Method and device based on EMLMR communication in wireless local area network

Abstract

A method and apparatus for EMLMR-based communication in a wireless local area network are disclosed. The method of STA MLD comprises the steps of: configuring a maximum NSS for EMLMR operation with an AP MLD; receiving, from the AP MLD, usage indications of n spatial streams less than or equal to the maximum NSS in the first link; and communicating with the AP MLD by utilizing the n spatial streams in the first link.

Description

Technical Field

[0001] The present invention relates to a wireless local area network (WLAN) communication technology, and more particularly, to an energy-saving technology and a communication technology in a WLAN supporting enhanced multi-link multi-radio (EMLMR) operation. 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] As applications requiring higher throughput and applications requiring real-time transmission emerge, wireless local area networks may support communications utilizing an expanded frequency bandwidth. In this case, methods to support efficient transmission operations and / or efficient power-saving operations may be required.

[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 directed to providing a method and apparatus for energy saving in a wireless local area network supporting enhanced multi-link multi-radio (EMLMR) operation.

[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: configuring a maximum number of spatial streams (NSS) for enhanced multi-link multi-radio (EMLMR) operation using an access point (AP) MLD; receiving an instruction from the AP MLD on a first link to use n spatial streams equal to or less than the maximum NSS; and communicating with the AP MLD on the first link using n spatial streams, where n is a natural number.

[0010] The method may further include communicating with the AP MLD using a "maximum NSS-n" number of spatial streams on the second link.

[0011] When the "maximum NSS-n" is 0, communication between the STA MLD and the APMLD may not be performed on links other than the first link.

[0012] The method may further include: communicating with the AP MLD on each link using a number of spatial streams corresponding to a default NSS, wherein, when the EMLMR operation is configured and the maximum NSS is configured, communication between the STA MLD and the AP MLD on each link may be performed using a number of spatial streams equal to or less than the maximum NSS.

[0013] When n exceeds the default NSS, one or more spatial streams configured for links other than the first link may be reconfigured for the first link, and a sum of the number of the one or more spatial streams and the default NSS may be n.

[0014] The reconfiguration of the one or more spatial streams may be performed based on at least one of a priority of the spatial streams on each link or a reconfiguration scheme.

[0015] The method may further include: configuring a maximum power saving (PS)-NSS for power saving operation with the AP MLD, wherein, when the power saving operation is performed on a link other than the first link, communication between the STA MLD and the AP MLD on the first link may be performed using a number of spatial streams equal to or less than the maximum PS-NSS, and the maximum PS-NSS may be configured to be less than the maximum NSS.

[0016] The initial frame received from the AP MLD on the first link may include instructions to utilize n spatial streams.

[0017] The maximum NSS can be configured during the configuration process of the EMLMR operation between the STA MLD and the AP MLD.

[0018] According to an exemplary embodiment of the present invention, a method of STA MLD for achieving the above-mentioned purpose may include: configuring a maximum number of spatial streams (NSS) for enhanced multi-link multi-radio (EMLMR) operation using an access point (AP) MLD; sending an instruction to the AP MLD on a first link to use n spatial streams equal to or less than the maximum NSS; and communicating with the AP MLD on the first link using n spatial streams, where n is a natural number.

[0019] The method may further include communicating with the AP MLD using a "maximum NSS-n" number of spatial streams on the second link.

[0020] When the "maximum NSS-n" is 0, communication between the STA MLD and the APMLD may not be performed on links other than the first link.

[0021] The method may further include: communicating with the AP MLD on each link using a number of spatial streams corresponding to a default NSS, wherein, when the EMLMR operation is configured and the maximum NSS is configured, communication between the STA MLD and the AP MLD on each link may be performed using a number of spatial streams equal to or less than the maximum NSS.

[0022] When n exceeds the default NSS, one or more spatial streams configured for links other than the first link may be reconfigured for the first link, and a sum of the number of the one or more spatial streams and the default NSS may be n.

[0023] The reconfiguration of the one or more spatial streams may be performed based on at least one of a priority of the spatial streams on each link or a reconfiguration scheme.

[0024] According to an exemplary embodiment of the present invention, a method of an access point (AP) MLD for achieving the above-mentioned purpose may include: configuring a maximum number of spatial streams (NSS) for enhanced multi-link multi-radio (EMLMR) operation using a station (STA) MLD; sending an instruction to the STA MLD to use n spatial streams equal to or less than the maximum NSS on a first link; and communicating with the STA MLD using n spatial streams on the first link, where n is a natural number.

[0025] The method may further include communicating with the STA MLD using a "maximum NSS-n" number of spatial streams on the second link.

[0026] When the "maximum NSS-n" is 0, communication between the STA MLD and the APMLD may not be performed on links other than the first link.

[0027] The method may further include: communicating with the STA MLD on each link using a number of spatial streams corresponding to a default NSS, wherein, when the EMLMR operation is configured and the maximum NSS is configured, communication between the STA MLD and the AP MLD on each link may be performed using a number of spatial streams equal to or less than the maximum NSS.

[0028] The method may further include: configuring a maximum power saving (PS)-NSS for power saving operation with the AP MLD, wherein, when the power saving operation is performed on a link other than the first link, communication between the STA MLD and the AP MLD on the first link may be performed using a number of spatial streams equal to or less than the maximum PS-NSS, and the maximum PS-NSS may be configured to be less than the maximum NSS.

[0029] Beneficial Effects

[0030] According to the present invention, a communication node in a wireless local area network may support EMLMR operation. The communication node may include a STA, a STA MLD, an AP and / or an AP MLD. Parameters for EMLMR operation may be configured between a STA (e.g., a STA MLD) and an AP (e.g., an AP MLD). The parameters may include parameters for energy-saving operation and / or parameters for multi-link communication. The communication node may perform efficient power-saving operation and / or efficient multi-link communication based on the parameters. 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 of a first exemplary embodiment of an EMLMR operation.

[0034] Figure 3b is a timing diagram of a second exemplary embodiment of an EMLMR operation.

[0035] Figure 3c is a timing diagram of a third exemplary embodiment of an EMLMR operation.

[0036] Figure 4 is a timing diagram illustrating a first exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0037] Figure 5is a timing diagram illustrating a second exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0038] Figure 6 is a timing diagram illustrating a third exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0039] Figure 7 is a timing diagram illustrating a fourth exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0040] Figure 8 is a timing diagram illustrating a fifth exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0041] Fig. 9 is a timing diagram illustrating a sixth exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0042] Fig.10 is a timing diagram illustrating a seventh exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0043] Fig.11 is a timing diagram illustrating an eighth exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0044] Fig.12 is a timing diagram showing a first exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation and EMLSR operation. DETAILED DESCRIPTION

[0045] Since the present invention can be variously modified and has multiple 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.

[0046] 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.

[0047] 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".

[0048] 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 between them. On the contrary, 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 between them.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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".

[0053] 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.

[0054] Figure 1 is a block diagram showing a first exemplary embodiment of a communication node constituting a wireless LAN system.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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).

[0059] Figure 2 is a conceptual diagram showing a first exemplary embodiment of multi-links configured between multi-link devices (MLDs).

[0060] like Figure 2 As 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.

[0061] 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).

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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".

[0066] For example, a multi-link 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 APMLD may send frames using link 1 and may receive frames 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.

[0067] 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 that supports multiple links (e.g., an access point, a station) 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 a "STAMLD". The AP MLD can have a physical address (e.g., a MAC address) for each link. The 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. The STA MLD can have a physical address (e.g., a MAC address) for each link. The 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.

[0068] For example, AP1 of the AP MLD and STA1 of the STA MLD may each be responsible for a first link and may communicate using the first link. AP2 of the AP MLD and STA2 of the STA MLD may each be responsible for a second link and may communicate using the second link. STA2 may receive state change information of the first link on the second link. In this case, the STA MLD may collect information (e.g., state change information) received on each link and control an operation performed by STA1 based on the collected information.

[0069] 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.

[0070] In the present invention, the operation of STA can be interpreted as the operation of STA MLD, the operation of STA MLD can be interpreted as the operation of STA, the operation of AP can be interpreted as the operation of AP MLD, and the operation of AP MLD can be interpreted as the operation of AP. The STA of STA MLD can refer to the STA associated with STA MLD, and the AP of AP MLD can refer to the AP associated with AP MLD. When STA MLD includes a first STA operating on a first link and a second STA operating on a second link, the operation of STA MLD on the first link can be interpreted as the operation of the first STA, and the operation of STA MLD on the second link can be interpreted as the operation of the second STA. When AP MLD includes a first AP operating on the first link and a second AP operating on the second link, the operation of AP MLD on the first link can be interpreted as the operation of the first AP, and the operation of AP MLD on the second link can be interpreted as the operation of the second AP. In the present invention, a communication node (e.g., STA, STA MLD, AP and / or AP MLD) can support multi-link single radio (MLSR), enhanced MLSR (EMLSR), multi-link multi-radio (MLMR) and / or enhanced MLMR (EMLMR).

