Wireless communication method for managing mutual interference in device and wireless communication terminal using same

Abstract

Disclosed is a non-AP station which supports a plurality of different communication technologies and communicates with an AP by using a wireless LAN. The non-AP station comprises: a transceiving unit; and a processor. The processor transmits, to the AP, a frame indicating information about an unavailable period of the non-AP station. The unavailable period is a time interval in which communication of the non-AP station is restricted. The information about the unavailable period includes a start time point of the unavailable period and a duration of the unavailable period.

Description

Wireless communication method for managing mutual interference within a device and wireless communication terminal using the same

[0001] The present invention relates to a wireless communication method that supports mutual interference management within a device and a wireless communication terminal using the same.

[0002] With the recent proliferation of mobile devices, wireless LAN (WLAN) technology, which can provide them with fast wireless Internet service, is attracting significant attention. WLAN technology utilizes short-range wireless communication technology to enable mobile devices such as smartphones, tablets, laptops, portable multimedia players, and embedded devices to wirelessly connect to the Internet at home, in businesses, or in specific service areas.

[0003] Since supporting the initial wireless LAN technology using the 2.4 GHz frequency, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 has been commercializing or developing various technology standards. First, IEEE 802.11b supports communication speeds of up to 11 Mbps while using the 2.4 GHz band. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses the 5 GHz band instead of the 2.4 GHz band, thereby reducing the impact of interference compared to the considerably crowded 2.4 GHz band. It also uses OFDM technology to increase communication speeds to up to 54 Mbps. However, IEEE 802.11a has the disadvantage of a shorter communication range than IEEE 802.11b. And IEEE 802.11g, like IEEE 802.11b, uses the 2.4GHz band to achieve a communication speed of up to 54Mbps and satisfies backward compatibility, which has garnered considerable attention. It is also superior to IEEE 802.11a in terms of communication distance.

[0004] And to overcome the limitations of communication speed, which has been pointed out as a vulnerability in wireless LAN, there is IEEE 802.11n, a technical standard established. IEEE 802.11n aims to increase the speed and reliability of networks and extend the operating range of wireless networks. More specifically, IEEE 802.11n supports high throughput (HT) with data processing speeds of up to 540 Mbps or more, and is based on MIMO (Multiple Inputs and Multiple Outputs) technology that uses multiple antennas at both the transmitter and receiver to minimize transmission errors and optimize data rates. In addition, this standard can use a coding method that transmits multiple redundant copies to increase data reliability.

[0005] As wireless LAN becomes more widespread and applications diversify, the need for new wireless LAN systems that support very high throughput (VHT) higher than the data processing speed supported by IEEE 802.11n has arisen. Among these, IEEE 802.11ac supports a wide bandwidth (80MHz to 160MHz) at the 5GHz frequency. Although the IEEE 802.11ac standard is defined only for the 5GHz band, early 11ac chipsets will also support operation in the 2.4GHz band to ensure backward compatibility with existing 2.4GHz band products. Theoretically, according to this specification, multi-station wireless LAN speeds can reach at least 1Gbps and a maximum single-link speed of at least 500Mbps. This is achieved by extending the wireless interface concepts accepted in 802.11n, such as wider radio frequency bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256 QAM). In addition, there is IEEE 802.11ad, which transmits data using the 60 GHz band instead of the existing 2.4 GHz / 5 GHz. IEEE 802.11ad is a transmission standard that provides speeds of up to 7 Gbps using beamforming technology, making it suitable for streaming high-bitrate video such as large amounts of data or uncompressed HD video. However, the 60 GHz frequency band has a disadvantage in that it has difficulty passing through obstacles, so it can only be used between devices in short distances.

[0006] Meanwhile, the IEEE 802.11ax (High Efficiency WLAN, HEW) standard, which follows 802.11ac and 802.11ad as a wireless LAN standard, is nearing completion to provide high-efficiency and high-performance wireless LAN communication technology in high-density environments with densely packed APs and terminals. In an 802.11ax-based wireless LAN environment, high-frequency efficient communication must be provided indoors and outdoors in the presence of high-density stations and APs (Access Points), and various technologies have been developed to achieve this.

[0007] Additionally, development of new wireless LAN standards has begun to increase maximum transmission speeds to support emerging multimedia applications such as high-definition video and real-time gaming. The 7th generation wireless LAN standard, IEEE 802.11be (Extremely High Throughput, EHT), is currently under development with the goal of supporting transmission rates of up to 30 Gbps in the 2.4 / 5 / 6 GHz bands through wider bandwidth, increased spatial streams, and multi-AP cooperation.

[0008] Recently, discussions have begun on Ultra High Reliability (UHR) wireless LAN communication technology, a successor to the 802.11be standard, to overcome reliability issues that have been identified as limitations of wireless LAN. The UHR standard is currently under development with the goal of supporting low latency and low jitter in wireless LAN traffic with a high probability (e.g., greater than 99.9999%).

[0009] An embodiment of the present invention aims to provide a wireless communication method supporting interference management within a device and a wireless communication terminal using the same.

[0010] According to one embodiment of the present invention, a non-AP station supporting a plurality of different communication technologies and communicating with an AP using a wireless LAN includes a transceiver; and a processor. The processor transmits a frame indicating information on an unavailable period of the non-AP station to the AP. The unavailable period may be a time period during which communication of the non-AP station is restricted. Information on the unavailable period may include a start time of the unavailable period and a duration of the unavailable period.

[0011] The frame indicating information about the unavailable section to the AP may be a Multi-STA BlockAck frame or a trigger frame transmitted by the non-AP station to the AP.

[0012] The frame indicating information about the unavailable section to the above AP may indicate cancellation of a previously set unavailable section.

[0013] If the frame indicating information about the unavailable interval to the above AP indicates cancellation of a previously set unavailable interval, the duration of the unavailable interval may be indicated as a pre-specified value.

[0014] The above predefined value may be 0.

[0015] The information of the above unavailable section may include information indicating an alternative operating band in which the non-AP station will operate in the above unavailable section.

[0016] A frame indicating information of the above unavailable section may include information of a plurality of unavailable sections including the above unavailable section.

[0017] The frame indicating information of the above unavailable section is a Multi-STA Block Ack frame, and the value of the Duration field of the frame soliciting transmission of the Multi-STA Block Ack frame can be set based on the value obtained by adding the length of the Per AID TID Info field indicating information of the above unavailable section and the length of the field indicating whether traffic is received.

[0018] According to an embodiment of the present invention, an AP that communicates with a non-AP station supporting a plurality of different communication technologies using a wireless LAN includes a transceiver; and a processor. The processor receives a frame indicating information on an unavailable period of the non-AP station from the non-AP station. The unavailable period may be a time period during which communication of the non-AP station is restricted. Information on the unavailable period may include a start time of the unavailable period and a duration of the unavailable period.

[0019] The frame indicating information about the unavailable section to the AP may be a Multi-STA BlockAck frame or a trigger frame transmitted by the non-AP station to the AP.

[0020] The frame indicating information about the unavailable section to the above AP may indicate cancellation of a previously set unavailable section.

[0021] If the frame indicating information about the unavailable interval to the above AP indicates cancellation of a previously set unavailable interval, the duration of the unavailable interval may be indicated as a pre-specified value.

[0022] The above predefined value may be 0.

[0023] The information of the above unavailable section may include information indicating an alternative operating band in which the non-AP station will operate in the above unavailable section.

[0024] A frame indicating information of the above unavailable section may include information of a plurality of unavailable sections including the above unavailable section.

[0025] The frame indicating information of the above unavailable section is a Multi-STA Block Ack frame, and the processor can set the value of the Duration field of the frame soliciting transmission of the Multi-STA Block Ack frame based on the value obtained by adding the length of the Per AID TID Info field indicating information of the unavailable section and the length of the field indicating whether traffic is received.

[0026] According to an embodiment of the present invention, a method for operating a non-AP station that supports a plurality of different communication technologies and communicates with an AP using a wireless LAN includes a step of transmitting a frame indicating information on an unavailable period of the non-AP station to the AP. The unavailable period may be a time period during which communication of the non-AP station is restricted. Information on the unavailable period may include a start time of the unavailable period and a duration of the unavailable period.

[0027] The frame indicating information about the unavailable section to the AP may be a Multi-STA BlockAck frame or a trigger frame transmitted by the non-AP station to the AP.

[0028] The frame indicating information about the unavailable section to the above AP may indicate cancellation of a previously set unavailable section.

[0029] According to an embodiment of the present invention, a method of operating an AP that communicates using a wireless LAN with a non-AP station that supports a plurality of different communication technologies includes receiving a frame from the non-AP station that indicates information on an unavailable period of the non-AP station. The unavailable period may be a time period during which communication of the non-AP station is restricted. Information on the unavailable period may include a start time of the unavailable period and a duration of the unavailable period.

[0030] The frame indicating information about the unavailable section to the AP may be a Multi-STA BlockAck frame or a trigger frame transmitted by the non-AP station to the AP.

[0031] The frame indicating information about the unavailable section to the above AP may indicate cancellation of a previously set unavailable section.

[0032] One embodiment of the present invention provides a wireless communication method for efficiently supporting interference management within a device and a wireless communication terminal using the same.

[0033] Figure 1 illustrates a wireless LAN system according to one embodiment of the present invention.

[0034] Figure 2 illustrates a wireless LAN system according to another embodiment of the present invention.

[0035] Figure 3 shows the configuration of a station according to one embodiment of the present invention.

[0036] Figure 4 shows the configuration of an access point according to one embodiment of the present invention.

[0037] Figure 5 schematically illustrates the process by which a station establishes a link with an access point.

[0038] Figure 6 shows an example of a CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication.

[0039] FIG. 7 shows various standard generation-specific physical layer protocol data unit (PPDU) formats according to an embodiment of the present invention.

[0040] Figure 8 shows an EHT / UHR PPDU format according to an embodiment of the present invention.

[0041] FIG. 9 shows a transmission / TXOP protection method using an RTS frame and a CTS frame according to an embodiment of the present invention.

[0042] FIG. 10 shows a transmission / TXOP protection method using an MU-RTS frame and a CTS frame according to an embodiment of the present invention.

[0043] FIG. 11 shows that communication between a non-AP station and an AP according to an embodiment of the present invention is affected by mutual interference.

[0044] FIG. 12 shows an operation in which a non-AP station transmits information about an IDC to an AP according to an embodiment of the present invention.

[0045] FIG. 13 shows a station according to an embodiment of the present invention indicating an unavailable channel and performing frame exchange on a channel other than the unavailable channel.

[0046] FIG. 14 shows a specific format of a field included in a frame for indicating an unusable section according to an embodiment of the present invention.

[0047] FIGS. 15 and 16 illustrate signaling of aperiodic IDC to a non-AP station during frame exchange between an AP and a non-AP station according to an embodiment of the present invention.

[0048] FIG. 17 shows that one non-AP station operates in an alternative operating band due to aperiodic IDC during frame exchange between an AP and multiple non-AP stations according to an embodiment of the present invention.

[0049] FIG. 18 shows the operation of the AP and the station when the AP and the station set up a P2P TWT for an unavailable period and an aperiodic IDC occurs according to an embodiment of the present invention.

[0050] FIG. 19 shows the operation of a non-AP station when an aperiodic IDC occurs according to an embodiment of the present invention.

[0051] FIGS. 20 to 22 illustrate operations of a station transmitting information about an updated unavailable section according to an embodiment of the present invention.

[0052] FIG. 23 shows the format of a Multi-STA BlockAck frame including information about an unavailable section according to an embodiment of the present invention.

[0053] FIG. 24 shows an operation of changing a previously set unavailable interval by a station according to an embodiment of the present invention.

[0054] FIG. 25 shows an operation of a station canceling a previously set unavailable section according to an embodiment of the present invention.

[0055] FIG. 26 illustrates an operation in which a non-AP station, which is a TXOP responder, transmits information about multiple unavailable spaces to an AP according to an embodiment of the present invention.

[0056] FIG. 27 illustrates an operation of a non-AP station and an AP setting information regarding multiple unavailable intervals of multiple non-periodic IDCs according to an embodiment of the present invention.

[0057] FIG. 28 illustrates a method for a non-AP station and an AP to update unavailable sections of multiple IDCs according to an embodiment of the present invention.

[0058] Figure 29 shows the format of the Per AID TID Info field according to an embodiment of the present invention.

[0059] FIG. 30 illustrates a method for a non-AP station to determine whether to receive a response frame containing information about an unavailable section according to an embodiment of the present invention.

[0060] FIG. 31 illustrates a method for an AP to receive an ACK response frame and transmit a frame indicating successful reception of the ACK response frame, according to an embodiment of the present invention.

[0061] FIG. 32 illustrates a method in which an AP receives an ACK response frame and indicates successful reception of the ACK response frame by adjusting the interval between the ACK response frame and a PPDU transmitted immediately after the ACK response frame, according to an embodiment of the present invention.

[0062] FIG. 33 shows an operation in which a station continuously transmits information about an unavailable section according to an embodiment of the present invention.

[0063] FIG. 34 illustrates a diagram of an AP and a non-AP station in an unavailable section where some functions are unavailable according to one embodiment of the present invention.

[0064] Figure 35 shows the format of a channel use request frame indicating reception impossibility and transmission impossibility.

[0065] FIG. 36 shows an AP and a non-AP station exchanging information about an unavailable section and performing frame exchange according to the information about the unavailable section according to an embodiment of the present invention.

[0066] Figure 37 shows the format of the Per AID TID Info field according to an embodiment of the present invention.

[0067] FIG. 38 shows the operation of an AP that allocates RUs to a station based on information about unavailable RUs in an unavailable section of the station according to an embodiment of the present invention.

[0068] The terms used in this specification have been selected from widely used and current terms, taking into account the functions of the present invention. However, these terms may vary depending on the intentions of those skilled in the art, customs, or the emergence of new technologies. Furthermore, in certain cases, the applicant may arbitrarily select terms, in which case their meanings will be described in the description of the relevant invention. Therefore, it should be noted that the terms used in this specification should be interpreted based on their substantive meaning and the overall content of this specification, rather than simply their names.

[0069] Throughout the specification, when a component is said to be "connected" to another component, this includes not only the case where the component is "directly connected," but also the case where the component is "electrically connected" with another component intervening therebetween. Furthermore, when a component is said to "include" a particular component, this does not exclude the other component, but rather allows the inclusion of other components, unless specifically stated otherwise. Furthermore, the terms "more than" or "less than" with respect to a specific threshold may be appropriately replaced with "greater than" or "less than", respectively, depending on the embodiment.

[0070] Hereinafter, in the present invention, fields and subfields may be used interchangeably.

[0071] Figure 1 illustrates a wireless LAN system according to one embodiment of the present invention.

[0072] A wireless LAN system includes one or more Basic Service Sets (BSSs), which represent a collection of devices that have successfully synchronized and can communicate with each other. BSSs can generally be categorized as infrastructure BSSs and independent BSSs (IBSSs). Figure 1 illustrates an infrastructure BSS.

[0073] As illustrated in FIG. 1, the infrastructure BSS (BSS1, BSS2) includes one or more stations (STA1, STA2, STA3, STA4, STA5), an access point (AP-1, AP-2) that provides a distribution service, and a distribution system (DS) that connects multiple access points (AP-1, AP-2).

[0074] A station (STA) is any device that includes a medium access control (MAC) and a physical layer interface for a wireless medium that complies with the IEEE 802.11 standard, and broadly includes both non-access point (AP) stations and access points (APs). In addition, the term "terminal" in this specification may refer to a non-AP STA or an AP, or both. A station for wireless communication includes a processor and a communication unit, and may further include a user interface unit and a display unit, depending on the embodiment. The processor may generate a frame to be transmitted through a wireless network or process a frame received through the wireless network, and may perform various other processes for controlling the station. In addition, the communication unit is functionally connected to the processor and transmits and receives frames through the wireless network for the station. In the present invention, a terminal may be used as a term that includes a user equipment (UE).

[0075] An Access Point (AP) is an entity that provides access to a distribution system (DS) via a wireless medium for stations associated with it. In an infrastructure BSS, communication between non-AP stations is in principle performed via the AP, but direct communication is also possible between non-AP stations when a direct link is established. Meanwhile, in the present invention, the AP is used as a concept including a Personal BSS Coordination Point (PCP), and in a broad sense, it can include concepts such as a centralized controller, a base station (BS), a node-B, a base transceiver system (BTS), or a site controller. In the present invention, the AP may also be referred to as a base wireless communication terminal, and the base wireless communication terminal may be used as a term including, in a broad sense, an AP, a base station, an eNodeB (eNB), and a transmission point (TP). In addition, the base wireless communication terminal may include various types of wireless communication terminals that allocate communication medium resources and perform scheduling in communication with multiple wireless communication terminals.

[0076] Multiple infrastructure BSSs can be interconnected via a distribution system (DS). Multiple BSSs connected via the distribution system are referred to as an Extended Service Set (ESS).

[0077] FIG. 2 illustrates an independent BSS, a wireless LAN system, according to another embodiment of the present invention. Parts of the embodiment of FIG. 2 that are identical or corresponding to those of the embodiment of FIG. 1 will not be redundantly described.

[0078] BSS3, illustrated in Figure 2, is an independent BSS and does not include an AP. Therefore, all stations (STA6, STA7) are not connected to an AP. An independent BSS does not allow access to a distribution system and forms a self-contained network. In an independent BSS, each station (STA6, STA7) can be directly connected to another.

[0079] FIG. 3 is a block diagram showing the configuration of a station (100) according to one embodiment of the present invention. As illustrated, the station (100) according to the embodiment of the present invention may include a processor (110), a communication unit (120), a user interface unit (140), a display unit (150), and a memory (160).

[0080] First, the communication unit (120) transmits and receives wireless signals such as wireless LAN packets, and may be built into or externally installed in the station (100). According to an embodiment, the communication unit (120) may include at least one communication module using different frequency bands. For example, the communication unit (120) may include communication modules of different frequency bands such as 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. According to one embodiment, the station (100) may include a communication module using a frequency band of 7.125 GHz or higher and a communication module using a frequency band of 7.125 GHz or lower. Each communication module may perform wireless communication with an AP or an external station according to the wireless LAN standard of the frequency band supported by the corresponding communication module. The communication unit (120) may operate only one communication module at a time or may operate multiple communication modules simultaneously, depending on the performance and requirements of the station (100). When the station (100) includes multiple communication modules, each communication module may be provided in an independent form, or multiple modules may be integrated into a single chip. In the embodiment of the present invention, the communication unit (120) may represent an RF (Radio Frequency) communication module that processes RF (Radio Frequency) signals.

[0081] Next, the user interface unit (140) includes various types of input / output means provided in the station (100). That is, the user interface unit (140) can receive user input using various input means, and the processor (110) can control the station (100) based on the received user input. In addition, the user interface unit (140) can perform output based on a command of the processor (110) using various output means.

[0082] Next, the display unit (150) outputs an image on the display screen. The display unit (150) can output various display objects, such as content executed by the processor (110) or a user interface based on the control commands of the processor (110). In addition, the memory (160) stores a control program used in the station (100) and various data corresponding thereto. Such a control program may include a connection program required for the station (100) to connect to an AP or an external station.

[0083] The processor (110) of the present invention can execute various commands or programs and process data within the station (100). In addition, the processor (110) can control each unit of the above-described station (100) and control data transmission and reception between the units. According to an embodiment of the present invention, the processor (110) can execute a program for connection to an AP stored in the memory (160) and receive a communication setup message transmitted by the AP. In addition, the processor (110) can read information on the priority conditions of the station (100) included in the communication setup message and request connection to the AP based on the information on the priority conditions of the station (100). The processor (110) of the present invention may refer to the main control unit of the station (100), and according to an embodiment, may refer to a control unit for individually controlling some components of the station (100), such as the communication unit (120). That is, the processor (110) may be a modem or modulator and / or demodulator that modulates and / or demodulates wireless signals transmitted and received from the communication unit (120). The processor (110) controls various operations of wireless signal transmission and reception of the station (100) according to an embodiment of the present invention. A specific embodiment thereof will be described later.

