Method and apparatus for updating parameters in roaming procedure of wireless local area network

Abstract

Disclosed are a method and apparatus for updating parameters in a roaming procedure of a wireless local area network. The method performed by a first AP includes the steps of: transmitting a DS mapping request frame to a first DS to which the first AP belongs for a roaming procedure of a STA; and receiving a DS mapping response frame indicating that a DS mapping procedure is completed from the first DS, wherein the DS to which the STA is mapped is changed from the first DS to a second DS to which a second AP belongs when the DS mapping procedure has been completed, the first AP is a serving AP, and the second AP is a target AP.

Description

Technical Field

[0001] This invention relates to a communication technology in a wireless local area network (WLAN), and more specifically, to a technology for updating parameters during roaming. Background Technology

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

[0003] The standard for wireless LAN technology was primarily developed by the Institute of Electrical and Electronics Engineers (IEEE) into the IEEE 802.11 standard. As wireless LAN technology has been developed and widely adopted, its applications have diversified, and there is a growing demand for wireless LAN technologies that support high throughput and / or high reliability.

[0004] With the emergence of applications requiring high throughput and / or real-time transmission, wireless LANs can leverage extended frequency bandwidth and efficient retransmission operations to support communication. Furthermore, wireless LANs can support simultaneous operation of multiple channels or multiple links. The IEEE 802.11 bn standard, as an ultra-high reliability (UHR) wireless LAN technology, is being developed in single basic service set (BSS) and / or overlapped BSS environments. The IEEE 802.11 bn standard aims to improve data transmission rates, enhance latency performance, and / or reduce data error rates. The IEEE 802.11 bn standard supports low-power operation and peer-to-peer communication.

[0005] In a wireless LAN, multiple access points (APs) can exist, and stations (STAs) can move between APs. Whenever a STA moves between APs, it performs a roaming process. During roaming, parameters may need to be modified (e.g., updated). Delaying parameter modification during roaming can reduce communication efficiency and increase latency. In other words, the reliability of the wireless LAN may not be guaranteed. Summary of the Invention

[0006] Technical issues To address the aforementioned problems, the present invention aims to provide a method and apparatus for updating parameters during roaming in a wireless local area network.

[0007] Technical solution A method for achieving the above objectives using a first access point (AP) according to an embodiment of the present invention includes: sending a DS mapping request frame to a first distributed system (DS) to which the first AP belongs for a roaming process of a station (STA), and receiving a DS mapping response frame from the first DS indicating completion of the DS mapping process, wherein, when the DS mapping process is completed, the DS mapped to the STA is changed from the first DS to a second DS to which a second AP belongs, the first AP being a serving AP and the second AP being a target AP.

[0008] When the DS mapping process is completed, the transmission path for packets used by the STA can be changed from the path from STA to the first AP to the first DS to the path from STA to the second AP to the second DS.

[0009] The method of the first AP may further include sending information to the second AP indicating that the DS mapping process is complete.

[0010] When the first DS to which the first AP belongs is different from the second DS to which the second AP belongs, the DS mapping process can be executed.

[0011] The DS request frame may include at least one of the following: information about the second AP, information about the second DS, or information about the STA.

[0012] A DS mapping request frame can be an Address Resolution Protocol (ARP) request frame, and a DS mapping response frame can be an ARP response frame.

[0013] The method of the first AP may further include receiving a roaming request frame from a STA connected to the first AP and sending a roaming response frame to the STA as a response to the roaming request frame.

[0014] The method of the first AP may further include executing a process of exchanging roaming information with the second AP when a roaming request frame is received.

[0015] The roaming response frame may include information indicating that the second AP accepts the roaming procedure.

[0016] STA can be a STA associated with a STA multi-link device (MLD), the first AP can be an AP associated with a first AP MLD, and the second AP can be an AP associated with a second AP MLD.

[0017] A method for achieving the above objectives using a second access point (AP) according to an embodiment of the present invention includes: sending a DS mapping request frame to a second distributed system (DS) to which the second AP belongs for a roaming process of a station (STA), and receiving a DS mapping response frame from the second DS indicating completion of the DS mapping process, wherein, when the DS mapping process is completed, the DS mapped to the STA is changed from a first DS to which the first AP belongs to the second DS, the first AP being a serving AP and the second AP being a target AP.

[0018] When the DS mapping process is completed, the transmission path for packets used by the STA can be changed from the path from STA to the first AP to the first DS to the path from STA to the second AP to the second DS.

[0019] The method of the second AP may further include sending information to the first AP indicating that the DS mapping process is complete.

[0020] When the first DS to which the first AP belongs is different from the second DS to which the second AP belongs, the DS mapping process can be executed.

[0021] The DS request frame may include at least one of the following: information about the first AP, information about the first DS, or information about the STA.

[0022] A DS mapping request frame can be an Address Resolution Protocol (ARP) request frame, and a DS mapping response frame can be an ARP response frame.

[0023] The method of the second AP may further include executing a process of exchanging roaming information with the first AP when the STA requests to initiate a roaming process.

[0024] The method of the second AP may further include executing the association process between the second AP and the STA when the second AP accepts the roaming process of the STA.

[0025] The association process between the second AP and the STA may include receiving an establishment request frame from the STA and sending an establishment response frame to the STA as a response to the establishment request frame.

[0026] STA can be a STA associated with a STA multi-link device (MLD), the first AP can be an AP associated with a first AP MLD, and the second AP can be an AP associated with a second AP MLD.

[0027] Beneficial effects According to the present invention, the STA can move between APs. In other words, the STA can perform a roaming procedure. Before performing the roaming procedure, the STA can send information to the APs (e.g., the current AP and / or the target AP) about the time of the roaming procedure, information about the target AP, and / or information about the current Internet Protocol (IP) address. The AP can support the update operation of the STA's parameters (e.g., association information, IP address, etc.) based on the information received from the STA. In other words, the STA can quickly update parameters during the roaming procedure based on the AP's support. Accordingly, the roaming procedure can be performed quickly in the wireless LAN, and the transmission efficiency in the wireless LAN can be enhanced. Attached Figure Description

[0028] Figure 1 This is a block diagram illustrating a first embodiment of a communication node constituting a wireless local area network system.

[0029] Figure 2 This is a conceptual diagram illustrating a first embodiment of multiple links configured between multi-link devices (MLDs).

[0030] Figure 3 This is a timing diagram illustrating the parameter exchange method in the roaming process.

[0031] Figure 4 This is a timing diagram illustrating the parameter exchange method in the roaming process.

[0032] Figure 5 This is a timing diagram illustrating the ARP method in the roaming process.

[0033] Figure 6 This is a timing diagram illustrating the ARP method in the roaming process.

[0034] Figure 7 This is a timing diagram illustrating the ARP method in the roaming process.

[0035] Figure 8 This is a timing diagram illustrating the ARP method in the roaming process. Detailed Implementation

[0036] This invention can have various modifications and embodiments, and specific embodiments are shown in the accompanying drawings and described in detail in the specification. However, this is not intended to limit the invention to the specific embodiments, but should be understood to include all modifications, equivalents, or alternatives contained within the spirit and technical scope of the invention.

[0037] The terms "first," "second," etc., can be used to describe various components, but components should not be limited by the terms. Terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the invention, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component. Terms and / or include combinations of multiple related descriptive terms or any one of multiple related descriptive terms.

[0038] In embodiments of the present invention, "at least one of A and B" can mean "at least one of A or B" or "at least one combination of one or more of A and B". Furthermore, in embodiments of the present invention, "one or more of A and B" can mean "one or more of A or B" or "one or more combinations of one or more of A and B".

[0039] When it is said that a component is "joined to" or "connected to" another component, it should be understood that one component is connected to the other component directly or through any other component in between. On the other hand, when it is said that a component is "directly connected to" or "directly joined to" another component, it should be understood that there are no other components between the components.

[0040] The terminology used in this invention is for describing particular embodiments only and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as “comprising” or “having” are intended to specify the presence of features, quantities, steps, operations, components, parts or combinations thereof described in the specification, but should be understood not to preclude the possibility of the presence or addition of one or more other features, quantities, steps, operations, components, parts or combinations thereof.

[0041] Unless otherwise defined, all terms used herein (including technical or scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in general dictionaries shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted as having an ideal or overly formal meaning unless expressly defined herein.

[0042] Preferred embodiments of the invention will be described in more detail below with reference to the accompanying drawings. In describing the invention, for ease of overall understanding, the same reference numerals are used for the same components in the drawings, and repeated descriptions of the same components are omitted.

[0043] The following describes a wireless communication system applying embodiments of the present invention. The wireless communication system applying embodiments of the present invention is not limited to the following description, and the embodiments of the present invention can be applied to various wireless communication systems. The wireless communication system may be referred to as a "wireless communication network".

[0044] In the implementation scheme, "configuration operation (e.g., transmission operation)" can mean signaling "configuration information for the operation (e.g., information elements, parameters)" and / or "information indicating the performance of the operation." "Configuration information element (e.g., parameter)" can mean signaling a corresponding information element. "Configuration resource (e.g., resource area)" can mean signaling configuration information for a resource. The frame names proposed in this invention can be summarized as First Frame, Second Frame, Third Frame, etc. The frame transmission time point can represent the transmission start time point or the transmission end time point, and the frame reception time point can represent the reception start time point or the reception end time point. The transmission time point can be interpreted as corresponding to the reception time point. A time point can be interpreted as time, and time can be interpreted as a time point.

[0045] Figure 1 A block diagram of a communication node in a wireless local area network system is shown.

[0046] refer to Figure 1 Communication node 100 can be an access point (AP), a station (STA), an AP multi-link device (MLD), or a non-AP MLD. STAs can be non-AP STAs. The operating channel width supported by the AP can be 20 MHz, 80 MHz, or 160 MHz, etc. The operating channel width supported by the STA can be 20 MHz or 80 MHz.

[0047] Communication node 100 may include at least one processor 110, memory 120, and at least one transmitting / receiving device 130 connected to a network and performing communication. Transmitting / receiving device 130 may also be referred to as a transceiver, radio frequency (RF) unit, or RF module. Additionally, communication node 100 may further include an input interface device 140, an output interface device 150, and a storage device 160. Components included in communication node 100 can be connected via bus 170 and perform communication between them.

[0048] However, each component included in communication node 100 may be connected not via common bus 170, but via a separate interface or separate bus around processor 110. For example, processor 110 may be connected via a dedicated interface to at least one of memory 120, transmitting / receiving device 130, input interface device 140, output interface device 150, and storage device 160.

[0049] Processor 110 can execute program instructions stored in at least one of memory 120 and storage device 160. Processor 110 can be a central processing unit (CPU), graphics processing unit (GPU), or dedicated processor that performs methods according to embodiments of the present invention. Memory 120 and storage device 160 can each be configured as at least one volatile storage medium and at least one non-volatile storage medium. For example, memory 120 can be configured as at least one read-only memory (ROM) and random access memory (RAM).

[0050] Figure 2 This is a conceptual diagram illustrating a first implementation of multiple links configured between MLDs.

[0051] refer to Figure 2 An MLD can have a medium access control (MAC) address. In an implementation, an MLD can be an AP MLD and / or a non-AP MLD. The MAC address of the MLD can be used in the multi-link establishment process between a non-AP MLD and an AP MLD. The MAC address of the AP MLD can be different from the MAC address of the non-AP MLD. APs associated with an AP MLD can have different MAC addresses, and STAs associated with a non-AP MLD can have different MAC addresses. APs within an AP MLD with different MAC addresses can be responsible for each link and act as independent APs.

[0052] A STA within a non-AP MLD with different MAC addresses can be responsible for each link and act as an independent STA. A non-AP MLD can be referred to as a STA MLD. An MLD can support simultaneous transmit and receive (STR) operations. For example, an MLD can perform a transmit operation on link 1 and a receive operation on link 2. An MLD that supports STR operations can be referred to as a STR MLD (e.g., a STR AP MLD or a STR non-AP MLD). In implementations, a link can be a channel or a frequency band. A device that does not support STR operations can be referred to as a non-STR (NSTR) AP MLD or an NSTR non-AP MLD (or an NSTR STA MLD).

