Medium access method and device in multi-link synchronous transmission

Abstract

The invention discloses a method and a device for medium access in multi-link synchronous transmission. The method of STA MLD comprises the steps of: performing a first backoff operation in a first link; if the first back-off operation is completed, keeping a back-off counter value of the first back-off operation for multi-link synchronous transmission in the first link and the second link as 0; performing a second backoff operation in the second link; and if the second backoff operation is completed, performing multi-link synchronous transmission in the first link and the second link.

Description

Technical Field

[0001] The present invention relates to a wireless local area network (WLAN) communication technology, and more specifically, to a technology for accessing a medium in multi-link synchronous transmission. 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 access the Internet in a wireless manner based on wireless communication technology.

[0003] The standards utilizing wireless LAN technology are mainly developed as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. As the above wireless LAN technology has been developed and widely adopted, applications utilizing wireless LAN technology have been diversified, and there has been a demand for wireless LAN technology supporting higher throughput.

[0004] With the emergence of applications that require higher throughput and applications that require real-time transmission, wireless LANs can support communications using expanded frequency bandwidth and efficient retransmission operations. In addition, wireless LANs can support operations that use multiple channels or multiple links at the same time. In other words, wireless LANs can support multi-link transmission. In this case, methods that support efficient multi-link transmission may be needed.

[0005] 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

[0006] Technical issues

[0007] The present invention is dedicated to providing a method and device for accessing a medium in multi-link synchronous transmission.

[0008] Technical Solution

[0009] According to an exemplary embodiment of the present invention, a method of a station (STA) multi-link device (MLD) for achieving the above-mentioned purpose may include: performing a first backoff operation on a first link; in response to completion of the first backoff operation, maintaining a backoff counter value for the first backoff operation at 0 for multi-link synchronous transmission on the first link and the second link; performing a second backoff operation on the second link; and in response to completion of the second backoff operation, performing multi-link synchronous transmission on the first link and the second link, wherein, when performing multi-link synchronous transmission, a transmission start time of a first frame on the first link may be equal to a transmission start time of a second frame on the second link.

[0010] When the second backoff operation is completed and the channel state of the first link is in an idle state, multi-link synchronous transmission may be performed; when the second backoff operation is completed and the channel state of the first link is in a busy state, multi-link synchronous transmission may not be performed.

[0011] The STA MLD may be a non-simultaneous transmit and receive (NSTR) STA MLD that is incapable of STR operation, and the first link and the second link may be NSTR links.

[0012] When a first channel access parameter configured for a first backoff operation is different from a second channel access parameter configured for a second backoff operation, the first backoff operation and the second backoff operation for multi-link synchronous transmission may be performed using the same channel access parameter, and the same channel access parameter may be the first channel access parameter or the second channel access parameter, and the same channel access parameter may include at least one of a contention window (CW) for each access category (AC) or a quality of service (QoS) short frame retry counter (QSRC) for each AC.

[0013] When a first backoff operation for each of a plurality of data units having a different AC is completed on a first link, multi-link synchronous transmission for a first data unit among the plurality of data units may be performed.

[0014] The method may further include: performing a third backoff operation on a second data unit among the plurality of data units on the first link; and transmitting the second data unit on the first link in response to the third backoff operation being successful.

[0015] The third backoff operation may be performed after the time when the channel state of the first link transitions from an idle state to a busy state, after the time when the channel state of the first link transitions from a busy state to an idle state, or after a predefined time from the time when the channel state of the first link is detected as a busy state.

[0016] The first channel access parameter for the first backoff operation on the first link may be equal to the third channel access parameter for the third backoff operation on the first link.

[0017] The first channel access parameter for the first backoff operation on the first link may be different from the third channel access parameter for the third backoff operation on the first link, and the CW in the third backoff parameter may be n times or 1 / n of the CW in the first backoff parameter, where n is a natural number.

[0018] The first channel access parameter for the first backoff operation on the first link may be different from the third channel access parameter for the third backoff operation on the first link, and the QSRC in the third backoff parameter may be greater or less than the QSRC in the first backoff parameter by m, where m is a natural number.

[0019] According to an exemplary embodiment of the present invention, a station (STA) multi-link device (MLD) for achieving the above-mentioned purpose may include at least one processor, wherein the at least one processor enables the STA MLD to perform: performing a first backoff operation on a first link; in response to completion of the first backoff operation, maintaining a backoff counter value for the first backoff operation at 0 for multi-link synchronous transmission on the first link and the second link; performing a second backoff operation on the second link; and in response to completion of the second backoff operation, performing multi-link synchronous transmission on the first link and the second link, wherein, when performing multi-link synchronous transmission, a transmission start time of a first frame on the first link may be equal to a transmission start time of a second frame on the second link.

[0020] When the second backoff operation is completed and the channel state of the first link is in an idle state, multi-link synchronous transmission may be performed; when the second backoff operation is completed and the channel state of the first link is in a busy state, multi-link synchronous transmission may not be performed.

[0021] The STAMLD may be a non-simultaneous transmit and receive (NSTR) STA MLD incapable of STR operation, and the first link and the second link may be NSTR links.

[0022] When a first channel access parameter configured for a first backoff operation is different from a second channel access parameter configured for a second backoff operation, the first backoff operation and the second backoff operation for multi-link synchronous transmission may be performed using the same channel access parameter, and the same channel access parameter may be the first channel access parameter or the second channel access parameter, and the same channel access parameter may include at least one of a contention window (CW) for each access category (AC) or a quality of service (QoS) short frame retry counter (QSRC) for each AC.

[0023] When a first backoff operation for each of a plurality of data units having a different AC is completed on a first link, multi-link synchronous transmission for a first data unit among the plurality of data units may be performed.

[0024] The at least one processor may further cause the STA MLD to: perform a third backoff operation on a second data unit among the plurality of data units on the first link; and transmit the second data unit on the first link in response to success of the third backoff operation.

[0025] The third backoff operation may be performed after the time when the channel state of the first link transitions from an idle state to a busy state, after the time when the channel state of the first link transitions from a busy state to an idle state, or after a predefined time from the time when the channel state of the first link is detected as a busy state.

[0026] The first channel access parameter for the first backoff operation on the first link may be equal to the third channel access parameter for the third backoff operation on the first link.

[0027] The first channel access parameter for the first backoff operation on the first link may be different from the third channel access parameter for the third backoff operation on the first link, and the CW in the third backoff parameter may be n times or 1 / n of the CW in the first backoff parameter, where n is a natural number.

[0028] The first channel access parameter for the first backoff operation on the first link may be different from the third channel access parameter for the third backoff operation on the first link, and the QSRC in the third backoff parameter may be greater or less than the QSRC in the first backoff parameter by m, where m is a natural number.

