Flexible power saving in the uplink of wireless LAN systems

Abstract

The present disclosure relates to dynamic power saving in the uplink of a wireless LAN system. According to an embodiment of the present disclosure, a method performed by an AP configured to operate in a wireless LAN system comprises: entering a listening state; receiving an initial control frame (ICF) from a STA (station) to initiate uplink (UL) transmission based on restricted capability in the listening state; switching from the listening state to a frame switching state in response to receiving the ICF; receiving UL data from the STA based on normal capability in the frame switching state; and switching from the frame switching state to the listening state in response to transmitting an acknowledgment (ACK) frame for the UL data.

Description

Technology Field

[0001] This disclosure relates to dynamic power saving in the uplink of a wireless LAN system. Background Technology

[0002] Next-generation Wi-Fi (e.g., IEEE 802.11be and / or later) aims to support ultra-high reliability when transmitting signals to STAs, and to achieve this, various technologies are being considered to support high throughput, low latency, and extended range. For example, while APs can be powered at all times, power reduction may be required in network environments where multiple APs exist, as the amount of power consumed by the APs is high. The problem to be solved

[0003] The present disclosure provides a method and apparatus for dynamic power saving in the uplink of a wireless LAN system. means of solving the problem

[0004] According to an embodiment of the present disclosure, a method performed by an AP configured to operate in a wireless LAN system comprises: entering a listening state; receiving an initial control frame (ICF) from a STA (station) to start uplink (UL) transmission based on restricted capability in the listening state; switching from the listening state to a frame switching state in response to receiving the ICF; receiving UL data from the STA based on normal capability in the frame switching state; and switching from the frame switching state to the listening state in response to transmitting an acknowledgment (ACK) frame for the UL data.

[0005] According to an embodiment of the present disclosure, a method performed by an STA configured to operate in a wireless LAN system comprises: transmitting an initial control frame (ICF) to an access point (AP) to initiate uplink (UL) transmission; and transmitting UL data to the AP, wherein the AP is configured to: receive the ICF from the STA based on a restricted capability in a listening state; switch from the listening state to a frame switching state in response to receiving the ICF; and switch from the frame switching state to the listening state in response to transmitting an acknowledgment (ACK) frame for the UL data.

[0006] In various embodiments, devices for implementing the methods described above are provided. Effects of the invention

[0007] The present disclosure may have various advantageous effects.

[0008] For example, the AP / STA can operate in a flexible power saving mode to reduce unnecessary power consumption during uplink data transmission.

[0009] The advantageous effects obtainable through specific embodiments of the present disclosure are not limited to those listed above. For example, there may be various technical effects that a person skilled in the art can understand and / or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein and may include various effects that can be understood or derived from the technical features of the present disclosure. Brief explanation of the drawing

[0010] FIG. 1 shows an example of a transmitting device and / or receiving device of the present disclosure. Figure 2 is a conceptual diagram showing the structure of a wireless LAN (WLAN). Figure 3 is a diagram illustrating a general link setup process. Figure 4 illustrates an example of a multi-link (ML). FIG. 5 shows a modified example of a transmitting device and / or receiving device of the present disclosure. FIG. 6 illustrates an example of a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received in an STA of the present disclosure. Figure 7 is a diagram showing the arrangement of resource units (RU) used for a 20 MHz PPDU. Figure 8 is a diagram showing the arrangement of resource units (RU) used for a 40 MHz PPDU. Figure 9 is a diagram showing the arrangement of resource units (RU) used for an 80 MHz PPDU. Figure 10 shows the operation according to UL-MU. Figure 11 shows an example of a channel used / supported / defined within the 2.4 GHz band. FIG. 12 illustrates an example of a channel used / supported / defined within the 5 GHz band. FIG. 13 illustrates an example of a channel used / supported / defined within the 6 GHz band. Figure 14 shows an example of a MAC frame header. Figure 15 shows an example of a random backoff procedure. Figure 16 illustrates an example of a procedure related to NAV settings. Figure 17 shows an example of per-link power saving operation. FIG. 18 shows an example of a power management operation according to an embodiment of the present disclosure. Figure 19 shows an example of EMLSR operation. FIG. 20 illustrates an example of a method performed by AP for flexible power saving according to an embodiment of the present disclosure. FIG. 21 shows an example of signal flow between AP and STA for flexible power saving according to an embodiment of the present disclosure. FIG. 22 shows an example of a frame sequence for UL transmission when the AP operates as a dynamic PS according to an embodiment of the present disclosure. Specific details for implementing the invention

[0011] In the present disclosure, “A or B” may mean “only A,” “only B,” or “both A and B.” Alternatively, in the present disclosure, “A or B” may be interpreted as “A and / or B.” For example, in the present disclosure, “A, B or C” may mean “only A,” “only B,” “only C,” or “any combination of A, B and C.”

[0012] A slash ( / ) or a comma used in the present disclosure may mean “and / or.” For example, “A / B” may mean “A and / or B.” Accordingly, “A / B” may mean “only A,” “only B,” or “both A and B.” For example, “A, B, C” may mean “A, B or C.”

[0013] In the present disclosure, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Additionally, in the present disclosure, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted as synonymous with “at least one of A and B.”

[0014] Additionally, parentheses used in this disclosure may mean “for example.” Specifically, when indicated as “control information (UHR-Signal field),” the “UHR-Signal field” may be proposed as an example of “control information.” In other words, the “control information” of this disclosure is not limited to the “UHR-Signal field,” and the “UHR-Signal field” may be proposed as an example of “control information.” Furthermore, even when indicated as “control information (UHR-Signal field),” the “UHR-Signal field” may be proposed as an example of “control information.”

[0015] Additionally, “a / an” as used in this disclosure may mean “at least one” or “one or more.” Also, terms ending in “(s)” may mean “at least one” or “one or more.”

[0016] Additionally, the expressions “based on,” “on the basis of,” or “according to” as used in this disclosure mean “based at least in part on,” and do not mean “based only on one.”

[0017] Technical features described individually within one drawing in this disclosure may be implemented individually or simultaneously.

[0018] The following examples of the present disclosure may be applied to various wireless communication systems. For example, the following examples of the present disclosure may be applied to wireless local area network (WLAN) systems. For example, the present disclosure may be applied to IEEE 802.11a / g / n / ac / ax / be / bn standards. Additionally, the examples of the present disclosure may be applied to Ultra High Reliability (UHR) standards or next-generation wireless LAN standards that enhance IEEE 802.11bn. Furthermore, the examples of the present disclosure may be applied to mobile communication systems. For example, they may be applied to mobile communication systems based on Long Term Evolution (LTE) and its evolution based on 3GPP (3rd Generation Partnership Project) standards.

[0019] To explain the technical features of the present disclosure, the technical features to which the present disclosure can be applied are described below.

[0020] FIG. 1 shows an example of a transmitting device and / or receiving device of the present disclosure.

[0021] An example of FIG. 1 can perform various technical features described below. FIG. 1 relates to at least one STA (station). For example, the STA (110, 120) of the present disclosure may also be referred to by various names such as mobile terminal, wireless device, Wireless Transmit / Receive Unit (WTRU), User Equipment (UE), Mobile Station (MS), Mobile Subscriber Unit, or simply user. The STA (110, 120) of the present disclosure may also be referred to by various names such as network, base station, Node-B, Access Point (AP), repeater, router, relay, etc. The STA (110, 120) of the present disclosure may also be referred to by various names such as receiving apparatus, transmitting device, receiving STA, transmitting STA, receiving device, transmitting device, etc.

[0022] For example, the STA (110, 120) can perform the role of an access point (AP) or a non-AP. That is, the STA (110, 120) of the present disclosure can perform the functions of an AP and / or a non-AP. In the present disclosure, an AP may also be indicated as an AP STA.

[0023] The STA (110, 120) of the present disclosure may support various communication standards other than the IEEE 802.11 standard. For example, it may support communication standards according to 3GPP standards (e.g., LTE, LTE-A, 5G NR standards). In addition, the STA of the present disclosure may be implemented in various devices such as mobile phones, vehicles, and personal computers. Furthermore, the STA of the present disclosure may support communication for various communication services such as voice calls, video calls, data communication, and self-driving.

[0024] In the present disclosure, the STA (110, 120) may include a medium access control (MAC) that complies with the specifications of the IEEE 802.11 standard and a physical layer interface for the wireless medium.

[0025] Based on side drawing (a) of Fig. 1, STA (110, 120) is described as follows.

[0026] The first STA (110) may include a processor (111), memory (112), and a transceiver (113). The illustrated processor, memory, and transceiver may each be implemented as separate chips, or at least two blocks / functions may be implemented through a single chip.

[0027] The transceiver (113) of the first STA performs the operation of transmitting and receiving signals. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0028] For example, the first STA (110) can perform the intended operation of the AP. For example, the processor (111) of the AP can receive a signal through the transceiver (113), process the received signal, generate a transmitted signal, and perform control for transmitting the signal. The memory (112) of the AP can store the signal received through the transceiver (113) (i.e., the received signal) and the signal to be transmitted through the transceiver (i.e., the transmitted signal).

[0029] For example, the second STA (120) can perform the intended operation of a Non-AP STA. For example, the non-AP transceiver (123) performs the operation of transmitting and receiving signals. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0030] For example, the processor (121) of the Non-AP STA can receive a signal through the transceiver (123), process the received signal, generate a transmitted signal, and perform control for transmitting the signal. The memory (122) of the Non-AP STA can store the signal received through the transceiver (123) (i.e., the received signal) and can store the signal to be transmitted through the transceiver (i.e., the transmitted signal).

[0031] For example, the operation of the device indicated as AP in the following specification may be performed in the first STA (110) or the second STA (120). For example, if the first STA (110) is the AP, the operation of the device indicated as AP is controlled by the processor (111) of the first STA (110), and related signals may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (110). Additionally, control information related to the operation of the AP or the transmission / reception signals of the AP may be stored in the memory (112) of the first STA (110). Additionally, if the second STA (110) is the AP, the operation of the device indicated as AP is controlled by the processor (121) of the second STA (120), and related signals may be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the AP or the transmission / reception signals of the AP can be stored in the memory (122) of the second STA (110).

[0032] For example, the operation of a device indicated as non-AP (or User-STA) in the following specification may be performed in the STA (110) or the second STA (120). For example, if the second STA (120) is non-AP, the operation of the device indicated as non-AP is controlled by the processor (121) of the second STA (120), and related signals may be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). Additionally, control information related to the operation of the non-AP or the transmission / reception signals of the AP may be stored in the memory (122) of the second STA (120). For example, if the first STA (110) is a non-AP, the operation of the device marked as non-AP is controlled by the processor (111) of the first STA (110), and the related signal can be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (120). Additionally, control information related to the operation of the non-AP or the transmission / reception signal of the AP can be stored in the memory (112) of the first STA (110).

[0033] In the following specification, a device referred to as (transmission / reception) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmission / reception) Terminal, (transmission / reception) device, (transmission / reception) apparatus, network, etc. may refer to the STA (110, 120) of FIG. 1. For example, a device indicated without specific drawing symbols as (transmission / reception) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmission / reception) Terminal, (transmission / reception) device, (transmission / reception) apparatus, network, etc. may also refer to the STA (110, 120) of FIG. 1. For example, in the following example, the operation of various STAs transmitting and receiving signals (e.g., PPPDU) may be performed by the transceiver (113, 123) of FIG. 1. Additionally, in the following example, the operation of various STAs generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals may be performed by the processor (111, 121) of FIG. 1.For example, an example of an operation to generate a transmission / reception signal or to perform data processing or operations in advance for a transmission / reception signal may include: 1) an operation to determine / acquire / configure / operate / decode / encode bit information of sub-fields (SIG, STF, LTF, Data) included in the PPDU; 2) an operation to determine / configure / acquire time resources or frequency resources (e.g., subcarrier resources) used for sub-fields (SIG, STF, LTF, Data) included in the PPDU; 3) an operation to determine / configure / acquire specific sequences (e.g., pilot sequence, STF / LTF sequence, extra sequence applied to SIG) used for sub-fields (SIG, STF, LTF, Data) included in the PPDU; 4) a power control operation and / or power saving operation applied to the STA; and 5) an operation related to determining / acquiring / configuring / operating / decoding / encoding of an ACK signal. In addition, in the following example, various information (e.g., information related to fields, subfields, control fields, parameters, power, etc.) used by various STAs for determining / acquiring / configuring / calculating / decoding / encoding of transmission and reception signals can be stored in the memory (112, 122) of FIG. 1.

