Communication method and apparatus

Abstract

Embodiments of the present application relates to a communication method and an apparatus. The method comprises: a target AP MLD receiving first downlink data sent by a current AP MLD; the target AP MLD encrypting the first downlink data by using a second key, so as to obtain second downlink data, wherein the second key is a key negotiated by the target AP MLD and a non-AP MLD, and the target AP MLD is an AP MLD for the non-AP MLD after transferring of a basic service set (BSS); and the target AP MLD sending the second downlink data to the non-AP MLD. The method in the embodiments of the present application can improve the roaming performance of non-AP MLDs.

Description

Communication method and device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on July 29, 2023, with application number 202310952314.0 and invention name "A Communication Method and Device", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The embodiments of the present application relate to the field of communication technology, and in particular to a communication method and apparatus. Background Art

[0004] Due to factors such as the mobility of non-access point (non-AP) multi-link devices (MLDs), non-AP MLDs need to switch their associated access point (AP) MLDs. During roaming, non-AP MLDs often experience speed drops (i.e., reduced transmission rates). Improving the roaming performance of non-AP MLDs is a key research topic for next-generation wireless fidelity (Wi-Fi) roaming.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a communication method and apparatus, which enable data transmission between a current AP MLD and a target AP MLD during roaming, thereby improving the roaming performance of a non-AP MLD.

[0007] In a first aspect, a communication method is provided, including: a target access point AP multi-link device (MLD) receiving first downlink data sent by a current AP MLD; the target AP MLD encrypting the first downlink data using a second key to obtain second downlink data, wherein the second key is a key negotiated between the target AP MLD and a non-access point non-AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after a basic service set (BSS) transfer; and the target AP MLD sending the second downlink data to the non-AP MLD.

[0008] According to a second aspect, a communication method is provided, including: a target access point AP multi-link device MLD receives first uplink data sent by a non-access point non-AP MLD; the target AP MLD uses a second key to decrypt the first uplink data to obtain second uplink data, where the second key is a key negotiated between the target AP MLD and the non-AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred; and the target AP MLD sends the second uplink data to the current AP MLD.

[0009] In one design, a first transmission link exists between the non-AP MLD and the current AP MLD, and the method further includes: the target AP MLD receiving a first request, where the first request is used to request establishment of a second transmission link between the non-AP MLD and the target AP MLD; and the target AP MLD establishing the second transmission link with the non-AP MLD.

[0010] In one design, the first request includes indication information for enabling dual-link transmission of the non-AP MLD, where the dual-link includes the first transmission link and the second transmission link.

[0011] In one design, the target AP MLD further includes sending a second request to the current AP MLD, where the second request is used to request to enable dual-link transmission of the non-AP MLD.

[0012] In one design, it also includes: the target AP MLD receives a third request, where the third request is used to request triggering path switching of the non-AP MLD; the target AP MLD sends a fourth request to the distributed system DS, where the fourth request is used to request the DS to update the stored mapping relationship between the non-AP MLD and the current AP MLD to: the mapping relationship between the non-AP MLD and the target AP MLD.

[0013] In one design, the first request and / or the third request is sent by the non-AP MLD, and the first request and / or the third request is transmitted through the air interface between the non-AP MLD and the target AP MLD, or through the current AP MLD and DS.

[0014] In one design, when the first request is transmitted through the current AP MLD and DS, the first request does not include operating channel information (OCI).

[0015] In one design, after the target AP MLD receives the third request and before the target AP MLD sends the fourth request to the DS, it also includes: the target AP MLD sends a context transfer request to the current AP MLD; the target AP MLD receives a context transfer response sent by the current AP MLD, and the context transfer response includes the context information of the non-AP MLD.

[0016] In one design, the context transfer response also includes at least one of the following: a block determination protocol of a service identifier TID, a window starting position of a send buffer of the TID, a window size of a send buffer of the TID, a window starting position of an uplink receiving end scoreboard, a window size of the uplink receiving end scoreboard, a window starting position of a receive reordering buffer, a window size of the receive reordering buffer, a maximum packet sequence number PN value currently received, or an uplink replay counter.

[0017] In one design, after the transmission path of the non-AP MLD is switched from the first transmission path to the second transmission path, the non-AP MLD and the target AP MLD use a second key negotiated between the two to encrypt and decrypt uplink data and / or downlink data.

[0018] According to a third aspect, a communication method is provided, including: a current access point AP multi-link device MLD receives third downlink data sent by a distributed system DS; the current AP MLD performs high media access control MAC layer processing on the third downlink data to obtain first downlink data, and the high MAC layer processing does not include encrypting the third downlink data; the current AP MLD sends the first downlink data to a target AP MLD, and the target AP MLD is the AP MLD of a non-access point non-AP MLD after the basic service set BSS is transferred.

[0019] In a fourth aspect, a communication method is provided, including: a current access point AP multi-link device MLD receives second uplink data sent by a target AP MLD, where the second uplink data is data decrypted using a second key, and the second key is a key negotiated between the target AP MLD and the non-access point non-AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred; the current AP MLD performs high media access control MAC layer processing on the second uplink data to obtain third uplink data, and the high MAC layer processing does not include decryption of the second uplink data; the current AP MLD sends the uplink data to a distributed system DS.

[0020] In one design, the high MAC layer processing includes: repeating detection of the uplink data packet.

[0021] In one design, there is a first transmission link between the current AP MLD and the non-AP MLD, and the design also includes: the current AP MLD receives a second request sent by the target AP MLD, the second request is used to request to enable dual-link transmission of the non-AP MLD, and the dual link includes the first transmission link and a second transmission link between the non-AP MLD and the target AP MLD.

[0022] In one design, it also includes: the current AP MLD receives a fifth request sent by the non-AP MLD, the fifth request is used to request to disconnect the first transmission link between the non-AP MLD and the current AP MLD, the fifth request includes first indication information, the first indication information instructs the current AP MLD to retain the block acknowledgment BA information and / or context information of the non-AP MLD, and cache the data not sent by the non-AP MLD; the current AP MLD sends a sixth request to the DS, the sixth request is used to request to delete the mapping relationship between the non-AP MLD and the current AP MLD stored in the DS.

[0023] In one design, the method further includes: the current AP MLD receiving a context transfer request sent by the target AP MLD; and the current AP MLD sending a context transfer response to the target AP MLD, wherein the context transfer response includes context information of the non-AP MLD.

[0024] In one design, the context transfer response also includes at least one of the following: a block determination protocol of a service identifier TID, a window starting position of a send buffer of the TID, a window size of the send buffer of the TID, a window starting position of an uplink receiving end scoreboard, a window size of the uplink receiving end scoreboard, a window starting position of a receive reordering buffer, a window size of the receive reordering buffer, a maximum packet sequence number PN value currently received, or an uplink replay counter.

[0025] In one design, the further configuration includes: the current AP MLD sending a beacon measurement request to the non-AP MLD, wherein the beacon measurement request includes indication information of a corresponding link of the serving AP.

[0026] In one design, it also includes: the current AP MLD sends a seventh request to the non-AP MLD, the seventh request includes second indication information, and the second indication information instructs the non-AP MLD to retain the BA information and / or context information of the non-AP MLD and cache the data not sent by the non-AP MLD.

[0027] In a fifth aspect, a communication method is provided, including: a non-access point non-AP multi-link device MLD receives second downlink data sent by a target access point AP MLD, where the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred; the non-AP MLD uses a second key to decrypt the second downlink data to obtain fourth downlink data, where the second key is a key negotiated between the target AP MLD and the non-AP MLD; the non-AP MLD receives fifth downlink data sent by a current AP MLD; the non-AP MLD uses a first key to decrypt the fifth downlink data to obtain sixth downlink data, where the first key is a key negotiated between the current AP MLD and the non-AP MLD.

[0028] In a sixth aspect, a communication method is provided, including: a non-access point non-AP multi-link device MLD uses a second key to encrypt uplink data to be transmitted to obtain first uplink data, where the second key is a key negotiated between a target access point AP MLD and the non-AP MLD; the non-AP MLD sends the first uplink data to the target AP MLD; the non-AP MLD uses a first key to encrypt the uplink data to be transmitted to obtain fourth uplink data, where the first key is a key negotiated between a current AP MLD and the non-AP MLD; the non-AP MLD sends the fourth uplink data to the current AP MLD, where the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred.

[0029] In one design, there is a first transmission link between the non-AP MLD and the current AP MLD, and the design also includes: the non-AP MLD sends a first request, where the first request is used to request establishment of a second transmission link between the non-AP MLD and the target AP MLD.

[0030] In one design, the first request includes indication information for enabling dual-link transmission of the non-AP MLD, where the dual-link includes the first transmission link and the second transmission link.

[0031] In one design, the non-AP MLD further includes sending a third request, where the third request is used to request triggering path switching of the non-AP MLD.

[0032] In one design, the first request and / or the third request is sent to the target AP MLD, and the first request and / or the third request is transmitted through the air interface between the non-AP MLD and the target AP MLD, or through the current AP MLD and the distributed system DS.

[0033] In one design, when the first request is transmitted via the current AP MLD and DS, the first request does not include operating channel information (OCI).

[0034] In one design, it also includes: the non-AP MLD sends a fifth request to the current AP MLD, the fifth request includes first indication information, the first indication information instructs the current AP MLD to retain the block acknowledgment BA information and / or context information of the non-AP MLD, and cache the data not sent by the non-AP MLD.

[0035] In one design, the non-AP MLD receives a beacon measurement request sent by the current AP MLD, where the beacon measurement request includes indication information of a link corresponding to the serving AP.

[0036] In one design, it also includes: the non-AP MLD receives a seventh request sent by the current AP MLD, the seventh request includes second indication information, and the second indication information instructs the non-AP MLD to retain the BA information and / or context information of the non-AP MLD and cache the data not sent by the non-AP MLD.

[0037] In one design, after the transmission path of the non-AP MLD is switched from the first transmission path to the second transmission path, the non-AP MLD and the target AP MLD use a second key negotiated between the two to encrypt and decrypt uplink data and / or downlink data.

[0038] In one design, in the above aspects, data is sent or received between the current AP MLD and the target AP MLD using transparent transmission.

[0039] In a seventh aspect, a device is provided that can implement the method of the first or second aspect. For example, the device includes means for executing the corresponding method of the first aspect. The device can be implemented through hardware, software, or hardware executing the corresponding software implementation.

[0040] In one design, the apparatus includes a unit for performing the first or second aspect described above.

[0041] In one design, the apparatus includes a processor and a memory, and the processor is configured to execute a computer program or instructions stored in the memory, so that the apparatus implements the method of the first aspect or the second aspect described above.

[0042] In one design, the device includes a processor and an interface circuit, the interface circuit is used to receive signals from other devices outside the device and transmit them to the processor or send signals from the processor to other devices outside the device, and the processor is used to implement the method of the first aspect or the second aspect above through logic circuits or executing code instructions.

[0043] In an eighth aspect, a device is provided that can implement the method of the third or fourth aspect. For example, the device includes means for executing the corresponding method of the third or fourth aspect. The device can be implemented through hardware, software, or hardware executing the corresponding software implementation.

[0044] In one design, the apparatus includes a unit for performing the third or fourth aspect described above.

[0045] In one design, the device includes a processor and a memory, and the processor is used to execute a computer program or instructions stored in the memory, so that the device implements the method of the third aspect or the fourth aspect above.

[0046] In one design, the device includes a processor and an interface circuit, the interface circuit is used to receive signals from other devices outside the device and transmit them to the processor or send signals from the processor to other devices outside the device, and the processor is used to implement the method in the third aspect or the fourth aspect above through logic circuits or executing code instructions.

[0047] In a ninth aspect, a device is provided that can implement the method of the fifth or sixth aspect. For example, the device includes means for executing the corresponding method of the fifth or sixth aspect. The device can be implemented through hardware, software, or hardware executing the corresponding software implementation.

[0048] In one design, the apparatus includes a unit for performing the fifth or sixth aspect described above.

[0049] In one design, the device includes a processor and a memory, and the processor is used to execute a computer program or instruction stored in the memory, so that the device implements the method of the fifth or sixth aspect above.

[0050] In one design, the device includes a processor and an interface circuit, the interface circuit is used to receive signals from other devices outside the device and transmit them to the processor or send signals from the processor to other devices outside the device, and the processor is used to implement the method in the above-mentioned fifth aspect or sixth aspect through logic circuits or executing code instructions.

[0051] In a tenth aspect, a computer-readable storage medium is provided, which stores a computer program or instruction. When the computer program or instruction is executed on a computer, the computer implements the methods of the first to second aspects above.

[0052] In an eleventh aspect, a computer program product is provided, comprising a computer program or instructions, which enables the method of the first or second aspect to be executed when the computer program or instructions are executed by a computer.

[0053] In the twelfth aspect, a chip is provided, comprising a processor, wherein the processor is coupled to a memory and is used to execute computer programs or instructions stored in the memory, so that the chip implements the method of the first or second aspect above.