[0071] Figure 3a is a timing diagram of a first exemplary embodiment of an EMLMR operation, Figure 3b is a timing diagram of a second exemplary embodiment of an EMLMR operation, Figure 3c is a timing diagram of a third exemplary embodiment of an EMLMR operation.

[0072] like Figure 3a , Figure 3b and Figure 3c As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0073] STA MLD1 may perform a performance negotiation process with AP MLD using one of the multiple links. The performance negotiation process may be performed through an association process between STA MLD1 and AP MLD. During the performance negotiation process, the number of spatial streams available for use by the STA on each link may be configured or determined. In other words, the number of spatial streams per link may be configured. For example, during the performance negotiation process, the number of spatial streams per link may be configured to be 2. In this case, each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 may perform communication on each link using 2 spatial streams. The number of spatial streams per link configured during the performance negotiation process may be the number of initial spatial streams (NSS) or the default NSS for each link.

[0074] STA MLD1 may perform a configuration process of EMLMR operation with AP MLD using one of a plurality of links. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) may be referred to as EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) may be referred to as EMLMR STA. For example, STA MLD1 may be an EMLMR STA MLD, and STA1-1, STA1-2, and STA1-3 may each be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation may be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operation on a first link, a second link, and a third link, and the first link, the second link, and the third link may be referred to as an EMLMR link. The configuration process of EMLMR operation may be performed by exchanging an enhanced multi-link (EML) operating mode notification (OMN) frame between STA MLD1 and AP MLD. The EML OMN frame may be an action frame. The EML OMN frame may include a plurality of information elements. For example, the EML OMN frame may include an EMLMR link bitmap, and the EMLMR bitmap may be used to indicate a link that performs an EMLMR operation (eg, a link that supports the EMLMR operation or an EMLMR link).

[0075] The EML OMN frame may include a supported modulation and coding scheme (MCS) and NSS set. The supported MCS and NSS set may be used to negotiate the maximum number of spatial streams used on each link. The number of spatial streams per link may be configured to a value indicated by the supported MCS and NSS set included in the EML OMN frame. During the configuration process for EMLMR operation, the maximum NSS on each link supporting EMLMR operation may be configured to 6.

[0076] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. In the present invention, the initial frame may refer to an initial control frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA (e.g., an initial NSS or a default NSS) associated with the STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link.

[0077] The initial frame may further include padding bits corresponding to an EMLMR delay time (e.g., at least one of an EMLMR padding delay or an EMLMR conversion delay) for an RF chain switching time (e.g., a spatial stream reconfiguration time). Since the maximum NSS for the EMLMR operation has been configured, the STA can perform transmission and reception operations on a frame (e.g., a data frame) using up to the number of spatial streams corresponding to the maximum NSS after receiving the initial frame. For example, if the maximum NSS for the EMLMR operation is configured to 6, the STA can perform communication using up to 6 spatial streams after receiving the initial frame.

[0078] In the EMLMR operation, the STAs (e.g., STA1-2 and / or STA1-3) associated with STA MLD1 as the EMLMR STA MLD may perform energy-saving operations. For example, if STA1-1 performs communication according to the EMLMR operation on the first link, the STAs (e.g., STA1-2 and / or STA1-3) on other links (e.g., the second link and / or the third link) may perform energy-saving operations. Energy-saving operations may refer to power management operations. The STAs that perform energy-saving operations may operate in a sleep state. The power consumption of the STAs in the sleep state may be low.

[0079] When EMLMR operation is configured and STA1-1 receives an initial frame, the RF chain of STA1-2 (e.g., the RF chain operating on the second link) can be switched to STA1-1 (e.g., the first link operated by STA1-1), and the RF chain of STA1-3 (e.g., the RF chain operating on the third link) can be switched to STA1-1 (e.g., the first link operated by STA1-1). Switching the RF chain may refer to the reconfiguration of the spatial stream. In this case, the power consumption of STA MLD1 may increase. In order to solve the above problem, the maximum NSS for supporting energy-saving operation can be configured separately. The maximum NSS for supporting energy-saving operation may be referred to as the maximum power-saving (PS)-NSS. The maximum PS-NSS can be exchanged between the AP MLD and the STA MLD1. The maximum PS-NSS can be configured to be less than or equal to the maximum NSS.

[0080] exist Figure 3aIn the exemplary embodiment shown, STA1-1 may receive an initial frame from AP1. Since STA1-2 and STA1-3 are in a sleep state, STA MLD1 may wish to use only 2 spatial streams to reduce power consumption. In this case, STA1-1 may notify the required NSS using a response frame to the initial frame of AP1. The required NSS may indicate the maximum NSS that STA1-1 (e.g., STA MLD1) wishes to use. The response frame to the initial frame may be generated in the form of an aggregated (A)-MAC layer protocol data unit (MPDU) including a block acknowledgment (BA) frame and a QoS null frame. The high throughput (HT) control field included in the QoS null frame may include information (e.g., a field, a subfield, a bitmap, or an information element) indicating the required NSS. The HT control field may include an operating mode indicator (OMI) as A-control information. The OMI (e.g., an OMI field) may indicate the required NSS. Alternatively, the HT control field may include a separate bitmap, a separate information element, or a separate field indicating the required NSS. The required NSS may be equal to or less than the maximum NSS or the maximum PS-NSS. As another method, a response frame to the initial frame may be generated in the form of an A-MPDU including a BA frame and an action frame (e.g., an "Action No Ack" frame as a type of action frame). The action frame may be a frame (e.g., an EML OMN frame) capable of indicating NSS and MCS information. The NSS and MCS information included in the action frame may indicate the required NSS. In the present invention, the BA frame may be interpreted as an ACK frame depending on the context.

[0081] As another method, a response frame to the initial frame may be generated in the form of an A-MPDU including a BA frame and an action frame, and the action frame may include information (e.g., a field, a subfield, a bitmap, or an information element) indicating a required NSS. The ACK policy field of the QoS null frame and / or the action frame added to the response frame together with the BA frame may be configured to indicate "no acknowledgment". Alternatively, the ACK policy field may be set to a value other than a value indicating "no acknowledgment".

[0082] AP1 may receive a response frame to the initial frame from STA1-1, and may identify a BA frame included in the response frame. In addition, AP1 may identify a QoS empty frame and / or an action frame included in the response frame. AP1 may identify the required NSS indicated by an information element (e.g., field) included in the QoS empty frame and / or the action frame. If the required NSS is configured as 2, AP1 may determine that the maximum NSS intended to be used by STA1-1 is 2. AP1 may identify an ACK policy field included in a QoS empty frame and / or an action frame. If the ACK policy field indicates "no confirmation", AP1 may not send a response frame to the QoS empty frame and / or the action frame. Alternatively, AP1 may not send a response frame to the QoS empty frame and / or the action frame, regardless of the ACK policy field included in the QoS empty frame and / or the action frame.

[0083] After receiving the response frame to the initial frame, AP1 may send a frame to STA1-1 using a number of spatial streams equal to or less than a desired NSS (e.g., a maximum NSS that STA1-1 intends to use) after a short interframe space (SIFS) from the time the response frame is received. STA1-1 may expect AP1 to send a frame using a number of spatial streams equal to or less than the desired NSS, and may perform a reception operation on the frame.

[0084] exist Figure 3b In an exemplary embodiment of the present invention, STA MLD1 and AP MLD may configure a maximum NSS (e.g., a maximum PS-NSS) for energy-saving operation in a separate process after a configuration process of an EMLMR operation. The maximum PS-NSS may be configured through an exchange process of an EML OMN frame between STA MLD1 and APMLD. The maximum PS-NSS may be the maximum NSS used by STA MLD1 during energy-saving operation. Some of the reserved bits in the EML OMN frame may be configured as a PS subfield. A PS subfield set to a first value may indicate that an EML OMN frame including the PS subfield includes an information element indicating a maximum PS-NSS. A PS subfield set to a second value may indicate that an EML OMN frame including the PS subfield does not include an information element indicating a maximum PS-NSS.

