Method and apparatus for performing power saving operation in wireless LAN system

Abstract

A method and an apparatus operating in a wireless LAN system are disclosed. A method performed by a first station (STA) in a wireless LAN system according to an embodiment of the present disclosure may comprise the steps of: receiving an initial control frame from a second STA in a first power mode; transmitting an initial control response frame for the initial control frame to the second STA; and receiving a first frame from the second STA in a second power mode on the basis of the initial control frame, wherein a time interval for switching from the first power mode to the second power mode is based on i) a predefined first time interval and ii) a second time interval of the first frame or the initial control frame.

Description

Method and device for performing power saving operation in a wireless LAN system

[0001] The present disclosure relates to communication operations in a wireless local area network (WLAN) system, and more specifically, to a method and device for performing power saving operations in a next-generation wireless LAN 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 performing a power saving operation in a wireless LAN system.

[0005] The technical problem of the present disclosure is to provide a method and device for performing an operation based on a low-power listening mode.

[0006] 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.

[0007] In one embodiment of the present disclosure, a method is provided, comprising: receiving an initial control frame by a first station (STA) from a second STA in a first power mode; transmitting an initial control response frame for the initial control frame by the first STA to the second STA; and receiving a first frame by the first STA from the second STA in a second power mode based on the initial control frame, wherein a time period for switching from the first power mode to the second power mode may be based on i) a predefined first time period and ii) a second time period of the initial control frame or the first frame.

[0008] In another embodiment of the present disclosure, a method is provided, comprising: transmitting an initial control frame by a second station (STA) to a first STA in a first power mode; receiving an initial control response frame for the initial control frame by the second STA from the first STA; and transmitting a first frame by the second STA to the first STA in a second power mode based on the initial control frame, wherein a time period for switching from the first power mode to the second power mode may be based on i) a predefined first time period and ii) a second time period of the initial control frame or the first frame.

[0009] According to various embodiments of the present disclosure, a method and device for performing a power saving operation in a wireless LAN system can be provided.

[0010] According to various embodiments of the present disclosure, a method and device for performing an operation based on a low-power listening mode can be provided.

[0011] Various embodiments of the present disclosure may result in additional power reduction of STAs operating in power saving mode in high frequency bands.

[0012] 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.

[0013] 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.

[0014] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0015] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0016] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0017] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0018] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0019] 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.

[0020] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0021] FIG. 8 is a flowchart illustrating a method performed by a first STA according to one embodiment of the present disclosure.

[0022] FIG. 9 is a flowchart illustrating a method performed by a second STA according to one embodiment of the present disclosure.

[0023] FIG. 10, FIG. 11 and FIG. 12 are diagrams illustrating a procedure related to a low-power listening mode according to one embodiment of the present disclosure.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] In this disclosure, terms such as “first,” “second,” etc. are used only to distinguish one component from another and are not used to limit the components, and do not limit the order or importance between the 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.

[0028] 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.

[0029] 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.

[0030] Below, technical features to which examples of the present disclosure can be applied are described.

[0031] FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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).

[0036] 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 memories (104) to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceivers (106). Furthermore, the processor (102) may receive a wireless signal including second information / signals via the transceivers (106), and then store information obtained from signal processing of the second information / signals 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.

[0037] 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). Furthermore, 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

[0045] 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.

[0046] 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.

[0047] 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).

[0048] 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.

[0049] 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 architectures). 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.

[0050] 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).

[0051] 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.

[0052] 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.

[0053] In addition to the structure of the DS described above, an extended service set (ESS) may be established to provide wider coverage.

[0054] 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.

[0055] 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 restriction 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.

[0056] FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.

[0070] 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.

[0071] 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).

[0072] 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, ...).

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] FIG. 5 is a diagram for explaining a CSMA / CA-based frame transmission operation to which the present disclosure can be applied.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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) based on a random backoff has elapsed.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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).

[0095] FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.

[0096] 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)).

[0097] 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).

[0098] 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)).

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated to allow legacy STAs to attempt demodulation and decoding, and 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 to allow STAs that have successfully decoded non-legacy SIGs (e.g., U-SIG and / or EHT-SIG) and obtained the information contained in the fields, and mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.).

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.).

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] Power saving mode in high frequency bands

[0126] As the number of wireless devices capable of accessing the Internet grows exponentially, interest in technologies that reduce the power consumption associated with these devices is growing. Massive power generation can lead to the emission of large quantities of greenhouse gases, such as carbon dioxide, and the resulting global warming poses a direct threat to human life. A significant portion of this power generation is handled by thermal power plants, and thermal power generation, which relies on the combustion of fossil fuels (e.g., coal, oil, etc.), is a major source of greenhouse gas emissions. Reducing power consumption is currently a top priority across various technological fields, contributing to the reduction of greenhouse gas emissions.