[0084] The station (100) illustrated in FIG. 3 is a block diagram according to one embodiment of the present invention, and the blocks shown separately are logically distinguished elements of the device. Accordingly, the elements of the above-described device may be mounted as one chip or as multiple chips depending on the design of the device. For example, the processor (110) and the communication unit (120) may be implemented by being integrated into one chip or may be implemented as separate chips. In addition, in the embodiment of the present invention, some components of the station (100), such as the user interface unit (140) and the display unit (150), may be selectively provided in the station (100).

[0085] Fig. 4 is a block diagram illustrating the configuration of an AP (200) according to one embodiment of the present invention. As illustrated, the AP (200) according to the embodiment of the present invention may include a processor (210), a communication unit (220), and a memory (260). In Fig. 4, redundant descriptions of portions of the configuration of the AP (200) that are identical or corresponding to the configuration of the station (100) of Fig. 3 will be omitted.

[0086] Referring to FIG. 4, the AP (200) according to the present invention has a communication unit (220) for operating a BSS in at least one frequency band. As described above in the embodiment of FIG. 3, the communication unit (220) of the AP (200) may also include a plurality of communication modules that utilize different frequency bands. That is, the AP (200) according to the embodiment of the present invention may include two or more communication modules for different frequency bands, such as 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. Preferably, the AP (200) may include a communication module that utilizes a frequency band of 7.125 GHz or higher and a communication module that utilizes a frequency band of 7.125 GHz or lower. Each communication module may perform wireless communication with a station according to the wireless LAN standard of the frequency band supported by the corresponding communication module. The communication unit (220) may operate only one communication module at a time or may operate multiple communication modules simultaneously, depending on the performance and requirements of the AP (200). In an embodiment of the present invention, the communication unit (220) may represent an RF communication module that processes an RF (Radio Frequency) signal.

[0087] Next, the memory (260) stores the control program used in the AP (200) and various data according to the control program. This control program may include a connection program that manages the connection of the station. In addition, the processor (210) controls each unit of the AP (200) and may control data transmission and reception between the units. According to an embodiment of the present invention, the processor (210) may execute a program for connection with a station stored in the memory (260) and transmit a communication setup message to one or more stations. At this time, the communication setup message may include information on the connection priority conditions of each station. In addition, the processor (210) performs connection setup according to a connection request from a station. According to one embodiment, the processor (210) may be a modem or a modulator and / or demodulator that modulates and demodulates a wireless signal transmitted and received from the communication unit (220). The processor (210) controls various operations of wireless signal transmission and reception of the AP (200) according to an embodiment of the present invention. Specific examples of this will be described later.

[0088] Figure 5 schematically illustrates the process by which a station establishes a link with an access point.

[0089] Referring to FIG. 5, the link between STA (100) and AP (200) is largely established through three stages: scanning, authentication, and association. First, the scanning stage is a stage in which STA (100) acquires access information of the BSS operated by AP (200). Methods for performing scanning include a passive scanning method in which information is acquired only by utilizing a beacon message (S101) periodically transmitted by AP (200), and an active scanning method in which STA (100) acquires access information by transmitting a probe request to AP (S103) and receiving a probe response from AP (S105).

[0090] The STA (100) that successfully receives wireless access information in the scanning step transmits an authentication request (S107a) and receives an authentication response from the AP (200) (S107b) to perform the authentication step. After the authentication step is performed, the STA (100) transmits an association request (S109a) and receives an association response from the AP (200) (S109b) to perform the association step. In this specification, association basically means wireless association, but the present invention is not limited thereto, and association in a broad sense may include both wireless association and wired association.

[0091] Meanwhile, an additional 802.1X-based authentication step (S111) and an IP address acquisition step (S113) via DHCP may be performed. In Fig. 5, the authentication server (300) is a server that processes STA (100) and 802.1X-based authentication, and may be physically connected to the AP (200) or may exist as a separate server.

[0092] Figure 6 shows an example of a CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication.

[0093] A terminal performing wireless LAN communication performs carrier sensing before transmitting data to check whether the channel is busy. If a wireless signal above a certain strength is detected, the channel is determined to be busy, and the terminal delays access to the channel. This process is called clear channel assessment (CCA), and the level that determines whether the signal is detected is called the CCA threshold. If a wireless signal above the CCA threshold received by the terminal is intended for the terminal, the terminal processes the received wireless signal. On the other hand, if no wireless signal is detected on the channel or a wireless signal with a strength lower than the CCA threshold is detected, the channel is determined to be idle.

[0094] When the channel is determined to be idle, each terminal with data to transmit performs a backoff procedure after an IFS (Inter Frame Space) time, such as AIFS (Arbitration IFS) or PIFS (PCF IFS), depending on the status of each terminal. In some embodiments, the AIFS may be used as a configuration to replace the existing DIFS (DCF IFS). Each terminal waits while decreasing the slot time by a random number determined for the terminal during the idle interval of the channel, and a terminal that has exhausted all slot times attempts to access the channel. The period during which each terminal performs the backoff procedure is called a contention window period. At this time, the random number may be referred to as a backoff counter. That is, the initial value of the backoff counter is set by an integer, which is a random number obtained by the terminal. If the terminal detects that the channel is idle during the slot time, the terminal may decrease the backoff counter by 1. Additionally, if the backoff counter reaches 0, the terminal may be permitted to perform channel access on the channel. Accordingly, transmission by the terminal may be permitted if the channel is idle during the AIFS time and the slot time of the backoff counter.

[0095] If a specific terminal successfully accesses the channel, the terminal can transmit data through the channel. However, if the terminal attempting access collides with another terminal, the collided terminals are each assigned a new random number and perform a backoff procedure again. According to one embodiment, the random number newly assigned to each terminal may be determined within a range twice (2*CW) of the random number range (contention window, CW) previously assigned to the terminal. Meanwhile, each terminal performs the backoff procedure again in the next contention window period to attempt access, and at this time, each terminal performs the backoff procedure starting from the slot time remaining in the previous contention window period. In this way, each terminal performing wireless LAN communication can avoid collisions with each other for a specific channel.

[0096] <Various PPDU format examples>

[0097] FIG. 7 shows various standard generation-specific physical layer protocol data unit (PPDU) formats according to an embodiment of the present invention.

[0098] More specifically, FIG. 7(a) illustrates an embodiment of a legacy PPDU format based on 802.11a / g, FIG. 7(b) illustrates an embodiment of a HE PPDU format based on 802.11ax, and FIG. 7(c) illustrates an embodiment of a non-legacy PPDU (i.e., EHT PPDU) format based on 802.11be. In addition, FIG. 7(d) illustrates a detailed field configuration of L-SIG and RL-SIG commonly used in the above PPDU formats.

[0099] Referring to FIG. 7(a), the preamble of a legacy PPDU includes a legacy short training field (L-STF), a legacy long training field (L-LTF), and a legacy signal field (L-SIG). In an embodiment of the present invention, the L-STF, L-LTF, and L-SIG may be referred to as a legacy preamble.

[0100] Referring to FIG. 7(b), the preamble of the HE PPDU additionally includes RL-SIG (Repeated Legacy Short Training field), HE-SIG-A (High Efficiency Signal A field), HE-SIG-B (High Efficiency Signal B field), HE-STF (High Efficiency Short Training field), and HE-LTF (High Efficiency Long Training field) in addition to the legacy preamble. In an embodiment of the present invention, the RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF, and HE-LTF may be referred to as a HE preamble. The specific configuration of the HE preamble may be modified according to the HE PPDU format. For example, HE-SIG-B may be used only in the HE MU PPDU format.

[0101] Referring to FIG. 7(c), the preamble of the EHT PPDU additionally includes, in addition to the legacy preamble, an RL-SIG (Repeated Legacy Short Training field), a U-SIG (Universal Signal field), an EHT / UHR-SIG-A (Extremely High Throughput / Ultra High Reliability Signal A field), an EHT / UHR-SIG-A (Extremely High Throughput / Ultra High Reliability Signal B field), an EHT-STF (Extremely High Throughput Short Training field), and an EHT-LTF (Extremely High Throughput Long Training field). In an embodiment of the present invention, the RL-SIG, EHT-SIG-A, EHT-SIG-B, EHT-STF, and EHT-LTF may be referred to as an EHT preamble. The specific configuration of the non-legacy preamble may be modified according to the EHT PPDU format. For example, EHT-SIG-A and EHT-SIG-B can only be used in some of the EHT PPDU formats.

[0102] In this way, the PPDU used in the UHR standard may have a format similar to the PPDU format used in the EHT standard. This is because the EHT PPDU format defined in 802.11be includes a U-SIG field that multiple wireless LAN generations have agreed to use in common. At this time, the value of the PHY Version Identifier field of the U-SIG field included in the EHT PPDU may be 0, and the value of the PHY Version identifier field of the U-SIG field included in the UHR PPDU may have a non-zero value, such as 1. The EHT PPDU includes an EHT-STF (Extremely High Throughput Short Training field) field in the STF field, and an EHT-LTF (Extremely High Throughput Long Training field) field in the LTF field. The UHR PPDU includes a UHR-STF (Ultra High Reliability Short Training field) field in the STF field, and a UHR-LTF (Ultra High Reliability Long Training field) field in the LTF field.

[0103] The L-SIG field included in the PPDU preamble applies 64FFT OFDM and consists of a total of 64 subcarriers. Of these, 48 subcarriers, excluding the guard subcarrier, DC subcarrier, and pilot subcarrier, are used for L-SIG data transmission. Since L-SIG applies BPSK, Rate=1 / 2 Modulation and Coding Scheme (MCS), it can contain a total of 24 bits of information. Figure 7(d) shows the 24-bit information structure of L-SIG.

[0104] Referring to Fig. 7(d), L-SIG includes an L_RATE field and an L_LENGTH field. The L_RATE field consists of 4 bits and indicates the MCS used for data transmission. Specifically, the L_RATE field indicates one of the transmission speeds of 6 / 9 / 12 / 18 / 24 / 36 / 48 / 54 Mbps, which combine modulation methods such as BPSK / QPSK / 16-QAM / 64-QAM and inefficiencies such as 1 / 2, 2 / 3, and 3 / 4. Combining the information in the L_RATE field and the L_LENGTH field can indicate the total length of the corresponding PPDU. In non-legacy PPDU formats, the L_RATE field is set to the minimum speed of 6 Mbps.

[0105] The L_LENGTH field is allocated in bytes, with a total of 12 bits, allowing for signaling up to 4095. In combination with the L_RATE field, it can indicate the length of the corresponding PPDU. At this time, legacy and non-legacy terminals may interpret the L_LENGTH field in different ways.

[0106] First, the method by which a legacy terminal or non-legacy terminal interprets the length of the PPDU using the L_LENGTH field is as follows. If the value of the L_RATE field is set to indicate 6 Mbps, 3 bytes (i.e., 24 bits) can be transmitted during 4 us, which is the duration of one symbol of 64 FFT. Therefore, by adding 3 bytes corresponding to the SVC field and Tail field to the L_LENGTH field value and dividing this by 3 bytes, which is the transmission amount of one symbol, the number of symbols based on 64 FFT after L-SIG is obtained. Multiplying the obtained number of symbols by 4 us, which is the duration of one symbol, and then adding 20 us required for transmission of L-STF, L-LTF, and L-SIG, the length of the PPDU, i.e., the reception time (RXTIME) is obtained. This can be expressed as a formula as shown in Mathematical Expression 1 below.

[0107]

[0108] At this time, represents the smallest natural number greater than or equal to x. Since the maximum value of the L_LENGTH field is 4095, the length of the PPDU can be set to a maximum of 5.484 ms. A non-legacy terminal transmitting the PPDU must set the L_LENGTH field as in Mathematical Expression 2 below.

[0109]

[0110] Here, TXTIME is the total transmission time that constitutes the corresponding PPDU, as shown in mathematical expression 3 below. In this case, TX represents the transmission time of X.

[0111]

[0112] Referring to the above formulas, the length of the PPDU is calculated based on the rounded value of L_LENGTH / 3. Therefore, for any value of k, three different values ​​of L_LENGTH={3k+1, 3k+2, 3(k+1)} indicate the same PPDU length.

[0113] Referring to Fig. 7(e), the U-SIG (Universal SIG) field continues to exist in EHT / UHR PPDUs and subsequent generation wireless LAN PPDUs, and serves to distinguish which generation of PPDU it is, including EHT / UHR. In addition, the U-SIG field can serve to facilitate spatial reuse of EHT / UHR and subsequent generation wireless LANs. U-SIG is an OFDM 2 symbol based on 64FFT and can convey a total of 52 bits of information. Of these, 43 bits, excluding the 9 bits of CRC / Tail, are largely divided into the VI (Version Independent) field and the VD (Version Dependent) field.

[0114] The VI bit maintains its current bit configuration in the future so that even if a subsequent generation PPDU is defined, current EHT / UHR terminals can obtain information about the PPDU through the VI fields of the PPDU. For this purpose, the VI field consists of PHY version, UL / DL, BSS Color, TXOP, and Reserved fields. The PHY version ID field is 3 bits and sequentially distinguishes EHT / UHR and subsequent generation wireless LAN standards by version. The PHY version ID field of the EHT (11be) PPDU has a value of 000b, and the PHY version ID field of the UHR PPDU has a value other than 000b. The UL / DL field distinguishes whether the PPDU is an uplink / downlink PPDU. BSS Color means an identifier for each BSS defined in 11ax and has a value of 6 bits or more. TXOP stands for Transmit Opportunity Duration transmitted in the MAC header. By adding it to the PHY header, the length of the TXOP containing the corresponding PPDU can be inferred without having to decode the MPDU, and has a value of 7 bits or more.

[0115] The VD field of EHT is signaling information that is only useful for PPDUs of version 11be. It can be composed of fields that are commonly used in any PPDU format, such as PPDU format and BW, and fields that are defined differently for each PPDU format. The PPDU format is a delimiter that distinguishes EHT SU (Single User), EHT MU (Multiple User), EHT TB (Trigger-based), and EHT ER (Extended Range) PPDUs.

[0116] The BW field largely signals five basic PPDU BW options of 20, 40, 80, 160 (80+80), and 320 (160+160) MHz (a BW that can be expressed in the form of an exponential of 20*2 can be called the basic BW), and various remaining PPDU BWs configured through Preamble Puncturing. In addition, some 80 MHz can be signaled in a punctured form after being signaled at 320 MHz. In addition, the punctured and modified channel form can be signaled directly in the BW field, or by using the BW field together with a field that appears after the BW field (for example, a field in the EHT-SIG field). If the BW field is 3 bits, a total of 8 BW signaling is possible, so only a maximum of 3 puncturing modes can be signaled. If the BW field is 4 bits, a total of 16 BW signaling is possible, so the puncturing mode can signal up to 11.

[0117] The VD field of the UHR is a field that indicates signaling information that is only useful for the UHR PPDU. However, the information indicated by each field included in the VD field of the UHR PPDU may be identical to or more extended than the information indicated by the field that plays the same role as the VD field of the EHT (11be). For example, the field indicating the puncturing pattern included in the VD field of the UHR PPDU may indicate a wider variety of patterns than the field indicating the puncturing pattern included in the VD field of the EHT PPDU. Alternatively, the field indicating the puncturing pattern included in the VD field of the UHR PPDU may be interpreted in conjunction with the BW field. This allows for indicating a wider variety of puncturing patterns.

[0118]

[0119] Figure 8 shows an EHT / UHR PPDU format according to an embodiment of the present invention.

[0120] The EHT / UHR PPDU format can be indicated by the PPDU Format field of the U-SIG field of the PPDU. Fig. 8 (a) shows an EHT / UHR SU PPDU according to an embodiment of the present invention. The EHT / UHR SU PPDU is a PPDU used for single-user transmission between an AP and a single station, and may include an EHT-SIG-A field for additional signaling after the U-SIG.

[0121] FIG. 8(b) illustrates an EHT / UHR Trigger-based PPDU according to an embodiment of the present invention. An EHT / UHR Trigger-based PPDU is an uplink PPDU used for transmission in response to a trigger frame, and may not have a separate EHT / UHR-SIG-A field after the U-SIG.

[0122] Figure 8(c) illustrates an EHT / UHR MU PPDU according to an embodiment of the present invention. An EHT / UHR MU PPDU is a PPDU used for transmission to one or more terminals. The EHT / UHR MU PPDU format may include a HE-SIG-B field after the U-SIG field.

[0123] Figure 8(d) illustrates an EHT / UHR ER SU PPDU according to an embodiment of the present invention. The EHT / UHR ER SU PPDU is used for single-user transmission to stations in an extended range. The EHT / UHR ER SU PPDU format allows the U-SIG to be repeated along the time axis.

[0124] The EHT / UHR MU PPDU described through (c) of FIG. 8 can be used by an AP to perform downlink transmission to multiple stations. At this time, the EHT / UHR MU PPDU can include scheduling information for multiple stations to simultaneously receive the PPDU. At this time, the EHT / UHR MU PPDU can convey AID information of the receiver or transmitter of the corresponding PPDU through the user specific field of EHT / UHR-SIG-B. A station that receives the EHT / UHR MU PPDU can perform a spatial reuse operation based on the AID information obtained from the preamble of the PPDU. More specifically, the resource unit allocation (RA) field of EHT / UHR-SIG-B can include information on a resource unit (RU) partitioning form in a specific bandwidth (e.g., 20 MHz) in the frequency domain. Additionally, information about the station assigned to each partitioned resource unit may be conveyed via a user-specific field of EHT / UHR-SIG-B. The user-specific field may include one or more user fields corresponding to each partitioned resource unit.

[0125] Among the multiple resource units divided, the AID of the receiver or sender may be inserted into the user field corresponding to the resource unit in which data transmission is performed. A pre-specified null STA ID may be inserted into the user field corresponding to the remaining resource units in which data transmission is not performed.

[0126] Two or more PPDUs described through FIG. 8 may be indicated by the same PPDU format. For example, the value of the U-SIG PPDU format subfield indicating an EHT / UHR SU PPDU and the value of the U-SIG PPDU format subfield indicating an EHT / UHR MU PPDU may be the same.

[0127] Some fields or some information within a field included in the PPDU format described above may be omitted. This may be referred to as compression mode or compressed mode.

[0128]

[0129] <Wi-Fi 단말의 채널 액세스 방법>

[0130] Wi-Fi terminals (APs, non-AP STAs, etc.) perform communication using unlicensed bands, so before transmitting a frame, they check whether the channel they want to transmit is in use by another device. CSMA (Carrier Sense Multiple Access) is a channel access method in which a terminal that wants to transmit a packet performs carrier sense to check whether the channel is in use by another device, and transmits only if the channel is determined to be idle. Since a terminal using CSMA can perform an action of not attempting transmission at least when it is determined that another device is using the medium (channel) (when it is determined to be busy), the transmission that was initiated first can be protected from other devices.

[0131] However, multiple terminals that recognize that the medium is occupied by another device experience a transmission collision by simultaneously attempting to transmit packets when it is confirmed that the medium occupation from the other device has ended (the medium has changed to Idle). That is, as multiple other terminals simultaneously attempt to transmit packets when a specific terminal attempts to transmit a packet, a terminal that is supposed to receive the packet transmitted by the specific terminal is unable to properly receive and decode the packet that it is supposed to receive due to interference caused by the transmissions performed by the multiple other terminals.

[0132] CSMA / CA (CSMA with collision avoidance) is a channel access mechanism that prevents multiple terminals from simultaneously attempting packet transmission when the medium has changed to Idle, as described above. Terminals accessing the medium (channel) using CSMA / CA attempt to transmit after waiting for a random amount of time when the state of the medium they observe changes to Idle. The random amount of time may be an aslottime (typically 9 microseconds) equal to a random number (random backoff counter) generated by each terminal attempting to transmit. In other words, terminals accessing the medium using CSMA / CA attempt to transmit after waiting for different random amounts of time, so they attempt to transmit at different times, unlike when CSMA alone is used. In this case, when a specific terminal that waited for the shortest random amount of time after the medium changed to Idle attempts to transmit first, other terminals can recognize that the medium has been occupied (changed to busy) by the specific terminal and abort the channel access procedure. At this time, the specific terminal may perform an operation of decreasing the backoff counter maintained by it by 1 every aslottime while the medium is maintained as Idle, and may attempt transmission when the backoff counter becomes 0, or when the aslottime has passed after the backoff counter becomes 0. At this time, the specific terminal that performed the transmission may generate a new random number (new backoff counter) after the transmission is finished, and may attempt transmission when the new random number becomes 0 again, or after it becomes 0.

