4 bits, and the length of the Tail bits may be determined as 6 bits and set to 000000. The common field may include RU allocation information. The RU allocation information may include information about the location of RUs to which multiple users (i.e., multiple receiving STAs) are allocated.

[0123] An RU can contain multiple subcarriers (or tones). RUs can be used when transmitting signals to multiple STAs based on OFDMA techniques. RUs can also be defined when transmitting signals to a single STA. Resources can be allocated on an RU basis for non-legacy STFs, non-legacy LTFs, and data fields.

[0124] Depending on the PPDU bandwidth, an applicable RU size can be defined. The RU may be defined identically or differently for the applicable PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, in the case of an 80MHz PPDU, the RU arrangements of HE PPDU and EHT PPDU may be different. The applicable RU size, RU number, RU position, DC (direct current) subcarrier position and number, null subcarrier position and number, guard subcarrier position and number, etc. for each PPDU bandwidth can be referred to as a tone plan. For example, a tone plan for a wide bandwidth can be defined in the form of multiple repetitions of a low bandwidth tone plan.

[0125] RUs of different sizes can be defined, such as 26-ton RU, 52-ton RU, 106-ton RU, 242-ton RU, 484-ton RU, 996-ton RU, 2X996-ton RU, 3X996-ton RU, etc. A multiple RU (MRU) is distinguished from multiple individual RUs and corresponds to a group of subcarriers consisting of multiple RUs. For example, one MRU can be defined as 52+26-tons, 106+26-tons, 484+242-tons, 996+484-tons, 996+484+242-tons, 2X996+484-tons, 3X996-tons, or 3X996+484-tons. Additionally, multiple RUs constituting one MRU may or may not be consecutive in the frequency domain.

[0126] The specific size of an RU may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) in the present disclosure is not limited and is exemplary. Furthermore, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, etc.) in the present disclosure, the number of RUs may vary depending on the RU size.

[0127] The names of each field in the PPDU formats of FIG. 7 are exemplary and the scope of the present disclosure is not limited by those names. Furthermore, the examples of the present disclosure can be applied not only to the PPDU format exemplified in FIG. 7, but also to a new PPDU format in which some fields are excluded and / or some fields are added based on the PPDU formats of FIG. 7.

[0128] trigger frame

[0129] FIG. 8 is a drawing showing an exemplary format of a trigger frame to which the present disclosure can be applied.

[0130] A trigger frame may allocate resources for the transmission of one or more TB PPDUs and request the transmission of TB PPDUs. The trigger frame may also include other information required by the STA transmitting the TB PPDU in response. The trigger frame may include common information and a user information list field in the frame body.

[0131] The common information field may include information common to one or more TB PPDU transmissions requested by the trigger frame, such as trigger type, UL length, presence of a subsequent trigger frame (e.g., More TF), whether CS (channel sensing) is required, UL BW (bandwidth), etc.

[0132] A user information list contains zero or more user information fields. Figure 8 illustrates an example of an EHT variant user information field format.

[0133] The AID12 subfield basically indicates that it is a user information field for an STA with the corresponding AID. In addition, if the AID12 field has a predetermined specific value, it may be utilized for other purposes, such as allocating a random access (RA)-RU, or being configured in the form of a special user information field. The special user information field is a user information field that does not contain user-specific information, but contains extended common information not provided in the common information field. For example, the special user information field can be identified by the AID12 value of 2007, and the special user information field flag subfield within the common information field can indicate whether the special user information field is included.

[0134] The RU allocation subfield can indicate the size and position of the RU / MRU. For this purpose, the RU allocation subfield can be interpreted together with the PS160 (primary / secondary 160MHz) subfield of the user information field, the UL BW subfield of the common information field, etc. For example, the mapping of B7-B1 of the RU allocation subfield can be defined together with the settings of the B0 and PS160 subfields of the RU allocation subfield as shown in Table 1 below. Table 1 shows an example of encoding the PS160 subfield and the RU allocation subfield of the EHT variant user information field.

[0135]

[0136]

[0137]

[0138]

[0139]

[0140] If the PS160 subfield is 0 and the RU / MRU size is 996 tones or less, setting B0 of the RU Allocation subfield to 0 may indicate that the RU / MRU allocation is applied to the primary 80 MHz channel, and setting its value to 1 may indicate that the RU allocation is applied to the secondary 80 MHz channel of the primary 160 MHz. On the other hand, if the PS160 subfield is 1 and the RU / MRU size is 996 tones or less, setting B0 of the RU Allocation subfield to 0 may indicate that the RU / MRU allocation is applied to the lower 80 MHz of the secondary 160 MHz, and setting its value to 1 may indicate that the RU allocation is applied to the upper 80 MHz of the secondary 160 MHz.