[0054] In the thirteenth aspect, a communication system is provided, comprising: a first communication device, a second communication device and a third communication device; wherein the first communication device is used to implement the method of the first or second aspect above, the second communication device is used to implement the method of the third or fourth aspect above, and the third communication device is used to implement the method of the fifth or sixth aspect above. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG1 is a schematic diagram of a multi-link device MLD provided in an embodiment of the present application;

[0056] FIG2 is a schematic diagram of an application scenario provided by an embodiment of the present application;

[0057] FIG3 is a flowchart of downlink data transmission provided by an embodiment of the present application;

[0058] FIG4 is a schematic diagram of processing downlink data provided in an embodiment of the present application;

[0059] FIG5 is a flowchart of uplink data transmission provided by an embodiment of the present application;

[0060] FIG6 is a schematic diagram of processing uplink data provided in an embodiment of the present application;

[0061] FIG7a is a flowchart of roaming handover provided in an embodiment of the present application;

[0062] Figures 7b and 7c are schematic diagrams of message formats provided by the present application;

[0063] FIG8 is another flowchart of roaming handover provided in an embodiment of the present application;

[0064] Figures 9, 10 and 11 are schematic diagrams of message formats provided in embodiments of the present application;

[0065] 12 and 13 are schematic diagrams of the structure of the device provided in the embodiments of the present application. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the embodiments of the present application will be further described in detail with reference to the accompanying drawings. The specific operation methods and functional descriptions in the method embodiments can also be applied to the device embodiments or system embodiments.

[0067] The embodiments of the present application can be applied to wireless local area network (WLAN) systems, and can be applied to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 series protocols used by WLANs, such as 802.11be, 802.11bf, and future 802.11 protocols. The methods provided in the embodiments of the present application can be implemented by a communication device in a wireless communication system or a chip or circuit used in the communication device. Accordingly, the communication device supports communication using the IEEE 802.11 series protocols. Although the embodiments of the present application are mainly described using a network deploying IEEE 802.11 as an example, it will be readily understood by those skilled in the art that the various aspects involved in the embodiments of the present application can be extended to other networks that adopt various standards or protocols, such as Bluetooth, high-performance wireless local area network (LAN) (HIPERLAN) (a wireless standard similar to the IEEE 802.11 standard, mainly used in Europe), and wide area network (WAN), WLAN, personal area network (PAN) or other networks now known or developed later. The technical solutions of the embodiments of the present application can be applied to various cellular communication systems, such as the fifth generation (5G) system, new radio (NR), and future sixth generation (6G) systems.

[0068] IEEE802.11's next-generation wireless fidelity (Wi-Fi) extremely high throughput (EHT) can use multi-link technology to increase transmission rates. A device with multi-link aggregation capabilities is called a multi-link device (MLD). In one design, MLD can mean that the device has multiple radio frequency modules, each operating on a different frequency band / channel. When the channel spacing between two radio frequency modules in a device is large enough, they can operate independently without interfering with each other. If any two links support sending on one link while receiving on the other link, the two links are said to support simultaneous transmit and receive (STR) capability. Otherwise, the two links are said to not support simultaneous transmit and receive capability, that is, the two links are said to be non-STR.

[0069] MLDs can include non-access point (non-AP) MLDs and / or access point (AP) MLDs. A non-AP MLD can also be called a station (STA) MLD. Non-AP MLDs and AP MLDs can communicate with each other. As shown in Figure 1, an MLD (such as an AP MLD or a non-AP MLD) can include a physical layer (PHY) (PHY#1, PHY#2, and PHY#n as shown in Figure 1) and a medium access control (MAC) layer. The physical layer can be used to process physical layer signals, and the MAC layer can be used to process MAC layer signals. Furthermore, the MAC layer can be divided into an upper-MAC (UMAC) layer (UMAC as shown in Figure 1) and multiple lower-MAC (LMAC) layers (LMAC#1, LMAC#2, LMAC#n as shown in Figure 1). As shown in Figure 1, the multiple APs included in the AP MLD are independent of each other in the lower-MAC layer and PHY layer, but share the upper-MAC layer. The multiple STAs included in the non-AP MLD are independent of each other at the low MAC layer and PHY layer, but share the high MAC layer. The high MAC layer is connected to multiple low MAC layers, meaning that the high MAC layer is shared by multiple links. Exemplarily, the high MAC layer primarily performs operations such as allocating sequence numbers (SNs) and packet numbers (PNs) for MAC service data units (MSDUs), as well as encryption and decryption. Exemplarily, the low MAC layer primarily performs operations such as assembling MAC protocol data units (MPDUs) for each link, channel access, and packet transmission and reception confirmation.

[0070] In Figure 1, the PHY#1, lower MAC#1, and upper MAC layers in the AP MLD are considered AP#1, the PHY#2, lower MAC#2, and upper MAC layers are considered AP#2, and so on. The PHY#n, lower MAC#n, and upper MAC layers are considered AP#n. This means that the AP MLD includes n AP entities. The situation is similar in non-AP MLD, where the upper MAC layer is also shared by multiple links. The PHY#1, lower MAC#1, and upper MAC layers are considered STA#1, the PHY#2, lower MAC#2, and upper MAC layers are considered STA#2, and so on. The PHY#n, lower MAC#n, and upper MAC layers are considered STA#n. This means that the non-AP MLD includes n STA entities. As shown in Figure 1, PHY#1 of AP#1 in the AP MLD and PHY#1 of STA#1 in the non-AP MLD operate on the same channel. AP#1 in the AP MLD and STA#1 in the non-AP MLD communicate with each other via a link (link #1 in Figure 1). PHY#2 of AP#2 in the AP MLD and PHY#2 of STA#2 in the non-AP MLD operate on another identical channel. AP#2 in the AP MLD and STA#2 in the non-AP MLD communicate with each other via a link (link #2 in Figure 1). PHY#n of AP#n in the AP MLD and PHY#n of STA#n in the non-AP MLD operate on another identical channel. AP#n in the AP MLD and STA#n in the non-AP MLD communicate with each other via a link (link #n in Figure 1).

[0071] In an embodiment of the present application, a non-AP MLD may switch its associated AP MLD due to factors such as movement. For example, due to the movement of the non-AP MLD, it moves from the coverage area of ​​AP MLD1 to the coverage area of ​​AP MLD2. Therefore, the AP MLD associated with the non-AP MLD may need to be switched. In one design, when switching, the non-AP MLD first disconnects the old link with the current AP MLD and then establishes a new link with the target AP MLD. Due to the interruption of the transmission link, there is a risk of data speed drop during the switching process. In the solution of an embodiment of the present application, the non-AP MLD first establishes a second transmission link with the target AP MLD, and the non-AP MLD and the current AP MLD continue to transmit data. Later, at a certain point in time, the non-AP MLD disconnects the first transmission link with the current AP MLD. During the switching process, the non-AP MLD utilizes its multi-link capability to simultaneously transmit data with the current AP MLD and the target AP MLD. Since non-AP MLD always has a transmission link during the entire handover process, there is no possibility of complete link interruption, which reduces the risk of speed drop during the handover process.

[0072] In the solution provided in the embodiment of the present application, during handover or roaming of a non-AP MLD, when dual connectivity transmission is enabled, for downlink transmission, the current AP MLD and the non-AP MLD use a first key negotiated between them to encrypt and decrypt uplink data and / or downlink data transmitted between them. The target AP MLD and the non-AP MLD use a second key negotiated between them to encrypt and decrypt uplink data and / or downlink data transmitted between them.

[0073] As shown in FIG2 , a communication system is provided, which includes a non-AP MLD and an AP MLD.

[0074] In embodiments of the present application, a non-AP MLD may be a device with wireless transceiver capabilities. For example, a non-AP MLD may be a terminal device, user equipment (UE), access terminal, subscriber unit (SU), user station, mobile station, remote station, remote terminal, mobile device, user terminal, wireless communication device, user agent, or user device. In specific applications, a non-AP MLD may be a cellular phone, mobile phone, tablet computer, wearable device, smart point of sale (POS) machine, customer-premises equipment (CPE), a computer with wireless transceiver capabilities, virtual reality (VR) terminal, augmented reality (AR) terminal, terminal equipment in industrial control, terminal equipment in self-driving, terminal equipment in remote medical, terminal equipment in smart grid, terminal equipment in smart city, terminal equipment in smart home, etc.

[0075] In this application example, the non-AP MLD may include multiple links, each corresponding to a different STA entity. The multiple STA entities are independent of each other at the lower MAC and PHY layers and share the higher MAC layer. These multiple STA entities typically operate on different frequency bands or channels. In the example of Figure 2, the non-AP MLD includes two STA entities, namely STA1 and STA2. Both STA1 and STA2 can operate in the 2.4 GHz and 5 GHz frequency bands. At a certain moment, STA1 and STA2 operate in different frequency bands.

[0076] AP MLD can be APMLD1 and / or APMLD2 in Figure 2. In the embodiment of the present application, AP MLD is a device such as a wireless hub or router for providing wireless network access services, and can serve as an access point for non-AP MLD to enter the wired Ethernet backbone.

[0077] Similar to non-AP MLD, AP MLD can include multiple links, each corresponding to a different AP entity. These AP entities are independent at the lower MAC and PHY layers but share the higher MAC layer. These AP entities typically operate on different frequency bands or channels. In the example in Figure 2, AP MLD1 and AP MLD2 each include two AP entities, AP1 and AP2. AP1 and AP2 operate on different frequency bands: AP1 operates at 2.4 GHz, and AP2 operates at 5 GHz.

[0078] In one design, before handover or roaming, the non-AP MLD is associated with AP MLD1, which is called the current AP MLD. Specifically, as shown in Figure 2, STA1 operates in the 2.4 GHz band and establishes a link with AP1. STA2 operates in the 5 GHz band and establishes a link with AP2.

[0079] Due to factors such as mobility, the non-AP MLD moves out of the coverage area of ​​the current AP MLD, AP MLD1, and enters the coverage area of ​​the target AP MLD (AP MLD2). During handover or roaming, the non-AP MLD establishes transmission links with both the current AP MLD (AP MLD1) and the target AP MLD (AP MLD2). Specifically, as shown in Figure 2, during handover or roaming, STA2 in the non-AP MLD can disconnect its link with AP2 in the current AP MLD and establish a link with AP1 in the target AP MLD. As previously explained, the two STAs in the non-AP MLD can operate in the 2.4 GHz or 5 GHz frequency band. In the example in Figure 2, STA2 operates in the 2.4 GHz frequency band and establishes a link with AP1 in the target STA MLD.

[0080] At some point in time, the non-AP MLD can completely switch from the current AP MLD to the target AP MLD. In the example in Figure 2, STA1 in the non-AP MLD disconnects from the current AP MLD and establishes a link with an AP in the target AP MLD. In the example in Figure 2, STA1 disconnects from the current AP MLD, operates in the 5 GHz frequency band, and establishes a link with AP2 in the target AP MLD.

[0081] As shown in Figure 2, after the handover or roaming of the non-AP MLD is completed, the non-AP MLD accesses the target AP MLD. Specifically, STA1 of the non-AP MLD establishes a link with AP2 of the target AP MLD, and STA2 establishes a link with AP1 of the target AP MLD.

[0082] In one possible implementation, the communication system shown in Figure 2 may also include other devices such as non-AP MLDs and / or AP MLDs, or other devices, without limitation. For example, the communication system may also include a distributed system (DS). In one implementation, the DS may interconnect multiple basic service sets (BSSs) and integrate a local area network (LAN) to form an extended service set (ESS). In other words, the DS may construct an ESS that includes multiple interconnected BSSs, or may be described as including multiple interconnected BSSs in the DS. A BSS is a basic component of a local area network (LAN) in 802.11. A BSS consists of STAs that form a certain connection within a certain coverage area. For example, an AP MLD may include multiple AP entities, each of which corresponds to a BSS. Each AP entity's corresponding BSS may include at least one STA, and these multiple STAs are associated with the AP entity corresponding to the BSS. Before switching or roaming: In downlink data transmission, the DS can forward downlink data to the current AP MLD, and the current AP MLD sends the downlink data to the non-AP MLD. In uplink data transmission, the non-AP MLD can send uplink data to the current AP MLD, and the current AP MLD then delivers the uplink data to the DS. After switching or roaming: In downlink data transmission, the DS can forward downlink data to the target AP MLD, and the target AP MLD then sends the downlink data to the non-AP MLD. In uplink data transmission, the non-AP MLD can send uplink data to the target AP MLD, and the target AP MLD delivers the uplink data to the DS. During the switching or roaming process, transmission links are established between the non-AP MLD and the current AP MLD and the target AP MLD. The processes of uplink data transmission and downlink data transmission can be found in the following description. In a possible implementation, the application scenario shown in Figure 2 is only a schematic illustration and does not limit the embodiments of the present application.

[0083] It should be noted that in the following description, in downlink and uplink data transmission, a first transmission link exists between the non-AP MLD and the current AP MLD, and a second transmission link exists between the non-AP MLD and the target AP MLD. Before roaming or handover of the non-AP MLD, a first transmission link is established between the non-AP MLD and the current AP MLD. During roaming or handover, a second transmission link can be established between the non-AP MLD and the target AP MLD. The process of establishing the second transmission link is described below. It should be noted that in this embodiment of the present application, handover or roaming of the non-AP MLD can also be referred to as BSS transfer of the non-AP MLD. The current AP MLD can be referred to as the AP MLD of the non-AP MLD before BSS transfer, and the target AP MLD can be referred to as the AP MLD of the non-AP MLD after BSS transfer, etc. The key negotiated between the current AP MLD and the non-AP MLD is referred to as the first key. The key negotiated between the target AP MLD and the non-AP MLD is referred to as the second key. In one implementation, the first key or the second key may be a pairwise transient key (PTK), etc., without limitation.

[0084]

Downlink Data Transmission

[0085] In one design, during downlink data transmission, the current AP MLD receives third downlink data sent by the DS. The higher MAC layer of the current AP MLD processes the third downlink data to obtain first downlink data, and sends the first downlink data to the target AP MLD. The higher MAC layer processing does not include encrypting the third downlink data using the first key. A schematic description of the higher MAC layer processing is provided below. The target AP MLD encrypts the first downlink data using the second key to obtain second downlink data, and then sends the second downlink data to the non-AP MLD. In response, the non-AP MLD decrypts the second downlink data using the second key.