[0133] The CSMA / CA and random backoff procedures briefly explained above are applied to DCF (Distributed coordination function) and EDCAF (Enhanced distributed channel access), which are the basic functions used by Wi-Fi terminals when attempting to access a channel. Since these are well-known and widely used unlicensed band channel access methods, a more detailed explanation will be omitted.

[0134]

[0135] The DCF and EDCAF utilized by the MAC of the Wi-Fi terminal evaluate the channel status by considering not only the channel status (idle / busy) confirmed by each terminal performing its own physical CS (Carrier Sense) but also the results of a virtual CS. In more detail, even if the result of the physical CS performed on the channel is idle, if the result of the virtual CS is busy, the Wi-Fi terminal considers the channel status to be busy. At this time, the Virtual CS is a channel evaluation method that determines the channel to be busy if the NAV (Network allocation vector) is not 0. The NAV may be a value maintained for future traffic that is predicted to occupy the medium. To explain in more detail, when the MAC of Wi-Fi receives an RTS / CTS frame, it can set the NAV (NAV count) based on the duration information of the received frame, for example, the value of the duration field, and maintain the NAV as a non-zero value for the expected time that the medium will be occupied after the RTS / CTS frame exchange. In other words, the value maintained as NAV decreases over time. If the NAV value of a specific MAC is 0, it can be interpreted that the future traffic recognized by the specific MAC is no longer occupying the medium. If the NAV is 0, the MAC can determine the virtual CS result as Idle. At this time, the MAC of Wi-Fi can also set the NAV based on the duration value obtained from not only the RTS / CTS frame but also other received MAC frames.

[0136] The channel assessment method (determine the state of the medium) that considers the results of the physical CS and virtual CS briefly described above is also one of the well-known Wi-Fi MAC functions, so a detailed explanation is omitted.

[0137]

[0138] <EDCA와 TXOP>

[0139] EDCA provides a mechanism to differentiate and manage traffic into four types of ACs (access categories) according to the characteristics of the traffic. At this time, the four types of ACs are AC_VO (AC Voice), AC_VI (AC Video), AC_BE (AC Best effort), and AC_BK (AC Background), and each AC can have different CW (contention window), TXOP (transmit opportunity), and AIFSN parameters. Simply put, EDCA is a mechanism that differentiates the CW, TXOP, and AIFSN parameters for the four types of ACs and controls the transmission priority of traffic transmitted using each AC. To this end, EDCA can map traffic (MSDU) that the MAC must service to one of the four ACs according to the TC (traffic category) or TS (traffic stream). At this time, the traffic mapped to one of the four ACs by EDCA is divided and managed into four queues for each AC. At this time, the four queues may be logically separated rather than physically separated.

[0140] AC_VO is an AC that can be utilized for traffic that is vulnerable to transmission delays, although the absolute volume of traffic, such as voice traffic, is not large. It has relatively small CW and AIFSN parameter values ​​to increase the probability of being serviced preferentially over traffic from other ACs. The TXOP parameter of AC_VO is limited to a relatively small value compared to the TXOP parameters of other ACs, ensuring only a shorter transmission time than other ACs.

[0141] AC_VI is an AC that is more delay-tolerant than voice traffic, but can still be used for low-latency transmission and high-volume traffic such as video. AC_VI has larger CW and AIFSN parameter values ​​than AC_VO but smaller than other ACs. However, its TXOP is about twice as long as AC_VI.

[0142] AC_BE is an AC that can be utilized for traffic that is robust to transmission delays, and most general traffic, excluding voice data and streaming video data, can be classified as AC_BE. AC_BE uses CW and AIFSN parameters with values ​​greater than AC_VO and AC_VI. In addition, AC_BE does not have a separate TXOP. Therefore, traffic corresponding to AC_BE cannot be utilized in the TXOP transmission sequence, which transmits a PPDU, receives an ACK in response, and then transmits a PPDU again after SIFS.

[0143] AC_BK, similar to AC_BE, is a delay-tolerant traffic, but can be utilized for lower-priority traffic than BE traffic. AC_BK utilizes the same CW parameter values ​​as AC_BE, and the AIFSN parameter values ​​are larger than those of AC_BE. In addition, traffic corresponding to AC_BK does not have a separate TXOP like AC_BE, so it cannot be utilized in the TXOP transmission sequence.

[0144] The four types of EDCA AC described above are mapped to the UP (user-priority) of 802.1D, and the EDCA AC is determined based on the UP value of the traffic received through the wire or the TID of the MSDU indicated from the upper layer. At this time, if the TID of the MSDU indicates a value between 0 and 7, the value indicated by the TID can correspond one-to-one with the UP.

[0145] In addition, the four types of EDCA AC described above have default CW (CWmin, CWmax), AIFSN, and TXOP parameters defined in the standard, and the parameter values ​​of each AC can be changed by the AP, so that different values ​​can be used for each BSS.

[0146]

[0147] Using the EDCA mechanism, Wi-Fi traffic is stored in one of four queues corresponding to four ACs, and can be transmitted to the destination device only if the AC containing the traffic wins the channel access competition with other ACs. At this time, in the channel access competition between ACs, each AC competes using its assigned access parameters (CW[AC], AIFSN[AC]), and the channel access competition operation performed by each AC is identical to DCF. At this time, if a specific AC does not have any traffic to transmit in its queue, the specific AC may not participate in the competition.

[0148] However, as described above, since the CW and AIFSN parameter values ​​utilized by each AC are different, the AC_VO with the smallest CW and AIFSN parameters is more likely to win the channel access competition with other ACs, and thus the traffic of AC_VO is more likely to be serviced with priority over the traffic of other ACs.

[0149] In addition, the EDCA mechanism stipulates internal competition rules such as when an (internal) collision occurs between ACs, the AC with a higher priority wins, and increases the CW of the other AC that caused the collision, and rules for composing a PPDU including traffic from an AC other than the AC that won the competition (primary AC), but a detailed description is omitted because it is not closely related to the proposal of the present invention.

[0150] As described above, EDCA provides the EDCA TXOP (EDCA Transmission Opportunity) function along with the function of operating differentiated ACs according to the type of traffic (frames, packets, etc.) to enhance QoS. EDCA TXOP refers to the time during which the EDCAF (EDCA Function) of a specific AC can control the medium without being disturbed by other devices during the TXOP period (duration) when it obtains a channel access opportunity, i.e., becomes a TXOP holder. At this time, the EDCA TXOP may be limited by the TXOP limit advertised by the AP. The TXOP holder must ensure that its own transmission and the transmission of the response frame responded to by its own transmission can be terminated within the TXOP limit.

[0151] A TXOP holder can transmit multiple frames (multiple PPDUs) during an EDCA TXOP period. If the transmission of each frame is performed within the acquired TXOP period, the TXOP holder can transmit multiple frames continuously without performing a separate channel access procedure, such as a backoff procedure, between transmissions of each frame. At this time, if the multiple frames are MPDUs or A-MPDUs (Aggregated MAC protocol data units) that do not request an immediate ack, the transmission of the multiple frames can be performed at an interval of a short interframe space (SIFS) or a reduced interframe space (RIFS). At this time, if there is an MPDU or A-MPDU requesting an immediate ack among the multiple frames, the TXOP holder can transmit a frame requesting an immediate ack, receive the ack, and transmit the next frame after an SIFS.

[0152] At this time, traffic (packets, frames, etc.) of other ACs other than the specific AC that is the TXOP holder may also be transmitted together within the TXOP acquired by the TXOP holder (specific AC) when certain conditions are satisfied. The transmission of traffic of other ACs other than the TXOP holder within the TXOP may be an operation due to TXOP sharing between ACs, and detailed information regarding the above-mentioned certain conditions is omitted because it is not related to the present invention.

[0153]

[0154] As described above, a TXOP holder can perform continuous frame transmission without performing a separate channel access procedure within the TXOP. This may be an operation that can be achieved when other terminals understand and protect the TXOP interval acquired by the TXOP holder. In other words, in order for the TXOP holder to acquire medium control authority for the EDCA TXOP interval, a procedure may be required to notify other terminals of the acquired TXOP interval so that they can recognize it.

[0155] To this end, a terminal (AC) that becomes a TXOP holder or initiates transmission after completing a channel access procedure may attempt to allow other terminals to recognize the TXOP section by transmitting an RTS frame. At this time, the RTS frame means a frame in which the Type subfield (the fourth bit (B3), the third bit (B2) of the Frame Control field) of the Frame Control field of the MAC frame header is set to 01b (Type = Control frame) and the Subtype subfield (the eighth bit (B7), the seventh bit (B6), the sixth bit (B5), the fifth bit (B4) of the Frame Control field) is set to 1011b. Another terminal that receives an RTS frame from a TXOP holder may set an NAV based on information related to the duration included in the RTS frame, for example, the value of the Duration field. The set NAV may be maintained as a non-zero value for a time corresponding to the TXOP of the TXOP holder. However, the terminal indicated as the destination device of the RTS frame must respond with a CTS frame instead of setting the NAV based on the information in the RTS frame. At this time, the destination device of the RTS frame transmitted to start TXOP is a TXOP responder and must transmit a CTS frame in response to the RTS (SIFS after the RTS frame is received). At this time, the Duration field of the responding CTS frame is set to a value calculated as the value indicated in the Duration field of the received RTS frame - the CTS frame transmission time - SIFS. The terminals receiving the CTS frame can set the NAV based on information related to the duration included in the CTS frame (e.g., the value of the Duration field).

[0156] Therefore, the NAV of the terminal that received the RTS frame from the TXOP holder and the terminal that received the CTS frame from the TXOP responder are set to 0 after the TXOP acquired by the TXOP holder ends. This allows the Wi-Fi MAC mechanism to protect the TXOP holder and the TXOP responder from exchanging multiple frames without interruption during the TXOP.

[0157] However, if the TXOP holder transmits an RTS frame as a non-HT duplicate PPDU over the primary 80 MHz band, but the CTS frame (non-HT duplicate PPDU) responded to by the TXOP responder is responded to only in the primary 40 MHz band, the TXOP holder may use only the bandwidth of the primary 40 MHz or less than the primary 40 MHz, for example, the primary 20 MHz, for frame exchange during the acquired TXOP. The CH_BANDWIDTH (a type of TXVECTOR parameter) of the PPDU transmitted by the TXOP holder shall be set to a value equal to or smaller than the CH_BANDWIDTH_IN-NON_HT (a type of RXVECTOR parameter) of the received CTS frame. In this case, the RTS frame may be an RTS frame that allows the CTS frame to be responded to in a BW smaller than the BW in which the RTS frame was transmitted. An RTS frame may be an RTS frame transmitted with DYN_BANDWIDTH_IN_NON_HT (a type of TXVECTOR parameter) set to Dynamic. If DYN_BANDWIDTH_IN_NON_HT is set to Static and the RTS frame is transmitted from a TXOP holder, the TXOP responder may have to respond with a CTS frame with the same BW as the BW in which the RTS frame was received.

[0158]

[0159] FIG. 9 shows a transmission / TXOP protection method using an RTS frame and a CTS frame according to an embodiment of the present invention.

[0160] Before transmitting a PPDU, the first station (STA1) transmits an RTS frame to the second station (STA2), which is the destination device of the PPDU, and the second station (STA2) recognizes that the received RTS frame is an RTS frame destined for itself and responds with a CTS frame after SIFS.

[0161] STA1_Neighbor, a neighbor station of the first station (STA1), sets the NAV based on the value indicated by the Duration field of the RTS frame after receiving the RTS frame transmitted by the first station (STA1). STA2_Neighbor, a neighbor station of the second station (STA2), sets the NAV based on the information indicated by the Duration field of the CTS frame after receiving the CTS frame transmitted by the second station (STA2). STA1_Neighbor and STA2_Neighbor determine that the virtual CS is busy while the set NAV (counter) is maintained at a non-zero value after receiving the RTS / CTS frame, and perform actions such as not decreasing the backoff counter. As a result, the neighboring terminals that received the RTS / CTS frame do not attempt transmission during the period in which the NAV is maintained at a non-zero value. Therefore, the first station (STA1) and the second station (STA2) may not be disturbed by surrounding terminals while exchanging PPDU and Ack frames.

[0162] Even if the first station (STA1) and STA2_Neighbor are in a relationship where signals due to each other's transmissions are not detected (hidden), STA2_Neighbor can perform an operation that takes into account that the channel (channel, WM, Wireless medium) is in use while the first station (STA1) transmits a PPDU.

[0163]

[0164] <MU-RTS 트리거 프레임을 이용한 TXOP 보호>

[0165] 11ax (6th generation Wi-Fi, Wi-Fi6, HEW, High Efficiency WLAN) defines the MU-RTS Trigger / CTS frame exchange procedure, and adds a function that enables the AP to start TXOP and protect the TXOP frame exchange procedure using the MU-RTS trigger frame (hereinafter referred to as MU-RTS, MU-RTS frame). The MU-RTS frame is a type of trigger frame. When the MU-RTS frame is received, the station whose AID12 (the LSB 12 bits of the Association ID) is indicated in the User field included in the MU-RTS frame simultaneously responds with a CTS frame. When the AP protects the TXOP using the MU-RTS frame, since multiple stations respond with CTS frames, the TXOP can be protected from the peripheral devices of each of the multiple stations that are the destination devices of the DL MU PPDU (Down link multi-user PPDU). In addition, the MU-RTS frame can be used to protect the UL MU PPDU. In more detail, before requesting a TB (Trigger based) PPDU from multiple stations through a trigger frame, the AP can transmit an MU-RTS frame to cause multiple stations that will respond to the TB PPDU to respond with a CTS frame. At this time, the CTS frames responded to by the multiple stations induce the surrounding stations of each station to set a NAV that protects the TB PPDU and the Ack frame (Ack, Block Ack, etc.) to be transmitted after the TB PPDU, and through this, legacy stations STAs that cannot recognize (interpret, decode) the trigger frame and TB PPDU may not perform channel access during the packet exchange sequence period (or TXOP) initiated through the trigger frame.

[0166]

[0167] FIG. 10 shows a transmission / TXOP protection method using an MU-RTS frame and a CTS frame according to an embodiment of the present invention.

[0168] In the embodiment of FIG. 10, before transmitting an MU PPDU, the AP transmits an MU-RTS frame to the first station (STA1) and the second station (STA2), which are the destination devices of the MU PPDU, and the first station (STA1) and the second station (STA2) receive the MU-RTS frame and, after SIFS, each respond to the MU-RTS frame with a CTS frame.

[0169] STA1_Neighbor, a neighboring station of the first station (STA1), sets its NAV based on the information indicated by the Duration field of the CTS frame after receiving the CTS frame transmitted by the first station (STA1). STA2_Neighbor, a neighboring station of the second station (STA2), sets its NAV based on the information indicated by the Duration field of the CTS frame after receiving the CTS frame transmitted by the second station (STA2). STA1_Neighbor and STA2_Neighbor perform operations such as not decreasing the backoff counter, assuming that the Virtual CS (Virtual Carrier Sense) is busy while the NAV (counter) set after receiving the CTS frame remains at a non-zero value. Therefore, neighboring terminals that have received the CTS frame do not attempt to transmit during the period in which the NAV remains at a non-zero value. This allows the AP to transmit MU PPDUs and the first station (STA1) and the second station (STA2) to transmit Ack frames without being interrupted by surrounding terminals.

[0170] The trigger frame described above is a frame type defined in 11ax, and is a frame type in which the Type (fourth bit (B3) and third bit (B2)) and Subtype (eighth bit (B7), seventh bit (B6), sixth bit (B5), and fifth bit (B4)) subfields of the Frame Control field are set to 01b and 0010b, respectively. A trigger frame is a frame of Control Type in which the Type subfield of the Frame Control field is 01b, and the Subtype value 0010 indicates that it is a Trigger frame type. In 11ax, a trigger frame is defined so that an AP can request a response frame for multiple stations at once, and an MU-RTS frame is used so that an AP can request a CTS frame for multiple stations (non-AP STAs). Trigger Types other than the MU-RTS frame include the Basic Tigger frame requesting UL MU PPDU, the Beamforming Report Poll Tigger frame requesting Beamforming Report, the MU-BAR Tigger frame (BlockAck request), the BSRP trigger frame requesting Buffer Status Report, the GCR MU-BAR trigger frame, the Bandwidth Query Report Poll (BQRP) trigger frame, and the NDP Feedback Report Poll trigger frame. Trigger Types other than the MU-RTS frame are not related to the content of the present invention, so a detailed description thereof is omitted.

[0171]

[0172] In-device coexistence

[0173] As demand for wireless connectivity continues to surge, wireless devices are increasingly utilizing multiple wireless technologies simultaneously. Consequently, wireless LAN, Bluetooth, and Ultra-wideband (UWB) are all present simultaneously. Interference can occur within a single device, resulting from the sharing of resources between multiple wireless technologies. This is referred to as in-device coexistence interference (IDC interference). This interference can delay or even cause wireless communication to fail. A WLAN communication method that mitigates the effects of this interference is needed. Figures 11 through 38 illustrate a method for a station supporting multiple communication functions to communicate using WLAN.

[0174] FIG. 11 shows that communication between a non-AP station and an AP according to an embodiment of the present invention is affected by mutual interference.

[0175] In the embodiment of FIG. 11, the AP and a non-AP station (STA) exchange an initial control frame (ICF) and a response frame (ICR), and the AP transmits a DL PPDU to the non-AP station (STA). The non-AP station (STA) transmits an ACK frame to the AP, and the AP transmits a DL PPDU again. At this time, an IDC occurs in the non-AP station (STA), making wireless LAN communication impossible. At this time, the AP may continue to attempt to transmit the DL PPDU. In this way, communication efficiency may be reduced due to the IDC. To prevent this, the non-AP station may transmit information regarding the time period during which wireless LAN frame exchange is impossible due to the IDC.

[0176] Cases where wireless LAN frame exchange is not possible due to IDC include cases where another wireless communication device within the device uses the same frequency resources as the wireless LAN, and cases where another wireless communication device within the device uses the same hardware resources as the wireless LAN. Specifically, wireless communication devices using unlicensed bands use the 2.4 GHz and 5 GHz bands. Therefore, when one unlicensed band wireless communication device uses a frequency band, the wireless LAN device may not be able to use that frequency band. Furthermore, the number of antennas included in a device that includes wireless LAN is limited, and multiple wireless devices can share antennas. For example, if a wireless LAN device uses all four antennas and a Bluetooth device uses two antennas, the wireless LAN device can only use two antennas. Furthermore, interference between antennas may occur in these cases.

[0177] In this way, in certain situations, IDC may cause wireless LAN performance to degrade or wireless LAN communication to become impossible. A station, such as a non-AP station, may transmit information regarding the occurrence of an IDC. Specifically, the non-AP station may transmit information regarding the occurrence of an IDC to the non-AP station's counterpart AP. The counterpart AP may be an AP that is currently communicating with the non-AP station or an AP with which the non-AP station is attempting to initiate communication. The information regarding the occurrence of an IDC may include at least one of information regarding a time interval during which an IDC may occur and information regarding frequency resources. The information regarding the time interval may include at least one of information regarding the start time and duration of the time interval. The information regarding the frequency resources may include information regarding a frequency band. This prevents other stations from attempting to communicate with the station via wireless LAN during a time interval during which an IDC may occur. For convenience of explanation, the time interval during which wireless LAN communication is impossible due to an IDC is referred to herein as an unavailable interval.