[0034] The device / STA of the aforementioned supplementary drawing (a) of FIG. 1 can be modified as shown in supplementary drawing (b) of FIG. 1. Below, the STA (110, 120) of the present disclosure will be described based on supplementary drawing (b) of FIG. 1.

[0035] For example, the transceiver (113, 123) shown in side drawing (b) of FIG. 1 can perform the same function as the transceiver shown in side drawing (a) of FIG. 1 described above. For example, the processing chip (114, 124) shown in side drawing (b) of FIG. 1 may include a processor (111, 121) and a memory (112, 122). The processor (111, 121) and the memory (112, 122) shown in side drawing (b) of FIG. 1 can perform the same function as the processor (111, 121) and the memory (112, 122) shown in side drawing (a) of FIG. 1 described above.

[0036] The mobile terminal, wireless device, Wireless Transmit / Receive Unit (WTRU), User Equipment (UE), Mobile Station (MS), Mobile Subscriber Unit, user, User STA, network, Base Station, Node-B, AP (Access Point), repeater, router, relay, receiving device, transmitting device, receiving STA, transmitting STA, receiving Device, transmitting Device, receiving Apparatus, and / or transmitting Apparatus described below may refer to the STA (110, 120) shown in side drawings (a) / (b) of FIG. 1, or the processing chip (114, 124) shown in side drawing (b) of FIG. 1. That is, the technical features of the present disclosure may be performed in the STA (110, 120) shown in side drawings (a) / (b) of FIG. 1, or only in the processing chip (114, 124) shown in side drawing (b) of FIG. 1. For example, the technical feature of the transmitting STA transmitting a control signal may be understood as a technical feature in which a control signal generated in the processor (111, 121) shown in side drawings (a) / (b) of FIG. 1 is transmitted through the transceiver (113, 123) shown in side drawings (a) / (b) of FIG. 1. Alternatively, the technical feature of the transmitting STA transmitting a control signal may be understood as a technical feature in which a control signal to be transmitted from the processing chip (114, 124) shown in side drawing (b) of FIG. 1 is generated to the transceiver (113, 123).

[0037] For example, the technical feature of the receiving STA receiving a control signal can be understood as the technical feature of the control signal being received by the transceiver (113, 123) shown in side view (a) of FIG. 1. Alternatively, the technical feature of the receiving STA receiving a control signal can be understood as the technical feature of the control signal received by the transceiver (113, 123) shown in side view (a) of FIG. 1 being acquired by the processor (111, 121) shown in side view (a) of FIG. 1. Alternatively, the technical feature of the receiving STA receiving a control signal can be understood as the technical feature of the control signal received by the transceiver (113, 123) shown in side view (b) of FIG. 1 being acquired by the processing chip (114, 124) shown in side view (b) of FIG. 1.

[0038] Referring to side view (b) of FIG. 1, software code (115, 125) may be included in memory (112, 122). The software code (115, 125) may include instructions that control the operation of the processor (111, 121). The software code (115, 125) may be included in various programming languages.

[0039] The processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and / or data processing devices. The processor may be an application processor (AP). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may be a SNAPDRAGON® series processor manufactured by Qualcomm®, an EXYNOS® series processor manufactured by Samsung®, an A series processor manufactured by Apple®, a HELIO® series processor manufactured by MediaTek®, an ATOM® series processor manufactured by INTEL®, or a processor enhanced therefrom.

[0040] In the present disclosure, an uplink may refer to a link for communication from a non-AP STA to an AP STA, and uplink PPDUs / packets / signals, etc. may be transmitted through the uplink. Additionally, in the present disclosure, a downlink may refer to a link for communication from an AP STA to a non-AP STA, and downlink PPDUs / packets / signals, etc. may be transmitted through the downlink.

[0041] Figure 2 is a conceptual diagram showing the structure of a wireless LAN (WLAN).

[0042] The top of Figure 2 shows the structure of the IEEE (Institute of Electrical and Electronic Engineers) 802.11 infrastructure BSS (basic service set).

[0043] Referring to the top of FIG. 2, the wireless LAN system may include one or more infrastructure BSSs (200, 205) (hereinafter BSS). The BSS (200, 205) is a set of APs and STAs, such as an AP (access point, 225) and STA1 (Station, 200-1), that can communicate with each other by successfully synchronizing, and is not a concept referring to a specific area. The BSS (205) may include one or more STAs (205-1, 205-2) that can be combined with one AP (230).

[0044] The BSS may include at least one STA, an AP (225, 230) that provides a distribution service, and a distribution system (DS, 210) that connects multiple APs.

[0045] A distributed system (210) can implement an extended service set (ESS, 240) by connecting multiple BSSs (200, 205). The term ESS (240) may be used to refer to a network formed by connecting one or more APs through the distributed system (210). APs included in a single ESS (240) may have the same service set identification (SSID).

[0046] The portal (portal, 220) can act as a bridge to connect a wireless LAN network (IEEE 802.11) with another network (e.g., 802.X).

[0047] In a BSS like the one at the top of Fig. 2, a network between APs (225, 230) and a network between APs (225, 230) and STAs (200-1, 205-1, 205-2) can be implemented. However, it may also be possible to establish a network between STAs and perform communication without APs (225, 230). A network that establishes a network between STAs and performs communication without APs (225, 230) is defined as an ad-hoc network or an independent basic service set (IBSS).

[0048] The bottom of Fig. 2 is a conceptual diagram showing IBSS.

[0049] Referring to the bottom of Fig. 2, the IBSS is a BSS that operates in ad-hoc mode. Since the IBSS does not include an AP, there is no centralized management entity that performs management functions centrally. That is, in the IBSS, the STAs (250-1, 250-2, 250-3, 255-4, 255-5) are managed in a distributed manner. In the IBSS, all STAs (250-1, 250-2, 250-3, 255-4, 255-5) can be mobile STAs, and since access to the distributed system is not allowed, they form a self-contained network.

[0050] Figure 3 is a diagram illustrating a general link setup process.

[0051] In the described S310 step, the STA can perform a network discovery operation. The network discovery operation may include the STA's scanning operation. That is, in order for the STA to access a network, it must find a network it can join. Before joining a wireless network, the STA must identify a compatible network, and the process of identifying networks existing in a specific area is called scanning. Scanning methods include active scanning and passive scanning.

[0052] Figure 3 illustrates a network discovery operation that includes an active scanning process as an example. In active scanning, the STA performing the scanning moves between channels and transmits a probe request frame to search for nearby APs, and waits for a response. The responder transmits a probe response frame as a response to the probe request frame to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame from the BSS of the channel being scanned. In a BSS, the AP becomes the responder because it transmits the beacon frame, whereas in an IBSS, the responder is not constant because STAs within the IBSS take turns transmitting the beacon frame. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 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 in the same way (i.e., transmit and receive probe request / response on channel 2).

[0053] Although not shown in the example of Fig. 3, scanning operations may also be performed using a passive scanning method. An STA performing scanning based on passive scanning can wait for a beacon frame while switching between channels. A beacon frame is one of the management frames in IEEE 802.11, which announces the presence of a wireless network and is periodically transmitted to allow a scanning STA to find the wireless network and join it. In a BSS, the AP performs the role of periodically transmitting beacon frames, while in an IBSS, STAs within the IBSS take turns transmitting beacon frames. When a scanning STA receives a beacon frame, it stores the information about the BSS included in the beacon frame and records the beacon frame information in each channel while moving to another channel. An STA that has received a beacon frame can store the BSS-related information included in the received beacon frame, move to the next channel, and perform scanning in the next channel in the same manner.

[0054] The STA that discovered the network can perform an authentication process through 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 later. The authentication process of S320 may include the STA sending an authentication request frame to the AP, and the AP sending an authentication response frame to the STA in response. The authentication frame used in the authentication request / response corresponds to a management frame.

[0055] The authentication frame may include information regarding the authentication algorithm number, authentication transaction sequence number, status code, challenge text, RSN (Robust Security Network), Finite Cyclic Group, etc.

[0056] The STA can send an authentication request frame to the AP. Based on the information contained in the received authentication request frame, the AP can determine whether to allow authentication for the STA. The AP can provide the result of the authentication process to the STA through an authentication response frame.

[0057] A successfully authenticated STA may perform an association process based on step S330. The association process includes the STA sending an association request frame to the AP, and in response, the AP sending an association response frame to the STA. For example, the association request frame may include information regarding various capabilities, beacon listen interval, service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operating classes, Traffic Indication Map Broadcast request, interworking service capabilities, etc. For example, a connection response frame may include information related to various capabilities, status code, AID (Association ID), support rate, EDCA (Enhanced Distributed Channel Access) parameter set, RCPI (Received Channel Power Indicator), RSNI (Received Signal to Noise Indicator), mobility domain, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS map, etc.

[0058] Subsequently, in step S340, the STA may perform a security setup process. The security setup process of step S340 may include, for example, a process of setting up a private key through a 4-way handshake via an EAPOL (Extensible Authentication Protocol over LAN) frame.

[0059] Figure 4 illustrates an example of a multi-link (ML).

[0060] As illustrated in FIG. 4, multiple multi-link devices (MLDs) can communicate through a multi-link. The MLDs can be classified into an AP MLD containing multiple AP STAs and a non-AP MLD containing multiple non-AP STAs. That is, the AP MLD may include affiliated APs (i.e., AP STAs), and the non-AP MLD may include affiliated STAs (i.e., non-AP STAs, or user-STAs).

[0061] A multilink may include a first link and a second link, and different channels / subchannels / frequency resources may be assigned to the first and second links. The first and second multilinks may be identified by a link ID of 4 bits (or other n bits). The first and second links may be configured in the same 2.4 GHz, 5 GHz, or 6 GHz band. Alternatively, the first link and the link may be configured in different bands.

[0062] The AP MLD of FIG. 4 includes three affiliated APs. In one example of FIG. 4, AP1 may operate in the 2.4 GHz band, AP2 may operate in the 5 GHz band, and AP3 may operate in the 6 GHz band. In one example of FIG. 4, the first link in which AP1 and non-AP1 operate may be defined as a channel / subchannel / frequency resource within the 2.4 GHz band. Additionally, in one example of FIG. 4, the second link in which AP2 and non-AP2 operate may be defined as a channel / subchannel / frequency resource within the 5 GHz band. Additionally, in one example of FIG. 4, the third link in which AP3 and non-AP3 operate may be defined as a channel / subchannel / frequency resource within the 6 GHz band.

[0063] In one example of FIG. 4, AP1 can initiate a multilink setup procedure (ML setup procedure) by transmitting an Association Request frame to non-AP STA1. In one example of FIG. 4, non-AP STA1 can transmit an Association Response frame in response to the Association Request frame. Each AP (e.g., AP1 / 2 / 3) shown in FIG. 4 may be the same as the AP shown in FIG. 1 and / or FIG. 2, and each non-AP (e.g., non-AP1 / 2 / 3) shown in FIG. 4 may be the same as the STA shown in FIG. 1 and / or FIG. 2 (i.e., user-STA or non-AP STA).

[0064] The specific features of the present disclosure are not limited to the specific features of FIG. 4. That is, the number of links can be defined in various ways, and a plurality of links can be defined in various ways within at least one band.

[0065] FIG. 5 shows a modified example of a transmitting device and / or receiving device of the present disclosure.

[0066] The device illustrated in FIGS. 1 to 4 (e.g., AP STA, non-AP STA) can be modified as in FIG. 5. The transceiver (530) of FIG. 5 may be identical to the transceiver (113, 123) of FIG. 1. The transceiver (530) of FIG. 5 may include a receiver and a transmitter.

[0067] The processor (510) of FIG. 5 may be the same as the processor (111, 121) of FIG. 1. Alternatively, the processor (510) of FIG. 5 may be the same as the processing chip (114, 124) of FIG. 1.

