WO2024237604A1 - Procédé et appareil de réduction d'une interférence de nœud caché dans un système lan sans fil - Google Patents

Procédé et appareil de réduction d'une interférence de nœud caché dans un système lan sans fil Download PDF

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Publication number
WO2024237604A1
WO2024237604A1 PCT/KR2024/006402 KR2024006402W WO2024237604A1 WO 2024237604 A1 WO2024237604 A1 WO 2024237604A1 KR 2024006402 W KR2024006402 W KR 2024006402W WO 2024237604 A1 WO2024237604 A1 WO 2024237604A1
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Prior art keywords
sta
bss
information
ppdu
twt
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English (en)
Korean (ko)
Inventor
백선희
최진수
장인선
김건환
윤예린
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LG Electronics Inc
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LG Electronics Inc
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Priority to CN202480032023.2A priority Critical patent/CN121336462A/zh
Priority to KR1020257037043A priority patent/KR20260002845A/ko
Publication of WO2024237604A1 publication Critical patent/WO2024237604A1/fr
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/08—Testing, supervising or monitoring using real traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. Transmission Power Control [TPC] or power classes
    • H04W52/02—Power saving arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0446—Resources in time domain, e.g. slots or frames
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/20—Control channels or signalling for resource management
    • H04W72/27—Control channels or signalling for resource management between access points
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]

Definitions

  • the present disclosure relates to a method and device for transmitting or receiving for reducing interference to a hidden node in a wireless local area network (WLAN) system.
  • WLAN wireless local area network
  • Wi-Fi wireless LAN
  • VHT Very High-Throughput
  • HE High Efficiency
  • EHT Extremely High Throughput
  • technologies for MIMO (Multiple Input Multiple Output) and multi-access point (AP) coordination that support increased bandwidth, efficient utilization of multiple bands, and increased spatial streams are being studied, and in particular, various technologies are being studied to support low latency or real-time traffic.
  • new technologies are being discussed to support ultra-high reliability (UHR), including improvements or extensions of EHT technologies.
  • the technical problem of the present disclosure is to provide a method and device for transmitting or receiving to reduce interference to a hidden node in a wireless LAN system.
  • a method performed by a first station (STA) in a wireless LAN system may include: monitoring, by the first STA associated with a first access point (AP) of a first basic service set (BSS), an inter-BSS physical layer protocol data unit (PPDU) transmitted from a second STA belonging to a second BSS or transmitted to the second STA; transmitting, to the first AP, report information including information indicating that the inter-BSS PPDU has been received or not been received; and receiving, from the first AP, scheduling information for the first STA based on the report information.
  • AP access point
  • PPDU physical layer protocol data unit
  • a method performed by a first access point (AP) in a wireless LAN system may include the steps of: receiving, from a first station (STA) associated with the first AP of a first basic service set (BSS), report information including information indicating that an inter-BSS physical layer protocol data unit (PPDU) transmitted from a second STA belonging to a second BSS or transmitted to the second STA is received or not received by the first STA; and transmitting, to the first STA, scheduling information for the first STA based on the report information.
  • STA station
  • BSS basic service set
  • a method and device for transmitting or receiving for reducing interference to a hidden node in a wireless LAN system can be provided.
  • FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.
  • FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.
  • FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.
  • FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.
  • FIG. 5 is a diagram for explaining a CSMA/CA-based frame transmission operation to which the present disclosure can be applied.
  • FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.
  • FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.
  • FIG. 8 is a diagram for explaining various transmission and reception techniques in a MAP environment to which the present disclosure can be applied.
  • FIG. 9 is a diagram illustrating an example of an individual TWT operation to which the present disclosure can be applied.
  • FIG. 10 is a diagram illustrating an example of a broadcast TWT operation to which the present disclosure can be applied.
  • FIG. 11 is a diagram showing an exemplary format of a silence element and an exemplary format of a silence channel element to which the present disclosure can be applied.
  • FIG. 12 is a diagram exemplarily showing STAs in an OBSS to which the present disclosure can be applied.
  • Figure 13 shows an example of OBSS R-TWT SP protection to which the present disclosure can be applied.
  • FIG. 14 and FIG. 15 are drawings for explaining examples of hidden nodes according to the present disclosure.
  • FIG. 16 is a diagram for explaining the operation of STA according to the present disclosure.
  • FIG. 17 is a drawing for explaining the operation of an AP according to the present disclosure.
  • first in one embodiment
  • second component in another embodiment
  • first component in another embodiment may be referred to as a first component in another embodiment
  • the examples of the present disclosure can be applied to various wireless communication systems.
  • the examples of the present disclosure can be applied to a wireless LAN system.
  • the examples of the present disclosure can be applied to a wireless LAN based on IEEE 802.11a/g/n/ac/ax/be standards.
  • the examples of the present disclosure can be applied to a wireless LAN based on a newly proposed IEEE 802.11bn (or UHR) standard.
  • the examples of the present disclosure can be applied to a wireless LAN based on a next-generation standard after IEEE 802.11bn.
  • the examples of the present disclosure can be applied to a cellular wireless communication system.
  • the examples of the present disclosure can be applied to a cellular wireless communication system based on a Long Term Evolution (LTE) series technology of the 3rd Generation Partnership Project (3GPP) standard and a New Radio (5G NR) series technology.
  • LTE Long Term Evolution
  • 3GPP 3rd Generation Partnership Project
  • 5G NR New Radio
  • FIG. 1 illustrates a block diagram of a wireless communication device according to one embodiment of the present disclosure.
  • the first device (100) and the second device (200) illustrated in FIG. 1 may be replaced with various terms such as a terminal, a wireless device, a 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 (MSS), a Subscriber Station (SS), an Advanced Mobile Station (AMS), a Wireless terminal (WT), or simply a user.
  • WTRU Wireless Transmit Receive Unit
  • UE User Equipment
  • MS Mobile Station
  • UT a Mobile Subscriber Station
  • MSS Mobile Subscriber Unit
  • SS Subscriber Station
  • AMS Advanced Mobile Station
  • WT Wireless terminal
  • first device (100) and the second device (200) may be replaced with various terms such as an access point (AP), a base station (BS), a fixed station, a Node B, a base transceiver system (BTS), a network, an Artificial Intelligence (AI) system, a road side unit (RSU), a repeater, a router, a relay, a gateway, etc.
  • AP access point
  • BS base station
  • BTS base transceiver system
  • AI Artificial Intelligence
  • RSU road side unit
  • RSU repeater
  • router a relay
  • gateway a gateway
  • the devices (100, 200) illustrated in FIG. 1 may also be referred to as stations (STAs).
  • STAs stations
  • the devices (100, 200) illustrated in FIG. 1 may be referred to by various terms such as a transmitting device, a receiving device, a transmitting STA, and a receiving STA.
  • the STAs (110, 200) may perform an AP (access point) role or a non-AP role. That is, the STAs (110, 200) in the present disclosure may perform functions of an AP and/or a non-AP.
  • the STAs (110, 200) When the STAs (110, 200) perform an AP function, they may simply be referred to as APs, and when the STAs (110, 200) perform a non-AP function, they may simply be referred to as STAs.
  • the APs in the present disclosure may also be indicated as AP STAs.
  • the first device (100) and the second device (200) can transmit and receive wireless signals through various wireless LAN technologies (e.g., IEEE 802.11 series).
  • the first device (100) and the second device (200) can include interfaces for a medium access control (MAC) layer and a physical layer (PHY) that follow the regulations of the IEEE 802.11 standard.
  • MAC medium access control
  • PHY physical layer
  • the first device (100) and the second device (200) may additionally support various communication standards (for example, standards of 3GPP LTE series, 5G NR series, etc.) other than wireless LAN technology.
  • the device of the present disclosure may be implemented as various devices such as a mobile phone, a vehicle, a personal computer, an Augmented Reality (AR) device, and a Virtual Reality (VR) device.
  • the STA of the present specification may support various communication services such as a voice call, a video call, a data communication, autonomous driving, MTC (Machine-Type Communication), M2M (Machine-to-Machine), D2D (Device-to-Device), and IoT (Internet-of-Things).
  • a first device (100) includes one or more processors (102) and one or more memories (104), and may additionally include one or more transceivers (106) and/or one or more antennas (108).
  • the processor (102) controls the memories (104) and/or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in the present disclosure.
  • the processor (102) may process information in the memory (104) to generate first information/signal, and then transmit a wireless signal including the first information/signal via the transceiver (106).
  • the processor (102) may receive a wireless signal including second information/signal via the transceiver (106), and then store information obtained from signal processing of the second information/signal in the memory (104).
  • the memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software codes including instructions for performing the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in the present disclosure.
  • the processor (102) and the memory (104) may be part of a communication modem/circuit/chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series).
  • the transceiver (106) may be connected to the processor (102) and may transmit and/or receive wireless signals via one or more antennas (108).
  • the transceiver (106) may include a transmitter and/or a receiver.
  • the transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit.
  • a device may also mean a communication modem/circuit/chip.
  • the second device (200) includes one or more processors (202), one or more memories (204), and may additionally include one or more transceivers (206) and/or one or more antennas (208).
  • the processor (202) may control the memories (204) and/or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this disclosure.
  • the processor (202) may process information in the memory (204) to generate third information/signal, and then transmit a wireless signal including the third information/signal via the transceiver (206).
  • the processor (202) may receive a wireless signal including fourth information/signal via the transceiver (206), and then store information obtained from signal processing of the fourth information/signal in the memory (204).
  • the memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software codes including instructions for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in the present disclosure.
  • the processor (202) and the memory (204) may be part of a communication modem/circuit/chip designed to implement a wireless LAN technology (e.g., IEEE 802.11 series).
  • the transceiver (206) may be connected to the processor (202) and may transmit and/or receive wireless signals via one or more antennas (208).
  • the transceiver (206) may include a transmitter and/or a receiver.
  • the transceiver (206) may be used interchangeably with an RF unit.
  • a device may also mean a communication modem/circuit/chip.
  • one or more protocol layers may be implemented by one or more processors (102, 202).
  • one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC).
  • One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this disclosure.
  • PDUs Protocol Data Units
  • SDUs Service Data Units
  • One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this disclosure.