[0029] Beneficial Effects

[0030] According to the present invention, a communication node in a wireless local area network can perform multi-link synchronous transmission. The communication node may include a STA, a STAMLD, an AP and / or an AP MLD. When multi-link synchronous transmission is supported, the start time (e.g., the transmission start time) of frames on multiple links may be synchronized. Depending on the change in channel state, multi-link synchronous transmission may be impossible. If multi-link synchronous transmission is not possible, a backoff operation may be performed to prevent conflicts between communication nodes and / or internal conflicts within a communication node. In this case, conflicts in multi-link synchronous transmission may be avoided, and multi-link synchronous transmission may be reliably performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a block diagram showing a first exemplary embodiment of a communication node constituting a wireless LAN system.

[0032] Figure 2 is a conceptual diagram showing a first exemplary embodiment of multi-links configured between multi-link devices (MLDs).

[0033] Figure 3a is a timing diagram showing a first exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible.

[0034] Figure 3b is a timing diagram showing a second exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible.

[0035] Figure 4a is a timing diagram showing a third exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible.

[0036] Figure 4b is a timing diagram showing a fourth exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible.

[0037] Figure 5 is a timing diagram showing a fifth exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible.

[0038] Figure 6 is a timing diagram illustrating a first exemplary embodiment of a method for determining parameters of a channel access operation in multi-link synchronous transmission. DETAILED DESCRIPTION

[0039] Since the present invention can be modified in various ways and has various forms, specific exemplary embodiments will be shown in the drawings and described in detail in the specific embodiments. However, it should be understood that it is not intended to limit the present invention to specific exemplary embodiments, but on the contrary, the present invention covers all modifications and alternative forms that fall within the spirit and scope of the present invention.

[0040] 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, the first component can be named as the second component, and the second component can also be similarly named as the first component. The term "and / or" refers to any one or a combination of multiple related and described matters.

[0041] 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".

[0042] When it is mentioned that a certain component is "coupled" or "connected" to another component, it should be understood that the certain component is directly "coupled" or "connected" to the other component, or another component may be provided therebetween. Conversely, when it is mentioned that a certain component is "directly coupled" or "directly connected" to another component, it will be understood that no other component is provided therebetween.

[0043] 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 stipulates 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.

[0044] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as those generally understood by ordinary technicians in the field to which the present invention belongs. Terms commonly used in dictionaries and already in dictionaries should be interpreted as having meanings that match the contextual meanings in the field. In this specification, unless explicitly defined, terms are not necessarily interpreted as having formal meanings.

[0045] Hereinafter, the form of the present invention will be described in detail with reference to the accompanying 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 accompanying drawings, and repeated description thereof will be omitted.

[0046] Hereinafter, a wireless communication system to which an exemplary embodiment according to the present invention is applied will be described. The wireless communication system to which an exemplary embodiment according to the present invention is applied is not limited to the contents described below, and the exemplary embodiment according to the present invention can be applied to various wireless communication systems. The wireless communication system can be referred to as a "wireless communication network".

[0047] In an exemplary embodiment, "configuration of an operation (e.g., a transmission operation)" may mean signaling "configuration information of an operation (e.g., an information element, a parameter)" and / or "information indicating that an operation is to be performed". "Configuration of an information element (e.g., a parameter)" may mean signaling an information element. "Configuration of a resource (e.g., a resource region)" may mean signaling setting information of a resource. The transmission time of a frame may refer to a transmission start time or a transmission end time, and the reception time of a frame may refer to a reception start time or a reception end time. The transmission time may be interpreted as corresponding to the reception time. A time point may be interpreted as a time, and a time may be interpreted as a time point.

[0048] Figure 1 is a block diagram showing a first exemplary embodiment of a communication node constituting a wireless LAN system.

[0049] like Figure 1 As shown in , the communication node 100 may be an access point, a station (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 the AP may be 20 megahertz (MHz), 80 MHz, 160 MHz, etc. The operating channel width supported by the STA may be 20 MHz, 80 MHz, etc.

[0050] The communication node 100 may include at least one processor 110, a memory 120, and a transceiver 130 connected to a network to perform 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.

[0051] 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.

[0052] 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. The memory 120 and the storage device 160 may each 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).

[0053] Figure 2 is a conceptual diagram showing a first exemplary embodiment of multi-links configured between multi-link devices (MLDs).

[0054] like Figure 2As shown in , the MLD may have a Medium 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. The AP associated with the AP MLD may have a different MAC address, and the station associated with the non-AP MLD may have a different MAC address. Each of the APs with different MAC addresses within the AP MLD may be responsible for each link and may perform the role of an independent AP.

[0055] Each of the STAs having different MAC addresses within the non-AP MLD may be responsible for each link and may perform the role of an independent STA. The non-AP MLD may be referred to as a STA MLD. The 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 a STR MLD (e.g., STR AP MLD, STR non-AP MLD). In an exemplary embodiment, a link may mean 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).

[0056] MLD can send and receive frames in multiple links by utilizing a non-contiguous bandwidth extension scheme (e.g., 80MHz+80MHz). Multi-link operation can include multi-band transmission. AP MLD can include multiple APs, and the multiple APs can operate in different links. Each of the multiple APs can perform the functions of the lower MAC layer. Each of the multiple APs can be referred to as a "communication node" or a "lower-level entity". The communication node (i.e., AP) can be in the upper layer (or Figure 1 The non-AP MLD 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-level entity". The communication node (i.e., STA) may be in the upper layer (or Figure 1 The system operates under the control of the processor 110 shown in FIG.

[0057] MLD can perform communication in multiple frequency bands (i.e., multi-band). For example, MLD can perform communication using 80MHz bandwidth in the 2.4GHz band according to a channel extension scheme (e.g., bandwidth extension scheme), and perform communication using 160MHz bandwidth in the 5GHz band according to a channel extension scheme. MLD can perform communication using 160MHz bandwidth in the 5GHz band, and can perform communication using 160MHz bandwidth in the 6GHz band. A frequency band (e.g., a channel) utilized by MLD can be defined as a link. Alternatively, multiple links can be configured in a frequency band utilized 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.

[0058] MLD (e.g., AP MLD and / or non-AP MLD) may configure multi-link by performing an access procedure and / or a negotiation procedure for multi-link operation. In this case, the number of links and / or links utilized 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 for 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.

[0059] The MLD is able to perform STR operations when the frequency band spacing between multiple links (for example, the frequency band spacing between link 1 and link 2 in the frequency domain) is sufficient. For example, the MLD can use link 1 among the multiple links to send physical (PHY) layer protocol data unit (PPDU) 1, and can use link 2 among the multiple links to receive PPDU 2. On the other hand, if the MLD performs STR operations when the frequency band spacing between multiple links is insufficient, in-device coexistence (IDC) interference, that is, interference between multiple links, will occur. Therefore, when the bandwidth spacing between multiple links is insufficient, the MLD may not be able to perform STR operations. The link pair with the above-mentioned interference relationship may be a non-simultaneous transmit and receive (NSTR) limited link pair. Here, the MLD may be referred to as an "NSTR AP MLD" or an "NSTR non-AP MLD".