[0141] In the trigger frame RU allocation table of Table 1, the parameter N can be calculated based on the formula N=2*X1+X0. For a bandwidth of 80 MHz or less, the values ​​of PS160, B0, X0, and X1 can be set to 0. For a bandwidth of 160 MHz and a bandwidth of 320 MHz, the values ​​of PS160, B0, X0, and X1 can be set as shown in Table 2. These settings represent the absolute frequency order for the primary and secondary 80 MHz and 160 MHz channels. The order from left to right represents the order from low frequency to high frequency. The primary 80 MHz channel is represented as P80, the secondary 80 MHz channel is represented as S80, and the secondary 160 MHz channel is represented as S160.

[0142]

[0143] Resource Unit (RU) and Resource Allocation

[0144] FIGS. 9 to 11 are diagrams for explaining examples of resource units of a wireless LAN system to which the present disclosure can be applied.

[0145] Referring to FIGS. 9 to 11, a resource unit (RU) defined in a wireless LAN system is described. An RU may include multiple subcarriers (or tones). An RU may be used when transmitting signals to multiple STAs based on OFDMA techniques. An RU may also be defined when transmitting signals to a single STA. An RU may be used for the STF, LTF, and data fields of a PPDU.

[0146] As illustrated in FIGS. 9 to 11, RUs corresponding to different numbers of tones (i.e., subcarriers) may be used to configure some fields of a 20 MHz, 40 MHz, or 80 MHz X-PPDU (X represents HE, EHT, etc.). For example, resources may be allocated in units of RUs illustrated for the X-STF, X-LTF, and Data fields.

[0147] Figure 9 is a diagram showing an exemplary arrangement of resource units (RUs) used on a 20 MHz band.

[0148] As shown at the top of Fig. 9, 26 units (i.e., units corresponding to 26 tones) may be allocated. Six tones may be used as a guard band in the leftmost band of the 20 MHz band, and five tones may be used as a guard band in the rightmost band of the 20 MHz band. In addition, seven DC tones may be inserted in the center band, i.e., the DC band, and 26 units corresponding to 13 tones may exist on each side of the DC band. In addition, 26 units, 52 units, and 106 units may be allocated to other bands. Each unit may be allocated for an STA or a user.

[0149] The RU arrangement of FIG. 9 can be utilized not only in situations for multiple users (MUs) but also in situations for a single user (SU), in which case it is possible to use a single 242-unit as shown at the bottom of FIG. 9. In this case, three DC tones can be inserted.

[0150] In the example of FIG. 9, RUs of various sizes, such as 26-RU, 52-RU, 106-RU, and 242-RU, are exemplified, but the specific sizes of these RUs may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) in the present disclosure is not limited and is exemplary. In addition, in the present disclosure, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...), the number of RUs may vary depending on the RU size. In the examples of FIG. 10 and / or FIG. 11 described below, the fact that the size and / or number of RUs may be changed is the same as in the example of FIG. 9.

[0151] Figure 10 is a diagram showing an exemplary arrangement of resource units (RUs) used on a 40 MHz band.

[0152] As in the example of FIG. 9 where RUs of various sizes were used, the example of FIG. 10 may also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, etc. In addition, five DC tones may be inserted at the center frequency, 12 tones may be used as a guard band in the leftmost band of the 40 MHz band, and 11 tones may be used as a guard band in the rightmost band of the 40 MHz band.

[0153] Additionally, as shown, when used for a single user, 484-RU may be used.

[0154] Figure 11 is a diagram showing an exemplary arrangement of resource units (RUs) used on the 80 MHz band.

[0155] As in the examples of FIGS. 9 and 10 where RUs of various sizes were used, the example of FIG. 11 may also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, 996-RU, etc. In addition, in the case of 80MHz PPDU, the RU arrangement of HE PPDU and EHT PPDU may be different, and the example of FIG. 11 shows an example of the RU arrangement for 80MHz EHT PPDU. In the example of FIG. 11, 12 tones are used as guard bands in the leftmost band of the 80MHz band, and 11 tones are used as guard bands in the rightmost band of the 80MHz band, which is the same for HE PPDU and EHT PPDU. Unlike the HE PPDU, which has seven DC tones inserted into the DC band and one 26-RU corresponding to 13 tones on each side of the DC band, the EHT PPDU has 23 DC tones inserted into the DC band and one 26-RU corresponding to 13 tones on each side of the DC band. Unlike the HE PPDU, which has one null subcarrier between the 242-RUs other than the center band, the EHT PPDU has five null subcarriers. In the HE PPDU, one 484-RU does not contain a null subcarrier, but in the EHT PPDU, one 484-RU contains five null subcarriers.

[0156] Also, as shown, when used for a single user, 996-RU can be used, in which case the insertion of 5 DC tones is common in both HE PPDU and EHT PPDU.

[0157] An EHT PPDU of 160MHz or higher may be configured with multiple 80MHz subblocks as shown in FIG. 11. The RU layout for each 80MHz subblock may be the same as the RU layout of the 80MHz EHT PPDU as shown in FIG. 11. If an 80MHz subblock of a 160MHz or 320MHz EHT PPDU is not punctured and the entire 80MHz subblock is used as part of an RU or MRU (Multiple RU), the 80MHz subblock may use the 996-RU layout as shown in FIG. 11.