[0068] The memory (150) of FIG. 5 may be the same as the memory (112, 122) of FIG. 1. Alternatively, the memory (150) of FIG. 5 may be a separate external memory different from the memory (112, 122) of FIG. 1.

[0069] Referring to FIG. 5, a power management module (511) manages power for a processor (510) and / or a transceiver (530). A battery (512) supplies power to the power management module (511). A display (513) outputs results processed by the processor (510). A keypad (514) receives input to be used by the processor (510). The keypad (514) may be displayed on the display (513). A SIM card (515) may be an integrated circuit used to securely store an international mobile subscriber identity (IMSI) and associated keys used to identify and authenticate a subscriber in a mobile device such as a mobile phone and a computer.

[0070] Referring to FIG. 5, the speaker (540) can output sound-related results processed by the processor (510). The microphone (541) can receive sound-related inputs to be used by the processor (510).

[0071] FIG. 6 illustrates an example of a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received in an STA of the present disclosure.

[0072] The STA of the present disclosure (e.g., AP STA, non-AP STA, AP MLD, non-AP MLD) can transmit and / or receive the PPDU of FIG. 6. The PPDU described in the present disclosure may have the structure of FIG. 6, for example. Additionally, the PPDU described in the present disclosure may be referred to by various names such as Ultra High Reliability (UHR) PPDU, Transmit PPDU, Receive PPDU, Type 1, or Type N PPDU. The PPDU described in the present disclosure may be used in WLAN systems defined according to IEEE 802.11bn and / or next-generation WLAN systems that improve upon IEEE 802.11bn.

[0073] The PPDU of FIG. 6 may be related to various PPDU types used in UHR systems. For example, the example of FIG. 6 may be used for at least one of SU (single-user) mode / type / transmission, MU (multi-user) mode / type / transmission, and NDP (null data packet) mode / type / transmission related to channel sounding. For example, if the example of FIG. 6 is related to NDP, the illustrated Data field may be omitted. If the PPDU of FIG. 6 is used for TB (Trigger-based) mode, the UHR-SIG of FIG. 6 may be omitted. In other words, an STA that receives a Trigger frame for UL-MU (Uplink-MU) communication may transmit a PPDU in which the UHR-SIG is omitted in the example of FIG. 6.

[0074] In FIG. 6, L-STF to UHR-LTF can be called a preamble or physical preamble and can be generated / transmitted / received / acquired / decoded at the physical layer (included in the transmitting / receiving STA).

[0075] Each block shown in FIG. 6 can be referred to as a field / subfield / signal, etc. As shown in FIG. 6, the names of these fields / subfields / signals may be L-STF (legacy short training field), L-LTF (legacy long training field), L-SIG (legacy signal), RL-SIG (repeated L-SIG), U-SIG (Universal Signal), UHR-SIG (UHR-signal), etc.

[0076] The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields in Fig. 6 can be set to 312.5 kHz, and the subcarrier spacing of the UHR-STF, UHR-LTF, and Data fields can be set to 78.125 kHz. That is, the tone index (or subcarrier index) of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields can be displayed in units of 312.5 kHz, and the tone index (or subcarrier index) of the UHR-STF, UHR-LTF, and Data fields can be displayed in units of 78.125 kHz.

[0077] The PPDU of Fig. 6, L-LTF and L-STF, may be the same as conventional fields (e.g., non-HT LTF and non-HT STF defined in conventional WLAN standards).

[0078] The L-SIG field of FIG. 6 may contain, for example, 24 bits of bit information. For example, the 24 bits of information may include a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity bit, and a 6-bit Tail bit. For example, the 12-bit Length field may contain information regarding 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, if the PPDU is a non-HT (non-High Throughput), HT (High Throughput), VHT (Very High Throughput) PPDU, or an EHT (extremely high throughput) PPDU, or a UHR PPDU, the value of the Length field may be determined as a multiple of 3. For example, if the PPDU is an HE PPDU, the value of the Length field may be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, for non-HT, HT, VHT PPDU, or EHT PPDU, UHR PPDU, the value of the Length field can be determined as a multiple of 3, and for HE (High-Efficiency) PPDU, the value of the Length field can be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, the Length field in a UHR PPDU is set to a value satisfying the condition that the remainder is zero when LENGTH is divided by 3.

[0079] For example, a (non-AP and AP) STA can apply BCC encoding based on a code rate of 1 / 2 to 24 bits of information in the L-SIG field. Subsequently, the transmitting STA can obtain 48 bits of BCC encoding. BPSK modulation can be applied to the 48 bits of encoding to generate 48 BPSK symbols. The transmitting STA can map the 48 BPSK symbols to positions excluding the pilot subcarrier {subcarrier indices -21, -7, +7, +21} and the DC subcarrier {subcarrier index 0}. Consequently, the 48 BPSK symbols can be mapped to subcarrier indices -26 to -22, -20 to -8, -6 to -1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA can additionally map the signal of {-1, -1, -1, 1} to the subcarrier index {-28, -27, +27, +28}. The above signal can be used for channel estimation for the frequency domain corresponding to {-28, -27, +27, +28}.

[0080] For example, the (non-AP and AP) STA can generate an RL-SIG that is identical to the L-SIG. BPSK modulation may be applied to the RL-SIG. The receiving (non-AP and AP) STA can determine that the received PPDU is a HE PPDU, EHT PPDU, or UHR PPDU based on the presence of the RL-SIG. In other words, the receiving (non-AP and AP) STA can determine that the received PPDU is one of the HE PPDU, EHT PPDU, or UHR PPDU if the RL-SIG is present. In other words, the receiving (non-AP and AP) STA can determine that the received PPDU is one of the non-HT PPDU, HT PPDU, or VHT PPDU if the RL-SIG is not present. In other words, the RL-SIG field is a repeat of the L-SIG field and is used to differentiate an UHR PPDU from a non-HT PPDU, HT PPDU, and VHT PPDU.

[0081] After the RL-SIG in Fig. 6, a U-SIG (Universal SIG) may be inserted. The U-SIG may be referred to by various names such as the first SIG field, first SIG, first type SIG, control signal, control signal field, first (type) control signal, common control field, and common control signal.

[0082] U-SIG may contain N bits of information and may contain information to identify the type of EHT PPDU. For example, U-SIG may be constructed based on two symbols (e.g., two consecutive OFDM symbols). Each symbol for U-SIG (e.g., OFDM symbol) may have a duration of 4 us. Each symbol of U-SIG may be used to transmit 26 bits of information. For example, each symbol of U-SIG may be transmitted and received based on 52 data tones and 4 pilot tones.

[0083] For example, A bit information (e.g., 52 un-coded bits) can be transmitted through U-SIG, and the first symbol of U-SIG can transmit the first X bit information (e.g., 26 un-coded bits) of the total A bit information, and the second symbol of U-SIG can transmit the remaining Y bit information (e.g., 26 un-coded bits) of the total A bit information. For example, the transmitting STA can obtain the 26 un-coded bits included in each U-SIG symbol. The transmitting STA can generate 52-coded bits by performing convolutional encoding (i.e., BCC encoding) based on a rate of R=1 / 2 and can perform interleaving on the 52-coded bits. The transmitting STA can generate 52 BPSK symbols assigned to each U-SIG symbol by performing BPSK modulation on the interleaved 52-coded bits. A single U-SIG symbol can be transmitted based on 56 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. 52 BPSK symbols generated by the transmitting STA can be transmitted based on the remaining tones (subcarriers), excluding the pilot tones -21, -7, +7, and +21.

[0084] For example, A bit information (e.g., 52 un-coded bits) transmitted by U-SIG may include a CRC field (e.g., a field of 4 bits) and a tail field (e.g., a field of 6 bits). The CRC field and the tail field may be transmitted through a second symbol of U-SIG. The CRC field may be generated based on 26 bits assigned to the first symbol of U-SIG and the remaining 16 bits within the second symbol excluding the CRC / tail field, and may be generated based on a conventional CRC calculation algorithm. Additionally, the tail field may be used to terminate the trellis of a convolutional decoder and may be set, for example, to "000000".

[0085] A bit information (e.g., 52 un-coded bits) transmitted by U-SIG (or U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, the size of the version-independent bits can be fixed or variable. For example, the version-independent bits may be assigned only to the first symbol of U-SIG, or the version-independent bits may be assigned to both the first and second symbols of U-SIG. For example, the version-independent bits and the version-dependent bits may be referred to by various names, such as the first control bit and the second control bit.

[0086] For example, the version-independent bits of U-SIG may include a 3-bit PHY version identifier. For example, the 3-bit PHY version identifier may include information related to the PHY version of the transmitted and received PPDU. For example, a first value of the 3-bit PHY version identifier (e.g., a value of 000) may indicate that the transmitted and received PPDU is an EHT PPDU. Additionally, a second value of the 3-bit PHY version identifier (e.g., a value of 001) may indicate that the transmitted and received PPDU is a UHR PPDU.

[0087] In other words, when an (AP / non-AP) STA transmits an EHT PPDU, it can set a 3-bit PHY version identifier to a first value. In other words, a receiving (AP / non-AP) STA can determine that the received PPDU is an EHT PPDU based on the PHY version identifier having the first value, and can determine that the received PPDU is a UHR PPDU based on the PHY version identifier having the second value.

[0088] For example, the version-independent bits of U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field is related to UL communication, and the second value of the UL / DL flag field is related to DL communication.

[0089] For example, the version-independent bits of U-SIG may include information regarding the length of the TXOP (transmission opportunity) and information regarding the BSS color ID.

[0090] For example, if the UHR PPDU is classified into various types (e.g., type related to SU transmission (performed based on UL or DL), type related to DL transmission, type related to NDP transmission, type related to DL non-MU-MIMO, type related to DL MU-MIMO, type related to Multi-AP operation, type related to CO-BF (Coordinated beamforming) and SR (Spatial Reuse), type related to C-OFDMA (Coordinated OFDMA), type related to CO-TDMA (Coordinated TDMA)), information regarding the type of the EHT PPDU (e.g., 2-bit or 3-bit information) may be included in the version-dependent bits of the U-SIG.

[0091] For example, U-SIG may include: 1) a bandwidth field containing information regarding bandwidth; 2) a field containing information regarding the Modulation and Coding Scheme (MCS) technique applied to UHR-SIG; 3) an indication field containing information regarding whether the dual subcarrier modulation (DCM) technique is applied to UHR-SIG; 4) a field containing information regarding the number of symbols used for UHR-SIG; 5) a field containing information regarding whether UHR-SIG is generated across the entire band; 6) a field containing information regarding the type of UHR-LTF / STF; and 7) information regarding a field indicating the length of UHR-LTF and CP length.

[0092] Preamble puncturing may be applied to the PPDU of Fig. 6. Preamble puncturing means applying puncturing to a portion of the total band of the PPDU (e.g., a secondary 20 MHz band). For example, when an 80 MHz PPDU is transmitted, the STA applies puncturing to the secondary 20 MHz band within the 80 MHz band and can transmit the PPDU only through the primary 20 MHz band and the secondary 40 MHz band.

[0093] For example, the pattern of preamble puncturing can be pre-set. For example, when a first puncturing pattern is applied, puncturing may be applied only to a secondary 20 MHz band within an 80 MHz band. For example, when a second puncturing pattern is applied, puncturing may be applied only to one of two secondary 20 MHz bands included in a secondary 40 MHz band within an 80 MHz band. For example, when a third puncturing pattern is applied, puncturing may be applied only to a secondary 20 MHz band included in a primary 80 MHz band within a 160 MHz band (or 80+80 MHz band). For example, when the fourth puncturing pattern is applied, within the 160 MHz band (or 80+80 MHz band), the primary 40 MHz band included in the primary 80 MHz band is present, and puncturing may be applied to at least one 20 MHz channel that does not belong to the primary 40 MHz band.

[0094] Information regarding preamble puncturing applied to the PPDU may be included in the U-SIG and / or UHR-SIG. For example, the first field of the U-SIG may include information regarding the contiguous bandwidth of the PPDU, and the second field of the U-SIG may include information regarding preamble puncturing applied to the PPDU.

