Method and apparatus for low latency communications in dense environments

Abstract

A method and apparatus for low latency communication in a dense environment are disclosed. The method of a first STA comprises the steps of: checking a first SP configured by a first AP connected to the first STA; checking a second SP configured by the second AP; checking that the first SP is overlapped with the second SP; a measurement report frame indicating an overlap between the first SP and the second SP is transmitted to the first AP.

Description

Technical Field

[0001] The present invention relates to a wireless local area network (WLAN) communication technology, and more particularly, to a technology for configuring a restricted target wake time (R-TWT) in a dense WLAN environment. Background Art

[0002] Recently, with the popularity of mobile devices, wireless local area network technology that can provide fast wireless communication services to mobile devices has become a focus. Wireless local area network technology can be a technology that supports mobile devices (e.g., smart phones, smart tablets, laptops, portable multimedia players, embedded devices, etc.) to wirelessly access the Internet based on wireless communication technology.

[0003] The IEEE 802.11ac standard has expanded the bandwidth used (e.g., a maximum of 160 MHz bandwidth or 80+80 MHz bandwidth) and also increased the number of supported spatial streams. The IEEE 802.11ac standard may refer to a very high throughput (VHT) wireless local area network technology capable of supporting data rates exceeding 1 gigabit per second (Gbps). The IEEE 802.11ac standard may utilize MIMO technology to support downlink transmission to multiple stations.

[0004] As applications requiring higher throughput and applications requiring real-time transmission emerge, the IEEE 802.11be standard is being developed, which is an extreme high throughput (EHT) wireless LAN technology. The goal of the IEEE 802.11be standard may be to support an ultra-high throughput of 30 Gbps. The IEEE 802.11be standard may support technologies for reducing transmission delays. In addition, the IEEE 802.11be standard may support a more extended frequency bandwidth (e.g., 320 MHz bandwidth), multi-link transmission and aggregation operations including multi-band operation, multi-access point (AP) transmission operation, and / or efficient retransmission operation (e.g., hybrid automatic repeat request (HARQ) operation).

[0005] Multiple links may be used in a wireless LAN, and specific operations may need to be defined for a wireless LAN that supports multiple links. For example, a restricted target wake time (R-TWT) operation for low-latency communication may be defined. In a dense wireless LAN environment, time periods for low-latency communication (e.g., R-TWT service periods (SPs)) may overlap in the time domain. For example, multiple terminals may attempt to communicate within an R-TWT SP. In this case, low-latency communication may be interrupted, and the expected low-latency communication may not be performed. Therefore, a method may be required to reconfigure the R-TWT SP when it overlaps in the time domain to prevent such overlap.

[0006] On the other hand, the technical writing in the background art of the present invention is to enhance the understanding of the background art of the present invention and may include contents that are not known to those of ordinary skill in the art to which the present invention belongs. Summary of the invention

[0007] Technical issues

[0008] The present invention is directed to providing a method and apparatus for changing and / or reconfiguring a restricted target wake time (R-TWT) in a wireless local area network.

[0009] Technical Solution

[0010] According to an exemplary embodiment of the present invention, a method for a first station (STA) to achieve the above-mentioned purpose may include: identifying a first service period (SP) configured by a first access point (AP) associated with the first STA; identifying a second SP configured by a second AP; determining that the first SP overlaps with the second SP; and sending a measurement report frame to the first AP indicating the overlap between the first SP and the second SP.

[0011] The first SP may be identified based on first target wake time (TWT) configuration information included in a first beacon frame received from a first AP, and the second SP may be identified based on second TWT configuration information included in a second beacon frame or a probe response frame received from a second AP.

[0012] The measurement report frame may include at least one of information about the second AP or second TWT configuration information for the second SP.

[0013] If the first SP is predicted to overlap with the second SP, the measurement report frame may be transmitted before the first SP or the second SP, or if the first SP is determined to overlap with the second SP, the measurement report frame may be transmitted after the first SP or the second SP.

[0014] The method may further include receiving a measurement request frame from the first AP, wherein the measurement request frame may indicate an overlap between the first SP and the second SP, and transmitting the measurement report frame upon receiving the measurement request frame.

[0015] The method may further include: receiving a third beacon frame including TWT reconfiguration information for the first SP from the first AP; identifying a changed first SP based on the TWT reconfiguration information; and performing communication in the changed first SP, wherein the changed first SP does not overlap with the second SP.

[0016] According to an exemplary embodiment of the present invention, a method for a first access point (AP) to achieve the above-mentioned purpose may include: sending a first beacon frame including first target wake-up time (TWP) configuration information for a first service period (SP); receiving a measurement report frame from a first STA indicating an overlap between the first SP and a second SP configured by a second AP; and sending a second beacon frame including TWT reconfiguration information for the first SP, wherein the first SP changed by the TWT reconfiguration information does not overlap with the second SP.

[0017] The measurement report frame may include at least one of information about the second AP or second TWT configuration information for the second SP.

[0018] If the first SP of the first STA is predicted to overlap with the second SP, the measurement report frame may be received before the first SP or the second SP, or if the first SP of the first STA is determined to overlap with the second SP, the measurement report frame may be sent after the first SP or the second SP.

[0019] The method may further include: in response to determining that the first SP overlaps with the second SP, sending a measurement request frame, wherein the measurement report frame may be received as a response to the measurement request frame.

[0020] According to an exemplary embodiment of the present invention, a method for a first station (STA) to achieve the above-mentioned purpose may include: identifying a first service period (SP) configured by a first access point (AP) associated with the first STA; detecting overlapping basic service set (OBSS) interference in the first SP; and sending a measurement report frame indicating the occurrence of OBSS interference to the first AP.

[0021] The first SP may be identified based on first target wake time (TWT) configuration information included in a first beacon frame received from the first AP, and the OBSS interference may be caused by a communication node belonging to the OBSS.

[0022] The measurement report frame may include a cause code, and the cause code may indicate the occurrence of OBSS interference.

[0023] The method may further include: receiving a second beacon frame including TWT reconfiguration information for the first SP from the first AP; identifying a changed first SP based on the TWT reconfiguration information; and performing communication in the changed first SP, wherein OBSS interference does not occur in the changed first SP.

[0024] Beneficial Effects

[0025] According to the present invention, low-latency communication between communication nodes (e.g., AP, STA, etc.) can be performed within an R-TWT SP. When the R-TWT SPs for multiple communication nodes are configured to overlap in the time domain, low-latency communication may not be achieved. For example, a first communication node may be configured with a first R-TWT SP, and a second communication node may be configured with a second R-TWT SP. A third communication node may perform low-latency communication within the first R-TWT SP of the first communication node, and a fourth communication node may perform low-latency communication within the second R-TWT SP of the second communication node.

[0026] When the first R-TWT SP overlaps with the second R-TWT SP in the time domain, the first communication node may send information (e.g., an indicator) indicating the overlap of the R-TWT SP to the third communication node, and the second communication node may send information (e.g., an indicator) indicating the overlap of the R-TWT SP to the fourth communication node. Accordingly, the first communication node and / or the second communication node may change and / or reconfigure the R-TWT SP to ensure that they do not overlap. Therefore, low-latency communication can be performed within the R-TWT SP, and communication latency can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a block diagram showing a first exemplary embodiment of a communication node constituting a wireless LAN system.

[0028] Figure 2 is a conceptual diagram showing a first exemplary embodiment of multi-links configured between multi-link devices (MLDs).

[0029] Figure 3 is a timing diagram illustrating a first exemplary embodiment of R-TWT operation.

[0030] Figure 4 is a conceptual diagram illustrating a first exemplary embodiment of a dense environment.

[0031] Figure 5 is a timing diagram illustrating a first exemplary embodiment of the R-TWT operation problem in a dense environment.

[0032] Figure 6is a timing diagram illustrating a first exemplary embodiment of an R-TWT SP reporting method in a dense environment.

[0033] Figure 7 is a timing diagram illustrating a second exemplary embodiment of an R-TWT SP reporting method in a dense environment.

[0034] Figure 8 is a timing diagram illustrating a third exemplary embodiment of an R-TWT SP reporting method in a dense environment.

[0035] Fig. 9 is a timing diagram illustrating a first exemplary embodiment of a method for changing an R-TWT SP in a dense environment.

[0036] Fig.10 is a timing diagram illustrating a second exemplary embodiment of a method for changing an R-TWT SP in a dense environment.

[0037] Fig.11 is a timing diagram illustrating a third exemplary embodiment of a method for changing an R-TWT SP in a dense environment.

[0038] Fig.12 is a timing diagram illustrating a first exemplary embodiment of a method for changing R-TWT SP and links in a dense environment.

[0039] Fig.13 is a timing diagram illustrating a second exemplary embodiment of a method for changing R-TWT SP and links in a dense environment. DETAILED DESCRIPTION

[0040] Since the present invention can be modified in various ways and has several forms, specific exemplary embodiments will be shown in the attached drawings and described in detail in the specific specification. However, it should be understood that this is not intended to limit the present invention to specific exemplary embodiments, on the contrary, the present invention covers all modified embodiments and alternative embodiments falling within the spirit and scope of the present invention.