[0053] MLDs can utilize discontinuous bandwidth extension schemes (e.g., 80 MHz + 80 MHz) to send and receive frames on multiple links. Multi-link operation can include multi-band transmission. An AP MLD can include multiple APs, and these APs can operate on different links. Each of the multiple APs can perform functions at the lower MAC layer. Each of the multiple APs can be referred to as a "communication node" or a "lower-level entity." A communication node (e.g., an AP) can be configured according to the upper layer (or...) Figure 1 The processor 110 shown is operated under the control of the processor. A non-AP MLD may include multiple STAs, and these STAs may operate on different links. Each of the multiple STAs may be referred to as a "communication node" or a "lower-level entity." A communication node (e.g., an STA) can operate according to the control of an upper layer (or...). Figure 1 The processor 110 shown is used for operation.

[0054] MLDs can perform communication across multiple frequency bands. For example, an MLD can perform communication using a 40 MHz bandwidth in the 2.4 GHz band, and a 160 MHz bandwidth in the 5 GHz band, depending on a channel extension scheme (e.g., a bandwidth extension scheme). An MLD can also perform communication using a 160 MHz bandwidth in the 5 GHz band and a 160 MHz bandwidth in the 6 GHz band. A single frequency band (e.g., a single channel) used by an MLD can be defined as a single link. Alternatively, multiple links can be configured within a single frequency band used by an MLD. For example, an MLD can configure one link in the 2.4 GHz band and two links in the 6 GHz band. The links can be referred to as Link 1, Link 2, and Link 3, respectively. Alternatively, the links can be referred to as Link 1, Link 2, and Link 3, respectively. Link numbers can be set by the AP, and an identifier (ID) can be assigned to each link.

[0055] A Multi-Link Ledger (MLD) (e.g., an AP MLD and / or a non-AP MLD) can configure multiple links by performing access and / or negotiation procedures for multi-link operation. For example, the number of links and / or the links to be used among multiple links can be configured. A non-AP MLD (e.g., a STA) can identify information about the frequency bands that can communicate with the AP MLD. In the multi-link operation negotiation procedure between the non-AP MLD and the AP MLD, the non-AP MLD can configure one or more links supported by the AP MLD for multi-link operation. A STA that does not support multi-link operation (e.g., a STA according to IEEE 802.11 a / b / g / n / ac / ax) can access one or more links supported by the AP MLD.

[0056] When the frequency band gaps between multiple links (e.g., the frequency band gap between link 1 and link 2 in the frequency domain) are sufficient, the MLD can perform STR operations. For example, the MLD can use link 1 to transmit a physical layer protocol data unit (PPDU) 1 and can use link 2 to receive a PPDU 2. On the other hand, when the frequency band gaps between multiple links are insufficient and the MLD performs STR operations, in-device coexistence (IDC) interference may occur, that is, interference between multiple links. Accordingly, when the frequency band gaps between multiple links are insufficient, the MLD may not be able to perform STR operations. The pair of links in the above interference relationship can be a non-simultaneous transmit and receive (NSTR) restricted link pair. Here, the MLD can be an NSTR AP MLD or an NSTR non-AP MLD.

[0057] For example, multiple links, including Link 1, Link 2, and Link 3, can be set up between the AP MLD and the non-AP MLD 1. When the band gap between Link 1 and Link 3 is sufficient, the AP MLD can perform STR operations using Link 1 and Link 3. In other words, the AP MLD can use Link 1 to send frames and use Link 3 to receive frames. When the band gap between Link 1 and Link 2 is insufficient, the AP MLD may not be able to perform STR operations using Link 1 and Link 2. When the band gap between Link 2 and Link 3 is insufficient, the AP MLD may not be able to perform STR operations using Link 2 and Link 3.

[0058] On the other hand, in a wireless LAN system, a negotiation process for multi-link operation can be performed during the access process between a STA and an AP. A device supporting multiple links (e.g., an AP or a STA) can be called a multi-link device (MLD). An AP supporting multiple links can be called an AP MLD, and a STA supporting multiple links can be called a non-AP MLD or a STA MLD. An AP MLD can have a physical address (e.g., a MAC address) for each link. An AP MLD can be implemented as if each AP were independently responsible for each link. Multiple APs can be managed within a single AP MLD. Accordingly, cooperation can occur between multiple APs belonging to the same AP MLD. A STA MLD can also have a physical address (e.g., a MAC address) for each link. A STA MLD can be implemented as if each STA were independently responsible for each link. Multiple STAs can be managed within a single STA MLD. Accordingly, cooperation can occur between multiple STAs belonging to the same STA MLD.

[0059] For example, AP 1 of the AP MLD and STA 1 of the STA MLD can each be responsible for a first link and perform communication using the first link. AP 2 of the AP MLD and STA 2 of the STA MLD can each be responsible for a second link and perform communication using the second link. STA 2 can receive state change information for the first link on the second link. The STA MLD can collect information received from each link (e.g., state change information) and control the operations performed by STA 1 based on the collected information.

[0060] Next, methods for transmitting and receiving data in a wireless local area network system will be described. When a method (e.g., signal transmission or reception) performed in a first communication node is described, the corresponding second communication node can also perform a method (e.g., signal reception or transmission) corresponding to the method performed in the first communication node. In other words, when the operation of a STA is described, the corresponding AP can perform an operation corresponding to the operation of the STA. On the other hand, when the operation of an AP is described, the corresponding STA can perform an operation corresponding to the operation of the AP.

[0061] In this invention, the operation of a STA can be interpreted as the operation of a STA MLD, the operation of a STA MLD can be interpreted as the operation of a STA, the operation of an AP can be interpreted as the operation of an AP MLD, and the operation of an AP MLD can be interpreted as the operation of an AP. The STA in a STA MLD can represent the STA associated with the STA MLD, and the AP in an AP MLD can represent the AP associated with the AP MLD. When a STA MLD includes a first STA operating on a first link and a second STA operating on a second link, the operation of a STA on the first link can be interpreted as the operation of the first STA, and the operation of a STA MLD on the second link can be interpreted as the operation of the second STA. When an AP MLD includes a first AP operating on a first link and a second AP operating on a second link, the operation of an AP MLD on the first link can be interpreted as the operation of the first AP, and the operation of an AP MLD on the second link can be interpreted as the operation of the second AP.

[0062] The embodiments of the present invention can be applied not only to multiple links but also to a single link. In other words, an embodiment described as applicable to multiple links can be applied to a single link in the same and / or similar manner. An embodiment described as applicable to a single link can be applied to multiple links in the same and / or similar manner. In this invention, a communication method will be described in the case of a single STA MLD connected to multiple AP MLDs. The embodiments of the present invention can be applied to the case of a STA connected to multiple APs.

[0063] Figure 3 This is a timing diagram illustrating the parameter exchange method in the roaming process.

[0064] refer to Figure 3AP 1, AP 2, and / or STA 1 can operate in a wireless LAN. AP 1 can represent AP MLD1, and the operation of AP 1 can be interpreted as the operation of AP MLD1. AP 1 can be referred to as the first AP. AP 2 can represent AP MLD 2, and the operation of AP 2 can be interpreted as the operation of AP MLD 2. AP 2 can be referred to as the second AP. STA 1 can represent STA MLD 1, and the operation of STA 1 can be interpreted as the operation of STA MLD 1. STA 1 can be associated with AP 1 (e.g., access AP 1) and perform communication when associated with AP 1. STA 1 can perform a roaming procedure to communicate with AP 2. According to the roaming procedure, the AP associated with STA 1 can change from AP 1 to AP 2. In other words, according to the roaming procedure, the communication target of STA 1 can change from AP 1 to AP 2. AP 1 can represent the current AP or the serving AP. AP 2 can represent the target AP.

[0065] STA 1 can determine whether to execute a roaming procedure based on the strength (e.g., quality) of the received signal. For example, when the received signal strength of AP 1 (or the received signal strength of AP 1 plus offset (or margin)) is lower than the received signal strength of AP 2, STA 1 can determine to execute a roaming procedure from AP 1 to AP 2. The roaming procedure can be initiated by STA 1 sending a link addition request (or roaming request) for AP 2 (e.g., the target AP) to AP 1 (e.g., the serving AP). During the roaming procedure, STA 1 can execute an association procedure with AP 2 and then initiate communication with AP 2 after the association procedure is completed. Alternatively, during the roaming procedure, STA 1 can initiate communication with AP 2 without executing an association procedure with AP 2.

[0066] STA 1 can send a probe request frame to discover AP 2 (e.g., the target AP) and receive a probe response frame in response to the probe request frame. Alternatively, STA 1 can discover AP 2 (e.g., the target AP) by receiving a beacon frame from AP 2. Yet another method, AP 1 (e.g., the serving AP) can send a management frame (e.g., a beacon frame) that includes a neighbor report (e.g., a reduced neighbor report, RNR). The neighbor report can include information about AP 2 (e.g., a neighboring AP, the target AP). The information about AP 2 can include at least one of the following: AP 2's MAC address, AP 2's operating frequency, AP 2's capability information, AP 2's IP address, or an indicator indicating whether IP address reallocation (or reassignment) (e.g., reset or reconfiguration) is required. The indicator indicating whether IP address reallocation (e.g., reset or reconfiguration) is required can be called an "IP reallocation indicator" or an "IP reset indicator." In this invention, reallocation and reset can be used to have the same meaning.

[0067] An IP redistribution indicator can be an indicator that suggests whether an IP address should be redistributed (e.g., reset) to STA 1 when STA 1 connects to AP 2 during roaming. For example, when the IP redistribution indicator indicates IP address redistribution, STA 1 may perform the IP address redistribution (e.g., reset) operation upon connecting to AP 2. When the IP redistribution indicator does not indicate IP address redistribution, STA 1 may not perform the IP address redistribution (e.g., reset) operation upon connecting to AP 2. In other words, IP address redistribution may not be necessary.

[0068] When STA 1 determines that it needs to perform a roaming procedure, STA 1 may send a roaming request frame to AP 1. The roaming request frame may include at least one of the following: the expected time for performing the roaming procedure (e.g., the time during which STA 1 can communicate with AP 2); the target AP that STA 1 intends to connect to (e.g., AP 2); a list of target APs that STA 1 intends to connect to (e.g., a list of target APs including AP 2); STA 1's IP address; STA 1's subnet information; STA 1's MAC address; STA 1's association identifier (AID); or STA 1's capability information. The roaming request frame may request the execution of a roaming procedure from the serving AP (e.g., AP 1) to the target AP (e.g., AP 2). A subnet may refer to a distributed system (DS).

[0069] AP 1 can receive roaming request frames from STA 1 and execute procedures for exchanging roaming information with AP 2 based on the information included in the roaming request frames. AP 1 can identify the target AP (e.g., AP 2) based on the information included in the roaming request frames. During the roaming information exchange procedure, AP 1 and AP 2 can exchange the information included in the roaming request frames sent by STA 1. In addition to the information included in the roaming request frames sent by STA 1, information known to AP 1 about STA 1 (e.g., STA 1's IP address, STA 1's subnet information, IP reallocation indicator, STA 1's received signal strength, STA 1's MAC address, and / or STA 1's capability information) can be transmitted to AP 2. Furthermore, during the roaming information exchange procedure, AP 1 and AP 2 can exchange information included in the roaming response frames sent by AP 1 to STA 1. During the roaming information exchange procedure, AP 2 can obtain roaming information from AP 1. AP 2 can accept or reject roaming procedures based on roaming information. In other words, AP 2 can send information to AP 1 instructing it to accept or reject roaming procedures. Roaming information can be transmitted directly between AP 1 and AP 2 via a wired network (e.g., an Ethernet network). Alternatively, roaming information can be transmitted via specific network endpoints (e.g., the management entities of AP 1 and AP 2). As another method, the process for exchanging roaming information can be performed via the wireless network between AP 1 and AP 2 (e.g., wireless LAN frame exchange).

[0070] After the process for exchanging roaming information is completed, AP 1 may send a roaming response frame to STA 1. The roaming response frame may include information indicating whether AP 2 accepts the roaming procedure (e.g., roaming acceptance or roaming rejection), information about the time when STA 1 performed the roaming procedure (e.g., roaming execution time), AP 2's capability information, AP 2's IP address, AP 2's subnet information, AP 2's MAC address, AP 2's operating frequency (e.g., operating channel), an IP reallocation indicator, or at least one of the following: a neighbor cell report (e.g., RNR) containing information about AP 2. The IP reallocation indicator may be included in the neighbor cell report containing information about AP 2. The neighbor cell report may be replaced by a multilink element. When the neighbor cell report is replaced by a multilink element, the IP reallocation indicator may be included in the multilink element. Alternatively, both the multilink element and the neighbor cell report may be included in the roaming response frame.