  • One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, suggestions and/or methodologies disclosed in this disclosure, and provide the signals to one or more transceivers (106, 206).
  • One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this disclosure.
  • signals e.g., baseband signals
  • the one or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer.
  • the one or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof.
  • ASICs Application Specific Integrated Circuits
  • DSPs Digital Signal Processors
  • DSPDs Digital Signal Processing Devices
  • PLDs Programmable Logic Devices
  • FPGAs Field Programmable Gate Arrays
  • the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc.
  • the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this disclosure may be implemented using firmware or software configured to perform one or more of the following: included in one or more processors (102, 202), or stored in one or more memories (104, 204) and driven by one or more of the processors (102, 202).
  • the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this disclosure may be implemented using firmware or software in the form of codes, instructions and/or sets of instructions.
  • One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and/or commands.
  • the one or more memories (104, 204) may be comprised of ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer readable storage media, and/or combinations thereof.
  • the one or more memories (104, 204) may be located internally and/or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.
  • One or more transceivers (106, 206) can transmit user data, control information, wireless signals/channels, etc., as mentioned in the methods and/or flowcharts of the present disclosure, to one or more other devices.
  • One or more transceivers (106, 206) can receive user data, control information, wireless signals/channels, etc., as mentioned in the descriptions, functions, procedures, suggestions, methods and/or flowcharts of the present disclosure, from one or more other devices.
  • one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals.
  • one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals/channels, and the like, as described in the description, function, procedure, proposal, method, and/or operational flowchart, etc.
  • one or more antennas may be multiple physical antennas, or multiple logical antennas (e.g., antenna ports).
  • One or more transceivers (106, 206) may convert received user data, control information, wireless signals/channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals/channels, etc. using one or more processors (102, 202).
  • One or more transceivers (106, 206) may convert processed user data, control information, wireless signals/channels, etc. from baseband signals to RF band signals using one or more processors (102, 202).
  • one or more transceivers (106, 206) may include an (analog) oscillator and/or filter.
  • one of the STAs (100, 200) may perform the intended operation of an AP, and the other of the STAs (100, 200) may perform the intended operation of a non-AP STA.
  • the transceivers (106, 206) of FIG. 1 may perform transmission and reception operations of signals (e.g., packets or PPDUs (Physical layer Protocol Data Units) according to IEEE 802.11a/b/g/n/ac/ax/be/bn, etc.).
  • signals e.g., packets or PPDUs (Physical layer Protocol Data Units) according to IEEE 802.11a/b/g/n/ac/ax/be/bn, etc.
  • operations of various STAs generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals may be performed in the processors (102, 202) of FIG. 1.
  • an example of an operation for generating a transmit/receive signal or performing data processing or calculation in advance for a transmit/receive signal may include: 1) an operation for determining/acquiring/configuring/computing/decoding/encoding bit information of a field (SIG (signal), STF (short training field), LTF (long training field), Data, etc.) included in a PPDU, 2) an operation for determining/configuring/acquiring time resources or frequency resources (e.g., subcarrier resources) used for the fields (SIG, STF, LTF, Data, etc.) included in a PPDU, 3) an operation for determining/configuring/acquiring specific sequences (e.g., pilot sequences, STF/LTF sequences, extra sequences applied to SIG) used for the fields (SIG, STF, LTF, Data, etc.) included in a PPDU, 4) a power control operation and/or a power saving operation applied to an STA, 5) an operation related to determining/acquiring/acquiring/
  • various information e.g., information related to fields/subfields/control fields/parameters/power, etc.
  • various information e.g., information related to fields/subfields/control fields/parameters/power, etc.
  • various STAs for determining/acquiring/configuring/computing/decoding/encoding transmission/reception signals can be stored in the memory (104, 204) of FIG. 1.
  • downlink means a link for communication from an AP STA to a non-AP STA, and downlink PPDU/packet/signal, etc. can be transmitted and received through the downlink.
  • a transmitter may be part of an AP STA, and a receiver may be part of a non-AP STA.
  • Uplink (UL) means a link for communication from a non-AP STA to an AP STA, and uplink PPDU/packet/signal, etc. can be transmitted and received through the uplink.
  • a transmitter may be part of a non-AP STA, and a receiver may be part of an AP STA.
  • FIG. 2 is a diagram showing an exemplary structure of a wireless LAN system to which the present disclosure can be applied.
  • a wireless LAN supporting transparent STA mobility to a higher layer can be provided through the interaction of multiple components.
  • a BSS Basic Service Set
  • FIG. 2 illustrates an example in which two BSSs (BSS1 and BSS2) exist and two STAs are included as members of each BSS (STA1 and STA2 are included in BSS1, and STA3 and STA4 are included in BSS2).
  • An ellipse representing a BSS in FIG. 2 can also be understood as representing a coverage area in which STAs included in the corresponding BSS maintain communication. This area can be referred to as a BSA (Basic Service Area). If an STA moves out of the BSA, it cannot directly communicate with other STAs within the corresponding BSA.
  • BSA Basic Service Area
  • an IBSS can have a minimal form consisting of only two STAs.
  • BSS1 consisting of only STA1 and STA2
  • BSS2 consisting of only STA3 and STA4
  • This configuration is possible when STAs can communicate directly without an AP.
  • a LAN can be configured when needed rather than being planned in advance, and this can be called an ad-hoc network.
  • an IBSS does not include an AP, there is no centralized management entity that performs management functions. That is, in an IBSS, STAs are managed in a distributed manner. In IBSS, all STAs can be mobile STAs, and access to distributed systems (DS) is not permitted, forming a self-contained network.
  • DS distributed systems
  • the membership of an STA in a BSS can be dynamically changed by the STA turning on or off, the STA entering or leaving the BSS area, etc.
  • an STA can join the BSS using a synchronization process.
  • an STA In order to access all services of the BSS infrastructure, an STA must be associated with a BSS. This association can be dynamically established and may include the use of a Distribution System Service (DSS).
  • DSS Distribution System Service
  • the direct STA-to-STA distance may be limited by the PHY performance. In some cases, this distance limitation may be sufficient, but in some cases, communication between STAs over longer distances may be required.
  • a distributed system may be configured.
  • DS refers to a structure in which BSSs are interconnected.
  • a BSS may exist as an extended component of a network composed of multiple BSSs, as shown in FIG. 2.
  • DS is a logical concept and can be specified by the characteristics of a distributed system medium (DSM).
  • DSM distributed system medium
  • WM wireless medium
  • DSM distributed system medium
  • Each logical medium is used for a different purpose and is used by different components. These media are neither limited to being the same nor limited to being different.
  • the flexibility of a wireless LAN structure can be explained in that multiple media are logically different.
  • a wireless LAN structure can be implemented in various ways, and each wireless LAN structure can be independently specified by the physical characteristics of each implementation example.
  • a DS can support mobile devices by providing seamless integration of multiple BSSs and providing logical services necessary to handle addresses to destinations.
  • a DS can further include a component called a portal that acts as a bridge for connecting wireless LANs to other networks (e.g., IEEE 802.X).
  • An AP is an entity that enables access to a DS through a WM for associated non-AP STAs, and also has the functionality of an STA. Data movement between a BSS and a DS can be performed through an AP.
  • STA2 and STA3 illustrated in FIG. 2 have the functionality of an STA, and provide a function that allows associated non-AP STAs (STA1 and STA4) to access the DS.
  • all APs are basically STAs, all APs are addressable entities.
  • the address used by an AP for communication on a WM and the address used by an AP for communication on a DSM need not necessarily be the same.
  • a BSS consisting of an AP and one or more STAs can be called an infrastructure BSS.
  • Data transmitted from one of the STA(s) associated with an AP to the STA address of that AP is always received on an uncontrolled port and can be processed by an IEEE 802.1X port access entity.
  • the transmitted data (or frame) can be forwarded to the DS.
  • an Extended Service Set may be established to provide wider coverage.
  • An ESS is a network of arbitrary size and complexity consisting of DS and BSS.
  • An ESS may correspond to a set of BSSs connected to a DS. However, an ESS does not include a DS.
  • An ESS network is characterized by being seen as an IBSS in the LLC (Logical Link Control) layer. STAs included in an ESS can communicate with each other, and mobile STAs can move from one BSS to another BSS (within the same ESS) transparently to the LLC.
  • APs included in an ESS may have the same SSID (service set identification). The SSID is distinct from the BSSID, which is an identifier of the BSS.
  • the BSSs can be partially overlapped, which is a common configuration used to provide continuous coverage.
  • the BSSs can be physically unconnected, and logically there is no limit to the distance between the BSSs.
  • the BSSs can be physically co-located, which can be used to provide redundancy.
  • one (or more) IBSS or ESS networks can physically co-exist in the same space as one (or more) ESS networks. This can correspond to ESS network configurations such as cases where ad-hoc networks operate at locations where ESS networks exist, cases where physically overlapping wireless networks are configured by different organizations, or cases where two or more different access and security policies are required at the same location.
  • FIG. 3 is a diagram for explaining a link setup process to which the present disclosure can be applied.
  • the link setup process may also be referred to as a session initiation process or a session setup process.
  • the discovery, authentication, association, and security setup processes of the link setup process may be collectively referred to as the association process.
  • 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 the STA to access the network, it must find a network that it can participate in. The STA must identify a compatible network before participating in the wireless network, and the process of identifying networks existing in a specific area is called scanning.
  • FIG. 3 illustrates a network discovery operation including an active scanning process as an example.
  • active scanning an STA performing scanning transmits a probe request frame to search for APs in the vicinity while moving between channels and waits for a response thereto.
  • a responder transmits a probe response frame to the STA that transmitted the probe request frame as a response to the probe request frame.
  • the responder may be an STA that last transmitted a beacon frame in the BSS of the channel being scanned.
  • the AP transmits a beacon frame, so the AP becomes the responder, and in the IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not fixed.
  • an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe request/response on channel 2) in the same manner.
  • the next channel e.g., channel 2
  • scanning i.e., transmitting and receiving probe request/response on channel 2
  • the scanning operation can also be performed in a passive scanning manner.
  • passive scanning an STA performing scanning moves through channels and waits for a beacon frame.
