Apparatus and method for fast error recovery in wireless local area network system

Abstract

A method for operating an access point (AP) in a wireless local area network system for fast error recovery in the wireless local area network system comprises the steps of: receiving a plurality of frames from an STA; detecting an error of at least one frame of the plurality of frames; transmitting a retransmission request on the basis of the frame in which the error has been detected; and receiving a retransmission frame based on the retransmission request, the retransmission frame including a frame in which an error is detected, and receiving the retransmission frame on a link in which the retransmission request is transmitted.

Description

Technical Field

[0001] This invention relates to a wireless local area network (WLAN) system, and more specifically, to an apparatus and method for rapid error recovery in a WLAN system. Background Technology

[0002] Recently, with the widespread adoption of mobile devices, wireless LAN technology, which provides fast wireless communication services to mobile devices, has attracted attention. Wireless LAN technology is a technology that uses wireless communication to enable mobile devices (such as smartphones, tablets, laptops, portable multimedia players, embedded devices, etc.) to wirelessly access the internet.

[0003] The standards for wireless LAN technology were primarily developed by the Institute of Electrical and Electronics Engineers (IEEE) as the IEEE 802.11 standard. As wireless LAN technology has developed and become more widespread, its applications have diversified, creating a demand for wireless LAN technologies that support higher reliability.

[0004] With the emergence of applications requiring higher reliability, the IEEE 802.11bn standard is being developed as an Ultra High Reliability (UHR) wireless LAN technology in single Basic Service Set (BSS) and / or redundant BSS environments. The IEEE 802.11bn standard aims to support higher data transmission rates, improved latency performance, and lower data error rates. Furthermore, the IEEE 802.11bn standard supports low-power operation and peer-to-peer communication.

[0005] Methods for recovering errors occurring in frames within a wireless LAN may require improvement. When multiple frames are combined and transmitted, some erroneous frames may not be recovered until all frames have been sent and acknowledgments of the errors have been received. Because acknowledgments of erroneous frames may only be received after all frames have been sent, errors may not be recovered quickly. In other words, the requirement for low-latency communication may not be met.

[0006] On the other hand, the techniques described in the background section are written to improve the understanding of the background of the present invention, and may include content that is not yet known to those skilled in the art to which the present invention pertains. Summary of the Invention

[0007] Technical issues The present invention provides a method and apparatus for detecting and reporting errors in frames received by an access point (AP) in a wireless local area network system.

[0008] This invention provides a method and apparatus for enabling a station (STA) in a wireless local area network system to quickly recover frames that have been detected as erroneous.

[0009] The present invention provides a method and apparatus for enabling APs and STAs utilizing non-simultaneous transmit / receive (NSTR) link pairs in a wireless local area network system to use at least one link to report and recover errors in frames.

[0010] The present invention also provides a method and apparatus for transmitting frames that request retransmission of frames that have detected errors in a wireless local area network system.

[0011] The technical objectives to be achieved in this invention are not limited to those described above, and those skilled in the art who apply the technical configuration of this invention may consider other technical objectives not mentioned in the embodiments of this invention described below.

[0012] Technical solution A method for operating an access point (AP) in a wireless local area network system may include: receiving a plurality of frames from a slave station (STA); detecting an error in at least one of the plurality of frames; sending a retransmission request based on the frame in which the error was detected; and receiving a retransmission frame based on the retransmission request. The retransmission frame includes the frame in which the error was detected, and the retransmission frame is received on the link on which the retransmission request was sent.

[0013] A method for an operator station (STA) in a wireless local area network system may include: sending a plurality of frames to an access point (AP); receiving a retransmission request based on a frame in the plurality of frames in which an error is detected; and sending a retransmission frame based on the retransmission request. The retransmission frame includes the frame in which the error is detected, and the retransmission frame is sent on the link where the retransmission request was received.

[0014] An access point (AP) in a wireless local area network (WLAN) system may include a transceiver and a processor connected to the transceiver. The processor is configured to: receive a plurality of frames from a slave station (STA); detect errors in at least one of the plurality of frames; send a retransmission request based on the frame in which the error was detected; and receive a retransmission frame based on the retransmission request. The retransmission frame includes the frame in which the error was detected, and the retransmission frame is received on the link on which the retransmission request was sent.

[0015] A station (STA) in a wireless local area network (WLAN) system may include a transceiver and a processor connected to the transceiver. The processor is configured to: send multiple frames to an access point (AP); receive a retransmission request based on a frame in the multiple frames that has detected an error; and send a retransmission frame based on the retransmission request. The retransmission frame includes the frame in which the error was detected, and the retransmission frame is sent on the link where the retransmission request was received.

[0016] Beneficial effects According to the present invention, a feedback frame including time information capable of identifying frames in which errors are detected can be transmitted in a wireless local area network system.

[0017] According to the present invention, an MPDU including information about the previous MPDU and the next MPDU can be transmitted.

[0018] According to the present invention, the AP can identify frames that have detected errors and transmit feedback frames.

[0019] The effects obtained in this invention are not limited to those described above, and those skilled in the art who apply the technical configuration of this invention can clearly deduce and understand other effects not mentioned above from the following description of the embodiments of this invention. That is, those skilled in the art can also deduce from the embodiments of this invention effects that were not intended in implementing the configurations described in this invention. Attached Figure Description

[0020] Figure 1 This is a block diagram illustrating a first embodiment of a communication node constituting a wireless local area network system.

[0021] Figure 2 This is a flowchart illustrating an implementation scheme for the negotiation process of multi-link operation in a wireless local area network system.

[0022] Figure 3 A first implementation of the fast error recovery method is shown.

[0023] Figure 4 A second implementation of the fast error recovery method is shown.

[0024] Figure 5 A third implementation of the fast error recovery method is shown.

[0025] Figure 6 A fourth implementation of the fast error recovery method is shown.

[0026] Figure 7 A fifth implementation of the fast error recovery method is shown.

[0027] Figure 8 A flowchart of an error recovery process according to one embodiment of the present invention is shown.

[0028] Figure 9 A flowchart of an error recovery process according to one embodiment of the present invention is shown. Detailed Implementation

[0029] This invention can have various modifications and embodiments, and specific embodiments are shown in the accompanying drawings and described in detail in the specific description. However, this is not intended to limit the invention to the specific embodiments, but should be understood to include all modified embodiments, equivalent embodiments, or alternative embodiments that are included within the spirit and technical scope of the invention.

[0030] The terms "first," "second," etc., can be used to describe various components, but components should not be limited by the terms. Terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the invention, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component. Terms and / or include combinations of multiple related descriptive terms or any one of multiple related descriptive terms.

[0031] When a component is claimed to be "connected to / attached to another component" or "connected to" another component, it should be understood that this component is directly connected to the other component or connected to the other component through any other component in between. On the other hand, when a component is claimed to be "directly connected to" or "directly coupled to" another component, it should be understood that there are no other components between these two components.