[0085] STA MLD1 may send an EML OMN frame including a PS subfield set to a first value to the AP MLD. When the PS subfield is set to the first value, an extremely high throughput (EHT)-MCS and NSS setting field of the EML OMN frame may indicate a maximum PS-NSS. The AP MLD may receive the EML OMN frame from the STA MLD1. If the PS subfield included in the EML OMN frame is set to a first value, the AP MLD may determine that the EHT-MCS and NSS setting fields of the EML OMN frame indicate a maximum PS-NSS. In other words, the AP MLD may identify the maximum PS-NSS indicated by the EML OMN frame received from the STA MLD1. The maximum PS-NSS may be equal to or greater than the number of spatial streams per link (e.g., a default NSS). For example, the maximum PS-NSS may be 4. The maximum PS-NSS may be configured to be less than the maximum NSS for EMLMR operation.

[0086] After the configuration of the maximum PS-NSS, AP1 may send an initial frame to STA1-1. STA1-1 may receive the initial frame from AP1 and send a response frame (e.g., a BA frame or an ACK frame) for the initial frame to AP1. AP1 may receive a response frame for the initial frame from STA1-1. After receiving the response frame, AP1 may send a frame to STA1-1 using a number of spatial streams equal to or less than the maximum PS-NSS. When STA MLD1 performs a power saving operation (e.g., when the STA is in a sleep state on a link other than the first link), communication between AP1 and STA1-1 on the first link may be performed using a spatial stream equal to or less than the maximum PS-NSS. For example, AP1 may send a frame to STA1-1 using 4 or less spatial streams. STA1-1 may expect AP1 to send a frame using a spatial stream equal to or less than the maximum PS-NSS, and may perform a receiving operation on the frame.

[0087] exist Figure 3cIn an exemplary embodiment, STA1-1 may receive a traffic indication map (TIM) from AP1 and identify an indicator configured in the TIM indicating the presence of a buffered unit (BU) to be received by STA1-1. In this case, STA1-1 may send a PS-Poll frame to AP1 to receive the BU. Since STA1-2 and STA1-3 are in a sleep state, STA MLD1 may want to use 3 spatial streams that are less than the maximum NSS (e.g., 6 spatial streams) to reduce power consumption. In this case, the PS-Poll frame sent by STA1-1 may be configured to include an information element (e.g., a field) indicating the NSS (e.g., the desired NSS) that STA1-1 intends to use.

[0088] For example, the PS-Poll frame may have the form of an A-MPDU, and a QoS empty frame and / or an action frame may be added to the PS-Poll frame. The HT control field included in the QoS empty frame added to the PS-Poll frame may include information (e.g., a field, a subfield, a bitmap, or an information element) indicating the required NSS. The required NSS may be equal to or greater than the number of spatial streams per link (e.g., a default NSS) and equal to or less than the maximum NSS. In order to minimize power consumption, the required NSS may be configured to a value less than the number of spatial streams per link (e.g., a default NSS). The HT control field may include OMI as A-control information. OMI (e.g., an OMI field) may indicate the required NSS. Alternatively, the HT control field may include a separate bitmap, a separate information element, or a separate field indicating the required NSS.

[0089] As another method, the action frame added to the PS-Poll frame may include information (e.g., a field, a subfield, a bitmap, or an information element) indicating the required NSS. The ACK policy field of the QoS null frame and / or the action frame added to the PS-Poll frame in the form of an A-MPDU may be configured to indicate "No ACK". Alternatively, the ACK policy field may be set to a value other than a value indicating "No ACK".

[0090] AP1 may receive a "PS-Poll frame and a QoS empty frame" or a "PS-Poll frame and an action frame" from STA1-1. In other words, AP1 may identify a PS-Poll frame and / or a QoS empty frame added to a PS-Poll frame in the form of an A-MPDU. AP1 may identify a required NSS indicated by an information element (e.g., field) included in a QoS empty frame and / or an action frame. If the required NSS is configured as 3, AP1 may determine that the maximum NSS that STA1-1 intends to use is 3. AP1 may identify an ACK policy field included in a QoS empty frame and / or an action frame. If the ACK policy field indicates "no acknowledgment", AP1 may not send a response frame to the QoS empty frame and / or the action frame. Alternatively, AP1 may not send a response frame to the QoS empty frame and / or the action frame regardless of the ACK policy field included in the QoS empty frame and / or the action frame.

[0091] AP1 may send a response frame (e.g., an ACK frame) for the PS-Poll frame to STA1-1. AP1 may send a BU (e.g., a frame including a BU) to STA1-1 using a number of spatial streams equal to or less than a desired NSS (e.g., a maximum NSS that STA1-1 intends to use). STA1-1 may expect AP1 to send a BU (e.g., a frame including a BU) using a spatial stream equal to or less than the desired NSS, and may perform a reception operation on the BU.

[0092] On the other hand, AP1 may not be able to support the required NSS of STA1-1. In other words, AP1 may use a smaller number of spatial streams than the required NSS of STA1-1. In this case, AP1 may send a NACK to STA1-1 in response to a QoS null frame and / or an action frame indicating the required NSS. For example, AP1 may generate a BA frame for "PS-Poll frame and QoS null frame" or "PS-Poll frame and action frame" and send the BA frame to STA1-1. Among the bits included in the BA frame, the bits for the QoS null frame and / or the action frame may indicate a NACK.

[0093] STA1-1 may receive a NACK of a QoS null frame and / or an action frame from AP1 indicating a required NSS. In this case, STA1-1 may determine that AP1 cannot support the required NSS. After sending a NACK of a QoS null frame and / or an action frame, AP1 may send a frame to STA1-1 using a spatial stream supported by AP1. STA1-1 may expect AP1 to send a frame using a spatial stream supported by AP1 and may perform a receive operation on the frame.

[0094] As another method, if AP1 does not support the required NSS of STA1-1, AP1 can send a frame to STA1-1 using a spatial stream supported by AP1 without sending a response frame (e.g., BA frame) for "PS-Poll frame and QoS empty frame" or "PS-Poll frame and action frame". STA1-1 can receive a frame from AP1.

[0095] Figure 4 is a timing diagram illustrating a first exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0096] like Figure 4 As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0097] Each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 can send and receive frames using 2 spatial streams. In other words, the number of spatial streams per link can be 2. The number of spatial streams per link (e.g., 2) can be the initial NSS or default NSS for each link. STA MLD1 and AP MLD can perform a configuration process for EMLMR operation. EMLMR operation can be configured between STA MLD1 and AP MLD. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) can be referred to as an EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) can be referred to as an EMLMR STA. For example, STA MLD1 can be an EMLMR STA MLD, and each of STA1-1, STA1-2, and STA1-3 can be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation can be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operations on the first link, the second link, and the third link, and the first link, the second link, and the third link may be referred to as EMLMR links.

[0098] In the configuration process (e.g., negotiation process) of the EMLMR operation between STA MLD1 and AP MLD, the maximum NSS for the EMLMR operation can be configured. In other words, STA MLD1 and AP MLD can configure the maximum NSS for the EMLMR operation. For example, the maximum NSS for the EMLMR operation can be configured to 6.

[0099] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA associated with STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link (e.g., default NSS).

[0100] The initial frame may further include a padding bit corresponding to the EMLMR delay time (e.g., at least one of the EMLMR padding delay or the EMLMR conversion delay) for the RF chain switching time. In the present invention, the RF chain switching time may refer to the time required to reconfigure the spatial stream. Since the maximum NSS for EMLMR operation is configured, the STA can perform transmission and reception operations on the frame (e.g., data frame) using up to the number of spatial streams corresponding to the maximum NSS after receiving the initial frame. For example, if the maximum NSS for the EMLMR operation is configured to 6, the STA can perform communication using up to 6 spatial streams after receiving the initial frame.

[0101] STA MLD1 may not support OMI. Accordingly, each STA associated with STA MLD1 may not send a frame including OMI (e.g., an OMI field). When EMLMR operation is configured and STA1-1 receives an initial frame, an RF chain switching process may be performed for STA1-1 to use 6 spatial streams after receiving the initial frame. For example, the RF chain of STA1-2 (e.g., an RF chain operating on the second link) may be switched to STA1-1 (e.g., a first link operated by STA1-1), and the RF chain of STA1-3 (e.g., an RF chain operating on the third link) may be switched to STA1-1 (e.g., a first link operated by STA1-1). After the RF chain switching process is completed, STA1-1 may communicate with AP1 using 6 spatial streams.

[0102] When communication between STA1-1 and AP1 is performed on the first link, communication between STA1-2 and AP2 on the second link and / or between STA1-3 and AP3 on the third link may not be performed. In the present invention, communication may refer to the transmission and reception process of a frame. The start time of the period during which communication is not performed (hereinafter referred to as a "non-communication period") may be the start time of the initial frame of the receiving AP (e.g., AP1), the time when the receiver address (RA) of at least one MPDU included in the initial frame is identified as corresponding to STA1-1, or the end time of receiving the initial frame. As another method, the start time of the non-communication period may start at a time when no spatial stream is available for the STA. The start time of the non-communication period may be identified when the STA (e.g., STA1-1) indicated by the RA of the MPDU successfully completes the decoding of the MPDU.