[0060] 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 interval 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 may receive a frame using link 3. When the frequency band interval 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 interval 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.

[0061] On the other hand, in a wireless local area network system, a negotiation process for multi-link operation can be performed during the access process between a station and an access point. A device (e.g., access point, station) that supports multiple links can be referred to as a "multi-link device (MLD)". An access point that supports multiple links can be referred to as an "AP MLD", and a station that supports multiple links can be referred to as a "non-AP MLD" or "STAMLD". AP MLD can have a physical address (e.g., MAC address) for each link. AP MLD can be implemented as if the AP responsible for each link exists alone. Multiple APs can be managed within one AP MLD. Therefore, collaboration between multiple APs belonging to the same AP MLD is possible. STA MLD can have a physical address (e.g., MAC address) for each link. STA MLD can be implemented as if the STA responsible for each link exists alone. Multiple STAs can be managed within one STA MLD. Therefore, collaboration between multiple STAs belonging to the same STA MLD is possible.

[0062] For example, AP 1 of AP MLD and STA 1 of STA MLD may each be responsible for a first link and may communicate using the first link. AP 2 of AP MLD and STA 2 of STA MLD may each be responsible for a second link and may communicate using the second link. STA 2 may receive state change information of 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 operations performed by STA 1 based on the collected information.

[0063] 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.

[0064] In the present invention, 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 STAMLD may refer to the STA associated with the STA MLD, and the AP of AP MLD may refer to the AP associated with the AP MLD. When the STA MLD 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 STAMLD on the second link may be interpreted as the operation of the second STA. When the 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.

[0065] A communication node (e.g., an AP, an AP MLD, a STA, or a STA MLD) may perform multi-link synchronous transmission. In multi-link synchronous transmission, a transmission operation may be performed on multiple links, and the start time of the transmission operation on the multiple links may be synchronized. In addition, the end time of the transmission operation on the multiple links may be synchronized. In other words, when performing multi-link synchronous transmission, at least one of the start time or the end time of the transmission operation on the multiple links may be synchronized.

[0066] Figure 3a is a timing diagram showing a first exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible, Figure 3b is a timing diagram showing a second exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible.

[0067] like Figure 3a and Figure 3b As shown, AP MLD 1, STA MLD 1, STAMLD 2, and STA MLD 3 may operate on a first link and a second link. AP MLD 1 may be a simultaneous transmit and receive (STR) AP MLD capable of performing STR operations. Each of STAMLD 1, STA MLD 2, and STA MLD 3 may be a non-STR (NSTR) STA MLD that is not capable of performing STR operations. The first link and the second link may be an NSTR link pair for each of the STA MLDs.

[0068] A STA associated with STA MLD N operating on link X may be referred to as STA N-X. An AP associated with AP MLD N operating on link X may be referred to as AP NX. Each of X and N may be a natural number. For example, an AP associated with AP MLD 1 operating on a first link may be referred to as AP 1-1, and an AP associated with AP MLD 1 operating on a second link may be referred to as AP 1-2. A STA associated with STA MLD 1 operating on a first link may be referred to as STA 1-1, and a STA associated with STA MLD 1 operating on a second link may be referred to as STA 1-2.

[0069] The STA associated with the STAMLD may perform a backoff operation to perform multi-link synchronous transmission on the first link and the second link. When the backoff operation is successfully completed on all multiple links (e.g., the first link and the second link), the multi-link synchronous transmission may be performed. Multi-link synchronous transmission may mean transmitting frames at the same start time on multiple links. In multi-link synchronous transmission, the difference between the start times of the frames may be within a predetermined time (e.g., aRxTxTurnAroundTime). aRxTxTurnAroundTime may be 4μs. The backoff operation may refer to an enhanced distributed channel access function (EDCAF) backoff operation for each access category (AC). In the present invention, the EDCAF backoff operation for each AC may be referred to as an "AC EDCAF backoff operation". In the present invention, the backoff operation may be interpreted as an AC EDCAF backoff operation based on the context. When EDCA backoff is called, the AC EDCAF backoff operation may start. In other words, when EDCA backoff is called, the AC EDCAF backoff operation may be performed. The backoff counter required for the backoff operation may be an EDCA backoff counter maintained by the EDCAF for each AC. The backoff counter for the AC EDCAF backoff operation may be referred to as an EDCAF backoff counter or an EDCA backoff counter. Each of the STA MLDs may perform multiple AC EDCAF backoff operations. Each of the STAMLDs may perform AC EDCAF backoff operations for the same AC and / or different ACs.

[0070] STAN-2 of STAMLD N may perform a backoff operation on the second link and may complete the backoff operation. Completion of the backoff operation may indicate the success of the backoff operation. When the backoff counter value is 0, the backoff operation associated with the backoff counter value may be completed. STA N-2 of STAMLD N operating on the second link may wait for STAN-1 of STA MLD N operating on the first link to obtain a transmission opportunity (TXOP) (e.g., EDCA TXOP). In the present invention, TXOP may refer to EDCA TXOP. TXOP may be obtained at a time slot (e.g., a time slot boundary) where the EDCAF backoff counter of the STA reaches 0. Acquiring a TXOP (e.g., EDCA TXOP) by a STA may mean acquiring a TXOP (e.g., EDCA TXOP) by the EDCAF of each AC.

[0071] exist Figure 3a In an exemplary embodiment of , STA1-2, STA2-2 and / or STA 3-2 may perform a backoff operation on the second link. When the backoff operation is completed (e.g., the backoff operation is successful), the backoff counter value for the backoff operation may be 0. The backoff counter value of STA1-2, STA2-2 and / or STA 3-2 may be maintained at 0 to perform multi-link synchronous transmission on the first link and the second link. On the first link, STA 1-1 of STA MLD 1 may acquire a TXOP. Frames may be transmitted within a TXOP. In the present invention, a frame may refer to a physical layer protocol data unit (PPDU), a MAC layer protocol data unit (MPDU) and / or an aggregate (A)-MPDU.

[0072] When STA 1-1 of STA MLD 1 acquires a TXOP on the first link and the backoff counter value of STA 1-2 of STA MLD 1 on the second link is 0, STA 1-1 and STA 1-2 associated with STA MLD 1 may perform multi-link synchronous transmission. In this case, the start time of frame transmission of STA 1-1 may be the same as the start time of frame transmission of STA 1-2. In other words, the start time of frame transmission of STA 1-1 may be synchronized with the start time of frame transmission of STA 1-2.

[0073] When the backoff operation of each of STA1-2, STA2-2, and STA 3-2 is completed on the second link, and STA1-2 transmits a frame, STA2-2 and STA3-2 may not transmit a frame on the second link. In other words, since STA 1-2 transmits a frame on the second link, each of STA2-2 and STA 3-2 may determine that the channel state (e.g., medium state) of the second link is a busy state, and frames cannot be transmitted on the second link in the busy state. When the channel state (e.g., medium state) of the second link changes from a busy state to an idle state, each of STA 2-2 and STA 3-2 may wait for an arbitration interframe space (AIFS) for each AC.