[0158] Here, an MRU corresponds to a group of subcarriers (or tones) composed of multiple RUs, and the multiple RUs constituting an MRU may be RUs of the same size or different sizes. For example, a single MRU may be defined as 52+26-tones, 106+26-tones, 484+242-tones, 996+484-tones, 996+484+242-tones, 2X996+484-tones, 3X996-tones, or 3X996+484-tones. Here, the multiple RUs constituting one MRU may correspond to RUs of small size (e.g., 26, 52, 106) or RUs of large size (e.g., 242, 484, 996, etc.). That is, a single MRU containing both small-sized RUs and large-sized RUs may not be configured / defined. Furthermore, multiple RUs constituting a single MRU may or may not be consecutive in the frequency domain.

[0159] If an 80MHz subblock contains RUs smaller than 996 tones, or portions of the 80MHz subblock are punctured, the 80MHz subblock may use RU layouts other than the 996-tone RUs.

[0160] The positions of RUs can be fixed as defined in Tables 3 to 7 below according to each PPDU bandwidth.

[0161] Table 3 illustrates the indices of RUs within a 20MHz PPDU and the data and pilot subcarrier indices (ranges) for each RU.

[0162]

[0163] Table 4 illustrates the indices of RUs within a 40MHz PPDU and the data and pilot subcarrier indices (ranges) for each RU.

[0164]

[0165] Table 5 illustrates the indices of RUs within an 80MHz PPDU and the data and pilot subcarrier indices (ranges) for each RU.

[0166]

[0167] Table 6 illustrates the indices of RUs within a 160MHz PPDU and the data and pilot subcarrier indices (ranges) for each RU.

[0168]

[0169]

[0170] Table 7 illustrates the indices of RUs within a 320MHz PPDU and the data and pilot subcarrier indices (ranges) for each RU.

[0171]

[0172]

[0173]

[0174]

[0175] In Table 3, RU 5 corresponds to the middle 26-ton RU.

[0176] Referring to Tables 3 to 7, subcarrier index 0 corresponds to the DC tone. Negative subcarrier indices correspond to subcarriers having a lower frequency than the DC tone. Positive subcarrier indices correspond to subcarriers having a higher frequency than the DC tone. DC subcarriers may refer to subcarriers having zero energy, including the DC tone and subcarrier indices adjacent to subcarrier index 0 (i.e., the DC tone). Guard subcarriers may refer to subcarriers located at the edge of an OFDM symbol in the frequency domain and having zero energy. Null subcarriers are located near the DC or edge tone to protect against transmission center frequency leakage, receiver DC offset, and interference from adjacent RU(s) or MRU(s), and have zero energy.

[0177] Referring to Figures 9 to 11 and Tables 3 to 7, for each RU, an RU index can be assigned in order from low frequency to high frequency.

[0178] A PPDU in the 160 MHz range or higher may consist of multiple 80 MHz frequency subblocks. The tone plan and RU allocation for each 80 MHz frequency subblock may be the same as the 80 MHz PPDU. If an 80 MHz frequency subblock of a 160 MHz or 320 MHz PPDU is not punctured and the entire 80 MHz frequency subblock is used as an RU or as part of an RU / MRU, the 80 MHz frequency subblock may use the 996-tone RU illustrated in FIG. 10. If an 80 MHz frequency subblock contains RUs with fewer than 996 tones or a portion of the 80 MHz frequency subblock is punctured, the 80 MHz frequency subblock may use a tone plan and RU allocation excluding the 996-tone RU, as illustrated in FIG. 10.

[0179] An STA may be assigned multiple RUs (MRUs). The subcarrier indices of an MRU may be composed of the indices of the corresponding RUs that constitute the MRU.

[0180] The RU of the present disclosure can be used for uplink (UL) and / or downlink (DL) communication. For example, when trigger-based UL-MU communication is performed, an STA (e.g., an AP) transmitting a trigger can allocate a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a first STA and a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a second STA through trigger information (e.g., a trigger frame or triggered response scheduling (TRS)). Thereafter, the first STA can transmit a first trigger-based (TB) PPDU based on the first RU, and the second STA can transmit a second TB PPDU based on the second RU. The first / second TB PPDUs can be transmitted to the AP in the same time interval.

[0181] For example, when a DL MU PPDU is configured, an STA (e.g., an AP) transmitting the DL MU PPDU may allocate a first RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a first STA and a second RU (e.g., 26 / 52 / 106 / 242-RU, etc.) to a second STA.

[0182] Trigger-based PPDU transmission and reception method

[0183] According to the current standard, if an STA cannot transmit a PPDU (e.g., a TB PPDU (trigger-based PPDU)) triggered by a trigger frame in a manner specified in the trigger frame, the STA does not transmit the PPDU. For example, when AP1 instructs STA1 to transmit a 484-tone RU in an 80 MHz band with a trigger frame, if STA1 cannot transmit for reasons such as interference being detected in 242-tone RUs among the allocated 484-tone RUs, STA1 does not transmit a TB PPDU for the entire 484-tone RU. In this case, resource waste occurs, so the present disclosure proposes a more efficient transmission method.