[0041] Relational terms such as first, second, etc. can be used to describe various elements, but these elements should not be limited by the terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present invention, a first component can be named as a second component, and the second component can also be similarly named as the first component. The term "and / or" means any one or combination of multiple related and described matters.

[0042] In an exemplary embodiment of the present invention, "at least one of A and B" may mean "at least one of A or B" or "at least one of a combination of one or more of A and B". In addition, "one or more of A and B" may mean "one or more of A or B" or "one or more of a combination of one or more of A and B".

[0043] When it is mentioned that a certain component is "engaged" or "connected" to another component, it should be understood that the certain component is directly "engaged" or "connected" to the other component, or a further component may be arranged between them. On the contrary, when it is mentioned that a certain component is "directly engaged" or "directly connected" to another component, it should be understood that no further component is arranged between them.

[0044] The terms used in the present invention are only used to describe specific exemplary embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "including" or "having" are intended to indicate the presence of features, values, steps, operations, components, parts, or combinations thereof described in the specification, but it should be understood that these terms do not exclude the presence or addition of one or more features, values, steps, operations, components, parts, or combinations thereof.

[0045] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as those generally understood by those of ordinary skill in the art to which the present invention belongs. Terms commonly used and appearing in dictionaries should be interpreted as having meanings that match the contextual meanings in the art. In this specification, unless explicitly defined, terms are not necessarily interpreted as having formal meanings.

[0046] Hereinafter, the form of the present invention will be described in detail with reference to the attached drawings. In describing the present invention, in order to facilitate a comprehensive understanding of the present invention, the same reference numerals refer to the same elements throughout the description of the drawings, and their repeated description will be omitted.

[0047] Hereinafter, a wireless communication system according to an exemplary embodiment of the present invention will be described. The wireless communication system according to the exemplary embodiment of the present invention is not limited to the content described below, and can be applied to various wireless communication networks according to the exemplary embodiment of the present invention. The wireless communication system can be referred to as a "wireless communication network".

[0048] In an exemplary embodiment, "configuration of an operation (e.g., a transmission operation)" may mean signaling "configuration information (e.g., information element, parameter) of an operation" and / or "information indicating the execution of an operation". "Configuration of an information element (e.g., parameter)" may mean signaling an information element. "Configuration of a resource (e.g., a resource region)" may mean signaling setting information of a resource.

[0049] Figure 1 is a block diagram showing a first exemplary embodiment of a communication node constituting a wireless LAN system.

[0050] like Figure 1 As shown, the communication node 100 may be an access point, a station, an access point (AP) multi-link device (MLD), or a non-AP MLD. An access point may be referred to as an "AP", and a station may be referred to as a "STA" or a "non-AP STA". The operating channel width supported by an AP may be 20 megahertz (MHz), 80 MHz, 160 MHz, etc. The operating channel width supported by a STA may be 20 MHz, 80 MHz, etc.

[0051] The communication node 100 may include at least one processor 110, a memory 120, and a transceiver 130 connected to a network for communication. The transceiver 130 may be referred to as a transceiver, a radio frequency (RF) unit, an RF module, etc. In addition, the communication node 100 may further include an input interface device 140, an output interface device 150, a storage device 160, etc. The various components included in the communication node 100 may be connected to communicate with each other via a bus 170.

[0052] However, the respective components included in the communication node 100 may be connected through a separate interface or a separate bus centered around the processor 110 instead of the common bus 170. For example, the processor 110 may be connected to at least one of the memory 120, the transceiver 130, the input interface device 140, the output interface device 150, and the storage device 160 through a dedicated interface.

[0053] The processor 110 may execute program instructions stored in at least one of the memory 120 and the storage device 160. The processor 110 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor that executes a method according to an exemplary embodiment of the present invention. Each of the memory 120 and the storage device 160 may be configured as at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 120 may be configured with at least one of a read-only memory (ROM) and a random access memory (RAM).

[0054] Figure 2 is a conceptual diagram showing a first exemplary embodiment of multi-links configured between multi-link devices (MLDs).

[0055] like Figure 2 As shown, the MLD may have a media access control (MAC) address. In an exemplary embodiment, the MLD may refer to an AP MLD and / or a non-AP MLD. The MAC address of the MLD may be used in a multi-link establishment process between a non-AP MLD and an AP MLD. The MAC address of the AP MLD may be different from the MAC address of the non-AP MLD. APs associated with an AP MLD may have different MAC addresses, and stations associated with a non-AP MLD may have different MAC addresses. Each AP with a different MAC address within an AP MLD may be responsible for each link and may function as an independent AP.

[0056] Each STA with a different MAC address within a non-AP MLD may be responsible for each link and may function as an independent STA. A non-AP MLD may be referred to as a STA MLD. An MLD may support simultaneous transmit and receive (STR) operations. In this case, the MLD may perform a transmit operation in link 1 and may perform a receive operation in link 2. An MLD that supports STR operations may be referred to as an STR MLD (e.g., STR AP MLD, STR non-AP MLD). In an exemplary embodiment, a link may refer to a channel or a frequency band. A device that does not support STR operations may be referred to as a non-STR (NSTR) AP MLD or an NSTR non-AP MLD (or an NSTR STA MLD).

[0057] MLD can send and receive frames in multiple links by using a non-contiguous bandwidth extension scheme (e.g., 80MHz+80MHz). Multi-link operation may include multi-band transmission. AP MLD may include multiple APs, and the multiple APs may operate in different links. Each of the multiple APs may perform the function of the lower MAC layer. Each of the multiple APs may be referred to as a "communication node" or a "lower entity". The communication node (i.e., AP) may be in the upper layer (or Figure 1 The non-APMLD may include multiple STAs, and the multiple STAs may operate in different links. Each of the multiple STAs may be referred to as a "communication node" or a "lower entity". The communication node (i.e., STA) may be in the upper layer (or Figure 1 Operates under the control of the processor 110 shown.

[0058] MLD can communicate in multiple frequency bands (i.e., multi-band). For example, MLD can communicate using 80MHz bandwidth according to a channel extension scheme (e.g., bandwidth extension scheme) in the 2.4GHz band, and use 160MHz bandwidth according to a channel extension scheme in the 5GHz band. MLD can communicate using 160MHz bandwidth in the 5GHz band, and can communicate using 160MHz bandwidth in the 6GHz band. A frequency band (e.g., a channel) used by MLD can be defined as a link. Alternatively, multiple links can be configured in a frequency band used by MLD. For example, MLD can configure one link in the 2.4GHz band and two links in the 6GHz band. Each link can be referred to as a first link, a second link, and a third link. Alternatively, each link can be referred to as link 1, link 2, link 3, etc. The link number can be set by the access point, and an identifier (ID) can be assigned to each link.

[0059] MLD (e.g., AP MLD and / or non-AP MLD) may configure multi-link by performing an access process and / or a negotiation process for multi-link operation. In this case, the number of (one and / or more) links to be used in the multi-link may be configured. Non-AP MLD (e.g., STA) may identify information about a frequency band capable of communicating with AP MLD. In the negotiation process of multi-link operation between non-AP MLD and AP MLD, non-AP MLD may configure one or more of the links supported by AP MLD for multi-link operation. A station that does not support multi-link operation (e.g., IEEE 802.11a / b / g / n / ac / ax STA) may be connected to one or more links of the multi-link supported by AP MLD.

[0060] When the frequency band spacing between multiple links (e.g., the frequency band spacing between link 1 and link 2 in the frequency domain) is sufficient, the MLD may be able to perform the STR operation. For example, the MLD may use link 1 among the multiple links to send a physical layer convergence procedure (PLCP) protocol data unit (PPDU) 1, and may use link 2 among the multiple links to receive PPDU 2. On the other hand, if the MLD performs the STR operation when the frequency band spacing between the multiple links is insufficient, in-device coexistence (IDC) interference, which is interference between the multiple links, may occur. Accordingly, when the bandwidth spacing between the multiple links is insufficient, the MLD may not be able to perform the STR operation. The link pair having the above-mentioned interference relationship may be a link pair with non-simultaneous transmit and receive (NSTR) restrictions. Here, the MLD may be referred to as an "NSTR APMLD" or an "NSTR non-AP MLD."

[0061] For example, a multilink including link 1, link 2, and link 3 may be configured between the AP MLD and the non-AP MLD 1. When the frequency band spacing between link 1 and link 3 is sufficient, the AP MLD may perform the STR operation using link 1 and link 3. That is, the AP MLD may send a frame using link 1 and receive a frame using link 3. When the frequency band spacing between link 1 and link 2 is insufficient, the AP MLD may not be able to perform the STR operation using link 1 and link 2. When the frequency band spacing between link 2 and link 3 is insufficient, the AP MLD may not be able to perform the STR operation using link 2 and link 3.

[0062] On the other hand, in the wireless LAN system, a negotiation process for a multi-link operation may be performed in an access process between a station and an access point.

