KR20260030717A - Backoff method and device for non-primary channel access in a wireless LAN system - Google Patents

Abstract

A backoff method and device related to non-primary channel access in a wireless LAN system are disclosed. The method, performed by a first station (STA) in a wireless LAN system according to one embodiment of the present disclosure, may include: receiving, from a second STA, information about a plurality of enhanced distributed channel access (EDCA) parameter sets, each set of parameters being associated with a plurality of non-primary backoff channels; performing a backoff process on the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets; and transmitting one or more physical layer protocol data units (PPDUs) on one or more of the plurality of non-primary backoff channels and one or more channels including zero or more non-primary non-backoff channels.

Description

Backoff method and device for non-primary channel access in a wireless LAN system.

The present disclosure relates to a backoff method and device related to non-primary channel access in a wireless local area network (WLAN) system.

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

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

The technical problem of the present disclosure is to provide a backoff method and device related to non-primary channel access in a wireless LAN system.

An additional technical challenge of the present disclosure is to provide a backoff method and device for non-primary channel access based on channel subset in a wireless LAN system.

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

A method performed by a first station (STA) in a wireless LAN system according to one aspect of the present disclosure may include: receiving, from a second STA, information about a plurality of enhanced distributed channel access (EDCA) parameter sets, each set of parameters being associated with a plurality of non-primary backoff channels; performing a backoff process on the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets; and transmitting one or more physical layer protocol data units (PPDUs) on one or more of the plurality of non-primary backoff channels and one or more channels including zero or more non-primary non-backoff channels.

A method performed by a second station (STA) in a wireless LAN system according to an additional aspect of the present disclosure may include the steps of: transmitting, to a first STA, information about a plurality of enhanced distributed channel access (EDCA) parameter sets, each set associated with a plurality of non-primary backoff channels; and receiving, from the first STA, one or more physical layer protocol data units (PPDUs) on one or more channels including one or more of the plurality of non-primary backoff channels and zero or more non-primary non-backoff channels, wherein the one or more PPDUs are transmitted by the first STA through a backoff process performed based on the plurality of EDCA parameter sets on the plurality of non-primary backoff channels.

According to the present disclosure, a backoff method and device related to non-primary channel access in a wireless LAN system can be provided.

According to the present disclosure, a backoff method and device for non-primary channel access based on channel subset in a wireless LAN system can be provided.

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

The accompanying drawings, which are incorporated in and are part of the detailed description to aid in understanding the present disclosure, provide embodiments of the present disclosure and, together with the detailed description, describe the technical features of the present disclosure.
FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.
FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.
FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.
FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.
FIG. 5 is a diagram for explaining a CSMA/CA-based frame transmission operation to which the present disclosure can be applied.
FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.
FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.
FIG. 8 is a diagram illustrating an example of primary channel-based channel access to which the present disclosure can be applied.
FIG. 9 is a drawing for explaining an example of a method performed by a first STA according to the present disclosure.
FIG. 10 is a drawing for explaining an example of a method performed by a second STA according to the present disclosure.
FIG. 11 is a diagram illustrating an example of secondary channel access according to the present disclosure.
FIG. 12 is a diagram for explaining a case where BSS channels between APs overlap, according to one embodiment of the present disclosure.
FIG. 13 is a diagram illustrating a process in which an AP transmits announcement information related to SCA according to one embodiment of the present disclosure.
FIG. 14 is a diagram for explaining a back-off procedure when the bandwidth of a BSS operating channel is 160 MHz, according to one embodiment of the present disclosure.
FIG. 15 is a diagram for explaining a back-off procedure when the bandwidth of a BSS operating channel is 320 MHz, according to one embodiment of the present disclosure.
FIGS. 16 to 18 are diagrams showing examples of multiple backoff-based secondary channel access operations according to the present disclosure.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated to allow legacy STAs to attempt demodulation and decoding, and mapped based on a predetermined subcarrier frequency interval (e.g., 312.5 kHz). These can be referred to as pre-EHT modulated fields. Next, the EHT-STF, EHT-LTF, Data, and PE fields can be encoded and modulated to allow STAs that have successfully decoded non-legacy SIGs (e.g., U-SIG and/or EHT-SIG) and obtained the information contained in the fields, and mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz). These can be referred to as EHT modulated fields.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

RUs of different sizes can be defined, such as 26-ton RU, 52-ton RU, 106-ton RU, 242-ton RU, 484-ton RU, 996-ton RU, 2X996-ton RU, 4X996-ton RU, etc. A multiple RU (MRU) is distinguished from multiple individual RUs and corresponds to a group of subcarriers consisting of multiple RUs. For example, one MRU can be defined as 52+26-tons, 106+26-tons, 484+242-tons, 996+484-tons, 996+484+242-tons, 2X996+484-tons, 3X996-tons, or 3X996+484-tons. Additionally, multiple RUs constituting one MRU may or may not be consecutive in the frequency domain.

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

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

Primary channel-based channel access

Channel access in a wireless LAN system is performed based on the primary channel. For example, if the primary channel is idle and the backoff counter (BC) expires, an STA can transmit frames on a channel that includes both the primary channel and the idle secondary channel. To this end, all STAs preferentially perform CCA on the primary channel. Furthermore, the AP announces information about the BSS's primary channel, and the primary channel is always included among the channels on which management frames (e.g., beacon frames, probe response frames, etc.) are transmitted.

FIG. 8 is a diagram illustrating an example of primary channel-based channel access to which the present disclosure can be applied.

The example of Figure 8 illustrates an example of primary channel-based channel access in an 80 MHz bandwidth. Referring to Figure 8, channels in an 80 MHz bandwidth may be referred to as follows.

P20: Primary 20MHz channel

S20: Secondary 20MHz channel (if the bandwidth is 40MHz, corresponds to the remaining 20MHz secondary channel excluding P20)

S40: Secondary 40MHz channel (when the bandwidth is 80MHz, corresponds to the remaining 40MHz secondary channels, excluding P20 and S20)

Similarly, channels with bandwidths exceeding 80 MHz may be referred to as:

S80: Secondary 80MHz channel (corresponds to the remaining 80MHz secondary channels, excluding P20, S20, and S40, when the bandwidth is 160MHz)

S160: Secondary 160MHz channel (if the bandwidth is 320MHz, corresponds to the remaining 160MHz secondary channels excluding P20, S20, S40, and S80)

S320: Secondary 320MHz channel (if the bandwidth is 640MHz, corresponds to the remaining 320MHz secondary channels, excluding P20, S20, S40, S80, and S160)

In existing wireless LAN systems, a backoff counter is set for the primary channel. For example, an STA can perform a CCA (e.g., physical CS and virtual CS) to determine whether the state of the medium on the primary channel is idle or busy. For example, in the example of FIG. 8, if the state of the medium on P20 is determined to be busy based on a CCA (e.g., physical CS and/or virtual CS (NAV)) for P20, the STA does not decrement the backoff counter (BC). However, if the state of the medium on P20 is determined to be idle, the STA can decrement the BC. Through this backoff process, when the BC expires (i.e., when the BC value becomes 0), the STA can check the state of the medium on S20 and S40 (e.g., CCA). The STA can transmit a PPDU (or frame) on the idle channel among S20 and S40 and the primary channel. (In the example of Figure 8, when the BC for P20 expires, S40 is busy and S20 is idle, so 40MHz PPDU can be transmitted on P20 and S20.

Secondary channel-based channel access

The aforementioned primary channel-based channel access operation can prevent interference and protect PPDU transmission, as frame exchange between all STAs and APs is performed according to the state of the primary channel. On the other hand, if only the primary channel is busy and the secondary channel(s) are idle, channel access cannot be performed only on the secondary channel(s) excluding the primary channel, resulting in inefficiency from a medium utilization perspective. For example, in the example of FIG. 8, if P20 is busy and both S20 and S40 are idle, a portion of the bandwidth corresponding to 60 MHz is wasted.

To improve the wireless LAN system, a new method of accessing the secondary channel based on the secondary channel is required even when the primary channel is not in an idle state.

Below, various examples of the present disclosure for secondary channel access are described.

In the present disclosure, secondary channel access means that an STA accesses a secondary channel (or a medium on the secondary channel) while the primary channel (or a medium on the primary channel) is BUSY (e.g., due to OBSS traffic or other circumstances). Here, an AP or non-AP STA may determine that the primary channel is BUSY based on physical carrier sensing and/or virtual carrier sensing and/or NAV settings, etc.