[0074] When STA 2-2 and STA 3-2 perform transmission based on the backoff counter value from the previously completed backoff operation (e.g., the backoff counter value maintained at 0), a transmission conflict may occur between STA 2-2 and STA 3-2. In order to prevent the transmission conflict, STA 2-2 and STA 3-2 may perform a new backoff operation (e.g., an AC EDCAF backoff operation or an EDCAF backoff operation). In other words, the backoff operation may be called again at STA 2-2 and STA 3-2. The time of calling the backoff operation may be after (e.g., immediately after) the time when the medium state transitions from the idle state to the busy state. Alternatively, the time of calling the backoff operation may be after (e.g., immediately after) the time when the medium state transitions from the busy state to the idle state. Alternatively, the time of calling the backoff operation may be after a predetermined time (e.g., a predefined time) from the time when the medium state is detected as the busy state.

[0075] The call of the backoff operation may indicate the operation of selecting a backoff counter value and the operation of decrementing the backoff counter value based on the channel condition (e.g., idle state or busy state). Accordingly, STA 2-2 and STA 3-2 may have a new backoff counter value for EDCAF. STA2-2 and STA3-2 may select a new backoff counter value using the existing CW[AC] and / or QSRC[AC] of the EDCAF for each AC. In other words, in order to select a new backoff counter value, the same CW[AC] and / or QSRC[AC used in the previous backoff operation may be used. CW[AC] and / or QSRC[AC] may be a backoff parameter (e.g., a channel access parameter or an EDCA parameter). In other words, the backoff parameter (e.g., a channel access parameter or an EDCA parameter) may include CW[AC] and / or QSRC[AC]. CW[AC] may refer to a CW for each AC. QSRC[AC] may refer to a QSRC for each AC. CW may refer to a contention window, and QSRC may refer to a quality of service (QoS) short frame retry counter.

[0076] As another method, in order to select a new backoff counter value, an increased CW[AC] and / or an increased QSRC[AC] may be used. For example, the CW[AC] of the EDCAF for each AC may be increased by n times, and the QSRC[AC] of the EDCAF for each AC may be increased by m. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. Each of STA 2-2 and STA 3-2 may select a new backoff counter value using an increased CW[AC] and / or an increased QSRC[AC]. Alternatively, in order to select a new backoff counter value, a decreased CW[AC] and / or a decreased QSRC[AC] may be used. For example, the decreased CW[AC] may be 1 / n of the existing CW[AC], and the decreased QSRC[AC] may be m less than the existing QSRC[AC]. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. Each of STA2-2 and STA3-2 may select a new backoff counter value using the reduced CW[AC] and / or the reduced QSRC[AC]. Alternatively, in order to select a new backoff counter value, an initial value of CW[AC] and / or an initial value of QSRC[AC] may be used. Each of the initial value of CW[AC] and the initial value of QSRC[AC] may be a predefined value or a value indicated by each AP associated with the AP MLD.

[0077] On the other hand, STA1-1 may perform a backoff operation after transmitting a frame. In other words, a backoff operation may be invoked at STA1-1 that has previously transmitted a frame. If the transmission of the previous frame was successful, STA1-1 may select a backoff counter value (e.g., a new backoff counter value) using the initial value of CW[AC] and / or the initial value of QSRC[AC]. If the transmission of the previous frame failed, STA1-1 may select a backoff counter value (e.g., a new backoff counter value) using an increased CW[AC] and / or an increased QSRC[AC].

[0078] The STAs of the STA MLD may perform a backoff operation using a backoff counter value selected according to the EDCAF for the corresponding AC to obtain a TXOP (eg, EDCA TXOP) on the second link. The STAs of the STA MLD may transmit frames (eg, data frames) within the TXOP on the second link.

[0079] exist Figure 3b In an exemplary embodiment of, STA 1-2, STA2-2 and / or STA 3-2 may perform a backoff operation on the second link. When the backoff operation is completed (e.g., the backoff operation is successful), the backoff counter value for the backoff operation may be 0. The backoff counter value of STA 1-2, STA 2-2 and / or STA3-2 may remain at 0 to perform multi-link synchronous transmission on the first link and the second link. When the backoff counter value remains at 0 on the second link, if another communication node transmits a frame, the medium state (e.g., channel state) of the second link may be detected as a busy state. STA1-2, STA2-2 and / or STA3-2 may not be able to decode a frame transmitted by another communication node. In other words, STA1-2, STA2 and / or STA3-2 may detect the energy of a frame transmitted by another communication node, but cannot decode the header of the frame.

[0080] When the backoff operation is successful on the first link and the channel state of the second link is an idle state, multi-link synchronous transmission may be performed on the first link and the second link. When the backoff operation is successful on the first link and the channel state of the second link is a busy state, multi-link synchronous transmission may not be performed on the first link and the second link. In this case, frame transmission may be performed on the first link, but frame transmission may not be performed on the second link.

[0081] When the channel state (e.g., medium state) of the second link transitions from a busy state to an idle state, STA 1-2 and STA2-2 and / or STA 3-2 may wait for an extended interframe space (EIFS) for each AC. The EIFS for each AC may be defined as "EIFS-distributed coordination function (DCF) interframe space (DCF interframe space, DIFS) + AIFS [AC]". If STA 1-2, STA 2-2 and / or STA 3-2 perform transmission based on a backoff counter value (e.g., a backoff counter value maintained at 0) according to a previously successful backoff operation, a transmission conflict may occur in the STA. Accordingly, STA1-2, STA2-2 and / or STA 3-2 may perform a new backoff operation (e.g., an AC EDCAF backoff operation or an EDCAF backoff operation). In other words, the backoff operation may be called again at STA 1-2, STA 2-2 and / or STA 3-2. The time of invoking the backoff operation may be after (e.g., immediately after) the medium state transitions from the idle state to the busy state. Alternatively, the time of invoking the backoff operation may be after (e.g., immediately after) the medium state transitions from the busy state to the idle state. Alternatively, the time of invoking the backoff operation may be after a predetermined time (e.g., a preconfigured time) from the time when the medium state is detected as the busy state. Accordingly, STA 1-2, STA2-2, and / or STA 3-2 may have a new backoff counter value for EDCAF. STA1-2, STA2-2, and / or STA3-2 may select a new backoff counter value using the existing CW[AC] and / or QSRC[AC] of the EDCAF for each AC. In other words, in order to select a new backoff counter value, the same CW[AC] and / or QSRC[AC] used in the previous backoff operation may be utilized.