[0178]

[0179] <IDC의 종류>

[0180] IDC can be classified as periodic IDC or aperiodic IDC depending on whether the IDC is scheduled to occur. If the IDC is scheduled to occur, for example, if the occupation of radio resources by other wireless devices is predicted or scheduled periodically, it can be classified as periodic IDC. Other IDC can be classified as aperiodic IDC. Specifically, an IDC that is not predicted or scheduled periodically can be called aperiodic IDC. A station, such as a non-AP station, transmits information about the unavailable period of the station's periodic IDC to another station, such as an AP, and the other station can communicate with the station based on the information about the unavailable period of the periodic IDC. Specifically, other stations may not attempt to communicate with the station during the time period in which the station's periodic IDC occurs. In these embodiments, a station can indicate information about the time period in which communication is unavailable using a peer-to-peer (P2P) target wake time. A station that has received information about a P2P target wake time can determine that the station that indicated the P2P (Peer-to-Peer) target wake time is unable to transmit or receive wireless LAN data during that time period.

[0181] Aperiodic IDC can occur unexpectedly. For example, while an AP, which holds a TXOP, is transmitting a DL PPDU to a non-AP station within the TXOP, the non-AP station may register the use of a different wireless technology, such as Bluetooth or UWB. This causes an aperiodic IDC, and the non-AP station may not be able to receive the DL PPDU transmitted from the AP. To prevent this, a method for signaling information regarding the unavailable interval of the aperiodic IDC is needed.

[0182] If a heterogeneous wireless technology is activated within a station that has transmitted information regarding a periodic IDC unavailability interval, the station may determine that an aperiodic IDC has occurred. For example, a station may signal a periodic IDC due to UWB to the AP, and Bluetooth may be activated on the station. In such cases where periodic and aperiodic IDC occur simultaneously, the station may need a method to deal with this.

[0183] Additionally, a scheduled periodic IDC may be canceled. For example, Bluetooth in use at a station may be deactivated. In such cases, a method is needed to notify that a signaled periodic IDC has been canceled. The station may indicate that a previously signaled periodic IDC will not occur. Specifically, the station may indicate that WLAN communication is possible during the time period corresponding to the previously signaled periodic IDC. In such embodiments, the station may include information indicating a change in the previously signaled periodic IDC in the response frame. Specific operations of the station will be described below.

[0184]

[0185] <Periodic IDC Instruction Method>

[0186] A station experiencing IDC can indicate information regarding wireless LAN communication failure to its counterpart station. In this specification, the counterpart station may refer to another station with which the station is currently communicating or another station with which the station is attempting to communicate. Specifically, the station may be a non-AP station receiving a DL PPDU. In this case, the counterpart station may be a peer non-AP station or an AP. Alternatively, the station may be a non-AP station transmitting a DL PPDU. In this case, the counterpart station may be a peer AP or a non-AP station. During the time period indicated by the wireless LAN communication failure information, the counterpart station may perform other operations instead of communicating with the station. This can improve communication efficiency.

[0187] A station may transmit a frame containing information regarding a periodic IDC unavailability interval to a counterpart station. The information regarding the IDC may include at least one of a start time of the communication unavailability interval, a duration of the communication unavailability interval, and information regarding a frequency resource to which the communication unavailability interval applies. The information regarding the frequency resource may be information indicating a frequency band. The counterpart station may schedule resource allocation based on the information regarding the communication unavailability interval. In these embodiments, the station may indicate the information regarding the IDC using at least one of a Channel Usage element, an Individual TWT parameter, and a channel unavailability of a P2P Wake Time TWT.

[0188] IDC can only occur in some subchannels within the operating bandwidth of a station. The station can indicate the subchannels within the operating bandwidth where IDC occurs. Specifically, the station can indicate the subchannels where IDC occurs in 20MHz subchannels. In a specific embodiment, the station can indicate whether IDC occurs for each subchannel within the operating bandwidth. By indicating information about frequency resources in this way and indicating the subchannels where IDC occurs in units of subchannels within the operating frequency band, the station can maximize the use of frequency resources within the operating bandwidth when communicating with the opposing station.

[0189] The other station may attempt to exchange frames with the station on frequency resources indicated by the station as available, e.g., on available subchannels, in the time interval indicated by the station.

[0190] FIG. 12 shows an operation in which a non-AP station transmits information about an IDC to an AP according to an embodiment of the present invention.

[0191] As described above, a station can indicate information related to IDC using the P2P target wake time. Specifically, the station can transmit a channel usage request frame indicating periodic IDC. The channel usage request frame can include the start time of the unavailable period, the duration, and the interval between the unavailable periods. In addition, the channel usage request frame can include information about the channel to which the unavailable period applies. The channel usage request frame can include a TWT element. In this case, the TWT element can be an Individual TWT element. The TWT element can indicate a time period during which wireless LAN communication of the station is unavailable. Specifically, the TWT element can indicate the start time and period of the time period. In addition, the TWT Flow Identifier subfield of the TWT element can indicate an identifier of the periodic IDC. The channel usage request frame can include a Channel Usage element. In this case, the value of the Usage mode field of the Channel Usage element can be set to 3.

[0192] A counterpart station that receives a channel use request frame including a TWT element may transmit a channel use response frame indicating that it accepts the periodic IDC information indicated by the channel use request frame. At this time, the counterpart station may set the value of the TWT Setup Command field of the Request Type field of the channel use response frame to a value indicating TWT acceptance. In addition, the counterpart station may set the values ​​of the remaining fields of the channel use response frame to be the same as the values ​​of the fields of the channel use request frame. If the value of the TWT Setup Command field of the channel use response frame indicates TWT acceptance, the station may determine that P2P TWT is approved by the counterpart station.

[0193] Based on the channel use request frame, the opposing station can determine the start time, duration, and interval between the impossible sections. Furthermore, based on the channel use request frame, the opposing station can obtain information about the channel to which the impossible section applies. The opposing station can transmit data to the station in a section other than the impossible section indicated by the P2P TWT. Furthermore, the opposing station may not transmit to the station in the impossible section indicated by the P2P TWT.

[0194] When information about the unavailable interval of a periodic IDC changes, a station can transmit information about the changed unavailable interval of a periodic IDC to a counterpart station using the TWT element of a channel use request frame. At this time, the station can specify which P2P TWT information is changed using the value of the TWT Flow Identifier subfield. The counterpart station can update information about the P2P TWT specified by the received channel use request frame. The station can transmit the value of the TWT Setup Command field of the channel use response frame to the other station by setting it to a value indicating TWT acceptance.

[0195] In the embodiment of FIG. 12, the first non-AP station (STA 1) transmits a channel usage request frame indicating the periodic IDC of the first non-AP station (STA 1) to the AP. The channel usage request frame indicates the time interval in which the periodic IDC occurs as an unusable time interval. The AP accepts the P2P TWT indicating the unusable interval by transmitting a channel usage response frame in response to the channel usage request frame transmitted by the first non-AP station (STA 1). The AP transmits data frame exchanges excluding the unusable interval corresponding to the P2P TWT. In addition, when information regarding the unusable interval of the periodic IDC is changed, the first non-AP station (STA 1) transmits a channel usage request frame indicating information regarding the changed unusable interval of the periodic IDC to the AP. The AP accepts the P2P TWT indicating the updated unavailable interval by transmitting a channel use response frame in response to the channel use request frame transmitted by the first non-AP station (STA 1). FIG. 13 illustrates a station indicating an unavailable channel and performing frame exchange on a channel other than the unavailable channel according to an embodiment of the present invention.

[0196] As described above, a station can indicate to a counterpart station the channel to which the unavailable period applies. Specifically, the station can use a channel usage request frame to indicate to the counterpart station the channel to which the unavailable time period applies. In another specific embodiment, the station can use a newly defined frame to indicate to the counterpart station the channel to which the unavailable time period applies. In these embodiments, the station can transmit to the counterpart station information indicating whether to move out of the operating bandwidth during the unavailable period. At this time, the station can include in the channel usage request frame information regarding the alternative operating bandwidth on which the station will operate during the unavailable period. Specifically, the usage request frame can use a bitmap to indicate the channel indicating the alternative operating bandwidth. Furthermore, the usage request frame can use a bitmap to indicate the channel to which the unavailable period applies. Furthermore, some of the reserved bits of the TWT element can indicate whether the alternative operating bandwidth is used. The Channel Usage element can indicate whether the operating bandwidth is used and the channel to which the unavailable period applies. The channel indicated by the alternative operating bandwidth can be limited to channels included in the bandwidth of the BSS to which the station belongs. If the channel indicated by the alternate operating bandwidth is outside the bandwidth of the BSS to which the station belongs, the field indicating the alternate operating bandwidth may be judged as a reserved bit.

[0197] The point in time at which the station transitions to the alternative operating bandwidth may be a pre-specified point in time. The pre-specified point in time may be prior to the start of the unavailable period. In another specific embodiment, the pre-specified point in time may be the start of the unavailable period. In another specific embodiment, the pre-specified point in time may be within a pre-specified time interval from the start of the unavailable period. The pre-specified time interval may be a channel switching delay. Furthermore, the channel switching delay is the time required for the station to switch between the operating bandwidth and the alternative operating bandwidth.

[0198] The opposing station may transmit an initial control frame to the station. If the opposing station receives a response frame to the initial control frame from the station, the opposing station may determine that the station has switched to an alternate operating bandwidth. The station may transmit a response frame in the RU allocated to the station by the opposing station in the alternate operating bandwidth. If the station switches to the transition bandwidth before the unavailable interval, the initial control frame may not include a padding field set based on the station's channel switching delay.

[0199] In these embodiments, the station may return to the operating bandwidth from the alternative operating bandwidth when or before the unavailable interval ends. When the unavailable interval ends, if frame exchange in the alternative operating bandwidth has not been completed, the station may return to the operating bandwidth after the frame exchange is completed. In this case, the opposing station may determine that the station has returned to the operating bandwidth when a channel change delay has elapsed from the time point of the frame exchange end. The channel change delay may be indicated by a type of element indicating the station's capability.

[0200] In the embodiment of FIG. 13, a first non-AP station (STA1) and a second non-AP station (STA2) are associated with an AP. The operating bandwidth of the first non-AP station (STA1) is 40 MHz. The first non-AP station (STA1) establishes a P2P TWT with the AP by indicating that periodic IDC occurs in the 40 MHz bandwidth. According to the embodiments described above, the first non-AP station (STA1) can indicate an alternative operating bandwidth to the AP. The AP obtains a TXOP and attempts to transmit data to the first non-AP station (STA1) and the second non-AP station (STA2). The AP transmits an initial control frame (ICF) to the first non-AP station (STA1) and the second non-AP station (STA2). At this time, the initial control frame may be a trigger frame. For example, the initial control frame may be either an MU-RTS trigger frame or a BSRP (Buffer Status Report Poll) trigger frame. In addition, the initial control frame may be included in a pre-designated PPDU format. The pre-designated PPDU format may be a non-HT Duplicate PPDU. When the first non-AP station (STA1) transmits a response frame (ICR) to the AP, the AP may set the initial control frame (ICF) transmitted in the unavailable section to an RU included in the alternative operation bandwidth for the first non-AP station (STA1). Through this, the AP and the first non-AP station (STA1) perform frame exchange in the unavailable section.

[0201] FIG. 14 shows a specific format of a field included in a frame for indicating an unusable section according to an embodiment of the present invention.

[0202] Figure 14 (a) shows the format of a channel usage request frame included in a channel usage request frame for indicating information about the unavailable section described above. Figure 14 (b) shows the format of a channel usage response frame. Figure 14 (c) shows the format of a Channel Usage element that can be included in a channel usage request frame and a channel usage response frame. Figure 14 (d) shows the format of a TWT element that can be included in a channel usage request frame and a channel usage response frame. Figure 14 (e) shows the format of a Timeout Interval element that can be included in a channel usage request frame and a channel usage response frame. Figure 14 (f) shows the format of a control field of a TWT element. Figure 14 (g) shows the format of an Individual TWT Parameter Set field of a TWT element. Figure 14 (h) shows the format of a Request Type subfield of an Individual TWT Parameter Set field. Figure 14 (i) shows the format of a subfield of a channel use request frame that indicates whether to transmit in the station alternative operation bandwidth.

[0203] As in (a) of Fig. 14, the channel usage request frame may include a Category field, a WNM Action field, a Dialog Token field, a Channel Usage Element field, a Supported Operating Classes Element field, a TWT elements field, and a Timeout Interval Element field.

[0204] The Category field can be a 1-octet field. Additionally, the Category field can indicate the type of action frame. The Category field of the Channel Use Request frame is set to 10, which indicates a Wireless Network Management (WNM) action frame.

[0205] The WNM Action field can be a 1-octet field. The WNM Action field is a field for indicating a frame transmitted for the purpose of managing a wireless network, and the value of the WNM Action field can be set to 21, indicating a channel use request frame.

[0206] The Dialog Token field can be a 1-octet field. The Dialog Token field can be a field used to identify requests and responses. The value of the Dialog Token field in a channel use request frame can be set to a non-zero value.

[0207] The Channel Usage Elements field may be a variable-length field. The Channel Usage Elements field may contain one or more Channel Usage elements. The Channel Usage Elements field may be used to identify a request for channel usage.

[0208] The Supported Operating Classes Element field may be a variable-length field. It may contain one Supported Operating Classes element. The Supported Operating Classes Element field may indicate the operating classes supported by the transmitting station.

[0209] The TWT elements field may be a variable-length field. The TWT elements field may contain one or more TWT elements. Each TWT element may contain an individual set of TWT parameters. As described above, the TWT element may indicate the start time of an unavailable interval, the duration, and the interval between unavailable intervals.

[0210] The Timeout Interval Element field can be a 0-octet to 7-octet field. The Timeout Interval Element field can be present when a TWT element is present. The Timeout Interval Element field can indicate the lifetime for which the TWT applies.

[0211] The Channel Usage Response frame contains a Country String field instead of the Supported Operating Classes Element field in the Channel Usage Request frame. The WMN Action field of the Channel Usage Response frame may be set to a non-zero value to indicate that it is a Channel Usage Response frame.

[0212] The Channel Usage element can indicate channel usage information of a BSS. The Channel Usage element can include an Element ID field, a Length field, a Usage Mode field, and a Channel Entry field. The Element ID field can be a 1-octet field. The Element ID field can be set to 97, indicating a Channel Usage element. The Usage Mode field can be a 1-octet field. The Usage Mode field can indicate information to be indicated in the Channel Entry field. The Usage Mode field can be set to 3, indicating that the element is for indicating channel unavailability. If the value of the Usage Mode field is 3, the Channel Entry field is not included in the Channel Usage element.

[0213] The Channel Usage element may indicate subchannels that are unavailable due to IDC. In this case, the Usage Mode field may indicate that some channels (partial channels) are unavailable. If the Usage Mode field indicates that some channels are unavailable, the Channel Entry field may indicate whether subchannels within the maximum operating bandwidth of the AP or within the 320MHz size are available. In this case, the Channel Entry field may be in bitmap format. Each bit of the bitmap may indicate whether a 20MHz subchannel is available. The least significant bit (LSB) may indicate the lowest center frequency among the 20MHz subchannels within the frequency band indicated by the Channel Entry field. In this case, the larger bit of two consecutive bits of the bitmap may correspond to a 20MHz subchannel with a center frequency next to the center frequency corresponding to the smaller bit. In addition, the Channel Entry field may indicate the alternative operating bandwidth described above. Specifically, a subchannel indicated as available by the Channel Entry field may be considered a subchannel included in the alternative operating bandwidth.

[0214] A TWT element may be an element for indicating a TWT to be set by a frame including the TWT element. A TWT element may include an Element ID field, a Length field, a Control field, and a TWT Parameter Information field. The Element ID field may be a 1-octet field. The Element ID field may be set to 216 indicating a TWT element. The Control field may be a 1-octet field. The Control field may include an instruction for requesting TWT setup or setting a unit of time for setting a TWT Service period. The TWT Parameter Information field is determined by the Negotiation Type subfield of the Control field, and a TWT element for setting P2P TWT may include an individual TWT parameter set.

[0215] If a frame including a TIE (timeout interval information) field includes a TWT element, the TIE field may indicate the lifetime of the TWT set by the TWT element. The TIE field may include an Element ID field, a Length field, a Timeout Interval Type field, and a Timeout Interval Value field. The Element ID field may be a 1-octet field. The Element ID field may be set to 56, indicating that it is a TIE field. The Timeout Interval Type field may be a 1-octet field. The Timeout Interval Type field may be set to 5, indicating the lifetime of the TWT. The Timeout Interval Value field indicates the value of the time indicated by the Timeout Interval Type field as an unsigned 32-bit integer.

[0216] The Control field of a TWT element can indicate the type of TWT information indicated by the TWT element. The Control field can include an NDP Paging Indicator / Unavailability Mode subfield, a Responder PM Mode subfield, a Negotiation Type subfield, a TWT Information Frame Disabled subfield, a Wake Duration Unit subfield, and a Reserved subfield. The Paging Indicator / Unavailability Mode subfield can be a 1-bit field. The NDP Paging Indicator / Unavailability Mode subfield can indicate that the TWT Parameter Information field includes an NDP Paging field when the TWT element is transmitted from a station operating in a sub-1 GHz band. The Responder PM Mode subfield can be a 1-bit field. The Responder PM Mode subfield is a subfield that indicates whether the power management mode of the receiving station is active mode or power save (PS) mode. When the TWT element indicates information about P2P TWT, the Responder PM Mode subfield may be a reserved field. The Negotiation Type subfield may be a 2-bit field. The Negotiation Type subfield may indicate whether the TWT element is negotiating for broadcast TWT, negotiating for individual TWT, or negotiating for wake TBTT interval. The Most Significant Bit (MSB) of the Negotiation Type subfield may indicate whether it is a broadcast TWT. When the value of the bit is 1, the bit may indicate that one or more broadcast TWT parameter sets are included in the TWT element.If the value of the corresponding bit is 0, the corresponding bit may indicate that the TWT element contains one individual TWT parameter set. The TWT Information Frame Disabled subfield may be a 1-bit subfield. If the value of the TWT Information Frame Disabled subfield is 1, the TWT Information Frame Disabled subfield may indicate that the receiving station cannot receive the TWT information frame. The Wake Duration Unit subfield may be a 1-bit subfield. The Wake Duration Unit subfield may indicate the time unit of the Nominal Minimum TWT Wake Duration subfield in the TWT Parameter Information field. If the value of the Wake Duration Unit subfield is 0, the Wake Duration Unit subfield may indicate that the time unit of the Nominal Minimum TWT Wake Duration subfield is 256 us. If the value of the Wake Duration Unit subfield is 1, the Wake Duration Unit subfield may indicate that the time unit of the Nominal Minimum TWT Wake Duration subfield is 1 TU (Time Unit, 1024 us).

[0217] The individual TWT parameter sets indicated in the TWT Parameter Information field in the TWT element may include a Request Type field, a Target Wake Time field, a TWT Group Assignment field, a Nominal Minimum TWT Wake Duration field, a TWT Wake Interval Mantissa field, a TWT Channel field, and an NDP Paging field. If the TWT element is for establishing P2P TWT, the TWT Group Assignment field and the NDP Paging field may be reserved fields. The Request Type field may be a 2-octet field. The Request Type field may indicate whether a frame including 2Request Type fields is a frame in which a terminal requests TWT establishment or a frame in response to TWT establishment. The Target Wake Time field may be an 8-octet field. The information meaning of the Target Wake Time field may vary depending on the value indicated by the Negotiation Type subfield. When a TWT element indicates an individual TWT, it may indicate the time of the Service Period (SP) of the individual TWT to be started. The Nominal Minimum TWT Wake Duration field may be a 1-octet field. The Nominal Minimum TWT Wake Duration field may indicate the minimum time that a station must stay awake to complete the frame exchange procedure during the TWT Wake interval duration, in units specified in the Wake Duration Unit subfield. The TWT Wake interval duration may be the expected average interval between consecutive TWT SPs of the station.The Nominal Minimum TWT Wake Duration field may indicate the minimum time of the P2P TWT SP for the channel unavailability period of the station that transmitted the channel use request frame. The TWT Wake Interval Mantissa field may be a 2-octet field. The TWT Wake Interval Mantissa field may indicate the TWT Wake interval duration between the TWT Wake Interval Exponent subfield in the Request Type field and the TWT SP. The TWT Wake Interval Duration may be calculated according to the following mathematical expression 4.

