Method and device for retransmitting initial control response in wireless LAN system

Abstract

The present disclosure relates to a method and device for retransmitting an initial control response in a wireless LAN system. A method performed by an electronic device operating as a first station (STA) in a wireless LAN network according to an embodiment of the present disclosure comprises the steps of: receiving an initial control frame (ICF) from a second STA; transmitting a first initial control response (ICR) to the second STA after a short inter frame space (SIFS) from a time point at which reception of the ICF is completed; and transmitting a second ICR corresponding to the first ICR to the second STA when a wireless medium (WM) is in an idle state until after a point coordination function inter frame space (PIFS) from a time point at which transmission of the first ICR is completed, and ICR retransmission is activated.

Description

Method and device for retransmitting an initial control response in a wireless LAN system

[0001] The present disclosure relates to a method and apparatus for transmitting a signal in a wireless LAN network system. More specifically, the present disclosure relates to a method and apparatus for retransmitting an initial control response (ICR).

[0002] A Wireless Local Area Network (WLAN), also known as Wi-Fi, is a network that enables internet access via mobile devices or laptops within a certain distance from an access point (AP). WLAN technology continues to evolve in line with the rise of the internet and the expansion of the smartphone market, and is being utilized to provide high-speed data services throughout the city, including in schools, airports, hotels, and offices.

[0003] The WiFi Alliance defines WiFi as a Wireless Local Area Network (WLAN) product based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11a and b, published in 1997 and 1999 respectively, are standards utilizing unlicensed bands at 2.4 GHz or 5 GHz; IEEE 802.11b provides a transmission speed of 11 Mbps, while IEEE 802.11a provides a transmission speed of 54 Mbps. IEEE 802.11g provides a transmission speed of 54 Mbps by applying Orthogonal Frequency-Division Multiplexing (OFDM) at 2.4 GHz. IEEE 802.11n applies multiple input multiple output OFDM (MIMO-OFDM) to provide a transmission speed of 300 Mbps using four spatial streams. IEEE 802.11n supports a channel bandwidth of up to 40 MHz, in which case it provides a transmission speed of 600 Mbps.

[0004] Subsequently, the IEEE 802.11ac standard was introduced, which uses a maximum bandwidth of 160 MHz and supports eight spatial streams to support speeds up to 1 Gbit / s, and the IEEE 802.11ax standard was introduced, which provides multi-user MIMO (MU-MIMO) in the uplink and downlink and supports spatial frequency reuse and dynamic fragmentation. Since then, research is underway on 802.11be, which aims to achieve theoretical speeds of 46 Gbps by supporting up to 320 ultra-wide channels, multi-link operation, and 4kQAM.

[0005] In existing wireless LAN systems, if a STA (station) that has transmitted an ICF (initial control frame) does not receive an ICR (initial control response), the STA determines that it has failed to acquire a TXOP (transmission opportunity) and retransmits the ICF through media access competition again.

[0006] If the STA that received the ICF transmits an ICR but the STA that transmitted the ICF does not receive the ICR, adjacent STAs that successfully received the ICR are excluded from media access contention for a long time, even though the STA that transmitted the ICF did not acquire the TXOP. As a result, overall network efficiency is reduced and unnecessary delays may occur. Additionally, if long padding is inserted into the ICF to support various technologies such as dynamic power save (DPS), multi-link operation (MLO), and dynamic subband operation (DSO), the overhead caused by ICF retransmission may increase.

[0007] Accordingly, technical means are required to reduce unnecessary ICF retransmissions and improve media utilization efficiency in the event of an ICR reception failure.

[0008] The technical problems to be solved in the various embodiments of the present disclosure are not limited to those mentioned above, and other technical problems not mentioned may be considered by those skilled in the art from the various embodiments of the present disclosure described below.

[0009] According to one embodiment of the present disclosure, a method is provided by an electronic device operating as a first STA (station) of a wireless LAN network. The method comprises: receiving an initial control frame (ICF) from a second STA; transmitting an initial control response (ICR) to the second STA after a short inter frame space (SIFS) from the time when the reception of the ICF is completed; and transmitting a second ICR corresponding to the first ICR to the second STA when the wireless medium (WM) is idle and ICR retransmission is enabled from the time when the transmission of the first ICR is completed until a point coordination function inter frame space (PIFS) from the time when the wireless medium (WM) is idle and ICR retransmission is enabled.

[0010] According to one embodiment of the present disclosure, a method is provided by an electronic device operating as a second STA of a wireless LAN network. The method comprises the steps of: transmitting an ICF to the first STA; and waiting for an ICR from the time when the transmission of the ICF is completed until the time when SIFS (short inter frame space), {ICR (initial control response) length + PIFS (point coordination function inter frame space)}*n, and 1 slot time are added, wherein n is an integer greater than or equal to 1 representing the number of allowed ICR retransmissions.

[0011] According to one embodiment of the present disclosure, an electronic device operating as a first STA of a wireless LAN network is provided. The electronic device includes a transceiver and a control unit. The control unit is configured to receive an ICF from a second STA through the transceiver, transmit a first ICR to the second STA through the transceiver after SIFS from the time when the reception of the ICF is completed, and also transmit a second ICR corresponding to the first ICR to the second STA through the transceiver when the WM is idle from the time when the transmission of the first ICR is completed until PIFS and ICR retransmission is enabled.

[0012] According to one embodiment of the present disclosure, an electronic device operating as a second STA of a wireless LAN network is provided. The electronic device includes a transceiver and a control unit. The control unit is configured to transmit an ICF to the first STA through the transceiver and to wait for an ICR from the time when the transmission of the ICF is completed until the time when SIFS, {ICR length + PIFS}*n, and 1 slot time are added, wherein n is an integer greater than or equal to 1 representing the number of allowed ICR retransmissions.

[0013] According to various embodiments of the present disclosure, a STA that has transmitted an ICR can retransmit the ICR after PIFS, thereby improving network latency without affecting fairness among STAs. Additionally, by reducing the overall network latency and the number of mode switches of DPS STAs, power efficiency and quality of service can be improved simultaneously, and the problem of increased overhead due to the repetition of ICF can be prevented.

[0014] The effects obtainable from the various embodiments of the present disclosure are not limited to those mentioned above, and other unmentioned effects can be clearly derived and understood by those skilled in the art based on the following detailed description.

[0015] Figure 1 is a diagram illustrating an example of a wireless communication network.

[0016] Figure 2 is a diagram illustrating an example of the structure of an electronic device that performs WLAN connection.

[0017] Figure 3 is a diagram illustrating an example of a link setup process for a typical wireless LAN.

[0018] Figure 4 is a diagram illustrating an example of a hidden node and an exposed node, and an example of an RTS and CTS for solving the problem of a hidden node and an exposed node.

[0019] Figure 5 is a diagram illustrating an example of a frame structure used in an IEEE 802.11 system.

[0020] Figure 6 is a diagram illustrating an example of a NAV setting.

[0021] Figure 7 is a diagram illustrating an example of TXOP.

[0022] Figure 8 is a diagram illustrating an example of a DPS mechanism.

[0023] Figure 9 is a diagram illustrating the structure of the ICF.

[0024] Figure 10 is a diagram illustrating the problems that occur when ICR reception fails.

[0025] FIG. 11 is a diagram illustrating an ICR retransmission procedure according to one embodiment of the present disclosure.

[0026] FIG. 12 is a diagram illustrating the operation method of a TXOP holder within an ICR retransmission procedure according to one embodiment of the present disclosure.

[0027] FIG. 13 is a diagram illustrating a DPS mechanism without an ICR retransmission procedure and a DPS mechanism with an ICR retransmission procedure applied, according to one embodiment of the present disclosure.

[0028] FIG. 14 is a flowchart illustrating the operation of a first STA of a wireless LAN system according to one embodiment of the present disclosure.

[0029] FIG. 15 is a flowchart illustrating the operation of a second STA of a wireless LAN system according to one embodiment of the present disclosure.

[0030] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0031] In describing the embodiments, technical details that are well known in the art to which this disclosure belongs and are not directly related to this disclosure are omitted. This is intended to convey the essence of this disclosure more clearly without obscuring it by omitting unnecessary explanations.

[0032] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the size of each component does not entirely reflect its actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference number.

[0033] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms. The embodiments of the present disclosure are provided merely to make the present disclosure complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Throughout the specification, like reference numerals refer to like components.

[0034] At this point, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing means of instruction to perform the function described in the flow diagram block(s).

[0035] Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that execute a computer or other programmable data processing equipment by performing a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer may also provide steps for executing the functions described in the flowchart block(s).

[0036] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specific logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For instance, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may be executed in reverse order depending on the corresponding function.

[0037] In this embodiment, the term "part" as used refers to a software or hardware component such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or may be configured to run one or more processors. Accordingly, according to some embodiments, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and 'parts' may be implemented to utilize one or more CPUs within the device or secure multimedia card. Also, according to some embodiments, the 'parts' may include one or more processors.

[0038] Exemplary embodiments are described below in relation to wireless LAN systems solely for the sake of simplicity. It should be understood that the exemplary embodiments are equally applicable to systems using signals of one or more wired standards or protocols (e.g., Ethernet and / or HomePlug, PLC standards), as well as other wireless networks (e.g., cellular networks, pico networks, femto networks, satellite networks). As used herein, the terms WLAN and Wi-Fi® may include communications controlled by the IEEE 802.11 family of standards, BLUETOOTH®, HiperLAN (a set of wireless standards comparable to IEEE 802.11 standards, mainly used in Europe), and other technologies having a relatively short wireless propagation range. Accordingly, the terms WLAN and Wi-Fi may be used interchangeably herein. Additionally, although the following describes an infrastructure WLAN system including one or more APs and multiple wireless stations (STAs), exemplary embodiments are equally applicable to other WLAN systems including, for example, multiple WLANs, peer-to-peer (or independent basic service set) systems, Wi-Fi Direct systems and / or hotspots.