[0184] Hereinafter, the present disclosure proposes a method for transmitting a PPDU by adaptively changing the RU size by an STA when a PPDU transmitted by being triggered by a trigger frame cannot follow the RU allocation specified in the trigger frame. Hereinafter, for convenience of explanation, the present disclosure refers to the STA adaptively changing the RU size to transmit a PPDU as "adaptive PPDU transmission."

[0185] Here, the adaptive PPDU referred to in the present disclosure may be a UL PPDU (e.g., UL TB PPDU) of a non-AP STA triggered by a trigger frame of an AP. Alternatively, in case of multi-AP transmission, the adaptive PPDU referred to in the present disclosure may be a shared AP DL PPDU triggered by an AP-to-AP trigger frame of a sharing AP.

[0186] Hereinafter, in this disclosure, STA may be collectively referred to as an AP, a non-AP STA, a relay, a mesh, or any other device.

[0187] In this disclosure, it is mainly explained that the following basic assumptions apply to PPDUs adaptively transmitted by STAs, but this is for convenience of explanation, and this disclosure is not limited thereto.

[0188] - Adaptive PPDU transmission is possible only when a large-size RU / MRU larger than 242-tone RU is allocated.

[0189] - Adaptive PPDU transmission is possible only with large-size RUs / MRUs that are smaller than or equal to the allocated RU / MRU.

[0190] - The RU / MRU size of the changed adaptive PPDU transmission is only possible with the RU / MRU set defined in the standard.

[0191] Below, the method of operating Adaptive PPDU is described in detail.

[0192] Example 1: An STA can perform adaptive PPDU transmission by arbitrarily changing the RU allocation. That is, if transmission is to be performed differently from the RU allocation indicated in the trigger frame (if the RU allocation indicated in the trigger frame cannot be followed), the STA can independently configure and transmit an adaptive PPDU.

[0193] (1) If the STA does not separately inform the AP about the TB PPDU (i.e., adaptive PPDU), the AP can receive the TB PPDU by determining whether it is transmitted every 20MHz. That is, the AP must perform preamble detection every 20MHz to determine whether the TB PPDU requested in the trigger frame is transmitted in case the TB PPDU is transmitted differently from the RU configuration indicated by the trigger frame, which may incur detection overhead for the AP.

[0194] To reduce this detection overhead, the types of adaptive PPDU configurations can be restricted. That is, STAs can only independently determine adaptive PPDUs within predefined adaptive PPDU formats / configurations.

[0195] For example, adaptive PPDU can be configured only if PPDU can be configured for consecutive 20 / 40 / 80 / 160MHz. For example (Example 1), if AP has allocated 484+242-tone MRU (i.e., assumed to be the first, second, and fourth 20MHz positions, where the first, second, third, and fourth 20MHz may be distinguished by RU index, or by the order of primary 20MHz and secondary 20MHz, or by the order of physical 20MHz region (e.g., ascending frequency order)). In this case, if STA cannot transmit the fourth 242-tone RU, it can construct and transmit adaptive PPDU only for 484-tone RU (first and second 20MHz positions). If the STA is unable to transmit a TB PPDU in the first and / or second 20MHz region, it may not transmit the entire PPDU.

[0196] As another example, adaptive PPDU transmission may be allowed only for non-MRU RU configurations within the configuration of the RU allocation subfield of the trigger frame (see FIG. 8). Example 1 above also applies, and as another example (Example 2), if the AP has allocated a 996-tone RU, and the STA cannot transmit on the third 20MHz, the adaptive PPDU may be transmitted only on the 484-tone RUs in the first and second 20MHz positions (here, the first, second, third, and fourth 20MHz may be distinguished by RU index, or by order such as primary 20MHz and secondary 20MHz, or by order of the physical 20MHz region (e.g., ascending frequency order)). When configuring this limited adaptive PPDU, the AP can perform PPDU detection only for a limited area and configuration rather than performing PPDU detection for the entire allocated 20MHz, thereby reducing detection overhead.

[0197] (2) The STA can inform the AP of whether the RU has changed through the SIG field of the adaptive PPDU (e.g., U-SIG field, UHR-SIG, etc.). However, in general, the SIG information for each STA within 80MHz must be the same. However, if the RU has changed in the SIG field of one STA in a situation where 80MHz is allocated to two or more STAs, a problem may arise where the SIG field is configured differently for each STA. Therefore, it is preferable to use the above method when resources are allocated to one STA within 80MHz.

[0198] Meanwhile, in the case of the first embodiment, the STA prepares a PPDU configuration according to the RU allocation specified in the trigger frame and transmits the PPDU after SIFS from the reception of the trigger frame. However, the preparation time may not be sufficient to determine the channel status within the SIFS time and transmit an adaptive PPDU accordingly.

[0199] Example 2: An AP may allocate multiple RUs to a single STA. For example, instead of allocating one 242+484 MRU to a single STA, 242 RUs and 484 RUs may be allocated to each STA. Currently, in a trigger frame, a single allocation is possible using a single user-specific information field (i.e., a user information field) to a single STA. On the other hand, for example, according to the present embodiment, multiple RUs may be allocated to a single STA using two or more user-specific information fields. Here, the MCS, the number of spatial streams, etc. may also be allocated differently in the multiple user-specific information fields.