[0032] The terminology used in this invention is for describing particular embodiments only and is not intended to limit the invention. Unless the context clearly indicates otherwise, singular expressions include plural expressions. In this invention, terms such as “comprising” or “having” are intended to specify the presence of the features, quantities, steps, operations, components, parts, or combinations thereof described in this specification, but should be understood not to preclude the possibility of the presence or addition of one or more other features, quantities, steps, operations, components, parts, or combinations thereof.

[0033] Unless otherwise defined, all terms used herein (including technical or scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in general dictionaries shall be interpreted as having the same meaning as they have in the context of the relevant art, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0034] Preferred embodiments of the invention will be described in more detail below with reference to the accompanying drawings. In describing the invention, for ease of overall understanding, the same reference numerals are used for the same components in the drawings, and repeated descriptions of the same components are omitted.

[0035] The following describes a wireless communication system applying embodiments of the present invention. The wireless communication system applying embodiments of the present invention is not limited to the following description, and the embodiments of the present invention can be applied to various wireless communication systems. The wireless communication system may be referred to as a "wireless communication network".

[0036] Figure 1 A block diagram of a communication node in a wireless local area network system is shown.

[0037] refer to Figure 1 Communication node 100 can be an access point (AP), a station (STA), an AP multi-link device (MLD), or a non-AP MLD. A STA can be a non-AP STA. The operating channel width supported by the AP can be 20 MHz, 80 MHz, or 160 MHz. The operating channel width supported by the STA can be 20 MHz or 80 MHz.

[0038] Communication node 100 may include at least one processor 110, memory 120, and at least one transmitting / receiving device 130, which is connected to a network and performs communication. Transmitting / receiving device 130 may also be referred to as a transceiver, radio frequency (RF) unit, or RF module. Additionally, communication node 100 may further include an input interface device 140, an output interface device 150, and a storage device 160. Components included in communication node 100 can be connected via bus 170 and perform communication between components.

[0039] However, each component included in communication node 100 may be connected via a separate interface or bus around processor 110 instead of via common bus 170. For example, processor 110 may be connected via a dedicated interface to at least one of memory 120, transmitting / receiving device 130, input interface device 140, output interface device 150, and storage device 160.

[0040] Processor 110 can execute program instructions stored in at least one of memory 120 and storage device 160. Processor 110 can be a central processing unit (CPU), graphics processing unit (GPU), or dedicated processor that performs methods according to embodiments of the present invention. Memory 120 and storage device 160 can each be configured as at least one volatile storage medium and at least one non-volatile storage medium. For example, memory 120 can be configured as at least one read-only memory (ROM) and random access memory (RAM).

[0041] Figure 2 This is a flowchart illustrating an implementation scheme for the negotiation process of multi-link operation in a wireless local area network system.

[0042] refer to Figure 2 The connection process between a station (STA) and an access point (AP) in the basic service set (BSS) can include access point detection steps, authentication steps between the station and the detected access point, and association steps between the station and the authenticated access point.

[0043] During the probe step, a station can detect one or more access points using either a passive scanning method or an active scanning method. When using a passive scanning method, a station can detect one or more access points by listening to beacon frames sent by one or more access points. When using an active scanning method, a station can detect one or more access points by sending probe request frames and receiving probe response frames from one or more access points as a response to the probe request frames.

[0044] If one or more access points are detected, the station can perform authentication steps with the detected access points. In this case, the station can perform authentication steps with multiple access points. Authentication algorithms according to the IEEE 802.11 standard can be classified into open system algorithms that exchange two authentication frames and shared key algorithms that exchange four authentication frames.

[0045] The station can send authentication request frames based on the authentication algorithm according to the IEEE 802.11 standard, and complete authentication with the access point by receiving authentication response frames from the access point as a response to the authentication request frames.

[0046] Once authentication with an access point is complete, the station can perform the association step with that access point. In this case, the station can select one of the access points that has already undergone authentication with it and perform the association step with the selected access point. That is, the station can send an association request frame to the selected access point and complete the association with the selected access point by receiving an association response frame from the selected access point as a response to the association request frame.

[0047] On the other hand, multi-link operation can be supported in wireless LAN systems. A Multi-Link Detection Element (MLD) can include one or more STAs associated with it. An MLD can be a logical entity. MLDs can be classified as AP MLDs and non-AP MLDs. Each STA associated with an AP MLD can be an AP, and each STA associated with a non-AP MLD can be a non-AP STA. To configure multiple links, multi-link discovery procedures, multi-link establishment procedures, etc., can be performed. The multi-link discovery procedure can be performed during the probe step between the station and the access point. In this case, the multi-link information element (MLIE) can be included in the beacon frame, probe request frame, and / or probe response frame.

[0048] For example, to perform multi-link operation, information indicating whether multi-link operation is available and information about available links can be exchanged between the access point (e.g., an AP associated with an MLD) and the station (e.g., a non-AP STA associated with an MLD) during the probing step. In the negotiation process for multi-link operation (e.g., a multi-link establishment process), the access point and / or station can send information about the links to be used for multi-link operation. The negotiation process for multi-link operation can be performed during the association process between the station and the access point (e.g., an association step), and the information elements required for multi-link operation can be set or changed by action frames during the negotiation process.

[0049] Additionally, during the connection process between the station and the access point (e.g., the association step), the available links of the access point can be configured, and an identifier (ID) can be assigned to each link. Subsequently, during the negotiation and / or change process for multi-link operation, information indicating whether each link is active can be sent, and this information can be expressed using the link ID.

[0050] Information indicating the availability of multi-link operation (STR) can be sent and received during the exchange of capability information elements (e.g., extremely high throughput (EHT) capability information elements) between the station and the access point. Capability information elements may include information about supported frequency bands, information about supported links (e.g., the ID and / or number of supported links), and information about links capable of STR operation (e.g., link frequency band information, link spacing information), etc. Additionally, capability information elements may include information specifically indicating which links are capable of STR operation.

[0051] Figure 3 A first implementation of the fast error recovery method is shown.

[0052] refer to Figure 3 AP 1-1 301 and AP 1-2 303, associated with AP MLD 1, are operable, with AP 1-1 301 operating on the first link and AP 1-2 303 operating on the second link. STA 1-1 311 and STA 1-2 313, associated with STA MLD 1, are operable, with STA 1-1 311 operating on the first link and STA 1-2 313 operating on the second link. The first and second links can be a Non-Simultaneous Transmit and Receive (NSTR) link pair. STA 1-1 311 can perform a channel access operation (e.g., EDCA backoff operation) to obtain a TXOP. Within the TXOP acquired by STA 1-1 311, STA 1-1 311 may transmit at least one frame (e.g., Physical Layer Protocol Data Unit (PPDU), Medium Access Control Layer Protocol Data Unit (MPDU), Aggregated MPDU (A-MPDU)). The PPDU transmitted by STA 1-1 311 may include at least one MPDU or A-MPDU.