[0103] The end time of the non-communication period may be the time after the EMLMR delay from the transmission time of the last frame on the first link. After the non-communication period, the MediumSyncDelay time (e.g., the MediumSyncDelay timer) may start. If there is data to be sent during the MediumSyncDelay time, the transmission of data (e.g., a data frame) may be initiated by sending a request-to-send (RTS) frame or a multi-user (MU) RTS frame. Without sending an RTS frame or a MU-RTS frame, a data frame may not be sent. During the MediumSyncDelay time, a communication node (e.g., an AP or a STA) may receive a frame from another communication node. If the decoding of the frame is successfully completed, the communication node may identify the duration indicated by the duration field included in the frame. If the duration is identified, the communication node may release the MediumSyncDelay timer and set the NAV. Once the MediumSyncDelay timer is released, the communication node may perform normal channel access operations.

[0104] Figure 5 is a timing diagram illustrating a second exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0105] like Figure 5As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0106] Each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 can send and receive frames using 2 spatial streams. In other words, the number of spatial streams per link can be 2. The number of spatial streams per link (e.g., 2) can be the initial NSS or default NSS for each link. STA MLD1 and AP MLD can perform a configuration process for EMLMR operation. EMLMR operation can be configured between STA MLD1 and AP MLD. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) can be referred to as an EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) can be referred to as an EMLMR STA. For example, STA MLD1 can be an EMLMR STA MLD, and each of STA1-1, STA1-2, and STA1-3 can be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation can be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operations on the first link, the second link, and the third link, and the first link, the second link, and the third link may be referred to as EMLMR links.

[0107] In the configuration process (e.g., negotiation process) of the EMLMR operation between STA MLD1 and AP MLD, the maximum NSS for the EMLMR operation can be configured. In other words, STA MLD1 and AP MLD can configure the maximum NSS for the EMLMR operation. For example, the maximum NSS for the EMLMR operation can be configured to 6.

[0108] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA associated with STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link (e.g., default NSS).

[0109] The initial frame may further include a padding bit corresponding to an EMLMR delay time (e.g., at least one of an EMLMR padding delay or an EMLMR conversion delay) for an RF chain switching time (e.g., a spatial stream reconfiguration time). Since the maximum NSS for the EMLMR operation is configured, the STA can perform transmission and reception operations on a frame (e.g., a data frame) using up to a number of spatial streams corresponding to the maximum NSS after receiving the initial frame. For example, if the maximum NSS for the EMLMR operation is configured to 6, the STA can perform communication using up to 6 spatial streams after receiving the initial frame.

[0110] STA MLD1 may support OMI. AP1 may send an initial frame to STA1-1. AP2 may send an initial frame to STA1-2. STA MLD1 may be a non-simultaneous transmit and receive (NSTR) STA MLD, and the first link and the second link may be an NSTR link pair. On the NSTR link pair, STR operation may not be possible. In this case, when the start time of the initial frame sent on the first link and the second link may be different, the end time of the initial frame sent on the first link and the second link needs to be the same. The initial frame sent by AP1 to STA1-1 may include OMI (e.g., OMI field). The initial frame sent by AP2 to STA1-2 may also include OMI (e.g., OMI field). OMI may be included in the MAC header in the form of A control. OMI may indicate the number of spatial streams used by the STA. The initial frame sent by AP1 may include information indicating that STA1-1 uses 3 spatial streams (e.g., OMI). The initial frame sent by AP2 may include information indicating that STA1-2 uses 3 spatial streams (e.g., OMI).

[0111] STA1-1 may receive an initial frame from AP1 and identify, based on information included in the initial frame, an indication of the use of three spatial streams. STA1-2 may receive an initial frame from AP2 and identify, based on information included in the initial frame, an indication of the use of three spatial streams. In order to use three spatial streams on each of the first link and the second link, an RF chain switching process (e.g., a process of reconfiguring spatial streams) may be performed. For example, the RF chain of STA1-3 (e.g., an RF chain operating on a third link) may be switched to STA1-1 (e.g., a first link operated by STA1-1) and STA1-2 (e.g., a second link operated by STA1-2). After the RF chain switching process is completed, STA1-1 may communicate with AP1 using three spatial streams, and STA1-2 may communicate with AP2 using three spatial streams.

[0112] When communication between STA1-1 and AP1 on the first link and / or communication between STA1-2 and AP2 on the second link is performed, communication between STA1-3 and AP3 on the third link (e.g., communication between STA MLD1 and AP MLD) may not be performed. In other words, if the spatial stream for the third link (e.g., STA1-3 operating on the third link) is not available, communication between STA1-3 and AP3 may not be performed on the third link. The start time of the period during which communication is not performed (e.g., the non-communication period) may be the start time of the initial frame of the receiving AP, the time when the receiver address (RA) of at least one MPDU included in the initial frame is identified as corresponding to STA1-1 or STA1-2, or the end time of receiving the initial frame. As another method, the start time of the non-communication period may start at the time when the spatial stream is not available for STA1-3. When the STA (e.g., STA1-1 or STA1-2) indicated by the RA of the MPDU successfully completes the decoding of the MPDU, the start time of the non-communication period may be identified.

[0113] The end time of the non-communication period may be the time after the EMLMR delay from the transmission time of the last frame on the first link or the second link. If the non-communication period is equal to or longer than a specific time (e.g., aMediumSyncThreshold), the MediumSyncDelay time (e.g., a MediumSyncDelay timer) may start after the non-communication period. When STA MLD1 is STR STA MLD, there will be no problem even if the end times of the frames sent on the first link and the second link are different. In the case where there is no problem even if the end times of the frames sent on the first link and the second link are different, the RF chain may switch to the third link at the time when the reception or transmission of the frame is first completed (e.g., the reception completion time or the transmission completion time of the frame), and normal operation may be performed. In other words, the end time of the non-communication period may be the time when the reception or transmission of the frame on the first link and / or the second link is first completed.

[0114] Figure 6 is a timing diagram illustrating a third exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0115] like Figure 6 As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0116] Each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 can send and receive frames using 2 spatial streams. In other words, the number of spatial streams per link can be 2. The number of spatial streams per link (e.g., 2) can be the initial NSS or default NSS for each link. STA MLD1 and AP MLD can perform a configuration process for EMLMR operation. EMLMR operation can be configured between STA MLD1 and AP MLD. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) can be referred to as an EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) can be referred to as an EMLMR STA. For example, STA MLD1 can be an EMLMR STA MLD, and each of STA1-1, STA1-2, and STA1-3 can be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation can be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operations on the first link, the second link, and the third link, and the first link, the second link, and the third link may be referred to as EMLMR links.

[0117] In the configuration process (e.g., negotiation process) of the EMLMR operation between STA MLD1 and AP MLD, the maximum NSS for the EMLMR operation may be configured. In other words, STA MLD1 and AP MLD may configure the maximum NSS for the EMLMR operation. For example, the maximum NSS for the EMLMR operation may be configured as 4. The maximum NSS (e.g., 4) may be configured to be less than the maximum number of spatial streams supported by STA MLD1. STA MLD1 may configure the maximum NSS for the EMLMR operation to a smaller value in order to perform communication on multiple links.

[0118] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA associated with STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link (e.g., default NSS).

[0119] The initial frame may further include a padding bit corresponding to an EMLMR delay time (e.g., at least one of an EMLMR padding delay or an EMLMR conversion delay) for an RF chain switching time (e.g., a spatial stream reconfiguration time). Since the maximum NSS for the EMLMR operation is configured, the STA can perform transmission and reception operations on a frame (e.g., a data frame) using up to a number of spatial streams corresponding to the maximum NSS after receiving the initial frame. For example, if the maximum NSS for the EMLMR operation is configured as 4, the STA can perform communication using up to 4 spatial streams after receiving the initial frame.

[0120] In the configuration process of the EMLMR operation, the priority of the RF chain on each link for the RF chain switching operation (e.g., the priority of the spatial stream) can be configured. In addition, the RF chain switching scheme (e.g., the scheme for switching the spatial stream) can also be configured during the configuration process of the EMLMR operation. For example, the priority and / or switching scheme of the RF chain can be configured as follows. In the present invention, "RF chain" can be interpreted as having a meaning corresponding to a spatial stream.

[0121] -When the initial frame is received on the first link, the RF chain of the second link can be switched to the first link with priority.

[0122] -When the initial frame is received on the second link, the RF chain of the third link can be switched to the second link with priority.

[0123] -When the initial frame is received on the third link, the RF chain of the second link can be preferentially switched to the third link.