[0071] As an alternative, AP 1 can execute the procedure for exchanging roaming information with AP 2 without receiving a roaming request frame from STA 1. After the procedure for exchanging roaming information is completed, AP 1 can send a roaming response frame to STA 1. Alternatively, AP 1 can send an unrequested roaming response frame to STA 1. The unrequested roaming response frame can be configured in the same or similar manner as a requested roaming response frame caused by a request from STA 1 (e.g., a roaming request frame). The unrequested roaming response frame may include information indicating whether AP 2 accepts the roaming procedure (e.g., roaming acceptance or roaming rejection), information about the time when STA 1 executes the roaming procedure (e.g., roaming execution time), AP 2's capability information, AP 2's IP address, AP 2's subnet information, AP 2's MAC address, AP 2's operating frequency (e.g., operating channel), an IP reallocation indicator, or at least one of the following: a neighbor cell report (e.g., an RNR) containing information about AP 2. The IP reallocation indicator may be included in the neighbor cell report containing information about AP 2. Neighbor cell reports can be replaced by multilink elements. When neighbor cell reports are replaced by multilink elements, IP reallocation indicators can be included in the multilink elements. Alternatively, both multilink elements and neighbor cell reports can be included in the roaming response frame.

[0072] AP 1 can periodically send unsolicited roaming response frames to STA 1. These unsolicited roaming response frames can be periodically sent management frames. Alternatively, AP 1 can send an unsolicited roaming response frame to STA 1 when it is determined that STA 1 should initiate a roaming procedure.

[0073] STA 1 can receive roaming response frames (e.g., requested or unrequested roaming response frames) from AP 1. STA 1 can perform roaming procedures based on the information included in the roaming response frame. In other words, STA 1 can perform association procedures (e.g., access procedures) with a target AP (e.g., AP 2) based on the information included in the roaming response frame. When the information included in the roaming response frame indicates a rejection of the roaming procedure (e.g., when AP 2 does not accept the roaming procedure), STA 1 can continue communicating with AP 1 or search for another target AP. When the information included in the roaming response frame indicates acceptance of the roaming procedure (e.g., when AP 2 accepts the roaming procedure), STA 1 can perform roaming procedures (e.g., association procedures) with AP 2. STA 1 can perform roaming procedures (e.g., association procedures) based on the roaming execution time indicated by AP 1. Depending on the situation of STA 1, the actual roaming execution time of STA 1 may differ from the roaming execution time indicated by AP 1. After the roaming execution time, STA 1 may not communicate with AP 1, but instead communicate with AP 2. In other words, after the roaming execution time, STA 1 may be in a state where it cannot communicate with AP 1, and STA 1 may be in a state where it can communicate with AP 2.

[0074] During roaming, STA 1 can send an establishment request frame to AP 2. When STA 1 is in a state where it can communicate with AP 2, it can send an establishment request frame to AP 2. The establishment request frame can be a frame in which STA 1 requests AP 2 to establish communication. The establishment request frame can be a management frame. For example, it can be an association request frame. The establishment request frame can be an action frame, which is a type of management frame. Alternatively, the establishment request frame may not be a management frame, but can be a data frame (e.g., a quality of service (QoS) data frame, a QoS empty frame), a control frame, or an action frame. The establishment request frame may include STA 1's IP address and / or subnet information.

[0075] AP 2 can receive setup request frames from STA 1. AP 2 can determine whether a new IP address needs to be assigned to STA 1 based on information included in STA 1's setup request frame (e.g., IP address and / or subnet information). The IP address included in the setup request frame may be the IP address used in communication with AP 1 (to which STA 1 was previously connected). The subnet information included in the setup request frame may indicate the subnet belonging to AP 1 (to which STA 1 was previously connected). AP 2 can determine on its own whether a new IP address needs to be assigned to STA 1. Alternatively, whether a new IP address needs to be assigned to STA 1 may be determined by another entity connected to AP 2 (e.g., a router, a Dynamic Host Configuration Protocol (DHCP) server). A new IP address needs to be assigned to STA 1 when the subnet (e.g., DS) to which AP 1 (to which STA 1 was previously connected) belongs is different from the subnet to which AP 2 belongs. When the subnet (e.g., DS) to which AP 1, previously connected to STA 1, belongs is the same as the subnet to which AP 2 belongs, it can be determined that no IP address needs to be reassigned to STA 1. The process for reassigning IP addresses (e.g., DHCP establishment process) can be interpreted as a DS mapping process.

[0076] AP 2 can send an establishment response frame to STA 1. The establishment response frame can be a management frame. For example, it can be an association response frame. Alternatively, the establishment response frame may not be a management frame, but can be a data frame (e.g., a QoS data frame, a QoS empty frame), a control frame, or an action frame. The establishment response frame may include AP 2's IP address and / or subnet information. The establishment response frame may further include an IP reallocation indicator for STA 1.

[0077] STA 1 can receive a setup response frame from AP 2. When the IP reallocation indicator included in the setup response frame indicates IP address reallocation, STA 1 and / or AP 2 can execute a procedure for IP address reallocation (e.g., a DHCP setup procedure). After the IP address reallocation procedure is completed, STA 1 and / or AP 2 can perform data communication. Alternatively, STA 1 can determine for itself whether IP address reallocation is needed. Since the roaming response frame (or setup response frame) received by STA 1 includes AP 2's IP address and / or subnet information, STA 1 can compare each of its IP address and / or subnet information with AP 2's IP address and / or subnet information. For example, if the subnet (e.g., DS) to which AP 1, previously connected to STA 1, belongs is different from the subnet to which AP 2 belongs, it can be determined that an IP address reallocation is needed for STA 1. When the subnet (e.g., DS) to which AP1, previously connected to STA1, belongs is the same as the subnet to which AP2 belongs, it can be determined that no IP address reassignment is required for STA1. If it is determined that IP address reassignment is required, STA1 and / or AP2 can execute the procedure for reassigning IP addresses (e.g., a DHCP establishment procedure) even if STA1 has not yet received an establishment response frame or if the establishment response frame does not include an IP reassignment indicator. The procedure for reassigning IP addresses (e.g., a DHCP establishment procedure) can be interpreted as a DS mapping procedure.

[0078] As another method, STA 1 can receive management frames from AP 1 that include a neighbor cell report (which includes an IP reassignment indicator). Alternatively, STA 1 can receive roaming response frames from AP 1 that include an IP reassignment indicator. In the above cases, when the IP reassignment indicator indicates that an IP address reassignment is required, STA 1 and / or AP 2 can execute procedures for reassigning IP addresses (e.g., a DHCP establishment procedure).

[0079] Figure 4 This is a timing diagram illustrating the parameter exchange method in the roaming process.

[0080] refer to Figure 4AP 1, AP 2, and / or STA 1 can operate in a wireless LAN. AP 1 can represent AP MLD1, and the operation of AP 1 can be interpreted as the operation of AP MLD1. AP 1 can be referred to as the first AP. AP 2 can represent AP MLD 2, and the operation of AP 2 can be interpreted as the operation of AP MLD 2. AP 2 can be referred to as the second AP. STA 1 can represent STA MLD 1, and the operation of STA 1 can be interpreted as the operation of STA MLD 1. STA 1 can be associated with AP 1 (e.g., access AP 1) and perform communication when associated with AP 1. STA 1 can perform a roaming procedure to communicate with AP 2. According to the roaming procedure, the AP associated with STA 1 can change from AP 1 to AP 2. In other words, according to the roaming procedure, the communication target of STA 1 can change from AP 1 to AP 2. AP 1 can represent the current AP or the serving AP. AP 2 can represent the target AP.

[0081] STA 1 can determine whether to execute a roaming procedure based on the strength (e.g., quality) of the received signal. For example, when the received signal strength of AP 1 (or the received signal strength of AP 1 plus offset (or margin)) is lower than the received signal strength of AP 2, STA 1 can determine to execute a roaming procedure from AP 1 to AP 2. The roaming procedure can be initiated by STA 1 sending a link addition request (or roaming request) for AP 2 (e.g., the target AP) to AP 1 (e.g., the serving AP). During the roaming procedure, STA 1 can execute an association procedure with AP 2 and then initiate communication with AP 2 after the association procedure is completed. Alternatively, during the roaming procedure, STA 1 can initiate communication with AP 2 without executing an association procedure with AP 2.

[0082] STA 1 can send probe request frames to discover AP 2 (e.g., the target AP) and receive probe response frames in response to the probe request frames. Alternatively, STA 1 can discover AP 2 (e.g., the target AP) by receiving beacon frames from AP 2. Yet another method, AP 1 (e.g., the serving AP) can send management frames (e.g., beacon frames) that include neighbor cell reports (e.g., RNRs). The neighbor cell report may include information about AP 2 (e.g., neighboring APs, the target AP). The information about AP 2 may include at least one of the following: AP 2's MAC address, AP 2's operating frequency, AP 2's capability information, AP 2's IP address, or an IP reassignment indicator.

[0083] An IP redistribution indicator can be an indicator that suggests whether an IP address should be redistributed (e.g., reset) to STA 1 when STA 1 connects to AP 2 during roaming. For example, when the IP redistribution indicator indicates IP address redistribution, STA 1 may perform the IP address redistribution (e.g., reset) operation upon connecting to AP 2. When the IP redistribution indicator does not indicate IP address redistribution, STA 1 may not perform the IP address redistribution (e.g., reset) operation upon connecting to AP 2. In other words, IP address redistribution may not be necessary.

[0084] When STA 1 determines to initiate a roaming procedure, STA 1 may send a roaming request frame to AP 1. The roaming request frame may include the expected time for initiating the roaming procedure (e.g., the time during which STA 1 can communicate with AP 2), the target AP that STA 1 intends to connect to (e.g., AP 2), a list of target APs that STA 1 intends to connect to (e.g., a list of target APs including AP 2), STA 1's IP address, STA 1's subnet information, STA 1's MAC address, STA 1's AID, or at least STA 1's capability information. The roaming request frame may request the execution of a roaming procedure from the serving AP (e.g., AP 1) to the target AP (e.g., AP 2). The subnet may refer to a DS.

[0085] AP 1 can receive roaming request frames from STA 1 and execute procedures for exchanging roaming information with AP 2 based on the information included in the roaming request frames. AP 1 can identify the target AP (e.g., AP 2) based on the information included in the roaming request frames. During the roaming information exchange procedure, AP 1 and AP 2 can exchange the information included in the roaming request frames sent by STA 1. In addition to the information included in the roaming request frames sent by STA 1, information known to AP 1 about STA 1 (e.g., STA 1's IP address, STA 1's subnet information, IP reallocation indicator, STA 1's received signal strength, STA 1's MAC address, and / or STA 1's capability information) can be transmitted to AP 2. Furthermore, during the roaming information exchange procedure, AP 1 and AP 2 can exchange information included in the roaming response frames sent by AP 1 to STA 1. During the roaming information exchange procedure, AP 2 can obtain roaming information from AP 1. AP 2 can accept or reject roaming procedures based on roaming information. In other words, AP 2 can send information to AP 1 instructing it to accept or reject roaming procedures. Roaming information can be transmitted directly between AP 1 and AP 2 via a wired network (e.g., an Ethernet network). Alternatively, roaming information can be transmitted via specific network endpoints (e.g., the management entities of AP 1 and AP 2). As another method, the process for exchanging roaming information can be performed via the wireless network between AP 1 and AP 2 (e.g., wireless LAN frame exchange).

[0086] After the process for exchanging roaming information is completed, AP 1 may send a roaming response frame to STA 1. The roaming response frame may include information indicating whether AP 2 accepts the roaming procedure (e.g., roaming acceptance or roaming rejection), information about the time when STA 1 performed the roaming procedure (e.g., roaming execution time), AP 2's capability information, AP 2's IP address, AP 2's subnet information, AP 2's MAC address, AP 2's operating frequency (e.g., operating channel), an IP reallocation indicator, or at least one of the following: a neighbor cell report (e.g., RNR) containing information about AP 2. The IP reallocation indicator may be included in the neighbor cell report containing information about AP 2. The neighbor cell report may be replaced by a multilink element. When the neighbor cell report is replaced by a multilink element, the IP reallocation indicator may be included in the multilink element. Alternatively, both the multilink element and the neighbor cell report may be included in the roaming response frame.

