CN121444577A

CN121444577A - Methods and apparatus for backoff related to non-primary channel access in wireless LAN systems

Info

Publication number: CN121444577A
Application number: CN202480043368.8A
Authority: CN
Inventors: 张仁善; 崔镇洙; 白善熙; 金虔焕; 尹艺邻; 车东柱
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2023-07-03
Filing date: 2024-06-17
Publication date: 2026-01-30
Also published as: WO2025009776A1; KR20260030717A

Abstract

A backoff method and apparatus related to non-primary channel access in a wireless LAN system are disclosed. A method performed by a first station (STA) in a wireless LAN system according to one embodiment of this disclosure may include the following steps: receiving from a second STA information about multiple Enhanced Distributed Channel Access (EDCA) parameter sets, each associated with a plurality of non-primary backoff channels; performing a backoff process on the plurality of non-primary backoff channels based on the multiple EDCA parameter sets; and 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 of the non-primary non-backoff channels.

Description

Backoff method and apparatus related to non-primary channel access in wireless LAN system

Technical Field

The present disclosure relates to a backoff method and apparatus related to non-primary channel access in a Wireless Local Area Network (WLAN) system.

Background

New technologies for improving transmission rate, increasing bandwidth, improving reliability, reducing errors, and reducing delay have been introduced for Wireless LANs (WLANs). In WLAN technology, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards may be referred to as Wi-Fi. For example, technologies recently introduced into WLANs include Very High Throughput (VHT) enhancements of the 802.11ac standard and High Efficiency (HE) enhancements of the IEEE 802.11ax standard.

In order to provide a more advanced wireless communication environment, improved techniques for Extremely High Throughput (EHT) are being discussed. For example, techniques for MIMO and multi-Access Point (AP) coordination supporting increased bandwidth, efficient use of multiple frequency bands, and increased spatial streams are being studied, and in particular, various techniques 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.

Disclosure of Invention

Technical problem

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

Another technical problem of the present disclosure is to provide a backoff method and apparatus for non-primary channel access based on a subset of channels in a WLAN system.

Technical objects to be achieved by the present disclosure are not limited to the above technical objects, and other technical objects not described herein will be apparent to those skilled in the art from the following description.

Technical proposal

According to an aspect of the present disclosure, a method performed by a first Station (STA) in a WLAN system may include receiving information for a plurality of Enhanced Distributed Channel Access (EDCA) parameter sets respectively associated with a plurality of non-primary backoff channels from a second STA, performing a backoff procedure on the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets, and transmitting at least one physical layer protocol data unit (PPDU) on at least one channel including at least one of the plurality of non-primary backoff channels and at least zero non-primary non-backoff channels.

In accordance with additional aspects of the present disclosure, a method performed by a second Station (STA) in a WLAN system may include transmitting information for a plurality of Enhanced Distributed Channel Access (EDCA) parameter sets respectively associated with a plurality of non-primary backoff channels to a first STA, and receiving at least one physical layer protocol data unit (PPDU) from the first STA over at least one channel including at least one of the plurality of non-primary backoff channels and at least zero non-primary non-backoff channels, the at least one PPDU being transmitted by the first STA through a backoff procedure performed over the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets.

Technical effects

According to the present disclosure, a backoff method and apparatus related to non-primary channel access in a WLAN system may be provided.

According to the present disclosure, a backoff method and apparatus for non-primary channel access based on a subset of channels in a WLAN system may be provided.

The effects achievable by the present disclosure are not limited to the above-described effects, and other effects not described herein can be clearly understood by those skilled in the relevant art through the following description.

Drawings

The accompanying drawings, which are included to provide a further understanding of embodiments of the disclosure, illustrate embodiments of the disclosure and together with the description serve to describe features of the disclosure.

Fig. 1 illustrates a block diagram of a configuration of a wireless communication device according to an embodiment of the present disclosure.

Fig. 2 is a diagram illustrating an exemplary structure of a WLAN system to which the present disclosure may be applied.

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

Fig. 4 is a diagram for explaining back-off processing 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 diagram for explaining an example of a frame structure used in a WLAN system to which the present disclosure can be applied.

Fig. 7 is a diagram illustrating an example of a PPDU defined in the IEEE 802.11 standard to which the present disclosure may be applied.

Fig. 8 is a diagram for describing an example of channel access based on a primary channel to which the present disclosure may be applied.

Fig. 9 is a diagram for describing an example of a method performed by a first STA according to the present disclosure.

Fig. 10 is a diagram for describing an example of a method performed by a second STA according to the present disclosure.

Fig. 11 is a diagram for describing an example of secondary channel access according to the present disclosure.

Fig. 12 is a diagram for describing a case where BSS channels overlap between APs according to an embodiment of the present disclosure.

Fig. 13 is a diagram for describing a process in which an AP transmits announcement information related to a SCA according to an embodiment of the present disclosure.

Fig. 14 is a diagram for describing a backoff procedure when the bandwidth of the BSS operation channel is 160MHz according to an embodiment of the present disclosure.

Fig. 15 is a diagram for describing a backoff procedure when the bandwidth of the BSS operation channel is 320MHz according to an embodiment of the present disclosure.

Fig. 16 to 18 are diagrams showing examples of a multi-backoff-based secondary channel access operation according to the present disclosure.

Detailed Description

Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description disclosed by the drawings is intended to describe exemplary embodiments of the disclosure and is not intended to represent the only embodiments in which the disclosure may be practiced. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the relevant art that the present disclosure may be practiced without these specific details.

In some cases, known structures and devices may be omitted or may be shown in block diagram form based on the core function of each structure and device in order to prevent ambiguity of the concepts of the present disclosure.

In this disclosure, when an element is referred to as being "connected," "combined," or "linked" to another element, it can comprise the indirect connection and the direct connection of yet another element therebetween. Furthermore, in the present disclosure, the terms "comprises" and/or "comprising" specify the presence of stated features, steps, operations, components, and/or elements, but do not preclude the presence or addition of one or more other features, stages, operations, components, elements, and/or groups thereof.

In this disclosure, terms such as "first," "second," and the like are used merely to distinguish one element from another element and are not intended to limit the order or importance between the elements unless otherwise indicated. Thus, within the scope of the present disclosure, a first element in an embodiment may be referred to as a second element in another embodiment, and as such, a second element in an embodiment may be referred to as a first element in another embodiment.

The terminology used in the present disclosure is for the purpose of describing particular embodiments, and is not intended to limit 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 indicates otherwise. The term "and/or" as used in this disclosure may refer to one of the relevant listed items or to any and all possible combinations of two or more of them. Furthermore, unless otherwise indicated, the words "/" and/or "between words in this disclosure have the same meaning.

Examples of the present disclosure may be applied to various wireless communication systems. For example, examples of the present disclosure may be applied to wireless LAN systems. For example, examples of the present disclosure may be applied to wireless LANs based on the IEEE 802.11a/g/n/ac/ax standard. Further, examples of the present disclosure may be applied to wireless LANs based on the newly proposed IEEE 802.11be (or EHT) standard. Examples of the present disclosure may be applied to wireless LANs based on the IEEE 802.11be version 2 standard corresponding to additional enhancements of the IEEE 802.11be version 1 standard. In addition, examples of the present disclosure may be applied to a wireless LAN based on the next generation standard after IEEE 802.11 be. Further, examples of the present disclosure may be applied to cellular wireless communication systems. For example, it may be applied to a cellular wireless communication system based on Long Term Evolution (LTE) technology and on 5G New Radio (NR) technology based on the third generation partnership project (3 GPP) standard.

Hereinafter, technical features to which examples of the present disclosure can be applied will be described.

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

The first apparatus 100 and the second apparatus 200 illustrated in fig. 1 may be replaced with various terms such as a terminal, a wireless apparatus, a Wireless Transmit Receive Unit (WTRU), a User Equipment (UE), a Mobile Station (MS), a User Terminal (UT), a mobile subscriber station (MSs), a Mobile Subscriber Unit (MSU), a Subscriber Station (SS), an Advanced Mobile Station (AMS), a Wireless Terminal (WT), or a simple user. In addition, the first apparatus 100 and the second apparatus 200 include an Access Point (AP), a Base Station (BS), a fixed station, a node B, a Base Transceiver System (BTS), a network. It may be replaced with various terms such as an Artificial Intelligence (AI) system, a roadside unit (RSU), a repeater, a router, a relay, and a gateway.

The apparatuses 100 and 200 illustrated in fig. 1 may be referred To As Stations (STAs). For example, the apparatuses 100 and 200 illustrated in fig. 1 may be referred to by various terms such as a transmitting apparatus, a receiving apparatus, a transmitting STA, and a receiving STA. For example, STAs 110 and 200 may perform an Access Point (AP) role or a non-AP role. That is, in the present disclosure, STAs 110 and 200 may perform AP and/or non-AP functions. STAs 110 and 200 may be simply referred to as APs when they perform AP functions, and STAs 110 and 200 may be simply referred to as STAs when they perform non-AP functions. In addition, in the present disclosure, an AP may also be indicated as an AP STA.

Referring to fig. 1, the first device 100 and the second device 200 may transmit and receive radio signals through various wireless LAN technologies (e.g., IEEE 802.11 series). The first apparatus 100 and the second apparatus 200 may include interfaces for a Medium Access Control (MAC) layer and a physical layer (PHY) compliant with the IEEE 802.11 standard.

In addition, the first apparatus 100 and the second apparatus 200 may additionally support various communication standard (e.g., 3GPP LTE series, 5G NR series standards, etc.) technologies in addition to the wireless LAN technology. In addition, the apparatus of the present disclosure may be implemented in various apparatuses such as a mobile phone, a vehicle, a personal computer, an Augmented Reality (AR) device, and a Virtual Reality (VR) device. In addition, STAs of the present description may support various communication services such as voice calls, video calls, data communications, autonomous driving, machine Type Communications (MTC), machine-to-machine (M2M), device-to-device (D2D), ioT (internet of things), and the like.

The first apparatus 100 may include one or more processors 102 and one or more memories 104, and may additionally include one or more transceivers 106 and/or one or more antennas 108. The processor 102 may control the memory 104 and/or the transceiver 106 and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts included in the present disclosure. For example, the processor 102 may transmit a wireless signal including the first information/signal through the transceiver 106 after generating the first information/signal by processing the information in the memory 104. In addition, the processor 102 may receive a wireless signal including the second information/signal through the transceiver 106 and then store information obtained through signal processing of the second information/signal in the memory 104. The memory 104 may be connected to the processor 102 and may store various information related to the operation of the processor 102. For example, the memory 104 may store software code including instructions for performing all or part of the processing controlled by the processor 102 or for performing descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts included in the present disclosure. Here, the processor 102 and the memory 104 may be part of a communication modem/circuit/chip designed to implement wireless LAN technology (e.g., IEEE 802.11 family). The transceiver 106 may be coupled to the processor 102 and may transmit and/or receive wireless signals via one or more antennas 108. Transceiver 106 may include a transmitter and/or a receiver. The transceiver 106 may be used with an RF (radio frequency) unit. In this disclosure, a wireless device may mean a communication modem/circuit/chip.

The second apparatus 200 may include one or more processors 202 and one or more memories 204, and may additionally include one or more transceivers 206 and/or one or more antennas 208. The processor 202 may control the memory 204 and/or the transceiver 206 and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts included in the present disclosure. For example, the processor 202 may generate the third information/signal by processing the information in the memory 204 and then transmit a wireless signal including the third information/signal through the transceiver 206. In addition, the processor 202 may receive a wireless signal including fourth information/signals through the transceiver 206 and then store information obtained through 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 store software code including instructions for performing all or part of the processing controlled by the processor 202 or for performing descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts included in the present disclosure. Here, the processor 202 and the memory 204 may be part of a communication modem/circuit/chip designed to implement wireless LAN technology (e.g., IEEE 802.11 family). The transceiver 206 may be coupled to the processor 202 and may transmit and/or receive wireless signals via one or more antennas 208. Transceiver 206 may include a transmitter and/or a receiver. The transceiver 206 may be used with an RF unit. In this disclosure, an apparatus may refer to a communication modem/circuit/chip.

Hereinafter, the hardware elements of the apparatus 100, 200 will be described in more detail. Without limitation, 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). The one or more processors 102, 202 may generate one or more PDUs (protocol data units) and/or one or more SDUs (service data units) according to the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in the present disclosure. One or more processors 102, 202 may generate messages, control information, data, or information in accordance with the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this disclosure. The one or more processors 102, 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information to provide to the one or more transceivers 106, 206 according to the functions, procedures, suggestions, and/or methods disclosed in the present disclosure. The one or more processors 102, 202 may receive signals (e.g., baseband signals) from the one or more transceivers 106, 206 and obtain PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts included in the present disclosure.