[0124] - Switching scheme (eg, reconfiguration scheme): The RF chain may be used first on a link to which priority is assigned (eg, a link with a high priority or a link receiving an initial frame).

[0125] For example, when STA1-1 of STA MLD1 receives an initial frame on the first link, the RF chain of STA1-2 operating on the second link may be preferentially switched to the first link. Since the maximum NSS for EMLMR operation is 4, STA1-1 may use the RF chain of STA1-2 to perform communication. When STA1-1 performs communication on the first link, STA1-2 may not perform communication on the second link. In other words, due to the reconfiguration of the spatial stream, there are no remaining spatial streams on the second link (e.g., STA1-2 operating on the second link), and therefore STA1-2 may not perform communication on the second link. Based on the preconfigured priority and / or switching scheme, AP MLD1 may determine that there are no remaining RF chains (e.g., no remaining spatial streams) for STA1-2. Therefore, when AP1 of AP MLD performs communication with STA1-1 on the first link, AP2 of AP MLD may not communicate with STA1-2 on the second link.

[0126] The start time of the non-communication period may be the start time of the initial frame of the receiving AP, the time when the RA of at least one MPDU included in the initial frame is identified as corresponding to STA1-1, or the end time of the receiving initial frame. As another method, the start time of the non-communication period may be the time when no spatial stream is available for STA1-2. When the STA (e.g., STA1-1) indicated by the RA of the MPDU successfully completes the decoding of the MPDU, the start time of the non-communication period may be identified. The end time of the non-communication period may be the time after the EMLMR delay from the transmission time of the last frame on the first link. After the non-communication period, the MediumSyncDelay time (e.g., the MediumSyncDelay timer) may start.

[0127] Although the RF chain of STA1-2 has been switched to STA1-1, there may be a remaining RF chain for STA1-3. Therefore, even when STA1-1 performs communication with AP1 on the first link, STA1-3 can perform communication with AP3 using 2 spatial streams. Based on the preconfigured priority and / or switching scheme, AP MLD can identify the remaining RF chain for STA1-3. Therefore, AP3 of AP MLD can communicate with STA1-3 using 2 spatial streams.

[0128] Figure 7 is a timing diagram illustrating a fourth exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0129] like Figure 7As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0130] Each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 can send and receive frames using 2 spatial streams. In other words, the number of spatial streams per link can be 2. The number of spatial streams per link (e.g., 2) can be the initial NSS or default NSS for each link. STA MLD1 and AP MLD can perform a configuration process for EMLMR operation. EMLMR operation can be configured between STA MLD1 and AP MLD. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) can be referred to as an EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) can be referred to as an EMLMR STA. For example, STA MLD1 can be an EMLMR STA MLD, and each of STA1-1, STA1-2, and STA1-3 can be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation can be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operations on the first link, the second link, and the third link, and the first link, the second link, and the third link may be referred to as EMLMR links.

[0131] In the configuration process (e.g., negotiation process) of the EMLMR operation between STA MLD1 and AP MLD, the maximum NSS for the EMLMR operation may be configured. In other words, STA MLD1 and AP MLD may configure the maximum NSS for the EMLMR operation. For example, the maximum NSS for the EMLMR operation may be configured as 4. The maximum NSS (e.g., 4) may be configured to be less than the maximum number of spatial streams supported by STA MLD1. STA MLD1 may configure the maximum NSS for the EMLMR operation to a smaller value in order to perform communication on multiple links.

[0132] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA associated with STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link (e.g., default NSS).

[0133] The initial frame may further include a padding bit corresponding to an EMLMR delay time (e.g., at least one of an EMLMR padding delay or an EMLMR conversion delay) for an RF chain switching time (e.g., a spatial stream reconfiguration time). Since the maximum NSS for the EMLMR operation is configured, the STA can perform transmission and reception operations on a frame (e.g., a data frame) using up to a number of spatial streams corresponding to the maximum NSS after receiving the initial frame. For example, if the maximum NSS for the EMLMR operation is configured as 4, the STA can perform communication using up to 4 spatial streams after receiving the initial frame.

[0134] In the configuration process of the EMLMR operation, the priority of the RF chain on each link for the RF chain switching operation (e.g., the priority of the spatial stream) can be configured. In addition, the RF chain switching scheme (e.g., the scheme for switching the spatial stream) can also be configured during the configuration process of the EMLMR operation. For example, the priority and / or switching scheme of the RF chain can be configured as follows. In the present invention, "RF chain" can be interpreted as having a meaning corresponding to a spatial stream.

[0135] -When the initial frame is received on the first link, the RF chain of the second link can be switched to the first link with priority.

[0136] -When the initial frame is received on the second link, the RF chain of the third link can be switched to the second link with priority.

[0137] -When the initial frame is received on the third link, the RF chain of the second link can be preferentially switched to the third link.

[0138] -Switching scheme (e.g., reconfiguration scheme): When performing an RF chain switching operation, the RF chain switching operation may be performed so that at least one RF chain remains on each link. In certain cases, after performing the RF chain switching operation, a link without any RF chain may appear.

[0139] For example, when STA1-1 of STA MLD1 receives an initial frame on the first link, the RF chain of STA1-2 operating on the second link can be switched to the first link preferentially. According to the RF chain switching scheme, the RF chain switching operation can be performed so that at least one RF chain remains on each link. Accordingly, of the two RF chains of STA1-2 operating on the second link, one RF chain can be switched to the first link, and one RF chain can remain on STA1-2. In addition, in order to allow STA1-1 to use 4 spatial streams, the RF chain of STA1-3 operating on the third link can be switched to the first link. For example, considering the RF chain switching scheme, of the two RF chains of STA1-3 operating on the third link, one RF chain can be switched to the first link, and one RF chain can remain on STA1-3.

[0140] According to the RF chain switching operation, STA1-1 may have 4 RF chains, STA1-2 may have one RF chain, and STA1-3 may have one RF chain. STA1-1 may communicate with AP1 using 4 spatial streams, STA1-2 may communicate with AP2 using one spatial stream, and STA1-3 may communicate with AP3 using one spatial stream. Based on the preconfigured priority and / or switching scheme, AP MLD1 may determine that there is one RF chain for each of STA1-2 and STA1-3. When communication between AP1 and STA1-1 is performed on the first link, communication between AP2 and STA1-2 on the second link may be performed using one spatial stream, and communication between AP3 and STA1-3 on the third link may also be performed using one spatial stream. Since STA1-2 and STA1-3 have each successfully sent and received frames on the second link and the third link, respectively, they may not lose medium synchronization. Accordingly, the MediumSyncDelay time may not be applied to communications on the second link and the third link, respectively.

[0141] Figure 8 is a timing diagram illustrating a fifth exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0142] like Figure 8 As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0143] Each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 can send and receive frames using 2 spatial streams. In other words, the number of spatial streams per link can be 2. The number of spatial streams per link (e.g., 2) can be the initial NSS or default NSS for each link. STA MLD1 and AP MLD can perform a configuration process for EMLMR operation. EMLMR operation can be configured between STA MLD1 and AP MLD. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) can be referred to as an EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) can be referred to as an EMLMR STA. For example, STA MLD1 can be an EMLMR STA MLD, and each of STA1-1, STA1-2, and STA1-3 can be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation can be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operations on the first link, the second link, and the third link, and the first link, the second link, and the third link may be referred to as EMLMR links.

[0144] In the configuration process (e.g., negotiation process) of the EMLMR operation between STA MLD1 and AP MLD, the maximum NSS for the EMLMR operation may be configured. In other words, STA MLD1 and AP MLD may configure the maximum NSS for the EMLMR operation. For example, the maximum NSS for the EMLMR operation may be configured to be 5. The maximum NSS (e.g., 5) may be configured to be less than the maximum number of spatial streams supported by STA MLD1. STA MLD1 may configure the maximum NSS for the EMLMR operation to a smaller value in order to perform communication on multiple links.

[0145] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA associated with STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link (e.g., default NSS).

[0146] The initial frame may further include padding bits corresponding to an EMLMR delay time (e.g., at least one of an EMLMR padding delay or an EMLMR conversion delay) for an RF chain switching time (e.g., a spatial stream reconfiguration time). Since the maximum NSS for the EMLMR operation is configured, the STA can perform transmission and reception operations on a frame (e.g., a data frame) using up to the number of spatial streams corresponding to the maximum NSS after receiving the initial frame. For example, if the maximum NSS for the EMLMR operation is configured to 5, the STA can perform communication using up to 5 spatial streams after receiving the initial frame.