[0200] In the conventional case, when decoding a trigger frame, the STA checks whether the AID in the user information field is its own AID or not, and if its own AID is found, it can stop decoding the user information fields following the corresponding user information field. However, according to the present embodiment, unlike in the conventional case, the STA must continue to decode the subsequent user information fields even if it finds its own AID, which may incur decoding overhead. However, the user information fields for the same AID within the trigger frame are configured consecutively, so the decoding overhead can be minimized. That is, the STA can find its own AID in the user information fields within the trigger frame, check the next user information field, and perform decoding if it is its own AID, and stop decoding if it is not its own AID. However, in this case, since the RU is divided, the size of the data encoded at one time is reduced, and the packet error rate (PER: Packet Error Rate) may increase during decoding.

[0201] Example 3: After receiving approval from the AP, an adaptive PPDU can be transmitted. That is, after the AP allocates an RU, the RU can be reallocated after receiving a short response for the allocated RU from the STA(s). This method has the advantage of allowing the STA to secure preparation time to transmit the adaptive PPDU, unlike the proposed method of Example 1. Here, the detailed method can be distinguished as follows depending on the form of the short response.

[0202] Method 1) The short response can be transmitted in the same frame (with the same content and structure) for each allocated 20MHz region. For example, the CTS frame can be transmitted only in the allocated 20MHz region. The MU-RTS (multi-user request to send) trigger frame described below or another trigger frame can be used as the trigger frame for this. In this embodiment, for the convenience of explanation, the case where the MU-RTS frame is used is mainly described, but the present disclosure is not limited thereto. That is, it can be interpreted as being replaced by another trigger frame that triggers a TB PPDU.

[0203] In the existing MU-RTS / CTS procedure, the CTS frame must be transmitted in Non-HT DUP (duplication) format in units of P20 (primary 20) / 40 / 80 / 160 / 320 MHz, and only RU allocation for P20 / 40 / 80 / 160 / 320 MHz is possible in the MU-RTS trigger frame.

[0204] In this embodiment, the following modified MU-RTS / CTS procedure is proposed. This indicates the RU region in which the actual STA will transmit with the MU-RTS frame, and the STA can transmit the CTS frame only in the region in which transmission is possible among the allocated 20MHz region (242-tone RU). This method may incur detection overhead of the AP like the proposed method of Embodiment 1, but preamble detection can be simpler because the same frame in the Non-HT DUP format is carried every 20MHz. A specific operation example is as follows.

[0205] FIG. 12 illustrates a procedure for transmitting and receiving a trigger-based PPDU according to one embodiment of the present disclosure.

[0206] FIG. 12 illustrates an example where resources are allocated in 242-tone RU units per 20 MHz in an 80 MHz bandwidth, but this is an example for convenience of explanation, and the bandwidth and RU units illustrated in FIG. 12 may be changed.

[0207] Referring to FIG. 12, assuming an 80MHz bandwidth, the AP can transmit the modified MU-RTS frame in a non-HT DUP (duplication) format across the entire bandwidth. For example, as shown in FIG. 12, the first, second, and fourth 20MHz (242-tone RU region) can be allocated to STA1, and the third 20MHz (242-tone RU region) can be allocated to STA2.

[0208] STAs may receive the modified MU-RTS frame and transmit a modified CTS frame in their respective allocated areas. Here, STA1 may not transmit the modified CTS frame in the fourth 20MHz (242-tone RU area) where interference is detected. Here, the STA may transmit the modified CTS frame only for the continuous bandwidth as in 'Example 1' described in Embodiment 1, or may transmit the modified CTS frame only for the configuration of RUs other than MRUs within the allocated bandwidth as in 'Example 2'.

[0209] The AP verifies whether a CTS frame has been transmitted for the entire allocated area. Here, the method of verification is an implementation issue, but for example, the AP can perform preamble detection in 20MHz units to verify. For example, preamble detection can be simpler if a modified CTS frame is transmitted only for the continuous bandwidth as in Example 1 of Embodiment 1, or only for the RU configuration, not the MRU configuration, within the allocated bandwidth as in Example 2. In addition, the AP can reconfigure the allocated area excluding the area where the CTS frame is not transmitted and transmit a trigger frame for TB PPDU transmission. Here, the AP may not reallocate the area where the STA transmitted the CTS frame as is, but may modify and reallocate it. For example, resources may be reallocated according to the configuration of the existing RU allocation subfield.

[0210] STAs can transmit TB PPDUs according to the area allocated by the trigger frame.

[0211] Method 2) A short response may be a frame containing information on acceptance or rejection of an assigned RU (e.g., acceptance or rejection per 20MHz). This is explained with reference to the drawing below.

[0212] FIG. 13 illustrates a procedure for transmitting and receiving a trigger-based PPDU according to one embodiment of the present disclosure.