[0039] Additionally, while this specification describes the exchange of data frames between wireless devices, exemplary embodiments may be applied to the exchange of any data unit, packet, and / or frame between wireless devices. Accordingly, the term "frame" may include any frame, packet, or data unit such as, for example, protocol data units (PDUs), media access control (MAC) protocol data units (MPDUs), and physical layer convergence procedure (PLCP) protocol data units (PPDUs). The term A-MPDU may mean aggregated MPDUs. In the following, a wireless LAN, or WLAN network, may be a network implementing at least one of the IEEE 802.11 wireless communication protocol standard family, such as as defined by the IEEE 802.11-2016 standard or its amendments (including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be).

[0040] In the following description, many specific details, such as examples of specific components, circuits, and processes, are presented to provide a thorough understanding of the present disclosure. As used herein, the term “connected” means being directly connected or being connected through one or more intervening components or circuits. The term “connected AP” means an access point to which a given wireless station is currently associated and / or connected (e.g., there exists a communication channel or link established between the access point and the given wireless station). Additionally, in the following description and for illustrative purposes, specific nomenclature is presented to provide a thorough understanding of exemplary embodiments. However, it will be apparent to those skilled in the art that these specific details may not be necessary to carry out the exemplary embodiments. In other cases, well-known circuits and devices are depicted in block diagram form to avoid obscuring the present disclosure. Also, the description of A / B means A or / and B, or at least one of A or B.

[0041] The operating principles of the present disclosure will be described in detail below with reference to the attached drawings. In describing the present disclosure below, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Furthermore, the terms described below are defined in consideration of their functions in the present disclosure, and these may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0042] Figure 1 is a diagram illustrating an example of a wireless communication network.

[0043] Referring to FIG. 1, the wireless communication network (100) may be an example of a wireless LAN, such as a Wi-Fi network. The wireless communication network (100) may include multiple wireless communication devices, such as an access point (AP, 102) and multiple stations (STA, 104). Although only one AP (102) is shown, the wireless communication network (100) may also include multiple APs (102).

[0044] A STA is a logical entity that includes a physical layer interface for a MAC and a wireless medium, and includes APs and non-AP STAs (Non-AP stations). Among the STAs, a portable terminal operated by a user is a Non-AP STA, and when simply referred to as STA, it may also refer to a Non-AP STA. Hereinafter, STA may refer to a non-AP STA. Each of the STAs (104) may be referred to as a terminal or a device. The terms 'terminal' or 'device' used in this specification may be referred to as a mobile station (MS), user equipment (UE), user terminal (UT), wireless terminal, access terminal (AT), terminal, subscriber unit, subscriber station (SS), wireless device, wireless communication device, wireless transmit / receive unit (WTRU), mobile node, mobile, or other terms. Various embodiments of the terminal may include cellular telephones, smartphones with wireless communication capabilities, personal handheld terminals (PDAs) with wireless communication capabilities, wireless modems, portable computers with wireless communication capabilities, imaging devices such as digital cameras with wireless communication capabilities, gaming devices with wireless communication capabilities, music storage and playback appliances with wireless communication capabilities, internet appliances capable of wireless internet access and browsing, as well as portable units or terminals integrating combinations of such functions. Additionally, the terminal may include machine-to-machine (M2M) terminals and machine-type communication (MTC) terminals / devices, but is not limited thereto. In this specification, the terminal may be referred to as an electronic device or simply a device.

[0045] An AP (102) is an entity that provides access to a distribution system (DS) via a wireless medium to an associated STA (STA) connected to it. The AP may also be called a central controller, a base station (BS), a Node-B, a base transceiver system (BTS), or a site controller.

[0046] An exemplary coverage area (106) of an AP (102) capable of representing the basic service area (BSA) of a wireless communication network (100) is illustrated. The AP (102) periodically broadcasts beacon frames (beacon frames may be interchangeable with beacons) containing a basic service set identifier (BSSID) to enable any STA (104) within the wireless range of the AP (102) to be associated with or re-associated with the AP (102) to establish or maintain individual communication links (108) (or may be referred to as Wi-Fi links) with the AP (102). The AP (102) can provide access to external networks for various STAs (104) within the WLAN through individual communication links (108).

[0047] A single AP (102) and an associated set of STAs (104) may be referred to as a basic service set (BSS) managed by the individual AP (102). The BSS may be identified to users by a service set identifier (SSID), as well as to other devices by a BSSID, which may be the MAC address of the AP (102).

[0048] BSS can be classified into infrastructure BSS and independent BSS (IBSS). The BSS shown in Fig. 1 is an IBSS, and it is also possible to establish an infrastructure BSS (not shown). An infrastructure BSS includes one or more STAs and APs, and in principle, communication between non-AP STAs in an infrastructure BSS is carried out via an AP, but if a direct link is established between non-AP STAs, direct communication between non-AP STAs is also possible.

[0049] Multiple infrastructure BSSs can be interconnected via DS. Multiple BSSs connected via DS are called an extended service set (ESS). STAs included in an ESS can communicate with each other, and within the same ESS, STAs can move from one BSS to another while communicating seamlessly.

[0050] A DS is a mechanism that connects multiple APs; it does not necessarily have to be a network, and there are no restrictions on its form as long as it can provide a specified distribution service. For example, a DS can be a wireless network such as a mesh network, or it can be a physical structure that connects APs to each other.

[0051] Additionally, AP (102) and STA (104) may be referred to as AP-MLD (access point multi-link device) and STA-MLD, respectively. This may mean that AP and STA can support multi-link operation.

[0052] Below, an example of a hierarchical structure according to the 802.11 standard is described.

[0053] The 802.11 standard document develops MAC and PHY protocols corresponding to Wi-Fi wireless access technology. The Data Link Layer (DLL) includes the MAC sublayer, which is responsible for media access control. It receives packets from the upper layer, 802.1X Port Filtering, via the MAC_SAP interface, constructs them into IEEE 802.11 MAC frames, and transmits them to the physical layer. The physical layer includes the PLCP (physical layer convergence procedure) sublayer and the PMD (physical medium dependent) sublayer. The PLCP sublayer is responsible for converting the IEEE 802.11 MAC frames constructed by the MAC sublayer into PLCP frames. The PLCP frames are then transmitted to the target terminal through the PMD sublayer.

[0054] Various management frames that manage Wi-Fi wireless access are not transmitted at the upper layers of 802.1X. Instead, these management frames are transmitted as requests and responses between Station Management Entities (SMEs) located within each terminal. An SME is a layer-independent entity that may exist within a separate management plane or appear to be off-the-side. For example, if an AP wants to configure a BSS, it instructs the transmission of beacons via the MLME_SAP interface, specifically the MLME-START.request and MLME-START.confirm primitives. If an STA wants to establish an association with the corresponding AP, it instructs the transmission of association Request / Response frames via the MLME-ASSOCIATE.request, MLME-ASSOCIATE.response, MLME-ASSOCIATE.confirm, and MLME-ASSOCIATE.indication primitives. Meanwhile, if you wish to set operational parameter values ​​related to the physical layer, the SME can set various physical layer parameter values ​​through the PLCP_SAP interface.

[0055] Figure 2 is a diagram illustrating an example of the structure of an electronic device that performs WLAN connection.

[0056] Referring to FIG. 2, the electronic device (200) may be connected to an AP (210), and the electronic device (200) may include a processor (230) and a communication module (220). The electronic device (200) may be the STA (104) of FIG. 1, in which case the electronic device (200) may be connected to the AP (210) as illustrated. Alternatively, the electronic device (200) may be the AP (102) of FIG. 1, in which case the electronic device may be connected to the STA (104) and / or another AP as illustrated in FIG. 1.

[0057] The communication module (220) can receive a communication signal from the outside or transmit a communication signal to the outside based on a Wi-Fi communication method (e.g., IEEE Std 802.11™). For example, the communication module (220) can operate based on Wi-Fi communication methods such as IEEE 802.11ac, 802.11ax, 802.11be, or 802.11bn, and in particular, IEEE 802.11be or 802.11bn supports a wider bandwidth, higher data throughput, and shorter latency compared to IEEE 802.11ax, thereby improving performance.

[0058] The communication module (220) may include a transceiver (224) for transmitting and receiving data with an external device and a communication processor (222) (e.g., a communication processor (not shown), or a short-range wireless communication module (e.g., a Wi-Fi chipset)). Depending on various embodiments, the communication module (220) may further include memory.

[0059] According to various embodiments, the transceiver (224) can convert a baseband transmission signal into a wireless signal or convert a received wireless signal into a baseband reception signal.

[0060] According to various embodiments, the communication module (220) may further include, in addition to the transceiver (224) and the communication processor (222), components for OFDM or OFDMA (orthogonal frequency division multiple access), such as a modulator, a digital-analog converter, a frequency converter, an A / D converter, an amplifier, and / or a demodulator.

[0061] According to various embodiments not shown, the electronic device (200) may be electrically connected to a communication module of the AP (210) and may include at least one antenna module that supports a communication protocol and / or frequency band supported by the communication module of the AP (210).

[0062] A communication processor (222) can control a transceiver (224) to form a communication connection with an AP (210). For example, the communication connection may include a Wi-Fi network. For example, a communication processor (222) can control a transceiver (224) to form a wireless connection with an AP (210) using a WLAN standard in the 2.4 GHz, 5 GHz, or 6 GHz band such as IEEE 802.11ac, 802.11ax, 802.11be, or 802.11bn. Alternatively, a communication processor (222) can control a transceiver (224) to form a wireless connection with an AP (210) using a WLAN standard in the 60 GHz band such as IEEE 802.11ad or 802.11ay. In addition, the method of communicating between the electronic device (200) and the AP (210) using a WLAN standard can be referred to as a communication method based on STA mode.

[0063] According to various embodiments, the processor (230) may include an application processor. The processor (230) may perform a specified operation of the electronic device (200) or control other hardware (e.g., a communication module (220)) to perform a specified operation.

[0064] According to various embodiments, the AP (210) may support the operation of transmitting packets to an external network and / or the operation of receiving packets from an external network based on a connection between a plurality of electronic devices (e.g., electronic device (200)) and an external network (e.g., the Internet, an external LAN, or a cellular network).