[0086] As shown in FIG3 , a process is provided, which is applicable to downlink data transmission and includes:

[0087] Step 300: The current AP MLD receives the third downlink data sent by the DS.

[0088] In this embodiment of the present application, the DS may store a mapping relationship between the non-AP MLD and the current AP MLD, and a data path exists between the DS and the current AP MLD. When the DS receives the third downlink data, the destination address of the third downlink data may be the address of the non-AP MLD. Based on the stored mapping relationship between the non-AP MLD and the current AP MLD, the DS may determine that the non-AP MLD is associated with the current AP MLD. Therefore, the DS forwards the third downlink data to the current AP MLD. Alternatively, the third downlink data is downlink data to be sent by the current AP MLD. Therefore, step 300 is one implementation and is not required.

[0089] Step 301: The current AP MLD performs high MAC layer processing on the third downlink data to obtain first downlink data. The high MAC layer processing does not include encrypting the third downlink data.

[0090] In one design, as shown in FIG4 , the current AP MLD may assign a sequence number (SN assignment) and a packet sequence number PN (PN assignment) to the third downlink data, and refer to the third downlink data to which the SN and PN are assigned as first downlink data, where the first downlink data includes the assigned SN and PN, etc. In one implementation, the high MAC processing includes at least one of the following: assigning an SN, assigning a PN, or encryption. In one description, the current AP MLD may perform high MAC layer processing on the third downlink data except for encryption, and refer to the processed downlink data as first downlink data. Subsequently, the target AP MLD performs high MAC encryption processing on the downlink data. Specifically, during the encryption process, the target AP MLD may use the second key to encrypt the downlink data.

[0091] Step 302: The current AP MLD sends first downlink data to the target AP MLD.

[0092] In one design, step 302 can be described as: the current AP MLD transparently transmits the first downlink data to the target AP MLD. For example, data transmission between the current AP MLD and the target AP MLD needs to be forwarded by the DS. For example, the current AP MLD sends the first downlink data to the DS, and the DS transparently transmits the first downlink data to the target AP MLD.

[0093] Step 303: The target AP MLD encrypts the first downlink data using the second key to obtain second downlink data.

[0094] In one design, step 303 can be described as follows: the target AP MLD may perform high MAC layer encryption processing on the first downlink data. During the encryption process, the target AP MLD encrypts the first downlink data using the second key. In one implementation, the target AP MLD may also perform low MAC layer and physical layer processing on the first downlink data. In one design, the downlink data that has undergone encryption, low MAC layer, and physical layer processing is referred to as second downlink data. In step 304, the target AP MLD may send the second downlink data to the non-AP MLD.

[0095] Step 304: The target AP MLD sends the second downlink data to the non-AP MLD.

[0096] For example, a second transmission link may be established between the target AP MLD and the non-AP MLD, and the target AP MLD may send the second downlink data to the non-AP MLD via the second transmission link. The non-AP MLD receives the second downlink data from the target AP MLD.

[0097] For example, as shown in Figure 4, for the transmitter of downlink data: the current AP MLD can receive the third downlink data forwarded by the DS, and the current AP MLD can perform processing such as allocating SNs and PNs on the third downlink data to obtain the first downlink data. The current AP MLD sends the first downlink data to the target AP MLD, which performs encryption, low MAC layer and physical layer processing on the first downlink data to obtain the second downlink data. In one implementation, the processing process of the high MAC layer includes: allocating SNs, allocating PNs, and encryption. In an embodiment of the present application, the current AP MLD performs operations such as allocating SNs and allocating PNs on the downlink data, and the target AP MLD encrypts the downlink data. In one description, it can be considered that the processing functions of the high MAC layer are split. During the processing of downlink data, the current AP MLD performs the operations of allocating SNs and allocating PNs, and the target AP MLD performs the encryption operation.

[0098] As shown in Figure 4 , in one implementation, encryption at the upper MAC layer may be referred to as MPDU encryption. Processing at the lower MAC layer includes, among other things, creating a cyclic redundancy check (CRC) in the MPDU header and / or A-MPDU aggregation. The interface between the lower MAC layer and the physical layer in the current AP MLD or target AP MLD may be referred to as a physical layer service access point (SAP). The current AP MLD or target AP MLD may transmit data processed by the lower MAC layer to the physical layer via the physical layer SAP. The example in Figure 4 does not specifically describe the physical layer processing.

[0099] Step 305: The non-AP MLD decrypts the second downlink data using the second key.

[0100] In the scenario of the embodiment of the present application, the non-AP MLD includes a first transmission link and a second transmission link. The first transmission link is used for data transmission with the current AP MLD, and the second transmission link is used for data transmission with the target AP MLD. The first transmission link and the second transmission link each have an independent physical layer and lower MAC layer, and the two transmission links share a higher MAC layer. Specifically, upon receiving second downlink data from the target AP MLD, the non-AP MLD processes the second downlink data using the physical layer and lower MAC layer corresponding to the non-AP MLD (for example, using the physical layer and lower MAC layer corresponding to the target AP MLD in the non-AP MLD) and submits the processed data to the shared higher MAC layer. During the processing at the higher MAC layer, the non-AP MLD may decrypt the second downlink data using the second key. Furthermore, in the embodiment of the present application, the non-AP MLD may also receive downlink data sent by the current AP MLD. This downlink data may be referred to as fourth downlink data. For example, in one implementation, upon receiving downlink data from the non-AP MLD, the DS sends the downlink data to the current AP MLD based on the mapping between the non-AP MLD and the current AP MLD. The current AP MLD sends a portion of downlink data to the target AP MLD, which then sends the downlink data to the non-AP MLD. This process is the data processing process in the flow of Figure 3. In the flow of Figure 3, the downlink data sent from the target AP MLD to the non-AP MLD is referred to as the second downlink data. Alternatively, the current AP MLD can directly send downlink data to the non-AP MLD. This downlink data is referred to as the fourth downlink data. The processing of the downlink data by the current AP MLD may include assigning a SN, assigning a PN, and encrypting the downlink data using the first key. Upon receiving the fourth downlink data, the non-AP MLD may decrypt the fourth downlink data using the first key.

[0101] For example, regarding the receiving end processing flow for downlink data, as shown in Figure 4, the non-AP MLD includes two protocol stacks: the physical layer and lower MAC layer protocol stack corresponding to the current AP MLD, and the physical layer and lower MAC layer protocol stack corresponding to the target AP MLD. The current AP MLD and the target AP MLD share the upper MAC layer protocol stack. Upon receiving the second downlink data from the target AP MLD, the non-AP MLD processes the second downlink data using the physical layer and lower MAC layer corresponding to the target AP MLD, and delivers the processed second downlink data to the shared upper MAC layer. Upon receiving the fourth downlink data from the current AP MLD, the non-AP MLD processes the fourth downlink data using the physical layer and lower MAC layer corresponding to the current AP MLD, and delivers the processed fourth downlink data to the shared upper MAC layer. The non-AP MLD performs upper MAC layer processing on the second and fourth downlink data. It should be noted that during the upper MAC layer processing, the non-AP MLD decrypts the second downlink data using the first key and the fourth downlink data using the second key.

[0102] In one implementation, for the downlink data receiver, as shown in FIG4 , the low MAC layer processing of the non-AP MLD includes, but is not limited to, at least one of the following: A-MPDU de-aggregation, MPDU header CRC validation, address 1 address filter, or block ack scoring. The high MAC layer processing of the non-AP MLD includes, but is not limited to, at least one of the following: block ack scoring, duplicate detection per SN, MPDU decryption, block ack buffering and reordering per SN, or replay detection per PN. It should be noted that the high MAC layer in FIG4 includes two MPDU decryptions: MPDU decryption corresponding to the current AP MLD (decrypted using a first key) and MPDU decryption corresponding to the target AP MLD (decrypted using a second key).

[0103] It should be noted that in this embodiment of the present application, the non-AP MLD has two transmission links: a first transmission link connected to the current AP MLD and a second transmission link connected to the target AP MLD. Before handover, or before roaming ends, the DS stores a mapping between the non-AP MLD and the current AP MLD. During downlink transmission, when the DS receives downlink data destined for the non-AP MLD, it sends the downlink data to the current AP MLD based on the mapping between the non-AP MLD and the current AP MLD. Specific processing for the current AP MLD includes, but is not limited to, the following: 1. The current AP MLD sends all downlink data to the non-AP MLD via the first transmission link. 2. The current AP MLD sends a portion of the downlink data to the non-AP MLD via the first transmission link. The remaining portion of the downlink data is transparently transmitted to the target AP MLD via the DS. The target AP MLD sends the remaining portion of the downlink data to the non-AP MLD via the second transmission link. 3. The current AP MLD transparently transmits all downlink data to the target AP MLD via the DS. The target AP MLD sends all downlink data to the non-AP MLD via the second transmission link. The process in Figure 3 focuses on the following: upon receiving downlink data from the DS, the current AP MLD transparently transmits the downlink data to the target AP MLD via the DS. The target AP MLD then sends the downlink data to the non-AP MLD. In one possible implementation, in the process in Figure 3, the current AP MLD may transparently transmit all downlink data received from the DS to the target AP MLD via the DS. Alternatively, in the process in Figure 3, the current AP MLD may send a portion of the downlink data received from the DS to the non-AP MLD via the first transmission link. The current AP MLD may transparently transmit another portion of the downlink data received from the DS to the target AP MLD via the DS. The target AP MLD may send the other portion of the downlink data to the non-AP MLD via the second transmission link. This splitting of the downlink data into two portions and sending them to the non-AP MLD via different transmission links can improve downlink data transmission speed. In another scenario, the current AP MLD may even replicate the downlink data received from the DS. One copy is transmitted to the non-AP MLD via the first transmission link. The other copy is transparently transmitted to the target AP MLD via the DS. The target AP MLD then sends the downlink data to the non-AP MLD via the second transmission link, thereby improving downlink data transmission reliability. The current AP MLD can even send all or part of its pending downlink data to the target AP MLD, which then sends the received downlink data to the non-AP MLD.In the embodiment of the present application, the source of the downlink data of the current AP MLD is not limited. The focus is on: when the current AP MLD sends downlink data to the target AP MLD, the current AP MLD and the target AP MLD each process the downlink data.

[0104]

Uplink Data Transmission

[0105] In one design, during uplink data transmission, the non-AP MLD establishes two transmission links: a first transmission link with the current AP MLD and a second transmission link with the target AP MLD. Before switching, or before the end of roaming, the DS stores the mapping relationship between the current AP MLD and the non-AP MLD. In order for the DS to correctly process uplink data, the non-AP needs to deliver the uplink data to the current AP MLD, which then delivers the uplink data to the DS. The non-AP MLD delivers the uplink data to the current AP MLD in the following ways, including but not limited to:

[0106] 1. The non-AP MLD delivers the uplink data to the current AP MLD through the first transmission link.

[0107] 2. The non-AP MLD forwards a portion of the uplink data to the current AP MLD. The non-AP MLD forwards the remaining portion of the uplink data to the target AP MLD. The target AP MLD transparently forwards the remaining portion of the uplink data to the current AP MLD via the DS. Splitting the uplink data into two parts and transmitting them to the current AP MLD over different links improves the uplink data transmission rate.

[0108] 3. The non-AP MLD passes all uplink data to the target AP MLD. The target AP MLD transparently passes all uplink data to the current AP MLD via the DS.

[0109] 4. The non-AP MLD can replicate uplink data into two copies. One copy is sent directly to the current AP MLD over the first transmission link. The other copy is sent to the target AP MLD over the second transmission link. The target AP MLD transparently transmits the uplink data to the current AP MLD using the DS. Transmitting the same uplink data over two transmission links improves uplink data transmission reliability.

[0110] In the above-mentioned methods 2, 3, and 4, the following process is involved: the non-AP MLD sends uplink data to the target AP MLD, and the target AP MLD transparently transmits the uplink data to the current AP MLD via the DS. In one possible implementation, the above-mentioned methods 1 to 4 are merely illustrative and do not limit the uplink data transmission scenarios in this application.

[0111] In the uplink data transmission process provided in the embodiments of the present application, when a non-AP MLD sends uplink data to a target AP MLD, it encrypts the uplink data using a second key negotiated between the non-AP MLD and the target AP MLD. Upon receiving the uplink data, the target AP MLD decrypts the uplink data using the second key and sends the decrypted data to the current AP MLD. The current AP MLD then delivers the complete uplink data to the DS in sequence. As shown in FIG5 , a process is provided that can be applied to uplink data transmission, including:

[0112] Step 500: The non-AP MLD encrypts the uplink data to be transmitted using the second key to determine the first uplink data.