[0147] In the configuration process of the EMLMR operation, the priority of the RF chain on each link for the RF chain switching operation (e.g., the priority of the spatial stream) can be configured. In addition, the RF chain switching scheme (e.g., the scheme for switching the spatial stream) can also be configured during the configuration process of the EMLMR operation. For example, the priority and / or switching scheme of the RF chain can be configured as follows. In the present invention, "RF chain" can be interpreted as having a meaning corresponding to a spatial stream.

[0148] -When the initial frame is received on the first link, the RF chain of the second link can be switched to the first link with priority.

[0149] -When the initial frame is received on the second link, the RF chain of the third link can be switched to the second link with priority.

[0150] -When the initial frame is received on the third link, the RF chain of the second link can be preferentially switched to the third link.

[0151] -Switching scheme (eg, reconfiguration scheme): When performing an RF chain switching operation, the RF chain switching operation may be performed so that at least one RF chain is retained on each link. In certain cases, after performing the RF chain switching operation, a link without any RF chain may appear.

[0152] For example, when STA1-1 of STA MLD1 receives an initial frame on the first link, the RF chain of STA1-2 operating on the second link can be preferentially switched to the first link. According to the RF chain switching scheme, the RF chain switching operation can be performed so that at least one RF chain is retained on each link. Therefore, of the two RF chains of STA1-2 operating on the second link, one RF chain can be switched to the first link, and one RF chain can remain with STA1-2. In addition, the RF chain of STA1-3 operating on the third link can be switched to the first link. For example, considering the RF chain switching scheme, of the two RF chains of STA1-3 operating on the third link, one RF chain can be switched to the first link, and one RF chain can remain with STA1-3.

[0153] According to the RF chain switching operation, STA1-1 may have 4 RF chains, STA1-2 may have one RF chain, and STA1-3 may have one RF chain. In order to use 5 spatial streams, STA1-1 may need an additional RF chain. In this case, based on the priority of the RF chain, the remaining RF chain of STA1-2 may be switched to the first link. According to the RF chain switching operation, STA1-1 may have 5 RF chains, STA1-2 may have no RF chain, and STA1-3 may have one RF chain.

[0154] STA1-1 can communicate with AP1 using 5 spatial streams, and STA1-3 can communicate with AP3 using one spatial stream. When communication between STA1-1 and AP1 is performed on the first link, STA1-2 may not be able to communicate with AP2 on the second link. In other words, since there are no remaining spatial streams on the second link (e.g., STA1-2 operating on the second link), STA1-2 may not be able to communicate with AP2 on the second link. AP MLD1 may determine that no RF chain is available for STA1-2 based on a preconfigured priority and / or switching scheme, and one RF chain is available for STA1-3. When communication between STA1-1 and AP1 is performed on the first link, communication between STA1-3 and AP3 on the third link may be performed using one spatial stream. Since STA1-3 has successfully sent and received frames and has not lost medium synchronization, the MediumSyncDelay time may not be applied to communication on the third link. STA1-2 may communicate after the EMLMR delay from the end time of the communication between STA1-1 and AP1. Since STA1 - 2 does not monitor the channel for a certain period of time, a MediumSyncDelay time (eg, a MediumSyncDelay timer) may be applied to communications on the second link.

[0155] Fig. 9 is a timing diagram illustrating a sixth exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0156] like Fig. 9 As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0157] Each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 can send and receive frames using 2 spatial streams. In other words, the number of spatial streams per link can be 2. The number of spatial streams per link (e.g., 2) can be the initial NSS or default NSS for each link. STA MLD1 and AP MLD can perform a configuration process for EMLMR operation. EMLMR operation can be configured between STA MLD1 and AP MLD. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) can be referred to as an EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) can be referred to as an EMLMR STA. For example, STA MLD1 can be an EMLMR STA MLD, and each of STA1-1, STA1-2, and STA1-3 can be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation can be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operations on the first link, the second link, and the third link, and the first link, the second link, and the third link may be referred to as EMLMR links.

[0158] In the configuration process (e.g., negotiation process) of the EMLMR operation between STA MLD1 and AP MLD, the maximum NSS for the EMLMR operation can be configured. In other words, STA MLD1 and AP MLD can configure the maximum NSS for the EMLMR operation. For example, the maximum NSS for the EMLMR operation can be configured to 6.

[0159] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA associated with STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link (e.g., default NSS).

[0160] When the maximum NSS for EMLMR operation is configured, the STA can communicate using up to the number of spatial streams corresponding to the maximum NSS after receiving the initial frame. The initial frame may further include a padding bit corresponding to the EMLMR delay time (e.g., at least one of the EMLMR padding delay or the EMLMR conversion delay) for the RF chain switching time (e.g., the spatial stream reconfiguration time). For example, if the maximum NSS for EMLMR operation is configured to 6, the STA can perform communication using up to 6 spatial streams after receiving the initial frame.

[0161] STA MLD1 may support OMI. STA1-1 may send a receiving operating mode (ROM) indicating NSS=3 to AP1. In other words, STA1-1 may indicate ROM to AP1. In the present invention, the sending of ROM may refer to the sending of a frame including ROM. ROM (e.g., ROM indication) may be OMI included in an uplink frame in the form of A control. AP1 may receive ROM (e.g., ROM indication) from STA1-1. AP1 may send a frame to STA1-1 in the next transmit opportunity (TXOP) based on the information indicated by ROM. Based on the above process or a process similar to the above process, STA1-2 may indicate ROM to AP2, and STA1-3 may indicate ROM to AP3. The ROM sent by STA1-2 may indicate NSS=2, and the ROM sent by STA1-3 may indicate NSS=3.

[0162] The AP of AP MLD may perform an EMLMR operation based on the NSS indicated by the latest ROM received from the STA of STA MLD1. For example, the latest ROM received by the AP from the STA may be the ROM received by AP3 from STA1-3, and the ROM may indicate NSS=3. AP3 may send an initial frame to STA1-3, and after the transmission of the initial frame, may communicate using up to 3 spatial streams. STA1-3 may prepare to communicate using 3 or fewer spatial streams.

[0163] In the configuration process of EMLMR operation, the priority of the RF chain (e.g., the priority of the spatial stream) for the RF chain switching operation on each link can be configured. For example, the priority of the RF chain can be configured as follows. In the present invention, the meanings of "RF chain" and "spatial stream" can be used interchangeably.

[0164] In the configuration process of EMLMR operation, the priority of the RF chain on each link for RF chain switching operation (e.g., the priority of the spatial stream) can be configured. For example, the priority and / or switching scheme of the RF chain can be configured as follows. In the present invention, "RF chain" can be interpreted as having a meaning corresponding to a spatial stream.

[0165] -When the initial frame is received on the first link, the RF chain of the second link can be switched to the first link with priority.

[0166] -When the initial frame is received on the second link, the RF chain of the third link can be switched to the second link with priority.

[0167] -When the initial frame is received on the third link, the RF chain of the second link can be preferentially switched to the third link.

[0168] For example, the last ROM sent by STA1-3 to AP3 may indicate NSS=3, and the last ROM sent by STA1-1 to AP1 may indicate NSS=3. When STA1-1 and STA1-3 receive the initial frame, the RF chain of STA1-2 may be switched to STA1-1 and STA1-3 according to their priorities. After the RF chain switching operation is completed, STA1-1 and STA1-3 may each communicate using 3 spatial streams. AP1 may send frames using spatial streams, the number of which is equal to or less than the NSS indicated by the latest ROM received from STA1-1. AP3 may send frames using multiple spatial streams, the number of which is equal to or less than the NSS indicated by the latest ROM received from STA1-3.

[0169] If the RF chain of STA1-2 is switched to STA1-1 and STA1-3, STA1-2 may not have any available RF chain (e.g., spatial stream). In this case, STA1-2 may not be able to communicate. In other words, the non-communication period may occur on the second link operated by STA1-2. After the non-communication period ends, STA1-2 may apply the MediumSyncDelay time. AP MLD may identify the number of spatial streams available for each STA of STA MLD1 based on the preconfigured priority, and send frames to each STA of STA MLD1 based on the number of identified spatial streams.

[0170] Fig.10 is a timing diagram illustrating a seventh exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0171] like Fig.10As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0172] Each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 can send and receive frames using 2 spatial streams. In other words, the number of spatial streams per link can be 2. The number of spatial streams per link (e.g., 2) can be the initial NSS or default NSS for each link. STA MLD1 and AP MLD can perform a configuration process for EMLMR operation. EMLMR operation can be configured between STA MLD1 and AP MLD. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) can be referred to as an EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) can be referred to as an EMLMR STA. For example, STA MLD1 can be an EMLMR STA MLD, and each of STA1-1, STA1-2, and STA1-3 can be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation can be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operations on the first link, the second link, and the third link, and the first link, the second link, and the third link may be referred to as EMLMR links.