One or more of the processors 102, 202 may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more of the processors 102, 202 may be implemented in hardware, firmware, software, or a combination thereof. For example, one or more ASICs (application specific integrated circuits), one or more DSPs (digital signal processors), one or more DSPDs (digital signal processing devices), one or more PLDs (programmable logic devices), or one or more FPGAs (field programmable gate arrays) may be included in the one or more processors 102, 202. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts included in the present disclosure may be implemented by using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, and so on. Firmware or software configured to perform the descriptions, functions, procedures, suggestions, methods, and/or operational flow diagrams included in the present disclosure may be included in one or more processors 102, 202 or may be stored in one or more memories 104, 204 and driven by one or more processors 102, 202. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts included in the present disclosure may be implemented using firmware or software in the form of codes, instructions and/or instruction sets.

The one or more memories 104, 204 may be connected to the one or more processors 102, 202 and may store data, signals, messages, information, programs, code, instructions, and/or commands in various forms. One or more of the memories 104, 204 may be configured with ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage medium, and/or combinations thereof. The one or more memories 104, 204 may be located internal and/or external to the one or more processors 102, 202. In addition, one or more memories 104, 204 may be connected to one or more processors 102, 202 through various techniques, such as a wired or wireless connection.

One or more transceivers 106, 206 may transmit user data, control information, wireless signals/channels, etc. referred to in the methods and/or operational flowcharts, etc. of the present disclosure to one or more other devices. One or more transceivers 106, 206 may receive user data, control information, wireless signals/channels, etc. referred to in descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts, etc. included in the present disclosure, from one or more other devices. For example, one or more transceivers 106, 206 may be connected to one or more processors 102, 202 and may transmit and receive wireless signals. For example, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to transmit user data, control information, or wireless signals to one or more other devices. In addition, the one or more processors 102, 202 may control the one or more transceivers 106, 206 to receive user data, control information, or wireless signals from one or more other devices. In addition, one or more transceivers 106, 206 may be connected 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, etc. mentioned in descriptions, functions, procedures, suggestions, methods, operational flowcharts, etc. included in the present disclosure through one or more antennas 108, 208. In the present disclosure, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). The one or more transceivers 106, 206 may convert received wireless signals/channels, etc. from RF band signals to baseband signals to process received user data, control information, wireless signals/channels, etc. using the one or more processors 102, 202. The one or more transceivers 106, 206 may convert user data, control information, wireless signals/channels, etc., processed by using the one or more processors 102, 202 from baseband signals to RF band signals. Thus, one or more transceivers 106, 206 may include (analog) oscillators and/or filters.

For example, one of the STAs 100 and 200 may perform the intended operation of the AP, and the other of the STAs 100 and 200 may perform the intended operation of the non-AP STA. For example, transceivers 106 and 206 of fig. 1 may perform transmission and reception operations of signals (e.g., IEEE 802.11a/b/g/n/ac/ax/be/bn compliant packets or physical layer protocol data units (PPDUs)). In addition, in the present disclosure, operations of various STAs generating transmission/reception signals or performing data processing or calculation in advance with respect to the transmission/reception signals may be performed by the processors 102 and 202 of fig. 1. For example, examples of operations to generate a transmission/reception signal or perform data processing or calculation in advance with respect to the transmission/reception signal may include 1) determining/acquiring/configuring/calculating/decoding/encoding bit information of fields (signal (SIG), short Training Field (STF), long Training Field (LTF), data, etc.) included in the PPDU, 2) determining/configuring/acquiring time resources or frequency resources (e.g., subcarrier resources) for fields (SIG, STF, LTF, data, etc.) included in the PPDU, 3) determining/configuring/acquiring specific sequences (e.g., pilot sequences, STF/LTF sequences, additional sequences applied to the SIG) for fields (SIG, STF, LTF, data, etc.) included in PPDU actions, 4) power control operations and/or power saving operations applied to the STA, 5) operations related to ACK signal determination/acquisition/configuring/calculating/decoding/encoding, etc. In addition, in the following examples, various information (e.g., information related to fields/subfields/control fields/parameters/power, etc.) used by various STAs to determine/acquire/configure/calculate/decode/encode transmission signals and reception signals may be stored in the memories 104 and 204 of fig. 1.

Hereinafter, downlink (DL) may mean a link for communication from an AP STA to a non-AP STA, and may transmit and receive DL PPDUs/packets/signals through DL. In DL communication, the transmitter may be part of an AP STA and the receiver may be part of a non-AP STA. The Uplink (UL) may mean a link for communication from a non-AP STA to an AP STA, and may transmit and receive UL PPDUs/packets/signals through the UL. In UL 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 illustrating an exemplary structure of a wireless LAN system to which the present disclosure can be applied.

The structure of the wireless LAN system may be constituted by a plurality of components. A wireless LAN supporting STA mobility transparent to upper layers may be provided through interaction of multiple components. A Basic Service Set (BSS) corresponds to a basic building block of a wireless LAN. Fig. 2 exemplarily shows that there are two BSSs (BSS 1 and BSS 2), and two STAs included as members of each BSS (STA 1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS 2). The ellipse representing the BSS in fig. 2 may also be understood as representing the coverage area in which STAs included in the corresponding BSS remain in communication. This region may be referred to as a Basic Service Area (BSA). When an STA moves outside the BSA, it cannot communicate directly with other STAs within the BSA.

If the DS shown in fig. 2 is not considered, the most basic BSS type in the wireless LAN is an Independent BSS (IBSS). For example, an IBSS may have a minimal form that includes only two STAs. For example, assuming that other components are omitted, BSS1 including only STA1 and STA2 or BSS2 including only STA3 and STA4 may correspond to representative examples of IBSS, respectively. This configuration is possible when STAs can communicate directly without an AP. In addition, in this type of wireless LAN, it is not preconfigured, but may be configured when a LAN is required, and this may be referred to as an ad-hoc (ad-hoc) network. Since IBSS does not include an AP, there is no centralized management entity. That is, in IBSS, STAs are managed in a distributed manner. In an IBSS, all STAs may consist of mobile STAs and are not allowed to access the Distributed System (DS), thus forming a self-contained network.

Membership of STAs in a BSS may be dynamically changed by switching the STAs on or off, entering or exiting a BSS area, etc. To become a member of the BSS, the STA may join the BSS using a synchronization process. To access all services of the BSS infrastructure, the STA should be associated with the BSS. The association may be dynamically established and may include use of a Distributed System Service (DSS).

The direct STA-to-STA distance in a wireless LAN may be limited by PHY performance. In some cases, this distance limitation may be sufficient, but in some cases, communication between STAs at longer distances may be required. A Distributed System (DS) may be configured to support extended coverage.

DS means a structure in which BSSs are interconnected. Specifically, as shown in fig. 2, the BSS may exist as an extension of a network composed of a plurality of BSSs. DS is a logical concept and may be specified by the characteristics of a Distributed System Medium (DSM). In this regard, the Wireless Medium (WM) and DSM may be logically separated. Each logic medium serves a different purpose and is used by different components. These media are not limited to being identical nor are they limited to being different. In this way, the flexibility of the wireless LAN structure (DS structure or other network structure) can be interpreted as a plurality of media being logically different. That is, the wireless LAN structure may be implemented in various ways, and the corresponding wireless LAN structure may be independently specified by the physical characteristics of each embodiment.

The DS may support mobile devices by providing seamless integration of multiple BSSs and providing the logical services necessary to address addresses to destinations. In addition, the DS may also include a component called a portal, which is used as a bridge for connection between the wireless LAN and other networks (e.g., IEEE 802. X).

The AP enables access to the DS by the WM for associated non-AP STAs and means entities that also have STA functionality. Data movement between the BSS and the DS may be performed by the AP. For example, STA2 and STA3 shown in fig. 2 have functions of STAs and provide functions of allowing associated non-AP STAs (STA 1 and STA 4) to access the DS. In addition, since all APs correspond to STAs substantially, all APs are addressable entities. The address used by the AP to communicate on the WM is not necessarily the same as the address used by the AP to communicate on the DSM. A BSS made up of an AP and one or more STAs may be referred to as an infrastructure BSS.

Data transmitted from one of the STAs associated with the AP to the STA address of the corresponding AP may always be received at the uncontrolled port and may be processed by the IEEE 802.1X port access entity. In addition, when the controlled port is authenticated, transmission data (or frames) may be delivered to the DS.

In addition to the structure of the DS described above, an Extended Service Set (ESS) may also be configured to provide wide coverage.

ESS means a network consisting of DS and BSS with arbitrary size and complexity. The ESS may correspond to a set of BSSs connected to one DS. However, the ESS does not include a DS. The ESS network is characterized as an IBSS in the Logical Link Control (LLC) layer. STAs included in the ESS may communicate with each other and the mobile STA may move transparently to the LLC from one BSS to another BSS (within the same ESS). The APs included in one ESS may have the same Service Set Identification (SSID). The SSID is distinguished from the BSSID, which is an identifier of the BSS.

The wireless LAN system does not assume anything about the relative physical location of the BSS, and all the following forms are possible. BSSs may overlap in part, which is a form commonly used to provide continuous coverage. In addition, BSSs may not be physically connected, and logically, there is no limitation on the distance between BSSs. In addition, BSSs may be physically co-located, which may be used to provide redundancy. In addition, one (or more than one) IBSS or ESS network may physically exist in the same space as one (or more than one) ESS network. This may correspond to the form of the ESS network, etc. when the ad hoc network operates in a location where the ESS network exists, when physically overlapping wireless networks are configured by different organizations, or when two or more different access and security policies are required in the same location.

In order for the STA to establish a link with respect to the network and transmit/receive data, it first discovers the network, performs authentication, establishes association, and needs to perform authentication processing for security. The link establishment process may also be referred to as a session initiation process or a session establishment process. In addition, the processes of discovery, authentication, association, and security establishment of the link establishment process may be collectively referred to as association process.

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

The scanning scheme includes active scanning and passive scanning. Fig. 3 exemplarily illustrates a network discovery operation including an active scanning process. In the active scanning, the STA performing the scanning transmits a probe request frame to discover which APs exist around it while the channel moves and waits for a response thereto. The responder transmits a probe response frame as a response to the probe request frame to the STA that has transmitted the probe request frame. Here, the responder may be a STA that finally transmits a beacon frame in the BSS of the channel being scanned. In the BSS, the AP becomes a responder since the AP transmits a beacon frame, and in the IBSS, the STA in the IBSS rotates to transmit the beacon frame, so the responder is not constant. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 may store BSS-related information included in the received probe response frame and may move to the next channel (e.g., channel 2) and perform scanning in the same manner (i.e., transmission and reception of probe request/response on channel 2).

Although not shown in fig. 3, the scanning operation may be performed in a passive scanning manner. In passive scanning, a STA performing scanning waits for a beacon frame while a channel moves. The beacon frame is one of management frames defined in IEEE 802.11 and is periodically transmitted to notify that a wireless network exists, and allow STAs performing scanning to find and participate in the wireless network. In a BSS, an AP is used to periodically transmit a beacon frame, and in an IBSS, STAs within the IBSS rotate to transmit the beacon frame. When the STA performing scanning receives the beacon frame, the STA stores information of the BSS included in the beacon frame and records the beacon frame information in each channel while moving to another channel. The STA receiving the beacon frame may store BSS-related information included in the received beacon frame, move to the next channel, and perform scanning in the next channel in the same manner. Comparing active scanning with passive scanning has the advantage of having less delay and less power consumption than passive scanning.

After the STA discovers the network, an authentication process may be performed at step S320. This authentication process may be referred to as a first authentication process in order to clearly distinguish from the security setup operation of step S340, which will be described later.

The authentication process includes a process in which the STA transmits an authentication request frame to the AP, and in response thereto, the AP transmits an authentication response frame to the STA. The authentication frame for authentication request/response corresponds to the management frame.

The authentication frame includes an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge plaintext (CHALLENGE TEXT), a Robust Secure Network (RSN), a limited set of loops, and the like. This corresponds to some examples of information that may be included in the authentication request/response frame, and may be replaced with other information, or additional information may also be included.

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

After the STA is successfully authenticated, association processing may be performed at 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 related to various capabilities, beacon listening intervals, service Set Identifiers (SSID), supported rates, supported channels, RSNs, mobility domains, supported operation categories, traffic indication map broadcast requests (TIM broadcast requests), interworking service capabilities, and so forth. For example, the association response frame may include information related to various capabilities, status codes, association IDs (AID), supported rates, enhanced Distributed Channel Access (EDCA) parameter sets, received Channel Power Indicator (RCPI), received signal-to-noise indicator (RSNI), mobility domain, time-out interval (e.g., association recovery time), overlapping BSS scan parameters, TIM broadcast response, quality of service (QoS) mapping, and so forth. This corresponds to some examples of information that may be included in the association request/response frame, and may be replaced with other information, or additional information may also be included.

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

The security establishment process of step S340 may include, for example, a process of establishing a private key through an Extensible Authentication Protocol (EAPOL) frame on the LAN using a four-way handshake. In addition, the security establishment process may be performed according to a security scheme not defined in the IEEE 802.11 standard.