[0063] A device (e.g., access point, station) that supports multiple links may be referred to as a "multi-link device (MLD)". An access point that supports multiple links may be referred to as an "AP MLD", and a station that supports multiple links may be referred to as a "non-AP MLD" or a "STA MLD". The AP MLD may have a physical address (e.g., MAC address) for each link. The AP MLD may be implemented as if there is a separate AP responsible for each link. Multiple APs may be managed within one AP MLD. Therefore, coordination between multiple APs belonging to the same APMLD is possible. The STA MLD may have a physical address (e.g., MAC address) for each link. The STA MLD may be implemented as if there is a separate STA responsible for each link. Multiple STAs may be managed within one STA MLD. Therefore, coordination between multiple STAs belonging to the same STA MLD is possible.

[0064] For example, AP1 of AP MLD and STA1 of STA MLD may each be responsible for the first link and communicate using the first link. AP2 of AP MLD and STA2 of STA MLD may each be responsible for the second link and communicate using the second link. STA2 may receive state change information for the first link on the second link. In this case, STAMLD may collect information (e.g., state change information) received on each link and control the operation performed by STA1 based on the collected information.

[0065] Hereinafter, a method for transmitting and receiving data in a wireless local area network system will be described. Even when describing a method (e.g., transmission or reception of a signal) performed at a first communication node among communication nodes, a corresponding second communication node may perform a method (e.g., reception or transmission of a signal) corresponding to the method performed at the first communication node. That is, when describing the operation of an STA, an AP corresponding thereto may perform an operation corresponding to the operation of the STA. Conversely, when describing the operation of an AP, an STA corresponding thereto may perform an operation corresponding to the operation of the AP.

[0066] In an exemplary embodiment, the operation of STA may be interpreted as the operation of STAMLD, the operation of STAMLD may be interpreted as the operation of STA, the operation of AP may be interpreted as the operation of AP MLD, and the operation of AP MLD may be interpreted as the operation of AP. The STA of STA MLD may refer to the STA associated with STA MLD, and the AP of AP MLD may refer to the AP associated with AP MLD. When STAMLD includes a first STA operating on a first link and a second STA operating on a second link, the operation of STAMLD on the first link may be interpreted as the operation of the first STA, and the operation of STA MLD on the second link may be interpreted as the operation of the second STA. When AP MLD includes a first AP operating on the first link and a second AP operating on the second link, the operation of AP MLD on the first link may be interpreted as the operation of the first AP, and the operation of AP MLD on the second link may be interpreted as the operation of the second AP. In an exemplary embodiment, the transmission time of a frame may refer to the transmission start time or the transmission end time, and the reception time of a frame may refer to the reception start time or the reception end time.

[0067] AP MLD, AP, STA MLD and / or STA may perform restricted target wake time (R-TWT) operation for low latency communication. In the present invention, R-TWT operation may be interpreted as TWT operation, and R-TWT service period (SP) may be interpreted as TWT SP. R-TWT SP and / or TWT SP may be simply represented as "SP". For example, R-TWT SP1 may be referred to as a first SP, and R-TWT SP2 may be referred to as a second SP.

[0068] Figure 3 is a timing diagram illustrating a first exemplary embodiment of R-TWT operation.

[0069] like Figure 3 As shown, AP1 can send a beacon frame including R-TWT configuration information (e.g., configuration information of R-TWT SP). In other words, the beacon frame can indicate the R-TWT SP. The STA can receive the beacon frame from AP1 and can identify the information elements included in the beacon frame. For example, the STA can identify the R-TWT SP based on the R-TWT configuration information included in the beacon frame. Low-latency communication between AP1 and the STA can be performed within the R-TWT SP. Conventional communication between AP1 and the STA can be performed in a period other than the R-TWT SP.

[0070] Figure 4 is a conceptual diagram illustrating a first exemplary embodiment of a dense environment.

[0071] like Figure 4 As shown, STA1 associated with STA MLD1 can connect and / or access AP1 associated with AP MLD1, and STA2 associated with STA MLD2 can connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1 or AP2 may not be associated with MLD. Alternatively, all STA1, STA2, AP1 and AP2 may not be associated with MLD. AP1 and STA1 may form a basic service set (BSS) 1, and AP2 and STA2 may form BSS2. BSS may be configured for each link (e.g., a link of MLD). For example, BSS1 may be configured for a first link, and BSS2 may be configured for a second link. BSS1 and BSS2 may support the same frequency (e.g., channel, link). BSS1 and BSS2 may be located very close physically. BSS1 and BSS2 may be overlapping BSSs (OBSS).

[0072] Due to signal attenuation, obstacles, etc., the wireless signal may only reach a certain distance. A communication node (e.g., AP and / or STA) may or may not receive the wireless signal (e.g., communication content) of another communication node. When AP1 and AP2 are located in an interference area, AP1 may not be able to receive AP2's wireless signal, and AP2 may not be able to receive AP1's wireless signal. In the interference area, AP1 may interpret AP2's wireless signal as noise, and AP2 may interpret AP1's wireless signal as noise. When AP1 and AP2 are located at a longer distance, AP1 may not be able to receive AP2's wireless signal, and AP2 may not be able to receive AP1's wireless signal.

[0073] AP1 may be a hidden node relative to AP2, and AP2 may be a hidden node relative to AP1. STA1 and AP2 may be located in a transmission area capable of sending and receiving signals (e.g., data). In this case, STA1 may receive the wireless signal of AP2. If AP2 sends a signal while STA1 is performing a reception operation on the signal of AP1, a conflict between the signal of AP1 and the signal of AP2 may occur in STA1. Accordingly, STA1 may not be able to receive the signal (e.g., data, frame) of AP1. In other words, the reception of the signal of AP1 at STA1 may fail. An error may occur in the signal received from AP1 at STA1.

[0074] If STA1 transmits a signal while AP2 performs a reception operation for STA2's signal, a conflict between STA1's signal and STA2's signal may occur at AP2. Accordingly, AP2 will not receive STA2's signal (e.g., data, frame). In other words, reception of STA2's signal at AP2 may fail. An error may occur in STA2's signal received at AP2. If STA2 and AP1 are located in a transmission area where signals can be transmitted and received, the above-mentioned conflict problem (e.g., reception failure and / or reception error of the signal) may occur. The AP (e.g., AP1 and / or AP2) may be an AP MLD, and the STA (e.g., STA1 and / or STA2) may be a STA MLD.

[0075] When in with Figure 4 The following issues may occur when performing R-TWT operations in an environment similar to and / or the same dense environment as shown.

[0076] Figure 5 is a timing diagram illustrating a first exemplary embodiment of the R-TWT operation problem in a dense environment.

[0077] like Figure 5 As shown, AP MLD1, AP MLD2, AP1, AP2, STAMLD1, STA MLD2, STA1 and STA2 can be Figure 4 The exemplary embodiments are arranged the same or similarly. STA1 associated with STAMLD1 can connect and / or access AP1 associated with AP MLD1, and STA2 associated with STA MLD2 can connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1 or AP2 may not be associated with MLD. Alternatively, all STA1, STA2, AP1 and AP2 may not be associated with MLD. AP1 can configure R-TWT SP1, and AP2 can configure R-TWT SP2. STA1 can be a member of R-TWT SP1, and STA2 can be a member of R-TWT SP2. In the time domain, R-TWT SP1 and R-TWT SP2 can overlap (for example, partially overlap or completely overlap). Communication can be performed simultaneously in some or all of two or more R-TWT SPs.

[0078] R-TWT SP1 can be indicated by a TWT information element (e.g., R-TWT configuration information) included in a beacon frame sent by AP1. R-TWT SP2 can be indicated by a TWT information element (e.g., R-TWT configuration information) included in a beacon frame sent by AP2. If AP1 and AP2 are hidden nodes relative to each other, AP1 may not be able to know the R-TWT configuration information of AP2, and AP2 may not be able to know the R-TWT configuration information of AP1. If the R-TWT SP1 of AP1 overlaps with the R-TWT SP2 of AP2, the transmissions of AP1 and AP2 within the overlapping R-TWT SP may conflict. In other words, a transmission conflict of frames may occur within the overlapping R-TWT SPs.

[0079] For example, when AP1 sends a frame (e.g., a physical layer protocol data unit (PPDU), a physical layer data unit, a medium access control (MAC) layer protocol data unit (MPDU), a MAC layer data unit, etc.) to STA1, AP2 may determine that the channel is idle and send a frame to STA2 on the channel. Due to the conflict between the frame transmission of AP1 and the frame transmission of AP2, STA1 may not be able to decode the frame of AP1, and STA2 may not be able to decode the frame of AP2. Accordingly, STA1 may not be able to send a reception response frame to the frame of AP1, and STA2 may not be able to send a reception response frame to the frame of AP2. In the present invention, the reception response frame may be an acknowledgment (ACK) frame or a block ACK (BA) frame.

[0080] If a receive response frame is not received from STA1, AP1 may determine that a transmission conflict has occurred and may double an enhanced distributed channel access (EDCA) parameter. In this case, the delay of AP1's channel access may increase. The EDCA parameters may be a contention window (CW) [access category (AC)] and / or a quick short retry count (QSRC) [AC]. If a receive response frame is not received from STA2, AP2 may determine that a transmission conflict has occurred and may double an EDCA parameter. In this case, the delay of AP2's channel access may increase.