[0095] For example, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following method. If the bandwidth of the PPDU exceeds 80 MHz, the U-SIG may be configured individually in 80 MHz units. For example, if the bandwidth of the PPDU is 160 MHz, the PPDU may include a first U-SIG for the first 80 MHz band and a second U-SIG for the second 80 MHz band. In this case, the first field of the first U-SIG may include information regarding the 160 MHz bandwidth, and the second field of the first U-SIG may include information regarding preamble puncturing applied to the first 80 MHz band (i.e., information regarding the preamble puncturing pattern). Additionally, the first field of the second U-SIG may include information regarding a 160 MHz bandwidth, and the second field of the second U-SIG may include information regarding preamble puncturing applied to the second 80 MHz band (i.e., information regarding a preamble puncturing pattern). Meanwhile, the UHR-SIG following the first U-SIG may include information regarding preamble puncturing applied to the second 80 MHz band (i.e., information regarding a preamble puncturing pattern), and the UHR-SIG following the second U-SIG may include information regarding preamble puncturing applied to the first 80 MHz band (i.e., information regarding a preamble puncturing pattern).

[0096] Additionally or generally, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following method. U-SIG may include information regarding preamble puncturing for all bands (i.e., information regarding preamble puncturing patterns). That is, UHR-SIG may not include information regarding preamble puncturing, and only U-SIG may include information regarding preamble puncturing (i.e., information regarding preamble puncturing patterns).

[0097] U-SIGs can be configured in 20 MHz units. For example, if an 80 MHz PPDU is configured, U-SIGs can be duplicated. That is, four identical U-SIGs can be included within an 80 MHz PPDU. PPDUs exceeding the 80 MHz bandwidth may contain different U-SIGs.

[0098] The UHR-SIG of FIG. 6 may include control information for a receiving STA. The UHR-SIG may be transmitted through at least one symbol, and one symbol may have a length of 4 us. Information regarding the number of symbols used for the UHR-SIG may be included in the U-SIG.

[0099] UHR-SIG provides additional signals to the U-SIG field, enabling the STA to interpret / decode the UHR PPDU. The UHR-SIG field may include U-SIG overflow bits that apply commonly to all users. Additionally, the UHR-SIG field contains resource allocation information, making it possible for the STA to look up resources used in fields containing data fields / UHR-STF / UHR-LTF (i.e., UHR modulated fields of an UHR PPDU).

[0100] The frequency resources of the UHR-LTF, UHR-STF, and data fields illustrated in FIG. 6 can be determined based on a RU (resource unit) defined by a plurality of subcarriers / tones. That is, the UHR-LTF, UHR-STF, and data fields of the present disclosure can be transmitted / received through a RU (resource unit) defined by a plurality of subcarriers / tones.

[0101] FIG. 7 is a diagram showing the arrangement of resource units (RUs) used for a 20 MHz PPDU. That is, UHR-LTF, UHR-STF and / or data fields included in the 20 MHz PPDU can be transmitted / received through at least one of the various RUs defined in FIG. 7.

[0102] As shown at the top of FIG. 7, 26 units (i.e., units corresponding to 26 tones) may be arranged. Six tones may be used as a guard band in the leftmost band of the 20 MHz band, and five tones may be used as a guard band in the rightmost band of the 20 MHz band. Additionally, seven DC tones are inserted in the center band, i.e., the DC band, and 26 units corresponding to 13 tones may exist on the left and right sides of the DC band. Furthermore, 26, 52, and 106 units may be allocated to other bands. Each unit may be allocated for a receiving station, i.e., a user.

[0103] Meanwhile, the RU arrangement of Fig. 7 is utilized not only for situations involving multiple users (MU) but also for situations involving a single user (SU), in which case it is possible to use one 242-unit as shown at the bottom of Fig. 4, and in this case, three DC tones can be inserted.

[0104] In the example of FIG. 7, various sizes of RUs, namely 26-RU, 52-RU, 106-RU, 242-RU, etc., are proposed. Since the specific size of these RUs can be expanded or increased, the present embodiment is not limited to the specific size of each RU (i.e., the number of corresponding tones). In the present disclosure, N-RU may be indicated as N-tone RU, etc. For example, 26-RU may be indicated as 26-tone RU.

[0105] Figure 8 is a diagram showing the arrangement of resource units (RU) used for a 40 MHz PPDU.

[0106] Just as various sizes of RUs were used in the example of FIG. 7, 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, etc., may also be used in the example of FIG. 8. Additionally, 5 DC tones may be inserted at the center frequency, 12 tones may be used as guard bands in the leftmost band of the 40 MHz band, and 11 tones may be used as guard bands in the rightmost band of the 40 MHz band.

[0107] In addition, as illustrated, 484-RU may be used when used for a single user. Meanwhile, the specific number of RUs may be changed, as in the example of FIG. 7.

[0108] FIG. 9 is a diagram showing the arrangement of resource units (RUs) used for an 80 MHz PPDU. The arrangement of resource units (RUs) used in the present disclosure may be varied. For example, the arrangement of resource units (RUs) used in the 80 MHz band may be varied.

[0109] FIG. 10 illustrates the operation according to UL-MU. As illustrated, a transmitting STA (e.g., AP) can acquire a TXOP (1025) by performing channel access through contending (i.e., Backoff operation) and transmit a Trigger frame (1030). That is, the transmitting STA (e.g., AP) can transmit a PPDU containing the Trigger frame (1030). When the PPDU containing the Trigger frame is received, a TB (trigger-based) PPDU is transmitted after a delay of SIFS.

[0110] TB PPDUs (1041, 1042) may be transmitted at the same time and may be transmitted from multiple STAs (e.g., User STAs) with an AID indicated within a Trigger frame (1030). An ACK frame (1050) for a TB PPDU may be implemented in various forms. For example, an ACK frame (1050) for a TB PPDU may be implemented in the form of a BA (block ACK).

[0111] In FIG. 10, the transmission(s) of the Trigger Frame (1030), TB PPDU (1041, 1042) and / or ACK Frame (1050) can be performed within TXOP (1025).

[0112] Figure 11 shows an example of a channel used / supported / defined within the 2.4 GHz band.

[0113] The 2.4 GHz band may be referred to by other names, such as the first band (band). Additionally, the 2.4 GHz band may refer to a frequency range in which channels with a center frequency adjacent to 2.4 GHz (e.g., channels with a center frequency located between 2.4 and 2.5 GHz) are used / supported / defined.

[0114] The 2.4 GHz band may include multiple 20 MHz channels. The 20 MHz channels within the 2.4 GHz band may have multiple channel indices (e.g., indices 1 through 14). For example, the center frequency of a 20 MHz channel assigned to channel index 1 may be 2.412 GHz, the center frequency of a 20 MHz channel assigned to channel index 2 may be 2.417 GHz, and the center frequency of a 20 MHz channel assigned to channel index N may be (2.407 + 0.005*N) GHz. Channel indices may be referred to by various names, such as channel numbers. The specific numerical values ​​of channel indices and center frequencies may change.

[0115] FIG. 11 illustrates four channels within a 2.4 GHz band as an example. The illustrated first frequency range (1110) to fourth frequency range (1140) may each include one channel. For example, the first frequency range (1110) may include channel 1 (a 20 MHz channel with index 1). The center frequency of channel 1 may be set to 2412 MHz. The second frequency range (1120) may include channel 6. The center frequency of channel 6 may be set to 2437 MHz. The third frequency range (1130) may include channel 11. The center frequency of channel 11 may be set to 2462 MHz. The fourth frequency range (1140) may include channel 14. The center frequency of channel 14 may be set to 2484 MHz.

[0116] FIG. 12 illustrates an example of a channel used / supported / defined within the 5 GHz band.

[0117] The 5 GHz band may be referred to by other names such as the second band / band. The 5 GHz band may refer to a frequency range in which channels with a center frequency of 5 GHz or more and less than 6 GHz (or less than 5.9 GHz) are used / supported / defined. Alternatively, the 5 GHz band may include multiple channels between 4.5 GHz and 5.5 GHz. The specific figures shown in FIG. 12 may be changed.

[0118] Multiple channels within the 5 GHz band include UNII (Unlicensed National Information Infrastructure)-1, UNII-2, UNII-3, and ISM. UNII-1 may be referred to as UNII Low. UNII-2 may include frequency regions referred to as UNII Mid and UNII-2 Extended. UNII-3 may be referred to as UNII-Upper.

[0119] Multiple channels may be configured within the 5 GHz band, and the bandwidth of each channel may be varied, such as 20 MHz, 40 MHz, 80 MHz, or 160 MHz. For example, the 5170 MHz to 5330 MHz frequency range within UNII-1 and UNII-2 may be divided into eight 20 MHz channels. The 5170 MHz to 5330 MHz frequency range may be divided into four channels through a 40 MHz frequency range. The 5170 MHz to 5330 MHz frequency range may be divided into two channels through an 80 MHz frequency range. Alternatively, the 5170 MHz to 5330 MHz frequency range may be divided into one channel through a 160 MHz frequency range.

[0120] FIG. 13 illustrates an example of a channel used / supported / defined within the 6 GHz band.

[0121] The 6 GHz band may be referred to by other names such as the third band / band. The 6 GHz band may refer to a frequency range in which channels with a center frequency of 5.9 GHz or higher are used / supported / defined. The specific figures shown in FIG. 13 are subject to change.

[0122] For example, the 20 MHz channel of FIG. 13 can be defined starting from 5.940 GHz. Specifically, the leftmost channel among the 20 MHz channels of FIG. 13 may have index 1 (or channel index, channel number, etc.), and the center frequency may be assigned as 5.945 GHz. That is, the center frequency of the index N channel may be determined as (5.940 + 0.005*N) GHz.

[0123] Accordingly, the indices (or channel numbers) of the 20 MHz channel in FIG. 13 are 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125, 129, 133, 137, 141, 145, 149, 153, 157, 161, 165, 169, 173, 177, 181, 185, 189, 193, 197, It may be 201, 205, 209, 213, 217, 221, 225, 229, 233. Also, according to the above-mentioned (5.940 + 0.005*N) GHz rule, the index of the 40 MHz channel of FIG. 13 may be 3, 11, 19, 27, 35, 43, 51, 59, 67, 75, 83, 91, 99, 107, 115, 123, 131, 139, 147, 155, 163, 171, 179, 187, 195, 203, 211, 219, 227.

[0124] FIG. 14 shows an example of a MAC frame header. As illustrated, the MAC frame may include a frame control field / information of 2 octets, a duration field / information of 2 octets, a Receiver Address (RA) field / information of 6 octets, and a Transmitter Address (TA) field / information of 6 octets. As illustrated in FIG. 14, the four fields may be consecutive. The MAC header of FIG. 14 may be modified in various ways, and a new field may be inserted between the four illustrated fields, or at least one of the illustrated fields may be omitted.

[0125] The MAC header shown in FIG. 14 may be located at the very beginning of the MAC frame. That is, the MAC frame may include a MAC header such as that in FIG. 14 and a MAC body field / information following the MAC header. The MAC frame containing the MAC header of FIG. 14 is inserted / included in the data field of the PPDU (e.g., UHR PPDU) shown in FIG. 5.

[0126] MAC frames included in the data fields of the PPDU of this specification may be classified into various types. For example, MAC frames of this specification may be classified into control frames, management frames, and data frames.

[0127] For example, a management frame includes Association Request, Association Response, Reassociation Request, Reassociation Response, Probe Request, Probe Response, Beacon, Disassociation, Authentication, and Deauthentication frames / signals defined in conventional WLANs. For the management frame, the values ​​of the type fields (B3 and B2) in FIG. 14 are set to 00. Additionally, the values ​​of the subtype fields (B7, B6, B5, B4) in FIG. 14 are as follows: Association Request (0000), Association Response (0001), Reassociation Request (0010), Reassociation Response (0011), Probe Request (0100), Probe Response (0101), Beacon (1000), Disassociation (1010), Authentication (1011), Deauthentication (1100).