[0127] Meanwhile, operation in high-frequency bands can experience significant power reduction relative to distance due to the channel characteristics. To compensate for this power reduction relative to distance, the use of directional antennas and increased transmission power are being considered. In the present disclosure, the high-frequency band may include, but is not limited to, the millimeter wave band. The description of the present disclosure can also be applied to general high-frequency bands.

[0128] Increasing the bandwidth of high-frequency bands can result in additional power consumption in receivers. Operations in high-frequency bands (e.g., high-speed analog-to-converters (ADCs)) are sensitive to phase noise, requiring high-performance phase-loop locking (PLLs), which can require additional power consumption.

[0129] To support power reduction in high-frequency bands, a power-saving mode may be applied / supported. If the power-saving mode is applied to at least one STA, at least one STA may operate in an Awake state / mode or a Doze state / mode.

[0130] The active state / mode can be divided into a listening mode, which waits for (re)transmission, and a transmitting / receiving mode, which supports data transmission and reception. STA(s) in the listening state / mode can perform various operations after assuming the maximum bandwidth and MCS that the receiving device can cover.

[0131] In a basic wireless LAN system, this may include operations to help reduce power by allowing reception of more than one spatial stream instead of multiple streams as a spatial multiplexing power save (SMPS) operation, but other settings may be maintained (e.g., full bandwidth and higher MCS reception latency).

[0132] In next-generation wireless LAN systems, operations and parameters for a low-power listening mode may be applied in the sub-7 GHz band. Additionally, considering operations and parameters related to the millimeter wave band in next-generation wireless LAN systems, a low-power listening mode may also be defined and applied in high-frequency bands. Accordingly, the power reduction effect in high-frequency bands may be greater than that in the sub-7 GHz band.

[0133] Hereinafter, the operation and information related to the low-power listening mode of an STA and / or a personal BSS control point (PCP) (or / and a PCP STA) will be described. Herein, the STA may include a non-AP STA and / or an AP. In addition, the present disclosure will describe a method for providing a sufficient amount of time when an STA and / or a PCP (or / and a PCP STA) operating in a low-power listening mode switches to full-bandwidth operation for data reception.

[0134] FIG. 8 is a flowchart illustrating a method performed by a first STA according to an embodiment of the present disclosure. The first STA may be a non-AP STA or a PCP STA (MLD), and the second STA may be, but is not limited to, an AP or a PCP (MLD). The first STA may be an AP or a PCP (MLD), and the second STA may be a non-AP STA or a PCP STA (MLD).

[0135] In describing the present disclosure, the first power mode may mean a low-power listening mode, and the second power mode may mean a full-power receiving mode. For example, at least one of a size of a bandwidth, a number of spatial streams, a modulation order (or / and MCS), or a power level supported in the first power mode may be smaller than at least one of a size of a bandwidth, a number of spatial streams, a modulation order (or / and MCS), or a power level supported in the second power mode. For example, a size of a receive / transmit power in the first power mode may be smaller than a size of a receive / transmit power in the second power mode.

[0136] The first STA can receive an initial control frame from the second STA in the first power mode (S810).

[0137] The initial control frame may be at least one of a multi-user ready to send (RTS) trigger frame or a specific variant of the trigger frame. However, this is only one embodiment, and the initial control frame may also be implemented as a separate frame.

[0138] Additionally, prior to step S810, the first STA may receive configuration information related to the initial control frame from the second STA or transmit it to the second STA. The configuration information related to the initial control frame may include the configuration of the initial control frame, information for transmitting the initial control frame (e.g., bandwidth, MCS, modulation method, etc.), etc. The configuration information related to the initial control frame may be exchanged between the first STA and the second STA in sub-7 GHz.

[0139] The configuration information related to the initial control frame can be transmitted and received during the association phase and negotiation phase between the first STA and the second STA.

[0140] Additionally or alternatively, the first STA may transmit a second frame to the second STA that includes information regarding whether the first power mode state is supported. The information regarding whether the first power mode state is supported may be included in, but is not limited to, an extended capability element.

[0141] Additionally or alternatively, the initial control frame may include at least one of modulation coding scheme (MCS) information, spatial stream information, and bandwidth information for reception of a first frame (e.g., a frame including data to be transmitted and received after the initial control frame). Furthermore, the initial control frame may include at least one set of antenna weigh vectors (AWVs) for beamforming. The first STA may perform beamforming based on at least one set of AWVs.

[0142] And, when the first STA is in the first power mode state, the reception antenna pattern of the first STA may be an omni-directional antenna pattern or a quasi-omni-directional antenna pattern. That is, the first STA may receive an initial control frame from the second STA based on the omni-directional antenna pattern or the quasi-omni-directional antenna pattern.