[0113] The non-AP MLD has two protocol stacks: the protocol stack corresponding to the current AP MLD and the protocol stack corresponding to the target AP MLD. The current AP MLD and the target AP MLD share the assigned SN and assigned PN. The current AP MLD and the target AP MLD each have exclusive access to encryption, the lower MAC layer, and the physical layer. In one design, the higher MAC layer includes the assigned SN, assigned PN, and encryption. In the current design, the protocol stacks of the target AP MLD and the current AP MLD corresponding to the non-AP MLD share the higher MAC layer. However, in this embodiment, the protocol stacks of the target AP MLD and the current AP MLD each have independent encryption. For example, as shown in Figure 6, the non-AP sequentially performs shared processing such as the assigned SN and assigned PN on the data to be transmitted. The non-AP MLD then performs encryption processing corresponding to the target AP MLD on the data to be transmitted. During the encryption process, the downlink data to be transmitted is encrypted using the second key. In the example of Figure 6, this encryption is called MPDU encryption. The data to be transmitted then undergoes lower MAC layer and physical layer processing to obtain the first data. In the example of Figure 6, the lower MAC layer processing includes creating a CRC in the MPDU header (MPDU header CRC creation) and / or A-MPDU aggregation. In Figure 6, the lower MAC layer of the target AP MLD passes the uplink data to the target AP MLD's physical layer via the physical layer SAP, which then performs physical layer processing on the uplink data. After physical layer processing, the uplink data is sent to the target AP MLD via a second transmission link.

[0114] Step 501: The non-AP MLD sends first uplink data to the target AP MLD.

[0115] Step 502: The target AP MLD decrypts the first uplink data using the second key to obtain second uplink data.

[0116] In one design, upon receiving the first uplink data, the target AP MLD may perform physical layer and lower MAC layer processing on the first uplink data. The physical layer processing is not indicated in FIG6 . In the example of FIG6 , the lower MAC layer processing includes, but is not limited to, at least one of the following: A-MPDU de-aggregation, CRC validation in the MPDU header, address 1 filter, or block acknowledgment scoring. The target AP MLD decrypts the first uplink data using the second key. In the example of FIG6 , decryption is referred to as MPDU decryption.

[0117] Step 503: The target AP MLD sends the second uplink data to the current AP MLD.

[0118] Step 504: The current AP MLD performs high MAC layer processing on the second uplink data to obtain third uplink data. The high MAC layer processing does not include decrypting the third uplink data.

[0119] In one design, upper MAC layer processing includes at least one of the following: block ack scoring, duplicate detection per SN, MPDU decryption, block ack buffering and reordering per SN, or replay detection per PN.

[0120] In this embodiment of the present application, the block acknowledgment scoreboard and MPDU decryption at the higher MAC layer can be implemented on the target AP MLD side. In other words, one implementation of step 502 is as follows: the target AP MLD performs higher MAC layer processing on the first uplink data, where the higher MAC layer processing includes the block acknowledgment scoreboard and MPDU decryption.

[0121] The high-MAC layer processing, such as per-SN duplicate detection, block acknowledgement buffering and SN reordering, or per-PN replay detection, can be implemented on the target AP MLD side. Specifically, one implementation of step 504 includes the current AP MLD performing high-MAC layer processing on the second uplink data, including per-SN duplicate detection, block acknowledgement buffering and SN reordering, or per-PN replay detection.

[0122] It should be noted that in the embodiment of the present application, during normal high-MAC layer processing, per-SN duplicate detection is implemented before MPDU decryption. In the embodiment of the present application, MPDU decryption is implemented before per-SN duplicate detection. The MPDU decryption function is implemented in the target AP MLD, while per-SN duplicate detection is implemented in the current AP MLD. This design is primarily based on the following considerations: In addition to receiving uplink data packets sent by the non-AP MLD through the target AP MLD, the current AP MLD can also receive uplink data packets directly from the non-AP MLD. When performing SN duplicate detection, the current AP MLD needs to obtain all uplink data before performing SN duplicate detection. For example, SN duplicate detection may also be referred to as duplicate detection.

[0123] Step 505: The current AP MLD sends the third uplink data to the DS.

[0124] In one design, the current AP MLD may send the third uplink data to the DS, which may then process or apply the third uplink data. Alternatively, the third uplink data may be sent to the current AP MLD, which may then directly process or apply the third uplink data. In this case, the third uplink data does not need to be reported to the DS. In this case, step 505 does not need to be performed. Therefore, step 505 is optional.

[0125] In one possible implementation, in the process of Figure 5 , in addition to using steps 500 to 504 to send uplink data to the current AP MLD, the non-AP MLD can also directly send uplink data to the current AP MLD. In this process, the non-AP MLD encrypts the uplink data using the first key. Accordingly, upon receiving the uplink data, the current AP MLD decrypts the uplink data using the first key. For example, in one description, the non-AP MLD encrypts the uplink data to be transmitted using the first key to obtain fourth uplink data. For example, in one implementation, as shown in Figure 6 , the non-AP MLD can process the uplink data to be transmitted using the shared assigned SN and assigned PN. Subsequently, the non-AP MLD processes the uplink data to be transmitted using the current AP MLD's independent MPDU encryption, lower MAC layer, and physical layer functions to obtain fourth uplink data. The uplink data to be transmitted is encrypted using the first key during MPDU encryption. Accordingly, when the current AP MLD receives the fourth uplink data, it may process the fourth uplink data sequentially through the physical layer, the lower MAC layer, and the upper MAC layer. Regarding the division of the lower MAC layer and the upper MAC layer on the current AP MLD side in FIG6 , please refer to the description of the target AP MLD side in the previous text.

[0126] An embodiment of the present application also provides a process for establishing a second transmission link between a non-AP MLD and a target AP MLD. For example, a first transmission link is established between the non-AP MLD and the current AP MLD. In one implementation, the first transmission link can be considered a data connection between the non-AP MLD and the current AP MLD. A data path exists between the current AP MLD and the DS, and the DS stores a mapping relationship between the non-AP MLD and the current AP MLD. The current AP MLD discovers through measurement that the link quality of the first transmission link between the non-AP MLD and the current AP MLD has deteriorated, for example, because the link quality of the first transmission link is less than or equal to a threshold. In this case, the current AP MLD may instruct the non-AP MLD to perform beacon measurement. Based on the beacon measurement results reported by the non-AP MLD, the current AP MLD recommends an AP MLD to the non-AP MLD for switching. The non-AP MLD selects an AP MLD from the recommended AP MLDs as the target AP MLD. In one implementation, the non-AP MLD reports its selected target AP MLD to the current AP MLD. In one implementation, the current AP MLD may send a seventh request to the non-AP MLD, where the seventh request also includes second indication information, where the second indication information instructs the non-AP MLD to retain the BA session information and / or context information of the non-AP MLD and to cache data not sent by the non-AP MLD. Upon receiving the second indication information, the non-AP MLD may retain the BA session information and / or context information during a subsequent tentative connection process. In one implementation, the non-AP MLD may send a seventh response to the current AP MLD, where the seventh response is a response to the seventh request. In one implementation, the seventh request may be a BSS transition management (BTM) request frame, and the seventh response may be a BTM response frame.

[0127] Tentative Association

[0128] The non-AP MLD can establish a tentative association with the target AP MLD through an affiliated STA. During the tentative association process, the non-AP MLD can establish a second transmission link with the target AP MLD. Furthermore, the transmission capability parameters of the two parties (for example, the transmission bandwidth and maximum number of streams between the two parties), the key information of the two parties (such as PTK, group temporal key (GTK), integrity group temporal key (IGTK) and beacon integrity group temporal key (BIGTK)), and the resource allocation information of the two parties (such as BA session, restricted target wakeup time (r-TWT) establishment, etc.) can also be negotiated.

[0129] In one design, the non-AP MLD may send a first request to the target AP MLD, requesting establishment of a second transmission link between the non-AP MLD and the target AP MLD. The target AP MLD may send a first response to the non-AP MLD, where the first response is a response to the first request. For example, the non-AP MLD may send a first request to the target AP MLD, requesting establishment of the second transmission link. Upon receiving the first request, the target AP MLD may send a first response to the non-AP MLD, where the first response indicates that the target AP MLD agrees to establish the second transmission link and indicates at least one of transmission capability parameters, key information, or resource allocation information between the non-AP MLD and the target AP MLD. The target AP MLD may send a first response to the non-AP MLD, where the first response may include at least one of the transmission capability parameters, key information, or resource allocation information between the non-AP MLD and the target AP MLD, as agreed between the non-AP MLD and the target AP MLD.

[0130] In one implementation, the first request may be a reassociation request frame, which is used by the non-AP MLD to request a tentative association with the target AP MLD. The first response may be a reassociation response frame, which is used to establish a tentative association between the non-AP MLD and the target AP MLD. During the tentative association process, the non-AP MLD and the target AP MLD may establish a second transmission link and negotiate various parameters.

[0131] It should be noted that during the tentative association process: the target AP MLD does not refresh the mapping relationship between the non-AP MLD and the current AP MLD stored on the DS side. Before sending the first request (such as the reassociation request frame mentioned above), the non-AP MLD does not delete the first key negotiated with the current AP MLD, does not clear the send buffer and the receive buffer, etc. The non-AP MLD still maintains the first transmission link with the current AP MLD. Through the first transmission link, the non-AP MLD and the current AP MLD can still transmit uplink data and / or downlink data.

[0132] In one implementation, the first request may include instruction information for enabling dual-link transmission for the non-AP MLD. The dual-link includes a first transmission link between the non-AP MLD and the current AP MLD, and a second transmission link between the non-AP MLD and the target AP MLD. After the target AP MLD receives the instruction information and successfully establishes the second transmission link, it initiates dual-link transmission negotiation with the current AP MLD to enable dual-link transmission.

[0133]

Dual-link transmission

[0134] During dual-link roaming, data needs to be transmitted between the current AP MLD and the target AP MLD. Therefore, upon receiving an instruction from the non-AP MLD to enable dual-link transmission via a first request, the target AP MLD can send a second request to the current AP MLD, requesting the non-AP MLD to enable dual-link transmission. During dual-link downlink transmission, the current AP MLD can send downlink data from the non-AP MLD to the target AP MLD. The target AP MLD encrypts the downlink data using the second key and sends the encrypted data to the non-AP MLD. During dual-link uplink transmission, the target AP MLD can receive uplink data from the non-AP MLD, decrypt the uplink data using the second key, and send the decrypted uplink data to the current AP MLD. The current AP MLD then sends the uplink data to the DS. For detailed procedures, see [Uplink Data Transmission] and [Downlink Data Transmission] above. In one implementation, the current AP MLD can send a second response to the target AP MLD, which is a response to the second request. For example, the second response may include indication information of whether the current AP MLD agrees to enable dual-link transmission.

[0135] In one design, dual-link transmission during roaming may be described as roaming transmission based on a dual active protocol stack (DAPS). DAPS-based roaming transmission may refer to a non-AP MLD capable of simultaneous multi-link transmission and reception, which can simultaneously perform uplink and / or downlink transmission with a current AP MLD and a target AP MLD during roaming. Exemplarily, the second request may be a DAPS enable request, and the second response may be a DAPS enable response.

[0136] In a possible implementation, data transmission between the target AP MLD and the current AP MLD can be forwarded by the DS. In the embodiment of the present application, there is no restriction on whether the DS performs relevant processing and / or operations on the data during the process of forwarding the data. If the DS does not perform any relevant operations or processing on the data, it can be called transparent transmission of the DS. In one design: the current AP MLD can encapsulate the data in a special frame or message and transparently transmit it to the target AP MLD through the DS. In a possible implementation, "transparent transmission" in the relevant description of the embodiment of the present application can also be replaced with relevant descriptions such as sending or forwarding. If the DS performs corresponding operations and / or processing on the received data during the process of data forwarding, it is also within the protection scope of the embodiment of the present application. Alternatively, data can be directly transmitted between the target AP MLD and the current AP MLD without restriction.

[0137]

Data path switching

[0138] The non-AP MLD can trigger a data path switch, for example, switching the non-AP MLD's transmission path from the current AP MLD to the target AP MLD. In one possible implementation, after the data path switch, the non-AP MLD uses the second key negotiated with the target AP MLD to encrypt and decrypt uplink and / or downlink data. In one implementation, the second key can be a PTK.

[0139] In one implementation, in an embodiment of the present application, the conditions for triggering a data path switch by a non-AP MLD are not restricted. For example, a non-AP MLD may trigger a data path switch when a first condition is met. This first condition includes, but is not limited to, the link quality of the target AP MLD's optimal link being higher than the link quality of the current AP MLD's optimal link.

[0140] It should be noted that during roaming, the non-AP MLD uses the first transmission link and the second transmission link to simultaneously transmit data. At the end of roaming, the non-AP MLD can perform data path switching. In one description, the non-AP MLD will disconnect the first transmission link during the data path switching process and fully utilize the second transmission link for data transmission. Alternatively, in another description, through the example of Figure 2 above, it can be seen that: in dual-link transmission, the non-AP MLD uses different STA entities to establish transmission links with the current AP MLD and the target AP MLD respectively. For example, as described in Figure 2, during roaming: STA1 of the non-AP STA establishes a first transmission link with the current AP MLD, and STA2 of the non-AP MLD establishes a second transmission link with the target AP MLD. During the data path switching process, the essence is: STA1 disconnects the first transmission link with the current AP MLD, and establishes another transmission link between STA1 and the target AP MLD.

[0141] In one design, during the process of a non-AP MLD triggering a path switch, the non-AP MLD may send a third request to the target AP MLD, requesting triggering a path switch for the non-AP MLD (e.g., a data path switch). In one implementation, the target AP MLD may send a third response to the non-AP MLD, which may be a response to the third request. For example, the third response may include information indicating whether the path switch is approved. If the target AP MLD approves the path switch for the non-AP MLD, the target AP MLD may send a fourth request to the DS, requesting the DS to update the stored mapping between the non-AP MLD and the current AP MLD to the mapping between the non-AP MLD and the target AP MLD. In one implementation, the DS may send a fourth response to the target AP MLD, which may be a response to the fourth request. In one implementation, the fourth response may include information indicating whether the DS approves the updated mapping. Alternatively, the target AP MLD may send an uplink data packet to the DS via a MAC SAP. The DS automatically updates its stored mapping relationship based on the information that the uplink data packet can carry non-AP MLD.