[0087] As an alternative approach, AP 1 can execute the procedure for exchanging roaming information with AP 2 without receiving a roaming request frame from STA 1. After the procedure for exchanging roaming information is completed, AP 1 can send a roaming response frame to STA 1. In other words, AP 1 can send an unrequested roaming response frame to STA 1. The unrequested roaming response frame can be configured in the same or similar manner as a requested roaming response frame caused by a request from STA 1 (e.g., a roaming request frame). The unrequested roaming response frame may include information indicating whether AP 2 accepts the roaming procedure (e.g., roaming acceptance or roaming rejection), information about the time when STA 1 executes the roaming procedure (e.g., roaming execution time), AP 2's capability information, AP 2's IP address, AP 2's subnet information, AP 2's MAC address, AP 2's operating frequency (e.g., operating channel), an IP reallocation indicator, or at least one of the following: a neighbor cell report (e.g., an RNR) containing information about AP 2. The IP reallocation indicator may be included in the neighbor cell report containing information about AP 2. Neighbor cell reports can be replaced by multilink elements. When neighbor cell reports are replaced by multilink elements, IP reallocation indicators can be included in the multilink elements. Alternatively, both multilink elements and neighbor cell reports can be included in the roaming response frame.

[0088] AP 1 can periodically send unsolicited roaming response frames to STA 1. These unsolicited roaming response frames can be periodically sent management frames. Alternatively, AP 1 can send an unsolicited roaming response frame to STA 1 when it is determined that STA 1 should initiate a roaming procedure.

[0089] STA 1 can receive roaming response frames (e.g., requested or unrequested roaming response frames) from AP 1. STA 1 can perform roaming procedures based on the information included in the roaming response frame. In other words, STA 1 can perform association procedures (e.g., access procedures) with a target AP (e.g., AP 2) based on the information included in the roaming response frame. When the information included in the roaming response frame indicates a rejection of the roaming procedure (e.g., when AP 2 does not accept the roaming procedure), STA 1 can continue communicating with AP 1 or search for another target AP. When the information included in the roaming response frame indicates acceptance of the roaming procedure (e.g., when AP 2 accepts the roaming procedure), STA 1 can perform roaming procedures (e.g., association procedures) with AP 2. STA 1 can perform roaming procedures (e.g., association procedures) based on the roaming execution time indicated by AP 1. Depending on the situation of STA 1, the actual roaming execution time of STA 1 may differ from the roaming execution time indicated by AP 1. After the roaming execution time, STA 1 may not communicate with AP 1, but instead communicate with AP 2. In other words, after the roaming execution time, STA 1 may be in a state where it cannot communicate with AP 1, and STA 1 may be in a state where it can communicate with AP 2.

[0090] AP 2 can determine the expected roaming execution time of STA 1 by executing a procedure for exchanging roaming information with AP 1. AP 2 can execute a channel access procedure (e.g., an enhanced distributed channel access (EDCA) backoff procedure) for transmitting a fast establishment frame. The fast establishment frame can be a trigger frame that triggers the transmission of an establishment request frame. AP 2's channel access procedure can be executed before the expected roaming execution time (e.g., at the point in time when the procedure for exchanging roaming information with AP 1 is completed, or at some point before the expected roaming execution time). Alternatively, AP 2's channel access procedure can be executed after the expected roaming execution time.

[0091] When AP 2 executes its channel access procedure before the expected roaming execution time, the channel access procedure can be completed before the expected roaming execution time. Completion of the channel access procedure can indicate success. In other words, completion of the channel access procedure can indicate that the EDCA backoff counter reaches 0. When AP 2's channel access procedure completes before the expected roaming execution time, AP 2 can keep the backoff counter (e.g., the EDCA backoff counter) at 0 until the expected roaming execution time. In other words, even when the channel access procedure is complete, AP 2 can wait without sending a fast establishment frame. Alternatively, AP 2 can choose a new backoff counter and execute the channel access procedure based on the chosen new backoff counter until after the expected roaming execution time. "When the backoff counter remains at 0 until (or after) the expected roaming execution time" or "when the channel access procedure completes after the expected roaming execution time," AP 2 can send a fast establishment frame (e.g., a trigger frame) to STA 1.

[0092] When the fast establishment frame is a trigger frame, the user information in the user information field of the trigger frame can indicate the AID of STA 1. When AP 2 does not know the AID of STA 1 or when the AID of STA 1 changes due to roaming procedures, AP 2 can send a trigger frame (e.g., a fast establishment frame) including allocation information for a random access resource unit (RA-RU) to perform uplink OFDMA random access (UORA) operation. When the association process between STA 1 and AP 2 is not completed, the RA-RU allocation information can indicate the AID, which indicates the UORA of the unassociated STA. When the association process between STA 1 and AP 2 is completed, the RA-RU allocation information can indicate the AID, which indicates the UORA of the associated STA. STA 1 can receive a fast establishment frame from AP 2. STA 1 can determine that the transmission of an establishment request frame was triggered by the fast establishment frame. STA 1 can send an establishment request frame to AP 2 in response to the fast establishment frame. Depending on the situation of STA 1, STA 1 may be unable to execute the roaming procedure at the expected roaming execution time. In this case, communication between STA 1 and AP 2 may be impossible. AP 2 may repeatedly send fast establishment frames until STA 1 is able to receive fast establishment frames.

[0093] A setup request frame can be a frame in which STA 1 requests AP 2 to establish communication. A setup request frame can be a management frame. For example, a setup request frame can be an association request frame. A setup request frame can be an action frame, which is a type of management frame. Alternatively, a setup request frame can not be a management frame, but can be a data frame (e.g., a QoS data frame, a QoS empty frame), a control frame, or an action frame. A setup request frame can include STA 1's IP address and / or subnet information.

[0094] AP 2 can receive setup request frames from STA 1. AP 2 can determine whether an IP address needs to be reassigned to STA 1 based on information included in STA 1's setup request frame (e.g., IP address and / or subnet information). AP 2 can determine whether an IP address needs to be reassigned to STA 1 on its own. Alternatively, whether an IP address needs to be reassigned to STA 1 can be determined by another entity connected to AP 2 (e.g., a router, a DHCP server). When the subnet (e.g., DS) to which AP 1 previously connected to STA 1 belongs is different from the subnet to which AP 2 belongs, it can be determined that an IP address needs to be reassigned to STA 1. When the subnet (e.g., DS) to which AP 1 previously connected to STA 1 belongs is the same as the subnet to which AP 2 belongs, it can be determined that an IP address does not need to be reassigned to STA 1. The process for reassigning an IP address (e.g., a DHCP setup process) can be interpreted as a DS mapping process. AP 2 can send setup response frames to STA 1. Setup response frames can be management frames. For example, setup response frames can be association response frames. Alternatively, the establishment response frame may not be a management frame, but may be a data frame (e.g., a QoS data frame, a QoS empty frame), a control frame, or an action frame. The establishment response frame may include the IP address and / or subnet information of AP 2. The establishment response frame may further include an IP reallocation indicator for STA 1.

[0095] STA 1 can receive a setup response frame from AP 2. When the IP reallocation indicator included in the setup response frame indicates IP address reallocation, STA 1 and / or AP 2 can execute a procedure for IP address reallocation (e.g., a DHCP setup procedure). After the IP address reallocation procedure is completed, STA 1 and / or AP 2 can perform data communication. Alternatively, STA 1 can determine for itself whether IP address reallocation is needed. Since the roaming response frame (or setup response frame) received by STA 1 includes AP 2's IP address and / or subnet information, STA 1 can compare each of its IP address and / or subnet information with AP 2's IP address and / or subnet information. For example, if the subnet (e.g., DS) to which AP 1, previously connected to STA 1, belongs is different from the subnet to which AP 2 belongs, it can be determined that an IP address reallocation is needed for STA 1. When the subnet (e.g., DS) to which AP1, previously connected to STA1, belongs is the same as the subnet to which AP2 belongs, it can be determined that no IP address reassignment is required for STA1. If it is determined that IP address reassignment is required, STA1 and / or AP2 can execute the procedure for reassigning IP addresses (e.g., a DHCP establishment procedure) even if STA1 has not yet received an establishment response frame or if the establishment response frame does not include an IP reassignment indicator. The procedure for reassigning IP addresses (e.g., a DHCP establishment procedure) can be interpreted as a DS mapping procedure.

[0096] As another approach, STA 1 can receive management frames from AP 1 that include a neighbor cell report (which includes an IP reassignment indicator). Alternatively, STA 1 can receive roaming response frames from AP 1 that include an IP reassignment indicator. In the above scenarios, when the IP reassignment indicator indicates that an IP address reassignment is required, STA 1 and / or AP 2 can execute procedures for reassigning IP addresses (e.g., a DHCP establishment procedure).

[0097] Figure 5 This is a timing diagram illustrating the ARP method in the roaming process.

[0098] refer to Figure 5AP 1, AP 2, and / or STA 1 can operate in a wireless LAN. AP 1 can represent AP MLD1, and the operation of AP 1 can be interpreted as the operation of AP MLD1. AP 1 can be referred to as the first AP. AP 2 can represent AP MLD 2, and the operation of AP 2 can be interpreted as the operation of AP MLD 2. AP 2 can be referred to as the second AP. STA 1 can represent STA MLD 1, and the operation of STA 1 can be interpreted as the operation of STA MLD 1. STA 1 can be associated with AP 1 (e.g., access AP 1) and perform communication when associated with AP 1. STA 1 can perform a roaming procedure to communicate with AP 2. According to the roaming procedure, the AP associated with STA 1 can change from AP 1 to AP 2. In other words, according to the roaming procedure, the communication target of STA 1 can change from AP 1 to AP 2. AP 1 can represent the current AP or the serving AP. AP 2 can represent the target AP.

[0099] STA 1 can determine whether to execute a roaming procedure based on the strength (e.g., quality) of the received signal. For example, when the received signal strength of AP 1 (or the received signal strength of AP 1 plus offset (or margin)) is lower than the received signal strength of AP 2, STA 1 can determine to execute a roaming procedure from AP 1 to AP 2. The roaming procedure can be initiated by STA 1 sending a link addition request (or roaming request) for AP 2 (e.g., the target AP) to AP 1 (e.g., the serving AP). During the roaming procedure, STA 1 can execute an association procedure with AP 2 and then initiate communication with AP 2 after the association procedure is completed. Alternatively, during the roaming procedure, STA 1 can initiate communication with AP 2 without executing an association procedure with AP 2.

[0100] When STA 1 determines to initiate a roaming procedure, STA 1 may send a roaming request frame to AP 1. The roaming request frame may include the expected time for initiating the roaming procedure (e.g., the time during which STA 1 can communicate with AP 2), the target AP that STA 1 intends to connect to (e.g., AP 2), a list of target APs that STA 1 intends to connect to (e.g., a list of target APs including AP 2), STA 1's IP address, STA 1's subnet information, STA 1's MAC address, STA 1's AID, or at least STA 1's capability information. The roaming request frame may request the execution of a roaming procedure from the serving AP (e.g., AP 1) to the target AP (e.g., AP 2). The subnet may refer to a DS.

[0101] AP 1 can receive roaming request frames from STA 1 and execute procedures for exchanging roaming information with AP 2 based on the information included in the roaming request frames. AP 1 can identify the target AP (e.g., AP 2) based on the information included in the roaming request frames. During the roaming information exchange procedure, AP 1 and AP 2 can exchange the information included in the roaming request frames sent by STA 1. In addition to the information included in the roaming request frames sent by STA 1, information known to AP 1 about STA 1 (e.g., STA 1's IP address, STA 1's subnet information, IP reallocation indicator, STA 1's received signal strength, STA 1's MAC address, and / or STA 1's capability information) can be transmitted to AP 2. Furthermore, during the roaming information exchange procedure, AP 1 and AP 2 can exchange information included in the roaming response frames sent by AP 1 to STA 1. During the roaming information exchange procedure, AP 2 can obtain roaming information from AP 1. AP 2 can accept or reject roaming procedures based on roaming information. In other words, AP 2 can send information to AP 1 instructing it to accept or reject roaming procedures. Roaming information can be transmitted directly between AP 1 and AP 2 via a wired network (e.g., an Ethernet network). Alternatively, roaming information can be transmitted via specific network endpoints (e.g., the management entities of AP 1 and AP 2). As another method, the process for exchanging roaming information can be performed via the wireless network between AP 1 and AP 2 (e.g., wireless LAN frame exchange).