In wireless LAN systems, the basic access mechanism for Medium Access Control (MAC) is a carrier sense multiple access with collision avoidance (CSMA/CA) mechanism. The CSMA/CA mechanism is also known as the Distributed Coordination Function (DCF) of IEEE 802.11MAC, and basically employs a "listen before talk" access mechanism. According to this type of access mechanism, the AP and/or STA may perform Clear Channel Assessment (CCA) of the sensed radio channel or medium during a predetermined time interval (e.g., DCF inter-frame space (DIFS)) before beginning to transmit. As a result of the sensing, if it is determined that the medium is in an idle state, frame transmission is started through the corresponding medium. On the other hand, if it is detected that the medium is occupied or busy, the corresponding AP and/or STA does not start its own transmission, and a delay period (e.g., a random backoff period) for medium access may be set and frame transmission is attempted after waiting. By applying the random backoff period, collisions may be minimized since multiple STAs are expected to attempt frame transmission after waiting different time periods.

In addition, the IEEE 802.11MAC protocol provides a Hybrid Coordination Function (HCF). HCF is based on DCF and Point Coordination Function (PCF). PCF is a synchronous access method based on polling and refers to a method in which all receiving APs and/or STAs periodically poll to receive a data frame. In addition, HCFs have Enhanced Distributed Channel Access (EDCA) and HCF Control Channel Access (HCCA). EDCA is a contention-based access method that provides data frames to a plurality of users, and HCCA uses a non-contention-based channel access method using a polling mechanism. In addition, the HCF includes a medium access mechanism for improving QoS (quality of service) of the wireless LAN, and can transmit QoS data in a Contention Period (CP) and a contention-free period (CFP).

Referring to fig. 4, an operation based on the random backoff period will be described. When the busy/busy medium becomes an idle state, multiple STAs may attempt to transmit data (or frames). As a method of minimizing collision, each of STAs may select a random backoff count separately and attempt transmission after waiting for a corresponding slot time. The random back-off count has a pseudo-random integer value and may be determined as one of values ranging from 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given as CWmin of an initial value, but may take a value twice as large in the case of transmission failure (for example, when ACK for a transmitted frame is not received). When the CW parameter value reaches CWmax, data transmission may be attempted while maintaining the CWmax value until data transmission is successful, and when data transmission is successful, the CWmin value is reset. The values of CW, CWmin and CWmax are preferably set to 2n-1 (n=0, 1, 2).

When the random backoff process starts, the STA continuously monitors the medium in a backoff slot countdown according to the determined backoff count value. When the medium is monitored for occupancy, it stops counting down and waits, and when the medium becomes idle, the remainder of the counting down is restarted.

In the example of fig. 4, when a packet to be transmitted arrives at the MAC of STA3, STA3 may transmit a frame immediately after the acknowledgement medium is idle for as long as DIFS. The remaining STAs monitor and wait for the medium to be occupied/busy. Meanwhile, data to be transmitted may also occur in each of STA1, STA2, and STA5, and when the medium is monitored to be idle, each STA waits for DIFS, and then may perform countdown of backoff slots according to a random backoff count value selected by each STA. Suppose that STA2 selects the minimum backoff count value and STA1 selects the maximum backoff count value. That is, a case is exemplified in which the remaining back-off time of STA5 is shorter than the remaining back-off time of STA1 when STA2 completes the back-off count and starts frame transmission. STA1 and STA5 temporarily stop counting down and wait while STA2 occupies the medium. When the occupancy of STA2 ends and the medium becomes idle again, STA1 and STA5 wait for DIFS and restart the stopped backoff count. That is, frame transmission may begin after the remaining back-off time slot is counted down for the remaining back-off time. Since the remaining back-off time of STA5 is shorter than that of STA1, STA5 starts frame transmission. Data to be transmitted may also occur in STA4 while STA2 occupies the medium. From the perspective of STA4, when the medium becomes idle, STA4 may wait for DIFS, then may perform countdown according to the random backoff count value selected by STA4, and begin transmitting frames. The example of fig. 4 shows a case where the remaining back-off time of STA5 accidentally collides with the random back-off count value of STA 4. In this case, a collision may occur between STA4 and STA 5. When collision occurs, neither STA4 nor STA5 receives ACK, and thus data transmission fails. In this case, STA4 and STA5 may double the CW value, select a random backoff count value, and perform countdown. While the medium is occupied due to transmissions of STA4 and STA5, STA1 waits, and when the medium becomes idle, STA1 waits for DIFS and then starts frame transmission after the remaining backoff time has elapsed.

As in the example of fig. 4, the data frame is a frame for transmitting data forwarded to a higher layer, and may be transmitted after a backoff performed after a DIFS has elapsed since the medium became idle. In addition, the management frame is a frame for exchanging management information that is not forwarded to a higher layer, and is transmitted after performing backoff after IFS such as DIFS or point coordination function IFS (PIFS). As subtype frames of the management frame, there are beacons, association requests/responses, reassociation requests/responses, probe requests/responses, authentication requests/responses, and the like. The control frame is a frame for controlling access to a medium. As subtype frames of the control frame, there are Request To Send (RTS), clear To Send (CTS), acknowledgement (ACK), power save Poll (PS-Poll), block ACK (BlockAck), block ACK request (BlockACKReq), null data packet announcement (NDP announcement), trigger, and the like. If the control frame is not a response frame of a previous frame, it is transmitted after performing backoff after passing through DIFS, and if it is a response frame of a previous frame, it is transmitted without performing backoff after passing through Short IFS (SIFS). The type and subtype of a frame may be identified by a type field and a subtype field in a Frame Control (FC) field.

A quality of service (QoS) STA may perform backoff performed after an Arbitration IFS (AIFS) (i.e., AIFS (where i is a value determined by an Access Class (AC)) for an Access Class (AC) to which a frame belongs, and then may transmit the frame. Here, the frame in which the AIFS may be used may be a data frame, a management frame, or a control frame instead of a response frame.

As described above, the CSMA/CA mechanism includes virtual carrier sensing in addition to physical carrier sensing where STAs directly sense the medium. Virtual carrier sensing aims to compensate for problems such as hidden node problems that may occur in medium access. For virtual carrier sensing, the MAC of the STA may use a Network Allocation Vector (NAV). The NAV is a value indicating a remaining time until a medium is available to other STAs that are currently using or have access to the medium. Accordingly, the value set to the NAV corresponds to a period in which the STA transmitting the frame plans to use the medium, and during the corresponding period, the STA receiving the NAV value is prohibited from accessing the medium. For example, the NAV may be configured based on the value of the "duration" field of the MAC header of the frame.

In the example of fig. 5, it is assumed that STA1 intends to transmit data to STA2, and STA3 is in a position capable of eavesdropping on some or all of the frames transmitted and received between STA1 and STA 2.

To reduce the possibility of transmission collisions 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, when transmission of STA1 is being performed, it may be determined that the medium is in an idle state as a result of carrier sensing of STA 3. That is, STA1 may correspond to a hidden node with respect to STA 3. Alternatively, in the example of fig. 5, it may be determined that the carrier sense result medium of STA3 is in an idle state while transmission of STA2 is being performed. That is, STA2 may correspond to a hidden node with respect to STA 3. By exchanging RTS/CTS frames before performing data transmission and reception between STA1 and STA2, STAs outside the transmission range of one of STA1 or STA2 or STAs outside the carrier sense range from the transmission of STA1 or STA3 may not attempt to occupy channels during data transmission and reception between STA1 and STA 2.

Specifically, STA1 may determine whether a channel is being used through carrier sensing. For physical carrier sensing, STA1 may determine that the channel occupies an idle state based on the energy level or signal correlation detected in the channel. In addition, for virtual carrier sensing, STA1 may use a Network Allocation Vector (NAV) timer to determine the channel occupancy state.

When the channel is in an idle state during DIFS, STA1 may transmit an RTS frame to STA2 after performing backoff. When STA2 receives the RTS frame, STA2 may transmit a CTS frame to STA1 as a response to the RTS frame after SIFS.

If STA3 cannot overhear the CTS frame from STA2 but can overhear the RTS frame from STA1, STA3 may set a NAV timer for a frame transmission period (e.g., sifs+cts frame+sifs+data frame+sifs+ack frame) continuously transmitted thereafter using duration information included in the RTS frame. Alternatively, if STA3 can overhear the CTS frame from STA2, although STA3 cannot overhear the RTS frame from STA1, STA3 may set the NAV timer for a frame transmission period (e.g., sifs+data frame+sifs+ack frame) continuously transmitted thereafter using the duration information included in the CTS frame. That is, if STA3 can overhear one or more of the RTS frames or CTS frames from one or more of STA1 or STA2, STA3 may set the NAV accordingly. When the STA3 receives a new frame before the NAV timer expires, the STA3 may update the NAV timer using duration information included in the new frame. STA3 does not attempt channel access until the NAV timer expires.

When STA1 receives the CTS frame from STA2, STA1 may transmit a data frame to STA2 after SIFS from a point in time when reception of the CTS frame is completed. When the STA2 successfully receives the data frame, the STA2 may transmit an ACK frame as a response to the data frame to the STA1 after SIFS. When the NAV timer expires, STA3 may determine whether a channel is being used through carrier sensing. When STA3 determines that the channel is not used by other terminals during DIFS after expiration of the NAV timer, STA3 may attempt channel access after a Contention Window (CW) according to random backoff has elapsed.

By means of instructions or primitives (meaning an aggregation of instructions or parameters) from the MAC layer, the PHY layer may prepare MAC PDUs (MPDUs) to be transmitted. For example, when a command requesting to start transmission of the PHY layer is received from the MAC layer, the PHY layer switches to a transmission mode, and information (e.g., data) provided from the MAC layer is configured in the form of a frame and transmitted. In addition, when the PHY layer detects a valid preamble of a received frame, the PHY layer monitors a header of the preamble and transmits a command informing the MAC layer of the start of reception of the PHY layer.

In this way, information transmission/reception in the wireless LAN system is performed in the form of frames, and for this purpose, a PHY layer protocol data unit (PPDU) format is defined.

The basic PPDU may include a Short Training Field (STF), a Long Training Field (LTF), a Signal (SIG) field, and a Data (Data) field. The most basic PPDU format (e.g., non-HT (high throughput) shown in fig. 7) may be composed of only a legacy-STF (L-STF), a legacy-LTF (L-LTF), a legacy-SIG (L-SIG) field, and a data field. In addition, depending on the type of PPDU format (e.g., HT mixed format PPDU, HT greenfield 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.)) and the like may be included between the L-SIG field and the data field.

The STF is a signal for signal detection, automatic Gain Control (AGC), diversity selection, accurate time synchronization, etc., and the LTF is a signal for channel estimation and frequency error estimation. The STF and LTF may be referred to as 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 be composed of 24 bits, and the L-SIG field may include a 4-bit rate field, 1-bit reserved bits, 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 the data. For example, the 12-bit length field may include information about the length or duration of the PPDU. For example, the value of the 12-bit length field may be determined based on the type of PPDU. For example, 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 the HE PPDU, the value of the length field may be determined as a multiple of 3+1 or a multiple of 3+2.

The data field may include a SERVICE (SERVICE) field, a physical layer SERVICE data unit (PSDU), and PPDU tail bits, and may also include padding bits, if necessary. Some bits of the service field may be used for synchronization of the descrambler at the receiving end. The PSDU corresponds to a MAC PDU defined in the MAC layer, and may include data generated/used in an upper layer. The PPDU tail bits may be used to return the encoder to the 0 state. The pad bits may be used to adjust the length of the data field by predetermined units.

The MAC PDU is defined according to various MAC frame formats, and a basic MAC frame is composed of a MAC header, a frame body, and a Frame Check Sequence (FCS). The MAC frame may be composed of MAC PDUs and transmitted/received through PSDUs of a data portion of a 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 a corresponding frame or the like. For details of the sequence control, qoS control and HT control subfields of the MAC header, 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 including a PPDU preamble of a general PPDU format (i.e., L-STF, L-LTF, L-SIG field, and additional non-legacy SIG, non-legacy STF, non-legacy LTF (if present)) and not including the remainder (i.e., data field).

In standards such as IEEE 802.11a/g/n/ac/ax, various types of PPDUs have been used. The basic PPDU format (IEEE 802.11 a/g) includes L-LTF, L-STF, L-SIG, and data fields. The basic PPDU format may also be referred to as a non-HT PPDU format (as shown in fig. 7 (a)).

In contrast to the basic PPDU format, the HT PPDU format (IEEE 802.11 n) additionally includes HT-SIG, HT-STF, and HT-LFT fields. The HT PPDU format shown in (b) of fig. 7 may be referred to as an HT mix format. In addition, an HT greenfield format PPDU may be defined and corresponds to a format (not shown) consisting of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTFs, and data fields, excluding L-STF, L-LTF, and L-SIG.