[0065] For example, the AP (210) may be a wireless router. The AP (210) may be a dedicated wireless router or a general-purpose device that supports mobile hotspot functions, and there are no limitations on its implementation. For example, the AP (210) may include the same components (e.g., a processor and / or a communication module) as the electronic device (200). Additionally, the AP (210) may transmit and receive data with an external device, such as a server. For example, the AP (210) may transmit at least some of the data received from the server to the electronic device (200).

[0066] If the electronic device (200) of FIG. 2 corresponds to the AP (102), the electronic device (200) may include a separate communication module for connection with an external network, although not shown. This communication module may be controlled by a processor (230) or by a separate processor. The separate communication module may include a transceiver and a processor, and may also include memory. Additionally, the electronic device (200) may include a separate antenna module or a wired connection device for connection with an external network.

[0067] Figure 3 is a diagram illustrating an example of a link setup process for a typical wireless LAN.

[0068] In order for an STA to set up a link and transmit and receive data on a network, it must first discover the network, perform authentication, establish an association, and go through authentication procedures for security. The link setup process can also be referred to as the session initiation process or the session setup process. Additionally, the discovery, authentication, association, and security setup processes of the link setup process can be collectively referred to as the association process.

[0069] Referring to FIG. 3, the STA (300) can perform a network discovery operation. The network discovery operation may include a scanning operation of the STA (300). That is, in order for the STA (300) to access a network, it must find a network that it can join. Before joining a wireless network, the STA (300) must identify a compatible network, and the process of identifying networks existing in a specific area is called scanning.

[0070] Scanning methods include active scanning and passive scanning. In active scanning, the STA (300) performing the scanning moves between channels and sends a probe request frame (322) to search for nearby APs and waits for a response. The responder sends a probe response frame (324) as a response to the probe request frame to the STA that sent the probe request frame. Here, the responder may be the AP or STA that last sent a beacon frame from the BSS of the channel being scanned. In FIG. 3, an example of a BSS that becomes the responder is shown where the AP (310) sends a beacon frame (320). In an IBSS, the responder is not constant because the STAs within the IBSS take turns sending beacon frames. For example, if an STA transmits a probe request frame on channel 1 and receives a probe response frame on channel 1, the STA can store the BSS-related information included in the received probe response frame and move to the next channel to perform scanning in the same way.

[0071] Scanning operations may be performed using a passive scanning method. In passive scanning, the STA performing the scanning detects beacon frames while switching between channels. A beacon frame is one of the management frames in IEEE 802.11, which announces the presence of a wireless network and is periodically transmitted to allow the scanning STA to find the wireless network and join it. Figure 3 illustrates an example of a BSS in which an AP (310) periodically transmits beacon frames (320) to an STA (300), and in an IBSS, STAs within the IBSS take turns transmitting beacon frames. When the scanning STA receives a beacon frame, it stores information about the BSS included in the beacon frame and records the beacon frame information in each channel while moving to another channel. When comparing active scanning and passive scanning, active scanning has the advantage of having less delay and power consumption than passive scanning.

[0072] After the STA (300) discovers the network, an authentication process may be performed. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation (350) described later. The authentication process includes the STA (300) sending an authentication request frame (330) to the AP (310), and in response, the AP (310) sending an authentication response frame (332) to the STA (300). The authentication frame used in the authentication request / response corresponds to a management frame.

[0073] The authentication frame may include information such as the authentication algorithm number, authentication transaction sequence number, status code, challenge text, RSN (robust security network), finite cyclic group, etc. These are some examples of information that may be included in the authentication request / response frame, and may be replaced with other information or additional information may be included.

[0074] AP (310) can determine whether to allow authentication for the STA based on the information included in the received authentication request frame. AP (310) can provide the result of the authentication processing to the STA (300) through an authentication response frame.

[0075] After the STA is successfully authenticated, an association process can be performed. The association process includes the STA (300) sending an association request frame (340) to the AP (310), and in response, the AP (310) sending an association response frame (342) to the STA (300).

[0076] For example, the associated request frame may include information regarding various capabilities, beacon listen interval, SSID, supported rates, supported channels, RSN (robust security network), mobility domain, supported operating classes, traffic indication map broadcast request, interworking service capabilities, etc.

[0077] For example, an association response frame may include information related to various capabilities, status code, association ID (AID), support rate, enhanced distributed channel access (EDCA) parameter set, received channel power indicator (RCPI), received signal to noise indicator (RSNI), mobility domain, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS map, etc.

[0078] This is a partial example of the information that may be included in the associated request / response frame, and it may be replaced with other information or additional information may be included.

[0079] Although not yet described, a security setup process can be performed after the STA is successfully associated with the network. The security setup process may be described as an authentication process through RSNA (robust security network association) requests / responses, and the authentication process (330) may be called the first authentication process, and the security setup process may also be called the authentication process.

[0080] The security setup process may include, for example, a private key setup process through a 4-way handshake via an EAPOL (extensible authentication protocol over LAN) frame, or may be performed according to a security method not defined in the IEEE 802.11 standard.

[0081] The following describes the Media Access Control Protocol provided by 802.11.

[0082] In wireless LAN systems based on IEEE 802.11, the basic access mechanism of a MAC is based on a distributed coordination function (DCF) utilizing the carrier sense multiple access with collision avoidance (CSMA / CA) method. There are two methods for detecting carriers in DCF: physical carrier sense and virtual carrier sense. The physical carrier sense method detects channel conditions at the physical layer and informs the MAC layer, while the virtual carrier sense method reserves a channel in advance by broadcasting the channel occupancy time to surrounding stations. An STA or AP that has secured a transmission channel records and transmits this channel occupancy time within an RTS and / or CTS or data frame; other STAs receiving this information determine that the channel is in use during this time and avoid channel occupancy contention, thereby avoiding collisions.

[0083] The physical carrier sensing method basically employs a listen before talk access mechanism, and according to this type of access mechanism, the AP and / or STA can perform a clear channel assessment (CCA) to sense the wireless channel, carrier, or medium for a predetermined time interval before starting transmission. The predetermined time interval is referred to as the inter-frame space (IFS) and may vary depending on the priority of the traffic to be transmitted. That is, priority can be determined by the length of the time interval, and packets with higher priority may have shorter time intervals.

[0084] The above IFS may include SIFS (short IFS), PIFS (PCF IFS), DIFS (DCF IFS), AIFS (arbitration IFS), etc. SIFS is the shortest time interval and can be used primarily as a waiting time for control information. PIFS is a medium-length time interval and may be for packets of medium priority (PIFS = SIFS + 1 slot time). DIFS is the longest time interval compared to SIFS and PIFS, has a low priority, and can be used primarily as a waiting time to check channel usage (DIFS = SIFS + 2 slot time). That is, for example, an STA intending to perform transmission can listen to (or detect the channel) the availability of the channel during the DIFS period. AIFS can be defined as a dynamic frame interval by assigning a different AIFSN (AIFS number) to each AC (AIFS = SIFS + AIFSN * slot time).

[0085] If sensing results determine that the medium is in an idle status, the AP and / or STA begin transmitting a frame through the medium. Conversely, if the medium is detected to be in an occupied status, the AP and / or STA may not begin their own transmission but wait for a delay period (e.g., a random backoff period) for accessing the medium before attempting to transmit a frame. By applying a random backoff period, multiple STAs are expected to attempt to transmit frames after waiting for different periods of time, thereby minimizing collisions.

[0086] However, since this DCF method does not consider the priority between STAs, it has the problem of being difficult to support various forms of data transmission and QoS (quality of service); therefore, HCF (hybrid coordination function) was introduced. HCF is based on the aforementioned DCF and PCF (point coordination function). PCF refers to a polling-based synchronous access method that periodically polls all receiving APs and / or STAs so that they can receive data frames. HCF includes EDCA (enhanced distributed channel access), a contention-based channel access method, and HCCA (HCF controlled channel access), a contention-based method utilizing a polling mechanism. Furthermore, HCF includes a media access mechanism to enhance the QoS of a WLAN and can transmit QoS data during both the contention period (CP) and the contention-free period (CFP).

[0087] According to EDCA, data has user priorities ranging from 0 to 7 based on traffic type, and data arriving at the MAC layer is mapped to four access categories (ACs) according to these priorities. More specifically, AC_VO (voice) is used for voice traffic. Since real-time communication, such as voice calls, requires minimal latency, it is assigned the highest priority to ensure fast transmission. AC_VI (video) is used for video streaming traffic. Because video streaming is also sensitive to latency, it is assigned a priority second only to voice to ensure smooth playback. AC_BE (best effort) is used for general data traffic. For example, traffic such as web surfing and email is relatively less sensitive to latency and can be processed with a medium priority. Finally, AC_BK (background) is used for background traffic. Traffic where latency is not critical, such as file downloads or data transmissions running in the background, can be processed with a low priority. As the priority increases, it is assigned a higher priority. Since ACs each possess their own AC parameters and perform backoff using differently configured AC parameter values, data acquires different channel access priorities depending on the AC. Potential AC parameters include AIFS, CWmin, CWmax, and TXOP limits. Smaller values ​​for AIFS and CWmin correspond to higher priority; consequently, channel access delays are shortened, allowing data to utilize more bandwidth in a given traffic environment. The EDCA backoff process, which generates a new backoff counter in the event of a collision between STAs during frame transmission, is similar to the existing DCF, and transmission based on traffic priority is guaranteed through EDCA parameters that include AC-specific priorities.

[0088] Figure 4 is a diagram illustrating an example of a hidden node and an exposed node, and an example of an RTS and CTS for solving the problem of a hidden node and an exposed node.

[0089] Figure 4 (a) (400) is an example of a hidden node. When STA A and STA B are communicating and STA C has information to transmit, STA A is transmitting information to STA B, but when STA C performs carrier sensing before sending data to STA B, it can be determined that the medium is idle. This is because STA C may not be able to sense STA A's transmission (i.e., medium occupancy) at its location. In this case, a collision occurs because STA B receives information from STA A and STA C simultaneously. At this time, STA A can be considered a hidden node of STA C.