[0173] In the configuration process (e.g., negotiation process) of the EMLMR operation between STA MLD1 and AP MLD, the maximum NSS for the EMLMR operation can be configured. In other words, STA MLD1 and AP MLD can configure the maximum NSS for the EMLMR operation. For example, the maximum NSS for the EMLMR operation can be configured to 6.

[0174] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA associated with STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link (e.g., default NSS).

[0175] When the maximum NSS for EMLMR operation is configured, the STA can communicate using up to the number of spatial streams corresponding to the maximum NSS after receiving the initial frame. The initial frame may further include a padding bit corresponding to the EMLMR delay time (e.g., at least one of the EMLMR padding delay or the EMLMR conversion delay) for the RF chain switching time (e.g., the spatial stream reconfiguration time). For example, if the maximum NSS for EMLMR operation is configured to 6, the STA can perform communication using up to 6 spatial streams after receiving the initial frame.

[0176] STA MLD1 may support OMI. STA1-1 may send a ROM indicating NSS=4 to AP1. In other words, STA1-1 may indicate ROM to AP1. In the present invention, the sending of ROM may refer to the sending of a frame including ROM. ROM (e.g., ROM indication) may be OMI included in an uplink frame in the form of A control. AP1 may receive ROM (e.g., ROM indication) from STA1-1. AP1 may send a frame to STA1-1 in the next TXOP based on the information indicated by ROM. STAs other than STA1-1 (e.g., STA1-2 and / or STA1-3) may not send ROM.

[0177] The AP of AP MLD may perform an EMLMR operation based on the NSS indicated by the latest ROM received from the STA of STA MLD1. For example, the latest ROM received by AP1 from STA1-1 may indicate NSS=4. AP1 may send an initial frame to STA1-1, and after the transmission of the initial frame, may communicate using up to 4 spatial streams. STA1-1 may prepare to communicate using up to 4 spatial streams.

[0178] In the configuration process of the EMLMR operation, the priority of the RF chain on each link for the RF chain switching operation (e.g., the priority of the spatial stream) can be configured. In addition, the RF chain switching scheme (e.g., the scheme for switching the spatial stream) can also be configured during the configuration process of the EMLMR operation. For example, the priority and / or switching scheme of the RF chain can be configured as follows. In the present invention, "RF chain" can be interpreted as having a meaning corresponding to a spatial stream.

[0179] -When the initial frame is received on the first link, the RF chain of the second link can be switched to the first link with priority.

[0180] -When the initial frame is received on the second link, the RF chain of the third link can be switched to the second link with priority.

[0181] -When the initial frame is received on the third link, the RF chain of the second link can be preferentially switched to the third link.

[0182] - Switching scheme (eg, reconfiguration scheme): The RF chain may be used first on a link to which priority is assigned (eg, a link with a high priority or a link receiving an initial frame).

[0183] For example, when STA1-1 of STA MLD1 receives an initial frame from AP1 on the first link, the RF chain of STA1-2 operating on the second link may be preferentially switched to the first link. Since the NSS for the EMLMR operation of STA1-1 is configured to 4 by ROM, the RF chain of STA1-2 may be switched to STA1-1. In this case, all RF chains (e.g., two RF chains) of STA1-2 may be switched to STA1-1. Therefore, when communication between STA1-1 and AP1 is performed on the first link, STA1-2 may not perform communication on the second link. In other words, due to the reconfiguration of the spatial stream, there are no remaining spatial streams (e.g., STA1-2 operating on the second link) on the second link, and STA1-2 may not perform communication on the second link. AP MLD1 may recognize that there are no remaining RF chains for STA1-2 based on the preconfigured priority and / or switching scheme. In this case, when communication between AP1 and STA1-1 is performed on the first link, AP2 may not send frames to STA1-2 on the second link. In other words, a non-communication period may occur on the second link.

[0184] The start time of the non-communication period may be the start time of the initial frame of the receiving AP, the time when the RA of at least one MPDU included in the initial frame is identified as corresponding to STA1-1, or the end time of the receiving initial frame. As another method, the start time of the non-communication period may start from the time when no spatial stream is available for STA1-2. When the STA (e.g., STA1-1) indicated by the RA of the MPDU successfully completes the decoding of the MPDU, the start time of the non-communication period can be identified. The end time of the non-communication period may be the time after the EMLMR delay from the transmission time of the last frame on the first link. After the non-communication period, the MediumSyncDelay time (e.g., the MediumSyncDelay timer) may start.

[0185] There may be two RF chains for STA1-3. Therefore, when communication between STA1-1 and AP1 is performed on the first link, STA1-3 may communicate with AP3 using 2 spatial streams. AP MLD1 may recognize that there are remaining RF chains (e.g., two RF chains) for STA1-3 based on a preconfigured priority and / or switching scheme. In this case, when communication between AP1 and STA1-1 is performed on the first link, AP3 may communicate with STA1-3 using 2 spatial streams.

[0186] Fig.11 is a timing diagram illustrating an eighth exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation.

[0187] like Fig.11 As shown, AP1, AP2, and AP3 may be APs associated with AP MLD. AP1 may operate on a first link, AP2 may operate on a second link, and AP3 may operate on a third link. STA1-1, STA1-2, and STA1-3 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, STA1-2 may operate on a second link, and STA1-3 may operate on a third link.

[0188] Each of STA1-1, STA1-2, and STA1-3 associated with STA MLD1 can send and receive frames using 2 spatial streams. In other words, the number of spatial streams per link can be 2. The number of spatial streams per link (e.g., 2) can be the initial NSS or default NSS for each link. STA MLD1 and AP MLD can perform a configuration process for EMLMR operation. EMLMR operation can be configured between STA MLD1 and AP MLD. A STA MLD configured with EMLMR operation (e.g., a STA MLD supporting EMLMR operation) can be referred to as an EMLMR STA MLD. A STA configured with EMLMR operation (e.g., a STA supporting EMLMR operation) can be referred to as an EMLMR STA. For example, STA MLD1 can be an EMLMR STA MLD, and each of STA1-1, STA1-2, and STA1-3 can be an EMLMR STA. A link on which the EMLMR STA MLD performs EMLMR operation can be referred to as an EMLMR link. For example, STA MLD1 may perform EMLMR operations on the first link, the second link, and the third link, and the first link, the second link, and the third link may be referred to as EMLMR links.

[0189] In the configuration process (e.g., negotiation process) of the EMLMR operation between STA MLD1 and AP MLD, the maximum NSS for the EMLMR operation can be configured. In other words, STA MLD1 and AP MLD can configure the maximum NSS for the EMLMR operation. For example, the maximum NSS for the EMLMR operation can be configured to 6.

[0190] When the EMLMR operation is configured and STA MLD1 (e.g., each STA associated with STA MLD1) receives an initial frame from AP MLD (e.g., each AP associated with AP MLD), STA MLD1 may switch the RF chain operating on other links to the link receiving the initial frame. In other words, the spatial streams configured for other links may be reconfigured for the link receiving the initial frame. The number of spatial streams used to send the initial frame may be equal to or less than the number of spatial streams available to each STA associated with STA MLD. The number of spatial streams available to each STA may correspond to the number of spatial streams available to each link (e.g., default NSS).

[0191] When the maximum NSS for EMLMR operation is configured, the STA can communicate using up to the number of streams corresponding to the maximum NSS after receiving the initial frame. The initial frame may further include a padding bit corresponding to the EMLMR delay time (e.g., at least one of the EMLMR padding delay or the EMLMR conversion delay) for the RF chain switching time. For example, if the maximum NSS for EMLMR operation is configured to 6, the STA can perform communication using up to 6 spatial streams after receiving the initial frame.

[0192] STA MLD1 may support OMI. STA1-1 may send a ROM indicating NSS=4 to AP1. In other words, STA1-1 may indicate ROM to AP1. ROM (e.g., ROM indication) may be OMI included in an uplink frame in the form of A control. AP1 may receive ROM (e.g., ROM indication) from STA1-1. AP1 may send a frame to STA1-1 in the next TXOP based on the information indicated by ROM. STAs other than STA1-1 (e.g., STA1-2 and / or STA1-3) may not send ROM.

[0193] The AP of AP MLD may perform an EMLMR operation based on the NSS indicated by the latest ROM received from the STA of STA MLD1. For example, the latest ROM received by AP1 from STA1-1 may indicate NSS=4. AP1 may send an initial frame to STA1-1, and after the transmission of the initial frame, may communicate using up to 4 spatial streams. STA1-1 may prepare to communicate using up to 4 spatial streams.