[0102] After the process for exchanging roaming information is completed, AP 1 may send a roaming response frame to STA 1. The roaming response frame may include information indicating whether AP 2 accepts the roaming procedure (e.g., roaming acceptance or roaming rejection), information about the time when STA 1 performed the roaming procedure (e.g., roaming execution time), AP 2's capability information, AP 2's IP address, AP 2's subnet information, AP 2's MAC address, AP 2's operating frequency (e.g., operating channel), an IP reallocation indicator, or at least one of the following: a neighbor cell report (e.g., RNR) containing information about AP 2. The IP reallocation indicator may be included in the neighbor cell report containing information about AP 2. The neighbor cell report may be replaced by a multilink element. When the neighbor cell report is replaced by a multilink element, the IP reallocation indicator may be included in the multilink element. Alternatively, both the multilink element and the neighbor cell report may be included in the roaming response frame.

[0103] Alternatively, AP 1 can execute the procedure for exchanging roaming information with AP 2 without receiving a roaming request frame from STA 1. After the procedure for exchanging roaming information is completed, AP 1 can send a roaming response frame to STA 1. In other words, AP 1 can send an unsolicited roaming response frame to STA 1. The unsolicited roaming response frame can be configured in the same or similar manner as a requested roaming response frame caused by a request from STA 1 (e.g., a roaming request frame).

[0104] After the process of exchanging roaming information between AP 1 and AP 2 is completed, AP 2 can know the IP address and / or MAC address of STA 1. Accordingly, AP 2 can send ARP packets (e.g., ARP request packets, ARP frames, or ARP request frames) to the network to receive packets (e.g., data frames) to be transmitted to STA 1 from the network (e.g., a wired Ethernet network, DS). The ARP frame may include the IP address of STA 1. After AP 2 sends the ARP packet to the network, AP 2 can receive packets from the network with the destination address set to STA 1. AP 2 can store packets for transmission. ARP can be a protocol used to query and / or respond to relationships between Layer 2 and Layer 3 addresses (e.g., the relationship between MAC addresses and IP addresses). The ARP packet may be an Ethernet frame. Communication between each AP (e.g., AP 1 and AP 2) and the network can be performed via wireless or wired media. The ARP packet sent to the network may include the destination MAC address, the source MAC address, and the body (e.g., the body of an Ethernet frame). The body of an Ethernet frame can have the structure shown in Table 1 below. The structure of an ARP packet can vary depending on the hierarchical structure of the network used.

[0105] [Table 1] refer to Figure 5As per Table 1, the hardware type and protocol type can vary depending on the hardware type and communication protocol type of AP 2. For example, the hardware type can be Ethernet, and the protocol type can be Internet Protocol version 4 (IPv4) or IPv6. The hardware length (e.g., the hardware length field) can indicate the length of the hardware address (e.g., MAC address) of the hardware indicated by the hardware type. The hardware length can be indicated in bytes. When the hardware address is a MAC address, the MAC address is 48 bits long, so the hardware length (e.g., the hardware length field) can indicate 6. The protocol length (e.g., the protocol length field) can indicate the length of the protocol address (e.g., IP address) of the communication protocol indicated by the protocol type. The protocol length can be indicated in bytes. When the protocol address is an IPv4 address, the IPv4 address is 32 bits long, so the protocol length (e.g., the protocol length field) can indicate 4.

[0106] The action code indicates what action an ARP packet should take. In an ARP packet sent by AP 2, the action code can be set to 2. An action code of 2 indicates an ARP response. The sender hardware address can indicate the MAC address of STA 1. The sender protocol address can indicate the IP address of STA 1. The destination hardware address can be set to FF:FF:FF:FF:FF:FF, which is the broadcast MAC address. The destination protocol address can indicate the IP address of STA 1. AP 2 can send ARP packets on behalf of STA 1. ARP packets can be sent across the network without a separate request.

[0107] exist Figure 5 In the implementation scheme, before the roaming execution time of STA 1, AP 1 may attempt to send downlink packets with a destination address set to STA 1 and existing in AP 1's queue. In other words, AP 1 may send downlink packets to STA 1. After the roaming execution time, STA 1 may associate with AP 2 (e.g., access AP 2) and perform communication with AP 2 while associated with AP 2. The association process (e.g., access process) between STA 1 and AP 2 can be... Figure 3 and / or Figure 4 The illustrated implementation is the same or similar. After the roaming execution time, AP 1 may have downlink packets that were not sent to STA 1. AP 1 may send downlink packets that were not sent to STA 1 to AP 2. AP 2 can receive downlink packets from AP 1 and send downlink packets to STA 1.

[0108] As an alternative approach, AP 1 can be allowed to send downlink packets to STA 1 that were not originally sent to STA 1 after the roaming execution time. For example, after the roaming execution time, STA 1 can receive downlink packets from AP 1. The packets that AP 1 can send to STA 1 after the roaming execution time can be limited to downlink packets that were not sent from AP 1 to STA 1 before the roaming execution time. When AP 1 has not sent all packets with a destination address set to STA 1, AP 1 can send packets with a destination address set to STA 1 to AP 2, and AP 2 can send packets received from AP 1 to STA 1.

[0109] The aforementioned send / receive procedures for ARP packets can be performed on DS mapping. A DS mapping procedure (e.g., a DS mapping change procedure) can represent a packet path change procedure (e.g., a path switching procedure). According to the DS mapping procedure, the packet path can be changed from "STA 1 - serving AP (e.g., AP 1) - first DS (e.g., the DS to which the serving AP belongs)" to "STA 1 - target AP (e.g., AP 2) - second DS (e.g., the DS to which the target AP belongs)". In other words, according to the DS mapping procedure, the DS mapped to by STA 1 can be changed from the first DS to which the serving AP belongs to the first DS to which the target AP belongs. A DS mapping procedure can be performed on the roaming procedure of STA 1. A DS mapping procedure can be performed when the first DS to which the serving AP (e.g., AP 1) belongs and the second DS to which the target AP (e.g., AP 2) belongs are different. An ARP packet (e.g., an ARP frame) can be a request frame that requests the initiation of a DS mapping procedure. For example, an ARP packet can be a DS mapping request frame. At least one of the serving AP or the target AP can send a DS mapping request frame to initiate a DS mapping procedure.

[0110] For example, a serving AP can send a DS mapping request frame to a first DS (e.g., an entity within the first DS) to which the serving AP belongs. The DS mapping request frame sent by the serving AP may include information about the target AP (e.g., address information, capability information, and / or context information), information about STA 1 (e.g., address information, capability information, and / or context information), and / or information about a second DS to which the target AP belongs. The first DS can receive the DS mapping request frame from the serving AP and perform DS mapping (e.g., DS change, path change, path switch) based on the DS mapping request frame. When the DS mapping is complete, the first DS can send a DS mapping response frame (e.g., an ARP response frame) to the serving AP indicating the completion of the DS mapping process. The serving AP can receive the DS mapping response frame from the first DS and determine the completion of the DS mapping process based on the DS mapping response frame. The serving AP can notify the target AP that the DS mapping process is complete. When the DS mapping process is complete, packets can be sent and received via the path "STA 1 - target AP (e.g., AP 2) - second DS (e.g., the DS to which the target AP belongs)".

[0111] As another example, a target AP can send a DS mapping request frame to a second DS (e.g., an entity within the second DS) to which the target AP belongs. The DS mapping request frame sent by the target AP may include information about the serving AP (e.g., address information, capability information, and / or context information), information about STA 1 (e.g., address information, capability information, and / or context information), and / or information about the first DS to which the serving AP belongs. The second DS can receive the DS mapping request frame from the target AP and perform DS mapping (e.g., DS change, path change, path switch) based on the DS mapping request frame. When the DS mapping is complete, the second DS can send a DS mapping response frame to the target AP indicating that the DS mapping process is complete. The target AP can receive the DS mapping response frame from the second DS and determine that the DS mapping process is complete based on the DS mapping response frame. The target AP can notify the serving AP that the DS mapping process is complete. When the DS mapping process is complete, packets can be sent and received via the path "STA 1 - Target AP (e.g., AP 2) - Second DS (e.g., the DS to which the target AP belongs)".

[0112] It can be used Figure 5 Implementation plan and Figure 3 or Figure 4 A combination of implementation schemes. For example, the IP address reallocation process of STA 1 can be applied to... Figure 5 The implementation plan is as follows: When the IP address reallocation process of STA 1 is completed, the data frame sending / receiving process between STA 1 and AP 2 can be executed.

[0113] Figure 6 This is a timing diagram illustrating the ARP method in the roaming process.

[0114] refer to Figure 6 AP 1, AP 2, and / or STA 1 can operate in a wireless LAN. AP 1 can represent AP MLD1, and the operation of AP 1 can be interpreted as the operation of AP MLD1. AP 1 can be referred to as the first AP. AP 2 can represent AP MLD 2, and the operation of AP 2 can be interpreted as the operation of AP MLD 2. AP 2 can be referred to as the second AP. STA 1 can represent STA MLD 1, and the operation of STA 1 can be interpreted as the operation of STA MLD 1. STA 1 can be associated with AP 1 (e.g., access AP 1) and perform communication when associated with AP 1. STA 1 can perform a roaming procedure to communicate with AP 2. According to the roaming procedure, the AP associated with STA 1 can change from AP 1 to AP 2. In other words, according to the roaming procedure, the communication target of STA 1 can change from AP 1 to AP 2. AP 1 can represent the current AP or the serving AP. AP 2 can represent the target AP.

[0115] STA 1 can determine whether to execute a roaming procedure based on the strength (e.g., quality) of the received signal. For example, when the received signal strength of AP 1 (or the received signal strength of AP 1 plus offset (or margin)) is lower than the received signal strength of AP 2, STA 1 can determine to execute a roaming procedure from AP 1 to AP 2. The roaming procedure can be initiated by STA 1 sending a link addition request (or roaming request) for AP 2 (e.g., the target AP) to AP 1 (e.g., the serving AP). During the roaming procedure, STA 1 can execute an association procedure with AP 2 and then initiate communication with AP 2 after the association procedure is completed. Alternatively, during the roaming procedure, STA 1 can initiate communication with AP 2 without executing an association procedure with AP 2.

[0116] When STA 1 determines to initiate a roaming procedure, STA 1 may send a roaming request frame to AP 1. The roaming request frame may include the expected time for initiating the roaming procedure (e.g., the time during which STA 1 can communicate with AP 2), the target AP that STA 1 intends to connect to (e.g., AP 2), a list of target APs that STA 1 intends to connect to (e.g., a list of target APs including AP 2), STA 1's IP address, STA 1's subnet information, STA 1's MAC address, STA 1's AID, or at least STA 1's capability information. The roaming request frame may request the execution of a roaming procedure from the serving AP (e.g., AP 1) to the target AP (e.g., AP 2). The subnet may refer to a DS.

[0117] AP 1 can receive roaming request frames from STA 1 and execute procedures for exchanging roaming information with AP 2 based on the information included in the roaming request frames. AP 1 can identify the target AP (e.g., AP 2) based on the information included in the roaming request frames. During the roaming information exchange procedure, AP 1 and AP 2 can exchange the information included in the roaming request frames sent by STA 1. In addition to the information included in the roaming request frames sent by STA 1, information known to AP 1 about STA 1 (e.g., STA 1's IP address, STA 1's subnet information, IP reallocation indicator, STA 1's received signal strength, STA 1's MAC address, and / or STA 1's capability information) can be transmitted to AP 2. Furthermore, during the roaming information exchange procedure, AP 1 and AP 2 can exchange information included in the roaming response frames sent by AP 1 to STA 1. During the roaming information exchange procedure, AP 2 can obtain roaming information from AP 1. AP 2 can accept or reject roaming procedures based on roaming information. In other words, AP 2 can send information to AP 1 instructing it to accept or reject roaming procedures. Roaming information can be transmitted directly between AP 1 and AP 2 via a wired network (e.g., an Ethernet network). Alternatively, roaming information can be transmitted via specific network endpoints (e.g., the management entities of AP 1 and AP 2). As another method, the process for exchanging roaming information can be performed via the wireless network between AP 1 and AP 2 (e.g., wireless LAN frame exchange).

[0118] After the process for exchanging roaming information is completed, AP 1 may send a roaming response frame to STA 1. The roaming response frame may include information indicating whether AP 2 accepts the roaming procedure (e.g., roaming acceptance or roaming rejection), information about the time when STA 1 performed the roaming procedure (e.g., roaming execution time), AP 2's capability information, AP 2's IP address, AP 2's subnet information, AP 2's MAC address, AP 2's operating frequency (e.g., operating channel), an IP reallocation indicator, or at least one of the following: a neighbor cell report (e.g., RNR) containing information about AP 2. The IP reallocation indicator may be included in the neighbor cell report containing information about AP 2. The neighbor cell report may be replaced by a multilink element. When the neighbor cell report is replaced by a multilink element, the IP reallocation indicator may be included in the multilink element. Alternatively, both the multilink element and the neighbor cell report may be included in the roaming response frame.