[0128] For example, the control frame includes the Trigger Beamforming Report Poll, NDP Announcement (NDPA), Control Frame Extension, Control Wrapper, Block Ack Request (BlockAckReq), Block Ack (BlockAck), PS-Poll, RTS, CTS, Ack, and CF-End frames / signals defined in conventional WLANs. For the control frame, the values ​​of the type fields (B3 and B2) in FIG. 14 are set to 01. Also, the values ​​of the subtype fields (B7, B6, B5, B4) in FIG. 14 are as follows: Trigger(0010), Beamforming Report Poll(0100), NDP Announcement(0101), Control Frame Extension(0110), Control Wrapper(0111), BlockAckReq(1000), BlockAck(1001), PS-Poll(1010), RTS(1011), CTS(1100), Ack(1101), CF-End(1110).

[0129] For example, the data frame includes (QoS) Data, (QoS) Null, etc., defined in conventional WLANs. For the management frame, the value of the type field (B3 and B2) in FIG. 14 is set to 10.

[0130] MAC frames / signals used in this specification can be identified through the type field / information and subtype field / information described above. For example, the “trigger frame” in this specification may refer to a MAC frame in which the type bits B3 and B2 within the frame control field of the MAC header are set to 01, and the subtype bits B7, B6, B5, and B4 within the frame control field are set to 0010. Various MAC frames described in this specification are inserted into / included in the data fields of various PPDUs (e.g., HE / VHT / HE / EHT / UHR PPDU).

[0131] Meanwhile, STAs with data to transmit can perform a Clear Channel Assessment (CCA) to sense the medium for a specific period (e.g., DIFS (Distributed Coordination Function (DCF) Inter-Frame Space)) before transmitting the data. In this case, if the medium is idle, the STA can use that medium to perform transmission. However, if the medium is busy, it can be assumed that multiple STAs are already waiting to use it, and the STA can transmit data after waiting for a random backoff period in addition to the DIFS. In this instance, the random backoff period enables collision avoidance because, assuming there are multiple STAs to transmit data, each STA probabilistically takes on a different backoff period value, resulting in different transmission times. Once one STA begins transmission, other STAs are unable to use that medium.

[0132] In the random backoff procedure, when a specific medium transitions from an active state to an idle state, multiple STAs begin preparing to send data. To minimize collisions at this time, STAs intending to transmit data each select a random backoff count and wait for the slot time corresponding to the selected counter. The random backoff count is a pseudo-random integer value, selecting one of the uniformly distributed values ​​within the range [0 CW]. CW stands for contention window. The CW parameter takes the initial value CWmin, but if transmission fails, the value is doubled. For example, if an ACK acknowledgment for a transmitted data frame is not received, it can be considered that a collision has occurred. If the CW value reaches CWmax, it is maintained until data transmission is successful; upon successful transmission, the CW value is reset to CWmin. In this case, CW, CWmin, and CWmax are used for the convenience of implementation and operation. It can be expressed as follows. Meanwhile, when the random backoff procedure starts, the STA selects a random backoff count within the range [0 CW] and continues to monitor the media while the backoff slots are counting down. During this time, if the media becomes in use, the countdown is stopped, and when the media becomes idle again, the countdown for the remaining backoff slots is resumed.

[0133] Figure 15 shows an example of a random backoff procedure.

[0134] Referring to Fig. 15, when multiple STAs have data they wish to send, STA3 can immediately transmit the data frame because the medium is idle for DIFS, while the other STAs wait for the medium to become idle. Since the medium has been idle for a while, multiple STAs will be looking for an opportunity to use it. Therefore, each STA selects a random backoff count, and STA 2, which selects the smallest backoff count, can transmit the data frame. After STA 2 finishes transmitting, the medium becomes idle again, and the STAs resume counting down for the backoff intervals that had been paused. STA 5, which has the next smallest random backoff count value after STA 2 and paused its countdown while the medium was in use, counts down the remaining backoff slots and begins transmitting the data frame, but a collision may occur if it happens to overlap with the random backoff count value of STA 4. At this time, since neither STA receives an ACK response after data transmission, the two STAs double the CW and then select a random backoff count value again.

[0135] Figure 16 illustrates an example of a procedure related to NAV settings.

[0136] Referring to FIG. 16, when a Source (e.g., AP STA / non-AP STA) intending to transmit data sends a request to send (RTS) frame to a destination (e.g., AP STA / non-AP STA) receiving data, the destination can notify surrounding terminals that it will receive data by sending a clear to send (CTS) frame. In other words, the destination designated as the recipient via the RTS frame can transmit a CTS frame. When the Source that transmitted the RTS frame receives the CTS frame, the Source can begin transmitting data to the destination.

[0137] Meanwhile, if an STA other than the Destination designated as the recipient via the RTS frame receives the RTS frame, or if an STA other than the Source that transmitted the RTS frame receives the CTS frame, that STA may set a Network Allocation Vector (NAV). An STA that sets a NAV may not transmit data during the NAV period, thereby allowing the STA to avoid collisions between the STA and the Source / Destination. On the other hand, if the Destination designated as the recipient via the RTS frame receives the RTS frame, or if the Source that transmitted the RTS frame receives the CTS frame, the Source / Destination does not set a NAV.

[0138] If a CTS frame (e.g., PHY-RXSTART.indication primitive) is not received within a certain period from the time when the RTS frame is received (e.g., when the MAC receives the PHY-RXEND.indication primitive corresponding to the RTS frame), STAs that set or updated the NAV through the RTS frame may reset the NAV (e.g., 0). The certain period may be (2*aSIFSTime + CTS_Time + aRxPHYStartDelay + 2*aSlotTime). CTS_Time may be calculated based on the length and data rate of the CTS frame indicated by the RTS frame.

[0139] In FIG. 16, for convenience, setting or updating the NAV is illustrated through an RTS frame or a CTS frame, but NAV setting / resetting / updating may also be performed based on the ¡ field of various other frames, such as non-HT PPDU, HT PPDU, VHT PPDU, or HE PPDU (e.g., the duration field within the MAC header of a MAC frame). For example, if the RA field in a received MAC frame does not match its own address (e.g., MAC address), the STA may set / reset / update the NAV according to the value of the duration field in the received MAC frame.

[0140] Non-AP STAs must maintain two NAVs, and APs can maintain two NAVs, namely an Intra-BSS NAV and a basic NAV. The Intra-BSS NAV can be updated / set by a PPDU within the BSS. The basic NAV can be updated / set by an inter-BSS PPDU, or a PPDU that cannot be classified as inter-BSS or intra-BSS.

[0141] Below, the details regarding power saving mode are explained.

[0142] A non-AP STA can be in one of the following two power management modes:

[0143] - Active Mode: When an STA is in the awake state, it receives and transmits frames at any time. Non-HE STAs remain in the awake state. HE STAs remain in the awake state unless they are unavailable. Unavailable STAs cannot receive PPDUs.

[0144] - Power saving (PS) mode: The STA switches to the awake state to receive or transmit frames. Otherwise, the STA remains in the doze state.

[0145] The STA in PS mode can be in one of the following two power states:

[0146] - Awake state: The STA is fully powered.

[0147] - Doze state: The STA cannot transmit or receive non-WUR PPDU and consumes very low power.

[0148] The way the STA switches between power states is determined by the power management mode and is reflected in dot11PowerManagementMode.

[0149] The power management mode of the STA is selected by the PowerManagementMode parameter of the MLMEPOWERMGT.request primitive or the MLME-MESHPOWERMGT.request primitive. When the STA updates the power management mode, the MLME issues the MLME-POWERMGT.confirm primitive or the MLMEMESHPOWERMGT.confirm primitive, respectively, indicating the success of the operation.

[0150] An STA connected to an AP that changes the power management mode must notify the AP of this fact using the power management subfield within the frame control field of the transmitted frame. The STA must maintain the current power management mode until it notifies the AP of the power management mode change through a frame switching sequence that includes acknowledgment from the AP. The power management mode does not change during a single frame switching sequence. That is, the power management subfield is the same for all MPDUs of the A-MPDU.

[0151] An STA operating in PS mode with dot11NonTIMModeActivated false must periodically receive beacon frames according to the ListenInterval parameter of the MLMEASSOCIATE.request or MLME-REASSOCIATE.request primitive and the ReceiveDTIMs parameter of the MLME-POWERMGT.request primitive, unless it is in WNM sleep mode. An STA operating in PS mode with dot11NonTIMModeActivated true must transmit at least one PS-Poll or trigger frame individually addressed to the connected AP for every ListenInterval parameter used by the MLME primitive, starting from the last known transition of the S1G STA in non-TIM mode, unless it follows TWT or NDP paging procedures.

[0152] WNM sleep mode enables extended sleep for non-AP STAs that do not need to receive all DTIM beacons or perform GTK / IGTK / BIGTK updates. A STA in WNM sleep mode can wake up approximately once per WNM sleep interval to check whether the corresponding TIM bit is set or if group address traffic is pending. An STA can use WNM sleep mode and PS mode simultaneously. The power management subfield of the frame control field can be set to 0 or 1 within a frame transmitted by a STA in WNM sleep mode.

[0153] I. Non-AP STA Power Management Mode

[0154] A non-AP STA must be in active mode upon (re)connection. However, if (re)connection is performed using the on-channel tunneling procedure, the non-AP STA is considered to be in sleep mode and sleep mode upon (re)connection to the BSS identified by the BSSID, band ID, and channel number fields included in the multi-band element transmitted in the on-channel tunneling request frame that carries the (re)connection request frame.

[0155] An STA that has sent a frame to an AP that is not connected and expects a response must remain in the awake state until it receives the response or the procedure times out.

[0156] To change the power management mode, the STA must notify the AP by completing a successful frame exchange initiated by the STA. This frame exchange sequence includes the STA's management frame, extension frame, or data frame, and the AP's Ack or BlockAck frame. In this exchange, the power management subfield in the frame control field of the frame transmitted by the STA indicates the power management mode that the STA should adopt upon successful completion of the frame exchange sequence, unless the power management subfield is reserved. A non-AP STA must not change the power management mode using a frame exchange sequence that does not receive an Ack or BlockAck frame from the AP, or by using a BlockAckReq frame. The power management subfield is ignored in frame exchange sequences initiated by the AP.

[0157] A non-S1G STA changing from doze state to awake state for transmission must perform CCA until a frame capable of setting NAV is detected or until the period specified in NAVSyncDelay of the MLME-JOIN.request primitive has elapsed. An S1G STA changing from doze state to awake state for transmission must perform CCA until a frame capable of setting RID or NAV is detected or until the period specified in NAVSyncDelay of the MLME-JOIN.request primitive has elapsed.

[0158] To change the power management mode, the STA coordinating with the MM-SME must notify the AP through a successful frame exchange sequence initiated by the STA. In this exchange, the power management subfield in the frame control field of the frame transmitted by the STA indicates the power management mode that the STA must adopt upon successfully completing the frame exchange sequence, as announced in the MMS element transmitted by the STA and coordinating with the MM-SME. To change the power management mode of the coordinating STA, a frame can be transmitted using the MMSL within the MMSL cluster established with the AP.

[0159] The non-AP S1G STA requests the PS mode type (TIM mode or non-TIM mode) through a (re)connection request frame sent to the S1G AP.

[0160] The non-AP S1G STA requests operation in non-TIM mode by setting the Non-TIM Support field in the S1G Capabilities element of the (re)connection request frame to 1.

[0161] The non-AP S1G STA requests operation in TIM mode by setting the Non-TIM Support field in the S1G Capabilities element of the (re)connection request frame to 0.

[0162] The non-AP S1G STA checks the PS mode type (TIM mode or non-TIM mode) in the (re)connection response frame received from the S1G AP.

[0163] When the S1G AP sets the non-TIM support field to 1 in the S1G operation element of the (re)connection response frame, the non-AP S1G STA sets dot11NonTIMModeActivated to true and operates in non-TIM mode after connection, and is called a non-TIM STA.

[0164] If the S1G AP sets the non-TIM support field to 0 in the S1G operation element of the (re)connection response frame, the non-AP S1G STA sets dot11NonTIMModeActivated to false and operates in TIM mode after connection, and is called a TIM STA.

[0165] The non-AP S1G STA must operate in the PS mode negotiated during the connection unless a PS mode transition is negotiated or a temporary PS mode transition occurs. The STA must update the value of the ListenInterval parameter used in the primitive call to the AID response interval field in the AID response element of the (re)connection response frame.