[0218]

[0219] The TWT Wake Interval Mantissa may indicate the value indicated by the TWT Wake Interval Mantissa field, and the TWT Wake Interval Exponent may indicate the value indicated by the TWT Wake Interval Exponent subfield of the Request Type field. It is in microseconds according to mathematical expression 4. The TWT Channel field may include a bitmap indicating a temporary channel to be used by a station requesting TWT during a TWT SP. The LSB (Least Significant Bit) of the bitmap may indicate the channel with the lowest number among the operating channels of the BSS. In this case, the larger bit of two consecutive bits of the bitmap may correspond to the channel with the next larger number after the center frequency corresponding to the smaller bit.

[0220] In a HE BSS, each bit of the bitmap may correspond to a 20MHz subchannel included in the operating bandwidth of the BSS. The TWT channel field may indicate that a station transmitting the TWT channel field will operate on a channel corresponding to a bit whose bitmap value is 1 during the TWT SP. Specifically, the TWT channel field may indicate that a TWT requesting station will temporarily operate on a channel corresponding to a bit whose bitmap value is 1 during the TWT SP. The TWT channel field may indicate that a TWT responding station will operate on a channel corresponding to a bit whose bitmap value is 1 during the TWT SP. In this case, the channel corresponding to a bit whose bitmap value is 1 may indicate a primary channel on which the station operates. When the TWT element establishes a P2P TWT, the TWT channel field may be a reserve field. However, in the case of indicating channel unavailability, the TWT channel field may be used as in the embodiments described above. This allows the TWT channel field to indicate the location and size of the channel to be used during the unavailable interval. Since the TWT channel field is 8 bits, additional extensions may be required to indicate 320 MHz in 20 MHz increments. In specific embodiments, fields other than the TWT channel field may be used together.

[0221] The Request Type field included in the individual TWT parameter sets indicated in the TWT Parameter Information field can indicate a request for information to be operated on in the TWT SP or whether to accept the request. The TWT Parameter Information field can be a 16-bit field. The TWT Parameter Information field can include a 1-bit TWT Request subfield, a 3-bit TWT Setup Command subfield, a 1-bit Trigger subfield, a 1-bit Implicit subfield, a 1-bit Flow Type subfield, a 3-bit TWT Flow Identifier subfield, a 5-bit TWT Wake Interval Exponent subfield, and a 1-bit TWT Protection subfield. The TWT Request subfield can indicate whether a frame containing a TWT element is a TWT request frame or a TWT frame. The value of the TWT Setup Command subfield can indicate the type of TWT command. The TWT Setup command can be divided into eight types. A TWT requesting station can set the value of the TWT Request subfield to any one of 0 to 2, where 0 indicates a TWT request, 1 indicates a TWT suggest, and 2 indicates a TWT demand. A TWT responding station can set the value of the TWT Request subfield to any one of 4 to 7, where 4 indicates accept, 5 indicates alternate TWT, 6 indicates TWT dictate, and 7 indicates TWT reject. When a TWT element is for establishing P2P TWT, the Trigger subfield, the Implicit subfield, and the Flow Type subfield are reserved fields.The TWT Flow Identifier subfield can indicate the identifier of the TWT corresponding to the TWT request information using 3 bits. The TWT Protection subfield can indicate to the TWT responding station that the TWT requesting station should activate NAV protection during the TWT SP of the TWT established within the BSS, thereby requesting protection for the TWT SP corresponding to the requested TWT flow identifier.

[0222] The Channel Switch Mode field may indicate whether a station will move to a channel outside the operating band or to which channel it will move. The Channel Switch Mode field may indicate some or all of the unusable channels. In this case, the Channel Switch Mode field may include a bitmap, and the bitmap may indicate subchannels included in the maximum operating bandwidth or 320 MHz in units of 20 MHz. The Channel Switch Mode field may indicate unusable channels in units of 20 MHz or channels included in the alternative operating bandwidth in units of 20 MHz. In addition, according to a specific embodiment, the Channel Switch Mode field may be combined with other elements of the channel use request frame to indicate unusable channels. For example, the Channel Switch Mode field may be combined with the TWT Channel field described above to indicate information about unusable channels. When the Channel Switch Mode field is indicated by the Channel Switch Mode Enabled field, the Channel Switch Mode Enabled field may indicate that the station will operate in the alternative bandwidth. In this case, the Channel Usage element, the TWT element, or other fields may indicate channels in the alternative operating bandwidth.

[0223] In this specification, using existing fields and subfields for different purposes may indicate that the bits at the positions of those fields and subfields are used for different purposes.

[0224]

[0225] Non-periodic IDC

[0226] As described above, a station may include information about an IDC to be generated in a frame transmitted to the counterpart station or in a response frame transmitted by the station. In this case, the IDC to be generated may be an aperiodic IDC. If the counterpart station is a TXOP holder and the unavailable interval indicated by the station is earlier than the TXOP end time, the counterpart station may end the TXOP before the unavailable interval. In addition, if the counterpart station is a TXOP holder and the unavailable interval indicated by the station is earlier than the TXOP end time, the counterpart station may complete the transmission of a PPDU to be transmitted to the station before the unavailable interval. In this case, the counterpart station may reduce the size of the PPDU to be transmitted to the station. In addition, the counterpart station may increase the MCS (modulation & coding scheme) of the PPDU to be transmitted to the station. If the counterpart station is a TXOP responder, the counterpart station may attempt to exchange frames with a station other than the station that transmitted the IDC-related information in the unavailable interval.

[0227] When aperiodic IDC occurs at a station, how the station signals the aperiodic IDC is described in FIG. 15.

[0228] FIGS. 15 and 16 illustrate signaling of aperiodic IDC to a non-AP station during frame exchange between an AP and a non-AP station according to an embodiment of the present invention.

[0229] A station may include information regarding an unavailable interval of an aperiodic IDC in a response frame to an initial control frame. The information regarding the unavailable interval of an aperiodic IDC may include at least one of the start time of the unavailable interval (Unavailable start time), the duration of the unavailable interval (Unavailable duration), or the channel to which the unavailable interval applies (Unavailable Channel). A counterpart station receiving the response frame may determine information regarding the unavailable interval. The counterpart station may perform transmission to the station based on the information regarding the unavailable interval. Specifically, the counterpart station may complete transmission before the unavailable interval begins. In this case, the counterpart station may reduce the size of the PPDU transmitted to the station from the size originally intended to be transmitted.

[0230] In addition, when there is a change in the information regarding the unavailable interval of the aperiodic IDC, the station may include the information regarding the unavailable interval of the aperiodic IDC in the ACK frame transmitted to the counterpart station. In addition, even when there is no change in the unavailable interval of the aperiodic IDC, the station may include the information regarding the unavailable interval of the aperiodic IDC in the ACK frame transmitted to the counterpart station. Through this, the station may continuously inform the counterpart station of the unavailable interval of the aperiodic IDC. The ACK frame is a frame indicating an ack and may include at least one of a Block ACK frame and a Multi-STA BlockAck frame. The time information among the information regarding the unavailable interval of the aperiodic IDC described above may indicate a start time based on the transmission time of the frame including the information regarding the unavailable interval of the aperiodic IDC. In another specific embodiment, the time information among the information regarding the unavailable interval of the aperiodic IDC may be indicated as an absolute time. Specifically, information about the time among the information about the unavailable interval of the aperiodic IDC can be indicated using the Time Synchronization Function (TSF).

[0231] Information about time can be indicated as the time from the transmission time of the frame to the IDC occurrence time using a relative time indication method, or can be indicated as a specific IDC occurrence time using a Time Synchronization Function (TSF) using an absolute time indication method.

[0232] In the embodiment of FIG. 15, the AP acquires a TXOP and transmits an initial control frame (ICF) to a non-AP station (Non-AP STA). The non-AP station (Non-AP STA) that receives the initial control frame (ICF) transmits a response frame (ICR). The AP performs frame exchange with the non-AP station (Non-AP STA) based on information about the unusable section indicated by the response frame (ICR). The AP adjusts the length of the DL PPDU transmitted to the non-AP station (Non-AP STA) so that the frame exchange is completed before the unusable section indicated by the response frame (ICR) begins. The non-AP station (Non-AP STA) that receives the DL PPDU transmits an ACK frame to the AP. At this time, the ACK frame may include information about the unusable section.

[0233] In the embodiment of FIG. 16, the AP operates a BSS having an 80 MHz operating bandwidth. At this time, a non-AP station (STA) belonging to the BSS operates with an operating bandwidth of 40 MHz. The AP, which has acquired a TXOP, transmits an initial control frame (ICF) to each of the first non-AP station (STA1) and the second non-AP station (STA2) using a non-HT Duplicate PPDU having a bandwidth of 40 MHz. At this time, the initial control frame may be an MU-RTS trigger frame. Each of the first non-AP station (STA1) and the second non-AP station (STA2) transmits a response frame (ICR) at SIFS intervals with a bandwidth of 40 MHz based on the initial control frame (ICF). At this time, the first non-AP station (STA1) and the second non-AP station (STA2) can determine whether the resources allocated by the initial control frame (ICF) are idle. If the allocated resources are determined to be idle, the first non-AP station (STA1) and the second non-AP station (STA2) can transmit a response frame (ICR) to the AP. The response frame may be a CTS frame. The AP transmits a DL PPDU to the first non-AP station (STA1) on the primary 20 MHz channel (P20) and the first secondary 20 MHz channel (S20-1). The first non-AP station (STA1) transmits a response frame to the AP indicating whether the DL PPDU has been received. The response frame may be a frame indicating an ack as described above, for example, a Multi-STA BlockACK frame. At this time, the non-AP station (STA) may include information indicating that the second secondary 20 MHz channel (S20-2) is unavailable in the response frame. The AP receives the response frame and performs frame exchange using the remaining channels except for the second secondary 20 MHz channel (S20-2).To this end, the AP does not allocate the second 20 MHz channel (S20-2) to the first non-AP station (STA1).

[0234] FIG. 17 shows that one non-AP station operates in an alternative operating band due to aperiodic IDC during frame exchange between an AP and multiple non-AP stations according to an embodiment of the present invention.

[0235] In the embodiment of FIG. 17, the AP operates a BSS with an 80 MHz operating bandwidth. The AP acquires a TXOP and transmits an initial control frame (ICF) to a first non-AP station (STA1), a second non-AP station (STA2), and the remaining other non-AP stations (80 MHz other STAs). The initial control frame (ICF) assigns the first secondary 20 MHz channel (S20-1) and the primary 20 MHz channel (P20) to the first non-AP station (STA1), and assigns 80 MHz channels (P20, S20-1, S20-2, S20-3) to the second non-AP station (STA2). The first non-AP station (STA1) and the second non-AP station (STA2) transmit a response frame (ICR) through the assigned RU. The AP transmits DL PPDUs to the first non-AP station (STA1) and the second non-AP station (STA2) on the first secondary 20 MHz channel (S20-1) and the primary 20 MHz channel (P20), and to the remaining non-AP stations on the second secondary 20 MHz channel (S20-2) and the third secondary 20 MHz channel (S20-3). The first non-AP station (STA1) and the second non-AP station (STA2) receive the DL PPDUs and transmit Multi-STA BlockAck (M-BA) frames to the AP.At this time, the first non-AP station (STA1) includes information about an unavailable interval indicating that the first secondary 20 MHz channel (S20-1) and the primary 20 MHz channel (P20) are unavailable and information indicating to operate in an alternative operating bandwidth (S20-2, S20-3) in a Multi-STA BlockAck (M-BA) frame. The AP receives the Multi-STA BlockAck (M-BA) frame from the first non-AP station (STA1) and does not attempt to exchange frames with the first non-AP station (STA1) using the first secondary 20 MHz channel (S20-1) and the primary 20 MHz channel (P20) in the unavailable interval. When the AP determines that the first non-AP station (STA1) is operating in an alternative operating bandwidth (S20-2, S20-3) based on the channel switching delay of the first non-AP station (STA1), it performs frame exchange with the first non-AP station (STA1).

[0236]

[0237] Overlap between Periodic and Aperiodic IDCs

[0238] As previously explained, when periodic IDC occurs, aperiodic IDC may also occur. This section describes station operations to address this.

[0239] FIG. 18 shows the operation of the AP and the station when the AP and the station set up a P2P TWT for an unavailable period and an aperiodic IDC occurs according to an embodiment of the present invention.

[0240] As previously explained, non-AP stations and APs can establish P2P TWTs for unavailable periods. Even with P2P TWT established, if aperiodic IDC occurs in the SP of the P2P TWT, the non-AP station and AP may not be able to exchange frames. Therefore, a method is needed to exchange information regarding unavailable periods of aperiodic IDC.

[0241] First, as previously explained, a station can include information about unavailable intervals due to aperiodic IDC in the response frame it transmits to the other station. For convenience, situations where periodic and aperiodic IDC overlap are classified based on several criteria.

[0242] The start time of the unavailable interval of the periodic IDC is referred to as x, the duration of the unavailable interval of the periodic IDC is referred to as X, the start time of the unavailable interval of the aperiodic IDC is referred to as y, and the duration of the unavailable interval of the aperiodic IDC is referred to as Y.

[0243] A. If the start time of the unavailable interval of the aperiodic IDC is earlier than the start time of the unavailable interval of the periodic IDC (x > y)

[0244] 1) The unavailable interval of the aperiodic IDC ends in the middle of the unavailable interval of the periodic IDC.

[0245] 2) The unavailable period of the aperiodic IDC ends after passing the unavailable period of the periodic IDC.

[0246] B. If the start time of the unavailable interval of the aperiodic IDC is later than the start time of the unavailable interval of the periodic IDC (x <y)

[0247] 1) The unavailable interval of the aperiodic IDC ends in the middle of the unavailable interval of the periodic IDC.

[0248] 2) The unavailable period of the aperiodic IDC ends after passing the unavailable period of the periodic IDC.

[0249] In case A, the counterpart station can determine the unavailable interval from the start time y of the unavailable interval of the aperiodic IDC to the end time of the unavailable interval of the periodic IDC or the end time of the unavailable interval of the aperiodic IDC. If the unavailable interval of the aperiodic IDC ends in the middle of the unavailable interval of the periodic IDC, the counterpart station can determine (x - y + X) as the duration of the unavailable interval. If the unavailable interval of the aperiodic IDC ends after the unavailable interval of the periodic IDC, the counterpart station can determine (y + Y) as the duration of the unavailable interval.

[0250] In case B, the counterpart station can determine the unavailable interval from the start time x of the unavailable interval of the periodic IDC to the end time of the unavailable interval of the periodic IDC or the end time of the unavailable interval of the aperiodic IDC. If the unavailable interval of the aperiodic IDC ends in the middle of the unavailable interval of the periodic IDC, the counterpart station can determine (x+X) as the unavailable interval. If the unavailable interval of the aperiodic IDC ends after the unavailable interval of the periodic IDC, the counterpart station can determine (y -x+ Y) as the unavailable interval.

[0251]

[0252] A station can compare the unavailable intervals of a periodic IDC with the unavailable intervals of an aperiodic IDC, combine them into a single unavailable interval, and transmit information about the combined unavailable interval to the other station. This case can also be categorized into the two cases (A and B) described above.

[0253] For A, the station can set the start time of the integrated unavailable interval to y. If the unavailable interval of the aperiodic IDC ends in the middle of the unavailable interval of the periodic IDC, the station can indicate the duration of the integrated unavailable interval as (x - y + X). If the unavailable interval of the aperiodic IDC ends after the unavailable interval of the periodic IDC, the station can indicate the duration of the unavailable interval as (y + Y).

[0254] For B, the station can set the start point of the integrated unavailable interval to x. If the unavailable interval of the aperiodic IDC ends in the middle of the unavailable interval of the periodic IDC, the station can determine (x+X) as the duration of the unavailable interval. If the unavailable interval of the aperiodic IDC ends after the unavailable interval of the periodic IDC, the station can determine (y-x+ Y) as the duration of the unavailable interval.

[0255] FIG. 19 shows the operation of a non-AP station when an aperiodic IDC occurs according to an embodiment of the present invention.

[0256] In the embodiment of FIG. 19, the AP and the first non-AP station (STA1) exchange information about an unusable section due to periodic IDC according to the embodiments described above. The AP transmits a data frame to the first non-AP station (STA1). An aperiodic IDC occurs to the first non-AP station (STA1), and the first non-AP station (STA1) transmits a response frame (ACK) including information indicating an unusable section due to the aperiodic IDC to the AP. At this time, the first non-AP station (STA1) determines an unusable section by considering both the aperiodic IDC and the periodic IDC. Information about the start time and duration of the determined unusable section is included in the response frame (ACK).

[0257] In another specific embodiment, a station may transmit only information about an unavailable section to the other station, other than information about an unavailable section previously transmitted. In this case, the other station may perform a frame exchange with the station by integrating information about the previously received unavailable section and the newly received unavailable section. This embodiment may be used in conjunction with the previously described embodiment, where the station indicates an integrated unavailable section. In this case, the station may indicate to the other station what action to take. Specifically, the station may use a response frame to indicate this.

[0258]

[0259] <Change of unavailable section>

[0260] A scheduled IDC may be canceled due to a heterogeneous communication method, such as the interruption of Bluetooth use. Therefore, a change instruction for an unavailable interval between a station and a counterpart station is needed that encompasses cases where an unavailable interval is canceled. In this specification, canceling an unavailable interval means reverting to a state where the unavailable interval is not set. The embodiments regarding changing an unavailable interval described below can be applied in conjunction with the embodiments regarding setting and changing an unavailable interval described above, as long as they do not conflict with each other.

[0261] FIGS. 20 to 22 illustrate operations of a station transmitting information about an updated unavailable section according to an embodiment of the present invention.

[0262] A station may include information for changing a previously set unavailable interval in a response frame transmitted to a counterpart station. At this time, the response frame may be a control frame. Specifically, the response frame may be a frame indicating ACK as described above. The frame indicating ACK may include at least one of an ACK frame, a BlockAck frame, or a Multi-STA BlockACK frame. The information for changing the unavailable interval may indicate cancellation of a previously set unavailable interval. If the response frame is a Multi-STA BlockACK frame, any one of the Per AID TID Info fields of the BA Information field may indicate cancellation of a previously set unavailable interval. At this time, the Per AID TID Info field may specify the unavailable interval to be canceled using a TWT flow indicator.

[0263] In the embodiment of FIG. 20, the first non-AP station (STA1) transmits a request frame indicating an unavailable interval of periodic IDC to the AP. The AP, which receives the request frame, transmits a response frame accepting the unavailable interval to the first non-AP station (STA1). Thereafter, the AP and the first non-AP station (STA1) perform frame exchange based on the configured unavailable interval. Therefore, the AP does not transmit frames to the first non-AP station (STA1) during the unavailable interval. When the periodic IDC is canceled at the first non-AP station (STA1), the first non-AP station (STA1) includes information canceling the previously configured unavailable interval in one of the response frames transmitted to the AP, a Multi-STA BlockAck frame. The AP receives the Multi-STA BlockAck frame and determines that the previously configured unavailable interval has been canceled. The AP attempts to exchange frames with the first non-AP station (STA1) in the previously configured unavailable interval.

[0264] In the embodiment of FIG. 21, the AP acquires a TXOP and transmits an initial control frame (ICF) to the first non-AP station (STA1). The first non-AP station (STA1) receives the initial control frame (ICF) and transmits a response frame (ICR) indicating an unavailable interval of the aperiodic IDC to the AP. The AP, which receives the response frame (ICR), performs a frame exchange with the first non-AP station (STA1) based on the unavailable interval. If the aperiodic IDC is canceled during the frame exchange, the first non-AP station (STA1) transmits a frame (ACK) indicating an ACK for canceling the previously set unavailable interval in the response frame to be transmitted to the AP. The AP receives the frame (ACK) indicating the ACK and determines that the previously set unavailable interval has been canceled. The AP attempts to exchange frames with the first non-AP station (STA1) in the previously set unavailable interval.