[0053] STA 1-1 311 can send UL PPDU 1 320 as the first frame of TXOP. STA MLD 1 can establish a BA session with AP MLD 1 for each TID. That is, a BA session can be established for each MLD. For example, STA 1-1 311 can establish a BA session corresponding to a specific TID with AP 1-1 301 on the first link, and STA 1-1 311 of STA MLD 1 can act as the initiator, and AP 1-1 301 of AP MLD 1 can act as the receiver. AP 1-1 301 can record the SN of the MPDU and / or MSDU included in the received UL PPDU 1 320 in the scoreboard and store the received frame in a reordering buffer. If AP 1-1 301 does not receive UL PPDU 1 320 correctly, a specific SN may be missing from the scoreboard, and the MSDU corresponding to the next SN of the missing SN may not be forwarded to the upper layer. AP 1-1 301 can request STA 1-1 311 to recover missing MPDUs and / or MSDUs. The recovery of MPDUs and / or MSDUs can be prioritized. AP 1-1 301 can utilize priorities to request STA 1-1 311 to recover missing MPDUs and / or MSDUs. For example, AP 1-1 301 can request the recovery of missing MPDUs and / or MSDUs based on the priority of a TID. Here, the TID is mapped to an AC, and in this case, the priority of the TID is the priority of the AC. Alternatively, AP 1-1 301 can request the recovery of missing MPDUs and / or MSDUs based on the priority of the frame, according to delay boundary information.

[0054] When a missing MPDU and / or MSDU is identified, the AP MLD can perform a channel access operation (e.g., EDCA backoff operation) on a link other than the first link that transmitted UL PPDU 1 320 (e.g., a second link). The channel access operation may include a backoff operation. According to one embodiment of the invention, initiating a backoff operation can be initiating a channel access operation. That is, once an error is identified on the first link, a backoff operation can be initiated on the second link. Alternatively, when a frame transmission is initiated on the first link, a backoff operation can be initiated on the second link. When the backoff operation is completed on the second link (e.g., when the backoff counter reaches 0), and STA 1-1 311 has completed transmission on the first link and is in a receiving state, i.e., when it can also receive on the second link, AP 1-2 303 can send a frame (e.g., a trigger frame (TF) 340) to STA 1-2 313 indicating that an error has occurred in the transmission of the frame sent by STA 1-1 311. Frame 340, indicating the transmission of a frame that has encountered an error, can be sent simultaneously with Block Acknowledgment (Block Ack, BA) frame 330 sent on the first link. It can indicate the resources available for transmission of the erroneous frame (e.g., uplink transmission time) and can include an Association ID (AID), which is an identifier assigned by the AP MLD to each STA MLD as a terminal identifier. The frame indicating the transmission of a erroneous frame can indicate the AID of STA MLD1. The AID of STA MLD1 can be the same as the AIDs of STA 1-1 311 and STA 1-2 313. Upon completion of the backoff operation, if STA 1-1 311 is transmitting on the first link, AP 1-2 303 can keep the backoff counter at 0 and wait without sending a frame. When it is anticipated that STA 1-1 311 has terminated transmission on the first link and is waiting to receive, AP 1-2 303 can send frame 340 indicating the transmission of a frame that has encountered an error. In the queue of the EDCAF associated with the Access Category (AC) whose backoff counter is held at 0 for AP 1-2 303, a packet (e.g., MSDU) destined for another STA other than STA 1-2 313 associated with STA MLD 1 may appear. AP 1-2 303 of AP MLD 1 may treat the buffer of the AC with its backoff counter held at 0 as empty until the transmission of a frame that has already erroneously occurred is terminated, and may delay the transmission of any packets that appear.Alternatively, even if the backoff operation is terminated when "STA 1-1 311 is transmitting on the first link," a new backoff operation can be performed again until STA 1-1 311 terminates transmission on the first link. AP 1-1 301 may transmit BA frame 330 after a certain period of time (e.g., SIFS time) from the end time of transmission of UL PPDU 1 320 transmitted by STA 1-1 311. AP MLD may transmit a frame indicating the transmission of an erroneous frame on the second link, rather than on the first link where BA frame 330 is transmitted, while transmitting BA frame 330. Alternatively, the start time of transmission of BA frame 330 of AP MLD 1 and AP 1-2 303 and the start time of transmission of frame 340 indicating the transmission of an erroneous frame may be different. Frame 340, indicating the transmission of a frame that has encountered an error, can be padded to align the transmission end time with BA frame 330 so that the frame that has encountered an error can be transmitted simultaneously with the transmission on the first link. Alternatively, the transmission start time can be adjusted so that the transmission end time of frame 340, indicating the transmission of a frame that has encountered an error, coincides with the end time of BA frame 330 transmitted by STA 1-1 311 on the first link. BA frame 330 can be padded to align the transmission end time with frame 340, indicating the transmission of a frame that has encountered an error, for simultaneous transmission of subsequent frames. Padding includes padding fields and padding bits. Padding can be performed in MAC frames or in PHY PPDUs. Frame 340, indicating the transmission of a frame that has encountered an error, can include TID information of the MPDU and / or MSDU that was not received correctly in various forms (e.g., fields, subfields, and indicator bits). STA MLD 1 can place the MPDUs and / or MSDUs requiring fast recovery at the very beginning of UL PPDU 2 and transmit them first, by referring to parameters (e.g., information about MPDUs and / or MSDUs not received correctly) included in the received BA frame 330 and frame 340 indicating that an error has occurred during transmission. Alternatively, STA MLD 1 can transmit the MPDUs and / or MSDUs requiring fast recovery as separate UL PPDUs on a second link, in addition to the first link that transmits UL PPDU 1 320. Alternatively, STA MLD 1 can transmit the MPDUs and / or MSDUs requiring fast recovery on both the first and second links.

[0055] The PPDUs transmitted by AP MLD 1 on the first and second links can be self-decoding. To correct errors in the PPDUs, a channel coding-decoding combination method (e.g., Chase combining) can be used to attempt decoding by combining the original data packet that has been erroneously transmitted with the retransmitted data packet. In this embodiment, the channel coding-decoding combination method is referred to as the "CC combining method". When decoding of a PPDU received on the first link fails (e.g., when an error occurs in an MPDU included in a PPDU received on the first link, or when error correction of a PPDU received on the first link fails), STA MLD 1 combines the PPDU received on the first link with the PPDU received on the second link and then performs decoding to decode the correct frame. PPDU combination is performed after PPDU demodulation in the physical layers of STA 1 and STA 2 of STA MLD 1. PPDU combination and decoding of the combined PPDU can be performed in either the physical layer of STA 1 or STA 2. Alternatively, PPDU combination and decoding of the combined PPDU can be performed by a separate entity existing in STA MLD 1. When using the CC combination method, the PPDUs transmitted by AP MLD 1 on the first link and the PPDUs transmitted on the second link can use the same redundancy (e.g., redundancy bits, channel codec bits). For example, the PPDUs transmitted on the first link and the PPDUs transmitted on the second link can use the same channel codec and can be identical PPDUs with the same codeword (e.g., bits including data bits and redundancy bits for error correction). Even when using the channel codec combination method and STA MLD 1 combines the PPDUs received on the first link and the PPDUs received on the second link, decoding may still fail. STA MLD 1 can request additional retransmission PPDUs (e.g., PPDU N) from AP MLD 1 and can combine the PPDUs. STA MLD 1 can perform frame decoding based on the combined PPDUs. In methods different from the channel codec combination method, a channel codec combination method (e.g., incremental redundancy) can be used, which gradually increases the channel codec gain for each retransmission and performs retransmission. In this invention, the channel codec combination method is referred to as the "IR combination method". When using the IR combination method, if decoding of the PPDU received on the first link fails, STA MLD 1 can use the PPDU received on the second link to decode the correct PPDU. The codewords of the PPDUs transmitted by AP MLD 1 on the first link and the PPDUs transmitted on the second link include the same data bits, but have different redundancies (e.g., redundancy bits, channel codec bits). That is, the two PPDUs are PPDUs with different codewords.STA MLD 1 can combine PPDUs received on the first link and PPDUs received on the second link, gaining additional redundancy for correcting errors in the PPDUs. Since the PPDUs received on the first link and the second link have different redundancies, the code rate of the combined PPDU is reduced. As the code rate decreases, the redundant bits used for data bits increase, allowing for better error recovery. For example, if the code rate of the PPDU received on the first link is 3 / 4 and the code rate of the PPDU received on the second link is 3 / 4, then the code rate of the combined PPDU can be 3 / 5. If three PPDUs with a code rate of 3 / 4 are combined, the code rate of the combined PPDU can be 1 / 2. STA MLD1 can use the combined PPDU to correct and decode errors in the PPDU.