  • a beacon frame is one of the management frames defined in IEEE 802.11, and is periodically transmitted to notify the existence of a wireless network and to enable an STA performing scanning to find a wireless network and participate in the wireless network.
  • an AP In a BSS, an AP periodically transmits a beacon frame, and in an IBSS, STAs in the IBSS take turns transmitting beacon frames.
  • an STA performing scanning receives a beacon frame, it stores information about the BSS included in the beacon frame and moves to another channel, recording beacon frame information on each channel.
  • An STA receiving a beacon frame stores information related to the BSS included in the received beacon frame, moves to the next channel, and performs scanning on the next channel in the same manner. Comparing active scanning and passive scanning, active scanning has the advantage of lower delay and power consumption than passive scanning.
  • step S320 After the STA discovers the network, an authentication process may be performed in step S320.
  • This authentication process may be referred to as a first authentication process to clearly distinguish it from the security setup operation of step S340 described below.
  • the authentication process includes the STA sending an authentication request frame to the AP, and the AP sending an authentication response frame to the STA in response.
  • the authentication frame used for the authentication request/response corresponds to a management frame.
  • the authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), a Finite Cyclic Group, etc. These are just some examples of information that may be included in an authentication request/response frame, and may be replaced by other information or may include additional information.
  • RSN Robust Security Network
  • the STA may transmit an authentication request frame to the AP.
  • the AP may determine whether to allow authentication for the STA based on information included in the received authentication request frame.
  • the AP may provide the result of the authentication processing to the STA through an authentication response frame.
  • an association process may be performed in step S330.
  • the association process includes a process in which the STA transmits an association request frame to the AP, and in response, the AP transmits an association response frame to the STA.
  • the association request frame may include information about various capabilities, a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, mobility domains, supported operating classes, a Traffic Indication Map Broadcast request, interworking service capabilities, etc.
  • the association response frame may include information about various capabilities, a status code, an Association ID (AID), supported rates, an Enhanced Distributed Channel Access (EDCA) parameter set, a Received Channel Power Indicator (RCPI), a Received Signal to Noise Indicator (RSNI), a mobility domain, a timeout interval (e.g., association comeback time), overlapping BSS scan parameters, a TIM broadcast response, a Quality of Service (QoS) map, etc.
  • AID Association ID
  • EDCA Enhanced Distributed Channel Access
  • RCPI Received Channel Power Indicator
  • RSNI Received Signal to Noise Indicator
  • timeout interval e.g., association comeback time
  • overlapping BSS scan parameters e.g., TIM broadcast response
  • a security setup process may be performed in step S340.
  • the security setup process of step S340 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request/response
  • the authentication process of step S320 may be referred to as a first authentication process
  • the security setup process of step S340 may be referred to simply as an authentication process.
  • RSNA Robust Security Network Association
  • the security setup process of step S340 may include a process of performing private key setup, for example, through 4-way handshaking via an Extensible Authentication Protocol over LAN (EAPOL) frame. Additionally, the security setup process may be performed according to a security method not defined in the IEEE 802.11 standard.
  • EAPOL Extensible Authentication Protocol over LAN
  • FIG. 4 is a diagram for explaining a backoff process to which the present disclosure can be applied.
  • the basic access mechanism of MAC is the CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism.
  • the CSMA/CA mechanism is also called the Distributed Coordination Function (DCF) of IEEE 802.11 MAC, and basically adopts the "listen before talk" access mechanism.
  • DCF Distributed Coordination Function
  • the AP and/or STA may perform a Clear Channel Assessment (CCA) to sense the wireless channel or medium for a predetermined time period (e.g., a DCF Inter-Frame Space (DIFS)) before starting transmission. If the sensing result determines that the medium is in an idle state, the AP and/or STA may start transmitting frames through the medium.
  • CCA Clear Channel Assessment
  • DIFS DCF Inter-Frame Space
  • the AP and/or STA may not start its own transmission, but may wait for a delay period (e.g., a random backoff period) for medium access and then attempt to transmit frames.
  • a delay period e.g., a random backoff period
  • the IEEE 802.11 MAC protocol provides a Hybrid Coordination Function (HCF).
  • the HCF is based on the DCF and the Point Coordination Function (PCF).
  • the PCF is a polling-based synchronous access method in which all receiving APs and/or STAs periodically poll to receive data frames.
  • the HCF has EDCA (Enhanced Distributed Channel Access) and HCCA (HCF Controlled Channel Access).
  • EDCA is a contention-based access method in which a provider provides data frames to multiple users, and HCCA uses a non-contention-based channel access method using a polling mechanism.
  • the HCF includes a medium access mechanism for improving the QoS (Quality of Service) of a wireless LAN, and can transmit QoS data in both a contention period (CP) and a contention-free period (CFP).
  • QoS Quality of Service
  • a random backoff period When an occupied/busy medium changes to an idle state, multiple STAs may attempt to transmit data (or frames). As a measure to minimize collisions, each STA may select a random backoff count, wait for a corresponding slot time, and then attempt to transmit.
  • the random backoff count has a pseudo-random integer value and may be determined as one of the values in the range of 0 to CW.
  • CW is a contention window parameter value.
  • the CW parameter is initially given CWmin, but may take a double value in case of a transmission failure (e.g., when an ACK for a transmitted frame is not received).
  • the STA continues to monitor the medium while counting down the backoff slots according to the determined backoff count value. If the medium is monitored as occupied, the countdown stops and waits, and when the medium becomes idle, the remaining countdown is resumed.
  • STA3 when a packet to be transmitted reaches the MAC of STA3, STA3 can check that the medium is idle for DIFS and transmit the frame right away. The remaining STAs monitor whether the medium is occupied/busy and wait. In the meantime, data to be transmitted may also occur in each of STA1, STA2, and STA5, and each STA can perform a countdown of the backoff slot according to a random backoff count value selected by each STA after waiting for DIFS when the medium is monitored as idle. Assume that STA2 selects the smallest backoff count value and STA1 selects the largest backoff count value.
  • this example shows a case where the remaining backoff time of STA5 is shorter than the remaining backoff time of STA1 when STA2 finishes the backoff count and starts frame transmission.
  • STA1 and STA5 briefly stop the countdown and wait while STA2 occupies the medium.
  • STA1 and STA5 resume the stopped backoff count after waiting for DIFS. That is, they can start frame transmission after counting down the remaining backoff slots by the remaining backoff time. Since the remaining backoff time of STA5 is shorter than that of STA1, STA5 starts frame transmission. While STA2 occupies the medium, STA4 may also have data to transmit.
  • STA4 From STA4's perspective, when the medium becomes idle, it waits for DIFS, performs a countdown according to the random backoff count value it selected, and starts frame transmission.
  • the remaining backoff time of STA5 coincidentally matches the random backoff count value of STA4, and in this case, a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 will receive an ACK, resulting in a failure in data transmission. In this case, STA4 and STA5 can select a random backoff count value and perform a countdown after doubling the CW value.
  • STA1 waits while the medium is occupied by transmissions from STA4 and STA5, and when the medium becomes idle, it waits for DIFS, and then starts transmitting frames after the remaining backoff time has elapsed.
  • a data frame is a frame used for transmitting data forwarded to a higher layer, and can be transmitted after a backoff performed after DIFS elapses from when the medium becomes idle.
  • a management frame is a frame used for exchanging management information that is not forwarded to a higher layer, and is transmitted after a backoff performed after an IFS such as DIFS or PIFS (Point coordination function IFS) elapses.
  • Subtype frames of the management frame include a beacon, an association request/response, a re-association request/response, a probe request/response, and an authentication request/response.
  • a control frame is a frame used to control access to the medium.
  • the subtype frames of the control frame include RTS (Request-To-Send), CTS (Clear-To-Send), ACK (Acknowledgment), PS-Poll (Power Save-Poll), Block ACK (BlockAck), Block ACK Request (BlockACKReq), NDP notification (null data packet announcement), and Trigger. If the control frame is not a response frame to the previous frame, it is transmitted after the backoff performed after the DIFS (DIFS), and if it is a response frame to the previous frame, it is transmitted without the backoff performed after the SIFS (short IFS).
  • DIFS DIFS
  • SIFS short IFS
  • a QoS (Quality of Service) STA can transmit a frame after a backoff performed after the AIFS (arbitration IFS) for the access category (AC) to which the frame belongs, that is, AIFS[i] (where i is a value determined by the AC), has elapsed.
  • AIFS aromatic IFS
  • the frames for which AIFS[i] can be used can be data frames, management frames, and also control frames that are not response frames.
  • FIG. 5 is a diagram for explaining a CSMA/CA-based frame transmission operation to which the present disclosure can be applied.
  • the CSMA/CA mechanism includes virtual carrier sensing in addition to physical carrier sensing in which an STA directly senses the medium.
  • Virtual carrier sensing is intended to complement problems that may occur in medium access, such as the hidden node problem.
  • the MAC of the STA may utilize a Network Allocation Vector (NAV).
  • NAV Network Allocation Vector
  • the NAV is a value that indicates to other STAs the remaining time until the medium becomes available, by an STA that is currently using or has the right to use the medium. Therefore, the value set as NAV corresponds to the period during which the medium is scheduled to be used by the STA transmitting the corresponding frame, and the STA that receives the NAV value is prohibited from accessing the medium during the corresponding period.
  • the NAV may be set based on the value of the "duration" field of the MAC header of the frame.
  • STA1 wants to transmit data to STA2, and STA3 is in a position to overhear part or all of the frames transmitted and received between STA1 and STA2.
  • a mechanism using RTS/CTS frames may be applied.
  • STA3 may determine that the carrier sensing result of the medium is idle. That is, STA1 may correspond to a hidden node to STA3.
  • STA2 may transmitting, STA3 may determine that the carrier sensing result of the medium is idle. That is, STA2 may correspond to a hidden node to STA3.
  • STAs outside the transmission range of either STA1 or STA2, or STAs outside the carrier sensing range for transmission from STA1 or STA3 may not attempt to occupy the channel during data transmission and reception between STA1 and STA2.
  • STA1 can determine whether a channel is occupied through carrier sensing.
  • STA1 can determine a channel occupied idle state based on energy magnitude or signal correlation detected in the channel.