[0082] As another method, in order to select a new backoff counter value, an increased CW[AC] and / or an increased QSRC[AC] may be used. For example, the CW[AC] of the EDCAF for each AC may be increased by n times, and the QSRC[AC] of the EDCAF for each AC may be increased by m. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. Each of STA 1-2, STA 2-2, and / or STA 3-2 may select a new backoff counter value using an increased CW[AC] and / or an increased QSRC[AC]. Alternatively, in order to select a new backoff counter value, a decreased CW[AC] and / or a decreased QSRC[AC] may be used. For example, the decreased CW[AC] may be 1 / n of the existing CW[AC], and the decreased QSRC[AC] may be m less than the existing QSRC[AC]. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. Each of STA 1-2, STA 2-2, and / or STA 3-2 may select a new backoff counter value using the reduced CW[AC] and / or the reduced QSRC[AC]. Alternatively, in order to select a new backoff counter value, an initial value of CW[AC] and / or an initial value of QSRC[AC] may be used. Each of the initial value of CW[AC] and the initial value of QSRC[AC] may be a predefined value or a value indicated by each AP associated with the AP MLD.

[0083] The STA of STA MLD may perform a backoff operation using a backoff counter value selected according to the EDCAF for the corresponding AC to obtain a TXOP (eg, EDCAT TXOP) on the second link. The STA of STAMLD may transmit a frame (eg, a data frame) within the TXOP on the second link.

[0084] Figure 4a is a timing diagram showing a third exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible, Figure 4b is a timing diagram showing a fourth exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible.

[0085] like Figure 4a and Figure 4bAs shown, AP MLD 1 can operate on the first link and the second link. The STA associated with STAMLD N operating on link X can be called STAN-X. The AP associated with AP MLD N operating on link X can be called AP NX. Each of X and N can be a natural number. STA MLD 1 can operate on the first link and the second link. The first link and the second link can be an NSTR link pair for STA MLD 1. The AP associated with AP MLD 1 operating on the first link can be called AP 1-1, and the AP associated with AP MLD 1 operating on the second link can be called AP1-2. The STA associated with STAMLD 1 operating on the first link can be called STA1-1, and the STA associated with STA MLD 1 operating on the second link can be called STA 1-2.

[0086] The STA associated with STA MLD 1 may perform a backoff operation to perform multi-link synchronous transmission on the first link and the second link. Multi-link synchronous transmission may mean transmitting frames at the same start time on multiple links. In multi-link synchronous transmission, the difference between the start times of the frames may be within a specific time (e.g., aRxTxTurnAroundTime). aRxTxTurnAroundTime may be 4μs. The backoff operation may refer to an EDCAF backoff operation for each AC. When EDCA backoff is called, a backoff operation (e.g., an AC EDCAF backoff operation) may start. In other words, when EDCA backoff is called, a backoff operation may be performed. The backoff counter required for the backoff operation may be an EDCA backoff counter maintained by the EDCAF for each AC.

[0087] STA1-2 may perform a backoff operation for each AC on the second link, and the backoff operation for each AC may be completed. For multi-link synchronous transmission between STA1-1 and STA1-2, STA1-2 may wait for STA1-1 to acquire a TXOP (e.g., EDCA TXOP) on the first link while maintaining the backoff counter value on the second link at 0. A TXOP may be acquired at a time slot (e.g., a time slot boundary) at which the EDCAF backoff counter of the STA reaches 0. Acquiring a TXOP (e.g., EDCA TXOP) by the STA may mean acquiring a TXOP (e.g., EDCA TXOP) by the EDCAF of each AC.

[0088] exist Figure 4aIn an exemplary embodiment of , STA 1-1 of STA MLD 1 may acquire a TXOP on a first link, and may transmit a frame (e.g., PPDU, MPDU, and / or A-MPDU) within the TXOP. When STA 1-1 of STA MLD 1 acquires a TXOP on a first link, STA 1-2 may select an AC_XX (e.g., AC_BE) of an EDCAF whose backoff counter value remains at 0, and perform multi-link synchronous transmission for a frame including data (e.g., data unit, packet) for the selected AC_BE. In other words, multi-link synchronous transmission of a frame for STA 1-1 on the first link and a frame for STA 1-2 on the second link may be performed. A frame including data for AC_BE may be referred to as an AC_BE frame.

[0089] Although the backoff operation for AC_VO data (e.g., data for AC_VO) and AC_VI data (e.g., data for AC_VI) has been completed on the second link, due to the transmission of the AC_BE frame, the transmission of AC_VO data and AC_VI data may not be performed. In this case, after the medium state of the second link transitions from the busy state to the idle state, the STA may wait for the AIFS for each AC to perform data transmission. The length of the AIFS may be changed by the AC. Alternatively, the length of the AIFS for AC may be the same. For example, the length of the AIFS for AC_VO and the length of the AIFS for AC_VI may be the same. Since the length of the AIFS for AC_VO and the length of the AIFS for AC_VI are the same, if the transmission of AC_VO data and AC_VI data starts when the backoff counter value remains at 0, frame transmission may not be performed, and an internal conflict may occur. If an internal conflict occurs, the backoff operation (e.g., EDCA backoff operation) for AC_VO EDCAF and AC_VI EDCAF may be called again.

[0090] As another method, the backoff operation of the EDCAF for the AC with the same AIFS may be called when the backoff counter value remains at 0. The time of calling the backoff operation may be after (e.g., immediately after) the medium state transitions from the idle state to the busy state. Alternatively, the time of calling the backoff operation may be after (e.g., immediately after) the medium state transitions from the busy state to the idle state. Alternatively, the time of calling the backoff operation may be after a predetermined time from the time when the medium state is detected as the busy state. Accordingly, STA 1-2 may select new backoff values ​​for AC_VO EDCAF and AC_VI EDCAF.

[0091] STA 1-2 may select a new backoff counter value using the existing CW[AC] and / or QSRC[AC] of the EDCAF for each AC. In other words, in order to select a new backoff counter value, the same CW[AC] and / or QSRC[AC used in the previous backoff operation may be used. As another method, in order to select a new backoff counter value, STA 1-2 may use an increased CW[AC] and / or an increased QSRC[AC]. For example, the CW[AC] of the EDCAF for each AC may be increased by n times, and the QSRC[AC] of the EDCAF for each AC may be increased by m. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. STA 1-2 may select a new backoff counter value using an increased CW[AC] and / or an increased QSRC[AC].

[0092] Alternatively, in order to select a new backoff counter value, a reduced CW[AC] and / or a reduced QSRC[AC] may be used. For example, the reduced CW[AC] may be 1 / n of the existing CW[AC], and the reduced QSRC[AC] may be m less than the existing QSRC[AC]. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. STA 1-2 may select a new backoff counter value using the reduced CW[AC] and / or the reduced QSRC[AC]. Alternatively, in order to select a new backoff counter value, an initial value of CW[AC] and / or an initial value of QSRC[AC] may be used. Each of the initial value of CW[AC] and the initial value of QSRC[AC] may be a predefined value, or a value indicated by each AP associated with the AP MLD.