[0265] Figure 22 illustrates a case where the IDC that caused a previously established unavailable interval disappears and a new IDC appears. The station can simultaneously cancel the previously established unavailable interval and establish a new unavailable interval. The station can configure the information canceling the previously established unavailable interval to be decoded before the information regarding the new unavailable interval.

[0266] In the embodiment of FIG. 22, the first non-AP station (STA1) transmits a request frame indicating an unavailable interval of periodic IDC to the AP. The AP, upon receiving the request frame, transmits a response frame accepting the unavailable interval to the first non-AP station (STA1). Thereafter, the AP and the first non-AP station (STA1) perform frame exchange based on the configured unavailable interval. Therefore, the AP does not transmit a frame to the first non-AP station (STA1) during the unavailable interval, or does not expect a response even if it transmits a frame. The periodic IDC is canceled in the first non-AP station (STA1) and a new aperiodic IDC is generated. The first non-AP station (STA1) includes information in the frame indicating the ACK transmitted to the AP, canceling the previously configured unavailable interval and setting a new unavailable interval. At this time, among the IDC information indicated in the response frame, the Multi-STA BlockAck frame, the information canceling the previously set unavailable interval must be indicated first. The AP receives the Multi-STA BlockAck frame and determines that the previously set unavailable interval has been canceled and a new unavailable interval has been set. The AP attempts to exchange frames with the first non-AP station (STA1) in a time interval other than the newly set unavailable interval.

[0267] In the embodiments described above, it has been explained that a station can transmit information about an unavailable section to a counterpart station via a control frame, such as a frame indicating an ACK. This allows the unavailable section to be set, canceled, or modified. Transmitting information about an unavailable section via a Multi-STA BlockAck frame is described with reference to Figure 23.

[0268] FIG. 23 shows the format of a Multi-STA BlockAck frame including information about an unavailable section according to an embodiment of the present invention.

[0269] First, the general format of the Multi-STA BlockAck frame is described. The Multi-STA BlockAck frame is a frame that indicates whether or not data is received to one or more stations. The Multi-STA BlockAck frame may include at least one of a 2-octet Frame Control field, a 2-octet Duration field, a 6-octet RA field, a 6-octet TA field, a 2-octet BA Control field, a BA Information field, or a 4-octet FCS field.

[0270] The Frame Control field may include information indicating that this is a BlockACK frame. The Duration field may indicate the value of the NAV set by the BlockACK frame. The value of the Duration field may be set to a value equal to the SIFS time plus the time required to transmit the BlockACK frame. The RA field may indicate the MAC address of the station that will receive the BlockACK frame. The TA field may indicate the MAC address of the station that transmits the BlockACK frame. The BA Control field may indicate the type of BlockAck frame. The value of the BA Type subfield of the BA Control field may be set to 11 to indicate a Multi-STA BlockAck variant. The BA Information field includes one or more Per AID TID Info subfields, and the Per AID TID Info subfields may include an AID TID Info subfield of 2 octets, a Block Ack Starting Sequence Control subfield of 0 or 2 octets, and a Block Ack Bitmap subfield of 0, 4, 8, 16, or 32 octets. The AID TID Info subfield may include an 11-bit AID11 subfield, a 1-bit Ack Type subfield, and a 4-bit TID subfield. The AID11 subfield may indicate 11 bits of the AID of the station that transmitted the data indicating whether the Per AID TID Info subfield including the AID11 subfield was received. When the value of the AID11 subfield is 0, the Per AID TID Info subfield may indicate whether the data transmitted from the AP was received. When the value of the AID11 subfield is 2045, the Per AID TID Info subfield may indicate whether the data transmitted from the unassociated station was received.The Ack Type subfield can indicate the presence of the Block Ack Starting Sequence Control subfield and the Block Ack Bitmap subfield following the AID TID Info subfield in the Per AID TID Info field. If the value of the Ack Type subfield is 0, the Ack Type subfield can indicate the presence of the Block Ack Starting Sequence Control subfield and the Block Ack Bitmap subfield following the AID TID Info subfield in the Per AID TID Info field. If the value of the Ack Type subfield is 1, the Ack Type subfield can indicate the absence of the Block Ack Starting Sequence Control subfield and the Block Ack Bitmap subfield following the AID TID Info subfield in the Per AID TID Info field. The TID subfield can indicate the TID of the traffic for which the Per AID TID Info field indicates whether to receive. The Block Ack Starting Sequence Control subfield may contain a 4-bit Fragment Number subfield and a 12-bit Starting Sequence Number subfield. The Fragment Number subfield may indicate the size of the Block Ack Bitmap subfield. If the value of the third bit (B3) of the Fragment Number subfield is 0, the Fragment Number subfield may indicate the length of the Block Ack Bitmap subfield as 4, 8, 16, or 32 octets in eight combinations. The Starting Sequence Number subfield may indicate the sequence number of the first MSDU or A-MSDU for which the Block Ack Bitmap subfield indicates whether it has been received.The sequence number indicated by the Starting Sequence Number subfield can correspond to the first bit position of the Block Ack Bitmap subfield. The Block Ack Bitmap subfield can indicate whether the MPDU corresponding to each bit of the bitmap has been received. If the value of the bit is 1, it can indicate that the MPDU corresponding to the bit has been received. If the value of the bit is 0, it can indicate that the MPDU corresponding to the bit has not been received.

[0271] In a specific embodiment of the present invention, any one of the Per AID TID Info subfields of the Multi-STA BlockAck frame may indicate information regarding an unavailable interval. At this time, the value of the Ack Type field and the value of the TID subfield of the Per AID TID Info subfield indicating information regarding the unavailable interval may each be set to a pre-specified value. At this time, the pre-specified value of the Ack Type field may be 0, and the pre-specified value of the TID subfield may be any one of 8 to 15. In addition, in a specific embodiment, the Per AID TID Info subfield may indicate cancellation of a previously set unavailable interval. At this time, the value of the Ack Type field and the value of the TID subfield of the Per AID TID Info subfield indicating cancellation of a previously set unavailable interval may each be set to a pre-specified value. At this time, the pre-specified value of the Ack Type field may be 1, and the pre-specified value of the TID subfield may be any one of 8 to 13.

[0272] When the Per AID TID Info field indicates information about an unavailable interval, the Per AID TID Info field's Block Ack Starting Sequence Control subfield may be set to a reserved bit. At this time, the Block Ack Bitmap subfield may be used as a Feedback Info subfield. The Feedback Info subfield may indicate information about an unavailable interval. Information about the unavailable interval may follow the embodiments described above. Specifically, the Feedback Info subfield may include at least one of a subfield indicating a start time of an unavailable interval, a subfield indicating a duration of the unavailable interval, or a subfield indicating a channel to which the unavailable interval applies. The subfield indicating the start time of an unavailable interval is referred to as an Unavailability Start Time subfield, the subfield indicating the duration of the unavailable interval is referred to as an Unavailability Duration subfield, and the subfield indicating a channel to which the unavailable interval applies is referred to as a Channel Unavailable Feedback Bitmap subfield. The value of the Unavailability Start Time subfield may indicate the time difference between the transmission end time of the Multi-STA BlockAck frame and the start time of the unavailability interval. In another specific embodiment, the value of the Unavailability Start Time subfield may indicate the start time of the unavailability interval as an absolute time using the TSF. In another specific embodiment, the Channel Unavailable Feedback Bitmap subfield may indicate a channel included in the alternative operation bandwidth.In the embodiments described above, the Channel Unavailable Feedback Bitmap subfield may include a bitmap, and each bit of the bitmap may correspond to a 20 MHz channel. Furthermore, the least significant bit (LSB) of the bitmap may correspond to a 20 MHz subchannel having the lowest center frequency of the bandwidth indicated by the bitmap. In this case, the larger bit of two consecutive bits of the bitmap may correspond to a 20 MHz subchannel having a center frequency next higher than the center frequency corresponding to the smaller bit.

[0273] If a Multi-STA Block ACK frame to be received by a counterpart station includes a Per AID TID Info field indicating information about an unavailable section, the counterpart station may set a value of a Duration field of a frame soliciting transmission of a Multi-STA Block ACK frame based on a value obtained by adding the length of the Per AID TID Info field indicating information about the unavailable section to the length of the field indicating whether traffic is received. At this time, the frame soliciting transmission of the Multi-STA Block ACK frame may be an Aggregated MAC Protocol Data Unit (A-MPDU), a Block Ack Request (BAR) frame, or a Multi User Block Ack Request (MU-BAR) frame including a Quality of Service (Qos) data frame. Specifically, the originator station may set the value of the Duration field of the frame soliciting the transmission of the Multi-STA Block ACK frame, taking into account the value of the largest Block Ack Bitmap length based on the negotiated buffer size and the length of the information about the unavailable interval to be transmitted through the Multi-STA Block Ack frame. At this time, the QoS data frame may include a management frame requesting an immediate Block Ack frame response or requesting an ACK.

[0274]

[0275] <Aperiodic IDC Management Method>

[0276] As described above, a station can update information about an unavailable section by transmitting information about a changed unavailable section to a counterpart station. At this time, the station can include the information about the changed unavailable section in a response frame, such as a frame indicating an ACK, and transmit it to the counterpart station. This operation can be used not only for unavailable sections of periodic IDCs but also for aperiodic unavailable sections. This will be described below. Depending on specific embodiments, the embodiments described with reference to FIGS. 24 and 25 can be applied together with the operations of the embodiments described with reference to FIGS. 20 to 23. In addition, the embodiments described with reference to FIGS. 24 and 25 can be applied not only to updating information about an unavailable section of an aperiodic IDC but also to updating information about an unavailable section of a periodic IDC. In addition, unless otherwise stated herein, the embodiments described with reference to FIGS. 11 to 19 can be applied together with the embodiments described herein.

[0277] A station may transmit a frame to a counterpart station that cancels an unavailable interval of an aperiodic IDC. Furthermore, the station may transmit a frame to the counterpart station that cancels an unavailable interval of an aperiodic IDC and establishes a new unavailable interval. At this time, the frame may be a response frame. Specifically, the response frame may be a frame indicating an ACK, as described above. The frame indicating an ACK may include at least one of an ACK frame, a BlockAck frame, or a Multi-STA BlockACK frame. Information for changing an unavailable interval may indicate cancellation of a previously established unavailable interval.

[0278] FIG. 24 shows an operation of changing a previously set unavailable interval by a station according to an embodiment of the present invention.

[0279] In the embodiment of FIG. 24, the AP acquires a TXOP and transmits an initial control frame (ICF) to the first non-AP station (STA1). The first non-AP station (STA1) receives the initial control frame (ICF) and transmits a response frame (ICR) indicating an unavailable interval of the aperiodic IDC to the AP. The AP, which receives the response frame (ICR), performs a frame exchange with the first non-AP station (STA1) based on the unavailable interval. If the aperiodic IDC changes during the frame exchange, the first non-AP station (STA1) transmits a frame (ACK) indicating an ACK that cancels the previously set unavailable interval and sets a new unavailable interval in the response frame to be transmitted to the AP. The AP receives the frame (ACK) indicating an ACK and determines that the previously set unavailable interval is canceled and a new unavailable interval is set. The AP attempts to exchange frames with the first non-AP station (STA1) in a time interval other than the newly set unavailable interval.

[0280] FIG. 25 shows an operation of a station canceling a previously set unavailable section according to an embodiment of the present invention.

[0281] In the embodiment of FIG. 25, the AP acquires a TXOP and transmits an initial control frame (ICF) to the first non-AP station (STA1). The first non-AP station (STA1) receives the initial control frame (ICF) and transmits a response frame (ICR) indicating an unavailable interval of the aperiodic IDC to the AP. The AP, which receives the response frame (ICR), performs a frame exchange with the first non-AP station (STA1) based on the unavailable interval. If the aperiodic IDC changes during the frame exchange, the first non-AP station (STA1) transmits a frame (ACK) indicating an ACK to cancel the previously set unavailable interval in the response frame to be transmitted to the AP. The AP receives the frame (ACK) indicating the ACK and determines that the previously set unavailable interval has been canceled. The AP attempts to exchange frames with the first non-AP station (STA1) in the canceled unavailable interval.

[0282] In the embodiments described above, the operation of a station canceling a previously set unavailable interval will be described. A station can cancel a previously set unavailable interval by indicating that it has no information about the unavailable interval it has acquired. In a specific embodiment, when canceling a previously set unavailable interval, the station can cancel the previously set unavailable interval by indicating that it has no information about the unavailable interval it has acquired. Furthermore, indicating that the station has no information about the unavailable interval it has acquired may mean that the station sets the information about the unavailable interval to a pre-specified value. Specifically, a station can cancel a previously set unavailable interval by setting at least one or both of the values ​​of the Unavailability Duration subfield and the Unavailability Start Time subfield described above to a pre-specified value. The pre-specified value may be 0. For example, a station can cancel a previously set unavailable interval by setting the value of the Unavailability Duration subfield of a response frame to a pre-specified value, such as 0. In such an embodiment, 0 in the Unavailability Start Time subfield may be used for purposes other than canceling an unavailable interval. In another specific embodiment, the station can cancel a previously set unavailability interval by setting the value of the Unavailability Duration subfield of the response frame to a first predefined value, for example, 0, and setting the value of the Unavailability Start Time subfield to a second predefined value, for example, 0. The counterpart station can receive the response frame and cancel the previously set unavailability interval according to the response frame. At this time, the counterpart station can determine the sender of the response frame based on the AID or MAC address.

[0283] As described in the previously described embodiments, a station and a counterpart station can exchange frames based on a configured unavailable interval. Specifically, the station and the counterpart station can determine the timing of frame transmission based on the configured unavailable interval. For example, the counterpart station may not transmit frames to the station during the configured unavailable interval.

[0284] Since APs communicate with multiple non-AP stations, they can manage unavailable periods for each non-AP station. Specifically, the AP can manage unavailable periods based on the identification information of the non-AP station, such as AID or MAC address. In this case, the AP can manage information regarding the unavailable periods described above for each non-AP station. Information regarding the unavailable period may include at least one of the following: the start time of the unavailable period, the duration of the unavailable period, or information regarding the channel to which the unavailable period applies.

[0285]

[0286] <Multiple 비주기적 IDC>

[0287] In the embodiments described above, if a station is a TXOP holder, the station may transmit a frame to the counterpart station including information about the unavailable interval. In another specific embodiment, the station may transmit a frame indicating only information about the unavailable interval instead of the frame to be transmitted to the counterpart station. For example, if the frame transmitted by the station is a QoS data frame, the station may use the Control subfield of the A-control field to transmit information about the unavailable interval to the counterpart station. If the station is a TXOP responder, it may use a response frame as described above to transmit information about the unavailable interval to the counterpart station. At this time, the station cannot be sure when it will have an opportunity to transmit information about the unavailable interval. In addition, the station may expect the occurrence of different IDCs at the same time. For example, IDCs may be expected to occur due to the use of different communication technologies. In addition, aperiodic IDCs may occur simultaneously. The station may transmit information about multiple unavailable intervals to the counterpart station. If a station has information about multiple unavailable intervals, it may not be permitted to transmit information divided into multiple unavailable intervals. Furthermore, if a station cannot specify the IDC generation period, it may consider the IDC to be aperiodic. In this case, the station may designate the IDC as aperiodic to the other station.

[0288] FIG. 26 illustrates an operation in which a non-AP station, which is a TXOP responder, transmits information about multiple unavailable spaces to an AP according to an embodiment of the present invention.

[0289] In the embodiment of FIG. 26, the AP and a non-AP station (STA) exchange an initial control frame (ICF) and a response frame (ICR). At this time, the non-AP station (STA) includes information about multiple unavailable intervals in the response frame (ICR). Thereafter, the AP transmits a DL PPDU to the non-AP station (STA). The non-AP station (STA) transmits an ACK frame to the AP. Thereafter, multiple unavailable intervals arrive one after another, and the AP does not transmit a frame to the non-AP station (STA).

[0290]

[0291] <Multiple Aperiodic IDC Management Methods>

[0292] As previously described, a station can transmit information about multiple unavailable intervals to a counterpart station. At this time, the counterpart station can maintain and manage information about the multiple unavailable intervals. To this end, each of the multiple unavailable intervals can have an identifier. For convenience of explanation, this identifier is referred to as an interval identifier. At this time, each unavailable interval of an aperiodic IDC can have one interval identifier. Additionally, multiple unavailable intervals generated by a single periodic IDC can have interval identifiers. A station can use the interval identifier to cancel an unavailable interval indicated by the interval identifier among multiple unavailable intervals or to update information about the unavailable interval. Specifically, the counterpart station can obtain information about an unavailable interval, specify an unavailable interval using an unavailable interval indicator, and cancel the unavailable interval or update information about the unavailable interval.

[0293] A station can set multiple unavailable intervals of multiple aperiodic IDCs as a single unavailable interval. In this case, the station can set the period from the start time of the earliest unavailable interval to the end time of the latest unavailable interval as a single unavailable interval. In this embodiment, since it is a single unavailable available interval, the unavailable interval can have a single unavailable available interval identifier. The station can transmit information about the unavailable interval according to the embodiments described above. In this case, the station can transmit a single unavailable information combined using a single Per AID TID Info field of the Multi-STA BlockAck frame. This allows the station to reduce signaling overhead. In this embodiment, the station can transmit information indicating an available interval included in the single unavailable information to the other station. In this case, the station can transmit information about the available interval using the Per AID TID Info field described above.

[0294] FIG. 27 illustrates an operation of a non-AP station and an AP setting information regarding multiple unavailable intervals of multiple non-periodic IDCs according to an embodiment of the present invention.

[0295] In FIG. 27, an AP and a non-AP station (STA) exchange an initial control frame (ICF) and a response frame (ICR). At this time, the non-AP station (STA) includes information about multiple unavailable intervals in the response frame (ICR). In the embodiment of FIG. 27 (a), the station assigns a different unavailable interval indicator to each of the multiple unavailable intervals. In addition, in the embodiment of FIG. 27 (b), the station combines multiple unavailable intervals into a single unavailable interval and assigns a single unavailable interval indicator to the combined single unavailable interval. The AP and the non-AP station (STA) exchange frames until an unavailable interval arrives, and stop frame exchange in the unavailable interval. In addition, the AP does not perform retransmission even if it does not receive a response frame in the unavailable interval from the non-AP station (STA).

[0296] In the embodiments described above, an operation of canceling an unavailable section of one of the plurality of IDCs by canceling one of the plurality of IDCs is described. If the plurality of IDCs have multiple individual unavailable sections, the station can cancel the unavailable section using the section identifier of the unavailable section to be canceled, as described above. In addition, if the plurality of IDCs have a single unavailable section, the station can transmit information indicating the unavailable section to be canceled or changed. In this case, the information indicating the unavailable section to be canceled or changed can include updated availability information. The updated available section can include not only the unavailable section to be canceled, but also an available section that is continuous to the unavailable section.

[0297] FIG. 28 illustrates a method for a non-AP station and an AP to update unavailable sections of multiple IDCs according to an embodiment of the present invention.

[0298] In the embodiment of FIG. 28, the operations of the non-AP station (STA) and the AP are the same as the operations up to the setting of the unusable section of the non-AP station (STA) and the AP described in the embodiment of FIG. 27. The unusable section of the second IDC (Aperiodic IDC #2) is canceled in the non-AP station (STA). In the embodiment of FIG. 28 (a), the non-AP station (STA) transmits to the AP the section identifier of the second IDC (Aperiodic IDC #2) and information indicating cancellation of the unusable section. The AP cancels the unusable section corresponding to the section identifier of the second IDC (Aperiodic IDC #2). In the embodiment of FIG. 28 (b), the non-AP station (STA) transmits to the AP an identifier indicating an integrated unusable section and information about an available section indicating the unusable section of the second IDC (Aperiodic IDC #2) as an available section.

[0299] Figure 29 shows the format of the Per AID TID Info field according to an embodiment of the present invention.

[0300] Unless otherwise specified in the embodiments described through Fig. 29, the embodiments described through Fig. 23 above can be applied as is.