[0166] An S1G STA in TIM mode receives a selected beacon frame (based on the ListenInterval parameter of the MLME-ASSOCIATE.request or MLME-REASSOCIATE.request primitive) and sends a PS-Poll frame to the AP if the TIM element of the most recent beacon frame indicates that a BU individually addressed to the STA has been buffered.

[0167] An S1G STA in non-TIM mode must transmit at least one individually addressed PS-Poll or trigger frame to the connected AP at every reception interval and may not receive selected S1G beacon frames (based on the ListenInterval parameter of the MLME-ASSOCIATE.request or MLME-REASSOCIATE.request primitive) unless it follows TWT or NDP paging procedures. An S1G STA in non-TIM mode may transmit (NDP) PS-Poll frames to the S1G AP regardless of whether the S1G AP has directed an individually addressed buffered BU.

[0168] II. AP Power Management

[0169] APs where dot11APPMActivated is false or absent must operate in active mode. APs where dot11APPMActivated is true can operate in the following power management modes:

[0170] - Active mode; and

[0171] - Power saving mode.

[0172] An AP in active mode must be in an awake state and can receive frames at any time.

[0173] In power saving mode, an AP with dot11APPMActivated true can be in one of the following two power states:

[0174] - awake state; and

[0175] - Doze state.

[0176] An AP with dot11APPMActivated true can indicate that it is operating in sleep mode in the following two ways.

[0177] - Set the AP PM bit to 1 in the frame control field of the S1G beacon frame, or

[0178] - Include one or more RPS elements in the S1G beacon frame that represent AP PM RAW (i.e., RAW allocation type is Simplex RAW and RAW type option is 0).

[0179] The AP must operate in active mode during a beacon interval or a short beacon interval when the AP PM subfield of an S1G beacon frame transmitted from TBTT or TSBTT is 0. Likewise, the AP must operate in active mode during one or more RAWs defined by an RPS element where the RAW assignment type is normal RAW, sounding RAW, triggering frame RAW, or simplex RAW with a RAW type option of 1 or 2.

[0180] An AP transmitting an S1G beacon frame with an AP PM subfield of 1 may be in a doze state at any time until the next TBTT or TSBTT, but must be in an awake state during one of the following time intervals:

[0181] - All configured RAW or PRAW intervals (excluding RAW defined by all RPS elements where the RAW assignment type is Simplex RAW and the RAW type option is 0); and

[0182] - All TWT SPs negotiated in accordance with TWT.

[0183] The AP must not be in a doze state for a time exceeding the dot11MaxAwayDuration value. The AP must set dot11MaxAwayDuration to the lowest value obtained from the Max Away Duration field included in the most recently received MAD element from the connected STA.

[0184] Regardless of the power management mode and power status, the AP must generate beacons to maintain network synchronization.

[0185] The STA, which is the intended recipient of a frame transmitted by an AP with a PM mode subfield of 0, must consider the AP to be in active mode.

[0186] An AP that has previously sent a frame to one or a group of STAs with a PM bit of 0 must send a frame with a PM bit of 1 to the same set of STAs before changing its operating mode to sleep mode.

[0187] The STA, which is the intended receiver of the AP transmitting a frame with a PM mode subfield of 1, must consider the AP to be in sleep mode.

[0188] The following describes multi-link (ML) power management.

[0189] Each non-AP STA belonging to a non-AP MLD operating on an active link must maintain its own power management mode and power state. Frame exchange on the active link is possible when a non-AP STA belonging to a non-AP MLD operating on that link is in the awake state.

[0190] Figure 17 shows an example of per-link power saving operation.

[0191] Referring to FIG. 17, the power saving behavior for each non-AP STA affiliated with the non-AP MLD during MLO is described. It is assumed that all TIDs are mapped to all links or a subset of links. As exemplified in FIG. 17, in the initial phase, both non-AP STAs affiliated with the non-AP MLD are in active mode and participate in frame exchange with the corresponding AP of the link. Each non-AP STA affiliated with the non-AP MLD indicates that it is in active mode by setting the power management subfield (i.e., the PM bit in FIG. 17) in the frame control field of the transmitted frame to 0. At some point, non-AP STA 2, affiliated with the non-AP MLD operating on Link 2, indicates to AP 2 that it is entering power saving mode (i.e., setting the PM bit to 1) and transitions to the doze state after a successful frame exchange. non-AP STA 2 maintains the doze state for the remainder of the period. After a certain period of time, non-AP STA 1 enters sleep mode after a successful frame exchange (i.e., sets the PM bit to 1). While operating in sleep mode, non-AP STA 1 wakes up to receive a beacon frame transmitted by AP 1 and confirms that the AP MLD has a BU for the non-AP MLD. Based on this decision, non-AP STA 1 transmits a PS-Poll or U-APSD trigger frame on Link 1 to notify AP 1 that it has switched to an active state. While active, non-AP STA 1 participates in frame exchange with AP 1.

[0192] The following describes the operation of enhanced multi-link single radio (EMLSR).

[0193] The EMLSR operation allows a non-AP MLD with multiple receiving chains to receive an initial control frame transmitted by an AP belonging to the AP MLD on one or more EMLSR links when the corresponding non-AP STA belonging to the non-AP MLD is in the awake state in a non-HT (replication) PPDU, and to participate in frame exchange on the link where the initial control frame was received.

[0194] A non-AP MLD can operate in EMLSR mode on a specified set of active links between the non-AP MLD and the connected AP MLD. A specified set of active links to which EMLSR mode applies is called an EMLSR link. An EMLSR link must be indicated in the link bitmap subfield of the EMLSR link by setting the bit position corresponding to the link ID value of the EMLSR link in the EMLSR link bitmap subfield to 1. For EMLSR mode enabled on a single wireless non-AP MLD, a STA belonging to the non-AP MLD operating on an active link where the bit position in the EMLSR link bitmap subfield is 0 becomes doze if a non-AP STA belonging to the non-AP MLD operating on one of the EMLSR links is in an awake state.

[0195] When a non-AP MLD with dot11EHTEMLSROptionActivated true is (re)connected with an AP MLD, EMLSR mode is disabled by default.

[0196] When a non-AP MLD operates in EMLSR mode on an EMLSR link, a non-AP STA operating on an EMLSR link and affiliated with a non-AP MLD must not operate in dynamic SM sleep mode on an EMLSR link.

[0197] When a non-AP MLD operates in EMLSR mode with an AP MLD that supports EMLSR mode, the following applies:

[0198] a) A non-AP MLD must be able to receive on an EMLSR link by ensuring that the affiliated non-AP STA corresponding to the link is in an awake state. Receive operations include receiving the initial control frame of a frame exchange initiated by the CCA and the AP MLD. A non-AP STA operating on one of the EMLSR links may change its power management mode and follow power management procedures. A non-AP STA may receive on one of the EMLSR links in active mode or in PS mode when in an awake state.

[0199] b) An AP belonging to an AP MLD that initiates frame exchange with a non-AP MLD on one of the EMLSR links for non-group address data or non-group address management frames must initiate frame exchange by sending an initial control frame to the non-AP MLD. For example, a MU-RTS trigger frame or a BSRP trigger frame may be used as the initial control frame to initiate frame exchange.

[0200] c) A non-AP STA belonging to a non-AP MLD that is in a receiving operation and receives a MU-RTS trigger frame or a BSRP trigger frame addressed to itself must transmit a response frame. However, this is an exception if a frame exchange initiated by an initial control frame on one of the EMLSR links overlaps with a group-addressed frame transmission on another EMLSR link where the non-AP STA intends to receive a group-addressed frame.

[0201] d) After receiving the initial control frame of the frame exchange and transmitting an immediate response frame in response to the initial control frame, a non-AP STA belonging to a non-AP MLD that was receiving on that link must be able to transmit or receive frames on the link where the initial control frame was received and must not transmit or receive frames on another EMLSR link until the frame exchange is finished. Additionally, depending on the spatial stream function, the mode of operation, and the minimum MAC frame padding period of the padding field of the initial control frame, a non-AP STA belonging to a non-AP MLD must be able to receive PPDUs transmitted using two or more spatial streams on the link where the initial control frame was received after SIFS, following the completion of the transmission of the response frame requested in the initial control frame. During the frame exchange, another AP belonging to an AP MLD must not transmit frames to another non-AP STA belonging to a non-AP MLD on another EMLSR link.

[0202] e) If an AP belonging to an AP MLD intends to continue frame exchange with a STA before the TXNAV timer expires and has not received a response frame from this STA for the most recently transmitted frame requiring an immediate response after SIFS, it must transmit another initial control frame addressed to a non-AP STA belonging to a non-AP MLD.

[0203] f) One of the non-AP STAs belonging to a non-AP MLD operating on one of the EMLSR links can start frame exchange with the AP MLD.

[0204] A non-AP STA belonging to a non-AP MLD operating in EMLSR mode can receive a beacon frame at the reserved beacon transmission time (e.g., TBTT).

[0205] The following explains the TIM (traffic indication map).

[0206] The TIM must identify STAs whose traffic is pending and buffered by the AP. This information is coded in the partial virtual bitmap. Additionally, the TIM contains an indication of whether traffic is pending, rather than the SYNRA group address. An AID is assigned to every STA by the AP as part of the connection process. AID 0 is reserved to indicate the presence of a buffered BU that is not a GCR-SP group address but is delivered using an MPDU with a non-SYNRA RA. The AP must identify STAs ready to deliver the buffered BU by setting the bit in the TIM's partial virtual bitmap corresponding to the appropriate AID.

[0207] Two different types of TIM are distinguished: TIM and DTIM. After DTIM, the AP must transmit buffered non-GCR-SP group addressing BUs delivered using MPDUs with RAs other than SYNRAs, and then transmit addressing frames individually. The AP may also transmit these BUs using a group AID.

[0208] The AP must transmit TIM with all beacon frames, except when frames are reserved for transmission via TSBTT rather than TBTT. For all dot11DTIMPeriods, a TIM of type DTIM, rather than a standard TIM, is transmitted within the beacon frame. An S1G AP with dot11ShortBeaconInterval true may include TIM in beacon frames reserved for transmission via TSBTT rather than TBTT. An S1G AP with dot11ShortBeaconInterval true may transmit a TIM of type DTIM in S1G beacon frames for all dot11ShortBeaconDTIMPeriods.

[0209] FIG. 18 shows an example of a power management operation according to an embodiment of the present disclosure.

[0210] Referring to Fig. 18, AP and STA activities are illustrated under the assumption that DTIMs are transmitted once every three TIMs. The top line of Fig. 18 represents the time axis, and the beacon interval is indicated along with the DTIM interval of three beacon intervals. The second line represents AP activity. The AP reserves beacon frames for transmission every beacon interval, but beacon frames may be delayed if there is traffic on the TBTT. This is indicated as "medium in use" in the second line. For the purposes of Fig. 18, an important fact regarding beacon frames is that they contain TIMs, some of which are DTIMs. The second STA, with ReceiveDTIMs false, does not power on the receiver for all DTIMs.

[0211] The third and fourth lines of Fig. 18 illustrate the activities of two STAs operating under different power management requirements. Both STAs power on their receivers when they need to receive a TIM. This indicates that the receiver power is ramped up prior to TBTT. For example, the first STA powers on its receiver and receives a TIM in the first beacon frame. This TIM indicates that there is a buffered BU for the receiving STA. The receiving STA then generates a PS-Poll frame to trigger the transmission of the buffered BU from the AP. The GCR-SP group unaddressed BU is transmitted from the AP after the DTIM beacon transmission.

[0212] Meanwhile, APs generally remain active at all times to provide high throughput and fast service to connected STAs, and can perform frame switching using the highest possible bandwidth and a large number of spatial streams. Since APs can be powered at all times, the need to reduce power consumption for the APs may be relatively small. However, because the actual power consumed by APs is substantial, network maintenance costs may increase. Additionally, for battery-operated APs (e.g., mobile APs), battery life must be considered. Accordingly, it is necessary to reduce the power consumption of the APs. Furthermore, considering the introduction of multi-link operation in IEEE 802.11be and multi-AP cooperative networks in IEEE 802.11bn, power consumption of APs may increase further because the number of links and / or STAs operated by each multi-link device (MLD) may increase. Therefore, a new method / device for reducing AP power needs to be designed, and an integrated framework applicable to all STAs can also be considered.