[0056] In both channel codec combination methods (CC combination and IR combination), the transmitted PPDU can be self-decoding. Therefore, if the retransmitted PPDU (e.g., PPDU transmitted on a second link) is error-free and self-decoding, PPDU combination can be omitted.

[0057] In both channel codec combining methods (CC combining and IR combining), decoding errors can be detected based on MPDUs. For example, an error may occur in the second MPDU included in the PPDU transmitted by AP MLD 1 on the first link, while no error may occur in the remaining MPDUs. AP MLD 1 can transmit a PPDU that only includes the second MPDU instead of retransmitting the entire PPDU on the second link for channel codec combining. STA MLD 1 can combine a portion of the PPDU received on the first link (e.g., a portion of the PPDU that includes the second MPDU) with the PPDU received on the second link and decode the combined PPDU. Based on the combined PPDU, STA MLD 1 can correctly receive the second MPDU that has already been erroneous.

[0058] AP 1-1 301 may send a BA frame after a certain period of time (e.g., SIFS time) from the end time of transmission of UL PPDU 2. When AP MLD receives the recovered MPDU and / or MSDU, AP MLD may reorder the MPDU and / or MSDU waiting in the reordering buffer and forward them to the upper layer.

[0059] Figure 4 A second implementation of the fast error recovery method is shown.

[0060] refer to Figure 4AP 1-1 401 and AP 1-2 403, associated with AP MLD 1, are operable, with AP 1-1 401 operating in the first link and AP 1-2 403 operating in the second link. STA 1-1 411 and STA 1-2 413, associated with STA MLD 1, are operable, with STA 1-1 411 operating in the first link and STA 1-2 413 operating in the second link. The first and second links can be a non-simultaneous transmit and receive (NSTR) link pair. STA 1-1 411 can perform a channel access operation (e.g., EDCA backoff operation) to acquire a TXOP. Within the TXOP acquired by STA 1-1 411, STA 1-1 411 can transmit at least one frame (e.g., Physical Layer Protocol Data Unit (PPDU), Media Access Control Layer Protocol Data Unit (MPDU), Aggregated MPDU (A-MPDU)). The PPDU sent by STA 1-1 411 may include at least one MPDU or A-MPDU.

[0061] STA 1-1 411 can send UL PPDU 420 as the first frame of TXOP. STA MLD 1 can establish a BA session with AP MLD 1 for each TID. That is, a BA session can be established for each MLD. For example, STA 1-1 411 can establish a BA session corresponding to a specific TID with AP 1-1 401 on the first link, and STA 1-1 411 of STA MLD 1 can act as the initiator, and AP 1-1 401 of AP MLD 1 can act as the receiver. AP 1-1 401 can record the SN of the MPDU and / or MSDU included in the received UL PPDU 420 in the scoreboard and store the received frame in a reordering buffer. If AP 1-1 401 does not receive the UL PPDU 420 correctly, a specific SN may be missing from the scoreboard, and the MSDU corresponding to the next SN of the missing SN may not be forwarded to the upper layer. AP 1-1 401 can request STA 1-1 411 to recover missing MPDUs and / or MSDUs. The recovery of MPDUs and / or MSDUs can be prioritized. AP 1-1 401 can utilize priorities to request STA 1-1 411 to recover missing MPDUs and / or MSDUs. For example, AP 1-1 401 can request the recovery of missing MPDUs and / or MSDUs based on the priority of a TID. Here, the TID is mapped to an AC, and in this case, the priority of the TID is the priority of the AC. Alternatively, AP 1-1 401 can request the recovery of missing MPDUs and / or MSDUs based on the priority of the frame, according to delay boundary information.

[0062] When a missing MPDU and / or MSDU is identified, the AP MLD can perform a channel access operation (e.g., EDCA backoff operation) on a link other than the first link that transmitted the UL PPDU 420 (e.g., a second link). The channel access operation may include a backoff operation. According to one embodiment of the invention, initiating a backoff operation can be initiating a channel access operation. That is, once an error is identified on the first link, a backoff operation can be initiated on the second link. Alternatively, when a frame transmission is initiated on the first link, a backoff operation can be initiated on the second link. When the backoff operation is completed on the second link (e.g., when the backoff counter reaches 0), and STA 1-1 411 has completed transmission on the first link and is in a receiving state, i.e., when it can also receive on the second link, AP 1-2 403 can send a frame (e.g., a trigger frame (TF) 440) to STA 1-2 413 indicating that an error has occurred in the transmission of the frame sent by STA 1-1 411. Frame 440, indicating the transmission of a frame that has encountered an error, can be sent simultaneously with BA frame 430 transmitted on the first link. It can indicate the resources available for transmission of the frame that has encountered an error (e.g., uplink transmission time) and can indicate information that can be specified for STA MLD 1 (e.g., association identifier (AID)). The AID of STA MLD 1 is the same for STA 1-1 411 and STA 1-2 413. When the backoff operation is complete, if STA 1-1 411 is transmitting on the first link, AP 1-2 403 can keep the backoff counter at 0 and wait without transmitting a frame. When it is expected that STA 1-1 411 has terminated transmission on the first link and is waiting to receive, AP 1-2 403 can send frame 440 indicating the transmission of a frame that has encountered an error. An MSDU for a STA MLD with an AID different from the AID of STA MLD1 can be generated or entered in the EDCAF associated with the Access Class (AC) where the backoff counter is 0. In other words, MSDUs can be generated or input for destinations other than STA MLD or STAMLD 1, as well as for STAs associated with STA MLD 1. AP MLD 1 can treat the buffer of an AC with a backoff counter of 0 as empty until the transmission of a frame that has already erroneously occurred is complete, and can delay the transmission of the generated MSDU. Alternatively, even if the backoff operation is completed when "STA 1-1 411 is transmitting on the first link", a new backoff operation can be performed again until STA 1-1 411 terminates transmission on the first link. AP 1-1 401 can transmit BA frame 430 after a certain period of time (e.g., SIFS time) from the end time of the transmission of UL PPDU 420 transmitted by STA 1-1 411.AP MLD can simultaneously transmit a frame (e.g., trigger frame (TF) 440) indicating the transmission of a frame that has encountered an error on a second link, outside the first link that transmits BA frame 430. Alternatively, the transmission start time of the BA frame of AP MLD 1 (AP 1-1401) and AP 1-2 (AP 1-2 403) can differ from the transmission start time of frame 440 indicating the transmission of a frame that has encountered an error. Frame 440 indicating the transmission of a frame that has encountered an error can be padded to align its transmission end time with BA frame 430 so that the frame that has encountered an error is transmitted simultaneously with the transmission on the first link, or the transmission start time can be adjusted so that the transmission end time of frame 440 indicating the transmission of a frame that has encountered an error can coincide with the end time of BA frame 430 transmitted by STA 1-1 (STA 411) on the first link. BA frame 430 can be padded for simultaneous transmission of subsequent frames to match the transmission end time with frame 440 indicating the transmission of a frame that has encountered an error. Padding includes padding fields and padding bits. Padding can be performed in MAC frames or PHY PPDUs. Frame 440, indicating that an error has occurred during the transmission of a frame, can include TID information for MPDUs and / or MSDUs that were not correctly received in various forms (e.g., fields, subfields, and indicator bits). Padding is used to extend the end time of frame transmission.