[0142] In one implementation, the third request is a STA-to-AP mapping request frame, and the third response is a STA-to-AP mapping response frame. The fourth request is a DS-STA-notify request for updating or adding a new DS-STA, and the fourth response may be a DS-STA-notify response.

[0143] Furthermore, after the target AP MLD receives the third request and before the target AP MLD sends the fourth request to the DS, it also includes: the target AP MLD sends a context transfer request (context transfer request) to the current AP MLD; the target AP MLD receives a context transfer response (context transfer response) sent by the current AP MLD, and the context transfer response includes the context information of the non-AP MLD.

[0144] In one implementation, the context transfer response further includes at least one of the following: a block determination protocol for a traffic identifier (TID), a window start position for a send buffer for the TID, a window size for the send buffer for the TID, a window start position for an uplink receiving end scoreboard, a window size for the uplink receiving end scoreboard, a window start position for a receive reordering buffer, a window size for the receive reordering buffer, a maximum packet sequence number (PN) value currently received, or an uplink replay counter.

[0145] In one design, the target AP MLD receives a third request from the non-AP MLD, requesting a path switch. The target AP MLD sends a context transfer request to the current AP MLD. The target AP MLD receives a context transfer response from the current AP MLD. The target AP MLD waits for a period of time before sending a fourth request to the DS to refresh the mapping relationship stored on the DS. This ensures that uplink delivery is not out of order. This is because, before refreshing the mapping relationship stored on the DS, all uplink data is delivered to the DS via the current AP MLD. At the moment when the non-AP MLD's transmission path switches from the first transmission path to the second transmission path, that is, when the target AP MLD receives the context transfer response from the current AP MLD, the uplink data delivered to the DS by the current AP MLD may not have been fully processed. Therefore, in this embodiment of the present application, after receiving the context transfer response from the current AP MLD, the target AP MLD waits for a period of time. At this time, when the DS has finished processing the uplink data of the current AP MLD, it sends the fourth request to the DS to refresh the mapping relationship. Alternatively, before sending a context transfer response, the current AP MLD must ensure that all of its uplink data has been successfully delivered to the DS. For example, in one implementation, after sending a sixth request to the DS to delete the mapping between the non-AP MLD and the current AP MLD, the current AP MLD then sends a context transfer response to the target AP MLD. For details about the sixth request, see the following description.

[0146] In one implementation, when the non-AP MLD determines to trigger a path switch, the non-AP MLD may further send a fifth request to the current AP MLD. The current AP MLD receives the fifth request sent by the non-AP MLD, wherein the fifth request is used to request severing the association between the non-AP MLD and the current AP MLD. Upon receiving the fifth request, the current AP MLD may disconnect the first transmission link with the non-AP MLD. In one implementation, the fifth request includes first indication information, wherein the first indication information instructs the current AP MLD to retain the BA information and / or context information of the non-AP MLD and to cache data not sent by the non-AP MLD. After receiving the fifth request, the current AP MLD sends a sixth request to the DS, wherein the sixth request is used to request deletion of the mapping relationship between the non-AP MLD and the current AP MLD stored in the DS. Upon receiving the sixth request, the DS may delete the mapping relationship between the non-AP MLD and the current AP MLD stored in the DS. Alternatively, in one implementation, the current AP MLD may proactively trigger the non-AP MLD to perform a BSS transfer. For example, the current AP MLD proactively triggers the non-AP MLD to switch to the target AP MLD. In this case, the current AP MLD may send a fifth request to the non-AP MLD, which is used to sever the association between the current AP MLD and the non-AP MLD.

[0147] In one implementation, the fifth request may be a disassociation frame, and the sixth request may be a DS-STA-NOTIFY.request for deletion.

[0148] In one design, the non-AP MLD may not send the fifth request to the current AP MLD. In this case, after the current AP MLD receives the context transfer request from the target AP MLD and does not receive the fifth request from the non-AP MLD, it may stop delivering uplink data to the DS and send a sixth request to the DS to delete the mapping between the non-AP MLD and the current AP MLD stored in the DS. The current AP MLD then sends a context transfer response to the target AP MLD.

[0149] It should be noted that in the preceding description, the target AP MLD may send a fourth request to the DS, requesting the DS to update the stored mapping relationship between the non-AP MLD and the current AP MLD to the mapping relationship between the non-AP MLD and the target AP MLD. Furthermore, in the preceding description, the current AP MLD may send a sixth request to the DS, requesting the DS to delete the stored mapping relationship between the non-AP MLD and the current AP MLD. In one design, the DS first receives the sixth request and deletes the stored mapping relationship between the non-AP MLD and the current AP MLD. Thereafter, the DS receives the fourth request, which adds the mapping relationship between the non-AP MLD and the target AP MLD to its storage. In other words, the updating of the mapping relationship in the fourth request can also mean adding the mapping relationship between the non-AP MLD and the target AP MLD. Alternatively, upon receiving the fourth request, the DS directly updates its stored mapping relationship. For example, it replaces the stored mapping relationship between the non-AP MLD and the current AP MLD with the mapping relationship between the non-AP MLD and the target AP MLD. In this case, the current AP MLD may no longer send the sixth request to delete the mapping relationship to the AP MLD.

[0150] On the DS side, after receiving the fourth request from the target AP MLD, the DS can switch the data path. For example, the DS deletes the data path between the non-AP MLD and the current AP MLD and adds the data path between the non-AP MLD and the target AP MLD. After the current AP MLD successfully sends a context transfer response, it can release the context of the non-AP MLD.

[0151] In an embodiment of the present application, the current AP MLD also needs to send downlink data and / or uplink data that meets the following conditions to the target AP MLD. For example, in one design, upon receiving a context transfer request from the target AP MLD, the current AP MLD may send the downlink data and / or uplink data described below to the target AP MLD. The downlink data and / or uplink data described below may be carried in a context transfer response. Alternatively, the current AP MLD may send the uplink data and / or downlink data described below to the target AP MLD before or after the current AP MLD sends the context transfer response to the target AP MLD, without limitation.

[0152] For example, for downlink data transmission, the current AP MLD needs to forward the (unencrypted) downlink data to the target AP MLD and carry an end identifier in the last downlink data. In one implementation, the format of the downlink data can be MSDU or MPDU. For downlink data in MPDU format, the more data field in the MPDU header can be reused. For example, when the MPDU is the last downlink data, the more data field is set to the first value, otherwise the more data field is set to the second value. In one implementation, the first value can be 0 and the second value can be 1. When the target AP MLD receives the downlink data forwarded by the current AP MLD, it encrypts the downlink data using the second key and sends the downlink data to the non-AP MLD.

[0153] For example, for uplink data transmission, the current AP MLD can forward the high MAC layer processed (eg, decrypted MSDU or MPDU) in the uplink receive buffer to the target AP MLD, etc. The target AP MLD sends the received complete continuous uplink data to the DS, etc.

[0154] In one design, during handover, the non-AP MLD first disconnects its old link with the current AP MLD and then establishes a new link with the target AP MLD. Before establishing a new link with the target AP MLD, the non-AP MLD clears its transmit and receive buffers, which can cause packet loss. The receive buffer is used to store discontinuous data received by the non-AP MLD, and the transmit buffer is used to store data that the non-AP MLD has not yet sent or that has been sent but not acknowledged by the receiver. In the solution of an embodiment of the present application, the non-AP MLD first establishes a second transmission link with the target AP MLD. During this period, the non-AP MLD and the current AP MLD do not clear their transmit and receive buffers; they continue to transmit data, thus avoiding packet loss. At some point, the non-AP MLD then disconnects its first transmission link with the current AP MLD and transfers the transmission session or block acknowledgment (BA) session to the target AP MLD. During the handover process, the non-AP MLD uses multi-link capabilities to simultaneously communicate with the current AP MLD and the target AP MLD, reducing the risk of data rate drops during the handover process.

[0155] [Example 1]

[0156] In an embodiment of the present application, a second transmission link is directly established between the non-AP MLD and the target AP. The first request and / or the third request mentioned above are transmitted through the air interface between the non-AP MLD and the target AP MLD. As shown in Figure 7a, a process is provided. It should be noted that before executing the process of Figure 7a: there is a first transmission link between the non-AP MLD and the current AP MLD. For example, there is a data connection between the non-AP MLD and the current AP MLD. There is a data path between the current AP MLD and the DS, and the DS stores the mapping relationship between the non-AP MLD and the current AP MLD. As shown in Figure 7a, the process includes:

[0157] Step 701: The current AP MLD finds that the link quality of the non-AP MLD has deteriorated, and the current AP MLD sends a beacon measurement request to the non-AP MLD.

[0158] Step 702: The non-AP MLD performs beacon measurement and feeds back a beacon measurement report to the current AP MLD.

[0159] Step 703: Based on the beacon measurement report, the current AP MLD recommends that the non-AP MLD switch to a neighboring AP MLD. For example, the current AP MLD sends a BTM request frame to the non-AP MLD. The BTM request frame includes information indicating at least one AP MLD recommended by the current AP MLD. The non-AP MLD selects one of the recommended AP MLDs as the target AP MLD.

[0160] In one implementation, the BTM request frame includes second indication information, which is used to instruct the non-AP MLD to retain the BA information and / or context information of the non-AP MLD and cache the data not sent by the non-AP MLD. Upon receiving the second indication information, the non-AP MLD may enable DAPS-based dual-link roaming.

[0161] In one implementation, before the current AP MLD sends the BTM request frame to the non-AP MLD, the non-AP MLD may further send a BTM inquiry frame to the current AP MLD. After receiving the BTM inquiry frame, the current AP MLD sends a BTM request frame to the current AP MLD.

[0162] Step 704: The non-AP MLD sends a BTM response frame to the current AP MLD. The BTM response frame includes the target AP MLD selected by the non-AP MLD.

[0163] Step 705: The non-AP MLD performs a tentative association with the target AP MLD. During the tentative association process, the following steps may be implemented: establishing a second transmission link between the target AP MLD and the non-AP MLD, such as the bandwidth of the second transmission link and the maximum number of supported flows; establishing a BA session; and negotiating a key, which includes a second key for communication between the two parties.

[0164] In one implementation, a tentative association can be established between the non-AP MLD and the target AP MLD via a reassociation request frame and a reassociation response frame. For details about the reassociation request frame and the reassociation response frame, refer to the description of the first request and the first response above. In one possible implementation, during the tentative association process, the mapping relationship between the non-AP MLD and the AP MLD stored on the DS is not refreshed. In this case, the DS stores the mapping relationship between the non-AP MLD and the current AP MLD. When the DS receives downlink data from the non-AP MLD, it delivers it to the current AP MLD.

[0165] Step 706: After the non-AP MLD completes the tentative association with the target AP MLD, the target AP MLD and the current AP MLD may enable DAPS roaming through the interaction of DAPS enablement request and DAPS enablement response.

[0166] For details about the DAPS enable request and DAPS usage response, please refer to the description of the second request and the second response in the previous text.

[0167] Step 707: The non-AP MLD triggers a path switch. The non-AP MLD sends a STA-AP mapping request frame to the target AP MLD. This STA-AP request frame can be used to request the target AP MLD to perform a path switch. For details about the STA-AP mapping request frame, see the third request above.

[0168] Step 708: The target AP MLD sends a context transfer request to the current AP MLD.

[0169] Step 709: The current AP MLD sends a context transfer response to the target AP MLD. For details about the content carried in the context transfer response, please refer to the above description.

[0170] Step 7010: The target AP MLD sends a DS-STA-Notify Request to the DS.

[0171] Upon receiving the DS-STA-Notify Request, the DS may update its stored mapping from the non-AP MLD to the current AP MLD to the non-AP MLD to the target AP MLD. The DS disconnects the data path with the current AP MLD and establishes a data path with the target AP MLD. For details about the DS-STA-Notify Request, see the fourth request above.

[0172] Step 7011: The current AP MLD deletes the context of the non-AP MLD.

[0173] After step 7011, the transmission path of the non-AP MLD is switched from the first transmission path to the second transmission path. The non-AP MLD and the target AP MLD may use the negotiated second key to encrypt and decrypt uplink data and / or downlink data.

[0174] In one implementation, in step 707, when the non-AP MLD determines to trigger a path switch, the process further includes: the non-AP MLD sending a disassociation frame to the current AP MLD. The disassociation frame can refer to the fifth request described above. The current AP MLD may send a DS-STA-Notify request to the DS for deletion. The DS deletes the stored mapping between the non-AP MLD and the current AP MLD.

[0175] In this embodiment of the present application, transmission between the current AP MLD and the target AP MLD occurs transparently via the DS. In this embodiment, transmission between the current AP MLD and the target AP MLD includes, but is not limited to, the aforementioned DAPS enable request, DAPS enable response, context transfer request, or context transfer response. In addition, uplink data and / or downlink data can also be transmitted between the current AP MLD and the target AP MLD. For details, see the descriptions of "Uplink Data Transmission" and "Downlink Data Transmission" above.

[0176] In one design, the following frame format may be used for information and / or data transmitted between the AP MLD and the target AP MLD. As shown in FIG7b , the frame format includes at least one of the following fields:

[0177] Destination MAC address: can carry a 48-bit MAC address.

[0178] Source MAC address: can carry a 48-bit MAC address.

[0179] Length field;

[0180] The logical link control (LLC) field includes: the destination service access point (DSAP) address (this field is fixed to AA), the destination service access point (SSAP) address (this field is fixed to AA), and the control field (fixed to 0x03).