For convenience of explanation in this disclosure, the term "secondary channel" is used to collectively refer to one or more channels other than the primary channel. However, the present disclosure is not limited thereto, and may also be referred to as a "non-primary channel." Furthermore, secondary channel access may be referred to as non-primary channel access (NPCA).

FIG. 9 is a drawing for explaining an example of a method performed by a first STA according to the present disclosure.

In step S910, the first STA may receive information about a plurality of EDCA parameter sets, each associated with a plurality of non-primary backoff channels, from the second STA.

In step S920, the first STA may perform a backoff process based on multiple EDCA parameter sets on multiple non-primary backoff channels.

A non-primary channel may include a non-primary backoff channel and a non-primary non-backoff channel. A non-primary backoff channel may be a channel other than the primary channel on which backoff is performed for non-primary channel access.

The first backoff process based on the first EDCA parameter set for the first non-primary backoff channel and the second backoff process based on the second EDCA parameter set for the second non-primary backoff channel can be performed in parallel or independently.

For example, the first backoff process may include decrementing a first backoff counter based on determining that the medium on the first non-primary backoff channel is idle based on the first EDCA parameter set. The second backoff process may include decrementing a second backoff counter based on determining that the medium on the second non-primary backoff channel is idle based on the second EDCA parameter set.

In step S930, the first STA may transmit one or more PPDUs on one or more channels including one or more non-primary backoff channels and zero or more non-primary non-backoff channels.

During a predetermined period of time before the backoff counter for a non-primary backoff channel expires (i.e., the backoff counter becomes 0), a non-primary channel CCA (e.g., a CCA based on guard interval detection (GID) or energy detection (ED)) for the non-primary non-backoff channel may determine whether the non-primary non-backoff channel is busy or idle. Accordingly, the non-primary non-backoff channel(s) that are idle may be included in one or more channels used for PPDU transmission, along with the non-primary backoff channel(s) whose backoff counters have expired. If no non-primary non-backoff channel(s) are idle (i.e., all non-primary non-backoff channels are busy), the non-primary backoff channel(s) whose backoff counters have expired may be included in one or more channels used for PPDU transmission.

That is, in the description below, the meaning that 0 non-primary non-backoff channels are included in one or more channels through which a PPDU is transmitted (i.e., non-primary non-backoff channels are not included in one or more channels) may correspond to the case where no non-primary non-backoff channel exists in an idle state as a result of the CCA for the non-primary non-backoff channel(s). In the description below, the meaning that one or more non-primary non-backoff channels are included in one or more channels through which a PPDU is transmitted may correspond to the case where one or more non-primary non-backoff channels exist in an idle state as a result of the CCA for the non-primary non-backoff channel(s).

Multiple non-primary backoff channels may be included in the same channel subset or may be included in different channel subsets. A channel subset may include one or more non-primary backoff channels, and some channel subsets may not include any non-primary backoff channels. The number of non-primary non-backoff channels included in a channel subset may be zero or more. A channel subset may correspond to a maximum bandwidth for a PPDU transmitted based on a backoff process for one or more non-primary backoff channels included in the channel subset. Non-primary backoff channels and non-primary non-backoff channels included in the same channel subset may be referred to as related (or adjacent) non-primary channels.

In an example where EDCA parameters for multiple non-primary backoff channels are independently set, the first STA may operate as follows.

For example, if the first backoff counter expires and the second backoff counter does not expire, one PPDU may be transmitted on the first non-primary backoff channel and zero or more first non-primary non-backoff channels associated with the first non-primary backoff channel.

Alternatively, if the first backoff counter expires and the second backoff counter does not expire, transmission of the PPDU on the first non-primary backoff channel and zero or more first non-primary non-backoff channels associated with the first non-primary backoff channel may be postponed.

In this case, if the second backoff counter expires after the first backoff counter expires, one or more PPDUs may be transmitted on the first non-primary backoff channel, zero or more first non-primary non-backoff channels, the second non-primary backoff channel, and zero or more second non-primary non-backoff channels (i.e., non-primary non-backoff channels associated with the second non-primary backoff channel).

A PPDU can be transmitted on one or more channels as follows:

For example, a first PPDU may be transmitted simultaneously on a first non-primary backoff channel and zero or more first non-primary non-backoff channels, and a second PPDU may be transmitted simultaneously on a second non-primary backoff channel and zero or more second non-primary non-backoff channels.

Alternatively, a PPDU may be transmitted on a first non-primary backoff channel, zero or more first non-primary non-backoff channels, a second non-primary backoff channel, and zero or more second non-primary non-backoff channels. In this case, a PPDU may be transmitted on contiguous channels or non-contiguous channels.

Unlike the example of FIG. 9, a common set of EDCA parameters may be applied to multiple non-primary backoff channels. In this case, the common backoff counter may be decremented when at least one of the first non-primary backoff channel and the second non-primary backoff channel is idle. Alternatively, the common backoff counter may be decremented when both the first non-primary backoff channel and the second non-primary backoff channel are idle. When the common backoff counter expires, a PPDU may be transmitted on the first non-primary backoff channel, the second non-primary backoff channel, and zero or more non-primary non-backoff channels.

The method described in the example of FIG. 9 may be performed by the first device (100) of FIG. 1. For example, one or more processors (102) of the first device (100) of FIG. 1 may be configured to receive information about a plurality of EDCA parameter sets, each associated with a plurality of non-primary backoff channels, from a second STA via one or more transceivers, perform a backoff process based on the plurality of EDCA parameter sets on the plurality of non-primary backoff channels, and transmit one or more PPDUs via the one or more transceivers on one or more of the plurality of non-primary backoff channels and one or more channels including zero or more non-primary non-backoff channels. Furthermore, one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 9 or the examples described below when executed by one or more processors (102).

FIG. 10 is a drawing for explaining an example of a method performed by a second STA according to the present disclosure.

In step S1010, the second STA may transmit information about a plurality of EDCA parameter sets, each associated with a plurality of non-primary backoff channels, to the first STA.

In step S1020, the second STA may receive one or more PPDUs from the first STA on one or more channels including one or more of the plurality of non-primary backoff channels and zero or more non-primary non-backoff channels, through a backoff process performed based on a plurality of EDCA parameter sets on a plurality of non-primary backoff channels, transmitted by the first STA.

In the example of Fig. 10, the specific description of the non-primary backoff channel, non-primary non-backoff channel, and EDCA parameter set is the same as the description referring to Fig. 9, so the redundant description is omitted.

The method described in the example of FIG. 10 may be performed by the second device (200) of FIG. 1. For example, one or more processors (202) of the second device (200) of FIG. 1 may be configured to transmit, to the first STA, information about a plurality of EDCA parameter sets, each associated with a plurality of non-primary backoff channels, through one or more transceivers, and to receive, from the first STA, through one or more transceivers, one or more PPDUs on one or more of the plurality of non-primary backoff channels, and one or more channels including zero or more non-primary non-backoff channels, transmitted by the first STA through a backoff process performed based on the plurality of EDCA parameter sets on the plurality of non-primary backoff channels. Furthermore, one or more memories (204) of the second device (200) may store commands for performing the method described in the example of FIG. 10 or the examples described below when executed by one or more processors (202).

The examples of FIGS. 9 and 10 may correspond to some of the various examples of the present disclosure. Below, various examples of the present disclosure, including the examples of FIGS. 9 and 10, will be described in more detail.

In the embodiments described below, a case where the operating channel of the BSS is mainly 80 MHz in size is described as a representative example, but the examples of the present disclosure can be equally applied to secondary channel access within an operating channel of a smaller or larger size.

Example 1

This embodiment relates to the capability of an STA for secondary channel access.

Unlike conventional primary channel-based channel access, which is fundamentally supported by STAs, secondary channel access (SCA) can be performed by STAs (e.g., AP STAs and/or non-AP STAs) that have the capability for SCA. For example, AP STAs and non-AP STAs can inform each other of whether they support the SCA capability and/or whether the SCA capability is enabled.

The capability for SCA can be defined by whether Type 1 CCA can be performed based on whether a WLAN frame is decoded/identified on the secondary channel (i.e., whether a preamble defined by the WLAN system is detected in the frame of the received PPDU (PD)). For Type 1 CCA for the secondary channel, similar to the NAV setting/reset (for the primary channel) through PD-based CCA performed on the existing primary channel (i.e., NAV update based on duration information of the detected preamble), NAV setting/reset for the secondary channel can be applied based on duration information of the preamble detected through Type 1 CCA on the secondary channel.