  • STA1 can determine a channel occupied state using a network allocation vector (NAV) timer.
  • NAV network allocation vector
  • STA1 can transmit an RTS frame to STA2 after performing a backoff if the channel is idle during DIFS.
  • STA2 can transmit a CTS frame, which is a response to the RTS frame, to STA1 after SIFS if it receives the RTS frame.
  • STA3 can set a NAV timer for the subsequently transmitted frame transmission period (e.g., SIFS + CTS frame + SIFS + data frame + SIFS + ACK frame) using the duration information included in the RTS frame.
  • STA3 can set a NAV timer for the subsequently transmitted frame transmission period (e.g., SIFS + data frame + SIFS + ACK frame) using the duration information included in the CTS frame.
  • STA3 can overhear one or more of the RTS or CTS frames from one or more of STA1 or STA2, it can set a NAV accordingly.
  • STA3 can update the NAV timer using the duration information contained in the new frame if it receives a new frame before the NAV timer expires. STA3 does not attempt to access the channel until the NAV timer expires.
  • STA1 receives a CTS frame from STA2, it can transmit a data frame to STA2 after SIFS from the time when reception of the CTS frame is completed. If STA2 successfully receives the data frame, it can transmit an ACK frame in response to the data frame to STA1 after SIFS.
  • STA3 can determine whether the channel is in use through carrier sensing if the NAV timer expires. If STA3 determines that the channel is not in use by other terminals during DIFS after the expiration of the NAV timer, it can attempt channel access after a contention window (CW) following a random backoff has elapsed.
  • CW contention window
  • FIG. 6 is a drawing for explaining an example of a frame structure used in a wireless LAN system to which the present disclosure can be applied.
  • the PHY layer can prepare an MPDU (MAC PDU) to be transmitted by an instruction or primitive (meaning a set of instructions or parameters) from the MAC layer. For example, when a command requesting the start of transmission of the PHY layer is received from the MAC layer, the PHY layer can switch to transmission mode and transmit information (e.g., data) provided from the MAC layer in the form of a frame. In addition, when the PHY layer detects a valid preamble of the received frame, it monitors the header of the preamble and sends a command to the MAC layer notifying the start of reception of the PHY layer.
  • MPDU MPDU
  • an instruction or primitive meaning a set of instructions or parameters
  • PPDU PHY layer Protocol Data Unit
  • a basic PPDU may include a Short Training Field (STF), a Long Training Field (LTF), a SIGNAL (SIG) field, and a Data field.
  • STF Short Training Field
  • LTF Long Training Field
  • SIG SIGNAL
  • PPDU format may consist of only a Legacy-STF (L-STF), a Legacy-LTF (L-LTF), a Legacy-SIG (Legacy-SIG) field, and a Data field.
  • RL-SIG RL-SIG
  • U-SIG non-legacy SIG field
  • non-legacy STF non-legacy LTF
  • xx-SIG xx-SIG
  • xx-LTF e.g., xx represents HT, VHT, HE, EHT, etc.
  • STF is a signal for signal detection, AGC (Automatic Gain Control), diversity selection, precise time synchronization, etc.
  • LTF is a signal for channel estimation, frequency error estimation, etc. STF and LTF can be said to be signals for OFDM physical layer synchronization and channel estimation.
  • the SIG field may include various information related to PPDU transmission and reception.
  • the L-SIG field may consist of 24 bits and may include a 4-bit Rate field, a 1-bit Reserved bit, a 12-bit Length field, a 1-bit Parity field, and a 6-bit Tail field.
  • the RATE field may include information about a modulation and coding rate of data.
  • the 12-bit Length field may include information about the length or time duration of the PPDU.
  • the value of the 12-bit Length field may be determined based on the type of the PPDU. For example, for a non-HT, HT, VHT, or EHT PPDU, the value of the Length field may be determined as a multiple of 3.
  • the value of the Length field can be determined as a multiple of 3 + 1 or a multiple of 3 + 2.
  • the data field may include a SERVICE field, a Physical layer Service Data Unit (PSDU), a PPDU TAIL bit, and, if necessary, padding bits.
  • PSDU Physical layer Service Data Unit
  • PPDU TAIL bit may be used to return the encoder to the 0 state.
  • padding bit may be used to adjust the length of the data field to a predetermined unit.
  • MAC PDU is defined according to various MAC frame formats, and the basic MAC frame consists of a MAC header, frame body, and FCS (Frame Check Sequence).
  • MAC frame consists of MAC PDU and can be transmitted/received through PSDU of the data part of PPDU format.
  • the MAC header includes a Frame Control field, a Duration/ID field, an Address field, etc.
  • the Frame Control field may include control information required for frame transmission/reception.
  • the Duration/ID field may be set to a time for transmitting the corresponding frame, etc.
  • the Address subfields may indicate a receiver address, a transmitter address, a destination address, and a source address of the frame, and some Address subfields may be omitted. For specific details of each subfield of the MAC header, including the Sequence Control, QoS Control, and HT Control subfields, refer to the IEEE 802.11 standard document.
  • Null-Data PPDU (NDP) format refers to a PPDU format that does not include a data field. That is, NDP refers to a frame format that includes a PPDU preamble (i.e., L-STF, L-LTF, L-SIG fields, and additionally, non-legacy SIG, non-legacy STF, non-legacy LTF if present) in a general PPDU format, and does not include the remaining part (i.e., data field).
  • a PPDU preamble i.e., L-STF, L-LTF, L-SIG fields, and additionally, non-legacy SIG, non-legacy STF, non-legacy LTF if present
  • FIG. 7 is a diagram illustrating examples of PPDUs defined in the IEEE 802.11 standard to which the present disclosure can be applied.
  • the basic PPDU format (IEEE 802.11a/g) includes L-LTF, L-STF, L-SIG, and Data fields.
  • the basic PPDU format can also be called a non-HT PPDU format (Fig. 7(a)).
  • the HT PPDU format (IEEE 802.11n) additionally includes HT-SIG, HT-STF, and HT-LFT(s) fields in the basic PPDU format.
  • the HT PPDU format illustrated in Fig. 7(b) may be referred to as an HT-mixed format.
  • an HT-greenfield format PPDU may be defined, which corresponds to a format that does not include L-STF, L-LTF, and L-SIG, and consists of HT-GF-STF, HT-LTF1, HT-SIG, one or more HT-LTF, and Data fields (not illustrated).
  • VHT PPDU format includes VHT SIG-A, VHT-STF, VHT-LTF, and VHT-SIG-B fields in addition to the basic PPDU format (Fig. 7(c)).
  • HE PPDU format (IEEE 802.11ax) additionally includes RL-SIG (Repeated L-SIG), HE-SIG-A, HE-SIG-B, HE-STF, HE-LTF(s), and PE (Packet Extension) fields in the basic PPDU format (Fig. 7(d)).
  • RL-SIG Repeated L-SIG
  • HE-SIG-A HE-SIG-B
  • HE-STF HE-LTF(s)
  • PE Packet Extension
  • some fields may be excluded or their lengths may vary.
  • the HE-SIG-B field is included in a HE PPDU format for multi-users (MUs), and the HE PPDU format for single users (SUs) does not include the HE-SIG-B.
  • a HE trigger-based (TB) PPDU format does not include the HE-SIG-B, and the length of the HE-STF field may vary to 8us.
  • a HE ER (Extended Range) SU PPDU format does not include the HE-SIG-B field, and the length of the HE-SIG-A field may vary to 16us.
  • RL-SIG can be configured identically to L-SIG. The receiving STA can know that the received PPDU is a HE PPDU or an EHT PPDU, described later, based on the presence of RL-SIG.
  • the EHT PPDU format may include the EHT MU (multi-user) PPDU of Fig. 7(e) and the EHT TB (trigger-based) PPDU of Fig. 7(f).
  • the EHT PPDU format is similar to the HE PPDU format in that it includes an RL-SIG following an L-SIG, but it may include a U (universal)-SIG, an EHT-SIG, an EHT-STF, and an EHT-LTF following the RL-SIG.
  • the EHT MU PPDU in Fig. 7(e) corresponds to a PPDU that carries one or more data (or PSDU) for one or more users. That is, the EHT MU PPDU can be used for both SU transmission and MU transmission.
  • the EHT MU PPDU can correspond to a PPDU for one receiving STA or multiple receiving STAs.
  • the EHT TB PPDU of Fig. 7(f) omits EHT-SIG compared to the EHT MU PPDU.
  • An STA that has received a trigger for UL MU transmission e.g., a trigger frame or TRS (triggered response scheduling)
  • TRS triggered response scheduling
  • the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG (Universal SIGNAL), and EHT-SIG fields can be encoded and modulated and mapped based on a predetermined subcarrier frequency interval (e.g., 312.5 kHz) so that even legacy STAs can attempt to demodulate and decode them. These can be referred to as pre-EHT modulated fields.
  • the EHT-STF, EHT-LTF, Data, and PE fields can be encoded and modulated and mapped based on a predetermined subcarrier frequency interval (e.g., 78.125 kHz) so that they can be demodulated and decoded by an STA that successfully decodes a non-legacy SIG (e.g., U-SIG and/or EHT-SIG) and obtains the information included in the corresponding fields.
  • a predetermined subcarrier frequency interval e.g., 78.125 kHz
  • a non-legacy SIG e.g., U-SIG and/or EHT-SIG
  • EHT modulated fields e.g., U-SIG and/or EHT-SIG
  • the L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, and HE-SIG-B fields may be referred to as pre-HE modulation fields, and the HE-STF, HE-LTF, Data, and PE fields may be referred to as HE modulation fields.
  • the L-STF, L-LTF, L-SIG, and VHT-SIG-A fields may be referred to as pre-VHT modulation fields
  • the VHT STF, VHT-LTF, VHT-SIG-B, and Data fields may be referred to as VHT modulation fields.
  • the U-SIG included in the EHT PPDU format of Fig. 7 can be configured based on, for example, two symbols (e.g., two consecutive OFDM symbols).
  • Each symbol (e.g., OFDM symbol) for the U-SIG can have a duration of 4us, and the U-SIG can have a total duration of 8us.
  • Each symbol of the U-SIG can be used to transmit 26 bits of information.