[0194] In the configuration process of the EMLMR operation, the priority of the RF chain on each link for the RF chain switching operation (e.g., the priority of the spatial stream) can be configured. In addition, the RF chain switching scheme (e.g., the scheme for switching the spatial stream) can also be configured during the configuration process of the EMLMR operation. For example, the priority and / or switching scheme of the RF chain can be configured as follows. In the present invention, "RF chain" can be interpreted as having a meaning corresponding to a spatial stream.

[0195] -When the initial frame is received on the first link, the RF chain of the second link can be switched to the first link with priority.

[0196] -When the initial frame is received on the second link, the RF chain of the third link can be switched to the second link with priority.

[0197] -When the initial frame is received on the third link, the RF chain of the second link can be preferentially switched to the third link.

[0198] -Switching scheme (e.g., reconfiguration scheme): When performing an RF chain switching operation, the RF chain switching operation may be performed so that at least one RF chain remains on each link. In certain cases, after performing the RF chain switching operation, a link without any RF chain may appear.

[0199] For example, when STA1-1 of STA MLD1 receives an initial frame on the first link, the RF chain of STA1-2 operating on the second link can be preferentially switched to the first link. According to the RF chain switching scheme, the RF chain switching operation can be performed so that at least one RF chain remains on each link. Therefore, of the two RF chains of STA1-2 operating on the second link, one RF chain can be switched to the first link, and one RF chain can remain with STA1-2. In addition, in order for STA1-1 to use 4 spatial streams, the RF chain of STA1-3 operating on the third link can be switched to the first link. For example, considering the RF chain switching scheme, of the two RF chains of STA1-3 operating on the third link, one RF chain can be switched to the first link, and one RF chain can be retained with STA1-3.

[0200] According to the RF chain switching operation, STA1-1 may have 4 RF chains, STA1-2 may have one RF chain, and STA1-3 may have one RF chain. STA1-1 may communicate with AP1 using 4 spatial streams, STA1-2 may communicate with AP2 using one spatial stream, and STA1-3 may communicate with AP3 using one spatial stream. AP MLD1 may determine that there is one RF chain for each of STA1-2 and STA1-3 based on a preconfigured priority and / or switching scheme. When communication between AP1 and STA1-1 is performed on the first link, communication between AP2 and STA1-2 on the second link may be performed using one spatial stream, and communication between AP3 and STA1-3 on the third link may be performed using one spatial stream. STA1-2 and STA1-3 may each perform frame transmission and reception on the second link and the third link, respectively, without losing medium synchronization. Therefore, the MediumSyncDelay time may not be applied to communications on the second link and the third link.

[0201] Fig.12 is a timing diagram showing a first exemplary embodiment of multi-link communication in a wireless local area network supporting EMLMR operation and EMLSR operation.

[0202] like Fig.12As shown, AP1 and AP2 may be APs associated with AP MLD. AP1 may operate on a first link, and AP2 may operate on a second link. STA1-1 and STA1-2 may be STAs associated with STA MLD1. STA1-1 may operate on a first link, and STA1-2 may operate on a second link. The first link and the second link may be an STR link pair. STR operation is possible in the STR link pair. STA MLD1 may perform EMLSR operation and EMLMR operation on the first link and the second link. The link that performs the EMLSR operation may be an EMLSR link, and the link that performs the EMLMR operation may be an EMLMR link. STA MLD1 may perform a configuration process of an EMLSR operation or an EMLMR operation with AP MLD. In other words, an EMLSR operation or an EMLMR operation may be configured between STA MLD1 and AP MLD.

[0203] Based on the EMLSR operation and / or the EMLMR operation, when STA MLD1 performs communication on the first link, communication on the second link may not be performed. Similarly, based on the EMLSR operation and / or the EMLMR operation, when STA MLD1 performs communication on the second link, communication on the first link may not be performed. If communication (e.g., frame transmission and reception) is performed between the AP MLD and the STA MLD1 on the first link, communication on the second link may not be performed. If communication is performed between the AP MLD and the STA MLD1 on the first link, the ongoing communication on the second link (e.g., the operation of sending a frame to STA1-2) may be suspended. If communication is performed between the AP MLD and the STA MLD1 on the second link (e.g., frame transmission and reception), communication on the first link may not be performed. If communication is performed between the AP MLD and the STA MLD2 on the second link, the ongoing communication on the first link (e.g., the operation of sending a frame to STA1-1) may be suspended.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] 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.

[0208] 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: Configure the maximum number of spatial streams (NSS) for enhanced multi-link multi-radio (EMLMR) operation using access point (AP) MLD; receiving, from the AP MLD on the first link, an instruction to utilize n spatial streams equal to or less than the maximum NSS; as well as Communicate with AP MLD using n spatial streams on the first link. Wherein, n is a natural number.

2. The method according to claim 1, further comprising: The maximum NSS-n spatial streams are used to communicate with the AP MLD on the second link.

3. The method according to claim 1, wherein: When the maximum NSS-n is 0, communication between the STA MLD and the AP MLD is not performed on links other than the first link.

4. The method according to claim 1, further comprising: Communicate with the AP MLD using the number of spatial streams corresponding to the default NSS on each link. Among them, when the EMLMR operation is configured and the maximum NSS is configured, communication between the STA MLD and the AP MLD on each link is performed using a number of spatial streams equal to or smaller than the maximum NSS.

5. The method according to claim 4, wherein: When n exceeds the default NSS, one or more spatial streams configured for links other than the first link are reconfigured for the first link, and a sum of the number of the one or more spatial streams and the default NSS is n.

6. The method according to claim 5, wherein: Reconfiguration of the one or more spatial streams is performed based on at least one of a priority or a reconfiguration scheme of the spatial streams on each link.

7. The method according to claim 1, further comprising: Configure the maximum power saving (PS)-NSS for power saving operation with AP MLD, When performing energy saving operations on links other than the first link, communication between the STA MLD and the AP MLD on the first link is performed using a number of spatial streams equal to or less than the maximum PS-NSS, and the maximum PS-NSS is configured to be less than the maximum NSS.

8. The method according to claim 1, wherein: The initial frame received from the AP MLD on the first link includes instructions to utilize n spatial streams.

9. The method according to claim 1, wherein: The maximum NSS is configured during the configuration process of the EMLMR operation between the STA MLD and the AP MLD.

10. A method of station (STA) multi-link device (MLD), comprising: Configure the maximum number of spatial streams (NSS) for enhanced multi-link multi-radio (EMLMR) operation using access point (AP) MLD; Sending an instruction to the AP MLD on the first link to use n spatial streams equal to or less than the maximum NSS; as well as Communicate with AP MLD using n spatial streams on the first link. Wherein, n is a natural number.

11. The method according to claim 10, further comprising: The maximum NSS-n spatial streams are used to communicate with the AP MLD on the second link.

12. The method according to claim 10, wherein: When the maximum NSS-n is 0, communication between the STA MLD and the AP MLD is not performed on links other than the first link.

13. The method according to claim 10, further comprising: Communicate with the AP MLD using the number of spatial streams corresponding to the default NSS on each link. Among them, when the EMLMR operation is configured and the maximum NSS is configured, communication between the STA MLD and the AP MLD on each link is performed using a number of spatial streams equal to or smaller than the maximum NSS.

14. The method according to claim 13, wherein: When n exceeds the default NSS, one or more spatial streams configured for links other than the first link are reconfigured for the first link, and a sum of the number of the one or more spatial streams and the default NSS is n.

15. The method according to claim 14, wherein: Reconfiguration of the one or more spatial streams is performed based on at least one of a priority or a reconfiguration scheme of the spatial streams on each link.

16. A method of access point (AP) multi-link device (MLD), comprising: Configure the maximum number of spatial streams (NSS) for enhanced multi-link multi-radio (EMLMR) operation using station (STA) MLD; Sending an instruction to the STA MLD on the first link to use n spatial streams equal to or less than the maximum NSS; as well as Communicate with STA MLD using n spatial streams on the first link, Wherein, n is a natural number.

17. The method according to claim 16, further comprising: The maximum number of NSS-n spatial streams is used to communicate with the STA MLD on the second link.

18. The method according to claim 16, wherein: When the maximum NSS-n is 0, communication between the STA MLD and the AP MLD is not performed on links other than the first link.

19. The method according to claim 16, further comprising: Communicate with the STA MLD using the number of spatial streams corresponding to the default NSS on each link, Among them, when the EMLMR operation is configured and the maximum NSS is configured, communication between the STA MLD and the AP MLD on each link is performed using a number of spatial streams equal to or smaller than the maximum NSS.

20. The method of claim 16, further comprising: Configure the maximum power saving (PS)-NSS for power saving operation with AP MLD, When performing energy saving operations on links other than the first link, communication between the STA MLD and the AP MLD on the first link is performed using a number of spatial streams equal to or less than the maximum PS-NSS, and the maximum PS-NSS is configured to be less than the maximum NSS.

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