Examples of the VHT PPDU format (IEEE 802.11 ac) additionally include a VHT SIG-A, VHT-STF, a VHT-LTF, and a VHT-SIG-B field (as shown in (c) of fig. 7) in comparison with the basic PPDU format.

Examples of the HE PPDU format (IEEE 802.11 ax) additionally include repeated L-SIG (RL-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF, packet Extension (PE) fields, as shown in (d) of fig. 7, in comparison with the basic PPDU format. Some fields may be excluded or their lengths may vary according to a detailed example of the HE PPDU format. For example, the HE-SIG-B field is included in an HE PPDU format for a multi-user (MU), and the HE-SIG-B is not included in an HE PPDU format for a Single User (SU). Further, the HE Trigger (TB) -based PPDU format does not include HE-SIG-B, and the length of the HE-STF field may vary to 8 μs. Ext> theext> extendedext> rangeext> (ext> HEERext>)ext> SUext> PPDUext> formatext> doesext> notext> includeext> theext> HEext> -ext> SIGext> -ext> Bext> fieldext>,ext> andext> theext> lengthext> ofext> theext> HEext> -ext> SIGext> -ext> Aext> fieldext> mayext> varyext> toext> 16ext> μsext>.ext> For example, the RL-SIG may be configured the same as the L-SIG. Based on the existence of the RL-SIG, the receiving STA may know that the received PPDU is a HE PPDU or an EHT PPDU, which will be described later.

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

The EHT MU PPDU in (e) of fig. 7 corresponds to a PPDU carrying one or more data (or PSDUs) for one or more users. That is, the EHT MU PPDU may be used for both SU transmissions and MU transmissions. For example, the EHT MU PPDU may correspond to a PPDU for one or more receiving STAs.

The EHT TB PPDU in (f) of FIG. 7 omits the EHT-SIG as compared to the EHT MU PPDU. A STA that receives a trigger (e.g., a trigger frame or Triggered Response Schedule (TRS)) for UL MU transmission may perform UL transmission based on the EHT TB PPDU format.

The L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (universal signal), EHT-SIG field may be encoded and modulated so that even legacy STAs may attempt demodulation and decoding and may be mapped based on the determined subcarrier frequency spacing (e.g., 312.5 kHz). These may be referred to as pre-EHT modulation fields. Next, EHT-STF, EHT-LTF, data, PE fields may be encoded and modulated to be demodulated and decoded by STAs that successfully decode non-legacy SIG (e.g., U-SIG and/or EHT-SIG) and obtain information included in the field, and may be mapped based on the determined subcarrier frequency spacing (e.g., 78.125 kHz). These may be referred to as EHT modulation fields.

Ext> similarlyext>,ext> inext> theext> HEext> PPDUext> formatext>,ext> Lext> -ext> STFext>,ext> Lext> -ext> LTFext>,ext> Lext> -ext> SIGext>,ext> RLext> -ext> SIGext>,ext> HEext> -ext> SIGext> -ext> Aext>,ext> andext> HEext> -ext> SIGext> -ext> Bext> fieldsext> mayext> beext> referredext> toext> asext> preext> -ext> HEext> modulationext> fieldsext>,ext> andext> HEext> -ext> STFext>,ext> HEext> -ext> LTFext>,ext> dataext>,ext> andext> PEext> fieldsext> mayext> beext> referredext> toext> asext> HEext> modulationext> fieldsext>.ext> Ext> inext> additionext>,ext> inext> theext> VHText> PPDUext> formatext>,ext> Lext> -ext> STFext>,ext> Lext> -ext> LTFext>,ext> Lext> -ext> SIGext>,ext> andext> VHText> -ext> SIGext> -ext> Aext> fieldsext> mayext> beext> referredext> toext> asext> VHText> -ext> freeext> modulationext> fieldsext>,ext> andext> VHText> STFext>,ext> VHText> -ext> LTFext>,ext> VHText> -ext> SIGext> -ext> Bext>,ext> andext> dataext> fieldsext> mayext> beext> referredext> toext> asext> VHText> modulationext> fieldsext>.ext>

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

The U-SIG may be constructed in units of 20 MHz. For example, if an 80MHz PPDU is constructed, the U-SIG may be duplicated. That is, the same 4U-SIGs may be included in an 80MHz PPDU. PPDUs exceeding the 80MHz bandwidth may include different U-SIG.

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

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

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

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

For example, version-related bits of the U-SIG may include 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 also include information about a bandwidth, information about an MCS technique applied to an unconventional SIG (e.g., EHT-SIG or UHR-SIG, etc.), information indicating whether a DCM (dual carrier modulation) technique (e.g., a technique for achieving an effect similar to frequency diversity by reusing the same signal on two subcarriers) is applied to the unconventional SIG, information about the number of symbols used for the unconventional SIG, information about whether the unconventional SIG is generated across the entire frequency band.

Some of the information required for PPDU transmission and reception 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 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 CP (cyclic prefix) length, information about the GI (guard interval) applicable to the non-legacy LTF, information about preamble puncturing applicable to the PPDU, information about Resource Unit (RU) allocation, etc. may be included in only the U-SIG, only 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 represent transmission of a PPDU in which no signal is present in one or more frequency units among bandwidths of the PPDU. For example, the size of the frequency bin (or the resolution of the preamble puncturing) may be defined as 20MHz, 40MHz, etc. For example, preamble puncturing may be applied to PPDU bandwidths of a predetermined size or more.

In the example of fig. 7, non-legacy SIG 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 one symbol may have a length of 4 μs. Information regarding the number of symbols 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 include common fields and user-specific fields. The common field and the user-specific field may be encoded separately.

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

The number of user-specific fields may be determined based on the number of users. One user block field may include up to two user fields. Each user field may be associated with a MU-MIMO allocation or may be associated with a non-MU-MIMO allocation.

The common field may include CRC bits and tail bits, and the length of the CRC bits may be determined to be 4 bits, and the length of the tail bits may be determined to be 6 bits and set to 000000. The common field may include RU allocation information. The RU allocation information may include information regarding bit positions of RUs to which a plurality of users (i.e., a plurality of receiving STAs) are assigned.

An RU may include a plurality of subcarriers (or tones). RU may be used when transmitting signals to a plurality of STAs based on OFDMA techniques. In addition, RU may be defined even when a signal is transmitted to one STA. Resources may be allocated for the non-legacy STF, the non-legacy LTF, and the data field in RU units.

An RU of an applicable size may be defined according to PPDU bandwidth. RU may be defined identically or differently for an applied PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.). For example, in the case of an 80MHz PPDU, RU layouts of the HE PPDU and the EHT PPDU may be different. The applicable RU size, number and RU position of each PPDU bandwidth, DC (direct current) subcarrier position and number, null subcarrier position and number, guard subcarrier position and number, etc. may be referred to as a tone plan. For example, a tone plan for a high bandwidth may be defined in terms of multiple iterations of a low bandwidth tone plan.

RU of various sizes may be defined as 26 tone RU, 52 tone RU, 106 tone RU, 242 tone RU, 484 tone RU, 996 tone RU, 2 x 996 tone RU, 3 x 996 tone RU, and the like. MRU (multiple RU) is different from multiple individual RUs and corresponds to a set of subcarriers made up of multiple RUs. For example, one MRU may be defined as 52+26 tones, 106+26 tones, 484+242 tones, 996+484 tones, 996+484+242 tones, 2×996+484 tones, 3×996 tones, or 3×996+484 tones. In addition, a plurality of RUs constituting one MRU may or may not be contiguous in the frequency domain.

The specific size of RU may be reduced or extended. Thus, the particular size (i.e., number of corresponding tones) of each RU in the present disclosure is not limiting but illustrative. In addition, in the present disclosure, the number of RUs may vary according to RU size within a predetermined bandwidth (e.g., 20MHz, 40MHz, 80MHz, 160MHz, 320MHz.

The names of each field in the PPDU format of fig. 7 are exemplary, and the scope of the present disclosure is not limited by these names. In addition, examples of the present disclosure may be applied to the PPDU format illustrated in fig. 7 and a new PPDU format excluding some fields and/or adding some fields based on the PPDU format of fig. 7.

Main channel based channel access

Channel access in the WLAN system is performed based on the primary channel. For example, when the primary channel is idle and a back-off counter (BC) expires, the STA may transmit a frame on a channel including the primary channel and the idle secondary channel. For this, all STAs preferentially perform CCA on the primary channel. Further, the AP announces information of a primary channel for the BSS, and the primary channel is always included in a channel in which a management frame (e.g., a beacon frame, a probe response frame, etc.) is transmitted.

The example in fig. 8 shows an example of primary channel-based channel access in 80MHz bandwidth. Referring to fig. 8, channels in the 80mhz bandwidth may be expressed as follows.

P20:Main 20MHz channel

S20. secondary 20MHz channel (when the bandwidth is 40MHz, it corresponds to the remaining 20MHz secondary channel excluding P20)

S40. auxiliary 40MHz channel (when the bandwidth is 80MHz, it corresponds to the remaining 40MHz auxiliary channel excluding P20 and S20)

Similarly, a channel for bandwidths exceeding 80MHz can be expressed as follows.

S80. auxiliary 80MHz channel (when the bandwidth is 160MHz, it corresponds to the remaining 80MHz auxiliary channel excluding P20, S20 and S40)

S160: auxiliary 160MHz channel (which corresponds to the remaining 160MHz auxiliary channel excluding P20, S40 and S80 when the bandwidth is 320 MHz)

S320:320 auxiliary 320MHz channel (when the bandwidth is 640MHz, it corresponds to the remaining 320MHz auxiliary channel excluding P20, S40, S80 and S160)

In existing WLAN systems, the backoff counter is configured for the primary channel. For example, the STA may perform CCA (e.g., physical CS and virtual CS) to determine whether the status of the medium on the primary channel is clear or busy. For example, in the example of fig. 8, the STA does not decrease the Backoff Counter (BC) when the status of the medium on P20 is determined to be busy according to CCA (e.g., physical CS and/or virtual CS (NAV)) for P20, and the STA may decrease BC when the status of the medium on P20 is determined to be idle. When the BC expires through the backoff procedure (i.e., when the value of BC becomes 0), the STA may confirm (e.g., CCA) the medium status at S20 and S40. The STA may transmit a PPDU (or frame) on a main channel and an idle channel between S20 and S40. (in the example of FIG. 8, since S40 is busy and S20 is idle when BC for P20 expires, a 40MHz PPDU may be sent over P20 and S20.)

Channel access based on secondary channel

The above-described channel access operation based on the primary channel may have the effect of preventing interference and protecting PPDU transmission because frame exchange between all STAs and the AP is performed according to the state of the primary channel. Furthermore, when only the primary channel is busy and the secondary channel is idle, channel access may be performed only on the secondary channel excluding the primary channel, thus being inefficient from the viewpoint of medium use. For example, in the example of fig. 8, when P20 is busy and both S20 and S40 are idle, the portion of bandwidth corresponding to 60MHz is wasted.

In order to enhance the WLAN system, a new method of accessing the secondary channel based on the secondary channel is required even when the primary channel is not idle.

Hereinafter, various examples of the present disclosure for secondary channel access will be described.

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

In the present disclosure, for convenience of description, the term of the secondary channel is used to collectively refer to at least one channel other than the primary channel, but the present disclosure is not limited thereto, and it may also be referred to as a non-primary channel. Further, the secondary channel access may be referred to as non-primary channel access (NPCA).

In S910, the first STA may receive information for a plurality of EDCA parameter sets related to a plurality of non-primary backoff channels, respectively, from the second STA.

In S920, the first STA may perform a backoff procedure on a plurality of non-primary backoff channels based on the plurality of EDCA parameter sets.

The non-primary channels may include non-primary backoff channels and non-primary non-backoff channels. The non-primary backoff channel may correspond to a channel performing backoff for non-primary channel access instead of a primary channel.

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

For example, the first backoff procedure may include 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. The second backoff procedure may include decrementing a second backoff counter based on the medium on the second non-primary backoff channel being determined to be idle based on the second EDCA parameter set.

In S930, the first STA may transmit at least one PPDU on at least one channel including at least one of a plurality of non-primary backoff channels and at least zero non-primary non-backoff channels.

During a predetermined period of time before the back-off counter for the non-primary back-off channel expires (i.e., the value of the back-off counter becomes 0), it may be determined whether it is busy or idle by a non-primary channel CCA for the non-primary non-back-off channel (e.g., a CCA based on Guard Interval Detection (GID) or Energy Detection (ED)). Thus, an idle non-primary non-backoff channel may be included in at least one channel for PPDU transmission along with the non-primary backoff channel for which the backoff counter expires. When there are no idle non-primary non-backoff channels (i.e., when all non-primary non-backoff channels are busy), the non-primary backoff channel for which the backoff counter expires may be included in at least one channel for PPDU transmission.