[0119] Alternatively, AP 1 can execute the procedure for exchanging roaming information with AP 2 without receiving a roaming request frame from STA 1. After the procedure for exchanging roaming information is completed, AP 1 can send a roaming response frame to STA 1. In other words, AP 1 can send an unsolicited roaming response frame to STA 1. The unsolicited roaming response frame can be configured in the same or similar manner as a requested roaming response frame caused by a request from STA 1 (e.g., a roaming request frame).

[0120] Before the roaming execution time of STA 1, AP 1 may attempt to send downlink packets with a destination address set to STA 1 that are already in AP 1's queue. In other words, AP 1 may send downlink packets to STA 1. After the roaming execution time, STA 1 may associate with AP 2 (e.g., access AP 2) and perform communication with AP 2 while associated with it. The association process (e.g., access process) between STA 1 and AP 2 can be... Figure 3 and / or Figure 4 The illustrated implementation is the same or similar. After the roaming execution time, AP 1 may have downlink packets that were not sent to STA 1. AP 1 may send downlink packets that were not sent to STA 1 to AP 2. AP 2 may receive downlink packets from AP 1.

[0121] After the roaming process between STA 1 and AP 2 is completed, AP 2 can send ARP packets (e.g., ARP request packets, ARP frames, or ARP request frames) to the network (e.g., a wired Ethernet network or DS) to receive packets destined for STA 1 from the network. In other words, when the send / receive process of establishing request frames and establishing response frames is completed (e.g., when the association process between AP 2 and STA 1 is completed), AP 2 can send ARP frames to the network. The ARP frame may include STA 1's IP address. After AP 2 sends the ARP packet to the network, AP 2 can receive packets from the network with the destination address set to STA 1. AP 2 can store packets for transmission. ARP can be a protocol used to query and / or respond to relationships between Layer 2 and Layer 3 addresses (e.g., the relationship between MAC addresses and IP addresses). ARP packets can be Ethernet frames. Communication between each AP (e.g., AP 1 and AP 2) and the network can be performed via wireless or wired media. ARP packets sent to the network can include the destination MAC address, the source MAC address, and the body (e.g., the body of an Ethernet frame). The body of an Ethernet frame can have the structure shown in Table 1 above. The structure of an ARP packet can vary depending on the hierarchical structure of the network used.

[0122] refer to Figure 6 As per Table 1, the hardware type and protocol type can vary depending on the hardware type and communication protocol type of AP 2. For example, the hardware type can be Ethernet, and the protocol type can be IPv4 or IPv6. The hardware length (e.g., the hardware length field) can indicate the length of the hardware address (e.g., MAC address) of the hardware indicated by the hardware type. The hardware length can be indicated in bytes. When the hardware address is a MAC address, the MAC address is 48 bits long, so the hardware length (e.g., the hardware length field) can indicate 6. The protocol length (e.g., the protocol length field) can indicate the length of the protocol address (e.g., IP address) of the communication protocol indicated by the protocol type. The protocol length can be indicated in bytes. When the protocol address is an IPv4 address, the IPv4 address is 32 bits long, so the protocol length (e.g., the protocol length field) can indicate 4.

[0123] The action code indicates what action an ARP packet should take. In an ARP packet sent by AP 2, the action code can be set to 2. An action code of 2 indicates an ARP response. The sender hardware address can indicate the MAC address of STA 1. The sender protocol address can indicate the IP address of STA 1. The destination hardware address can be set to FF:FF:FF:FF:FF:FF, which is the broadcast MAC address. The destination protocol address can indicate the IP address of STA 1. AP 2 can send ARP packets on behalf of STA 1. ARP packets can be sent across the network without a separate request.

[0124] exist Figure 6 In this implementation, ARP packets for AP 2 can be sent after the roaming execution time of STA 1. In other words, ARP packets for AP 2 can be sent after STA 1 is associated with AP 2. Even after the roaming execution time of STA 1, the network can still send packets to AP 1 (which is the AP previously associated with STA 1) with a destination address set to STA 1. AP 1 can send packets received from the network (e.g., packets with a destination address set to STA 1) to AP 2. AP 2 can receive packets from AP 1. AP 2 can send packets received from the network and / or packets received from AP 1 to STA 1. STA 1 can receive packets from AP 2.

[0125] As an alternative approach, after the roaming execution time, AP 1 can be allowed to send packets to STA 1 with a destination address set to STA 1. For example, after the roaming execution time, STA 1 can receive packets from AP 1. The packets that AP 1 can send to STA 1 after the roaming execution time can be limited to those with a destination address set to STA 1 and received by AP 1 from the network after the roaming execution time. When AP 1 does not send all packets with a destination address set to STA 1, AP 1 can send packets with a destination address set to STA 1 to AP 2, and AP 2 can send packets received from AP 1 to STA 1.

[0126] The aforementioned send / receive procedures for ARP packets can be performed on DS mapping. A DS mapping procedure (e.g., a DS mapping change procedure) can represent a packet path change procedure (e.g., a path switching procedure). According to the DS mapping procedure, the packet path can be changed from "STA 1 - serving AP (e.g., AP 1) - first DS (e.g., the DS to which the serving AP belongs)" to "STA 1 - target AP (e.g., AP 2) - second DS (e.g., the DS to which the target AP belongs)". In other words, according to the DS mapping procedure, the DS mapped to by STA 1 can be changed from the first DS to which the serving AP belongs to the first DS to which the target AP belongs. A DS mapping procedure can be performed on the roaming procedure of STA 1. A DS mapping procedure can be performed when the first DS to which the serving AP (e.g., AP 1) belongs and the second DS to which the target AP (e.g., AP 2) belongs are different. An ARP packet (e.g., an ARP frame) can be a request frame that requests the initiation of a DS mapping procedure. For example, an ARP packet can be a DS mapping request frame. At least one of the serving AP or the target AP can send a DS mapping request frame to initiate a DS mapping procedure.

[0127] For example, a serving AP can send a DS mapping request frame to a first DS (e.g., an entity within the first DS) to which the serving AP belongs. The DS mapping request frame sent by the serving AP may include information about the target AP (e.g., address information, capability information, and / or context information), information about STA 1 (e.g., address information, capability information, and / or context information), and / or information about a second DS to which the target AP belongs. The first DS can receive the DS mapping request frame from the serving AP and perform DS mapping (e.g., DS change, path change, path switch) based on the DS mapping request frame. When the DS mapping is complete, the first DS can send a DS mapping response frame (e.g., an ARP response frame) to the serving AP indicating the completion of the DS mapping process. The serving AP can receive the DS mapping response frame from the first DS and determine the completion of the DS mapping process based on the DS mapping response frame. The serving AP can notify the target AP that the DS mapping process is complete. When the DS mapping process is complete, packets can be sent and received via the path "STA 1 - target AP (e.g., AP 2) - second DS (e.g., the DS to which the target AP belongs)".

[0128] As another example, a target AP can send a DS mapping request frame to a second DS (e.g., an entity within the second DS) to which the target AP belongs. The DS mapping request frame sent by the target AP may include information about the serving AP (e.g., address information, capability information, and / or context information), information about STA 1 (e.g., address information, capability information, and / or context information), and / or information about the first DS to which the serving AP belongs. The second DS can receive the DS mapping request frame from the target AP and perform DS mapping (e.g., DS change, path change, path switch) based on the DS mapping request frame. When the DS mapping is complete, the second DS can send a DS mapping response frame to the target AP indicating that the DS mapping process is complete. The target AP can receive the DS mapping response frame from the second DS and determine that the DS mapping process is complete based on the DS mapping response frame. The target AP can notify the serving AP that the DS mapping process is complete. When the DS mapping process is complete, packets can be sent and received via the path "STA 1 - Target AP (e.g., AP 2) - Second DS (e.g., the DS to which the target AP belongs)".

[0129] It can be used Figure 6 Implementation plan and Figure 3 or Figure 4 A combination of implementation schemes. For example, the IP address reallocation process of STA 1 can be applied to... Figure 6 The implementation plan is as follows: When the IP address reallocation process of STA 1 is completed, the data frame sending / receiving process between STA 1 and AP 2 can be executed.

[0130] Figure 7 This is a timing diagram illustrating the ARP method in the roaming process.

[0131] refer to Figure 7AP 1, AP 2, and / or STA 1 can operate in a wireless LAN. AP 1 can represent AP MLD1, and the operation of AP 1 can be interpreted as the operation of AP MLD1. AP 1 can be referred to as the first AP. AP 2 can represent AP MLD 2, and the operation of AP 2 can be interpreted as the operation of AP MLD 2. AP 2 can be referred to as the second AP. STA 1 can represent STA MLD 1, and the operation of STA 1 can be interpreted as the operation of STA MLD 1. STA 1 can be associated with AP 1 (e.g., access AP 1) and perform communication when associated with AP 1. STA 1 can perform a roaming procedure to communicate with AP 2. According to the roaming procedure, the AP associated with STA 1 can change from AP 1 to AP 2. In other words, according to the roaming procedure, the communication target of STA 1 can change from AP 1 to AP 2. AP 1 can represent the current AP or the serving AP. AP 2 can represent the target AP.

[0132] STA 1 can determine whether to execute a roaming procedure based on the strength (e.g., quality) of the received signal. For example, when the received signal strength of AP 1 (or the received signal strength of AP 1 plus offset (or margin)) is lower than the received signal strength of AP 2, STA 1 can determine to execute a roaming procedure from AP 1 to AP 2. The roaming procedure can be initiated by STA 1 sending a link addition request (or roaming request) for AP 2 (e.g., the target AP) to AP 1 (e.g., the serving AP). During the roaming procedure, STA 1 can execute an association procedure with AP 2 and then initiate communication with AP 2 after the association procedure is completed. Alternatively, during the roaming procedure, STA 1 can initiate communication with AP 2 without executing an association procedure with AP 2.

[0133] When STA 1 determines to initiate a roaming procedure, STA 1 may send a roaming request frame to AP 1. The roaming request frame may include the expected time for initiating the roaming procedure (e.g., the time during which STA 1 can communicate with AP 2), the target AP that STA 1 intends to connect to (e.g., AP 2), a list of target APs that STA 1 intends to connect to (e.g., a list of target APs including AP 2), STA 1's IP address, STA 1's subnet information, STA 1's MAC address, STA 1's AID, or at least STA 1's capability information. The roaming request frame may request the execution of a roaming procedure from the serving AP (e.g., AP 1) to the target AP (e.g., AP 2). The subnet may refer to a DS.

[0134] AP 1 can receive roaming request frames from STA 1 and execute procedures for exchanging roaming information with AP 2 based on the information included in the roaming request frames. AP 1 can identify the target AP (e.g., AP 2) based on the information included in the roaming request frames. During the roaming information exchange procedure, AP 1 and AP 2 can exchange the information included in the roaming request frames sent by STA 1. In addition to the information included in the roaming request frames sent by STA 1, information known to AP 1 about STA 1 (e.g., STA 1's IP address, STA 1's subnet information, IP reallocation indicator, STA 1's received signal strength, STA 1's MAC address, and / or STA 1's capability information) can be transmitted to AP 2. Furthermore, during the roaming information exchange procedure, AP 1 and AP 2 can exchange information included in the roaming response frames sent by AP 1 to STA 1. During the roaming information exchange procedure, AP 2 can obtain roaming information from AP 1. AP 2 can accept or reject roaming procedures based on roaming information. In other words, AP 2 can send information to AP 1 instructing it to accept or reject roaming procedures. Roaming information can be transmitted directly between AP 1 and AP 2 via a wired network (e.g., an Ethernet network). Alternatively, roaming information can be transmitted via specific network endpoints (e.g., the management entities of AP 1 and AP 2). As another method, the process for exchanging roaming information can be performed via the wireless network between AP 1 and AP 2 (e.g., wireless LAN frame exchange).

[0135] After the process for exchanging roaming information is completed, AP 1 may send a roaming response frame to STA 1. The roaming response frame may include information indicating whether AP 2 accepts the roaming procedure (e.g., roaming acceptance or roaming rejection), information about the time when STA 1 performed the roaming procedure (e.g., roaming execution time), AP 2's capability information, AP 2's IP address, AP 2's subnet information, AP 2's MAC address, AP 2's operating frequency (e.g., operating channel), an IP reallocation indicator, or at least one of the following: a neighbor cell report (e.g., RNR) containing information about AP 2. The IP reallocation indicator may be included in the neighbor cell report containing information about AP 2. The neighbor cell report may be replaced by a multilink element. When the neighbor cell report is replaced by a multilink element, the IP reallocation indicator may be included in the multilink element. Alternatively, both the multilink element and the neighbor cell report may be included in the roaming response frame.