[0081] If the reception of the frame fails or if an error occurs in the received frame, each of STA1 and STA2 can perform a channel access operation after waiting for the extended inter frame space (EIFS). EIFS can be (distributed coordination function (DCF) interframe space (DCF interframe space, DIFS) + short interframe space (Short interframe space, SIFS) + AckTxTime). AckTxTime can be the maximum transmission time of an ACK frame or a BA frame. Accordingly, the delay of channel access for each of STA1 and STA2 may increase. The communication delay may increase within the R-TWT SP, which is a period for low-delay communication.

[0082] In the following, a method for solving the above-mentioned problem will be described. In order to solve the problem of increased communication delay within the R-TWT SP, the STA may report the overlap prediction information of the R-TWT SP and / or the past overlap information of the R-TWT SP to the AP. The overlap prediction information may indicate that the R-TWT SP is predicted to be overlapped. The past overlap information may be information of the previously overlapped R-TWT SP.

[0083] Figure 6 is a timing diagram illustrating a first exemplary embodiment of an R-TWT SP reporting method in a dense environment.

[0084] like Figure 6 As shown, AP MLD1, AP MLD2, AP1, AP2, STAMLD1, STA MLD2, STA1 and STA2 can be Figure 4The exemplary embodiments of the present invention are arranged the same or similarly. AP MLD1, AP MLD2, AP1, AP2, STA MLD1, STA MLD2, STA1 and STA2 may belong to an OBSS. STA1 associated with STA MLD1 may connect and / or access AP1 associated with AP MLD1, and STA2 associated with STA MLD2 may connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1 or AP2 may not be associated with MLD. Alternatively, all STA1, STA2, AP1 and AP2 may not be associated with MLD. AP1 may configure R-TWT SP1, and AP2 may configure R-TWT SP2. STA1 may be a member of R-TWT SP1, and STA2 may be a member of R-TWT SP2. In the time domain, R-TWT SP1 and R-TWT SP2 may overlap (e.g., partially overlap or completely overlap). Communication may be performed simultaneously in some or all of two or more R-TWT SPs.

[0085] R-TWT SP1 can be indicated by a TWT information element (e.g., R-TWT configuration information) included in a beacon frame sent by AP1. R-TWT SP2 can be indicated by a TWT information element (e.g., R-TWT configuration information) included in a beacon frame sent by AP2. R-TWT SP1 and / or R-TWT SP2 can be configured by another frame instead of the beacon frame. STA1 can receive the beacon frame of AP2. STA1 can be configured to identify the beacon frame of the AP belonging to the OBSS in the R-TWT configuration process (e.g., R-TWT establishment process, R-TWT negotiation process) between STA1 and AP1. As another method, when STA1 performs R-TWT operation (e.g., when STA1 participates in R-TWT SP), STA1 can identify the beacon frame of the AP belonging to the OBSS without separate configuration or indication.

[0086] STA1 may receive a beacon frame of AP2, and may identify R-TWT SP2 based on information elements included in the beacon frame. STA1 may identify that R-TWT SP1 and R-TWT SP2 overlap. In this case, STA1 may send a measurement report frame (e.g., measurement report information) to AP1. The measurement report frame may indicate that the R-TWT SP overlaps. The measurement report frame may include information about AP2 (e.g., address, target beacon transmission time (TBTT)) and / or R-TWT configuration information included in the beacon frame of AP2 (e.g., TWT information element, quiet information element). The information included in the measurement report frame may be overlapping prediction information. The measurement report frame may be sent before R-TWT SP1 and / or R-TWT SP2. Alternatively, the measurement report frame may be sent within R-TWT SP1 and / or R-TWT SP2.

[0087] Before sending the measurement report frame, STA1 may send past overlap information to AP1. The past overlap information may include information about the frequency and / or number of times that overlapping R-TWT SPs have previously occurred. AP1 may receive past overlap information from STA1, and may allocate R-TWT SPs to STA1 (e.g., additional R-TWT SPs) based on the past overlap information. The above operation may be referred to as an "additional SP allocation operation". The additional SP allocation operation may be performed to ensure low-latency data transmission (e.g., low-latency communication) for STA1. STA2 may operate the same or similarly to the above-mentioned operation of STA1. AP2 may operate the same or similarly to the above-mentioned operation of AP1.

[0088] AP1 and AP2 may be associated with an AP MLD supporting two or more links. Alternatively, AP1 may be associated with APMLD1, and AP2 may be associated with AP MLD2. The operation of AP1 may be interpreted as the operation of AP MLD1, and the operation of AP2 may be interpreted as the operation of AP MLD2. STA1 and STA2 may be associated with a STA MLD supporting two or more links. Alternatively, STA1 may be associated with STA MLD1, and STA2 may be associated with STA MLD2. The operation of STA1 may be interpreted as the operation of STA MLD1, and the operation of STA2 may be interpreted as the operation of STA MLD2.

[0089] STA MLD1 may send a measurement report frame to AP MLD1 using multiple links. Alternatively, STA MLD1 may send a measurement report frame to AP MLD1 on a link other than the link on which the beacon frame was received. AP MLD1 may perform additional SP allocation operations on one or more links supported by STA MLD1. STA MLD2 may operate the same or similarly to the operation of STA MLD1 described above. AP MLD2 may operate the same or similarly to the operation of AP MLD1 described above.

[0090] Figure 7 is a timing diagram illustrating a third exemplary embodiment of an R-TWT SP reporting method in a dense environment.

[0091] like Figure 7 As shown, AP MLD1, AP MLD2, AP1, AP2, STA MLD1, STA MLD2, STA1 and STA2 can be Figure 4 The exemplary embodiments of the present invention are arranged the same or similarly. AP MLD1, AP MLD2, AP1, AP2, STA MLD1, STAMLD2, STA1 and STA2 may belong to an OBSS. STA1 associated with STA MLD1 may connect and / or access AP1 associated with AP MLD1, and STA2 connected and / or accessed with STA MLD2 may connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1 or AP2 may not be associated with MLD. Alternatively, all STA1, STA2, AP1 and AP2 may not be associated with MLD. AP1 may configure R-TWT SP1, and AP2 may configure R-TWT SP2. STA1 may be a member of R-TWT SP1, and STA2 may be a member of R-TWT SP2. In the time domain, R-TWT SP1 and R-TWT SP2 may overlap (e.g., partially overlap or completely overlap). Communication may be performed simultaneously in some or all of two or more R-TWT SPs.

[0092] R-TWT SP1 may be indicated by a TWT information element (e.g., R-TWT configuration information) included in a beacon frame sent by AP1. R-TWT SP2 may be indicated by a TWT information element (e.g., R-TWT configuration information) included in a beacon frame sent by AP2. R-TWT SP1 and / or R-TWT SP2 may be configured by another frame instead of the beacon frame. STA1 may not receive the beacon frame of AP2. In other words, STA1 may only recognize the beacon frame of AP1. After R-TWT SP1 and R-TWT SP2 overlap, STA1 may recognize that R-TWT SP1 and R-TWT SP2 overlap. STA1 may determine that R-TWT SP1 and R-TWT SP2 overlap based on at least one of the following: the collision frequency of frames, the address field included in the MAC header of the frame received from the communication node (e.g., AP2 and / or STA2), or the BSS color information included in the PHY header of the frame received from the communication node (e.g., AP2 and / or STA2). In this case, STA1 may send a measurement report frame to AP1. The measurement report frame may indicate that R-TWT SPs (e.g., R-TWT SP1 and R-TWT SP2) overlap. The measurement report frame may be sent after R-TWT SP1 and / or R-TWT SP2. Alternatively, the measurement report frame may be sent within R-TWT SP1 and / or R-TWT SP2.

[0093] STA1 may be configured to report information about overlapping R-TWT SPs in an R-TWT configuration process (e.g., R-TWT establishment process, R-TWT negotiation process) between STA1 and AP1. As another method, when STA1 performs an R-TWT operation (e.g., when STA1 participates in an R-TWT SP), STA1 may report information about overlapping R-TWT SPs without separate configuration or indication. Before sending a measurement report frame, STA1 may receive a beacon frame of AP2 and identify information about AP2 included in the beacon frame. As another method, before sending a measurement report frame, STA1 may send a probe request frame to AP2, receive a probe response frame from AP2 in response to the probe request frame, and identify information about AP2 included in the probe response frame. STA1 may generate a measurement report frame including information about the identification of AP2. The measurement report frame may include information about AP2 (e.g., address, TBTT) and / or R-TWT configuration information (e.g., TWT information element, quiet information element) included in the beacon frame and / or the probe response frame of AP2.

[0094] Before sending the measurement report frame, STA1 may send past overlap information to AP1. The past overlap information may include information about the frequency and / or number of times that overlapping R-TWT SPs have previously occurred. AP1 may receive past overlap information from STA1, and may allocate R-TWT SPs to STA1 (e.g., additional R-TWT SPs) based on the past overlap information. The above operation may be referred to as an "additional SP allocation operation". The additional SP allocation operation may be performed to ensure low-latency data transmission (e.g., low-latency communication) for STA1. STA2 may operate the same or similarly to the above-mentioned operation of STA1. AP2 may operate the same or similarly to the above-mentioned operation of AP1.