[0090] (b)(410) is an example of an exposed node. In a situation where STA B is transmitting data to STA A, STA C may have information to transmit to STA D. In this case, if STA C performs carrier sensing, it can determine that the medium is occupied due to the transmission by STA B. Accordingly, STA C must wait until the medium becomes idle, even if it has information to transmit to STA D. However, in reality, since STA A is outside the transmission range of STA C, the transmission from STA C and the transmission from STA B may not conflict from STA A's perspective, so STA C ends up waiting unnecessarily until STA B stops transmitting. In this case, STA C can be referred to as the exposed node of STA B.

[0091] In order to efficiently utilize the collision avoidance mechanism in the above situation, short signaling packets such as RTS (request to send) and CTS (clear to send) may be used. An STA intending to transmit data transmits an RTS to a STA intending to receive data, and the receiving STA that receives the RTS responds to the transmitting STA with a CTS frame. The RTS and / or CTS between the two STAs may cause surrounding STA(s) to overhear, thereby causing the surrounding STA(s) to consider whether to transmit information between the two STAs.

[0092] (c)(420) is an example of how to solve the hidden node problem. Assume that both STA A and STA C intend to transmit data to STA B. When STA A transmits an RTS to STA B, STA B transmits a CTS to STA A. STA C, which overhears the RTS and CTS, delays its media access until the data transmission of STA A and STA B is finished, thereby avoiding collisions.

[0093] (d)(430) is an example of a method for solving the exposed node problem. STA B, which intends to transmit data to STA A, transmits an RTS, and STA A, which is to receive the data, transmits a CTS to respond to the RTS. In this case, if STA C receives only the RTS transmitted by STA B and does not receive the CTS transmitted by STA A, STA C can determine that STA A is outside the carrier sensing area of ​​STC C. In this case, STA C can transmit data, judging that no collision will occur even if it transmits data to another STA (e.g., STA D).

[0094] Figure 5 is a diagram illustrating an example of a frame structure used in an IEEE 802.11 system.

[0095] The PPDU (physical layer protocol data unit) format can be configured to include the STF (short training field), LTF (long training field), SIG (signal) field, and data field. The most basic (e.g., non-HT (high throughput)) PPDU frame format can be configured to include only the L-STF (legacy-STF), L-LTF (legacy-LTF), SIG field, and data field.

[0096] STF can be used for frame timing acquisition, automatic gain control (AGC), diversity detection, and coarse frequency / time synchronization. LTF can be used for fine frequency / time synchronization and channel estimation. STF and LTF together can be referred to as the PLCP preamble, and the PLCP preamble can be described as a signal for synchronization and channel estimation in the OFDM physical layer.

[0097] The SIG field can be used to transmit control information for demodulation and decoding of the data field. The SIG field may include information regarding the data rate and data length. Additionally, the SIG field may include a parity bit, a SIG TAIL bit, etc.

[0098] The data field may include a SERVICE field, a PSDU (physical layer service data unit), and PPDU TAIL bits, and may also include padding bits if necessary. Some bits of the SERVICE field may be used for the descrambler at the receiver. The PSDU corresponds to the MPDU (MAC protocol data unit) defined at the MAC layer and may contain data generated or used by the upper layer. The PPDU TAIL bits may be used to return the encoder to a state of 0. Padding bits may be used to adjust the length of the data field to a predetermined unit.

[0099] MPDUs are defined according to various MAC frame formats, and a basic MAC frame consists of a MAC header, a frame body, and a frame check sequence (FCS). A MAC frame is composed of an MPDU and can be transmitted or received through the PSDU of the data portion in the PPDU format.

[0100] The MAC header is defined as an area containing the frame control field, duration / ID field, address 1 field, address 2 field, address 3 field, sequence control field, address 4 field, QoS control field, and HT control field.

[0101] The frame control field contains information about the corresponding MAC frame characteristics. The interval / identifier field can be implemented to have different values ​​depending on the type and subtype of the corresponding MAC frame.

[0102] Fields 1 through 4 of the address are used to indicate the BSSID, source address (SA), destination address (DA), transmitting address (TA) representing the transmitting STA address, and receiving address (RA) representing the receiving STA address.

[0103] The sequence control field is configured to include a sequence number and a fragment number. The sequence number may indicate the sequence number assigned to the corresponding MAC frame. The fragment number may indicate the number of each fragment of the corresponding MAC frame.

[0104] The QoS control field contains information related to QoS. The QoS control field may be included if the Subtype subfield indicates a QoS data frame. The HT control field contains control information related to HT and / or VHT transmission and reception techniques.

[0105] The frame body is defined as the MAC payload, contains the data to be transmitted from the upper layer, and has a variable size. For example, the maximum MPDU size can be 11,454 octets, and the maximum PPDU size can be 5.484 ms.

[0106] FCS is defined as the MAC footer and is used for error detection in MAC frames.

[0107] The first three fields (frame control field, interval / identifier field, and address 1 field) and the very last field (FCS field) constitute the minimum frame format and are present in all frames. Other fields may exist only in specific frame types.

[0108] The following describes the network allocation vector (NAV) used in wireless LAN networks.

[0109] As previously mentioned, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing, where the AP and / or STA directly senses the medium. Virtual carrier sensing is intended to compensate for problems that may occur in medium access, such as hidden node issues. For virtual carrier sensing, the MAC of a wireless LAN system may utilize NAV. NAV is a value that indicates to other APs and / or STAs the time remaining until the medium becomes available, provided that the AP and / or STA currently using or authorized to use the medium is using the medium. Therefore, the value set as NAV corresponds to the period during which the medium is scheduled to be used by the AP and / or STA transmitting the frame, and the STA receiving the NAV value is prohibited from accessing the medium during that period. NAV can be set, for example, based on the value of the duration field in the MAC header of the frame.

[0110] Figure 6 is a diagram illustrating an example of a NAV setting.

[0111] Referring to FIG. 6, the source STA (source STA, 600) transmits an RTS frame after DIFS, and the destination (610) transmits a CTS frame after SIFS. The destination STA designated as the recipient via the RTS frame does not set the NAV. Some of the remaining STAs (620) receive the RTS frame and set the NAV (630), while others receive the CTS frame and set the NAV (640).

[0112] If a CTS frame (e.g., PHY-RXSTART.indication primitive) is not received within a certain period from the time an RTS frame is received (e.g., when a MAC receives the PHY-RXEND.indication primitive corresponding to the RTS frame), STAs that set or updated the NAV via the RTS frame may reset the NAV (e.g., to 0) (or this case may be referred to as NAVtimeout). The certain period may be (2*aSIFSTime + CTS_Time + aRxPHYStartDelay + 2*aSlotTime), which may be referred to as the NAVtimeout period. CTS_Time may be calculated based on the length and data rate of the CTS frame indicated by the RTS frame.

[0113] In FIG. 6, for convenience, NAV setting or updating is exemplified through an RTS frame or a CTS frame, but NAV setting / resetting / updating may also be performed based on the interval field of various other frames, such as non-HT PPDU, HT PPDU, VHT PPDU, or HE PPDU (for example, the interval field within the MAC header of a MAC frame).

[0114] In addition, 802.11ax introduced basic NAV and intra-BSS NAV. Basic NAV is always set (mandatory) to NAV based on frames transmitted by APs or STAs other than itself, while intra-BSS NAV can be optionally set to NAV based on frames transmitted by the BSS to which it belongs. An AP or STA can access the medium when both NAV timers have expired (or after the NAV time interval has elapsed).

[0115] The following describes TXOP. TXOP (transmission opportunity) was newly introduced in 802.11e MACs to guarantee QoS and increase channel utilization. To guarantee QoS, TXOP can be used to allocate an opportunity for priority transmission when two or more packets belong to the same AC (access category).

[0116] Figure 7 is a diagram illustrating an example of TXOP.

[0117] STAs participating in QoS transmission can obtain a TXOP that allows them to transmit traffic for a certain period using two channel access methods, such as EDCA and HCCA. TXOP acquisition is possible by succeeding in EDCA contention or receiving a QoS CF-Poll frame from an AP; the former is referred to as an EDCA TXOP, and the latter as a Polled TXOP. In this way, the concept of a TXOP can be used to grant a certain amount of time to any STA to transmit a frame, or to forcibly limit the transmission time.

[0118] The transmission start time and maximum transmission time of a TXOP are determined by the AP, and this is notified to the STA by a beacon frame in the case of an EDCA TXOP, and by a QoS CF-Poll frame in the case of a Polled TXOP.

[0119] NAV can be understood as a type of timer designed to protect the TXOP of a transmitting STA (e.g., a TXOP holder). An STA can protect the TXOPs of other STAs by not performing channel access during the period when the NAV set for it is valid. In current wireless LAN systems, the TXOP duration is set via the duration field of the MAC header. That is, the TXOP holder and the TXOP responder (e.g., an Rx STA) include all the TXOP information necessary for transmitting and receiving frames in the duration field of the frames being exchanged between them. Third-party STAs that are not the TXOP holder or TXOP responder (e.g., third-party STAs) check the duration field of the frames exchanged between the TXOP holder and the TXOP responder, and delay channel usage until the NAV period expires by setting or updating the NAV.

[0120] The primary channel and secondary channel are described below. The primary channel is a common channel operated by all STAs that are members of the BSS. For example, in a 20 MHz, 40 MHz, 80 MHz, 160 MHz, or 80 + 80 MHz BSS, the primary channel may be the primary 20 MHz channel. In this case, the 40 and 80 MHz channels containing the primary 20 MHz channel may be referred to as the primary 40 and 80 MHz channels, and the primary channel may generally refer to the primary 20 MHz channel.

[0121] A secondary channel is a channel associated with a primary channel and is used to create a channel wider than the primary channel. For example, in a 40 MHz, 80 MHz, and 160 MHz BSS, the 40 MHz channel may be the sum of the primary 20 MHz channel and the secondary 20 MHz channel, the 80 MHz channel may be the sum of the primary 40 MHz channel and the secondary 40 MHz channel, and the 160 MHz channel may be the sum of the primary 80 MHz channel and the secondary 80 MHz channel.