Additionally, the capability for SCA may be defined by whether a second type CCA based on guard interval detection (GID) or energy detection (ED) is performed on the secondary channel. GID may include determining whether a guard interval symbol defined by the wireless LAN system is detected, and ED may include determining whether a signal greater than or equal to an arbitrary strength is detected, regardless of whether it is a signal/packet defined by the wireless LAN system. Additionally, different or independent detection thresholds (e.g., thresholds for received signal strength) may be defined for the first type CCA and the second type CCA.

Based on these different types of CCA, different levels of SCA capabilities can be defined.

SCA Capability Level 0 may correspond to a capability that does not perform backoff on the secondary channel. That is, as with conventional primary channel-based channel access, a second type of CCA (e.g., GID-based CCA and/or ED-based CCA) may be performed on the secondary channel.

SCA Capability Level 1 may correspond to a capability to perform backoff on one secondary channel simultaneously. If there is more than one secondary channel within the operating channel, Type 1 CCA (e.g., PD-based CCA) may be performed on one secondary channel at a time, and Type 1 CCA/backoff on multiple secondary channels at a time may not be supported.

SCA Capability Level 2 may correspond to the capability to perform backoff on multiple secondary channels simultaneously. If there is one or more secondary channels in the operating channel, a first type CCA (e.g., PD-based CCA) may be performed on one or more of the secondary channels.

These SCA capabilities may be included in capability information elements (e.g., UHR capability IE) for a specific version/generation of a wireless LAN system. For example, an AP may transmit a capability IE including information indicating whether the SCA capability is supported in a beacon frame, a probe response frame, an association request frame, a reassociation request frame, etc. For example, an STA may transmit a capability IE including information indicating whether the SCA capability is supported in a probe request frame, an association request frame, a reassociation request frame, etc.

Example 2

This embodiment describes the operation process of secondary channel access.

First, the STA behavior when the NAV for the primary channel is running (i.e., the NAV is set/reset and has not expired) can be assumed as follows.

For example, when an AP performs frame exchange with a first STA associated with a BSS within a TXOP acquired by the AP, an intra-BSS NAV for the primary channel may be set/reset for the second STA(s) within the BSS. In addition, it may be assumed that the second STA, for which the intra-BSS NAV for the primary channel is operating, accesses a secondary channel (e.g., on a secondary channel identified as idle) and transmits a frame to the AP. In this case, while the AP is performing a transmission within the TXOP (e.g., transmitting downlink data on the primary channel, transmitting an ACK for uplink data, etc.), the AP may not receive a frame transmitted by the second STA to the AP on the secondary channel.

Considering this, it can be expected that an STA can successfully perform frame exchange on SCA if its default NAV is set/reset by a PPDU related to a BSS other than its own BSS (e.g., an OBSS) on the primary channel (i.e., an inter-BSS PPDU), or by a PPDU that cannot be classified/identified as its own BSS or another BSS, and if it performs SCA while the default NAV for the primary channel is in operation. In other words, an STA can perform SCA when the default NAV for the primary channel is set (or in operation).

Example 2-1

This embodiment relates to frame transmission on a secondary channel.

FIG. 11 is a diagram illustrating an example of secondary channel access according to the present disclosure.

In the case of the conventional primary channel-based channel access described with reference to FIG. 8, when a backoff is performed at P20 and the backoff counter expires (i.e., the BC value becomes 0), a frame can be transmitted on P20 and one or more secondary channels in an idle state, depending on whether one or more secondary channels are idle/busy.

In the case of secondary channel access as in Fig. 11, since the case where P20 is in a busy state (e.g., during basic NAV operation for the primary channel) is considered, a backoff process and a channel access operation according to the backoff process on the secondary channel can be defined that are distinct from the backoff process on the existing primary channel.

First, the STA can perform a backoff process on one or more secondary channels capable of performing backoff (referred to as “the first one or more secondary channels”) when P20 is in a busy state.

In this regard, assuming that a backoff process based on a randomly selected backoff counter is not performed on the secondary channel, if a plurality of adjacent STAs having similar operating channels immediately perform frame transmission on a channel that is idle based on the CCA result for a short time interval (e.g., one slot) on a channel that includes (or overlaps with) the secondary channel (without performing the backoff process), a situation may arise where multiple STAs transmit frames simultaneously, and this possibility of collision may actually waste the channel. Therefore, in order to improve channel utilization, a backoff process may be performed on the secondary channel.

Additionally, if the remaining length of the NAV timer for the primary channel is less than a predetermined threshold, the STA may not perform secondary channel access (or backoff on the secondary channel). That is, secondary channel access (or backoff on the secondary channel) may be performed if the remaining length of the NAV timer for the primary channel is greater than or equal to a predetermined threshold.

For example, such a predetermined threshold may be associated with the TXOP length on the secondary channel. For example, if the remaining NAV timer on the primary channel is not sufficient time to acquire a TXOP on the secondary channel, the STA may not perform a backoff on the secondary channel.

Next, when the backoff counter on one or more of the first secondary channels expires (i.e., the BC value becomes 0), the STA may perform a Type 2 CCA on one or more additional secondary channels in addition to the first one or more secondary channels on which the backoff process was performed. For example, the STA may determine whether the result of the Type 2 CCA on other secondary channels (i.e., the additional secondary channels) is idle or busy during a predetermined length of time (e.g., PIFS) before the time when the backoff counter on the first secondary channel on which the backoff process was performed becomes 0.

Accordingly, the STA may perform backoff to perform PPDU/frame transmission on the first one or more secondary channels for which the backoff counter has expired and the second one or more secondary channels corresponding to the additional secondary channels determined to be idle according to the second type CCA. If all secondary channels other than the first one or more secondary channels for which the backoff has been performed (i.e., the secondary channels on which the second type CCA is performed) are busy, the second one or more secondary channels may not include any secondary channels other than the secondary channels for which the backoff counter has expired.

For example, in the example of FIG. 11, S20 is a secondary channel on which a backoff process based on the first type CCA is performed, and a second type CCA may be performed on S40 without a backoff. When the backoff counter on S20 expires and both 20MHz channels of S40 are idle as a result of the second type CCA for a predetermined time period before that, a PPDU corresponding to the remaining 60MHz of S20 and S40, excluding P20, among the 80MHz bandwidth may be transmitted (i.e., the second one or more secondary channels include S20 and S40). In this case, the PPDU transmitted on the second one or more secondary channels may be a PPDU of the 80MHz bandwidth including information indicating that P20 is punctured, and a MAC frame transmitted by an STA that performed secondary channel access may be included in this punctured PPDU.

If the backoff counter for S20 expires and S40 is busy as a result of a second type CCA during a predetermined time interval before that, a PPDU corresponding to 20 MHz of S20 may be transmitted (i.e., the second one or more secondary channels include S20). In this case, the PPDU transmitted on the second one or more secondary channels may be a PPDU of 80 MHz bandwidth that includes information indicating that P20 and S40 are punctured, and the punctured PPDU may include a MAC frame transmitted by the STA that performed the secondary channel access.

Additionally, a PPDU/frame transmitted by an STA on one or more secondary channels may be transmitted to the AP or to another STA.

In the example of Fig. 11, the STA can set/reset the basic NAV based on a frame received while performing a backoff process on the primary channel. During the basic NAV operation for the primary channel, the STA can perform a backoff process on S20. The backoff on S20 can be performed via PD-based CCA, and a time delay due to the switching operation may occur between the PD-based CCA or backoff stop on the primary channel and the PD-based CCA or backoff start on the secondary channel. The CCA on S20 is not limited to PD-based CCA (i.e., Type 1 CCA), and GID-based or ED-based CCA (i.e., Type 2 CCA) can also be performed.

Example 2-2

This embodiment is for TXOP on a secondary channel.

Since a CCA must be performed for P20 when the default NAV for the primary channel expires, the termination point of the TXOP on the secondary channel may be before the default NAV for the primary channel expires. Therefore, the TXOP for the secondary channel may be acquired/configured to terminate before the default NAV for the primary channel expires.