[0213] FIG. 13 illustrates an example where resources are allocated in 242-tone RU units per 20 MHz in an 80 MHz bandwidth, but this is an example for convenience of explanation, and the bandwidth and RU units illustrated in FIG. 13 may be changed.

[0214] Referring to FIG. 13, assuming an 80 MHz bandwidth, the AP can transmit the first trigger frame across the entire bandwidth. For example, as shown in FIG. 13, the first, second, and fourth 20 MHz (242-tone RU region) can be allocated to STA1, and the third 20 MHz (242-tone RU region) can be allocated to STA2.

[0215] As in Figure 13, for example, to reduce detection overhead per 20MHz of an AP, the AP can announce its RU configuration (via the first trigger frame) and receive the STA's response thereto in a small RU (less than a 242-tone RU) on the primary 20MHz.

[0216] In this case, the first trigger frame may include an instruction that it is a trigger frame for this purpose.

[0217] Additionally, the first trigger frame may contain information about a small RU for transmitting a short response in addition to information about an RU that will transmit a TB PPDU (e.g., a large-size RU). Alternatively, the information about a small RU for transmitting a short response in the first trigger frame may be omitted by using an implicit method of mapping 26-tone RU indices according to the order of the user information fields (the first user information field is mapped to the lowest 26-tone RU index, the second user information field is mapped to the second lowest 26-tone RU index, ...). In this case, information about up to 9 users in 20 MHz may be included, for example.

[0218] The STA can include information in the form of a TB PPDU in the short response to the trigger frame, including whether it can respond to the large RU allocated by the AP (i.e., whether TB PPDU transmission is possible in the allocated area). For example, a bitmap composed of bits corresponding to every 20MHz can be defined. In this case, the STA can set only the bits for the possible 20MHz areas among the allocated areas to '1', and set the bits for the other areas (i.e., unallocated areas or allocated but not transmittable areas) to '0', and feed back the corresponding bit values ​​through the short response. As another example, the STA can include the RU allocation subfield of the trigger frame to feed back the possible configurations to the AP through the short response.

[0219] An STA may not transmit a short response on a band other than the primary 20MHz. Alternatively, an STA may duplicate a frame carried on the primary 20MHz band and transmit it in a transmittable area within its assigned area to protect against an overlapping BSS (OBSS).

[0220] The AP may reconfigure the allocation area based on the information in the short response and transmit a second trigger frame for TB PPDU transmission. Here, the AP may modify the area indicated by the STA in the short response rather than reallocating it as is. For example, resources may be reallocated according to the configuration of the existing RU allocation subfield.

[0221] STAs can transmit TB PPDUs according to the area allocated by the second trigger frame.

[0222] FIG. 14 illustrates the operation of a device for a PPDU transmission and reception method according to one embodiment of the present disclosure.

[0223] Figure 14 illustrates the operation of a device based on the previously proposed methods. The example in Figure 14 is provided for convenience of explanation and does not limit the scope of the present disclosure. Some of the steps illustrated in Figure 14 may be omitted depending on the circumstances and / or settings.

[0224] The device exemplified in FIG. 14 may include a non-AP station (non-AP STA), another AP different from the AP, or a device such as a relay or mesh.

[0225] Referring to FIG. 14, the device receives a first frame including information for allocation of a first frequency range from an AP (S1401).

[0226] The device transmits a PPDU to the AP based on the first frame (S1402).

[0227] Here, the PPDU can be transmitted in a second frequency domain different from the first frequency domain.

[0228] According to the above-described embodiment 1, the second frequency domain may be composed of only continuous frequency resources in the frequency domain. In addition, the second frequency domain may be composed of only one or more continuous resource units (RUs) in the frequency domain, rather than multiple resource units (MRUs).

[0229] In this case, the PPDU includes a SIG (signal) field, and the SIG field may indicate that the second frequency range is different from the first frequency range.

[0230] Additionally, according to the above-described embodiment 2, the first frequency domain may be allocated to a plurality of RUs, and the second frequency domain may be configured as a part of the plurality of RUs.

[0231] In this case, the first frame includes a plurality of user information fields for the device, and the plurality of RUs can be allocated by the plurality of user information fields.

[0232] In addition, according to the above-described embodiment 3, after receiving the first frame, the device can transmit a response frame for the first frame. Here, the response frame can be transmitted by the device in a frequency range in which transmission of the PPDU is possible within the first frequency range. And, the device can receive a second frame from the AP. Here, the second frequency range in which the PPDU is to be transmitted can be allocated by the second frame.

[0233] In addition, after receiving the first frame, the device may transmit a response frame for the first frame. Here, the response frame may be transmitted in a predetermined specific frequency range and may include information about a frequency range in which the PPDU can be transmitted by the device within the first frequency range. In addition, the device may receive a second frame from the AP. Here, the second frequency range in which the PPDU is to be transmitted may be allocated by the second frame.

[0234] Based on the allocation of RUs and / or MRUs of a size larger than 242-tone RUs to the first frequency domain, the PPDU may be transmittable in the second frequency domain different from the first frequency domain.