[0063] When it is anticipated that the original TXOP of STA 1-1 411 obtained via the initially sent UL PPDU 420 will end with the transmission of BA frame 430 (e.g., when it is anticipated that the original TXOP of STA 1-1 411 will end soon), AP 1-2 403 of AP MLD may send a control frame (e.g., a trigger frame) on a second link to obtain a new TXOP for rapid recovery of the missing MPDU and / or MSDU. The control frame sent by AP MLD includes indicators (e.g., indicators of at least one of fields, subfields, information elements, and indicator bits) indicating the recovery of the missing MPDU and / or MSDU. AP MLD may instruct (e.g., trigger) the transmission of a UL PPDU, which includes retransmission data (e.g., the recovered MPDU and / or MSDU) 450 for retransmitting the frame that has already been erroneously transmitted in the newly acquired TXOP, and the transmission of the UL PPDU may be carried on a different link than the initially sent UL PPDU (e.g., a second link). An AP MLD that has received a UL PPDU including retransmission data 450 can send a BA frame after a certain period of time (e.g., SIFS time) from the end time of the transmission of the UL PPDU frame including retransmission data 450. When a recovered MPDU and / or MSDU is received, the AP MLD can reorder the MPDUs and / or MSDUs waiting in the reordering buffer and forward them to the upper layer.

[0064] Figure 5 A third implementation of the fast error recovery method is shown.

[0065] refer to Figure 5AP 1-1 501 and AP 1-2 503, associated with AP MLD 1, are operable, with AP 1-1 501 operating in the first link and AP 1-2 503 operating in the second link. STA 1-1 511 and STA 1-2 513, associated with STA MLD 1, are operable, with STA 1-1 511 operating in the first link and STA 1-2 513 operating in the second link. The first and second links can be Enhanced Multi-Link Single Radio (EMLSR) links performing EMLSR operations or / and Non-Simultaneous Transmit and Receive (NSTR) link pairs. STA 1-1 511 can perform channel access operations (e.g., EDCA backoff operation) to obtain a TXOP. Within the TXOP acquired by STA 1-1511, STA 1-1 511 may transmit at least one frame (e.g., Physical Layer Protocol Data Unit (PPDU), Media Access Control Layer Protocol Data Unit (MPDU), Aggregated MPDU (A-MPDU)). The PPDU transmitted by STA 1-1 511 may include at least one MPDU or A-MPDU.

[0066] STA 1-1 511 can send UL PPDU 520 as the first frame of TXOP. STA MLD 1 can establish a BA session with AP MLD 1 for each TID. That is, a BA session can be established for each MLD. For example, STA 1-1 511 can establish a BA session corresponding to a specific TID with AP 1-1 501 on the first link, and STA 1-1 511 of STA MLD 1 can act as the initiator, while AP 1-1 501 of AP MLD 1 can act as the receiver. AP 1-1 501 can record the SN of the MPDU and / or MSDU included in the received UL PPDU 520 in the scoreboard and store the received frame in a reordering buffer. If AP 1-1 501 does not receive the UL PPDU 520 correctly, a specific SN may be missing from the scoreboard, and the MSDU corresponding to the next SN of the missing SN may not be forwarded to the upper layer. AP 1-1 501 can request STA 1-1 511 to recover missing MPDUs and / or MSDUs. The recovery of MPDUs and / or MSDUs can be prioritized. AP 1-1 501 can utilize priorities to request STA 1-1 511 to recover missing MPDUs and / or MSDUs. For example, AP 1-1 501 can request the recovery of missing MPDUs and / or MSDUs based on the priority of a TID. Here, the TID is mapped to an AC, and in this case, the priority of the TID is the priority of the AC. Alternatively, AP 1-1 501 can request the recovery of missing MPDUs and / or MSDUs based on the priority of the frame, according to delay boundary information.

[0067] AP 1-1 501 may send BA frame 530 after a certain period of time (e.g., SIFS time) from the end time of transmission of UL PPDU 520 sent by STA 1-1 511. AP 1-1 501 may send an indicator to cause STA 1-1 511, as the TXOP holder, to extend the TXOP limit to retransmit missing MPDU and / or MSDU. In a particular embodiment, AP 1-1 501 may include the indicator in BA frame 530 as a field, subfield, or information element. In another embodiment, AP 1-1 501 may configure the indicator as a separate MPDU and send it to STA 1-1 511 as an MPDU or A-MPDU including BA frame 530. In another embodiment, AP 1-1 501 may include the indicator in a QoS frame (e.g., a QoS empty frame and a QoS data frame) or an action frame. QoS frames or action frames can be QoS frames that do not request an immediate response (e.g., frames with an Ack policy set to no Ack) or action frames without Ack. STA 1-1 511 can use an extended TXOP based on the TXOP restriction extension indicator in the BA frame issued by AP 1-1 501. STA MLD 1 can be an EMLSR MLD, and STA 1-1 511 and STA 1-2 513 can perform EMLSR operations. When STA 1-1 511 receives a BA frame 530 including the TXOP extension indicator, STA 1-1 511 can extend the TXOP. STA 1-1 511 can transmit frames within the extended TXOP during EMLSR operations using the extended TXOP without returning to a listen operation. A listen operation is a state where the STA MLD can only receive the initial control frame. The initial control frame includes a MU-RTS trigger frame and a buffer status report poll (BSRP) trigger frame. Because STA 1-1 511 uses extended TXOP for communication without returning to listen operation, no additional channel access procedures (e.g., EDCA backoff operation and EMLSR initial control frame transmission procedures) are required, and additional delays are prevented because the transition delays that occur during EMLSR operation (e.g., EMLSR transition delays that occur when transitioning to listen operation) do not occur. STA 1-1 511 can send a UL PPDU including retransmission data 540 to AP 1-1 501 on the first link that sends the initial UL PPDU. AP 1-1 501, having received the UL PPDU including retransmission data 540, can send a BA frame after a certain period of time (e.g., SIFS time) from the end time of the UL PPDU transmission.When a recovered MPDU or / and MSDU is received, the AP MLD can reorder the MPDU or / and MSDU waiting in the reorder buffer and forward them to the upper layer.