If an STA acquires/configures the TXOP for the secondary channel to end after the default NAV for the primary channel expires, other STAs that do not support secondary channel access (e.g., legacy STAs, etc.) may transmit frames on the channel including the primary channel (i.e., the primary channel and the secondary channel) after the default NAV for the primary channel expires, and STAs that perform secondary channel access may not be able to receive frames transmitted by other STAs on the channel including the primary channel. In addition, if the target beacon transmission time (TBTT) is set at the time when the default NAV is running, the AP should prepare to transmit a beacon on the channel including the primary channel immediately after the default NAV expires, but it may not be able to transmit the beacon in time due to the TXOP on the secondary channel, and other STAs may not receive the beacon that the AP will transmit at the scheduled time and may have to wait for the beacon for a longer period of time. Therefore, by setting the TXOP for the secondary channel to end before the primary NAV expires, frame exchange can be performed normally on the channel including the primary channel.

Additionally, the STA may not transmit frames on the secondary channel or perform backoff on the secondary channel if there is not sufficient time to establish/acquire a TXOP on the secondary channel (e.g., when the default NAV expiration time for the primary channel is below a predetermined threshold (related to the TXOP length)). For example, if the length of the time interval between the time when the backoff counter for the secondary channel expires and the time when the default NAV for the primary channel ends is not sufficient for frame exchange (or not sufficient to establish/acquire a TXOP), the STA may not perform frame transmission on the secondary channel.

Referring to the example of Fig. 11, an STA that wishes to acquire a TXOP through a backoff process on S20 and whose backoff counter has expired can set/acquire the TXOP so that its length is shorter than the remaining time of the basic NAV for the primary channel (i.e., so that the TXOP ends before the basic NAV ends).

Example 3

This embodiment relates to a transmission or reception operation of an STA performing secondary channel access.

An STA performing secondary channel access may transmit a frame/PPDU on the secondary channel during the time when the NAV for the primary channel is operating. For example, the STA may transmit a frame/PPDU on one or more idle secondary channels, excluding/puncturing some channels (e.g., the primary channel and (if any) busy secondary channel(s)), based on a backoff process performed on one or more first secondary channels and a CCA result of one or more additional secondary channels for which backoff has not been performed.

Additionally or alternatively, a TXOP for a secondary channel, which starts with a frame/PPDU transmission on the secondary channel, may be set to end before the NAV on the primary channel ends. The TXOP length may be set/indicated through duration information (e.g., the value of the Duration/ID field) of a frame transmitted or received by an STA performing secondary channel access. For example, the value of the Duration/ID field may be set to a value including the time required for the exchange of frames/PPDU(s) following the corresponding frame/PPDU (e.g., the length of the corresponding frame/PPDU(s) and the interframe gap (IFS)).

Additionally or alternatively, the EDCA parameter set for each (primary) secondary channel on which backoff is performed at the transmitting STA may be set as the EDCA parameter set for the primary channel, the MU EDCA parameter set, or a new EDCA parameter set. This EDCA parameter set may be applied equally to all (primary) secondary channels, or may be applied differently.

In the present disclosure, an STA receiving a frame transmitted via secondary channel access can perform frame detection on the secondary channel while the NAV is operating on the primary channel. For example, the STA may have a frame to transmit and perform backoff on the secondary channel, may receive a frame during the backoff on the secondary channel, or may attempt to receive a frame addressed to itself on the secondary channel even when there is no frame to transmit. Furthermore, the STA may perform NAV setting/resetting for the secondary channel based on duration information of a frame detected on the secondary channel.

Additionally or alternatively, the EDCA parameter set for each (primary) secondary channel on which backoff is performed at the receiving STA may be set as the EDCA parameter set for the primary channel, the MU EDCA parameter set, or a new EDCA parameter set. This EDCA parameter set may be applied equally to all (primary) secondary channels, or may be applied differently.

Example 4

Example 4 relates to a procedure for an AP to announce information related to secondary channel access and information related to secondary access.

If the BSS operating channel of an AP (or AP MLD) overlaps with the BSS (i.e., OBSS) operating channel of a neighboring AP (i.e., a neighboring AP), SCA within the BSS of the AP and SCA within the BSS of the neighboring AP may affect each other. For example, if an AP successfully performs SCA within a BSS and transmits/receives PPDUs/frames using both secondary channels, and the secondary channel through which the AP transmits PPDUs/frames overlaps with the primary channel of another AP, the channel access opportunities of the other AP may be reduced.

For example, assume that the STA of FIG. 11 is AP 1 of FIG. 12. Since S20 of AP 1 of FIG. 12 corresponds to P20 of AP 2 (i.e., S20 of AP 1 and P20 of AP 2 overlap each other), if AP 1 transmits PPDU/frames using all secondary channels, AP 2 may not be able to use P20 and S20. That is, if AP 1 performs SCA, a problem may arise in that AP 2 does not have the opportunity to perform PCH-based channel access.

Additionally, if an AP has the capability for SCA but another AP does not have the capability for SCA, there is a problem that the longer the AP with the capability for SCA occupies the channel, the less chance the other AP has of accessing the channel.

Therefore, the AP may notify the STA of information related to the SCA operation so that the STA can use the SCH while considering the surrounding circumstances (e.g., whether other STAs have the capability for SCA, the operating channel of the BSS to which the STA is associated, channel state information related to the STA, information related to the OBSS, etc.).

Example 4-1

Example 4-1 relates to information related to SCA operation transmitted by an AP to an STA.

The AP can transmit various types of information related to SCA operation to the STA through management frames (e.g., beacon frames, probe response frames, etc.). For example, the management frame can include an IE related to UHR operation or an IE related to SCA operation, and the UHR operation IE or the IE related to SCA operation can include various types of information related to SCA operation. The STA can perform an operation related to SCA according to various types of information related to SCA operation received from the AP.

As an example of the present disclosure, information related to SCA operation may include information on whether to allow SCA, a maximum value of bandwidth that can transmit a frame/PPDU on an SCH when SCA is performed, information on one or more secondary channels that serve as a reference for SCA (i.e., a channel on which backoff is to be performed), and/or CCA threshold information related to a secondary channel.

Specifically, information on whether to allow SCA can be indicated through a field related to whether to allow SCA (e.g., an SCA allowed field), but the name of the field can be changed. For example, assume that the SCA allowed field consists of 1 bit. In this case, if the SCA allowed field value is 1 (or 0), this may mean that SCA is allowed, and if the SCA allowed field value is 0 (or 1), this may mean that SCA is not allowed.

Additionally or alternatively, one of 20, 40, 80, 160, 320, and 640 MHz bandwidths may be indicated as the maximum value of the bandwidth for transmitting a frame/PPDU on the SCH when SCA is performed. The maximum value of the bandwidth for transmitting a frame/PPDU on the SCH by an STA may not be greater than the operating bandwidth of the BSS associated with the STA (or the bandwidth of the BSS operating channel). The operating bandwidth of the BSS (or the bandwidth of the BSS operating channel) may collectively refer to the bandwidths operated by the BSS. As described above, the AP may transmit information about the maximum value of the bandwidth for transmitting a frame/PPDU on the SCH to the STA via a management frame (e.g., a beacon frame or/and a probe response frame). Information about the maximum value of the bandwidth for transmitting a frame/PPDU on the SCH may be indicated via the SCA bandwidth field, but the name of the field may be changed.

For example, assume that the BSS operating bandwidth is 160 MHz and one or more SCHs of S80 are idle. In this case, if the maximum bandwidth announced by the AP (i.e., the maximum bandwidth over which frames/PPDUs can be transmitted on the SCH) is 80 MHz, frames in the form of 80 MHz PPDUs can be transmitted and received by STAs on the excluded channels.

Additionally or alternatively, information about one or more secondary channels that serve as the basis for SCA (i.e., the channels on which backoff is to be performed) may indicate the channels on which backoff is to be performed based on the BSS operating bandwidth or the maximum bandwidth capable of transmitting the frame/PPDU. For example, information about one or more secondary channels that serve as the basis for SCA may be configured through a bitmap.

For example, as illustrated in FIG. 11, if the total bandwidth (e.g., the bandwidth of the BSS operating channel) is 80 MHz and backoff is performed based on the first secondary channel, one or more secondary channels that serve as the basis for SCA may be configured with a 3-bit bitmap. Each bit constituting the 3-bit bitmap may correspond to each 20 MHz secondary channel. For example, the bitmap may be configured with "100" (i.e., the bitmap is configured to indicate that backoff is performed on the first 20 MHz secondary channel). However, this is merely an example, and the bitmap may include a bit corresponding to the PCH. In this case, information indicating one or more secondary channels that serve as the basis for SCA may be configured with a 4-bit bitmap.