[0235] Additionally, the second frequency domain may be included in (equal to or smaller than) the first frequency domain in the frequency domain.

[0236] Additionally, the second frequency domain may be composed of a combination of one or more RUs and / or MRUs.

[0237] Additionally, the first frame may be a MU-RTS trigger frame, and the response frame may be a CTS frame.

[0238] Transmission and reception of the frame illustrated in Fig. 14 means transmission and reception of the PPDU carrying the frame. The PPDU for the procedure illustrated in Fig. 14 can be configured as follows.

[0239] Here, the PPDU may be configured to include a legacy part, a SIG part (e.g., U-SIG, UHR-SIG, etc.), an STF part (e.g., UHR-STF), an LTF part (e.g., UHR-LTF), and a data part.

[0240] All or part of any part (i.e., field) may be divided into multiple sub-parts / sub-fields. Each field (and its sub-fields) may be transmitted in units of 4us * N (where N is an integer). Additionally, a guard interval (GI) may be included. A common subcarrier frequency spacing value (delta_f=312.5 kHz / N or 312.5 kHz * N, where N=integer) may be applied to all of the fields, or a first delta_f may be applied to the first part (e.g., all legacy part, all / part of SIG part), and a second delta_f (e.g., a value smaller than the first delta_f) may be applied to all / part of the remaining parts.

[0241] Some of the fields described above may be omitted, and the order of the fields may be changed in various ways. For example, the subfields of the signal part may be placed before the STF part, and the remaining subfields of the SIG part may be placed after the STF part.

[0242] The legacy portion described above may include at least one of a conventional L-STF (Non-HT Short Training Field), L-LTF (Non-HT Long Training Field), and L-SIG (Non-HT Signal Field).

[0243] The SIG portion described above (e.g., including the U-SIG field, UHR-SIG field, etc.) may include various control information for the transmitted PPDU. For example, it may include the STF portion, the LTF portion, and control information for decoding data.

[0244] The above-described STF-part (e.g., the U-STF field) may contain an STF sequence.

[0245] The above-described LTF-part (e.g., U-LTF field) may include a training field (i.e., LTF sequence) for channel estimation.

[0246] The data-part described above may include user data and may include packets (e.g., MPDUs) for upper layers (i.e., first frames or response frames).

[0247] The method described in the example of FIG. 14 may be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) of FIG. 1 may be configured to transmit a first frame (or a PPDU including the first frame) via the transceiver(s) (106). Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 14 or the examples described above when executed by one or more processors (102).

[0248] FIG. 15 illustrates the operation of an access point for a PPDU transmission and reception method according to one embodiment of the present disclosure.

[0249] Figure 15 illustrates the operation of an access point based on the previously proposed methods. The example in Figure 15 is provided for convenience of explanation and does not limit the scope of the present disclosure. Some of the steps illustrated in Figure 15 may be omitted depending on the circumstances and / or settings.

[0250] The device exemplified in FIG. 15 may include a non-AP station (non-AP STA), another AP different from the AP, or a device such as a relay or mesh.

[0251] Referring to FIG. 15, the AP transmits a first frame including information for allocation of a first frequency region to the device (S1501).

[0252] The AP receives a PPDU based on the first frame from the device (S1502).

[0253] Here, the PPDU can be transmitted in a second frequency domain different from the first frequency domain.

[0254] According to the above-described embodiment 1, the second frequency domain may be composed of only continuous frequency resources in the frequency domain. In addition, the second frequency domain may be composed of only one or more continuous resource units (RUs) in the frequency domain, rather than multiple resource units (MRUs).

[0255] In this case, the PPDU includes a SIG (signal) field, and the SIG field may indicate that the second frequency range is different from the first frequency range.

[0256] Additionally, according to the above-described embodiment 2, the first frequency domain may be allocated to a plurality of RUs, and the second frequency domain may be configured as a part of the plurality of RUs.

[0257] In this case, the first frame includes a plurality of user information fields for the device, and the plurality of RUs can be allocated by the plurality of user information fields.

[0258] In addition, according to the above-described embodiment 3, after receiving the first frame, the device can transmit a response frame for the first frame. Here, the response frame can be transmitted by the device in a frequency range in which transmission of the PPDU is possible within the first frequency range. And, the device can receive a second frame from the AP. Here, the second frequency range in which the PPDU is to be transmitted can be allocated by the second frame.

[0259] In addition, after receiving the first frame, the device may transmit a response frame for the first frame. Here, the response frame may be transmitted in a predetermined specific frequency range and may include information about a frequency range in which the PPDU can be transmitted by the device within the first frequency range. In addition, the device may receive a second frame from the AP. Here, the second frequency range in which the PPDU is to be transmitted may be allocated by the second frame.

[0260] Based on the allocation of RUs and / or MRUs of a size larger than 242-tone RUs to the first frequency domain, the PPDU may be transmittable in the second frequency domain different from the first frequency domain.

[0261] Additionally, the second frequency domain may be included in (equal to or smaller than) the first frequency domain in the frequency domain.