[0181] The subnetwork access protocol (SNAP) field includes an organizationally unique identifier (UII) field and an ether type (Ether Type) field.

[0182] Payload type field: This field can be set to one or more preset values ​​depending on the payload.

[0183] Payload field: For example, the payload field may carry the DAPS enable request, DAPS enable response, context transfer request, context transfer response, or uplink / downlink data that needs to be transparently transmitted. The payload field may carry MPDUs that comply with the tunneling 802.11 protocol.

[0184] It should be noted that when transparently transmitting uplink / downlink data between the current AP MLD and the target AP MLD, the information carried in the payload field can be constructed based on the additional authentication data (AAD) of the cipher-block chaining message authentication code protocol (CCMP), and carries the CCMP header and the encrypted frame body. In one design, as shown in Figure 7c, the payload field includes at least one of the following fields: frame control, address 1, address 2, address 3, sequence control, quality of service (QoS) control, CCMP header, or frame body.

[0185] In one implementation, the payload field may further include at least one of the following fields: a retry field, a power management field, a data field, a high throughput control (HTC) field, or a QoS field other than the TID field. Furthermore, when the payload field carries the above fields, the specific values ​​of the above fields may be set to empty.

[0186] According to the first embodiment, during handover or roaming, the non-AP MLD utilizes its multi-link capability to establish dual links with the current AP MLD and the target AP MLD, enabling simultaneous data transmission using both the current AP MLD and the target AP MLD. This improves the transmission rate and reliability during roaming. Furthermore, because the non-AP MLD does not disconnect the primary transmission link with the current AP MLD and does not clear its transmit and receive buffers during roaming, the probability of packet loss and / or interruption during roaming is reduced.

[0187] [Example 2]

[0188] In this embodiment of the present application, the second transmission link between the non-AP MLD and the target AP is established via the current AP MLD and the DS. The first request and / or third request mentioned above are transmitted via the current AP MLD and the DS. For example, the non-AP MLD may send the first request and / or third request to the current AP MLD, which then transparently transmits the first request and / or third request to the target AP MLD via the DS.

[0189] Another important device type for non-AP MLDs is the enhanced multi-link single radio (EMLSR) non-AP MLD. In one design, an EMLSR non-AP MLD has multiple receive radio chains and can monitor multiple links simultaneously. Upon receiving an initial control frame from an AP MLD, it switches the radio chains of other links in the EMLSR link set to the link corresponding to the received initial control frame, thereby increasing the number of transmit and receive flows. In other words, at any given moment, an EMLSR non-AP MLD can only select one link for data transmission and reception. Compared to a multi-radio non-AP MLD, an eMLSR non-AP MLD has only one fully functional transceiver, while the remaining transceivers are low-cost devices with limited functionality (because they can only receive specific initial control frames). This significantly reduces costs, but performance is significantly lower than that of a multi-radio non-AP MLD. This is because an EMLSR non-AP MLD can only transmit and receive data on a single link. When using the solution in Example 1 to tentatively associate with a target AP MLD, it must jump to the target AP MLD's corresponding channel for the tentative association operation, which interrupts data transmission with the current AP MLD and seriously affects roaming performance. Therefore, Example 2 proposes a solution to further improve the roaming performance of non-AP MLDs, especially for non-AP MLDs with single radio links and EMLSR non-AP MLDs.

[0190] As shown in Figure 8, a process is provided. Before executing the process in Figure 8, a first transmission link is established between the non-AP MLD and the current AP MLD. The first transmission link is also called the data connection between the current AP MLD and the non-AP MLD. A data path exists between the DS and the current AP MLD. The DS stores the mapping relationship between the non-AP MLD and the current AP MLD. As shown in Figure 8, the process includes:

[0191] Step 801: The current AP MLD finds that the link quality of the non-AP MLD has deteriorated, and the current AP MLD sends a beacon measurement request to the non-AP MLD.

[0192] Step 802: The non-AP MLD performs beacon measurement and feeds back a beacon measurement report to the current AP MLD.

[0193] Step 803: Based on the beacon measurement report, the current AP MLD recommends that the non-AP MLD switch to a neighboring AP MLD. For example, the current AP MLD sends a BTM request frame to the non-AP MLD. The BTM request frame includes information indicating at least one AP MLD recommended by the current AP MLD. The non-AP MLD selects one of the recommended AP MLDs as the target AP MLD.

[0194] In one implementation, before the current AP MLD sends the BTM request frame to the non-AP MLD, the non-AP MLD may further send a BTM inquiry frame to the current AP MLD. After receiving the BTM inquiry frame, the current AP MLD sends a BTM request frame to the current AP MLD.

[0195] Step 804: The non-AP MLD sends a BTM response frame to the current AP MLD. The BTM response frame includes the target AP MLD selected by the non-AP MLD.

[0196] Step 805: The non-AP MLD performs a tentative association with the target AP MLD. The tentative association may be a tentative reassociation over the DS.

[0197] To ensure that a non-AP MLD can perform a tentative association with a target AP MLD while maintaining data transmission with the current AP MLD, an Over-the-DS (DS) tentative association mode is defined. This mode allows a non-AP MLD to perform a tentative association with a target AP MLD using the current AP MLD.

[0198] For example, a non-AP may send a first request to the current AP MLD, where the first request is used to request the establishment of a second transmission link between the non-AP MLD and the target AP MLD. After receiving the first request, the current AP MLD transparently transmits the first request to the target AP MLD via the DS. The target AP MLD may establish a second transmission link between the target AP MLD and the non-AP MLD based on the first request. The second transmission link may be an air interface link between the non-AP MLD and the target AP MLD. In one implementation, the target AP MLD may send a first response to the current AP MLD via the DS. The current AP MLD sends the first response to the non-AP MLD. In one implementation, the first request and the first response may be a fast BSS transition (FT) probe request and an FT probe response, respectively.

[0199] In one implementation, when the first request is transmitted through the current AP MLD and DS, the first request does not include operating channel information (OCI), thereby saving signaling overhead of the first request.

[0200] The non-AP MLD sends an eighth request to the current AP MLD. The current AP MLD transparently transmits the eighth request to the target AP MLD via the DS. The eighth request is used to request communication parameters of the target AP MLD. The target AP MLD sends an eighth response to the current AP MLD via the DS. The current AP MLD sends the eighth response to the non-AP MLD. The eighth response includes the second key negotiated between the non-AP MLD and the target AP MLD. In one implementation, the eighth request and the eighth response may be an FT request and an FT response, respectively.

[0201] The non-AP MLD sends a ninth request to the current AP MLD. The current AP MLD transparently transmits the ninth request to the target AP MLD via the DS. The ninth request is used to negotiate link operation parameters, etc., between the non-AP MLD and the target AP MLD. The target AP MLD sends a ninth response to the current AP MLD via the DS. The current AP MLD sends a ninth response to the non-AP MLD. The ninth response includes link operation parameters, etc., between the non-AP MLD and the target AP MLD. In one implementation, the ninth request and the ninth response may be an FT reassociation request and an FT reassociation response, respectively.

[0202] In one design, as shown in FIG9 , the FT action frame transparently transmitted between the non-AP MLD and the target AP MLD through the DS and the current AP MLD (including but not limited to the FT query request, FT query response, FT request, FT response, FT reassociation request, and FT reassociation response described above) includes at least one of the following fields: category, FT action, MAC address of the non-AP MLD, MAC address of the target AP MLD, and frame body.

[0203] The category field is used to indicate the category to which the FT action frame belongs. The FT action field includes the value corresponding to FT. Different FT action frames have different values ​​set in the corresponding FT action field. For example, as shown in Table 1:

[0204] Table 1

[0205] As can be seen, when the FT Action frame in Figure 9 is used as an FT Reassociation Request, the FT Action field is set to a value of 7. When the Action frame in Figure 9 is used as an FT Reassociation Response, the FT Action field is set to a value of 8. The FT Query Request, FT Query Response, FT Request, and FT Response mentioned above can all use the FT Action frame format in Figure 9. The difference is that the FT Action field value in Table 1 is set to the corresponding value.

[0206] The non-AP MLD field includes the MAC layer address of the non-AP MLD. Specifically, it can be the high MAC layer address or the low MAC layer address of the non-AP MLD, without limitation. The MAC address of the target AP MLD includes the MAC layer address of the target AP MLD, which can be the high MAC layer address or the low MAC layer address of the target AP MLD.

[0207] The frame body field is used to carry the frame body corresponding to the FT action frame.

[0208] In one implementation, the FT reassociation request frame, as shown in Table 2, carries at least one of the following information in its frame body.

[0209] Table 2: Information carried in the frame body of the FT reassociation request frame

[0210] In one implementation, as shown in Table 3, the frame body of the FT reassociation response carries at least one of the following information:

[0211] Table 3: Information carried in the frame body of the FT reassociation response frame

[0212] In one embodiment of the present application, when the FT reassociation request and the FT reassociation response are transparently transmitted via the DS, an implementation method is as follows:

[0213] 1. The frame body of the FT reassociation request and / or FT reassociation response does not need to carry the OCI. The OCI is mainly used to verify the channel information, thereby reducing the signaling overhead of the FT reassociation request and / or FT reassociation response.

[0214] 2. After the current AP MLD and the target AP MLD perform a tentative association using the FT reassociation request and the FT reassociation response, the initial state of the second transmission link established between the non-AP MLD and the target AP MLD is the energy-saving mode, and its state is the energy-saving (doze) state.

[0215] 3. The mobility domain element (MDE) in the frame body of the FT reassociation request and / or FT reassociation response carries 1-bit indication information, which is used to indicate whether OS (over-the-DS) based tentative association is supported.

[0216] Step 806: The non-AP MLD triggers a path switch. The non-AP MLD sends a STA-AP mapping request frame to the target AP MLD. This STA-AP request frame can be used to request the target AP MLD to perform a path switch. For details about the STA-AP mapping request frame, see the third request above.

[0217] Unlike the process in FIG. 7a , in the process in FIG. 8 , in step 806, the non-AP MLD sends a STA-AP mapping request frame to the target AP MLD. This includes the non-AP MLD sending a STA-AP mapping request frame to the current AP MLD. The current AP MLD transparently transmits the STA-AP mapping request frame to the target AP MLD via the DS.

[0218] Step 807: The target AP MLD sends a context transfer request to the current AP MLD.

[0219] Step 808: The current AP MLD sends a context transfer response to the target AP MLD. For details about the content carried in the context transfer response, please refer to the above description.

[0220] Step 809: The target AP MLD sends a DS-STA-Notify Request to the DS.

[0221] Upon receiving the DS-STA-Notify Request, the DS may update its stored mapping from the non-AP MLD to the current AP MLD to the non-AP MLD to the target AP MLD. The DS disconnects the data path with the current AP MLD and establishes a data path with the target AP MLD. For details about the DS-STA-Notify Request, see the fourth request above.

[0222] Step 8010: The current AP MLD deletes the context of the non-AP MLD.

[0223] In one implementation, in step 806, when the non-AP MLD determines to trigger a path switch, it may also send a disassociation frame to the current AP MLD. For details about this disassociation frame, see the fifth request above. The current AP MLD may send a DS-STA-Notify request to the DS for deletion. The DS deletes the stored mapping between the non-AP MLD and the current AP MLD.

[0224] It should be noted that in the process of FIG8 , before roaming or handover, a first transmission link exists between the non-AP MLD and the current AP MLD. During roaming or handover, a second transmission link can be established between the non-AP MLD and the target AP MLD through transparent transmission of the DS and / or the current AP MLD. The second transmission link includes: non-AP MLD-target AP MLD. After the roaming or handover is completed, the non-AP MLD and the target AP MLD use the second transmission link for uplink and / or downlink data transmission. In one design, after step 8011, that is, after the target AP MLD sends a STA-AP mapping response frame to the non-AP MLD, the target AP MLD and the non-AP MLD use the second transmission link for uplink and / or downlink data transmission. The target AP MLD and the non-AP MLD use a second key negotiated between them to encrypt and decrypt uplink data and / or downlink data, and the corresponding data is transmitted over the second transmission link.

[0225] It should be noted that, in the previous description of this application, the solution of this embodiment 2 is introduced for single-radio non-AP MLDs and / or EMLSR-type non-AP MLDs. In one possible implementation, the solution of this embodiment 2 is not limited to applying only to these two types of non-AP MLDs. For example, the solution provided in this embodiment 2 can also be applied to non-AP MLDs that can simultaneously transmit and receive data with multiple AP MLDs, without limitation.

[0226] In the second embodiment, the non-AP MLD is not limited to being able to transmit and receive data with multiple AP MLDs simultaneously. This also applies to non-AP MLDs that can only transmit data with one AP MLD at a time. This further improves the roaming performance of non-AP MLDs, especially the roaming performance of single-radio non-AP MLDs and EMLSR non-AP MLDs.

[0227] [Example 3]

[0228] In the aforementioned first or second embodiment, the beacon measurement request sent by the current AP MLD to the non-AP MLD may include information indicating the link corresponding to the serving AP. In one implementation, upon receiving the beacon measurement request, the non-AP MLD may perform beacon measurement on each link of the non-AP. In one design, the non-AP MLD may report the link quality of all measured links to the current AP MLD. Alternatively, when obtaining the link quality of each link, the non-AP MLD compares the link quality of the current link with the link quality of the serving AP's link indicated in the beacon measurement request. Only when the link quality of the current link is greater than or equal to the link quality of the serving AP's link does the non-AP MLD report the link quality of that link to the current AP MLD; otherwise, the non-AP MLD does not report the link quality of the corresponding link. This design primarily considers the following: the non-AP MLD reports the link quality of the measured links to the current AP MLD, and the current AP MLD selects a target AP MLD that meets the requirements based on the link quality reported by the non-AP MLD. If the link quality of a link is lower than that of the serving AP's corresponding link, the link is considered to have poor quality and is not suitable as the target AP MLD for handover. In this case, the non-AP MLD does not need to report the beacon measurement results of the poor-quality link, thus reducing the overhead of reporting beacon measurement results.