[0213] In the present disclosure, "frame exchange (FE)" may include frame transmission and / or reception operations between STAs. The STA may be an AP or a non-AP STA. Herein, the frame may include various types of frames (e.g., data frame, control frame, management frame).

[0214] Figure 19 shows an example of EMLSR operation.

[0215] EMLSR (enhance multi-link single radio) was introduced in IEEE 802.11be for efficient multi-link operation of single radio non-AP MLDs. A non-AP MLD operating in EMLSR mode can perform a listening operation on an awake EMLSR link(s). This listening operation may include receiving an initial control frame (ICF) and / or a CCA for frame exchange(s) initiated by the AP MLD. That is, the non-AP MLD can perform a listening operation on one or more links using a single radio's multiple receive chain and then exchange frames with the AP on the link that receives the ICF.

[0216] During this listening operation, the STA can reduce its power consumption by transmitting (TX) / receiving (RX) PPDUs with a restricted configuration (e.g., non-HT (duplicate) PPDU, 20 MHz-only, 1 spatial stream) and / or by performing CCA on a limited bandwidth. That is, operational characteristics such as the listening operation of EMLSR can be utilized as one of the power saving modes (e.g., awake, doze states). Specifically, the power consumed on each link during the listening state can be reduced by applying the characteristics of the EMLSR operation as shown in FIG. 19 to individual links. An AP / STA operating in power saving (PS) mode on one or more links may have a low capability / configuration in the listening state and may switch to a capability / configuration that utilizes a wide bandwidth and a large number of spatial streams to exchange frames quickly. In other words, ICF can be defined and / or utilized similarly to EMLSR for the transition of these capabilities / configurations. This PS is also similar to dynamic spatial multiplexing (SM) PS and can be classified as a dynamic PS because it does not achieve power savings based on planned time.

[0217] Therefore, a new frame sequence needs to be defined so that an AP / STA that remains in a listening state to reduce power consumption and receives an ICF included in a PPDU transmitted with limited capability / setting can exchange frames with the AP / STA that transmitted the ICF.

[0218] The present disclosure provides a frame sequence between one or more STAs operating as dynamic PS. Specifically, the present disclosure defines a frame sequence for the STA to perform UL transmission to an AP operating as dynamic PS. Through this frame sequence, the AP / STA can perform UL transmission while reducing power consumption.

[0219] In the present disclosure, a dynamic PS may mean a PS whose PS mode / state changes based on the detection of a specific event and / or the transmission / reception of a specific frame.

[0220] For example, if an STA operating as a dynamic PS (e.g., AP / non-AP STA) detects an ICF transmission event (e.g., detects that there is data to transmit / receive) while in the listening state, transmits an ICF, and / or receives an ICF, the STA may transition to the frame switching state and perform frame switching in the frame switching state. For example, if the STA receives an ICF while in the listening state, the STA may transition from the listening state to the frame switching state to perform CCA / backoff for wide bandwidth and transmit an ICR (initial control response) based on normal capability / configuration. When frame switching is complete (e.g., when an ACK frame is transmitted / received), the STA may transition back to the listening state.

[0221] In the present disclosure, a listening state may mean a state in which a STA (e.g., AP / non-AP STA) operates with limited capability / configuration and receives an ICF based on limited capability / configuration, and / or performs CCA / backoff for limited bandwidth.

[0222] In the present disclosure, a frame switching state may mean a state in which a STA (e.g., AP / non-AP STA) operates with normal capability / configuration and performs frame switching based on normal capability / configuration. For example, a frame switching state may include an awake state.

[0223] Specific designations (names) proposed in this disclosure may be changed and are not limited thereto.

[0224] FIG. 20 illustrates an example of a method performed by AP for flexible power saving according to an embodiment of the present disclosure.

[0225] Referring to Fig. 20, in step S2001, the AP can enter a listening state.

[0226] In step S2003, the AP can receive an initial control frame (ICF) from the STA (station) to start uplink transmission based on restricted capability while in a listening state.

[0227] In step S2005, the AP can switch from a listening state to a frame switching state in response to receiving an ICF.

[0228] In step S2007, the AP can receive UL data from the STA based on normal capability in the frame switching state.

[0229] In step S2009, in response to the AP transmitting an ACK (acknowledge) frame for the UL data, the AP may switch from a frame switching state to a listening state.

[0230] According to various embodiments, the AP may perform a listening operation based on limited capability in a listening state. The listening operation may include at least one of an operation to monitor the reception of an ICF, an operation to receive an ICF, or an operation to perform a channel access procedure for a limited bandwidth. The channel access procedure may include at least one of a clear access assessment (CCA) or a back-off.

[0231] According to various embodiments, the limited capability may include at least one of a limited bandwidth or a limited number of spatial streams. The general capability may include at least one of a bandwidth greater than the limited bandwidth or a number of spatial streams greater than the number of limited spatial streams.

[0232] According to various embodiments, the general capability may be determined based on at least one of: i) a preset; ii) information contained in the ICF; or iii) information received from the STA before the ICF is received.

[0233] According to various embodiments, the general capability may include at least one of the capability supported by STA or the capability supported by AP.

[0234] According to various embodiments, the capability supported by STA may include the maximum capability of STA. The capability supported by AP may include the maximum capability of AP.

[0235] According to various embodiments, the ICF may be transmitted by the STA based on detecting data that the STA will transmit to the AP.

[0236] According to various embodiments, the AP may transmit a response frame to the ICF to the STA based on general capability in a frame switching state. The response frame may include at least one of a clear-to-send (CTS) frame, a block acknowledge (BA) frame, or a management frame.

[0237] According to various embodiments, after the AP transmits a response frame to the ICF to the STA, the AP can receive UL data from the STA based on general capability in the frame switching state.

[0238] According to various embodiments, the AP can transmit an ACK (acknowledge) frame for UL data to the STA based on general capability in the frame switching state.

[0239] According to various embodiments, the AP can transmit information to the STA about the power save state in which the AP is currently operating. The power save state may include at least one of a listening state or a frame switching state.

[0240] According to various embodiments, the ICF may be included in duplicated PPDUs having a limited configuration and transmitted over a bandwidth greater than the limited bandwidth. The AP may receive the ICF from the STA over the limited bandwidth while in a listening state.

[0241] According to various embodiments, duplicate PPDUs having limited settings may each include non-HT (high throughput) duplicate PPDUs transmitted at 20 MHz.

[0242] FIG. 21 shows an example of signal flow between AP and STA for flexible power saving according to an embodiment of the present disclosure.

[0243] Referring to Fig. 21, in step S2101, the AP can enter a listening state.

[0244] In step S2103, the STA may transmit an initial control frame (ICF) to the AP to initiate uplink transmission. The AP may receive the ICF from the STA (station) based on restricted capability while in a listening state.

[0245] In step S2105, the AP can switch from a listening state to a frame switching state in response to receiving an ICF.

[0246] In step S2107, the STA can transmit UL data to the AP. The AP can receive UL data from the STA based on normal capability in the frame switching state.

[0247] In step S2109, in response to the AP transmitting an ACK (acknowledge) frame for the UL data, the AP may switch from a frame switching state to a listening state.

[0248] According to various embodiments, the STA can receive a response frame for the ICF from the AP. Based on the response frame, the STA can identify that the AP has transitioned from a listening state to a frame switching state.

[0249] According to various embodiments, the STA can receive an ACK (acknowledge) frame for UL data from the AP. Based on the ACK frame, the STA can identify that the AP has transitioned from a frame switching state to a listening state.

[0250] Below, a detailed implementation for flexible power saving in the uplink is described.

[0251] The present disclosure provides a frame sequence for an STA connected to an AP to perform UL transmission when the AP is operating as a dynamic PS. Herein, the STA may operate in an individual / independent power management mode.

[0252] In some implementations, a non-AP STA can support the AP's dynamic PS operation. For example, a non-AP STA can send an ICF (e.g., a control frame) to the AP. For example, a non-AP STA can receive an ICF from the AP and send a response frame (i.e., an ICR) for the ICF after SIFS.

[0253] In some implementations, an AP operating as a dynamic PS may not be aware of the PS mode / state of the STA unless it receives separate signaling (e.g., PS-Poll frame, PM bit = 0 or 1, ICF) from the receiver STA of a DL transmission (or the sender STA performing a UL transmission to the AP). For example, when the AP is in the listening state of a dynamic PS, non-AP STAs may operate in individual / independent power management modes and may be in individual / independent PS modes / states.

[0254] FIG. 22 shows an example of a frame sequence for UL transmission when the AP operates as a dynamic PS according to an embodiment of the present disclosure.

[0255] Referring to FIG. 22, a Non-AP STA can operate in an individual power management mode. An AP connected to an STA(s) supporting a dynamic AP PS can perform listening operations (e.g., receiving an ICF and / or CCA) based on a limited capability / setting (e.g., 20 MHz, 1 SS, non-HT (duplicate) PPDU TX / RX) in the listening state to reduce power consumption. When UL data is transmitted from an upper layer, the STA can initiate a random backoff procedure and acquire a TXOP through contention. The STA that acquired the TXOP can transmit a PPDU with a limited capability / setting containing an ICF (e.g., non-HT (duplicate) PPDU, 20 MHz, 1 SS) to the AP to transition the AP operating with the dynamic PS from the listening state to the awake state. At this time, the ICF contained in the PPDU with limited configuration / capability (e.g., non-HT (duplicate) PPDU) can be transmitted over an unrestricted bandwidth (e.g., bandwidth of 20 MHz or more), but the AP in the listening state can receive the PPDU with a limited bandwidth (e.g., 20 MHz).

[0256] An AP operating in a listening state based on a low (or limited) capability / setting may, after receiving an ICF transmitted from a STA, transition to a frame switching state / awake state associated with a high capability / setting (e.g., 80 MHz / 1 SS or 160 MHz / 2 SS) based on pre-configured information and / or information contained within the ICF transmitted from the STA. After receiving the ICF and transitioning to the frame switching state / awake state, the AP may send a response frame (ICR, e.g., CTS frame, BA frame, management frame) to the STA in response to the ICF following SIFS. Upon receiving the response frame from the AP, the STA may initiate UL transmission and transmit PPDU(s) containing UL data. After completing UL transmission and transmitting a BA frame to the STA, the AP may transition back to the listening state to reduce unnecessary power consumption.

[0257] In the present disclosure, a STA provides a frame sequence for performing UL transmission to an AP operating as a dynamic PS. According to embodiments of the present disclosure, based on the frame sequence for UL transmission, the STA can efficiently save power while operating in a separate power management mode and can perform UL transmission with an AP operating as a dynamic PS.

[0258] The technical features of the present disclosure described above may be applied to various devices and methods. For example, the technical features of the present disclosure described above may be performed or supported through the device of FIG. 1 and / or FIG. 5. For example, the technical features of the present disclosure described above may be applied only to parts of FIG. 1 and / or FIG. 5. For example, the technical features of the present disclosure described above may be implemented based on the processing chip (114, 124) of FIG. 1, or based on the processor (111, 121) and memory (112, 122) of FIG. 1, or based on the processor (510) and memory (520) of FIG. 5.

[0259] For example, the processor (121) and / or processing chip (124) of FIG. 1 may be configured to perform operations performed by the AP in the present disclosure by executing instructions stored in memory (122). The operations include: entering a listening state; receiving an initial control frame (ICF) from a STA (station) to start uplink (UL) transmission based on restricted capability in the listening state; switching from the listening state to a frame switching state in response to receiving the ICF; receiving UL data from the STA based on normal capability in the frame switching state; and switching from the frame switching state to the listening state in response to transmitting an ACK (acknowledge) frame for the UL data.

[0260] For example, the processor (111), processing chip (114) of FIG. 1 and / or the processor (510) of FIG. 5 may be configured to execute instructions stored in memory (112, 520) to perform operations performed by the second STA in the present disclosure. The operations include: an operation of transmitting an initial control frame (ICF) to an access point (AP) to initiate uplink (UL) transmission; and an operation of transmitting UL data to the AP, wherein the AP is configured to: receive the ICF from the STA based on restricted capability in a listening state; switch from the listening state to a frame switching state in response to receiving the ICF; and switch from the frame switching state to the listening state in response to transmitting an acknowledgment (ACK) frame for the UL data.