[0068] Figure 6 A fourth implementation of the fast error recovery method is shown.

[0069] refer to Figure 6 AP 1-1 601 and AP 1-2 603, associated with AP MLD 1, are operable, with AP 1-1 601 operating in the first link and AP 1-2 603 operating in the second link. STA 1-1 611 and STA 1-2 613, associated with STA MLD 1, are operable, with STA 1-1 611 operating in the first link and STA 1-2 613 operating in the second link. The first and second links can be Enhanced Multi-Link Single Radio (EMLSR) links performing EMLSR operations or / and Non-Simultaneous Transmit and Receive (NSTR) link pairs. STA 1-1 611 can perform channel access operations (e.g., EDCA backoff operation) to obtain a TXOP. Within the TXOP acquired by STA 1-1 611, STA 1-1 611 may transmit at least one frame (e.g., Physical Layer Protocol Data Unit (PPDU), Media Access Control Layer Protocol Data Unit (MPDU), Aggregated MPDU (A-MPDU)). The PPDU transmitted by STA 1-1 611 may include at least one MPDU or A-MPDU.

[0070] STA 1-1 611 can send UL PPDU 620 as the first frame of TXOP. STA MLD 1 can establish a BA session with AP MLD 1 for each TID. That is, a BA session can be established for each MLD. For example, STA 1-1 611 can establish a BA session corresponding to a specific TID with AP 1-1 601 on the first link, and STA 1-1 611 of STA MLD 1 can act as the initiator, and AP 1-1 601 of AP MLD 1 can act as the receiver. AP 1-1 601 can record the SN of the MPDU and / or MSDU included in the received UL PPDU 620 in the scoreboard and store the received frame in a reordering buffer. If AP 1-1 601 does not receive the UL PPDU 620 correctly, a specific SN may be missing from the scoreboard, and the MSDU corresponding to the next SN of the missing SN may not be forwarded to the upper layer. AP 1-1 601 can request STA 1-1 611 to recover missing MPDUs and / or MSDUs. The recovery of MPDUs and / or MSDUs can be prioritized. AP 1-1 601 can utilize priorities to request STA 1-1 611 to recover missing MPDUs and / or MSDUs. For example, AP 1-1 601 can request the recovery of missing MPDUs and / or MSDUs based on the priority of a TID. Here, the TID is mapped to an AC, and in this case, the priority of the TID is the priority of the AC. Alternatively, AP 1-1 601 can request the recovery of missing MPDUs and / or MSDUs based on the priority of the frame, according to delay boundary information.

[0071] AP 1-1 601 may transmit a BA frame after a certain period of time (e.g., SIFS time) following the end time of transmission of the UL PPDU sent by STA 1-1 611. If the initially transmitted UL PPDU 620 is not received correctly, AP 1-1 601 may include an indicator in the BA frame 630 as a field, subfield, or information element, which instructs STA MLD 1 to perform normal transmit / receive operations on the second link (e.g., operations for retransmitting the erroneous frame) to recover the erroneous frame. STA MLD 1, having received a frame including the indicator indicating normal transmit / receive operations (e.g., operations for retransmitting the erroneous frame) on the second link, may perform normal transmit / receive operations (e.g., operations for retransmitting the erroneous frame) on the second link after an EMLSR conversion delay time following the receipt of the frame including the indicator. AP 1-2 603 may pre-execute a backoff operation to trigger the transmission of the UL PPDU including retransmitted data 650 on the second link, and may wait until the time when STA 1-2 613 is expected to perform normal transmit / receive operation (e.g., operation for retransmitting a frame that has already been erroneous) (e.g., after the EMLSR conversion delay time from the transmission completion time of the frame including the indicator of AP 1-1 601). Alternatively, AP 1-2 603 may repeat the backoff operation until the time when STA 1-2 613 is expected to perform normal transmit / receive operation (e.g., operation for retransmitting a frame that has already been erroneous) (e.g., after the EMLSR conversion delay time from the transmission completion time of the frame including the indicator of AP 1-1 601). AP 1-2 603 may wait for the transmission of trigger frame 640 on the second link until after the EMLSR conversion delay time from the transmission completion time of BA frame 630 on the first link. AP 1-2 603 can trigger a ULPPDU including retransmitted data 650 by sending a trigger frame to STA 1-2 613 after an EMLSR conversion delay time starting from the transmission completion time of BA frame 630 on the first link. STA 1-2 613 can send the retransmitted data 650 indicated by trigger frame 640 to AP 1-2 603. AP 1-2 603 can send a BA frame after a certain period of time (e.g., SIFS time) starting from the transmission end time of the UL PPDU including the retransmitted data 650 sent by STA 1-2 613. When a recovered MPDU and / or MSDU is received, AP MLD can reorder the MPDU and / or MSDU waiting in the reordering buffer and forward them to the upper layer.

[0072] Figure 7 A fifth implementation of the fast error recovery method is shown.

[0073] refer to Figure 7 AP 1-1 701 and AP 1-2 703, associated with AP MLD 1, are operable, with AP 1-1 701 operating in the first link and AP 1-2 703 operating in the second link. STA 1-1 711 and STA 1-2 713, associated with STA MLD 1, are operable, with STA 1-1 711 operating in the first link and STA 1-2 713 operating in the second link. The first and second links can be Enhanced Multi-Link Single Radio (EMLSR) links performing EMLSR operations or / and Non-Simultaneous Transmit and Receive (NSTR) link pairs. STA 1-1 711 can perform channel access operations (e.g., EDCA backoff operation) to obtain a TXOP. Within the TXOP acquired by STA 1-1 711, STA 1-1 711 may transmit at least one frame (e.g., Physical Layer Protocol Data Unit (PPDU), Media Access Control Layer Protocol Data Unit (MPDU), Aggregated MPDU (A-MPDU)). The PPDU transmitted by STA 1-1 711 may include at least one MPDU or A-MPDU.