[0301] Figure 29 (a) shows the format of the Per AID TID Info field of the BA Information field of the Multi-STA Block Ack frame. Figure 29 (b) shows the AID TID Info subfield of the Per AID TID Info field. Figure 29 (c) shows the format of the BA Bitmap subfield indicating information about time and frequency band among the information about the unavailable section. Figure 29 (d) shows the BA Bitmap subfield indicating only the frequency band among the information about the unavailable section. Figure 29 (e) shows the format of the BA Bitmap subfield indicating only the information about time among the information about the unavailable section.

[0302] As described with reference to FIG. 23, the Per AID TID Info subfield can indicate information about an unavailable interval. In addition, the station can indicate that the Per AID TID Info subfield indicates information about an unavailable interval by setting a pre-specified value in the AID11 subfield. At this time, the station can indicate that the Per AID TID Info subfield is for indicating an unavailable interval of an aperiodic IDC by using a first pre-specified value. In addition, the station can indicate that the Per AID TID Info subfield is for indicating an unavailable interval of a periodic IDC by using a second pre-specified value. At this time, the pre-specified value, the first pre-specified value, and the second pre-specified value may be reserved values ​​that are not used as the value of the AID. In another specific embodiment, the station can indicate the type of information indicated by the Per AID TID Info field by using the value of the Ack Type subfield and the value of the TID subfield. At this time, the station may indicate that it is a Per AID TID Info subfield for indicating an unavailable section of aperiodic IDC by setting the value of the TID subfield to a first pre-specified value. In addition, the station may indicate that it is a Per AID TID Info subfield for indicating an unavailable section of aperiodic IDC by setting the value of the TID subfield to a second pre-specified value. At this time, the first pre-specified value and the second pre-specified value may be reserved values ​​that are not used as the value of the AID. In another specific embodiment, the station may indicate the type of information indicated by the Per AID TID Info field by setting the value of the AID11 subfield, the Ack Type subfield, and the value of the TID subfield to a pre-specified combination.At this time, the values ​​of the ID11 subfield, the Ack Type subfield, and the TID subfield may be set according to the embodiments for each field described above. For example, the station may set the value of the AID11 subfield to 2024, the value of the Ack Type subfield to 0, and the value of the TID subfield to 13.

[0303] The BA Bitmap field may include a field indicating an interval identifier and a field indicating the application time of information regarding an unavailable interval of a periodic IDC. The field indicating the interval identifier is referred to as an IDC Identifier subfield. In addition, the field indicating the application time of information regarding an unavailable interval is referred to as an SP count subfield. The IDC Identifier subfield may be a 4-bit subfield. The SP Count subfield may be a 4-bit subfield. In addition, the BA Bitmap field may include the subfields described through FIG. 23.

[0304]

[0305] Some bits of the IDC Identifier subfield may indicate whether the Per AID TID Info field indicates an unavailable interval of a periodic IDC or an unavailable interval of an aperiodic IDC. In this case, some bits may be the fourth bit (B3) of the IDC Identifier subfield. Specifically, if the value of the fourth bit (B3) is 0, the fourth bit (B3) may indicate that the Per AID TID Info field indicates an unavailable interval of a periodic IDC. In addition, if the value of the fourth bit (B3) is 1, the fourth bit (B3) may indicate that the Per AID TID Info field indicates an unavailable interval of an aperiodic IDC. If the Per AID TID Info field indicates an unavailable interval of a periodic IDC, the remaining bits of the IDC Identifier subfield may indicate a TWT flow identifier. Additionally, if the Per AID TID Info field indicates an unavailable interval of an aperiodic IDC, the remaining bits of the IDC Identifier subfield may indicate an interval identifier. In this case, the remaining bits may be the first to third bits (B0-B2).

[0306] When the Per AID TID Info field indicates an unavailable interval of the periodic IDC, the SP Count subfield may indicate the time point of the unavailable interval indicated by the information of the unavailable interval indicated by the Per AID TID Info field. At this time, the SP Count subfield may indicate from which periodic unavailable interval the information of the unavailable interval indicated by the Per AID TID Info field is applied. For example, when the value of the SP Count subfield is 2 and the Per AID TID Info field indicates cancellation of the unavailable interval of the periodic IDC, the Per AID TID Info field may indicate that the unavailable interval is canceled from the second periodic unavailable interval after the time point at which the Per AID TID Info field is transmitted. In the embodiments described above, the BA Bitmap subfield may include only a part of the unavailable interval. Specifically, it may be as in (d) or (e) of FIG. 29.

[0307] <Check whether aperiodic IDC information is received>

[0308] In the embodiments described above, a station cannot determine whether the opposing station has received information during an unavailable interval. Specifically, this is because the opposing station does not have a sequence for determining whether it has received a response frame, such as a frame indicating an ACK. In particular, the opposing station does not indicate in a separate frame whether it has received a Multi-STA BlockAck, and performs or does not perform retransmission based on the information indicated by the Multi-STA BlockAck. A method for a station to successfully receive information about an unavailable interval of the opposing station, particularly information about an unavailable interval of an irregular IDC, is described.

[0309] When a station transmits information about an unavailable section using a response frame to an initial control frame, the station can determine whether the transmission of the information about the unavailable section was successful based on whether a transmission is received from the counterpart station after SIFS after transmitting the response frame. If a transmission is received from the counterpart station after SIFS after transmitting the response frame, the station can determine that the transmission of the information about the unavailable section was successful. If a transmission is not received from the counterpart station after SIFS from the end of the response frame transmission, the station can determine that the transmission of the information about the unavailable section was unsuccessful. In this case, the station can perform a backoff procedure for channel access.

[0310] FIG. 30 illustrates a method for a non-AP station to determine whether to receive a response frame containing information about an unavailable section according to an embodiment of the present invention.

[0311] In Figure 30, the AP and a non-AP station (STA) exchange initial control frames (ICFs) and response frames (ICRs). At this time, the non-AP station (STA) includes information about the unavailable section in the response frame (ICR). The AP receives the response frame (ICR) and transmits a DL PPDU to the non-AP station (STA) at SIFS intervals. The non-AP station (STA) determines that the AP has successfully received information about the unavailable section.

[0312] This section describes how a station determines whether the transmission of information about an unavailable section was successful when the station transmits information about the unavailable section using a response frame, such as a frame indicating an ACK. For convenience of explanation, the frame indicating an ACK is referred to as an ACK response frame.

[0313] If the counterpart station successfully receives an ACK response frame including information about an unavailable section, the counterpart station may include information indicating successful reception of the ACK response frame in a PPDU transmitted at an SIFS interval with the ACK response frame. Specifically, the counterpart station may indicate successful reception of the ACK response frame in any field of the preamble of the PPDU, for example, U-SIG or UHR-SIG. This allows the counterpart station to indicate successful reception without incurring significant overhead. In another specific embodiment, if the counterpart station successfully receives the ACK response frame, the counterpart station may transmit a PPDU including a Null MPDU indicating successful reception of the ACK response frame. At this time, some of the reserved fields of the MAC header of the Null MPDU may indicate successful reception of the ACK response frame. In another specific embodiment, the MAC header of the Null MPDU may include an A-Control field for indicating successful reception of the ACK response frame. In another specific embodiment, the counterpart station may transmit a frame including only information about an unavailable section received from the station. At this time, a frame that only contains information about an unavailable section may include information about the unavailable section in the frame body. The station can determine whether the ACK frame transmission was successful based on the PPDU or MPDU transmitted immediately after the ACK response frame.

[0314] FIG. 31 illustrates a method for an AP to receive an ACK response frame and transmit a frame indicating successful reception of the ACK response frame, according to an embodiment of the present invention.

[0315] In Fig. 31, an AP and a non-AP station (STA) exchange an initial control frame (ICF) and a response frame (ICR). The AP receives the response frame (ICR) and transmits a DL PPDU to the non-AP station (STA) at SIFS intervals. At this time, the non-AP station (STA) includes information about the unavailable section in the Multi-STA BlockAck frame (M-BA) and transmits the Multi-STA BlockAck frame (M-BA) to the AP. The AP fails to obtain information about the unavailable section and transmits a DL PPDU to the non-AP station that does not include the Multi-STA BlockAck frame (M-BA) that only includes information about the unavailable section. The non-AP station (STA) includes information about the unavailable section in the Multi-STA BlockAck frame (M-BA) and transmits the Multi-STA BlockAck frame (M-BA) back to the AP. The AP successfully acquires information about the unavailable section and transmits a DL PPDU containing a Multi-STA BlockAck frame (M-BA) containing only information about the unavailable section to the non-AP station.

[0316] The counterpart station can indicate successful reception of the ACK response frame by adjusting the interval between the PPDU transmitted immediately after the ACK response frame and the ACK response frame. Specifically, if the counterpart station successfully receives the ACK response frame, the counterpart station can set the interval between the PPDU transmitted immediately after the ACK response frame and the ACK response frame to the SIFS interval. If the counterpart station fails to receive the ACK response frame, the counterpart station can set the interval between the PPDU transmitted immediately after the ACK response frame and the ACK response frame to a predetermined interval.

[0317] At this time, the predetermined interval may be an interval other than SIFS, such as xIFS. xIFS may be a value greater than the SIFS time and equal to or greater than the SIFS time plus an integer number of slot times. The station may determine whether the transmission of the ACK response frame is successful based on the interval between the ACK response frame and the PPDU transmitted immediately after the ACK response frame. If the interval between the ACK response frame and the PPDU transmitted immediately after the ACK response frame is SIFS, the station may determine that the transmission of the ACK response frame is successful. If the interval between the ACK response frame and the PPDU transmitted immediately after the ACK response frame is a predetermined interval, the station may determine that the transmission of the ACK response frame has failed. At this time, the station may retransmit the ACK response frame.

[0318] FIG. 32 illustrates a method in which an AP receives an ACK response frame and indicates successful reception of the ACK response frame by adjusting the interval between the ACK response frame and a PPDU transmitted immediately after the ACK response frame, according to an embodiment of the present invention.

[0319] In Fig. 32, an AP and a non-AP station (STA) exchange an initial control frame (ICF) and a response frame (ICR). The AP receives the response frame (ICR) and transmits a DL PPDU to the non-AP station (STA) at SIFS intervals. At this time, the non-AP station (STA) includes information about the unavailable section in the Multi-STA BlockAck frame (M-BA) and transmits the Multi-STA BlockAck frame (M-BA) to the AP. The AP fails to acquire information about the unavailable section and transmits the BlockAck frame (M-BA) and a DL PPDU with a PIFS interval. The non-AP station (STA) includes information about the unavailable section in the Multi-STA BlockAck frame (M-BA) and transmits the Multi-STA BlockAck frame (M-BA) back to the AP. The AP succeeds in acquiring information about the unavailable section and transmits the BlockAck frame (M-BA) and a DL PPDU with a SIFS interval.

[0320] If a station experiences or is expected to experience an unavailable period, the station may include information about the unavailable period in every response frame. In such an embodiment, the station may not determine whether the other station has successfully received the information about the unavailable period.

[0321] FIG. 33 shows an operation in which a station continuously transmits information about an unavailable section according to an embodiment of the present invention.

[0322] In Figure 33, the AP and a non-AP station (STA) exchange an initial control frame (ICF) and a response frame (ICR). The AP receives the response frame (ICR) and transmits a DL PPDU to the non-AP station (STA) at SIFS intervals. Thereafter, the non-AP station (STA) includes information about the unavailable interval in each Multi-STA BlockAck frame (M-BA) and transmits the Multi-STA BlockAck frame (M-BA) to the AP.

[0323]

[0324] <Indicates available functions during unavailable periods>

[0325] A station can specifically indicate whether wireless LAN communication is possible in an unavailable section as described above. In this case, the possibility of wireless LAN communication may include at least one of reception and transmission being possible. Specifically, a station can indicate whether transmission is impossible, reception is impossible, or neither is possible in an unavailable section. A station can indicate whether transmission is impossible, reception is impossible, or neither is possible in an unavailable section using a pre-designated field of a frame indicating information about an unavailable section as described above. For example, if the value of the pre-designated field is 0, the pre-designated field may indicate that both transmission and reception by the station are impossible in an unavailable section. If the value of the pre-designated field is 1, the pre-designated field may indicate that reception by the station is impossible in an unavailable section and transmission by the station is possible. If the value of the pre-designated field is 3, the pre-designated field may indicate that transmission by the station is impossible and reception by the station is possible in an unavailable section. In another specific embodiment, the pre-designated field may be divided into a field indicating whether reception is impossible and a field indicating whether transmission is impossible. If the value of the field indicating whether reception is impossible is 1, the field may indicate that reception is impossible at the station in the unavailable section. If the value of the field indicating whether transmission is impossible is 1, the field may indicate that transmission is impossible at the station in the unavailable section. Through this, the station and the counterpart station can increase the efficiency of use of the unavailable section. These embodiments may be applied to the embodiments indicating information regarding the unavailable section described above.For convenience of explanation, information indicating whether a station can receive in an unavailable section is referred to as reception unavailability information, and information indicating whether a station can transmit in an unavailable section is referred to as transmission unavailability information.

[0326] A station may include information indicating whether reception is unavailable and whether transmission is unavailable in a channel use request frame for indicating P2P TWT. Specifically, it may be included in a part of a field indicating information regarding an unavailable section of the use request frame. The format and setting method of the information indicating whether reception is unavailable and whether transmission is unavailable may follow the embodiments described above. Even if a station indicates that reception is possible in an unavailable section, reception may fail due to low reception sensitivity of the station. Therefore, when a station indicates that reception is possible, the station may indicate its interference power level or its expected maximum MCS. The opposing station may transmit to the station according to the interference power level or expected maximum MCS indicated by the station.

[0327] A station can indicate that transmission is possible in an unavailable section and reception is impossible. At this time, the operation of the counterpart station is described. The counterpart station can transmit a trigger frame that triggers transmission in the unavailable section before the station enters the unavailable section. At this time, the counterpart station can set the value of the CS required field of the User Info field corresponding to the station in the trigger frame to 0. This is to prevent the station from determining the channel status as busy and not transmitting. In this embodiment, the station can transmit a TB PPDU in response to the trigger frame. At this time, the station can determine the composition of the MPDU included in the TB PPDU based on whether it can receive an immediate response to the MPDU included in the TB PPDU. Specifically, if the station cannot receive an immediate response to the MPDU included in the TB PPDU, the station can include in the TB PPDU only the MPDU whose ACK Policy corresponds to No Ack. If a station can receive an immediate response to an MPDU included in a TB PPDU, the station can include the MPDU in the TB PPDU without this limitation. In this embodiment, even if the station cannot receive an immediate response to an MPDU included in the TB PPDU, the station can include the MPDU in the TB PPDU regardless of the Ack Policy under a pre-specified exception situation. The exception situation may include a case where the MPDU includes low-latency traffic. In addition, the exception situation may include a case where there is no traffic in the buffer of the station with a TID whose Ack Policy is No Ack. In addition, the exception situation may include a case where a response from the other station to an MPDU included in the TB PPDU is expected to be transmitted past a transmission dead zone.In these exceptional circumstances, the other station may not transmit a response to the station during the unavailable interval. The other station may transmit a response to the MPDU received during the unavailable interval after the unavailable interval has passed.

[0328] The opposing station may assign a TXOP to the station before the station enters the unavailable interval. At this time, the opposing station may transmit a station MU-RTS TXS trigger frame.

[0329] A counterpart station can induce a station to transmit in an unavailable section by using a frame indicating RDG (reverse grant direction) instead of a trigger frame. The frame indicating RDG may be a frame in which the RDG subfield, which is a field indicating permission of reverse direction in the counterpart frame, has a value of 1. At this time, the counterpart station can transmit the frame indicating RDG according to embodiments regarding the timing of transmission of the trigger frame. In addition, the station can select an MPDU to transmit in the unavailable section according to embodiments regarding restrictions on selection of MPDUs included in a TB PPDU. The station transmits data to the counterpart station, and if there is data remaining in the buffer to be transmitted to the counterpart station, the station can transmit a PPDU in which the More PPDU field has a value of 1 to the counterpart station. Thereafter, the station can transmit additional PPDUs at SIFS intervals.

[0330] In addition, if a station successfully accesses the channel and acquires a TXOP before an unavailable interval in which reception is not possible and transmission is possible arrives, the station may transmit in the unavailable interval. At this time, the station may determine the configuration of the MPDU included in the transmitted PPDU based on whether an immediate acknowledgment to the MPDU included in the transmitted PPDU can be received. Specifically, if the station cannot receive an immediate acknowledgment to the MPDU included in the PPDU, the station may include in the PPDU only MPDUs for which the ACK Policy corresponds to No Ack. If the station can receive an immediate acknowledgment to the MPDU included in the PPDU, the station may include the MPDU in the PPDU without this restriction. In this embodiment, even if the station cannot receive an immediate acknowledgment to the MPDU included in the PPDU, the station may include the MPDU in the PPDU regardless of the Ack Policy under a pre-specified exceptional circumstance. At this time, the exceptional circumstance may include a case in which the MPDU includes low-latency traffic. Additionally, an exception may include a case where there is no traffic in the station's buffer with a TID whose Ack Policy is No Ack. Additionally, an exception may include a case where the counterpart station's response to an MPDU included in a PPDU is expected to be transmitted past a transmission unavailable interval. For example, the Ack Policy of the last frame transmitted during a frame exchange performed during the unavailable interval may be an immediate Ack or a BlockAck. In such an exceptional case, the counterpart station may not transmit a response to the station during the unavailable interval. The counterpart station may transmit a response to the MPDU received during the unavailable interval to the station past the unavailable interval.Specifically, a station can pass through an unavailable interval and transmit a BlockAck frame to the other station.

[0331] The following describes the operations of a station and a counterpart station when a station cannot transmit and can receive in an unavailable interval. If the counterpart station acquires a TXOP before entering an unavailable interval in which the station cannot transmit, the counterpart station can transmit to the station during the unavailable interval. At this time, the counterpart station can transmit an initial control frame to the station before the unavailable interval and receive a response frame to the initial control frame from the station. In addition, the counterpart station can transmit an initial control frame so that the station can transmit a response frame before the unavailable interval. The counterpart station can only perform transmissions that do not request an immediate response during the unavailable interval. In addition, the counterpart station cannot transmit a trigger frame to the station. In these embodiments, if the station can transmit an immediate response after passing through the unavailable interval, the counterpart station can perform transmissions requesting an immediate response from the station during the unavailable interval. In addition, if the station can transmit a TB PPDU after passing through the unavailable interval, the counterpart station can transmit a trigger frame to the station during the unavailable interval. A station can transmit a response to an MPDU received during an unavailable interval to the other station. Specifically, a station can transmit a BlockAck frame to the other station during an unavailable interval.

[0332] FIG. 34 illustrates the operation of an AP and a non-AP station in an unavailable section where some functions are unavailable according to one embodiment of the present invention.

[0333] In the embodiment of (a) of Fig. 34, a station can transmit but cannot receive in an unavailable section. A non-AP station (STA) transmits a request frame to the AP indicating an unavailable section of a periodic IDC. The AP, which receives the request frame, transmits a response frame to the non-AP station (STA) accepting the unavailable section. The AP obtains a TXOP before the unavailable section. The AP transmits a trigger frame to trigger transmission of the non-AP station (STA) before the non-AP station (STA) enters the unavailable section. At this time, the AP sets the value of the CS required field of the User Info field corresponding to the non-AP station (STA) in the trigger frame to 0. The non-AP station (STA) transmits a TB PPDU. At this time, the non-AP station (STA) includes only an MPDU having a TID whose Ack Policy is No Ack in the TB PPDU. Additionally, as previously explained, if a non-AP station (STA) expects a response to a TB PPDU to be transmitted past an unavailable interval, the non-AP station (STA) includes an MPDU requesting an immediate response in the TB PPDU. The AP receives it from the non-AP station (STA) and does not transmit a response to the MPDU included in the TB PPDU during the unavailable interval.