[0122] The 802.11be standard is described below. Also known as EHT (extremely high throughput), 802.11be operates across the 2.4, 5, and 6 GHz bands. It is being developed to provide low latency and high network throughput by introducing a 320 MHz wide bandwidth, 4096QAM, multiple resource units (RUs), and multi-link operation (MLO), offering speeds up to 46 Gbps—4.8 times faster than WiFi 6. Specifically, 802.11be provides a 320 MHz wide bandwidth in the 6 GHz band and can transmit data via MU-MIMO, which offers 16 spatial streams in both uplink and downlink. It also achieves high transmission efficiency by adopting 4096QAM. Furthermore, it features enhanced spectrum efficiency by flexibly performing spectrum resource scheduling through multiple RUs, and the ability to simultaneously transmit and receive data across various frequency bands and channels through multi-link operation.

[0123] The following describes TXOP sharing. In 802.11ac, MU-MIMO MAC technology was introduced to enhance wireless channel efficiency by utilizing spatially partitioned multiple channels, enabling the simultaneous transmission of different frames from an AP to multiple STAs. In this process, the AP determines the destination STA and the frame to be transmitted for each channel during the TXOP period based on the AC (access category, or priority) of the frame to be transmitted, and then sends the determined multiple frames to the multiple STAs. Recently, TXOP sharing between APs has been under research. Through TXOP sharing between APs, an AP holding a TXOP can share it with other APs, thereby efficiently utilizing frequency and spatial resources to increase network throughput and reduce latency.

[0124] Next, we will describe the overlapping basic service set (OBSS). As the number of users increases, the performance of existing wireless LAN networks, such as transmission rates, decreases significantly. This is because wireless LAN systems fundamentally utilize the CSMA / CA method, which corresponds to time division access control; therefore, when an adjacent network is detected, the frequency resources of the same band are shared for the duration of the adjacent network's activity.

[0125] Currently, it is common for multiple APs to operate in specific areas, and in such cases, wireless LAN network performance degradation occurs due to coverage overlap between APs. This is because the APs of each BSS and the STAs connected to them are affected by signals from adjacent BSSs, leading to interference and a reduction in transmission rates caused by collisions between signals transmitted simultaneously. BSSs that can affect signal transmission in this way (or have overlapping coverage) can be referred to as overlapping BSSs (OBSS). To address this problem, interference avoidance techniques are being researched, such as dividing the bandwidth available to each user so that it does not overlap or performing channel switching to unused channels, as well as interference alignment techniques that minimize the impact of interference even when using the same bandwidth.

[0126] Meanwhile, Ultra High Reliability (UHR) is a technology currently under development by IEEE 802.11bn that aims to significantly improve the reliability of WLAN networks. In particular, various technologies are being discussed to achieve UHR. For example, distributed multi-link operation (MLO) enables seamless connectivity by distributing APs to multiple physical hardware locations under a single control entity; technologies that guarantee deterministic performance for time-sensitive and event-based traffic by improving the PHY and MAC layers; and multi-AP coordination technology, which mitigates contention and improves spectrum utilization by coordinating the activities of multiple APs within and between networks, are being developed.

[0127] As various technologies are introduced for UHR, power consumption of devices within WLAN networks may increase, and the need for power reduction is also growing, particularly in battery-operated mobile devices and IoT devices.

[0128] To address this, power saving (PS) mechanisms are being explored in UHR environments, and they can be broadly classified into short-term PS and long-term PS methods.

[0129] Examples of short-term PS methods include the following:

[0130] - Dynamic PS (DPS): By switching between LC (Low Capability) mode and HC (High Capability) mode as needed, the STA can reduce power consumption to meet the required reliability or performance level. This is achieved through control-level signaling, allowing it to return to LC mode to minimize power usage when high-performance communication is not required. For example, an STA in LC mode can receive only a single spatial stream with a 20 MHz bandwidth, while an STA in HC mode can receive multiple spatial streams with an 80 MHz or 160 MHz bandwidth.

[0131] - Cross-link PS: An STA that supports the MLO function can report the PS status of one active link to the AP and enable / disable the PS mode on other links. This reduces the burden on the STA to operate multiple links simultaneously and allows for flexible adjustment of power consumption per link as needed.

[0132] Examples of long-term PS methods include the following.

[0133] - Scheduled PS: Similar to TWT (Target Wake Time), the operation time is scheduled / notified in advance, allowing the STA to enter doze mode for a certain period and return to an active state at the scheduled time. This enables the optimization of power usage schedules in the long term and reduces unnecessary active time.

[0134] The following describes the process of switching between HC and LC modes using DPS, one of the power saving mechanisms.

[0135] Figure 8 is a diagram illustrating an example of a DPS mechanism.

[0136] Referring to FIG. 8, the process of STA-1 (800) and STA-2 (810) operating according to the DPS mechanism is illustrated. Here, STA-1 (800) may be a peer STA (including AP or non-AP STA) of a STA with the DPS function enabled and may be referred to as a TXOP holder. STA-2 (810) may be a STA (including AP or non-AP STA) with the DPS function enabled and may be referred to as a TXOP responder.

[0137] STA-1 (800) can transmit an Initial Control Frame (ICF) (802) that allows STA-2 (810) to transition from LC mode to HC mode after a period of backoff (801).

[0138] An Intermediate Frame Check Sequence (IFCS) field may be inserted into the ICF (802) for error verification. STA-2 (810), which was in LC mode, can perform error verification by decoding up to the IFCS field included in the ICF (802). If the part up to the IFCS field is successfully received without errors, STA-2 (810) can start switching to HC mode.

[0139] Additionally, the ICF (802) may include additional padding, which prevents other STAs in the network from attempting to access the channel while STA-2 (810) is transitioning from LC mode to HC mode.

[0140] STA-2 (810), having completed entering HC mode, can transmit an ICR (Initial Control Response) (811) to STA-1 (800). The ICR (811) can be transmitted after SIFS, when the reception of the ICF (802), including padding, is fully completed.

[0141] STA-1 (800) can confirm that STA-2 (810) has successfully transitioned to HC mode by receiving ICR (811). Subsequently, STA-1 (800) can transmit data (803) based on HC mode. For example, STA-1 (800) can transmit data (803) using multiple spatial streams with a bandwidth of 80 MHz or 160 MHz.

[0142] STA-2 (810) can provide feedback on the reception status of the data received from STA-1 (800) by transmitting a Block Acknowledgement (BA) (812). For example, the data (803) may be an Aggregated MPDU (A-MPDU) consisting of one or more MAC Protocol Data Units (MPDUs), and the BA (812) may be transmitted in the form of a bitmap indicating whether each MPDU in the A-MPDU has been successfully received.

[0143] Afterwards, when frame exchange is complete and there are no more frames to receive, STA-2 (810) can terminate HC mode operation and return to LC mode after a transition time to maintain a low power state.

[0144] Figure 9 is a diagram illustrating the structure of the ICF.

[0145] In order to perform the DPS operation described above in FIG. 8, it is necessary for the ICF to include sufficient padding to secure time for the DPS STA to switch from LC mode to HC mode. In this case, if a padding section is inserted into the ICF, the receiving STA of the ICF must perform error verification before initiating the switch from LC mode to HC mode, so it may be desirable for the IFCS field to be located before the padding. The ICF used for the DPS operation may be configured, for example, as a modified form of a trigger frame, and a typical trigger frame may include at least one of the following fields.

[0146] - Frame Control: A field containing control information for the MAC frame, which may include basic control information such as frame type and subtype.

[0147] - Duration: A field indicating the time required for frame transmission, which can be used for NAV settings.

[0148] - RA (Receiver Address): May include the receiver's MAC address.

[0149] - TA (Transmitter Address): May include the sender's MAC address.

[0150] - Common Info: Information applicable to all users, which may include basic control parameters and / or common setting values.

[0151] - User Info List: Contains information for each individual user (User Info field) and may consist of one or more User Info fields that include user-specific transmission parameters and settings. If the AID12 (Association ID 12-bit) within the User Info field has a value of '2007' or higher, information that applies commonly to all users, such as Common Info, may be included in that User Info field.

[0152] - Padding: Can be used to adjust the frame size.

[0153] - FCS (Frame Check Sequence): Can be used to detect errors that may occur during frame transmission.

[0154] According to one embodiment of the present disclosure, the method of inserting IFCS and padding into an ICF can be divided into, for example, two options as follows.

[0155] FIG. 9(a) illustrates a structure in which an IFCS field is included in some of the User Info List or User Info fields of a trigger frame. These User Info List or User Info fields may have an AID12 value greater than '2007' and may be referred to as a Special User Info List or Special User Info field, respectively. Additionally, an additional padding bit is inserted after the IFCS field and added to the existing padding field of the trigger frame to secure the time required for switching from LC mode to HC mode for DPS.

[0156] FIG. 9(b) illustrates a structure in which an IFCS field is included in part of the padding field of a trigger frame. All bits of a specific number (e.g., 2) of octets initially set in the padding field are set to '1', and then the IFCS field may be positioned. After the IFCS field, padding bits may be inserted in an amount sufficient for the DPS STA to switch from LC mode to HC mode.

[0157] For example, the length of padding inserted into the ICF can be set from 0μs to 256μs. The maximum of 256μs is intended to sufficiently support the delay required to switch from LC mode to HC mode, whereas 0μs may indicate a case where the DPS STA determines that padding is unnecessary because there is almost no switching delay. If padding is not inserted, the IFCS may also not be required.

[0158] In addition, it may be desirable for the required padding time to be notified in advance before the STA switches to DPS mode. For example, the switching delay (padding) time can be shared among STAs along with power saving operations through UHR Capabilities, UHR Operation IE, or Action frames for activating DPS mode. Through this, when a STA in LC mode switches to HC mode, the other STA can determine how much padding to insert and ensure the stability of the switching process by transmitting an ICF with appropriate IFCS and padding configurations.

[0159] FIG. 9(c) illustrates another example of a structure in which an IFCS field is included in a User Info List or some of the User Info fields of a trigger frame. To insert the IFCS into the ICF, two consecutive first User Info fields and a second User Info field may be used, in which the AID12 field is set to a specific value (e.g., '2011'). The first User Info field may be configured to include the lower 24 bits (IFCS[0:23]) of the 32-bit IFCS data. The subsequent second User Info field may include the remaining upper 8 bits (IFCS[24:31]) of the 32-bit IFCS data, indicating continuity with the first User Info field by having the same AID12 value ('2011').