[0143] The first STA may transmit an initial control response frame to the initial control frame to the second STA (S820). For example, the first STA may transmit the initial control response frame to the second STA in the first power mode or the second power mode.

[0144] For example, a first STA may transmit an initial control response frame to a second STA based on a specific sector or AWV. Specifically, the first STA may decode / obtain at least one of at least one AWV set or sector ID set for beamforming included in the initial control frame. The first STA may receive the initial control response frame from the second STA using the at least one AWV set (e.g., using beamforming based on the at least one AWV set). Additionally or alternatively, the first STA may receive the initial control response frame from the second STA using a specific sector based on the sector ID (e.g., using specific sector-based beamforming). As an example of the present disclosure, at least one of at least one AWV set or sector ID (identifier) ​​set for beamforming may be transmitted from the second STA to the first STA in a sub-7 GHz band. However, this is only one embodiment, and at least one AWV set or sector ID set for beamforming may be transmitted from the second STA to the first STA in the millimeter wave band.

[0145] The first STA may receive a first frame from the second STA in a second power mode based on an initial control frame (S830). Here, the first frame may collectively refer to a frame containing data transmitted and received subsequent to the initial control frame / initial control response frame.

[0146] As an example of the present disclosure, the time period for switching from the first power mode to the second power mode may be based on i) a predefined first time period and ii) a second time period of the initial control frame or the first frame.

[0147] For example, the time period required to switch from the first power mode to the second power mode may be greater than a predefined first time period (e.g., one of a short inter-frame space (SIFS) or a point coordination function inter-frame space (PIFS)). Accordingly, the first STA may switch from the first power mode to the second power mode during the predefined first time period and the second time period.

[0148] And, the first time interval may include i) a time interval between an initial control frame and an initial control response frame or ii) a time interval between an initial control response frame and the first frame.

[0149] As an example of the present disclosure, a first STA may switch from a first power mode to a second power mode during a first predefined time period (e.g., a time period between an initial control frame and an initial control response frame) and a second time period of the initial control frame. At this time, the first STA may transmit an initial control response frame to a second STA in the second power mode state. In addition, padding bits may be mapped onto a field of the initial control frame corresponding to the second time period.

[0150] As another example of the present disclosure, the first STA may switch from the first power mode to the second power mode during a predefined first time period (e.g., the time period between the initial control response frame and the first frame) and a second time period of the first frame. Here, the second time period of the first frame may include a time period corresponding to an ultra-high reliability (UHR) preamble of the first frame or a UHR preamble.

[0151] As an example of the present disclosure, the initial control frame, the initial control response frame, and the first frame can be transmitted and received in a high frequency band (e.g., a millimeter wave band).

[0152] After the first frame transmission and reception is completed, the first STA may receive a control frame from the third STA. The third frame (or control frame) may include information (e.g., bandwidth, etc.) related to the first frame transmission and reception procedure. The first STA may receive the second frame and switch from the second power mode to the first power mode after a predefined third time period (e.g., SIFS or PIFS).

[0153] The method described in the example of FIG. 8 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 receive an initial control frame from a second STA through one or more transceivers (106) in a first power mode. The one or more processors (102) may transmit an initial control response frame to the initial control frame to the second STA through one or more transceivers (106). The one or more processors (102) may receive a first frame from the second STA through one or more transceivers (106) in a second power mode based on the initial control frame.

[0154] Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 8 or the examples described below when executed by one or more processors (102).

[0155] FIG. 9 is a flowchart illustrating a method performed by a second STA according to one embodiment of the present disclosure.

[0156] The second STA may transmit an initial control frame to the first STA in the first power mode (S910). The second STA may receive a second frame from the first STA containing information regarding whether the second power mode is supported. Accordingly, the second STA may confirm that the first STA can receive data in the second power mode. The configuration of the initial control frame has been described with reference to FIG. 8, and therefore, a duplicate description will be omitted.

[0157] The second STA can receive an initial control response frame for the initial control frame from the first STA (S920).

[0158] The second STA can transmit the first frame to the first STA in the second power mode based on the initial control frame (S930).

[0159] The method described in the example of FIG. 9 may be performed by the second device (200) of FIG. 1. For example, one or more processors (202) of the second device (200) of FIG. 1 may transmit an initial control frame to a first STA in a first power mode state via one or more transceivers (206). The one or more processors (202) may receive an initial control response frame for the initial control frame from the first STA via one or more transceivers (206). The one or more processors (202) may transmit a first frame to the first STA in a second power mode via one or more transceivers (206) based on the initial control frame.

[0160] Furthermore, one or more memories (204) of the second device (200) may store commands for performing the method described in the example of FIG. 9 or the examples described below when executed by one or more processors (202).

[0161] Below, we will describe in detail the low-power listening mode and its related operations.