[0093] On the other hand, STA 1-1 may perform a backoff operation after transmitting a frame. In other words, a backoff operation for AC_BE may be called at STA 1-1 that has previously transmitted a frame. If the transmission of the previous frame was successful, STA 1-1 may select a backoff counter value (e.g., a new backoff counter value) for AC_BE using an initial value of CW[AC] and / or an initial value of QSRC[AC]. If the transmission of the previous frame failed, STA 1-1 may select a backoff counter value (e.g., a new backoff counter value) for AC_BE using an increased CW[AC] and / or an increased QSRC[AC].

[0094] STA 1-2 may perform a backoff operation using a backoff counter value selected according to the EDCAF for the corresponding AC to obtain a TXOP (eg, EDCAT TXOP) on the second link. STA 1-2 may transmit a frame (eg, a data frame) within the TXOP on the second link.

[0095] exist Figure 4b In an exemplary embodiment of , backoff operations of AC_BE EDCAF, AC_VO EDCAF, and AC_VI EDCAF for STA1-2 can be completed on the second link, and the backoff counter value for the backoff operation can be maintained at 0 to perform multi-link synchronous transmission on the first link and the second link. When the backoff counter value is maintained at 0 on the second link, if another communication node transmits a frame, the medium state (e.g., channel state) of the second link can be detected as a busy state. STA1-2 may not be able to decode the frame transmitted by the other communication node. In other words, STA1-2 can detect the energy of the frame transmitted by the other communication node, but cannot decode the header of the frame.

[0096] When the backoff operation on the first link is successful and the channel state of the second link is an idle state, multi-link synchronous transmission may be performed on the first link and the second link. When the backoff operation on the first link is successful and the channel state of the second link is a busy state, multi-link synchronous transmission may not be performed on the first link and the second link. In this case, frame transmission on the first link may be performed, and frame transmission on the second link may not be performed.

[0097] When the channel state (e.g., medium state) of the second link transitions from a busy state to an idle state, STA1-2 may wait for the EIFS for each AC. The EIFS for each AC may be "EIFS-DIFS+AIFS[AC]". If STA1-2 performs transmission based on the backoff counter value of a previously successful backoff operation (e.g., a backoff counter value maintained at 0), a transmission conflict (e.g., an internal conflict) may occur. If an internal conflict occurs, the frame may not be transmitted. Therefore, STA 1-2 may perform new backoff operations for AC_BE EDCAF, AC_VO EDCAF, and AC_VI EDCAF. In other words, the backoff operations for AC_BE EDCAF, AC_VO EDCAF, and AC_VI EDCAF may be called again at STA 1-2. The time of calling the backoff operation may be immediately after the time when the medium state transitions from the idle state to the busy state. Alternatively, the time of calling the backoff operation may be immediately after the time when the medium state transitions from the busy state to the idle state. Alternatively, the time of invoking the backoff operation may be after a predetermined time from the time when the medium status is detected as the busy state. Accordingly, STA 1-2 may have a new backoff counter value for EDCAF.

[0098] STA 1-2 may select a new backoff counter value using the existing CW[AC] and / or QSRC[AC] of the EDCAF for each AC. In other words, in order to select a new backoff counter value, the same CW[AC] and / or QSRC[AC used in the previous backoff operation may be used. As another method, in order to select a new backoff counter value, STA 1-2 may use an increased CW[AC] and / or an increased QSRC[AC]. For example, the CW[AC] of the EDCAF for each AC may be increased by n times, and the QSRC[AC] of the EDCAF for each AC may be increased by m. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. STA 1-2 may select a new backoff counter value using an increased CW[AC] and / or an increased QSRC[AC].

[0099] Alternatively, in order to select a new backoff counter value, a reduced CW[AC] and / or a reduced QSRC[AC] may be used. For example, the reduced CW[AC] may be 1 / n of the existing CW[AC], and the reduced QSRC[AC] may be m less than the existing QSRC[AC]. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. STA1-2 may select a new backoff counter value using the reduced CW[AC] and / or the reduced QSRC[AC]. Alternatively, in order to select a new backoff counter value, an initial value of CW[AC] and / or an initial value of QSRC[AC] may be used. Each of the initial value of CW[AC] and the initial value of QSRC[AC] may be a predefined value, or a value indicated by each AP associated with the AP MLD.

[0100] STA1-2 may perform a backoff operation using a backoff counter value selected according to the EDCAF for the corresponding AC to obtain a TXOP (eg, EDCAT TXOP) on the second link. STA1-2 may transmit a frame (eg, a data frame) within the TXOP on the second link.

[0101] Figure 5 is a timing diagram showing a fifth exemplary embodiment of a backoff operation method when multi-link synchronous transmission is not possible.

[0102] like Figure 5As shown, AP MLD 1 can operate on the first link and the second link. The STA associated with STAMLD N operating on link X can be called STA NX. The AP associated with AP MLD N operating on link X can be called AP NX. Each of X and N can be a natural number. STAMLD 1 can operate on the first link and the second link. The first link and the second link can be an NSTR link pair for STA MLD 1. The AP associated with AP MLD 1 operating on the first link can be called AP 1-1, and the AP associated with AP MLD 1 operating on the second link can be called AP 1-2. The STA associated with STA MLD 1 operating on the first link can be called STA 1-1, and the STA associated with STA MLD 1 operating on the second link can be called STA1-2.

[0103] The first link and the second link may be enhanced multi-link multi-radio (EMLMR) links for STAMLD 1. For example, AP MLD 1 and STAMLD 1 may perform a negotiation process for EMLMR operation on one of the first link and the second link. Once the negotiation process for EMLMR operation is completed, the EMLMR operation may be performed on both the first link and the second link.

[0104] The STA associated with STAMLD 1 may perform a backoff operation to perform multi-link synchronous transmission on the first link and the second link. The backoff operation may refer to an EDCAF backoff operation for each AC. When EDCA backoff is called, a backoff operation (e.g., an AC EDCAF backoff operation) may start. In other words, when EDCA backoff is called, a backoff operation may be performed. The backoff counter required for the backoff operation may be a backoff counter (e.g., an EDCA backoff counter) maintained by the EDCAF for each AC.

[0105] STA1-2 may successfully perform a backoff operation on the second link, and if the backoff operation is successful, the backoff counter value may be 0. For multi-link synchronous transmission involving STA1-1 and STA1-2, STA1-2 may maintain the backoff counter value on the second link (e.g., backoff counter values ​​for AC_VO EDCAF and AC_VI EDCAF) at 0 while waiting for STA1-1 to acquire a TXOP (e.g., EDCA TXOP) on the first link. TXOP may be acquired at a time slot (e.g., a time slot boundary) at which the EDCAF backoff counter of the STA reaches 0. Acquiring a TXOP (e.g., EDCA TXOP) by the STA may mean acquiring a TXOP (e.g., EDCA TXOP) by the EDCAF for each AC.