As described above, the first bit of the bitmap may correspond to the highest frequency 20 MHz channel and the last bit of the bitmap may correspond to the lowest frequency 20 MHz channel. However, this is only an example, and the first bit of the bitmap may correspond to the lowest frequency 20 MHz channel and the last bit of the bitmap may correspond to the highest frequency 20 MHz channel. In addition, the bandwidth that serves as the basis for the bitmap is not limited to 20 MHz, and may be implemented as 40, 80, or 160 MHz, etc.

Additionally or alternatively, the CCA threshold information related to the secondary channel may include information on a threshold that serves as a criterion for determining the state of the channel through CCA (e.g., a criterion for determining whether the channel state is idle or busy) in one or more SCHs on which SCA is performed. The lower the threshold that serves as a criterion for determining the state of the channel through CCA (i.e., a threshold that is compared with a measurement value of the channel), the higher the likelihood that the state of the channel will be determined as busy even if the measurement value of the channel (e.g., a received signal strength indicator (RSSI)) is low. In this case, the CCA may include a first type CCA and/or a second type CCA.

For example, the threshold value, which serves as a criterion for judging the channel status, may be determined/set as a fixed/predefined value (e.g., -82 dbM or -72 dbM, etc.). Additionally or alternatively, the threshold value, which serves as a criterion for judging the channel status, may be determined/set as a value obtained by adding/subtracting a variable value (e.g., 4 dbM, 8 dbM, etc.) to/from the fixed/predefined value. In this case, the AP may transmit to the STA only the value added/subtracted from the threshold value.

As an example of the present disclosure, FIG. 13 illustrates a procedure for performing SCA based on SCA-related information announced by an AP. As illustrated in FIG. 13, the AP may announce to the STA information regarding the BSS operating bandwidth set to 160 MHz, information indicating that SCA is permitted, information regarding the maximum bandwidth of a PPDU that can be transmitted via SCA set to 40 MHz, and information regarding a secondary channel (i.e., a channel on which backoff is performed) that serves as a reference for SCA. The AP may transmit/announce the above-described information to the STA via a beacon frame.

At this time, information about the channel on which backoff is performed can be configured in bitmap format. For example, as illustrated in FIG. 13, if information about the channel on which backoff is performed is set to an 8-bit bitmap (e.g., "00100000"), this can indicate that the first 20 MHz of S40 (i.e., the second SCH) is the channel on which backoff is performed. Here, it is assumed that the first bit of the bitmap corresponds to the 20 MHz channel with the lowest frequency, and the last bit of the bitmap corresponds to the 20 MHz channel with the highest frequency (i.e., in ascending order).

If information related to SCA is announced from the AP, the STA can perform backoff based on the announced information based on the first SCH of S40. If the backoff count becomes 0 and the second SCH of S40 is IDLE, the STA can transmit a frame on S40 (to another STA (e.g., AP)). In addition, even if the channel state of S80 is IDLE, since the maximum bandwidth of the PPDU that can be transmitted through SCA is 40 MHz, the STA may not perform CCA on a specific SCH of S80 and may not use it.

Through the example described above, the STA can transmit a frame using the SCH even if the state of the PCH is busy, thereby increasing the efficiency of channel use.

Example 5

Example 5 relates to operations related to SCA of STA.

In one embodiment of the present disclosure, during the time when the NAV is set in the PCH, the STA can transmit a frame/PPDU on the SCH by performing SCA. For example, the STA can identify/determine the channel state of one or more SCHs based on the backoff performed on one or more SCHs and the CCA results of one or more SCHs on which the backoff was not performed. If the channel state of one or more SCHs is idle, the STA can transmit a frame/PPDU with the PCH excluded/punctured on the one or more SCHs (to another STA (e.g., AP)).

Additionally or alternatively, a TXOP established based on an SCA performed on one or more SCHs (i.e., backoff performed on one or more SCHs, etc.) may be set to end before the NAV on the PCH ends. That is, the end point of a TXOP that starts with a frame/PPDU transmission on the SCH may be set/determined before the NAV on the PCH ends.

Here, the length of the TXOP set on the SCH can be set/indicated through the duration/ID field of the frame transmitted in the corresponding TXOP. For example, the value of the duration/ID field can be set to a value corresponding to the time required for the exchange of the frame/PPDU following the corresponding frame/PPDU (including the interframe interval (IFS)).

Additionally or alternatively, the STA may obtain information about one or more SCHs performing backoff, such as through a management frame transmitted from the AP (e.g., a beacon frame). At this time, the information about the one or more SCHs may include information about whether frame/PPDU transmission is possible on the one or more SCHs. For example, if the STA performing SCA is an AP, the STA may utilize the information transmitted by the STA (e.g., information about whether frame/PPDU transmission is possible on the SCH and/or information about one or more SCHs performing backoff, etc.).

Additionally or alternatively, an STA may obtain information about the maximum bandwidth over which it can transmit frames/PPDUs on the SCH from the AP via a management frame (e.g., a beacon frame). If the STA performing SCA is an AP, the STA may utilize the information about the maximum bandwidth over which it can transmit frames/PPDUs on the SCH it transmitted.

Additionally or alternatively, the STA may obtain a threshold for the first type of CCA or the second type of CCA for determining the state of the channel (i.e., whether the channel is busy or idle) on the SCH through a management frame (e.g., a beacon frame, etc.). That is, if a value measured by the STA on the SCH (e.g., RSSI or power related to the channel) exceeds the threshold, the channel state of the corresponding SCH may be determined to be busy.

Additionally or alternatively, the EDCA parameter set for each SCH on which backoff is performed may be set to the EDCA parameter set in the PCH, the MU EDCA parameter set, or a new EDCA parameter set. The EDCA parameter set may be applied equally or differently to all SCHs.

As an example of the present disclosure, an STA receiving a frame transmitted via SCA may perform frame detection on the SCH even during the time for which the NAV is set in the PCH. For example, the STA may perform backoff on the SCH for a frame to be transmitted. As another example, when there is no frame to be transmitted, the STA may attempt to receive a frame addressed to itself on the SCA. Furthermore, the STA may perform NAV setting/resetting based on the value of the interval/ID field of the frame detected on the SCH.

Additionally or alternatively, the STA may obtain information about one or more SCHs performing backoff, such as through a management frame transmitted from the AP (e.g., a beacon frame). At this time, the information about the one or more SCHs may include information about whether frame/PPDU transmission is possible on the one or more SCHs. For example, if the STA performing SCA is an AP, the STA may utilize the information transmitted by the STA (e.g., information about whether frame/PPDU transmission is possible on the SCH and/or information about one or more SCHs performing backoff, etc.).

Additionally or alternatively, the STA may obtain a threshold for the first type of CCA or the second type of CCA for determining the state of the channel (i.e., whether the channel is busy or idle) on the SCH through a management frame (e.g., a beacon frame, etc.). That is, if a value measured by the STA on the SCH (e.g., RSSI or power related to the channel) exceeds the threshold, the channel state of the corresponding SCH may be determined to be busy.

Additionally or alternatively, the EDCA parameter set for each SCH on which backoff is performed may be set to the EDCA parameter set in the PCH, the MU EDCA parameter set, or a new EDCA parameter set. The EDCA parameter set may be applied equally or differently to all SCHs.

Example 5-1

Example 5-1 relates to a method for performing backoff by dividing channels including BSS operating channels into multiple sets for efficient SCA. In this case, in addition to the information announced by the AP for SCA as described in Examples 4, 4-1, and 5, information described below (e.g., channel subset unit information, SCA channel bitmap size information, etc.) may be additionally announced/transmitted.

As an example of the present disclosure, the AP may announce information about bandwidth criteria (or units) for dividing the bandwidth of the entire BSS operating channel into one or more channel subsets for SCA (i.e., channel subset unit information).

For example, assume that the (sub)field size indicating channel subset unit information is 2 bits. If the (sub)field value indicating channel subset unit information is 0 (i.e., if the (sub)field indicates no subset), this may mean that the BSS operating channel is not divided into one or more subsets. If the (sub)field value is 1, this may mean that the bandwidth reference/unit value for dividing the BSS operating channel into one or more subsets is 40 MHz. If the (sub)field value is 2, this may mean that the bandwidth reference/unit value for dividing the BSS operating channel into one or more subsets is 80 MHz. If the (sub)field value is 3, this may mean that the bandwidth reference/unit value for dividing the BSS operating channel into one or more subsets is 160 MHz.

However, this is only one embodiment, and the (sub)field size indicating channel subset unit information may be set to 3 bits. In this case, the bandwidth reference/unit value may be indicated as 320 MHz through the (sub)field.