[0160] Padding (or Reserved) bits may be included in the remaining sections of the first and second User Info fields, excluding AID12 and IFCS. After the first and second User Info fields containing the IFCS field, padding bits may be inserted in an amount necessary for the DPS STA to switch from LC mode to HC mode.

[0161] When the receiving STA detects a series of User Info fields where AID12 is set to '2011', it combines the bits stored distributed in each field to restore a 32-bit IFCS, thereby verifying the integrity of the frame received prior to the padding interval.

[0162] Meanwhile, although the DPS operation was illustrated as an example in Fig. 9, the structure of the proposed ICF may also be applied for a Multi-Link Operation (MLO) function that operates simultaneously across multiple frequency bands and / or a Dynamic Subband Operation (DSO) function that dynamically utilizes a wider bandwidth by using auxiliary channel bandwidth.

[0163] Figure 10 is a diagram illustrating the problems that occur when ICR reception fails.

[0164] Referring to FIG. 10, an exemplary situation is illustrated in which STA-1 (1000) transmits an ICF, and STA-2 (1010) successfully receives the ICF and transmits an ICR, but STA-1 (1000) fails to receive the ICR. Here, STA-1 (1000) may be referred to as a TXOP holder, and STA-2 (1010) may be referred to as a TXOP responder. Additionally, similar to the description of FIG. 8, STA-2 (1010) may be a STA with the DPS function enabled (including an AP or non-AP STA) and STA-1 (1000) may be a peer STA of STA-2 (including an AP or non-AP STA), but the scope of the present disclosure is not necessarily limited to a DPS scenario.

[0165] STA-1 (1000) can transmit a first ICF (1002) to STA-2 (1010) after undergoing a backoff (1001) for a certain period. The first ICF (1002) may include an IFCS field and padding, and the specific structure can be described in FIG. 9. STA-2 (1010) and an adjacent STA (1020) can each set a first NAV (1011, 1021) based on the Duration field included in the first ICF (1002).

[0166] STA-2 (1010) successfully receives the first ICF (1002) and transmits the first ICR (1012) to STA-1 (1000) after SIFS, but STA-1 (1000) may not receive the first ICR (1012) due to problems such as channel environment, interference, or other frame errors. On the other hand, an adjacent STA (1020) may successfully receive the first ICR (1012). In another example, if the first ICR (1012) is not transmitted from STA-2 (1010), it may be possible for the adjacent STA (1020) to reset the first NAV (1021) and attempt a medium access contention, assuming that STA-1 (1000) has not successfully secured the TXOP. However, as in FIG. 10, if STA-2 (1010) transmits the first ICR (1012) and the adjacent STA (1020) successfully receives it, the adjacent STA (1020) does not reset the first NAV (1021) and may not perform media access contention during the period of the first NAV (1021).

[0167] STA-1 (1000), having not received the first ICR (1012), determines that it has not secured the TXOP and, after undergoing a backoff (1003) for a certain period, can transmit the second ICF (1004) to STA-2 (1010). Similarly, the second ICF (1004) may include an IFCS field and padding, and the specific structure can be described in FIG. 9. STA-2 (1010) and the adjacent STA (1020) can each set the second NAV (1013, 1022) based on the Duration field included in the second ICF (1004).

[0168] STA-2 (1010) transmits a new ICR (1014) to STA-1 (1000) in response to the second ICF (1004) after SIFS, and STA-1 (1000) can successfully receive it. STA-1 (1000) can perform frame exchange (1005) with STA-2 (1010) after SIFS and transmit and receive data. Likewise, the adjacent STA (1020) may not perform media access contention during the period of the second NAV (1022).

[0169] As such, if STA-1 (1000) fails to receive the ICR even though STA-2 (1010) has transmitted it, and the ICF retransmission procedure is repeated, the adjacent STA (1020) may remain in a waiting state for a relatively long period due to multiple NAV resets, which may reduce the efficiency of wireless medium (WM) usage and cause unnecessary delays. In addition, as mentioned in FIG. 9, if the padding inserted into the ICF has a long length of up to 256 μs, the overhead may increase significantly due to the retransmission of the ICF. Therefore, technical means are required to reduce this unnecessary retransmission overhead and improve the efficiency of medium utilization.

[0170] FIG. 11 is a diagram illustrating an ICR retransmission procedure according to one embodiment of the present disclosure.

[0171] Referring to FIG. 11, an exemplary situation is illustrated in which STA-1 (1100) transmits an ICF, and STA-2 (1110) successfully receives the ICF and transmits an ICR, but STA-1 (1100) fails to receive the ICR. According to the embodiment of FIG. 11, a method is proposed in which STA-2 (1110) retransmits the ICR after PIFS from the time of transmitting the first ICR, and this procedure may be referred to as 'PIFS recovery for ICR'. Here, STA-1 (1100) may be referred to as the TXOP holder, and STA-2 (1110) may be referred to as the TXOP responder. Additionally, similar to the description in FIG. 8, STA-2 (1110) may be a STA with the DPS function enabled (including AP or non-AP STA) and STA-1 (1100) may be a peer STA of STA-2 (including AP or non-AP STA), but the scope of the present disclosure is not necessarily limited to DPS scenarios.

[0172] STA-1 (1100) can transmit an ICF (1102) to STA-2 (1110) after undergoing a backoff (1101) for a certain period. The ICF (1102) may include an IFCS field and padding, and the specific structure can be described in FIG. 9. STA-2 (1110) and an adjacent STA (1120) can each set NAVs (1111, 1121) based on the Duration field included in the ICF (1102).

[0173] STA-2 (1110) successfully receives the ICF (1102) and transmits the first ICR (1112) to STA-1 (1100) after SIFS, but STA-1 (1100) may not receive the first ICR (1112) due to problems such as channel environment, interference, or other frame errors. On the other hand, an adjacent STA (1120) may successfully receive the first ICR (1112). In another example, if the first ICR (1112) is not transmitted from STA-2 (1110), the adjacent STA (1120) may reset the NAV (1121) and attempt a medium access contention, assuming that STA-1 (1100) has not successfully secured the TXOP. However, as in FIG. 11, if STA-2 (1110) transmits the first ICR (1112) and the adjacent STA (1120) successfully receives it, the adjacent STA (1120) does not reset the NAV (1121) and may not perform media access contention during the period of the NAV (1121).

[0174] Subsequently, if STA-2 (1110) does not receive response data and / or frames for the first ICR (1112) during the PIFS period from the time the transmission of the first ICR (1112) is completed, that is, if it is observed that the wireless medium (WM) remains idle during that period, STA-2 (1110) may transmit the second ICR (1113) corresponding to the first ICR (1112) to STA-1 (1100) (i.e., retransmit the ICR).

[0175] At this time, the ICR retransmission of STA-2 (1110) may have at least one of the following features or a combination thereof.

[0176] - Since ICR reception may fail with even a single retransmission, ICR can be retransmitted multiple times in succession if necessary.

[0177] - Since the failure to receive the ICR may be due to channel degradation, the retransmitted ICR can be transmitted with a lower modulation and coding scheme (MCS) to increase the reception success rate of the other party. For example, if the first ICR (1112) is transmitted at a data rate of 24 Mbps, the second ICR (1113) can be transmitted at a data rate of 12 Mbps.

[0178] - The value included in the TXOP subfield within the Duration / ID field and / or SIG (signal) field may be set to be reduced by {PIFS + length of the retransmitted ICR} compared to that of the previous ICR. Here, if, as ICR retransmission is repeated, the value of the TXOP subfield within the Duration / ID value and / or SIG field becomes less than or equal to a specific threshold, it may be difficult to perform normal frame exchange in subsequent TXOPs, and thus the benefit of further ICR retransmission may no longer be significant. Therefore, under such conditions, additional ICR retransmission may be discontinued. The aforementioned specific threshold may be determined, for example, based on the QoS null and the corresponding ACK time length.

[0179] STA-1 (1100) can successfully receive the second ICR (1113), and STA-1 (1100) can perform frame exchange (1103) with STA-2 (1110) after SIFS and transmit and receive data. Likewise, the adjacent STA (1120) can also successfully receive the second ICR (1113) and not perform media access contention during the NAV (1121).

[0180] Consequently, STA-1 (1100) can successfully obtain the TXOP (1104) by receiving the retransmitted response (i.e., the second ICR (1113)) even if it fails to receive the first response to the ICF (1102) (i.e., the first ICR (1112)). By following the procedure described above, overhead due to the repeated transmission of unnecessary ICFs can be prevented and the efficiency of wireless medium (WM) usage can be increased. Additionally, compared to the case where, as described in FIG. 10, when an ICF is retransmitted, adjacent STAs reset the NAV, making long-term media access contention impossible, network latency can be improved without affecting overall fairness among STAs.

[0181] FIG. 12 is a diagram illustrating the operation method of a TXOP holder within an ICR retransmission procedure according to one embodiment of the present disclosure.

[0182] Referring to FIG. 12, an exemplary method is illustrated in which STA-1 (1200) waits for a retransmitted ICR within the aforementioned ICR retransmission procedure or PIFS recovery for ICR procedure. Here, STA-1 (1200) may be referred to as a TXOP holder, and STA-2 (1210) may be referred to as a TXOP responder. Additionally, similar to the description of FIG. 8, STA-2 (1210) may be a STA with the DPS function enabled (including an AP or non-AP STA) and STA-1 (1200) may be a peer STA of STA-2 (including an AP or non-AP STA), but the scope of the present disclosure is not necessarily limited to a DPS scenario.

[0183] STA-1 (1200) can transmit the first ICF (1202) to STA-2 (1210) after a period of backoff (1201). The first ICF (1202) may include an IFCS field and padding, and the specific structure can be described in FIG. 9.