[0229] In one implementation, the current AP MLD may send a radio measurement request frame to a non-AP MLD via a link. Upon receiving the radio measurement request frame, the non-AP MLD may perform corresponding measurements on the non-AP MLD's link and send a radio measurement report frame to the current AP MLD. The radio measurement report frame includes, among other things, the non-AP MLD's measurement results.

[0230] In one design, as shown in FIG10 , the radio measurement request frame includes at least one of the following fields: category, radio measurement action, dialog token, number of repetitions, or measurement request elements.

[0231] The category field may be used to indicate which category the corresponding wireless measurement request frame belongs to. For example, the wireless measurement request frame may be a frame related to wireless measurement or a frame related to roaming.

[0232] Wireless Measurement Action: This field can be used to indicate the type of wireless measurement request. For example, a wireless measurement action can indicate whether the corresponding frame is a request frame or a measurement frame. In the embodiment of the present application, the wireless measurement request frame shown in FIG10 is used to request a non-AP MLD to perform wireless measurements. In this case, the wireless measurement action indicates that the frame type is a request frame.

[0233] Dialog Token: Used to identify the correspondence between a request frame and a response frame. In one implementation, the response frame may also adopt the format shown in Figure 10. A pair of request and response frames carry the same dialog token value.

[0234] Repetition Count: Indicates the number of times the wireless measurement is repeated. For example, if the repetition count is set to 0, non-AP MLD measurements only need to be repeated once. Alternatively, if the repetition count is set to 65535, non-AP MLD measurements will be repeated until the measurement is canceled. This repetition count field is an implementation option; the frame format shown in Figure 10 may not include the repetition count field.

[0235] Measurement Request element: used to request beacon measurement or indicate the received signal strength indication (RSSI) of a channel. In one design, when the measurement request element instructs the non-AP MLD to perform RSSI measurement, the non-AP MLD may report the RSSI of the measured link to the current AP MLD. That is, in the first and second embodiments described above, in addition to requesting the non-AP MLD to perform beacon measurement, the current AP MLD may also request the non-AP MLD to report the RSSI of the measured link. Alternatively, when the measurement request element instructs the non-AP MLD to perform beacon measurement, the non-AP MLD may jump to the channel of the link to be measured and send a probe request. The current AP MLD responds with a probe response containing information about the corresponding link. The non-AP MLD determines the link quality of the corresponding link based on the received probe response. Alternatively, the non-AP MLD may directly listen for beacon frames on the link to be measured. The non-AP MLD determines the link quality of the corresponding link based on the listened beacon frames.

[0236] Furthermore, in the frame format of FIG10 , when the measurement request element instructs the non-AP MLD to perform beacon measurement, the frame in FIG10 may further include a beacon reporting subelement. In one implementation, the beacon reporting subfield includes a reporting condition field and / or a threshold / offset reference field. In one design, when the value of the reporting condition field is set to a first value, the first value includes, but is not limited to, 7, indicating that if the difference between the received signal-to-noise ratio (SNR) of the corresponding link measured by the non-AP MLD and the received signal-to-noise ratio (SNR) of the current serving AP is greater than or equal to the value in the threshold / offset reference field, the beacon measurement result is reported to the current AP MLD; otherwise, the beacon measurement result is no longer reported to the current AP.

[0237] In one design, in a multi-link scenario, the current AP MLD can send a beacon measurement request to the non-AP MLD through any of its affiliated APs that have a link with the non-AP MLD. In this case, the non-AP MLD may have ambiguity regarding the serving AP. In this case, the non-AP MLD cannot clearly determine which AP to use as the serving AP for the aforementioned received signal-to-noise ratio comparison. To address this issue, the following solution is proposed:

[0238] Solution 1: In the frame format shown in Figure 10, in addition to the reporting condition field and / or the threshold / offset reference field, a link ID field is also included, as shown in Figure 11. The link ID field can indicate the link corresponding to the serving AP. Furthermore, in addition to the link ID field, a reserved field is also included. This field can be called a link ID information field. The link ID field can occupy 4 bits, and the reserved field can occupy 4 bits. Alternatively, in the frame format shown in Figure 10, a multi-link operation (MLO) link information subelement is carried. As shown in Figure 11, this subelement includes: a field ID, a length, an extended field ID (element ID extension), and a link ID bitmap in bitmap form.

[0239] Solution 2: Limit the links on which the current AP MLD sends beacon measurement requests and specify that the AP corresponding to the link sending the beacon measurement request is the serving AP. In other words, for the non-AP MLD side, the AP corresponding to the link on which it receives the beacon measurement request is designated as the serving AP.

[0240] Through the above method, non-AP MLD can report beacon measurement results that meet the conditions, which can reduce reporting overhead compared to reporting beacon measurement results of all links.

[0241] It should be noted that in the embodiments of this application:

[0242] 1. Focus on describing the differences between different processes. The descriptions of different processes can refer to each other.

[0243] 2. In the processes of FIG3 , FIG5 , FIG7 a and FIG8 , there is no restriction on the order in which different steps are executed.

[0244] 3. The processes in FIG. 3 , FIG. 5 , FIG. 7 a and FIG. 8 may include more steps or fewer steps than those in the flowcharts or text descriptions, without limitation.

[0245] In the embodiments provided above, the methods provided in the embodiments of this application are described from the perspective of device interaction. To implement the methods provided in the embodiments of this application, the non-AP MLD, the current AP MLD, and the target AP MLD may include hardware structures and / or software modules, and the aforementioned functions may be implemented in the form of hardware structures, software modules, or a combination of hardware structures and software modules. Whether any of the aforementioned functions is implemented in the form of hardware structures, software modules, or a combination of hardware structures and software modules depends on the design constraints of the specific application of the technical solution.

[0246] Figures 12 and 13 are schematic diagrams of possible apparatuses provided in embodiments of the present application. These communication apparatuses can implement one or more corresponding functions in the aforementioned method embodiments. For example, functions implemented by the target AP MLD, the current AP MLD, or the non-AP MLD, thereby potentially achieving the beneficial effects of the aforementioned method embodiments.

[0247] As shown in FIG. 12 , the communication device 1200 includes a processing unit 1210 and a transceiver unit 1220 .

[0248] For example, the processing unit 1210 may also be referred to as a processor, a processing board, a processing module, a processing device, etc. The transceiver unit 1220 may also be referred to as a transceiver, a transceiver, a transceiver module, a transceiver device, a communication unit, etc. Furthermore, the transceiver unit 1220 may include at least one of a transmitting unit and a receiving unit. The transmitting unit and the receiving unit may be integrated together or two independent units.

[0249] In one design, the communication device 1200 is used to implement the functions of the target AP MLD in Figure 3. Specifically, the transceiver unit 1220 is used to receive first downlink data sent by the current AP MLD; the processing unit 1210 is used to encrypt the first downlink data using a second key to obtain second downlink data, where the second key is a key negotiated between the target AP MLD and a non-AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after the basic service set (BSS) is transferred; and the transceiver unit 1220 is further used to send the second downlink data to the non-AP MLD.

[0250] In one design, communication apparatus 1200 is configured to implement the functionality of the current AP MLD in FIG. 3 , specifically:

[0251] The transceiver unit 1220 is configured to receive third downlink data sent by the distributed system DS. The processing unit 1210 is configured to perform high-level media access control (MAC) layer processing on the third downlink data to obtain first downlink data, where the high-level MAC layer processing does not include encrypting the third downlink data. The transceiver unit 1220 is further configured to send the first downlink data to a target AP MLD, where the target AP MLD is the AP MLD of the non-AP MLD after the basic service set (BSS) is transferred.

[0252] In one design, the communication device 1200 is used to implement the functions of the non-AP MLD in Figure 3. Specifically, the transceiver unit 1220 is used to receive second downlink data sent by a target access point AP MLD, where the target AP MLD is the AP MLD of the non-AP MLD after the basic service set (BSS) is transferred; the processing unit 1210 is used to decrypt the second downlink data using a second key to obtain fourth downlink data, where the second key is a key negotiated between the target AP MLD and the non-AP MLD; the transceiver unit 1220 is further used to receive fifth downlink data sent by a current AP MLD; and the processing unit 1210 is further used to decrypt the fifth downlink data using a first key to obtain sixth downlink data, where the first key is a key negotiated between the current AP MLD and the non-AP MLD.

[0253] In one design, communication device 1200 is configured to implement the functionality of the target AP MLD in FIG. 5 , specifically:

[0254] The transceiver unit 1220 is configured to receive first uplink data sent by a non-access point non-AP MLD; the processing unit 1210 is configured to decrypt the first uplink data using a second key to obtain second uplink data, where the second key is a key negotiated between the target AP MLD and the non-AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred; the transceiver unit 1220 is configured to send the second uplink data to the current AP MLD.

[0255] In one design, communication apparatus 1200 is configured to implement the functionality of the current AP MLD in FIG. 5 , specifically:

[0256] The transceiver unit 1220 receives second uplink data sent by the target AP MLD, where the second uplink data is data decrypted using a second key. The second key is a key negotiated between the target AP MLD and the non-AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred. The processing unit 1210 is configured to perform high media access control (MAC) layer processing on the second uplink data to obtain third uplink data, where the high MAC layer processing does not include decryption of the second uplink data. The transceiver unit 1220 is configured to send the uplink data to the distributed system DS.

[0257] In one design, communication apparatus 1200 implements the functionality of non-AP MLD in FIG. 5 , specifically:

[0258] The processing unit 1210 is configured to encrypt the uplink data to be transmitted using a second key to obtain first uplink data, where the second key is a key negotiated between a target access point AP MLD and the non-AP MLD. The transceiver unit 1220 is configured to send the first uplink data to the target AP MLD. The processing unit 1210 is configured to encrypt the uplink data to be transmitted using the first key to obtain fourth uplink data, where the first key is a key negotiated between the current AP MLD and the non-AP MLD. The transceiver unit 1220 is configured to send the fourth uplink data to the current AP MLD, where the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred.

[0259] For a more detailed description of the processing unit 1210 and the transceiver unit 1220, reference may be made to the description of FIG3 or FIG5 in the above method embodiment, which will not be repeated here.

[0260] The division of units in the embodiments of the present application is schematic and is only a logical functional division. In actual implementation, there may be other division methods. In addition, the various functional units in the embodiments of the present application can be integrated into a physical device (for example, a processor), or each functional unit can be a separate physical device, or two or more units can be integrated into a single unit for implementation. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional modules.

[0261] Figure 13 shows another schematic diagram of the structure of a communication device 1300 provided in an embodiment of the present application. For example, the communication device 1300 shown in Figure 13 can be a hardware circuit implementation of the communication device 1200 shown in Figure 12. For ease of illustration, Figure 13 only shows the main parts of the communication device.

[0262] As shown in Figure 13, the communication device 1300 includes a processor 1310 and an interface circuit 1320. The processor 1310 and the interface circuit 1320 are coupled to each other.

[0263] For example, the processor 1310 may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor. The interface circuit 1320 may be a transceiver or input / output circuit, etc.

[0264] Optionally, the communication device 1300 may further include a memory 1330 for storing instructions executed by the processor 1310, or storing input data required by the processor 1310 to execute instructions, or storing data generated after the processor 1310 executes instructions. For example, instructions may also be referred to as computer programs, or computer program codes, etc.

[0265] For example, the memory 1330 can be a random access memory (RAM), a flash memory, a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium known in the art.

[0266] When the communication device 1300 is used to implement the target AP MLD, current AP MLD or non-AP MLD method in Figure 3 or Figure 5, the processor 1310 is used to implement the function of the processing unit 1210, and the interface circuit 1320 is used to implement the function of the transceiver unit 1220.

[0267] In one design, the interface circuit 1320 is configured to receive signals from a communication device other than the communication device 1300 and transmit the signals to the processor 1310, or to send signals from the processor 1310 to a communication device other than the communication device. The processor 1310 implements the functions of the target AP MLD, current AP MLD, or non-AP MLD in FIG. 3 or 5 through logic circuits or executing code instructions.

[0268] The present application also provides a communication device, which includes a processor and a memory, the processor and the memory being coupled, and the processor being configured to implement the functions of the target AP MLD, the current AP MLD, or the non-AP MLD in FIG3 or FIG5. For example, the processor may execute instructions in the memory so that the communication device implements one or more functions in the above-mentioned method embodiments, such as the target AP MLD, the current AP MLD, or the non-AP MLD in FIG3 or FIG5.

[0269] Implemented functions, etc. In one exemplary embodiment, a storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium may also be an integral part of the processor. The processor and storage medium may be located in an ASIC. Furthermore, the ASIC may be located in the target AP MLD, current AP MLD, or non-AP MLD in Figures 3 or 5. The processor and storage medium may also be located as discrete components in the target AP MLD, current AP MLD, or non-AP MLD in Figures 3 or 5.

[0270] The present application also provides a computer-readable storage medium storing instructions, which may also be referred to as a computer program, computer program code, etc. The instructions, when executed on a computer, cause the computer to perform the functions of the target AP MLD, current AP MLD, or non-AP MLD in FIG. 3 or FIG. 5 of the method embodiments described above.