Additionally, the AP may notify the STA of the size of a bitmap (i.e., SCA channel bitmap size information) indicating one or more SCHs that serve as a reference when performing SCA (i.e., SCHs on which backoff is performed).

For example, assume that the (sub)field size indicating SCA channel bitmap size information is 2 bits. If the (sub)field value indicating the SCA channel bitmap size information is 0, this may mean that the SCA channel bitmap size is 4 bits. If the (sub)field value indicating the SCA channel bitmap size information is 1, this may mean that the SCA channel bitmap size is 8 bits. If the (sub)field value indicating the SCA channel bitmap size information is 2, this may mean that the SCA channel bitmap size is 16 bits. If the (sub)field value indicating the SCA channel bitmap size information is 3, this may mean that the SCA channel bitmap size is 32 bits. Here, if P20 is not indicated through the SCA channel bitmap, the SCA channel bitmap size may be reduced by 1.

Here, the (sub)field size indicating the SCA channel bitmap size information may vary depending on the BSS operating channel. For example, if the size of the BSS operating channel is 320 MHz, the SCA channel bitmap size may be set/determined to a maximum of 16 bits.

For example, if information indicating one or more SCHs that serve as references when performing SCA is configured as a bitmap, information for configuring/indicating/described channel subsets may not be required. In other words, there may be no need to configure a bitmap corresponding to each subset as a separate field. If information indicating one or more SCHs that serve as references when performing SCA is configured as a bitmap, if a bit corresponding to a specific channel among the bitmaps is set to 1, it may mean that backoff is performed on the corresponding channel. Additionally or alternatively, there may not be an SCH for which backoff is performed within a channel subset.

As an example of the present disclosure, FIG. 14 illustrates a case where the bandwidth of a BSS operating channel is 160 MHz. In FIG. 14, the shaded portion, excluding P20, may denote an SCH that serves as a reference for SCA (i.e., an SCH capable of performing backoff).

For example, (a) of Fig. 14 illustrates a case where the channel subset unit is 40 MHz. If information indicating one or more SCHs that serve as references when performing P20 and SCA is configured as a bitmap, the bitmap may be set to "01101001." In this case, if P20 is not indicated through the bitmap, the bitmap may be set to "01101001." In other words, one or more SCHs that serve as references when performing SCA for all channel subsets may be expressed/set through a single bitmap.

For example, (b) of Fig. 14 illustrates a case where the channel subset unit is 80 MHz. If information indicating one or more SCHs that serve as references when performing P20 and SCA is configured as a bitmap, the bitmap may be set to "01001000." In this case, if P20 is not indicated through the bitmap, the bitmap may be set to "1001000." In other words, one or more SCHs that serve as references when performing SCA for all channel subsets may be expressed/set through a single bitmap.

As another example of the present disclosure, FIG. 15 is a diagram illustrating an SCA channel bitmap when the bandwidth of a BSS operating channel is 320 MHz. That is, it is assumed that the bandwidth of the BSS operating channel is 320 MHz and the channel subset unit is 80 MHz. In FIG. 15, the shaded portion, excluding P20, may denote a channel that serves as a reference for SCA (i.e., an SCH capable of performing backoff).

For example, if information indicating one or more SCHs that serve as references when performing P20 and SCA is configured as a bitmap, the bitmap may be set to "0100100001001000". In this case, if P20 is not indicated through the bitmap, the bitmap may be set to "100100001001000". That is, one or more SCHs that serve as references when performing SCA for all channel subsets may be expressed/set through a single bitmap. That is, one or more SCHs that serve as references when performing SCA for all channel subsets may be expressed/set through a single bitmap.

Example 6

The present embodiment relates to a backoff mechanism based on multiple backoff channels in relation to secondary channel access. For example, in the STA capabilities related to secondary channel access described in the above-described embodiments, a backoff scheme is described below in the case where an STA (i.e., an AP STA and/or a non-AP STA) has a level 2 secondary channel access capability (i.e., the capability to perform a backoff process on more than one secondary channel simultaneously).

Since an STA having a secondary channel access capability of Level 2 can perform backoff on more than one channel simultaneously, it is necessary to define a specific method for performing backoff on more than one secondary channel and transmitting a frame based on the backoff result (i.e., the value of the backoff counter). The secondary channel on which the STA performs backoff can be predefined (i.e., determined between the AP and the STA without separate signaling) or pre-configured (i.e., notified by the AP to the STA through separate signaling).

In the following description, a secondary channel defined/configured to perform backoff among the secondary channel(s) is referred to as a secondary backoff channel (or non-primary backoff channel), and a secondary channel that does not perform backoff but can be included in a channel through which frames are transmitted is referred to as a secondary non-backoff channel (or non-primary non-backoff channel).

Example 6-1

This embodiment relates to a secondary channel access scheme in which independent/individual EDCA parameter sets are set for secondary backoff channels.

An EDCA parameter set may include various parameters set for each access category (AC), such as VO (voice), VI (video), BE (best effort), BK (background), etc. For example, the minimum contention window per AC (e.g., CWmin[AC]), the maximum contention window per AC (e.g., CWmax[AC]), and the arbitration interframe space number (AIFSN) per AC (e.g., AIFSN[AC]) may be included in the EDCA parameter set.

Accordingly, multiple backoff counters, each corresponding to a plurality of secondary backoff channels, may be maintained and managed by the STA. The value of each backoff counter may be determined according to the busy/idle state of the corresponding secondary backoff channel. In addition, a frame/PPDU may be transmitted on one or more secondary backoff channels (and zero or more secondary non-backoff channels) for which the backoff counter has expired (i.e., the value of the backoff counter is 0).

Additionally or alternatively, frames/PPDUs may be transmitted on one or more secondary backoff channels (and zero or more secondary non-backoff channels) whose backoff counters expire first. This allows data that needs to be transmitted quickly (e.g., latency-sensitive data) to be transmitted first.

FIG. 16 is a diagram illustrating an example of a multi-backoff based secondary channel access operation according to the present disclosure.

For example, a beacon frame may include information indicating that the BSS operating bandwidth is 320 MHz, information indicating that secondary channel access is allowed, information indicating that the secondary channel access bandwidth (i.e., channel subset unit) is 80 MHz, information indicating the secondary channel access channel (i.e., secondary backoff channel), etc.

For example, information indicating a secondary channel access channel can be defined as 16-bit bitmap information. If the value is 0000100000001000, it can indicate that among 16 20MHz channels (i.e., including P20) within 320MHz, the 5th 20MHz channel (i.e., the first secondary channel of the 2nd channel subset) and the 13th 20MHz channel (i.e., the first secondary channel of the 4th channel subset) are secondary backoff channels. Since P20 is always 0 in the information indicating a secondary channel access channel, if this is excluded, it can be defined as 15-bit bitmap information, and its value can be 000100000001000. That is, the location of the secondary backoff channel can be indicated through one bitmap for all channel subsets.

The backoff process is performed in parallel/independently on each secondary backoff channel, and it is assumed that the value of the backoff counter becomes 0 first on the 13th channel.

In this case, if there is one or more idle secondary channels among the secondary non-backoff channels belonging to the same 4th channel subset as the 13th channel, a frame/PPDU may be transmitted on the 13th channel (i.e., the secondary backoff channel) and one or more idle secondary non-backoff channels. For example, the STA may acquire a TXOP by transmitting an RTS frame on the 13th channel (i.e., the secondary backoff channel) and the 14th to 16th channels (i.e., the secondary non-backoff channels) (i.e., on an 80 MHz channel), and may transmit/receive a data frame within the TXOP after receiving a CTS frame from the AP. Alternatively, if the idle secondary channel is the 14th channel among the secondary non-backoff channels belonging to the same 4th channel subset as the 13th channel, the frame/PPDU may be transmitted on a 40MHz channel. Alternatively, if the idle secondary channels are the 15th and 16th channels among the secondary non-backoff channels belonging to the same 4th channel subset as the 13th channel, the frame/PPDU may be transmitted with the 14th channel position punctured among the 80MHz channels. Alternatively, if the number of idle secondary channels is 0 among the secondary non-backoff channels belonging to the same 4th channel subset as the 13th channel, the frame/PPDU may be transmitted on the 13th channel (i.e., the secondary backoff channel).