In other words, in the following description, when zero non-primary non-backoff channels are included in at least one channel in which the PPDU is transmitted (i.e., non-primary non-backoff channels are not included in at least one channel), it may correspond to a case in which there is no idle non-primary non-backoff channel as a result of CCA for the non-primary non-backoff channels. In the following description, when at least one non-primary non-backoff channel is included in at least one channel in which a PPDU is transmitted, it may correspond to a case in which at least one idle non-primary non-backoff channel exists as a result of CCA for the non-primary non-backoff channel.

Multiple non-primary backoff channels may be included in the same channel subset or may be included in different channel subsets. The at least one non-primary backoff channel may be included in one channel subset and the non-primary backoff channel may not be included in a specific channel subset. At least zero non-primary non-backoff channels may be included in one channel subset. One channel subset may correspond to a maximum bandwidth for PPDUs transmitted based on a backoff procedure for at least one non-primary backoff channel included in the one channel subset. The non-primary backoff channel and the non-primary non-backoff channel included in the same channel subset may be referred to as correlated (or adjacent) non-primary channels.

According to an example of independently configuring EDCA parameters for a plurality of non-primary backoff channels, the first STA may operate as follows.

For example, when the first back-off counter expires and the second back-off counter does not expire, one PPDU may be transmitted on the first non-primary back-off channel and at least zero first non-primary non-back-off channels associated with the first non-primary back-off channel.

Alternatively, when the first back-off counter expires and the second back-off counter does not expire, transmission of the PPDU may be deferred on the first non-primary back-off channel and at least zero first non-primary non-back-off channels associated with the first non-primary back-off channel.

In this case, when the second backoff counter expires after the first backoff counter expires, the at least one PPDU may be transmitted on the first non-primary backoff channel, the at least zero first non-primary non-backoff channel, the second non-primary backoff channel, and the at least zero second non-primary non-backoff channel (i.e., the non-primary non-backoff channel associated with the second non-primary backoff channel).

The PPDU may be transmitted on at least one channel as follows.

For example, a first PPDU may be transmitted on a first non-primary back-off channel and at least zero first non-primary non-back-off channels, and a second PPDU may be transmitted on a second non-primary back-off channel and at least zero second non-primary non-back-off channels simultaneously.

Alternatively, one PPDU may be transmitted on a first non-primary backoff channel, at least zero first non-primary non-backoff channel, a second non-primary backoff channel, and at least zero second non-primary non-backoff channel. In this case, one PPDU may be transmitted on a continuous channel or a discontinuous channel.

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

The method described in the example of fig. 9 may be performed by the first apparatus 100 in fig. 1. For example, the at least one processor 102 of the first apparatus 100 in fig. 1 may be configured to receive, by the at least one transceiver, information from the second STA regarding a plurality of EDCA parameter sets respectively associated with the plurality of non-primary backoff channels, perform a backoff procedure on the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets, and transmit, by the at least one transceiver, the at least one PPDU on at least one channel comprising at least one of the plurality of non-primary backoff channels and at least zero non-primary non-backoff channels. Further, the at least one memory 104 of the first apparatus 100 may store instructions for performing the methods described in the example of fig. 9 or the examples described below when executed by the at least one processor 102.

In S1010, the second STA may transmit information for a plurality of EDCA parameter sets respectively related to the plurality of non-primary backoff channels to the first STA.

In S1020, the second STA may receive at least one PPDU from the first STA over at least one channel including at least one of the plurality of non-primary backoff channels and at least zero non-primary non-backoff channels, the at least one PPDU transmitted by the first STA through a backoff procedure performed over the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets.

In the example of fig. 10, since the specific descriptions of the non-primary backoff channel, the non-primary non-backoff channel, and the EDCA parameter set are the same as those described with reference to fig. 9, overlapping descriptions are omitted.

The method described in the example of fig. 10 may be performed by the second apparatus 200 in fig. 1. For example, the at least one processor 202 of the second apparatus 200 in fig. 1 may be configured to transmit, by the at least one transceiver, information to the first STA regarding a plurality of EDCA parameter sets respectively associated with the plurality of non-primary backoff channels, and receive, by the at least one transceiver, at least one PPDU from the first STA over at least one channel including at least one of the plurality of non-primary backoff channels and at least zero non-primary non-backoff channels, the at least one PPDU transmitted by the first STA through a backoff procedure performed on the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets. Further, the at least one memory 204 of the second apparatus 200 may store instructions for performing the methods described in the example of fig. 10 or the examples described below when executed by the at least one processor 202.

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

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

Embodiment 1

This embodiment relates to the capabilities of STAs for secondary channel access.

Unlike existing primary channel-based channel access supported by STAs on a basic basis, secondary Channel Access (SCA) may be performed by STAs (e.g., AP STAs and/or non-AP STAs) that have the capability for SCA. For example, the AP STA and the non-AP STA may notify each other whether to support SCA capabilities and/or whether to enable SCA capabilities.

The capability for SCA may be defined in terms of whether it is possible to perform a first type of CCA based on whether it is possible to decode/identify a WLAN frame on a secondary channel, i.e. whether a preamble defined by the WLAN system is detected in a frame of a received PPDU (PD). For the first type CCA for the secondary channel, NAV setting/resetting for the secondary channel may be applied based on the duration information of the preamble detected over the first type CCA, similar to NAV setting/resetting (for the primary channel) by the PD-based CCA performed in the existing primary channel (i.e., NAV updating based on the duration information of the detected preamble).

In addition, the capability for SCA may be defined in terms of whether it is possible to perform a second type CCA based on Guard Interval Detection (GID) or Energy Detection (ED) on the secondary channel. The GID may include determining whether guard interval symbols defined by the WLAN system are detected, and the ED may include determining whether any or higher strength signals are detected, regardless of whether it is a signal/packet defined by the WLAN system. In addition, different or independent detection thresholds (e.g., thresholds for received signal strength) may be defined for the first type of CCA and the second type of CCA.

Various levels of SCA capability may be defined based on these various types of CCAs.

The SCA capability level 0 may correspond to a capability that does not perform backoff on the secondary channel. In other words, similar to existing 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.

The SCA capability level 1 may correspond to a capability that can perform backoff on one secondary channel at the same time. When there is at least one secondary channel in the operating channel, a first type CCA (e.g., PD-based CCA) may be performed on one secondary channel at one point in time, and the first type CCA/backoff on multiple secondary channels may not be supported at one point in time.

The SCA capability level 2 may correspond to a capability that can perform backoff on multiple secondary channels simultaneously. When there is at least one secondary channel within the operating channel, a first type of CCA (e.g., PD-based CCA) may be performed on one or more of them.

These SCA capabilities may be included in a capability information element (e.g., UHR capability IE) or the like for a particular version/generation of the WLAN system. For example, the AP may include and transmit a capability IE including information indicating whether SCA capability is supported for a beacon frame, a probe response frame, an association request frame, a reassociation request frame, and the like. For example, the STA may include and transmit a capability IE including information indicating whether SCA capability is supported for a probe request frame, an association request frame, a reassociation request frame, and the like.

Embodiment 2

This embodiment relates to the operation of secondary channel access.

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

For example, when the AP performs frame exchange with a first STA associated with the BSS within the obtained TXOP, an intra-BSS NAV for a primary channel may be set/reset for a second STA within the corresponding BSS. In addition, it may be assumed that a second STA in which an intra-BSS NAV for a primary channel is running accesses a secondary channel (e.g., on a secondary channel that is confirmed to be idle) to transmit a frame to the AP. In this case, when the AP is performing transmission (e.g., transmission of downlink data on a primary channel, transmission of ACK for uplink data, etc.) within the TXOP, the AP may not receive a frame transmitted by the second STA to the AP on a secondary channel.

In view of this, if the basic NAV is set/reset on the primary channel by a PPDU (i.e., an inter-BSS PPDU) associated with a BSS (e.g., OBSS) other than its BSS, or by a PPDU that is not classified/identified as its BSS or another BSS, it may be expected that the STA successfully performs frame exchange on the SCA and performs the SCA when the basic NAV for the primary channel is running. In other words, the STA may perform SCA when the basic NAV for the primary channel is configured (or run).

Embodiment 2-1

This embodiment relates to frame transmission on a secondary channel.

For the existing primary channel-based channel access described by referring to fig. 8, when backoff is performed on P20 and the backoff counter expires (i.e., BC value becomes 0), a frame may be transmitted on P20 and at least one idle secondary channel according to whether the at least one secondary channel is idle/busy.

For the secondary channel access as shown in fig. 11, since the case where P20 is busy (e.g., the basic NAV for the primary channel is running) is considered, a backoff procedure and a channel access operation on a secondary channel different from the existing backoff procedure on the primary channel can be defined.

First, when P20 is busy, the STA may perform a backoff procedure on at least one secondary channel (referred to as "first at least one secondary channel") on which backoff may be performed.

In this regard, if it is assumed that the backoff process based on the backoff counter selected at random is not performed on the secondary channel, when a plurality of neighboring STAs having similar operation channels perform frame transmission (without performing the backoff process) on the idle channel immediately according to the CCA result for a short period of time (e.g., 1 slot) on the channel including (or overlapping with) the corresponding secondary channel, the plurality of STAs may transmit frames at the same time, and the channel may be wasted due to the possibility of such collision. Accordingly, in order to enhance the channel utilization, a backoff procedure may be performed on the secondary channel.

In addition, the STA may not perform secondary channel access (or backoff on the secondary channel) when the remaining length of the NAV timer for the primary channel is less than a predetermined threshold. In other words, secondary channel access (or backoff on the secondary channel) may be performed when 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 a TXOP length on the secondary channel. For example, when the NAV timer currently remaining for the primary channel does not have enough time to obtain a TXOP on the secondary channel, the STA cannot perform backoff on the secondary channel.

Next, when the backoff counter on the first at least one secondary channel expires (i.e., the BC value becomes 0), the STA may perform a second type CCA on at least one additional secondary channel other than the first at least one secondary channel performing the backoff procedure. For example, the STA may determine whether the result of the second type CCA for another secondary channel (i.e., the additional secondary channel) is idle or busy during a predetermined length of time (e.g., PIFS) before a point in time at which a backoff counter on the first secondary channel performing backoff becomes 0.

Accordingly, the STA may perform backoff to perform PPDU/frame transmission on the first at least one secondary channel and on the second at least one secondary channel corresponding to the additional secondary channel determined to be idle according to the second type CCA upon expiration of the backoff counter. If all of the secondary channels except the first at least one secondary channel performing the backoff (i.e., the secondary channel performing the second type CCA) are busy, the second at least one secondary channel may not include the secondary channel except the secondary channel for which the backoff counter expires.

For example, in the example of fig. 11, S20 is a secondary channel performing a backoff procedure based on the first type CCA, and at S40, backoff is not performed and the second type CCA may be performed. When the backoff counter on S20 expires and the two 20MHz channels on S40 are idle during a predetermined period of time before them as a result of the second type CCA, PPDUs corresponding to 60MHz excluding the remaining S20 and S40 of P20 from the 80MHz bandwidth (i.e., the second at least one secondary channel includes S20 and S40) may be transmitted. In this case, the PPDU transmitted on the second at least one secondary channel may be an 80MHz bandwidth PPDU including information indicating that P20 is punctured, and the MAC frame transmitted by the STA performing the secondary channel access may be included in the punctured PPDU.

If the backoff counter on S20 expires and S40 is busy during a predetermined period of time before it as a result of the second type CCA, a PPDU corresponding to 20MHz of S20 (i.e., the second at least one secondary channel includes S20) may be transmitted. In this case, the PPDU transmitted on the second at least one secondary channel may be an 80MHz bandwidth PPDU including information indicating that P20 and P40 are punctured, and a MAC frame transmitted by an STA performing secondary channel access may be included in the punctured PPDU.

In addition, a PPDU/frame transmitted by the STA on the second at least one secondary channel may be transmitted to the AP or another STA.

In the example of fig. 11, the STA may set/reset the basic NAV based on a frame received when performing the backoff procedure on the primary channel. The STA may perform a backoff procedure at S20 when the basic NAV for the primary channel is running. The backoff at S20 may be performed by the PD-based CCA, and a time delay may occur due to a switching operation 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 at S20 is not limited to the PD-based CCA (i.e., first type CCA), and a GID-based or ED-based CCA (i.e., second type CCA) may also be performed.

Embodiment 2-2

This embodiment relates to TXOPs on secondary channels.

Since the CCA must be performed for the P20 when the basic NAV for the primary channel expires, the point in time of TXOP termination on the secondary channel may be before the point in time of the basic NAV for the primary channel expires. Thus, the TXOP for the secondary channel may be obtained/configured to terminate before the point in time when the primary NAV for the primary channel expires.