[0262] Additionally, the second frequency domain may be composed of a combination of one or more RUs and / or MRUs.

[0263] Additionally, the first frame may be a MU-RTS trigger frame, and the response frame may be a CTS frame.

[0264] Transmission and reception of the frame described in FIG. 15 means transmission and reception of the PPDU carrying the frame. The PPDU for the procedure illustrated in FIG. 15 can be configured as follows.

[0265] Here, the PPDU may be configured to include a legacy part, a SIG part (e.g., U-SIG, UHR-SIG, etc.), an STF part (e.g., UHR-STF), an LTF part (e.g., UHR-LTF), and a data part.

[0266] All or part of any part (i.e., field) may be divided into multiple sub-parts / sub-fields. Each field (and its sub-fields) may be transmitted in units of 4us * N (where N is an integer). Additionally, a guard interval (GI) may be included. A common subcarrier frequency spacing value (delta_f=312.5 kHz / N or 312.5 kHz * N, where N=integer) may be applied to all of the fields, or a first delta_f may be applied to the first part (e.g., all legacy part, all / part of SIG part), and a second delta_f (e.g., a value smaller than the first delta_f) may be applied to all / part of the remaining parts.

[0267] The method proposed in this disclosure has been described with a focus on examples applied to IEEE 802.11-based systems, but can be applied to various wireless LANs or wireless communication systems in addition to IEEE 802.11-based systems.

Claims

1. A step of receiving a first frame from an access point (AP), by a device, wherein the first frame includes information for allocation of a first frequency range; and A step of transmitting a PPDU (physical protocol data unit) based on the first frame to the AP by the device, A method wherein the PPDU is transmitted in a second frequency domain different from the first frequency domain.

2. In paragraph 1, A method wherein the second frequency domain is composed of only continuous frequency resources in the frequency domain.

3. In paragraph 1, A method in which the second frequency domain is composed of only one or more consecutive resource units (RUs) in a frequency domain rather than multiple resource units (MRUs).

4. In paragraph 1, The above PPDU includes a SIG (signal) field, A method wherein the second frequency range is indicated to be different from the first frequency range by the SIG field.

5. In paragraph 1, The above first frequency domain is allocated to a number of RUs, A method wherein the second frequency domain is composed of a portion of the plurality of RUs.

6. In paragraph 5, The first frame includes a plurality of user information fields for the device, A method in which a plurality of RUs are allocated by a plurality of user information fields.

7. In paragraph 1, A step of transmitting, by the device, a response frame for the first frame, wherein the response frame is transmitted in a frequency range in which transmission of the PPDU is possible within the first frequency range by the device; and A method further comprising the step of: receiving a second frame from the AP by the device, wherein the second frequency range in which the PPDU is to be transmitted is allocated by the second frame.

8. In paragraph 1, A step of transmitting, by the device, a response frame for the first frame, wherein the response frame is transmitted in a predetermined specific frequency range and includes information about a frequency range in which transmission of the PPDU is possible within the first frequency range by the device; and A method further comprising the step of: receiving a second frame from the AP by the device, wherein the second frequency range in which the PPDU is to be transmitted is allocated by the second frame.

9. In paragraph 1, A method wherein the PPDU is transmittable in the second frequency region different from the first frequency region, based on the allocation of RUs and / or MRUs of a size larger than 242-tone RUs to the first frequency region.

10. In paragraph 1, A method wherein the second frequency region is included in the first frequency region in the frequency domain.

11. In paragraph 1, A method wherein the second frequency domain is composed of a combination of one or more RUs and / or MRUs.

12. In paragraph 1, A method wherein the above device is a non-AP station (non-AP STA) or another AP different from the above AP.

13. One or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: Receive a first frame from an access point (AP), wherein the first frame includes information for allocation of a first frequency range, and It is set to transmit a PPDU (physical protocol data unit) based on the first frame to the AP, A device wherein the PPDU is transmitted in a second frequency domain different from the first frequency domain.

14. A step of transmitting a first frame to a device by an access point (AP), wherein the first frame includes information for allocation of a first frequency range; and A step of receiving a physical protocol data unit (PPDU) based on the first frame from the device by the AP, A method wherein the PPDU is transmitted in a second frequency domain different from the first frequency domain.

15. One or more transmitters and receivers; and comprising one or more processors connected to said one or more transceivers, One or more of the above processors: Transmitting a first frame to a device, wherein the first frame includes information for allocation of a first frequency range, and It is set to receive a PPDU (physical protocol data unit) based on the first frame from the above device, An access point wherein the above PPDU is transmitted in a second frequency domain different from the first frequency domain.

16. In a processing device configured to control a device in a wireless LAN system, the processing device: one or more processors; and A processing device comprising one or more computer memories operatively connected to said one or more processors and storing instructions that, when executed by said one or more processors, perform a method according to any one of claims 1 to 12.

17. One or more non-transitory computer-readable media storing one or more instructions, A computer-readable medium, wherein the one or more commands are executed by one or more processors to control a device in a wireless LAN system to perform a method according to any one of claims 1 to 12.

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