[0261] The technical features of the present disclosure may be implemented based on a computer-readable medium (CRM). For example, the CRM proposed by the present disclosure is at least one computer-readable medium comprising instructions based on execution by at least one processor.

[0262] For example, the CRM may be the memory (122) of FIG. 1 and / or a separate external memory / storage medium / disk. The CRM may store instructions for performing operations performed by the AP in the present disclosure based on execution by a processor (e.g., the processor (121) and / or processing chip (124) of FIG. 1). The operations include: an operation to enter a listening state; an operation to receive an initial control frame (ICF) from a STA (station) to start an uplink (UL) transmission based on restricted capability in the listening state; an operation to switch from the listening state to a frame switching state in response to receiving the ICF; an operation to receive UL data from the STA based on normal capability in the frame switching state; and an operation to switch from the frame switching state to the listening state in response to transmitting an ACK (acknowledge) frame for the UL data.

[0263] For example, the CRM may be the memory (112) of FIG. 1, the memory (520) of FIG. 5, and / or a separate external memory / storage medium / disk. The CRM may store instructions for performing operations performed by the STA in this disclosure based on execution by a processor (e.g., the processor (111) of FIG. 1, the processing chip (114), and / or the processor (510) of FIG. 5). The operations include: an operation of transmitting an initial control frame (ICF) to an access point (AP) to initiate uplink (UL) transmission; and an operation of transmitting UL data to the AP, wherein the AP receives the ICF from the STA based on a restricted capability in a listening state; and in response to receiving the ICF, switches from the listening state to a frame switching state; And in response to transmitting an ACK (acknowledge) frame for the above UL data, it is configured to switch from the frame exchange state to the listening state.

[0264] The technical features of the present disclosure described above are applicable to various applications or business models. For example, the technical features described above may be applied for wireless communication in devices supporting Artificial Intelligence (AI).

[0265] Artificial intelligence refers to the field of researching artificial intelligence or the methodologies to create it, while machine learning refers to the field of researching methodologies to define and solve various problems addressed within the field of artificial intelligence. Machine learning is also defined as an algorithm that improves performance on a task through continuous experience.

[0266] An Artificial Neural Network (ANN) is a model used in machine learning that can refer to any model capable of problem-solving, composed of artificial neurons (nodes) that form a network through the connection of synapses. An artificial neural network can be defined by connection patterns between neurons in different layers, a learning process that updates model parameters, and an activation function that generates output values.

[0267] An artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer may include one or more neurons, and the artificial neural network may include synapses connecting the neurons. In an artificial neural network, each neuron may output a function value of an activation function for input signals, weights, and biases input through the synapses.

[0268] Model parameters refer to parameters determined through learning, including synaptic connection weights and neuron biases. Hyperparameters, on the other hand, refer to parameters that must be set prior to training in a machine learning algorithm, including the learning rate, number of iterations, mini-batch size, and initialization function.

[0269] The objective of training an artificial neural network can be viewed as determining model parameters that minimize the loss function. The loss function can be used as an indicator to determine optimal model parameters during the training process of an artificial neural network.

[0270] Machine learning can be classified into supervised learning, unsupervised learning, and reinforcement learning depending on the learning method.

[0271] Supervised learning refers to a method of training an artificial neural network with labels provided for the training data; a label can refer to the correct answer (or result) that the neural network must infer when the training data is input. Unsupervised learning refers to a method of training an artificial neural network without labels provided for the training data. Reinforcement learning refers to a learning method in which an agent defined within an environment is trained to select an action or sequence of actions that maximizes the cumulative reward in each state.

[0272] Machine learning implemented using a Deep Neural Network (DNN) that includes multiple hidden layers among artificial neural networks is also called Deep Learning, and Deep Learning is a part of Machine Learning. Hereinafter, Machine Learning is used in a sense that includes Deep Learning.

[0273] In addition, the aforementioned technical features can be applied to the wireless communication of robots.

[0274] A robot can refer to a machine that automatically processes or operates a given task based on its own capabilities. In particular, a robot that has the ability to perceive its environment, make decisions on its own, and perform actions can be called an intelligent robot.

[0275] Robots can be classified into industrial, medical, domestic, and military types depending on their purpose or field of use. Robots are equipped with drive units, including actuators or motors, to perform various physical movements, such as moving robot joints. Additionally, mobile robots include wheels, brakes, and propellers in their drive units, enabling them to drive on the ground or fly in the air.

[0276] In addition, the aforementioned technical features can be applied to devices that support augmented reality.

[0277] Extended Reality is a collective term for Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR). VR technology provides real-world objects or backgrounds solely as CG images, AR technology provides virtual CG images superimposed on real-world images, and MR technology is a computer graphics technology that mixes and combines virtual objects with the real world.

[0278] MR technology is similar to AR technology in that it displays real-world objects and virtual objects together. However, there is a difference in that while virtual objects in AR technology are used to complement real-world objects, virtual objects and real-world objects are used as equals in MR technology.

[0279] XR technology can be applied to HMDs (Head-Mount Displays), HUDs (Head-Up Displays), mobile phones, tablet PCs, laptops, desktops, TVs, digital signage, etc., and devices to which XR technology is applied can be called XR devices.

[0280] The present disclosure may have various advantageous effects.

[0281] For example, the AP / STA can operate in a flexible power saving mode to reduce unnecessary power consumption during uplink data transmission.

[0282] The advantageous effects obtainable through specific embodiments of the present disclosure are not limited to those listed above. For example, there may be various technical effects that a person skilled in the art can understand and / or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein and may include various effects that can be understood or derived from the technical features of the present disclosure.

[0283] The claims described in this disclosure may be combined in various ways. For example, the technical features of the method claims of this disclosure may be combined to be implemented as a device, and the technical features of the device claims of this disclosure may be combined to be implemented as a method. Additionally, the technical features of the method claims of this disclosure and the technical features of the device claims of this disclosure may be combined to be implemented as a device, and the technical features of the method claims of this disclosure and the technical features of the device claims of this disclosure may be combined to be implemented as a method.

Claims

Claim 1 A method comprising: a step in which an access point (AP) enters a listening state; a step in which the AP receives an initial control frame (ICF) from a station (STA) to initiate uplink (UL) transmission based on restricted capability while in the listening state; a step in which the AP switches from the listening state to a frame switching state in response to receiving the ICF; a step in which the AP receives UL data from the STA based on normal capability while in the frame switching state; and a step in which the AP switches from the frame switching state to the listening state in response to transmitting an acknowledgment (ACK) frame for the UL data. Claim 2 The method of claim 1 further comprises the step of the AP performing a listening operation based on the limited capability in the listening state, wherein the listening operation includes at least one of an operation of monitoring the reception of the ICF, an operation of receiving the ICF, or an operation of performing a channel access procedure for a limited bandwidth, and the channel access procedure includes at least one of a clear access assessment (CCA) or a back-off. Claim 3 A method according to claim 1, wherein the limited capability comprises at least one of a limited bandwidth or a limited number of spatial streams, and the general capability comprises at least one of a bandwidth greater than the limited bandwidth or a number of spatial streams greater than the number of limited spatial streams. Claim 4 The method of claim 1, wherein the general capability is determined based on at least one of: i) a preset; ii) information contained in the ICF; or iii) information received from the STA before the ICF is received. Claim 5 A method according to claim 1, wherein the general capability comprises at least one of the capability supported by the STA or the capability supported by the AP. Claim 6 A method according to claim 5, wherein the capability supported by the STA includes the maximum capability of the STA, and the capability supported by the AP includes the maximum capability of the AP. Claim 7 The method of claim 1, wherein the ICF is transmitted by the STA based on detecting data to be transmitted by the STA to the AP. Claim 8 A method according to claim 1, further comprising the step of the AP transmitting a response frame to the STA for the ICF based on the general capability in the frame exchange state, wherein the response frame comprises at least one of a CTS (clear-to-send) frame, a BA (block acknowledge) frame, or a management frame. Claim 9 A method according to claim 8, wherein the step of receiving the UL data comprises the step of transmitting a response frame for the ICF to the STA, and then the AP receiving the UL data from the STA based on the general capability in the frame exchange state. Claim 10 A method according to claim 1, further comprising the step of the AP transmitting an ACK (acknowledge) frame for the UL data to the STA based on the general capability in the frame exchange state. Claim 11 A method according to claim 1, further comprising the step of the AP transmitting information about the power save state in which the AP is currently operating to the STA, wherein the power save state includes at least one of the listening state or the frame switching state. Claim 12 A method according to claim 1, wherein the ICF is included in duplicated PPDUs having a limited setting and transmitted over a bandwidth greater than the limited bandwidth, and the step of receiving the ICF includes the step of the AP receiving the ICF from the STA over the limited bandwidth in the listening state. Claim 13 A method according to claim 12, wherein the duplicate PPDUs having the limited setting each include non-HT (high throughput) duplicate PPDUs transmitted at 20 MHz. Claim 14 An access point (AP) comprises: a transceiver; a memory; and at least one processor functionally coupled to the transceiver and the memory, wherein the memory stores instructions for performing operations based on execution by the at least one processor, and the operations include: an operation of entering a listening state; an operation of receiving an initial control frame (ICF) from a station (STA) to start uplink (UL) transmission based on restricted capability in the listening state; an operation of switching from the listening state to a frame switching state in response to receiving the ICF; an operation of receiving UL data from the STA based on normal capability in the frame switching state; and an operation of switching from the frame switching state to the listening state in response to transmitting an acknowledgment (ACK) frame for the UL data. Claim 15 A device comprising: at least one processor; and at least one memory functionally coupled to the at least one processor, wherein the at least one memory stores instructions for performing operations based on execution by the at least one processor, the operations comprising: an operation of entering a listening state; an operation of receiving an initial control frame (ICF) from a station (STA) to start uplink (UL) transmission based on restricted capability in the listening state; an operation of switching from the listening state to a frame switching state in response to receiving the ICF; an operation of receiving UL data from the station based on normal capability in the frame switching state; and an operation of switching from the frame switching state to the listening state in response to transmitting an acknowledgment (ACK) frame for the UL data. Claim 16 A non-transitory computer-readable medium (CRM) storing program code that implements instructions for performing operations based on execution by at least one processor, wherein the operations include: an operation of entering a listening state; an operation of receiving an initial control frame (ICF) from a station (STA) to start uplink (UL) transmission based on restricted capability in the listening state; an operation of transitioning from the listening state to a frame-switching state in response to receiving the ICF; an operation of receiving UL data from the STA based on normal capability in the frame-switching state; and an operation of transitioning from the frame-switching state to the listening state in response to transmitting an acknowledgment (ACK) frame for the UL data. Claim 17 A method comprising: a step in which a STA (station) transmits an initial control frame (ICF) to an AP (access point) to initiate uplink (UL) transmission; and a step in which the STA transmits UL data to the AP, wherein the AP is configured to: receive the ICF from the STA based on a restricted capability in a listening state; switch from the listening state to a frame switching state in response to receiving the ICF; and switch from the frame switching state to the listening state in response to transmitting an ACK (acknowledge) frame for the UL data. Claim 18 A STA (station) comprises: a transceiver; a memory; and at least one processor functionally coupled to the transceiver and the memory, wherein the memory stores instructions for performing operations based on execution by the at least one processor, the operations include: an operation of transmitting an initial control frame (ICF) to an access point (AP) to initiate uplink (UL) transmission; and an operation of transmitting UL data to the AP, wherein the AP is configured to: receive the ICF from the STA based on restricted capability in a listening state; transition from the listening state to a frame switching state in response to receiving the ICF; and transition from the frame switching state to the listening state in response to transmitting an ACK (acknowledge) frame for the UL data. Claim 19 In claim 18, the operations include: receiving a response frame for the ICF from the AP; and identifying, based on the response frame, that the AP has switched from the listening state to the frame switching state. Claim 20 The STA of claim 18, wherein the operations include: an operation of receiving an ACK (acknowledge) frame for the UL data from the AP; and an operation of identifying, based on the ACK frame, that the AP has switched from the frame exchange state to the listening state.

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