  • each symbol of the U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.
  • U-SIG can be configured in 20MHz units. For example, when an 80MHz PPDU is configured, the same U-SIG can be replicated in 20MHz units. That is, four identical U-SIGs can be included in an 80MHz PPDU. When the bandwidth exceeds 80MHz, for example, for a 160MHz PPDU, the U-SIG of the first 80MHz unit and the U-SIG of the second 80MHz unit can be different.
  • a uncoded bits can be transmitted, and a first symbol of U-SIG (e.g., U-SIG-1 symbol) can transmit the first X bits of information out of the total A bits of information, and a second symbol of U-SIG (e.g., U-SIG-2 symbol) can transmit the remaining Y bits of information out of the total A bits of information.
  • the A bits of information e.g., 52 uncoded bits
  • the tail field can be used to terminate the trellis of the convolutional decoder and can be set to 0, for example.
  • the A bit information transmitted by U-SIG can be divided into version-independent bits and version-dependent bits.
  • U-SIG may be included in a new PPDU format (e.g., UHR PPDU format) not shown in FIG. 7, and in the format of the U-SIG field included in the EHT PPDU format and the format of the U-SIG field included in the UHR PPDU format, the version-independent bits may be the same, and some or all of the version-dependent bits may be different.
  • the size of the version-independent bits of U-SIG can be fixed or variable.
  • the version-independent bits can be assigned only to U-SIG-1 symbols, or to both U-SIG-1 symbols and U-SIG-2 symbols.
  • the version-independent bits and the version-dependent bits can be called by various names, such as the first control bit and the second control bit.
  • the version-independent bits of U-SIG may include a 3-bit PHY version identifier, which may indicate the PHY version (e.g., EHT, UHR, etc.) of the transmitted and received PPDU.
  • the version-independent bits of U-SIG may include a 1-bit UL/DL flag field. The first value of the 1-bit UL/DL flag field relates to UL communication, and the second value of the UL/DL flag field relates to DL communication.
  • the version-independent bits of U-SIG may include information about the length of a TXOP (transmission opportunity) and information about a BSS color ID.
  • the version-dependent bits of the U-SIG may contain information that directly or indirectly indicates the type of the PPDU (e.g., SU PPDU, MU PPDU, TB PPDU, etc.).
  • the U-SIG may further include information about bandwidth, information about an MCS technique applied to a non-legacy SIG (e.g., EHT-SIG or UHR-SIG, etc.), information indicating whether a dual carrier modulation (DCM) 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 non-legacy SIG, information about the number of symbols used for the non-legacy SIG, information about whether the non-legacy SIG is generated over the entire band, etc.
  • DCM dual carrier modulation
  • 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.).
  • 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 cyclic prefix (CP) length e.g., EHT-LTF/EHT-STF or UHR-LTF/UHR-STF, etc.
  • information about the length of the non-legacy LTF and the cyclic prefix (CP) length e.g., information about the guard interval (GI) applied to the non-legacy LTF
  • information about preamble puncturing applicable to the PPDU e.g., information about resource unit (RU) allocation, etc.
  • RU resource unit
  • Preamble puncturing may mean transmission of a PPDU in which no signal is present in one or more frequency units within the bandwidth of the PPDU.
  • the size of the frequency unit (or the resolution of the preamble puncturing) may be defined as 20 MHz, 40 MHz, etc.
  • preamble puncturing may be applied to a PPDU bandwidth greater than a predetermined size.
  • non-legacy SIGs such as HE-SIG-B, EHT-SIG, etc. may include control information for the receiving STA.
  • the non-legacy SIG may be transmitted through at least one symbol, and one symbol may have a length of 4 us.
  • Information about the number of symbols used for 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, EHT-SIG, etc.
  • HE-SIG-B may contain common fields and user-specific fields. Common fields and user-specific fields may be coded separately.
  • the common field may be omitted.
  • the common field may be omitted, and multiple STAs may receive a PPDU (e.g., a data field of a PPDU) over the same frequency band.
  • a PPDU e.g., a data field of a PPDU
  • multiple users may receive a PPDU (e.g., a data field of a PPDU) over different frequency bands.
  • the number of user-specific fields can be determined based on the number of users.
  • One user block field can include at most two user fields.
  • Each user field can be associated with an MU-MIMO allocation or associated with a non-MU-MIMO allocation.
  • the common field may include CRC bits and Tail bits, the length of the CRC bits may be determined as 4 bits, the length of the Tail bits may be determined as 6 bits and may be set to 000000.
  • the common field may include RU allocation information.
  • the RU allocation information may include information about the location of RUs to which multiple users (i.e., multiple receiving STAs) are allocated.
  • An RU may include multiple subcarriers (or tones). An RU may be used when transmitting signals to multiple STAs based on the OFDMA technique. An RU may also be defined when transmitting signals to one STA. Resources may be allocated in RU units for non-legacy STFs, non-legacy LTFs, and Data fields.
  • an applicable size of RU can be defined.
  • the RU may be defined identically or differently for the applicable PPDU format (e.g., HE PPDU, EHT PPDU, UHR PPDU, etc.).
  • the RU arrangements of HE PPDU and EHT PPDU may be different.
  • the applicable RU size, RU number, RU position, DC (direct current) subcarrier position and number, null subcarrier position and number, guard subcarrier position and number, etc. for each PPDU bandwidth can be referred to as a tone plan.
  • a tone plan for a wide bandwidth can be defined in the form of multiple repetitions of a tone plan for a low bandwidth.
  • RUs of different sizes can be defined, such as 26-tone RU, 52-tone RU, 106-tone RU, 242-tone RU, 484-tone RU, 996-tone RU, 2 ⁇ 996-tone RU, 4 ⁇ 996-tone RU, etc.
  • a multiple RU is distinct from multiple individual RUs and corresponds to a group of subcarriers consisting of multiple RUs.
  • one MRU can 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.
  • multiple RUs constituting one MRU may or may not be consecutive in the frequency domain.
  • the specific size of the RU may be reduced or expanded. Therefore, the specific size of each RU (i.e., the number of corresponding tones) in the present disclosure is not limited and is exemplary. In addition, within a given bandwidth (e.g., 20, 40, 80, 160, 320 MHz, ...) in the present disclosure, the number of RUs may vary depending on the RU size.
  • each field in the PPDU formats of FIG. 7 are exemplary, and the scope of the present disclosure is not limited by the names.
  • the examples of the present disclosure can be applied not only to the PPDU format exemplified in FIG. 7, but also to a new PPDU format in which some fields are excluded and/or some fields are added based on the PPDU formats of FIG. 7.
  • MAP multi-access point
  • MAP operation can be defined as an operation between a master AP (or sharing AP) and a slave AP (or shared AP).
  • the master AP initiates and controls MAP operations for transmission and reception between multiple APs.
  • the master AP groups slave APs and manages links with slave APs so that information can be shared between the slave APs.
  • the master AP manages information about the BSSs that the slave APs are configuring and information about STAs that have formed associations with the BSSs.
  • Slave APs can associate with the master AP and share control information, management information, and data traffic with each other. Slave APs perform the same basic functions of APs that can establish a BSS in a wireless LAN.
  • an STA can associate with a slave AP or a master AP and form a BSS.
  • the master AP and slave AP can perform direct transmission and reception with each other.
  • the master AP and STA may not perform direct transmission and reception with each other.
  • the slave AP e.g., the slave AP associated with the STA
  • the slave AP can perform direct transmission and reception with the STA.
  • One of the slave APs can become the master AP.
  • MAP operation is a technique in which one or more APs transmit and receive information to one or more STAs.
  • coordinated-time division multiple access C-TDMA
  • C-OFDMA coordinated-orthogonal frequency division multiple access
  • C-SR coordinated-spatial reuse
  • C-BF coordinated beamforming
  • C-BF coordinated beamforming
  • joint beamforming techniques that cooperatively perform simultaneous transmission and reception can also be applied to the MAP operation.
  • FIG. 8 is a diagram for explaining various transmission and reception techniques in a MAP environment to which the present disclosure can be applied.
  • a BSS AP transmits to a BSS STA
  • it can be called STX (single transmission).
  • STX single transmission
  • the performance of transmission and reception for users/STAs located at the cell edge is reduced due to interference with adjacent APs.
  • Fig. 8(a) when AP1 and AP2 transmit to STA1 and STA2, respectively, at the same time in the same frequency bandwidth, a collision may occur on the wireless medium.
  • MAP performance can be improved by reducing inter-symbol interference (ISI) through cooperation between neighboring APs, or by performing joint transmissions.
  • ISI inter-symbol interference
  • interference can be avoided by having AP1 transmit to STA1 in the first bandwidth and AP2 transmit to STA2 in the second bandwidth at the same time.
  • the example of Fig. 8(c) shows a cooperative beamforming or nulling technique in which AP1 nulls interference to AP2 and/or STA2 while transmitting to STA1, and AP2 nulls interference to AP1 and/or STA1 while transmitting to STA2.
  • JTX Joint transmission
  • JRX joint reception
  • multi-AP operation is assumed to be performed as follows.
  • Step 1 Allocate resource areas to each AP through a trigger frame from the master AP (i.e., AP-to-AP trigger frame, or master trigger frame).
  • master AP i.e., AP-to-AP trigger frame, or master trigger frame.
  • Step 2 Each AP performs DL (i.e., from AP to STA) data transmission in the resource area allocated to it, or transmits a trigger frame (i.e., AP-to-STA trigger frame) for UL (i.e., from STA to AP) data transmission in the resource area allocated to it.
  • DL i.e., from AP to STA
  • UL i.e., from STA to AP
  • Step 3 STA transmits a response to DL data or transmits UL data (e.g., via TB PPDU).
  • the resources distributed between APs are frequency resources, it may correspond to the C-OFDMA method, if it is time resources, it may correspond to the C-TDMA technique, and if it is space resources (or beams), it may correspond to the CBF method.
  • the C-OFDMA technique that is, multi-AP operations are performed using resources distinguished in the frequency domain
  • the scope of the present disclosure is not limited thereto, and may additionally or alternatively include multi-AP operations using resources distinguished in other domains (e.g., the time domain and/or the space domain).