[0136] Alternatively, AP 1 can execute the procedure for exchanging roaming information with AP 2 without receiving a roaming request frame from STA 1. After the procedure for exchanging roaming information is completed, AP 1 can send a roaming response frame to STA 1. In other words, AP 1 can send an unsolicited roaming response frame to STA 1. The unsolicited roaming response frame can be configured in the same or similar manner as a requested roaming response frame caused by a request from STA 1 (e.g., a roaming request frame).

[0137] Before the roaming execution time of STA 1, AP 1 may attempt to send downlink packets with a destination address set to STA 1 that are already in AP 1's queue. In other words, AP 1 may send downlink packets to STA 1. After the roaming execution time, STA 1 may associate with AP 2 (e.g., access AP 2) and perform communication with AP 2 while associated with it. The association process (e.g., access process) between STA 1 and AP 2 can be... Figure 3 and / or Figure 4 The illustrated implementation is the same or similar. After the roaming execution time, AP 1 may have downlink packets that were not sent to STA 1. AP 1 may send downlink packets that were not sent to STA 1 to AP 2. AP 2 may receive downlink packets from AP 1.

[0138] During roaming execution (e.g., before roaming execution), AP 2 may send ARP packets (e.g., ARP request packets, ARP frames, or ARP request frames) to the network (e.g., a wired Ethernet network, DS) to receive packets destined for STA 1 from the network. The ARP frame may include STA 1's IP address. After AP 2 sends the ARP packet to the network, AP 2 may receive packets from the network with the destination address set to STA 1. AP 2 may store packets for transmission. ARP may be a protocol used to query and / or respond to relationships between Layer 2 and Layer 3 addresses (e.g., the relationship between MAC addresses and IP addresses). The ARP packet may be an Ethernet frame. Communication between each AP (e.g., AP 1 and AP 2) and the network may be performed via wireless or wired media. The ARP packet sent to the network may include the destination MAC address, the source MAC address, and the body (e.g., the body of an Ethernet frame). The body of an Ethernet frame may have the structure shown in Table 1 above. The structure of the ARP packet may vary depending on the hierarchical structure of the network used.

[0139] refer to Figure 7As per Table 1, the hardware type and protocol type can vary depending on the hardware type and communication protocol type of AP 2. For example, the hardware type can be Ethernet, and the protocol type can be IPv4 or IPv6. The hardware length (e.g., the hardware length field) can indicate the length of the hardware address (e.g., MAC address) of the hardware indicated by the hardware type. The hardware length can be indicated in bytes. When the hardware address is a MAC address, the MAC address is 48 bits long, so the hardware length (e.g., the hardware length field) can indicate 6. The protocol length (e.g., the protocol length field) can indicate the length of the protocol address (e.g., IP address) of the communication protocol indicated by the protocol type. The protocol length can be indicated in bytes. When the protocol address is an IPv4 address, the IPv4 address is 32 bits long, so the protocol length (e.g., the protocol length field) can indicate 4.

[0140] The action code indicates what action an ARP packet should take. In an ARP packet sent by AP 2, the action code can be set to 2. An action code of 2 indicates an ARP response. The sender hardware address can indicate the MAC address of STA 1. The sender protocol address can indicate the IP address of STA 1. The destination hardware address can be set to FF:FF:FF:FF:FF:FF, which is the broadcast MAC address. The destination protocol address can indicate the IP address of STA 1. AP 2 can send ARP packets on behalf of STA 1. ARP packets can be sent across the network without a separate request.

[0141] exist Figure 7 In one implementation, ARP packets for AP 2 can be sent at the roaming execution time of STA 1 (e.g., before the roaming execution time). In other words, ARP packets for AP 2 can be sent at the time when STA 1 is associated with AP 2. Alternatively, ARP packets for AP 2 can be sent before STA 1 is associated with AP 2. The network can send packets to AP 1 (which is the AP previously associated with STA 1) with a destination address set to STA 1. AP 1 can send packets received from the network (e.g., packets with a destination address set to STA 1) to AP 2. AP 2 can receive packets from AP 1. AP 2 can send packets received from the network and / or packets received from AP 1 to STA 1. STA 1 can receive packets from AP 2.

[0142] As an alternative approach, after the roaming execution time, AP 1 can be allowed to send packets to STA 1 with a destination address set to STA 1. For example, after the roaming execution time, STA 1 can receive packets from AP 1. The packets that AP 1 can send to STA 1 after the roaming execution time can be limited to those with a destination address set to STA 1 and received by AP 1 from the network. When AP 1 does not send all packets with a destination address set to STA 1, AP 1 can send packets with a destination address set to STA 1 to AP 2, and AP 2 can send packets received from AP 1 to STA 1.

[0143] The aforementioned send / receive procedures for ARP packets can be performed on DS mapping. A DS mapping procedure (e.g., a DS mapping change procedure) can represent a packet path change procedure (e.g., a path switching procedure). According to the DS mapping procedure, the packet path can be changed from "STA 1 - serving AP (e.g., AP 1) - first DS (e.g., the DS to which the serving AP belongs)" to "STA 1 - target AP (e.g., AP 2) - second DS (e.g., the DS to which the target AP belongs)". In other words, according to the DS mapping procedure, the DS mapped to by STA 1 can be changed from the first DS to which the serving AP belongs to the first DS to which the target AP belongs. A DS mapping procedure can be performed on the roaming procedure of STA 1. A DS mapping procedure can be performed when the first DS to which the serving AP (e.g., AP 1) belongs and the second DS to which the target AP (e.g., AP 2) belongs are different. An ARP packet (e.g., an ARP frame) can be a request frame that requests the initiation of a DS mapping procedure. For example, an ARP packet can be a DS mapping request frame. At least one of the serving AP or the target AP can send a DS mapping request frame to initiate a DS mapping procedure.

[0144] For example, a serving AP can send a DS mapping request frame to a first DS (e.g., an entity within the first DS) to which the serving AP belongs. The DS mapping request frame sent by the serving AP may include information about the target AP (e.g., address information, capability information, and / or context information), information about STA 1 (e.g., address information, capability information, and / or context information), and / or information about a second DS to which the target AP belongs. The first DS can receive the DS mapping request frame from the serving AP and perform DS mapping (e.g., DS change, path change, path switch) based on the DS mapping request frame. When the DS mapping is complete, the first DS can send a DS mapping response frame (e.g., an ARP response frame) to the serving AP indicating the completion of the DS mapping process. The serving AP can receive the DS mapping response frame from the first DS and determine the completion of the DS mapping process based on the DS mapping response frame. The serving AP can notify the target AP that the DS mapping process is complete. When the DS mapping process is complete, packets can be sent and received via the path "STA 1 - target AP (e.g., AP 2) - second DS (e.g., the DS to which the target AP belongs)".

[0145] As another example, a target AP can send a DS mapping request frame to a second DS (e.g., an entity within the second DS) to which the target AP belongs. The DS mapping request frame sent by the target AP may include information about the serving AP (e.g., address information, capability information, and / or context information), information about STA 1 (e.g., address information, capability information, and / or context information), and / or information about the first DS to which the serving AP belongs. The second DS can receive the DS mapping request frame from the target AP and perform DS mapping (e.g., DS change, path change, path switch) based on the DS mapping request frame. When the DS mapping is complete, the second DS can send a DS mapping response frame to the target AP indicating that the DS mapping process is complete. The target AP can receive the DS mapping response frame from the second DS and determine that the DS mapping process is complete based on the DS mapping response frame. The target AP can notify the serving AP that the DS mapping process is complete. When the DS mapping process is complete, packets can be sent and received via the path "STA 1 - Target AP (e.g., AP 2) - Second DS (e.g., the DS to which the target AP belongs)".

[0146] It can be used Figure 7 Implementation plan and Figure 3 or Figure 4 A combination of implementation schemes. For example, the IP address reallocation process of STA 1 can be applied to... Figure 7 The implementation plan is as follows: When the IP address reallocation process of STA 1 is completed, the data frame sending / receiving process between STA 1 and AP 2 can be executed.

[0147] Figure 8 This is a timing diagram illustrating the ARP method in the roaming process.

[0148] refer to Figure 8 AP 1, AP 2, and / or STA 1 can operate in a wireless LAN. AP 1 can represent AP MLD1, and the operation of AP 1 can be interpreted as the operation of AP MLD1. AP 1 can be referred to as the first AP. AP 2 can represent AP MLD 2, and the operation of AP 2 can be interpreted as the operation of AP MLD 2. AP 2 can be referred to as the second AP. STA 1 can represent STA MLD 1, and the operation of STA 1 can be interpreted as the operation of STA MLD 1. STA 1 can be associated with AP 1 (e.g., access AP 1) and perform communication when associated with AP 1. STA 1 can perform a roaming procedure to communicate with AP 2. According to the roaming procedure, the AP associated with STA 1 can change from AP 1 to AP 2. In other words, according to the roaming procedure, the communication target of STA 1 can change from AP 1 to AP 2. AP 1 can represent the current AP or the serving AP. AP 2 can represent the target AP.

[0149] STA 1 can determine whether to execute a roaming procedure based on the strength (e.g., quality) of the received signal. For example, when the received signal strength of AP 1 (or the received signal strength of AP 1 plus offset (or margin)) is lower than the received signal strength of AP 2, STA 1 can determine to execute a roaming procedure from AP 1 to AP 2. The roaming procedure can be initiated by STA 1 sending a link addition request (or roaming request) for AP 2 (e.g., the target AP) to AP 1 (e.g., the serving AP). During the roaming procedure, STA 1 can execute an association procedure with AP 2 and then initiate communication with AP 2 after the association procedure is completed. Alternatively, during the roaming procedure, STA 1 can initiate communication with AP 2 without executing an association procedure with AP 2.

[0150] When STA 1 determines to initiate a roaming procedure, STA 1 may send a roaming request frame to AP 1. The roaming request frame may include the expected time for initiating the roaming procedure (e.g., the time during which STA 1 can communicate with AP 2), the target AP that STA 1 intends to connect to (e.g., AP 2), a list of target APs that STA 1 intends to connect to (e.g., a list of target APs including AP 2), STA 1's IP address, STA 1's subnet information, STA 1's MAC address, STA 1's AID, or at least STA 1's capability information. The roaming request frame may request the execution of a roaming procedure from the serving AP (e.g., AP 1) to the target AP (e.g., AP 2). The subnet may refer to a DS.

[0151] AP 1 can receive roaming request frames from STA 1 and execute procedures for exchanging roaming information with AP 2 based on the information included in the roaming request frames. AP 1 can identify the target AP (e.g., AP 2) based on the information included in the roaming request frames. During the roaming information exchange procedure, AP 1 and AP 2 can exchange the information included in the roaming request frames sent by STA 1. In addition to the information included in the roaming request frames sent by STA 1, information known to AP 1 about STA 1 (e.g., STA 1's IP address, STA 1's subnet information, IP reallocation indicator, STA 1's received signal strength, STA 1's MAC address, and / or STA 1's capability information) can be transmitted to AP 2. Furthermore, during the roaming information exchange procedure, AP 1 and AP 2 can exchange information included in the roaming response frames sent by AP 1 to STA 1. During the roaming information exchange procedure, AP 2 can obtain roaming information from AP 1. AP 2 can accept or reject roaming procedures based on roaming information. In other words, AP 2 can send information to AP 1 instructing it to accept or reject roaming procedures. Roaming information can be transmitted directly between AP 1 and AP 2 via a wired network (e.g., an Ethernet network). Alternatively, roaming information can be transmitted via specific network endpoints (e.g., the management entities of AP 1 and AP 2). As another method, the process for exchanging roaming information can be performed via the wireless network between AP 1 and AP 2 (e.g., wireless LAN frame exchange).

[0152] After the process for exchanging roaming information is completed, AP 1 may send a roaming response frame to STA 1. The roaming response frame may include information indicating whether AP 2 accepts the roaming procedure (e.g., roaming acceptance or roaming rejection), information about the time when STA 1 performed the roaming procedure (e.g., roaming execution time), AP 2's capability information, AP 2's IP address, AP 2's subnet information, AP 2's MAC address, AP 2's operating frequency (e.g., operating channel), an IP reallocation indicator, or at least one of the following: a neighbor cell report (e.g., RNR) containing information about AP 2. The IP reallocation indicator may be included in the neighbor cell report containing information about AP 2. The neighbor cell report may be replaced by a multilink element. When the neighbor cell report is replaced by a multilink element, the IP reallocation indicator may be included in the multilink element. Alternatively, both the multilink element and the neighbor cell report may be included in the roaming response frame.