[0271] Optionally, the computer may be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, or other programmable device. The computer program or instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired or wireless method. The computer-readable storage medium may be any available medium that can be accessed by a computer, or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; an optical medium, such as a digital video disc; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0272] Embodiments of the present application also provide a computer program product, including a computer program or instructions. When the computer program or instructions are executed on a computer, the method for determining the target AP MLD, current AP MLD, or non-AP MLD described in FIG. 3 or FIG. 5 is executed. For example, the computer program product includes one or more computer programs or instructions. When loaded and executed on a computer, the computer program or instructions fully or partially execute the process or functions described in FIG. 3 or FIG. 5 for determining the target AP MLD, current AP MLD, or non-AP MLD described in FIG. 3 or FIG. 5 .

[0273] The methods in the embodiments of the present application may be implemented in whole or in part by software, hardware, firmware, or any other combination. When implemented by software, they may be implemented in whole or in part in the form of a computer program product.

[0274] An embodiment of the present application further provides a chip, including a processor coupled to a memory, the processor being configured to execute a computer program or instruction stored in the memory, so that the chip implements the functions of the target AP MLD, current AP MLD, or non-AP MLD in FIG. 3 or FIG. 5 .

[0275] An embodiment of the present application further provides a communication system, comprising: a first communication device, a second communication device, and a third communication device.

[0276] The first communication device can implement the functionality of the target AP MLD described in FIG. 3 or FIG. 5 . The second communication device can implement the functionality of the current AP MLD described in FIG. 3 or FIG. 5 . The third communication device can implement the functionality of the non-AP MLD described in FIG. 3 or FIG. 5 . For the specific structures of the first, second, or third communication devices, refer to the descriptions above, such as the structural descriptions in FIG. 12 or FIG. 13 .

[0277] In the description of this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the previous and next associated objects are in an "or" relationship; "including at least one of A, B or C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B and C.

[0278] The various numbers used in the embodiments of this application are for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above processes does not necessarily indicate the order in which they are executed. The order in which the processes are executed should be determined by their functions and internal logic.

Claims

1. A communication method, characterized in that: include: The target access point AP multi-link device MLD receives the first downlink data sent by the current AP MLD; The target AP MLD encrypts the first downlink data using a second secret key to obtain second downlink data, The second key is a key negotiated between the target AP MLD and a non-AP MLD, and the target AP MLD is an AP MLD of the non-AP MLD after the basic service set BSS is transferred; The target AP MLD sends the second downlink data to the non-AP MLD.

2. A communication method, characterized in that: include: The target access point AP multi-link device MLD receives the first uplink data sent by the non-access point non-AP MLD; The target AP MLD decrypts the first uplink data using a second key to obtain second uplink data, where the second key is a key negotiated between the target AP MLD and the non-AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred; The target AP MLD sends the second uplink data to the current AP MLD.

3. The method according to claim 1 or 2, characterized in that There is a first transmission link between the non-AP MLD and the current AP MLD, and the method further includes: The target AP MLD receives a first request, where the first request is used to request to establish a second transmission link between the non-AP MLD and the target AP MLD; The target AP MLD establishes a second transmission link with the non-AP MLD.

4. The method according to claim 3, characterized in that The first request includes indication information for starting dual-link transmission of the non-AP MLD, and the dual-link includes the first transmission link and the second transmission link.

5. The method according to any one of claims 1 to 4, characterized in that Also includes: The target AP MLD sends a second request to the current AP MLD, where the second request is used to request to enable dual-link transmission of the non-AP MLD.

6. The method according to any one of claims 1 to 5, characterized in that Also includes: The target AP MLD receives a third request, where the third request is used to request triggering a path switch of the non-AP MLD; The target AP MLD sends a fourth request to the distributed system DS, wherein the fourth request is used to request the DS to update the stored mapping relationship between the non-AP MLD and the current AP MLD to: a mapping relationship between the non-AP MLD and the target AP MLD.

7. The method according to any one of claims 3 to 6, characterized in that The first request and / or the third request is sent by the non-AP MLD, and the first request and / or the third request is transmitted through the air interface between the non-AP MLD and the target AP MLD, or is transmitted through the current AP MLD and DS.

8. The method according to claim 7, characterized in that When the first request is transmitted through the current AP MLD and DS, the first request does not include operating channel information OCI.

9. The method according to any one of claims 6 to 8, characterized in that After the target AP MLD receives the third request and before the target AP MLD sends the fourth request to the DS, the method further includes: The target AP MLD sends a context transfer request to the current AP MLD; The target AP MLD receives a context transfer response sent by the current AP MLD, where the context transfer response includes the context information of the non-AP MLD.

10. The method according to claim 9, characterized in that The context transfer response also includes at least one of the following: a block determination protocol of a service identifier TID, a window start position of a send buffer area of ​​the TID, a window size of a send buffer area of ​​the TID, a window start position of an uplink receiving end scoreboard, a window size of the uplink receiving end scoreboard, a window start position of a receive reordering buffer area, a window size of the receive reordering buffer area, a maximum packet sequence number PN value currently received, or an uplink replay counter.

11. The method according to any one of claims 1 to 10, characterized in that After the transmission path of the non-AP MLD is switched from the first transmission path to the second transmission path, the non-AP MLD and the target AP MLD use a second key negotiated between the two to encrypt and decrypt uplink data and / or downlink data.

12. A communication method, characterized in that: include: The current access point AP multi-link device MLD receives the third downlink data sent by the distributed system DS; The current AP MLD performs high media access control MAC layer processing on the third downlink data to obtain first downlink data, wherein the high MAC layer processing does not include encrypting the third downlink data; The current AP MLD sends the first downlink data to a target AP MLD, where the target AP MLD is an AP MLD of a non-AP MLD after a basic service set BSS is transferred.

13. A communication method, characterized in that: include: The current access point AP multi-link device MLD receives second uplink data sent by the target AP MLD, where the second uplink data is data decrypted using a second key, where the second key is a key negotiated between the target AP MLD and the non-access point non-AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred; The current AP MLD performs high media access control MAC layer processing on the second uplink data to obtain third uplink data, wherein the high MAC layer processing does not include decrypting the second uplink data; The current AP MLD sends the uplink data to the distributed system DS.

14. The method according to claim 12, characterized in that The processing of the high MAC layer includes: repeated detection of the uplink data packet.

15. The method according to any one of claims 12 to 14, characterized in that There is a first transmission link between the current AP MLD and the non-AP MLD, further comprising: The current AP MLD receives a second request sent by the target AP MLD, where the second request is used to request to enable dual-link transmission of the non-AP MLD, where the dual link includes the first transmission link and a second transmission link between the non-AP MLD and the target AP MLD.

16. The method according to any one of claims 12 to 15, characterized in that Also includes: The current AP MLD receives a fifth request sent by the non-AP MLD, where the fifth request is used to request to disconnect a first transmission link between the non-AP MLD and the current AP MLD, and the fifth request includes first indication information, where the first indication information instructs the current AP MLD to retain block acknowledgment BA information and / or context information of the non-AP MLD and cache data not sent by the non-AP MLD; The current AP MLD sends a sixth request to the DS, where the sixth request is used to request deletion of a mapping relationship between the non-AP MLD and the current AP MLD stored in the DS.

17. The method according to any one of claims 12 to 16, characterized in that Also includes: The current AP MLD receives a context transfer request sent by the target AP MLD; The current AP MLD sends a context transfer response to the target AP MLD, where the context transfer response includes the context information of the non-AP MLD.

18. The method according to claim 17, characterized in that The context transfer response further includes at least one of the following: a block determination protocol of a service identifier TID, a window start position of a send buffer area of ​​the TID, a window size of the send buffer area of ​​the TID, a window start position of an uplink receiving end scoreboard, a window size of the uplink receiving end scoreboard, a window start position of a receive reordering buffer area, a window size of the receive reordering buffer area, a maximum packet sequence number PN value currently received, or an uplink replay counter.

19. The method according to any one of claims 12 to 18, characterized in that Also includes: The current AP MLD sends a beacon measurement request to the non-AP MLD, where the beacon measurement request includes indication information of a corresponding link of the serving AP.

20. The method according to any one of claims 12 to 19, characterized in that Also includes: The current AP MLD sends a seventh request to the non-AP MLD, wherein the seventh request includes second indication information, and the second indication information instructs the non-AP MLD to retain the BA information and / or context information of the non-AP MLD and cache the data not sent by the non-AP MLD.

21. A communication method, characterized in that: include: The non-access point non-AP multi-link device MLD receives the second downlink data sent by the target access point AP MLD, where the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred; The non-AP MLD decrypts the second downlink data using a second key to obtain fourth downlink data, where the second key is a key negotiated between the target AP MLD and the non-AP MLD; The non-AP MLD receives the fifth downlink data sent by the current AP MLD; The non-AP MLD decrypts the fifth downlink data by using a first key to obtain sixth downlink data, where the first key is a key negotiated between the current AP MLD and the non-AP MLD.

22. A communication method, characterized in that: include: The non-AP multi-link device MLD uses a second key to encrypt the uplink data to be transmitted to obtain first uplink data, where the second key is a key negotiated between the target access point AP MLD and the non-AP MLD; The non-AP MLD sends the first uplink data to the target AP MLD; The non-AP MLD encrypts the uplink data to be transmitted by using the first key to obtain fourth uplink data, where the first key is a key negotiated between the current AP MLD and the non-AP MLD; The non-AP MLD sends the fourth uplink data to the current AP MLD, and the target AP MLD is the AP MLD of the non-AP MLD after the basic service set BSS is transferred.

23. The method according to claim 21 or 22, characterized in that There is a first transmission link between the non-AP MLD and the current AP MLD, further comprising: The non-AP MLD sends a first request, where the first request is used to request to establish a second transmission link between the non-AP MLD and the target AP MLD.

24. The method of claim 23, wherein: The first request includes indication information for starting dual-link transmission of the non-AP MLD, and the dual-link includes the first transmission link and the second transmission link.

25. The method according to any one of claims 21 to 24, characterized in that Also includes: The non-AP MLD sends a third request, where the third request is used to request triggering of path switching of the non-AP MLD.

26. The method according to any one of claims 23 to 25, characterized in that The first request and / or the third request is sent to the target AP MLD, and the first request and / or the third request is transmitted through the air interface between the non-AP MLD and the target AP MLD, or transmitted through the current AP MLD and the distributed system DS.

27. The method of claim 26, wherein: When the first request is transmitted through the current AP MLD and DS, the first request does not include operating channel information OCI.

28. The method according to any one of claims 21 to 27, characterized in that Also includes: The non-AP MLD sends a fifth request to the current AP MLD, wherein the fifth request includes first indication information, and the first indication information instructs the current AP MLD to retain the block acknowledgment BA information and / or context information of the non-AP MLD and cache the data not sent by the non-AP MLD.

29. The method according to any one of claims 21 to 28, characterized in that Also includes: The non-AP MLD receives the beacon measurement request sent by the current AP MLD, where the beacon measurement request includes indication information of a link corresponding to the serving AP.

30. The method according to any one of claims 21 to 29, characterized in that Also includes: The non-AP MLD receives a seventh request sent by the current AP MLD, where the seventh request includes second indication information, and the second indication information instructs the non-AP MLD to retain the BA information and / or context information of the non-AP MLD and cache data not sent by the non-AP MLD.

31. The method according to any one of claims 21 to 30, characterized in that After the transmission path of the non-AP MLD is switched from the first transmission path to the second transmission path, the non-AP MLD and the target AP MLD use a second key negotiated between the two to encrypt and decrypt uplink data and / or downlink data.

32. A communication device, characterized in that: The method comprises a unit for implementing the method described in any one of claims 1 to 11, or a unit for implementing the method described in any one of claims 12 to 20, or a unit for implementing the method described in any one of claims 21 to 31.

33. A communication device, characterized in that: include: A memory for storing program instructions; A processor, configured to execute the program instructions so that the communication device performs the method according to any one of claims 1 to 11, or the method according to any one of claims 12 to 20, or the method according to any one of claims 21 to 31.

34. A device, characterized in that The invention comprises a processor and an interface circuit, wherein the interface circuit is used to receive a signal from another device outside the device and transmit it to the processor or send a signal from the processor to another device outside the device, and the processor enables the device to implement the method as described in any one of claims 1 to 11, or the method as described in any one of claims 12 to 20, or the method as described in any one of claims 21 to 31 through a logic circuit or executing code instructions.

35. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, which are executed on a computer to cause the computer to execute the method of any one of claims 1 to 11, or the method of any one of claims 12 to 20, or the method of any one of claims 21 to 31.

36. A computer program product, characterized in that The method comprises a computer program or an instruction, which, when executed by a device, causes the method described in any one of claims 1 to 11 to be executed, or the method described in any one of claims 12 to 20 to be executed, or the method described in any one of claims 21 to 31 to be executed.

37. A chip, characterized in that: The invention comprises a processor, wherein the processor is coupled to a memory and is used to execute a computer program or instruction stored in the memory, so that a communication device including the chip executes the method described in any one of claims 1 to 11, or executes the method described in any one of claims 12 to 20, or executes the method described in any one of claims 21 to 31.

38. A communication system, characterized in that: include: A first communication device, the first communication device being configured to perform the method according to any one of claims 1 to 11; A second communication device, the second communication device being configured to perform the method according to any one of claims 12 to 20; A third communication device, wherein the second communication device is configured to execute the method according to any one of claims 21 to 31.

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