[0334] Additionally, a non-AP station (STA) can acquire a TXOP before the unavailable period and transmit data to the AP during the unavailable period. The non-AP station (STA) transmits to the AP only MPDUs with a TID whose Ack Policy is No Ack. As described above, if the non-AP station (STA) expects that a response to an MPDU will be transmitted after the unavailable period, the non-AP station (STA) transmits to the AP an MPDU requesting an immediate response, for example, an MPDU with a TID whose Ack Policy is not No ACK. The AP receives a TB PPDU from the non-AP station (STA) and does not transmit a response to the MPDU included in the TB PPDU during the unavailable period. The AP transmits a BlockAck frame after the unavailable period.

[0335] In the embodiment of (b) of Fig. 34, a station can perform reception but cannot perform transmission in an unavailable section. A non-AP station (STA) transmits a request frame indicating an unavailable section of a periodic IDC to the AP. The AP, which receives the request frame, transmits a response frame accepting the unavailable section to the non-AP station (STA). The AP obtains a TXOP before the unavailable section. The AP transmits an initial control frame to the non-AP station (STA) before the non-AP station (STA) enters the unavailable section. The non-AP station (STA) transmits a response frame to the initial control frame to the AP. At this time, the AP transmits only MPDUs having a TID whose Ack Policy is No Ack to the non-AP station (STA) in the unavailable section. Additionally, as previously explained, if a non-AP station (STA) expects that a response to an MPDU will be transmitted after the unavailable interval, the non-AP station (STA) transmits an MPDU requesting an immediate response, e.g., an MPDU with a TID whose Ack Policy is not No Ack, to the non-AP station (STA). The non-AP station (STA) receives data from the AP and does not transmit a response to the MPDU included in the data during the unavailable interval. The non-AP station (STA) transmits a BlockAck frame after the unavailable interval.

[0336]

[0337] <P2P TWT를 이용한 수신 불가능 및 전송 불가능 지시>

[0338] Figure 35 shows the format of a channel use request frame indicating reception impossibility and transmission impossibility.

[0339] Descriptions of parts identical or corresponding to the embodiment of Fig. 14 are omitted. Fig. 35 (a) shows the format of a channel use request frame. Fig. 35 (b) shows the format of a Channel Usage element of a channel use request frame. Fig. 35 (c) shows the format of a TWT element of a channel use request frame. Fig. 35 (d) shows the format of an individual TWT parameter set indicated in a TWT Parameter Information field of a TWT element of a channel use request frame. Fig. 35 (e) shows the format of a field indicating whether a station is unable to receive or transmit in an unavailable section.

[0340] As described above, a station may include information on whether reception is unavailable and information on whether transmission is unavailable in a channel use request frame for indicating P2P TWT. Specifically, it may be included in a part of a field indicating information on an unavailable section of the use request frame. In this case, the field indicating whether reception is unavailable and the field indicating whether transmission is unavailable may be a single field. The field indicating the information on whether reception is unavailable and the information on whether transmission is unavailable may be referred to as a Tx / Rx Unavailable subfield. In another specific embodiment, the field indicating whether reception is unavailable and the field indicating whether transmission is unavailable may be distinguished as different fields. The subfield indicating the information on whether transmission is unavailable may be referred to as a Tx Unavailable subfield, and the subfield indicating the information on whether reception is unavailable may be referred to as an Rx Unavailable subfield.

[0341] As described above, a station can indicate information regarding its reception capability. Specifically, it can indicate the station's interference power level or expected maximum MCS. The field indicating information regarding its reception capability may be referred to as the Rx Capable Parameter subfield. The field indicating the station's interference power level may be referred to as the Expected Interference Power Level subfield. The subfields described through (e) of FIG. 35 may be included in the Channel Usage element or the TWT element. The setting of the value of each subfield and the operation of the station and the counterpart station according to the value of each field may follow the embodiments described above.

[0342] The embodiments described above regarding information regarding transmission impossibility and reception impossibility can also be applied to the unavailable periods of irregular IDCs. Specifically, the embodiments regarding the method for determining the timing of frame exchange and the MPDU to be exchanged between a station and a counterpart station based on the information regarding transmission impossibility and reception impossibility can be applied equally. In addition, a station can include a field indicating information regarding transmission impossibility and a field indicating information regarding reception impossibility in the subfields of the Per AID TID Info field of a Multi-STA BlockAck frame.

[0343] FIG. 36 shows an AP and a non-AP station exchanging information about an unavailable section and performing frame exchange according to the information about the unavailable section according to an embodiment of the present invention.

[0344] In the embodiment of (a) of Fig. 36, a station can perform reception but cannot perform transmission in the unavailable section. The AP transmits an initial control frame (ICF) to a non-AP station (STA). The non-AP station (STA) transmits a response frame (ICR) to the initial control frame to the AP. At this time, the response frame indicates the unavailable section of the aperiodic IDC. The AP transmits to the non-AP station (STA) only MPDUs having a TID whose Ack Policy is No Ack in the unavailable section. In addition, as described above, if the non-AP station (STA) expects that a response to an MPDU will be transmitted past the unavailable section, the non-AP station (STA) transmits an MPDU requesting an immediate response, for example, an MPDU having a TID whose Ack Policy is not No ACK, for example, a TID whose ACK Policy is BlockAck, to the non-AP station (STA). The non-AP station (STA) receives data from the AP and does not transmit a response to an MPDU included in the data in the unavailable section. A non-AP station (STA) transmits a BlockAck frame after an unavailable period.

[0345] In the embodiment of (b) of Fig. 36, a station can transmit but cannot receive in an unavailable section. The AP transmits an initial control frame (ICF) to a non-AP station (STA). The non-AP station (STA) transmits a response frame (ICR) to the initial control frame to the AP. At this time, the response frame indicates an unavailable section of the aperiodic IDC. The AP transmits a frame indicating an RDG before the non-AP station (STA) enters the unavailable section. The non-AP station (STA) transmits a UL PPDU in the unavailable section. At this time, the non-AP station (STA) includes only an MPDU with a TID whose Ack Policy is No Ack in the UL PPDU. In addition, as described above, if the non-AP station (STA) expects that a response to the UL PPDU will be transmitted past the unavailable section, the non-AP station (STA) includes an MPDU requesting an immediate response in the TB PPDU. Additionally, if a non-AP station (STA) wants to transmit a UL PPDU again after transmitting a UL PPDU, the non-AP station (STA) sets the value of the More PPDU field to 1. The AP receives from the non-AP station (STA) and does not transmit a response to the MPDU included in the TB PPDU during the unavailable interval.

[0346]

[0347] An AP can transmit information about low-latency traffic that the AP intends to transmit to a non-AP station. At this time, the non-AP station can determine whether to prioritize an operation causing IDC or the low-latency traffic. The information about the low-latency traffic can include at least one of the latency bound, priority, or TID of the low-latency data. The AP can transmit information about the low-latency traffic using an initial control frame. At this time, the initial control frame can be a control frame, such as a BSR trigger frame or an (MU-)RTS trigger frame. Based on the information about the low-latency traffic, the non-AP station can compare the urgency of the low-latency traffic with the importance of the operation causing the IDC and decide whether to perform the operation causing the IDC. At this time, the non-AP station can transmit a response frame to the initial control frame, which includes information about the decision, to the AP. If the urgency of low-latency traffic is deemed more critical, the non-AP station may transmit a response frame to the AP that does not include information about the unavailable interval due to IDC. If the operation causing the IDC is deemed more critical, the non-AP station may transmit a response frame to the AP that includes information about the unavailable interval due to IDC. In this case, the AP may terminate its TXOP in advance of the unavailable interval.

[0348] As described above, a station can transmit reception unavailable information and transmission unavailable information using the Per AID TID Info field of the Multi-STA BlockAck frame. At this time, the format of the Per AID TID Info field can follow the embodiments described through FIG. 29. In the embodiments described through FIG. 29, the Per AID TID Info field can include the Tx / Rx Unavailable subfield, the Tx Unavailable subfield, or the Rx Unavailable subfield of the embodiments described through (e) of FIG. 35. Specifically, the BA Bitmap field of the Per AID TID Info field can include the Tx / Rx Unavailable subfield, the Tx Unavailable subfield, or the Rx Unavailable subfield. This will be described with reference to FIG. 37.

[0349] Figure 37 shows the format of the Per AID TID Info field according to an embodiment of the present invention.

[0350] Figure 37 (a) shows the format of the Per AID TID Info field of the BA Information field of the Multi-STA Block Ack frame. Figure 37 (b) shows the AID TID Info subfield of the Per AID TID Info field. Figure 37 (c) shows the format of the BA Bitmap subfield indicating information about the type and time of an unavailable interval. Figure 37 (d) shows the format of the BA Bitmap subfield indicating information about the type and time of the unavailable interval together with the information type of the unavailable interval. Figure 37 (e) shows the format of the BA Bitmap subfield indicating information about the type and time of the unavailable interval together with information about the reception capability.

[0351] The Per AID TID Info field can indicate the type of information of the unavailable section included in the Per AID TID Info field by combining the values ​​of at least two fields among the Ack Type field, the AID11 field, and the TID field of the Per AID TID Info field. The type of information of the unavailable section can indicate any one of reception and transmission impossibility, reception impossibility, and transmission impossibility. In this embodiment, the value of the Ack Type field can be 0, the value of the AID11 field can be 2024 or higher, and the value of the TID field can be any one of 8 to 15.

[0352] As previously explained, the unavailable-to-receive information and the unavailable-to-transmit information may be indicated by a single subfield (Tx / Rx Unavailable subfield) or by separate subfields (Tx Unavailable subfield and Rx Unavailable subfield). The description of other subfields may be the same as in the embodiments explained through FIG. 29.

[0353] As previously explained, frame exchange sequences can be managed based on information about unavailable periods due to IDC. The opposing station can determine when to transmit to the station based on information about the station's unavailable periods. Specifically, during a station's unavailable period, a station may be permitted to transmit to the AP, but the opposing station may not be permitted to transmit to the station. Furthermore, during a station's unavailable period, the opposing station may not be permitted to transmit to the station.

[0354]

[0355] <AP RU Allocation in Unavailable Area>

[0356] As described above, a station can transmit to the AP information about RUs in which the station can operate, such as information about alternative operating bandwidths, in an unavailable section. The AP can exchange frames with the station only using RUs in which the station can operate in the unavailable section. Specifically, the AP can allocate RUs for DL ​​PPDU transmission or UL PPDU transmission to the station based on the information about RUs in which the station can operate in the unavailable section. At this time, the DL PPDU may be a DL MU PPDU. The AP can indicate the RU allocated to the station using the STA-ID field and the RU Allocation field of the UHR-SIG content channel in the DL MU PPDU. The AP can set the last MPDU of the A-MPDU included in the DL PPDU to a triggering frame, such as an MU-BAR trigger frame, a basic trigger frame, or a frame including a TRS field, to indicate a response to the DL PPDU. At this time, the RU Allocation field of the trigger frame is used to allocate available RUs to the station. This prevents the station from attempting to transmit a response to a DL PPDU using an unavailable RU in an unavailable interval.

[0357] FIG. 38 shows the operation of an AP that allocates RUs to a station based on information about unavailable RUs in an unavailable section of the station according to an embodiment of the present invention.

[0358] A non-AP station (STA) operating in the 80 MHz band indicates to the AP that the first 20 MHz subchannel (20MHz-1), the second 20 MHz subchannel (20MHz-2), and the fourth 20 MHz subchannel (20MHz-4) are unavailable during the unavailable period. When transmitting a DL MU PPDU, the AP allocates the third 20 MHz subchannel (20MHz-3) to the non-AP station (STA). At this time, a triggering frame is included in the last MPDU of the A-MPDU in the DL MU PPDU, and the triggering frame allocates the third 20 MHz subchannel (20MHz-3) to the non-AP station (STA). At this time, since the non-AP station (STA) cannot use the primary 20 MHz subchannel, it can perform channel switching to check the preamble before the unavailable period.

[0359]

[0360] As described above, a station may support multiple different communication technologies, including wireless LAN. In this case, wireless LAN communication may be unavailable due to the use of one of the technologies. The station may transmit information about an unavailable period, which is a time period during which wireless LAN communication is restricted, to the other station. Specifically, the station may transmit a frame including information about the unavailable period to the other station. The information about the unavailable period may include the start time of the unavailable period and the duration of the unavailable period. In addition, the information about the unavailable period may include information indicating an unavailable channel. In addition, the information about the unavailable period may include information about an unavailable channel in the unavailable period. In addition, the information about the unavailable period may include information about an alternative operating bandwidth, which is an available channel other than the unavailable channel, on which the station will operate in the unavailable period. The content and format of the information of the unavailable section may follow the embodiments described above with reference to FIGS. 11 to 13, 15 to 16, 23, 29, and 35 to 37.

[0361] A frame indicating information about an unavailable section may be a response frame or an initial control frame transmitted by a station to a counterpart station. The response frame may be a frame indicating ACK. The frame indicating ACK may include at least one of an ACK frame, a BlockAck frame, or a Multi-STA BlockACK frame. The specific format of the frame indicating ACK may follow the embodiments described with reference to FIGS. 16, 20 to 33, and 37. The initial control frame may be a trigger frame. The trigger frame may be either an MU-RTS trigger frame or a BSRP (Buffer Status Report Poll) trigger frame. If the Multi-STA Block ACK frame includes a Per AID TID Info field indicating information about an unavailable section, the counterpart station may set the value of the Duration field of the frame soliciting transmission of the Multi-STA Block ACK frame based on the value obtained by adding the length of the Per AID TID Info field indicating information about the unavailable section to the length of the field indicating whether traffic is received. At this time, the frame soliciting transmission of the Multi-STA Block ACK frame may be an Aggregated MAC Protocol Data Unit (A-MPDU), a Block Ack Request (BAR) frame, or a Multi User Block Ack Request (MU-BAR) frame including a Quality of Service (Qos) data frame.Specifically, the originator station may set the value of the Duration field of the frame soliciting transmission of the Multi-STA Block ACK frame by considering the value of the largest Block Ack Bitmap length based on the negotiated buffer size and the value of the length of information about the unavailable interval to be transmitted through the Multi-STA Block Ack frame. At this time, the QoS data frame may include a management frame requesting an immediate Block Ack frame response or requesting an ACK. Embodiments regarding the initial control frame may follow the embodiments described above.

[0362] A frame indicating information about an unavailable interval may indicate cancellation of a previously set unavailable interval. If a frame indicating information about an unavailable interval to an AP indicates cancellation of a previously set unavailable interval, the duration of the unavailable interval may be indicated as a pre-specified value. The pre-specified value may be 0. In addition, the start time of the unavailable interval may be indicated as a pre-specified value. In this case, the pre-specified value may be 0. Specific operations of the station and the counterpart station may follow the embodiments regarding information change and cancellation described through FIGS. 12, 20 to 22, 24 to 25, and 27 to 28.

[0363] Information regarding unavailable intervals may include information indicating an alternative operating band in which the station will operate during the unavailable interval. Operations of the station and the counterpart station may follow the embodiments regarding alternative operating bandwidths described in FIGS. 13, 14, 17, and 38.

[0364] A frame indicating information about an unavailable section may include information about multiple unavailable sections including the unavailable section. The operations of the station and the counterpart station regarding the multiple unavailable sections may follow the embodiments described in FIGS. 26 to 28 , etc.

[0365]

[0366] While the present invention has been described using wireless LAN communication as an example, it is not limited thereto and can be equally applied to other communication systems, such as cellular communication. Furthermore, while the methods, devices, and systems of the present invention have been described with reference to specific embodiments, some or all of the components and operations of the present invention can be implemented using a computer system with a general-purpose hardware architecture.

[0367] The features, structures, effects, etc. described in the embodiments above are included in at least one embodiment of the present invention, and are not necessarily limited to just one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment can be combined or modified in other embodiments by those skilled in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be construed as being included within the scope of the present invention.

[0368] Although the above has been described focusing on embodiments, these are merely examples and do not limit the present invention. Those skilled in the art to which the present invention pertains will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present embodiment. For example, each component specifically shown in the embodiments can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention defined in the appended claims.

Claims

1. In a non-AP station that supports multiple different communication technologies and communicates with the AP using wireless LAN, Transmitter and receiver; and Contains a processor, The above processor Transmitting a frame indicating information on an unavailable period of the non-AP station to the AP, wherein the unavailable period is a time period during which communication of the non-AP station is restricted; Information on the above unavailable section includes the start time of the above unavailable section and the duration of the above unavailable section. non-AP station.

2. In paragraph 1, The frame that indicates information about the unavailable section to the AP is a Multi-STA BlockAck frame or trigger frame transmitted by the non-AP station to the AP. non-AP station.

3. In paragraph 1, The frame indicating the unavailable section information to the above AP indicates the cancellation of the previously set unavailable section. non-AP station.

4. In paragraph 3, If the frame indicating information of the unavailable interval to the above AP indicates cancellation of a previously set unavailable interval, the duration of the unavailable interval is indicated as a pre-specified value. non-AP station.

5. In paragraph 4, The above predefined value is 0 non-AP station.

6. In paragraph 1, The information of the above unavailable section includes information indicating an alternative operating band in which the non-AP station will operate in the above unavailable section. non-AP station.

7. In paragraph 1, The frame indicating information of the above unavailable section includes information of multiple unavailable sections including the above unavailable section. non-AP station.

8. In paragraph 1, The frame indicating information about the above unavailable section is a Multi-STA Block Ack frame, The value of the Duration field of the frame that solicits the transmission of the Multi-STA Block Ack frame is set based on the sum of the length of the Per AID TID Info field indicating information on the impossible section and the field indicating whether traffic is received. non-AP station.

9. In an AP that communicates using wireless LAN with a non-AP station that supports multiple different communication technologies, Transmitter and receiver; and Contains a processor, The above processor Receive a frame indicating information on an unavailable period of the non-AP station from the non-AP station, wherein the unavailable period is a time period during which communication of the non-AP station is restricted; Information on the above unavailable section includes the start time of the above unavailable section and the duration of the above unavailable section. AP.

10. In paragraph 9, The frame that indicates information about the unavailable section to the AP is a Multi-STA BlockAck frame or trigger frame transmitted by the non-AP station to the AP. AP.

11. In paragraph 9, The frame indicating the unavailable section information to the above AP indicates the cancellation of the previously set unavailable section. AP.

12. In paragraph 11, If the frame indicating information of the unavailable interval to the above AP indicates cancellation of a previously set unavailable interval, the duration of the unavailable interval is indicated as a pre-specified value. AP.

13. In paragraph 12, The above predefined value is 0 AP.

14. In paragraph 9, The information of the above unavailable section includes information indicating an alternative operating band in which the non-AP station will operate in the above unavailable section. AP.

15. In paragraph 9, The frame indicating information of the above unavailable section includes information of multiple unavailable sections including the above unavailable section. AP.

16. In paragraph 9, The frame indicating information about the above unavailable section is a Multi-STA Block Ack frame, The above processor The value of the Duration field of the frame that solicits the transmission of the Multi-STA Block Ack frame is set based on the value obtained by adding the length of the Per AID TID Info field indicating information of the impossible section and the field indicating whether traffic is received. AP.

17. In the operation method of a non-AP station that supports multiple different communication technologies and communicates with the AP using wireless LAN. A step of transmitting a frame indicating information about the unavailable section of the non-AP station to the AP, The above unavailable period is a time period during which communication of the non-AP station is restricted. Information on the above unavailable section includes the start time of the above unavailable section and the duration of the above unavailable section. How it works.

18. In paragraph 17, The frame that indicates information about the unavailable section to the AP is a Multi-STA BlockAck frame or trigger frame transmitted by the non-AP station to the AP. How it works.

19. In paragraph 17, The frame indicating the unavailable section information to the above AP indicates the cancellation of the previously set unavailable section. How it works.

20. In the operation method of an AP that communicates using wireless LAN with a non-AP station that supports multiple different communication technologies. A step of receiving a frame indicating information on an unavailable section of the non-AP station from the non-AP station, The above unavailable period is a time period during which communication of the non-AP station is restricted. Information on the above unavailable section includes the start time of the above unavailable section and the duration of the above unavailable section. How it works.

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