[0095] AP1 and AP2 may be associated with an AP MLD supporting two or more links. Alternatively, AP1 may be associated with APMLD1, and AP2 may be associated with AP MLD2. The operation of AP1 may be interpreted as the operation of AP MLD1, and the operation of AP2 may be interpreted as the operation of AP MLD2. STA1 and STA2 may be associated with a STA MLD supporting two or more links. Alternatively, STA1 may be associated with STA MLD1, and STA2 may be associated with STA MLD2. The operation of STA1 may be interpreted as the operation of STA MLD1, and the operation of STA2 may be interpreted as the operation of STA MLD2.

[0096] STA MLD1 may send a measurement report frame to AP MLD1 using multiple links. Alternatively, STA MLD1 may send a measurement report frame to AP MLD1 on a link other than the link on which the beacon frame was received. AP MLD1 may perform additional SP allocation operations on one or more links supported by STA MLD1. STA MLD2 may operate the same or similarly to the operation of STA MLD1 described above. AP MLD2 may operate the same or similarly to the operation of AP MLD1 described above.

[0097] Figure 8 is a timing diagram illustrating a third exemplary embodiment of an R-TWT SP reporting method in a dense environment.

[0098] like Figure 8 As shown, AP MLD1, AP MLD2, AP1, AP2, STA MLD1, STA MLD2, STA1 and STA2 can be Figure 4The exemplary embodiments of the present invention are arranged the same or similarly. AP MLD1, AP MLD2, AP1, AP2, STA MLD1, STAMLD2, STA1 and STA2 may belong to OBSS. STA1 associated with STAMLD1 may connect and / or access AP1 associated with AP MLD1, and STA2 associated with STA MLD2 may connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1 or AP2 may not be associated with MLD. Alternatively, all STA1, STA2, AP1 and AP2 may not be associated with MLD. AP1 may configure R-TWT SP1, and AP2 may configure R-TWT SP2. STA1 may be a member of R-TWT SP1, and STA2 may be a member of R-TWT SP2. In the time domain, R-TWT SP1 and R-TWT SP2 may overlap (e.g., partially overlap or completely overlap). Communication may be performed simultaneously in some or all of two or more R-TWT SPs.

[0099] R-TWT SP1 may be indicated by a TWT information element (e.g., R-TWT configuration information) included in a beacon frame sent by AP1. R-TWT SP2 may be indicated by a TWT information element (e.g., R-TWT configuration information) included in a beacon frame sent by AP2. R-TWT SP1 and / or R-TWT SP2 may be configured by another frame instead of the beacon frame. AP1 and AP2 may be hidden nodes relative to each other. In this case, AP1 may not recognize the beacon frame of AP2, and AP2 may not recognize the beacon frame of AP1. Alternatively, even when AP1 and AP2 are not hidden nodes relative to each other, AP1 will not recognize the beacon frame of AP2, and AP2 will not recognize the beacon frame of AP1.

[0100] After the R-TWT SP (e.g., R-TWT SP1 and R-TWT SP2) overlap, AP1 may recognize that the R-TWT SP overlaps. AP1 may determine that R-TWT SP1 and R-TWT SP2 overlap based on at least one of the following: the collision frequency of the frame, the address field included in the MAC header of the frame received from the communication node (e.g., AP2 and / or STA2), or the BSS color information included in the PHY header of the frame received from the communication node (e.g., AP2 and / or STA2). AP1 may send a measurement request frame to the STA requesting the sending of a measurement report frame. AP1 may send a measurement request frame to a specific STA (e.g., STA1). Alternatively, AP1 may send a measurement request frame based on a unicast scheme, a broadcast scheme, or a multicast scheme. In this case, the address field of the measurement request frame may be set to a unicast address, a broadcast address, or a multicast address. The measurement request frame may be sent after R-TWT SP1 and / or R-TWT SP2 are terminated. Alternatively, the measurement request frame may be transmitted within R-TWT SP1 and / or R-TWT SP2.

[0101] STA1 may receive a measurement request frame from AP1, and may send a measurement report frame in response to the measurement request frame. The measurement request frame may indicate the occurrence of an overlapping R-TWT SP. If STA1 does not recognize the occurrence of an overlapping R-TWT SP, STA1 may send a measurement report frame after receiving the measurement request frame of AP1. Alternatively, even if STA1 recognizes the occurrence of an overlapping R-TWT SP, STA1 may send a measurement report frame after receiving the measurement request frame of AP1.

[0102] STA1 can determine that an overlapping R-TWTSP has occurred based on the information elements included in the measurement request frame. The measurement request frame can request the transmission of a measurement report frame including OBSS information and / or information elements (e.g., TBTT, TWT information element, quiet information element) included in a beacon frame and / or a probe response frame sent by an AP belonging to the OBSS. In addition, the measurement request frame may include information indicating the transmission of a probe request frame to an AP belonging to the OBSS and / or information indicating the reception of a beacon frame of an AP belonging to the OBSS.

[0103] Before sending the measurement report frame, STA1 may perform a reception operation of a beacon frame of AP2 or a transmission / reception operation of a probe request / response frame with AP2 according to an instruction of AP1 included in the measurement request frame. STA1 may receive a beacon frame or a probe response frame of AP2, and may obtain information about AP2 included in the beacon frame or the probe response frame. STA1 may generate a measurement report frame including information about AP2. In other words, the measurement report frame may include information indicated (e.g., requested) by AP1.

[0104] The measurement report frame may include information about AP2 (e.g., address, TBTT) and / or R-TWT configuration information (e.g., TWT information element, quiet information element) included in the beacon frame or probe response frame of AP2. The information included in the measurement report frame may be overlap prediction information. Before sending the measurement report frame, STA1 may send past overlap information to AP1. Past overlap information may include information about the frequency and / or number of times overlapping R-TWT SPs have previously occurred. AP1 may receive past overlap information from STA1, and may allocate R-TWT SPs to STA1 based on the past overlap information (e.g., additional R-TWT SPs). The above operation may be referred to as an "additional SP allocation operation". An additional SP allocation operation may be performed to ensure low-latency data transmission (e.g., low-latency communication) for STA1. STA2 may operate in the same or similar manner as the above-mentioned operation of STA1. AP2 may operate in the same or similar manner as the above-mentioned operation of AP1.

[0105] AP1 and AP2 may be associated with an AP MLD supporting two or more links. Alternatively, AP1 may be associated with APMLD1, and AP2 may be associated with AP MLD2. The operation of AP1 may be interpreted as the operation of AP MLD1, and the operation of AP2 may be interpreted as the operation of AP MLD2. STA1 and STA2 may be associated with a STA MLD supporting two or more links. Alternatively, STA1 may be associated with STA MLD1, and STA2 may be associated with STA MLD2. The operation of STA1 may be interpreted as the operation of STA MLD1, and the operation of STA2 may be interpreted as the operation of STA MLD2.

[0106] AP MLD1 may send a measurement request frame to STAMLD1 using multilink. Alternatively, AP MLD 1 may send a measurement request frame to STA MLD1 on a link other than the link on which overlapping R-TWT SP has occurred. STA MLD1 may send a measurement report frame to AP MLD1 using multilink. Alternatively, STA MLD1 may send a measurement report frame to AP MLD1 on a link other than the link on which the beacon frame was received. AP MLD1 may perform additional SP allocation operations on one or more links supported by STAMLD1. STAMLD2 may operate the same as or similar to the operation of the above-mentioned STAMLD1. AP MLD2 may operate the same as or similar to the operation of the above-mentioned AP MLD1.

[0107] Hereinafter, a method for changing the R-TWT SP based on the R-TWT configuration information included in the measurement report frame sent by the STA will be described. The method for changing the R-TWT SP may mean a method for reconfiguring the R-TWT SP. The change of the R-TWT SP may refer to a change in the start time of the R-TWT SP, a change in the end time of the R-TWT SP, a change in the length of the R-TWT SP, a change in the periodicity of the R-TWT SP, and / or a change in the link (e.g., channel) to which the R-TWT SP is applied.

[0108] Fig. 9 is a timing diagram illustrating a first exemplary embodiment of a method for changing an R-TWT SP in a dense environment.

[0109] like Fig. 9 As shown, AP MLD1, AP MLD2, AP1, AP2, STAMLD1, STAMLD2, STA1, and STA2 can be Figure 4 The exemplary embodiments of the present invention may be arranged the same or similarly. AP MLD1, AP MLD2, AP1, AP2, STAMLD1, STAMLD2, STA1, and STA2 may belong to an OBSS. STA1 associated with STAMLD1 may connect and / or access AP1 associated with AP MLD1, and STA2 associated with STA MLD2 may connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1, or AP2 may not be associated with an MLD. Alternatively, all STA1, STA2, AP1, and AP2 may not be associated with an MLD.