[0106] STA1-1 of STAMLD 1 may receive an initial frame from AP 1-1 before acquiring a TXOP on the first link. The initial frame may be an EMLMR initial frame. The initial frame may be an initial control frame. When receiving the initial frame on the first link, STA 1-2 of STAMLD1 may switch its RF chain to the first link (e.g., STA1-1 operating on the first link). In the present invention, the RF chain may correspond to a spatial stream. When the RF chain of STA1-2 is switched to the first link, a blindness period may occur on the second link. The blindness period on the second link may end after the EMLMR delay from the end time of the communication between STA1-1 and AP1-1 on the first link. Alternatively, the blindness period on the second link may end after "aSIFstime+aSlotTime+aRxPHYStartDelay+EMLMR delay" from the end time of the communication between STA1-1 and AP 1-1 on the first link. If the blindness period exceeds 72μs, the MediumSyncDelay timer may appear on the second link. In other words, the MediumSyncDelay timer may be started on the second link. The length of the MediumSyncDelay timer (e.g., the time corresponding to the MediumSyncDelay timer) may be aPPDUMaxTime. aPPDUMaxTime may be a predefined maximum length of the PPDU. During the time corresponding to the MediumSyncDelay timer, a channel detection operation and / or a frame transmission operation initiated by a request-to-send (RTS) frame may be performed. Since the channel detection operation is possible during the time corresponding to the MediumSyncDelay timer, an EDCAF backoff operation may also be performed.

[0107] After the blind period on the second link ends and the medium state of the second link transitions from the busy state to the idle state, the STA may wait for the AIFS for each AC to transmit data (e.g., AC_VO data and / or AC_VI data). The length of the AIFS may vary depending on the AC. Alternatively, the length of the AIFS for the ACs may be the same. For example, the length of the AIFS for AC_VO and the length of the AIFS for AC_VI may be the same. Since the length of the AIFS for AC_VO and the length of the AIFS for AC_VI are the same, if the transmission of AC_VO data and AC_VI data starts when the backoff counter value remains at 0, a transmission conflict may occur. When a transmission conflict occurs, a new backoff operation (e.g., EDCA backoff operation) for AC_VO EDCAF and AC_VI EDCAF may be called.

[0108] The time of invoking the backoff operation may be immediately after the time when the blind period occurs on the second link. Alternatively, the time of invoking the backoff operation may be after (e.g., immediately after) the end time of the blind period on the second link. Alternatively, the time of invoking the backoff operation may be after a predetermined time (e.g., a preconfigured time) from when the blind period occurs on the second link. Accordingly, STA1-2 may select new backoff values ​​for AC_VO EDCAF and AC_VI EDCAF.

[0109] STA1-2 may select a new backoff counter value using the existing CW[AC] and / or QSRC[AC] of the EDCAF for each AC. In other words, in order to select a new backoff counter value, the same CW[AC] and / or QSRC[AC used in the previous backoff operation may be used. As another method, in order to select a new backoff counter value, STA 1-2 may use an increased CW[AC] and / or an increased QSRC[AC]. For example, the CW[AC] of the EDCAF for each AC may be increased by n times, and the QSRC[AC] of the EDCAF for each AC may be increased by m. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. STA 1-2 may select a new backoff counter value using an increased CW[AC] and / or an increased QSRC[AC].

[0110] Alternatively, in order to select a new backoff counter value, a reduced CW[AC] and / or a reduced QSRC[AC] may be used. For example, the reduced CW[AC] may be 1 / n of the existing CW[AC], and the reduced QSRC[AC] may be m less than the existing QSRC[AC]. Each of n and m may be a natural number. For example, n may be 2, and m may be 1. STA1-2 may select a new backoff counter value using the reduced CW[AC] and / or the reduced QSRC[AC]. Alternatively, in order to select a new backoff counter value, an initial value of CW[AC] and / or an initial value of QSRC[AC] may be used. Each of the initial value of CW[AC] and the initial value of QSRC[AC] may be a predefined value, or a value indicated by each AP associated with the AP MLD.

[0111] STA1-2 may perform a backoff operation using a backoff counter value selected according to the EDCAF for the corresponding AC to obtain a TXOP (e.g., EDCAT TXOP) on the second link. STA 1-2 may transmit a frame (e.g., a data frame) within the TXOP on the second link. For example, STA 1-2 may first transmit an RTS frame within the TXOP on the second link, and after transmitting the RTS frame within the TXOP on the second link, STA 1-2 may transmit a data frame. In other words, if the MediumSyncDelay timer of STA1-2 has not expired, the frame first transmitted within the TXOP on the second link may be an RTS frame.

[0112] Figure 6 is a timing diagram illustrating a first exemplary embodiment of a method for determining parameters of a channel access operation in multi-link synchronous transmission.

[0113] like Figure 6 As shown, AP MLD 1 can operate on the first link and the second link. The STA associated with STAMLD N operating on link X can be called STAN-X. The AP associated with AP MLD N operating on link X can be called AP NX. Each of X and N can be a natural number. STAMLD 1 can operate on the first link and the second link. The first link and the second link can be an NSTR link pair for STA MLD 1. The AP associated with AP MLD 1 operating on the first link can be called AP 1-1, and the AP associated with AP MLD 1 operating on the second link can be called AP 1-2. The STA associated with STA MLD 1 operating on the first link can be called STA 1-1, and the STA associated with STA MLD 1 operating on the second link can be called STA1-2.

[0114] The STA associated with STAMLD 1 may perform a backoff operation to perform multi-link synchronous transmission on the first link and the second link. The backoff operation may refer to an EDCAF backoff operation for each AC. When EDCA backoff is called, a backoff operation (e.g., an AC EDCAF backoff operation) may start. In other words, when EDCA backoff is called, a backoff operation may be performed. The backoff counter required for the backoff operation may be a backoff counter (e.g., an EDCA backoff counter) maintained by the EDCAF for each AC.

[0115] STA1-2 may successfully perform a backoff operation on the second link, and if the backoff operation is successful, the backoff counter value may be 0. For multi-link synchronous transmission involving STA1-1 and STA1-2, STA1-2 may maintain the backoff counter value on the second link at 0 while waiting for STA1-1 to acquire a TXOP (e.g., EDCA TXOP) on the first link. A TXOP may be acquired at a time slot (e.g., a time slot boundary) at which the EDCAF backoff counter of the STA reaches 0. Acquiring a TXOP (e.g., EDCA TXOP) by the STA may mean acquiring a TXOP (e.g., EDCA TXOP) by the EDCAF for each AC.

[0116] The EDCA parameters (e.g., channel access parameters, backoff parameters) used for the respective links may be different. For example, the (default) EDCA parameters configured for the first link may be different from the (default) EDCA parameters configured for the second link. During a specific period (e.g., a restricted target wake time (rTWT) service period (SP)), the EDCA parameters may be modified, and they may vary depending on the link.