  • TWT Target wake time
  • TWT target wake time
  • TWT is a PS (Power Saving) technology that can improve the energy efficiency of non-AP STAs by defining a Service Period (SP) between APs and non-AP STAs and sharing information about the SP to reduce contention of the medium.
  • SP Service Period
  • an STA that performs Request/Suggest/Demand, etc. may be called a TWT Requesting STA.
  • an AP that responds to the request by accepting/rejecting it, etc. may be called a TWT Responding STA.
  • the Setup phase may include a process of determining/defining a TWT request from an STA to an AP, the type of TWT operation to be performed, and the type of frame to be transmitted and received. TWT operations can be divided into individual TWT and broadcast TWT.
  • FIG. 9 is a diagram illustrating an example of an individual TWT operation to which the present disclosure can be applied.
  • Individual TWT is a mechanism in which an AP and a non-AP STA negotiate the awake/doze status of a non-AP STA by sending and receiving TWT Request/Response frames, and then exchange data.
  • the AP and STA1 can form a trigger-enabled TWT agreement through a TWT request frame and a TWT response frame.
  • the method used by STA1 is a solicited TWT method, in which STA1 transmits a TWT request frame to the AP, and STA1 receives information for TWT operation from the AP through a TWT response frame.
  • STA2 performing the unsolicited TWT mode can receive information about trigger-enabled TWT agreement setup from the AP through the unsolicited TWT response. Specifically, STA2 can calculate the next TWT by adding a specific number to the current TWT value.
  • the AP can transmit a trigger frame to the STAs.
  • the trigger frame can inform the STAs that the AP has buffered data.
  • STA1 can inform the AP of its awake state by transmitting a PS-Poll frame.
  • STA2 can inform the AP of its activated state by transmitting a QoS Null frame.
  • the data frames transmitted by STA1 and STA2 can be frames in a TB PPDU format.
  • the AP which has checked the status of STA1 and STA2, can transmit DL MU PPDU to the activated STAs.
  • STA1 and STA2 can transition to the doze state.
  • FIG. 10 is a diagram illustrating an example of a broadcast TWT operation to which the present disclosure can be applied.
  • Broadcast TWT is a TWT in which a non-AP STA (or TWT scheduling STA) obtains information about a target beacon transmission time (TBTT) and a listen interval by transmitting and receiving TWT request/response frames with an AP (or TWT scheduled STA).
  • TBTT target beacon transmission time
  • AP or TWT scheduled STA
  • a negotiation operation for TBTT may be performed.
  • the AP can define a frame to include TWT scheduling information through a beacon frame.
  • STA1 performs a requested TWT operation and STA2 performs an unsolicited TWT operation.
  • the AP can check the awake status of STAs through a trigger transmitted by itself and then transmit a DL MU PPDU. This may be the same as the process of an individual TWT.
  • a trigger-enabled TWT SP including a beacon frame may be repeated several times at a regular cycle.
  • Transmission of TWT information can be accomplished through a TWT information frame and a TWT information element.
  • Latency-sensitive traffic includes real-time audio/video transmission, and the need to support this in a wireless environment has increased as multimedia devices have spread.
  • latency may mean latency defined in the IEEE 802.11 series standards. For example, it may mean the time from when a frame to be transmitted enters the queue of the MAC layer of the transmitting STA, until the transmission of the transmitting STA is successfully completed in the PHY layer, and the transmitting STA receives ACK/block ACK, etc. from the receiving STA, and until the corresponding frame is deleted from the MAC layer queue of the transmitting STA.
  • a non-AP STA that supports transmission of latency sensitive data may be called a low latency STA.
  • data other than latency sensitive data may be called regular data.
  • Restricted TWT can support securing data transmission possibility for low-latency STAs preferentially over other STAs by having an AP set a special broadcast TWT for the low-latency STAs transmitting latency-sensitive data.
  • the STA can establish membership for one or more r-TWT schedules with respect to the AP.
  • the r-TWT agreement can be established by the same process as the broadcast TWT agreement, and a broadcast TWT element therefor can be defined to include an r-TWT parameter set field.
  • the r-TWT parameter set can refer to a specific broadcast TWT parameter set field that is distinguished from other broadcast TWT parameter set fields. That is, the r-TWT parameter set field can correspond to a special case of the broadcast TWT parameter set field.
  • the AP can announce an r-TWT SP.
  • the TXOP must end before the start time of the r-TWT SP advertised by the associated AP. Accordingly, the STA related to the r-TWT (i.e., the low-latency STA) can perform traffic transmission and reception with priority over the other STAs within the r-TWT SP.
  • the STA related to the r-TWT i.e., the low-latency STA
  • a low-latency STA associated with a specific r-TWT as described above is referred to as a member r-TWT scheduled STA, and other STAs are referred to as non-member STAs.
  • a non-member STA may be an STA that has the capability to support an r-TWT operation but is not a member of any r-TWT, or an STA that supports an r-TWT operation but is a member of another r-TWT, or an STA that does not have the capability to support an r-TWT operation.
  • An STA e.g., a low-latency STA
  • supporting limited SP (or r-TWT SP) operation of broadcast TWT may inform the AP that it needs to transmit latency sensitive data based on r-TWT operation. If the AP supports the r-TWT operation/mode, the AP may transmit a frame including scheduling information of TWTs requested by each STA to the low-latency STA and other STA(s).
  • non-AP STAs may obtain r-TWT related information from the AP through a beacon frame, a probe response frame, a (re)association response frame, or other frames in a not-yet-defined format (e.g., frames for broadcast, advertisement, or announcement purposes).
  • a beacon frame e.g., a probe response frame
  • a (re)association response frame e.g., a probe response frame
  • other frames in a not-yet-defined format e.g., frames for broadcast, advertisement, or announcement purposes.
  • a separate TXOP (i.e., access of other STAs is restricted) can be secured within the r-TWT SP by using NAV such as (MU) RTS/CTS or CTS-to-self, or a quiet interval.
  • NAV such as (MU) RTS/CTS or CTS-to-self
  • a quiet interval e.g., a quiet interval.
  • a silent interval may be indicated by a quiet element or a quiet channel element. Basically, an STA receiving a silent element or a quiet channel element may not perform transmission (or channel access) on the corresponding channel during the indicated silent interval.
  • FIG. 11 is a diagram showing an exemplary format of a silence element and an exemplary format of a silence channel element to which the present disclosure can be applied.
  • Fig. 11(a) shows an exemplary format of a silence element.
  • a silence element may define an interval during which no transmission is performed on the current channel.
  • the interval may be used to assist in performing channel measurements (or channel tests) without interference from other STAs within the BSS.
  • the Element ID field may have a value corresponding to the silence element (e.g., 40).
  • the Length field may have a value corresponding to the length of the following fields (e.g., 6 octets).
  • the quiet count field can have a value corresponding to the number of TBTTs until the beacon interval at which the next silent interval begins.
  • the value 0 of this field can be reserved.
  • the quiet period field may have a value corresponding to the number of beacon intervals between the start points of regularly scheduled silent intervals defined by the corresponding silence element.
  • a value of the quiet period field of 0 may indicate that no periodic silent intervals are defined.
  • the quiet duration field can have a value expressing the duration of the silent interval in time units (TUs).
  • TUs time units
  • 1 TU can correspond to 1024 microseconds (us).
  • the quiet offset field may have a value representing the offset in TU units from the TBTT specified by the silence count field to the start of the silence interval.
  • the value of the quiet offset field may be less than one beacon interval.
  • the silence element may be included in a beacon frame, probe response frame, etc.
  • an AP may schedule a silence interval by transmitting a beacon/probe response frame that includes a silence element. Multiple independent silence intervals may also be scheduled.
  • An STA may set a NAV (on the silent channel) for the length of a silence interval.
  • Fig. 11(b) shows an exemplary format of a silent channel element.
  • the Silence Channel element may be used to indicate that a secondary channel (e.g., the secondary 80 MHz channel of a VHT BSS) is to be silenced during the silence interval, and also, in an infrastructure BSS, to indicate that a primary channel (e.g., the primary 80 MHz channel of a VHT BSS) may be used during the silence interval.
  • the silence interval may be established using the Silence Element, or, in an infrastructure BSS, using the Silence Channel element when the value of the AP Silence Mode field is 1.
  • Silent channel elements may be included in beacon frames, probe response frames, etc.
  • the AP quiet mode field may specify the STA behavior in the infrastructure BSS during the quiet interval. If communication to the AP is allowed within the primary 80MHz channel (during the quiet interval), the AP quiet mode field may have a value of 1. Otherwise, the AP quiet mode field may have a value of 0.
  • the Silence Channel element may include a Silence Count field, a Silence Period field, a Silence Duration field, and a Silence Offset field. Otherwise, these fields may not be included in the Silence Channel element.
  • the silence count field, silence period field, silence duration field, and silence offset field in the silence channel element are identical to the corresponding fields in the silence element field, so redundant description is omitted.
  • the silent interval may be scheduled with respect to the r-TWT SP.
  • an AP supporting r-TWT e.g., an EHT AP or an AP supporting an EHT successor (e.g., UHR) standard
  • the overlapping silent interval if scheduled, may be required to have a duration of 1 TU and to start at the same point in time as the start of the corresponding r-TWT SP.
  • Overlapping silence intervals can be configured by including one or more silence elements in beacon frames, probe response frames, etc. transmitted by an AP supporting r-TWT (e.g., an EHT AP).
  • an AP supporting r-TWT e.g., an EHT AP.
  • Non-AP EHT STAs may behave as if no overlapping silence intervals exist.
  • the AP may use silent intervals for channel measurements/testing by managing or avoiding overlapping scheduled silent intervals with r-TWT SPs.
  • FIG. 12 is a diagram exemplarily showing STAs in an OBSS to which the present disclosure can be applied.
  • a range of an OBSS may be formed.
  • a range in which AP1 can be signaled e.g., a range corresponding to BSS1
  • a range in which AP2 can be signaled e.g., a range corresponding to BSS2
  • the STA at that location may receive beacon frames from APs with which it has formed an association as well as beacon frames from APs with which it has not formed an association.
  • STA1-2 may receive a beacon frame from AP1 with which it has formed an association, and may also receive (i.e., overhear) a beacon frame from AP2 with which it has not formed an association.