[0162] Because the millimeter-wave frequency band is sensitive to phase noise, receiving high-order modulation may require more accurate phase-locked loop (PLL) operation, which can lead to higher power consumption. Furthermore, the ADC operation required to receive the extended bandwidth considered in the millimeter-wave frequency band can also result in higher power consumption. Furthermore, the directional antenna operation required by the millimeter-wave characteristics can result in additional power consumption.

[0163] Considering the power consumption described above, a new listening mode can be defined in the millimeter wave frequency band. A receiving device in the millimeter wave frequency band can operate in a low-power listening mode when operating in the listening mode in the "active" state.

[0164] Example 1

[0165] Embodiment 1 relates to a configuration applied when an STA and / or a PCP (or / and a PCP STA) operates in a low-power listening mode. That is, the following describes the operation and configuration when an STA and / or a PCP (or / and a PCP STA) is in a low-power listening mode.

[0166] The STA and / or PCP (or / and PCP STA) may perform a receiving operation through sector-level beamforming or may perform a quasi-omni receiving operation. Sector-level beamforming refers to a beamforming method that transmits a beam in units of sector areas for beam search, and may include sector-level training or sector-level sweep. Here, a beam sector may refer to a set of two or more adjacent beam(s).

[0167] Here, the bandwidth associated with the receiving operation (e.g., the receiving operation performed in low power listening mode) may be a defined minimum bandwidth (e.g., 80, 160 or 320 MHz).

[0168] Additionally, the order of the modulation associated with the receiving operation may be a defined minimum value (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), or 16 quadrature amplitude modulation (QAM)).

[0169] Additionally, the number of spatial streams associated with the receiving operation may be based on the minimum number of spatial streams supported. For example, if two spatial streams are supported, the receiving operation may be performed based on one spatial stream.

[0170] Example 1-1

[0171] Embodiment 1-1 relates to operations when an STA and / or a PCP (or / and a PCP STA) operates in a low-power listening mode. For example, an STA and / or a PCP (or / and a PCP STA) may perform the operations described below in a low-power listening mode based on the settings described in Embodiment 1.

[0172] The STA and / or PCP (or / and PCP STA) may perform sector-level beamforming in a low-power listening mode. For this purpose, control frames (e.g., an initial control frame (ICF), a multi-user (MU)-RTS, or a trigger frame of a separate variant, etc.) transmitted by the STA and / or PCP (or / and PCP STA) in a sub-7 GHz or millimeter band (e.g., 60 GHz) may be transmitted and received. The STA and / or PCP (or / and PCP STA) may transmit information about candidate sector(s) on which sector-level beamforming is to be performed through the control frames.

[0173] The ICF may include information about the full bandwidth and overall capabilities applicable to subsequent uplink transmissions and receptions (e.g., uplink transmissions and receptions performed after the ICF is transmitted and received). For example, the ICF may include information / capabilities about the MCS, bandwidth, and spatial streams for subsequent uplink transmissions and receptions.

[0174] The AP / PCP MLD can receive information related to an ICF transmission time transmitted by a non-AP STA / PCP STA via sub-7 GHz and / or information related to a low-power listening mode of the AP / PCP MLD. That is, the non-AP STA / PCP STA can transmit information related to an ICF to an AP / PCP MLD in a low-power listening mode (e.g., an STA in a low-power listening mode operation state) using sub-7 GHz. For example, the information related to the ICF transmission time may include information on a BI (beacon interval) at which ICF transmission is expected. The information related to the ICF transmission timing may include information on an exact transmission time of the ICF or a transmission time period of the ICF.

[0175] For example, when transmission by a non-AP / PCP STA directly utilizes full-bandwidth and full-capability transmission without utilizing ICF transmission, the information transmitted using sub-7 GHz may include information related to full-bandwidth and full-capability transmission (e.g., bandwidth, MCS, number of spatial streams, etc.).

[0176] For example, if ICF is not used, AP / PCP and non-AP / PCP STAs may transition from low-power listening mode to other modes (e.g., full-power mode) a certain amount of time before full-bandwidth, full-capability transmission is performed, and sector-level beamforming or antenna weight vector (AWV) adjustment may be performed.

[0177] Support for low power listening mode of AP / PCP (MLD) and / or non-AP / PCP STA (MLD) may be indicated through extended capability elements, etc.

[0178] For example, an AP / PCP (MLD) and / or a non-AP / PCP STA (MLD) may not transition from a low-power listening mode to a full-bandwidth or full-capability receiving mode on a particular link or channel. An AP / PCP (MLD) and / or a non-AP / PCP STA (MLD) may perform receiving operations using the settings applied in the low-power listening mode on a particular link or channel.