[0074] STA 1-1 711 can send UL PPDU 720 as the first frame of TXOP. STA MLD 1 can establish a BA session with AP MLD 1 for each TID. That is, a BA session can be established for each MLD. For example, STA 1-1 711 can establish a BA session corresponding to a specific TID with AP 1-1 701 on the first link, and STA 1-1 711 of STA MLD 1 can act as the initiator, and AP 1-1 701 of AP MLD 1 can act as the receiver. AP 1-1 701 can record the SN of the MPDU and / or MSDU included in the received UL PPDU 720 in the scoreboard and store the received frame in a reordering buffer. If AP 1-1 701 does not receive the UL PPDU 720 correctly, a specific SN may be missing from the scoreboard, and the MSDU corresponding to the next SN of the missing SN may not be forwarded to the upper layer. AP 1-1 701 can request STA 1-1 711 to recover missing MPDUs and / or MSDUs. The recovery of MPDUs and / or MSDUs can be prioritized. AP 1-1 701 can utilize priorities to request STA 1-1 711 to recover missing MPDUs and / or MSDUs. For example, AP 1-1 701 can request the recovery of missing MPDUs and / or MSDUs based on the priority of a TID. Here, the TID is mapped to an AC, and in this case, the priority of the TID is the priority of the AC. Alternatively, AP 1-1 701 can request the recovery of missing MPDUs and / or MSDUs based on the priority of the frame, according to delay boundary information.

[0075] AP 1-1 701 may transmit BA frame 730 after a certain period of time (e.g., SIFS time) following the transmission end time of UL PPDU 720 sent by STA 1-1 711. STA MLD 1 may switch STA 1-1 711 on the first link and STA 1-2 713 on the second link to EMLSR listening operation after the EMLSR transition delay time, and may wait for the reception of an initial control frame on the first link and / or the second link. The initial control frame is either a MU-RTS trigger frame 740 or a BSRP trigger frame.

[0076] AP 1-2 703 may preemptively perform a backoff operation to trigger the transmission of the UL PPDU, including retransmitted data 750, on the second link before the expected time when STA 1-2 713 is expected to operate in the listening operation (e.g., after the EMLSR transition delay time from the transmission completion time of BA frame 730 of AP 1-1 701), and may wait until the backoff counter reaches 0. Alternatively, AP 1-2 703 may repeatedly perform the backoff until the expected time when STA 1-2 713 is expected to operate in the listening operation (e.g., after the EMLSR transition delay time from the transmission completion time of BA frame 730 of AP 1-1 701). AP 1-2 703 may wait for the transmission of MU-RTS trigger frame 740 until after the EMLSR transition delay time from the transmission end time of BA frame 730 on the first link. AP 1-2 703 can send MU-RTS frame 740 (i.e., send an initial control frame) to STA 1-2 713 after the EMLSR conversion delay time from the end time of transmission on the first link of BA frame 730, allowing STA MLD 1 to perform normal transmit / receive operations on the second link (e.g., operations for retransmitting frames that have been erroneously transmitted). STA 1-2 713 can send CTS frame after a certain period of time (e.g., SIFS time) from the end time of transmission of MU-RTS frame 740. AP 1-2 703 can trigger a UL PPDU including retransmitted data 750 by sending a trigger frame to STA 1-2 713. STA 1-2 713 can send retransmitted data 750 indicated by trigger frame 740 to AP 1-2 703. AP 1-2 703 may send a BA frame after a certain period of time (e.g., SIFS time) following the end time of the transmission of the UL PPDU, which includes the retransmission data 750 sent by STA 1-2 713. When a recovered MPDU and / or MSDU is received, AP MLD may sequentially reorder the MPDUs and / or MSDUs waiting in the reordering buffer and forward them to the upper layer.

[0077] The following describes the implementation scheme of the error recovery procedure. The error recovery procedure is performed by the STA and AP. The STA and AP can be MLDs. In other words, the STA and AP can use multiple links to perform communication. For example, the STA and AP can use a first link and a second link to perform communication. Here, the first link and the second link can be an NSTR link pair. In other words, the STA and AP cannot simultaneously perform transmission and reception on the first link and the second link.

[0078] Figure 8A flowchart of an error recovery process according to one embodiment of the present invention is shown. Figure 8 It shows the AP (e.g., Figure 3 The process executed by AP MLD.

[0079] refer to Figure 8 In step S801, the AP receives multiple frames. The AP can use the first link to receive multiple frames (e.g., Figure 3 The UL PPDU 1 320. Multiple frames may include at least one Physical Layer Protocol Data Unit (PPDU), Media Access Control Layer Protocol Data Unit (MPDU), or Aggregated MPDU (A-MPDU). For example, multiple frames may be grouped and received as a single PPDU. Multiple frames may include at least one sequence number (SN) or traffic identifier (TID). Each frame may have the same TID, or alternatively, each frame may have a different TID. For example, at least some frames may have the same TID. At least some frames may have different TIDs. Each frame may have a priority for recovery. For example, each frame may have a TID-based priority, and when an error is detected, frames with higher priority may be recovered or retransmitted first. The AP records the received multiple frames in a reordering buffer and performs reordering based on SN, etc.

[0080] In step S803, the AP detects errors in multiple frames. Errors include cases where received frames are not decoded. The AP can detect errors based on the received frames. For example, the AP can detect errors based on the TID or SN included in the received frames. For example, in a reordering process, the AP can identify frames containing missing SNs that have not been correctly received and detect the errors.

[0081] In step S805, the AP sends a retransmission request. The AP can send a retransmission request to request the retransmission of the frame from which the error was detected. The retransmission request can be sent on either the first link or the second link. It can be sent on the trigger frame (e.g., Figure 3 Trigger frame 340), response frame (e.g., Figure 5 BA frame 530) or MU-RTS frame (e.g., Figure 7A retransmission request is sent in the MU-RTS trigger frame 740. When a retransmission request is sent on the second link, the transmission of the frame including the retransmission request can be completed (or terminated) simultaneously with the response frame sent on the first link. To complete the transmission simultaneously, the frame including the retransmission request may include padding. Alternatively, the response frame sent on the first link may include padding to complete the transmission simultaneously. The retransmission request may include at least one of the TID of the frame that detected the error, the SN of the frame that detected the error, the resource for retransmitting the frame that detected the error, or the AID of the STA that retransmitted the frame. To send the retransmission request, the AP may perform a channel access procedure. For example, the channel access procedure may be performed from the time when the error in the frame is detected. After the channel access procedure is completed, the AP may wait without sending a retransmission request. For example, the AP may send a retransmission request after the STA has completed the transmission of multiple frames. As another example, the AP may send a retransmission request after the STA has transmitted a frame and then switch to EMLSR listening mode. To send the retransmission request, the AP may acquire a TXOP on the second link.

[0082] In step S807, the AP receives the retransmission frame (e.g., Figure 3 (Retransmitted data 350). Retransmitted frames include frames in which errors are detected. For example, a retransmitted frame may include the frame in which an error is detected, as well as frames transmitted after the frame in which the error is detected. A first link or a second link may be used to receive retransmitted frames. The first link or the second link may be used to receive retransmitted frames depending on the type of frame that includes the retransmission request. For example, if the retransmission request is included in a trigger frame transmitted on the second link or a MU-RTS frame transmitted on the second link, the second link may be used to receive the retransmitted frame. As another example, if the retransmission request is included in a response frame transmitted on the first link, the first link may be used to receive the retransmitted frame.