  • STA2-4 can receive a beacon frame from AP2, which it is associated with, and can also receive (i.e., overhear) a beacon frame from AP1, which it is not associated with.
  • AP1 and AP2 may correspond to slave APs (or shared APs) belonging to a MAP having the same master AP (or shared AP).
  • a beacon frame may include restricted-TWT (R-TWT) scheduling information that an AP assigns to STAs associated with it, and STAs receiving the R-TWT scheduling information are required to protect R-TWT SPs of which they are not a member (e.g., terminating the TXOP of the STA if it is in progress before the start time of the R-TWT SP, as described above). That is, an STA receiving a beacon frame including R-TWT scheduling information may mean that it is present in a position to protect the corresponding R-TWT SP.
  • R-TWT restricted-TWT
  • an STA receives R-TWT scheduling information advertised by an AP to which it is not associated (or a neighboring AP), it is not yet defined whether it should protect the corresponding R-TWT SP or transmit/receive low-latency traffic/data during the corresponding R-TWT SP.
  • an operation of an STA e.g., STA1-2
  • R-TWT scheduling information of an unassociated (or neighboring) AP e.g., AP2
  • an R-TWT SP scheduled by another AP is referred to as an OBSS R-TWT SP in order to distinguish it from an R-TWT SP scheduled by an associated AP.
  • OBSS R-TWT SP e.g., an unassociated AP or a neighboring AP
  • the scope of the present disclosure is not limited by the name OBSS R-TWT.
  • one of the two APs associated with an OBSS can obtain R-TWT (i.e., OBSS R-TWT) scheduling information of the other AP by one or more of the following methods.
  • R-TWT i.e., OBSS R-TWT
  • an AP may transmit its R-TWT scheduling information to one or more other APs, or receive R-TWT scheduling information of each of one or more other APs from the one or more other APs. For example, this may work in cases where the APs are not located within the same ESS.
  • R-TWT scheduling information may be shared between APs that are not capable of direct data transmission and reception through a third-party management entity. For example, this may be the case when the APs are located within the same ESS and/or when the APs are slave APs (or shared APs) having the same master AP (or shared AP).
  • the master AP may act as the third-party management entity.
  • an STA that overhears a beacon frame from another AP may forward relevant information to the AP with which it is associated. For example, the STA may forward information contained in the overheard beacon frame to the associated AP, or may decode the overheard beacon frame and forward OBSS R-TWT relevant information to the associated AP.
  • the STA may support a wireless LAN technology for which the R-TWT capability itself is not defined, or may support a wireless LAN technology for which the R-TWT capability is defined.
  • a pre-EHT STA type that does not support the EHT technology may be referred to as a legacy STA type, and such a type of STA may not support the R-TWT operation itself.
  • an EHT STA type that supports the EHT technology for which the R-TWT capability is defined may support the R-TWT operation depending on whether it has the R-TWT capability. Even an EHT STA type that has the R-TWT capability may not support the OBSS R-TWT operation itself.
  • a STA e.g., a UHR STA
  • a new wireless LAN technology e.g., a UHR technology
  • OBSS R-TWT or enhanced R-TWT
  • OBSS R-TWT operation depending on whether it has the OBSS R-TWT (or enhanced R-TWT) capability.
  • UHR STA type that does not have the R-TWT capability (and the OBSS R-TWT capability)
  • a UHR STA type that has only the R-TWT capability without restricting whether such type of STA can interpret OBSS R-TWT (or enhanced R-TWT) related information
  • a UHR STA type that has OBSS R-TWT (or enhanced R-TWT) capability it is assumed that such type of STA can perform OBSS R-TWT SP protection operation).
  • overlapping silence interval, TXOP for R-TWT SP, and backoff procedure rules can be extended and applied.
  • a TXOP in progress before the start of the OBSS R-TWT SP can be terminated.
  • the STA can select a random backoff count to defer transmission.
  • a silence interval overlapping with the OBSS R-TWT SP can be set.
  • the OBSS R-TWT SP protection operation can be applied as follows.
  • OBSS R-TWT SP can be protected through overlapping silence intervals.
  • OBSS R-TWT SP can be protected through overlapping silence intervals.
  • an AP i.e., a BSS AP
  • an STA associated with an R-TWT SP i.e., an OBSS R-TWT SP
  • the OBSS R-TWT SP can be protected by terminating an ongoing TXOP before the OBSS R-TWT SP starts based on TXOP and backoff procedure rules for the R-TWT SP.
  • the associated AP can configure the OBSS R-TWT SP information in the same manner as the R-TWT SP information allocated by itself.
  • An STA receiving such an R-TWT SP may not distinguish between the OBSS R-TWT SP and the R-TWT SP.
  • the broadcast TWT ID corresponding to the R-TWT SP allocated by the associated AP and the broadcast TWT ID corresponding to the OBSS R-TWT SP may not overlap. Accordingly, associated STAs that have been notified of multiple R-TWT information including OBSS R-TWT information can interpret the OBSS R-TWT SP as an R-TWT SP allocated to another R-TWT member to which they do not belong.
  • an AP i.e., a BSS AP
  • the associated STA of information about an R-TWT SP (i.e., an OBSS R-TWT SP) allocated by another AP together with information about an R-TWT SP it allocates
  • the OBSS R-TWT SP can be protected through an overlapping silence interval.
  • OBSS R-TWT SP can be protected through overlapping silence intervals.
  • OBSS R-TWT SP can be protected based on TXOP and backoff procedure rules for R-TWT SP. A specific example of this is described with reference to FIG. 13.
  • Figure 13 shows an example of OBSS R-TWT SP protection to which the present disclosure can be applied.
  • AP1 and AP2 can share each other's R-TWT SP information. Accordingly, AP1 can announce information about the R-TWT SP(s) of BSS1 that it allocates and information about the R-TWT SP(s) of BSS2 that it allocates by AP2 through a beacon frame. In addition, AP2 can announce information about the R-TWT SP(s) of BSS2 that it allocates and information about the R-TWT SP(s) of BSS1 that it allocates by AP1 through a beacon frame.
  • STA1 may correspond to a UHR STA type that is coupled with AP1 and supports enhanced R-TWT.
  • STA1 may terminate its TXOP (earlier than the originally acquired TXOP length) before the start of the OBSS R-TWT SP.
  • the OBSS R-TWT SP may be protected via overlapping silence intervals.
  • AP2 transmits trigger information to STA2 associated with it, and in response, STA2 can transmit uplink data.
  • FIG. 14 and FIG. 15 are drawings for explaining examples of hidden nodes according to the present disclosure.
  • OBSS region i.e., a region where beacon frames from other APs can be overheard
  • BSS1 and BSS2 overlap or even if there is an OBSS region as in the example of Fig. 15, overhearing of beacon frames from other APs may not be possible depending on the location of the STA.
  • STA1-2 corresponds to a hidden node to AP2
  • STA2-4 corresponds to a hidden node to AP1. That is, STA1-2 may not receive a beacon frame from AP2, and STA2-4 may not receive a beacon frame from AP1.
  • a PPDU transmitted from STA1-2 or a PPDU transmitted from another STA (e.g., AP1 or another non-AP STA in BSS1) to STA1-2 may be overheard at STA2-4.
  • a PPDU transmitted from STA2-4 or a PPDU transmitted from another STA (e.g., AP2 or another non-AP STA in BSS2) to STA2-4 may be overheard at STA1-2. That is, PPDUs transmitted to/from STA1-2 and STA2-4 may cause interference to each other.
  • Interference reduction to hidden nodes may include OBSS R-TWT SP protection.
  • FIG. 16 is a diagram for explaining the operation of STA according to the present disclosure.
  • the first STA can monitor a PPDU related to a second STA belonging to the second BSS (hereinafter, inter-BSS PPDU).
  • inter-BSS PPDU a PPDU related to a second STA belonging to the second BSS
  • the first STA may correspond to an STA associated with the first AP of the first BSS. Additionally, a beacon frame transmitted by the second AP of the second BSS may not be received/detected by the first STA.
  • a PPDU associated with a second STA may correspond to a PPDU transmitted from or to the second STA.
  • the second STA may correspond to an STA associated with a second AP of the second BSS.
  • Inter-BSS PPDU monitoring may include determining whether a received or detected PPDU corresponds to an inter-BSS PPDU. That is, the first STA may determine whether the received/detected PPDU is a PPDU associated with itself or a PPDU associated with another STA based on various information included in the received/detected PPDU (e.g., BSS color information, source address information, destination address information, UL/DL direction information, etc.).
  • various information included in the received/detected PPDU e.g., BSS color information, source address information, destination address information, UL/DL direction information, etc.
  • a PPDU transmitted by a second STA to one or more other entities (e.g., the second AP and/or other non-AP STAs within the second BSS) belonging to the second BSS is received/detected by the first STA, it may be determined that an inter-BSS PPDU has been received/detected.
  • a PPDU transmitted from another entity (e.g., the second AP and/or other non-AP STAs within the second BSS) to the second STA is received/detected by the first STA, it may be determined that an inter-BSS PPDU has been received/detected.
  • the first STA may transmit report information including information indicating that an inter-BSS PPDU has been received or not received to the first AP.
  • the reporting information may be transmitted from the first STA to the first AP based on a request from the first AP.
  • the request (for transmitting reporting information) from the first AP may be transmitted periodically to the first STA.
  • the reporting information may be transmitted periodically from the first STA to the first AP.
  • the reporting information may be transmitted from the first STA to the first AP without a request from the first AP (i.e., in an unsolicited manner).
  • the first STA may transmit the reporting information to the first AP based on an event.
  • the event may include an event in which an inter-BSS PPDU is received/detected more than a predetermined number of times and/or with a predetermined receive strength or higher.
  • the reporting information may include one or more of BSS color information of the second BSS, source address (SA) information of the inter-BSS PPDU (e.g., MAC address of the transmitting STA), destination address (DA) information of the inter-BSS PPDU (e.g., MAC address of the receiving STA), or uplink/downlink (UL/DL) direction information of the inter-BSS PPDU.
  • SA source address
  • DA destination address
  • UL/DL uplink/downlink
  • the first STA can receive scheduling information for the first STA from the first AP based on the reporting information.