[0179] For example, the specific link or channel may be determined through negotiation between the AP / PCP (MLD) and the non-AP / PCP STA (MLD). For example, the specific link or channel may be determined by the AP / PCP (MLD) and the non-AP / PCP STA (MLD) exchanging frames to establish / determine the specific link or channel. As another example, the AP / PCP (MLD) may transmit a frame indicating the specific link or channel to the non-AP / PCP STA (MLD).

[0180] For example, the initiation of the low-power listening mode may be initiated in a default manner. That is, the initiation time, parameters, operation, etc. of the low-power listening mode may be defined in a default manner. As another example, the channel may be initiated in the low-power listening mode at the instruction of the AP / PCP (MLD) and / or at the request of a non-AP / PCP STA (MLD). That is, the channel may transmit and receive frames including information indicating the initiation of the low-power listening mode by the AP / PCP (MLD). Additionally or alternatively, the non-AP / PCP STA (MLD) may transmit and receive frames including information requesting the initiation of the low-power listening mode.

[0181] For example, information for an AP / PCP (MLD) to indicate a low-power listening mode and / or information for a non-AP / PCP STA (MLD) to request a low-power listening mode may include parameters and settings related to the low-power listening mode. For example, parameters and settings related to the low-power listening mode may include information such as a specific time, cycle, etc. to operate in the low-power listening mode.

[0182] Parameters and settings related to the low-power listening mode may be transmitted and received via the sub-7 GHz band. Additionally, parameters and settings related to the low-power listening mode may include instructions for quasi-omnidirectional or sector-level beamforming, information about candidate sector(s) during sector-level beamforming, and the like.

[0183] Example 2

[0184] Embodiment 2 relates to operations related to low-power listening mode. As illustrated in (a) of FIG. 10, a non-AP / PCP STA may transmit an ICF to the AP / PCP. Here, the ICF may include an MU-RTS frame, a variant frame, or / and a trigger frame of another variant.

[0185] For example, an AP / PCP can receive an ICF from a non-AP / PCP STA in a low-power listening mode. If the time it takes for the AP / PCP to switch to full power receiving mode for ICF reception is longer than SIFS, a certain amount of time (e.g., (a) of FIG. 10) may be required. ) may be provided.

[0186] For example, AP / PCP may be used for a certain amount of time (e.g., (a) of Fig. 10). ) and can switch from low power listening mode to full power receiving mode during SIFS. And, AP / PCP can transmit ICR (initial control response) to non-AP / PCP STA.

[0187] That is, (a) of FIG. 10 is about a method of using / allocating some of the time defined / allocated / indicated for ICF transmission for mode switching of AP / PCP when the time required to switch from low power listening mode to full power reception mode is SIFS or longer.

[0188] For example, the above-mentioned time of a certain size (e.g., (a) of Fig. 10) ) may be indicated / provided through MAC padding or a separate field that is not required for decoding the MAC packet. For example, information about the time of a certain size may be transmitted and received during the negotiation or association phase. In addition, information about the time of a certain size may be included in the negotiation / association request / response frame.

[0189] The above time of a certain size (e.g., (a) of Fig. 10) ) may be determined based on the time required to perform fine-granularity beamforming within a sector-level beamforming or quasi-omni-directional receiving procedure. Here, the beamforming operation of the AP / PCP and / or non-AP / PCP STA may proceed in the order of quasi-omni-directional beamforming, sector-level beamforming, and fine-granularity beamforming operations.

[0190] The ICF may include an AWV set for performing fine-grained beamforming. For example, to perform sector-level beamforming in a quasi-omnidirectional reception state, the ICF may include a sector ID set. The sector ID set may be information used for (previous) data transmission and reception between the AP / PCP and non-AP STA / PCP STA. If the elapsed time since the (previous) data transmission and reception is later than a predetermined time, the sector ID set may be a null set.

[0191] The ICF may include information for receiving subsequent data (e.g., data in (a) of FIG. 10), thereby preventing power waste in receiving devices. For example, the ICF may include MCS information, spatial stream information, bandwidth information, and the like required for data reception.

[0192] A non-AP / PCP STA can transmit information for data reception to the AP / PCP through a control frame transmission after the uplink transmission is completed. If the bandwidth used for the uplink transmission is a multiple of the basic bandwidth unit (e.g., 80, 160, 320 MHz), the control frame can be transmitted to the AP / PCP through the primary channel (e.g., the primary basic bandwidth unit) or multiple basic bandwidth units.

[0193] The AP / PCP can receive the control frame and switch to low-power listening mode reception mode after a certain period of time (e.g., SIFS, PIFS, etc.).

[0194] If the non-AP / PCP STA of Fig. 10 (a) is replaced with an AP / PCP, and the AP / PCP of Fig. 10 (a) is replaced with a non-AP / PCP STA, this corresponds to the operation according to Fig. 10 (b). That is, the operations of the non-AP / PCP STA and the AP / PCP, respectively, with respect to Fig. 10 (a) can be replaced / corresponded to the operations of the AP / PCP and the non-AP / PCP STA, respectively, with respect to Fig. 10 (b).