If the STA obtains/configures a TXOP for the secondary channel to terminate after a point in time when a basic NAV for the primary channel expires, another STA (e.g., a legacy STA or the like) that does not support the secondary channel access may transmit a frame on a channel including the primary channel (i.e., the primary channel and the secondary channel) after the basic NAV for the primary channel expires, and the STA performing the secondary channel access may not receive the frame transmitted by the other STA on the channel including the primary channel. Further, when a Target Beacon Transmission Time (TBTT) is configured at a point of time when the basic NAV is running, the AP must be ready to transmit a beacon on a channel including the primary channel immediately after the basic NAV expires, but it may not be able to transmit a beacon in time due to the TXOP on the secondary channel, and other STAs may not receive a beacon to be transmitted by the AP at the scheduled point of time, and may have to wait for a longer period of time. Accordingly, by configuring the TXOP for the secondary channel to terminate before the point of time when the basic NAV expires, frame exchange can be normally performed on a channel including the primary channel.

Further, when there is insufficient time to configure/acquire a TXOP on the secondary channel (e.g., when the point in time when the basic NAV for the primary channel expires is less than a predetermined threshold (related to the TXOP length), the STA cannot transmit a frame on the secondary channel or cannot perform backoff on the secondary channel. For example, when the length of the period between the point in time when the backoff counter for the secondary channel expires and the point in time when the basic NAV for the primary channel is terminated is insufficient for frame exchange (or insufficient to configure/acquire the TXOP), the STA cannot perform frame transmission on the secondary channel.

Referring to the example of fig. 11, an STA intending to obtain a TXOP due to the expiration of the backoff counter through the backoff procedure on S20 may configure/obtain the TXOP to ensure that the length is shorter than the remaining time of the basic NAV for the primary channel (i.e., the TXOP is terminated before the point in time at which the basic NAV is terminated).

Embodiment 3

This embodiment relates to a transmitting or receiving operation of an STA performing secondary channel access.

The STA performing the secondary channel access may transmit a frame/PPDU on the secondary channel during a time when the NAV for the primary channel is running. For example, the STA may transmit a frame/PPDU excluding/puncturing some channels (e.g., a primary channel, and if any, a busy secondary channel) on the second at least one idle secondary channel based on the CCA result of the backoff procedure performed on the first at least one secondary channel and the at least one additional secondary channel not performing backoff.

Additionally or alternatively, the TXOP for the secondary channel, which is started by the frame/PPDU transmission on the secondary channel, may be configured to terminate before the point in time at which the NAV on the primary channel terminates. The TXOP length may be configured/indicated by duration information (e.g., a value of a 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 a time required to exchange the frame/PPDU after the corresponding frame/PPDU (e.g., a length of the corresponding frame/PPDU and an inter-frame space (IFS)).

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

In the present disclosure, an STA receiving a frame transmitted through a secondary channel access may perform frame detection on a secondary channel during a time when a NAV is operating on a primary channel. For example, the STA may have a frame to send and perform a backoff on the secondary channel, or may receive a frame on the secondary channel during the backoff, or may attempt to receive whether there is a frame addressed to it on the secondary channel, even if it has no frame to transmit. Further, the STA may perform NAV setting/resetting for the secondary channel based on the duration information of the frame detected on the secondary channel.

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

Embodiment 4

Embodiment 4 relates to a procedure in which an AP announces information related to secondary channel access and information related to secondary access.

When the BSS operation channel of an AP (or AP MLD) overlaps with the BSS (i.e., OBSS) operation channel of a neighboring AP (i.e., neighbor AP), SCA within the BSS of the AP and SCA within the BSS of the neighboring AP may affect each other. As an example, when an AP performs SCA successfully within a BSS and transmits and receives PPDUs/frames by using all secondary channels and the secondary channel in which the AP transmits PPDUs/frames overlaps with a primary channel of another AP, a channel access opportunity of another AP may be reduced.

For example, assume that the STA in fig. 11 is AP 1 in fig. 12. Since S20 of AP 1 in fig. 12 corresponds to P20 of AP 2 (i.e., S20 of AP 1 and P20 of AP 2 overlap), when AP 1 transmits PPDU/frame by using all the secondary channels, AP 2 cannot use P20 and S20. In other words, when the AP 1 performs SCA, there may occur a problem in that the AP 2 may not have an opportunity to perform PCH-based channel access.

In addition, when an AP has a capability for SCA but another AP does not have a capability for SCA, there is a problem in that since an AP having a capability for SCA takes longer to occupy a channel, it is possible to reduce the chance that another AP performs channel access.

Accordingly, the AP may inform the STA of information related to the SCA operation to ensure that the STA can use the SCH by considering neighbor situations (e.g., whether another STA has a capability for SCA, an operation channel of a BSS associated with the STA, channel state information related to the STA, OBSS related information, etc.).

Embodiment 4-1

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

The AP may transmit various types of information related to the SCA operation to the STA through a management frame (e.g., a beacon frame, a probe response frame, etc.). As an example, the management frame may include a UHR operation IE or an IE related to a SCA operation, and the UHR operation IE or the IE related to a SCA operation may include various types of information related to the SCA operation. The STA may perform the SCA-related operation based on various types of information related to the SCA operation received from the AP.

As an example of the present disclosure, the information related to the SCA operation may include information on whether or not the SCA is to be allowed, a maximum value of a bandwidth of a frame/PPDU that can be transmitted on the SCH when the SCA is performed, information on at least one secondary channel (i.e., a channel on which backoff is to be performed) serving as a reference for the SCA, and/or CCA threshold information related to the secondary channel.

In particular, the information on whether or not the SCA is to be allowed may be indicated by a field (e.g., a SCA allowed field) related to whether or not the SCA is to be allowed, but the name of the corresponding field may be changed. As an example, assume that the SCA enable field consists of 1 bit. In this case, when the SCA allowable field value is 1 (or 0), it may mean that the SCA is allowed, and when the SCA allowable field value is 0 (or 1), it may mean that the SCA is not allowed.

Additionally or alternatively, one of the 20MHz bandwidth, the 40MHz bandwidth, the 80MHz bandwidth, the 160MHz bandwidth, the 320MHz bandwidth, the 640MHz bandwidth may be indicated as a maximum value of bandwidths that the frame/PPDU may be transmitted on the SCH when performing SCA. The maximum value of the bandwidth that the STA may transmit the frame/PPDU on the SCH may be not greater than the operating bandwidth of the BSS (or the bandwidth of the BSS operating channel) associated with the STA. The operating bandwidth of a BSS (or the bandwidth of a BSS operating channel) may be collectively referred to as the bandwidth operated by the corresponding BSS. As described above, the AP may transmit information to the STA for the maximum value of the bandwidth in which the frame/PPDU may be transmitted on the SCH through a management frame (e.g., a beacon frame and/or a probe response frame).

As an example, assume that the BSS operation bandwidth is 160MHz and at least one SCH of S80 is idle. In this case, when the maximum bandwidth advertised by the AP (i.e., the maximum value of the bandwidth over which the frame/PPDU can be transmitted on the SCH) is 80MHz, the STA can transmit and receive frames in the form of 80MHz PPDUs on a channel excluding S80.

Additionally or alternatively, the information for at least one secondary channel (i.e., a channel in which backoff is to be performed) used as a reference for SCA may indicate a channel in which backoff is to be performed based on a BSS operation bandwidth or a maximum bandwidth in which frames/PPDUs may be transmitted. As an example, the information for at least one secondary channel used as a reference for SCA may be configured by a bitmap.

As an example, as shown in fig. 11, when the total bandwidth (e.g., the bandwidth of the BSS operation channel) is 80MHz and backoff is performed based on the first auxiliary channel, at least one auxiliary channel used as a reference for SCA may be configured in a 3-bit bitmap. Each bit of the configuration 3-bit bitmap may correspond to each 20MHz auxiliary channel. As an example, the corresponding bitmap may be configured with "100" (i.e., with the bitmap to indicate that backoff is performed on the first 20MHz secondary channel). However, this is merely an implementation, and the bitmap may include bits corresponding to the PCH. In this case, the information indicating at least one secondary channel used as a reference for the SCA may be configured with a 4-bit bitmap.

As described above, the first bit of the bitmap may correspond to the highest frequency 20MHz channel and the last bit of the bitmap may correspond to the lowest frequency 20MHz channel. However, this is an implementation only, and the first bit of the bitmap may correspond to the lowest frequency 20MHz channel, and the last bit of the bitmap may correspond to the highest frequency 20MHz channel. Further, the bandwidth used as a reference for the bitmap is not limited to 20MHz, and may be implemented as 40MHz, 80MHz, 160MHz, or the like.

Additionally or alternatively, CCA threshold information related to the secondary channel may include information for use as a threshold for a reference (e.g., a reference for determining whether the channel status is clear or busy) for determining the status of the channel through the CCA in at least one SCH performing the SCA. Since the threshold used as a reference for determining the status of a channel by CCA, i.e., the threshold compared to the measured value of the channel, is low, the likelihood that the status of the corresponding channel will be determined to be busy may increase, although the measured value of the channel, e.g., the Received Signal Strength Indicator (RSSI), is low. In this case, the CCA may include a first type of CCA and/or a second type of CCA.

As an example, the threshold used as a reference for determining the channel state may be determined/configured as a fixed/predefined value (e.g., -82dbM or-72 dbM, etc.). Additionally or alternatively, the threshold used as a reference to determine the channel state may be determined/configured as a value obtained by adding/subtracting a changed value (e.g., 4dbM, 8dbM, etc.) to/from a fixed/predefined value. In this case, the AP may transmit only the value added/subtracted to/from the threshold value to the STA.

As an example of the present disclosure, fig. 13 illustrates a procedure in which SCA is performed based on SCA related information announced by an AP. As shown in fig. 13, the AP may notify the STA of information for BSS operation bandwidth configured to 160MHz, information representing an allowable SCA, information for a maximum bandwidth of a PPDU that can be transmitted through the SCA configured to 40MHz, and information for a secondary channel (i.e., a channel in which backoff is performed) serving as a reference for the SCA. The AP may transmit/announce the above information to the STA through a beacon frame.

In this case, information for a channel in which backoff is performed may be configured in the form of a bitmap. As an example, as shown in fig. 13, when information for a channel in which backoff is performed is configured as an 8-bit bitmap (e.g., "00100000"), it may indicate that the first 20MHz (i.e., the second SCH) of S40 is a channel in which backoff is performed. Here, it is assumed that the first bit of the bitmap corresponds to the 20MHz channel of the lowest frequency, and the last bit of the bitmap corresponds to the 20MHz channel of the highest frequency (i.e., in ascending order).

When the information related to the SCA is announced from the AP, the STA may perform backoff based on the announced information based on the first SCH of S40. When the backoff count becomes 0 and the second SCH of S40 is idle, the STA may transmit a frame (to another STA (e.g., AP)) on S40. Further, although the channel state of S80 is idle, the maximum bandwidth of the PPDU that can be transmitted through the SCA is 40MHz, and thus the STA may not perform and use CCA for the specific SCH of S80.

By way of the above example, the STA can transmit a frame by using the SCH even when the PCH state is busy, thereby improving channel use efficiency.

Embodiment 5

Embodiment 5 relates to operations related to SCA of STAs.

As an embodiment of the present disclosure, during the time when the NAV is configured on the PCH, the STA may transmit a frame/PPDU on the SCH by performing the SCA. As an example, the STA may identify/determine a channel state of at least one SCH based on a CCA result of at least one SCH performing backoff and at least one SCH not performing backoff. When the channel state of at least one SCH is idle, a STA may transmit a frame/PPDU (to another STA (e.g., AP)) in which the PCH is excluded/punctured on at least one corresponding SCH.

Additionally or alternatively, a TXOP configured in accordance with the SCA performed on the at least one SCH (i.e., backoff performed on the at least one SCH, etc.) may be configured to terminate before the NAV on the PCH is terminated. In other words, the end time point of the TXOP starting with the frame/PPDU transmission on the SCH may be configured/determined before the time point at which the NAV on the PCH is terminated.

Here, the length of the TXOP configured on the SCH may be configured/indicated through a duration/ID field of a frame transmitted at the corresponding TXOP. For example, the value of the duration/ID field may be set to a value corresponding to a time required to exchange the frame/PPDU after the corresponding frame/PPDU including an inter-frame space (IFS).

Additionally or alternatively, the STA may obtain information for at least one SCH in which backoff is performed by a management frame (e.g., beacon frame) transmitted from the AP. In this case, the information for the at least one SCH may include information for whether a frame/PPDU can be transmitted on the at least one SCH. As an example, when the STA performing the SCA is an AP, the corresponding STA may use information transmitted by itself (e.g., information on whether a frame/PPDU can be transmitted on the SCH and/or information on at least one SCH in which backoff is performed, etc.).

Additionally or alternatively, the STA may obtain information for the maximum bandwidth (where the frame/PPDU may be transmitted on the SCH) through a management frame (e.g., beacon frame) from the AP. When the STA performing SCA is an AP, the corresponding STA may use information for the maximum bandwidth (in which a frame/PPDU may be transmitted on the SCH) transmitted by itself.