[0110] AP1 may send a beacon frame including configuration information of R-TWT SP1. In other words, the beacon frame of AP1 may indicate R-TWT SP1. AP2 may send a beacon frame including configuration information of R-TWT SP2. In other words, the beacon frame of AP2 may indicate R-TWT SP2. STA1 may be a member of R-TWT SP1, and STA2 may be a member of R-TWT SP2. STA1 may receive the beacon frame of AP1 and the beacon frame of AP2, and identify R-TWT SP1 and R-TWT SP2 based on the received beacon frames. STA1 may determine that R-TWT SP1 and R-TWT SP2 overlap, and may send a measurement report frame including information about AP2 and R-TWT configuration information of AP2 to AP1. STA2 may receive the beacon frame of AP1 and the beacon frame of AP2, and may identify R-TWT SP1 and R-TWT SP2 based on the received beacon frames. STA2 may determine that R-TWT SP1 and R-TWT SP2 overlap, and may send a measurement report frame including information about AP1 and R-TWT configuration information of AP1 to AP2. R-TWT SP1 and / or R-TWT SP2 may be configured by another frame instead of a beacon frame.

[0111] AP1 may receive a measurement report frame of STA1 and / or a measurement report frame of STA2, and may determine that R-TWT SP1 and R-TWT SP2 overlap based on the received measurement report frame. AP2 may receive a measurement report frame of STA1 and / or a measurement report frame of STA2, and may determine that R-TWT SP1 and R-TWT SP2 overlap based on the received measurement report frame. When receiving the measurement report frame of STA1 (for example, when determining that R-TWT SP1 and R-TWT SP2 overlap), AP1 may change R-TWT SP1. Alternatively, even if AP1 recognizes that R-TWT SP1 and R-TWT SP2 overlap, AP1 may change R-TWT SP1 despite not receiving the measurement report frame. R-TWT SP1 may be changed immediately after receiving the measurement report frame of STA1. In other words, R-TWT SP1 may be shifted in the time domain.

[0112] AP1 may send a management frame and / or an action frame to change the R-TWT SP1. For example, in order to change the R-TWT SP1, AP1 may send a beacon frame, a probe response frame, and / or a TWT frame (e.g., an R-TWT frame) indicating the change of the R-TWT SP1. The frame indicating the change of the R-TWT SP1 may include R-TWT reconfiguration information (e.g., a TWT information element). AP1 may change the R-TWT SP1 so that the R-TWT SP1 does not overlap with the R-TWT SP2. In other words, AP1 may identify the position and / or length of the R-TWT SP2 based on the information element included in the measurement report frame of STA1, and may reconfigure the R-TWT SP1 so that the R-TWT SP1 does not overlap with the R-TWT SP2.

[0113] AP2 can receive the measurement report frame sent by STA1 to AP1. In other words, AP2 can receive the measurement report frame (for example, the measurement report frame sent by STA1 to AP1) even if the destination of the measurement report frame is not AP2. If the measurement report frame of STA1 is received before the measurement report frame of STA2, AP2 can ignore the measurement report frame of STA2. AP2 can predict that AP1 will change R-TWT SP1, and can determine that the R-TWT SP1 changed by the change of R-TWT SP1 does not overlap with R-TWT SP2. Therefore, even if STA2 sends a measurement report frame to AP2, AP2 may not change R-TWT SP2.

[0114] If AP1 changes R-TWT SP1 based on the measurement report frame of STA1, the changed R-TWT SP1 and R-TWT SP2 may not overlap in the time domain. Accordingly, low-latency communication may be smoothly performed within the R-TWT SP. The changed R-TWT SP1 may mean a reconfigured R-TWT SP1.

[0115] Fig.10 is a timing diagram illustrating a second exemplary embodiment of a method for changing an R-TWT SP in a dense environment.

[0116] like Fig.10 As shown, AP MLD1, AP MLD2, AP1, AP2, STAMLD1, STAMLD2, STA1, and STA2 can be Figure 4The exemplary embodiments of the present invention are arranged the same or similarly. AP MLD1, AP MLD2, AP1, AP2, STAMLD1, STA MLD2, STA1, and STA2 may belong to an OBSS. STA1 associated with STAMLD1 may connect and / or access AP1 associated with AP MLD1, and STA2 associated with STA MLD2 may connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1, or AP2 may not be associated with an MLD. Alternatively, all STA1, STA2, AP1, and AP2 may not be associated with an MLD.

[0117] AP1 may send a beacon frame including configuration information of R-TWT SP1. In other words, the beacon frame of AP1 may indicate R-TWT SP1. AP2 may send a beacon frame including configuration information of R-TWT SP2. In other words, the beacon frame of AP2 may indicate R-TWT SP2. STA1 may receive the beacon frame of AP1 and the beacon frame of AP2, and may identify R-TWT SP1 and R-TWT SP2 based on the received beacon frames. STA1 may be a member of R-TWT SP1, and STA2 may be a member of R-TWT SP2. STA1 may determine that R-TWT SP1 and R-TWT SP2 overlap, and may send a measurement report frame including information about AP2 and R-TWT configuration information of AP2 to AP1. STA2 may receive the beacon frame of AP1 and the beacon frame of AP2, and may identify R-TWT SP1 and R-TWT SP2 based on the received beacon frames. STA2 may determine that R-TWT SP1 and R-TWT SP2 overlap, and may send a measurement report frame including information about AP1 and R-TWT configuration information of AP1 to AP2. R-TWT SP1 and / or R-TWT SP2 may be configured by another frame instead of a beacon frame.

[0118] AP1 may receive a measurement report frame of STA1, and may determine that R-TWT SP1 and R-TWT SP2 overlap based on the received measurement report frame. AP2 may receive a measurement report frame of STA2, and may determine that R-TWT SP1 and R-TWT SP2 overlap based on the received measurement report frame. When receiving the measurement report frame of STA1 (for example, when determining that R-TWT SP1 and R-TWT SP2 overlap), AP1 may change R-TWT SP1. R-TWT SP1 may be changed immediately after receiving the measurement report frame of STA1. In other words, R-TWT SP1 may be shifted in the time domain. Alternatively, even if AP1 recognizes that R-TWT SP1 and R-TWT SP2 overlap, AP1 may change R-TWT SP1 despite not receiving the measurement report frame. When receiving the measurement report frame of STA2 (for example, when determining that R-TWT SP1 and R-TWT SP2 overlap), AP2 may change R-TWT SP2. R-TWT SP2 may be changed immediately after receiving the measurement report frame of STA2. In other words, R-TWT SP2 may be shifted in the time domain. Alternatively, even if AP2 recognizes that R-TWT SP1 and R-TWT SP2 overlap, AP2 may change R-TWT SP2 despite not receiving the measurement report frame.

[0119] AP1 may not be aware that the process of changing R-TWT SP2 is performed by AP2. AP2 may not be aware that the process of changing R-TWT SP1 is performed by AP1. The R-TWT SP may be changed by a random scheme. For example, the offset and / or periodicity of the R-TWT SP may be randomly changed. Accordingly, the changed R-TWT SP1 of AP1 may not overlap with the changed R-TWT SP2 of AP2.

[0120] AP1 may send a management frame and / or an action frame to change R-TWT SP1. For example, in order to change R-TWT SP1, AP1 may send a beacon frame, a probe response frame, and / or a TWT frame (e.g., an R-TWT frame) indicating the change of R-TWT SP1. The frame indicating the change of R-TWT SP1 may include R-TWT reconfiguration information. AP2 may send a management frame and / or an action frame to change R-TWT SP2. For example, in order to change R-TWT SP2, AP2 may send a beacon frame, a probe response frame, and / or a TWT frame (e.g., an R-TWT frame) indicating the change of R-TWT SP2. The frame indicating the change of R-TWT SP2 may include R-TWT reconfiguration information. If AP1 changes R-TWT SP1 and AP2 changes R-TWT SP2, the changed R-TWT SP1 and the changed R-TWT SP2 may not overlap in the time domain. Accordingly, low-latency communication may be smoothly performed within the R-TWT SP.

[0121] Fig.11 is a timing diagram illustrating a third exemplary embodiment of a method for changing an R-TWT SP in a dense environment.

[0122] like Fig.11 As shown, AP MLD1, AP MLD2, AP1, AP2, STA MLD1, STA MLD2, STA1 and STA2 can be Figure 4 The exemplary embodiments of the present invention may be arranged the same or similarly. AP MLD1, AP MLD2, AP1, AP2, STA MLD1, STA MLD2, STA1, and STA2 may belong to an OBSS. STA1 associated with STA MLD1 may connect and / or access AP1 associated with AP MLD1, and STA2 associated with STA MLD2 may connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1, or AP2 may not be associated with an MLD. Alternatively, all STA1, STA2, AP1, and AP2 may not be associated with an MLD.