[0195] Example 3

[0196] Embodiment 3 relates to additional operations related to low-power listening mode. As illustrated in (a) of FIG. 11, a non-AP / PCP STA may transmit an ICF to the AP / PCP. Here, the ICF may include an MU-RTS frame, a variant frame, or / and a trigger frame of another variant.

[0197] Additionally or alternatively, the ICF may include an AWV set to support fine-grained beamforming. Furthermore, the ICF may include a sector ID set to enable sector-level beamforming when performing quasi-omnidirectional reception operations. The sector ID set may include information used in (previous) data transmissions between the AP / PCP and non-AP / PCP STAs. If a certain amount of time has elapsed since the (previous) data transmission, the sector ID set may be a null set.

[0198] Additionally or alternatively, the ICF may include information for subsequent data reception / transmission. For example, the ICF may include MCS information, spatial stream information, bandwidth information, etc. for data reception / transmission. In addition, the ICF may include information about a pre-UHR field of the data (e.g., information about LTF, STF repetition, etc.). The pre-UHR field may be a field that supports coexistence with existing users (e.g., DMG, EDMG) (e.g., DMG / EDMG LTF, STF, etc.).

[0199] As illustrated in (a) of FIG. 11, the AP / PCP can receive an ICF from a non-AP / PCP STA in a low-power listening mode. The AP / PCP can transmit an ICR (Initial Control Response) to the non-AP / PCP STA in the low-power listening mode. The AP / PCP can receive data from the non-AP / PCP STA based on the information included in the ICF.

[0200] Specifically, if the sum of i) SIFS and ii) duration value (δ) of the free UHR field (e.g., the value (δ) indicated / set by the duration field value of the UHR field) is less than the time required to switch from low power listening mode to full power receiving mode, additional overhead may be added to the free UHR field. For example, the repeat field of DMG / EDME LTF or STF may be included in the free UHR field.

[0201] As another example, if the time required to transition from low power listening mode to full power receiving mode is greater than SIFS, the AP / PCP may transition from low power listening mode to full power receiving mode during the SIFS and free UHR field period (δ).

[0202] Here, SIFS may mean a predefined interval between the time when the AP / PCP transmits an ICR to a non-AP / PCP STA and the time when the non-AP / PCP STA transmits data (e.g., a frame containing the data) to the AP / PCP.

[0203] That is, (a) of Fig. 11 is about a method of using the time of the pre-UHR field defined for coexistence (between legacy STAs) to switch the AP / PCP to the full power reception mode operation when it takes more than SIFS to switch from the low power listening mode to the full power reception mode. The AP / PCP can receive fields after the pre-UHR (e.g., data field, UHR field, etc.) in the full power reception mode state.

[0204] As an example of the present disclosure, the ICF may include information related to a free UHR field interval (δ) and / or information indicating that the interval is to be used for mode switching. The free UHR field interval (δ) may be determined based on the time required to perform fine-grained beamforming from a sector-level beamforming or quasi-omnidirectional beamforming (or, receiving) procedure. As described above, beamforming may be performed in the order of quasi-omnidirectional beamforming, sector-level beamforming, and fine-grained beamforming.

[0205] A non-AP / PCP STA can transmit a control frame to the AP / PCP after an uplink transmission (e.g., data transmission) is completed. That is, the non-AP / PCP STA can transmit information related to the uplink transmission (e.g., information about the bandwidth used for the uplink transmission, information indicating that the uplink transmission is completed, etc.) to the AP / PCP through the control frame. For example, the AP / PCP can receive a control frame from a non-AP / PCP STA in a full power reception mode.

[0206] When the bandwidth used for uplink transmission is a multiple of the basic bandwidth unit (e.g., 80 MHz, 160 MHz, 320 MHz, etc.), the control frame can be transmitted over the primary channel (e.g., the primary basic bandwidth unit) or multiple basic bandwidth units. The AP / PCP can receive the control frame and switch to a low-power listening mode after a certain period of time (e.g., SIFS, PIFS, etc.).

[0207] If the non-AP / PCP STA of Fig. 11 (a) is replaced with an AP / PCP, and the AP / PCP of Fig. 11 (a) is replaced with a non-AP / PCP STA, this corresponds to the operation according to Fig. 11 (b). That is, the operations of the non-AP / PCP STA and the AP / PCP, respectively, with respect to Fig. 11 (a) can be replaced / corresponded to the operations of the AP / PCP and the non-AP / PCP STA, respectively, with respect to Fig. 11 (b).