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

Additionally or alternatively, the EDCA parameter set for each SCH performing backoff may be configured as an EDCA parameter set, a MU EDCA parameter set, or a new EDCA parameter set on the PCH. The corresponding EDCA parameter set may be equally or differently applied to all SCHs.

As an example of the present disclosure, a STA receiving a frame transmitted through the SCA may perform frame detection on the SCH even during the time that the NAV is configured on 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 send, the STA may attempt to receive frames addressed to itself on the SCA. Further, the STA may perform NAV configuration/reconfiguration based on the value of the duration/ID field of the frame detected on the SCH.

Additionally or alternatively, the STA may obtain information for at least one SCH in which backoff is performed through a management frame (e.g., beacon frame) transmitted from the AP. In this case, the information for the at least one SCH may include information for whether a frame/PPDU can be transmitted on the at least one SCH. As an example, when the STA performing the SCA is an AP, the corresponding STA may use information transmitted by itself (e.g., information on whether a frame/PPDU can be transmitted on the SCH and/or information on at least one SCH in which backoff is performed, etc.).

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

Embodiment 5-1

Embodiment 5-1 relates to a method for performing backoff by dividing a channel including a BSS operation channel into a plurality of sets for efficient SCA. In this case, in addition to the information announced by the AP for the SCA described in embodiment 4, embodiment 4-1, and embodiment 5, information described below (e.g., channel subset element 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 references (or units) used to divide the bandwidth of the entire BSS operation channel into at least one subset of channels for SCA (i.e., channel subset unit information).

As an example, assume that the (sub) field size representing channel subset unit information is 2 bits. When the (sub) field value representing the channel subset element information is 0 (i.e., the corresponding (sub) field indicates no subset), this may mean that the BSS operation channel is not divided into at least one subset. When the (sub) field value is 1, this may mean that the bandwidth reference/unit value for dividing the BSS operation channel into at least one subset is 40MHz. When the (sub) field value is 2, this may mean that the bandwidth reference/unit value for dividing the BSS operation channel into at least one subset is 80MHz. When the (sub) field value is 3, this may mean that the bandwidth reference/unit value for dividing the BSS operation channel into at least one subset is 160MHz.

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

In addition, the AP may notify the STA of a size of a bitmap (i.e., SCA channel bitmap size information) representing at least one SCH (i.e., SCH in which backoff is performed) used as a reference when performing SCA.

As an example, assume that the (sub) field size representing the SCA channel bitmap size information is 2 bits. When the (sub) field value representing the SCA channel bitmap size information is 0, this may mean that the SCA channel bitmap size is 4 bits. When the (sub) field value representing the SCA channel bitmap size information is 1, this may mean that the SCA channel bitmap size is 8 bits. When the (sub) field value representing the SCA channel bitmap size information is 2, this may mean that the SCA channel bitmap size is 16 bits. When the (sub) field value representing the SCA channel bitmap size information is 3, this may mean that the SCA channel bitmap size is 32 bits. Here, when P20 is not indicated by the SCA channel bitmap, the SCA channel bitmap size may be reduced by 1.

Here, the (sub) field size representing the SCA channel bitmap size information may be changed according to the BSS operation channel. As an example, when the size of the BSS operation channel is 320MHz, the SCA channel bitmap size may be configured/determined to be at most 16 bits.

As an example, when information indicating at least one SCH used as a reference when performing SCA is configured in a bitmap, information for configuring/indicating/describing a subset of channels may not be required. In other words, it may not be necessary to configure the bitmap corresponding to each subset as a separate field. When information indicating at least one SCH used as a reference when performing SCA is configured in a bitmap, if a bit corresponding to a specific channel in a corresponding bitmap is configured to be 1, this may mean performing backoff on the corresponding channel. Additionally or alternatively, there may be no SCH within which backoff is performed within one channel subset.

As an example of the present disclosure, fig. 14 shows a case where the bandwidth of the BSS operation channel is 160 MHz. In fig. 14, a hatched portion excluding P20 may refer to SCH (i.e., SCH in which backoff may be performed) used as a reference for SCA.

As an example, fig. 14 (a) illustrates a case where the channel subset unit is 40 MHz. When information indicating at least one SCH used as a reference in performing P20 and SCA is configured in a bitmap, the corresponding bitmap may be configured as "01101001". In this case, when P20 is not indicated by the corresponding bitmap, the corresponding bitmap may be configured as "01101001". In other words, at least one SCH used as a reference when performing SCA on all channel subsets may be expressed/configured by one bitmap.

As an example, fig. 14 (b) shows a case where the channel subset unit is 80 MHz. When information indicating at least one SCH used as a reference in performing P20 and SCA is configured in a bitmap, the corresponding bitmap may be configured as "01001000". In this case, when P20 is not indicated by the corresponding bitmap, the corresponding bitmap may be configured as "1001000". In other words, at least one SCH used as a reference when performing SCA on all channel subsets may be expressed/configured by one bitmap.

As another example of the present disclosure, fig. 15 is a diagram for describing a SCA channel bitmap when the bandwidth of a BSS operation channel is 320 MHz. In other words, assume that the bandwidth of the BSS operation channel is 320MHz and the channel subset element is 80MHz. In fig. 15, a hatched portion excluding P20 may refer to a channel (i.e., SCH in which backoff may be performed) used as a reference for SCA.

As an example, when information indicating at least one SCH used as a reference in performing P20 and SCA is configured in a bitmap, the corresponding bitmap may be configured as "0100100001001000". In this case, when P20 is not indicated by the corresponding bitmap, the corresponding bitmap may be configured as "100100001001000". In other words, at least one SCH, which is used as a reference when performing SCA for all channel subsets, may be expressed/configured by one bitmap. In other words, at least one SCH, which is used as a reference when performing SCA for all channel subsets, may be expressed/configured by one bitmap.

Embodiment 6

This embodiment relates to a backoff mechanism based on a plurality of backoff channels for secondary channel access. For example, among the STA capabilities related to secondary channel access described in the above embodiments, a backoff method for a case in which an STA (i.e., an AP STA and/or a non-AP STA) has a level 2 secondary channel access capability (i.e., a capability of simultaneously performing a backoff procedure on at least one secondary channel) is described below.

Since the STA having the level 2 secondary channel access capability can perform backoff on at least one channel at the same time, it is necessary to define a specific method for performing backoff on at least one secondary channel and transmitting a frame according to the backoff result (i.e., the value of the backoff counter). The secondary channel in which the STA performs backoff may be predefined (i.e., determined between the AP and the STA without separate signaling) or may be preconfigured (i.e., signaled to the STA by the AP through separate signaling).

In the following description, among the secondary channels, a secondary channel defined/configured to perform backoff is referred to as a secondary backoff channel (or a non-primary backoff channel), and a secondary channel that does not perform backoff but may be included in a channel transmitting a frame is referred to as a secondary non-backoff channel (or a non-primary non-backoff channel).

Embodiment 6-1

This embodiment relates to a secondary channel access method for the case where an independent/separate EDCA parameter set is configured for the secondary backoff channel.

The EDCA parameter set may include various parameters configured for each Access Category (AC), such as Voice (VO), video (VI), best Effort (BE), background (BK), etc. For example, a minimum value of the contention window per AC (e.g., CWmin [ AC ]), a maximum value of the contention window per AC (e.g., CWmax [ AC ]), an arbitration inter-frame space number per AC (AIFSN) (e.g., AIFSN [ AC ]), and the like may be included in the EDCA parameter set.

Accordingly, the STA may maintain and manage a plurality of backoff counters corresponding to the plurality of secondary backoff channels, respectively. The value of each backoff counter may be determined according to the busy/idle state of the corresponding secondary backoff channel. Further, the frame/PPDU may be transmitted on at least one secondary backoff channel (and at least zero secondary non-backoff channels) in which the backoff counter expires (i.e., the value of the backoff counter is 0).

Additionally or alternatively, the frame/PPDU may be transmitted on at least one secondary backoff channel (and at least zero secondary non-backoff channels) in which the backoff counter expires first. Thus, data (e.g., delay sensitive data) that must be sent quickly may be sent first.

Fig. 16 is a diagram illustrating an example of a multi-backoff-based secondary channel access operation in accordance with the present disclosure.

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

For example, information representing the secondary channel access channel may be defined as 16-bit bitmap information. When the value is 0000100000001000, it may indicate that, among 16 20MHz channels (i.e., including P20) within 320MHz, the 5th 20MHz channel (i.e., the first secondary channel of the 2 nd subset of channels) and the 13 th 20MHz channel (i.e., the first secondary channel of the 4 th subset of channels) are secondary backoff channels. Since P20 is always 0 in the information indicating the secondary channel access channel, when P20 is not included, the information may be defined as 15-bit bitmap information and the value thereof may be 000100000001000. In other words, the position of the secondary backoff channel may be indicated for all channel subsets by one bitmap.

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

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

Further, when interference occurs within the STA due to the frame/PPDU transmitted on the 13 th channel while the backoff procedure is performed on the 5 th channel, it may be determined that it is busy as a result of the CCA for the 5 th channel, or the backoff counter may be stopped (i.e., may not be decreased) since the CCA is not properly performed. Thus, the frame/PPDU may be transmitted on the 13 th channel (and the secondary non-backoff channels that are idle in the corresponding subset of channels), where the backoff counter first goes to 0 and the backoff counter does not go to 0 on the 5 th channel.

Fig. 17 is a diagram representing another example of a multi-backoff-based secondary channel access operation in accordance with the present disclosure.

When the back-off counter first becomes 0 on at least one secondary back-off channel, the frame/PPDU may be transmitted on a plurality of secondary back-off channels (and secondary non-back-off channels that are idle in a corresponding subset of channels), where the back-off counter becomes 0 after waiting until the back-off counter on at least one other secondary back-off channel becomes 0.

Unlike the example of fig. 16, which preferably performs transmission on a channel including a secondary backoff channel in which a backoff counter expires first, which has the effect of reducing latency, the example of fig. 17 may have the effect of increasing the data rate, which transmits a larger frame/PPDU or uses more secondary channels.

In the example of fig. 17, it is assumed that information on BSS operation bandwidths included in a beacon frame, whether secondary channel access is allowed, secondary channel access bandwidths (i.e., channel subset units), and secondary channel access channels (i.e., secondary backoff channels) are the same as in the example of fig. 16.

For example, when the back-off counter of the 13 th channel first becomes 0, transmission in the channel subset including the 13 th channel may be waited or deferred until the back-off counter in the 5 th channel becomes 0. When the backoff counter becomes 0 on the 5 th channel, a frame/aPPDU may be transmitted on a second subset of channels including the 5 th channel and a fourth subset of channels including the 13 th channel. In each channel subset, a frame/PPDU may be transmitted on a secondary backoff channel and at least zero idle secondary non-backoff channels. When a particular secondary non-backoff channel is not idle, a frame/PPDU may be transmitted on the remaining idle secondary backoff/non-backoff channels other than the corresponding secondary non-backoff channel. If the idle secondary backoff/non-backoff channel is discontinuous, the punctured PPDU may be transmitted.

Embodiment 6-2

This embodiment relates to a secondary channel access method for the case where one common EDCA parameter set is configured for a secondary backoff channel.

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

For example, the backoff counter may be decremented when at least one of the plurality (or all) of secondary backoff channels associated with one backoff counter is idle.

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

Fig. 18 is a diagram representing another example of a multi-backoff-based secondary channel access operation in accordance with the present disclosure.

In the example of fig. 18, it is assumed that the information for BSS operation 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 fig. 16 and 17.

In the example of fig. 18, for example, for information on a secondary channel access channel (i.e., secondary backoff channel) included in the beacon frame, it is assumed that its value is 0000000010001000. In other words, it may indicate that, among 16 20MHz channels (i.e., including P20) within 320MHz, the 9 th 20MHz channel (i.e., the first secondary channel of the third subset of channels) and the 13 th 20MHz channel (i.e., the first secondary channel of the fourth subset of channels) are secondary backoff channels. Since P20 is always 0 in the information indicating the secondary channel access channel, when P20 is not included, the information may be defined as 15-bit bitmap information and the value thereof may be 000000010001000. In other words, the positions of the secondary backoff channels may be indicated for all channel subsets by one bitmap.

Since the same EDCA parameter set is applied to two secondary backoff channels, the value of one common backoff counter may be decreased according to the idle/busy state of each secondary backoff channel.

For example, the common back-off counter may be decremented when at least one of the 9 th and 13 th channels, which are secondary back-off channels, is idle.

Alternatively, the common back-off counter may be decremented when both the 9 th and 13 th channels, which are secondary back-off channels, are idle.