[0123] AP1 may send a beacon frame including configuration information of R-TWT SP1. In other words, the beacon frame of AP1 may indicate R-TWT SP1. AP2 may send a beacon frame including configuration information of R-TWT SP2. In other words, the beacon frame of AP2 may indicate R-TWT SP2. STA1 may receive the beacon frame of AP1 and / or the beacon frame of AP2, and may identify R-TWT SP1 and R-TWT SP2 based on the received beacon frame. STA1 may be a member of R-TWT SP1, and STA2 may be a member of R-TWT SP2. STA1 may determine that R-TWT SP1 and R-TWT SP2 overlap, and may send a measurement report frame including information about AP2 and R-TWT configuration information of AP2 to AP1. STA2 may receive the beacon frame of AP1 and / or the beacon frame of AP2, and may identify R-TWT SP1 and R-TWT SP2 based on the received beacon frame. STA2 may determine that R-TWT SP1 and R-TWT SP2 overlap, and may send a measurement report frame including information about AP1 and R-TWT configuration information of AP1 to AP2. R-TWT SP1 and / or R-TWT SP2 may be configured by another frame instead of a beacon frame.

[0124] When receiving the measurement report frame of STA1, AP1 can determine that R-TWT SP1 and R-TWT SP2 overlap. Alternatively, AP1 can determine that R-TWT SP1 and R-TWT SP2 overlap without receiving the measurement report frame. In this case, AP1 can select an integer in the range [0, M] in a uniform random manner. For example, AP1 can select 1. The selected integer can be an SP change counter. M can be a natural number. When receiving the measurement report frame of STA2, AP2 can determine that R-TWT SP1 and R-TWT SP2 overlap. In this case, AP2 can select an integer in the range [0, N] in a uniform random manner. For example, AP2 can select 3. N can be a natural number. M and N can be the same. Alternatively, M and N can be different.

[0125] If the R-TWT SP overlap is determined based on the measurement report frame received from the STA, or if the R-TWT SP overlap is determined by another method (e.g., a method that does not use the measurement report frame), the SP change counter may be decremented by 1. For example, if R-TWT SP1 is predicted to overlap with another R-TWT SP in the future, or if it is determined that R-TWT SP1 has overlapped with another R-TWT SP in the past, AP1 may decrement the SP change counter by 1. If R-TWT SP2 is predicted to overlap with another R-TWT SP in the future, or if it is determined that R-TWT SP2 has overlapped with another R-TWT SP in the past, AP2 may decrement the SP change counter by 1. If the corresponding SP change counter becomes 0, each of AP1 and AP2 may change the R-TWT SP.

[0126] The initial SP change counter of AP1 may be 1, and the initial SP change counter of AP2 may be 3. After AP1 selects the SP change counter to be 1, if the measurement report frame of STA1 is received, AP1 may change the SP change counter from 1 to 0. In other words, if the overlap of R-TWT SP1 is identified based on the measurement report frame of STA1, AP1 may change the SP change counter from 1 to 0. If the SP change counter becomes 0, AP1 may change R-TWT SP1. AP1 may change R-TWT SP1 so that R-TWT SP1 does not overlap with R-TWT SP2.

[0127] AP1 may send a management frame and / or an action frame to change R-TWT SP1. For example, in order to change R-TWT SP1, AP1 may send a beacon frame, a probe response frame, and / or a TWT frame (e.g., an R-TWT frame) indicating the change of R-TWT SP1. The frame indicating the change of R-TWT SP1 may include R-TWT reconfiguration information (e.g., a TWT information element).

[0128] After AP2 selects the SP change counter to be 3, if the measurement report frame of STA2 is received, AP2 may change the SP change counter from 3 to 2. In other words, if the overlap of R-TWT SP2 is identified based on the measurement report frame of STA2, AP2 may change the SP change counter from 3 to 2. Since AP1 changes R-TWT SP1, AP2 may know that R-TWT SP2 does not overlap with the changed R-TWT SP1. Alternatively, STA 2 may send a measurement report frame to AP 2, the measurement report frame including information indicating that R-TWT SP2 does not overlap with another R-TWT SP (e.g., the changed R-TWT SP1). AP 2 may receive the measurement report frame from STA 2, and may identify that R-TWT SP2 does not overlap with another R-TWT SP (e.g., the changed R-TWT SP1) based on the information elements included in the measurement report frame. Alternatively, if R-TWT SP2 does not overlap with another R-TWT SP (e.g., R-TWT SP1 after the change), STA2 may not send a measurement report frame to AP2. If the measurement report frame of STA2 is not received within a preset time, or if R-TWT SP2 does not overlap with another R-TWT SP (e.g., R-TWT SP1 after the change), AP2 may discard the SP change counter and may not perform the process for changing R-TWT SP2.

[0129] Fig.12 is a timing diagram illustrating a first exemplary embodiment of a method for changing R-TWT SP and links in a dense environment.

[0130] like Fig.12 As shown, AP MLD1, AP MLD2, AP1, AP2, STAMLD1, STA MLD2, STA1 and STA2 can be Figure 4 The exemplary embodiments of the present invention may be arranged the same or similarly. AP MLD1, AP MLD2, AP1, AP2, STA MLD1, STA MLD2, STA1, and STA2 may belong to an OBSS. STA1 associated with STA MLD1 may connect and / or access AP1 associated with AP MLD1, and STA2 associated with STA MLD2 may connect and / or access AP2 associated with AP MLD2. Alternatively, at least one of STA1, STA2, AP1, or AP2 may not be associated with an MLD. Alternatively, all STA1, STA2, AP1, and AP2 may not be associated with an MLD.

[0131] Communication nodes (e.g., AP2 and / or STA2) belonging to the OBSS may cause interference to STA1. In this case, communication (e.g., low-latency communication) of STA1 may not be performed smoothly in R-TWT SP1. Due to interference from communication nodes belonging to the OBSS, STA1 may not be able to perform communication (e.g., frame transmission and reception operations) smoothly. From the perspective of AP1 and / or STA1, OBSS interference may be interference caused by communication of AP2 and / or STA2. OBSS interference may occur when the R-TWT SP1 of AP1 overlaps with the R-TWT SP of a communication node belonging to the OBSS. When interference occurs within the R-TWT SP1, STA1 may send a measurement report frame to AP1. STA1 may send a measurement report frame to AP1 without a separate request. For example, if OBSS interference is detected, STA1 may send a measurement report frame to AP1 without a separate request or a separate indication.

[0132] The measurement report frame of STA1 may include a reason code. The reason code may indicate OBSS interference and / or overlapping of R-TWT SP. AP1 may receive the measurement report frame from STA1, and may identify the occurrence of OBSS interference and / or overlapping R-TWT SP based on the reason code included in the measurement report frame. In this case, AP1 may perform a link change operation and / or an R-TWT SP change operation. The link change operation may be an operation of changing the operating frequency of the link. The R-TWT SP change operation may be an operation of changing the R-TWT SP1 so that the R-TWT SP of the communication node belonging to the OBSS does not overlap with the R-TWT SP1 of AP1. AP1 may change the R-TWT SP1 so that OBSS interference does not occur. OBSS interference may not occur in the changed R-TWT SP1. The R-TWT SP change operation may be related to Figures 9 to 11 The exemplary embodiments are the same or similar to at least one of the exemplary embodiments.

[0133] The link change operation and / or the R-TWT SP change operation may be indicated by at least one of a management frame or an action frame. For example, the link change operation and / or the R-TWT SP change operation may be performed based on at least one of a beacon frame, a probe response frame, or a TWT frame. AP1 may not perform the link change operation and / or the R-TWT SP change operation. Alternatively, AP1 may perform one of the link change operation or the R-TWT SP change operation.

[0134] As another method, before performing a link change operation and / or an R-TWT SP change operation, AP1 may send an additional measurement request frame to one or more STAs associated with AP1. The additional measurement request frame of AP1 may indicate an OBSS measurement. The additional measurement request frame may include measurement target information. The measurement target information may indicate at least one of a channel load, an OBSS beacon frame, an OBSS R-TWT configuration information, or an OBSS interference. An OBSS beacon frame may refer to a beacon frame sent by a communication node belonging to the OBSS. The OBSS R-TWT configuration information may be R-TWT configuration information (e.g., TWT configuration information) sent by a communication node belonging to the OBSS. OBSS interference may be interference caused by a communication node belonging to the OBSS.

[0135] STA may receive an additional measurement request frame from AP1, and perform a measurement operation based on the measurement target information included in the additional measurement request frame. For example, STA may perform a measurement operation on OBSS. STA may send a measurement report frame including a measurement result to AP1. AP1 may receive a measurement report frame from the STA, and perform a link change operation and / or an R-TWT SP change operation based on the measurement result included in the measurement report frame. Alternatively, AP1 may not perform a link change operation and / or an R-TWT SP change operation. AP1 may perform one of a link change operation or an R-TWT SP change operation.

[0136] Fig.13 is a timing diagram illustrating a second exemplary embodiment of a method for changing R-TWT SP and links in a dense environment.

[0137] like Fig.13 As shown, AP1 and AP2 may be associated with AP MLD1, and AP1 may operate on a first link and AP2 may operate on a second link. STA1 and STA2 may be associated with STA MLD1, and STA1 may operate on a first link and STA2 may operate on a second link. AP MLD1 (e.g., AP1 and AP2) and STA MLD1 (e.g., STA1 and STA2) may belong to an OBSS. STA MLD1 may be affected by OBSS interference on at least one of the first link or the second link. STA1 may be affected by OBSS interference and may not smoothly perform communication (e.g., low-latency communication) of STA1 in R-TWT SP1. Due to OBSS interference, STA1 may not smoothly perform communication (e.g., frame transmission and reception).