[0117] If the EDCA parameters of the second link are different from the EDCA parameters of the first link, STA MLD 1 may perform a backoff operation on the first link (e.g., a backoff operation of STA1-1) and a backoff operation on the second link (e.g., a backoff operation of STA1-2) using the EDCA parameters of the second link (e.g., the EDCA parameters applied to STA1-2 operating on the second link) to perform multi-link synchronous transmission on the first link and the second link. Alternatively, STAMLD 1 may perform a backoff operation on the first link (e.g., a backoff operation of STA1-1) and a backoff operation on the second link (e.g., a backoff operation of STA1-2) using the EDCA parameters of the first link (e.g., the EDCA parameters applied to STA1-1 operating on the first link). In other words, for multi-link synchronous transmission, backoff operations on multiple links (e.g., the first link and the second link) may be performed using the same EDCA parameters. STA1-1 and STA 1-2 may perform multi-link synchronous transmission and may transmit frames within a TXOP (e.g., an EDCA TXOP).

[0118] 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.

[0119] 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.

[0120] 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 step of the method or the feature of the step. Similarly, the aspects described in the context of the method may be represented as the feature of a corresponding block or project or a corresponding device. Some or all steps of the method may be performed by (or using) a hardware device such as a microprocessor, a programmable computer or an electronic circuit. In some embodiments, one or more of the most important steps of the method may be performed by such a device.

[0121] 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 methods 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.

[0122] The description of the present invention is merely exemplary in nature, 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 considered 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 may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A method of a station (STA) multi-link device (MLD), comprising: performing a first backoff operation on the first link; In response to completion of the first backoff operation, maintaining a backoff counter value for the first backoff operation at 0 for multi-link synchronous transmission on the first link and the second link; performing a second backoff operation on the second link; as well as In response to completion of the second backoff operation, performing multi-link synchronous transmission on the first link and the second link, When performing multi-link synchronous transmission, the transmission start time of the first frame on the first link is equal to the transmission start time of the second frame on the second link.

2. The method according to claim 1, wherein: When the second backoff operation is completed and the channel state of the first link is in an idle state, multi-link synchronous transmission is performed; when the second backoff operation is completed and the channel state of the first link is in a busy state, multi-link synchronous transmission is not performed.

3. The method according to claim 1, wherein: The STA MLD is a non-simultaneous transmit and receive (NSTR) STA MLD that is incapable of STR operation, and the first link and the second link are NSTR links.

4. The method according to claim 1, wherein: When a first channel access parameter configured for a first backoff operation is different from a second channel access parameter configured for a second backoff operation, the first backoff operation and the second backoff operation for multi-link synchronous transmission are performed using the same channel access parameter, wherein the same channel access parameter is the first channel access parameter or the second channel access parameter, and the same channel access parameter includes at least one of a contention window (CW) for each access category (AC) or a quality of service (QoS) short frame retry counter (QSRC) for each AC.

5. The method according to claim 1, wherein: When a first backoff operation for each of a plurality of data units having different ACs is completed on a first link, multi-link synchronous transmission for a first data unit among the plurality of data units is performed.

6. The method according to claim 5, further comprising: performing a third backoff operation on a second data unit among the plurality of data units on the first link; as well as In response to the third backoff operation being successful, transmitting a second data unit on the first link.

7. The method according to claim 6, wherein: A third backoff operation is performed after a time when the channel state of the first link transitions from an idle state to a busy state, after a time when the channel state of the first link transitions from a busy state to an idle state, or after a predefined time from a time when the channel state of the first link is detected as a busy state.

8. The method according to claim 6, wherein: The first channel access parameter for the first backoff operation on the first link is equal to the third channel access parameter for the third backoff operation on the first link.

9. The method according to claim 6, wherein: The first channel access parameter for the first backoff operation on the first link is different from the third channel access parameter for the third backoff operation on the first link, and the CW in the third backoff parameter is n times or 1 / n of the CW in the first backoff parameter, where n is a natural number.

10. The method according to claim 6, wherein: The first channel access parameter for the first backoff operation on the first link is different from the third channel access parameter for the third backoff operation on the first link, and the QSRC in the third backoff parameter is greater or less than the QSRC in the first backoff parameter by m, where m is a natural number.

11. A station (STA) multi-link device (MLD), comprising at least one processor, wherein the at least one processor causes the STA MLD to perform: performing a first backoff operation on the first link; In response to completion of the first backoff operation, maintaining a backoff counter value for the first backoff operation at 0 for multi-link synchronous transmission on the first link and the second link; performing a second backoff operation on the second link; as well as In response to completion of the second backoff operation, performing multi-link synchronous transmission on the first link and the second link, When performing multi-link synchronous transmission, the transmission start time of the first frame on the first link is equal to the transmission start time of the second frame on the second link.

12. The STA MLD according to claim 11, wherein: When the second backoff operation is completed and the channel state of the first link is in an idle state, multi-link synchronous transmission is performed; when the second backoff operation is completed and the channel state of the first link is in a busy state, multi-link synchronous transmission is not performed.

13. The STA MLD according to claim 11, wherein: The STA MLD is a non-simultaneous transmit and receive (NSTR) STA MLD that is incapable of STR operation, and the first link and the second link are NSTR links.

14. The STA MLD according to claim 11, wherein: When a first channel access parameter configured for a first backoff operation is different from a second channel access parameter configured for a second backoff operation, the first backoff operation and the second backoff operation for multi-link synchronous transmission are performed using the same channel access parameter, wherein the same channel access parameter is the first channel access parameter or the second channel access parameter, and the same channel access parameter includes at least one of a contention window (CW) for each access category (AC) or a quality of service (QoS) short frame retry counter (QSRC) for each AC.

15. The STA MLD according to claim 11, wherein: When a first backoff operation for each of a plurality of data units having different ACs is completed on a first link, multi-link synchronous transmission for a first data unit among the plurality of data units is performed.

16. The STA MLD according to claim 15, wherein: The at least one processor further causes the STA MLD to perform: performing a third backoff operation on a second data unit of the plurality of data units on the first link; and In response to the third backoff operation being successful, transmitting a second data unit on the first link.

17. The STA MLD according to claim 16, wherein: A third backoff operation is performed after a time when the channel state of the first link transitions from an idle state to a busy state, after a time when the channel state of the first link transitions from a busy state to an idle state, or after a predefined time from a time when the channel state of the first link is detected as a busy state.

18. The STA MLD according to claim 16, wherein: The first channel access parameter for the first backoff operation on the first link is equal to the third channel access parameter for the third backoff operation on the first link.

19. The STA MLD according to claim 16, wherein: The first channel access parameter for the first backoff operation on the first link is different from the third channel access parameter for the third backoff operation on the first link, and the CW in the third backoff parameter is n times or 1 / n of the CW in the first backoff parameter, where n is a natural number.

20. The STA MLD according to claim 16, wherein: The first channel access parameter for the first backoff operation on the first link is different from the third channel access parameter for the third backoff operation on the first link, and the QSRC in the third backoff parameter is greater or less than the QSRC in the first backoff parameter by m, where m is a natural number.

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