[0184] STA-2 (1210) successfully receives the first ICF (1202) and transmits the first ICR (1211) to STA-1 (1200) after SIFS, but STA-1 (1200) may not receive the first ICR (1211) due to problems such as channel environment, interference, or other frame errors. Subsequently, if STA-2 (1210) does not receive response data and / or frames for the first ICR (1211) during the PIFS period from the time the transmission of the first ICR (1211) is completed, that is, if it is observed that the wireless medium (WM) remains in an idle state during that period, STA-2 (1210) may transmit the second ICR (1212) corresponding to the first ICR (1211) to STA-1 (1200) (i.e., retransmit the ICR).

[0185] As illustrated in FIG. 12(a), if only one ICR retransmission is allowed, STA-1 (1200) may wait (monitor) for reception of an ICR for (SIFS + length of ICR + DIFS) or (SIFS + length of ICR + PIFS + 1 slot time) from the time when the transmission of the first ICF (1202) is completed. If STA-1 (1200) also fails to receive the second ICR (1212) and consequently does not receive any ICR for (SIFS + length of ICR + DIFS) or (SIFS + length of ICR + PIFS + 1 slot time) from the time when the transmission of the first ICF (1202) is completed, STA-1 (1200) may consider that it has failed to acquire a TXOP and may attempt to re-compete on the wireless medium (WM).

[0186] On the other hand, as illustrated in FIG. 12(b), if ICR retransmission is allowed one or more times (n times), STA-1 (1200) may wait (monitor) for reception of ICR for {SIFS + (length of ICR + PIFS)*n + 1 slot time} from the time the transmission of the first ICF (1202) is completed. For example, to calculate the period of waiting for reception of ICR, STA-1 (1200) may assume that the n retransmitted ICRs have the same data rate (or MCS). If STA-1 (1200) fails to receive the nth second ICR (1212n) and consequently does not receive any ICR for {SIFS + (length of ICR + PIFS)*n + 1 slot time} from the time it completes the transmission of the first ICF (1202), STA-1 (1200) may be deemed to have failed to acquire the TXOP and may attempt to re-compete on the wireless medium (WM).

[0187] STA-1 (1200) can transmit the second ICF (1204) to STA-2 (1210) after undergoing a backoff (1203) for a certain period. Similarly, the second ICF (1204) may include an IFCS field and padding, and the specific structure can be described in FIG. 9.

[0188] STA-2 (1210) can successfully receive the second ICF (1204) and, after SIFS, transmit the third ICR (1213) to STA-1 (1200). This time, STA-1 (1200) can successfully receive the third ICR (1213), and STA-1 (1200) can perform frame exchange (1205) with STA-2 (1210) after SIFS and transmit and receive data.

[0189] The following describes exemplary requirements and conditions for enabling the previously described ICR retransmission procedure or the PIFS recovery procedure for ICR.

[0190] For example, if a TXOP holder (e.g., STA-1) does not send any frames to a TXOP responder (e.g., STA-2) even though it has successfully received an ICR, the TXOP responder may conclude that its ICR transmission has failed. Therefore, as a requirement to prevent such errors, if the ICR has been successfully received, the TXOP holder may send frames and / or data to the TXOP responder (or ICR sender) after SIFS from the time the ICR reception ended.

[0191] Additionally, the ICR retransmission procedure or the PIFS recovery procedure for the ICR according to the present disclosure may be applied optionally under specific conditions. For example, the ICR retransmission procedure or the PIFS recovery procedure for the ICR may be applied when the length of padding in the ICF exceeds a specific threshold value (e.g., 200 μs) and / or when the ICF is associated with a specific function (e.g., DPS, eMLSR (enhanced Multi-Link Single Radio), etc.).

[0192] Meanwhile, the following two methods can be considered as mechanisms to enable the ICR retransmission procedure or the PIFS recovery procedure for ICR.

[0193] - Implicit enabling method: When the ICF is transmitted in a unicast form and / or the ICR is transmitted with the same bandwidth as the ICF, an ICR retransmission procedure or a PIFS recovery procedure for the ICR may be applied.

[0194] - Explicit enabling method: Referring to FIG. 9, in an ICF of a type that may include IFCS and padding, one of the Reserved bits in the Common Info field or Special User Info field may be used as 'PIFS recovery enabled for ICR' to indicate whether the ICR retransmission procedure or the PIFS recovery procedure for ICR is enabled. If the STA successfully receives the ICF and the 'PIFS recovery enabled for ICR' bit is set to '1', the STA determines that the ICR retransmission procedure or the PIFS recovery procedure for ICR is enabled and can transmit the ICR. If the wireless medium (WM) is in an idle state during the PIFS from the time the ICR transmission is completed, the STA may retransmit the ICR by decreasing the value included in the TXOP subfield within the Duration / ID field and / or the SIG (signal) field. For example, the value included in the TXOP subfield within the Duration / ID field and / or SIG (signal) field may be set to be reduced by {PIFS + length of the retransmitted ICR} compared to that of the previous ICR.

[0195] FIG. 13 is a diagram illustrating a DPS mechanism without an ICR retransmission procedure and a DPS mechanism with an ICR retransmission procedure applied, according to one embodiment of the present disclosure.

[0196] Referring to FIG. 13, the process of STA-1 (1300) and STA-2 (1310) operating according to the DPS mechanism is illustrated. Here, STA-1 (1300) may be a peer STA (including AP or non-AP STA) of a STA with the DPS function enabled and may be referred to as a TXOP holder. STA-2 (1310) may be a STA (including AP or non-AP STA) with the DPS function enabled and may be referred to as a TXOP responder.

[0197] FIG. 13(a) illustrates a conventional DPS operation method in which an ICR retransmission procedure or a PIFS recovery procedure for ICR is not applied.

[0198] STA-1 (1300) can transmit a first ICF (1302) that enables STA-2 (1310) to transition from LC mode to HC mode after undergoing a backoff (1301) for a certain period. The first ICF (1302) may include an IFCS field and padding, and the specific structure can be described in FIG. 9. STA-2 (1310), which was in the LC mode state, can perform error verification by decoding up to the IFCS field included in the first ICF (1302). If the part up to the IFCS field is successfully received without errors, STA-2 (1310) can start transitioning to HC mode.

[0199] STA-2 (1310), having completed entry into HC mode, can transmit the first ICR (1311) to STA- (1300). The first ICR (1311) can be transmitted after SIFS, when the reception of the first ICF (1302), including padding, is fully completed. However, STA-1 (1300) may not receive the first ICR (1311) due to problems such as the channel environment, interference, or other frame errors. In this case, since the response data and / or frame for the first ICR (1311) is not transmitted to STA-2 (1310), STA-2 (1310) can terminate the HC mode operation and return to LC mode after a transition time to maintain a low-power state.

[0200] Meanwhile, STA-1 (1300), having failed to receive the first ICR (1311), determines that it has not secured the TXOP and, after undergoing a backoff (1303) for a certain period, can transmit the second ICF (1304) to STA-2 (1310). Similarly, the second ICF (1304) may include an IFCS field and padding, and the specific structure can be described by referring to the description in FIG. 9.

[0201] STA-2 (1310) transmits a new ICR (1312) to STA-1 (1300) in response to the second ICF (1304) after SIFS, and STA-1 (1300) can confirm that STA-2 (1310) has transitioned to HC mode by successfully receiving it. Subsequently, STA-1 (1300) can transmit data (1305) based on HC mode. For example, STA-1 (1300) can transmit data (1305) using multiple spatial streams with a bandwidth of 80 MHz or 160 MHz.

[0202] STA-2 (1310) can provide feedback on the reception status of data received from STA-1 (1300) by transmitting a Block Acknowledgement (BA) (1313). For example, the data (1305) may be an Aggregated MPDU (A-MPDU) consisting of one or more MAC Protocol Data Units (MPDUs), and the BA (1313) may be transmitted in the form of a bitmap indicating whether each MPDU in the A-MPDU has been successfully received.

[0203] Afterwards, when frame exchange is complete and there are no more frames to receive, STA-2 (1310) can terminate HC mode operation and return to LC mode after a transition time to maintain a low power state.

[0204] FIG. 13(b) illustrates a DPS operation method to which an ICR retransmission procedure or a PIFS recovery procedure for ICR is applied according to one embodiment of the present disclosure.

[0205] Unlike the conventional DPS mechanism illustrated in FIG. 13(a), if STA-2 (1310) does not receive response data and / or frames for the first ICR (1311) during the PIFS period from the time the transmission of the first ICR (1311) is completed, i.e., if it is observed that the wireless medium (WM) remains idle during that period, STA-2 (1310) can transmit (i.e., retransmit the ICR) a second ICR (1311b) corresponding to the first ICR (1311) to STA-1 (1300) while maintaining HC mode. STA-1 (1300) can secure and maintain a TXOP by successfully receiving the second ICR (1311b) and transmit data (1305) to STA-2 (1310) based on HC mode.

[0206] As described above, when an ICR retransmission procedure or a PIFS recovery procedure for ICR is applied to the DPS mechanism, the DPS STA can retransmit the ICR while maintaining HC mode, thereby avoiding the process of unnecessarily returning to LC mode and then switching back to HC mode. Consequently, power efficiency and quality of service can be simultaneously improved by reducing the overall network delay and the number of mode switches of the DPS STA, and the problem of increased overhead due to the repetition of ICF can also be prevented.

[0207] FIG. 14 is a flowchart illustrating the operation of a first STA of a wireless LAN system according to one embodiment of the present disclosure.

[0208] Referring to FIG. 14, the first STA may perform a series of operations of the STA-2 (810, 1010, 1110, 1210, 1310) illustrated in FIG. 8 and FIG. 10 through 13 described above. The first STA may be a STA with a DPS function enabled (including an AP or non-AP STA) and may be referred to as a TXOP responder. FIG. 14 illustrates an exemplary method that may be implemented according to the principles of the present disclosure, and various modifications may be made to the method illustrated in the flowchart. For example, although illustrated as a series of steps, the various steps in each figure may overlap, occur in parallel, occur in a different order, or occur multiple times. In other examples, each step may be omitted or replaced with another step.

[0209] In step 1410, the first STA can receive an initial control frame (ICF) from the second STA.

[0210] In step 1420, the first STA can transmit the first ICR (initial control response) to the second STA after SIFS (short inter frame space) from the time when reception of the ICF is completed.