[0208] Example 4

[0209] Example 4 relates to additional operations related to low-power listening mode. As illustrated in (a) of FIG. 12, a non-AP / PCP STA may transmit an ICF to the AP / PCP. The ICF may include an MU-RTS frame, a variant frame, or / and a trigger frame of another variant.

[0210] Additionally or alternatively, the ICF may include an AWV set to support fine-grained beamforming. Furthermore, the ICF may include a sector ID set to enable sector-level beamforming when performing quasi-omnidirectional reception operations. The sector ID set may include information used in (previous) data transmissions between the AP / PCP and non-AP / PCP STAs. If a certain amount of time has elapsed since the (previous) data transmission, the sector ID set may be a null set.

[0211] Additionally or alternatively, the ICF may include information for subsequent data reception / transmission. For example, the ICF may include MCS information, spatial stream information, bandwidth information, etc. for data reception / transmission.

[0212] The UHR preamble illustrated in (a) of FIG. 12 may include at least one field for supporting a UHR PPDU. For example, the UHR preamble may include a UHL LTF field, a UHR STF field, etc.

[0213] Specifically, i) the time interval of SIFS and ii) UHR preamble ( )(e.g., the time interval during which the UHR preamble is allocated / set) is less than the time required to switch from low power listening mode to full power receiving mode, additional overhead may be added to the UHR preamble. For example, the UHR preamble may include repetition fields of UHR LTF, STF, etc.

[0214] As another example, if the time taken to switch from low power listening mode to full power receiving mode is greater than SIFS, the AP / PCP may use SIFS and UHR preamble period ( ) can switch from low power listening mode to full power receiving mode.

[0215] As an example of the present disclosure, the ICF comprises a UHR preamble section ( ) and / or information indicating that the above section will be used for mode change. Based on the time required to perform fine-grained beamforming from a sector-level beamforming or quasi-omnidirectional beamforming (or, receiving) procedure, the UHR preamble section ( ) may be determined. As described above, beamforming may proceed in the order of quasi-forward beamforming, sector-level beamforming, and fine-grained beamforming.

[0216] A non-AP / PCP STA can transmit a control frame to the AP / PCP after an uplink transmission (e.g., data transmission) is completed. That is, the non-AP / PCP STA can transmit information related to the uplink transmission (e.g., information about the bandwidth used for the uplink transmission, information indicating that the uplink transmission is completed, etc.) to the AP / PCP through the control frame. For example, the AP / PCP can receive a control frame from a non-AP / PCP STA in a full power reception mode.

[0217] When the bandwidth used for uplink transmission is a multiple of the basic bandwidth unit (e.g., 80 MHz, 160 MHz, 320 MHz, etc.), the control frame can be transmitted over the primary channel (e.g., the primary basic bandwidth unit) or multiple basic bandwidth units. The AP / PCP can receive the control frame and switch to a low-power listening mode after a certain period of time (e.g., SIFS, PIFS, etc.).

[0218] If the non-AP / PCP STA of Fig. 12 (a) is replaced with an AP / PCP, and the AP / PCP of Fig. 12 (a) is replaced with a non-AP / PCP STA, this corresponds to the operation according to Fig. 12 (b). That is, the operations of the non-AP / PCP STA and the AP / PCP, respectively, with respect to Fig. 12 (a) can be replaced / corresponded to the operations of the AP / PCP and the non-AP / PCP STA, respectively, with respect to Fig. 12 (b).

[0219] The above-described embodiments of the present disclosure relate to a low-power listening mode for additional power reduction of APs / PCPs and / or non-AP / PCP STAs operating in a power-saving mode in a high-frequency band (e.g., millimeter-wave band, etc.). Furthermore, the above-described embodiments of the present disclosure relate to a method for transitioning from a low-power listening mode to a receiving mode appropriate for the properties of received data, and a method for addressing the lack of time required for mode switching.

[0220] By various embodiments of the present disclosure, greater power savings can be achieved than the low-power listening mode proposed in the existing sub-7 GHz band.

[0221] The embodiments described above are combinations of components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to form embodiments of the present disclosure by combining some components and / or features. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is self-evident that claims that do not have an explicit citation relationship in the patent claims may be combined to form embodiments or incorporated as new claims through post-application amendments.

[0222] It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms without departing from the essential characteristics thereof. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents of the present disclosure are intended to be included within the scope of the present disclosure.