Accordingly, when the value of one common backoff counter expires (i.e., the value of the backoff counter becomes 0), the frame/PPDU may be transmitted on at least zero idle secondary non-backoff channels within a subset of channels including the 9 th channel and the 13 th channel and to which each secondary backoff channel belongs. For example, when the 9 th channel and the 13 th channel, which are secondary backoff channels, are idle and the 10 th to 12 th channels and the 14 th to 16 th channels, which are secondary non-backoff channels, are idle, the TXOP may be obtained by transmitting an RTS frame on a 160MHz channel, and after receiving a CTS frame from the AP, a data frame may 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 channel subset and the fourth channel subset. The punctured PPDU may be transmitted when the idle secondary channel is discontinuous.

Embodiment 6-3

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

The STA performing the secondary channel access may transmit a frame/PPDU on at least one secondary channel even during a time when the primary channel is busy (e.g., a state in which a basic NAV is configured for the primary channel). For example, the STA may transmit a frame/PPDU on at least one idle secondary channel through a backoff procedure performed on at least one secondary backoff channel and a CCA on at least one secondary non-backoff channel, wherein the primary channel is excluded/punctured.

Additionally or alternatively, the TXOP starting with the frame/PPDU transmission on the SCH may be configured to terminate before the point in time at which the NAV on the primary channel terminates. The length of the TXOP may be configured/indicated by a duration/ID field of the corresponding frame. For example, the value of the duration/ID field may be set to a value corresponding to a time required to exchange the frame/PPDU after the corresponding frame/PPDU (e.g., a time including a length of the frame/PPDU and an inter-frame space (IFS)).

Additionally or alternatively, configuration information related to secondary channel access, such as information on whether a frame/PPDU can be transmitted on a secondary channel, secondary channel access bandwidth (i.e., channel subset unit), information on at least one secondary channel in which backoff is performed when transmission is possible (i.e., secondary backoff channel), and the like, may be included in a management frame (e.g., beacon frame) that may be transmitted by an AP. When the STA performing the secondary channel access is an AP STA, it may perform the secondary channel access by using configuration information related to the secondary channel access transmitted by itself. When the STA performing the secondary channel access is a non-AP STA, it may perform the secondary channel access by using secondary channel access-related configuration information received from the AP STA.

Additionally or alternatively, information for at least one secondary channel in which backoff is performed (i.e., secondary backoff channel) may be transmitted based on a subset of channels that divide the bandwidth of the entire BSS operation channel by some unit (e.g., 40MHz, 80MHz, etc.). For example, a secondary backoff channel may be indicated in each divided channel subset. In some examples, at least one subset of channels that does not include secondary backoff channels may be configured.

Additionally or alternatively, when the backoff counter for the secondary backoff channels within one channel subset becomes 0, the channel in 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 other secondary channels (i.e., secondary non-backoff channels included in the same channel subset). When configuring multiple channel subsets, the channel in which the second type of CCA is performed may also correspond to a secondary non-backoff channel in other channel subsets.

For example, with regard to the above-described embodiment 6-1 (i.e., an example in which the individual/independent EDCA parameter sets are configured for a plurality of secondary backoff channels), although the second backoff counter for the second secondary backoff channel does not become 0, when the first backoff counter for the first secondary backoff channel becomes 0, the frame/PPDU may be first transmitted on the secondary backoff channel (and at least zero secondary non-backoff channels) in which the backoff counter expires.

Additionally or alternatively, with respect to embodiment 6-1 described above (i.e., an example in which separate/independent EDCA parameter sets are configured 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/deferred 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 at least zero secondary non-backoff channels).

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

Additionally or alternatively, information for the maximum bandwidth of the frame/PPDU on the secondary channel may be transmitted in a management frame (e.g., beacon frame) transmitted by the AP. When the STA performing the secondary channel access is an AP STA, it may perform the secondary channel access by using information of maximum bandwidth transmitted by itself for a frame/PPDU related to the secondary channel access. When the STA performing the secondary channel access is a non-AP STA, it may perform the secondary channel access by using information of a maximum bandwidth for a frame/PPDU transmission related to the secondary channel access received from the AP STA.

Additionally or alternatively, the EDCA parameter set for the secondary backoff channel may be configured the same as the EDCA parameter set for the primary channel, or may be configured as a MU EDCA parameter set, or may be configured as a new EDCA parameter set. The EDCA parameter set for this secondary backoff channel may be configured separately/independently (i.e., may be the same or different) for different secondary backoff channels, as in embodiment 6-1, or may be configured identically/jointly for different secondary backoff channels, as in embodiment 6-2.

Additionally or alternatively, the power measured on the secondary back-off/non-back-off channel may be determined to be busy or idle based on whether it is greater than or less than or equal to a predetermined threshold, and the threshold may be configured for each of the first type of CCA and the second type of CCA. The threshold for the first type of CCA and/or the threshold for the second type of CCA may be included in a management frame (e.g., beacon frame) transmitted by the AP. When the STA performing the secondary channel access is an AP STA, it may perform the secondary channel access by using a threshold for a first type of CCA and/or a threshold for a second type of CCA transmitted by itself. When the STA performing the secondary channel access is a non-AP STA, it may perform the secondary channel access by using a threshold for a first type of CCA and/or a threshold for a second type of CCA received from the AP STA. In various examples of the present disclosure, an STA receiving a frame/PPDU transmitted through a secondary channel access may perform frame/PPDU detection on a secondary channel even during a time when a NAV for a primary channel is configured. For example, a STA may perform backoff on the secondary channel when 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. Further, the STA may perform NAV setting/resetting for the secondary channel based on the value of the duration/ID field of the frame detected on the secondary channel.

Unlike the back-off based channel access for the primary channel in the existing WLAN system, by the back-off based channel access for the secondary channel (or non-primary channel) according to the examples of the present disclosure, fast frame/PPDU transmission or transmission rate improvement can be supported on the idle secondary channel even when the primary channel is busy.

The above-described embodiments are intended to combine elements and features of the present disclosure in a predetermined form. Individual elements or features should be considered optional unless explicitly mentioned otherwise. Each element or feature may be implemented in a form not combined with other elements or features. Additionally, embodiments of the present disclosure may include combined partial elements and/or features. The order of operations described in embodiments of the present disclosure may be changed. Some elements or features of one embodiment may be included in or substituted for corresponding elements or features of other embodiments. It will be apparent that embodiments may include claims that do not explicitly refer to a relationship in a combination claim or may be included as new claims by modification after application.

It will be apparent to those skilled in the relevant art that the present disclosure may be embodied in other specific forms without departing from the essential characteristics of the disclosure. The foregoing detailed description is, therefore, not to be taken in a limiting sense, and is intended to be illustrative in every respect. The scope of the present disclosure should be determined by a fair interpretation of the accompanying claims, and all changes that come within the meaning and range of equivalency of the disclosure are intended to be embraced therein.

The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, application programs, firmware, programs, etc.) that perform operations in accordance with the methods of the various embodiments in an apparatus or computer, as well as non-transitory computer-readable media that cause the software or instructions to be stored and executed in an apparatus or computer. Commands that may be used to program a processing system that performs the features described in this disclosure may be stored in a storage medium or a computer readable storage medium, and the features described in this disclosure may be implemented by using a computer program product that includes such a storage medium. The storage medium may include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid state storage devices, and it may 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 located remotely from the processor. The memory, or alternatively, the non-volatile memory device in the memory, comprises a non-transitory computer-readable storage medium. The features described in this disclosure may be stored in any one of a variety of machine-readable media to control the hardware of the processing system, and may be integrated into software and/or firmware that allows the processing system to interact with other mechanisms using results from 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.

Industrial applicability

The method proposed by the present disclosure is mainly described based on an example applied to an IEEE 802.11 based system (5G system), but may be applied to various WLANs or wireless communication systems other than the IEEE 802.11 based system.

Claims

1. A method performed by a first station STA in a wireless local area network, WLAN, system, the method comprising the steps of:

receiving information for a plurality of enhanced distributed channel access EDCA parameter sets respectively associated with a plurality of non-primary backoff channels from a second STA;

performing a backoff procedure on the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets, and

At least one physical layer protocol data unit, PPDU, is transmitted on at least one channel comprising at least one of the plurality of non-primary back-off channels and at least zero non-primary non-back-off channels.

2. The method of claim 1, wherein,

A first backoff procedure based on a first EDCA parameter set for a first non-primary backoff channel and a second backoff procedure based on a second EDCA parameter set for a second non-primary backoff channel are performed in parallel or independently.

3. The method of claim 2, wherein,

The first back-off procedure includes decrementing a first back-off counter based on the medium on the first non-primary back-off channel being determined to be idle based on the first EDCA parameter set, and

The second backoff procedure includes decrementing a first backoff counter based on the medium on the second non-primary backoff channel being determined to be idle based on the second EDCA parameter set.

4. The method of claim 3, wherein based on the first back-off counter expiring and the second back-off counter not expiring:

One PPDU is transmitted on the first non-primary backoff channel and at least zero first non-primary non-backoff channels associated with the first non-primary backoff channel.

5. The method of claim 3, wherein based on the first back-off counter expiring and the second back-off counter not expiring:

Deferring transmission of a PPDU on the first non-primary backoff channel and at least zero first non-primary non-backoff channels associated with the first non-primary backoff channel.

6. The method of claim 5, wherein the at least one PPDU is transmitted on the following basis that the second back-off counter expires after the first back-off counter expires:

The first non-primary backoff channel;

the at least zero first non-primary non-backoff channels;

the second non-primary backoff channel, and

At least zero second non-primary non-back-off channels associated with the second non-primary back-off channel.

7. The method of claim 6, wherein,

At the same time

Transmitting a first PPDU on the first non-primary backoff channel and the at least zero first non-primary non-backoff channel, an

And transmitting a second PPDU on the second non-primary non-backoff channel and the at least zero second non-primary non-backoff channel.

8. The method of claim 6, wherein one PPDU is transmitted on:

The first non-primary backoff channel;

the at least zero first non-primary non-backoff channels;

the second non-primary backoff channel, and

The at least zero second non-primary non-backoff channels.

9. The method of claim 8, wherein,

The one PPDU is transmitted on a continuous channel or a discontinuous channel.

10. The method of claim 1, wherein,

One non-primary non-backoff channel included in the at least one channel is a non-primary channel determined to be idle by a non-primary channel idle channel assessment CCA during a predetermined time before a backoff counter for the non-primary backoff channel associated with the one non-primary non-backoff channel expires.

11. The method of claim 1, wherein,

The plurality of non-primary backoff channels are included in the same channel subset or in different channel subsets.

12. The method of claim 11, wherein,

The number of non-primary backoff channels included in one channel subset is greater than or equal to 1, and

The number of non-primary non-backoff channels included in the one channel subset is greater than or equal to 0.

13. The method of claim 12, wherein,

The one channel subset corresponds to a maximum bandwidth for PPDUs transmitted based on a backoff procedure for at least one non-primary backoff channel included in the one channel subset.

14. An apparatus of a first station STA in a wireless local area network WLAN system, the apparatus comprising:

at least one transceiver, and

At least one processor coupled to the at least one transceiver,

Wherein the at least one processor is configured to:

Receiving, by the at least one transceiver, information from a second STA for a plurality of enhanced distributed channel access EDCA parameter sets associated with a plurality of non-primary backoff channels, respectively;

At least one physical layer protocol data unit, PPDU, is transmitted by the at least one transceiver on at least one channel comprising at least one of the plurality of non-primary back-off channels and at least zero non-primary non-back-off channels.

15. A method performed by a second station STA in a wireless local area network WLAN system, the method comprising the steps of:

Transmitting information to the first STA for a plurality of enhanced distributed channel access EDCA parameter sets respectively associated with a plurality of non-primary backoff channels, and

At least one physical layer protocol data unit, PPDU, is received from the first STA on at least one channel including at least one of the plurality of non-primary backoff channels and at least zero non-primary non-backoff channels, the at least one PPDU being transmitted by the first STA through a backoff procedure performed on the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets.

16. An apparatus of a second station STA in a wireless local area network WLAN system, the apparatus comprising:

at least one transceiver, and

At least one processor coupled to the at least one transceiver,

Wherein the at least one processor is configured to:

transmitting, by the at least one transceiver, information to the first STA for a plurality of enhanced distributed channel access, EDCA, parameter sets associated with a plurality of non-primary backoff channels, respectively, and

At least one physical layer protocol data unit, PPDU, is received by the at least one transceiver from the first STA over at least one channel including at least one of the plurality of non-primary backoff channels and at least zero non-primary non-backoff channels, the at least one PPDU being transmitted by the first STA over a backoff procedure performed on the plurality of non-primary backoff channels based on the plurality of EDCA parameter sets.

17. A processing apparatus configured to control a station STA in a wireless local area network WLAN system, the processing apparatus comprising:

At least one processor, and

At least one computer memory operatively connected to the at least one processor, and the at least one computer memory storing instructions for performing the method of any one of claims 1 to 13 based on execution by the at least one processor.

18. At least one non-transitory computer-readable medium storing at least one instruction, wherein,

The at least one instruction, by execution by at least one processor, to control a device to perform the method according to any one of claims 1 to 13 in a wireless local area network, WLAN, system.