Furthermore, if interference occurs inside the STA due to a frame/PPDU transmitted on the 13th channel while performing the backoff process on the 5th channel, the result of CCA for the 5th channel may be determined to be busy or the CCA may not be performed properly, causing the backoff counter to be stopped (i.e., not decrement the backoff counter). Accordingly, while the backoff counter on the 5th channel is not 0, a frame/PPDU may be transmitted on the 13th channel (and secondary non-backoff channel(s) that are idle in the corresponding channel subset) where the backoff counter first becomes 0.

FIG. 17 is a diagram illustrating another example of a multi-backoff based secondary channel access operation according to the present disclosure.

If the backoff counter on one or more secondary backoff channels becomes 0 first, the frame/PPDU may be transmitted on multiple secondary backoff channels (and idle secondary non-backoff channel(s) in a subset of those channels) after waiting for the backoff counter on one or more other secondary backoff channels to become 0.

Unlike the example of FIG. 16, which has the effect of reducing latency by preferentially transmitting on a channel including a secondary backoff channel whose backoff counter has expired, the example of FIG. 17 may have the effect of increasing the data rate by transmitting larger frames/PPDUs or utilizing more secondary channels.

In the example of Fig. 17, it is assumed that the information about the BSS operating bandwidth, whether secondary channel access is allowed, secondary channel access bandwidth (i.e., channel subset unit), and secondary channel access channel (i.e., secondary backoff channel) included in the beacon frame are the same as in the example of Fig. 16.

For example, if the backoff counter of the 13th channel becomes 0 first, transmission on the channel subset including the 13th channel may be waited or deferred until the backoff counter on the 5th channel becomes 0. If the backoff counter on the 5th channel becomes 0, the frame/PPDU may be transmitted on the second channel subset including the 5th channel and the fourth channel subset including the 13th channel. In each channel subset, the frame/PPDU may be transmitted on the secondary backoff channel and zero or more idle secondary non-backoff channel(s). If a particular secondary non-backoff channel is not idle, the frame/PPDU may be transmitted on the idle secondary backoff/non-backoff channels other than the secondary non-backoff channel. If the secondary backoff/non-backoff channels in idle state are non-contiguous, punctured PPDUs may be transmitted.

Example 6-2

This embodiment describes a secondary channel access scheme in which a common set of EDCA parameters is set for secondary backoff channels.

Accordingly, a single backoff counter for multiple (or all) secondary backoff channels may be maintained and managed by the STA. When such a single backoff counter expires (i.e., the value of the backoff counter is 0), a frame/PPDU may be transmitted on the multiple (or all) secondary backoff channels (and zero or more secondary non-backoff channels) associated with that single backoff counter.

For example, a backoff counter may be decremented if at least one of multiple (or all) secondary backoff channels associated with a backoff counter is idle.

Additionally or alternatively, a backoff counter may be decremented when multiple (or all) secondary backoff channels associated with a backoff counter are idle.

FIG. 18 is a diagram illustrating another example of a multi-backoff based secondary channel access operation according to the present disclosure.

In the example of Fig. 18, it is assumed that the information about the BSS operating bandwidth, whether secondary channel access is allowed, and secondary channel access bandwidth (i.e., channel subset unit) included in the beacon frame are the same as in the examples of Figs. 16 and 17.

In the example of FIG. 18, information about the secondary channel access channel (i.e., secondary backoff channel) included in the beacon frame is assumed to have a value of, for example, 0000000010001000. That is, among the 16 20MHz channels (i.e., including P20) within 320MHz, the 9th 20MHz channel (i.e., the first secondary channel of the 3rd channel subset) and the 13th 20MHz channel (i.e., the first secondary channel of the 4th channel subset) can be indicated as secondary backoff channels. Since P20 is always 0 in the information indicating the secondary channel access channel, if this is excluded, it can be defined as 15-bit bitmap information, and its value can be, in this case, 000000010001000. That is, the location of the secondary backoff channel can be indicated through a single bitmap for all channel subsets.

Since the same set of EDCA parameters is applied to both secondary backoff channels, the value of one common backoff counter can be decremented depending on the idle/busy state of each secondary backoff channel.

For example, the common backoff counter can be decremented if at least one of the secondary backoff channels, the 9th channel and the 13th channel, is in an idle state.

Alternatively, the common backoff counter can be decremented when both the 9th channel, which is the secondary backoff channel, and the 13th channel are idle.

Therefore, when the value of one common backoff counter has expired (i.e., the value of the backoff counter becomes 0), a frame/PPDU can be transmitted on a secondary non-backoff channel that is in an idle state within a channel subset including the 9th channel and the 13th channel and to which each secondary backoff channel belongs. For example, when the 9th channel and the 13th channel, which are secondary backoff channels, are in an idle state and the 10th to 12th channels and the 14th to 16th channels, which are secondary non-backoff channels, are in an idle state, a TXOP can be obtained by transmitting an RTS frame on a 160MHz channel, and after receiving a CTS frame from the AP, a data frame can be transmitted/received within the TXOP.

The transmitted PPDU bandwidth may vary depending on the number and location of idle secondary non-backoff channels within the third and fourth channel subsets. If idle secondary channels are discontinuous, a punctured PPDU may be transmitted.

Example 6-3

This embodiment relates to the secondary channel access operation of an STA according to the aforementioned embodiments 6-1 and 6-2. Here, the STA may be an AP STA or a non-AP STA.

An STA performing secondary channel access may transmit frames/PPDUs on one or more secondary channels even while the primary channel is busy (e.g., a state in which a default NAV is set for the primary channel). For example, the STA may transmit frames/PPDUs with the primary channel excluded/punctured on one or more secondary channels that are idle, through a backoff process performed on one or more secondary backoff channels and a CCA for one or more secondary non-backoff channels.

Additionally or alternatively, a TXOP initiated by a frame/PPDU transmission on the SCH may be configured to end before the NAV for the primary channel ends. The length of the TXOP may be configured/indicated via the Duration/ID field of the corresponding frame. For example, the value of the Duration/ID field may be set to a value corresponding to the time required for the exchange of the frame/PPDU(s) following the corresponding frame/PPDU (e.g., the time including the length of the frame/PPDU(s) and the interframe gap (IFS)).

Additionally or alternatively, secondary channel access-related configuration information, such as information on whether frame/PPDU transmission is possible on a secondary channel, secondary channel access bandwidth (i.e., in channel subset units), and information on one or more secondary channels on which backoff is performed when transmission is possible (i.e., secondary backoff channels), may be included in a management frame (e.g., a beacon frame) transmitted by the AP. If the STA performing secondary channel access is an AP STA, the STA may perform secondary channel access using the secondary channel access-related configuration information transmitted by the STA. If the STA performing secondary channel access is a non-AP STA, the STA may perform secondary channel access using the secondary channel access-related configuration information received from the AP STA.

Additionally or alternatively, information regarding one or more secondary channels (i.e., secondary backoff channels) performing backoff may be transmitted based on channel subsets that divide the bandwidth of the overall BSS operating channel into certain units (e.g., 40 MHz, 80 MHz, etc.). For example, a secondary backoff channel may be indicated in each of the divided channel subsets. In some examples, one or more channel subsets that do not include the secondary backoff channel may be configured.

Additionally or alternatively, if the backoff counter for a secondary backoff channel within a channel subset becomes 0, the channel on which the second type of CCA (i.e., CCA based on guard interval detection (GID) or energy detection (ED)) may be performed may correspond to another secondary channel (i.e., secondary non-backoff channel)(s) included in the same channel subset. If multiple channel subsets are configured, the channel on which the second type of CCA is performed in the other channel subset(s) may also correspond to a secondary non-backoff channel.

For example, with respect to the aforementioned embodiment 6-1 (i.e., an example in which separate/independent EDCA parameter sets are set for multiple secondary backoff channels), if the first backoff counter for the first secondary backoff channel becomes 0, even if the second backoff counter for the second secondary backoff channel does not become 0, the frame/PPDU may be transmitted first on the secondary backoff channel (and zero or more secondary non-backoff channels) whose backoff counter has expired.

Additionally or alternatively, with respect to the aforementioned embodiment 6-1 (i.e., the example where separate/independent EDCA parameter sets are set for multiple secondary backoff channels), when the first backoff counter for the first secondary backoff channel becomes 0, transmission on the first secondary backoff channel may be waited/postponed until the second backoff counter for the second secondary backoff channel becomes 0, and when the second backoff counter becomes 0, a frame/PPDU may be transmitted on the first secondary backoff channel and the second secondary backoff channel (and zero or more secondary non-backoff channels).