[0138] In this case, STA MLD1 may send a measurement report frame to AP MLD1 using at least one of the first link or the second link. When OBSS interference is detected, the measurement report frame may be sent. STA MLD1 may send a measurement report frame to AP MLD1 without a separate request. The measurement report frame may be sent using one or more of the multiple links. When OBSS interference is detected, STA MLD1 may send a measurement report frame to AP MLD1 without a separate request or a separate indication.

[0139] The measurement report frame of STA MLD1 may include a cause code. The cause code may indicate OBSS interference and / or overlapping of R-TWT SP. The measurement report frame may indicate the occurrence of OBSS interference and / or overlapping R-TWT SP on the first link. In addition, the measurement report frame may include information indicating a link (e.g., a first link) on which OBSS interference and / or overlapping R-TWT SP has occurred. The information indicating the link may be a link indicator (e.g., a link bitmap). The measurement report frame may be sent on a link indicated by the measurement report frame (e.g., a first link) or a link not indicated by the measurement report frame (e.g., a second link).

[0140] AP MLD1 may receive a measurement report frame from STA MLD1, and may identify the occurrence of OBSS interference and / or overlapping R-TWT SP based on a cause code included in the measurement report frame. In addition, AP MLD1 may identify a link (e.g., a first link) on which OBSS interference and / or overlapping R-TWT SP has occurred based on information (e.g., a link indicator) included in the measurement report frame. In this case, AP MLD1 may perform a link change operation and / or an R-TWT SP change operation on the link (e.g., the first link) indicated by the measurement report frame. The link change operation may be an operation of changing the operating frequency of the link. The R-TWT SP change operation may be an operation of changing the R-TWT SP1 so that the R-TWT SP of a communication node belonging to the OBSS does not overlap with the R-TWT SP1 of AP1. The R-TWT SP change operation may be an operation of changing the R-TWT SP1 so that the R-TWT SP of a communication node belonging to the OBSS does not overlap with the R-TWT SP1 of AP1. The R-TWT SP change operation may be an operation of changing the R-TWT SP1 so that the R-TWT SP of a communication node belonging to the OBSS does not overlap with the R-TWT SP1 of AP1. Figures 9 to 11 The exemplary embodiments are the same or similar to at least one of the exemplary embodiments.

[0141] The link change operation and / or the R-TWT SP change operation may be indicated by at least one of a management frame or an action frame. For example, the link change operation and / or the R-TWT SP change operation may be performed based on at least one of a beacon frame, a probe response frame, or a TWT frame. A frame indicating a link change operation may be sent on a link other than a link on which a link change operation is performed. AP MLD1 may not perform a link change operation and / or an R-TWT SP change operation. Alternatively, AP MLD1 may perform one of a link change operation or an R-TWT SP change operation.

[0142] As another method, before performing the link change operation and / or the R-TWT SP change operation, AP MLD1 may send an additional measurement request frame to one or more STAs associated with AP MLD1. The additional measurement request frame of AP MLD1 may indicate OBSS measurement. The additional measurement request frame may include measurement target information. The additional measurement request frame of AP MLD1 may be sent on the link indicated by the measurement report frame of STA MLD1. The additional measurement request frame of AP MLD1 may include a link indicator. The link indicator may indicate the link on which the measurement operation is performed.

[0143] The measurement target information may indicate at least one of a channel load, an OBSS beacon frame, an OBSS R-TWT configuration information, or an OBSS interference. An OBSS beacon frame may refer to a beacon frame sent by a communication node belonging to the OBSS. The OBSS R-TWT configuration information may be R-TWT configuration information (e.g., TWT configuration information) sent by a communication node belonging to the OBSS. OBSS interference may be interference caused by a communication node belonging to the OBSS.

[0144] The STA may receive an additional measurement request frame from the AP MLD1, and perform a measurement operation based on the measurement target information included in the additional measurement request frame. For example, the STA may perform a measurement operation on the OBSS. The STA may send a measurement report frame including a measurement result to the AP MLD1. The AP MLD1 may receive a measurement report frame from the STA, and perform a link change operation and / or an R-TWT SP change operation based on the measurement result included in the measurement report frame. Alternatively, the AP MLD1 may not perform a link change operation and / or an R-TWT SP change operation. The AP MLD1 may perform one of a link change operation or an R-TWT SP change operation.

[0145] The operation of the method according to the exemplary embodiment of the present invention can be implemented as a computer-readable program or code in a computer-readable recording medium. The computer-readable recording medium may include a recording device of all types having data that can be read by a computer system. In addition, the computer-readable recording medium can store and execute programs or codes, which can be distributed in a computer system connected via a network and read by a computer in a distributed manner.

[0146] Computer readable recording media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM or flash memory. Program instructions may include not only machine language codes created by a compiler, but also high-level language codes that can be executed by a computer using an interpreter.

[0147] Although some aspects of the present invention have been described in the context of a device, these aspects may indicate the corresponding description according to the method, and a block or device may correspond to the steps of the method or the features of the steps. Similarly, the aspects described in the context of the method may be represented as the features of the corresponding blocks or items or corresponding devices. Some or all steps of the method may be performed by (or using) hardware devices such as microprocessors, programmable computers or electronic circuits. In some embodiments, one or more of the most important steps of the method may be performed by such a device.

[0148] In some exemplary embodiments, a programmable logic device such as a field programmable gate array can be used to perform some or all of the functions of the method described herein. In some exemplary embodiments, the field programmable gate array can be operated with a microprocessor to perform one of the methods described herein. Typically, the method is preferably performed by a specific hardware device.

[0149] The description of the present invention is essentially only exemplary, and therefore variant forms that do not deviate from the essence of the present invention are intended to be within the scope of the present invention. Such variant forms should not be regarded as departing from the spirit and scope of the present invention. Therefore, it will be understood by those of ordinary skill in the art that various changes in form and details can be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A method of first station (STA), include: identifying a first service period (SP) configured by a first access point (AP) associated with a first STA; identifying a second SP configured by a second AP; Determining that the first SP overlaps with the second SP; as well as A measurement report frame indicating an overlap between the first SP and the second SP is sent to the first AP.

2. The method according to claim 1, in, The first SP is identified based on first target wake time (TWT) configuration information included in a first beacon frame received from a first AP, and the second SP is identified based on second TWT configuration information included in a second beacon frame or a probe response frame received from a second AP.

3. The method according to claim 1, in, The measurement report frame includes at least one of information about the second AP or second TWT configuration information for the second SP.

4. The method according to claim 1, in, If the first SP is predicted to overlap with the second SP, the measurement report frame is sent before the first SP or the second SP, or if the first SP is determined to overlap with the second SP, the measurement report frame is sent after the first SP or the second SP.

5. The method according to claim 1, further comprising: include: A measurement request frame is received from the first AP, wherein the measurement request frame indicates an overlap between the first SP and the second SP, and a measurement report frame is transmitted when the measurement request frame is received.

6. The method according to claim 1, further comprising: include: receiving, from the first AP, a third beacon frame including TWT reconfiguration information for the first SP; identifying a changed first SP based on the TWT reconfiguration information; performing communication in the changed first SP, The changed first SP does not overlap with the second SP.

7. A method of a first access point (AP), wherein include: transmitting a first beacon frame including first target wake time (TWP) configuration information for a first service period (SP); receiving, from the first STA, a measurement report frame indicating an overlap between the first SP and a second SP configured by the second AP; sending a second beacon frame including TWT reconfiguration information for the first SP, Among them, the first SP changed by the TWT reconfiguration information does not overlap with the second SP.

8. The method according to claim 7, in, The measurement report frame includes at least one of information about the second AP or second TWT configuration information for the second SP.

9. The method according to claim 7, in, If the first SP of the first STA is predicted to overlap with the second SP, the measurement report frame is received before the first SP or the second SP, or if the first SP of the first STA is determined to overlap with the second SP, the measurement report frame is sent after the first SP or the second SP.

10. The method according to claim 7, further comprising: include: In response to determining that the first SP overlaps with the second SP, a measurement request frame is sent, wherein a measurement report frame is received as a response to the measurement request frame.

11. A method of a first station (STA), include: identifying a first service period (SP) configured by a first access point (AP) associated with a first STA; detecting overlapping basic service set (OBSS) interference in a first SP; A measurement report frame indicating occurrence of OBSS interference is sent to the first AP.

12. The method according to claim 11, in, The first SP is identified based on first target wake time (TWT) configuration information included in a first beacon frame received from the first AP, and the OBSS interference is caused by a communication node belonging to the OBSS.

13. The method according to claim 11, in, The measurement report frame includes a cause code, and the cause code indicates occurrence of OBSS interference.

14. The method according to claim 11, further comprising: include: receiving, from the first AP, a second beacon frame including TWT reconfiguration information for the first SP; identifying a changed first SP based on the TWT reconfiguration information; performing communication in the changed first SP, Here, no OBSS interference occurs in the changed first SP.

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