[0153] Alternatively, AP 1 can execute the procedure for exchanging roaming information with AP 2 without receiving a roaming request frame from STA 1. After the procedure for exchanging roaming information is completed, AP 1 can send a roaming response frame to STA 1. In other words, AP 1 can send an unsolicited roaming response frame to STA 1. The unsolicited roaming response frame can be configured in the same or similar manner as a requested roaming response frame caused by a request from STA 1 (e.g., a roaming request frame).

[0154] With the above Figures 5 to 7 In a manner similar to or the same as the implementation scheme, AP 2 can send ARP packets (e.g., ARP request packets, ARP frames, or ARP request frames) to the network (e.g., a wired Ethernet network, DS) to receive packets to be transmitted to STA 1 from the network. The ARP frame may include STA 1's IP address. After AP 2 sends the ARP packet to the network, AP 2 can receive packets from the network with the destination address set to STA 1. AP 2 can store packets for transmission. At the time of STA 1's roaming execution, STA 1's roaming process may fail. For example, STA 1 may not be able to associate with AP 2 for a preset time (e.g., for a preset time from the roaming execution time). In other words, STA 1 may not be able to perform communication with AP 2 for a preset time (e.g., for a preset time from the roaming execution time). Alternatively, STA 1's roaming process may fail when AP 2 rejects STA 1's association (e.g., access, roaming). A failure of the roaming process of STA 1 can indicate a failure of the association process (e.g., establishing a process) between STA 1 and AP 2.

[0155] When STA 1's roaming process fails, STA 1 can resume communication with AP 1. When STA 1's roaming process fails, AP 2 can send a message to AP 1 indicating the roaming failure. AP 2 can send packets received from the network with the destination address set to STA 1 to AP 1. AP 1 can send ARP packets (e.g., ARP frames) to the network (e.g., a wired Ethernet network, DS) to receive packets to be transmitted to STA 1 from the network. The ARP frame may include STA 1's IP address. After AP 1 sends the ARP packet to the network, AP 1 can receive packets with the destination address set to STA 1 from the network. AP 1 can store packets for transmission. ARP packets sent by AP 1 to the network may include the destination MAC address, source MAC address, and body (e.g., the body of an Ethernet frame). The body of an Ethernet frame may have the structure shown in Table 1 above. The structure of the ARP packet can vary depending on the hierarchical structure of the network used.

[0156] refer to Figure 8 As per Table 1, the hardware type and protocol type can vary depending on the hardware type and communication protocol type of AP 1. For example, the hardware type can be Ethernet, and the protocol type can be IPv4 or IPv6. The hardware length (e.g., the hardware length field) can indicate the length of the hardware address (e.g., MAC address) of the hardware indicated by the hardware type. The hardware length can be indicated in bytes. When the hardware address is a MAC address, the MAC address is 48 bits long, so the hardware length (e.g., the hardware length field) can indicate 6. The protocol length (e.g., the protocol length field) can indicate the length of the protocol address (e.g., IP address) of the communication protocol indicated by the protocol type. The protocol length can be indicated in bytes. When the protocol address is an IPv4 address, the IPv4 address is 32 bits long, so the protocol length (e.g., the protocol length field) can indicate 4.

[0157] The action code indicates what action an ARP packet should take. In an ARP packet sent by AP 1, the action code can be set to 2. An action code of 2 indicates an ARP response. The sender hardware address can indicate the MAC address of STA 1. The sender protocol address can indicate the IP address of STA 1. The destination hardware address can be set to FF:FF:FF:FF:FF:FF, which is the broadcast MAC address. The destination protocol address can indicate the IP address of STA 1. AP 1 can send ARP packets on behalf of STA 1. ARP packets can be sent across the network without a separate request.

[0158] exist Figure 8In this implementation scheme, AP 1 can receive packets from the network with the destination address set to STA 1 after sending ARP packets. AP 1 can then send downlink frames to STA 1 based on the packets received from the network. STA 1 can receive downlink frames from AP 1.

[0159] The aforementioned send / receive procedures for ARP packets can be performed on DS mapping. A DS mapping procedure (e.g., a DS mapping change procedure) can represent a packet path change procedure (e.g., a path switching procedure). According to the DS mapping procedure, the packet path can be changed from "STA 1 - serving AP (e.g., AP 1) - first DS (e.g., the DS to which the serving AP belongs)" to "STA 1 - target AP (e.g., AP 2) - second DS (e.g., the DS to which the target AP belongs)". In other words, according to the DS mapping procedure, the DS mapped to by STA 1 can be changed from the first DS to which the serving AP belongs to the first DS to which the target AP belongs. A DS mapping procedure can be performed on the roaming procedure of STA 1. A DS mapping procedure can be performed when the first DS to which the serving AP (e.g., AP 1) belongs and the second DS to which the target AP (e.g., AP 2) belongs are different. An ARP packet (e.g., an ARP frame) can be a request frame that requests the initiation of a DS mapping procedure. For example, an ARP packet can be a DS mapping request frame. At least one of the serving AP or the target AP can send a DS mapping request frame to initiate a DS mapping procedure.

[0160] For example, a serving AP can send a DS mapping request frame to a first DS (e.g., an entity within the first DS) to which the serving AP belongs. The DS mapping request frame sent by the serving AP may include information about the target AP (e.g., address information, capability information, and / or context information), information about STA 1 (e.g., address information, capability information, and / or context information), and / or information about a second DS to which the target AP belongs. The first DS can receive the DS mapping request frame from the serving AP and perform DS mapping (e.g., DS change, path change, path switch) based on the DS mapping request frame. When the DS mapping is complete, the first DS can send a DS mapping response frame (e.g., an ARP response frame) to the serving AP indicating the completion of the DS mapping process. The serving AP can receive the DS mapping response frame from the first DS and determine the completion of the DS mapping process based on the DS mapping response frame. The serving AP can notify the target AP that the DS mapping process is complete. When the DS mapping process is complete, packets can be sent and received via the path "STA 1 - target AP (e.g., AP 2) - second DS (e.g., the DS to which the target AP belongs)".

[0161] As another example, a target AP can send a DS mapping request frame to a second DS (e.g., an entity within the second DS) to which the target AP belongs. The DS mapping request frame sent by the target AP may include information about the serving AP (e.g., address information, capability information, and / or context information), information about STA 1 (e.g., address information, capability information, and / or context information), and / or information about the first DS to which the serving AP belongs. The second DS can receive the DS mapping request frame from the target AP and perform DS mapping (e.g., DS change, path change, path switch) based on the DS mapping request frame. When the DS mapping is complete, the second DS can send a DS mapping response frame to the target AP indicating that the DS mapping process is complete. The target AP can receive the DS mapping response frame from the second DS and determine that the DS mapping process is complete based on the DS mapping response frame. The target AP can notify the serving AP that the DS mapping process is complete. When the DS mapping process is complete, packets can be sent and received via the path "STA 1 - Target AP (e.g., AP 2) - Second DS (e.g., the DS to which the target AP belongs)".

[0162] It can be used Figure 8 Implementation plan and Figure 3 or Figure 4 A combination of implementation schemes. For example, the IP address reallocation process of STA 1 can be applied to... Figure 8 The implementation plan is as follows: When the IP address reallocation process of STA 1 is completed, the data frame sending / receiving process between STA 1 and AP 2 can be executed.

[0163] The operation of the method according to embodiments of the present invention can be implemented as a computer-readable program or code in a computer-readable recording medium. A computer-readable recording medium includes every type of recording device storing information readable by a computer system. Furthermore, the computer-readable recording medium can be distributed across computer systems connected via a network, allowing the computer-readable program or code to be stored and executed in a distributed manner.

[0164] Additionally, computer-readable recording media may include hardware devices specifically configured to store and execute program commands, such as ROM, RAM, or flash memory. Program commands may include not only machine language code created by a compiler but also high-level language code that can be executed by a computer using an interpreter.

[0165] Although some aspects of the invention have been described in the context of apparatus, these aspects may refer to the corresponding description according to the method, and blocks or devices may correspond to steps or features of the method. Similarly, aspects described in the context of the method may be expressed as features of corresponding blocks or items or corresponding devices. Some or all steps of the method may be performed by (or utilizing) hardware devices such as microprocessors, programmable computers, or electronic circuits. In some embodiments, one or more of the most important steps of the method may be performed by such devices.

[0166] In implementations, a programmable logic device (e.g., a field-programmable gate array) can be used to perform some or all of the functions of the methods described herein. In implementations, the field-programmable gate array can be operated by a microprocessor to perform one of the methods described herein. Typically, the methods are preferably performed by specific hardware devices.

[0167] Although the invention has been described above with reference to preferred embodiments thereof, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the scope and spirit of the invention as defined by the appended claims.

Claims

1. A method for a first access point (AP), the method comprising: Send a DS mapping request frame to the first distributed system (DS) to which the first AP belongs for use in the station (STA) roaming process; as well as Receive a DS mapping response frame from the first DS indicating that the DS mapping process is complete. In this process, based on the DS mapping process, the DS mapped to by the STA is changed from the first DS to the second DS belonging to the second AP. The first AP is the serving AP, and the second AP is the target AP.

2. The method according to claim 1, wherein, Based on the DS mapping process, the transmission path for packets used by the STA is changed from the path from STA to the first AP to the first DS to the path from STA to the second AP to the second DS.

3. The method of claim 1, further comprising sending information to the second AP indicating that the DS mapping process is complete.

4. The method according to claim 1, wherein, The DS mapping process is performed based on the fact that the first DS to which the first AP belongs is different from the second DS to which the second AP belongs.

5. The method according to claim 1, wherein, The DS request frame includes at least one of the following: information about the second AP, information about the second DS, or information about the STA.

6. The method according to claim 1, wherein, The DS mapping request frame is an Address Resolution Protocol (ARP) request frame, and the DS mapping response frame is an ARP response frame.

7. The method of claim 1, further comprising: Receive roaming request frames from STAs connected to the first AP; as well as Send a roaming response frame to the STA as a response to the roaming request frame.

8. The method of claim 7, further comprising performing a process of exchanging roaming information with a second AP based on receiving a roaming request frame.

9. The method according to claim 7, wherein, The roaming response frame includes information indicating that the second AP accepts the roaming procedure.

10. The method according to claim 1, wherein, The STA is a STA associated with a STA multi-link device (MLD), the first AP is an AP associated with a first AP MLD, and the second AP is an AP associated with a second AP MLD.

11. A method for a second access point (AP), the method comprising: Send a DS mapping request frame to the second distributed system (DS) to which the second AP belongs for use in the station (STA) roaming process; as well as Receive a DS mapping response frame from the second DS indicating that the DS mapping process is complete. In this process, based on the DS mapping procedure, the DS mapped to by the STA is changed from the first DS belonging to the first AP to the second DS. The first AP is the serving AP, and the second AP is the target AP.

12. The method according to claim 11, wherein, Based on the DS mapping process, the transmission path for packets used by the STA is changed from the path from STA to the first AP to the first DS to the path from STA to the second AP to the second DS.

13. The method of claim 11, further comprising sending information to the first AP indicating that the DS mapping process is complete.

14. The method according to claim 11, wherein, The DS mapping process is performed based on the fact that the first DS to which the first AP belongs is different from the second DS to which the second AP belongs.

15. The method according to claim 11, wherein, The DS request frame includes at least one of the following: information about the first AP, information about the first DS, or information about the STA.

16. The method according to claim 11, wherein, The DS mapping request frame is an Address Resolution Protocol (ARP) request frame, and the DS mapping response frame is an ARP response frame.

17. The method of claim 11, further comprising initiating a roaming process based on a STA request to perform a process of exchanging roaming information with a first AP.

18. The method of claim 17, further comprising performing an association process between the second AP and the STA based on the roaming process of the second AP accepting the STA.

19. The method according to claim 18, wherein, The process of establishing the association between the second AP and STA includes: Receive a setup request frame from the STA; and Send an establishment response frame to the STA as a response to the establishment request frame.

20. The method according to claim 11, wherein, The STA is a STA associated with a STA multi-link device (MLD), the first AP is an AP associated with a first AP MLD, and the second AP is an AP associated with a second AP MLD.

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