For example, with respect to the aforementioned embodiment 6-2 (i.e., an example in which one common EDCA parameter set is set for multiple secondary backoff channels), one common backoff counter may be applied to multiple (or all) secondary backoff channels. In this case, the common backoff counter may be decremented when at least one secondary backoff channel among the first and second secondary backoff channels is idle (i.e., even when the other secondary backoff channels are busy). Additionally or alternatively, the common backoff counter may be decremented when both the first and second secondary backoff channels are idle.

Additionally or alternatively, information on the maximum bandwidth for transmitting frames/PPDUs on a secondary channel may be included in a management frame (e.g., a beacon frame) transmitted by the AP. If the STA performing secondary channel access is an AP STA, the STA may perform secondary channel access using the maximum bandwidth information for transmitting frames/PPDUs related to secondary channel access transmitted by the STA. If the STA performing secondary channel access is a non-AP STA, the STA may perform secondary channel access using the maximum bandwidth information for transmitting frames/PPDUs related to secondary channel access received from the AP STA.

Additionally or alternatively, the EDCA parameter set for the secondary backoff channel may be set to be identical to the EDCA parameter set for the primary channel, or may be set as an MU EDCA parameter set, or may be set as a new EDCA parameter set. The EDCA parameter set for the secondary backoff channel may be set individually/independently (i.e., may be identical or different) for different secondary backoff channels, as in Embodiment 6-1, or may be set identically/commonly for different secondary backoff channels, as in Embodiment 6-2.

Additionally or alternatively, the busy or idle state may be determined based on whether the measured power on the secondary backoff/non-backoff channel is above or below a predetermined threshold, and this threshold may be set for each of the first type CCA and the second type CCA. The threshold for the first type CCA and/or the threshold for the second type CCA may be included in a management frame (e.g., a beacon frame) transmitted by the AP. If the STA performing the secondary channel access is an AP STA, the STA may perform the secondary channel access using the threshold for the first type CCA and/or the threshold for the second type CCA transmitted by the STA. If an STA performing secondary channel access is a non-AP STA, the STA may perform secondary channel access using a threshold for the first type CCA and/or a threshold for the second type CCA received from the AP STA. In various examples of the present disclosure, an STA receiving a frame/PPDU transmitted through secondary channel access may perform frame/PPDU detection on the secondary channel even during the time when the NAV for the primary channel is set. For example, the STA may perform backoff on the secondary channel because it has a frame to transmit, or may attempt to receive a frame addressed to itself on the secondary channel even when it has no frame to transmit. In addition, the STA may perform NAV setting/resetting on the secondary channel based on the value of the duration/ID field of the frame detected on the secondary channel.

Unlike backoff-based channel access for a primary channel in a conventional wireless LAN system, backoff-based channel access for a secondary channel (or non-primary channel) according to examples of the present disclosure can support rapid frame/PPDU transmission or transmission rate improvement on idle secondary channel(s) even when the primary channel is busy.

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

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

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

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

Claims (18)

A method performed by a first station (STA) in a wireless LAN system, the method comprising:
A step of receiving information about a plurality of enhanced distributed channel access (EDCA) parameter sets, each set being associated with a plurality of non-primary backoff channels, from a second STA;
A step of performing a backoff process based on the plurality of EDCA parameter sets on the plurality of non-primary backoff channels; and
A method comprising the step of transmitting one or more physical layer protocol data units (PPDUs) on one or more channels including one or more of the plurality of non-primary backoff channels and zero or more non-primary non-backoff channels. In the first paragraph,
A method wherein a first backoff process based on a first EDCA parameter set for a first non-primary backoff channel and a second backoff process based on a second EDCA parameter set for a second non-primary backoff channel are performed in parallel or independently. In the second paragraph,
The first backoff process includes decrementing a first backoff counter based on the medium on the first non-primary backoff channel being determined to be idle based on the first EDCA parameter set,
A method wherein the second backoff process comprises decrementing a second backoff counter based on determining that the medium on the second non-primary backoff channel is idle based on the second EDCA parameter set. In the third paragraph,
Based on the first backoff counter expiring and the second backoff counter not expiring:
A method wherein one PPDU is transmitted on the first non-primary backoff channel and zero or more first non-primary non-backoff channels associated with the first non-primary backoff channel. In the third paragraph,
Based on the first backoff counter expiring and the second backoff counter not expiring:
A method wherein transmission of a PPDU on the first non-primary backoff channel and zero or more first non-primary non-backoff channels associated with the first non-primary backoff channel is deferred. In paragraph 5,
Based on the expiration of the second backoff counter after the expiration of the first backoff counter:
The first non-primary backoff channel;
The above zero or more first non-primary non-backoff channels;
the second non-primary backoff channel; and
Zero or more second non-primary non-backoff channels associated with the second non-primary backoff channel.
A method in which one or more PPDUs are transmitted above. In paragraph 6,
a first PPDU on the first non-primary backoff channel and zero or more first non-primary non-backoff channels, and
A second PPDU on the second non-primary backoff channel and zero or more second non-primary non-backoff channels.
A method in which signals are transmitted simultaneously. In paragraph 6,
The first non-primary backoff channel;
The above zero or more first non-primary non-backoff channels;
the second non-primary backoff channel; and
Zero or more second non-primary non-backoff channels above
A method in which one PPDU is transmitted on the top. In paragraph 8,
A method wherein the above one PPDU is transmitted on contiguous channels or non-contiguous channels. In the first paragraph,
A method wherein one non-primary non-backoff channel included in the one or more channels is a non-primary channel determined to be idle by a non-primary channel clear channel assessment (CCA) for a predetermined period of time before the expiration of a backoff counter for a non-primary backoff channel associated with the one non-primary non-backoff channel. In the first paragraph,
A method wherein the plurality of non-primary backoff channels are included in the same channel subset or in different channel subsets. In paragraph 11,
The number of non-primary backoff channels included in a channel subset is one or more,
A method wherein the number of non-primary non-backoff channels included in one channel subset is 0 or more. In paragraph 12,
A method wherein the one channel subset corresponds to a maximum bandwidth for a PPDU transmitted based on a backoff process for one or more non-primary backoff channels included in the one channel subset. In a first station (STA) device in a wireless LAN system, the device:
one or more transmitters and receivers; and
comprising one or more processors connected to said one or more transceivers,
One or more of the above processors:
Receive information about a plurality of enhanced distributed channel access (EDCA) parameter sets, each associated with a plurality of non-primary backoff channels, from a second STA through the one or more transceivers;
Performing a backoff process based on the plurality of EDCA parameter sets on the plurality of non-primary backoff channels; and
A device configured to transmit one or more physical layer protocol data units (PPDUs) through one or more transceivers on one or more of the plurality of non-primary backoff channels, and one or more channels including zero or more non-primary non-backoff channels. A method performed by a second station (STA) in a wireless LAN system, the method comprising:
A step of transmitting information about a plurality of enhanced distributed channel access (EDCA) parameter sets, each associated with a plurality of non-primary backoff channels, to a first STA; and
A method comprising the step of receiving, from the first STA, one or more physical layer protocol data units (PPDUs) on one or more channels including one or more of the plurality of non-primary backoff channels and zero or more non-primary non-backoff channels, through a backoff process performed based on the plurality of EDCA parameter sets on the plurality of non-primary backoff channels, transmitted by the first STA. In a second station (STA) device in a wireless LAN system, the device:
one or more transmitters and receivers; and
comprising one or more processors connected to said one or more transceivers,
One or more of the above processors:
Transmitting information about a plurality of enhanced distributed channel access (EDCA) parameter sets, each associated with a plurality of non-primary backoff channels, to a first STA via the one or more transceivers; and
A device configured to receive, from the first STA, one or more physical layer protocol data units (PPDUs) on one or more channels including one or more of the plurality of non-primary backoff channels and zero or more non-primary non-backoff channels, through a backoff process performed based on the plurality of EDCA parameter sets on the plurality of non-primary backoff channels, through the one or more transceivers. In a processing device configured to control a station (STA) in a wireless LAN system, the processing device:
one or more processors; and
A processing device comprising one or more computer memories operatively connected to said one or more processors and storing instructions that, when executed by said one or more processors, perform a method according to any one of claims 1 to 13. One or more non-transitory computer-readable media storing one or more instructions,
A computer-readable medium, wherein the one or more commands are executed by one or more processors to control a device in a wireless LAN system to perform a method according to any one of claims 1 to 13.