  • the scheduling information for the first STA may include information not requesting uplink transmission of the first STA.
  • the information not requesting uplink transmission of the first STA may include information indicating that a response to a downlink transmission from the first AP to the first STA is not requested (e.g., when the ACK policy is noACK).
  • the information not requesting uplink transmission of the first STA may not include information triggering uplink transmission from the first STA.
  • the first AP may not provide any scheduling information to the first STA.
  • the first AP may provide the first STA with information to set a silent interval overlapping for a specific time interval, similar to the OBSS R-TWT SP protection scheme, or to schedule the specific time interval as an R-TWT SP for another STA other than the first STA, and/or to schedule the specific time interval as an OBSS R-TWT SP.
  • the scheduling information for the first STA may include information requesting uplink transmission of the first STA. That is, if the first STA explicitly reports that a hidden node (e.g., the second STA) does not exist, or does not perform a report itself indicating the existence of a hidden node, the first AP may assume that the hidden node does not exist, and request uplink transmission from the first STA if necessary, perform downlink transmission from the first AP to the first STA, or allow or schedule transmission from another STA to the first STA.
  • a hidden node e.g., the second STA
  • the method described in the example of FIG. 16 may be performed by the first device (100) of FIG. 1.
  • one or more processors (102) of the first device (100) of FIG. 1 may be configured to monitor an inter-BSS PPDU transmitted from or to a second STA belonging to a second BSS, transmit report information including information indicating that an inter-BSS PPDU has been received or not received to the first AP through one or more transceivers, and receive scheduling information for the first device based on the report information from the first AP through one or more transceivers.
  • one or more memories (104) of the first device (100) may store commands for performing the method described in the example of FIG. 16 or the examples described below when executed by one or more processors (102).
  • FIG. 17 is a drawing for explaining the operation of an AP according to the present disclosure.
  • the first AP may receive, from the first STA associated with the first AP, report information including information indicating that an inter-BSS PPDU related to a second STA belonging to the second BSS is received or not received by the first STA.
  • the first AP may transmit scheduling information for the first STA based on the reporting information to the first STA.
  • the method described in the example of FIG. 17 may be performed by the second device (200) of FIG. 1.
  • one or more processors (202) of the second device (200) of FIG. 1 may be configured to receive, from a first device coupled with the second device, report information including information indicating that an inter-BSS PPDU transmitted from a second STA belonging to the second BSS or transmitted to the second STA is received or not received by the first device, through one or more transceivers, and to transmit, to the first device, scheduling information for the first device based on the report information, through one or more transceivers.
  • one or more memories (204) of the second device (200) may store commands for performing the method described in the example of FIG. 17 or the examples described below when executed by one or more processors (202).
  • FIGS. 16 and 17 may correspond to some of the various examples of the present disclosure.
  • various examples of the present disclosure, including the examples of FIGS. 16 and 17, will be described in more detail.
  • This embodiment relates to an STA that monitors a hidden node and a scheduling operation for the STA.
  • STA1-2 may interfere with (or cause interference to) data transmission and reception of STA2-4 by performing PPDU transmission and reception (especially, UL PPDU transmission) during the R-TWT SP allocated to it from AP1.
  • STA2-4 may interfere with (or cause interference to) data transmission and reception of STA1-2 by performing PPDU transmission and reception (especially, UL PPDU transmission) during the R-TWT SP allocated to it from AP2.
  • STA1-2 and/or STA2-4 may reduce or prevent influence/interference on each other by performing the following operations.
  • the overheard PPDU can be limited to a case corresponding to an inter-BSS PPDU. That is, assume a situation in which an STA belonging to a BSS other than the BSS to which it belongs, such as STA1-2 or STA2-4 of FIG. 14 or FIG. 15, can receive/detect transmission/reception involving the STA, or a case in which an STA exists in such a location.
  • An STA that receives/detects an inter-BSS PPDU can report to its associated AP that it has overheard the inter-BSS PPDU.
  • STA1-2 of FIG. 14 or FIG. 15 can report to AP1 that it has overheard a PPDU related to STA2-4, and STA2-4 can report to AP2 that it has overheard a PPDU related to STA1-2.
  • an AP may periodically request its associated STA(s) to report whether it has received/detected inter-BSS PPDUs (e.g., PPDUs associated with STAs belonging to different BSSs and in UL direction).
  • the STAs may periodically report whether it has received/detected inter-BSS PPDUs to the associated AP.
  • AP1 in FIG. 14 or FIG. 15 may request STA1-2 to report inter-BSS PPDU monitoring results
  • AP2 may request STA2-4 to report inter-BSS PPDU monitoring results.
  • an AP may not request UL data transmission to the STA that provided the report.
  • the AP may request/schedule the STA to receive only DL data.
  • AP1 of FIG. 14 or FIG. 15 may schedule/configure STA1-2 not to perform UL data transmission, and AP2 may schedule/configure STA2-4 not to perform UL data transmission, thereby preventing them from interfering with each other's data transmission and reception.
  • This embodiment relates to inter-BSS PPDU monitoring report information.
  • Specific fields and/or specific elements used to report to an AP to which an STA is associated that an inter-BSS PPDU has been received/detected may include some/all of the information described below.
  • the information included in the reporting information is not limited to the information described below, and may include various forms/types of information that may indicate that it corresponds to an inter-BSS PPDU and/or corresponds to UL data.
  • Specific fields/elements including reporting information for an inter-BSS PPDU may be transmitted/received via a previously defined frame, or may be transmitted/received via a newly defined frame.
  • BSS Color Corresponds to BSS color information (i.e., information that distinguishes BSSs) included in the inter-BSS PPDU (especially UL data) received/detected by the STA.
  • SA Source Address
  • SA corresponds to the MAC address of the transmitting STA of the inter-BSS PPDU (especially UL data) received/detected by the STA. This may correspond to the value of the address field set to SA or TA (transmitter address) in the PPDU (or in the MAC header).
  • DA Destination Address
  • the UL/DL information can indicate whether the PPDU is transmitted from a non-AP STA belonging to a different BSS or from an AP belonging to a different BSS.
  • the hidden node interference reduction operation can achieve a new effect of protecting transmission and reception of hidden nodes by preventing an STA monitoring a hidden node from transmission and reception that causes interference to the hidden node.
  • the scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) that cause operations according to the various embodiments to be executed on a device or a computer, and a non-transitory computer-readable medium having such software or instructions stored thereon and executable on the device or computer.
  • Instructions that can be used to program a processing system to perform the features described in the present disclosure can be stored on/in a storage medium or a computer-readable storage medium, and a computer program product including such a storage medium can be used to implement the features described in the present disclosure.
  • the storage medium can include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDR RAM, or other random access solid state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices.
  • the memory optionally includes one or more storage devices remotely located from the processor(s).
  • the memory or alternatively the non-volatile memory device(s) within the memory comprises a non-transitory computer-readable storage medium.
  • the features described in this disclosure may be incorporated into software and/or firmware stored on any one of the machine-readable media to control the hardware of the processing system and to allow the processing system to interact with other mechanisms that utilize results according to embodiments of the present disclosure.
  • Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments/containers.
  • the method proposed in this disclosure has been described with a focus on examples applied to IEEE 802.11-based systems, but can be applied to various wireless LANs or wireless communication systems in addition to IEEE 802.11-based systems.

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Abstract

Sont divulgués un procédé et un appareil de transmission ou de réception permettant de réduire les interférences pour un nœud caché dans un OBSS dans un système LAN sans fil. Un procédé mis en œuvre par une première station (STA) dans un système LAN sans fil, selon un mode de réalisation de la présente divulgation, comprend les étapes dans lesquelles : une première STA associée à un premier point d'accès (AP) d'un premier ensemble de services de base (BSS) surveille une unité de données de protocole de couche physique (PPDU) inter-BSS transmise par une deuxième STA, appartenant à un deuxième BSS, ou à la deuxième STA ; des informations de rapport comprenant des informations d'indication que la PPDU inter-BSS est reçue ou non reçue est transmise au premier AP ; et des informations de planification pour la première STA sur la base des informations de rapport sont reçues de la part du premier AP.
PCT/KR2024/006402 2023-05-12 2024-05-10 Procédé et appareil de réduction d'une interférence de nœud caché dans un système lan sans fil Ceased WO2024237604A1 (fr)

Priority Applications (2)

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CN202480032023.2A CN121336462A (zh) 2023-05-12 2024-05-10 用于减少无线lan系统中隐藏节点干扰的方法和装置
KR1020257037043A KR20260002845A (ko) 2023-05-12 2024-05-10 무선랜 시스템에서 히든 노드 간섭 저감 방법 및 장치

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Citations (5)

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KR20170030564A (ko) * 2014-08-07 2017-03-17 엘지전자 주식회사 무선랜에서 파워 세이브 모드 기반의 동작 방법 및 장치
US20180027573A1 (en) * 2016-05-10 2018-01-25 Laurent Cariou Station (sta), access point (ap) and method of spatial reuse
KR20180091772A (ko) * 2017-02-07 2018-08-16 애플 인크. 2차 채널 상의 기본 대역폭 디바이스
CN107210847B (zh) * 2015-02-12 2020-07-24 华为技术有限公司 一种信道竞争方法及相关装置
US20210409075A1 (en) * 2019-03-08 2021-12-30 Huawei Technologies Co., Ltd. Information transmission method, information receiving method, and apparatus for wireless communications system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20170030564A (ko) * 2014-08-07 2017-03-17 엘지전자 주식회사 무선랜에서 파워 세이브 모드 기반의 동작 방법 및 장치
CN107210847B (zh) * 2015-02-12 2020-07-24 华为技术有限公司 一种信道竞争方法及相关装置
US20180027573A1 (en) * 2016-05-10 2018-01-25 Laurent Cariou Station (sta), access point (ap) and method of spatial reuse
KR20180091772A (ko) * 2017-02-07 2018-08-16 애플 인크. 2차 채널 상의 기본 대역폭 디바이스
US20210409075A1 (en) * 2019-03-08 2021-12-30 Huawei Technologies Co., Ltd. Information transmission method, information receiving method, and apparatus for wireless communications system

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