[0083] Figure 9 A flowchart of an error recovery process according to one embodiment of the present invention is shown. Figure 9 It shows the result of STA (e.g., Figure 3 The process executed by STA MLD.

[0084] refer to Figure 9 In step S901, the STA sends multiple frames (e.g., Figure 3(UL PPDU 1 320). The STA can use the first link to send multiple frames. To send multiple frames, the STA can acquire a transmit opportunity (TXOP). Multiple frames include at least one Physical Layer Protocol Data Unit (PPDU), Media Access Control Layer Protocol Data Unit (MPDU), or Aggregated MPDU (A-MPDU). For example, multiple frames can be grouped and sent as a single PPDU. Multiple frames can include at least one Sequence Number (SN) or Flow Identifier (TID). Each frame can have the same TID; alternatively, they can have different TIDs. For example, at least some frames can have the same TID. At least some frames can have different TIDs. Each frame can have a priority for recovery. For example, each frame can have a TID-based priority, and when an error is detected, frames with higher priority can be recovered or retransmitted first. Multiple frames can be sent in SN order; alternatively, multiple frames can be sent regardless of SN order.

[0085] In step S903, the STA receives a retransmission request. The retransmission request can be received on either the first link or the second link. It can be received in the trigger frame (e.g., Figure 3 Trigger frame 340), response frame (e.g., Figure 5 BA frame 530) or MU-RTS frame (e.g., Figure 7 The retransmission request is received in the MU-RTS trigger frame 740. If a retransmission request is received on the second link, the reception of the frame including the retransmission request can be completed simultaneously with the response frame received on the first link. To complete the reception simultaneously, the frame including the retransmission request may include padding. The retransmission request may include at least one of the TID, SN, resource for retransmitting the frame that detected the error, or AID of the retransmission frame STA. The STA may receive the retransmission request after the transmission of multiple frames has been completed. As another example, the STA may receive the retransmission request after transmitting a frame and then switching to EMLSR listening mode. The retransmission request may include an indicator for extending the TXOP of the STA. If the retransmission request includes an indicator for extending the TXOP, the STA may extend the TXOP to transmit the retransmission frame.

[0086] In step S905, the STA sends a retransmission frame (e.g., Figure 3The retransmitted data (350). A retransmitted frame includes a frame in which an error was detected. For example, a retransmitted frame may include a frame in which an error was detected, as well as a frame sent after the frame in which the error was detected. A first link or a second link can be used to send the retransmitted frame. The first link or the second link can be used to send the retransmitted frame depending on the type of frame that includes the retransmission request. For example, if the retransmission request is included in a trigger frame sent on the second link or a MU-RTS frame sent on the second link, the second link can be used to send the retransmitted frame. As another example, if the retransmission request is included in a response frame sent on the first link, the first link can be used to send the retransmitted frame. To send retransmitted data, the STA can acquire a TXOP. The STA can acquire a TXOP on the link from which the retransmitted frame is sent.

[0087] The operation of the method according to an 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 can include all types of recording means for storing data readable by a computer system. Furthermore, the computer-readable recording medium can store and execute programs or code that can be distributed across computer systems connected via a network and read in a distributed manner by a computer.

[0088] Additionally, 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 code created by a compiler, but also high-level language code that can be executed by a computer using an interpreter.

[0089] Although the invention has been described above with reference to preferred embodiments thereof, those skilled in the art will understand that various modifications and variations may be made to the invention without departing from the scope and spirit of the invention as defined by the appended claims.

[0090] Industrial applicability This invention can be applied to devices and recording media in wireless local area network systems.

Claims

1. A method for operating an access point (AP) in a wireless local area network system, comprising: Receive multiple frames from the slave station (STA); Detect errors in at least one of multiple frames; Based on the detected erroneous frame, a retransmission request is sent; as well as Based on the retransmission request, receive the retransmission frame. The retransmission frames include frames in which errors were detected, and Specifically, retransmission frames are received on the link where a retransmission request has been sent.

2. The method according to claim 1, wherein, The retransmission request includes at least one of the TID of the frame in which the error was detected, the SN of the frame in which the error was detected, the resource for sending the retransmission frame, or the AID of the STA.

3. The method according to claim 1, wherein, Use response frames, trigger frames, or MU-RTS frames to send retransmission requests.

4. The method according to claim 3, wherein, When a trigger frame is used to send a retransmission request, the trigger frame and the response frame are sent simultaneously.

5. The method according to claim 4, wherein, The trigger frame includes padding to facilitate simultaneous transmission with the response frame.

6. The method of claim 1, further comprising performing a channel access procedure for sending a retransmission request. in, A retransmission request is sent after the channel access process and the reception of multiple frames are completed.

7. The method according to claim 6, wherein, A retransmission request is sent after the STA has switched to listening mode.

8. The method according to claim 1, in, Each of the multiple frames includes a priority, and Among them, retransmission frames are received based on the priority.

9. A method for using an operator station (STA) in a wireless local area network system, comprising: Send multiple frames to the access point (AP); Based on the frames from which errors are detected, a retransmission request is received. as well as Based on the retransmission request, a retransmission frame is sent. The retransmission frames include frames in which errors were detected, and Specifically, a retransmission frame is sent on the link that receives the retransmission request.

10. The method according to claim 9, wherein, The retransmission request includes at least one of the TID of the frame in which the error was detected, the SN of the frame in which the error was detected, the resource for sending the retransmission frame, or the AID of the STA.

11. The method according to claim 9, wherein, Use response frames, trigger frames, or MU-RTS frames to receive retransmission requests.

12. The method according to claim 11, wherein, When a trigger frame is used to receive a retransmission request, the trigger frame and the response frame are received simultaneously.

13. The method according to claim 12, wherein, The trigger frame or response frame includes padding to facilitate simultaneous reception with the response frame or trigger frame.

14. The method according to claim 9, wherein, Receive retransmission requests after multiple frames have been sent.

15. The method of claim 14, further comprising switching to a listening mode after receiving a response frame for a plurality of frames. in, After the time allotted for switching to listening mode has elapsed, a retransmission request is received.

16. The method according to claim 9, in, Each of the multiple frames includes a priority, and Among them, retransmission frames are sent based on the priority.

17. An access point (AP) in a wireless local area network system, comprising: transceiver; and The processor, which is connected to the transceiver, The processor is configured as follows: Receive multiple frames from the slave station (STA); Detect errors in at least one of multiple frames; Based on the detected erroneous frame, a retransmission request is sent; and Based on the retransmission request, receive the retransmission frame. The retransmission frames include frames in which errors were detected, and Specifically, retransmission frames are received on the link where a retransmission request has been sent.

18. A station (STA) in a wireless local area network system, comprising: transceiver; and The processor, which is connected to the transceiver, The processor is configured as follows: Send multiple frames to the access point (AP); Based on the detected erroneous frames among multiple frames, a retransmission request is received; and Based on the retransmission request, a retransmission frame is sent. The retransmission frames include frames in which errors were detected, and Specifically, a retransmission frame is sent on the link that receives the retransmission request.

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