[0211] In step 1430, if the wireless medium (WM) is idle from the time the transmission of the first ICR is completed until after the point coordination function inter frame space (PIFS) and ICR retransmission is enabled, the first STA can transmit a second ICR corresponding to the first ICR to the second STA.

[0212] According to one embodiment of the present disclosure, the ICF may include an intermediate frame check sequence (IFCS) field and padding.

[0213] According to one embodiment of the present disclosure, the first STA may switch from an LC (low capability) mode to an HC (high capability) mode when the error verification procedure using the IFCS field is successfully completed. Additionally, the length of the padding may correspond to the time taken to switch from the LC mode to the HC mode.

[0214] According to one embodiment of the present disclosure, the ICF may further include information indicating that the ICR retransmission is enabled.

[0215] According to one embodiment of the present disclosure, the ICF may be received in a unicast form. Additionally, the first ICR and the second ICR may be transmitted at the same bandwidth as the bandwidth at which the ICF was received.

[0216] According to one embodiment of the present disclosure, at least one of the duration field value and the TXOP (transmission opportunity) subfield value within the SIG (signal) field included in the second ICR may be set by reducing at least one of the duration field value and the TXOP subfield value within the SIG field included in the first ICR by the length of PIFS and the second ICR. Additionally, if at least one of the duration field value and the TXOP subfield value within the SIG field included in the second ICR is less than or equal to a specific threshold value, the retransmission of the ICR may be stopped.

[0217] According to one embodiment of the present disclosure, the second ICR may be transmitted based on a data rate lower than the data rate of the first ICR.

[0218] FIG. 15 is a flowchart illustrating the operation of a second STA of a wireless LAN system according to one embodiment of the present disclosure.

[0219] Referring to FIG. 15, the second STA can perform a series of operations of STA-1 (800, 1000, 1100, 1200, 1300) as described in FIG. 8 and FIG. 10 through 13. The second STA may be a peer STA (including AP or non-AP STA) of a STA with a DPS function enabled and may be referred to as a TXOP holder. FIG. 15 illustrates an exemplary method that may be implemented according to the principles of the present disclosure, and various modifications may be made to the method illustrated in the flowchart. For example, although illustrated as a series of steps, the various steps in each figure may overlap, occur in parallel, occur in a different order, or occur multiple times. In other examples, each step may be omitted or replaced with another step.

[0220] In step 1510, the second STA can transmit an initial control frame (ICF) to the first STA.

[0221] In step 1520, the second STA may wait for an ICR from the time when the transmission of the ICF is completed until the time when SIFS (short inter frame space), {ICR (initial control response) length + PIFS (point coordination function inter frame space)}*n, and 1 slot time are added. Here, n may be an integer greater than or equal to 1 representing the number of allowed ICR retransmissions.

[0222] According to one embodiment of the present disclosure, the ICF may include an intermediate frame check sequence (IFCS) field and padding.

[0223] According to one embodiment of the present disclosure, the second STA may determine that it has failed to acquire a TXOP (transmission opportunity) if no ICR is received from the time when the transmission of the ICF is completed until the time when SIFS, {ICR length + PIFS}*n, and 1 slot time are added.

[0224] Methods according to the claims or embodiments described in the specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0225] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to the claims or embodiments described in the specification of this disclosure.

[0226] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, ROM (Read Only Memory), Electrically Erasable Programmable Read Only Memory (EEPROM), magnetic disc storage devices, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0227] Additionally, the program may be stored on an attachable storage device accessible via a communication network such as the Internet, Intranet, Local Area Network (LAN), Wireless LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present disclosure.

[0228] In the specific embodiments of the present disclosure described above, the components included in one embodiment are expressed in a singular or plural form according to the specific embodiment presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed in the singular form, or even if a component is expressed in the singular form, it may be composed in the plural form.

[0229] The flowcharts described above illustrate exemplary methods that may be implemented in accordance with the principles of the present disclosure, and various modifications may be made to the methods illustrated in the flowcharts of this specification. For example, although they are illustrated as a series of steps, the various steps in each figure may overlap, occur in parallel, occur in a different order, or occur multiple times. In other examples, steps may be omitted or replaced with other steps. The values ​​described above are merely examples, and it is fully possible to apply other values.

[0230] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are merely specific examples provided to facilitate the explanation of the technical content of the present disclosure and to aid in understanding the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it is obvious to those skilled in the art that other variations based on the technical concept of the present disclosure are possible. Furthermore, each of the above embodiments may be combined and operated together as needed. For example, parts of one embodiment of the present disclosure and another embodiment may be combined to operate AP and STA.

[0231] Furthermore, the order of description in the drawings illustrating the method of the present invention does not necessarily correspond to the order of execution, and the order of execution may be changed or executed in parallel. Alternatively, the drawings illustrating the method of the present invention may omit some components and include only some components to the extent that the essence of the present invention is not compromised.

Claims

1. A method performed by an electronic device operating as a first STA (station) of a wireless LAN network, A step of receiving an ICF (initial control frame) from the second STA; A step of transmitting a first ICR (initial control response) to the second STA after the SIFS (short inter frame space) from the time when the reception of the above ICF is completed; and A method comprising the step of transmitting a second ICR corresponding to the first ICR to the second STA when the wireless medium (WM) is idle from the time when the transmission of the first ICR is completed until after the point coordination function inter frame space (PIFS) and ICR retransmission is enabled.

2. In Paragraph 1, A method characterized in that the above ICF includes an IFCS (intermediate frame check sequence) field and padding.

3. In Paragraph 2, If the error verification procedure using the above IFCS field is successfully completed, it further includes a step of switching from LC (low capability) mode to HC (high capability) mode, and A method characterized in that the length of the padding corresponds to the time taken to switch from the LC mode to the HC mode.

4. In Paragraph 1, A method characterized in that the above ICF includes information indicating that the above ICR retransmission is enabled.

5. In Paragraph 1, The above ICF is received in a unicast format, and A method characterized in that the first ICR and the second ICR are transmitted with the same bandwidth as the received ICF.

6. In Paragraph 1, At least one of the duration field value and the TXOP (transmission opportunity) subfield value within the SIG (signal) field included in the retransmitted ICR is set by decreasing at least one of the duration field value and the TXOP subfield value within the SIG field included in the previous ICR by PIFS and the length of the retransmitted ICR, and If at least one of the duration field value and the TXOP subfield value within the SIG field included in the retransmitted ICR is less than or equal to a specific threshold value, the retransmission of the ICR is stopped, and A method characterized in that the retransmitted ICR is transmitted based on a data rate lower than the data rate of the preceding ICR.

7. A method performed by an electronic device operating as a second STA (station) of a wireless LAN network, A step of transmitting an ICF (initial control frame) to the first STA; and A method comprising the step of waiting for an ICR from the time when the transmission of the above ICF is completed until the time when SIFS (short inter frame space), {ICR (initial control response) length + PIFS (point coordination function inter frame space)}*n, and 1 slot time are added, wherein n is an integer greater than or equal to 1 representing the number of allowed ICR retransmissions.

8. In Paragraph 7, The method further includes a step of determining that a TXOP (transmission opportunity) has failed to be acquired if no ICR is received from the time when the transmission of the above ICF is completed until the time calculated by adding SIFS, {ICR length + PIFS}*n, and 1 slot time. A method characterized in that the above ICF includes an IFCS (intermediate frame check sequence) field and padding.

9. An electronic device operating as a first STA (station) of a wireless LAN network, Transmitter / receiver; and It includes a control unit, and the control unit, said control unit From the second STA, an ICF (initial control frame) is received through the transceiver, and After the SIFS (short inter frame space) from the time when the reception of the above ICF is completed, the first ICR (initial control response) is transmitted to the second STA through the transceiver, and also An electronic device configured to transmit a second ICR corresponding to the first ICR to the second STA through the transceiver when the wireless medium (WM) is idle from the time the transmission of the first ICR is completed until after the point coordination function inter frame space (PIFS) and ICR retransmission is enabled.

10. In Paragraph 9, The above ICF includes an IFCS (intermediate frame check sequence) field and padding, and The above control unit is further configured to switch from LC (low capability) mode to HC (high capability) mode when the error verification procedure using the IFCS field is successfully completed, and An electronic device characterized in that the length of the padding corresponds to the time taken to switch from the LC mode to the HC mode.

11. In Paragraph 9, An electronic device characterized in that the above ICF includes information indicating that the above ICR retransmission is enabled.

12. In Paragraph 9, The above ICF is received in a unicast format, and An electronic device characterized in that the first ICR and the second ICR are transmitted at the same bandwidth as the received ICF.

13. In Paragraph 9, At least one of the duration field value and the TXOP (transmission opportunity) subfield value within the SIG (signal) field included in the retransmitted ICR is set by decreasing at least one of the duration field value and the TXOP subfield value within the SIG field included in the previous ICR by PIFS and the length of the retransmitted ICR, and If at least one of the duration field value and the TXOP subfield value within the SIG field included in the retransmitted ICR is less than or equal to a specific threshold value, the retransmission of the ICR is stopped, and An electronic device characterized in that the retransmitted ICR is transmitted based on a data rate lower than the data rate of the preceding ICR.

14. An electronic device operating as a second STA (station) of a wireless LAN network, Transmitter / receiver; and It includes a control unit, and the control unit, said control unit The ICF (initial control frame) is transmitted to the first STA through the transceiver, and also An electronic device configured to wait for an ICR from the time when the transmission of the above ICF is completed until the time when SIFS (short inter frame space), {ICR (initial control response) length + PIFS (point coordination function inter frame space)}*n, and 1 slot time are added, wherein n is an integer greater than or equal to 1 representing the number of allowed ICR retransmissions.

15. In Paragraph 14, The control unit is further configured to determine that the acquisition of a TXOP (transmission opportunity) has failed if no ICR is received from the time when the transmission of the ICF is completed until the time when SIFS, {ICR length + PIFS}*n, and 1 slot time are added. The electronic device is characterized in that the above ICF includes an IFCS (intermediate frame check sequence) field and padding.

Images