[0223] The scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) that cause operations according to the methods of various embodiments to be executed on a device or a computer, and a non-transitory computer-readable medium having such software or instructions stored thereon and executable on the device or computer. Instructions that can be used to program a processing system to perform the features described in the present disclosure can be stored on / in a storage medium or a computer-readable storage medium, and a computer program product including such a storage medium can be used to implement the features described in the present disclosure. The storage medium can include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. The memory optionally includes one or more storage devices remotely located from the processor(s). The memory or, alternatively, the non-volatile memory device(s) within the memory comprise a non-transitory computer-readable storage medium. The features described in this disclosure may be incorporated into software and / or firmware stored on any of the machine-readable media, which may control the hardware of the processing system and allow the processing system to interact with other mechanisms that utilize results according to embodiments of the present disclosure. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0224] The method proposed in this disclosure is explained with a focus on examples applied to IEEE 802.11-based systems, but can be applied to various wireless LANs or wireless LANs in addition to IEEE 802.11-based systems.

Claims

1. A step of receiving an initial control frame from a second STA by a first station (STA) in a first power mode; A step of transmitting an initial control response frame for the initial control frame by the first STA to the second STA; and A step of receiving a first frame from the second STA by the first STA in a second power mode based on the initial control frame, A method wherein the time period for switching from the first power mode to the second power mode is based on i) a predefined first time period and ii) a second time period of the initial control frame or the first frame.

2. In paragraph 1, A method wherein at least one of the size of the bandwidth, the number of spatial streams, the order of modulation, or the power magnitude supported in the first power mode is smaller than at least one of the size of the bandwidth, the number of spatial streams, the order of modulation, or the power magnitude supported in the second power mode.

3. In paragraph 1, The method wherein the first time interval is one of a short inter-frame space (SIFS) or a point coordination function inter-frame space (PIFS).

4. In paragraph 3, A method according to claim 1, wherein the first time period comprises: i) a time period between the initial control frame and the initial control response frame, or ii) a time period between the initial control response frame and the first frame.

5. In paragraph 1, The first STA is switched from the first power mode to the second power mode during the second time period and the first time period of the initial control frame, A method wherein the initial control response frame is transmitted from the first STA to the second STA in the second power mode state.

6. In paragraph 1, A method wherein the second time period of the first frame includes a time period corresponding to a UHR (ultra-high reliability) preamble or a UHR preamble of the first frame.

7. In paragraph 1, A method wherein the initial control frame includes at least one of MCS (modulation coding scheme) information, spatial stream information, and bandwidth information for receiving the first frame.

8. In paragraph 1, The configuration information related to the initial control frame is transmitted to the first STA or the second STA at sub 7 GHz, A method wherein the initial control frame, the initial control response frame and the first frame are transmitted and received in a millimeter wave band.

9. In paragraph 1, A method wherein the initial control frame is at least one of a multi-user ready to send (RTS) trigger frame or a trigger frame of a specific variant.

10. In paragraph 1, A method in which padding bits are mapped onto fields of the initial control frame corresponding to the second time interval.

11. In paragraph 1, The initial control frame includes at least one of an antenna weigh vector (AWV) set or a sector ID (identifier) set for beamforming, A method wherein beamforming based on at least one AWV set or sector ID set is performed by the first STA.

12. In paragraph 1, A method in which a second frame containing information related to whether the first power mode state is supported is transmitted from the first STA to the second STA.

13. In paragraph 1, A method wherein, based on the first STA being in the first power mode state, the receiving antenna pattern of the first STA is an omni-directional antenna pattern or a quasi-omni-directional antenna pattern.

14. In paragraph 1, A method wherein at least one of at least one AWV set or sector ID (identifier) set for beamforming is transmitted to the first STA or the second STA in sub-7 GHz.

15. In the first station (STA), the first STA: 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: In the first power mode, an initial control frame is received from the second STA through the one or more transceivers; Transmitting an initial control response frame for the initial control frame to the second STA through the one or more transceivers; and Based on the initial control frame, the first frame is set to be received from the second STA through the one or more transceivers in the second power mode, A first STA, wherein the time period for switching from the first power mode to the second power mode is based on i) a predefined first time period and ii) a second time period of the initial control frame or the first frame.

16. A step of transmitting an initial control frame to a first STA in a first power mode state by a second station (STA); A step of receiving an initial control response frame for the initial control frame from the first STA by the second STA; and Based on the initial control frame, a step of transmitting a first frame to the first STA in a second power mode state by the second STA, A method wherein the time period for switching from the first power mode to the second power mode is based on i) a predefined first time period and ii) a second time period of the initial control frame or the first frame.

17. In the second station (STA), the second STA: 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 an initial control frame to a first STA in a first power mode state via the one or more transceivers; Receiving an initial control response frame for the initial control frame from the first STA through the one or more transceivers; and Based on the initial control frame, the first frame is set to be transmitted to the first STA in the second power mode state through the one or more transceivers, A second STA, wherein the time period for switching from the first power mode to the second power mode is based on i) a predefined first time period and ii) a second time period of the initial control frame or the first frame.

18. In a processing device configured to control a station (STA) in a wireless local area network (WLAN) 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.

19. 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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